Y1 Receptor Research Articles

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.

Usefulness of a Kampo Medicine on Stress‐Induced Delayed Gastric Emptying in Mice

Anxiety and depression often occur with gastrointestinal symptoms. Although the Japanese traditional medicine (Kampo medicine) bukuryoingohangekobokuto (BGH) is approved for treating anxiety, neurotic gastritis, and heartburn, its effect on gastrointestinal motility remains poorly known. This study aimed to examine the effect of BGH on delayed gastric emptying in stress model mice and clarified its action mechanism. Seven-week-old C57BL/6 male mice were acclimated for a week and fasted overnight. Stress hormone, corticotropin-releasing factor (CRF), was intracerebroventricularly injected to mice, and solid nutrient meal (ground chow and distilled water) was orally administered 1 hour after. Gastric contents were collected to evaluate gastric emptying rates by measuring its dry weight. Injection of CRF (0.3 or 1.0 μg/mouse) significantly delayed the 2-hour gastric emptying in mice. BGH (1.0 g/kg), which was administered 30 minutes before the CRF injection, significantly ameliorated the delayed gastric emptying induced by CRF (0.3 μg/mouse). BGH (0.5, 1.0 g/kg) significantly enhanced the 1-hour gastric emptying and slightly increased the 2-hour gastric emptying in mice without CRF injection. In vitro functional assays showed that components of BGH antagonized or inhibited CRF type-2, dopamine D2/D3, neuropeptide Y Y2 receptors, or acetylcholinesterase. In conclusion, the components of BGH may exert synergistic effects on improving gastric emptying via various targets. BGH is considered to be potentially useful for treating gastrointestinal dysmotility with psychological symptoms.

Active targeting nano-scale bubbles enhanced ultrasound cavitation chemotherapy in Y1 receptor-overexpressed breast cancer.

Ultrasound cavitation therapy has attracted much attention in recent years because the cavitation of microbubbles can be leveraged to boost the infiltration of chemotherapeutic drugs into cancer tissues. For breast cancer therapy, most of the previously reported microbubbles lack specific targeting capacity and permeability. In this study, we have successfully fabricated Y1 receptor ligand (NPY)-modified bubbles, and examined their therapeutic efficacies as size-dependent functions with or without NPY targeting. To achieve this, four types of micro-scale bubbles (MBs or MBs-NPY) and nano-scale bubbles (NBs or NBs-NPY) were comprehensively evaluated. In vivo results indicated that the NBs-NPY group with doxorubicin (DOX) under ultrasound irradiation showed a high tumor suppression effect and a prolonged survival time. Furthermore, the NBs-NPY with DOX group exhibited minimal damage to mouse vital organs, which points to the considerable tolerance of the proposed nanosystem for efficacious breast cancer therapy. In summary, these findings suggest that the developed NPY-targeted NBs could have a broad application prospect in ultrasound cavitation chemotherapy of Y1 receptor-overexpressed breast cancer.

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.

Neuropeptide Y1 Receptor Antagonist Alters Gut Microbiota and Alleviates the Ovariectomy-Induced Osteoporosis in Rats.

A plethora of evidence has suggested that gut microbiota is involved in the occurrence and development of postmenopausal osteoporosis (PMO). It has been suggested that neuropeptide Y (NPY) modulates the bone metabolism through Y1 receptor (Y1R), and might be associated with gut microbiota. The present study aims to evaluate the anti-osteoporotic effects of Y1R antagonist and to investigate the potential mechanism by which Y1R antagonist regulates gut microbiota. In this study, eighteen female rats were randomly divided into three groups: the sham surgery (SHAM) group, the ovariectomized (OVX) group, and OVX+BIBO3304 group. After 6weeks following surgery, Y1R antagonist BIBO3304 was administered to the rats in OVX+BIBO3304 group for 7days. The bone microstructure and serum biochemical parameters were measured at 12weeks after operation. The differences in the gut microbiota were analyzed by 16S rDNA gene sequencing. Heat-map and Spearman's correlation analyses were constructed to investigate the correlations between microbiota and bone metabolism-related parameters. The results indicated that OVX+BIBO3304 group showed significantly higher BMD, BV/TV, Tb.Th, Tb.N, Conn.D, and serum Ca2+ level than those in OVX group. Additionally, Y1R antagonist changed the gut microbiota composition with lower Firmicutes/Bacteroidetes ratio and higher proportions of some probiotics, including Lactobacillus. The correlation analysis showed that the changes of gut microbiota were closely associated with bone microstructure and serum Ca2+ levels. Our results suggested that Y1R antagonist played an anti-osteoporotic effect and regulated gut microbiota in OVX rats, indicating the potential to utilize Y1R antagonist as a novel treatment for PMO.

