Effects of neuropeptide Y deficiency on hypothalamic agouti-related protein expression and responsiveness to melanocortin analogues

Central administration of neuropeptide Y (NPY) potently induces feeding and its abundance in the hypothalamus increases when energy stores fall. Consequently, NPY is considered to be a physiological effector of feeding behavior. Surprisingly, NPY-deficient (NPY-/-) mice feed and grow normally with ad libitum access to food and manifest a normal hyperphagic response after fasting, suggesting that other feeding effectors may compensate for the lack of NPY. Agouti-related protein (AgRP), a melanocortin receptor antagonist, can also stimulate feeding behavior when administered centrally and is coexpressed in a majority of hypothalmamic NPY-ergic neurons, making AgRP a candidate compensatory factor. To test this possibility, we evaluated AgRP mRNA and protein expression, as well as responsiveness to centrally administered AgRP in NPY-/- mice. These studies demonstrate that hypothalamic AgRP mRNA and immunoreactivity are upregulated with fasting and that these increases are not affected by NPY deficiency. Interestingly, NPY-/- mice are hypersensitive to central administration of AgRP(83-132), yet exhibit a normal response to centrally administered MTII, a melanocortin receptor agonist. These data suggest that if AgRP compensates for the lack of NPY in NPY-/- mice, it is not at the level of AgRP synthesis and may instead involve alterations in the postsynaptic signaling efficacy of AgRP. Moreover, the effects of AgRP are not limited to its actions at the melanocortin-4 receptor (MC4R), because MC4R-deficient (MC4R-/-) mice manifest a significant response to centrally administered AgRP. These data imply that AgRP has additional targets in the hypothalamus.     

Differential regulation of neuropeptide Y mRNA expression in the arcuate nucleus and locus coeruleus by stress and antidepressants

In rats, circulating corticosterone and insulin are involved in regulation of the hypothalamic neuropeptide Y (NPY) system, which in turn, is involved in regulation of the hypothalamic-pituitary-adrenal (HPA) axis. Since the HPA axis and stress responsivity is altered in diseases such as depression, we investigated interactions between the effects of stress and antidepressant drug treatment on arcuate nucleus and locus coeruleus NPY mRNA expressions using in-situ hybridization histochemistry. After acute (2 h) and repeated immobilization (2 h daily, for 14 days), plasma concentrations of corticosterone increased, and those of insulin decreased. The expression of NPY mRNA was significantly increased in the arcuate nucleus, but was unchanged in the locus coeruleus following acute and repeated immobilization. Adrenalectomized rats with systemic corticosterone replacement (ADX+CORT), whose corticosterone concentration was maintained at approximately 50-100 ng/ml during repeated stress, showed a decrease in plasma insulin and an increase in arcuate nucleus NPY mRNA similar to that observed in sham rats, suggesting that changes in NPY mRNA levels are more closely tied to circulating insulin than to circulating corticosterone. In contrast, locus coeruleus NPY mRNA expressions in ADX+CORT rats were significantly higher than those in sham rats after repeated stress. Desmethylimipramine (DMI) treatment for 24 days did not affect basal plasma concentrations of corticosterone or insulin, or arcuate nucleus NPY mRNA expressions, but significantly decreased basal levels of locus coeruleus NPY mRNA compared to saline-treated rats. After repeated immobilization (2 h daily, for 4 days), DMI significantly reduced the stress-induced rise in locus coeruleus NPY mRNA levels, but potentiated the stress-induced rise in arcuate nucleus NPY mRNA expression. These results demonstrate that: (1) the increase in arcuate nucleus NPY mRNA expressions in stressed rats closely follows the decrease in plasma concentrations of insulin; (2) increases in NPY mRNA expressions occur in the absence of changes in plasma corticosterone; and (3) desipramine treatment potentiated the effect of stress on arcuate nucleus NPY mRNA expressions, but blocked the repeated stress-induced increase in locus coeruleus NPY mRNA expressions. Thus, NPY mRNA expression in the arcuate nucleus and the locus coeruleus is sensitive to the effects of stress and to the antidepressant drug desipramine, but the arcuate nucleus NPY system is regulated by different mechanisms than the locus coeruleus NPY system. The results provide further evidence for the importance of circulating insulin in the regulation of the arcuate nucleus NPY system.     

