Neuropeptide Y Receptor Research Articles

Neuropeptide Y Signaling in the Lateral Hypothalamus Modulates Diet Component Selection and is Dysregulated in a Model of Diet-Induced Obesity

The preclinical multicomponent free-choice high-fat high-sucrose (fcHFHS) diet has strong validity to model diet-induced obesity (DIO) and associated maladaptive molecular changes in the central nervous system. fcHFHS-induced obese rats demonstrate increased sensitivity to intracerebroventricular infusion of the orexigenic Neuropeptide Y (NPY). The brain region-specific effects of NPY signaling on fcHFHS diet component selection are not completely understood. For example, fcHFHS-fed rats have increased intake of chow and fat following intracerebroventricular NPY infusion, whereas NPY administration in the nucleus accumbens, a key hub of the reward circuitry, specifically increases fat intake. Here, we investigated whether NPY infusion in the lateral hypothalamic area (LHA), which is crucially involved in the regulation of intake, regulates fcHFHS component selection, and if LHA NPY receptor subtypes 1 or 5 (NPYR1/5) are involved. Male Wistar rats were fed a chow or fcHFHS diet for at least seven days, and received intra-LHA vehicle or NPY infusions in a cross-over design. Diet component intake was measured two hours later. Separate experimental designs were used to test the efficacy of NPY1R- or NPY5R antagonism to prevent the orexigenic effects of intra-LHA NPY. Intra-LHA NPY increased caloric intake in chow- and fcHFHS-fed rats. This effect was mediated specifically by chow intake in fcHFHS-fed rats. The orexigenic effects of intra-LHA NPY were prevented by NPY1R and NPY5R antagonism in chow-fed rats, but only by NPY5R antagonism in fcHFHS-fed rats. Thus, NPY signaling has brain region-specific effects on fcHFHS component selection and LHA NPYR sensitivity is dysregulated during consumption of a fcHFHS diet.

Activation of NPY receptor subtype 1 by [D-His26]NPY is sufficient to prevent development of anxiety and depressive like effects in the single prolonged stress rodent model of PTSD

The neuropeptide Y (NPY) system plays an important role in mediating resilience to the harmful effect of stress in post-traumatic stress disorder (PTSD). It can mediate its effects via several G-protein coupled receptors: Y1R, Y2R, Y4R and Y5R. To investigate the role of individual NPY receptors in the resilience effects of NPY to traumatic stress, intranasal infusion of either Y1R agonists [D-His26]NPY, [Leu31Pro34]NPY, Y2R agonist NPY (3–36) or NPY were administered to male Sprague–Dawley rats immediately following the last stressor of the single prolonged stress (SPS) protocol, a widely used PTSD animal model. After 7 or 14 days, effects of the treatments were measured on the elevated plus maze (EPM) for anxiety, in forced swim test (FST) for development of depressive-like or re-experiencing behavior, in social interaction (SI) test for impaired social behavior, and acoustic startle response (ASR) for hyperarousal. [D-His26]NPY, but not [Leu31Pro34]NPY nor NPY (3–36) Y2R, was effective in preventing the SPS-elicited development of anxiety. Y1R, but not Y2R agonists prevented development of depressive- feature on FST, with [D-His26]NPY superior to NPY. The results demonstrate that [D-His26]NPY was sufficient to prevent development of anxiety, social impairment and depressive symptoms, and has promise as an early intervention therapy following traumatic stress.

Peptide YY (1-36) peptides from phylogenetically ancient fish targeting mammalian neuropeptide Y1 receptors demonstrate potent effects on pancreatic β-cell function, growth and survival.

