Effect of neuropeptide Y on behavior and on the time course of the brain noradrenalin level

Laboratory of General Physiology of Functional Systems, P. K. Anokhin Research Institute of Normal Physiology, Academy of Medical Sciences of the USSR, Moscow. Institute of Pathophysiology, Szeged Medical University, Hungary. (Presented by Academician of the Academy of Medical Sciences of the USSR I. P. Ashmarin). Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 108, No. 8, pp. 132–135, August, 1989.     

Release and vasoconstrictor effects of neuropeptide Y in relation to non-adrenergic sympathetic control of renal blood flow in the pig

The possible involvement of neuropeptide Y (NPY) in sympathetic control of renal blood flow was investigated in the pig in vivo. Exogenous NPY caused renal vasoconstriction with a threshold effect at an arterial plasma concentration of 164 pmol 6(-1). Stimulation of the renal nerves (0.59, 2 and 10 Hz) in control animals evoked rapid and frequency-dependent reduction in renal blood flow and overflow of NPY-like immunoreactivity (NPY-LI) and noradrenaline (NA) from the kidney, suggesting co-release from sympathetic nerves. Following the administration of the alpha- and beta-adrenoceptor antagonists phenoxybenzamine and propranolol, the vasoconstrictor response to exogenous NA was reduced by 98%, whereas that of NPY was unaltered. The response to nerve stimulation with 0.59 Hz was abolished, whereas relatively slowly developing reductions in renal blood flow by 7 and 28% were obtained upon stimulation with 2 and 10 Hz respectively. The nerve stimulation-evoked overflow of NA at 0.59 and 2 Hz, but not at 10 Hz and not that of NPY-LI, was enhanced after adrenoceptor blockade. Twenty-four hours after reserpine treatment (1 mg kg-1 i.v.) the contents of NPY-LI and NA in the renal cortex were reduced by 80 and 98% respectively. Sectioning of the renal nerves largely prevented the reserpine-induced depletion of NPY-LI, but not that of NA. Nerve stimulation of the denervated kidney with 2 and 10 Hz 24 h after reserpine treatment evoked slowly developing and long-lasting reductions in renal blood flow by 6 and 52% respectively. These responses were associated with overflow of NPY-LI, which was similar to and threefold higher than that observed in controls at 2 and 10 Hz respectively, while no detectable overflow of NA occurred. Repeated stimulation with 10 Hz resulted in a progressive fatigue of the vasoconstrictor response and the associated overflow of NPY-LI, giving a high correlation (r = 0.86, P less than 0.001) between the two parameters. It is concluded that NPY is a potent constrictor of the renal vascular bed. Furthermore, although NA is the likely transmitter mediating most of the responses to low to moderate nerve activation under control conditions, the data suggest that NPY may mediate the non-adrenergic reductions in renal blood flow evoked by high-frequency sympathetic nerve stimulation after reserpine treatment.     

Occurrence of neuropeptide Y (NPY)-like immunoreactivity in catecholamine neurons in the human medulla oblongata

We report here the coexistence of a neuropeptide and catecholamines in neurons of the human brain. Using indirect immunofluorescence histochemistry, combined with elution and restaining experiments, neurons in the medulla oblongata of man were demonstrated to contain both a neuropeptide Y-like peptide and the catecholamine synthesizing enzyme tyrosine hydroxylase.     

Time-dependent effects of ischaemia on neuropeptide Y mechanisms in pig renal vascular control in vivo

We have investigated the effects of ischaemia on neuropeptide Y (NPY) mechanisms involved in sympathetic vascular control of the pig kidney in vivo. Reperfusion after 2 h of renal ischaemia was associated with local overflow of noradrenaline (NA) but not of NPY-like immunoreactivity (-LI). Renal sympathetic nerve stimulation 10 min into reperfusion evoked markedly reduced vasoconstrictor effects and significantly less overflow of NA (reduced by 70% from the pre-ischaemic conditions), whereas NPY-LI overflow was unaltered. Renal vasoconstrictor responses to exogenous peptide YY (PYY), phenylephrine and angiotensin II were strongly attenuated after this ischaemic period, while vasoconstriction to α,β-methylene ATP was maintained to a larger extent. The renal vascular responses and NA overflow had become partially normalized within a 2 h recovery period. In contrast, the renal vasoconstrictor response and the overflow of NPY-LI upon sympathetic nerve stimulation were enhanced after 15 min of renal ischaemia. In parallel, the PYY-evoked renal vasoconstriction was selectively and markedly prolonged after the 15 min of ischaemia. In the presence of the NPY Y₁ receptor antagonist BIBP 3226, the augmented vascular response to nerve stimulation was significantly attenuated. We conclude that reperfusion after 2 h of renal ischaemia is associated with local overflow of NA, whereas the sympathetic nerve-evoked release of NA and the reactivity of the renal vasculature to vasoconstrictor stimuli are reversibly reduced. Furthermore, possibly due to an impaired local degradation, the role of neurogenically released NPY in renal sympathetic vasoconstriction is enhanced after short-term (15 min) ischaemia compared with control conditions.     

