下丘脑室旁核胃动素对消化功能影响的研究

目的：研究下丘脑室旁核注入胃动素及其拮抗剂对大鼠消化功能和体重增长的研究。方法：将剂量为0.005-5nmol的motilin和GM109注入大鼠下丘脑室旁核,1小时后可观察到大鼠摄食量显著增加并持续到两小时后。进食量的计算是通过预先称量好的鼠粮和应用药物20分钟、1小时、两小时后剩余数量比较而得出。实验持续一周。将实验组和对照组的进食量和体重进行比较。结果：室旁核注入胃动素5nmol的实验组和合并应用GM1090.005nmol的实验组在应用药物后1小时和2小时,可观察到摄食量显著增加（p〈0.01）,一周后体重也增加（p〉0.05）,然而摄食量的增加有显著性差异,体重的增加并无显著性差异。其他实验组也没有观察到显著性差异。结论：胃动素有调节消化运动,促进胃肠排空,促进食欲的作用。可能由于胃肠排空是频繁的,没有充裕的时间消化吸收,从而体重增加无显著性差异。     

下丘脑室旁核胃动素对胃运动影响的探讨

目的 :研究下丘脑室旁核 (paraventricularnucleus,PVN)胃动素对胃运动调节的参与作用及机制。 方法 :应用免疫组织化学的方法检测室旁核内胃动素神经元的表达情况及室旁核与延髓迷走复合体 (dorsalvagalcomplex ,DVC)间的神经联系 ,应用室旁核内微量注入胃动素的方法观察清醒大鼠胃运动的变化。结果 :①下丘脑室旁核有胃动素免疫阳性细胞 ,在饥饿组和十二指肠灌酸组 ,阳性细胞数有明显增加 (P <0 .0 1)。②迷走背核注入辣根过氧化物酶 (horseradishperoxidase ,HRP) ,在室旁核发现HRP标记细胞 ,证实室旁核与DVC间的纤维联系。③清醒大鼠室旁核内微量注射胃动素可使胃运动的幅度和频率明显增加 (P <0 .0 5 ) ,切断双侧膈下迷走神经后 ,胃动素对胃运动的作用消失。结论 :下丘脑室旁核内胃动素可增强胃运动 ,其作用可能是通过下丘脑 延髓迷走复合体 迷走神经实现的     

中枢注射Nesfatin-1与Exendin(9-39)对大鼠摄食和胃肠动力调节的影响

目的:探讨下丘脑室旁核注射GLP-1R拮抗剂Exendin(9-39)对Nesfatin-1所致大鼠摄食和胃肠动力改变的影响及作用机制。方法:选择40只雄性Wistar大鼠,随机分成正常对照组(NC组)、Nesfatin-1组(NS组)、Exendin(9-39)组(ES组)、Nesfatin-1联合Exendin(9-39)组(NE组)。采用下丘脑室旁核(PVN)埋置套管并分别给予以上药物干预,干预前和干预后的12小时、24小时记录和比较各组大鼠的摄食、饮水及体重变化。2天后,采用甲基纤维素-酚红溶液灌胃法测各组大鼠胃排空率,实时荧光定量法(RT-PCR)检测下丘脑及胃组织GLP-1Rm RNA的表达。结果:与基础摄食量比较,NS组大鼠给药后12 h、24 h的摄食量减少(P0.05),NE组大鼠给药后12 h、24 h的摄食量减少(P0.05),但较NS组增加(P0.05);与基础饮水量比较,NS组、NE组给药后12 h饮水量减少(P0.05);与基础体重比较,NS组大鼠给药后12 h、24 h的体重降低(P0.05),NE组大鼠给药后12 h的体重降低(P0.05),但较NS组增加(P0.05);NS组大鼠给药后胃排空率较NC、NE组大鼠显著下降(P0.05),NS组大鼠下丘脑GLP-1Rm RNA的表达量较NC组增加(P0.05)。结论:中枢给予GLP-1R拮抗剂能减弱Nesfatin-1引起的摄食抑制、胃排空延迟及体重下降效应,Nesfatin-1可能通过与GLP-1的协同作用参与摄食及胃肠动力的调节。     