To investigate the antidiabetic efficacy of enzymatically stable Peptide YY (PYY) peptides from phylogenetically ancient fish. N-terminally stabilized, PYY (1-36) sequences from Amia calva (bowfin), Oncorhynchus mykiss (trout), Petromyzon marinus (sea lamprey) and Scaphirhynchus albus (sturgeon), were synthesized, and both biological actions and antidiabetic therapeutic efficacy were assessed. All fish PYY (1-36) peptides were resistant to dipeptidyl peptidase-4 (DPP-4) degradation and inhibited glucose- and alanine-induced (P < 0.05 to P < 0.001) insulin secretion. In addition, PYY (1-36) peptides imparted significant (P < 0.05 to P < 0.001) β-cell proliferative and anti-apoptotic benefits. Proliferative effects were almost entirely absent in β cells with CRISPR-Cas9-induced knockout of Npyr1. In contrast to human PYY (1-36), the piscine-derived peptides lacked appetite-suppressive actions. Twice-daily administration of sea lamprey PYY (1-36), the superior bioactive peptide, for 21 days significantly (P < 0.05 to P < 0.001) decreased fluid intake, non-fasting glucose and glucagon in streptozotocin (STZ)-induced diabetic mice. In addition, glucose tolerance, insulin sensitivity, pancreatic insulin and glucagon content were significantly improved. Metabolic benefits were linked to positive changes in pancreatic islet morphology as a result of augmented (P < 0.001) proliferation and decreased apoptosis of β cells. Sturgeon PYY (1-36) exerted similar but less impressive effects in STZ mice. These observations reveal, for the first time, that PYY (1-36) peptide sequences from phylogenetically ancient fish replicate the pancreatic β-cell benefits of human PYY (1-36) and have clear potential for the treatment of type 2 diabetes.

295 Awardee Talk: Novel regulation of growth hormone by kisspeptin

Abstract Kisspeptin (KP) is critical regulator of reproductive function through it’s potent stimulation of gonadotropin releasing hormone (GnRH). In addition there has been inconclusive evidence to suggest intravenous KP can stimulate growth hormone (GH). Studies in 24 h fasted (but not fed) sheep determined that ICV injection of Kp-10 can increase plasma GH concentrations. This led to questions about the mechanism linking KP and GH. Since fasting is a critical requirement for the Kp effect on GH, studies were focused on factors that are linked to fasting within the hypothalamus and are known regulators of GH. Fasting causes a major upregulation of neuropeptide Y (NPY), a potent appetite regulator and in ruminants, a stimulator of GH. Pretreatment of BIBO 3304, an NPY receptor antagonist, blocked the effect of KP to increase GH and implicated NPY as a mediator of the KP effect. Indeed, KP injected ICV upregulated cFOS in NPY and GH Releasing Hormone (GHRH) cells in the arcuate nucleus and reduced cFOS in Somatostatin (SS) cells in the periventricular nucleus. Another factor, altered by fasting and capable of regulating GH, is Ghrelin. Both blockage of Ghrelin release and central blockade of Ghrelin receptors reduced or blocked release of GH after KP treatment. These experiments suggest an hypothesis that fasting upregulates central Ghrelin and NPY expression permitting the activation of NPY by KP. NPY in turn activates GHRH and inhibits SS to release GH.

Overexpression of neuropeptide Y decreases responsiveness to neuropeptide Y

Neuropeptide Y (NPY) is an endogenous neuropeptide that is abundantly expressed in the central nervous system. NPY is involved in various neurological processes and neuropsychiatric disorders, including fear learning and anxiety disorders. Reduced levels of NPY are reported in Post-Traumatic Stress Disorder (PTSD) patients, and NPY has been proposed as a potential therapeutic target for PTSD. It is therefore important to understand the effects of chronic enhancement of NPY on anxiety and fear learning. Previous studies have shown that acute elevation of NPY reduces anxiety, fear learning and locomotor activity. Models of chronic NPY overexpression have produced mixed results, possibly caused by ectopic NPY expression. NPY is expressed primarily by a subset of GABAergic interneurons, providing specific spatiotemporal release patterns. Administration of exogenous NPY throughout the brain, or overexpression in cells that do not normally release NPY, can have detrimental side effects, including memory impairment. In order to determine the effects of boosting NPY only in the cells that normally release it, we utilized a transgenic mouse line that overexpresses NPY only in NPY+ cells. We tested for effects on anxiety related behaviors in adolescent mice, an age with high incidence of anxiety disorders in humans. Surprisingly, we did not observe the expected reduction in anxiety-like behavior in NPY overexpression mice. There was no change in fear learning behavior, although there was a deficit in nest building. The effect of exogenous NPY on synaptic transmission in acute hippocampal slices was also diminished, indicating that the function of NPY receptors is impaired. Reduced NPY receptor function could contribute to the unexpected behavioral outcomes. We conclude that overexpression of NPY, even in cells that normally express it, can lead to reduced responsiveness of NPY receptors, potentially affecting the ability of NPY to function as a long-term therapeutic.

