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Estrogens act through nuclear and membrane-initiated signaling. Estrogen receptor alpha (ERα) is critical for reproduction, but the relative contribution of its nuclear and membrane signaling to the central regulation of reproduction is unclear. To address this question, two complementary approaches were used: estetrol (E 4 ) a natural estrogen acting as an agonist of nuclear ERs, but as an antagonist of their membrane fraction, and the C451A-ERα mouse lacking mERα. E 4 dose- dependently blocks ovulation in female rats, but the central mechanism underlying this effect is unknown. To determine whether E 4 acts centrally to control ovulation, its effect was tested on the positive feedback of estradiol (E 2 ) on neural circuits underlying luteinizing hormone (LH) secretion. In ovariectomized females chronically exposed to a low dose of E 2 , estradiol benzoate (EB) alone or combined with progesterone (P) induced an increase in the number of kisspeptin (Kp) and gonadotropin-releasing hormone (GnRH) neurons coexpressing Fos, a marker of neuronal activation. E 4 blocked these effects of EB, but not when combined to P. These results indicate that E 4 blocked the central induction of the positive feedback in the absence of P, suggesting an antagonistic effect of E 4 on mERα in the brain as shown in peripheral tissues. In parallel, as opposed to wild-type females, C451A-ERα females did not show the activation of Kp and GnRH neurons in response to EB unless they are treated with P. Together these effects support a role for membrane-initiated estrogen signaling in the activation of the circuit mediating the LH surge., Competing Interests: The authors declare no competing financial interests., (Copyright © 2024 Faure et al.)

Kisspeptins are essential regulators of the reproductive axis, with capacity to potently activate gonadotropin-releasing hormone neurons, acting also as central conduits for the metabolic regulation of fertility. Recent evidence suggests that kisspeptins per se may also modulate several metabolic parameters, including body weight, food intake or energy expenditure, but their actual roles and site(s) of action remain unclear. We present herein a series of studies addressing the metabolic effects of central and peripheral administration of kisspeptin-10 (Kp-10; 1 nmol and 3 nmol daily, respectively) for 11 days in mice of both sexes. To assess direct metabolic actions of Kp-10 versus those derived indirectly from its capacity to modulate gonadal hormone secretion, kisspeptin effects were tested in adult male and female mice gonadectomized and supplemented with fixed, physiological doses of testosterone or 17β-estradiol, respectively. Central administration of Kp-10 decreased food intake in male mice, especially during the dark phase (~50%), which was accompanied by a reduction in total and nocturnal energy expenditure (~16%) and locomotor activity (~70%). In contrast, opposite patterns were detected in female mice, with an increase in total and nocturnal locomotor activity (>65%), despite no changes in food intake or energy expenditure. These changes were independent of body weight, as no differences were detected in mice of both sexes at the end of Kp-10 treatments. Peripheral administration of Kp-10 failed to alter any of the metabolic parameters analyzed, except for a decrease in locomotor activity in male mice and a subtle increase in 24 h food intake in female mice, denoting a predominant central role of kisspeptins in the control of energy metabolism. Finally, glucose tolerance and insulin sensitivity were not significantly affected by central or peripheral treatment with Kp-10. In conclusion, our data reveal a potential role of kisspeptins in the control of key metabolic parameters, including food intake, energy expenditure and locomotor activity, with a preferential action at central level, which is sex steroid-independent but sexually dimorphic., (© 2024 The Author(s). Journal of Neuroendocrinology published by John Wiley & Sons Ltd on behalf of British Society for Neuroendocrinology.)

This study explored the alteration in kisspeptin and reproductive hormones during different superovulation protocols (SOP) in dromedary camel. The kisspeptin and reproductive hormonal profile, ovarian response, and the quality and quantity of embryos in dromedary camel donors were evaluated. A total of thirty donor camels were divided into two groups: the 5dSOP group, which received diluent containing 400 mg pFSH dissolved in 20 ml and administered two times daily for 5 days at decreasing doses (2.5, 2, 1.5, and 1 ml); and the 3dSOP group, which received diluent containing 400 mg pFSH dissolved in 12 ml and administered two times daily for 3 days at decreasing doses (3 ml, 2 ml, and 1 ml). Ultrasonography was used to monitor the ovarian environment, recording daily follicle count and dimensions and the time taken for follicles to mature. On the sixth day after mating, a corpus luteum (CL) count was conducted. On the 8th day after mating, records of the quantity and quality of embryos collected were kept. Blood samples from the jugular vein were collected at the commencement of the superovulation protocol and at 8:00 a.m. for the following 48 h to measure the concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), kisspeptin (KP), and progesterone (P4). The findings indicated that the 3dSOP yielded superior results compared to the 5dSOP in terms of follicle quantity and size, as well as the quantity of CL and embryos. This improvement was attributed to significantly higher concentrations of reproductive hormones, including FSH, LH, E2, kisspeptin, and P4 (P ≤ 0.05), in the 3dSOP than in the 5dSOP. In conclusion, reducing the duration of superovulation protocols contributed to the proliferation of follicles with improved dimensions and counts, ultimately resulting in a greater quantity of embryos of superior quality. The levels of FSH, LH, E2, KP, and P4 were affected significantly by SOP and time of evaluation., Competing Interests: Declaration of competing interest No competing interests exist., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The neuropeptide kisspeptin (Kiss) is crucial in regulating the hypothalamic-pituitary-gonadal axis. It is produced by two main groups of neurons in the hypothalamus: the rostral periventricular region around the third ventricle and the arcuate nucleus. Kiss is the peptide product of the KiSS-1 gene and serves as the endogenous agonist for the GPR54 receptor. The Kiss/GPR54 system functions as a critical regulator of the reproductive system. Thus, we examined the effect of intracerebroventricular administration of 3 μg of Kiss to the right lateral ventricle of ovariectomized rats primed with a dose of 5 μg subcutaneous (sc) of estradiol benzoate (EB). Kiss treatment increased the lordosis quotient at all times tested. However, the lordosis reflex score was comparatively lower yet still significant compared to the control group. To investigate receptor specificity and downstream mechanisms on lordosis, we infused 10 μg of GPR54 receptor antagonist, Kiss-234, 5 μg of the progestin receptor antagonist, RU486, or 3 μg of antide, a gonadotropin-releasing hormone-1 (GnRH-1) receptor antagonist, to the right lateral ventricle 30 min before an infusion of 3 μg of Kiss. Results demonstrated a significant reduction in the facilitation of lordosis behavior by Kiss at 60 and 120 min when Kiss-234, RU486, or antide were administered. These findings suggest that Kiss stimulates lordosis expression by activating GPR54 receptors on GnRH neurons and that Kiss/GPR54 system is an essential intermediary by which progesterone activates GnRH., (Copyright © 2024. Published by Elsevier Inc.)

Kisspeptin, a key neuropeptide derived from the KISS1R gene, is renowned for its critical role in regulating the hypothalamic-pituitary-gonadal axis and reproductive hormone secretion. Beyond its primary function in reproductive biology, emerging research has illuminated its influence in various cancers, mediating significant effects through its interaction with the G protein-coupled receptor, kisspeptin receptor. This interaction has been implicated in modulating cellular processes such as proliferation and metastasis, making it a potential target for therapeutic intervention. Our study initially screened ten kisspeptin-10 analogs through cytotoxic effects of kisspeptin-10 (KP10) and its analogs in several cancer types, including cervical, prostate, breast, and gastric cancers, with a particular focus on cervical cancer, where the most profound effects were observed. Further exploration using kinase array assays revealed that these analogs specifically alter key kinases involved in cancer progression. Migration assays demonstrated a substantial decrease in cell motility, and Bioluminescence Resonance Energy Transfer assays confirmed these analogs' strong interactions with the kisspeptin receptor. Overall, our results indicate that these KP10 analogs not only hinder cervical cancer cell proliferation but also curtail migration through targeted modulation of kinase signaling, suggesting their potential as therapeutic agents in managing cervical cancer progression. This comprehensive approach underscores the therapeutic promise of exploiting kisspeptin signaling in cancer treatment strategies.

