Neuropeptide Y Receptor Research Articles

Neuropeptide Y1 receptor antagonist but not neuropeptide Y itself increased bone mineral density when locally injected with hyaluronic acid in male Wistar rats

Background/aim The nervous system controls bone mass via both the central (CNS) and the peripheral (PNS) nervous systems. Intriguingly, neuropeptide Y (NPY) signaling occurs in both. Less is known on how the PNS stimulated NPY signaling controls bone metabolism. The objective of this study was to evaluate whether NPY or NPY1 receptor antagonist changes local bone mineral density (BMD) when injected into a Wistar rat tibia. Materials and methodsTibial intramedullary area of 24 wild type male Wistar rats (average weight = 350 ± 50 g, average age = 4 ± 0.5 months) were injected with NPY (1 × 10-5 M and 1 × 10-6 M) and NPY1 receptor antagonist (1 × 10-4 M) dissolved in hyaluronic acid (HA) separately. Tibiae were collected after one and two weeks. BMD was measured with dual-energy X-ray absorptiometry (DXA) and micro quantitative computer tomography (QCT). Histological changes were analyzed with light microscopy, Goldner's Masson trichrome (MT), and hematoxylin-eosin staining.ResultsAccording to DXA , the mean BMD of NPY dose 1 (1 × 10-5 M) was significantly lower than that of the control (HA applied) group and not significantly but still lower than that of the NPY dose 2 and NPY1 antagonist applied groups. QCT results indicated the same pattern statistically insignificantly in the trabecular area but not in the cortex of the bones. Histologically, only NPY1 antagonist applied tibiae revealed young spongiosis bone trabeculae formed in the borderline of the cortical bones. HA was remarkably biocompatible and late degrading in the tissues. Conclusion Local administration of NPY and NPY1 antagonists may hold regulating potential of BMD and bone formation. NPY1 antagonist caused new bone formation in trabecular bone when applied locally. NPY dissolved in HA however can be used to suppress bone formation.

Central injection of neuropeptide Y modulates sexual behavior in male rats: interaction with GnRH and kisspeptin/neurokinin B/dynorphin

Aims A number of studies have shown that neuropeptide Y (NPY) is considered to be one of the key regulators of hypothalamic-pituitary-gonadal (HPG) axis in the mammals. In addition, kisspeptin (encode by Kiss1 gene), neurokinin B (encode by Tac3 gene) and dynorphin (encode by Pdyn gene) (commonly known as KNDy secreting neurons) are a powerful upstream regulators of GnRH neuron in hypothalamus. Materials and Methods The present study aims to investigate the effects of the intracerebroventricular (icv) injection of NPY and BIBP3226 (NPY receptor antagonist (NPYRA)) on the male sexual behavioral. Additionally, in order to see whether NPY signals can be relayed through the pathway of kisspeptin/neurokinin B/dynorphin, the gene expression of these peptides along with Gnrh1 gene in the hypothalamus were measured. Results The icv injection of NPY decreased the latencies and increase the frequencies of sexual parameters of the male rats in a significant way. In this line, NPYRA antagonized the stimulative effects of NPY. Moreover, data from real-time quantitative PCR indicated that injection of NPY significantly increased the gene expression of Gnrh1, Kiss1 and Tac3 and decrease the Pdyn while treatment with NPYRA controlled the modulative effects of NPY on these gene expression. Conclusions In conclusion based on the results of this study, NPY can exert its impacts on the sexual behavior of male rats via modulation of the KNDy secreting neurons as an interneural pathway to GnRH neurons.

Molecular crosstalk between Y5 receptor and neuropeptide Y drives liver cancer

Hepatocellular carcinoma (HCC) is clearly age-related and represents one of the deadliest cancer types worldwide. As a result of globally increasing risk factors including metabolic disorders, the incidence rates of HCC are still rising. However, the molecular hallmarks of HCC remain poorly understood. Neuropeptide Y (NPY) and NPY receptors represent a highly conserved, stress-activated system involved in diverse cancer-related hallmarks including aging and metabolic alterations, but its impact on liver cancer had been unclear. Here, we observed increased expression of NPY5 receptor (Y5R) in HCC, which correlated with tumor growth and survival. Furthermore, we found that its ligand NPY was secreted by peritumorous hepatocytes. Hepatocyte-derived NPY promoted HCC progression by Y5R activation. TGF-β1 was identified as a regulator of NPY in hepatocytes and induced Y5R in invasive cancer cells. Moreover, NPY conversion by dipeptidylpeptidase 4 (DPP4) augmented Y5R activation and function in liver cancer. The TGF-β/NPY/Y5R axis and DPP4 represent attractive therapeutic targets for controlling liver cancer progression.

