Role of the adrenal gland in the thermal response to morphine withdrawal in rats.

Administration of naloxone to morphine-dependent rats results in an elevation of tail skin temperature and a fall in core temperature. Previous studies have demonstrated a role of the adrenal gland in the thermal responses that accompany morphine withdrawal in the rat. In the present study, experiments were designed to determine if the duration of adrenalectomy significantly influenced the thermal response observed in morphine withdrawal. In addition we evaluated the influence of the adrenal medulla and glucocorticoid replacement in adrenalectomized rats in mediating the thermal responses of the morphine-dependent rat. Ovariectomized rats were addicted to morphine and subsequently withdrawn by administration of naloxone. This treatment results in a significant rise in tail skin temperature and subsequent fall in colonic temperature. These thermal responses were not observed in morphine-naive rats. Adrenalectomy resulted in a significant attenuation of the rise in tail skin temperature associated with withdrawal. This reduced tail skin temperature response was not different among animals adrenalectomized for 1, 7, 14, 21, or 28 days. Likewise, the moderate increase in core temperature associated with morphine treatment was not observed in the adrenalectomized rats. Serum corticosteroid determinations confirmed the loss of the adrenal steroids in the adrenalectomized rats. In a subsequent experiment it was determined that adrenal demedullation did not reduce the tail skin temperature response during morphine withdrawal, and corticosteroids restored the naloxone-induced surge in tail skin temperature in morphine-dependent, adrenalectomized rats.(ABSTRACT TRUNCATED AT 250 WORDS)