Neuropeptide Y receptor subtypes, Y1 and Y2

Structural basis of neuropeptide Y signaling through Y1 and Y2 receptors

Neuropeptide Y (NPY), a 36-amino-acid peptide, functions as a neurotransmitter in both the central and peripheral nervous systems by activating the NPY receptor subfamily. Notably, NPY analogs display varying selectivity and exert diverse physiological effects through their interactions with this receptor family. [Pro34]-NPY and [Leu31, Pro34]-NPY, mainly acting on Y1R, reportedly increases blood pressure and postsynaptically potentiates the effect of other vasoactive substances above all, while N-terminal cleaved NPY variants in human body primary mediates angiogenesis and neurotransmitter release inhibition through Y2R. However, the recognition mechanisms of Y1R and Y2R with specific agonists remain elusive, thereby hindering subtype receptor-selective drug development. In this study, we report three cryo-electron microscopy (cryo-EM) structures of Gi2-coupled Y1R and Y2R in complexes with NPY, as well as Y1R bound to a selective agonist [Leu31, Pro34]-NPY. Combined with cell-based assays, our study not only reveals the conserved peptide-binding mode of NPY receptors but also identifies an additional sub-pocket that confers ligand selectivity. Moreover, our analysis of Y1R evolutionary dynamics suggests that this sub-pocket has undergone functional adaptive evolution across different species. Collectively, our findings shed light on the molecular underpinnings of neuropeptide recognition and receptor activation, and they present a promising avenue for the design of selective drugs targeting the NPY receptor family.

The Bidirectional Relationship of NPY and Mitochondria in Energy Balance Regulation

Energy balance is regulated by several hormones and peptides, and neuropeptide Y is one of the most crucial in feeding and energy expenditure control. NPY is regulated by a series of peripheral nervous and humoral signals that are responsive to nutrient sensing, but its role in the energy balance is also intricately related to the energetic status, namely mitochondrial function. During fasting, mitochondrial dynamics and activity are activated in orexigenic neurons, increasing the levels of neuropeptide Y. By acting on the sympathetic nervous system, neuropeptide Y modulates thermogenesis and lipolysis, while in the peripheral sites, it triggers adipogenesis and lipogenesis instead. Moreover, both central and peripheral neuropeptide Y reduces mitochondrial activity by decreasing oxidative phosphorylation proteins and other mediators important to the uptake of fatty acids into the mitochondrial matrix, inhibiting lipid oxidation and energy expenditure. Dysregulation of the neuropeptide Y system, as occurs in metabolic diseases like obesity, may lead to mitochondrial dysfunction and, consequently, to oxidative stress and to the white adipose tissue inflammatory environment, contributing to the development of a metabolically unhealthy profile. This review focuses on the interconnection between mitochondrial function and dynamics with central and peripheral neuropeptide Y actions and discusses possible therapeutical modulations of the neuropeptide Y system as an anti-obesity tool.

The Role of Neuropeptide Y in the Nucleus Accumbens

Neuropeptide Y (NPY), an abundant peptide in the central nervous system, is expressed in neurons of various regions throughout the brain. The physiological and behavioral effects of NPY are mainly mediated through Y1, Y2, and Y5 receptor subtypes, which are expressed in regions regulating food intake, fear and anxiety, learning and memory, depression, and posttraumatic stress. In particular, the nucleus accumbens (NAc) has one of the highest NPY concentrations in the brain. In this review, we summarize the role of NPY in the NAc. NPY is expressed principally in medium-sized aspiny neurons, and numerous NPY immunoreactive fibers are observed in the NAc. Alterations in NPY expression under certain conditions through intra-NAc injections of NPY or receptor agonists/antagonists revealed NPY to be involved in the characteristic functions of the NAc, such as alcohol intake and drug addiction. In addition, control of mesolimbic dopaminergic release via NPY receptors may take part in these functions. NPY in the NAc also participates in fat intake and emotional behavior. Accumbal NPY neurons and fibers may exert physiological and pathophysiological actions partly through neuroendocrine mechanisms and the autonomic nervous system.

Biased agonists at the human Y1 receptor lead to prolonged membrane residency and extended receptor G protein interaction

Functionally selective ligands to address specific cellular responses downstream of G protein-coupled receptors (GPCR) open up new possibilities for therapeutics. We designed and characterized novel subtype- and pathway-selective ligands. Substitution of position Q34 of neuropeptide Y to glycine (G34-NPY) results in unprecedented selectivity over all other YR subtypes. Moreover, this ligand displays a significant bias towards activation of the Gi/o pathway over recruitment of arrestin-3. Notably, no bias is observed for an established Y1R versus Y2R selective ligand carrying a proline at position 34 (F7,P34-NPY). Next, we investigated the spatio-temporal signaling at the Y1R and demonstrated that G protein-biased ligands promote a prolonged localization at the cell membrane, which leads to enhanced G protein signaling, while endosomal receptors do not contribute to cAMP signaling. Thus, spatial components are critical for the signaling of the Y1R that can be modulated by tailored ligands and represent a novel mode for biased pathways.

Enteroendocrine Regulation of Nutrient Absorption

Enteroendocrine cells (EECs) in the intestine regulate many aspects of whole-body physiology and metabolism. EECs sense luminal and circulating nutrients and respond by secreting hormones that act on multiple organs and organ systems, such as the brain, gallbladder, and pancreas, to control satiety, digestion, and glucose homeostasis. In addition, EECs act locally, on enteric neurons, endothelial cells, and the gastrointestinal epithelium, to facilitate digestion and absorption of nutrients. Many recent reports raise the possibility that EECs and the enteric nervous system may coordinate to regulate gastrointestinal functions. Loss of all EECs results in chronic malabsorptive diarrhea, placing EECs in a central role regulating nutrient absorption in the gut. Because there is increasing evidence that EECs can directly modulate the efficiency of nutrient absorption, it is possible that EECs are master regulators of a feed-forward loop connecting appetite, digestion, metabolism, and abnormally augmented nutrient absorption that perpetuates metabolic disease. This review focuses on the roles that specific EEC hormones play on glucose, peptide, and lipid absorption within the intestine.

The gender-specific expression of neuropeptide Y and neuropeptide Y receptors in human atrial tissue during cardiopulmonary bypass surgery

Background

Cardiac sympathetic nervous system is usually activated in cardiopulmonary bypass (CPB) surgery, accompanied by excessive release of norepinephrine (NE). Neuropeptide Y (NPY) has been shown to regulate NE release in the terminal of sympathetic fiber, which is a target for regulating heart function. The expression of NPY and NPY receptor (NPYR) genes in the human atrial tissues during CPB in cardiac surgery was investigated in the present study.

Methods

A few discarded atrial tissues before and after CPB were collected in 22 patients with rheumatic cardiac valve diseases. The transcriptional levels of NPY and NPYRs were monitored by real-time quantitative polymerase chain reaction (RT-qPCR) method. Moreover, the correlation between the mRNA levels of NPY/NPYRs and the clinical data were investigated in detail.