Candidate genes for predicting the survival of patients with gastric cancer: a study based on The Cancer Genome Atlas (TCGA) database.

BackgroundGastric cancer (GC) is the second most frequent cause of cancer-related mortality in the world, and the five-year survival rate for GC remains very low universally. In recent years, it has become a consensus that genetic changes are associated with carcinogenesis of GC, and precision medicine based on genetic changes is one of the most popular treatments for GC patients. However, the association between some genes and GC-related protein signaling pathways is still not well understood. This study revealed that seven genes were closely related to the survival probability in GC patients.MethodsWe downloaded the gene expression data of GC patients from The Cancer Genome Atlas (TCGA) databases, and integrated bioinformatic analysis was performed, such as differential gene expression analysis, including Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) pathways analyses, as well as survival analysis. The r package “survival” was used to analyze the Kaplan-Meier survival analysis, which showed the associations between specific gene expressions and the outcomes of patients with GC to identify which genes could be potential prognostic biomarkers.ResultsThis study revealed that seven genes: alcohol dehydrogenase 4 (ADH4), histamine receptor H3 (HRH3), neuropeptide Y2 receptor (NPY2R), apolipoprotein AI (APOA1), N-acetylgalactosaminyltransferase 14 (GALNT14), leucine-rich repeats and IQ motif containing 1 (LRRIQ1), and coiled-coil-domain-containing 57 (CCDC57). These seven genes were closely related to the survival probability of GC patients (P<0.05).ConclusionsOur study found seven genes which could be considered as candidate prognostic biomarkers and therapeutic targets.

Neuropeptide Y (NPY) receptor 2 deletion in adipocytes blunts fat‐derived aldosterone production in female mice exposed to chronic stress

NPY is a 36‐amino acid peptide that plays a critical role in the regulation of energy homeostasis. In response to chronic environmental stress, NPY released by neurons innervating the fat promotes adipocyte proliferation and lipid storage via NPY receptor 2 (Y2). Y2 also stimulates aldosterone synthesis in the adrenal gland; however, little is known about its role in the regulation of aldosterone secretion in adipose tissue. We have previously shown that Maternal Separation and Early Weaning (MSEW), a mouse model of early life stress, exacerbates high fat diet (HF)‐induced adiposity and increases circulating aldosterone in female mice but not in males. Thus, the aim of this study was to investigate the effect of MSEW on chronic stress‐induced aldosterone release by adipose tissue with or without the deletion of Y2. In addition, we tested the capacity of adipose tissue conditioned media from these mice to modulate the endothelial function of aortic rings ex‐vivo. Y2‐WT and Y2‐KO pups were separated from the dam for 4 to 8 hours during postnatal days (PD) 2 to 16 and weaned on PD 17. Control mice remained undisturbed and were weaned on PD 21. At weaning, female mice were fed a HF (60% Kcal from fat) for 16 weeks. Following, a subset of mice were subjected to restraint stress (RS) for 6 more consecutive weeks and the other one was not disturbed (NORS). At the end of the experiment, mice were euthanized, and ~50 mg of fresh adipose tissue was incubated in DMEM + 2% fatty acid free BSA (1 hour, 37°C). Aldosterone concentration was measured in media explants by ELISA. Visceral adipose tissue‐derived aldosterone secretion was similar in WT MSEW and control explants from NORS mice (3.22±0.21 vs 3.50±0.76 pg/mg tissue). RS increased aldosterone levels in the media explant from MSEW mice compared to controls (5.34±0.85 vs. 2.96±0.35 pg/mg tissue). The deletion of Y2 from adipose tissue depots attenuated the increased aldosterone release in response to RS in MSEW mice only (5.34±0.85 to 3.46±0.21 pg/mg tissue; p &lt; 0.05). In additional studies, we used perivascular adipose tissue (PVAT) and mesenteric adipose tissue (MESAT) media explants from RS control and MSEW mice to test their effect on acetylcholine (Ach)‐dependent relaxation (pre‐constricted with ser 10−3 M, 3 ul). We performed relaxation dose‐response curves in thoracic aortic rings from healthy female mice (16‐week‐old fed a regular chow) before and after the incubation with fat explants. We found similar worsening of the baseline vascular relaxation when we incubated rings with PVAT media from MSEW and controls (14.38±4.58 vs. 19.95±3.80 Delta % relaxation). However, rings incubated with MESAT from MSEW mice showed significant worsening of the vascular relaxation compared to controls (26.71±4.44 vs. 12.43±2.63 Delta % relaxation, p&lt;0.05). Y2 deletion protected the vascular function in both groups. Taken together, female MSEW mice exposed to RS are prone to release aldosterone from adipose tissue, dependent upon Y2 signaling. Increased aldosterone release near vessels may explain impaired endothelial function, which could be prevented by targeting adipose tissue Y2.Support or Funding InformationR01 HL135158

