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Neuropeptide Y (NPY) is a powerful orexigenic factor in the brain. However, mice lacking NPY or NPY receptor Y1 (NPY1R) have minimal changes in basal food intake. In a study published in Nature, Zhu et al. 1 demystify this paradox and show that central and peripheral NPY have antipodal roles in energy homeostasis., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This novel study investigated the effects of intracerebroventricular (ICV) injection α- klotho and its interaction with neuropeptide Y (NPY) receptors on food intake in broiler chicken. This study included 4 experiments with 4 groups in each with 11 replicates per group. Birds were feed deprived 3 h prior injection, following injection returned to their cage and food provided. In experiment 1, group 1 received ICV injection of the saline and groups 2 to 4 received ICV injection of the α-klotho (1, 2, and 4 µg), respectively. In experiment 2, chicken received ICV injection of the saline, B5063 (NPY 1 receptor antagonist, 1.25 µg), α-klotho (4 µg) and co-injection of the B5063 + α-klotho. In experiments 3 and 4, SF22 (NPY 2 receptor antagonist, 1.25 µg), and SML0891 (NPY 5 receptor antagonist, 1.25 µg) were injected instead of the B5063. Then consumed food was measured at 30, 60, and 120 min post the injection. Based on results, ICV injection of the α-klotho (2 and 4 µg) significantly decreased food intake (P < 0.05). Co-injection of the B5063 + α-klotho significantly amplified hypophagic effect of the α-klotho (P < 0.05). α-klotho-induced hypophagia was not influenced by SF22 or SML0891. These results suggest that α-klotho-induced hypophagia is mediated via NPY 1 receptors in broiler chicken., Competing Interests: DISCLOSURES No potential conflict of interest was reported by the authors., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Neuropeptide Y (NPY) Y2 receptor (Y2) antagonist BIIE0246 can both inhibit and facilitate nociception. The authors hypothesized that Y2 function depends on inflammation or nerve injury status., Methods: The authors implemented a battery of behavioral tests in mice of both sexes that received (1) no injury; (2) an incision model of postoperative pain; (3) a spared nerve injury model of neuropathic pain; and (4) a latent sensitization model of chronic postsurgical pain. In addition to Y2 gene expression assays, spinal Y2 G-protein coupling was studied with guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTPγS) binding assays., Results: The authors report that intrathecal BIIE0246 increased mechanical and cold hypersensitivity, produced behavioral signs of spontaneous nociception and itch, and produced conditioned place aversion and preference in normal, uninjured mice. BIIE0246 did not change heat hypersensitivity or motor coordination. Conditional (sensory neuron-specific) Y2 deletion prevented BIIE0246-induced mechanical and cold hypersensitivity, nocifensive behaviors, and aversion. Both conditional deletion and pharmacologic blockade of Y2 reduced mechanical and thermal hypersensitivity after incision or nerve injury. SNI did not change the sensitivity of Y2 G-protein coupling with the Y2 agonist peptide YY (3-36) (PYY3-36), but increased the population of Y2 that effectively coupled G-proteins. Intrathecal PYY3-36 failed to reduce spared nerve injury- or incision-induced hypersensitivity in C57BL/6N mice. Incision did not change Npy2r gene expression in dorsal root ganglion., Conclusions: The authors conclude that Y2 at central terminals of primary afferent neurons provides tonic inhibition of mechanical and cold nociception and itch. This switches to the promotion of mechanical and thermal hyperalgesia in models of acute and chronic postsurgical and neuropathic pain, perhaps due to an increase in the population of Y2 that effectively couples to G-proteins. These results support the development of Y2 antagonists for the treatment of chronic postsurgical and neuropathic pain., (Copyright © 2024 American Society of Anesthesiologists. All Rights Reserved.)

Aim: To thoroughly investigate the impact of sustained neuropeptide Y4 receptor (NPY4R) activation in obesity-associated diabetes., Methods: Initially, the prolonged pharmacodynamic profile of the enzymatically stable pancreatic polypeptide (PP) analogue, [P 3 ]PP, was confirmed in normal mice up to 24 h after injection. Subsequent to this, [P 3 ]PP was administered twice daily (25 nmol/kg) for 28 days to high-fat-fed mice with streptozotocin-induced insulin deficiency, known as HFF/STZ mice., Results: Treatment with [P 3 ]PP for 28 days reduced energy intake and was associated with notable weight loss. In addition, circulating glucose was returned to values of approximately 8 mmol/L in [P 3 ]PP-treated mice, with significantly increased plasma insulin and decreased glucagon concentrations. Glucose tolerance and glucose-stimulated insulin secretion were improved in [P 3 ]PP-treated HFF/STZ mice, with no obvious effect on peripheral insulin sensitivity. Benefits on insulin secretion were associated with elevated pancreatic insulin content as well as islet and beta-cell areas. Positive effects on islet architecture were linked to increased beta-cell proliferation and decreased apoptosis. Treatment intervention also decreased islet alpha-cell area, but pancreatic glucagon content remained unaffected. In addition, [P 3 ]PP-treated HFF/STZ mice presented with reduced plasma alanine transaminase and aspartate transaminase levels, with no change in circulating amylase concentrations. In terms of plasma lipid profile, triglyceride and cholesterol levels were significantly decreased by [P 3 ]PP treatment, when compared to saline controls., Conclusion: Collectively, these data highlight for the first time the potential of enzymatically stable PP analogues for the treatment of obesity and related diabetes., (© 2024 The Author(s). Diabetes, Obesity and Metabolism published by John Wiley & Sons Ltd.)

Gene therapy is emerging as an alternative option for individuals with drug-resistant focal epilepsy. Here, we explore the potential of a novel gene therapy based on Neuropeptide Y (NPY), a well-known endogenous anticonvulsant. We develop a lentiviral vector co-expressing NPY with its inhibitory receptor Y2 in which, for the first time, both transgenes are placed under the control of the minimal CamKIIa(0.4) promoter, biasing expression toward excitatory neurons and allowing autoregulation of neuronal excitability by Y2 receptor-mediated inhibition. Vector-induced NPY and Y2 expression and safety are first assessed in cultures of hippocampal neurons. In vivo experiments demonstrate efficient and nearly selective overexpression of both genes in granule cell mossy fiber terminals following vector administration in the dentate gyrus. Telemetry video-EEG monitoring reveals a reduction in the frequency and duration of seizures in the synapsin triple KO model. This study shows that targeting a small subset of neurons (hippocampal granule cells) with a combined overexpression of NPY and Y2 receptor is sufficient to reduce the occurrence of spontaneous seizures., (© 2024. The Author(s).)

High ambient temperatures (HT) can increase diencephalic neuropeptide Y (NPY) expression, and central injection of NPY attenuates heat stress responses while inducing an antioxidative state in the chick spleen. However, there is a lack of knowledge about NPY receptor expression, and its regulation by HT, in the chick spleen. In the current study, male chicks were used to measure the expression of NPY receptors in the spleen and other immune organs under acute (30 vs. 40 ± 1°C for 3 h) or chronic (30 vs. 40 ± 1°C for 3 h/day for 3 days) exposure to HT and in response to central injection of NPY (47 pmol, 188 pmol, or 1 nmol). We found that NPY-Y4 receptor mRNA was expressed in the spleen, but not in other immune organs studied. Immunofluorescence staining revealed that NPY-Y4 receptors were localized in the splenic pulp. Furthermore, NPY-Y4 receptor mRNA increased in the chick spleen under both acute and chronic exposure to HT. Central NPY at two dose levels (47 and 188 pmol) and a higher dose (1 nmol) did not increase splenic NPY-Y4 receptor mRNA expression or splenic epinephrine under HT (35 ± 1°C), and significantly increased 3-methoxy-4-hydroxyphenylglycol (MHPG) concentrations under HT (40 ± 1°C). In conclusion, increased expression of NPY-Y4 receptor mRNA in the spleen under HT suggest that Y4 receptor may play physiological roles in response to HT in male chicks., 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 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The central amygdala (CeA) is a crucial hub in the processing of affective itch, containing a diverse array of neuronal populations. Among these components, Neuropeptide Y (NPY) and its receptors, such as NPY2R, affect various physiological and psychological processes. Despite this broad impact, the precise role of NPY2R + CeA neurons in itch modulation remains unknown, particularly concerning any potential lateralization effects. To address this, we employed optogenetics to selectively stimulate NPY2R + CeA neurons in mice, investigating their impact on itch modulation. Optogenetic activation of NPY2R + CeA neurons reduced scratching behavior elicited by pruritogens without exhibiting any lateralization effects. Electrophysiological recordings confirmed increased neuronal activity upon stimulation. However, this modulation did not affect thermal sensitivity, mechanical sensitivity, or formalin-induced hyperalgesia. Additionally, no alterations in anxiety-like behaviors or locomotion were observed upon stimulation. Projection tracing revealed connections of NPY2R + CeA neurons to brain regions implicated in itch processing. Overall, this comprehensive study highlights the role of NPY2R + CeA neurons in itch regulation without any lateralization effects., (© 2024. The Author(s).)