Effects of age on feeding response: Focus on the rostral C1 neuron and its glucoregulatory proteins.

Older people are likely to develop anorexia of aging. Rostral C1 (rC1) catecholaminergic neurons in rostral ventrolateral medulla (RVLM) are recently discovered its role in food intake control. It is well established that these neurons regulate cardiovascular function. This study aims to determine the effect of age on the function of rostral C1 (rC1) neurons in mediating feeding response. Male Sprague Dawley rats at 3-months (n = 22) and 24-months (n = 22) old were used and further divided into two subgroups; 1) treatment group with 2-deoxy-d-glucose (2DG) and 2) vehicle group. Feeding hormones such as cholecystokinin (CCK), ghrelin and leptin were analysed using enzyme-linked immunosorbent assay (ELISA). Rat brain was carefully dissected to obtain the brainstem RVLM region. Further analysis was carried out to determine the level of proteins and genes in RVLM that were associated with feeding pathway. Protein expression of tyrosine hydroxylase (TH), phosphorylated TH at Serine40 (pSer40TH), AMP-activated protein kinase (AMPK), phosphorylated AMPK (phospho AMPK) and neuropeptide Y Y5 receptor (NPY5R) were determined by western blot. Expression of TH, AMPK and NPY genes were determined by real-time PCR. This study showed that blood glucose level was elevated in young and old rats following 2DG administration. Plasma CCK-8 concentration was higher in the aged rats at basal and increased with 2DG administration in young rats, but the leptin and ghrelin showed no changes. Old rats showed higher TH and lower AMPK mRNA levels. Glucoprivation decreased AMPK mRNA level in young rats and decreased TH mRNA in old rats. Aged rC1 neurons showed higher NPY5R protein level. Following glucoprivation, rC1 neurons produced distinct molecular changes across age in which, in young rats, AMPK phosphorylation level was increased and in old rats, TH phosphorylation level was increased. These findings suggest that glucose-counterregulatory responses by rC1 neurons at least, contribute to the ability of young and old rats in coping glucoprivation. Age-induced molecular changes within rC1 neurons may attenuate the glucoprivic responses. This situation may explain the impairment of feeding response in the elderly.

Age related changes of neuropeptide Y-ergic system in the rat duodenum

Neuropeptide Y (NPY) is widely distributed in the autonomic nervous system and acts as a neurotransmitter and a trophic factor. However, there is no report concerning the expression of NPY and its receptors in the intestine during postnatal ontogenesis. In the current study, immunohistochemistry and western blot analysis was used to label NPY, Y1R, Y2R and Y5R receptors in the duodenum from rats of different ages (1-, 10-, 20-, 30-, 60-day-old and 2-year-old).The obtained data suggest age-dependent changes of NPY-mediated gut innervation. NPY-immunoreactive (IR) neurons were observed in the myenteric (MP) and submucous (SP) plexus from the moment of birth. In the MP, the percentage of NPY-IR neurons was low and varied from 4.1 ± 0.32 in 1-day-old to 2.9 ± 0.62 in 2-year-old rats. The proportion of NPY-IR myenteric neurons did not change significantly through the senescence (p > .05). In the SP, the proportion of NPY-IR neurons significantly increased in the first month of life from 56.3 ± 2.4% in 1-day-old to 78.1 ± 5.18% in 20-day-old and significantly decreased from 75.6 ± 4.62% in 30-day-old rats to 59.8 ± 4.24% in 2-year-old rats.The expression of NPY in the duodenum did not change significantly during the development by western blot analysis. The expression of Y1R and Y2R was low in newborns and upregulated in the first ten days of life. The expression of Y5R was maximal in newborn pups and significantly decreased in in the first 20 days.Thus, there are some fluctuation of the percentage of NPY-IR neurons accompanies changes in relation of different subtypes of NPY receptors in the small intestine during postnatal ontogenesis.

Contribution of Baroreflex Afferent Pathway to NPY-Mediated Regulation of Blood Pressure in Rats.

