Some genetical aspects on pituitary-adrenal response to stress in mice

The response of pituitary-adrenal axis (as measured by the estimation of 11-hydroxycorticosteroid level in plasma of decapitated animals) to various kinds of stress (restriction, cold, formalin injection) was studied in eight inbred strains of mice and compared to that found after the injection of epinephrine, isopropyl-norepinephrine or ACTH. It was found that the response to all of the above mentioned influences appears to be genetically determined. A positive correlation was observed between the basal level of corticosteroids in plasma and the effect of adrenomimetics on one hand and the response to cold and restriction on the other, while no correlation was found between the former parameter and the effect of ACTH and formalin injection. It may be concluded that genetically conditioned control and regulatory mechanisms appear to be the most important factor in the response of pituitary-adrenal axis to the emotional and cold stress, while the reactivity of adrenal cortex itself as measured by the effect of ACTH injection appears to be of a minor importance.