Effects on levels of glutathione and some related enzymes in tissues afteran acute arsenic exposure in rats and their relationship to dietary protein deficiency

Arsenic is a potent toxin, carcinogen and modulator of antioxidant defense system. In this study, male rats of Wistar strain, maintained on either 18% or 6% protein (casein) diet, received an acute i.p. exposure to sodium ars enite (As3+) at its LD50 dose (15.86 mg/kg body weight). One hour after the arsenic exposure, glutathione (GSH) concentration was significantly deplet ed and lipid peroxidation was increased. A relationship between any two of tissue arsenic concentrations, GSH levels and lipid peroxidation values was observed only for liver when the proportional changes of respective parame ters in either of the dietary groups of animals were compared. This suggest s that, in liver, arsenic metabolism appears dependant upon the GSH concent ration. Acute arsenic exposure significantly increased the glutathione pero xidase (GPx) activity in liver of both dietary groups and in kidney of only the 18% protein-fed group of animals. The glutathione-S-transferase (GST) activity significantly decreased in liver of the 18% protein-fed animals wh ile GST increased in kidney of both the 18% and the 6% protein-fed groups. No significant change in glutathione reductase (GR) or glucose-6-phosphate dehydrogenase (G6PDH) activity was observed. In the present investigation, liver as a whole seems to be more affected in terms of GSH level and GST ac tivity. The mode of responses of GPx and GR activities as well as the unalt ered G6PDH activity might result in arsenic-induced GSH depletion and incre ase in lipid peroxidation. The animals of the 6% protein-fed group, appeare d to be affected less in terms of tissue arsenic concentration, lipid perox idation, GSH level and GST activity.