Kisspeptin is a peptide that plays an important role through its effects on the hypothalamus-pituitary-gonadal (HPG) axis. It has also been implicated in sexual behavior. The present study investigated whether the relationship between kisspeptin and sexual behavior is independent of the HPG axis, i.e., testosterone. Sexual behavior was examined after the administration of kisspeptin to gonadally intact male rats and gonadectomized male rats that received testosterone supplementation. Other male rats were also observed for sexual behavior once a week from 2 to 5 weeks after gonadectomy and receiving kisspeptin for the sixth postoperative week. Sexual behavior in female rats serving as the partner for each male was also observed. Female rats were not administered kisspeptin in the present study. The results obtained showed that the administration of kisspeptin increased precopulatory behavior in gonadally intact male rats and gonadectomized male rats that received testosterone supplementation and proceptive behavior in their female partners. Precopulatory behavior in males and receptive behavior in females increased, while copulatory behavior in males and receptive behavior in females remained unchanged. Furthermore, the administration of kisspeptin increased precopulatory behavior in gonadectomized males, but did not affect receptive behavior in females. These results suggest that kisspeptin affected males independently and/or supplementally to testosterone, and also that changes in the presence of testosterone in males had an impact on proceptive behavior in their female partners. In conclusion, kisspeptin may involve an as-yet-unidentified neural pathway in sexual desire independently of the HPG axis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Parkinson's Disease is a progressive neurodegenerative disorder characterized by motor symptoms resulting from the loss of nigrostriatal dopaminergic neurons. Kisspeptins (KPs) are a family of neuropeptides that are encoded by the Kiss-1 gene, which exert their physiological effects through interaction with the GPR54 receptor. In the current investigation, we investigated the prospective protective effects of central KP-54 treatments on nigrostriatal dopaminergic neurons and consequent motor performance correlates in 6-hydroxydopamine (6-OHDA)-lesioned rats. Male adult Sprague Dawley rats underwent stereotaxic injection of 6-OHDA into the right medial forebrain bundle to induce hemiparkinsonism. Following surgery, rats received chronic central treatments of nasal or intracerebroventricular KP-54 (logarithmically increasing doses) for seven consecutive days. Motor performance was evaluated seven days post-surgery utilizing the open field test and catalepsy test. The levels of dopamine in the striatum were determined with mass spectrometry. Immunohistochemical analysis was conducted to assess the immunoreactivities of tyrosine hydroxylase (TH) and the GPR54 in the substantia nigra. The dose-response curve revealed a median effective dose value of ≈3 nmol/kg for both central injections. Due to its non-invasive and effective nature, nasal administration was utilized in the second phase of our study. Chronic administration of KP-54 (3nmol/kg, nasally) significantly protected 6-OHDA-induced motor deficits. Nasal KP-54 attenuated the loss of nigrostriatal dopaminergic neurons induced by 6-OHDA. Additionally, significant correlations were observed between motor performance and nigrostriatal dopamine levels. Immunohistochemical analysis demonstrated the localization of the GPR54 within TH-positive nigral cells. These findings suggest the potential efficacy of central KP-54 on motor impairments in hemiparkinsonism., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This study evaluated whether the treatment of pseudopregnancy in bitches with vitamin B6 modulates uterine expression of receptors for progesterone (PR), oestrogen (ERα), androgen (AR), thyroid hormone (TRα) and the kisspeptin/Kiss1r system. Eighteen pseudopregnant bitches were treated for 20 days in groups receiving placebo (n = 6); cabergoline (5 μg/kg/day; n = 6); or vitamin B6 (50 mg/kg/day; n = 6). Blood was collected on the 1st day of drug administration and 120 h later to measure serum prolactin (PRL). After treatment, they were ovariohysterectomized and uterine fragments were collected for histomorphometry and immunohistochemical evaluation of PR, ERα, AR, TRα, Kiss1 and Kiss1r. After 120 h of cabergoline or vitamin B6 treatment, PRL levels were reduced in the bitches, confirming the antiprolactinemic effect of these drugs. Furthermore, regardless of treatment, the animals exhibited uterine histomorphometry consistent with dioestrus. The PR showed strong immunostaining in all regions and an increase in scores was observed for this receptor in animals treated with vitamin B6 in deep glands. In contrast, ERα and Kiss1R receptors showed weak to no immunostaining in all uterine regions and no changes between groups. Regarding AR, most animals treated with vitamin B6 showed increased trends in the deep gland and myometrium marking scores. In contrast, in both vitamin B6 and cabergoline treatments, a reduction in TRα marking scores was observed compared to the control group. In addition, on the endometrial surface, a reduction was observed in the marked area of Kiss1 after administration of cabergoline when compared to the pseudopregnant control group. These findings shed valuable insight into the use of vitamin B6 as a drug with actions similar to cabergoline in reducing PRL and uterine modulation in bitches., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Kisspeptin is a multifunctional neurohormone, primarily involved in the regulation of reproduction. We tested whether peripheral administration of kisspeptin10 (KP-10) via intraperitoneal injection or slow release affects reproductive hormones and metabolites in Sterlet sturgeon (Acipenser ruthenus). Plasma and mucus 17β-estradiol (E 2 ), and testosterone (T), plasma and follicular vitellogenin (VTG) and calcium (Ca) as well as glucose and lipids were determined. Mature Sterlet sturgeon were grouped into six groups: saline i.p injection (control), human kisspeptin (hKP-10) i.p injection; acipenser kisspeptin (aKP-10) i.p injection; hKP-10 (slow release); aKP-10 (slow-release) and no treatment control. No effect for KP-10 on sturgeon body weight was found after 4 weeks of treatment. Multivariate analysis revealed a significant disparity in plasma E 2 levels. It was significantly different between groups (time, P = 0.0022). E 2 in epithelia mucosa showed significant difference between and within groups in the acute group (time, P = 0.0252; treatment, P = 0.0423; time × treatment, P = 0.0429). T levels were unaffected by treatments (P > 0.05). The presence of synthetic aKP-10 led to an elevation in oocyte and plasma VTG levels (P < 0.05). Prolonged exposure to this peptide resulted in an increase in plasma calcium levels. Simultaneously, there was an augmentation in the number of mature follicles. Regardless of the duration of exposure, aKP-10 significantly elevated plasma glucose levels in Sterlet (P < 0.0). Additionally, KP-10 led to an increase in plasma lipids and cholesterol in Sterlet. Overall, our data support an involvement for KP-10 in the regulation of gonadal steroid hormones, oocyte maturation and metabolite levels in sturgeon, suggesting a positive role for this peptide in the reproductive physiology of this species., Competing Interests: Declaration of competing interest None., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The effect of a synthetic analog of kisspeptin 1, a peptide involved in the regulation of the hypothalamicpituitary- gonadal (HPG) stress axis, on the cortisol level of Danio rerio fish was investigated. Kisspeptin 1 was administered at doses of 2 μg/kg and 8 μg/kg followed by resting for 1 h and 4 h. We found that kisspeptin at doses of 2 μg/kg and 8 μg/kg increased cortisol levels, with a significant spike in cortisol levels at 1 h post-injection.

Epigenetic alterations my play a role in the aggressive behavior of Non-Small Cell Lung Cancer (NSCLC). Treatment with the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA, vorinostat) has been reported to interfere with the proliferative and invasive potential of NSCLC cells. In addition, the DNA methyltransferase inhibitor azacytidine (AZA, vidaza) can modulate the levels of the metastasis suppressor KiSS-1. Thus, since cisplatin is still clinically available for NSCLC therapy, the aim of this study was to evaluate drug combinations between cisplatin and SAHA as well as AZA using cisplatin-sensitive H460 and -resistant H460/Pt NSCLC cells in relation to KiSS-1 modulation. An analysis of drug interaction according to the Combination-Index values indicated a more marked synergistic effect when the exposure to SAHA or AZA preceded cisplatin treatment with respect to a simultaneous schedule. A modulation of proteins involved in apoptosis (p53, Bax) was found in both sensitive and resistant cells, and compared to the treatment with epigenetic agents alone, the combination of cisplatin and SAHA or AZA increased apoptosis induction. The epigenetic treatments, both as single agents and in combination, increased the release of KiSS-1. Finally, the exposure of cisplatin-sensitive and -resistant cells to the kisspeptin KP10 enhanced cisplatin induced cell death. The efficacy of the combination of SAHA and cisplatin was tested in vivo after subcutaneous inoculum of parental and resistant cells in immunodeficient mice. A significant tumor volume inhibition was found when mice bearing advanced tumors were treated with the combination of SAHA and cisplatin according to the best schedule identified in cellular studies. These results, together with the available literature, support that epigenetic drugs are amenable for the combination treatment of NSCLC, including patients bearing cisplatin-resistant tumors.

The presence of Kisspeptin (Kp) and its receptors in the corpus luteum (CL) of buffalo has recently been demonstrated. In this study, we investigated the role of Kp in the modulation of progesterone (P 4 ) synthesis in vitro. The primary culture of bubaline luteal cells (LCs) was treated with 10, 50, and 100 nM of Kp and Kp antagonist (KpA) alongside a vehicle control. The combined effect of Kp and KpA was assessed at 100 nM concentration. Intracellular response to Kp treatment in the LCs was assessed by examining transcript profiles (LHR, STAR, CYP11A1, HSD3B1, and ERK1/2) using quantitative polymerase chain reaction (qPCR). In addition, the immunolocalization of ERK1/2 and phosphorylated ERK1/2 (p-ERK1/2) in the LCs was studied using immunocytochemistry. Accumulation of P 4 from the culture supernatant was determined using enzyme-linked immunosorbent assay (ELISA). The results indicated that LCs had a greater p-ERK1/2 expression in the Kp treatment groups. A significant increase in the P 4 concentration was recorded at 50 nM and 100 nM Kp, while KpA did not affect the basal concentration of P 4 . However, the addition of KpA to the Kp-treated group at 100 nM concentration suppressed the Kp-induced P 4 accumulation into a concentration similar to the control. There was significant upregulation of ERK1/2 and CYP11A1 expressions in the Kp-treated LCs at 100 nM (18.1 and 37fold, respectively, p < 0.01). However, the addition of KpA to Kp-treated LCs modulated ERK1/2, LHR, STAR, CYP11A1, and HSD3B1 at 100 nM concentration. It can be concluded that Kp at 100 nM stimulated P 4 production, while the addition of KpA suppressed Kp-induced P 4 production in the buffalo LCs culture. Furthermore, an increment in p-ERK1/2 expression in the LCs indicated activation of the Kp signaling pathway was associated with luteal steroidogenesis., Competing Interests: Declaration of competing interest The authors do not have any conflict of interest to declare., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Scope: The disturbance of the hypothalamic-pituitary-gonadal (HPG) axis, gut microbiota (GM) community, and short-chain fatty acids (SCFAs) is a triggering factor for pubertal onset. The study investigates the effects of the long-term intake of aspartame on puberty and GM in animals and humans., Methods and Results: Aspartame-fed female offspring rats result in vaginal opening time prolongation, serum estrogen reduction, and serum luteinizing hormone elevation. , 60 mg kg -1 aspartame treatment decreases the mRNA levels of gonadotropin-releasing hormone (GnRH), Kiss1, and G protein-coupled receptor 54 (GPR54), increases the mRNA level of RFamide-related peptide-3 (RFRP-3), and decreases the expression of GnRH neurons in the hypothalamus. Significant differences in relative bacterial abundance at the genus levels and decreased fecal SCFA levels are noted by 60 mg kg -1 aspartame treatment. Among which, Escherichia-Shigella is negatively correlated with several SCFAs. In girls, high-dose aspartame consumption decreases the risk of precocious puberty., Conclusions: Aspartame reduces the chance of puberty occurring earlier than usual in female offspring and girls. Particularly, 60 mg kg -1 aspartame-fed female offspring delays pubertal onset through the dysregulation of HPG axis and GM composition by inhibiting the Kiss1/GPR54 system and inducing the RFRP-3. An acceptable dose of aspartame should be recommended during childhood., (© 2024 Wiley‐VCH GmbH.)

