Functions of the hypothalamo-hypophyseal-adrenal system in aging in female monkeys.
Comparative studies on the functioning of the adrenal cortex in female rhesus macaques (Macaca mulatta) of different ages are reported - animals were aged 6-9 years (young adults; n = 5) and 20-26 years (old adults; n = 5). Corticosteroid concentrations (cortisol (F) and dehydroepiandrosterone sulfate (DHEAS)) were determined by specific radioimmunological and immunoenzyme methods in basal conditions, after acute stress (insulin-induced hypoglycemia, 2-h movement restriction), and after administration of dexamethasone. Basal F levels showed no marked age differences, while DHEAS concentrations in older animals decreased sharply. These animals also demonstrated weakened adrenal cortex responses to movement restriction, giving rise to delays in reaching peak F and DHEAS levels and decreases in the areas under their response curves (AUC) during the 4-h study period. In the dexamethasone test, the hypothalamo-hypophyseal-adrenal system of monkeys aged 20-26 years was relatively resistant to the suppressing effect of glucocorticoids via the negative feedback mechanism. It is suggested that disruption of feedback in the system controlling adrenal cortex function may be at least partially due to the development of peripheral blood steroid dysbalance with aging, this consisting particularly of a decrease in the DHEA (DHEAS) level; this steroid is known for its neurological activity.
Goncharova
N D
ND
Science Research Institute of Medical Primatology, Russian Academy of Medical Sciences, Sochi.
Oganyan
T E
TE
Taranov
A G
AG
D000302:Adrenal Cortex / Q000502:physiology; D000375:Aging / Q000502:physiology*; D000818:Animals; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism; D019314:Dehydroepiandrosterone Sulfate / Q000097:blood; D005260:Female; D006854:Hydrocortisone / Q000097:blood; D007004:Hypoglycemic Agents / Q000633:toxicity; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D007328:Insulin / Q000633:toxicity; D008253:Macaca mulatta; D010913:Pituitary-Adrenal System / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D012149:Restraint, Physical; D013315:Stress, Psychological / Q000503:physiopathology
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D019314:Dehydroepiandrosterone Sulfate; D006854:Hydrocortisone