Galanin and neuropeptide Y in chromaffin granules from the guinea-pig

We have examined the subcellular distribution of galanin-like immunoreactivity, neuropeptide Y-like immunoreactivity and the catecholamines noradrenaline and adrenaline in the adrenal medulla from guinea-pigs. By differential centrifugation of the adrenal medulla homogenate the neuropeptides as well as the catecholamines sedimented in a 10000 g pellet. This pellet was resuspended and further examined in discontinuous and continuous density gradients. In the discontinuous gradient the catecholamines peaked in the heavy bottom fraction, assumed to contain chromaffin granules. Galanin-like immunoreactivity and neuropeptide Y-like immunoreactivity were also enriched in this fraction. However, both neuropeptides showed high levels of sedimentable material also in a fraction of intermediate density. In the continuous density gradient, the sum of sedimentable and soluble catecholamines showed peak values in two fractions corresponding to 1.07 and 1.47 m sucrose, respectively. The NA peak in the denser fraction was more pronounced than the corresponding A peak. Galanin-like immunoreactivity showed only one peak, in the fraction corresponding to 1.07 M sucrose. The data suggest that galanin-like immunoreactivity and neuropeptide Y-like immunoreactivity are partly stored with catecholamines in chromaffin granules. However, galanin-like immunoreactivity and neuropeptide Y-like immunoreactivity was also found in fractions lighter than those containing the bulk of the catecholamines.     

神经肽Y在癫痫发病机制中的作用

Neuropeptide Y (NPY) is a pancreatic polypeptide- related peptide, consisting of 36 amino acids. NPY is expressed in the nervous system widely and abundandy, mainly in the hippcampus, regulates the excitability of neurons through its receptors (Y1, Y2, Y5). In recent yeats the research progress indicated the changes induced by seizures in the level and distribution of NPY, its receptors subtypes and their respectire mRNAs in brain. The inhibitory action of NPY on glutamate- mediatedand in seizure phenomena, suggests that one of its roles in hippocampal physiology is to modulate neuronal excitability by regulating glutamate release.     

神经肽Y促血管生成的研究进展

神经肽Y（neuropeptide Y,NPY）是人体内含量最丰富的神经肽之一,在介绍NPY的生物学特性及受体基础上,本文阐述了释放的有活性的NPY与促血管生成相关受体结合呈浓度依赖性双峰性直接刺激血管生成,及通过上调促血管生成相关受体的表达、诱导其它促血管生长因子的表达及降低血管生成抑制因子的表达、动员骨髓间充质干细胞和内皮祖细胞等其它途径促进血管生成,为其在临床预防和治疗某些疾病提供依据。     

Reserpine-induced potentiation of the inhibitory action of neuropeptide Y on the rat vas deferens neurotransmission

The inhibitory action of neuropeptide Y (NPY) on the muscular activity of the prostatic end of the rat vas deferens elicited by transmural electrical stimulation was examined in control and in reserpinized rats. Pretreatment with 1 mg/kg reserpine for 48 h induced a 6-fold increase in NPY potency. Likewise, the potency of clonidine to inhibit the electrically induced muscular activity or noradrenaline to contract the ductus musculature was also potentiated. It is hypothesized that reserpine via a denervation super-sensitivity-like process increases the density of the NPY receptors. The functional significance of NPY in the motor activity of the vas deferens is discussed.     