Drugs with poor water and lipid solubility are termed "brick dust." We previously successfully developed a co-amorphous system of a novel neuropeptide Y 5 receptor antagonist (AntiY 5 R), a brick dust molecule, using sodium taurocholate (NaTC) as a co-former. However, the maximum improvement in AntiY 5 R dissolution by the co-amorphous system was only approximately 10 times greater than that of the crystals. Therefore, in the current study, other bile salts, including sodium cholate (NaC), sodium chenodeoxycholate (NaCC), and sodium glycocholate (NaGC), were examined as co-formers to further improve AntiY 5 R dissolution. NaC, NaCC, and NaGC have glass transition temperatures above 150°C. All three co-amorphous systems prepared successfully retained the amorphous form of AntiY 5 R for 3 months at 40°C, but the co-amorphous system with NaGC (AntiY 5 R-NaGC; 1:9 molar ratio) provided the highest improvement in AntiY 5 R dissolution, which was approximately 50 times greater than that of the crystals. Possible intermolecular interactions via the glycine moiety of NaGC more than the other bile salts would contribute to the highest dissolution enhancement with AntiY 5 R-NaGC. Thus, NaGC would be a promising co-former for formulating stable co-amorphous systems to enhance the dissolution behavior of brick dust molecules., 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 B.V. All rights reserved.)

Neuropeptide Y (NPY) increases resilience and buffers behavioral stress responses in male rats in part through decreasing the excitability of principal output neurons in the basolateral amygdala (BLA). Intra-BLA administration of NPY acutely increases social interaction (SI) through activation of either Y 1 or Y 5 receptors, whereas repeated NPY (rpNPY) injections (once daily for 5 d) produce persistent increases in SI through Y 5 receptor-mediated neuroplasticity in the BLA. In this series of studies, we characterized the neural circuits from the BLA that underlie these behavioral responses to NPY. Using neuronal tract tracing, NPY Y 1 and Y 5 receptor immunoreactivity was identified on subpopulations of BLA neurons projecting to the bed nucleus of the stria terminalis (BNST) and the central nucleus of the amygdala (CeA). Inhibition of BLA→BNST, but not BLA→CeA, neurons using projection-restricted, cre-driven designer receptors exclusively activated by designer drug-G i expression increased SI and prevented stress-induced decreases in SI produced by a 30 min restraint stress. This behavioral profile was similar to that seen after both acute and rpNPY injections into the BLA. Intracellular recordings of BLA→BNST neurons demonstrated NPY-mediated inhibition via suppression of H currents, as seen previously. Repeated intra-BLA injections of NPY, which are associated with the induction of BLA neuroplasticity, decreased the activity of BLA→BNST neurons and decreased their dendritic complexity. These results demonstrate that NPY modulates the activity of BNST-projecting BLA neurons, suggesting that this pathway contributes to the stress-buffering actions of NPY and provides a novel substrate for the proresilient effects of NPY., Competing Interests: The authors declare no competing financial interests., (Copyright © 2024 the authors.)

Introduction: While therapies based on endogenous gut peptides such as glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs) have been compelling therapeutic agents for obesity and type 2 diabetes (T2D), only a few have achieved long-term weight loss and all have shown significant side-effects, including nausea/malaise and gastrointestinal ailments., Objective: As the pathophysiology of obesity is driven by dysregulation of multiple, inter-related, pathways, we tested a novel peptide targeting multiple receptors of complementary neurocircuits regulating the controls of energy balance., Methods: Response to daily injections of GEP44, a GLP-1R and neuropeptide Y1R and Y2R receptor (Y1R/Y2R) triple agonist was tested vs. the GLP-1R agonist liraglutide (LIRA) in diet-induced obese (DIO) male and female rats. Glucose tolerance tests after intraperitoneal injection of glucose (IPGTT) were performed at baseline and after 14-d of treatment in GEP44 treated rats. Other metabolic parameters were assessed in blood at the end of a 28-d intervention., Results: Upon conclusion at 28-d, body weight reduction compared to vehicle was -15.6%/-11.9% in response to GEP44, vs. -9.7%/-5.1% after LIRA, males, and females, respectively. Significant reductions of cumulative food intake occurred over 28-d in female rats treated with GEP44 (-30%; p < 0.0001), vs. LIRA (-10%), and in male rats GEP44 (-39%; p < 0.0001), vs. LIRA (-20%; p = 0.003). In IPGTTs, a similar stimulation glucose induced insulin secretion was noted in rats treated with GEP44 and LIRA., Conclusion: The strong reductions of body weight in response to long-term applications of the triple agonist GEP44 confirms the therapeutic potential of targeting multiple receptors for achieving more robust and potentially more sustained improvement of energy balance., Competing Interests: Conflict of interest R.P.D. is a Scientific Advisory Board member of Balchem Corporation, New Hampton, NY, which played no role in the design, execution, or analysis of the results of these studies. R.P.D. is a named author of a patent pursuant to the development of GEP44 that is owned by Syracuse University., (Copyright © 2024 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Background: Female Aedes aegypti mosquitoes can spread disease-causing pathogens when they bite humans to obtain blood nutrients required for egg production. Following a complete blood meal, host-seeking is suppressed until eggs are laid. Neuropeptide Y-like receptor 7 (NPYLR7) plays a role in endogenous host-seeking suppression and previous work identified small-molecule NPYLR7 agonists that inhibit host-seeking and blood-feeding when fed to mosquitoes at high micromolar doses., Methods: Using structure-activity relationship analysis and structure-guided design we synthesized 128 compounds with similarity to known NPYLR7 agonists., Results: Although in vitro potency (EC 50 ) was not strictly predictive of in vivo effect, we identified three compounds that reduced blood-feeding from a live host when fed to mosquitoes at a dose of 1 μM-a 100-fold improvement over the original reference compound., Conclusions: Exogenous activation of NPYLR7 represents an innovative vector control strategy to block mosquito biting behavior and prevent mosquito-human host interactions that lead to pathogen transmission., (© 2024. The Author(s).)

The neuropeptide Y 4 receptor (Y 4 R), a rhodopsin-like G protein-coupled receptor (GPCR) and the hormone pancreatic polypeptide (PP) are members of the neuropeptide Y family consisting of four receptors (Y 1 R, Y 2 R, Y 4 R, Y 5 R) and three highly homologous peptide ligands (neuropeptide Y, peptide YY, PP). In this family, the Y 4 R is of particular interest as it is the only subtype with high affinity to PP over NPY. The Y 4 R, as a mediator of PP signaling, has a pivotal role in appetite regulation and energy homeostasis, offering potential avenues for the treatment of metabolic disorders such as obesity. PP as anorexigenic peptide is released postprandial from the pancreas in response to food intake, induces satiety signals and contributes to hamper excessive food intake. Moreover, this system was also described to be associated with different types of cancer: overexpression of Y 4 R have been found in human adenocarcinoma cells, while elevated levels of PP are related to the development of pancreatic endocrine tumors. The pharmacological relevance of the Y 4 R advanced the search for potent and selective ligands for this receptor subtype, which will be significantly progressed through the elucidation of the active state PP-Y 4 R cryo-EM structure. This review summarizes the development of novel PP-derived ligands, like Obinepitide as dual Y 2 R/Y 4 R agonist in clinical trials or UR-AK86c as small hexapeptide agonist with picomolar affinity, as well as the first allosteric modulators that selectively target the Y 4 R, e.g. VU0506013 as potent Y 4 R positive allosteric modulator or (S)-VU0637120 as allosteric antagonist. Here, we provide valuable insights into the complex physiological functions of the Y 4 R and PP and the pharmacological relevance of the system in appetite regulation to open up new avenues for the development of tool compounds for targeted therapies with potential applications in metabolic disorders., (Copyright © 2023. Published by Elsevier Ltd.)

Aims: Cardiac dysfunction is commonly observed in patients with subarachnoid haemorrhage (SAH). However, the specific timeline of cardiac remodelling and the underlying mechanisms responsible for this effect following SAH remain unknown. This study aims to explore the impact of SAH on cardiac dysfunction and its potential mechanisms over time., Methods and Results: In Protocol 1, we investigated cardiac function and potential mechanisms in a Sprague-Dawley rat model of SAH at six time points (baseline and Days 1, 3, 7, 14, and 28) while exploring the underlying mechanisms. Our assessments included the haemodynamic profile, echocardiography, and the concentrations of plasma biomarkers at various time points post-SAH. We determined neuropeptide Y (NPY) 1-5 receptor protein expression levels through western blotting. In Protocol 2, we administered an NPY1 receptor antagonist to evaluate the effects of cardiac dysfunction induced by SAH on Day 3. In Protocol 1, SAH gradually provoked cardiac systolic dysfunction during the acute phase, reaching its peak on Day 3 without concurrent alterations in wall thickness. However, no significant changes were observed from Days 14 to 28 compared with Day 0. The changes in cardiac dysfunction were consistent with myocardial injury, inflammatory biomarkers, and NPY levels. SAH resulted in a heightened heart rate and systolic blood pressure, correlating with elevated epinephrine and norepinephrine levels. In Protocol 2, the administration of the NPY1 receptor antagonist effectively ameliorated cardiac dysfunction., Conclusions: SAH induces transient cardiac dysfunction in the acute phase, and the underlying mechanisms for this response involve the NPY-NPY1 receptor pathway, otherwise known as catecholamines., (© 2024 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of European Society of Cardiology.)

