Effect of lithium on hepatic lipid peroxidation and antioxidative enzymes under different dietary protein regimens

Lithium in the form of lithium carbonate was administered at a dose level of 1.1 g kg(-1) food to rats fed normal (18% protein), low-protein (LP; 8%) and high-protein (HP; 30%) diets for a period of 1 month. A highly significant (53%) increase in the level of lipid peroxidation (LPO) was observed in protein-deficient rats but this increase was marginal in rats fed an HP diet (18%). Lithium treatment of rats fed a normal diet caused a marked decrease (22%) in LPO. Lithium administration to rats fed an LP diet also reduced the raised levels of LPO to the extent of 16%. Furthermore, lithium treatment normalized the HP-induced increase in the levels of LPO. The activities of glutathione peroxidase (GPx), catalase and superoxide dismutase (SOD) were reduced significantly in protein-deficient rats. On the other hand, an HP diet caused a decrease in SOD activity only. The activities of GPx and catalase were appreciably enhanced in lithium-treated rats. Lithium treatment to LP-fed rat markedly increased GPx activity and brought the decreased levels of SOD and catalase to within normal limits. Lithium administration to HP-fed rats did not cause any significant alteration in the activities of these antioxidative enzymes.