Resistance to diet-induced obesity is associated with increased proopiomelanocortin mRNA and decreased neuropeptide Y mRNA in the hypothalamus

Mechanisms mediating genetic susceptibility to diet-induced obesity have not been completely elucidated. Elevated hypothalamic neuropeptide Y (NPY) and decreased hypothalamic proopiomelanocortin (POMC) are thought to promote the development and maintenance of obesity. To assess the potential role of hypothalamic neuropeptide gene expression in diet-induced obesity, the present study examined effects of a high-fat diet on hypothalamic NPY and POMC mRNA in three strains of mice that differ in susceptibility to develop diet-induced obesity. C57BL/6J, CBA, and A/J mice were fed either normal rodent chow or a high-fat diet for 14 weeks after which hypothalamic gene expression was measured. On the high-fat diet, C57BL/6J mice gained the most weight, whereas A/J mice gained the least weight. On the high-fat diet, NPY mRNA significantly decreased as body weight increased in CBA and A/J mice, but not in C57BL/6J mice. In addition, POMC mRNA significantly increased as body weight increased in A/J mice, but not in CBA and C57BL/6J mice. Since decreased NPY mRNA and increased POMC mRNA would presumably attenuate weight gain, these results suggest that a high-fat diet produces compensatory changes in hypothalamic gene expression in mice resistant to diet-induced obesity but not in mice susceptible to diet-induced obesity.     

Metformin inhibits food intake and neuropeptide Y gene expression in the hypothalamus

Metformin may reduce food intake and body weight, but the anorexigenic effects of metformin are still poorly understood. In this study, Sprague-Dawley rats were administered a single intracere-broventricular dose of metformin and compound C, in a broader attempt to investigate the regula-tory effects of metformin on food intake and to explore the possible mechanism. Results showed that central administration of metformin significantly reduced food intake and body weight gain, par-ticularly after 4 hours. A reduction of neuropeptide Y expression and induction of AMP-activated protein kinase phosphorylation in the hypothalamus were also observed 4 hours after metformin administration, which could be reversed by compound C, a commonly-used antagonist of AMP-activated protein kinase. Furthermore, metformin also improved lipid metabolism by reducing plasma low-density lipoprotein. Our findings suggest that under normal physiological conditions, central regulation of appetite by metformin is related to a decrease in neuropeptide Y gene expres-sion, and that the activation of AMP-activated protein kinase may simply be a response to the anorexigenic effect of metformin.     

大鼠脊髓背角浅层神经元中神经肽Y Y1受体与生长抑素共存

用间接免疫荧光双标记方法,研究大鼠脊髓Ⅱ层神经元中神经肽Ｙ Ｙ１受体与生长抑素共存关系。结果显示在Ⅱ层深部许多神经元含Ｙ１受体－免疫反应性物质,只观察到少量的生长抑素免疫反应阳性神经元胞体,其中个别Ｙ１受体阳性神经元也含生长抑素免疫反应性物质;在局部使用秋水仙素后,大多数Ｙ１受体免疫反应阳性神经元含有生长抑素免疫反应性物质。推论脊髓背角Ⅱ层神经元中的Ｙ１受体可能与生长抑素在脊髓水平的功能有关。     

Characterization of neuropeptide Y2 receptor protein expression in the mouse brain. I. Distribution in cell bodies and nerve terminals

