Decreased drug tolerance following endocrinological manipulation in the rat.

Nine groups of rats of rats were either hypophysectomized, adrenalectomized or left unoperated. These groups were then subjected to daily increasing injections of either morphine HCL, sodium pentobarbital, chloridiazepoxide or saline. Hypophysectomy seemed to lower the lethal dose of the three drugs tested. Adrenalectomy seemed to have only a minimal effect on the lethal dose of morphine HCL or sodium pentobarbital.