Peripheral administration of bombesin increases metabolism in the rat

Bombesin has been shown to decrease food intake and increase the duration of slow wave sleep, as well as to increase blood glucose and glucagon. A suspected mechanism of bombesin's anorexigenic and hypnogenic action could be via its possible effect on the enhancement of metabolism itself. Therefore, the effect of bombesin on rat metabolism was investigated in an open circuit computerized respirometer. This device was specifically conceived to extract the fraction of metabolism which is not due to the energy cost of muscular effort. This fraction of metabolism was designed background metabolism. In the absence of food, peripheral administration of bombesin increased the background metabolism at all doses. The higher dose of bombesin (32 micrograms/kg IP) elicited a four-hour enhancement of background metabolism, the magnitude of which was equivalent to that induced by a meal of about 1.5 grams. Therefore, it is suggested that the effect of bombesin on feeding and sleep could be achieved, at least partly, by its effect on the background metabolism, which ultimately may modulate the behavioral responses.