Neuropeptide Y (NPY), a 36-amino-acid peptide, mediates biological effects by activating Y1, Y2, Y5, and y6 receptors. NPY neurons innervate many brain regions, including the hypothalamus, where NPY is involved in regulation of a broad range of homeostatic functions. We examined, by immunohistochemistry with tyramide signal amplification, the expression of the NPY Y2 receptor (Y2R) in the mouse brain with a newly developed rabbit polyclonal antibody. Y2R immunoreactivity was specific with its absence in Y2R knockout (KO) mice and in adjacent sections following preadsorption with the immunogenic peptide (10(-5) M). Y2R-positive processes were located in many brain regions, including the olfactory bulb, some cortical areas, septum, basal forebrain, nucleus accumbens, amygdala, hippocampus, hypothalamus, substantia nigra compacta, locus coeruleus, and solitary tract nucleus. However, colchicine treatment was needed to detect Y2R-like immunoreactivity in cell bodies in many, but not all, areas. The densest distributions of cell bodies were located in the septum basal forebrain, including the bed nucleus, and amygdala, with lower density in the anterior olfactory nucleus, nucleus accumbens, caudal striatum, CA1, CA2, and CA3 hippocampal fields, preoptic nuclei lateral hypothalamus, and A13 DA cells. The widespread distribution of Y2R-positive cell bodies and fibers suggests that NPY signaling through the Y2R is common in the mouse brain. Localization of the Y2R suggests that it is mostly presynaptic, a view supported by its frequent absence in cell bodies in the normal mouse and its dramatic increase in cell bodies of colchicine-treated mice.     

Gene expression of neuropeptide Y in the nucleus of the solitary tract is activated in rats under restricted daily feeding but not under 48-h food deprivation

The two neuropeptide Y (NPY) systems innervating the hypothalamic paraventrivular nucleus were examined regarding their roles in the prefeeding corticosterone peak developed under restricted daily feeding (RF). Protein and mRNA levels of NPY were measured in the arcuate nucleus (ARC) and the nucleus of the solitary tract (NST) in rats under 48-h food deprivation (48-hFD), RF, and 72-h food deprivation imposed after RF (post-RF 72-hFD) with 7 days of ad libitum feeding in between. NPY protein and mRNA levels in the ARC significantly increased with 48-hFD and decreased with re-feeding, whereas those in the NST were not changed by 48-hFD. When rats had RF imposed with free access to food from 10.00 to 12.00 h (lights on from 06.00 to 18.00 h) for 3 weeks, NPY concentrations in the ARC increased at 10.00 h, just prior to the daily meal, but those in the NST did not change significantly throughout the period examined. On the other hand, NPY mRNA levels in both the ARC and NST increased before the meal supply and remained high for 4 h after feeding. Under post-RF 72-hFD, the prefeeding peak of NPY mRNA was detected in the NST, but NPY mRNA levels in the ARC were continuously high throughout the 24-h period. These findings indicate that the NPY neurons from the NST are specifically activated by RF, whereas those from the ARC are generally stimulated by an increased food demand.     

Perinatal developmental changes in expression of the neuropeptide genes preoptic regulatory factor-1 and factor-2, neuropeptide Y and GnRH in rat hypothalamus

