Radiation Effects and Adrenal Cortex

Summary Previous investigations in rats have demonstrated a biphasic increase of the corticosteroid levels both in the adrenal glands and the blood after whole-body x-irradiation. The first increase occurred 2·5 hours and the second increase 72 hours after irradiation. In this paper it was shown that both these phases of increased corticosteroid production and secretion are significantly inhibited by cysteamine. This radioprotective effect was basically the same after mid-lethal and totally lethal radiation doses. It is concluded that both the first and second corticosteroid reaction are specific effects of irradiation. Cysteamine by itself caused an increase of the plasma corticosteroid levels 2·5 hours after the injection while the levels in the adrenal gland remained unchanged. 72 hours after irradiation this effect of cysteamine could no longer be demonstrated. The possible mechanisms of action of cysteamine are discussed. It is suggested that its radioprotective properties mitigate a stress reaction of the pituitary-adrenal system occurring shortly after irradiation.