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Background: The present study aimed at determining pericytes, a missing component in the previously proposed living neurovascular unit (NVU) of the sexually dimorphic nucleus of the preoptic area (SDN-POA) in rats. Materials and Mehods: Calbindin D28K-immunoreactivities (CB28-irs) were used to delineate the SDN-POA in which CD13-immunoreactivities (CD13-irs) or alpha-smooth muscle actinimmunoreactivities (αSMA-irs), two pericyte biomarkers serving the indexes of pericytes, were tagged using two adjacent brain sections (90-micron intervals). In addition, the nestinimmunoreactive (nestin-ir) cells in the SDN-POA were counted as pericytes referring to additional standards: location and nucleic and cellular morphology. Male SDN-POA volume (5.0±0.3x10-3 mm3) was significantly larger than the female (1.7±0.3x10-3 mm3). Within the SDN-POA, the CD13-irs were characterized as dots, densely packed and net-like in distribution, while the αSMAirs, excluding pipe-like or circular structures, appeared as short rod-like structures that were sparsely distributed. Results: The immunoreactive counts of alpha-smooth muscle actin were 353±57/mm2 in males and 124±46/mm2 in females (p Conclusion: In conclusion, the present study adds new information concerning pericytes to the living NVU of the SDN-POA. There is a difference of sex in the count of the αSMA-irs in the living NVU of the SDN-POA. However, why such a difference exists warrants further investigations. more...

Background Bisphenol A is well known endocrine-disrupting chemical while Bisphenol S was considered a safe alternative. The present study aims to examine the comparative effects of xenobiotic bisphenol-A (BPA) and its substitute bisphenol-S (BPS) on spermatogenesis and development of sexually dimorphic nucleus population of dopaminergic neurons in the anteroventral periventricular nucleus (AVPV) of the hypothalamus in male pups. Methods Sprague Dawley rat’s pups were administered subcutaneously at the neonatal stage from postnatal day PND1 to PND 27. Thirty animals were divided into six experimental groups (6 animals/group). The first group served as control and was provided with normal olive oil. The four groups were treated with 2 μg/kg and 200 μg/kg of BPA and BPS, respectively. The sixth group was given with 50 μg/kg of estradiol dissolved in olive oil as a standard to find the development of dopaminergic tyrosine hydroxylase neurons in AVPV regions. Histological analysis for testicular tissues and immunohistochemistry for brain tissues was performed. Results The results revealed adverse histopathological changes in testis after administration of different doses of BPA and BPS. These degenerative changes were marked by highly significant (p more...

The intermediate nucleus of Brockhaus (INH), also known as the interstitial nucleus of the anterior hypothalamus-1 of Allen and Gorski (INAH-1), the sexually dimorphic nucleus of Swaab and colleagues (SDN), and the ventrolateral preoptic nucleus of Saper and colleagues (VLPO), is a cluster of largely galanin-expressing neurons in the lateral preoptic area, at the level of the crossing of the anterior commissure and dorsal to the supraoptic nucleus. The number of Nissl-stained neurons in the INH has been reported to be larger in men than women and to decrease with aging, although these findings have been controversial, in part because of differences in patient populations and methods used to assess the nucleus. However, recent studies have confirmed that the number of galanin-immunoreactive INH neurons is larger in men than women and decreases with age and have reported further loss with Alzheimer disease. The galanin-immunoreactive VLPO neurons have been thought to drive sleep behavior in many species, and their numbers in older humans correlate with the amount of consolidated sleep they experience. Sleep differences between men and women, during aging, and with Alzheimer disease may also depend upon the integrity of this nucleus. more...

It is the heterogeneous changes of hypothalamic functions that determine the chronological sequence of aging in mammals. Recently, it was hypothesized by Cai the decrease in slow-wave sleep (SWS) resulting from skin aging as responsible for the degeneration of hypothalamic suprachiasmatic nucleus (SCN). It was soon hypothesized by the European people in television that the increase in body fat as responsible for the degeneration of male preoptic sexually dimorphic nucleus (SDN-POA), via the aromatase converting testosterone to estradiol as proposed by Cohen. It is the hypothalamic paraventricular nucleus (PVN) that remains unchanged in neuron number during aging for psychological stress. In this chapter, it is briefly reviewed more manifestations of hypothalamic related mammalian aging processes, including (1) the aging of ovary by lipid, estradiol and hypothalamus; (2) the aging of muscle, stomach, intestine, thymus, and the later aging of brain, regulated by growth hormone/insulin-like growth factor 1(GH/IGF1); (3) the cardiovascular hypertension from PVN activation, the bone and other peripheral aging by psychological stress, and that of kidney by vasopressin. It is classified these aging processes by the primary regulation from one of the three hypothalamic nuclei, although still necessary to investigate and supplement their secondary regulation by the hypothalamic nuclei in future. It is the hypothalamic structural changes that shift the functional balance among these three hypothalamic systems toward aging. more...