The preoptic regulatory factor genes, PORF-1 and PORF-2, are expressed in the rat brain in a regional-, age- and gender-dependent fashion. They are also expressed in the testis, where PORF-2 mRNA localizes to dividing germ cells while PORF-1 mRNA is associated with newly differentiated sperm. This suggests that PORF-1 and PORF–2 may play distinct roles in cell growth and differentiation. Moreover, the two preoptic regulatory factors are also highly expressed in the immature and mature rat hypothalamus, and their expression is modulated by gonadal hormones. Therefore, in the present study we investigated the expression of these two factors in neuroendocrine regions of the developing rat brain by addressing the following questions. First, are PORF-1 and PORF–2 mRNAs expressed during perinatal development in the preoptic area-anterior hypothalamus (POA-AH) and medial basal hypothalamus (MBH), and how do their levels vary? Second, are there gender differences in their expression? We also compared expression of the PORF mRNAs with those of neuropeptide Y (NPY) and gonadotropin-releasing hormone (GnRH), which play critical neuroendocrine roles, in these brain regions. PORF-1, PORF-2, and NPY mRNAs in the POA-AH and MBH, and GnRH mRNA in the POA-AH, were quantified by RNase protection assay at embryonic day (E) 18–19, and postnatal days (P) 0, 5, 10 and 15 in male and female rats. The results show that the four neuropeptide genes are regulated differentially during the perinatal-prepubertal period. PORF-1 mRNA shows age-related increases in expression from E18–E19 to P15 in POA-AH and MBH, without significant gender differences. In contrast, PORF-2 mRNA shows both age and gender differences in expression in these brain regions, with decreases occurring during the same time period in development. NPY mRNA increases similarly in males and females with age in POA-AH and MBH during this period. GnRH mRNA does not change during this period. Taken together with previous studies, the results suggest possible roles for PORF-1 and NPY in the pubertal process, since their expression is maximal from the prepubertal to the early pubertal period. The observation of highest levels of expression of PORF-2 in embryonic neuroendocrine tissues suggests a possible involvement of this neuropeptide in prenatal/neonatal developmental events.     

Influence of Ganoderma lucidum spores on the levels of neuropeptide Y and somatostatin in brains of seizure rats

BACKGROUND: Previous research has revealed that somatostatin can induce epilepsy, and that the levels of neuropeptide Y may increase and become more active in brain areas with epileptic seizures.OBJECTIVE: To observe the effect of Ganoderma lucidum spore powder on the neuropeptide Y and somatostatin content in the cerebral cortex and hippocampal regions of seizure rats induced by pentylenetetrazol (PTZ). Furthermore, to verify any effect of Ganoderma lucidum spore powder on inhibition of epileptic seizures.DESIGN, TIME AND SETTING: A randomized group animal study was performed in August 2007 in the School of Basic Medical Sciences, Jiamusi University (Jiamusi, Heilongjiang, China).MATERIALS: Thirty healthy, male, Wistar rats, aged 12 weeks and weighing 180-220g, were taken as the experimental animals. PTZ (Sigma Company, United States) was used to induce epilepsy. Ganoderma lucidum spores (Leyss, ex Fr variety) were purchased from Jiamusi City Wild Growing Case of the Ganoderma Lucidum (China). Rabbit anti-somatostatin antibodies and secondary antibodies were purchased from Wuhan Boster Company (China). Neuropeptide Y radioimmunoassay kit was purchased from Beijing Furui Biotechnology Company (China).METHODS: Thirty rats were randomly divided into three groups: a control group, an epilepsy model group and a Ganoderma lucidum spore-treated group. Each group contained 10 animals. Rats in the epilepsy model group were treated with intraperitoneal injections of PTZ and gastric perfusion of physiologic saline, In the Ganoderma lucidum spore-treated group, intraperitoneal injection of PTZ and gastric perfusion of Ganoderma lucidum spore powder were administered. The blank control group was only administered with the physiological saline by intraperitoneal injection and gastric perfusion.MAIN OUTCOME MEASURES: Immunohistochemical staining and radioimmunoassay methods were used to observe the changes of somatostatin and neuropeptide Y content in brain tissue of epileptic rats, as well as the morphology of neurons.RESULTS: All 30 rats were involved in the result analysis, without any loss. The number of somatostatin immunoreacted positive cells in the cerebral cortex and hippocampus was significantly increased in the epilepsy model group compared to the blank control group (P<0.01). The number of somatostatin immunoreacted positive cells in cerebral cortex and hippocampus was significantly decreased in the Ganoderma lucidum spore-treated group compared to the epilepsy model group (P<0.01). The contents of neuropeptide Y in cerebral cortex and hippocampus were significantly increased in the epilepsy model group compared to the blank control group (P<0.01). The contents of neuropeptide Y in the cerebral cortex and hippocampus were significantly decreased in the Ganoderma lucidum spore-treated group compared to the epilepsy model group (P<0.05). The epilepsy seizures in the Ganoderma lucidum spore-treated group were obviously reduced compared to the epilepsy model group.CONCLUSION: Ganoderma lucidum spore powder was able to reduce the somatostatin and neuropeptide Y content in the cerebral cortex and hippocampus effectively, so as to achieve an anti-epileptic function and protect neurons from being damaged.     

