Leptin: A new gastric hormone

Introduction. The circulating peptide leptin, product of the ob gene, regulates long-term satiety to maintain energy balance and body weight homeostasis. According to current literature, it is uniquely secreted by adipocytes and the placenta. Results. We report the presence of leptin mRNA and leptin protein in rat gastric epithelium. Leptin immunoreactive cells were localized in the gastric fundus at the site of chief cells. Experiments on isolated rat stomach showed that leptin was secreted by these cells into the blood. In 18-hour fasted rats, refeeding or CCK injection resulted in an acute release of the gastric pool (15 mn) without any effect on fat tissue leptin. This release was followed by a recovery phase. In agreement with these findings CCK-induction of leptin gene expression was demonstrated in isolated fundic cells. Discussion. We suggest that gastric leptin could play a role in early satiety events following food ingestion, perhaps in a synergistic way with CCK, via vagal afférents. In addition, gastric leptin could be involved in other effects such as regulation of digestive secretions, intestinal absorption and hepatocyte insulin sensitivity (Bado et al., Nature 1998:394:790-793).