The control of feeding and physical activity is tightly linked and coordinated. However the underlying mechanisms are unclear. One of the major regulatory systems of feeding behaviour involves neuropeptide Y (NPY) signalling, with the signalling mediated through NPY Y4 receptor also known to influence activity. Here we show that mice globally lacking the Npy4r (Npy4r -/- ) in the absence of access to a running wheel behaved WT-like with regards to food intake, energy expenditure, respiratory exchange ratio and locomotion regardless of being fed on a chow or high fat diet. Interestingly however, when given the access to a running wheel, Npy4r -/- mice while having a comparable locomotor activity, showed significantly higher wheel-running activity than WT, again regardless of dietary conditions. This higher wheel-running activity in Npy4r -/- mice arose from an increased dark-phase running time rather than changes in number of running bouts or the running speed. Consistently, energy expenditure was higher in Npy4r -/- than WT mice. Importantly, food intake was reduced in Npy4r -/- mice under wheel access condition which was due to decreased feeding bouts rather than changes in meal size. Together, these findings demonstrate an important role of Npy4r signalling in the dual control of feeding and physical activity, particularly in the form of wheel-running activity., Competing Interests: Declaration of competing interest All authors declare no conflict of interest., (Copyright © 2023. Published by Elsevier Ltd.)

Dysfunction of the sympathetic nervous system and increased epicardial adipose tissue (EAT) have been independently associated with the occurrence of cardiac arrhythmia. However, their exact roles in triggering arrhythmia remain elusive. Here, using an in vitro coculture system with sympathetic neurons, cardiomyocytes, and adipocytes, we show that adipocyte-derived leptin activates sympathetic neurons and increases the release of neuropeptide Y (NPY), which in turn triggers arrhythmia in cardiomyocytes by interacting with the Y1 receptor (Y1R) and subsequently enhancing the activity of the Na + /Ca 2+ exchanger (NCX) and calcium/calmodulin-dependent protein kinase II (CaMKII). The arrhythmic phenotype can be partially blocked by a leptin neutralizing antibody or an inhibitor of Y1R, NCX, or CaMKII. Moreover, increased EAT thickness and leptin/NPY blood levels are detected in atrial fibrillation patients compared with the control group. Our study provides robust evidence that the adipose-neural axis contributes to arrhythmogenesis and represents a potential target for treating arrhythmia., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Our recent multi-omics studies have revealed rich sources of novel bioactive proteins and polypeptides from marine organisms including cnidarians. In the present study, we initially conducted a transcriptomic analysis to review the composition profile of polypeptides from Zoanthus sociatus. Then, a newly discovered NPY-like polypeptide-ZoaNPY was selected for further in silico structural, binding and virtually pharmacological studies. To evaluate the pro-angiogenic effects of ZoaNPY, we employed an in vitro HUVECs model and an in vivo zebrafish model. Our results indicate that ZoaNPY, at 1-100 pmol, enhances cell survival, migration and tube formation in the endothelial cells. Besides, treatment with ZoaNPY could restore a chemically-induced vascular insufficiency in zebrafish embryos. Western blot results demonstrated the application of ZoaNPY could increase the phosphorylation of proteins related to angiogenesis signaling including PKC, PLC, FAK, Src, Akt, mTOR, MEK, and ERK1/2. Furthermore, through molecular docking and surface plasmon resonance (SPR) verification, ZoaNPY was shown to directly and physically interact with NPY Y2 receptor. In view of this, all evidence showed that the pro-angiogenic effects of ZoaNPY involve the activation of NPY Y2 receptor, thereby activating the Akt/mTOR, PLC/PKC, ERK/MEK and Src- FAK-dependent signaling pathways. Furthermore, in an excision wound model, the treatment with ZoaNPY was shown to accelerate the wound healing process in mice. Our findings provide new insights into the discovery and development of novel pro-angiogenic drugs derived from NPY-like polypeptides in the future., 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 The Authors. Published by Elsevier Ltd.. All rights reserved.)

This study evaluates the sustained antidepressant-like effects and neurogenic potential of a 3-day intranasal co-administration regimen of galanin receptor 2 (GALR2) agonist M1145 and neuropeptide Y Y1 receptor (NPY1R) agonist [Leu31, Pro34]NPY in the ventral hippocampus of adult rats, with outcomes analyzed 3 weeks post-treatment. Utilizing the forced swimming test (FST), we found that this co-administration significantly enhances antidepressant-like behaviors, an effect neutralized by the GALR2 antagonist M871, highlighting the synergistic potential of these neuropeptides in modulating mood-related behaviors. In situ proximity ligation assay (PLA) indicated a significant increase in GALR2/NPYY1R heteroreceptor complexes in the ventral hippocampal dentate gyrus, suggesting a molecular basis for the behavioral outcomes observed. Moreover, proliferating cell nuclear antigen (PCNA) immunolabeling revealed increased cell proliferation in the subgranular zone of the dentate gyrus, specifically in neuroblasts as evidenced by co-labeling with doublecortin (DCX), without affecting quiescent neural progenitors or astrocytes. The study also noted a significant uptick in the number of DCX-positive cells and alterations in dendritic morphology in the ventral hippocampus, indicative of enhanced neuronal differentiation and maturation. These morphological changes highlight the potential of these agonists to facilitate the functional integration of new neurons into existing neural circuits. By demonstrating the long-lasting effects of a brief, 3-day intranasal administration of GALR2 and NPY1R agonists, our findings contribute significantly to the understanding of neuropeptide-mediated neuroplasticity and herald novel therapeutic strategies for the treatment of depression and related mood disorders, emphasizing the therapeutic promise of targeting neurogenesis and neuronal maturation processes., (© 2024 The Authors. The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

This study investigates the combined effects of the neuropeptide Y Y1 receptor (NPY1R) agonist [Leu31-Pro34]NPY at a dose of 132 µg and Ketamine at 10 mg/Kg on cognitive functions and neuronal proliferation, against a backdrop where neurodegenerative diseases present an escalating challenge to global health systems. Utilizing male Sprague-Dawley rats in a physiological model, this research employed a single-dose administration of these compounds and assessed their impact 24 h after treatment on object-in-place memory tasks, alongside cellular proliferation within the dorsal hippocampus dentate gyrus. Methods such as the in situ proximity ligation assay and immunohistochemistry for proliferating a cell nuclear antigen (PCNA) and doublecortin (DCX) were utilized. The results demonstrated that co-administration significantly enhanced memory consolidation and increased neuronal proliferation, specifically neuroblasts, without affecting quiescent neural progenitors and astrocytes. These effects were mediated by the potential formation of NPY1R-TrkB heteroreceptor complexes, as suggested by receptor co-localization studies, although further investigation is required to conclusively prove this interaction. The findings also highlighted the pivotal role of brain-derived neurotrophic factor (BDNF) in mediating these effects. In conclusion, this study presents a promising avenue for enhancing cognitive functions and neuronal proliferation through the synergistic action of the NPY1R agonist and Ketamine, potentially via NPY1R-TrkB heteroreceptor complex formation, offering new insights into therapeutic strategies for neurodegenerative diseases.

Background: Major Depressive Disorder (MDD) is a prevalent and debilitating condition, necessitating novel therapeutic strategies due to the limited efficacy and adverse effects of current treatments. We explored how galanin receptor 2 (GALR2) and Neuropeptide Y1 Receptor (NPYY1R) agonists, working together, can boost brain cell growth and increase antidepressant-like effects in rats. This suggests new ways to treat Major Depressive Disorder (MDD)., Research Design and Methods: In a controlled laboratory setting, adult naive Sprague-Dawley rats were administered directly into the brain's ventricles, a method known as intracerebroventricular (ICV) administration, with GALR2 agonist (M1145), NPYY1R agonist, both, or in combination with a GALR2 antagonist (M871). Main outcome measures included long-term neuronal survival, differentiation, and behavioral., Results: Co-administration of M1145 and NPYY1R agonist significantly enhanced neuronal survival and maturation in the ventral dentate gyrus, with a notable increase in Brain-Derived Neurotrophic Factor (BDNF) expression. This neurogenic effect was associated with an antidepressant-like effect, an outcome partially reversed by M871., Conclusions: GALR2 and NPYY1R agonists jointly promote hippocampal neurogenesis and exert antidepressant-like effects in rats without adverse outcomes, highlighting their therapeutic potential for MDD. The study's reliance on an animal model and intracerebroventricular delivery warrants further clinical exploration to confirm these promising results.