Influence of Ganoderma lucidum spores on the levels of neuropeptide Y and somatostatin in brains of seizure rats*★

BACKGROUND： Previous research has revealed that somatostatin can induce epilepsy, and that the levels of neuropeptide Y may increase and become more active in brain areas with epileptic seizures. OBJECTIVE： To observe the effect of Ganoderma luciclum spore powder on the neuropeptide Y and somatostatin content in the cerebral cortex and hippocampal regions of seizure rats induced by pentylenetetrazol （PTZ）. Furthermore, to verify any effect of Ganoderma lucidum spore powder on inhibition of epileptic seizures. DESIGN, TIME AND SETTING： A randomized group animal study was performed in August 2007 in the School of Basic Medical Sciences, Jiamusi University （Jiamusi, Heilongjiang, China）. MATERIALS： Thirty healthy, male, Wistar rats, aged 12 weeks and weighing 180-220 g, were taken as the experimental animals. PTZ （Sigma Company, United States） was used to induce epilepsy. Ganoderma lucidum spores （Leyss, ex Fr variety） were purchased from Jiamusi City Wild Growing Case of the Ganoderma Lucidum （China）. Rabbit anti-somatostatin antibodies and secondary antibodies were purchased from Wuhan Boster Company （China）. Neuropeptide Y radioimmunoassay kit was purchased from Beijing Furui Biotechnology Company （China）. METHODS： Thirty rats were randomly divided into three groups： a control group, an epilepsy model group and a Ganoderma lucidum spore-treated group. Each group contained 10 animals. Rats in the epilepsy model group were treated with intraperitoneal injections of PTZ and gastric perfusion of physiologic saline. In the Ganoderma lucidum spore-treated group, intraperitoneal injection of PTZ and gastric perfusion of Ganoderma lucidum spore powder were administered. The blank control group was only administered with the physiological saline by intraperitoneal injection and gastric perfusion. MAIN OUTCOME MEASURES： Immunohistochemical staining and radioimmunoassay methods were used to observe the changes of somatostatin and neuropeptide Y content in brain tissue of epileptic r     

Effect of intracerebroventricular administration of the octadecaneuropeptide on the expression of pro-opiomelanocortin,neuropeptide Y and corticotropin-releasing hormone mRNAs in rat hypothalamus

Intracerebroventricular (i.c.v.) administration of the octadecaneuropeptide (diazepam-binding inhibitor [33-50]; ODN) exerts a potent anorexigenic effect in the rat. We studied the effect of ODN on three neuropeptides involved in feeding behaviour: the orexigenic peptide neuropeptide Y (NPY) and two anorexigenic peptides, corticotropin-releasing hormone (CRH) and the pro-opiomelanocortin (POMC)-derived peptide alpha-melanocyte-stimulating hormone. The effect of i.c.v. administration of ODN (0.1 microg/kg and 1 microg/kg) on mRNA expression of the peptides in male rat hypothalamus was evaluated by semiquantitative in situ hybridization. In the arcuate nucleus, NPY-expressing neurones were mostly found in the inner zone in close proximity of the third ventricle. ODN at the dose of 0.1 microg/kg induced a significant decrease of 17.4% in NPY mRNA expression, while the depressing effect was more marked (31.4%) with the highest dose of ODN (1 microg/kg). POMC-expressing neurones were more laterally located in the arcuate nucleus. Administration of ODN at 0.1 microg/kg and 1 microg/kg doses induced increases of 33.5% and 27.4% in POMC mRNA expression, respectively. Labelling obtained with the CRH cRNA probe was essentially distributed throughout the medial parvocellular area of the hypothalamic paraventricular nucleus. ODN, at doses of 0.1 and 1 microg/kg, resulted in 17.8% and 32.8% decreases in CRH mRNA expression, respectively. The present data suggest that ODN might exert its anorexigenic effect by increasing mRNA expression of POMC and decreasing mRNA expression of NPY in the arcuate nucleus.     