Potentiation of the resetting effects of light on circadian rhythms of hamsters using serotonin and neuropeptide Y receptor antagonists

Circadian rhythms are entrained by light/dark cycles. In hamsters, the effects of light on circadian rhythms can be modulated by serotonergic input to the suprachiasmatic nucleus from the raphe nuclei and by neuropeptide Y containing afferents to the suprachiasmatic nucleus from the intergeniculate leaflet in the thalamus. In this study we measured effects of compounds acting on serotonergic 1A and neuropeptide Y Y5 receptors to determine if combined serotonergic-neuropeptide Y inhibition could synergistically potentiate effects of light on rhythms. We used mixed serotonergic agonist/antagonists BMY 7378 or NAN-190 as well as a neuropeptide Y Y5 antagonist CP-760,542. Both BMY 7378 and NAN-190 are thought to block serotonin release via acting as agonists at the 5-hydroxytryptamine 1A (5-HT1A) autoreceptors on cells in the raphe, and also block response of target cells by acting as antagonists at post-synaptic 5-HT1A receptors, for example, in the suprachiasmatic nuclei or the intergeniculate leaflet. Replicating prior work, we found that pretreatment with either drug alone increased the phase shift to light at circadian time 19. The combined effect of BMY 7378 and CP-760,542 given prior to light at circadian time 19 was to further potentiate the subsequent phase shift in wheel-running rhythms (the phase shift was 317% of controls; light alone: 1.35 h phase shift vs. BMY 7378, CP-760,542, and light: 4.27 h phase shift). Combined treatment with NAN-190 and CP-760,542 produced a light-induced phase shift 576% of controls (phase shift to light alone: 1.23 h vs. NAN-190, CP-760,542, and light: 7.1 h phase shift). These results suggest that the resetting effects of light on circadian rhythms can be greatly potentiated in hamsters by using pharmacological treatments that block both serotonergic and neuropeptide Y afferents to the suprachiasmatic nuclei.     

The homeostatic role of neuropeptide Y in immune function and its impact on mood and behaviour

Neuropeptide Y (NPY), one of the most abundant peptides in the nervous system, exerts its effects via five receptor types, termed Y1, Y2, Y4, Y5 and Y6. NPY's pleiotropic functions comprise the regulation of brain activity, mood, stress coping, ingestion, digestion, metabolism, vascular and immune function. Nerve‐derived NPY directly affects immune cells while NPY also acts as a paracrine and autocrine immune mediator, because immune cells themselves are capable of producing and releasing NPY. NPY is able to induce immune activation or suppression, depending on a myriad of factors such as the Y receptors activated and cell types involved. There is an intricate relationship between psychological stress, mood disorders and the immune system. While stress represents a risk factor for the development of mood disorders, it exhibits diverse actions on the immune system as well. Conversely, inflammation is regarded as an internal stressor and is increasingly recognized to contribute to the pathogenesis of mood and metabolic disorders. Intriguingly, the cerebral NPY system has been found to protect against distinct disturbances in response to immune challenge, attenuating the sickness response and preventing the development of depression. Thus, NPY plays an important homeostatic role in balancing disturbances of physiological systems caused by peripheral immune challenge. This implication is particularly evident in the brain in which NPY counteracts the negative impact of immune challenge on mood, emotional processing and stress resilience. NPY thus acts as a unique signalling molecule in the interaction of the immune system with the brain in health and disease.     

Co-localization of neuropeptide Y, vasoactive intestinal polypeptide and dynorphin in non-noradrenergic axons of the guinea pig uterine artery

Two major populations of perivascular axons containing immunoreactivity to neuropeptide Y (NPY) have been revealed in the main uterine artery of the guinea pig by immunohistochemical procedures which allow the simultaneous visualization of two antigens. One population contained immunoreactivity to dopamine-beta-hydroxylase (D beta H) and was presumably noradrenergic. The other main population of axons with NPY-like immunoreactivity (NPY-LI) did not have D beta H-like immunoreactivity (D beta H-LI) and was presumably non-noradrenergic. These non-noradrenergic axons also contained immunoreactivity to vasoactive intestinal polypeptide (VIP) and dynorphin (DYN). Indeed, nearly all axons with VIP-LI also contained NPY-LI and DYN-like immunoreactivity (DYN-LI). NPY constricted the uterine artery perfused in vitro, whilst VIP dilated uterine arteries preconstricted with noradrenaline or NPY. Thus, we have evidence for the coexistence of a vasoconstrictor peptide and a vasodilator peptide in the same non-noradrenergic perivascular axons, which also contain an opioid peptide, dynorphin.     

