The effects of adrenal hormones on brain and body size

By surgical means and selective hormone replacement, the adrenal secretions responsible for the suppression of brain growth were investigated. Adrenalectomy, but not demedullation, promoted brain growth, indicating that the active hormone was a cortical steroid. Replacement at various doses of mineralocorticoids (aldosterone,.02 and.5 mg/kg; deoxycorticosterone, 1.0 and 3.0 mg/kg) and corticosterone (1, 3, 15 mg/kg) revealed that mineralocorticoids were without influence on hindbrain weight, forebrain weight, or linear dimensions. These hormones did, however, exact a pronounced effect on body weight, seeming to increase fat deposition in a dose-dependent manner. They did not, however, affect skeletal growth as assessed by body (nose to anus) length. Corticosterone strongly depressed brain weights and dimensions, indicating that this glucocorticoid was the likely steriod whose removal by adrenalectomy augmented brain size. Corticosterone also decreased body weight, seemingly at the expense of fat stores, since it had no effect on body length. A combined dose of corticosterone (8 mg/kg) and deoxycorticosterone (.6 mg/kg) administered to adrenalectomized rats was found to very closely match the brain and body characteristics of intact rats.