Results

The mRNA levels of NPY Y1 and NPY Y5 genes were statistically attenuated in male patients after CPB. Conversely, the expression of NPY, NPY Y1 and NPY Y5 genes were enhanced in female patients. Correlation analysis suggested that there was a significant negative correlation between cardiac ejection fraction (EF) after CPB with the atrial transcriptional level of NPY in male patients.

Conclusions

These results suggested that the expression of NPY/NPYRs in human atrial tissue during CPB was gender specific and activated NPY signaling was only identified in female patients. The elevated expression level of NPY in male patients was correlated with lower cardiac EF after CPB.

Neuropeptide Y in Alcohol Addiction and Affective Disorders

Neuropeptide Y (NPY), a neuropeptide highly conserved throughout evolution, is present at high levels in the central nervous system (CNS), as well as in peripheral tissues such as the gut and cardiovascular system. The peptide exerts its effects via multiple receptor subtypes, all belonging to the G-protein-coupled receptor superfamily. Of these subtypes, the Y1 and the Y2 are the most thoroughly characterized, followed by the Y5 subtype. NPY and its receptors have been shown to be of importance in central regulation of events underlying, for example, affective disorders, drug/alcohol use disorders, and energy homeostasis. Furthermore, within the CNS, NPY also affects sleep regulation and circadian rhythm, memory function, tissue growth, and plasticity. The potential roles of NPY in the etiology and pathophysiology of mood and anxiety disorders, as well as alcohol use disorders, have been extensively studied. This focus was prompted by early indications for an involvement of NPY in acute responses to stress, and, later, also data pointing to a role in alterations within the CNS during chronic, or repeated, exposure to adverse events. These functions of NPY, in addition to the peptide's regulation of disease states, suggest that modulation of the activity of the NPY system via receptor agonists/antagonists may be a putative treatment mechanism in affective disorders as well as alcohol use disorders. In this review, we present an overview of findings with regard to the NPY system in relation to anxiety and stress, acute as well as chronic; furthermore we discuss post-traumatic stress disorder and, in part depression. In addition, we summarize findings on alcohol use disorders and related behaviors. Finally, we briefly touch upon genetic as well as epigenetic mechanisms that may be of importance for NPY function and regulation. In conclusion, we suggest that modulation of NPY-ergic activity within the CNS, via ligands aimed at different receptor subtypes, may be attractive targets for treatment development for affective disorders, as well as for alcohol use disorders.

NPY Y1 receptors differentially modulate GABAA and NMDA receptors via divergent signal-transduction pathways to reduce excitability of amygdala neurons

Neuropeptide Y (NPY) administration into the basolateral amygdala (BLA) decreases anxiety-like behavior, mediated in part through the Y1 receptor (Y1R) isoform. Activation of Y1Rs results in G-protein-mediated reduction of cAMP levels, which results in reduced excitability of amygdala projection neurons. Understanding the mechanisms linking decreased cAMP levels to reduced excitability in amygdala neurons is important for identifying novel anxiolytic targets. We studied the intracellular mechanisms of activation of Y1Rs on synaptic transmission in the BLA. Activating Y1Rs by [Leu(31),Pro(34)]-NPY (L-P NPY) reduced the amplitude of evoked NMDA-mediated excitatory postsynaptic currents (eEPSCs), without affecting AMPA-mediated eEPSCs, but conversely increased the amplitude of GABAA-mediated evoked inhibitory postsynaptic currents (eIPSCs). Both effects were abolished by the Y1R antagonist, PD160170. Intracellular GDP-β-S, or pre-treatment with either forskolin or 8Br-cAMP, eliminated the effects of L-P NPY on both NMDA- and GABAA-mediated currents. Thus, both the NMDA and GABAA effects of Y1R activation in the BLA are G-protein-mediated and cAMP-dependent. Pipette inclusion of protein kinase A (PKA) catalytic subunit blocked the effect of L-P NPY on GABAA-mediated eIPSCs, but not on NMDA-mediated eEPSCs. Conversely, activating the exchange protein activated by cAMP (Epac) with 8CPT-2Me-cAMP blocked the effect of L-P NPY on NMDA-mediated eEPSCs, but not on GABAA-mediated eIPSCs. Thus, NPY regulates amygdala excitability via two signal-transduction events, with reduced PKA activity enhancing GABAA-mediated eIPSCs and Epac deactivation reducing NMDA-mediated eEPSCs. This multipathway regulation of NMDA- and GABAA-mediated currents may be important for NPY plasticity and stress resilience in the amygdala.

Influence of estradiol supplementation on neuropeptide Y neurotransmission in skeletal muscle arterioles of F344 rats

The effects of estradiol on neuropeptide Y (NPY) neurotransmission in skeletal muscle resistance vessels have not been described. The purpose of this study was to determine the effects of long-term estradiol supplementation on NPY overflow, degradation, and vasoconstriction in gastrocnemius first-order arterioles of adult female rats. Female rats (4 mo; n = 34) were ovariectomized (OVX) with a subset (n = 17) receiving an estradiol pellet (OVE; 17β-estradiol, 4 μg/day). After conclusion of the treatment phase (8 wk), arterioles were excised, placed in a physiological saline solution (PSS) bath, and cannulated with micropipettes connected to albumin reservoirs. NPY-mediated vasoconstriction via a Y(1)-agonist [Leu31Pro34]NPY decreased vessel diameter 44.54 ± 3.95% compared with baseline; however, there were no group differences in EC(50) (OVE: -8.75 ± 0.18; OVX: -8.63 ± 0.10 log M [Leu31Pro34]NPY) or slope (OVE: -1.11 ± 0.25; OVX: -1.65 ± 0.34% baseline/log M [Leu31Pro34]NPY). NPY did not potentiate norepinephrine-mediated vasoconstriction. NPY overflow experienced a slight increase following field stimulation and significantly increased (P < 0.05) over control conditions in the presence of a DPPIV inhibitor (diprotin A). Estradiol status did not affect DPPIV activity. These data suggest that NPY can induce a moderate decrease in vessel diameter in skeletal muscle first-order arterioles, and DPPIV is active in mitigating NPY overflow in young adult female rats. Long-term estradiol supplementation did not influence NPY vasoconstriction, overflow, or its enzymatic breakdown in skeletal muscle first-order arterioles.

NPY receptors as potential targets for anti-obesity drug development

The neuropeptide Y system has proven to be one of the most important regulators of feeding behaviour and energy homeostasis, thus presenting great potential as a therapeutic target for the treatment of disorders such as obesity and at the other extreme, anorexia. Due to the initial lack of pharmacological tools that are active in vivo, functions of the different Y receptors have been mainly studied in knockout and transgenic mouse models. However, over recent years various Y receptor selective peptidic and non-peptidic agonists and antagonists have been developed and tested. Their therapeutic potential in relation to treating obesity and other disorders of energy homeostasis is discussed in this review.

