Hyperthermic action of somatostatin-28

An intracisternal injection of somatostatin-28 produced hyperthermia in rats at cold, thermoneutral, warm ambient temperatures. The hyperthermic response to somatostatin-28 was not prevented by pretreatment of rats with the following agents: alpha-methylparatyrosine, phenoxybenzamine, propranolol, sulpiride, atropine, methysergide or naloxone. Somatostatin-28 prevented hypothermia induced by bombesin and gamma-MSH when it was administered simultaneously, but it left the hyperthermic response to TRH intact. The results indicate that somatostatin-28 produces hyperthermia by elevating a "set point" or regulated level of temperature. Under the conditions tested, the hyperthermic response to somatostatin-28 does not appear to be dependent on muscarinic cholinergic, serotonergic, alpha- or beta-adrenergic, dopaminergic or endogenous opiate system.