The cardiac sympathetic co-transmitter neuropeptide Y is pro-arrhythmic following ST-elevation myocardial infarction despite beta-blockade.

AimsST-elevation myocardial infarction is associated with high levels of cardiac sympathetic drive and release of the co-transmitter neuropeptide Y (NPY). We hypothesized that despite beta-blockade, NPY promotes arrhythmogenesis via ventricular myocyte receptors.Methods and resultsIn 78 patients treated with primary percutaneous coronary intervention, sustained ventricular tachycardia (VT) or fibrillation (VF) occurred in 6 (7.7%) within 48 h. These patients had significantly (P < 0.05) higher venous NPY levels despite the absence of classical risk factors including late presentation, larger infarct size, and beta-blocker usage. Receiver operating curve identified an NPY threshold of 27.3 pg/mL with a sensitivity of 0.83 and a specificity of 0.71. RT-qPCR demonstrated the presence of NPY mRNA in both human and rat stellate ganglia. In the isolated Langendorff perfused rat heart, prolonged (10 Hz, 2 min) stimulation of the stellate ganglia caused significant NPY release. Despite maximal beta-blockade with metoprolol (10 μmol/L), optical mapping of ventricular voltage and calcium (using RH237 and Rhod2) demonstrated an increase in magnitude and shortening in duration of the calcium transient and a significant lowering of ventricular fibrillation threshold. These effects were prevented by the Y1 receptor antagonist BIBO3304 (1 μmol/L). Neuropeptide Y (250 nmol/L) significantly increased the incidence of VT/VF (60% vs. 10%) during experimental ST-elevation ischaemia and reperfusion compared to control, and this could also be prevented by BIBO3304.ConclusionsThe co-transmitter NPY is released during sympathetic stimulation and acts as a novel arrhythmic trigger. Drugs inhibiting the Y1 receptor work synergistically with beta-blockade as a new anti-arrhythmic therapy.

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.

Inhibition of epileptiform activity by neuropeptide Y in brain tissue from drug-resistant temporal lobe epilepsy patients

In epilepsy patients, drug-resistant seizures often originate in one of the temporal lobes. In selected cases, when certain requirements are met, this area is surgically resected for therapeutic reasons. We kept the resected tissue slices alive in vitro for 48 h to create a platform for testing a novel treatment strategy based on neuropeptide Y (NPY) against drug-resistant epilepsy. We demonstrate that NPY exerts a significant inhibitory effect on epileptiform activity, recorded with whole-cell patch-clamp, in human hippocampal dentate gyrus. Application of NPY reduced overall number of paroxysmal depolarising shifts and action potentials. This effect was mediated by Y2 receptors, since application of selective Y2-receptor antagonist blocked the effect of NPY. This proof-of-concept finding is an important translational milestone for validating NPY-based gene therapy for targeting focal drug-resistant epilepsies, and increasing the prospects for positive outcome in potential clinical trials.

The Neuropeptide Y Y2 Receptor Is Coexpressed with Nppb in Primary Afferent Neurons and Y2 Activation Reduces Histaminergic and IL-31-Induced Itch.

