Leptin secretion and leptin receptor in the human stomach

Background and aim-The circulating peptide leptin produced by fat cells act s on central receptors to control food intake and body weight homeostasis. Contrary to initial reports, leptin expression has also been detected in th e human placenta, muscles, and recently, in rat gastric chief cells. Here w e investigate the possible presence of leptin and leptin receptor in the hu man stomach. Methods-Leptin and leptin receptor expression were assessed by immunohistoc hemistry, reverse transcriptase-polymerase chain reaction (RT-PCR), and wes tern blot analysis on biopsy samples from 24 normal individuals. Fourteen ( 10 healthy volunteers and four patients with non-ulcer dyspepsia and normal gastric mucosa histology) were analysed for gastric secretions. Plasma and fundic mucosa leptin content was determined by radioimmunoassay. Results-In fundic biopsies from normal individuals, immunoreactive leptin c ells were found in the lower half of the fundic glands. mRNA encoding ob pr otein was detected in the corpus of the human stomach. The amount of fundic leptin was 10.4 (3.7) ng leptin/g mucosa, as determined by radioimmunoassa y. Intravenous infusions of pentagastrin or secretin caused an increase in circulating leptin levels and leptin release into the gastric juice. The le ptin receptor was present in the basolateral membranes of fundic and antral gastric cells. mRNA encoding Ob-RL was detected in both the corpus and ant rum, consistent with a protein of similar to 120 kDa detected by immunoblot ting. Conclusion-These data provide the first evidence of the presence of leptin and leptin receptor proteins in the human stomach and suggest that gastric epithelial cells may be direct targets for leptin. Therefore, we conclude t hat leptin may have a physiological role in the human stomach, although muc h work is required to establish this.