Klinefelter syndrome (KS; 47,XXY) impacts neurodevelopment and is associated with an increased risk of cognitive, psychological and social impairments, although significant heterogeneity in the neurodevelopmental profile is seen. KS is characterized by a specific cognitive profile with predominantly verbal deficits, preserved function in non-verbal and visuo-spatial domains, executive dysfunction and social impairments, and by an increased vulnerability toward psychiatric disorders. The neurobiological underpinnings of the observed neuropsychological profile have not been established. A distinct pattern of both global and regional brain volumetric differences has been demonstrated in addition to preliminary findings of functional brain alterations related to auditory, motor, language and social processing. When present, the combination of cognitive, psychological and social challenges has the potential to negatively affect quality of life. This review intends to provide information and insight to the neuropsychological outcome and brain correlates of KS. Possible clinical intervention and future directions of research will be discussed. more...

It is well known that the hypothalamic changes in control of hormones determine the chronological sequence of aging in mammals. For decades, it has been demonstrated in humans that the hypothalamic nuclei manifest heterogeneity in degeneration during aging, with the neuron number decreasing in both the suprachiasmatic nucleus (SCN) and the preoptic sexually dimorphic nucleus (SDN-POA) in the process of senescence, while the neuron number remains unchanged in the paraventricular nucleus (PVN). Recently, it was newly hypothesized some peripheral mechanisms responsible for the senescent changes of the hypothalamic nuclei. It was proposed by Cai that the decrease in slow-wave sleep (SWS) caused the degeneration of the suprachiasmatic nucleus (SCN). Besides, when reviewing the proposal by the European people in television about the senescent pathway for male reproduction on the degeneration of hypothalamic preoptic area by the common knowledge of reduction of sperm production from adipose accumulation in the middle/old age, it was as well demonstrated that the reduced testosterone level from the increased body fat caused the degeneration of the male preoptic sexually dimorphic nucleus (SDN-POA). It seems both the activity-dependent and hormonal regulation of the neuronal numbers are involved in the mechanisms causing the senescence of the hypothalamic nuclei. It is further pointed out that the paraventricular nucleus (PVN) maintaining its neuronal number unchanged in aging may cause many cellular and molecular changes of aging from chronic stress. It is expected that these preliminary considerations could elicit more investigations on the other peripheral causes for the hypothalamic aging, such as the cholesterol, hypertension, and so on. more...

Bisphenol A (BPA) is a high volume endocrine disrupting chemical found in a wide variety of products including plastics and epoxy resins. Human exposure is nearly ubiquitous, and higher in children than adults. Because BPA has been reported to interfere with sex steroid hormone signaling, there is concern that developmental exposure, even at levels below the current FDA No Observed Adverse Effect Level (NOAEL) of 5 mg/kg body weight (bw)/day, can disrupt brain sexual differentiation. The current studies were conducted as part of the CLARITY-BPA (Consortium Linking Academic and Regulatory Insights on BPA Toxicity) program and tested the hypothesis that perinatal BPA exposure would induce morphological changes in hormone sensitive, sexually dimorphic brain regions. Sprague-Dawley rats were randomly assigned to 5 groups: BPA (2.5, 25, or 2500 µg/kg bw/day), a reference estrogen (0.5 µg ethinylestradiol (EE2)/kg bw/day), or vehicle. Exposure occurred by gavage to the dam from gestational day 6 until parturition, and then to the offspring from birth through weaning. Unbiased stereology was used to quantify the volume of the sexually dimorphic nucleus (SDN), the anteroventral periventricular nucleus (AVPV), the posterodorsal portion of the medial amygdala (MePD), and the locus coeruleus (LC) at postnatal day 28. No appreciable effects of BPA were observed on the volume of the SDN or LC. However, AVPV volume was enlarged in both sexes, even at levels below the FDA NOAEL. Collectively, these data suggest the developing brain is vulnerable to endocrine disruption by BPA at exposure levels below previous estimates by regulatory agencies. more...

We recently reported a female-biased sexually dimorphic area in the mouse brain in the boundary region between the preoptic area and the bed nucleus of the stria terminalis (BNST). We reexamined this area and found that it is a ventral part of the principal nucleus of the BNST (BNSTp). The BNSTp is a male-biased sexually dimorphic nucleus, but the ventral part of the BNSTp (BNSTpv) exhibits female-biased sex differences in volume and neuron number. The volume and neuron number of the BNSTpv were increased in males by neonatal orchiectomy and decreased in females by treatment with testosterone, dihydrotestosterone, or estradiol within 5 days after birth. Sex differences in the volume and neuron number of the BNSTpv emerged before puberty. These sex differences became prominent in adulthood with increasing volume in females and loss of neurons in males during the pubertal/adolescent period. Prepubertal orchiectomy did not affect the BNSTpv, although prepubertal ovariectomy reduced the volume increase and induced loss of neurons in the female BNSTpv. In contrast, the volume and neuron number of male-biased sexually dimorphic nuclei that are composed of mainly calbindin neurons and are located in the preoptic area and BNST were decreased by prepubertal orchiectomy but not affected by prepubertal ovariectomy. Testicular testosterone during the postnatal period may defeminize the BNSTpv via binding directly to the androgen receptor and indirectly to the estrogen receptor after aromatization, although defeminization may proceed independently of testicular hormones in the pubertal/adolescent period. Ovarian hormones may act to feminize the BNSTpv during the pubertal/adolescent period. more...

