Ait-Chaoui A, Rakotondrazafy J, Brudieux R
Laboratoire d'Endocrinologie comparée, Université Bordeaux I, UFR de Biologie, Talence, France.
Horm Res. 1995;43(5):181-7. doi: 10.1159/000184275.
Age related changes in the time courses of response of plasma corticosterone and aldosterone to exogenously applied ACTH were simultaneously studied in old (female and male) Long-Evans rats and compared to both young and adult pentobarbitone-anesthetized and dexamethasone-pretreated control rats. Acute intravenous injection of either 0.5 or 50.0 ng ACTH (1-24)/100 g body weight increased plasma concentrations of the two steroids with a similar time course in all groups of rats. However, we observed a significant age-related attenuation in the plasma corticosteroid response. Thus, in old as compared to young rats there was a decrease of approximately 45, 40 and 30% in plasma corticosterone levels respectively 8 min after the lower dose of ACTH in female and 45 min after the higher dose in female and male rats. Similarly, an attenuated (approximately -38%) response of plasma aldosterone levels, induced 45 min after the higher dose of ACTH, was observed both in old female and male rats. These results suggest that the previously reported age-related decreases of in vivo corticosterone and aldosterone secretion are, at least in part, due to a reduced capacity of adrenocortical cells for steroid biosynthesis and release in response to stimulation by ACTH.
在老年（雌性和雄性）Long-Evans大鼠中，同时研究了血浆皮质酮和醛固酮对外源性促肾上腺皮质激素（ACTH）反应的时间进程中与年龄相关的变化，并与年轻和成年戊巴比妥麻醉及地塞米松预处理的对照大鼠进行了比较。急性静脉注射0.5或50.0 ng ACTH(1 - 24)/100 g体重，在所有大鼠组中，两种类固醇的血浆浓度均以相似的时间进程升高。然而，我们观察到血浆皮质类固醇反应存在显著的年龄相关衰减。因此，与年轻大鼠相比，老年大鼠在低剂量ACTH注射后8分钟，雌性血浆皮质酮水平分别降低了约45%、40%和30%，在高剂量ACTH注射后45分钟，雌性和雄性大鼠的血浆皮质酮水平也分别降低了约45%、40%和30%。同样，在高剂量ACTH注射后45分钟，老年雌性和雄性大鼠血浆醛固酮水平的反应均减弱（约-38%）。这些结果表明，先前报道的与年龄相关的体内皮质酮和醛固酮分泌减少，至少部分是由于肾上腺皮质细胞对ACTH刺激的类固醇生物合成和释放能力降低所致。