下丘脑室旁核orexin-A对大鼠摄食和胃动力影响及调控机制

目的:探讨下丘脑室旁核orexin-A对大鼠摄食和胃动力影响及调控机制。方法:采用免疫组化观察下丘脑室旁核(paraventricular nucleus,PVN)orexin受体表达情况;PVN注射orexin-A观察大鼠摄食、胃运动、胃酸分泌和胃排空的改变。结果:免疫组化实验显示大鼠PVN中存在orexin受体免疫阳性细胞。PVN注射orexin-A后,大鼠前三小时摄食增加,6 h和24 h摄食无显著改变。PVN微量注射orexin-A后,大鼠胃运动幅度和频率增加、胃排空增快并且胃酸分泌增多。[D-Lys-3]-GHRP-6可部分阻断orexin-A对摄食、胃运动、胃排空和胃酸分泌的促进作用,SB334867可完全阻断orexin-A对胃运动、胃排空和胃酸分泌的促进作用。结论:下丘脑室旁核orexin-A可能通过生长激素促泌素GHSR受体信号通路调控大鼠摄食及胃功能。     

嗅觉与摄食行为的相互调节及其神经机制

嗅觉与摄食相互关联和相互调节。在摄食过程中,体内的代谢信号及食物刺激产生的进食信号首先被下丘脑的弓状核及脑干的孤束核感受到,进一步投射到下丘脑室旁核,室旁核再将信号传递到与摄食相关的其他脑区,调控摄食行为。在此过程中,嗅觉信号可以通过嗅球及嗅皮层投射到下丘脑,调节摄食行为。与此同时,摄食过程中产生的胃肠激素(促生长激素释放素、胰岛素、瘦素等)和体内的一些神经递质(乙酰胆碱,去甲肾上腺素、五羟色胺、内源性大麻素等)又作用于嗅觉系统,对嗅觉功能进行调节,反过来影响摄食本身。本综述从神经调节、激素调节等方面总结了近年嗅觉与摄食之间的相互作用及其内在机制的研究进展。     

一次性运动对肥胖大鼠NPY蛋白及其基因表达的影响

目的通过观察一次性运动对肥胖大鼠摄食量、血清学指标、血浆和下丘脑NPY蛋白及其基因表达的影响，探讨运动影响摄食量和体重的分子生物学机制。方法肥胖建模成功大鼠分为对照、即刻、1h、3h、12h和24h等6组，分别在一次性跑台运动后不同时间段观察大鼠进食量并测试相关指标。结果一次性运动后肥胖大鼠摄食量明显下降，血糖和血脂等在运动后即刻没有明显变化，在运动后的恢复期开始明显下降，恢复后期才逐渐恢复到正常水平。血浆NPY水平显著下降，下丘脑NPY水平明显上升，而下丘脑NPY基因表达变化不明显。结论肥胖大鼠运动后摄食量下降；下丘脑NPY分泌增加而基因表达没有明显增加；下丘脑NPY蛋白增加可以促进机体运动后摄食，防止能量的进一步消耗，有利于运动后的能量恢复。     

神经肽Y和胰多肽可刺激大鼠摄食

某些胃肠激素、胰腺激素以及脑内的激素可调制动物的摄食行为。最近发现,在下丘脑有一种胰多肽类似物——神经肽Y(NPY),可能在动物的摄食活动中起一定的调制作用。Clark等用大鼠进行了这方面的观察。它们发现向饱食大鼠的第三脑室注入2～10μg的人胰多肽(hPP)和NPY,可使动物白昼进食总量明显增加,而且NPY比hPP更有效。它可在注射后诱导所有的大鼠进食,其摄食量比注射hPP多2倍、潜伏期短,而进食时间更长。实验中还观察到NPY和hPP在给动物第二次注射后,对于增加动物单位时     

大鼠室旁核注射orexin-A对体重的影响

目的:探讨大鼠室旁核(PVN)注射orexin-A对体重的影响。方法:大鼠室旁核(PVN)微量注射orexin-A,用大脑置管埋管、组织化学染色等方法探讨PVN注射orexin-A对其体重的影响。结果:与安慰剂组大鼠相比,PVN注射orexin-A组大鼠体重明显减轻(P0.05),而orexin-A组和安慰剂组摄食量无明显差异(P0.05)。注射结束后6天,orexin-A处理大鼠的体重仍显著低于注射前(P0.05),而安慰剂组大鼠则比注射前显著增重(P0.05)。药物注射可显著降低机体脂肪,但并不特异存在于注射orexin-A或安慰剂的大鼠身上。Orexin-A组和安慰剂组大鼠的肌肉量和脂肪量均显著降低(P0.05),但注射orexin-A的大鼠降低更明显。与安慰剂组相比,orexin-A处理后的摄食转化率显著降低(P0.05)。结论:大鼠室旁核(PVN)注射orexin-A可通过增加活动量产生负能量平衡,引起体重减轻。     

