Date Yukari
Frontier Science Research Center, University of Miyazaki, Kiyotake, Miyazaki, Japan.
Methods Enzymol. 2012;514:261-9. doi: 10.1016/B978-0-12-381272-8.00016-7.
Ghrelin, a gastrointestinal hormone, stimulates feeding and secretion of growth hormone (GH). Ghrelin is thought to directly affect neurons involved in feeding or GH secretion through growth hormone secretagogue receptor (GHS-R; ghrelin receptor); however, it is still unclear whether ghrelin crosses through the blood-brain barrier. Recently, several gastrointestinal hormones have been shown to transmit signals involved in feeding to the brain at least in part via the vagal afferent system. In fact, ghrelin's action on feeding or GH secretion is abolished or attenuated in rats that have undergone vagotomy or treatment with capsaicin, a specific afferent neurotoxin. GHS-R is present in the vagal afferent neurons as well as the brain and is transported to the afferent terminals. In addition, the firing rate of vagal afferent fibers significantly decreases after ghrelin administration. Taken together, these data show that the vagal afferent system is the major pathway conveying ghrelin's signals for feeding and GH secretion to the brain.
胃饥饿素是一种胃肠激素，可刺激进食和生长激素（GH）分泌。胃饥饿素被认为通过生长激素促分泌素受体（GHS-R；胃饥饿素受体）直接影响参与进食或GH分泌的神经元；然而，胃饥饿素是否能穿过血脑屏障仍不清楚。最近，有研究表明，几种胃肠激素至少部分通过迷走神经传入系统将与进食相关的信号传递至大脑。事实上，在接受迷走神经切断术或用辣椒素（一种特异性传入神经毒素）处理的大鼠中，胃饥饿素对进食或GH分泌的作用会被消除或减弱。GHS-R存在于迷走神经传入神经元以及大脑中，并被转运至传入神经末梢。此外，给予胃饥饿素后，迷走神经传入纤维的放电频率显著降低。综上所述，这些数据表明，迷走神经传入系统是将胃饥饿素的进食和GH分泌信号传递至大脑的主要途径。
