Somatostatin Cell is the Progenitor of the -Cell Family in the Gastro-entero-pancreatic Endocrine System

초록

The endocrine system of the upper digestive is functionally related with endocrine pancreas. In spite of different developmental process during the early embryonic period, the endocrine cells in both organs show functional and morphological similarities. In particular, the somatostatin producing -cell retains a unique feature with long cytoplasmic processes producing inhibitory action upon the surrounding secretory cells. Other investigators and we have recently reported NOS (nitric oxide synthase) in the islet somatostatin cells. In the present study, we pursued and illustrated the developmental and functional characteristics of somatostatin cells in both pancreatic islets and gastric mucosa. Pancreas and stomach were obtained from fetus of Sprague-Dawley rat at 10, 12, 14, 18, 20 days of gestation, and from neonate at 1, 2, 7 and 14 days after birth. Adult tissues were also taken from 5, 7 and 9-week-old animals. The tissues were used for double and triple labeling immunocytochemistry using somatostatin, bNOS and amylin antibodies. Somatostatin cells were first detected in pancreas as early as at 18th day of gestation and lacked immunoreactivity to bNOS and amylin. At 20th days of gestation, they appeared in gastric gut mucosa as well as in pancreas. In pancreas, they showed NOS immunoreactivity that was not detected in gastric somatostatin at this age. In peri-natal stages, we found NOS immunoreaction in most somatostatin cells, whereas amylin was seen only in few somatostatin cells in both endocrine systems. The same is true in adult pancreas, but not in gastric mucosa. In adult gastric mucosa, several types of -cells were classified according to their hormonal contents. All somatostatin cells contained bNOS (type 1; 47%), amylin (type 2