The present study was conducted to elucidate (1) the influence of kisspeptin (KP) on the in vitro development of preantral follicles (PFs) and (2) evolution of KP receptor gene ( KISS1R ) expression during ovarian follicular development in sheep. Kisspeptin was supplemented (0-100 µg/ml) in the culture medium of PFs for 6 days. The cumulus-oocyte complexes (COCs) from cultured PFs were subsequently matured to metaphase II (MII) for an additional 24 h. The proportions of PFs exhibiting growth, antrum formation, average increase in diameter, and maturation of oocytes to MII stage were the indicators of follicular development in vitro . The expression of the kisspeptin receptor gene at each development stages of in vivo developed (preantral, early antral, antral, large antral and COCs from Graafian follicles) and in vitro cultured PFs supplemented with KP was assessed using a real-time polymerase chain reaction. The best development in all the parameters under study was elicited with 10 µg/ml of KP. Supplementation of KP (10 µg/ml) in a medium containing other growth factors (insulin-like growth factor-I) and hormones (growth hormone, thyroxine, follicle-stimulating hormone) resulted in better PF development. The KISS1R gene was expressed in follicular cells and oocytes at all the development stages of both in vivo developed and in vitro cultured follicles. Higher KISS1R gene expression was supported by culture medium containing KP along with other hormones and growth factors. Accordingly, it is suggested that one of the mechanisms through which KP and other growth factors and hormones influence the ovarian follicular development in mammals is through the upregulation of expression of the KP receptor gene.

At this time, with advances in medical science, many cancers and chronic diseases are treatable, but one of their side effects is infertility. Some women also want to delay pregnancy for personal reasons. There has been some evidence that kisspeptin activates broad signals by binding to its receptor, suggesting that the role of kisspeptin in direct control of ovarian function includes follicle growth and steroid production. In this study, the effect of kisspeptin on improving the quality and results for human ovarian follicles was investigated. A section of ovary was removed laparoscopically from women between 20 and 35 years of age ( n = 12). Pieces were divided randomly into two groups, control and treatment (with 1 μM kisspeptin). Real-time PCR was performed for GDF9 , BMP15 and mTOR gene expression assessments. Western blotting was carried out to measure AKT and FOXO3a protein expression. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey's test; means were considered significantly different at a P -value < 0.05. During treatment with the kisspeptin group, maturity genes are expressed. Therefore, kisspeptin is an effective substance to improve the quality of the human ovarian medium as it increases the maturity of follicles.

Kisspeptin is an important hormone involved in the stimulation of the hypothalamo-pituitary gonadal (HPG) axis. The HPG axis can be suppressed in certain conditions such as stress, which gives rise to the activation of the hypothalamo-pituitary-adrenal (HPA) axis. However, the physiological role of kisspeptin in the interaction of HPG and HPA axis is not fully understood yet. This study was conducted to investigate the possible effects of central kisspeptin injection on HPG axis as well as HPA axis activity. Adult male Wistar rats were randomly divided into seven groups as followed: sham (control), kisspeptin (50 pmol), P234 (1 nmol), kisspeptin + p234, kisspeptin + antalarmin (0.1 μg), kisspeptin + astressin 2B (1 μg), and kisspeptin + atosiban (300 ng/rat) ( n  = 10 each group). At the end of the experiments, the hypothalamus, pituitary, and serum samples of the rats were collected. There was no significant difference in corticotropic-releasing hormone immunoreactivity in the paraventricular nucleus of the hypothalamus, serum adrenocorticotropic hormone, and corticosterone levels among all groups. Moreover, no significant difference was detected in pituitary oxytocin level. Serum follicle-stimulating hormone and luteinizing hormone levels of the kisspeptin, kisspeptin + antalarmin, and kisspeptin + astressin 2B groups were significantly higher than the control group. Serum testosterone levels were significantly higher in the kisspeptin kisspeptin + antalarmin, kisspeptin + astressin 2B, and kisspeptin + atosiban groups compared to the control group. Our findings suggest that central kisspeptin injection causes activation in the HPG axis, but not the HPA axis in male rats.

Objective: To elucidate the mechanism of the nourishing Yin and purging fire Chinese herbal mixture (NYPF) in delaying light-induced premature puberty in rats., Methods: Twenty-one days old female Sprague-Dawley rats were randomly assigned to normal group (N), long light exposure group (L), NYPF and normal saline group (NS). Rats in the L, NYPF and NS groups were exposed to 16 h: 350 lux light/8 h: dark, while rats in the N group were exposed to 12 h: 50 lux light/12 h: dark. NYPF and normal saline was administered to the rats in the NYPF group or NS group, respectively, from day 21. Five rats in every group were sacrificed at 9 p.m. on day 28 (P28), on the day when rat's vulva opened in the L group (L-VO), on the day when the first estrous interphase occurred in rats of L group (L-E1), and on the day when the second estrous interphase occurred in rats of L group (L-E2), respectively., Resulits: On day 34, all rats in the L group, 80% of rats in the NS group, 40% of rats in the N group, and 20% of rats in the NYPF group showed complete opening of the vulva. At P28, mRNA level of hypothalamic kisspeptin (Kiss-1) in the L group was significantly higher than that in the N group ( P < 0.05). The rats in the L and NS groups had significantly lower hypothalamic arginine-phenylalanine-amide (RFamide)-related peptide 3 (RFRP-3) mRNA levels than those in the N group ( P < 0.05), whereas RFRP-3 mRNA level was significantly higher in the NYPF group than that in the L group ( P < 0.05). At L-VO, the ovarian index of the L and NS groups was significantly higher than that of the N group ( P < 0.05) and estradiol (E2) level of the NYPF group was significantly lower than that of the N and NS groups ( P < 0.05); hypothalamic Kiss-1 mRNA level in the L and NS groups was significantly higher than that in the N and NYPF groups ( P < 0.05), whereas hypothalamic RFRP-3 mRNA level in the L, NYPF, and NS groups was significantly lower than that in the N group ( P < 0.05). At L-E1, E2 level of the L and NS groups was significantly higher than that of the N group ( P < 0.01), whereas it was significantly lower in the NYPF group than that of the N, L, and NS groups ( P < 0.01), and serum luteinizing hormone level of the L and NS groups was significantly higher than that of the N group ( P < 0.05); levels of serum melatonin and ovarian melatonin receptor 1 (MT-1) mRNA in the L, NYPF, and NS groups were significantly lower than those in the N group ( P < 0.05). At L-E2, the uterine organ index of the NYPF group was significantly lower than that of the L group ( P < 0.05); and ovarian MT-1 mRNA level of the L and NS groups was significantly lower than that in the N group ( P < 0.05)., Conclusions: NYPF can delay puberty onset in rats exposed to strong light for a prolonged duration, and regulation of the gene expression of Kiss-1 and RFRP-3 in the hypothalamus has been suggested as one of the mechanisms.

This study evaluated the effects of Cl 3 BPA on kisspeptin-G-protein coupled receptor 54 (GPR54)/gonadotropin-releasing hormone (GnRH) (KGG) signals and analyzed the roles of estrogen receptor alpha (ERɑ) and G-protein coupled estrogen receptor 1 (GPER1) in regulating KGG signals. The results showed that Cl 3 BPA at 50 μM increased the levels of intracellular reactive oxygen species (ROS) and GnRH, upregulated the protein levels of kisspeptin and the expression of fshr, lhr and gnrh1 genes related to KGG in GT1-7 cells. In addition, 50 μM Cl 3 BPA significantly upregulated the phosphorylation of extracellular regulated protein kinases 1/2 (Erk1/2), the protein levels of GPER1 and the expression of the gper1 as well as the most target genes associated with mitogen-activated protein kinase (MAPK)/Erk1/2 pathways. Specific signal inhibitor experiments found that Cl 3 BPA activated KGG signals by activating the GPER1-mediated MAPK/Erk1/2 signaling pathway at the mRNA level. A docking test further confirmed the interactions between Cl 3 BPA and GPER1. The findings suggest that Cl 3 BPA might induce precocious puberty by increasing GnRH secretion together with KGG signaling upregulation, which is driven by GPER1-mediated signaling pathway. By comparison, Cl x BPAs with fewer chlorine atoms had more obvious effects on the expression of proteins and partial genes related to KGG signals in GT1-7 cells., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background: Kisspeptin is an essential regulator of hypothalamic gonadotropin-releasing hormone release and is required for physiological ovulation. Native kisspeptin-54 can induce oocyte maturation during in vitro fertilization treatment, including in women who are at high risk of ovarian hyperstimulation syndrome. MVT-602 is a potent kisspeptin receptor agonist with prospective utility to treat anovulatory disorders by triggering oocyte maturation and ovulation during medically assisted reproduction (MAR). Currently, the endocrine profile of MVT-602 during ovarian stimulation is unreported., Objective: To determine the endocrine profile of MVT-602 in the follicular phase of healthy premenopausal women (phase-1 trial), and after minimal ovarian stimulation to more closely reflect the endocrine milieu encountered during MAR (phase-2a trial)., Design: Two randomized, placebo-controlled, parallel-group, dose-finding trials., Setting: Clinical trials unit., Patients: Healthy women aged 18-35 years, either without (phase-1; n = 24), or with ovarian stimulation (phase-2a; n = 75)., Interventions: Phase-1: single subcutaneous dose of MVT-602 (0.3, 1.0, or 3.0 μg) or placebo, (n = 6 per dose). Phase-2a: single subcutaneous dose of MVT-602 (0.1, 0.3, 1.0, or 3.0 μg; n = 16-17 per dose), triptorelin 0.2 mg (n = 5; active comparator), or placebo (n = 5)., Main Outcome Measures: Phase-1: safety/tolerability; pharmacokinetics; and pharmacodynamics (luteinizing hormone [LH] and other reproductive hormones). Phase-2a: safety/tolerability; pharmacokinetics; pharmacodynamics (LH and other reproductive hormones); and time to ovulation assessed by transvaginal ultrasound., Results: In both the trials, MVT-602 was safe and well tolerated across the entire dose range. It was rapidly absorbed and eliminated, with a mean elimination half-life of 1.3-2.2 hours. In the phase-2a trial, LH concentrations increased dose dependently; mean maximum change from baseline of 82.4 IU/L at 24.8 hours was observed after administration of 3 μg MVT-602 and remained >15 IU/L for 33 hours. Time to ovulation after drug administration was 3.3-3.9 days (MVT-602), 3.4 days (triptorelin), and 5.5 days (placebo). Ovulation occurred within 5 days of administration in 100% (3 μg), 88% (1 μg), 82% (0.3 μg), and 75% (0.1 μg), of women after MVT-602, 100% after triptorelin and 60% after placebo., Conclusions: MVT-602 induces LH concentrations of similar amplitude and duration as the physiological midcycle LH surge with potential utility for induction of oocyte maturation and ovulation during MAR., Clinical Trial Registration Number: EUDRA-CT: 2017-003812-38, 2018-001379-20., Competing Interests: Declaration of interests A.A. reports Myovant Sciences Ltd Consultancy Fee and NIHR Clinician Scientist Fellowship for the submitted work. M.U. has nothing to disclose. C.V.-P. is an employee of QPS Netherlands BV. L.B. reports contracting consultant to Myovant Sciences outside the submitted work. M.E. has nothing to disclose. R.W. has nothing to disclose. T.-Y.L. has nothing to disclose. J.C.A.F. has nothing to disclose. E.M has nothing to disclose. W.S.D. reports consulted for Myovant Sciences Ltd. for the submitted work; NIHR research professorship; consulting fees from Myovant Sciences outside the submitted work., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

