AREA POSTREMA, LATERAL PARABRACHIAL NUCLEUS, AND THE ANTINATRIOREXIC EFFECT OF BOMBESIN

Bombesin (BN) injected to sodium depleted rats either centrally, parti cularly into the paraventricular nucleus (PVN) or peripherally by intr aperitoneal (IP) route, exerts a potent inhibitory effect on the intak e of 2% sodium chloride. To determine whether the area postrema (AP) a nd the lateral parabrachial nucleus (LPBN), which are known to be invo lved in the control of ingestive behavior, could be sites for the anti natiorexic activity of BN, we studied the effects of injections of thi s peptide into the LPBN or, by LP or fourth ventricular route, to surg ically AP-lesioned rats. We observed that in sodium depleted rats: 1) injected into the LPBN at a dose of 50, but not of 25, ng per nucleus, BN significantly reduced the intake of 2% sodium chloride; 2) adminis tered either intraperitoneally or into the fourth brain ventricle, BN induced a potent antinatriorexic effect in AP-sham lesioned animals; a nd 3) in the same experimental conditions, surgical ablation of the AP did not reduce the antinatriorexic effect of the peptide. These data indicate that the LPBN may be, with the PVN, a site for the BN-ergic i nhibitory control of salt appetite and that the AP, which has been imp licated in BN-induced anorexia, does not play a role in the antinatrio rexic effect of this peptide. (C) 1998 Elsevier Science Inc.