The calbindin-sexually dimorphic nucleus (CALB-SDN) and calbindin-principal nucleus of the bed nucleus of the stria terminalis (CALB-BNSTp) show male-biased sex differences in calbindin neuron number. The ventral part of the BNSTp (BNSTpv) exhibits female-biased sex differences in noncalbindin neuron number. We previously reported that prepubertal gonadectomy disrupts the masculinization of the CALB-SDN and CALB-BNSTp and the feminization of the BNSTpv. This study aimed to determine the action mechanisms of testicular androgens on the masculinization of the CALB-SDN and CALB-BNSTp and whether ovarian estrogens are the hormones that have significant actions in the feminization of the BNSTpv. We performed immunohistochemical analyses of calbindin and NeuN, a neuron marker, in male mice orchidectomized on postnatal day 20 (PD20) and treated with cholesterol, testosterone, estradiol, or dihydrotestosterone during PD20-70, female mice ovariectomized on PD20 and treated with cholesterol or estradiol during PD20-70, and PD70 mice gonadectomized on PD56. Calbindin neurons number in the CALB-SDN and CALB-BNSTp in males treated with testosterone or dihydrotestosterone, but not estradiol, was significantly larger than that in cholesterol-treated males. Noncalbindin neuron number in the BNSTpv in estradiol-treated females was significantly larger than that in cholesterol-treated females. Gonadectomy on PD56 had no significant effect on neuron numbers. Additionally, an immunohistochemical analysis revealed the expression of androgen receptors in the CALB-SDN and CALB-BNSTp of PD30 males and estrogen receptors-α in the BNSTpv of PD30 females. These results suggest that peripubertal testicular androgens act to masculinize the CALB-SDN and CALB-BNSTp without aromatization, and peripubertal ovarian estrogens act to feminize the BNSTpv. more...

Evidence suggests that the hypothalamic–pituitary–gonadal (HPG) axis is active during the critical period for sexual differentiation of the ovine sexually dimorphic nucleus, which occurs between gestational day (GD) 60 and 90. Two possible neuropeptides that could activate the fetal HPG axis are kisspeptin and neurokinin B (NKB). We used GD85 fetal lambs to determine whether intravenous administration of kisspeptin-10 (KP-10) or senktide (NKB agonist) could elicit luteinizing hormone (LH) release. Immunohistochemistry and fluorescent in situ hybridization (FISH) were employed to localize these peptides in brains of GD60 and GD85 lamb fetuses. In anesthetized fetuses, KP-10 elicited robust release of LH that was accompanied by a delayed rise in serum testosterone in males. Pretreatment with the GnRH receptor antagonist (acyline) abolished the LH response to KP-10, confirming a hypothalamic site of action. In unanesthetized fetuses, senktide, as well as KP-10, elicited LH release. The senktide response of females was greater than that of males, indicating a difference in NKB sensitivity between sexes. Gonadotropin-releasing hormone also induced a greater LH discharge in females than in males, indicating that testosterone negative feedback is mediated through pituitary gonadotrophs. Kisspeptin and NKB immunoreactive cells in the arcuate nucleus were more abundant in females than in males. Greater than 85% of arcuate kisspeptin cells costained for NKB. FISH revealed that the majority of these were kisspeptin/NKB/dynorphin (KNDy) neurons. These results support the hypothesis that kisspeptin–GnRH signaling regulates the reproductive axis of the ovine fetus during the prenatal critical period acting to maintain a stable androgen milieu necessary for brain masculinization. more...

The medial preoptic area (mPOA) of the hypothalamus is sexually dimorphic and controls sexually dimorphic display of male mating and parental care. Yet, despite extensive characterization of sex differences in the mPOA, we know surprisingly little about whether or how male and female mPOA neurons differ electrophysiologically, which relate more directly to neuronal firing and behavioral pattern generation. In this study, we performed whole-cell patch clamp recordings of the mPOA in acute brain slices cut from virgin adult mice, and compared in total 29 electrophysiological parameters between male and female mPOA neurons. We find that resting membrane potential (Vm), input resistance (Rm), time constant (τm), threshold (Vth) and minimum current (rheobase) required to generate an action potential differ significantly between male and female in a cell-type dependent manner. Nonetheless, there is little evidence for profuse sex differences in neuronal excitability, except for a higher probability of rebound neurons in males. Depletion of male gonadal hormones in adulthood partially de-masculinizes sexually dimorphic electrophysiological parameters, suggesting that some of these sex differences may establish during development. Furthermore, as a demonstration of the behavioral relevance of these sex differences, we show that pharmacologic blockage of currents mediated by T-type Ca2+ channel, which underlie rebound and tends to be larger in male mPOA neurons, result in behavioral deficits in male mating. In summary, we have identified key sex differences in electrophysiological properties of mPOA neurons that likely contribute to sexually dimorphic display of behaviors.Significance StatementSex represents an important biological variable that impact an individual’s behaviors, physiology and disease susceptibility. Indeed, sex differences in the nervous system manifest across many different levels and scales. Yet, throughout previous multifaceted investigations on sex differences in the brain, electrophysiological characterizations, which could potentially bridge cellular and molecular sex differences with sexually dimorphic brain functions and behaviors, remains scant. Here, focusing on an evolutionarily conserved sexually dimorphic nucleus, we investigated sex differences in electrophysiological properties of mPOA neurons and its modulation by gonadal hormones in adult males via in vitro whole-cell patch clamp. As a result, we identified novel sex differences in electrophysiological properties that likely contribute to sexually dimorphic display of behaviors and physiological functions. more...

