Bombesin, but not amylin, blocks the orexigenic effect of peripheral ghrelin

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology Vol. 291; no. 4; p. 24
• Main Authors: Kobelt, Peter, Goebel, Miriam, Stengel, Andreas, Schmidtmann, Marco
• Format: Journal Article
• Language: English
• Published: Bethesda American Physiological Society 01.10.2006
• Subjects: Diet; Neurology; Neurons; Peptides; Rodents
• ISSN: 0363-6119; 1522-1490

The interaction between ghrelin and bombesin or amylin administered intraperitoneally on food intake and brain neuronal activity was assessed by Fos-like immunoreactivity (FLI) in nonfasted rats. Ghrelin (13 µg/kg ip) increased food intake compared with the vehicle group when measured at 30 mm (g/kg: 3.66 ± 0.80 vs. 1.68 ± 0.42, P<0.0087). Bombesin (8 µg/kg) injected intraperitoneally with ghrelin (13 µg/kg) blocked the orexigenic effect of ghrelin (1.18 ± 0.41 g/kg, P<0.0002). Bombesin alone (4 and 8 µg/kg ip) exerted a dose-related nonsignificant reduction of food intake (g/kg: 1.08 ± 0.44, P>0.45 and 0.55 ± 0.34, P>0.16, respectively). By contrast, ghrelin-induced stimulation of food intake (g/kg: 3.96 ± 0.56 g/kg vs. vehicle 0.82 ± 0.59, P<0.004) was not altered by amylin (1 and 5 µg/kg ip) (g/ kg: 4.37 ± 1.12, P>0.69, and 3.01 1 0.78, respectively, P>0.37). Ghrelin increased the number of FLI-positive neurons/section in the arcuate nucleus (ARC) compared with vehicle (median: 42 vs. 19, P<0.008). Bombesin alone (4 and 8 µg/kg ip) did not induce FLI neurons in the paraventricular nucleus of the hypothalamus (PVN) and coadministered with ghrelin did not alter ghrelin-induced FLI in the ARC. However, bombesin (8 µg/kg) with ghrelin significantly increased neuronal activity in the PVN approximately threefold compared with vehicle and ~1.5-fold compared with the ghrelin group. Bombesin (8 µg/kg) with ghrelin injected intraperitoneally induced Fos expression in 22.4 ± 0.8% of CRF-immunoreactive neurons in the PVN. These results suggest that peripheral bombesin, unlike amylin, inhibits peripheral ghrelin induced food intake and enhances activation of CRF neurons in the PVN. [PUBLICATION ABSTRACT]