Changes of CGRP- and VIP-containing Nerve Fibers in the pancreas of Streptozotocin-Induced Diabetic Rat

Kim, Young Joo; Won, Moo Ho; Suh, Gun Gyo; Seong, Je Kyung; Lee, Joon Sup; Kim, Hwan Mook; Oh, Yang Seok

Abstract

BACKGROUND: The peptidergic nerves, namely the third nerve, are distributed in the pancreas with adreniergic and cholinergic nerves. However, it has been known that the peptidergic nerves control the pancreatic endocrine and exocrine functions, only a few morphological studies has been done. Therefore we tried to investigate the distribution patterns of the pancreatic calcitonin gene-related peptide(CGRP) and vasoactive intestinal polypeptide(VIP) containing nerves in the pancreas of the streptozotocin-induced diabetic rats. METHODS: Eight week old male WKY rats were used in this study. Insulin-dependent diabetic animals were produced by the intraperitoneal injection of streptozotocin(60 mg/Kg) dissolved in cold citrate buffer(pH 4.2) to WKY rats. The control rats were treated with the vehicle. Immnunohistochemical studies were carried out to observe the changes of CGRP containing nerve fibers and VIP containing nerve fibers in the pancreas at 0, 3, 14, and 28 days after the injection of streptozotocin. RESULTS: In insulin-dependent diabetic animal group, the density and the innervation patr.erns of CGRP containing nerve fitrs were significantly increased on day 3 and thereafter decreased to the level of control group at the end of experiment. The immunoreactivities of VIP containing nerve fibers were not altered in the pancreatic islers. The immunoreaetivities, however, were gradually increased in the periphery of the acini, the connective tissues, and the periphery of the ducts and vasculatures. CONCLUSION: The results of the present imvestigation suggest that the distribution patterns of CGRP and VIP containing nerve fibers in the insulin-dependent diabetic rats are related to the development of diabetes and may provide a morphological bases for the possible role of nueropeptides in pancreas of the diabetic rats. Further study are required about the relationships between the distribution patterns and the functions of the peptidergic nerve in pancreas.