In Female Rats, the Sympathoexcitatory and Pressor Actions of Arcuate Nucleus Angiotensin II Vary During the Estrus Cycle and are Mediated by Inhibition of Neuropeptide Y, and Excitation of α‐Melanocyte Stimulating Hormone, Projections to the Hypothalamic Paraventricular Nucleus

In male rats, nanoinjections of Angiotensin II (AngII) into the arcuate nucleus (ArcN) increases sympathetic nerve activity (SNA) by suppressing tonic sympathoinhibitory Neuropeptide Y (NPY) inputs, and activating excitatory pro‐opiomelanocortin (POMC) inputs that release alpha melanocyte stimulating hormone (α‐MSH), into the hypothalamic paraventricular nucleus (PVN). In female rats, ArcN AngII AT1a receptor (AT1aR) expression is generally higher than in males, but varies with the estrus cycle (highest during estrus; lowest during proestrus). However, whether ArcN AngII increases SNA in females, or if the response varies during the cycle, is unknown. Therefore, we tested bilateral ArcN AngII injections (30 pmol in 30 nL) in α‐chloralose anesthetized female rats throughout the reproductive cycle, and found that 90 min after ArcN AngII injections, LSNA increased (P&lt;0.05) in rats during estrus (by 72±12 %; n=6) and diestrus (by 40±9 %; n=4), but not proestrus (−1±8 %; n=5). ArcN AngII also induced an initial rapid rise (P&lt;0.05) in mean arterial pressure (MAP) in all groups (estrus: 13±2 mmHg; diestrus: 11±3 mmHg; proestrus: 13±3 mmHg), but the increase was sustained only in estrus rats (by 12±2 mmHg; P&lt;0.05). We next tested if ArcN AngII suppresses inhibitory NPY inputs by determining if blockade of PVN NPY Y1 receptors (Y1R) with bilateral nanoinjections of BIBO3304 (60 pmol/60nL) elicits smaller increases in MAP and LSNA 60 min after nanoinjection of AngII into the ArcN. As previously reported, PVN injections of BIBO3304 (without ArcN AngII; n=3) increased (P&lt;0.05) LSNA (by 34±6 %) and MAP (by 10±1 mmHg). However, the increases (P&lt;0.05) in LSNA (to 93±16 %) and MAP (by 19±1 mmHg) (n=4) following ArcN AngII and PVN BIBO3304 were the same as ArcN AngII followed by PVN artificial cerebrospinal fluid (n=3; LSNA by 107±30 % and MAP by 17±4 mmHg). Thus, ArcN AngII markedly attenuated the pressor and sympathoexcitatory effects of blockade of PVN Y1R, indicating that AngII increases LSNA and MAP in part by inhibition of NPY projections to the PVN. Finally, because suppression of tonic NPY inhibition of PVN presympathetic neurons permits increased activation of PVN α‐MSH receptors (MC4R), we tested if blockade of PVN MC4R with SHU9119 decreases LSNA and MAP 90 min after ArcN AngII (n=4). Indeed, bilateral PVN SHU9119 decreased (P&lt;0.05) LSNA (by 30±10 %) and MAP (by 10±1 mmHg). In conclusion, in females as in males, ArcN AngII increases SNA and MAP by inhibiting NPY inputs and increasing α‐MSH inputs into the PVN. However, these effects vary during the estrus cycle in parallel to AngII AT1aR expression: highest during estrus and undetectable during proestrus.Support or Funding InformationHL128181

Neuropeptide Y Inputs to Neurons in the Dorsomedial Hypothalamus Tonically Inhibit Brown Adipose Tissue (BAT) Sympathetic Nerve Activity (SNA) via NPY Y1 Receptors

Hypothalamic Neuropeptide Y (NPY) has been implicated in metabolic homeostasis. For example, NPY acts in the paraventricular nucleus of the hypothalamus to decrease BAT SNA. NPY neurons within the dorsomedial hypothalamus (DMH) have also been implicated in energy balance, however the role of NPY inputs to BAT regulatory neurons in the DMH has not been assessed. The present study tested the hypothesis that neurons in the DMH receive a NPY‐containing input that contributes to the regulation of BAT SNA via activation of NPY Y1 receptors. First, administration of a retrograde tracer (cholera toxin B) into the raphe pallidus area (RPa) and immunohistochemistry for NPY demonstrated that CtB‐labeled (RPa‐projecting) DMH neurons receive close appositions from NPY‐positive fibers. In addition, bilateral nanoninjections of the NPY Y1 receptor antagonist BIBO3304 (2mM, 60nl) into the DMH increased BAT SNA +424±110% baseline, TBAT (+2.2±0.5 °C) and expired CO2 (+1.2±0.1%). In conclusion, NPY inputs to neurons in the DMH tonically inhibit BAT SNA and BAT thermogenesis via activation of NPY Y1 receptors.Support or Funding InformationNIH DK112198

