Homeostatic regulation of autonomous nerves system by ghrelin

生长素降低体温。在高温条件下，胃促生长素的产生受到刺激，血浆胃促生长素浓度升高。此外，ghrelin KO小鼠在高温条件下的死亡率较高，说明这些小鼠缺乏正常的体温调节机制。像老鼠这样的小动物在长期的食物剥夺后表现出麻木（每日冬眠）诱导。在冬眠状态下，它们表现为体温低，活动减少。然而，饥饿素KO小鼠没有表现出麻木诱导和能量抑制。因此，胃饥饿素是抑制新陈代谢和活动所必需的生存激素。

Ghrelin decreases body temperature. In a hot condition, ghrelin production in stomach is stimulated and plasma ghrelin concentration is increased in mice. In addition, ghrelin KO mice shows high mortality rate in a hot condition, suggesting that these mice lack normal regulatory mechanism of body temperature. Small animals like mice show torpor(daily hibernation) induction after long term food deprivation. In torpor state, they show low body temperature and decrease of activity. However, ghrelin KO mice do not show torpor induction and suppression of energy. Thus, ghrelin is a survival hormone necessary to suppress metabolism and activity.