Made available in DSpace on 2020-12-12T01:53:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-03-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Ibuprofen, a non-steroidal anti-inflammatory drug, inhibits the activity of cyclooxygenase enzyme, leading to reduction in Prostaglandin E2 (PGE2) production. Due to the importance of PGE2 in promoting the brain masculinization in male fetus, this study aimed to evaluate the effects of in utero and lactational exposure to ibuprofen and their late repercussions on reproductive parameters in male rats. Pregnant rats were exposed to ibuprofen (10, 30 or 60 mg/kg) or vehicle (control group) per gavage daily from gestational day 15 to day 21 after birth, and late reproductive effects were assessed during the sexual development and in the reproductive adult life in the male offspring. Males exposed to ibuprofen had a decrease in body weight and anogenital distance, as well as a delay in the ages of testicular descent and preputial separation. In adulthood, there was a decrease in the Leydig cells nuclei volume, testosterone levels and percentage of normal sperm morphology. All animals exposed to ibuprofen presented male copulatory behavior, however, in the presence of another male, they also presented a female-typical behavior. Maternal exposure to ibuprofen during the sensitive windows of brain development adversely impacted the reproductive parameters of male rats, suggesting an incomplete masculinization of the hypothalamus. Department of Morphology Institute of Biosciences of Botucatu Univ. Estadual Paulista Department of Animal Reproduction Faculty of Veterinary Medicine Univ. Estadual Paulista (UNESP) Department of Pharmacology Institute of Biosciences of Botucatu Univ. Estadual Paulista (UNESP) Department of Anatomy Institute of Biosciences of Botucatu Univ. Estadual Paulista (UNESP) Center of Toxicological Assistance (CEATOX) Institute of Biosciences of Botucatu Univ. Estadual Paulista Department of Animal Reproduction Faculty of Veterinary Medicine Univ. Estadual Paulista (UNESP) Department of Pharmacology Institute of Biosciences of Botucatu Univ. Estadual Paulista (UNESP) Department of Anatomy Institute of Biosciences of Botucatu Univ. Estadual Paulista (UNESP) FAPESP: 2016/12110-3 FAPESP: 2017/03997-7 more...

The medial preoptic area, which plays an essential role in the control of sexual behavior in rats, contains a sexually dimorphic nucleus that consists of neurons expressing calbindin-D28 K (Calb) that is referred to as the CALB-SDN. The CALB-SDN is larger and contains more Calb neurons in males than in females. The physiological functions of the CALB-SDN are not fully understood; however, CALB-SDN neurons are activated during sexual behavior in males, suggesting that the male CALB-SDN is involved in regulation of sexual behavior. However, no information exists about the physiological functions of the female CALB-SDN. In the present study, we performed an immunohistochemical analysis of c-Fos, a neuronal activity marker, in the CALB-SDN of female and male rats that had copulated with conspecifics of the opposite sex to determine whether neurons of the female CALB-SDN are activated during copulation and whether the neuronal activity of the CALB-SDN differs between sexes. The numbers of c-Fos-immunoreactive cells with or without Calb-immunoreactivity (c-Fos+/Calb+ and c-Fos+/Calb− cells) were greater in the CALB-SDN of rats that had copulated than in rats that had not copulated in each sex. Although the number of Calb+ cells in the CALB-SDN was smaller in females than in males, the increase in the number of c-Fos+/Calb+ cells in the female CALB-SDN with copulation was comparable to that in the male CALB-SDN with copulation. The increase in the number of c-Fos+/Calb− cells in the CALB-SDN with copulation was more prominent in males than in females. These results suggest that CALB-SDN neurons are activated during copulation in both sexes. The patterns of neuronal activation in the CALB-SDN during copulation may differ between sexes. more...

Testosterone and its metabolites masculinize the brain during a critical perinatal window, including the relative volume of sexually dimorphic brain areas such as the sexually dimorphic nucleus of the preoptic area (SDN), which is larger in males than females. Serotonin (5HT) may mediate this hormone action, since 5HT given during the second week of life decreases (i.e., feminizes) SDN volume in males and testosterone-treated females. Although previous work indicates that the 5HT2A/2C receptor is sufficient to induce feminization, it is unclear whether other serotonin receptors are required and which subpopulation(s) of SDN cells are specifically organized by 5HT. Therefore, we injected male and female Sprague-Dawley rat pups with saline, a nonselective 5HTR agonist, a 5HT2A/2C agonist, or a 5HT2A/2C antagonist over several timecourses in early life, and measured the Nissl-SDN as well as a calbindin+ subdivision of the SDN, the CALB-SDN. When examined on postnatal day 18 or early adulthood, the size of the Nissl-SDN was feminized in males treated with any of the serotonergic drugs, eliminating the typical sex difference. In contrast, the sex difference in CALB-SDN size was maintained regardless of serotoninergic drug treatment. This pattern suggests that although gonadal hormones shape the whole SDN, individual cellular phenotypes respond to different intermediary signals to become sexually dimorphic. Specifically, 5HT mediates sexual differentiation of non-calbindin population(s) within the SDN. The results also caution against using measurement of the CALB-SDN in isolation, as the absence of an effect on the CALB-SDN does not preclude an effect on the overall nucleus. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1241-1253, 2016. more...

