Central nervous system effects of bombesin on the cardiovascular response to cold exposure

The effects of cold exposure on mean arterial pressure (MAP), heart rate (HR) and oxygen consumption (VO2) were examined in conscious, unrestrained rats receiving intracerebroventricular (i.c.v.) injections of bombesin or appropriate control solutions. Cold exposure elicited significant elevations of MAP, HR and VO2 in control-treated rats. I.c.v. administration of bombesin produced dose-related suppressions of cold-induced elevations of HR and VO2, but not MAP. The central nervous system (CNS)-selective somatostatin analog, ODT8-SS, injected i.c.v., reversed the effects of bombesin on HR and VO2 during cold exposure. Intravenous administration of atropine methyl nitrate did not antagonize the effects of bombesin on HR and VO2 during cold exposure. HR and VO2 were strongly correlated in bombesin-treated rats suggesting that this peptide may prevent cold-induced elevations of VO2 through a CNS action on cardiac function.