Taurine modifies insulin signaling enzymes in the fructose-fed insulin resistant rats

Abstract

High fructose feeding induces insulin resistance and hyperinsulinemia in rats. The present study was proposed to elucidate the derangements in the insulin signaling pathway in high fructose-fed rats and whether taurine, a sulphur-containing amino acid could improve insulin action by modulating the signal transduction pathway. Male Wistar rats of body weight 170-190 g were divided into 4 groups of 6 rats each. Control rats received control diet and water ad libitum. Fructose fed animals received high fructose diet (> 60% of total calories) and water ad libitum. Fructose + taurine rats received fructose diet and 2% taurine solution ad libitum. Control + taurine rats received control diet and 2% taurine solution ad libitum. After the experimental period of 30 days, the effects of taurine on certain parameters on glucose metabolism were determined. The activities of protein tyrosine kinase (PTK) and protein tyrosine phosphatase (PTP) were assayed in liver. The activities of the glycolytic enzymes were significantly lower while the activities of the gluconeogenic enzymes were higher in untreated fructose-fed rats as compared to control animals. Depletion of liver glycogen was observed in fructose-fed rats. Fructose-fed rats showed alterations in the activities of insulin signaling enzymes PTK and PTP. Taurine administration improved insulin sensitivity and controlled hyperglycemia and hyperinsulinemia in fructose-fed rats. Taurine treatment also restored the glucose metabolizing enzyme activities in fructose-fed rats. Taurine supplementation might have a beneficial effect in overcoming insulin resistance and its associated abnormalities by modifying the post-receptor events of insulin action.