The increase of lipid peroxidation in rat adjuvant arthritis and its inhibition by superoxide dismutase.

Adjuvant arthritis was induced in rats by the injection of Mycobacterium tuberculosis, and its severity was scored according to the macroscopic findings of the legs, tail, and ears. The average score so obtained was lower in SOD-injected rats than in the control group. The depression of albumin/globulin ratio was inhibited significantly in rats treated with 10.0 mg/kg of SOD. The levels of acid phosphatase and beta-glucuronidase were elevated after the administration of an adjuvant, and these lysosomal enzymes showed a remarkable increase in the control rats, while the elevation was inhibited in rats injected with 10.0 mg/kg of SOD. The levels of TBA-reactive substances in the sera and synovia were elevated at 2 weeks after the injection of adjuvant and decreased thereafter. In rats injected with 5.0 mg/kg or 10.0 mg/kg of SOD, the increase in both serum and synovial levels of TBA reactants was inhibited significantly. These observations suggest that the aggravation of adjuvant arthritis may be associated with lipid peroxidation due to superoxide, and that SOD may be beneficial for the treatment of arthritis.