Selenium as a modulator of membrane stability parameters and surface changes during the initiation phase of 1,2-dimethylhydrazine induced colorectal carcinogenesis.

The present study evaluated the modulatory potential of selenium on colonic surface abnormalities and membrane fluidity changes following 1,2-dimethylhydrazine (DMH) induced colon carcinogenesis. Rats were segregated into four groups viz., normal control, DMH treated, selenium treated, and DMH + selenium treated. Initiation of molecular events leading to colon carcinogenesis was started following weekly subcutaneous injections of DMH (30 mg/Kg body weight) for 10 weeks. Selenium in the form of sodium selenite was supplemented to rats at a dose level of 1 PPM in drinking water, ad libitum for the entire duration of the study. Brush border membranes were isolated from the colon of rats and the viscosity as well as fluidity parameters were assessed using the membrane extrinsic fluorophore pyrene. DMH treatment resulted in a significant increase in lipid peroxidation. Reduced glutathione levels (GSH) and the activities of glutathione reductase (GR), glutathione transferase (GST), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were found to be significantly decreased following DMH treatment. On the other hand, supplementation with selenium to DMH treated rats resulted in a significant decrease in the levels of lipid peroxidation but caused a significant increase in the levels of GSH as well in the activities of GR, GST, SOD, CAT, and GPx. The results further, demonstrated a marked decrease in membrane microviscosity following DMH treatment. On the other hand, a significant increase was observed in the excimer/monomer ratio and fluidity parameter of DMH treated rats when compared to normal control rats. However, the alterations in membrane microviscosity and the fluidity parameters were significantly restored following selenium treatment. Further, histological as well as colon surface alterations were also observed following DMH treatment, which however were greatly prevented upon selenium co-administration. The study, therefore, concludes that selenium proves as a useful in modulating the colonic surface abnormalities and membrane stability following DMH induced colon carcinogenesis.