Unusually persistent G\u03b1i-signaling of the neuropeptide Y2 receptor depletes cellular Gi/o pools and leads to a Gi-refractory state

BackgroundA sensitive balance between receptor activation and desensitization is crucial for cellular homeostasis. Like many other GPCR, the human neuropeptide Y2 receptor (hY2R) undergoes ligand dependent activation and internalization into intracellular compartments, followed by recycling to the plasma membrane. This receptor is involved in the pathophysiology of distinct diseases e.g. epilepsy and cancer progression and conveys anorexigenic signals which makes it an interesting and promising anti-obesity target. However, Y2R desensitization was observed after daily treatment with a selective PYY13–36 analog in vivo by a yet unknown mechanism.MaterialsWe studied the desensitization and activatability of recycled Y2R in transiently transfected HEK293 cells as well as in endogenously Y2R expressing SH-SY5Y and SMS-KAN cells. Results were evaluated by one-way ANOVA and Tukey post test.ResultsWe observed strong desensitization of the Y2R in a second round of stimulation despite its reappearance at the membrane. Already the first activation of the Y2R leads to depletion of the functional cellular Gαi/o protein pool and consequently desensitizes the linked signal transduction pathways, independent of receptor internalization. This desensitization also extends to other Gαi/o-coupled GPCR and can be detected in transfected HEK293 as well as in SH-SY5Y and SMS-KAN cell lines, both expressing the Y2R endogenously. By overexpression of chimeric Gαqi proteins in a model system, activation has been rescued, which identifies a critical role of the G protein status for cellular signaling. Furthermore, Y2R displays strong allosteric coupling to inhibitory G proteins in radioligand binding assays, and loses 10-fold affinity in the G protein-depleted state observed after activation, which can be largely abrogated by overexpression of the Gαi-subunit.ConclusionThe unusually persistent Gαi-signaling of the Y2R leads to a state of cellular desensitization of the inhibitory Gαi-pathway. The strong allosteric effects of the Y2R-Gαi-interaction might be a mechanism that contributes to the burst of Gαi-signaling, but also serves as a mechanism to limit the Y2-mediated signaling after recycling. Thus, the cell is left in a refractory state, preventing further Gαi-signaling of the Y2R itself but also other Gαi/o-coupled receptors by simply controlling the repertoire of downstream effectors.BuwH6WrTd3LsdoK61ytbqiVideo abstractGraphical abstract

Contribution of NPY Y5 Receptors to the Reversible Structural Remodeling of Basolateral Amygdala Dendrites in Male Rats Associated with NPY-Mediated Stress Resilience.

Endogenous neuropeptide Y (NPY) and corticotrophin-releasing factor (CRF) modulate the responses of the basolateral amygdala (BLA) to stress and are associated with the development of stress resilience and vulnerability, respectively. We characterized persistent effects of repeated NPY and CRF treatment on the structure and function of BLA principal neurons in a novel organotypic slice culture (OTC) model of male rat BLA, and examined the contributions of specific NPY receptor subtypes to these neural and behavioral effects. In BLA principal neurons within the OTCs, repeated NPY treatment caused persistent attenuation of excitatory input and induced dendritic hypotrophy via Y5 receptor activation; conversely, CRF increased excitatory input and induced hypertrophy of BLA principal neurons. Repeated treatment of OTCs with NPY followed by an identical treatment with CRF, or vice versa, inhibited or reversed all structural changes in OTCs. These structural responses to NPY or CRF required calcineurin or CaMKII, respectively. Finally, repeated intra-BLA injections of NPY or a Y5 receptor agonist increased social interaction, a validated behavior for anxiety, and recapitulated structural changes in BLA neurons seen in OTCs, while a Y5 receptor antagonist prevented NPY's effects both on behavior and on structure. These results implicate the Y5 receptor in the long-term, anxiolytic-like effects of NPY in the BLA, consistent with an intrinsic role in stress buffering, and highlight a remarkable mechanism by which BLA neurons may adapt to different levels of stress. Moreover, BLA OTCs offer a robust model to study mechanisms associated with resilience and vulnerability to stress in BLA.SIGNIFICANCE STATEMENT Within the basolateral amygdala (BLA), neuropeptide Y (NPY) is associated with buffering the neural stress response induced by corticotropin releasing factor, and promoting stress resilience. We used a novel organotypic slice culture model of BLA, complemented with in vivo studies, to examine the cellular mechanisms associated with the actions of NPY. In organotypic slice cultures, repeated NPY treatment reduces the complexity of the dendritic extent of anxiogenic BLA principal neurons, making them less excitable. NPY, via activation of Y5 receptors, additionally inhibits and reverses the increases in dendritic extent and excitability induced by the stress hormone, corticotropin releasing factor. This NPY-mediated neuroplasticity indicates that resilience or vulnerability to stress may thus involve neuropeptide-mediated dendritic remodeling in BLA principal neurons.