Itch stimuli are detected by specialized primary afferents that convey the signal to the spinal cord, but how itch transmission is regulated is still not completely known. Here, we investigated the roles of the neuropeptide Y (NPY)/Y2 receptor system on scratch behavior. The inhibitory Y2 receptor is expressed on mouse primary afferents, and intrathecal administration of the Y2 agonist peptide YY (PYY)3-36 reduced scratch episode frequency and duration induced by compound 48/80, an effect that could be reversed by intrathecal preadministration of the Y2 antagonist BIIE0246. Also, scratch episode duration induced by histamine could be reduced by PYY3-36 In contrast, scratch behavior induced by α-methyl-5HT, protease-activated receptor-2-activating peptide SLIGRL, chloroquine, topical dust mite extract, or mechanical itch induced by von Frey filaments was unaffected by stimulation of Y2 Primary afferent neurons expressing the Npy2r gene were found to coexpress itch-associated markers such as natriuretic peptide precursor b, oncostatin M receptor, and interleukin (IL) 31 receptor A. Accordingly, intrathecal PYY3-36 reduced the scratch behavior induced by IL-31. Our findings imply that the NPY/Y2 system reduces histaminergic and IL-31-associated itch through presynaptic inhibition of a subpopulation of itch-associated primary afferents. SIGNIFICANCE STATEMENT: The spinal neuropeptide Y system dampens scratching behavior induced by histaminergic compounds and interleukin 31, a cytokine involved in atopic dermatitis, through interactions with the Y2 receptor. The Y2 receptor is expressed by primary afferent neurons that are rich in itch-associated neurotransmitters and receptors such as somatostatin, natriuretic peptide precursor b, and interleukin 31 receptors.

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.

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.

Selective Neuropeptide Y Conjugates with Maximized Carborane Loading as Promising Boron Delivery Agents for Boron Neutron Capture Therapy.

G-protein-coupled receptors like the human Y1 receptor (hY1R) are promising targets in cancer therapy due to their high overexpression on cancer cells and their ability to internalize together with the bound ligand. This mechanism was exploited to shuttle boron atoms into cancer cells for the application of boron neutron capture therapy (BNCT), a noninvasive approach to eliminate cancer cells. A maximized number of carboranes was introduced to the hY1R-preferring ligand [F7,P34]-NPY by solid phase peptide synthesis. Branched conjugates loaded with up to 80 boron atoms per peptide molecule exhibited a maintained receptor activation profile, and the selective uptake into hY1R-expressing cells was demonstrated by internalization studies. In order to ensure appropriate solubility in aqueous solution, we proved the need for eight hydroxyl groups per carborane. Thus, we suggest the utilization of bis-deoxygalactosyl-carborane building blocks in solid phase peptide synthesis to produce selective boron delivery agents for BNCT.

Neuropeptide Y system mRNA expression changes in the hippocampus of a type I diabetes rat model

BackgroundNeuropeptide Y (NPY) plays a crucial role in many neurobiological functions, such as cognition and memory. Cognitive and memory impairment have been described in diabetic patients. The metabolism of NPY is determined by the activity of proteases, primarily dipeptidyl-peptidase-IV (DPP-IV). Therefore, DPP-IV inhibitors, such as sitagliptin, may modulate the function of NPY. In this study, we investigated the effect of type 1 diabetes and sitagliptin treatment on the regulation of the mRNA encoding for NPY and its receptors (Y1, Y2, and Y5 receptors) in the hippocampus. MethodsType 1 diabetes was induced in male Wistar rats by i.p. injection of streptozotocin. Starting two weeks after diabetes onset, animals were treated orally with sitagliptin (5mg/kg, daily) for two weeks. The mRNA expression of Npy and its receptors (Npy1r, Npy2r, and Npy5r) in the hippocampus was evaluated using in situ hybridization with 33P-labeled oligonucleotides. ResultsThe mRNA expression of Npy, Npy1r and Npy5r was higher in the dentate gyrus, whereas Npy2r highest level was observed in the CA3 subregion. The mRNA expression of Npy, Npy1r and Npy5r in dentate gyrus, CA1 and CA3 was not affected by diabetes and/or by sitagliptin treatment. Type 1 diabetes increased the mRNA expression of Npy2r in the CA3 subregion, which was prevented by sitagliptin treatment. ConclusionsOur results show that type 1 diabetes, at early stages, induces mild changes in the NPY system in the hippocampus that were counteracted by sitagliptin treatment.

