[Age-related changes of the hypothalamic-pituitary-adrenal axis in individuals with various types of adaptive behaviour].

The purpose was to study age-related changes of the hypothalamic-pituitary-adrenal (HPA) axis function and their interrelations with features of cognitive aging in individuals with various type of adaptive behaviour on model of laboratory primates. Plasma cortisol (F) and dehydroepiandrosterone sulfate (DHEAS) levels in basal conditions (0900h and 2100h of day) and under acute psycho emotional stress (2-hour moderate restraint) were estimated in blood plasma of 34 young (6-8 years) and 34 old (20-27 years) female rhesus monkeys with various types of adaptive behaviour (aggressive, adequate, depressive-like). We have found that the age-related changes in HPA of monkeys of the depression-like behavior were accompanied by the maximal absolute and relative hypercortisolemia in the basal conditions as well as in the stress conditions. These disturbances in HPA are apparently associated with the higher age-related cognitive disturbances. Moreover, the young aggressive monkeys in comparison with the young monkeys of other behavior groups, demonstrated the higher levels of DHEAS and the minimal molar ratios between F and DHEAS plasma levels. For old animals with the aggressive behavior, these inter-group differences have leveled off. The minimal age-related changes in HPA and the minimal cognitive disturbances have been revealed for the monkeys with the adequate behavior. These results establish that the age-related damage of the HPA axis and the relevant age-related changes in the cognitive processes are the characteristic individual peculiarities of the animals associated with their individual features in the adaptive behavior strategy.

[Stress, aging, hypothalamic-pituitary-adrenal axis and reliability of antioxidant enzyme defence].

The purpose of the investigation was to study age-related changes in reaction of the hypothalamic-pituitary-adrenal axis and erythrocyte antioxidant enzyme system in response to acute psychoemotional stress in non human primates. Ten young (6-8 years) and ten old (20-26 years) healthy female rhesus monkeys were subjected to acute moderate psycho-emotional stress (two hours squeeze cage restraint) at 15:00 h. Plasma cortisol (F), activities of superoxide dismutase (SOD), glutathione peroxidase, gluthatione reductase (GR), gluthatione-S-transferase, and lipid peroxidation products (TBARS) in erythrocytes were measured before stress and 30, 60, 120, 240 min and 24 h after beginning of the stress. In young monkeys SOD activity decreased in response to the stress while it increased in the half of old monkeys. Young animals also demonstrated essentially higher increase in plasma F level and GR activity in response to the restraint, in comparison with old monkeys. Level of TBARS did not change in response to the stress in young animals and significantly increased in old monkeys. The age-related alterations in F, SOD, and GR stress responsiveness lead to activation of peroxide oxidation of lipids that may be considered as an important factor of aging damage of erythrocyte functioning and reliability of oxygen transport to tissues under stress conditions.