Intra-articular injection of 2-pyridylethylamine produces spinal NPY-mediated antinociception in the formalin-induced rat knee-joint pain model

Low doses of histamine or H1R agonist 2-pyridylethylamine (2-PEA) into the knee-joint were found to decrease formalin-induced articular nociception in rats. In this study, we evaluated the participation of spinal NPY in the antinociceptive effect produced by 2-PEA. Injection of formalin (1.5%) into one of the knee-joints causes the limping of the respective limb due to nociception, which was registered each 5 min over 60 min. Neuropeptide Y1 receptor (Y1R) content in the spinal cord was evaluated by western-blotting. Intrathecal (i.t.) injection of Y1R agonist Leu31, Pro34-NPY (0.7–7 µmol) decreased nociception, while injection of the antagonist BIBO 3304 (4 μmol), increased nociception. Antinociception produced by 2-PEA was reversed by a sub-effective i.t. dose of the Y1R antagonist. Similarly, this antinociceptive effect was prevented by i.t. pretreatment with the neurotoxin NPY-saporin (750 ng), which also reduced immunoblotting for Y1R in spinal cord homogenates. These data support the idea that antinociception induced by H1R agonists in the knee-joint of rats may be mediated by the spinal release of NPY, and this peptide seems to be acting via Y1R.

Japanese Herbal Medicine Ninjinyoeito Mediates Its Orexigenic Properties Partially by Activating Orexin 1 Receptors.

Cancer cachexia is highly prevalent in patients with progressive cancer and is characterized by decreased food consumption, and body weight. Japanese herbal medicine Ninjinyoeito (NYT), composed of 12 herbal crude drugs, is prescribed in Asian countries to improve several symptoms such as anorexia and fatigue, which are commonly observed in patients with cancer cachexia. However, the action mechanisms of NYT in improving anorexia or fatigue in patients with cancer are not clear. Therefore, in the present study, we examined the effects of NYT on the activities of several G-protein-coupled receptors (GPCRs), which activate hyperphagia signaling in the central nervous system, using an in vitro assay with the CellKey™ system, which detects the activation of GPCRs as a change in intracellular impedance (ΔZ). NYT increased the ΔZ of human embryonic kidney 293 (HEK293) cells expressing orexin 1 receptor (OX1R) and those expressing neuropeptide Y1 receptor (NPY1R) in a dose-dependent manner. On the contrary, NYT did not significantly increase the ΔZ of HEK293A cells expressing growth hormone secretagogue receptor (GHSR) and those expressing NPY5R. The selective OX1R antagonist SB674042 significantly decreased the NYT-induced increase in ΔZ in OX1R-expressing cells. Contrarily, the selective NPY1R antagonist BIBO3340 failed to inhibit the NPY-induced increase in ΔZ in NPY1R-expressing cells. Additionally, we prepared modified NYT excluding each one of the 12 herbal crude drugs in NYT and investigated the effects on the activity of OX1R. Among the 12 modified NYT formulations, the one without citrus unshiu peel failed to activate OX1R. A screening of each of the 12 herbal crude drugs showed that citrus unshiu peel significantly activated OX1R, which was significantly suppressed by SB674042. These finding suggest that NYT and citrus unshiu peel could increase food intake via activation of orexigenic OX1R-expressing neurons in the hypothalamus. This study provides scientific evidence to support the potential of NYT for cancer patients with anorexia.

Neuropeptide Y Acts Directly on Cartilage Homeostasis and Exacerbates Progression of Osteoarthritis Through NPY2R.

