Non-essential Role of the Adrenal Medulla in the Hibernation of the 13-Lined Ground Squirrel

Abstract

ALTHOUGH the adrenal cortical hormones are reported to be necessary for successful hibernation and arousal in European ground squirrels, Citellus citellus¹, and in European hamsters, Cricetus cricetus², the necessity and function of the adrenal medullary hormones are still in doubt. Most investigators agree, however, that these catecholamines, especially norepinephrine, are probably involved in chemical heat production by torpid and arousing hibernators^3–5. Although totally adrenalectomized hibernating animals arouse in a nearly normal manner, a return to normal hibernating patterns is prevented unless adrenal cortical tissue is transplanted into the anterior chamber of the eye or unless cortisone or deoxycorticosterone acetate (DCA) is administered^1,2. Presumably, then, the hormones of the adrenal medulla are not needed for at least short ‘bouts’ of hibernation or for arousal, even though the importance of the sympathetico-adrenal system in spontaneous arousal has been repeatedly emphasized^4,6–8.