ABSTRACT
Insulin resistance is characterized by alterations in insulin signaling components thereby resulting in reduced glucose uptake. The mechanistic role of [3beta]-stigmast-5-en-3-ol in augmenting glucose uptake to overcome insulin resistance is deciphered in this study. 16 myotubes, rat skeletal muscle model have been used to check the effect of [3beta]-stig-mast-5-en-3-ol, a plant phytosterol isolated from the ethyl acetate extract of Adathoda vasica on glucose transport. The influence of [3beta]-stigmast-5-en-3-ol on various cellular targets of insulin signaling cascade has been evaluated using inhibitors on glucose uptake as well as gene and protein expression to unravel the mechanistic action in triggering glucose uptake. [3beta]-stigmast-5-en-3-ol promoted glucose uptake in a dose dependent manner under insulin resistant condition. As assessed by inhibitor studies using Genistein [IRTK inhibitor] and Wortmannin [PI3K inhibitor], gene expression and protein expression studies using specific primers and antibodies, an activation of IR-[3, IRS-1, PI3K, AKT/PKB, PKC by both the crude and [3beta] stigmast-5-en-3-ol were observed. This suggested that [3beta]-stigmast-5-en-3-ol induced glucose uptake functions through the PI3K dependent pathway in L6 myotubes. Both, the crude and [3beta]-stigmast-5-en-3-ol activates GLUT 4 transport [evident from increased mRNA levels and redistribution of GLUT4 from intracellular membrane to plasma membrane through translocation studies]. Confocal microscopy revealed a substantial increase in redistribution of FITC tagged GLUT4 throughout the cells. Our results emphasize the insulin-like effect of [3beta]-stigmast-5-en-3-ol in stimulating glucose transport in vitro and provide evidence in its beneficial role possessing antidiabetic property apart from its existing cholesterol lowering efficacy