Neuropeptide Y (NPY) is known to regulate bone homeostasis; however, its functional role as a risk factor during osteoarthritis (OA) remains elusive. In this study, we aim to investigate the direct effect of NPY on degradation of cartilage and progression of OA and explore the molecular events involved. NPY was overexpressed in human OA cartilage accompanied with increased expression of NPY1 receptor (NPY1R) and NPY2 receptor (NPY2R). Stressors such as cold exposure resulted in the peripheral release of NPY from sympathetic nerves, which in turn promoted upregulation of NPY and NPY2R in articular cartilage in vivo. Intra-articular administration of NPY significantly promoted chondrocyte hypertrophy and cartilage matrix degradation, with a higher OARSI score than that of control mice, whereas inhibition of NPY2R but not NPY1R with its specific antagonist remarkably ameliorated NPY-mediated effects. Moreover, NPY activated mTORC1 pathway in articular chondrocytes, whereas the administration of rapamycin (an mTORC1 inhibitor) in vitro abrogated NPY-mediated effects. Mechanistically, mTORC1 downstream kinase S6K1 interacted with and phosphorylated SMAD1/5/8 and promoted SMAD4 nuclear translocation, resulting in upregulation of Runx2 expression to promote chondrocyte hypertrophy and cartilage degradation. In conclusion, our findings provided the direct evidence and the crucial role of NPY in cartilage homeostasis. © 2020 American Society for Bone and Mineral Research.

Correlation of neuropeptides substance P and neuropeptide Y and their receptors with fracture healing in rats

Bone fracture healing is a complex process involving a cascade of cellular and molecular events that are orchestrated by a variety of factors, including neuropeptides and their receptors. However, the roles of neuropeptides and their receptors in the fracture healing process are controversial. We monitored the expression and distribution of the neuropeptides, substance P (SP) and neuropeptide Y (NPY) and their receptors, neurokinin 1 receptor (NK1) and neuropeptide Y1 receptor (NPY1R), in rats undergoing fracture healing. Total RNA was extracted using Fe3O4 and was retrieved into DNA using the MagBeads Total RNA Extraction Kit. The expression levels of SP, NK1, and NPY at each time point in the healing bone tissue were found to be higher than the levels in normal bone tissue. Their location and expression levels correlated with the healing process. In the callus formation stage, the expression levels of SP, NK1, and NPY were found to be increased in the matrix of the cartilage, in chondrocytes, and in the subperiosteal region. At the bone remodeling stage, they were located in the periosteum, new bone tissue, and perivascular regions, and their expression levels gradually reduced. Therefore, we conclude that SP was involved in callus formation and bone resorption at different physiological concentrations. At some concentrations, SP positively regulated new bone formation via NK1. At other concentrations, the SP-NK1 interaction promoted bone resorption. Very low expression levels of NPY1R were observed at the early healing stage, but they increased at the middle stage and then decreased at the late stage. This indicated that NPY was involved in bone formation through NPY1R-unrelated mechanisms. NPY1R was more involved at the later stage of bone remodeling, according to its expression levels. NPY1R contributed to callus formation and remodeling.

Development and characterisation of a peptidergic N-and C-terminally stabilised mammalian NPY1R agonist which protects against diabetes induction

BackgroundPYY (1–36) peptides from phylogenetically ancient fish, such as sea lamprey, have previously been shown to function as specific neuropeptide Y1 receptor (NPYR1) agonists. Although, sea lamprey PYY (1–36) is N-terminally stable, we reveal in this study that the peptide is subject to endopeptidase mediated C-terminal dipeptide degradation. In an attempt to prevent this, (d-Arg35)-sea lamprey PYY (1–36) was developed. MethodsIn vitro bioassays assessed enzymatic stability, insulinostatic activity as well as beta-cell anti-apoptotic actions of (d-Arg35)-sea lamprey PYY (1–36). Follow-up studies examined the impact of twice daily administration of sea lamprey PYY (1–36) or (d-Arg35)-sea lamprey PYY (1–36) in multiple low dose STZ-induced diabetic mice. Results(d-Arg35)-sea lamprey PYY (1–36) was fully resistant to plasma enzymatic degradation. The peptide possessed similar significant insulinostatic, as well as positive anti-apoptotic biological actions, as the parent peptide. Sea lamprey PYY (1–36) and (d-Arg35)-sea lamprey PYY (1–36) delayed diabetes progression in STZ mice. Both treatment interventions induced a significant decrease in body weight, food and fluid intake as well as glucose and glucagon concentrations. In addition, glucose tolerance, plasma and pancreatic insulin were partially normalised. (d-Arg35)-sea lamprey PYY (1–36) was significantly more effective than sea lamprey PYY (1–36) in terms of enhancing glucose-stimulate insulin release. Both treatments improved pancreatic islet morphology, linked to decreased apoptosis of beta-cells. ConclusionWe present (d-Arg35)-sea lamprey PYY (1–36) as the first-in-class N- and C-terminally stable PYY (1–36) peptide analogue. General significanceEnzymatically stable, long-acting PYY (1–36) peptides highlight the therapeutic benefits of sustained activation of NPYR1's in diabetes.