Neuropeptide Y overflow and metabolism in skeletal muscle arterioles

The purpose of this study was to characterize neuropeptide Y (NPY) overflow and metabolism from isolated skeletal muscle arterioles of female rats. Gastrocnemius first-order arterioles were removed from young (2 months), young adult (6 months) and middle-aged (12 months) F344 female rats. Arterioles were isolated, cannulated and pressurized in a microvessel bath with field stimulation electrodes. NPY overflow from isolated arterioles was assessed at 0 s and 30 s post-field stimulation. Dipeptidyl peptidase IV (DPPIV) activity was quantified via fluorometric assay of whole vessel homogenate. In young adult and middle-aged rats, NPY overflow increased 0 s and 30 s following field stimulation. In young adult rats, DPPIV inhibition resulted in an increase in NPY overflow at 30 s, while middle-aged rats had no increase in NPY overflow with DPPIV inhibition (P <0.05). DPPIV activity was influenced by factors such as age, vessel type, and endothelium (P <0.05). The present data suggest that DPPIV plays a significant role in modulating the actions of NPY in arterioles of young adult females; however, this role appears to diminish with age.

Therapeutic potential of neuropeptide Y (NPY) receptor ligands

Neuropeptide Y (NPY) is widely distributed in the human body and contributes to a vast number of physiological processes. Since its discovery, NPY has been implicated in metabolic regulation and, although interest in its role in central mechanisms related to food intake and obesity has somewhat diminished, the topic remains a strong focus of research concerning NPY signalling. In addition, a number of other uses for modulators of NPY receptors have been implied in a range of diseases, although the development of NPY receptor ligands has been slow, with no clinically approved receptor therapeutics currently available. Nevertheless, several interesting small molecule compounds, notably Y2 receptor antagonists, have been published recently, fueling optimism in the field. Herein we review the role of NPY in the pathophysiology of a number of diseases and highlight instances where NPY receptor signalling systems are attractive therapeutic targets.

Neuropeptide Y Y5 receptor promotes cell growth through extracellular signal-regulated kinase signaling and cyclic AMP inhibition in a human breast cancer cell line

Overexpression of neuropeptide Y (NPY) and its receptor system has been reported in various types of cancers. NPY Y5 receptor (Y5R) has been implicated in cell growth and angiogenesis. However, the role of Y5R in breast cancer is unknown. To identify the role of Y5R in breast cancer, we screened several breast cancer cell lines to examine the expression of Y5R and its function in breast cancer. All screened cell lines express both Y1 receptor and Y5R except BT-549, which expresses mainly Y5R. Binding studies showed that NPY, Y5R-selective agonist peptide, and Y5R-selective antagonist (CGP71683A) displaced (125)I-PYY binding in BT-549 cell membranes in a dose-dependent manner. The displacement studies revealed the presence of two binding sites in Y5R with IC(50) values of 29 pmol/L and 531 nmol/L. NPY inhibited forskolin-stimulated cyclic AMP accumulation with an IC(50) value of 52 pmol/L. NPY treatment of BT-549 cells induced extracellular signal-regulated kinase phosphorylation but did not alter intracellular calcium. Y5R activation stimulates BT-549 cell growth, which is inhibited by CGP71683A, pertussis toxin, and extracellular signal-regulated kinase blockade. CGP71683A alone induced cell death in a time- and dose-dependent manner in Y5R-expressing cells. The stimulation of MDA MB-231 cell migration by NPY is inhibited by CGP71683A. Together, our results suggest that Y5R plays an important role in cancer cell growth and migration and could be a novel therapeutic target for breast cancer.

Estrogen modulates the contribution of neuropeptide Y to baseline hindlimb blood flow control in female Sprague-Dawley rats

The purpose of this study was to determine the role of estrogen in neuropeptide Y (NPY) and Y(1) receptor (Y(1)R)-mediated vascular responses in female rats. Based on earlier work from our laboratory that female rats lacked an NPY contribution to hindlimb vascular conductance relative to males, we tested the hypothesis that estrogen modulates Y(1)R-mediated hindlimb blood flow control. Thus it was expected that ovariectomy would: 1) increase skeletal muscle Y(1)R expression, 2) decrease skeletal muscle Y(2) receptor (Y(2)R) expression, 3) decrease peptidase activity, and/or 4) increase overall skeletal muscle NPY concentration. Separate groups of control (CTL), ovariectomized (OVX), and OVX + 17beta-estradiol replacement (OVX + E(2); 21-day pellet) rats were studied. Animals were anesthetized and given localized hindlimb delivery of BIBP-3226 (Y(1)R antagonist), while femoral artery blood flow and blood pressure were recorded. Tissue samples from the white and red vastus lateralis muscle were extracted to examine Y(1)R and Y(2)R expression, peptidase activity, and NPY concentration. We found that Y(1)R blockade resulted in increased baseline hindlimb blood flow and vascular conductance in OVX rats, whereas no change was noted in CTL or OVX + E(2) groups (P < 0.05). This enhanced functional effect in the OVX group aligned with greater skeletal muscle Y(1)R expression in white vastus muscle and a substantial increase in NPY concentration in both white and red vastus muscle compared with CTL and OVX + E(2) groups. There was no change in Y(2)R expression or peptidase activity among the groups. These data support the hypothesis that estrogen blunts Y(1)R activation in the rat hindlimb through an effect on Y(1)R expression and NPY concentration.

Neuropeptide Y and neurovascular control in skeletal muscle and skin

Neuropeptide Y (NPY) is a ubiquitous peptide with multiple effects on energy metabolism, reproduction, neurogenesis, and emotion. In addition, NPY is an important sympathetic neurotransmitter involved in neurovascular regulation. Although early studies suggested that the vasoactive effects of NPY were limited to periods of high stress, there is growing evidence for the involvement of NPY on baseline vasomotor tone and sympathetically evoked vasoconstriction in vivo in both skeletal muscle and the cutaneous circulation. In Sprague-Dawley rat skeletal muscle, Y(1)-receptor activation appears to play an important role in the regulation of basal vascular conductance, and this effect is similar in magnitude to the alpha(1)-receptor contribution. Furthermore, under baseline conditions, agonist and receptor-based mechanisms for Y(1)-receptor-dependent control of vascular conductance in skeletal muscle are greater in male than female rats. In skin, there is Y(1)-receptor-mediated vasoconstriction during whole body, but not local, cooling. As with the NPY system in muscle, this neural effect in skin differs between males and females and in addition, declines with aging. Intriguingly, skin vasodilation to local heating also requires NPY and is currently thought to be acting via a nitric oxide pathway. These studies are establishing further interest in the role of NPY as an important vasoactive agent in muscle and skin, adding to the complexity of neurovascular regulation in these tissues. In this review, we focus on the role of NPY on baseline vasomotor tone in skeletal muscle and skin and how NPY modulates vasomotor tone in response to stress, with the aim of compiling what is currently known, while highlighting some of the more pertinent questions yet to be answered.

