Leptin (the ob gene product), ob-receptor and ghrelin immunolocalizations in fasted and fed swine gastrointestinal mucosa

Leptin and ghrelin are hormones, which affect food intake and energy balance. Leptin is secreted, among other tissues, by the mammalian white adipose tissue and can prevent feeding. Ghrelin, which is mainly secreted by the stomach, elicits the opposite effect. Considering that leptin has been extracted from the gastric mucosa too, this study was performed to investigate gastric immunolocalizations of leptin, leptin-receptor (OB-R) and ghrelin in 18 h-fasted and 2 h-fed adult pigs. Leptin was detected in the gastric fundus, where cells on the lower half of the gastric glands were positive for either OB or pepsinogen in fasted animals, and both immunoreactivities were detected all along the gastric glands in the fed ones. OB-R-immunoreactivity was present in duodenal and jejunal enterocytes, as already seen in other species. Ghrelin-positive endocrine cells were detected in all the three glandular regions of gastric mucosa, although labeled cells were most numerous in the oxyntic mucosa, without difference in relation with fasting and feeding. We suggest that leptin is involved in the peripheral short-term regulation of food intake, possibly acting as an endocrine and paracrine regulating factor.