STRESS AND EPIDERMAL MITOTIC ACTIVITY

Abstract

An examination has been made of the actions and interactions of the androgenic, oestrogenic and glucocorticoid hormones on epidermal mitotic activity in the mouse. Testosterone, which has a moderate mitogenic action in the male, does not appear to stimulate adrenal secretion. Thus no antimitotic mechanism is brought into play, and the mitotic activity induced by testosterone continues indefinitely. Oestrogenic hormones, on the other hand, cause active growth of the adrenal cortex, and this appears to be accompanied by active glucocorticoid hormone secretion. Thus the stimulation of epidermal mitotic activity caused by oestrogens is counteracted by the antimitotic action of the glucocorticoid hormones. This reaction occurs naturally on a limited scale at each oestrous period, and it is especially obvious after repeated injections of oestrone and after oestradiol implantation. Cortisone, when given simultaneously with oestrone, largely prevents the initial rise in mitotic activity, and conversely, adrenalectomy prevents the development of the full mitotic inhibition after oestradiol implantation. A detailed consideration of these last results suggests that the glucocorticoid hormones, while playing a major role in the antimitotic mechanism, may not represent the whole of that mechanism. Evidence is reviewed to indicate that the oestrogenic stimulus to the adrenal cortex passes by way of the anterior pituitary gland, and it is possible that a pituitary hormone may itself exert an antimitotic action.