Neuropeptide Y (NPY), an extensively distributed neurotransmitter within the central nervous system (CNS), was initially detected and isolated from the brain of a pig in 1982. By binding to its G protein-coupled receptors, NPY regulates immune responses and contributes to the pathogenesis of numerous inflammatory diseases. The hippocampus contained the maximum concentration in the CNS, with the cerebral cortex, hypothalamus, thalamus, brainstem, and cerebellum following suit. This arrangement suggests that the substance has a specific function within the CNS. More and more studies have shown that NPY is involved in the physiological and pathological mechanism of stroke, and its serum concentration can be one of the specific biomarkers of stroke and related complications because of its high activity, broad and complex effects. By summarizing relevant literature, this article aims to gain a thorough understanding of the potential clinical applications of NPY in the treatment of stroke, identification of stroke and its related complications, and assessment of prognosis., 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 Ltd. All rights reserved.)

Background: Major Depressive Disorder (MDD) poses a significant challenge to global health, with current treatments often limited by efficacy and onset delays. This study explores the synergistic antidepressant-like effects of an NPY1R agonist and Ketamine, targeting their neurobiological interactions within the ventral hippocampus., Research Design and Methods: Utilizing a preclinical model, this study administered Neuropeptide Y receptor 1 (NPY1R) agonist and Ketamine, both separately and in combination, through intracerebroventricular (icv) and intranasal (i.n.) routes. The Forced Swimming Test (FST) was employed to assess antidepressant-like activity, while in situ Proximity Ligation Assay and immunohistochemistry were used to examine NPY1R/TrkB heteroreceptor complexes and BDNF expression in the ventral dentate gyrus (DG), along with neurogenesis markers., Results: The combined treatment significantly reduced immobility in the FST, indicative of enhanced antidepressant-like effects, correlated with increased formation of NPY1R/TrkB complex and brain-derived neurotrophic factor (BDNF) expression in the ventral DG. These molecular alterations were associated with increased neurogenesis., Conclusions: The coadministration of an NPY1R agonist and Ketamine in a rodent model demonstrated potentiated antidepressant responses through synergistic neurobiological pathways, including TrkB signaling and hippocampal neurogenesis. This indicates a novel therapeutic strategy for MDD, warranting further clinical investigation to fully understand its implications.

Glucoprivic feeding is one of several counterregulatory responses (CRRs) that facilitates restoration of euglycemia following acute glucose deficit (glucoprivation). Our previous work established that glucoprivic feeding requires ventrolateral medullary (VLM) catecholamine (CA) neurons that coexpress neuropeptide Y (NPY). However, the connections by which VLM CA/NPY neurons trigger increased feeding are uncertain. We have previously shown that glucoprivation, induced by an anti-glycolygic agent 2-deoxy-D-glucose (2DG), activates perifornical lateral hypothalamus (PeFLH) neurons and that expression of NPY in the VLM CA/NPY neurons is required for glucoprivic feeding. We therefore hypothesized that glucoprivic feeding and possibly other CRRs require NPY-sensitive PeFLH neurons. To test this, we used the ribosomal toxin conjugate NPY-saporin (NPY-SAP) to selectively lesion NPY receptor-expressing neurons in the PeFLH of male rats. We found that NPY-SAP destroyed a significant number of PeFLH neurons, including those expressing orexin, but not those expressing melanin-concentrating hormone. The PeFLH NPY-SAP lesions attenuated 2DG-induced feeding but did not affect 2DG-induced increase in locomotor activity, sympathoadrenal hyperglycemia, or corticosterone release. The 2DG-induced feeding response was also significantly attenuated in NPY-SAP-treated female rats. Interestingly, PeFLH NPY-SAP lesioned male rats had reduced body weights and decreased dark cycle feeding, but this effect was not seen in female rats. We conclude that a NPY projection to the PeFLH is necessary for glucoprivic feeding, but not locomotor activity, hyperglycemia, or corticosterone release, in both male and female rats., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

(1) Background: Modulators of the Neuropeptide Y (NPY) system are involved in energy metabolism, but the effect of NPY receptor antagonists on metabolic-dysfunction-associated steatotic liver disease (MASLD), a common obesity-related comorbidity, are largely unknown. In this study, we report on the effects of antagonists of the NPY-2 receptor (Y2R) in comparison with empagliflozin and semaglutide, substances that are known to be beneficial in MASLD. (2) Methods: Diet-induced obese (DIO) male Wistar rats were randomized into the following treatment groups: empagliflozin, semaglutide ± PYY 3-36 , the Y2R antagonists JNJ 31020028 and a food-restricted group, as well as a control group. After a treatment period of 8 weeks, livers were weighed and histologically evaluated. QrtPCR was performed to investigate liver inflammation and de novo lipogenesis (in liver and adipose tissue). Serum samples were analysed for metabolic parameters. (3) Results: Semaglutide + PYY 3-36 led to significant weight loss, reduced liver steatosis ( p = 0.05), and decreased inflammation, insulin resistance, and leptin levels. JNJ-31020028 prevented steatosis ( p = 0.03) without significant weight loss. Hepatic downregulation of de novo lipogenesis-regulating genes (SREBP1 and MLXIPL) was observed in JNJ-31020028-treated rats ( p ≤ 0.0001). Food restriction also resulted in significantly reduced weight, steatosis, and hepatic de novo lipogenesis. (4) Conclusions: Body weight reduction (e.g., by food restriction or drugs like semaglutide ± PYY 3-36 ) is effective in improving liver steatosis in DIO rats. Remarkably, the body-weight-neutral Y2R antagonists may be effective in preventing liver steatosis through a reduction in de novo lipogenesis, making this drug class a candidate for the treatment of (early) MASLD.

Neuropeptide Y (NPY) has anxiolytic-like effects and facilitates the extinction of cued and contextual fear in rodents. We have previously shown that intracerebroventricular administration of NPY reduces the expression of social fear via simultaneous activation of Y1 and Y2 receptors in a mouse model of social fear conditioning (SFC). In the present study, we investigated whether the anteroventral bed nucleus of the stria terminalis (BNSTav) mediates these effects of NPY, given the important role of BNSTav in regulating anxiety- and fear-related behaviors. We show that while NPY (0.1 nmol/0.2 μl/side) did not reduce the expression of SFC-induced social fear in male CD1 mice, it reduced the expression of both cued and contextual fear by acting on Y2 but not on Y1 receptors within the BNSTav. Prior administration of the Y2 receptor antagonist BIIE0246 (0.2 nmol/0.2 μl/side) but not of the Y1 receptor antagonist BIBO3304 trifluoroacetate (0.2 nmol/0.2 μl/side) blocked the effects of NPY on the expression of cued and contextual fear. Similarly, NPY exerted non-social anxiolytic-like effects in the elevated plus maze test but not social anxiolytic-like effects in the social approach avoidance test by acting on Y2 receptors and not on Y1 receptors within the BNSTav. These results suggest that administration of NPY within the BNSTav exerts robust Y2 receptor-mediated fear-reducing and anxiolytic-like effects specifically in non-social contexts and add a novel piece of evidence regarding the neural underpinnings underlying the effects of NPY on conditioned fear and anxiety-like behavior., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Neuropeptide Y (NPY), as one of the most abundant neuropeptides known, is widely distributed in the central and peripheral nervous system. However, most of the reported NPY-mimetic peptides are hard to cross the blood-brain barrier, target glioma mitochondria, and achieve self-assembly nanostructure in situ. Here, based on the α-helix structure of the novel chiral NPY-mimetic peptides D/L NPY(14), a Y-shaped peptide is designed with the sequences that can be recognized by enterokinase and achieved nanofibers conversion in glioma cell mitochondria. Coupling the Y-shaped NPY-mimetic peptide with the NIR-II fluorophore IR1048, a red-shifting of the fluorescence spectrum beyond 1300 nm is achieved through self-assembly. After the self-assembly in glioma mitochondria, the formed nanofibers can promote intracellular mitochondrial ROS production and extend the NIR-II fluorescence imaging time to at least 7 days in vivo. This work for the first time endows the self-assembly of α-helical-based chiral NPY-mimetic peptides, providing a novel strategy for glioma subcellular regulation enhanced antitumor treatment guided by NIR-II fluorescence imaging., (© 2023 Wiley‐VCH GmbH.)

