Immunocytochemical detection of leptin-like immunoreactivity in the chicken gastroenteric tract

Leptin is a hormone produced and secreted mainly by adipocytes, but also by other tissues such as placenta, brain, mammary, and pituitary glands. The gastric epithelium has also been reported as a source of leptin in mammals. In this study we examined the presence of leptin in the chicken gastroenteric tract by immunohistochemistry and Western blotting. Strong and widespread leptin-like immunoreactivity was observed in the mucosal epithelium of proventriculus plicae and in the epithelium of the complex compound glands. Numerous leptin-immunoreactive cells were found along lining epithelium of duodenum villi, while few leptin-immunoreactive cells were observed in the basal zone of duodenum glands. Many leptin-immunoreactive cells were found in the caeca at the basal zone of glands, while very few leptin-immunoreactive cells were found in the deep glandular structures of the large intestine. In the homogenates of chicken gastroenteric tract the protein detected using a human leptin-specific antibody had estimated molecular weight of approximately 15-16 kDa. To our knowledge, this is the first report demonstrating leptin-like protein distribution in the whole gastroenteric tract of bird. This finding constitute important data for the further understanding of the mechanism that regulate feeding behaviour in birds, farm animal for which the control of food intake and fatness are a high economic interest.