生长激素释放肽-6对小鼠下丘脑摄食相关核团c-fos表达时间依从性影响北大核心CSCD

本研究旨在探讨外周注射ghrelin受体激动剂生长激素释放肽-6(growth hormone releasing peptide-6,GHRP-6)对NMRI小鼠摄食的影响以及摄食相关核团(弓状核、视上核和室旁核)的激活情况及其有效作用时间。腹腔注射GHRP-6 1,3,6 h后观察小鼠累计摄食量,同时用免疫组织化学方法检测GHRP-6对自由饮食小鼠和禁食小鼠下丘脑摄食相关核团c-fos表达影响,并观察GHRP-6作用的时间依从性。结果显示,腹腔注射了GHRP-6的小鼠摄食量明显大于生理盐水注射鼠,且在注射后3 h时观察到的摄食量的增加尤为显著,但注射后6 h内总的累计摄食量无显著变化;同时,GHRP-6能够在不依赖于摄食的情况下促进弓状核和室旁核中c-fos的表达,且c-fos的表达在注射后1 h时达到峰值,随后逐渐下降。以上结果提示,外源性注入GHRP-6可显著增加动物在给药后1、3 h的累积摄食量,该作用至少部分是通过上调弓状核和室旁核中的c-fos蛋白表达起作用的,而且具有时间依从性。本研究结果可为临床ghrelin受体激动剂的使用间隔提供理论依据。     

生长激素释放肽-6对小鼠下丘脑摄食相关核团c-fos表达时间依从性影响

本研究旨在探讨外周注射ghrelin受体激动剂生长激素释放肽-6(growth hormone releasing peptide-6,GHRP-6)对NMRI小鼠摄食的影响以及摄食相关核团(弓状核、视上核和室旁核)的激活情况及其有效作用时间。腹腔注射GHRP-6 1,3,6 h后观察小鼠累计摄食量,同时用免疫组织化学方法检测GHRP-6对自由饮食小鼠和禁食小鼠下丘脑摄食相关核团c-fos表达影响,并观察GHRP-6作用的时间依从性。结果显示,腹腔注射了GHRP-6的小鼠摄食量明显大于生理盐水注射鼠,且在注射后3 h时观察到的摄食量的增加尤为显著,但注射后6 h内总的累计摄食量无显著变化;同时,GHRP-6能够在不依赖于摄食的情况下促进弓状核和室旁核中c-fos的表达,且c-fos的表达在注射后1 h时达到峰值,随后逐渐下降。以上结果提示,外源性注入GHRP-6可显著增加动物在给药后1、3 h的累积摄食量,该作用至少部分是通过上调弓状核和室旁核中的c-fos蛋白表达起作用的,而且具有时间依从性。本研究结果可为临床ghrelin受体激动剂的使用间隔提供理论依据。     

Hypotensive mechanism of [Leu13]motilin in dogs in vivo and in vitro.

The effects of [Leu13]motilin were examined in vivo after its intravenous administration into anesthetized dogs and in vitro with isolated preparations of canine mesenteric artery. [Leu13]Motilin (0.1-10 nmol x kg(-1), i.v.) induced both strong and clustered phasic contractions in the gastric antrum and duodenum. At doses of over 1 nmol x kg(-1), [Leu13]motilin also produced transient decreases in arterial blood pressure, left ventricular pressure, maximum rate of rise of left ventricular pressure, and total peripheral resistance, and an increase in aortic blood flow and heart rate. A selective motilin antagonist, GM-109 (Phe-cyclo[Lys-Tyr(3-tBu)-betaAla] trifluoroacetate), completely abolished the gastric antrum and duodenal motor responses induced by [Leu13]motilin. In contrast, hypotension induced by [Leu13]motilin (1 nmol x kg(-1)) was unchanged in the presence of GM-109. In isolated mesenteric artery preparations precontracted with U-46619 (10(-7) M), [Leu13]motilin (10(-8)-10(-5) M) induced an endothelium-dependent relaxation, and this was inhibited by a pretreatment with N(omega)-nitro-L-arginine, a competitive inhibitor of NO synthase (10(-4) M). A high dose (10(-4) M) of GM-109 slightly decreased [Leu13]motilin-induced relaxation, and shifted the concentration-response curve of [Leu13]motilin to the right. However, the pA2 value (4.09) of GM-109 for [Leu13]motilin in the present study was conspicuously lower than that previously demonstrated in the rabbit duodenum (7.37). These results suggest that [Leu13]motilin induces hypotension via the endothelial NO-dependent relaxation mechanism and not through the receptor type that causes upper gastrointestinal contractions.     

