Anti-opiate (naloxone) suppression of Cushingoid degenerative changes in obese/SHR.

Young and mature, genetically obese and non-obese, spontaneously hypertensive rats (SHR) were injected with saline (controls) or naloxone for 12 weeks. Naloxone stilled the hyperphagia to a normal intake in the obese SHR (Obese/SHR) so that young Obese/SHR did not develop their usual massive obesity and mature Obese/SHR that had become massively obese were reduced to leanness. The naloxone-treated young, obese and non-obese SHR (controls) exhibited marked reduction of the weight of their pituitary and adrenal glands, whereas the pituitary and adrenal glands of naloxone-treated mature, obese and non-obese/SHR were greatly increased in weight. The elevated systolic blood pressure of the obese and non-obese rats was reduced after chronic treatment with naloxone. Naloxone treatment caused reduction of blood ACTH, corticosterone, and beta endorphin levels but elevated growth hormone levels. The characteristic hyperinsulinemia, hyperlipidemia, hyperglycemia, elevated BUN levels, and the Cushingoid spectrum of degenerative changes found in Obese/SHR did not appear in naloxone-treated rats.