Novel role of Y1 receptors in the coordinated regulation of bone and energy homeostasis

The importance of neuropeptide Y (NPY) and Y2 receptors in the regulation of bone and energy homeostasis has recently been demonstrated. However, the contributions of the other Y receptors are less clear. Here we show that Y1 receptors are expressed on osteoblastic cells. Moreover, bone and adipose tissue mass are elevated in Y1(-/-) mice with a generalized increase in bone formation on cortical and cancellous surfaces. Importantly, the inhibitory effects of NPY on bone marrow stromal cells in vitro are absent in cells derived from Y1(-/-) mice, indicating a direct action of NPY on bone cells via this Y receptor. Interestingly, in contrast to Y2 receptor or germ line Y1 receptor deletion, conditional deletion of hypothalamic Y1 receptors in adult mice did not alter bone homeostasis, food intake, or adiposity. Furthermore, deletion of both Y1 and Y2 receptors did not produce additive effects in bone or adiposity. Thus Y1 receptor pathways act powerfully to inhibit bone production and adiposity by nonhypothalamic pathways, with potentially direct effects on bone tissue through a single pathway with Y2 receptors.

Age-related effect of peptide YY (PYY) on paw edema in the rat: the function of Y1 receptors on inflammatory cells

It is well documented that neuropeptides participate in local inflammatory reaction and modulate functions of inflammatory cells. The aim of the study was to determine a link between in vivo and in vitro effects of NPY-related peptides on inflammatory response with respect to ageing. Peptide YY (PYY) intraplantarly applied decreases concanavalin A-induced paw edema in 3 and 8 months, but not in 24 months old male rats of Albino Oxford strain. The use of NPY-related receptor-specific peptides and Y1 receptor antagonist revealed that anti-inflammatory effect of PYY is mediated via NPY Y1 receptors. PYY in vitro decreases adherence of macrophages from 8 months, but not from 3 and 24 months old rats and this effect is also mediated via NPY Y1 receptor. Additionally, PYY (10(-6)M) decreases NBT reduction in macrophages from 3 and 8 months old rats, and suppresses NO production in cells from 24 months old rats, albeit regardless of absence of in vivo effect of PYY on inflammation in aged rats. It is concluded that aged rats are less responsive to anti-inflammatory action of PYY compared to adult and young rats, and that ageing is associated with altered NPY Y1 receptor functioning.

Effect of peripheral axotomy on pain-related behavior and dorsal root ganglion neurons excitability in NPY transgenic rats

In order to clarify the physiologic role of NPY in sensory processing, we obtained intracellular recordings of DRG neurons from wild type (WT) and NPY overexpressing transgenic rats (NPY-TG) before and after injury. We investigated medium and large diameter DRG neurons since upregulation of NPY peptide following the nerve injury occurs primarily in those cells. Neurons were classified as Aalpha/beta and Adelta using conduction velocity and action potential duration. Prior to the injury, Aalpha/beta neurons of NPY-TG rats conducted more slowly and had a more brief AHP than similar cells from the WT group. Adelta neurons at baseline conducted faster in TG animals compared to WT. Ligation of the 5th lumbar spinal nerve (SNL) produced certain changes in Aalpha/beta cells that were evident only in the TG group. These include increased refractory period, increased input resistance, AHP prolongation and a depolarizing shift in threshold for AP initiation. The expected injury-induced CV slowing was not seen in NPY-TG Aalpha/beta cells. In the Adelta cell group, injury produced a depolarizing shift in the resting membrane potential, an increase in AP duration and decrease in AHP and refractory period duration only in WT rats, while NPY-TG cells lacked these injury-induced changes. Behavior tests showed diminished sensory response to nerve injury in NPY-TG rats, i.e., shorter duration of enhanced pain-related behavior and attenuation of contralateral effect. In conclusion, our observations suggest that NPY overexpression leads to reduced neuronal activity following nerve injury in a cell-specific manner.

Peptide YY (3–36) inhibits dopamine and norepinephrine release in the hypothalamus

Peptide YY (1-36) and peptide YY (3-36) are gut-derived hormones which are involved in feeding control in the hypothalamus. The hypothalamic mechanisms of feeding have been shown to be modulated by aminergic neurotransmitters, which could mediate the anorectic or orexigenic effects of neuropeptides and hormones. We have investigated the role of peptide YY (1-36) and peptide YY (3-36) on dopamine, norepinephrine, and serotonin release from hypothalamic synaptosomes in vitro. We found that peptide YY (3-36) inhibited depolarization-induced dopamine and norepinephrine release, leaving unaffected serotonin release, while peptide YY (1-36) did not modify either basal or stimulated amine release. We can hypothesize that the effects of peptide YY (3-36) could be mediated by inhibited hypothalamic dopamine and norepinephrine release, which could partially account for the anorectic activity of the peptide. On the other hand, peptide YY (1-36), which has a feeding stimulatory role, does not affect aminergic neurotransmission in the hypothalamus.

Sympathetic co-transmission: the coordinated action of ATP and noradrenaline and their modulation by neuropeptide Y in human vascular neuroeffector junctions

The historical role of noradrenaline as the predominant sympathetic neurotransmitter in vascular neuroeffector junctions has matured to include ATP and the modulator action of neuropeptide Y (NPY). Numerous studies with isolated blood vessels rings demonstrate the presence of key enzymes responsible for the synthesis of ATP, noradrenaline and NPY, their co-storage, and their electrically evoked release from sympathetic perivascular nerve terminals. Functional assays coincide to demonstrate the integral role of these neurochemicals in sympathetic reflexes. In addition, the detection of the diverse receptor populations for ATP, noradrenaline and NPY in blood vessels, either in the smooth muscle, endothelial cells or nerve endings, further contribute to the notion that sympathetic vascular reflexes encompass the orchestrated action of the noradrenaline and ATP, and their modulation by NPY. The future clinical opportunities of sympathetic co-transmission in the control of human cardiovascular diseases will be highlighted.

From Transcription Profile to Expression: The Signaling Repertoire of the SK-N-MC Neuroepithelioma Cell-Line

SK-N-MC neuroepithelioma cells are routinely cultured and widely used as a model system in biochemical and pharmacological experiments. To clarify the gene expression patterns of SK-N-MC cells with respect to G protein-coupled receptors and signaling network components, we describe in this report the transcription profile of the cell line. Following the traditional pathway from genome to proteome, selected examples are further examined at the level of protein expression and by functional assays. cRNA targets derived from total RNA extracts were hybridized to Affymetrix Human Genome U133A GeneChip arrays, and the data were analyzed and grouped according to functional aspects. Results obtained for neuropeptide Y (NPY) Y1, Y5, and orexin Ox1 receptors were confirmed by RT-PCR. It is surprising that we found the presence of both NPY receptor subtypes and the absence of the orexin receptor at the mRNA level. Receptor-binding experiments confirmed NPY binding of the Y1 receptor in the nanomolar range but gave no evidence for high expression levels of Y5 receptor subtypes on the cell surface. Protein expression was assayed with immunoblots by using antibodies directed against selected Galpha protein subunits. The presence of at least Galphas, Galphai3, and Galphai2 subunits was indicated.

