Gastric neuropeptides and gastric motor abnormality in streptozotocin-induced diabetic rats - Observation for four weeks after streptozotocin

Alterations of gastric calcitonin gene-related peptide and substance P cont ent and gastric emptying in early stages of streptozotocin-induced diabetic rats were investigated. Diabetes was induced by intravenous injection of s treptozotocin (50 mg/kg) in male Wistar rats. Gastric emptying of phenol re d solution and calcitonin gene-related peptide and substance P content of g astric walls, measured by radioimmunoassay, was assessed two and four weeks after streptozotocin injection. Gastric emptying two weeks after streptozo tocin was delayed (32 +/- 9%) and that four weeks after was enhanced (73 +/ - 2%) compared with nondiabetic control rats (50 +/- 3%). Calcitonin gene-r elated peptide content of the gastric antrum and corpus was increased two w eeks after and decreased four weeks after streptozotocin, while gastric sub stance P content was not changed at any time in diabetic rats. Insulin trea tment reversed alterations of gastric emptying and calcitonin gene-related peptide content. The delayed gastric emptying in two-week diabetic rats was reversed by CGRP antagonist and the enhanced gastric emptying in four-week diabetic rats was reversed by CGRP pretreatment. These results suggest a p ossible relationship between gastric calcitonin gene-related peptide and ab normal gastric motility in diabetic state.