Estrogens exert pleiotropic effects on multiple physiological and behavioral responses. Male and female sexual behavior in rodents constitutes some of the best-characterized responses activated by estrogens in adulthood and largely depend on ERα. Evidence exists that nucleus- and membrane-initiated estrogen signaling cooperate to orchestrate the activation of these behaviors both in short- and long-term. However, questions remain regarding the mechanism(s) and receptor(s) involved in the early brain programming during development to organize the circuits underlying sexually differentiated responses. Taking advantage of a mouse model harboring a mutation of the ERα palmitoylation site, which prevents membrane ERα signaling (mERα; ERα-C451A), this study investigated the role of mERα on the expression of male and female sexual behavior and neuronal populations that differ between sexes. The results revealed no genotype effect on the expression of female sexual behavior, while male sexual behavior was significantly reduced, but not abolished, in males homozygous for the mutation. Similarly, the number of kisspeptin- (Kp-ir) and calbindin-immunoreactive (Cb-ir) neurons in the anteroventral periventricular nucleus (AVPv) and the sexually dimorphic nucleus of the preoptic area (SDN-POA), respectively, were not different between genotypes in females. In contrast, homozygous males showed increased numbers of Kp-ir and decreased numbers of Cb-ir neurons compared to wild-types, thus leading to an intermediate phenotype between females and wild-type males. Importantly, females neonatally treated with estrogens exhibited the same neurochemical phenotype as their corresponding genotype among males. Together, these data provide evidence that mERα is involved in the perinatal programming of the male brain. more...

Sexuality is an important component of human personality and behavior. Its development follows a multifactorial model, since psychological, biological, and sociocultural characteristics play a major role. The majority of basic research mainly comes from animals, while epigenetic, cognitive, and sociocultural factors play an important role in humans. The hypothalamus seems to be the main brain structure involved in sexual behavior, while various of its areas such as the sexually dimorphic nucleus of the preoptic area, the median preoptic area, the ventromedial nucleus, the bed nucleus of the stria terminalis, etc. are sexually differentiated in humans. Androgenization is mainly based on steroid action during the sensitive period of brain development in the fetus, while also other factors (e.g., hormone and neurotransmitter metabolism) play a role in the development of sexual identity and orientation. Central nervous system dimorphisms regarding the regions that modulate sexual function are also a biological basis for the differences in sexual desire, arousal, and orgasm. Hypothalamic structures, limbic and cortical areas, are activated and deactivated during all the phases of the sexual response cycle, while the role of hormones, neurotransmitters, and its receptors is crucial. more...

The medial preoptic nucleus (MPN) plays an essential role in the control of male sexual behavior. In rats, the central part of the MPN (MPNc) contains a sexually dimorphic nucleus exhibiting male-biased morphological sex differences. Although it has been suggested that the MPNc of male rats functions to induce sexual arousal, the mechanisms by which male rats are sexually aroused to successfully achieve copulation are poorly understood. We recently showed that increased neuronal activity in the MPNc of male rats during copulation is higher at their first copulation compared with later copulations, indicating that a plastic change in excitatory synaptic transmission occurs with copulatory experience. In this study, we tested the hypothesis that changes to dendritic spines at structural and molecular levels occur following copulatory experience. First, we examined the effects of at least two copulations on the morphology of dendrites and spines in the MPNc and in the lateral and medial parts of the MPN (MPNlm) of male rats. In the MPNc, the total number of dendrites and their branches, and the surface area of dendrites were not significantly affected by copulation. However, the copulatory experience, specifically experience of ejaculation, significantly reduced the density of mushroom spines but not of filopodia, thin or stubby spines in the MPNc. In the MPNlm, the copulatory experience, specifically experience of ejaculation, significantly increased the surface area of dendrites, although there was no significant effect of copulation on spine density. Next, we measured the mRNA levels of genes encoding actin-binding proteins related to spinogenesis after male rats had copulated for their first and second times. Copulatory stimuli, especially stimuli from ejaculation, significantly reduced the mRNA levels of drebrin A and spinophilin in the MPNc but not in the MPNlm. These results indicate that copulatory experiences, especially experience of ejaculation, reduce spine density in the MPNc of male rats, which may result, in part, from downregulation of genes encoding actin-binding proteins. more...

