Effect of sulfur dioxide on active and passive avoidance in experimental diabetes mellitus:: Relation to oxidant stress and antioxidant enzymes

The effect of sulfur dioxide (SO2) on hippocampus antioxidant status, lipid peroxidation and learning and memory was investigated in diabetic rats. A total of 40 rats were divided into four equal groups: Control (C), SO2 + C (SO2), diabetic (DM) and SO2 + D (DMSO2). Experimental diabetes mellitus (DM) was induced by i.v injection of alloxan with a dose of 50 mg/kg body weight. Ten ppm SO2 was administered to the rats in the sulfur dioxide groups in an exposure chamber. Exposure occurred 1 h/d, 7 d/wk, for 6 wk; control rats were exposed to filtered air during the same time periods. SO2 exposure, while markedly increasing Cu-Zn Superoxide dismutase activity, significantly decreased glutathione peroxidase activity in diabetic and non-diabetic groups compared with the C group; hippocampus catalase activity was unaltered. Hippocampus thiobarbituric acid reactive substances (TBARS) were found to be elevated in all experimental groups with respect to control group. The active avoidance training results indicated that diabetic condition has been associated with learning and memory impairment. SO2 exposure caused deficits of learning and memory. Diabetes mellitus-induced impairment of learning and memory were potentiated by SO2 exposure. These findings suggest that exposure to SO2 by increasing lipid peroxidation, can change antioxidant enzyme activities and can elevated intensity of deficits of learning and memory in diabetic rats.