Neuropeptide Y (NPY), a metabolism-related cardiovascular factor, plays a crucial role in blood pressure (BP) regulation via peripheral and central pathways. The expression of NPY receptors (Y1R/Y2R) specific to baroreflex afferents impacts on the sexually dimorphic neural control of circulation. This study was designed to investigate the expression profiles of NPY receptors in the nodose ganglion (NG) and nucleus tractus solitary (NTS) under hypertensive conditions. To this end, rats with hypertension induced by NG-nitro-L-arginine methylester (L-NAME) or high fructose drinking (HFD), and spontaneously hypertensive rats (SHRs) were used to explore the effects/mechanisms of NPY on BP using functional, molecular, and electrophysiological approaches. The data showed that BP was elevated along with baroreceptor sensitivity dysfunction in model rats; Y1R was up- or down-regulated in the NG or NTS of male and female HFD/L-NAME groups, while Y2R was only down-regulated in the HFD groups as well as in the NG of the male L-NAME group. In SHRs, Y1R and Y2R were both down-regulated in the NTS, and not in the NG. In addition to NPY-mediated energy homeostasis, leptin-melanocortin activation may be essential for metabolic disturbance-related hypertension. We found that leptin and α-melanocyte stimulating hormone (α-MSH) receptors were aberrantly down-regulated in HFD rats. In addition, α-MSH concentrations were reduced and NPY concentrations were elevated in the serum and NTS at 60 and 90min after acute leptin infusion. Electrophysiological recordings showed that the decay time-constant and area under the curve of excitatory post-synaptic currents were decreased by Y1R activation in A-types, whereas, both were increased by Y2R activation in Ah- or C-types. These results demonstrate that sex- and afferent-specific NPY receptor expression in the baroreflex afferent pathway is likely to be a novel target for the clinical management of metabolism-related and essential hypertension.

Neuropeptide Y and cannabinoids interaction in the amygdala after exposure to shock and reminders model of PTSD

Modulation of cannabinoid and neuropeptide Y (NPY) receptors may offer therapeutic benefits for post-traumatic stress disorder (PTSD). In this study, we aimed to investigate the functional interaction between these systems in the basolateral amygdala (BLA) in a rat model of PTSD.Rats were exposed to the shock and reminders model of PTSD and tested for hyper arousal/PTSD- and depression-like behaviors 3 weeks later. Immediately after shock exposure rats were microinjected into the BLA with URB597, a selective inhibitor of fatty acid amide hydrolase (FAAH) that increases the levels of the endocannabinoid anandamide or with the NPY1 receptor agonist Leu31,Pro34-NPY (Leu).Intra-BLA URB597 prevented the shock/reminders-induced PTSD- behaviors (extinction, startle) and depression-behaviors (despair, social impairments). These preventing effects of URB597 on PTSD- and depression-like behaviors were shown to be mostly mediated by cannabinoid CB1 and NPY1 receptors, as they were blocked when URB597 was co-administered with a low dose of a CB1 or NPY1 receptor antagonist. Similarly, intra-BLA Leu prevented development of all the behaviors. Interestingly, a CB1 antagonist prevented the effects of Leu on despair and social behavior, but not the effects on extinction and startle. Moreover, exposure to shock and reminders upregulated CB1 and NPY1 receptors in the BLA and infralimbic prefrontal cortex and this upregulation was restored to normal with intra-BLA URB597 or Leu.The findings suggest that the functional interaction between the eCB and NPY1 systems is complex and provide a rationale for exploring novel therapeutic strategies that target the cannabinoid and NPY systems for stress-related diseases.

Physical exercise inhibits atherosclerosis development by regulating the expression of neuropeptide Y in apolipoprotein E-deficient mice