Neuropeptide Y (NPY) signaling regulation of corticolimbic communication is known to modulate binge-like ethanol consumption in rodents. In this work we sought to assess the impact of intra-BLA NPY system modulation on binge-like ethanol intake and to assess the role of the NPY1R+ projection from the BLA to the mPFC in this behavior. We used "drinking-in-the-dark" (DID) procedures in C57BL6J mice to address these questions. First, the impact of intra-BLA administration of NPY on binge-like ethanol intake was assessed. Next, the impact of repeated cycles of DID intake on NPY1R expression in the BLA was assessed with use of immunohistochemistry (IHC). Finally, chemogenetic inhibition of BLA→mPFC NPY1R+ projections was assessed to determine if limbic communication with the mPFC was specifically involved in binge-like ethanol intake. Importantly, as both the BLA and NPY system are sexually dimorphic, both sexes were assessed in these studies. Intra-BLA NPY dose-dependently decreased binge-like ethanol intake in males only. Repeated DID reduced NPY1R expression in the BLA of both sexes. Silencing of BLA→mPFC NPY1R+ neurons significantly reduced binge-like ethanol intake in both sexes in a dose-dependent manner. We provide novel evidence that (1) intra-BLA NPY reduces binge-like ethanol intake in males; (2) binge-like ethanol intake reduces NPY1R levels in the BLA; and (3) chemogenetic inhibition of BLA→mPFC NPY1R+ neurons blunts binge-like drinking in male and female mice. These observations provide the first direct evidence that NPY signaling in the BLA, and specifically BLA communication with the mPFC, modulates binge-like ethanol consumption., (© 2023. The Author(s), under exclusive licence to American College of Neuropsychopharmacology.)

The structure and dynamics of the lipid membrane can affect the activity of membrane proteins. Therefore, small lipophilic molecules that alter membrane properties (such as the neurotransmitter serotonin) can potentially modulate receptor activity without binding to the receptor. Here, we investigated how the activity of neuropeptide Y type 4 receptor (Y4R, reconstituted in lipid bicelles) is modulated by serotonin, which has no known interaction with Y4R. We found a serotonin-concentration-dependent decrease (down to 0.1 mM of serotonin) in the ligand affinity of Y4R. This effect correlates with a serotonin-induced reduction of the resistance of the bilayer to indentation (measured by atomic force microscopy) and bilayer thickness (measured by solid state NMR) in two different types of zwitterionic lipid bicelles. Our findings indicate a "membrane-mediated allosteric effect" of serotonin on the activation of Y4R and suggest the potential for developing pharmacophores, which can modulate cellular signaling without directly interacting with any receptor.

Rationale: In the physiological states, the act of scratching protects the person from harmful substances, while in certain pathological conditions, the patient suffers from chronic itch, both physically and mentally. Chronic itch sufferers are more sensitive to mechanical stimuli, and mechanical hyperknesis relief is essential for chronic itch treatment. While neuropeptide Y-Y1 receptor (NPY-Y1R) system is known to play a crucial role in modulating mechanical itch in physiological conditions, it is elusive how they are altered during chronic itch. We hypothesize that the negative regulatory effect of Y1Rs on Tac2 neurons, the key neurons that transmit mechanical itch, declines during chronic itch. Methods: We combined transgenic mice, chemogenetic manipulation, immunofluorescence, rabies virus circuit tracing, and electrophysiology to investigate the plasticity of Y1Rs on Tac2 neurons during chronic itch. Results: We found that Tac2 neurons receive direct input from Npy neurons and that inhibition of Npy neurons induces activation of Tac2 neurons. Moreover, the expression of Y1Rs on Tac2 neurons is reduced, and the regulatory effect is also reduced during chronic itch. Conclusion: Our study clarifies the plasticity of Y1Rs on Tac2 neurons during chronic itch and further elucidates the mechanism by which NPY-Y1R system is responsible for modulating mechanical itch. We highlight Y1Rs as a promising therapeutic target for mechanical hyperknesis during chronic itch., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

A peptide composed of a 36 amino acid called Neuropeptide Y (NPY) is employed in a variety of physiological processes to manage and treat conditions affecting the endocrine, circulatory, respiratory, digestive, and neurological systems. NPY naturally binds to G-protein coupled receptors, activating the Y-receptors (Y1-Y5 and y6). The findings on numerous therapeutic applications of NPY for CNS disease are presented in this review by the authors. New targets for treating diseases will be revealed by medication combinations that target NPY and its receptors. This review is mainly focused on disorders such as anxiety, Alzheimer's disease, Parkinson's disease, Huntington's disease, Machado Joseph disease, multiple sclerosis, schizophrenia, depression, migraine, alcohol use disorder, and substance use disorder. The findings from the preclinical studies and clinical studies covered in this article may help create efficient therapeutic plans to treat neurological conditions on the one hand and psychiatric disorders on the other. They may also open the door to the creation of novel NPY receptor ligands as medications to treat these conditions., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest, financial or otherwise., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The neuropeptide-Y (NPY) family acts through four G protein-coupled receptor subtypes in humans, namely, Y 1 , Y 2 , Y 4 , and Y 5 . A growing body of evidence suggest the involvement of the NPY system in several cancers, notably the Y 5 subtype, thus acting as a relevant target for the development of radiopharmaceuticals for imaging or targeted radionuclide therapy (TRT). Here, the [cPP(1-7),NPY(19-23),Ala 31 ,Aib 32 ,Gln 34 ]hPP scaffold, further referred to as sY 5 ago, was modified with a DOTA chelator and radiolabeled with 68 Ga and 111 In and investigated in vitro and in vivo using the MCF-7 model. For in vivo studies, MCF-7 cells were orthotopically implanted in female nude mice and imaging with small animal positron emission tomography/computed tomography (μPET/CT) was performed. At the end of imaging, the mice were sacrificed. A scrambled version of sY 5 ago, which was also modified with a DOTA chelator, served as a negative control (DOTA-[Nle]sY 5 ago&#95;scrambled). sY 5 ago and DOTA-sY 5 ago showed subnanomolar affinity toward the Y 5 (0.9 ± 0.1 and 0.8 ± 0.1 nM, respectively) and a single binding site at the Y 5 was identified. [ 68 Ga]Ga-DOTA-sY 5 ago and [ 111 In]In-DOTA-sY 5 ago were hydrophilic and showed high specific internalization (1.61 ± 0.75%/10 6 cells at 1 h) and moderate efflux (55% of total binding externalized at 45 min). On μPET/CT images, most of the signal was depicted in the kidneys and the liver. MCF-7 tumors were clearly visualized. On biodistribution studies, [ 68 Ga]Ga-DOTA-sY 5 ago was eliminated by the kidneys (∼60 %ID/g). The kidney uptake is Y 5 -mediated. A specific uptake was also noted in the liver (5.09 ± 1.15 %ID/g vs 1.13 ± 0.21 %ID/g for [ 68 Ga]Ga-DOTA-[Nle]sY 5 ago&#95;scrambled, p < 0.05), the lungs (1.03 ± 0.34 %ID/g vs 0.20 %ID/g, p < 0.05), and the spleen (0.85 ± 0.09%ID/g vs 0.16 ± 0.16%ID/g, p < 0.05). In MCF-7 tumors, [ 68 Ga]Ga-DOTA-sY 5 ago showed 12-fold higher uptake than [ 68 Ga]Ga-DOTA-[Nle]sY 5 ago&#95;scrambled (3.43 ± 2.32 vs 0.27 ± 0.15 %ID/g, respectively, p = 0.0008) at 1 h post-injection. Finally, a proof-of-principle tissular micro-imaging study on a human primary cancer sample showed weak binding of [ 111 In]In-DOTA-sY 5 ago in prostatic intra-neoplasia and high binding in the ISUP1 lesion while normal prostate was free of signal.

The family of human neuropeptide Y receptors (YRs) comprises four subtypes (Y 1 R, Y 2 R, Y 4 R, and Y 5 R) that are involved in the regulation of numerous physiological processes. Until now, Y 4 R binding studies have been predominantly performed in hypotonic sodium-free buffers using 125 I-labeled derivatives of the endogenous YR agonists pancreatic polypeptide or peptide YY. A few tritium-labeled Y 4 R ligands have been reported; however, when used in buffers containing sodium at a physiological concentration, their Y 4 R affinities are insufficient. Based on the cyclic hexapeptide UR-AK86C, we developed a new tritium-labeled Y 4 R radioligand ([ 3 H]UR-JG102, [ 3 H] 20 ). In sodium-free buffer, [ 3 H] 20 exhibits a very low Y 4 R dissociation constant ( K d 0.012 nM). In sodium-containing buffer (137 mM Na + ), the Y 4 R affinity is lower ( K d 0.11 nM) but still considerably higher compared to previously reported tritiated Y 4 R ligands. Therefore, [ 3 H] 20 represents a useful tool compound for the determination of Y 4 R binding affinities under physiological-like conditions.

