Abstract
We have investigated aging of the hypothalamic-pituitary-adrenal (HPA) axis in female rhesus monkeys that differ in adaptive behavior. Plasma cortisol (F) and dehydroepiandrosterone sulfate (DHEA-S) concentrations under basal conditions and under acute psycho-emotional stress were evaluated in blood plasma of young (6-8 years) and old (20-27 years) female rhesus monkeys with various types of adaptive behavior (aggressive, depression-like, and average). We have found that the age-related changes in the HPA axis of monkeys with depression-like behavior were accompanied by the maximal absolute and relative hypercortisolemia under both basal conditions and stress. Moreover, young aggressive monkeys, in comparison with young monkeys of other behavior groups, demonstrated the highest plasma levels of DHEA-S and the lowest molar ratios between F and DHEA-S. Thus, age-related dysfunctions of the HPA axis are associated with adaptive behavior of animals.
Highlights
The incidence of the stress-related diseases, such as depression, anxiety, insulin resistance, coronary heart disease, hypertension, cerebrovascular insufficiency, and some other diseases dramatically increases through ageing [for example 1-6]
It is worthy of note that dehydroepiandrosterone sulfate (DHEA-S) concentrations underwent maximum age-related changes in the first group of animals (5.07-fold), and minimal age-related changes in the third group (1.95-fold)
We evaluated the behavior of monkeys housed individually, in metabolic cages
Summary
The incidence of the stress-related diseases, such as depression, anxiety, insulin resistance, coronary heart disease, hypertension, cerebrovascular insufficiency, and some other diseases dramatically increases through ageing [for example 1-6]. It has been shown that intrinsic factors, contributing to decreased stress adaptability in old animals, namely disturbances of the hypothalamicpituitary-adrenal (HPA) axis, are likely to be responsible, at least in part, for health deterioration in the aged [7,8,9,10,11]. There are individual peculiarities in vulnerability and resistance to stresses and stress-related pathologies among different persons due to the heterogeneity of the ageing process. Hyperactivation of the HPA axis occurs in persons who exhibit increased anxiety, in those with some forms of depression [14,15,16,17] as well as in animals with depression-like behavior [12;18;19]. DHEA-S is elevated in individuals exhibiting aggressive behavior [22,23,24]
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