Effect of tetrahydrocurcumin on insulin receptor s

Authors: Pidaran Murugan Leelavinothan Pari Chippada Appa Rao

Publish Date: 2008/03/01

Volume: 33, Issue: 1, Pages: 63-72

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Abstract

Curcumin is the most active component of turmeric It is believed that curcumin is a potent antioxidant and antiinflammatory agent Tetrahydrocurcumin THC is one of the major metabolites of curcumin and exhibits many of the same physiological and pharmacological activities as curcumin and in some systems may exert greater antioxidant activity than curcumin Using circulating erythrocytes as the cellular mode the insulinbinding effect of THC and curcumin was investigated Streptozotocin STZnicotinamideinduced male Wistar rats were used as the experimental models THC 80 mg/kg body weight was administered orally for 45 days The effect of THC on blood glucose plasma insulin and insulin binding to its receptor on the cell membrane of erythrocytes were studied Mean specific binding of insulin was significantly lowered in diabetic rats with a decrease in plasma insulin This was due to a significant decrease in mean insulin receptors Erythrocytes from diabetic rats showed a decreased ability for insulinreceptor binding when compared with THCtreated diabetic rats Scatchard analysis demonstrated that the decrease in insulin binding was accounted for by a decrease in insulin receptor sites per cell with erythrocytes of diabetic rats having less insulin receptor sites per cell than THCtreated rats High affinity Kd1 low affinity Kd2 and kinetic analyses revealed an increase in the average receptor affinity of erythrocytes from THCtreated rats compared with those of diabetic rats These results suggest that acute alteration of the insulin receptor on the membranes of erythrocytes occurred in diabetic rats Treatment with THC significantly improved specific insulin binding to the receptors with receptor numbers and affinity binding reaching nearnormal levels Our study suggests the mechanism by which THC increases the number of total cellular insulin binding sites resulting in a significant increase in plasma insulin The effect of THC is more prominent than that of curcumin

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