Characterization of NPY Y2 receptor protein expression in the mouse brain. II. Coexistence with NPY, the Y1 receptor, and other neurotransmitter-related molecules

Neuropeptide Y (NPY) is widely expressed in the brain and its biological effects are mediated through a variety of receptors. We examined, using immunohistochemistry, expression of the Y2 receptor (R) protein in the adult mouse brain and its association with NPY and the Y1R, as well as a range of additional neurotransmitters and signaling-related molecules, which previously have not been defined. Our main focus was on the hippocampal formation (HiFo), amygdaloid complex, and hypothalamus, considering the known functions of NPY and the wide expression of NPY, Y1R, and Y2R in these regions. Y2R-like immunoreactivity (-LI) was distributed in nerve fibers/terminal endings throughout the brain axis, without apparent colocalization with NPY or the Y1R. Occasional coexistence between NPY- and Y1R-LI was found in the HiFo. Following colchicine treatment, Y2R-LI accumulated in cell bodies that coexpressed γ-aminobutyric acid (GABA) in a population of cells in the amygdaloid complex and lateral septal nucleus, but not in the HiFo. Instead, Y2R-positive nerve terminals appeared to surround GABA-immunoreactive (ir) cells in the HiFo and other neuronal populations, e.g., NPY-ir cells in HiFo and tyrosine hydroxylase-ir cells in the hypothalamus. In the HiFo, Y2R-ir mossy fibers coexpressed GABA, glutamic acid decarboxylase 67 and calbindin, and Y2R-LI was found in the same fibers that contained the presynaptic metabotropic glutamate receptor 2, but not together with any of the three vesicular glutamate transporters. Our findings provide further support that Y2R is mostly presynaptic, and that Y2Rs thus have a modulatory role in mediating presynaptic neurotransmitter release.     

The distribution and origin of a novel brain peptide, neuropeptide Y, in the spinal cord of several mammals

The distribution of neuropeptide Y [NPY]-immunoreactive material was examined in the spinal cord and dorsal root ganglia of rat, guinea-pig, cat, marmoset, and horse. Considerable concentrations of NPY and similar distribution patterns of immunoreactive nerve fibres were found in the spinal cord of all species investigated. The dorsal root ganglia of the cat and the horse contained numerous immunoreactive nerve fibres, but in these species, as in the other three studied [rat, guinea-pig, marmoset], no positively stained cell bodies were found. Neuropeptide Y-immunoreactive nerves were observed at all levels of the spinal cord, being most concentrated in the dorsal horn. In the rat, guinea-pig, and marmoset, there was a marked increase of NPY-immunoreactive fibres in the lumbosacral regions of the spinal cord, and this was reflected by a considerable increase of extractable NPY. Estimations of NPY-immunoreactive material in the various regions of the rat spinal cord were as follows: cervical, 13.8 +/- 1.0; thoracic, 21.1 +/- 2.5; lumbar, 16.3 +/- 2.9; sacral, 92.4 +/- 8.5 pmol/gm wet weight of tissue +/- SEM. In the ventral portion of the guinea-pig spinal cord they were as follows: cervical, 7.1 +/- 1.2; thoracic, 8.2 +/- 3.6; lumbar, 22.6 +/- 7.0; sacral, 36.7 +/- 9.5 pmol/gm wet weight of tissue +/- SEM. Analysis of spinal cord extracts by reverse phase high performance liquid chromatography [HPLC] demonstrated that NPY-immunoreactive material elutes in the position of pure NPY standard. No changes in the concentration and distribution of the NPY-like material in the rat spinal cord were observed following a variety of surgical and pharmacological manipulations, including cervical rhizotomy, sciatic nerve section and ligation, and local application of capsaicin [50 mM] to one sciatic nerve. It is therefore suggested that most of the NPY-immunoreactive material in the spinal cord is derived either from intrinsic nerve cell bodies or from supraspinal tracts.     