The medial preoptic area (MPN) plays an important role in the control of male sexual behavior. In rats, the central part of the MPN (MPNc) is sexually dimorphic and contains a sexually dimorphic nucleus composed of neurons expressing calbindin-D28 K (CALB-SDN). Although the functions of the MPNc are not well understood, surgical destruction of the MPNc adversely affects the performance of sexual behavior in sexually naive males, but not in sexually experienced males, supporting the notion that the MPNc changes functionally with sexual experience. In this study, we aimed to determine the effects of sexual experience on the neuronal activity of the MPNc and CALB-SDN. Sexual behavior in sexually inexperienced males that had no experience of ejaculation, and experienced males that had ejaculated once was observed. After they displayed sexual behavior, the brains were sampled, and immunohistochemical analysis of c-Fos, a neuronal activity marker, in the MPNc and CALB-SDN was performed. The numbers of c-Fos-immunopositive cells with or without calbindin-D28K-immunoreactivity increased significantly in the MPNc and CALB-SDN following ejaculation in both sexually inexperienced and experienced males, although the numbers did not change significantly with exposure to estrous female odors, the first mount, and the first intromission before and after the first ejaculation. We further found that the number of c-Fos-immunopositive and calbindin-D28K-immunonegative cells in the MPNc, but not in the CALB-SDN, was significantly smaller in sexually experienced males than in sexually inexperienced males. These results suggest that a population of MPNc neurons, which is located outside the CALB-SDN and do not express calbindin-D28 K, are activated during the first copulation and then silent after acquisition of sexual experience. more...

Sexually dimorphic neural structures regulate numerous gender-specific functions including luteinizing hormone (LH) release patterns. The female cyclic surge pattern of release is controlled by the anteroventral periventricular nucleus (AVPV), a preoptic area (POA) region that is significantly smaller in males. The prevailing hypothesis used to explain these differences in structure and function is that a "default" feminine AVPV is defeminized by exposure to estradiol (E2), a metabolite of testosterone (T) produced by the perinatal testes. E2 exposure then culminates in apoptosis in the male AVPV, but the upstream pathways are poorly understood. To address this issue, we compared AVPV transcriptomes of postnatal day 2 (PND2) males and females with those of females treated with E2 or vehicle. Only six of 89 sex-specific genes were also regulated by E2 in the PND2 AVPV and E2 regulated over 280 genes not found to be sex-specific. Of targets that changed similarly in males and E2-treated females, the gene encoding CUG triplet repeat, RNA-binding protein 2 (Cugbp2), a proapoptotic protein, showed the highest fold-changes. Quantitative polymerase chain reaction (QPCR) studies confirmed higher mRNA levels in PND2 male and E2-treated female AVPVs wherein E2 induces apoptosis. POA mapping studies detected Cugbp2 mRNA in the AVPV and in the sexually dimorphic nucleus of the POA (SDN-POA); however, sex differences and E2 effects occurred only in the AVPV. Combined with evidence that Cugbp2 regulates splicing and translation of mRNAs linked to sexual differentiation, we propose that this gene mediates E2-dependent effects on AVPV defeminization. more...