Effect of cannabinoid-serotonin interactions in the regulation of neuropeptide Y1 receptors expression in rats: the role of CB1 and 5-HT2C receptor

Neuropeptide Y (NPY) is involved in a diversity of critical functions such as circadian rhythms, energy homeostasis, and appetite regulation in the hypothalamus. It has identified as a crucial participant in adjusting energy intake and energy storage as fat via central neuropeptide Y1 receptor (NPY1R), leading to obesity and metabolic disorders. The present study was expected to investigate the interaction between 2-AG (CB1R agonist), m-CPP (5HT2CR agonist), SB-242084 (5HT2CR antagonist), and SR-141716A (CB1R antagonist) by mediating through the NPY1R for treating or preventing obesity, metabolic disorders, and other abnormalities. The expression level of NPY1R mRNA has studied on the rat brain by real-time quantitative PCR assay. Based on our findings, intracerebroventricular (ICV) injection of combined 2-AG (1 μg) + m-CPP (2.5 μg) has antagonistic interaction in the expression of the NPY1R gene (P < 0.001). Moreover, the ICV co-injection of SB-242084 (3 μg) + SR-141716A (1 μg) has antagonistic interaction in the NPY1R gene expression (P < 0.001). Co-administration of 2-AG (1 μg) + SB-242084 (3 μg) amplified NPY1R gene expression (P < 0.001), while the ICV co-injection of m-CPP (2.5 μg) + SR-141716A (1 μg) decreased NPY1R gene expression in the hypothalamus (P < 0.001). These results revealed the interference in cannabinoid and serotonergic systems via CB1 and 5HT2C receptors in the expression of NPY1R mRNA in the hypothalamic area of rats.

Decreased Level of Neuropeptide Y Is Associated With Gastroparesis in Male Diabetic Rats.

BackgroundSubstance P (SP) and neuropeptide Y (NPY), excitatory and inhibitory neuropeptides, respectively, may impact gastric motility in patients with diabetic mellitus (DM). We investigated these neuropeptide levels, NPY receptors, total nitric oxide synthase (NOS) levels, and neuronal NOS alpha (nNOSα) activation status and levels in streptozotocin-induced type I diabetes in male rats.MethodsRats were grouped based on serum glucose and gastric emptying time: normal untreated control (CM), diabetic (DM) and diabetic gastroparesis (DM + GP). Neuropeptide serum levels were determined by enzyme-linked immunosorbent assay (ELISA). Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting measured NPY receptors, Y1 and Y2, and nNOSα expression. Low-temperature SDS-PAGE followed by western blotting was used to measure the dimerization of nNOSα. An NOS colorimetric assay kit was used to measure total NOS activity.ResultsSP levels were significantly decreased (P < 0.05) in DM and DM + GP compared to CM. NPY levels were significantly decreased (P < 0.05) in DM compared to CM, and DM + GP had a more significantly decreased NPY when compared to both DM and CM. Protein levels of neuropeptide receptor Y1 (NPY-Y1) in the smooth muscle of pylorus were significantly increased in DM, but not in DM + GP when compared to CM. Neuropeptide receptor Y2 (NPY-Y2) was not detected. Changes in nNOSα activity and their protein levels, as well as total NOS activity, among the groups were insignificant.ConclusionsIncreased expression of pylorus NPY-1R and decreased serum NPY are present in diabetes. A more pronounced decreased serum NPY with no NPY-1R upregulation in pyloric smooth muscle is associated with gastroparesis. NPY levels show no relationship with nNOSα levels, their activation status, or total NOS activity in pyloric smooth muscle. These data suggest a pathophysiological role of severely depleted NPY and absence of NPY-Y1 upregulation for gastroparesis phenotype.

The role of neuropeptide Y for the development of allergic airway responses

Neuropeptide Y (NPY) is a neurotransmitter that is widely expressed in the brain and peripheral nervous system. Various immune cells express the receptor for NPY, Y1 receptor. NPY modulates these cells via its Y1 receptor, and involvement of NPY in the pathophysiology of bronchial asthma, has been reported. Increased plasma levels of NPY in asthmatic patients have been reported. NPY polymorphisms are associated with an increased risk for asthma in overweight subjects and young adults. We and other researchers have reported that using murine models of allergic airway responses, NPY and Y1 receptor play critical roles for the development of allergic airway inflammation and airway hyperresponsiveness. Therefore, manipulating NPY-Y1 pathway represents a novel therapeutic target to control allergic airway responses, and might be beneficial for treatment of bronchial asthma.

The effect of intracerebroventricular administration of neuropeptide Y on reproductive axis function in the male Wistar rats: Involvement of hypothalamic KiSS1/GPR54 system.