Electro-acupuncture as a peroperative analgesic method and its effects on implantation rate and neuropeptide Y concentrations in follicular fluid

BACKGROUND: In a previous study on the effect of electro-acupuncture (EA) in combination with a paracervical block (PCB) as an analgesic method during oocyte aspiration in IVF treatment, EA appeared to increase the pregnancy rate. This study was designed to test the hypothesis that EA as an analgesic during oocyte aspiration would result in: (i) a better IVF pregnancy rate than with alfentanil; (ii) peroperative analgesia that was as good as that produced by alfentanil; (iii) less postoperative abdominal pain, nausea and stress; and (iv) a reduction in the use of additional analgesics. Neuropeptide Y (NPY) concentrations in follicular fluid (FF) were analysed when possible. METHODS AND RESULTS: In this prospective, randomized, multicentre clinical trial, 286 women undergoing oocyte aspiration were randomly allocated to the EA group (EA plus a PCB) or to the alfentanil group (alfentanil plus a PCB). No significant differences were found between the EA and alfentanil groups in any of the IVF variables. NPY concentrations in FF were significantly higher in the EA group compared with the alfentanil group. No correlation between pregnancy rate and NPY concentrations was found in either analgesic group. Both EA plus a PCB and alfentanil plus a PCB induced adequate peroperative analgesia during oocyte aspiration evaluated using the visual analogue scale. After 2 h, the EA group reported significantly less abdominal pain, other pain, nausea and stress than the alfentanil group. In addition, the EA group received significantly lower amounts of additional alfentanil than the alfentanil group. CONCLUSION: EA does not improve pregnancy rate in the present clinical situation. The observation that NPY concentrations in FF were higher in the EA group may be important for human ovarian steroidogenesis. The analgesic effects produced by EA are as good as those produced by conventional analgesics, and the use of opiate analgesics with EA is lower than when conventional analgesics alone are used.     

Action and localization of neuropeptide Y in the human fallopian tube

Using indirect immunohistochemistry, neuropeptide Y-like immunoreactivity was found in nerve fibers around blood vessels and in the muscle layers of the human fallopian tube. Apart from a network of immunoreactive nerve fibers in connection with the luminary epithelium of the isthmus, the distribution resembled that of adrenergic, tyroxine hydroxylase immunoreactive, nerve fibers. Neuropeptide Y was found to have a dose-dependent inhibitory action on the adrenergic contractile response to field stimulation in the external longitudinal muscle layer of the isthmus. Furthermore, neuropeptide Y inhibited [3H]noradrenaline release from isthmic preparations during field stimulation, suggesting a prejunctional inhibitory action on adrenergic neurotransmission.     

Release of endothelin-like immunoreactivity in relation to neuropeptide Y and catecholamines during endotoxin shock and asphyxia in the pig

The changes in endothelin-like immunoreactivity in plasma during various provocations in the pig were investigated and related to those of neuropeptide Y, noradrenaline and adrenaline. Release as revealed by overflow was determined in the spleen, kidney and femoral vascular bed (skeletal muscle) simultaneously by collecting local venous and arterial blood samples. Under basal conditions there was no net release of endothelin-like immunoreactivity from any region but a net removal (negative overflow) over the kidney. Endotoxin administration (20 micrograms kg-1 h-1 for 4 h) increased arterial endothelin-like immunoreactivity, neuropeptide Y-like immunoreactivity, noradrenaline and adrenaline seven-, 27-, 100- and 166-fold respectively, as well as splenic and renal vascular resistance. An increased overflow of endothelin-like immunoreactivity, neuropeptide Y-like immunoreactivity and noradrenaline, indicating local release, was observed in the spleen during endotoxin administration. The arterial plasma endothelin-like immunoreactivity during endotoxaemia correlated significantly with the splenic and renal vasoconstriction (r = 0.75 and 0.68 respectively). Chromatographic characterization revealed that the main portions of arterial plasma endothelin-like immunoreactivity collected during endotoxaemia corresponded to synthetic endothelin-1 and big endothelin. A similar uptake (50-90%) and plasma half-life (1-2 min) of exogenous endothelin-1-like immunoreactivity was observed both under control conditions and after endotoxin, suggesting that elevated plasma endothelin-like immunoreactivity after endotoxin was the result not of reduced clearance but rather of enhanced release. Asphyxia for 2 min did not increase arterial endothelin-like immunoreactivity but evoked an increased overflow of endothelin-like immunoreactivity, neuropeptide Y-like immunoreactivity and noradrenaline as well as vasoconstriction in the spleen. Capsaicin induced a release of neuropeptide Y-like immunoreactivity and noradrenaline from both the spleen and the kidney and of adrenaline from the adrenal, but no detectable overflow of endothelin-like immunoreactivity from any of the vascular regions. Renal nerve stimulation, renal artery occlusion for 30 min, haemorrhagic shock, hypotension induced by nitroprusside infusion or serotonin did not cause any detectable increase in arterial plasma levels or local overflow of endothelin-like immunoreactivity. It is concluded that plasma levels of endothelin-like immunoreactivity are increased, suggesting release in the pig in response to endotoxin administration and asphyxia. The possible involvement of endothelin as a mediator of the peripheral vasoconstrictor responses during these situations remains to be further established.     

