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 dete rmine whether the pancreatic tissue content of catecholamines is altered af ter the onset of diabetes. Experimental diabetes was induced by intraperito neal injection of streptozotocin (60 mg/kg body weight), Four weeks after t he induction of diabetes, pancreatic tissue fragments were taken from the t ail end of the pancreas and processed for catecholamine content using the h igh-performance liquid chromatography method. Immunohistochemical analysis showed that the pancreata of diabetic rats contained more tyrosine hydroxy] ase-positive nerves compared with controls. Pancreatic noradrenaline conten t, expressed as the mean +/- SD, was significantly (p < 0.03) greater in di abetic rats (54 +/- 11.74 pg.mL(-1) mg tissue(-1)) compared with normal, se x- and age-matched control rats (37.54 +/- 1.18 pg . mL(-1).mg tissue(-1)). Similarly, the adrenaline content in diabetic rat pancreatic tissue (102.6 9 +/- 20.24 pg.mL(-1).mg tissue(-1)) was markedly greater (p < 0.003) compa red with sex- and age-matched controls (35 +/- 9.23 pg.mL(-1).mg tissue(-1) ). In contrast, 5-hydroxyindole acetic acid decreased significantly (p < 0. 0002) in diabetic pancreatic tissue (13.41 +/- 0.87 pg.mL(-1).mg tissue(-1) ) compared with controls (80.72 +/- 1.46 pg.mL(-1).mg tissue(-1)). The plas ma levels of these catecholamines also increased slightly but not significa ntly in diabetic rats compared with controls. These results suggest that di abetes is associated with increased noradrenaline and adrenaline and decrea sed 5-hydroxyindole acetic acid pancreatic tissue levels. These disturbance s in catecholamine metabolism may play a role in the pathogenesis of the ac ute and chronic complications of diabetes mellitus.