Reduced expression of IA channels is associated with postischemic seizures in hyperglycemic rats

Poststroke seizures are considered to be the major cause of epilepsy in the elderly. The mechanisms of poststroke seizures remain unclear. A history of diabetes mellitus has been identified as an independent predictor of acute poststroke seizures in stroke patients. The present study sought to reveal the mechanisms for the development of postischemic seizures under hyperglycemic conditions. Transient forebrain ischemia was produced in adult Wistar rats by using the four‐vessel occlusion method. At the normal blood glucose level, seizures occurred in ～50% of rats after 25 min of ischemia. However, in rats with hyperglycemia, the incidence rate of postischemic seizures was significantly increased to 100%. The occurrence of postischemic seizures was not correlated with the severity of brain damage in hyperglycemic rats. Mannitol, an osmotic diuretic agent, could neither prevent postischemic seizures nor alleviate the exacerbated brain damage in the presence of hyperglycemia. K⁺ channels play a critical role in controlling neuronal excitability. The expression of A‐type K⁺ channel subunit Kv4.2 in the hippocampus and the cortex was significantly reduced in hyperglycemic rats with seizures compared with those without seizures. These results suggest that the reduction of Kv4.2 expression could contribute to the development of postischemic seizures in hyperglycemia. © 2014 Wiley Periodicals, Inc.     

Nicotine administration decreases neuropeptide Y expression and increases leptin receptor expression in the hypothalamus of food-deprived rats

The effects of nicotine on the expressions of neuropeptide Y (NPY) and leptin receptor in the rat hypothalamus were investigated via immunohistochemistry. The results show that NPY expression is not affected in the arcuate nucleus (ARN) and is increased only slightly in the paraventricular nucleus (PVN) by nicotine administration under normal (i.e. fed) conditions and that leptin receptor expression is decreased slightly in the ARN and not affected in the PVN following nicotine treatment under the same conditions. Food deprivation enhanced NPY and suppressed leptin receptor expression in the ARN and PVN of the hypothalamus. Nicotine administration resulted in decreased NPY and increased leptin receptor levels.     

Effect of neuropeptide Y on white matter demyelination and serum interleukin-4 and gamma-interferon levels in the guinea pig with experimental allergic encephalomyelitis★

BACKGROUND： Neuropeptide Y （NPY） may influence differentiation of Th cells immunological pathology of experimental allergic encephalomyelitis （EAE） is differentiation of Th cells It is assumed that the related to abnormal OBJECTIVE： To investigate the effect of NPY on white matter demyelination, the serum levels interleukin-4 （IL-4） and gamma-interferon （IFN-γ ）, as well as EAE pathogenesis in an EAE guinea pig model following NPY injection into the lateral cerebral ventricle. DESIGN, TIME AND SETTING： A randomized controlled animal study, which was performed in the Infection Immunity Animal Laboratory, Affiliated Hospital of Luzhou Medical College, China, from October 2005 to April 2006. MATERIALS： Thirty healthy female guinea pigs of 8-12 weeks of age, and 10 healthy female rats of three months of age were used. NPY was provided by Sigma Company, USA. NPY kit was provided by Beijing Huaying Biotechnology Institute, China. METHODS： Thirty guinea pigs were randomly divided into three groups： normal control group, EAE model group, and NPY intervention group （n =10 per group）. Normal control group and EAE model group： Saline （10μ L, once） was injected into the lateral cerebral ventricle. After one week, the same volume of Freund＇s adjuvant complete was either injected subcutaneously into two post-palms or EAE was modeled. NPY intervention group： EAE was modeled after one week and NPY was injected （10 μ L of 6 nmol NPY, once） into the lateral cerebral ventricle. Myelin basic protein （MBP） antigen made from rat spinal cord homogenate and Freund＇s adjuvant complete were injected subcutaneously into both post-palms （0.2 mL per palm） to establish the EAE model. MAIN OUTCOME MEASURES： White matter demyelination of the cerebrum, cerebellum, brain stem, and spinal cord were observed by light microscopy after HE staining. Levels of serum IFN-γ and IL-4 were detected by the double antibody sandwich ABC-ELISA technique. NPY content was detected by radioimmunoassay.     