Neuropeptide Y is released from human mammary and radial vascular biopsies and is a functional modulator of sympathetic cotransmission

The role of neuropeptide Y (NPY) as a modulator of the vasomotor responses mediated by sympathetic cotransmitters was examined by electrically evoking its release from the perivascular nerve terminals of second- to third-order human blood vessel biopsies and by studying the peptide-induced potentiation of the vasomotor responses evoked by exogenous adenosine 5' triphosphate (ATP) and noradrenaline (NA). Electrical depolarization of nerve terminals in mammary vessels and radial artery biopsies elicited a rise in superfusate immunoreactive NPY (ir-NPY), which was chromatographically identical to a standard of human NPY (hNPY); a second peak was identified as oxidized hNPY. The amount released corresponds to 4-6% of the total NPY content in these vessels. Tissue extracts also revealed two peaks; hNPY accounted for 68-85% of the ir-NPY, while oxidized hNPY corresponded to 7-15%. The release process depended on extracellular calcium and on the frequency and duration of the electrical stimuli; guanethidine blocked the release, confirming the peptide's sympathetic origin. Assessment of the functional activity of the oxidized product demonstrated that while it did not change basal tension, the NA-evoked contractions were potentiated to the same extent as with native hNPY. Moreover, NPY potentiated both the vasomotor action of ATP or NA alone and the vasoconstriction elicited by the simultaneous application of both cotransmitters. RT-PCR detected the mRNA coding for the NPY Y(1) receptor. In summary, the release of hNPY or its oxidized species, elicited by nerve terminal depolarization, coupled to the potentiation of the sympathetic cotransmitter vasomotor responses, highlights the modulator role of NPY in both arteries and veins, strongly suggesting its involvement in human vascular sympathetic reflexes.

Importance of NPY Y1 receptor-mediated pathways: assessment using NPY Y1 receptor knockouts

The peptidic neurotransmitter neuropeptide Y (NPY) has been functionally implicated in feeding behavior, cardiovascular regulation, control of neuroendocrine axes, affective disorders, seizures, and memory retention. At least five different receptors mediate NPY actions. In particular, the Y1 receptor appears to be involved in a variety of NPY-induced pathways. This review summarizes the main findings resulting from the use of mice lacking NPY Y1 receptor expression. Interestingly, the overall phenotype of Y1 knockouts mimics metabolic syndrome, which is characterized by obesity, a prediabetic state, and a susceptibility to develop hypertension.

Release and functional role of neuropeptide Y as a sympathetic modulator in human saphenous vein biopsies

Transmural electrical stimulation of the sympathetic nerve endings of human saphenous vein biopsies released two forms of NPY identified chromatographically as native and oxidized peptide. The release process is dependent on extracellular calcium, the frequency, and the duration of the stimuli. While guanethidine reduced the overflow of ir-NPY, phenoxybenzamine did not augment NPY release, but increased that of noradrenaline. Oxidized NPY, like native NPY, potentiated the noradrenaline and adenosine 5'-triphospahate-induced vasoconstriction, an effect blocked by BIBP 3226 and consonant with the RT-PCR detection of the mRNA encoding the NPY Y1 receptor. These results highlight the functional role of NPY in human vascular sympathetic reflexes.

Neuropeptide y targets in the hypothalamus: nitric oxide synthesizing neurones express Y1 receptor

Neuropeptide Y (NPY)-expressing neurones in the arcuate nucleus densely innervate many hypothalamic nuclei. To determine the neurochemical phenotype of target neurones for NPY, we studied the immunohistochemical localization of the NPY Y1 receptor (Y1R) in discrete subpopulations of neurones in the rat hypothalamus. Among several tested populations, including hypocretin/orexin-, melanin-concentrating hormone (MCH)- and nitric oxide synthase (NOS)-positive neurones, only the latter were found to coexpress the Y1R. Numerous Y1R/NOS-positive neurones were found as a densely packaged group of cells located ventrolateral to the ventromedial nucleus, forming a band ascending towards the fornix. Lower numbers of Y1R/NOS-positive neurones were found in the perifornical area and in the peri- and paraventricular nuclei. Expression of the Y1R gene was found in the same locations in the mouse by colocalizing beta-galactosidase, a Y1R gene reporter, with NOS in a Y1R knockout mouse. To explore possible downstream targets of NO in the rat hypothalamus, the NO-regulated molecule cGMP was analysed immunohistochemically after incubation of brain slices with sodium nitroprusside, an NO donor. We observed several cGMP-positive cell bodies in the arcuate nucleus, cGMP-positive blood vessels and a cGMP-positive network of thin fibres, some of which colocalized with choline acetyltransferase.

Neuropeptide Y inhibits axonal transport of particles in neurites of cultured adult mouse dorsal root ganglion cells

Neuropeptide Y (NPY) plays a modulatory role in processing nociceptive information. The present study investigated the effects of NPY on axonal transport of particles in neurites of cultured adult dorsal root ganglion (DRG) cells using video-enhanced microscopy. Application of NPY decreased the number of particles transported in both the anterograde and retrograde directions. This effect was persistently observed during NPY application and was reversed after washout. The inhibitory effect of NPY was concentration dependent between 10(-9) M and 10(-6) M. The instantaneous velocity of individual particles moving in anterograde and retrograde directions was also reduced by NPY. Both the NPY Y1 receptor agonist [Leu31,Pro34]-NPY and NPY Y2 receptor agonist NPY(13-36) mimicked the effect of NPY on the number of transported particles. An immunocytochemical study using an antiserum against the NPY Y1 receptor protein revealed that the Y1 receptor was expressed in the majority (85.9 %) of cultured adult mouse DRG cells. Pre-treatment of cells with pertussis toxin, a GTP-binding protein (G protein) inhibitor, completely blocked the inhibitory effect of NPY. Each application of SQ-22536, an adenylate cyclase inhibitor, and H-89, a protein kinase A inhibitor, mimicked and occluded the effect of NPY. In contrast, dibutyryl cAMP (dbcAMP), a membrane permeable cAMP analogue, and forskolin, an activator of adenylate cyclase, produced a transient increase in axonal transport. The application of dbcAMP and forskolin in combination with NPY negated the effect of NPY alone. These results suggest that NPY, acting at Y1 and Y2 receptors, inhibits axonal transport of particles in sensory neurones. The effect seems to be mediated by a pertussis toxin-sensitive G protein, adenylate cyclase, and protein kinase A pathway. Therefore, NPY may be a modulatory factor for axonal transport in sensory neurones.

