Does the histaminergic system mediate bombesin/GRP-induced suppression of food intake?
Merali, Z.; Banks, K.
American Journal of Physiology 267(6 Pt 2): R1589-R1595
1994
ISSN/ISBN: 0002-9513 PMID: 7810769 Document Number: 422882
Bombesin (BN) and its mammalian homologue, gastrin-releasing peptide (GRP), are potent satiety agents and have been implicated in the physiological regulation of food intake. The mechanisms) of action of this effect remains unclear. There is a functional and anatomic overlap between histamine and BN in relationship to feeding, which led us to hypothesize that BN may mediate its satiety effects through activation of the histaminergic system. To assess this contention, we examined the effects of R-alpha-methylhistamine (alpha-MH) and Imetit, selective H-3-receptor agonists that inhibit the release and synthesis of histamine, on BN- or cholecystokinin (CCK)-induced satiety. In this report we present the first evidence for the role of histamine H-3 receptors in the mediation of BN-elicited satiety. During the first hour of the 4-h daily feeding session, BN reduced food intake by gt 50% relative to the control condition; this suppression was blocked by prior treatment with the H-3-receptor agonist, alpha-MH. This blockade of BN-induced satiety was dose related and selective to BN as alpha-MH failed to attenuate sulfated CCK-8-induced satiety. When alpha-MH was administered alone, it failed to significantly affect food intake. The specificity of this effect was further supported by the demonstration that another H-3 agonist, Imetit, was also able to block the feeding-suppressant effects of BN. Furthermore, thioperamide, an H-3-receptor antagonist, blocked these effects of Imetit. These data support our working hypothesis that BN elicits its satiety effect by facilitating histaminergic activity at yet to be determined relevant sites and that H-3-receptor agonists attenuate its effect on food intake by inhibiting the release of histamine.