AimsPopulation-based studies have shown that exercise has anti-atherosclerotic effects, but the mechanisms underlying this cardiac protection are poorly understood. The aim of this study was to investigate if the anti-atherosclerotic effects of exercise are associated with changes in neuropeptide Y (NPY) expression in apolipoprotein E-deficient (ApoE−/-) mice. Main methodsThirty-one male ApoE−/- mice were randomly divided into regular exercise (5 days/week), occasional exercise (1–2 days/week), and sedentary groups. After 8 weeks, atherosclerotic burden and plaque stability were measured by histological and morphological analysis. Quantitative real-time PCR and immunohistochemistry were used to measure the expression of NPY and its receptors in the aorta. Key findingsEight weeks of occasional exercise was equally effective as regular exercise at preventing atherosclerotic plaque formation and enhancing atherosclerotic plaque stability. This was shown by increased plaque collagen and smooth muscle cell content and decreased plaque lipid and macrophage content. The expression of NPY and its receptors in the vasculature was decreased in the regular exercise and occasional exercise groups, and this expression was significantly correlated with the progress of atherosclerosis. Moreover, exercise may reduce the activity of macrophages by down-regulating the expression of NPY Y1 receptors, thereby reducing the release of inflammatory cytokines. SignificanceThese results suggest that exercise training can attenuate plaque burden and enhance atherosclerotic plaque stability. The anti-atherosclerotic effect of exercise appears to be, at least in part, dependent on down-regulation of the expression of NPY and its receptors (especially Y1 receptors) in the aorta.

Pharmacological and functional similarities of the human neuropeptide Y system in C. elegans challenges phylogenetic views on the FLP/NPR system

BackgroundThe neuropeptide Y system affects various processes, among others food intake, and is frequently discussed in the context of targeting obesity. Studies in model organisms are indispensable to enable molecular studies in a physiological context. Although the NPY system is evolutionarily conserved in all bilaterians, in the widely used model Caenorhabditis elegans there is controversy on the existence of NPY orthologous molecules. While the FMRFamide-like peptide (FLP)/Neuropeptide receptor-Resemblance (NPR) system in the nematode was initially suggested to be orthologous to the mammalian NPY system, later global phylogenetic studies indicate that FLP/NPR is protostome-specific.MethodsWe performed a comprehensive pharmacological study of the FLP/NPR system in transfected cells in vitro, and tested for functional substitution in C. elegans knockout strains. Further, we phenotypically compared different flp loss-of-function strains. Differences between groups were compared by ANOVA and post-hoc testing (Dunnett, Bonferroni).ResultsOur pharmacological analysis of the FLP/NPR system including formerly functionally uncharacterized NPY-like peptides from C. elegans demonstrates that G protein-coupling and ligand requirements for receptor activation are similar to the human NPY system. In vitro and in vivo analyses show cross-reactivity of NPY with the FLP/NPR system manifesting in the ability of the human GPCRs to functionally substitute FLP/NPR signaling in vivo. The high pharmacological/functional similarities enabled us to identify C. elegans FLP-14 as a key molecule in avoidance behavior.ConclusionsOur data demonstrate the pharmacological and functional similarities of human NPY and C. elegans NPR systems. This adds a novel perspective to current phylogenetic reconstructions of the neuropeptide Y system. NPY and NPR receptors are pharmacologically so similar that the human receptors can functionally compensate for the C. elegans ones, suggesting orthologous relationships. This is also underlined by the presence of NPY-like peptides and parallels in peptide requirements for receptor activation. Further, the results presented here highlight the potential of this knowledge for physiological as well as molecular studies on neuropeptide GPCRs such as the NPY system in the future.

QRFP receptor (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

The human gene encoding the QRFP receptor (nomenclature as agreed by the NC-IUPHAR Subcommittee on the QRFP receptor [16]; QRFPR, formerly known as the Peptide P518 receptor), previously designated as an orphan GPCR receptor was identified in 2001 by Lee et al. from a hypothalamus cDNA library [15]. However, the reported cDNA (AF411117) is a chimera with bases 1-127 derived from chromosome 1 and bases 155-1368 derived from chromosome 4. When corrected, QRFPR (also referred to as SP9155 or AQ27) encodes a 431 amino acid protein that shares sequence similarities in the transmembrane spanning regions with other peptide receptors. These include neuropeptide FF2 (38%), neuropeptide Y2 (37%) and galanin Gal1 (35%) receptors.

