Reactive oxygen species (ROS) have been suggested to be contributory factors in
complications of diabetes mellitus. In the present study, we investigated the generation of
superoxide, the
lipid peroxide level measured as
thiobarbituric acid reactive substances, the
vasorelaxation of isolated
thoracic aorta and the iNOS expression in
kidney of
streptozotocin induced diabetic
rats.
Sprague Dawley rats were divided into four groups control, ascorbate (400 mg/kg
rat weight daily in
drinking water), diabetic (
single dose of 50 mg of STZ/kg i.p.) and diabetic simultaneously fed with ascorbate for 12 wk.
Rats in groups were studied at tri-weekly intervals (0 to 12 wk). Diabetic
rats were evaluated periodically with changes of
plasma glucose levels and
body weight. The ascorbate supplimentation attenuated the development of
hyperglycemia and
weight loss induced by STZ
injection in
rats. In the present experimental condition, the ascorbate supplimentation had no significant effect on
plasma glucose levels and changes in
body weight of normal rate. The
superoxide generation, formation of thiobarbituric
acid reactive substance and iNOS expression in
kidney were significantly increased in STZ-treated
rats that were decreased by ascorbate supplimentation. The ascorbate supplimentation had no effect on
vasorelaxation of isolated
thoracic aorta. These results indicate that ascorbate supplimentation may exert an inhibitory effect on STZ-induced oxidative
tissue damage through
protection of
pancreatic islet cells by scavanging
reactive oxygen species. The ascorbate supplimentation may possibly attenuate the renal complication of
diabetes mellitus.