下丘脑室旁核微量注射ghrelin经迷走神经增强清醒大鼠胃运动及胃电活动

Ghrelin microinjected into hypothalamic paraventricular nucleus stimulates gastric motility and elecctrical activity mediated by vagus nerve in conscious rats

目的探讨下丘脑室旁核(paraventricular nucleus,PVN)内微量注射ghrelin对清醒大鼠胃运动及胃电活动的影响及其自主神经机制。方法采用核团内微量注射药物、应力传感器引导胃运动及银丝电极同步记录胃电活动等方法。结果PVN注射0.15、0.3 nmol ghrelin后,胃运动及胃电幅度呈剂量依赖性增强(P<0.01),0.3 nmol ghrelin组胃运动及胃电快波和慢波的幅度变化率分别为(68.76±17.00)%、(57.04±17.10)%、(63.20±19.59)%;药物剂量对胃运动频率无明显影响。膈下迷走神经切断或静脉注射阿托品(0.5 mg/kg)可完全消除PVN内ghrelin增强胃运动及胃电活动的效应(P<0.01),而交感神经节摘除或静脉注射酚妥拉明(2 mg/kg)或心得安(5 mg/kg)则不影响该效应。结论PVN内微量注射ghrelin可增强清醒大鼠胃运动及胃电活动,这种作用在外周通过迷走神经胆碱能通路介导,而与交感神经关系不大。

Objective To investigate the effects of microinjection of exogenous ghrelin into the hypothalamic paraventricular nucleus（PVN） on gastric motility and electrical activity in ambulant conscious rats and their peripheral neural mechanisms.Methods Ghrelin was microinjected into PVN in rats and the antral motility and electrical activity were measured by extraluminal force strain gage transducers and electrodes.Results The amplitudes of gastric motility and electrical activity dose-dependently increased after administration of ghrelin（0.15,0.3 nmol） into PVN（P〈0.01）.In 0.3 nmol group,the amplitudes of gastric motility,fast wave and slow wave increased by（68.76±17.00）%,（57.04±17.10）% and（63.20±19.59）%,respectively.Pretreatment of subdiaphragmatic vagotomy or intravenous injection of atropine（0.5 mg/kg） completely abolished the effects of ghrelin（P〈0.01）,but no effect was observed following sympathectomy or intravenous injection of propranolol（5 mg/kg） or phentolamine（2 mg/kg）.Conclusion Exogenous ghrelin in PVN stimulates gastric motility and electrical activity in conscious rats,which seems to be mediated by the vagal cholinergic fibers,whereas the sympathetic nerves may not be involved in the pathway.