Brudieux R, Ait Chaoui A, Rakotondrazafy J
Laboratoire d'Endocrinologie Comparée, UFR de Biologie, Université Bordeaux I, Talence, France.
Gerontology. 1995;41(6):308-14. doi: 10.1159/000213700.
Age-related changes in plasma adrenocorticotropic hormone (ACTH), corticosterone, and aldosterone responses to exogenous corticotropin-releasing hormone (CRH) were studied concomitantly in both old and adult Long-Evans female rats. All animals were pretreated with dexamethasone and pentobarbital anesthetized. An acute intravenous injection of 1 micrograms rat CRH/100 g body weight markedly increased the plasma concentrations of ACTH, corticosterone, and aldosterone--with similar temporal kinetics in the two groups of rats. However, the incremental CRH responses were significantly lower in old (approximately -70, -45-60, and -30-50%, respectively, for ACTH, corticosterone, and aldosterone) as compared with adult rats. Together with our recent findings, the present results suggest that the previously reported reduced secretion of corticosteroids in aged rats is due to both an impaired steroidogenetic capacity of adrenocortical cells to respond to ACTH and to a decreased ability of corticotropes to produce ACTH in response to CRH.
在老年和成年雌性Long-Evans大鼠中，同时研究了血浆促肾上腺皮质激素（ACTH）、皮质酮和醛固酮对外源性促肾上腺皮质激素释放激素（CRH）反应的年龄相关变化。所有动物均用地塞米松预处理并戊巴比妥麻醉。急性静脉注射1微克大鼠CRH/100克体重可显著提高ACTH、皮质酮和醛固酮的血浆浓度，两组大鼠的时间动力学相似。然而，与成年大鼠相比，老年大鼠（ACTH、皮质酮和醛固酮分别约降低70%、45%-60%和30%-50%）的CRH增量反应显著更低。结合我们最近的研究结果，目前的结果表明，先前报道的老年大鼠皮质类固醇分泌减少是由于肾上腺皮质细胞对ACTH反应的类固醇生成能力受损以及促肾上腺皮质激素细胞对CRH产生ACTH的能力下降。
