Role of nitric oxide in insulin-induced hypothermia in rats.

Hypothermia is a well-known phenomenon which accompanies hypoglycemia in mammals. The present study was designed to test the hypothesis that nitric oxide (NO) plays a role in insulin-induced hypothermia. The body temperature (Tb) of awake, unrestrained rats was measured before and after systemic infusion of insulin (2U x kg(-1) x h(-1)), and intracerebroventricular administration of NG-nitro-(L)-arginine methyl ester (L-NAME, a nonselective NO synthase inhibitor, 200 microg/1 microl). We observed a significant reduction in body temperature after insulin infusion. L-NAME alone caused no significant change in body temperature. When the two treatments were combined, no change in Tb was observed. The data indicate that NO plays a key role in insulin-induced hypothermia.