Neuropeptide Y and differential sympathetic control of splenic blood flow and capacitance function in the pig and dog

The roles of different mediators in the sympathetic regulation of the pig and dog spleens were investigated using a preparation with intact vascular perfusion in vivo. Sympathetic nerve stimulation caused overflow of neuropeptide Y-like immunoreactivity (NPY-LI) and noradrenaline (NA), arterial vasoconstriction, increase in venous blood flow and haematocrit. The dog spleen responded to single impulse stimulation, whereas more prolonged stimulation was required to elicit vascular responses in the pig spleen. Furthermore, the maximal splenic capacitance response was about 10 times larger in the dog than in the pig. After depletion of neuronal NA content by reserpine combined with preganglionic denervation, about 70% of the splenic arterial vasoconstrictor responses in the dog and pig still remained at 5 Hz stimulation. Fifty per cent of the capacitance response evoked by nerve stimulation still remained in the pig while in the dog spleen the capacitance response was virtually abolished after reserpine. The stimulation-evoked overflow of NPY-LI in pig spleen was increased several fold after reserpine treatment as compared to controls reaching levels in the venous effluent where exogenous NPY evokes vasoconstriction. In the dog spleen, overflow of NPY-LI was only observed after reserpine. Administration of NA caused arterial vasoconstriction with an initial increase in venous blood flow while NPY mainly reduced arterial blood flow. It is concluded that NA is involved in both the splenic arterial vasoconstriction and the capacitance responses while a non-adrenergic splenic vasoconstriction at least in the pig may be mediated by NPY.     

Coexistence of neuropeptide Y and somatostatin in rat and human cortical and rat hypothalamic neurons

The distribution and coexistence of neuropeptide Y (NPY) and somatostatin (SOM) were evaluated in rat and human cerebral cortex and in the rat hypothalamic arcuate nucleus (n) using double immunofluorescent staining in which primary antisera were raised in different species. The results of the study indicate extensive coexistence of NPY and SOM in both rat and human cortex but only occasional coexistence in the rat arcuate n.     

Immunohistochemical analysis of the early ontogeny of the neuropeptide Y system in rat brain

The distribution of neuropeptide Y in the developing rat brain was studied with immunocytochemistry, using the peroxidase-antiperoxidase method. Immunoreactive perikarya were first seen on embryonic day 13 and staining of fibres appeared from embryonic day 15 onwards: perikaryal staining was generally more intense prenatally than after birth. Areas rich in neuropeptide Y immunostaining included the monoaminergic regions of the brain stem from embryonic day 13 (especially the lateral reticular nucleus and the medullary reticular formation), the dorsal mesencephalon (with spots of immunoreactivity in the outer subventricular zone at embryonic days 13 or 14 and many cells and fibres in the inferior colliculus from embryonic days 16-20) and the olfactory tubercle/ventral striatum from embryonic day 15 until birth. The period of development of cortical neurones extended from embryonic day 19 until postnatal day 21. A hitherto unreported feature unique to neuropeptide Y was the presence in certain parts of the cerebral cortex of transient cells at the base of the cortical plate bearing radial processes which transverse its width. They were present from embryonic day 17 until postnatal day 4 and were maximally developed at embryonic days 20 or 21, contributing at this age a substantial fibre projection through the immature corpus callosum. The abundance of neuropeptide Y in the prenatal rat brain suggests it may play an important role in development.     

海洛因依赖对大鼠直肠神经肽Y表达的影响

目的探讨海洛因依赖期间大鼠直肠内神经肽Y（NPY）免疫反应阳性细胞的形态学改变。方法选取成年SD大鼠,分为海洛因依赖组、盐水对照组和正常对照组,皮下注射海洛因建立大鼠海洛因依赖模型,取直肠组织用免疫组织化学SABC法及图像分析法进行研究。结果与正常及盐水对照组比较,海洛因依赖组大鼠直肠NPY阳性细胞的细胞数均增多。图像分析显示海洛因依赖期间大鼠直肠内NPY阳性细胞的平均灰度值均低于正常及盐水对照组（P〈0.05）;以17 d时间组最低（P〈0.05）。结论海洛因依赖期间直肠NPY阳性细胞的平均灰度值发生变化,提示NPY合成和分泌增多。