Circuits and systems in stress. I. Preclinical studies

This paper reviews the preclinical literature related to the effects of stress on neurobiological and neuroendocrine systems. Preclinical studies of stress provide a comprehensive model for understanding neurobiological alterations in post-traumatic stress disorder (PTSD). The pathophysiology of stress reflects long-standing changes in biological stress response systems and in systems involved in stress responsivity, learning, and memory. The neural circuitry involved includes systems mediating hypothalamic-pituitary-adrenal (HPA) axis, norepinephrine (locus coeruleus), and benzodiazepine, serotonergic, dopaminergic, neuropeptide, and central amino acid systems. These systems interact with brain structures involved in memory, including hippocampus, amygdala, and prefrontal cortex. Stress responses are of vital importance in living organisms; however excessive and/or repeated stress can lead to long-lasting alterations in these circuits and systems involved in stress responsiveness. Intensity and duration of the stressor, and timing of the stressor in life, have strong impact in this respect.

Effects of blockade of alpha- and beta-adrenoceptors and neuropeptide Y(1) receptors, as well as brachial plexus blockade, on endothelium-dependent vasodilation in the human forearm

1. The aim of the present study was to investigate the effects of alpha-adrenoceptor blockade (phentolamine), beta-adrenoceptor blockade (propranolol), neuropeptide Y(1) receptor blockade and neurogenic blockade (brachial plexus) on endothelium-dependent vasodilation (EDV) in the human forearm. 2. Forty-four young healthy volunteers underwent forearm blood flow (FBF) measurements, using venous occlusion plethysmography, during local intra-arterial infusions of methacholine (MCh; inducing EDV) and sodium nitroprusside (SNP; inducing endothelium-independent vasodilation (EIDV)). These measurements were undertaken at baseline and were repeated with either concomitant local intra-arterial infusion of phentolamine (n = 8), propranolol (n = 7) or saline (n = 6) in the forearm, neuropeptide Y(1) receptor blockade (n = 12) given i.v. or during axillary plexus blockade (n = 11). 3. Both alpha-adrenoceptor blockade and neurogenic blockade induced an upward shift in the dose-response curve for both EDV and EIDV. beta-Adrenoceptor blockade did not change resting FBF or EIDV, but induced a significant decrease in EDV (P = 0.015). Neuropeptide Y(1) receptor blocker induced no significant changes in resting FBF, EDV and EIDV and neither did saline. No changes in blood pressure or heart rate were induced by any of the blockades. 4. Whereas beta-adrenoceptor blockade impaired EDV, alpha-adrenoceptor blockade and neurogenic blockade caused a general vasodilation that was not endothelium dependent. Neuropeptide Y does not seem to influence blood flow in the resting forearm.

Neuropeptide Y-Y1 receptor modulates nitric oxide level during stroke in the rat

In a rat endovascular middle cerebral artery occlusion (MCAO) stroke model, we previously showed that intracerebroventricular (ICV) injection of neuropeptide Y (NPY) or an Y1 receptor agonist, [Leu(31),Pro(34)]-NPY, increased the infarct volume, that an Y1 receptor antagonist, BIBP3226, reduced the infarct volume, and that an Y2 receptor agonist, NPY3-36, had no effect. In this study, we used electron paramagnetic resonance (EPR) spectroscopy to measure nitric oxide (NO) and examined how ICV administration of NPY or its receptor analogs would modulate the brain NO level between the bregma levels +2 and -4 mm during MCAO, since excessive NO mediates ischemic damage. The relative brain NO concentration was increased to 131.94 +/- 7.99% (mean +/- SEM; n = 8) at 15 min of MCAO. NPY treatment further increased the relative brain NO concentration to 250.94 +/- 50.48% (n = 8), whereas BIBP3226 significantly reduced the brain NO concentration to 69.63 +/- 8.84% (n = 8). [Leu(31),Pro(34)]-NPY (137.61 +/- 14.54%; n = 7) or NPY3-36 (129.23 +/- 21.77%; n = 8) did not affect the brain NO concentration at 15 min of MCAO. Our results suggest that the NPY-Y1 receptor activation mediates ischemic injury via NO overproduction and that inhibition of the Y1 receptor may confer protection via suppression of excessive NO production during ischemia.

Autoinhibitory function of the sympathetic prejunctional neuropeptide Y Y(2) receptor evidenced by BIIE0246

The significance of neuropeptide Y Y(2) receptors in sympathetic nonadrenergic transmission was investigated using the novel selective antagonist BIIE0246 ((S)-N2-[[1-[2-[4-[(R,S)-5,11-dihydro-6(6h)-oxodibenz[b,e]azepin-11-yl]-1-piperazinyl]-2-oxoethyl]cyclopentyl]acetyl]-N-[2-[1,2-dihydro-3,5 (4H)-dioxo-1,2-diphenyl-3H-1,2,4-triazol-4-yl]ethyl]-argininamide). In anaesthetized pigs pretreated with reserpine, and after transection of sympathetic nerves (depleted of noradrenaline), electrical stimulation of renal and splanchnic sympathetic nerves evoked vasoconstriction in, and overflow of neuropeptide Y-like immunoreactivity from, kidney and spleen, respectively. In the presence of BIIE0246, the nerve-evoked overflows of neuropeptide Y-like immunoreactivity were markedly increased and the splenic vasoconstrictor response prolonged. In addition, BIIE0246 caused splenic vasodilatation per se in this model where basal levels of circulating neuropeptide Y exceed 40 pM. It is concluded that endogenous neurogenical neuropeptide Y regulates its own release via activation of sympathetic prejunctional inhibitory neuropeptide Y Y(2) receptors in both spleen and kidney in the reserpinized pig. Moreover, when circulating levels of neuropeptide Y are moderately increased, activation of neuropeptide Y Y(2) receptors seems to contribute to basal splenic vascular tone.

Aminopyrazoles with high affinity for the human neuropeptide Y5 receptor

1,3-Disubstituted-5-aminopyrazoles were prepared based on a lead compound found through high-throughput screening of our corporate compound library in an assay measuring affinity for the human neuropeptide Y5 receptor. The target compounds were prepared by cyclization of alpha-cyanoketones with appropriate hydrazines, followed by reduction and coupling to various sulfonamido-carboxylic acids. Several of these arylpyrazoles (e.g., 19 and 45) displayed high affinity for the human NPY Y5 receptor (<20nM IC(50)s).

Pyrazolecarboxamide human neuropeptide Y5 receptor ligands with in vivo antifeedant activity

1-Aryl-3-carboxamido-5-alkylpyrazoles were prepared based on a hit found in high-throughput screening of our corporate compound library in an assay measuring affinity for the human neuropeptide Y5 receptor. 1-(3-Trifluoromethylphenyl)-3-[N-(5-quinolinyl)carboxamido]-5-methylpyrazole (31) bound to the human neuropeptide Y5 receptor with a 80 nM IC(50 )and was shown to inhibit cumulative food consumption 43.2% 2-6 h after ip dosing in a fasting-induced feeding model in rats.

