Acetyl-homocysteine-thiolactone-induced increase of superoxide dismutase counteracts the effect of subdiabetogenic doses of streptozocin.

Acetyl-homocysteine-thiolactone (CYT) is an organic thio compound that exerts free radical scavenger activity and increases superoxide dismutase (SOD) activity. Administration of 32 mg CYT/kg body wt/day/30 days in rats increased SOD activity in erythrocytes by 126%, and in pancreatic islets by 202%. Treatment affected only the Cu-Zn fraction of the enzyme. Transmission electron microscope observations showed that the damage to the pancreatic beta cells induced by single or multiple subdiabetogenic doses of streptozocin (STZ) (45 mg/kg body wt) was attenuated in animals treated with CYT. This protective effect was not observed with 65 mg of STZ. The experimental results seem to support the hypothesis that pancreatic beta cells are particularly vulnerable to the effect of oxygen radicals and that the cytotoxic effect of STZ is related to free radical-induced peroxidation.