Motilin activates neurons in the rat amygdala and increases gastric motility

Motilin and motilin receptors have been found in most regions of the brain, including the amygdala, one of the most important parts of the limbic system. Our previous study found that administration of motilin in the hippocampus stimulates gastric motility. We now explore the effect of motilin in the amygdala on gastric motility. In conscious rats, gastric motility was recorded after microinjection of motilin, motilin receptor antagonist (GM-109) or a mixture of the two into the basomedial amygdala nucleus (BMA). In anesthetized rats the changes of spontaneous discharges of gastric distention sensitive neurons (GDSN) in the BMA were recorded after intracerebroventricular (i.c.v.) microinjection of motilin or GM-109. In conscious rats the amplitude of gastric contractions increased dose-dependently after microinjection of motilin in the BMA, and decreased after microinjection of GM-109. The excitatory or inhibitory effects induced by motilin or GM-109 alone, were weakened by microinjection of a mixture solution of both. The spontaneous discharge frequency of gastric distention excitatory neuron (GDEN) was mainly inhibited by i.c.v. microinjection of motilin but excited by GM-109. In contrast, the spontaneous discharge frequency of gastric distention inhibitory neuron (GDIN) was mainly excited by motilin, but inhibited by GM-109. Our findings suggest that motilin may regulate gastric motility by modulating neural pathways in the BMA.     

Neuropeptide Y receptor(s) mediating feeding in the rat: characterization with antagonists

The present study evaluated the effect of the neuropeptide Y (NPY) Y1 receptor antagonists BIBO 3304 and SR 120562A and of the Y5 receptor antagonists JCF 104, JCF 109, and CGP 71683A on feeding induced either by NPY or food deprivation. In a preliminary experiment, NPY was injected into the third cerebroventricle (3V) at doses of 0.07, 0.15, 0.3, or 0.6 nmol/rat. The dose of 0.3 nmol/rat, which produced a cumulative 2-h food intake of 11.2 +/- 1.9 g/kg body weight, was chosen for the following experiments. The antagonists were injected in the 3V 1 min before NPY. The Y1 receptor antagonist BIBO 3304 significantly inhibited NPY-induced feeding at doses of 1 or 10 nmol/rat. The Y1 receptor antagonist SR 120562A, at the dose of 10 but not of 1 nmol/rat, significantly reduced the hyperphagic effect of NPY, 0.3 nmol/rat. The Y5 receptor antagonists JCF 104 and JCF 109 (1 or 10 nmol/rat) and CGP 71683A (10 or 100 nmol/rat) did not significantly modify the effect of NPY, 0.3 nmol/rat. However, JCF 104 (10 nmol/rat) and CGP 71683A (100 nmol/rat), but not JCF 109 (10 nmol/rat), significantly reduced food intake during the interval from 2 to 4 h after injection of a higher dose, 0.6 nmol/rat, of NPY. Feeding induced by 16 h of food deprivation was significantly reduced by the Y1 receptor antagonist BIBO 3304 (10 nmol/rat), but it was not significantly modified by the same dose of SR 120562A or JCF 104. These findings support the idea that the hyperphagic effect of NPY is mainly mediated by Y1 receptors. The results obtained with JCF 104 and CGP 71683A suggest that Y5 receptors may have a modulatory role in the maintenance of feeding induced by rather high doses of NPY after the main initial feeding response.     

Different metabolic responses to central and peripheral injection of enterostatin

Enterostatin, a pentapeptide cleaved from procolipase, suppresses fat intake after peripheral and central administration. Chronic treatment of rats with enterostatin decreases body weight and body fat. The effect was greater than could be accounted by the reduction in food intake alone. Hence, we have investigated the effect of enterostatin on energy metabolism. Male Sprague-Dawley rats adapted to a high-fat diet were implanted with lateral cerebral ventricular or amygdala cannulas. The metabolic effects were determined by indirect calorimetry. After habituation to the test cages, fasted rats were injected with either saline vehicle or enterostatin given either intraperitoneally (100 nmol) or intracerebroventricularly (1 nmol) or into specific brain regions [amygdala (0.01 nmol) or paraventricular nucleus (PVN) (0.1 nmol)]. Respiratory quotient (RQ) and energy expenditure were monitored over 2 h. Intraperitoneal enterostatin reduced RQ (saline: 0.81 +/- 0.02 vs. enterostatin: 0.76 +/- 0.01) and increased energy expenditure by 44%. Intracerebroventricular enterostatin increased the energy expenditure without any effects on RQ, whereas PVN enterostatin increased metabolic rate, while preventing the increase in RQ observed in the control animals. In contrast, neither RQ nor energy expenditure was altered after enterostatin was injected into the amygdala. Enterostatin activated AMP-activated protein kinase in primary cultures of human myocytes in a dose- and time-dependent manner and increased the rate of fatty acid beta-oxidation. These findings suggest that enterostatin regulates energy expenditure and substrate partitioning through both peripheral and central effects.     