Regulation of the Y1 neuropeptide Y receptor gene expression in PC12 cells

The Y1 receptor for neuropeptide Y (NPY-Y1) is constitutively expressed in PC12 cells. In this study, we examined the role of nerve growth factor (NGF), pituitary adenylyl cyclase activating polypeptide (PACAP) and dexamethasone on the expression of the gene encoding the rat NPY-Y1 receptor in PC12 cells. A fusion gene (pY1-Luc) was constructed where the reporter enzyme firefly luciferase was placed under the control of 700 bp of the promoter region of the rat NPY-Y1 receptor gene. This promoter region contains recognition consensus sequences for various transcription factors, including one activation protein-1 (AP-1) site, two cyclic AMP responsive element sites, one estrogen receptor element site and four glucocorticoid receptor element sites. NGF increased luciferase activity in a concentration dependent manner. This increase was inhibited by K-252a, a trk A receptor inhibitor, and calphostin C, a PKC inhibitor. PACAP-38 increased luciferase activity in a concentration dependent manner. This activation was inhibited by H-89. Dexamethasone increased transcription of NPY-Y1 gene in PC12 cells. These results indicate that differentiation of PC12 cells into endocrine-like phenotype by dexamethasone and into a neuronal-like phenotype by either NGF or PACAP-38 increases the transcriptional activity of the NPY-Y1 receptor gene in PC12 cells.

Neurohormonal regulation of secretion from isolated rat stomach ECL cells: a critical reappraisal

ECL cells are endocrine/paracrine cells in the oxyntic mucosa. They produce, store and secrete histamine and chromogranin A-derived peptides such as pancreastatin. The regulation of ECL-cell secretion has been studied by several groups using purified ECL cells, isolated from rat stomachs. Reports from different laboratories often disagree. The purpose of the present study was to re-evaluate the discrepancies by studying histamine (or pancreastatin) secretion from standardized preparations of pure, well-functioning ECL cells. Cells from rat oxyntic mucosa were dispersed by pronase digestion, purified by repeated counter-flow elutriation and subjected to density gradient centrifugation. The final preparation consisted of more than 90% ECL cells (verified by histamine and/or histidine decarboxylase immunocytochemistry). They were maintained in primary culture for 48 h before they were exposed to candidate stimulants and inhibitors for 30 min after which the medium was collected for determination of mobilized histamine (or pancreastatin). Gastrin-17 and sulphated cholecystokinin octapeptide (CCK-8s) raised histamine secretion 4-fold, the EC(50) for both peptides being around 100 pM. The neuropeptide pituitary adenylate cyclase activating peptide (PACAP-27) (5-fold increase) and the related neuropeptides vasoactive intestinal peptide (VIP) and peptide histidine isoleucine (PHI) (3-fold increase) mobilized histamine with similar potency (EC(50) ranging from 80 to 140 pM). Adrenaline, isoprenaline and terbutaline stimulated secretion by activating a beta2 receptor subtype, while acetylcholine and carbachol were without effect. Secretion experiments were invariably run in parallel with a gastrin standard curve. Somatostatin, prostaglandin E2 (PGE2) and the PGE1 congener misoprostol inhibited PACAP- and gastrin-stimulated secretion by more than 90%, with IC(50) values ranging from 90-720 (somatostatin) to 40-200 (misoprostol) pM. The neuropeptide galanin inhibited secretion by 60-70% with a potency similar to that of somatostatin. Proposed inhibitors such as peptide YY, neuropeptide Y and the cytokines interleukin 1-beta and tumor necrosis factor alpha induced at best a moderate inhibition of gastrin- or PACAP-stimulated secretion at high concentrations, while calcitonin gene-related peptide, pancreatic polypeptide and histamine itself were without effect. Inhibition of gastrin- or PACAP-stimulated secretion was routinely compared to a somatostatin standard curve. In conclusion, gastrin, PACAP, VIP/PHI and adrenaline stimulated secretion. Somatostatin and PGE2 were powerful inhibitors of both gastrin- and PACAP-stimulated secretion; although equally potent, galanin was less effective than somatostatin and PGE2.

Neuropeptide Y Y2 receptor signalling mechanisms in the human glioblastoma cell line LN319

Neuropeptide Y (NPY) regulates neurotransmitter release through activation of the Y2 receptor subtype. We have recently characterized a human glioblastoma cell line, LN319, that expresses exclusively NPY Y2 receptors and have demonstrated that NPY triggers transient decreases in cAMP and increases in intracellular calcium responses. The present study was designed to further characterize calcium signalling by NPY and bradykinin (BK) in LN319 cells. Both agonists elevated free intracellular calcium ([Ca(2+)](i)) without soliciting calcium influx. NPY appeared to activate two distinct signalling cascades that liberate calcium from thapsigargin- and ryanodine-insensitive compartments. One pathway proceeded through phospholipase C (PLC)-dependent phosphatidylinositol turnover, while the other triggered calcium release through a so far unidentified mediator. Part of the response was sensitive to pertussis toxin (PTX) under conditions where the toxin totally abolished the NPY-mediated effects on cAMP. The calcium release induced by BK on the other hand was largely PTX-insensitive, PLC-dependent, and from both thapsigargin- and ryanodine-sensitive stores. Following stimulation with NPY, subsequent [Ca(2+)](i) responses to NPY were strongly depressed. Partial heterologous desensitization occurred, when BK was used as the first agonist, whereas NPY had no effect on a subsequent stimulation with BK. These data suggest that NPY-induced calcium mobilization in LN319 cells involves two different G proteins and signalling mediators, and a hitherto unidentified calcium compartment. Homologous desensitization of NPY signalling might be explained by receptor-G protein uncoupling, while heterologous desensitization by BK could be the result of either transient depletion or inhibition of a mediator in the calcium signalling cascades activated by NPY.

Neuropeptide Y-mediated constriction and dilation in rat middle cerebral arteries

Neuropeptide Y (NPY) is an important vasoconstrictor in the cerebral circulation. Its constrictor response is because of activation of NPY receptors on the vascular smooth muscle (VSM). Little is known regarding the effects of NPY on the endothelium. In the current study, the authors tested the hypothesis that NPY can either constrict or dilate rat middle cerebral arteries (MCAs). Constriction is elicited by stimulating receptors on the VSM; dilation is elicited by stimulating receptors on the endothelium. Middle cerebral arteries were isolated, cannulated with micropipettes, pressurized to 85 mm Hg, and luminally perfused. The extraluminal application of NPY (mixed agonist), [Leu31, Pro34]-NPY (Y1 agonist), or NPY-[13-36] (Y2 agonist) produced concentration-dependent constrictions. BIBP 3226 (Y1 selective antagonist) significantly attenuated the NPY- and [Leu31, Pro34]-NPY-induced constrictions. The luminal application of NPY, [Leu31, Pro34]-NPY, and NPY-[13-36] produced concentration-dependent dilations of MCAs. The maximum dilation produced by the NPY receptor agonists was approximately 40% of the dilation elicited by the luminal administration of 10(-5) mol/L ATP. Dilations elicited by luminal NPY, [Leu31, Pro34]-NPY, or NPY-[13-36] were abolished by inhibition of nitric oxide synthase with 10(-5) mol/L Nomega-nitro-L-arginine methyl ester (L-NAME) or removal of the endothelium. Dilations produced by luminal NPY or luminal [Leu31, Pro34]-NPY were not affected by BIBP 3226. Stimulation of NPY receptors on vascular smooth muscle constricted MCAs. Stimulation of an NPY receptor other than the Y1 subtype on endothelium dilated the MCAs by releasing nitric oxide.