Neuropeptide Y (NPY) is co-released with norepinephrine and ATP by sympathetic nerves innervating arteries. Circulating NPY is elevated during exercise and cardiovascular disease, though information regarding the vasomotor function of NPY in human blood vessels is limited. Wire myography revealed NPY directly stimulated vasoconstriction (EC 50 10.3 ± 0.4 nM; N = 5) in human small abdominal arteries. Maximum vasoconstriction was antagonised by both BIBO03304 (60.7 ± 6%; N = 6) and BIIE0246 (54.6 ± 5%; N = 6), suggesting contributions of both Y 1 and Y 2 receptor activation, respectively. Y 1 and Y 2 receptor expression in arterial smooth muscle cells was confirmed by immunocytochemistry, and western blotting of artery lysates. α,β-meATP evoked vasoconstrictions (EC 50 282 ± 32 nM; N = 6) were abolished by suramin (IC 50 825 ± 45 nM; N = 5) and NF449 (IC 50 24 ± 5 nM; N = 5), suggesting P2X1 mediates vasoconstriction in these arteries. P2X1, P2X4 and P2X7 were detectable by RT-PCR. Significant facilitation (1.6-fold) of α,β-meATP-evoked vasoconstrictions was observed when submaximal NPY (10 nM) was applied between α,β-meATP applications. Facilitation was antagonised by either BIBO03304 or BIIE0246. These data reveal NPY causes direct vasoconstriction in human arteries which is dependent upon both Y 1 and Y 2 receptor activation. NPY also acts as a modulator, facilitating P2X1-dependent vasoconstriction. Though in contrast to the direct vasoconstrictor effects of NPY, there is redundancy between Y 1 and Y 2 receptor activation to achieve the facilitatory effect., Competing Interests: Declaration of Competing Interest Authors declare no conflict of interest., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: Neuropeptide Y (NPY) is a pleiotropic peptide, which is involved in many biological mechanisms important in regulation of cell growth and survival. The aim of this study was a comprehensive analysis of the NPY system in prostate pathology., Methods: The study was based on immunohistochemical analysis of NPY and its receptors, Y1R, Y2R and Y5R, in tissue samples from benign prostate (BP), primary prostate cancer (PCa) and PCa bone metastases. Tissue microarray (TMA) technique was employed, with analysis of multiple cores from each specimen. Intensity of the immunoreactivity and expression index (EI), as well as distribution of the immunostaining in neoplastic cells and stromal elements were evaluated. Perineural invasion (PNI) and extraprostatic extension (EPE) were areas of special interests. Moreover, a transwell migration assay on the LNCaP PCa cell line was used to assess the chemotactic properties of NPY., Results: Morphological analysis revealed homogeneous membrane and cytoplasmic pattern of NPY staining in cancer cells and its membrane localization with apical accentuation in BP glands. All elements of the NPY system were upregulated in pre-invasive prostate intraepithelial neoplasia, PCa and metastases. EI and staining intensity of NPY receptors were significantly higher in PCa then in BP with correlation between Y2R and Y5R. The strength of expression of the NPY system was further increased in the PNI and EPE areas. In bone metastases, Y1R and Y5R presented high expression scores., Conclusion: The results of our study suggest that the NPY system is involved in PCa, starting from early stages of its development to disseminated states of the disease, and participates in the invasion of PCa into the auto and paracrine matter., (© 2022. The Author(s).)

The G-protein-coupled Y 4 -receptor (Y 4 R) and its endogenous ligand, pancreatic polypeptide (PP), suppress appetite in response to food intake and, thus, are attractive drug targets for body-weight control. The C-terminus of human PP (hPP), T 32 -R 33 -P 34 -R 35 -Y 36 - NH 2 , penetrates deep into the binding pocket with its tyrosine-amide and di-arginine motif. Here, we present two C-terminally amidated α,γ-hexapeptides ( 1a / b ) with sequence Ac -R 31 -γ-CBAA 32 -R 33 -L 34 -R 35 -Y 36 - NH 2 , where γ-CBAA is the (1 R ,2 S ,3 R )-configured 2-(aminomethyl)-3-phenylcyclobutanecarboxyl moiety ( 1a ) or its mirror image ( 1b ). Both peptides bind the Y 4 R ( K i of 1a / b : 0.66/12 nM) and act as partial agonists (intrinsic activity of 1a / b : 50/39%). Their induced-fit binding poses in the Y 4 R pocket are unique and build ligand-receptor contacts distinct from those of the C-terminus of the endogenous ligand hPP. We conclude that energetically favorable interactions, although they do not match those of the native ligand hPP, still guarantee high binding affinity (with 1a rivaling hPP) but not the maximum receptor activation.

Positive allosteric modulators targeting the Y 4 receptor (Y 4 R), a G protein-coupled receptor (GPCR) involved in the regulation of satiety, offer great potential in anti-obesity research. In this study, we selected 603 compounds by using quantitative structure-activity relationship (QSAR) models and tested them in high-throughput screening (HTS). Here, the novel positive allosteric modulator (PAM) VU0506013 was identified, which exhibits nanomolar affinity and pronounced selectivity toward the Y 4 R in engineered cell lines and mouse descending colon mucosa natively expressing the Y 4 R. Based on this lead structure, we conducted a systematic SAR study in two regions of the scaffold and presented a series of 27 analogues with modifications in the N - and C -terminal heterocycles of the molecule to obtain insight into functionally relevant positions. By mutagenesis and computational docking, we present a potential binding mode of VU0506013 in the transmembrane core of the Y 4 R. VU0506013 presents a promising scaffold for developing in vivo tools to move toward anti-obesity drug research focused on the Y 4 R.

Currently available data on the involvement of neuropeptide Y (NPY), peptide YY (PYY), and pancreatic polypeptide (PP) and their receptors (YRs) in cancer are updated. The structure and dynamics of YRs and their intracellular signaling pathways are also studied. The roles played by these peptides in 22 different cancer types are reviewed (e.g., breast cancer, colorectal cancer, Ewing sarcoma, liver cancer, melanoma, neuroblastoma, pancreatic cancer, pheochromocytoma, and prostate cancer). YRs could be used as cancer diagnostic markers and therapeutic targets. A high Y1R expression has been correlated with lymph node metastasis, advanced stages, and perineural invasion; an increased Y5R expression with survival and tumor growth; and a high serum NPY level with relapse, metastasis, and poor survival. YRs mediate tumor cell proliferation, migration, invasion, metastasis, and angiogenesis; YR antagonists block the previous actions and promote the death of cancer cells. NPY favors tumor cell growth, migration, and metastasis and promotes angiogenesis in some tumors (e.g., breast cancer, colorectal cancer, neuroblastoma, pancreatic cancer), whereas in others it exerts an antitumor effect (e.g., cholangiocarcinoma, Ewing sarcoma, liver cancer). PYY or its fragments block tumor cell growth, migration, and invasion in breast, colorectal, esophageal, liver, pancreatic, and prostate cancer. Current data show the peptidergic system's high potential for cancer diagnosis, treatment, and support using Y2R/Y5R antagonists and NPY or PYY agonists as promising antitumor therapeutic strategies. Some important research lines to be developed in the future will also be suggested.

Background: Neuropeptide Y (NPY) is an abundant neurohormone in human breast carcinomas that acts on a class of G-protein coupled receptors, of which NPY1R and NPY5R are the most highly expressed. This abundance is exploited for cancer imaging, but there is interest in pharmacological inhibition of the NPYRs to interrogate their functional relevance in breast cancer. We previously reported that NPY1R and NPY5R mRNA abundance is increased by hypoxia inducible factors, which sensitizes these receptors to NPY stimulation leading to enhanced migration and proliferation., Methods/results: Here, we measured the effects of NPY1R and NPY5R antagonists in normoxia and hypoxia on migration, proliferation, invasion, and signaling in 2D and 3D models of breast cancer cell lines MDA-MB-231 and MCF7. Antagonizing NPY1R and/or NPY5R in hypoxia compared to normoxia more greatly reduced MAPK signaling, cell proliferation, cell migration and invasion, and spheroid growth and invasion. The estrogen receptor positive MCF7 cells were significantly less invasive in 3D spheres when NPY5R was specifically inhibited. There were some discrepancies in the responses of each cell line to the isoform-specific antagonists and oxygen availability, therefore further investigations are required to dissect the intricacies of NPYR signaling dynamics. In human breast tumor tissue, we show via immunofluorescence that NPY5R protein levels and colocalization with hypoxia correlate with advanced cancer, and NPY1R protein correlates with adverse outcomes., Conclusions: Antagonizing the NPYRs has been implicated as a treatment for a wide variety of diseases. Therefore, these antagonists may aid in the development of novel cancer therapeutics and patient-based treatment plans., (© 2023. The Author(s).)