Disease Modification by Combinatorial Single Vector Gene Therapy: A Preclinical Translational Study in Epilepsy

Gene therapy has been suggested as a plausible novel approach to achieve seizure control in patients with focal epilepsy that do not adequately respond to pharmacological treatment. We investigated the seizure-suppressant potential of combinatorial neuropeptide Y and Y2 receptor single vector gene therapy based on adeno-associated virus serotype 1 (AAV1) in rats. First, a dose-response study in the systemic kainate-induced acute seizure model was performed, whereby the 1012 genomic particles (gp)/mL titer of the vector was selected as an optimal concentration. Second, an efficacy study was performed in the intrahippocampal kainate chronic model of spontaneous recurrent seizures (SRSs), designed to reflect a likely clinical scenario, with magnetic resonance image (MRI)-guided focal unilateral administration of the vector in the hippocampus during the chronic stage of the disease. The efficacy study demonstrated a favorable outcome of the gene therapy, with a 31% responder rate (more than 50% reduction in SRS frequency) and 13% seizure-freedom rate, whereas no such effects were observed in the control animals. The inter-SRS and SRS cluster intervals were also significantly prolonged in the treated group compared to controls. In addition, the SRS duration was significantly reduced in the treated group but not in the controls. This study establishes the SRS-suppressant ability of the single vector combinatorial neuropeptide Y/Y2 receptor gene therapy in a clinically relevant chronic model of epilepsy.

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).

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.

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.

18F-labelled triazolyl-linked argininamides targeting the neuropeptide Y Y1R for PET imaging of mammary carcinoma

Neuropeptide Y Y1 receptors (Y1R) have been found to be overexpressed in a number of different tumours, such as breast, ovarian or renal cell cancer. In mammary carcinoma the high Y1R density together with its high incidence of 85% in primary human breast cancers and 100% in breast cancer derived lymph node metastases attracted special attention. Therefore, the aim of this study was the development of radioligands for Y1R imaging by positron emission tomography (PET) with a special emphasis on imaging agents with reduced lipophilicity to provide a PET ligand with improved biodistribution in comparison with previously published tracers targeting the Y1R. Three new radioligands based on BIBP3226, bearing an 18F-fluoroethoxy linker (12), an 18F-PEG-linker (13) or an 18F-fluoroglycosyl moiety (11) were radiosynthesised in high radioactivity yields. The new radioligands displayed Y1R affinities of 2.8 nM (12), 29 nM (13) and 208 nM (11) and were characterised in vitro regarding binding to human breast cancer MCF-7-Y1 cells and slices of tumour xenografts. In vivo, small animal PET studies were conducted in nude mice bearing MCF-7-Y1 tumours. The binding to tumours, solid tumour slices and tumour cells correlated well with the Y1R affinities. Although 12 and 13 showed displaceable and specific binding to Y1R in vitro and in vivo, the radioligands still need to be optimised to achieve higher tumour-to-background ratios for Y1R imaging by PET. Yet the present study is another step towards an optimized PET radioligand for imaging of Y1R in vivo.

Neuropeptide Y increases differentiation of human olfactory receptor neurons through the Y1 receptor

Olfactory dysfunction significantly impedes the life quality of patients. Neuropeptide Y (NPY) is not only a neurotrophic factor in the rodent olfactory system but also an orexigenic peptide that regulates feeding behavior. NPY increases the olfactory receptor neurons (ORNs) responsivity during starvation; however, whether NPY can promote differentiation of human ORNs remains unexplored. This study investigates the effect of NPY on the differentiation of human olfactory neuroepithelial cells in vitro. Human olfactory neuroepithelium explants were cultured on tissue culture polystyrene dishes for 21 days. Then, cells were cultured with or without NPY at the concentration of 0.5 ng/mℓ for 7 days. The effects of treatment were assessed by phase contrast microscopy, immunocytochemistry and western blot analysis. The further mechanism was evaluated with NPY Y1 receptor-selected antagonist BIBP3226. NPY-treated olfactory neuroepithelial cells exhibited thin bipolar shape, low circularity, low spread area, and long processes. The expression levels of Ascl1, βIII tubulin, GAP43 and OMP were significantly higher in NPY-treated cells than in controls (p < 0.05). NPY-treated olfactory neuroepithelial cells expressed more components of signal transduction apparatuses, Golf and ADCY3, than those without NPY treatment. Western blot analysis also further confirmed these findings (p < 0.05). Additionally, the expression levels of Ascl1, βIII2 tubulin, GAP43, OMP, ADCY3, and Golf in BIBP3226 + NPY and controls were comparable (p > 0.05). NPY not only increases expressions of protein markers of human olfactory neuronal progenitor cells, but also promotes differentiation of ORN and enhances formation of components of olfactory-specific signal transduction pathway through Y1 receptors.

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.