Peripherally administered bombesin has been demonstrated to inhibit food intake in a variety of species. Although the behavioral actions of bombesin are well characterized, neither the site of action nor mechanism through which bombesin affects feeding has been demonstrated. To test the hypothesis that bombesin's feeding effects are through a gastric inhibitory mechanism or a gastric site of action we examined the potential relationship between the inhibition of gastric emptying and the inhibition of intake produced across a dose range of bombesin and compared the relative potency of bombesin analogues for inhibiting feeding with their affinity for gastric bombesin receptors. Comparisons of the inhibitions of gastric emptying and feeding produced by 2, 4, 8, or 16 micrograms/kg of bombesin revealed no relationship, and, in fact, no gastric inhibitory action was evident. The feeding inhibitory actions of dose ranges (100 pmol-100 nmol) of litorin, ranatensin, acetylated gastrin-releasing peptide-(20-27) [AcGRP-(20-27)] and bombesin-(8-14) fragment were assessed and compared with bombesin. These compounds inhibited feeding with a relative potency of bombesin greater than AcGRP-(20-27) greater than ranatensin greater than litorin greater than bombesin-(8-14). This rank order of potency differed from the relative affinity of these compounds for gastric bombesin receptors for which all of these compounds except bombesin-(8-14) have a greater affinity than does bombesin. The results of these two experiments suggest that bombesin's satiety actions are not mediated by a gastric inhibitory mechanism or through a gastric site of action.
INHIBITORY MECHANISM OF COSTUNOLIDE, A SESQUITERPENE LACTONE ISOLATED FROM LAURUS NOBILIS, ON BLOOD-ETHANOL ELEVATION IN RATS: INVOLVEMENT OF INHIBITION OF GASTRIC EMPTYING AND INCREASE IN GASTRIC JUICE SECRETION
