Sapolsky R M, Krey L C, McEwen B S
Exp Gerontol. 1983;18(1):55-64. doi: 10.1016/0531-5565(83)90051-7.
To test if the adrenocortical axis of the rat loses sensitivity to negative feedback control during aging, we examined corticosterone secretion under basal, stressed and post-stress conditions in young and in aged Fisher male rats. We find no age-related change in the speed or magnitude of the stress response or in the capacity to manifest a corticosterone response following chronic stress. However, we do observe in aging rats an elevation of basal corticosterone and an impaired capacity to adapt to and recover from stress. This latter finding is illustrated by longer latencies relative to young rats, in the return of serum corticosterone concentrations to basal values during sustained exposure to mild cold or following the end of immobilization stress. All of these deficits reflect an increased rate of corticosterone secretion during physiologically inappropriate circumstances. Such observations support the concept that there is an age-related loss of sensitivity of the brain and pituitary to the inhibitory effects of high circulating levels of corticosterone on ACTH release.
为了测试大鼠的肾上腺皮质轴在衰老过程中是否会丧失对负反馈控制的敏感性，我们研究了年轻和老年雄性费希尔大鼠在基础、应激和应激后条件下的皮质酮分泌情况。我们发现，应激反应的速度或幅度以及慢性应激后表现出皮质酮反应的能力没有与年龄相关的变化。然而，我们确实观察到老年大鼠的基础皮质酮水平升高，并且适应应激和从应激中恢复的能力受损。相对于年轻大鼠，在持续暴露于轻度寒冷期间或固定应激结束后，血清皮质酮浓度恢复到基础值的延迟时间更长，这说明了后一个发现。所有这些缺陷都反映了在生理上不适当的情况下皮质酮分泌速率增加。这些观察结果支持这样一种概念，即大脑和垂体对高循环水平的皮质酮对促肾上腺皮质激素释放的抑制作用的敏感性存在与年龄相关的丧失。