In Heteropneustes fossilis, kisspeptins (Kiss) and nonapeptides (NPs; vasotocin, Vt; isotocin, Itb; Val8-isotocin, Ita) stimulate the hypothalamus-pituitary-gonadal (HPG) axis, and estrogen feedback modulates the expression of these systems. In this study, functional interactions among these regulatory systems were demonstrated in the brain and ovary at the mRNA expression level. Human KISS1 (hKISS1) and H. fossilis Kiss2 (HfKiss2) produced biphasic effects on brain and ovarian vt, itb and ita expression at 24 h post injection: low and median doses produced inhibition, no change or mild stimulation, and the highest dose consistently stimulated the mRNA levels. The Kiss peptides produced an upregulation of NP mRNA expression at 24 h incubation of brain and ovarian slices by increasing the concentration of hKISS1 and HfKiss2. The kiss peptides stimulated brain cyp19a1b and ovary cyp19a1a expression, both in vivo and in vitro. Peptide234, a Kiss1 receptor antagonist, inhibited basal mRNA expression of the NPs, cyp19a1b and cyp19a1a, which was prevented by the Kiss peptides, both in vivo and in vitro. In all the experiments, HfKiss2 was more effective than hKISS1 in modulating mRNA expression. The results suggest that the NP and E 2 systems are functional targets of Kiss peptides and interact with each other., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Kisspeptin (Kp-10) is a neuropeptide that binds to GPR54 receptors, exerting several functions mainly in the nervous and reproductive systems of the body. However, its effects and mechanisms of action on the skeletal system remain poorly understood. This study evaluated the effects of different concentrations of Kp-10 on in vitro osteogenic differentiation of multipotent mesenchymal stromal cells (MSCs) extracted from the bone marrow (BM) of adult Wistar rats. Two-month-old female rats were euthanized to extract BM from long bones to obtain MSCs. Four experimental groups were established in vitro: a control and Kp-10 at concentrations of 0.01, 0.05 and, 0.1 µg/mL. After induction of osteogenic differentiation, cell viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyl tetrazolium bromide (MTT) assay, alkaline phosphatase activity, collagen synthesis, percentage of area covered by MSCs/field and mineralized nodules/field, and immunocytochemistry of the GPR54 receptor tests. Furthermore, evaluation of gene transcripts for type I collagen, Runx-2, Bmp-2, bone sialoprotein, osteocalcin and osteopontin was performed using real-time RT-qPCR. It was observed that MSCs expressed GPR54 receptor to which Kp-10 binds during osteogenic differentiation, promoting a negative effect on osteogenic differentiation. This effect was observed at all the Kp-10 concentrations in a concentration-dependent manner, characterized by a decrease in the activity of alkaline phosphatase, collagen synthesis, mineralized nodules, and decreased expression of gene transcripts for type I collagen, osteocalcin, osteopontin, and Runx-2. Thus, Kp-10 inhibits in vitro osteogenic differentiation of MSCs extracted from the BM of adult Wistar rats., Competing Interests: Conflicts of Interest The authors declare no conflict of interest., (Copyright © 2023 Elsevier GmbH. All rights reserved.)

Kisspeptin is characterized as a neuropeptide with a pivotal function in female and male infertility, and its antioxidant properties have been demonstrated. In this study, the effects of kisspeptin on the improvement of the vitrification and thawing results of human ovarian tissues were investigated. In this work, 12 ovaries from patients who underwent hysterectomy were collected laparoscopically, and then 32 samples from each of their tissues were taken. Haematoxylin and eosin (H&E) staining was performed to check the normality of the ovarian tissue and, subsequently, the samples were allocated randomly into four groups, including: (1) fresh (control), (2) vitrification, (3) vitrified + 1 μM kisspeptin, and (4) vitrified + 10 μM kisspeptin groups. After vitrification, thawing, and tissue culture processes, H&E staining for tissue quality assessment, terminal deoxynucleotidyl transferase dUTP nick end labelling assay for apoptosis evaluation, and malondialdehyde (MDA), superoxide dismutase (SOD), and ferric reducing ability of plasma tests for oxidative stress appraisal were carried out. Our histological results showed incoherency of ovarian tissue morphology in the vitrification group compared with other groups. Other findings implicated increased apoptosis rate and MDA concentration and reduced SOD activity and total antioxidant capacity (TAC) in the vitrification group compared with the control group ( P < 0.05). Moreover, decreased apoptosis rate and MDA concentration, and increased TAC and SOD function were observed in the vitrification with kisspeptin groups (1 μM and 10 μM) compared with the vitrified group ( P < 0.05). Our reports express that kisspeptin is an effective agent to overcome the negative effects of vitrification by regulating reactive oxygen species-related apoptotic processes.

We evaluated whether the administration of kisspeptin-10 (Kp10) is capable of restoring gonadal function in hypothyroid male rats. Hypothyroidism was induced with 6-propyl-2-thiouracil (PTU) for three months. In the last month, half of the hypothyroid animals were treated with Kp10. Hypothyroidism reduced testicular and sex gland mass, decreased the proliferation of the seminiferous epithelium, and compromised sperm morphology, motility, and vigor. A decrease in plasma LH and testosterone levels and an increase in prolactin secretion were observed in the hypothyroid rats. Hypothyroidism reduced Kiss1 and Kiss1r protein and gene expression and Star and Cyp11a1 mRNA levels in the testis. Furthermore, it reduced Lhb, Prl, and Drd2 and increased Tshb and Gnrhr expression in the pituitary. In the hypothalamus, hypothyroidism increased Pdyn and Kiss1r while reducing Gnrh1. Kp10 treatment in hypothyroid rats restored testicular and seminal vesicle morphology, improved sperm morphology and motility, reversed high prolactin levels, and increased LH and testosterone levels. In addition, Kp10 increased testicular expression of Kiss1, Kiss1r, Fshr, and Nr5a1 and pituitary Kiss1 expression. Our findings describe the inhibitory effects of hypothyroidism on the male gonadal axis and sperm quality and demonstrate that Kp10 treatment reverses high prolactin levels and improves gonadal function and sperm quality in hypothyroid rats., (© 2023. Springer Nature Limited.)

The present study was conducted to ascertain whether the role of kisspeptin in promoting in vitro development of preantral follicles was through the regulation of P450 aromatase gene expression and steroidogenesis in sheep. Accordingly, the cumulus cells and oocytes were collected from different development stages of preantral follicles grown in vivo and cultured in vitro in TCM199B (Group I), TCM199B + KP (10 μg/mL) (Group II) and Standard medium + KP (10 μg/mL). To measure the steroid (Estradiol-17β; E 2 and Progesterone; P 4 ) synthesis through ELISA, spent culture medium was collected separately from the same in vitro groups. E 2 synthesis in the spent medium collected from all the three groups showed an increasing trend from PFs' exposed to respective culture media for 3 min to 2-day culture stage but decreased thereafter till 6-day culture stage. This is followed by a sharp increase in E 2 concentration in the spent medium collected after in vitro maturation. However, P 4 synthesis in group III followed increased pattern as the development progressed from PFs' exposed to culture medium for 3 min to in vitro maturation stage. The steroid production was observed at all stages of in vitro development in altered supplemented conditions. The steroid synthesis in the spent medium was highest in the 6 day cultured PFs' in Standard medium + KP matured in vitro for 24 h. Therefore, supplementation of kisspeptin along with other growth factors promoted steroid production in cultured preantral follicles far better than in other media., (© 2023 Wiley-VCH GmbH. Published by John Wiley & Sons Ltd.)

Gamma-hydroxybutyrate (GHB, clinically administrated as sodium oxybate) is a GABA-B/GHB receptor agonist inducing prosexual effects and progesterone secretion in humans. As the neuropeptide kisspeptin has well-established roles in regulating sexual behavior and as it was also associated with GABA-B receptor and progesterone function, we investigated the effect of two GHB doses (20 and 35 mg/kg p.o.) on plasma kisspeptin levels in 30 healthy male volunteers, using a double-blind, randomized, placebo-controlled cross-over design. We found no significant alterations of kisspeptin levels after GHB administration compared to placebo. In conclusion, plasma kisspeptin levels are not related to the prosexual effects of GHB.

Secretion of pulsatile gonadotropin-releasing hormone (GnRH) is essential for reproduction. Kisspeptin neurons in the arcuate nucleus (ARC), which coexpress neurokinin B (NKB) and its receptor (NK3R), are believed to be components of the GnRH pulse generator that regulates pulsatile GnRH secretion. We examined the effects of peripheral infusion of senktide, an NK3R selective agonist, on GnRH pulse generator activity by monitoring multiple unit activity (MUA) in the goat ARC. Previous studies have shown that characteristic increases in MUA (MUA volleys) reflect GnRH pulse generator activity. Senktide was infused intravenously or intravaginally for 2 h while recording MUA. Both infusions significantly increased the MUA volley frequency compared with the control. These results demonstrate that peripherally administered senktide acts centrally to sustainably accelerate the neural activity of the GnRH pulse generator throughout the infusion period. This suggests the possibility of practical applications of NK3R agonists for improving reproductive activity in farm animals.

