HISTO-PHYSIOLOGICAL EFFECTS OF CORTISONE ON RAT PITUITARY AND THYROID1

Abstract

Young adult male albino rats were treated with 5 mg. of cortisone daily for 20 days and with 2 mg. daily for 83 days resp. Their controls were pair-fed. No change was encountered in their pituitaries which could have been correlated with the substantially decreased output of ACTH reflected by the atrophy of the adrenals. On the other hand, there was some cytological evidence in the hypophyses of both cortisone-treated groups for an increased rate of TSH release. The histological structure of the thyroids of the treated animals was indicative of a higher level of thyrotropic activation than that occurring in the controls. The protein bound I (PBI) of the thyroids in the 5 mg. group was lower than that of the control glands. The plasma PBI was somewhat higher in the rats treated with 5 mg. of cortisone daily than in their controls. The cortisone-induced inhibition of thyroid function, which was encountered by several previous workers, cannot de due to an interference with the production or action of TSH. The data presented suggest a promoting effect of cortisone on the thyrotropic function of the pituitary.