Neuropeptide Y receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

Neuropeptide Y (NPY) receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Neuropeptide Y Receptors [156]) are activated by the endogenous peptides neuropeptide Y, neuropeptide Y-(3-36), peptide YY, PYY-(3-36) and pancreatic polypeptide (PP). The receptor originally identified as the Y3 receptor has been identified as the CXCR4 chemokine recepter (originally named LESTR, [137]). The y6 receptor is a functional gene product in mouse, absent in rat, but contains a frame-shift mutation in primates producing a truncated non-functional gene [83]. Many of the agonists exhibit differing degrees of selectivity dependent on the species examined. For example, the potency of PP is greater at the rat Y4 receptor than at the human receptor [61]. In addition, many agonists lack selectivity for individual subtypes, but can exhibit comparable potency against pairs of NPY receptor subtypes, or have not been examined for activity at all subtypes. [125I]-PYY or [125I]-NPY can be used to label Y1, Y2, Y5 and y6 subtypes non-selectively, while [125I][cPP(1-7), NPY(19-23), Ala31, Aib32, Gln34]hPP may be used to label Y5 receptors preferentially (note that cPP denotes chicken peptide sequence and hPP is the human sequence).

Discovery of small molecule agonists targeting neuropeptide Y4 receptor using homology modeling and virtual screening

Neuropeptide Y4 receptor has the most significant effect on body weight and fat mass in its physiological functions, and the activation of Y4 receptor has explicit role on losing weight. The Y4 receptor has been successfully applied in the development of anti-obesity agent, thus representing a potential therapeutic target for obesity treatment. Here, we reported the first discovery of small molecule agonists targeting Y4 receptor: three Y4 receptor models with active and inactive conformations were built, each model was submitted following structure-based virtual screening, and finally six hits were identified as Y4 receptor agonists. These results confirm the reliability of the constructed Y4 receptor models and the proposed computational strategy for investigating novel Y4 receptor agonists. These new small molecule Y4 receptor agonists will contribute to the further development of Y4 agonists as potential therapeutics and functional probes.

Pharmacological characterization, cellular localization and expression profile of NPY receptor subtypes Y2 and Y7 in large yellow croaker, Larimichthys crocea.

Neuropeptide Y (NPY) receptors are suggested to mediate the multi-physiological functions of NPY family peptides, such as food intake, in teleost fish. However, the structure and signaling of fish NPY receptors are yet to be fully elucidated. In this study, we report the cloning and characterization of two neuropeptide Y receptor subtypes, Y2 (NPY2R) and Y7 (NPY7R), in yellow croaker Larimichthys crocea (L. crocea) (LcNPY2R, LcNPY7R). The gene structure, pharmacological characterization, cell location, and tissue expression of these two receptors were explored. The phylogenetic results showed that LcNPY2R and LcNPY7R had typical G protein-coupled receptor profiles, associated with the Y2 subfamily, with coding sequences that are highly conserved in vertebrates. The expression of both LcNPY2R and LcNPY7R could be activated by LcNPY in HEK293 cells. However, truncated LcNPY18-36 was only able to activate LcNPY2R at the same level as full length LcNPY. Expression analysis revealed that LcNPY2R mRNA was predominantly expressed in the intestine and liver, whereas LcNPY7R was expressed in the stomach, which indicated that both receptors were related to the digestive system. Overall, our data establishes a molecular basis to determine the actions of LcNPY2R and LcNPY7R, which could be used to elucidate the conserved roles of these receptor-ligand pairs in vertebrates.

Abstract 016: Sex-Specific Effects of Neuropeptide Y2 Receptor (y2) Deletion in Adipose Tissue From Mice Exposed to Early Life Stress