Background: Migraine is a highly disabling health burden with multiple symptoms; however, it remains undertreated because of an inadequate understanding of its neural mechanisms. Neuropeptide Y (NPY) has been demonstrated to be involved in the modulation of pain and emotion, and may play a role in migraine pathophysiology. Changes in NPY levels have been found in patients with migraine, but whether and how these changes contribute to migraine is unknown. Therefore, the purpose of this study was to investigate the role of NPY in migraine-like phenotypes., Methods: Here, we used intraperitoneal injection of glyceryl trinitrate (GTN, 10 mg/kg) as a migraine mouse model, which was verified by light-aversive test, von Frey test, and elevated plus maze test. We then performed whole-brain imaging with NPY-GFP mice to explore the critical regions where NPY was changed by GTN treatment. Next, we microinjected NPY into the medial habenula (MHb), and further infused Y1 or Y2 receptor agonists into the MHb, respectively, to detect the effects of NPY in GTN-induced migraine-like behaviors., Results: GTN effectively triggered allodynia, photophobia, and anxiety-like behaviors in mice. After that, we found a decreased level of GFP + cells in the MHb of GTN-treated mice. Microinjection of NPY attenuated GTN-induced allodynia and anxiety without affecting photophobia. Furthermore, we found that activation of Y1-but not Y2-receptors attenuated GTN-induced allodynia and anxiety., Conclusions: Taken together, our data support that the NPY signaling in the MHb produces analgesic and anxiolytic effects through the Y1 receptor. These findings may provide new insights into novel therapeutic targets for the treatment of migraine., (© 2023. The Author(s).)

Neural regulation of adipose tissue is crucial in the homeostasis of energy metabolism. Adipose tissue neuropeptide Y (NPY) and its receptors contribute to the development of diet-induced obesity. NPY1R and NPY2R are major receptors for NPY in peripheral tissues including the adipose tissue. NPY receptor 4 ( Npy4r ) gene is expressed in adipose tissue. However, it is unknown whether Npy4r is involved in the development of diet-induced obesity. Here, we established an immunofluorescence microscopy technique and generated an adipocyte-reconstituted Npy4r gene knockout mouse. Among six adipose depots, we found that NPY is highly expressed around the vasculature in a dot-like fashion in interscapular brown fat and subcutaneous fat, and NPY receptors are expressed in a depot-specific manner. NPY1R is highly expressed in epidydimal fat, interscapular and peri-aortic brown fat, NPY2R in both interscapular and peri-aortic brown fat, and NPY4R in both brown fat and epidydimal fat. Next, we showed that adipocyte-reconstituted expression of Npy4r promoted diet-induced obesity in mice ( P < 0.0001). Overall, this study defines the abundance and distribution of NPY and its receptors 1, 2, and 4 in mouse adipose depots, and demonstrates in an adipocyte-reconstituted gene knockout model that adipocyte Npy4r is sufficient to promote diet-induced obesity.

Pancreatic polypeptide (PP), a member of the neuropeptide Y (NPY) family of peptides, is a hormone secreted from the endocrine pancreas with established actions on appetite regulation. Thus, through activation of hypothalamic neuropeptide Y4 (NPY4R or Y4) receptors PP induces satiety in animals and humans, suggesting potential anti-obesity actions. In addition, despite being actively secreted from pancreatic islets and evidence of local Y4 receptor expression, PP mediated effects on the endocrine pancreas have not been fully elucidated. To date, it appears that PP possesses an acute insulinostatic effect, similar to the impact of other peptides from the NPY family. However, it is interesting that prolonged activation of pancreatic Y1 receptors leads to established benefits on beta-cell turnover, preservation of beta-cell identity and improved insulin secretory responsiveness. This may hint towards possible similar anti-diabetic actions of sustained Y4 receptor modulation, since the Y1 and Y4 receptors trigger comparable cell signalling pathways. In terms of exploiting the prospective therapeutic promise of PP, this is severely restricted by a short circulating half-life as is the case for many regulatory peptide hormones. It follows that long-acting, enzyme resistant, forms of PP will be required to determine viability of the Y4 receptor as an anti-obesity and -diabetes drug target. The current review aims to refocus interest on the biology of PP and highlight opportunities for therapeutic development., Competing Interests: Conflict of interest PRF and NI are named on patents filed by Ulster University for exploitation of incretin-based drugs and other peptide therapeutics. WZ and NT declare no conflict of interest., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Neuropeptide Y (NPY) and its receptors are expressed in various human tissues including the brain where they regulate appetite and emotion. Upon NPY stimulation, the neuropeptide Y1 and Y2 receptors (Y 1 R and Y 2 R, respectively) activate G I signaling, but their physiological responses to food intake are different. In addition, deletion of the two N-terminal amino acids of peptide YY (PYY(3-36)), the endogenous form found in circulation, can stimulate Y 2 R but not Y 1 R, suggesting that Y 1 R and Y 2 R may have distinct ligand-binding modes. Here, we report the cryo-electron microscopy structures of the PYY(3-36)‒Y 2 R‒G i and NPY‒Y 2 R‒G i complexes. Using cell-based assays, molecular dynamics simulations, and structural analysis, we revealed the molecular basis of the exclusive binding of PYY(3-36) to Y 2 R. Furthermore, we demonstrated that Y 2 R favors G protein signaling over β-arrestin signaling upon activation, whereas Y 1 R does not show a preference between these two pathways., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Neuropeptide Y (NPY) is produced by the nerve system and may contribute to the progression of CKD. The present study found the new protective role for NPY in AKI in both patients and animal models. Interestingly, NPY was constitutively expressed in blood and resident kidney macrophages by co-expressing NPY and CD68+ markers, which was lost in patients and mice with AKI-induced by cisplatin. Unexpectedly, NPY was renoprotective in AKI as mice lacking NPY developed worse renal necroinflammation and renal dysfunction in cisplatin and ischemic-induced AKI. Importantly, NPY was also a therapeutic agent for AKI because treatment with exogenous NPY dose-dependently inhibited cisplatin-induced AKI. Mechanistically, NPY protected kidney from AKI by inactivating M1 macrophages via the Y1R-NF-κB-Mincle-dependent mechanism as deleting or silencing NPY decreased Y1R but increased NF-κB-Mincle-mediated M1macrophage activation and renal necroinflammation, which were reversed by addition of NPY or by silencing Mincle but promoted by blocking Y1R with BIBP 3226. Thus, NPY is renoprotective and may be a novel therapeutic agent for AKI. NPY may act via Y1R to protect kidney from AKI by blocking NF-κB-Mincle-mediated M1 macrophage activation and renal necroinflammation., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

The neuropeptide Y(NPY) mediates bone metabolism and the degradation of cartilage in the peripheral nervous system. However, its role in the intervertebral disc degeneration (IDD) is less clear and warrant further study. The process of IDD has always been accompanied by inflammatory response and pyroptosis of nucleus pulposus cells (NPCs). The aim of this study was to investigate the relationship between NPY, Y1R, Y2R and pyroptosis in aging and degenerative discs and the direct effect of NPY on NPCs. First, we have assessed NPY, Y1R, Y2R and the expression of pyroptosis related protein in the immature (6 weeks), mature (16 weeks), aged (54 weeks), and degenerated discs. As part of our studies, we also have evaluated pyroptotic changes in the NPCs, induced by exposure to NPY. Our results suggested that compared with natural aging discs, the degenerative discs showed the high expression of NPY, Y1R and Y2R. Correlation analysis showed that the level of NPY and Y1R in degenerative discs were positively correlated with GSDMD, whereas there was no significant correlation between Y2R and GSDMD. In vitro, NPY treatment stimulated the activation of caspase-1-dependent pyroptosis of NPCs. However, Y1R antagonist inhibited NPY-induced pyroptosis of NPCs. Western blot confirmed that Y1R antagonist decreased the level of cleaved.GSDMD and caspase-1 in NPCs. In conclusion, our results indicated that compared with natural aging discs, the degenerated discs showed the high expression of NPY, Y1R and Y2R. NPY-Y1R involve the IDD development by the regulation of pyroptosis in the NPCs. Regulating the function of NPY may be a promising strategy for IDD treatment., Competing Interests: Declaration of Competing Interest The authors have no conflict of interest to disclose., (Copyright © 2022. Published by Elsevier Ltd.)

Stress plays a major role in the pathogenesis of many diseases. Central neuropeptide Y (NPY) counteracts the biological actions of corticotropin-releasing factor (CRF) and attenuates stress responses. Intracerebroventricular (ICV) administration of NPY significantly antagonized the inhibitory effects of chronic complicated stress (CCS) on gastrointestinal (GI) dysmotility in rats. However, ICV administration is an invasive technique. The effect of intranasal administration of NPY on the hypothalamus-pituitary-adrenal (HPA) axis and GI motility in CCS conditions have not been studied, and the inhibitory mechanism of NPY on CRF through the γ-aminobutyric acid (GABA) A receptor needs to be further investigated. A CCS rat model was set up, and NPY was intranasally administered every day before the stress loading. Furthermore, ICV administration of a GABA A receptor antagonist was performed daily. Hypothalamic CRF and NPY expressions were evaluated, serum corticosterone and NPY levels were analyzed, and colonic motor functions were assessed. CCS rats showed significantly increased CRF expression and corticosterone levels, which resulted in enhanced colonic motor functions. Intranasal NPY significantly increased hypothalamic NPY mRNA expression and reduced CRF mRNA expression and plasma corticosterone levels, helping to restore colonic motor functions. However, ICV administration of the GABA A receptor antagonist significantly abolished these effects induced by NPY. In conclusion, intranasal administration of NPY upregulates the hypothalamic NPY system. NPY may, through the GABA A receptor, significantly antagonize overexpressed central CRF and attenuate HPA axis activity in CCS conditions, influencing and helping to restore colonic motor function.