Objective: This study investigated the expression of Kiss1 gene on the testis and the blood of Wistar rats, following the administration of methanolic extract of Hibiscus Sabdariffa (MEHS)., Methods: Fifteen (15) rats with an average weight of 204g were randomly divided into three (3) groups (A-C). Group A was given no treatment and served as the normal control group. Groups B and C were orally administered 200mg/kg and 400mg/kg of MEHS, respectively. The extract was administered once a day for 21 days., Results: There was a significant increase in the relative testicular weight in group B and C compared to the control group (p=0.035). There was no significant difference in the sperm parameters, reproductive hormones, and antioxidant levels in all the treatment groups when compared to the control group (p>0.05). There is a significantly lower expression intensity of the Kiss1 gene in the blood in groups B (p=0.000) and C (p=0.017), compared to the control group. There is no difference in the relative intensity of Kiss1 gene expression in the testis of all the experimental groups (p=0.173)., Conclusions: MEHS caused no histopathological changes on the testis at both doses. MEHS shows the potential of downregulating the expression of the Kiss1 gene in the blood. However, this effect lacks a regulatory mechanism on the reproductive hormones, sperm parameters, testicular morphology, and antioxidative levels.

Reproductive sterilization by surgical gonadectomy is strongly advocated to help manage animal populations, especially domesticated pets, and to prevent reproductive behaviors and diseases. This study explored the use of a single-injection method to induce sterility in female animals as an alternative to surgical ovariohysterectomy. The idea was based on our recent finding that repetitive daily injection of estrogen into neonatal rats disrupted hypothalamic expression of Kisspeptin (KISS1), the neuropeptide that triggers and regulates pulsatile secretion of GnRH. Neonatal female rats were dosed with estradiol benzoate (EB) either by daily injections for 11 days or by subcutaneous implantation of an EB-containing silicone capsule designed to release EB over 2-3 weeks. Rats treated by either method did not exhibit estrous cyclicity, were anovulatory, and became infertile. The EB-treated rats had fewer hypothalamic Kisspeptin neurons, but the GnRH-LH axis remained responsive to Kisspeptin stimulation. Because it would be desirable to use a biodegradable carrier that is also easier to handle, an injectable EB carrier was developed from PLGA microspheres to provide pharmacokinetics comparable to the EB-containing silicone capsule. A single neonatal injection of EB-microspheres at an equivalent dosage resulted in sterility in the female rat. In neonatal female Beagle dogs, implantation of an EB-containing silicone capsule also reduced ovarian follicle development and significantly inhibited KISS1 expression in the hypothalamus. None of the treatments produced any concerning health effects, other than infertility. Therefore, further development of this technology for sterilization in domestic female animals, such as dogs and cats is worthy of investigation., (© 2023. The Author(s).)

The action of betacellulin (BTC) on basic ovarian cell functions and interrelationships with kisspeptin (KISS) was investigated. For this purpose, we examined (1) the effect of the addition of BTC (0, 1, 10, and 100 ng/ml) given alone or in combination with KISS (10 ng/ml) on cultured feline ovarian fragments or granulosa cells. Viability, proliferation (accumulation of cyclin B1) and apoptosis (accumulation of bax), and the release of steroid hormones (progesterone, testosterone, and estradiol) were analyzed by using the Trypan blue exclusion test, quantitative immunocytochemistry, and ELISA. The addition of KISS alone increased proliferation, apoptosis, progesterone, estradiol release, and decreased testosterone but did not affect viability. The addition of BTC alone decreased cell proliferation, apoptosis, progesterone, testosterone, and estradiol release but did not influence viability. Furthermore, BTC mainly inhibited the stimulatory action of KISS on feline ovarian functions. The findings of our study suggest the effects of KISS on basic ovarian functions. We also observed the influence of BTC on these functions and its ability to modify the effects of KISS on these processes., Competing Interests: Conflicts of interest The authors confirm the lack of potential conflicts of interest., (Copyright © 2023 Society for Biology of Reproduction & the Institute of Animal Reproduction and Food Research of Polish Academy of Sciences in Olsztyn. Published by Elsevier B.V. All rights reserved.)

The hypothalamic neurohormone kisspeptin-10 (KP-10) was inherently implicated in cholinergic pathologies when aberrant fluctuations of expression patterns and receptor densities were discerned in neurodegenerative micromilieus. That said, despite variable degrees of functional redundancy, KP-10, which is biologically governed by its cognate G-protein-coupled receptor, GPR54, attenuated the progressive demise of α-synuclein (α-syn)-rich cholinergic-like neurons. Under explicitly modeled environments, in silico algorithms further rationalized the surface complementarities between KP-10 and α-syn when KP-10 was unambiguously accommodated in the C-terminal binding pockets of α-syn. Indeed, the neuroprotective relevance of KP-10's binding mechanisms can be insinuated in the amelioration of α-syn-mediated neurotoxicity; yet it is obscure whether these extenuative circumstances are contingent upon prior GPR54 activation. Herein, choline acetyltransferase (ChAT)-positive SH-SY5Y neurons were engineered ad hoc to transiently overexpress human wild-type or E46K mutant α-syn while the mitigation of α-syn-induced neuronal death was ascertained via flow cytometric and immunocytochemical quantification. Recapitulating the specificity observed on cell viability, exogenously administered KP-10 (0.1 µM) substantially suppressed wild-type and E46K mutant α-syn-mediated apoptosis and mitochondrial depolarization in cholinergic differentiated neurons. In particular, co-administrations with a GPR54 antagonist, kisspeptin-234 (KP-234), failed to abrogate the robust neuroprotection elicited by KP-10, thereby signifying a GPR54 dispensable mechanism of action. Consistent with these observations, KP-10 treatment further diminished α-syn and ChAT immunoreactivity in neurons overexpressing wild-type and E46K mutant α-syn. Overall, these findings lend additional credence to the previous notion that KP-10's binding zone may harness efficacious moieties of neuroprotective intent.

In Brief: Seminal nerve growth factor induces ovulation in camelids by influencing the secretion of gonadotrophin-releasing hormone (GnRH) into the portal vessels of the pituitary gland. We show that the nerve growth factor-induced release of GnRH is not mediated directly through interaction with hypothalamic neurons., Abstract: Ovulation in camelids is triggered by seminal nerve growth factor (NGF). The mechanism of action of NGF appears to occur via the central nervous system. In this study, we tested the hypothesis that NGF acts in the hypothalamus to induce GnRH release. To determine if NGF-induced ovulation is associated with a rise in NGF concentrations in the cerebrospinal fluid (CSF), llamas were i) mated with an urethrostomized male, ii) mated with intact male, or given intrauterine iii) seminal plasma or i.v.) saline (Experiment 1). To characterize the luteinizing hormone (LH) response after central vs peripheral administration, llamas were treated with saline (negative control) or NGF either by i.v. or intracerebroventricular (ICV) administration (Experiment 2). To determine the role of kisspeptin, the effect of ICV infusion of a kisspeptin receptor antagonist on NGF-induced LH secretion and ovulation was tested in llamas (Experiment 3). In Experiment 1, a surge in circulating concentrations of LH was detected only in llamas mated with an intact male and those given intrauterine seminal plasma, but no changes in CSF concentrations of NGF were detected. In Experiment 2, peripheral administration (i.v.) of NGF induced an LH surge and ovulation, whereas no response was detected after central (ICV) administration. In Experiment 3, the kisspeptin receptor antagonist had no effect on the LH response to NGF. In conclusion, results did not support the hypothesis that NGF-induced ovulation is mediated via a trans-synaptic pathway within the hypothalamus, but rather through a releasing effect on tanycytes at the median eminence.

Background: Sperm cryopreservation reduces sperm quality. Kisspeptin (KP) has beneficial effects on sperm functions. This study compares the effect of KP and Glutathione (GSH) on mitigating the detrimental effects of the freeze-thaw cycle on sperm., Methods: An experimental study was conducted in Birjand (Iran) during 2018-2020. Thirty normal swim-up semen samples were treated with Ham's F10 medium (negative control), 1 mM GSH (positive control), or KP (10 µM) for 30 min before freezing. The motility, acrosome reaction, capacitation, and DNA quality of the frozen-thawed sperms were assessed according to the WHO guidelines. Statistical analysis was performed using paired t test, one-way analysis of variance, and least significant difference., Results: Pre-incubation with KP significantly increased the percentage of sperm motility (34.00±6.7, P=0.003) compared to the control (20.44±7.4) and GSH-treated (31.25±12.2) aliquots. The frequency of non-capacitated spermatozoa was significantly higher in the KP-treated group (98.73%) than in the control (96.46%) and GSH-treated (96.49%) aliquots (P<0.001). The percentage of acrosome-intact spermatozoa in the KP-treated group (77.44%) was significantly higher than the control (74.3%) and GSH-treated (74.54%) groups (P<0.001). The sperm frequency with normal histone in the KP-treated group (51.86%) and with normal protamine (65.39%) was significantly higher than the controls (P=0.001 and P=0.002, respectively). The percentage of TUNEL-positive sperm was significantly lower in the KP-treated group (9.09±2.71) than both GSH-treated (11.22±2.73) and control (11.31±2.2) groups (both P=0.002)., Conclusion: Pre-incubation with KP protects sperm motility and DNA integrity from the detrimental effect of the freeze-thaw cycle. KP is suitable as a pre-treatment to control sperm quality during freezing-thawing., Competing Interests: None declared., (Copyright: © Iranian Journal of Medical Sciences.)