Effect of neuropeptide Y on white matter demyelination and serum interleukin-4 and gamma-interferon levels in the guinea pig with experimental allergic encephalomyelitis

BACKGROUND: Neuropeptide Y (NPY) may influence differentiation of Th cells. It is assumed that the immunological pathology of experimental allergic encephalomyelitis (EAE) is related to abnormal differentiation of Th cellsOBJECTIVE: To investigate the effect of NPY on white matter demyelination, the serum levels interleukin-4 (IL-4) and gamma-interferon (IFN-γ), as well as EAE pathogenesis in an EAE guinea pig model following NPY injection into the lateral cerebral ventricle.DESIGN, TIME AND SETTING: A randomized controlled animal study, which was performed in the Infection Immunity Animal Laboratory, Affiliated Hospital of Luzhou Medical College, China, from October 2005 to April 2006.MATERIALS: Thirty healthy female guinea pigs of 8-12 weeks of age, and 10 healthy female rats of three months of age were used. NPY was provided by Sigma Company, USA. NPY kit was provided by Beijing Huaying Biotechnology Institute, China.METHODS: Thirty guinea pigs were randomly divided into three groups: normal control group, EAE model group, and NPY intervention group (n=10 per group). Normal control group and EAE model group: Saline (10μL, once) was injected into the lateral cerebral ventricle. After one week, the same volume of Freund's adjuvant complete was either injected subcutaneously into two post-palms or EAE was modeled. NPY intervention group: EAE was modeled after one week and NPY was injected (10μL of 6nmol NPY, once) into the lateral cerebral ventricle. Myelin basic protein (MBP) antigen made from rat spinal cord homogenate and Freund's adjuvant complete were injected subcutaneously into both post-palms (0.2mL per palm) to establish the EAE model.MAIN OUTCOME MEASURES: White matter demyelination of the cerebrum, cerebellum, brain stem, and spinal cord were observed by light microscopy after HE staining. Levels of serum IFN-γ and IL-4 were detected by the double antibody sandwich ABC-ELISA technique. NPY content was detected by radioimmunoassay.RESULTS: Pathological alterations in the NPY intervention groups were reduced compared to those in the EAE model group, suggesting a reduction and remission of white matter demyelination with NPY treatment. When compared to the model group, the serum IL-4 level was increased in the NPY intervention group during the high-frequent EAE stage (P<0.01), but the serum IFN-γ level was decreased (P<0.01). Furthermore, the EAE latency was prolonged (P<0.01), the neurological scores were decreased in the high-frequent EAE stage (P<0.01), and the death rate was decreased (P<0.05). NPY content and the serum IL-4 level at the peak stage were positively correlated with those in the latent phase (r=0.863-0.900, P<0.01), but negatively correlated with neurological scores at the peak stage (r=-0.068 to -0.863, P<0.05-0.01). The IFN-γ level at the peak stage was negatively correlated to that in the latent phase (r=-0.683-0.650, P<0.05), but positively correlated to neurological scores at the peak stage (r=0.975,0.845, P<0.05).CONCLUSION: NPY injection into the lateral cerebral ventricle can promote the secretion of IL-4, inhibit the production of IFN-γ, relieve white matter demyelination, and inhibit EAE attack in an experimental model of EAE.