Submitted by PAOLA DA SILVA BALIN (paolasilvabalin@gmail.com) on 2018-04-19T09:06:18Z No. of bitstreams: 1 Dissertação_PAOLA_BALIN_final.pdf: 4151020 bytes, checksum: b273a627e9417be79a8432d3b964e7c5 (MD5) Approved for entry into archive by ROSANGELA APARECIDA LOBO null (rosangelalobo@btu.unesp.br) on 2018-04-20T18:07:06Z (GMT) No. of bitstreams: 1 balin_ps_me_bot_par.pdf: 756262 bytes, checksum: 5db429f57597b440c2ec1701853dd7e3 (MD5) Made available in DSpace on 2018-04-20T18:07:06Z (GMT). No. of bitstreams: 1 balin_ps_me_bot_par.pdf: 756262 bytes, checksum: 5db429f57597b440c2ec1701853dd7e3 (MD5) Previous issue date: 2018-02-20 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Os anti-inflamatórios não esteroidais (AINEs), entre eles o Ibuprofeno, são amplamente utilizados para o tratamento da dor e de processos inflamatórios, e estão entre as classes de medicamentos mais utilizadas por gestantes. Através da inibição da enzima ciclo-oxigenase, os AINEs inibem a síntese de prostaglandinas, compostos eicosanoides que atuam não somente como mediadores e moduladores inflamatórios, mas também em diversos processos fisiológicos do organismo, como no mecanismo de diferenciação sexual hipotalâmica. O processo de masculinização do hipotálamo é dependente de testosterona, que por ação da enzima citocromo P450 aromatase, é convertida em estradiol. Este hormônio regula positivamente a expressão da enzima ciclo-oxigenase no hipotálamo, aumentando a produção de prostaglandina do subtipo E2 (PGE2), que atua aumentando a formação de espinhas dendríticas no núcleo sexualmente dimórfico da área pré-optica (SDN-POA). Em virtude da importância da PGE2 no processo de diferenciação sexual hipotalâmica, torna-se preocupante o uso de anti-inflamatórios durante a gestação. Desta forma, o objetivo desse estudo foi avaliar os possíveis efeitos resultantes da exposição in utero e lactacional ao ibuprofeno e suas repercussões tardias sobre parâmetros reprodutivos masculinos em ratos machos. Para tanto, ratas prenhes foram expostas a três doses de ibuprofeno (10; 30; 60 mg/kg) entre a última semana de prenhez (Dias gestacionais 15-21) até o final da lactação (Dias pós-natal 21) por gavage. Durante o tratamento, foram monitorados o consumo de água e ração, massa corporal e comportamento materno das ratas expostas. Após o desmame, coletou-se o sangue das mães para análises bioquímicas e órgãos para registro do peso. Após o nascimento, os filhotes machos foram avaliados através dos seguintes parâmetros: massa corporal, distância anogenital e idades de descida testicular e separação prepucial. Na vida adulta, estes mesmos animais foram investigados em relação a parâmetros comportamentais (comportamento sexual masculino e feminino e preferência sexual), fertilidade, parâmetros espermáticos (contagem, motilidade e morfologia espermática), pesos de órgãos reprodutores, dosagem hormonal, quantificação do volume do SDN-POA e histologia de testículo e epidídimo. O tratamento com ibuprofeno não alterou os parâmetros maternos avaliados. A prole masculina apresentou redução na massa corporal e na distância anogenital, bem como, atraso nas idades de descida testicular e separação prepucial. Na vida adulta, os animais apresentaram redução nos níveis séricos de testosterona e no volume do núcleo de célula de Leydig. A exposição ao ibuprofeno não alterou os pesos dos órgãos reprodutores, a contagem espermática, a fertilidade ou o número de células de Sertoli, entretanto causou diminuição no número de espermatozoides normais. Em relação aos parâmetros comportamentais, os animais expostos ao ibuprofeno apresentaram tanto comportamento sexual masculino quanto feminino, contudo não houve alteração em relação ao padrão de preferência sexual. O volume total do SDN-POA não foi alterado. Concluiu-se que o ibuprofeno, nestas condições experimentais, foi capaz de perturbar a programação do eixo hipotálamo-hipófise-gônada, afetou a maturação sexual e as funções reprodutivas masculinas. Non-steroidal anti-inflammatory drugs (NSAID), including Ibuprofen, are widely used in the treatment of pain and inflammatory processes, and are of the most commonly classes of drugs used by pregnant women. By inhibiting the cyclooxygenase enzyme (COX), NSAID inhibit the synthesis of prostaglandins, eicosanoids compounds that act not only as mediators and inflammatory modulators, but also in various physiological processes of the organism, such as in the mechanism of sexual hypothalamic differentiation. The hypothalamus masculinization process is testosterone dependent, which by action of the aromatase cytochrome P450 enzyme is metabolized to estradiol. This hormone upregulates the expression of COX enzyme in the hypothalamus, increasing the production of prostaglandin E2, which acts by increasing the formation of dendritic spines in the neurons of the sexually dimorphic nucleus of the preoptic area in males (SDN-POA). Due to the importance of prostaglandin E2 in the process of hypothalamic sexual differentiation, the use of anti-inflammatory drugs during pregnancy is of concern. Thus, the aim of this study was to evaluate the possible effects resulting from in utero and lactation exposure to non-steroidal anti-inflammatory ibuprofen and its late repercussions on male reproductive parameters in male rats. For this, pregnant rats were exposed to three doses of ibuprofen (10; 30; 60 mg/kg) between the last week of pregnancy (Gestational Days 15-21) until the end of lactation (Postnatal Days 21) by gavage. During treatment, water consumption, food intake, body weight and maternal behavior of the dams were monitored. After weaning, blood samples was collected for biochemical analyzes and organs for weight recording. After birth, male offspring were evaluated through the following parameters: body weight, anogenital distance and ages of testicular descent and preputial separation. In the adult life, these same animals were investigated in relation to behavioral parameters (male and female sexual behavior and sexual preference), fertility, sperm parameters (sperm count, sperm motility and sperm morphology), reproductive organ weights, hormonal levels, volume of the SDN-POA and histology of testis and epididymis. Treatment did not affect any of the maternal parameters evaluated. Male offspring presented reduction in body weight and anogenital distance, as well as delay in the ages of testicular descent and preputial separation. In adulthood, these animals showed reduced serum testosterone levels and the volume of Leydig cell nucleus. Exposure to ibuprofen did not alter reproductive organ weights, sperm count, fertility or the number of Sertoli cells; however it resulted in a decrease in the number of normal sperm. Regarding the behavioral parameters, the animals exposed to ibuprofen presented both male and female sexual behavior, but there was no change in relation to the pattern of sexual preference. The total volume of the sexually dimorphic nucleus of the preoptic area was not altered. It was concluded that ibuprofen, under these experimental conditions, was able to disturb the hypothalamic-pituitary-gonadal axis programming, affected sexual maturation and male reproductive functions. more...