Several studies have shown that neuropeptide Y (NPY) is considered to be one of the key regulators of the hypothalamic-pituitary-gonadal axis in the mammals. Also, kisspeptin is a powerful upstream regulator of gonadotropin-releasing hormone neurons in the hypothalamus. The present study aims to investigate the effects of the intracerebroventricular (ICV) injection of NPY and BIBP3226 (NPY receptor antagonist) on the reproductive axis (either hormonal or behavioral) of the male rats. Furthermore, to see whether NPY signals can be relayed through the pathway of KiSS1/GPR54, the gene expression of these peptides in the arcuate nucleus was measured. The ICV injection of NPY decreased the latencies and increased the frequencies of sexual parameters of the male rats in a significant way. Results obtained from LH and testosterone measurement showed that NPY had a significant increase in comparison with the control group. In this line, BIBP3226 antagonized the stimulative effects of NPY. Furthermore, data from real-time quantitative PCR showed that injection of NPY significantly increased the gene expression of KiSS1 and GPR54, while treatment with BIBP3226 controlled the stimulative effects of NPY on gene expression of KiSS1 and GPR54. Summing up, NPY can exert its impacts on the reproductive axis, this occurs at least partly through affecting KiSS1/GPR54 system.

Upregulation of Kiss-1 and Gpr54 Genes Expression in Pituitary of Male Rats Following the Central Administration of Neuropeptide Y

Introduction: The neuropeptide Y (NPY) in the neural circuits of the hypothalamus has a stimulating effect on reproductive activities in mammals. Kisspeptin (KiSS1) is a quintessential neurotransmitter in the reproductive axis which directly stimulates gonadotropin-releasing hormone neurons in the hypothalamus. The distribution of KiSS1 expressing cells in the pituitary was described previously. Despite earlier reports showing the KiSS1 receptor, G-protein coupled receptor 54 (GPR54) expression in the pituitary, the potential physiological roles of kisspeptin at this gland have remained obscure. Accordingly, this study investigated the role of NPY on the relative expression of Kiss1 and Gpr54 genes in the pituitary gland in male Wistar rats. Methods: In general, 20 male Wistar rats weighing 200-250 g in 4 groups (5 in each group) received saline, NPY (2.3 nM), BIBP3226 (NPY receptor antagonist, 7.8 nM), and NPY+ BIBP3226. Then, they received the simultaneous injection of these molecules through the third ventricle of the brain. Finally, the relative mean expressions of Kiss1 and Gpr54 genes in the anterior pituitary were quantitatively analyzed by the real-time polymerase chain reaction. Results: The central injection of NPY increased the relative mean expressions of Kiss1 and Gpr54 genes in the pituitary gland compared to the control group although the injection of BIBP3226 eradicated these effects. However, the gene expression of Gpr54 in the rats receiving NPY coupled with BIBP3226 in hypophysis in comparison to the group receiving only NPY demonstrated a significant reduction (P&lt;0.05). Conclusion: Overall, the central injection of NPY stimulated the gene expression of Kiss1 and Gpr54 in the pituitary gland.

Risperidone stimulates food intake and induces body weight gain via the hypothalamic arcuate nucleus 5-HT2c receptor-NPY pathway.

AimsMany patients taking risperidone for the treatment of psychiatric disorders experience substantial body weight gain. Researchers have speculated that risperidone induces obesity by modulating central signals; however, the precise central mechanisms involved remain to be fully elucidated.MethodsTwenty‐four C57BL/6J mice were divided into four groups: a control group; a risperidone‐treated group; a lorcaserin‐treated group; and a combined risperidone + lorcaserin‐treated group. The mice were received the corresponding treatments for 4 weeks, and their brains were collected for in situ hybridization analysis. A subset of C57BL/6J mice was administrated with risperidone or placebo, and brains were collected 60 minutes post‐treatment for determination of c‐fos activity. In addition, brains of NPY‐GFP mice treated with or without risperidone were collected to perform colocalization of NPY and c‐fos, as well as NPY and 5‐HT2c receptor using immunohistochemistry.ResultsThere was significantly elevated c‐fos expression in the hypothalamic arcuate nucleus (Arc) of risperidone‐treated mice. More than 68% c‐fos‐positive neurons were NPY‐expressing neurons. Furthermore, in situ hybridization revealed that Arc NPY mRNA expression was significantly increased in the risperidone‐treated group compared with control group. Moreover, we identified that 95% 5‐HT2c receptors were colocalized with NPY positive neurons, and increased Arc NPY mRNA expression induced by risperidone was markedly reduced by cotreatment with lorcaserin, a specific 5‐HT2c receptor agonist.ConclusionOur findings provide critical insight into the mechanisms underlying antipsychotic‐induced obesity, which may assist the development of therapeutic strategies to address metabolic side effects of risperidone.