The differential role of selenium in diabetes -a question of the compound and the applied concentration

摘要

In the present study the impact of selenium supplementation as selenite and selenate at the recommended level (0.2 mg/kg diet) and at supranutritional doses (1.0 mg/kg diet and 35% of the LD_(50)) on the expression and activity of protein tyrosine phosphatases (PTPs) as important factors in the development of insulin resistance and obesity were studied in type II diabetic dbdb mice and healthy rats. The results suggest that selenium possesses a differentiated role with regard to insulin resistance. The supplementation of selenium at the recommended level (0.2 mg/kg diet) and at a supranutritional level (1.0 mg/kg diet = 5-fold recommended amount) led to an increase in both the expression and the activities of protein tyrosine phosphatases thus possibly having an increasing influence on the development of insulin resistance and obesity. The supplementation of even higher doses of selenite and selenate (up to the 25-fold of the recommended amount) also effected an increase in PTP1B expression but at this dose the inhibitory effect of selenate metabolites on PTP activity seems to compensate for the enhanced expression and thus only selenate supplementation in very high doses might have a beneficial effect on the treatment of insulin resistance and obesity.