LS-2-P-1471 Localization and Distribution of Ghrelin in the Gastrointestinal Tract of the Golden Apple Snail, Pomacea canaliculata

Ghrelin, a 28 amino acid peptide, is an endogenous ligand for the growth hormone secretagogue receptor. Ghrelin was firstly isolated from the rat stomach. However, ghrelin has later been identified in the gastrointestinal tract of many species. In the present study, the localization and distribution of ghrelin were investigated in the gastrointestinal tract of the golden apple snail, Pomacea canaliculata, by immunohistochemistry technique using antibody that raised against the N-terminus of ghrelin of human origin. In addition, levels of ghrelin in segments of the gastrointestinal tract were measured using enzyme-linked immunosorbent assay (ELISA). Immunoreactivity of ghrelin was identified in the entire segments of the gastrointestinal tract. The immunoreactive cells were localized in the mucosal layer of the esophagus, stomach, intestine, and rectum. In the esophagus, the immunoreactivity was observed in the apical region of the epithelial cells. However, the immunoreactivity was found at the basal region of the epithelial cells lining the stomach, intestine, and rectum. It was found that ghrelin level was highest in the esophagus, but was in the lowest level in the rectum. The levels were 74.14 ± 3.56, 59.21 ± 4.22, 26.13 ± 2.76, and 10.87 ± 3.62 ng/ml in the esophagus, intestine, stomach, and rectum, respectively. These results suggest that ghrelin may participate in the digestive function of this species. Moreover, it seems that ghrelin has a high degree of preservation during evolution from invertebrates to vertebrates.