Neuropeptide Y (NPY) plays a critical role in the regulation of energy homeostasis acting in the central nervous system as an orexigenic agent. Peripherally, NPY is co-released by catecholaminergic neurons and stimulates adipocyte precursor proliferation, differentiation, via NPY receptor 2 (Y2), and inhibit lipolysis, via the cAMP/PKA pathway. We have shown that female mice exposed to a model of early life stress, maternal separation and early weaning (MSEW), display greater increases in fat mass in response to high fat diet (HF). Thus, we hypothesized that Y2 deletion in adipose tissue could prevent fat expansion in female MSEW mice. MSEW was performed by separating pups from the dam during postnatal days 2 to 16, and weaned early on day 17. Control (C) mice remained undisturbed and were weaned on day 21. Genotyping was completed to determine WT (Y2 fl/fl) and Y2 KO (Y2 fl/fl) littermates. All groups were placed on a HF (60% kcal from fat) for 18 weeks. Following, mice were subjected to 6-weeks of chronic restraint stress (1 hr/day) combined with high fat/high sucrose diet (RS+HFS). No differences in fat mass were found between male WT MSEW and C mice (37.5±2.0 vs. 41.9±2.3 % body fat, respectively), although Y2 KO reduced fat mass in both groups (23.2±2.3 vs. 38.1±2.9 % body fat, p MSEW=0.084, p genotype=0.011, p interaction=0.401). Conversely, female WT MSEW mice displayed increased fat mass compared to C (26.4±2.6 vs. 19.1±2.6 % body fat), and Y2 KO further increased fat deposition in MSEW female mice compared to C (36.1±4.3 vs. 15.8±1.2 % body fat, p MSEW=0.0001, p genotype=0.047, p interaction=0.007). In addition, female WT MSEW mice displayed reduced free fatty acid release in response to an in vivo lipolysis test in compared to C (101±21 vs. 167±12 uM/ml, p=0.066). After RS+HFS, MSEW increased fat mass in male WT mice more than in female WT mice, while Y2 KO attenuated this effect in both sexes. These data suggests that Y2 in adipose tissue may contribute to reduced lipolysis in HF-fed female mice exposed to MSEW. However, Y2-mediated effects of chronic stress on fat expansion in adult life are greater in male than in female MSEW mice. Overall, our data shows that there is possibly a sex-specific imbalance between adipogenesis and lipolysis in response to different stressors.

Role of Paraventricular Nucleus in Regulation of Feeding Behaviour and the Design of Intranuclear Neuronal Pathway Communications

Food consumption and body weight regulations are done in the hypothalamus. Indeed, hypothalamus is the brain’s main area in controlling food intake. Hypothalamus controls food intake via special nuclei such as: ARC, PVN, DMH, VMH and LHA. PVN are second order neurons. This nucleus received multiple inputs from different areas of the brain via specific and non-specific receptors. NPYR and α2-adrenoceptors are orexigenic receptors, but Melanocortin receptors are anorexigenic receptors. PVN integrated inputs from multiple areas, and then transmitted various outputs for central regulation of food intake. To identify neural pathways and the role of neurotransmitters on central control of food intake in PVN, multiple researches have been done via injection of various neurotransmitters on the laboratory animals. Leptin applies its effect on regulation of feeding behaviours through arcuate nucleus-paraventricular nucleus axis and MC4R receptor. Also, Insulin is a hypophagic neurotransmitter, and its hypophagic effect applied in PVN via NPY1 and MC4R receptors. Ghrelin has a biphasic effect on food intake in birds and mammals. In birds, ghrelin inhibits food intake, but in mammals stimulated food intake. In birds, ghrelin via 5HT2A receptor on CRF neurons located on PVN reduced food intake. In mammals via GHSR (ghrelin receptor) and NPY1 receptors increased food intake. Somatostatin acts in the brain as an inhibitory and hyperphagic neurotransmitter. Hyperphagic effect of Somatostatin on PVN exert via SST2, OX1 and NPY1 receptors respectively. Therefore, PVN has an important effect on central regulation of food intake via different neurotransmitters and pathway. The role of PVN in central regulation of food intake. ARC arcuate nucleus, PVN paraventricular nucleus, LHA lateral hypothalamus area, CRF Corticotropin-realising factor, POMC pro-opiomelanocortin, CART Cocaine and amphetamine-regulated transcript, NPY/AgRP neuropeptide Y/agouti-related protein, Y1R NPY1 receptor, GHSR growth hormone secretagogues receptor, LEPR Leptin receptor, INSR Insulin receptor, OX1R orexin receptor, MC4R Melanocortin4 receptor, SST2R Somatostatin2 receptor.

