Streptozotocin-Induced Diabetes Mellitus Is Associated with Increased Pancreatic Tissue Levels of Noradrenaline and Adrenaline in the Rat

The pancreata of streptozotocin-induced diabetic rats were examined to determine whether the pancreatic tissue content of catecholamines is altered after the onset of diabetes. Experimental diabetes was induced by intraperitoneal injection of streptozotocin (60 mg/kg body weight). Four weeks after the induction of diabetes, pancreatic tissue fragments were taken from the tail end of the pancreas and processed for catecholamine content using the high-performance liquid chromatography method. Immunohistochemical analysis showed that the pancreata of diabetic rats contained more tyrosine hydroxylase-positive nerves compared with controls. Pancreatic noradrenaline content, expressed as the mean +/- SD, was significantly (p < 0.03) greater in diabetic rats (54+/-11.74 pg x mL(-1) x mg tissue(-1)) compared with normal, sex- and age-matched control rats (37.54+/-1.18 pg x mL(-1) x mg tissue(-1)). Similarly, the adrenaline content in diabetic rat pancreatic tissue (102.69+/-20.24 pg x mL(-1) mg tissue(-1)) was markedly greater (p < 0.003) compared with sex- and age-matched controls (35+/-9.23 pg x mL(-1) x mg tissue(-1)). In contrast, 5-hydroxyindole acetic acid decreased significantly (p < 0.0002) in diabetic pancreatic tissue (13.41+/-0.87 pg x mL(-1) x mg tissue(-1)) compared with controls (80.72+/-1.46 pg x mL(-1) x mg tissue(-1)). The plasma levels of these catecholamines also increased slightly but not significantly in diabetic rats compared with controls. These results suggest that diabetes is associated with increased noradrenaline and adrenaline and decreased 5-hydroxyindole acetic acid pancreatic tissue levels. These disturbances in catecholamine metabolism may play a role in the pathogenesis of the acute and chronic complications of diabetes mellitus.