Importance: The human physiological sexual response is crucial for reward, satisfaction, and reproduction. Disruption of the associated neurophysiological pathways predisposes to low sexual desire; the most prevalent psychological form is hypoactive sexual desire disorder (HSDD), which affects 8% of men but currently has no effective pharmacological treatment options. The reproductive neuropeptide kisspeptin offers a putative therapeutic target, owing to emerging understanding of its role in reproductive behavior., Objective: To determine the physiological, behavioral, neural, and hormonal effects of kisspeptin administration in men with HSDD., Design, Setting, and Participants: This double-blind, 2-way crossover, placebo-controlled randomized clinical trial was performed at a single academic research center in the UK. Eligible participants were right-handed heterosexual men with HSDD. Physiological, behavioral, functional magnetic resonance imaging (fMRI), and hormonal analyses were used to investigate the clinical and mechanistic effects of kisspeptin administration in response to visual sexual stimuli (short and long video tasks). The trial was conducted between January 11 and September 15, 2021, and data analysis was performed between October and November 2021., Interventions: Participants attended 2 study visits at least 7 days apart, in balanced random order, for intravenous infusion of kisspeptin-54 (1 nmol/kg/h) for 75 minutes or for administration of a rate-matched placebo., Main Outcomes and Measures: Changes in (1) brain activity on whole-brain analysis, as determined by fMRI blood oxygen level-dependent activity in response to visual sexual stimuli during kisspeptin administration compared with placebo, (2) physiological sexual arousal (penile tumescence), and (3) behavioral measures of sexual desire and arousal., Results: Of the 37 men randomized, 32 completed the trial. Participants had a mean (SD) age of 37.9 (8.6) years and a mean (SD) body mass index of 24.9 (5.4). On viewing sexual videos, kisspeptin significantly modulated brain activity in key structures of the sexual-processing network on whole-brain analysis compared with placebo (mean absolute change [Cohen d] = 0.81 [95% CI, 0.41-1.21]; P =  .003). Furthermore, improvements in several secondary analyses were observed, including significant increases in penile tumescence in response to sexual stimuli (by up to 56% more than placebo; mean difference = 0.28 units [95% CI, 0.04-0.52 units]; P = .02) and behavioral measures of sexual desire-most notably, increased happiness about sex (mean difference = 0.63 points [95% CI, 0.10-1.15 points]; P = .02)., Conclusions and Relevance: Collectively, this randomized clinical trial provides the first evidence to date showing that kisspeptin administration substantially modulates sexual brain processing in men with HSDD, with associated increases in penile tumescence and behavioral measures of sexual desire and arousal. These data suggest that kisspeptin has potential as the first pharmacological treatment for men with low sexual desire., Trial Registration: isrctn.org Identifier: ISRCTN17271094.

Background: Non-alcoholic fatty liver disease (NAFLD) adversely affects reproduction. We aimed to study the effect of a high-fat diet (HFD), supplemented with apple vinegar, on folliculogenesis in a rat model of NAFLD., Methods: Female rats were randomly divided into four groups (N = 28): Standard diet (SD), SD + vinegar, HFD, and HFD + vinegar groups. At the end of the study, biochemical tests were assessed in serum. HOMA-IR (Homeostatic model assessment-Insulin resistance) was calculated. Sex hormones were determined using an ELISA kit; ovary follicle counts were studied using histological methods. The proliferation index of granulosa cells was determined using immunohistochemistry. Kisspeptin expression in the ovary was detected using RT-PCR., Results: The HFD induced steatohepatitis and NAFLD. The ovaries in the rat model of NAFLD were atrophied. The ovaries had less count of developing follicles and corpus luteum, and more degenerated and cystic follicles in comparison with the SD group. Vinegar + HFD consumption decreased ALT, compared to the HFD group (P = 0.004). Steatohepatitis was reduced in the Vinegar + HFD group (P = 0.001). Vinegar + HFD considerably reduced HOMA-IR (p = 0.01). The HFD + vinegar diet could increase estradiol (P = 0.001), without significantly affecting progesterone or testosterone. In addition, an increase of primordial follicles as an ovarian reserve and also primary follicles were determined in the HFD + vinegar group. There were no statistical differences in the granulosa cell proliferation index in various follicle types between groups. HFD + vinegar significantly enhanced ovarian kisspeptin expression (p = 0.04)., Conclusions: The vinegar diet in a rat model of NAFLD raises estradiol, primordial, and small primary follicles, and increases ovarian kisspeptin expression indirectly. Insulin resistance and obesity were improved by apple vinegar, and anti-glycemic and anti-lipidemic effects were also determined. The supplementation of apple vinegar in NAFLD might be useful for ovary. However, it requires further investigation., (© 2022. The Author(s).)

Kisspeptin modulates GnRH secretion in mammals and peripheral administration of 10-amino acid fragment of kisspeptin (Kp10) induces LH release and ovulation in cattle. Experiments were done to determine if iv administration of kisspeptin will activate GnRH neurons (i.e., after crossing the blood-brain barrier) and if pre-treatment with a GnRH receptor blocker will alter kisspeptin-induced LH release (from gonadotrophs) and ovulation. In Experiment 1, cows (n = 3 per group) were given human-Kisspeptin10 (hKp10; 3 x 15 mg iv at 60-min intervals) or normal saline and euthanized 150 min after treatment was initiated. Every 20th free-floating section (50 μm thickness) from the preoptic area to hypothalamus was double immunostained to colocalize GnRH- (DAB) and activated neurons (cFOS; Nickel-DAB). Kisspeptin induced plasma LH release from 15 to 150 min (P = 0.01) but the proportion of activated GnRH neurons did not differ between groups (5.8% and 3.5%, respectively; P = 0.11). Immunogold electron microscopy detected close contacts between kisspeptin fibers and GnRH terminals in the median eminence. In Experiment 2, pubertal heifers (n = 5 per group) were treated with 1) hKp10 iv, 2) Cetrorelix (GnRH antagonist; im) + hKp10 iv or 3) saline on Day 6 of the follicular wave under low-progesterone condition. A rise in plasma LH concentration was detected from 15 to 240 min in the hKp10 group but not in cetrorelix or control group (P<0.001). Ovulations were detected only in the hKp10 group (4/5; P = 0.02). Cetrorelix treatment was associated with regression of the preovulatory dominant follicle and emergence of a new follicular wave 3.4±0.75 days after the treatment in all five heifers. Results support the hypothesis that the effect of peripheral kisspeptin is mediated downstream of GnRH synthesis and does not involve GnRH-independent LH release from gonadotrophs. Peripheral kisspeptin may release pre-synthesized GnRH from the nerve terminals in areas outside the blood-brain barrier., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2022 Leonardi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Kisspeptin is a hypothalamic neuropeptide that acts via the hypothalamus to stimulate hypothalamic gonadotrophin-releasing hormone secretion and downstream gonadotrophin release. In health, kisspeptin induces normal puberty and modulates ovulation in healthy women. Hypothalamic kisspeptin expression is reduced in several functional reproductive disorders; thus, treating such conditions with kisspeptin is conceptually attractive. Recent studies have demonstrated that kisspeptin can induce a more physiological degree of oocyte maturation during in vitro fertilisation treatment that can reduce the risk of potentially life-threatening complications such as ovarian hyperstimulation syndrome seen with human chorionic gonadotrophin. Furthermore, chronic use of kisspeptin could potentially restore reproductive health in females with hypothalamic amenorrhoea, treat hyposexual drive disorder in otherwise healthy males and has potential indications in polycystic ovary syndrome, osteoporosis and metabolic dysfunction-associated fatty liver disease. Finally, kisspeptin analogues could potentially overcome some of the pharmacological challenges associated with the natural forms of kisspeptin such as short duration of action and development of tachyphylaxis., Competing Interests: Declaration of competing interest AA and WSD have consulted for Myovant Sciences who are developing a kisspeptin receptor agonist., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Hypothyroidism causes ovarian dysfunction and infertility in women, in addition to being associated with hyperprolactinemia and reduced hypothalamic expression of kisspeptin (Kp). However, it remains unknown whether and how Kp is able to reverse the ovarian dysfunction caused by hypothyroidism. Methods: Hypothyroidism was induced in adult female Wistar rats using 6-propyl-2-thiouracil for 3 months. In the last month, half of the animals received Kp10. Blood samples were collected for dosage of free thyroxine, thyrotropin (TSH), luteinizing hormone (LH), prolactin (PRL), progesterone (P 4 ), and estradiol (E 2 ), and uteruses and ovaries were collected for histomorphometry. Body and ovarian weight and the number of corpora lutea were also evaluated. Half of the brains were evaluated by immunohistochemistry to Kp, and the other half had the arcuate nucleus of hypothalamus (ARC) and preoptic area microdissected for gene evaluation of Kiss1, Nkb, Pdyn, and Gnrh1. The pituitary gland and corpora lutea were also dissected for gene evaluation. Results: Hypothyroidism kept the animals predominantly acyclic and promoted a reduction in ovarian weight, number of corpora lutea, endometrial thickness, number of endometrial glands, and plasma LH, in addition to increasing the luteal messenger RNA (mRNA) expression of Star and Cyp11a1 and reducing 20αHsd . An increase in plasma PRL and P 4 levels was also caused by hypothyroidism. Kp immunoreactivity and Kiss1 and Nkb mRNA levels in the ARC and Kiss1 in the anteroventral periventricular nucleus of hypothalamus were reduced in hypothyroid rats. Hypothyroid animals had lower pituitary gene expression of Gnrhr , Lhb , Prl , and Drd2 , and an increase in Tshb . The treatment with Kp10 restored estrous cyclicality, plasma LH, ovarian and uterine morphology, and Cyp11a1 , 3βHsd , and 20αHsd mRNA levels in the corpora lutea. Kp10 treatment did not alter gene expression for Kiss1 or Nkb in the ARC of hypothyroid rats. Nevertheless, Kp10 increased Lhb mRNA levels and reduced Tshb in the pituitary compared with the hypothyroid group. Conclusions: The present findings characterize the inhibitory effects of hypothyroidism on the hypothalamic-pituitary-gonadal axis in female rats and demonstrate that Kp10 is able to reverse the ovarian dysfunction caused by hypothyroidism, regardless of hyperprolactinemia.