Chronic intraparaventricular nuclear administration of orexin A in male rats does not alter thyroid axis or uncoupling protein-1 in brown adipose tissue

Orexin A, synthesised in the posterolateral hypothalamus, has widespread distribution including the paraventricular nucleus (PVN), which is rich in thyrotropin-releasing hormone (TRH) neurones. Nerve fibres in the PVN synapse on neurones that send polysynaptic projections to brown adipose tissue (BAT), which is important in thermogenesis. A number of observations suggests orexin A may be involved in regulation of metabolism and thermogenesis. We investigated the effect of orexin A injected intracerebroventricularly (ICV) on thyroid-stimulating hormone (TSH) and thyroid hormones in male rats. We then examined the effect of chronic iPVN injections of orexin A on plasma TSH and uncoupling protein-1 (UCP-1) protein in BAT. Orexin A (3 nmol) administered ICV significantly suppressed plasma TSH at 10 and 90 min. Orexin A (0.3 nmol) administered into the PVN twice daily for 3 days significantly increased day-time 2-h food intake, but did not significantly alter nocturnal food intake. Though chronic iPVN orexin A altered diurnal food intake, there was no effect on 24-h food intake or body weight. Furthermore, orexin A administered chronically into the PVN did not alter UCP-1 level in BAT, or plasma hormones relative to saline injected animals. Chronic iPVN orexin A does not appear to influence thermogenesis through activation of UCP-1 or the thyroid axis.     

Obestatin对血浆ghrelin和nesfatin-1水平及胃排空的影响

目的:探讨侧脑室注射obestatin对大鼠血浆酰基化ghrelin、去酰基化ghrelin、nesfatin-1水平的影响以及对胃排空的调控。方法:侧脑室注射obestatin,采用酶免疫测定(EIA)法检测血浆酰基化ghrelin、去酰基化ghrelin、nesfatin-1水平以及胃排空率的变化。结果:侧脑室分别注射0.1、0.3或1.0 nmol obestatin,大鼠血浆酰基化ghrelin、去酰基化ghrelin以及nesfatin-1水平无显著改变(P0.05),且酰基化ghrelin与去酰基化ghrelin比率无显著改变(P0.05);侧脑室注射obestatin,大鼠摄食量无显著改变,但胃排空率明显增加(P0.05);胃排空率明显延迟(P0.05)。与侧脑室注射1.0 nmol Obestatin组相比,注射1.0 nmol Obestatin+CRF,大鼠摄食量无显著改变,胃排空率明显延迟(P0.05)。各组摄食量及进入十二指肠内食物量无明显差异(P0.05)。结论:中枢obestatin促进大鼠的胃排空,可能与h/r CRF通路有关。     

Brain-derived neurotrophic factor in the hypothalamic paraventricular nucleus increases energy expenditure by elevating metabolic rate

Brain-derived neurotrophic factor (BDNF) decreases food intake and body weight, but few central sites of action have been identified. The hypothalamic paraventricular nucleus (PVN) is important in energy metabolism regulation, and expresses both BDNF and its receptor. We tested three hypotheses: 1) PVN BDNF reduces feeding and increases energy expenditure (EE), 2) PVN BDNF-enhanced thermogenesis results from increased spontaneous physical activity (SPA) and resting metabolic rate (RMR), and 3) PVN BDNF thermogenic effects are mediated, in part, by uncoupling protein 1 (UCP1) in brown adipose tissue (BAT). BDNF (0.5 microg) was injected into the PVN of Sprague-Dawley rats; and oxygen consumption, carbon dioxide production, food intake, and SPA were measured for 24 h in an indirect calorimeter. SPA was also measured in open-field activity chambers for 48 h after BDNF injection. Animals were killed 6 or 24 h after BDNF injection, and BAT UCP1 gene expression was measured with quantitative real-time PCR. BDNF significantly decreased food intake and body weight gain 24 h after injection. Heat production and RMR were significantly elevated for 7 h immediately after BDNF injection. BDNF had no effect on SPA, but increased UCP1 gene expression in BAT at 6 h, but not 24 h after injection. In conclusion, PVN BDNF reduces body weight by decreasing food intake and increasing EE consequent to increased RMR, which may be due, in part, to BAT UCP1 activity. These data suggest that the PVN is an important site of BDNF action to influence energy balance.