Mano-Otagiri Asuka, Ohata Hisayuki, Iwasaki-Sekino Azusa, Nemoto Takahiro, Shibasaki Tamotsu
Department of Physiology, Nippon Medical School, Bunkyo-ku, Tokyo, Japan.
J Endocrinol. 2009 Jun;201(3):341-9. doi: 10.1677/JOE-08-0374. Epub 2009 Apr 7.
To clarify the role of ghrelin in the regulatory mechanism of energy metabolism, we analyzed the effects of centrally and peripherally administered ghrelin on noradrenaline release in the brown adipose tissue (BAT) of rats using a microdialysis system. I.c.v. administration of ghrelin at a dose of 500 pmol suppressed noradrenaline release in BAT, and microinjection of ghrelin (50 pmol) into the paraventricular nucleus (PVN) or arcuate nucleus (ARC) of the hypothalamus also suppressed noradrenaline release in BAT. In addition, i.v. administered ghrelin (30 nmol) suppressed noradrenaline release in BAT, and this suppression was blocked by a vagotomy. Neither i.c.v. nor i.v. administration of des-acyl ghrelin, which does not bind to GH secretagogue receptor type 1a (GHS-R1a), affected noradrenaline release in BAT. These results indicate that ghrelin increases energy storage by suppressing the activity of the sympathetic nerve innervating BAT. It seems that the PVN and ARC, which express GHS-R1a, are the sites of action of ghrelin in the brain and that the action of peripheral ghrelin on the sympathetic nerve activity innervating BAT is mediated by the vagal nerve, which also expresses GHS-R1a.
为阐明胃饥饿素在能量代谢调节机制中的作用，我们使用微透析系统分析了中枢和外周给予胃饥饿素对大鼠棕色脂肪组织（BAT）中去甲肾上腺素释放的影响。脑室内给予500 pmol剂量的胃饥饿素可抑制BAT中去甲肾上腺素的释放，向下丘脑室旁核（PVN）或弓状核（ARC）微量注射胃饥饿素（50 pmol）也可抑制BAT中去甲肾上腺素的释放。此外，静脉注射胃饥饿素（30 nmol）可抑制BAT中去甲肾上腺素的释放，而这种抑制作用可被迷走神经切断术阻断。既不与1a型生长激素促分泌素受体（GHS-R1a）结合的去酰基胃饥饿素，无论是脑室内注射还是静脉注射，均不影响BAT中去甲肾上腺素的释放。这些结果表明，胃饥饿素通过抑制支配BAT的交感神经活性来增加能量储存。似乎表达GHS-R1a的PVN和ARC是胃饥饿素在大脑中的作用部位，并且外周胃饥饿素对支配BAT的交感神经活性的作用是由同样表达GHS-R1a的迷走神经介导的。