Neuropeptide Y1- and Y2-receptor-mediated cardiovascular effects in the anesthetized guinea pig, rat, and rabbit

Neuropeptide Y (NPY) causes vasoconstriction through Y1-receptors and inhibits vagal bradycardia through presynaptic Y2-receptors. These effects of NPY were investigated in anesthetized guinea pigs, rats, and rabbits to find the most suitable species for evaluation of Y1- and Y2-active agents in vivo. The increase in blood pressure (through Y1) of lower doses of NPY was similar in the three species (ED50, 0.9 +/- 0.13, 0.8 +/- 0.39, and 0.6 +/- 0.09 nmol/kg, respectively), but higher doses had depressor effects in four of six rats. Vagal bradycardia, induced by electrical stimulation of the right cervical vagus nerve, was inhibited by NPY in the guinea pig and in the rat (ED35, 3.5 +/- 0.46 and 11.2 +/- 1.79 nmol/kg, respectively; p < 0.05) but not in the rabbit. In the guinea pig, the Y2-receptor-preferring fragment NPY(3-36) and the selective Y1-receptor antagonist H 409/22 were used to confirm that the increase in blood pressure was mediated solely through the Y1-receptor and the vagal inhibition solely through the Y2-receptor. Aside from the cardiovascular effects, NPY caused a decrease in the body temperature and inhibited vagal bronchoconstriction in this species. Considering that NPY may cause depressor effects in the rat and has no effect on the vagal bradycardia in the rabbit, the guinea pig is preferable to both these species for assessment of Y1- and Y2-receptor-active agents in vivo.

Neuropeptide Y-Y1 receptor antisense oligodeoxynucleotide increases the infarct volume after middle cerebral artery occlusion in rats

An antisense oligodeoxynucleotide selective for the rat neuropeptide Y1 receptor gene was given into the left lateral ventricle in the experimental group of rats, whereas a missense oligodeoxynucleotide or saline was given in the control groups. Some rats were decapitated at 1-2h after the last injection of the oligodeoxynucleotides to examine their effects on the Y1 receptor density in the insular cortex. When compared to the Y1 and Y2 binding density of the untreated rats, the antisense-treated rats had reduced Y1 binding in the insular cortex but the Y2 binding was unaffected; treatment with missense oligodeoxynucleotide had no effect. Other rats underwent a right-sided middle cerebral artery occlusion at 1-2h after the last injection of the oligodeoxynucleotides or saline to examine the effect on the infarction volume at three days following stroke. The antisense treatment resulted in a doubling of the mean infarction volume when compared to the missense or saline treatment.Thus, reducing the Y1 receptor density prior to middle cerebral artery occlusion is harmful. Neuropeptide Y may mediate neuroprotection against focal ischemia via the cortical Y1 receptor, since the immunoreactivity for neuropeptide Y has been shown to increase within the peri-infarct cortex after middle cerebral artery occlusion.

N-acylated alpha-(3-pyridylmethyl)-beta-aminotetralin antagoinists of the human neuropeptide Y Y5 receptor

Alpha-(3-Pyridylmethyl)-beta-aminotetralins were acylated with amino-piperidinyl and-pyrrolidinyl acetic acids, and with (aminomethyl)cyclohexanecarboxylic acid. Reaction with acyl chlorides, chloroformates, and isocyanates gave amides 8e, carbamates 9, and ureas 10, which bound to the Y5 receptor with nanomolar affinity. Congeners 11a and 11d containing a terminal benzimidazolone group were shown to be functional Y5 antagonists.

N-(sulfonamido)alkyl[tetrahydro-1H-benzo[e]indol-2-yl]amines: potent antagonists of human neuropeptide Y Y5 receptor

[3a,4,5,9b-Tetrahydro-1H-benzo[e]indol-2-yl]amines were prepared via reductive amination and concomitant cyclization of alpha-cyanomethyl-beta-aminotetralins. N-acylation with omega-sulfonamido-carboxylic acids and subsequent reduction afforded a series of N-(sulfonamido)alkyl[tetrahydro-1H-benzo[e]indol-2-yl]amines, which bound to the human neuropeptide Y Y5 receptor with nanomolar affinity.

Y receptor-mediated induction of CD63 transcripts, a tetraspanin determined to be necessary for differentiation of the intestinal epithelial cell line, hBRIE 380i cells

Peptide YY (PYY) and neuropeptide Y (NPY) are peptides that coordinate intestinal activities in response to luminal and neuronal signals. In this study, using the rat hybrid small intestinal epithelial cell line, hBRIE 380i cells, we demonstrated that PYY- and NPY-induced rearrangement of actin filaments may be in part through a Y1alpha and/or a nonneuronal Y2 receptor, which were cloned from both the intestinal mucosa and the hBRIE 380i cells. A number of PYY/NPY-responsive genes were also identified by subtractive hybridization of the hBRIE 380i cells in the presence or absence of a 6-h treatment with PYY. Several of these genes coded for proteins associated with the cell cytoskeleton or extracellular matrix. One of these proteins was the transmembrane-4 superfamily protein CD63, previously shown to associate with beta(1)-integrin and implicated in cell adhesion. CD63 immunoreactivity, using antibody to the extracellular domain, was highest in the differentiated cell clusters of the hBRIE 380i cells. The hBRIE 380i cells transfected with antisense CD63 cDNA lost these differentiated clusters. These studies suggest a new role for NPY and PYY in modulating differentiation through cytoskeletal associated proteins.

Transmitter release and uptake evoked by the amphibian skin alkaloid, pumiliotoxin-B (PTX-B), in the electrically stimulated mouse vas deferens preparation (MVD)

Upon electrical stimulation three transmitters are known to be released from the adrenergic nerve terminals of the isolated MVD preparation: two motor transmitters (noradrenaline (NA) and ATP) acting synergistically to provoke twitch contraction, and an inhibitory transmitter, the peptide NPY. The frog alkaloid pumiliotoxin-B (PTX-B) displayed two opposite effects on the electrically stimulated MVD: at low concentrations (0.1-0.3 microM) it caused twitch depression, at higher concentrations (0.5-2 microM) there was a potent twitch stimulation. Transmitters and/or receptors involved in the depressive effect could not be clearly identified, although interference with NPY is possible. On the other hand, the potent twitch stimulation caused by PTX-B may be due to exaggerated release of the same transmitters (NA and ATP) involved in twitch stimulation produced by electrical stimulation. Opening by PTX-B of the Na+ channels on the membrane of the adrenergic nerve terminals causes activation of the amine pump facilitating re-uptake of not only endogenous NA but also of exogenous catecholamines.