Scope: Puberty timing, critical for adulthood wellbeing, is influenced by the environment, life-style, and diets. However, differential puberty-interfering effects of soy and soy isoflavone are observed in both epidemiological and toxicological studies. Additionally, their impact on neuroendocrine function at various pre-pubertal developmental windows is unclear., Methods and Results: This study investigates the effect of genistein, a typical soy isoflavone, at neonatal, lactational, and post-weaning stages on the time of vaginal opening and determines the levels of neuroendocrine factors in female rats using immunofluorescence, immunochemistry, and enzyme-linked immunosorbent assays. A physiologically relevant dosage (10 mg kg -1 ) is used to resemble human exposure. The results show that genistein exposure at lactational stage significantly accelerates vaginal opening time, marginally increases hypothalamic gonadotropin-releasing hormone (GnRH) secretion, significantly enhances kisspeptin receptor expression, and markedly elevates blood levels of GnRH, luteinizing hormone, and follicle-stimulating hormone, while neonatal and post-weaning exposures do not induce significant alternations., Conclusion: Lactational stage may be an important window for genistein to impact reproductive development and neuroendocrine regulations., (© 2022 Wiley-VCH GmbH.)

The objective of this experiment was to determine if incorporation of kisspeptin-10 (Kp10) into treatment with estradiol benzoate (EB) and sulpiride to induce early cyclicity would result in greater endocrine responses and a greater number of mares responding with either follicle(s) > 30 mm or ovulation within 25 days of treatment. Eighteen anestrous mares were blocked by breed, body condition, and age before random assignment to treatment or control. All mares received 50 mg EB before receiving osmotic minipumps containing either saline (n = 9) or Kp10 (50 μg/hour; n = 9) one day later. The next day, all mares received 3 g sulpiride. Serial blood sampling occurred after pump placement and continued daily for 25 days. Transrectal ultrasounds were performed regularly to monitor ovarian activity. Data were analyzed by Student's t-test or ANOVA with repeated measures. Seven Kp10-treated mares responded compared to only 4 saline-treated mares. Mean days from sulpiride treatment to ovarian response was less in Kp10-treated mares (13.7 ± 1.1 d, P ≤ 0.01) compared to saline-treated mares (35.9 ± 7.8 d). Plasma prolactin increased (P < 0.001) in response to sulpiride in all mares; however, prolactin was higher (P < 0.05) in Kp10-treated mares. Plasma LH increased in all mares beginning 5 days after sulpiride but was greater (P < 0.0001) in Kp10-treated mares. Plasma FSH concentrations did not differ between groups. In conclusion, incorporation of Kp10 potentiated the prolactin and LH responses to EB-sulpiride and resulted in more mares responding with early ovarian activity., Competing Interests: Conflict of interest The authors declare no conflict of interest., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Intracerebroventricular (ICV) administration of estradiol benzoate (E 2 B) and progesterone (P) induces intense lordosis behavior in ovariectomized rats primed peripherally with E 2 B. The present study tested the hypothesis that the Kisspeptin (Kiss) and melanin-concentrating hormone (MCH) pathways regulate female sexual behavior induced by these steroid hormones. In Experiment 1, we tested the relevance of the Kiss pathway by ICV infusion of its inhibitor, kiss-234, before administration of E 2 B or P in estrogen-primed rats. Lordosis induced by E 2 B alone or with the addition of P was reduced significantly at 30, 120, and 240 min. In Experiment 2, ICV infusion of MCH 30 min before E 2 B or P significantly reduced lordosis in rats primed with E 2 B alone. These data support the hypothesis that the Kiss and MCH pathways, which can release or modulate gonadotropin-releasing hormone (GnRH), are involved in E 2 B- and P-induced lordosis., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Importance: Despite being the most common female sexual health complaint worldwide, current treatment options for hypoactive sexual desire disorder (HSDD) are limited in their safety and effectiveness. The hormone kisspeptin is a key endogenous activator of the reproductive hormonal axis with additional emerging roles in sexual and emotional behavior; however, its effects in women with HSDD are unknown., Objective: To test the hypothesis that kisspeptin enhances sexual and attraction brain processing in women with HSDD., Design, Setting, and Participants: This randomized clinical trial was double-masked and placebo controlled with a 2-way crossover. The trial was conducted in a university research setting in the UK from October 2020 to April 2021. Eligible participants were premenopausal women with HSDD. Functional neuroimaging, psychometric, and hormonal analyses were employed to investigate the effects of kisspeptin administration on brain processing, in response to erotic stimuli (erotic videos) and facial attraction (face images of varying attractiveness). Data were analyzed from May to December 2021., Interventions: A 75-minute intravenous infusion of kisspeptin-54 (1 nmol/kg/h) vs equivalent-rate placebo infusion., Main Outcomes and Measures: Blood oxygen level-dependent responses across the whole brain and regions of interest during kisspeptin vs placebo administration in response to erotic and facial attraction stimuli., Results: Of the 40 participants who were randomized, 32 women completed both kisspeptin and placebo visits, with a mean (SE) age of 29.2 (1.2) years. Kisspeptin administration resulted in modulations in sexual and facial attraction brain processing (deactivation of the left inferior frontal gyrus: Z max, 3.76; P = .01; activation of the right postcentral and supramarginal gyrus: Z max, 3.73; P < .001; deactivation of the right temporoparietal junction: Z max 4.08; P = .02). Furthermore, positive correlations were observed between kisspeptin-enhanced hippocampal activity in response to erotic videos, and baseline distress relating to sexual function (r = 0.469; P = .007). Kisspeptin's enhancement of posterior cingulate cortex activity in response to attractive male faces also correlated with reduced sexual aversion, providing additional functional significance (r = 0.476, P = .005). Kisspeptin was well-tolerated with no reported adverse effects., Conclusions and Relevance: These findings lay the foundations for clinical applications for kisspeptin in women with HSDD., Trial Registration: ISRCTN trial registry identifier: ISRCTN17271094.

Background: Kisspeptin is a neuropeptide with a primary role on the onset of puberty and has beneficial effects on ischemia/ reperfusion (I/R) injury. In this study, we aimed to investigate the effect of kisspeptin administration on striatal I/R injury in mice., Methods: Forty adult C57/BL6 mice were randomly divided into four groups: Sham, Kisspeptin, I/R, and I/R + Kisspeptin groups. The groups were administered with either physiological saline (Sham and I/R groups) or kisspeptin (Kisspeptin and I/R + Kisspeptin groups) intraperitoneally 40 min before the operation. A microdialysis probe was placed in the right striatum according to stereotaxic coordinates. During the experimental period, artificial cerebrospinal fluid was passed through the micropump. Then, transient cerebral ischemia was established by compressing both common carotid arteries with an aneurysm clip for 15 min and animals were reperfused for 2 h. Throughout the process of microdialysis (before, during and after I/R period), samples were collected to measure dopamine (DA), noradrenaline (NA), and 3,4-dihydroxyphenylglycine (DHPG) at intervals of 20 min continuously. At the end of the reperfusion period, the animals were decapitated, striatum was dissected, half of the animals were used for oxidative stress analyses (reduced glutathione, glutathione S-transferase (GST), superoxide dismutase (SOD), malondialdehyde (MDA), and the other half were used for histopathology analyses., Results: Number of glial cells was significantly increased in kisspeptin-administered groups. DA levels in ischemic animals were decreased by kisspeptin administration (p < 0.0001). NA levels were reduced in animals administered with kisspeptin without I/R injury (p < 0.05). DHPG levels reduced during the reperfusion period in ischemic animals (p < 0.05). Kisspeptin did not exhibit a significant antioxidant activity in the ischemic animals, while GST and SOD levels were reduced in the I/R + kisspeptin group compared to the kisspeptin group (p < 0.05)., Discussion: Our results suggest that kisspeptin may be regulating the neurotransmitter release and metabolism, as well as inflammatory response in brain upon I/R injury.

Kisspeptins (KPs) are the most potent stimulating neurotransmitters of GnRH release, and consequently KP administration triggers LH and/or FSH release. In small ruminants, KP or its analogs induced an LH surge followed by ovulation in both cyclic and acyclic animals, while in the mare KP only increased LH plasma levels but failed to induce ovulation. This study in jennies compares the endocrinological effects, ovulatory and pregnancy rates of the KP analog C6 and the GnRH analog buserelin acetate. The ovarian activity of nine Amiata jennies was monitored daily by transrectal ultrasound for three complete estrous cycles. Jennies in estrus were assigned, to one of three treatment groups: 50 nmol of the KP analog C6 (injected twice, 24 h apart, C6 group); 0.4 mg buserelin acetate (injected once, Bu group); and 2 mL of saline (injected once, CTRL group). Blood samples were collected at Day-1 (-24 h) Day0 (h0, before treatment), h2, h4, h6, h8, h10, h24 (before second treatment with C6), h26, h28, h30, h32, h34, h48 and every 24 h until ovulation. Jennies were inseminated once at h24 with fresh extended semen from a donkey stallion. Pregnancy diagnoses were performed 14 days after ovulation. On days 5, 10, and 14 after ovulation, for every CL the cross-sectional area (CSA) and the vascularized area (VA) were recorded by color doppler ultrasound and measured. Significantly higher plasma LH levels were found after induction between the Bu and CTRL groups at h6 and h8 (P < 0.05), while tendentially higher differences were found between the Bu/C6 groups and CTRL at h10. Five/9, 4/9, and 2/9 jennies ovulated between 24 and 48 h after induction from the Bu, C6, and CTRL groups respectively, (P > 0.05). Correlations between corpora lutea CSA and VA with serum progesterone concentration were r = 0.31, P = 0.01, r = 0.38, P = 0.01, respectively. Pregnancy rates after artificial insemination did not differ among groups (CTRL: 6/9, 66.7%; C6: 7/9, 77.8%; Bu: 6/9, 66.7%; P > 0.05). Ovulation rates after C6 treatment were comparable to that of Bu, although not different from the CTRL. Pregnancy rates were comparable to the literature in terms of fresh extended donkey semen in every group. This study suggests that stimulation of the Kp system in jennies, in contrast to findings observed in mares, induces ovulation. Further studies using higher doses and/or more animals are needed to better characterize the efficacy of C6 in jennies., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Kisspeptin is an anti-metastatic mediator in many cancer types, acting through its receptor, KISS1R. However, controversy remains regarding its role in breast cancer since both pro- and anti-metastatic roles have been ascribed to it. In KISS1R overexpressing triple-negative breast cancer (TNBC) cells, stimulation has been associated with increased invasion and MMP-9 expression, leading to the suggestion that hormone receptor status determines the metastatic effects of kisspeptin. To assess the veracity of this claim, we compared endogenous KISS1R signalling and physiological output in the hormone receptor-negative MDA-MB-231 and BT-20 cell lines after KP-10 (shortest active kisspeptin peptide) stimulation. MDA-MB-231 cells are metastatic when implanted in mice while BT-20 are not and remain epithelial-like. We show that both cell lines express KISS1R mRNA and respond to KP-10 by elevating calcium mobilisation. However, KP-10 stimulation induced migration of MDA-MB-231, but not BT-20 cells, in a calcium-dependent manner. Moreover, only BT-20 cells responded to KP-10 by increasing ERK phosphorylation in a β-arrestin-dependent manner. Interestingly, both cell lines displayed different complements of β-arrestin 1 and 2 expression. Overall, our data shows that, in TNBC, it is not universally true that kisspeptin/KISS1R stimulate migration or pro-metastatic behaviour, as divergent responses were observed in the two TNBC lines tested. Whether this divergence is related to the observed differences in β-arrestin complements warrants further investigation and may enable further stratification of the ability of kisspeptin to influence breast tumour behaviour.

