ACUTE STRESS EFFECTS ON THE ADRENAL-CORTEX IN THE RAT - A BIOCHEMICALAND IMMUNOHISTOCHEMICAL STUDY

Activation of the stress system induces physiologic alterations as wel l as behavioural ones that ultimately improve the adaptability of the organism to adverse conditions. In our previous study on the morpho-fu nctional evolution of the adrenal cortex, from birth to adulthood, the question of what could be the contribution of immobilization stress t o the observed hormonal levels was brought up. Male adult rats were su bmitted to immobilization of variable duration. The antibody IZAb was used to allow a correct differentiation between the zona glomerulosa ( ZG) and the inner zones of the cortex (IZ). A significant increase of the ACTH levels, especially at 5 and 30 min was observed. Corticostero ne (B), surprisingly, revealed 2 peaks of secretion: one at 30 sec and another at 30 min. The area of the cortex, determined by an image ana lyser, only showed a slight decrease at 30 sec. The proportions of the cortical area occupied by ZG and IZ were unaltered. We concluded that a corticosterone peak at 30 sec precedes the elevation of ACTH induce d by stress. Only the second peak, in view of its parallel course to A CTH, can be attributed to an effect of this pituitary hormone.