Sexual identity and sexual orientation are independent components of a person's sexual identity. These dimensions are most often in harmony with each other and with an individual's genital sex, although not always. The present review discusses the relationship of sexual identity and sexual orientation to prenatal factors that act to shape the development of the brain and the expression of sexual behaviours in animals and humans. One major influence discussed relates to organisational effects that the early hormone environment exerts on both gender identity and sexual orientation. Evidence that gender identity and sexual orientation are masculinised by prenatal exposure to testosterone and feminised in it absence is drawn from basic research in animals, correlations of biometric indices of androgen exposure and studies of clinical conditions associated with disorders in sexual development. There are, however, important exceptions to this theory that have yet to be resolved. Family and twin studies indicate that genes play a role, although no specific candidate genes have been identified. Evidence that relates to the number of older brothers implicates maternal immune responses as a contributing factor for male sexual orientation. It remains speculative how these influences might relate to each other and interact with postnatal socialisation. Nonetheless, despite the many challenges to research in this area, existing empirical evidence makes it clear that there is a significant biological contribution to the development of an individual's sexual identity and sexual orientation. more...

The ovine sexually dimorphic nucleus (oSDN) is 2 times larger in rams than in ewes. Sexual differentiation of the oSDN is produced by testosterone exposure during the critical period occurring between gestational day (GD)60 and GD90 (term, 147 d). We tested the hypothesis that testosterone acts through the androgen receptor to control development of the male-typical oSDN. In experiment 1, pregnant ewes received injections of vehicle, androgen receptor antagonist flutamide, or nonaromatizable androgen dihydrotestosterone (DHT) propionate during the critical period. Fetuses were delivered at GD135. Both antagonist and agonist treatments significantly reduced mean oSDN volume in males but had no effects in females. Experiment 2, we analyzed the effect of treatments on the fetal hypothalamic-pituitary-gonadal axis to determine whether compensatory changes in hormone secretion occurred that could explain the effect of DHT. Pregnant ewes were injected with vehicle, flutamide, or DHT propionate from GD60 to GD84, and fetuses were delivered on GD85. Flutamide significantly increased LH and testosterone in males, whereas DHT significantly decreased both hormones. In females, LH was unaffected by flutamide but significantly reduced by DHT exposure. DHT significantly decreased pituitary gonadotropin and hypothalamic kisspeptin mRNA expression in males and females. These results suggest that androgen receptor mediates the effect of testosterone on oSDN masculinization, because this process was blocked by the androgen receptor antagonist flutamide in eugonadal males. In contrast, the reduction of oSDN volume observed after DHT exposure appears to be mediated by a negative feedback mechanism exerted on the hypothalamus to reduce LH and testosterone secretion. The reduced androgen exposure most likely accounted for the decreased oSDN volume. We conclude that, during the critical period, the male reproductive axis in long gestation species, such as sheep, is sufficiently developed to react to perturbations in serum androgens and mitigate disruptions in brain masculinization. more...

The developing central nervous system may be particularly sensitive to bisphenol A (BPA)-induced alterations. Here, pregnant Sprague Dawley rats (n = 11–12/group) were gavaged daily with vehicle, 2.5 or 25.0 μg/kg BPA, or 5.0 or 10.0 μg/kg ethinyl estradiol (EE2) on gestational days 6–21. The BPA doses were selected to be below the no-observed-adverse-effect level (NOAEL) of 5 mg/kg/day. On postnatal days 1–21, all offspring/litter were orally treated with the same dose. A naïve control group was not gavaged. Body weight, pubertal age, estrous cyclicity, and adult serum hormone levels were measured. Adolescent play, running wheel activity, flavored solution intake, female sex behavior, and manually elicited lordosis were assessed. No significant differences existed between the vehicle and naïve control groups. Vehicle controls exhibited significant sexual dimorphism for most behaviors, indicating these evaluations were sensitive to sex differences. However, only EE2 treatment caused significant effects. Relative to female controls, EE2-treated females were heavier, exhibited delayed vaginal opening, aberrant estrous cyclicity, increased play behavior, decreased running wheel activity, and increased aggression toward the stimulus male during sexual behavior assessments. Relative to male controls, EE2-treated males were older at testes descent and preputial separation and had lower testosterone levels. These results suggest EE2-induced masculinization/defeminization of females and are consistent with increased volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) at weaning in female siblings of these subjects (He, Z., Paule, M. G. and Ferguson, S. A. (2012) Low oral doses of bisphenol A increase volume of the sexually dimorphic nucleus of the preoptic area in male, but not female, rats at postnatal day 21. Neurotoxicol. Teratol. 34, 331–337). Although EE2 treatment caused pubertal delays and decreased testosterone levels in males, their behaviors were within the range of control males. Conversely, BPA treatment did not alter any measured endpoint. Similar to our previous reports (Ferguson, S. A., Law, C. D. Jr and Abshire, J. S. (2011) Developmental treatment with bisphenol A or ethinyl estradiol causes few alterations on early preweaning measures. Toxicol. Sci. 124, 149–160; Ferguson, S. A., Law, C. D. and Abshire, J. S. (2012) Developmental treatment with bisphenol A causes few alterations on measures of postweaning activity and learning. Neurotoxicol. Teratol. 34, 598–606), the BPA doses and design used here produced few alterations. more...