Faculty of Safety & ADME, Asubio Pharma Co., Ltd., Japan.
J Pharmacol Sci. 2014;124(1):31-9. doi: 10.1254/jphs.13180fp. Epub 2013 Dec 21.
Ghrelin plays multiple physiological roles such as growth hormone secretion and exerting orexigenic actions; however, its physiological roles in the electrical activity of autonomic nerves remain unclear. Here, we investigated the effects of human ghrelin on several autonomic nerve activities in urethane-anesthetized rats using an electrophysiological method. Intravenous injection of ghrelin at 3 μg/kg significantly and transiently potentiated the efferent activity of the gastric vagus nerve; however, it did not affect the efferent activity of the hepatic vagus nerve. The activated response to ghrelin in the gastric efferent vagus nerve was not affected by the gastric afferent vagotomy, suggesting that this effect was not induced via the gastric afferent vagus nerve. Ghrelin did not affect the efferent activity of the brown adipose tissue, adrenal gland sympathetic nerve, and the renal sympathetic nerve. In addition, rectal temperature and the plasma concentrations of norepinephrine, corticosterone, and renin were also not changed by ghrelin. These findings demonstrate that ghrelin stimulates the gastric efferent vagus nerve in an organ-specific manner without affecting the gastric afferent vagus nerve and that ghrelin does not acutely affect the efferent basal activity of the sympathetic nerve in rats.
胃饥饿素发挥多种生理作用，如促进生长激素分泌和发挥摄食作用；然而，其在自主神经电活动中的生理作用尚不清楚。在这里，我们使用电生理学方法研究了在乌拉坦麻醉大鼠中，人胃饥饿素对几种自主神经活动的影响。静脉内注射 3μg/kg 的胃饥饿素可显著且短暂地增强胃迷走神经传出活动；然而，它不影响肝迷走神经的传出活动。胃饥饿素对胃传出迷走神经的激活反应不受胃传入迷走神经切断术的影响，表明这种作用不是通过胃传入迷走神经诱导的。胃饥饿素不影响棕色脂肪组织、肾上腺交感神经和肾交感神经的传出活动。此外，直肠温度和血浆去甲肾上腺素、皮质酮和肾素浓度也不受胃饥饿素的影响。这些发现表明，胃饥饿素以器官特异性方式刺激胃传出迷走神经，而不影响胃传入迷走神经，并且胃饥饿素不会急性影响大鼠交感神经的传出基础活动。
