竹叶青蛇消化道内分泌细胞的免疫组织化学定位

IMMUNOHISTOCHEMICAL LOCALIZATION OF THE ENDOCRINE CELLS IN THE DIGESTIVE TRACT OF TRIMERESURUS STEJNEGERI

应用 8种特异性胃肠激素抗血清对竹叶青蛇 (Trimeresurusstejnegeri)消化道内分泌细胞进行了免疫组织化学定位。 5 羟色胺细胞和生长抑素细胞在整个消化道中均有分布。 5 羟色胺细胞以十二指肠和回肠密度为最高 ,空肠、直肠和幽门其次 ,胃体较低 ,食道和贲门中偶见 ;生长抑素细胞在十二指肠处数量最多 ,胃体、幽门和空肠其次 ,其余消化道各段偶见 ;胰高血糖素细胞只见于十二指肠和空肠 ;血管活性肠肽在贲门和胃体处有少量阳性细胞分布 ,食道中偶见。以上各处内分泌细胞的分布密度差异显著。未检出胃泌素、P 物质、胰多肽和胰岛素免疫反应阳性细胞。上述内分泌细胞的分布特点可能与竹叶青的摄食习性和生活环境有关。

At present, the gastrointestinal tract of reptiles has received a little attention from comparative endocrinologist and the available information being mainly limited to the crocodiles and lizards. To date there have been few studies of regulatory peptides in the gastrointestinal tract of snakes. However, Masini reported immunoreactivity for gastrin\\cholecystokinin (combined) and somatostatin in small intestinal endocrine cells of three species of snake, the Asp viper ( Vipera aspis ), the Grass snake ( Natrix natrix ) and the Viperine snake ( N. maura ), but found that immunoreactivity to pancreatic glucagon, secretin or motilin was absent. In addition, somatostatin containing cells had been detected in the stomach and small intestine of the European adder ( Viper aberus ). There is, however, no systematic study of regulatory peptides of the entire length of the digestive tract in any snake. In view of the evolutionary position of reptiles, an investigation of the gastrointestinal regulatory peptide system was considered to be of particular interest. Trimeresurus stejnegeri , a member of the reptilia suborder serpents, was studied as an example of poisonous snakes. The purpose of this study was to conduct a detailed examination of the distribution of the endocrine cells in the digestive tract of this snake. The tunica mucosa of the entire length of the digestive tract was examined to determine the types, relative frequencies and distributions of endocrine cells found there by using an immunohistochemical method (Avidin biotin peroxidase complex method). The eight gastrointestinal peptides involved, which had been reported to occur in mammals, were 5 Hydroxytryptamine, somatostatin, glucagon, vasoactive intestinal polypeptide, gastrin, substance P, pancreatic polypeptide and insulin. The results showed that four of them were observed in the digestive tract of Trimeresurus stejnegeri , namely 5 Hydroxytryptamine, somatostatin, glucagon and vasoactive intestinal polypeptide. 5 Hydroxytryptamine and somatostatin immunoreactive cells distributed throughout the digestive tract, while 5 Hydroxytryptamine immunoreactive cells were found with the highest density in the duodenum and ileum, the second highest in the jejunum, rectum and stomachus pyloricus, numberously in the stomachus corpus, occasionally in the oesophagus and stomachus cardiacus. Somatostatin immunoreactive cells were mainly located in the duodenum, numberously in the stomach pyloric, stomachus corpus and jejunum, but rarely in any other regions. The glucagon immunoreactive cells were only present in the duodenum and jejunum. The vasoactive intestinal polypeptide immunoreactive cells were found moderately in the corpus stomachus and cardiacus, while sparsely in the oesophagus.Data are statistically different among these regions. No immunoreactivity was observed with the antisera to gastrin, substance P, pancreatic polypeptide and insulin. The evidence collected in this study indicates that the distributive mode of endocrine cells in the digestive tract of Trimeresurus stejnegeri differs from the other snakes. This may be related to its feeding and habitation.