Sex-Dependent Gene Expression in Infants with Neonatal Opioid Withdrawal Syndrome

To evaluate salivary biomarkers that elucidate the molecular mechanisms by which in utero opioid exposure exerts sex-specific effects on select hypothalamic and reward genes driving hyperphagia, a hallmark symptom of infants suffering from neonatal opioid withdrawal syndrome (NOWS). We prospectively collected saliva from 50 newborns born at ≥34weeks of gestational age with prenatal opioid exposure and 50 sex- and gestational age-matched infants without exposure. Saliva underwent transcriptomic analysis for 4 select genes involved in homeostatic and hedonic feeding regulation (neuropeptide Y2 receptor [NPY2R], proopiomelanocortin [POMC], leptin receptor [LEPR], dopamine type 2 receptor [DRD2]). Normalized gene expression data were stratified based on sex and correlated with feeding volume on day of life 7 and length of stay in infants with NOWS requiring pharmacotherapy. Expression of DRD2, a hedonistic/reward regulator, was significantly higher in male newborns compared with female newborns with NOWS (Δ threshold cycle 10.8±3.8 vs 13.9±3.7, P=.01). In NOWS requiring pharmacotherapy expression of leptin receptor, an appetite suppressor, was higher in male subjects than female subjects (Δ threshold cycle 8.4±2.5 vs 12.4±5.1, P=.05), DRD2 expression significantly correlated with intake volume on day of life 7 (r=0.58, P=.02), and expression of NPY2R, an appetite regulator, negatively correlated with length of stay (r=-0.24, P=.05). Prenatal opioid exposure exerts sex-dependent effects on hypothalamic feeding regulatory genes with clinical correlations. Neonatal salivary gene expression analyses may predict hyperphagia, severity of withdrawal state, and length of stay in infants with NOWS.

Hypothalamic mechanisms associated with neuropeptide K-induced anorexia in Japanese quail (Coturnix japonica)

Central administration of neuropeptide K (NPK), a 36-amino acid peptide, is associated with anorexigenic effects in rodents and chickens. The mechanisms underlying the potent anorexigenic effects of NPK are still poorly understood. Thus, the aim of the present study was to identify the hypothalamic nuclei and neuropeptides that mediate anorexic effects of NPK in 7 day-old Japanese quail (Coturnix japonica). After a 6 h fast, intracerebroventricular (ICV) injection of NPK decreased food and water intake for 180 min post-injection. Quail injected with NPK had more c-Fos immunoreactive cells in the arcuate nucleus (ARC), lateral hypothalamus, and paraventricular nucleus (PVN) compared to the birds that were injected with the vehicle. In the ARC of NPK-injected quail, there was decreased neuropeptide Y (NPY), NPY receptor sub-type 1, and agouti-related peptide mRNA, and increased CART, POMC, and neurokinin receptor 1 mRNA. NPK-injected quail expressed greater amounts of corticotropin-releasing factor (CRF), CRF receptor sub-type 2, melanocortin receptors 3 and 4, and urocortin 3 mRNA in the PVN. In conclusion, results provide insights into understanding NPK-induced changes in hypothalamic physiology and feeding behavior, and suggest that the anorexigenic effects of NPK involve the ARC and PVN, with increased CRF and melanocortin and reduced NPY signaling.

NPY and NPY receptors in the central control of feeding and interactions with CART and MC4R in Siberian sturgeon

Neuropeptide Y (NPY) is the most powerful central neuropeptide implicated in feeding regulation via its receptors. Understanding the role of NPY system is critical to elucidate animal feeding regulation. Unlike mammal, the possible mechanisms of NPY system in the food intake of teleost fish are mostly unknown. Therefore, we investigated the regulatory mechanism of NPY and NPY receptors in Siberian sturgeon. In this study, we cloned the cDNA encoding NPY, and assessed the effects of different energy status on npy mRNAs abundance. The expression of npy was decreased in the brain after feeding 1 and 3 h. Besides, the expression of npy was increased after fasting within 15 days, while exhibiting significant decrease after refeeding. In order to further characterize the role of NPY receptor in fish, we performed acute intraperitoneal (i.p.) injection of NPY Y1 and Y2 receptor agonists, which is [Leu 31, Pro 34] NPY and NPY13-36 respectively. The results showed that the food intake of Siberian sturgeon was increased within 30 mins after injection of both Y1 and Y2 receptor agonist. To explore the relationship between NPY, NPY receptors and another appetite peptides, we examined the level of npy, cocaine- and amphetamine-regulated transcript (cart) and melanocortin-4 receptor (mc4r) by injected Y1 and Y2 receptor agonist. The results suggested that cart expression was regulated by NPY which acts on Y1 receptor or Y2 receptor. While mc4r expression just was mediated by NPY and Y1 receptor.