Social interactions define the human experience, but these integral behaviors are disrupted in many psychiatric disorders. Social behaviors have evolved over millennia, and neuromodulatory systems that promote social behavior in invertebrates are also present in mammalian brains. One such conserved neuromodulator, neuropeptide Y (NPY), acts through several receptors including the Y1r, Y2r, and Y5r. These receptors are present in brain regions that control social behavior, including the nucleus accumbens (NAc). However, whether NPY modulates NAc neurotransmission is unknown. Using whole-cell patch-clamp electrophysiology of NAc neurons, we find that multiple NPY receptors regulate excitatory synaptic transmission in a cell-type specific manner. At excitatory synapses onto D1+ MSNs, Y1r activity enhances transmission while Y2r suppresses transmission. At excitatory synapses onto D1- MSNs, Y5r activity enhances transmission while Y2r suppresses transmission. Directly infusing NPY or the Y1r agonist [Leu 31 , Pro 34 ]-NPY into the NAc significantly increases social interaction with an unfamiliar conspecific. Inhibition of an enzyme that breaks down NPY, dipeptidyl peptidase IV (DPP-IV), shifts the effect of NPY on D1+ MSNs to a Y1r dominated phenotype. Together, these results increase our understanding of how NPY regulates neurotransmission in the NAc and identify a novel mechanism underlying the control of social behavior. Further, they reveal a potential strategy to shift NPY signaling for therapeutic gain., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Objectives: Apolipoprotein A1 (ApoA1), a major component of high-density lipoprotein (HDL), is a protective factor against cardiovascular disease (CVD). A recent epidemiological study found an association between neuropeptide Y (NPY) gene polymorphism and serum HDL levels. However, the direct effect of NPY on ApoA1 expression remains unknown. This study was designed to investigate the molecular mechanisms underlying the NPY-mediated regulation of hepatic ApoA1., Methods: Serum ApoA1, total cholesterol, and HDL-c and hepatic ApoA1 levels were measured after intraperitoneal administration of NPY or an NPY Y5 receptor (NPY5R) agonist in vivo. HepG2 and BRL-3A hepatocytes were treated in vitro with NPY in the presence or absence of NPY receptor antagonists, agonists, or signal transduction pathway inhibitors. Subsequently, the protein and mRNA expression of cellular and secreted ApoA1 were determined., Results: NPY considerably upregulated hepatic ApoA1 expression and stimulated ApoA1 secretion, both in vivo and in vitro. NPY5R inhibition blocked NPY-induced upregulation of ApoA1 expression, and NPY5R activation stimulated ApoA1 expression and secretion in hepatocytes. Moreover, extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) and protein kinase A (PKA) inhibition almost completely blocked the upregulation of ApoA1 expression and secretion induced by NPY5R., Conclusions: For the first time, we demonstrated that NPY5R activation promotes hepatic ApoA1 synthesis and secretion through the ERK1/2 and PKA signal transduction pathways. Thus, NPY5R may be a potential therapeutic target for treating CVD by promoting cholesterol reverse transport., (Copyright © 2022 Elsevier Inc. All rights reserved.)

We previously demonstrated that Npy1r rfb mice, which carry the conditional inactivation of the Npy1r gene in forebrain principal neurons, display a sexually dimorphic phenotype, with male mice showing metabolic, hormonal and behavioral effects and females being only marginally affected. Moreover, exposure of Npy1r rfb male mice to a high-fat diet (HFD) increased body weight growth, adipose tissue, blood glucose levels and caloric intake compared to Npy1r 2lox male controls. We used conditional knockout Npy1r rfb and Npy1r 2lox control mice to examine whether forebrain disruption of the Npy1r gene affects susceptibility to obesity and associated disorders of cycling and ovariectomized (ovx) female mice in a standard diet (SD) regimen or exposed to an HFD for 3 months. The conditional deletion of the Npy1r gene increased body weight and subcutaneous white adipose tissue weight in both SD- and HFD-fed ovx females but not in cycling females. Moreover, compared with ovx control females on the same diet regimen, Npy1r rfb females displayed increased microglia number and activation, increased expression of Neuropeptide Y (NPY)-immunoreactivity (IR) and decreased expression of proopiomelanocortin-IR in the hypothalamic arcuate nucleus (ARC). These results suggest that in the ARC NPY-Y1R reduces the susceptibility to obesity of female mice with low levels of gonadal hormones and that this effect may be mediated via NPY-Y1R ability to protect the brain against neuroinflammation.

Neuropeptide Y (NPY) is a significant neuromodulator implicated in a multitude of physiological functions via activating NPY receptors which belong to seven transmembrane G-protein-coupled receptors (GPCRs). However, the detailed cellular expression of NPY receptors in retina has been scarcely investigated. In this study, the expression of the special NPY4R receptor in rat retina was assessed using Western blot analysis and immunofluorescent staining. The detailed cellular localization of NPY4R receptor was studied using double immunofluorescent staining and laser-scanning confocal microscopy. Our data demonstrated that NPY4R receptor was weakly expressed in the inner segment of outer photoreceptors and extensively expressed in the outer segment of S-opsin-positive blue cones, L/M-opsin-positive red/green cones and in the somata of CB-positive horizontal cells, GAD65-positive GABAnergic amacrine cells, ChAT-positive cholinergic amacrine cells, TH-positive dopaminergic CA1 amacrine cells and CA2 amacrine cells, PV-positive AII amacrine cells, Brn3a-positive conventional ganglion cells and melanopsin-containing ipRGCs. In addition, NPY4R receptor was diffusely distributed throughout the full thickness of the inner plexiform layer and outer plexiform layer. However, the outer segment of Rho4D2-positive rods, the somata of ChX10-positive bipolar cells and CRALBP-positive Müller glial cells seemed to lack immunoreactivity of NPY4R receptor. The new finding that multiple types of retinal cell express NPY4R receptor provides new neurobiological basis for the participation of NPY in the regulation of retinal functions through activating NPY4R receptor., (Copyright © 2022. Published by Elsevier Ltd.)

Adverse prognosis in Ewing sarcoma (ES) is associated with the presence of metastases, particularly in bone, tumor hypoxia and chromosomal instability (CIN). Yet, a mechanistic link between these factors remains unknown. We demonstrate that in ES, tumor hypoxia selectively exacerbates bone metastasis. This process is triggered by hypoxia-induced stimulation of the neuropeptide Y (NPY)/Y5 receptor (Y5R) pathway, which leads to RhoA over-activation and cytokinesis failure. These mitotic defects result in the formation of polyploid ES cells, the progeny of which exhibit high CIN, an ability to invade and colonize bone, and a resistance to chemotherapy. Blocking Y5R in hypoxic ES tumors prevents polyploidization and bone metastasis. Our findings provide evidence for the role of the hypoxia-inducible NPY/Y5R/RhoA axis in promoting genomic changes and subsequent osseous dissemination in ES, and suggest that targeting this pathway may prevent CIN and disease progression in ES and other cancers rich in NPY and Y5R., (© 2022. The Author(s).)

Neuropeptide Y (NPY) is a highly conserved endogenous peptide in the central and peripheral nervous systems, which has been implicated in nociceptive signaling in neuropathic pain. However, downstream mechanistic actions remain uncharacterized. In this study, we sought to investigate the mechanism of NPY and its receptor NPY2R in the amygdala in rats with neuropathic pain-like behaviors induced by chronic constriction injury (CCI) of the sciatic nerve. The expression of NPY and NPY2R was found to be aberrantly up-regulated in neuropathic pain-related microarray dataset. Further, NPY was found to act on NPY2R in the basolateral amygdala (BLA). As reflected by the decrease in mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) as well as the increase of NPY expression in the amygdala of rats with neuropathic pain-like behaviors, NPY was closely related to the effect of amygdala nerve activity in neuropathic pain. Subsequently, mechanistic investigations indicated that NPY2R activated the MAPK signaling pathway in the amygdala. NPY2R-induced decrease of MWT and TWL were also restored in the presence of MAPK signaling pathway antagonist. Moreover, it was revealed that NPY2R overexpression promoted the viability while inhibiting the apoptosis of microglia. Taken together, NPY in the amygdala interacts with NPY2R to activate the MAPK signaling pathway, thereby promoting the occurrence of neuropathic pain.