THE DISTRIBUTIVE PATTERNS OF SOMATOSTATIN IN THE DIGESTIVE TRACT AND BRAIN OF SCHIZOTHORAX PRENANTI

In order to provide the morphological evidence for further researches in the regulation of digestive and neuroen-docrine activities, the distributive patterns of somatostatin (Som) in the digestive tract and brain of Schizothorax prenanti were studied. Strept avidin-biotin-peroxidase complex (SABC) immunocytochemical method associated with image analysis was used to observe Sore positive reactions in the different parts of Schizothorax prenanti's digestive tract and brain. There was no Som-positive reaction in the oropharyneal cavity and esophagus. Sore-positive cells with strong inten-sity were detected in the intestine, being the highest in the foregut(anterior segment: 58.20±10.97 number/mm2; poste-rior segment:57.34±8.12 number/mm2), medium in the midgut (46.17±12.99 number/mm2), and lower in the hind gut (anterior segment:21.36±7.25 number/mm2; posterior segment:13.64±4.24 number/mm2). Som-positive cells in the intestine were often distributed in the mucosal epithelium, presenting various kinds of forms such as ovoid, globu-lar, triangle, elongated or spindle-shaped aspects. The macrophages located in the intestine showed strong Som-positive reaction. Sore-positive reaction with weak or strong intensity was widely located in the neurons and nerve fibers of the brain. Reaching 1496.80±233.42 number/mm2, most of Som-positive cells were greatly distributed in the corpus mam-millare of inferior lobe in the hypothalamus. The number densities of Som-positive cells were medium in the dorsal olfactory (795.67±67.12 number/mm2) and lateral olfactory nuclei (740.52±87.38 number/mm2), the primordial striatum (278.34±12.14 number/mm2), preoptic nucleus (283.60±89.13 number/mm2), latero-rhinal fissure (299.36±78.61 number/mm2), nucleus habenulae (346.63±83.12 number/mm2), nucleus anterior thalami (173.31±23.54number/mm2), nucleus prerotundus (199.57±32.80 number/mm2), medium lobe of hypothalamus (101.31±21.45 number/mm2), Diverticulum of hypothalamus inferiors lobes (217.43±39.23 number/mm2), the bilateral parts of the mesencephalon chamber (346.63±105.76 number/mm2), lower in the molecular layer of cerebella valvula (91.48±11.14 number/mm2), the nuclei Ⅵ and Ⅴ of myelencephalon (nucleus Ⅵ: 47.27±15.76 number/mm2;nucleus Ⅴ: 78.78±13.79 number/mm3). In addition, Som-positive nerve fibers were observed in the lamina terminali and epiphy-sis. Our study has further confirmed that Som is a kind of brain-gut peptide. The distributive patterns of the Som-posi-tive cells in the digestive tract of Schizothorax prenanti are greatly related to its feeding habits, intestinal functions and structures as well, indicating that Som may play an important role in the modulation of the secretive and suppressive activi-ties of intestine. The distributive characteristics of Som-positive cells in the hypothalamus of Schizothorax prenanti provide the morphorlogieal evidence for the regulation of GH in the fish. Som is widely distributed in the different parts of the brain, suggesting that Som not only plays a role in the regulation of the physiological activities in the hypothalamus-hy-pophysial axis, but also has wide functions as a nervous transmitter, or regulator by affecting different target cells.