Prenatal and postnatal biphasic increases in plasma testosterone levels derived from perinatal testes are considered critical for defeminizing/masculinizing the brain mechanism that regulates sexual behavior in male rats. Hypothalamic kisspeptin neurons are indispensable for stimulating GnRH and downstream gonadotropin, as well as the consequent testicular testosterone production/release in adult male rats. However, it is unclear whether kisspeptin is responsible for the increase in plasma testosterone levels in perinatal male rats. The present study aimed to investigate the role of Kiss1/kisspeptin in generating perinatal plasma LH and the consequent testosterone increase in male rats by comparing the plasma testosterone and LH profiles of wild-type (Kiss1 +/+ ) and Kiss1 knockout (Kiss1 -/- ) male rats. A biphasic pattern of plasma testosterone levels, with peaks in the prenatal and postnatal periods, was found in both Kiss1 +/+ and Kiss1 -/- male rats. Postnatal plasma testosterone and LH levels were significantly lower in Kiss1 -/- male rats than in Kiss1 +/+ male rats, whereas the levels in the prenatal embryonic period were comparable between the genotypes. Exogenous kisspeptin challenge significantly increased plasma testosterone and LH levels and the number of c-Fos-immunoreactive GnRH neurons in neonatal Kiss1 -/- and Kiss1 +/+ male rats. Kiss1 and Gpr54 (kisspeptin receptor gene) were found in the testes of neonatal rats, but kisspeptin treatment failed to stimulate testosterone release in the cultured testes of both genotypes. These findings suggest that postnatal, but not prenatal, testosterone increase in male rats is mainly induced by central kisspeptin-dependent stimulation of GnRH and consequent LH release.

Context: Hyperprolactinemia suppresses gonadotropin-releasing hormone (GnRH)-induced luteinizing hormone (LH) pulses. The hypothalamic neuropeptide kisspeptin potently stimulates the secretion of GnRH. The effects of exogenous kisspeptin administration on GnRH pulse generation in the setting of hyperprolactinemia have not previously been explored., Objective: This work aimed to examine the effects of kisspeptin on GnRH secretion, as reflected by LH secretion, in women with hyperprolactinemia., Methods: Women with hyperprolactinemia (n = 11) participated in two 12-hour visits. Before study visits, participants underwent washout of dopamine agonist and/or combined oral contraceptive. Frequent blood sampling was performed (1 sample was collected every 10 minutes). Visit 1 involved no intervention, to examine baseline LH pulsatility. During visit 2, kisspeptin 112-121 (0.24 nmol/kg) was administered every 1 hour, for 10 hours. At hour 11, one intravenous bolus of GnRH (75 ng/kg) was administered., Results: Repetitive intravenous bolus kisspeptin administration increased the total number of LH pulses in the setting of hyperprolactinemia. The interpulse interval declined during the same time frames. LH pulse amplitude did not change, but the mean LH rose. In 6 participants with progesterone levels suggestive of an anovulatory state, mean LH and estradiol levels increased significantly at visit 2. In the entire cohort, follicle-stimulating hormone and prolactin levels did not change significantly across the 2 visits. A total of 73% of subjects exhibited an LH pulse within 30 minutes of first kisspeptin dose., Conclusion: Kisspeptin is capable of stimulating hypothalamic GnRH-induced LH pulses in the setting of hyperprolactinemia., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society.)

Oxytocin is secreted by hypothalamic supraoptic nucleus (SON) and paraventricular nucleus (PVN) oxytocin neurons to induce uterine contractions during parturition. Increased activation of oxytocin neurons at parturition involves a network of afferent inputs that increase oxytocin neuron excitability. Kisspeptin fibre density increases around oxytocin neurons during pregnancy, and central kisspeptin administration excites oxytocin neurons only in late pregnancy. Kisspeptin signals via extracellular regulated kinase 1/2 (ERK1/2) and p38. Therefore, to determine whether kisspeptin excites oxytocin neurons via ERK1/2-p38 signalling in late-pregnant rats, we performed immunohistochemistry for phosphorylated ERK1/2 (pERK1/2) and phosphorylated p38 (p-p38) in oxytocin neurons of non-pregnant and late-pregnant rats. Intracerebroventricular (ICV) kisspeptin administration (2 µg) did not affect pERK1/2 or p-p38 expression in SON and PVN oxytocin neurons of non-pregnant or late-pregnant rats. Furthermore, ICV kisspeptin did not affect pERK1/2 or p-p38 expression in brain areas with major projections to the SON and PVN: the nucleus tractus solitarius, rostral ventrolateral medulla, locus coeruleus, dorsal raphe nucleus, organum vasculosum of the lamina terminalis, median preoptic nucleus, subfornical organ, anteroventral periventricular nucleus, periventricular nucleus and arcuate nucleus. Hence, kisspeptin-induced excitation of oxytocin neurons in late pregnancy does not appear to involve ERK1/2 or p38 activation in oxytocin neurons or their afferent inputs.

Hypothalamic hormone kisspeptin is also produced by placental syncytiotrophoblast. Blood leukocytes express a specific membrane receptor of kisspeptin (KISS-1R). Since kisspeptin-54 enters the bloodstream during pregnancy, the hormone has a systemic effect on the leukocytes only in this period. Earlier we demonstrated that kisspeptin-54 enhances the generation of regulatory T (Treg) cells and suppresses the IL-17-producing T helper (Th17) cells. NK cells specialize into a regulatory subtype with reduced cytotoxic activity against fetal cells under the hormone influence. Kisspeptin-54 also regulates the maturation of thymic dendritic cells (DC). However, kisspeptin-54 effect on leukocytes functional activity has not been studied. Although it is known that these cells play an important role in ensuring fetus survival. The aim of the study was investigation of kisspeptin-54 effect in concentrations comparable to its level during physiological pregnancy on neutrophils and monocytes functional activity. Cells were isolated from peripheral blood of healthy non-pregnant women and cultured with kisspeptin-54 for 1 h. The monocytes and neutrophils phagocytic activity was determined by reducing bacterial bioluminescence. The production of reactive oxygen species (ROS) was evaluated in a luminol-dependent chemiluminescence test. The activity of myeloperoxidase (MPO) and indolamine-2,3-dioxygenase (IDO) was determined spectrophotometrically. It was revealed that kisspeptin-54 inhibits phagocytosis, MPO and ROS of neutrophils. On the contrary, the hormone activates phagocytosis, MPO activity, ROS production and IDO activity of monocytes. Thus, received data demonstrate that kisspeptin-54 is an important reproductive hormone that regulates leukocytes functional activity. The action of kisspeptin-54 depends on the type of cells expressing KISS-1 R., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Context: Osteoporosis results from disturbances in bone formation and resorption. Recent nonhuman data suggest that the reproductive hormone kisspeptin directly stimulates osteoblast differentiation in vitro and thus could have clinical therapeutic potential. However, the effects of kisspeptin on human bone metabolism are currently unknown., Objective: To assess the effects of kisspeptin on human bone metabolism in vitro and in vivo., Methods: In vitro study: of Mono- and cocultures of human osteoblasts and osteoclasts treated with kisspeptin. Clinical study: Randomized, placebo-controlled, double-blind, 2-way crossover clinical study in 26 men investigating the effects of acute kisspeptin administration (90 minutes) on human bone metabolism, with blood sampling every 30 minutes to +90 minutes. Cells for the in vitro study were from 12 male blood donors and 8 patients undergoing hip replacement surgery. Twenty-six healthy eugonadal men (age 26.8 ± 5.8 years) were included in the clinical study. The intervention was Kisspeptin (vs placebo) administration. The main outcome measures were changes in bone parameters and turnover markers., Results: Incubation with kisspeptin in vitro increased alkaline phosphatase levels in human bone marrow mesenchymal stem cells by 41.1% (P = .0022), and robustly inhibited osteoclastic resorptive activity by up to 53.4% (P < .0001), in a dose-dependent manner. Kisspeptin administration to healthy men increased osteoblast activity, as evidenced by a 20.3% maximal increase in total osteocalcin (P = .021) and 24.3% maximal increase in carboxylated osteocalcin levels (P = .014)., Conclusion: Collectively, these data provide the first human evidence that kisspeptin promotes osteogenic differentiation of osteoblast progenitors and inhibits bone resorption in vitro. Furthermore, kisspeptin acutely increases the bone formation marker osteocalcin but not resorption markers in healthy men, independent of downstream sex steroid levels. Kisspeptin could therefore have clinical therapeutic application in the treatment of osteoporosis., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society.)