ARS | Publication request: Green Tea Increases Insulin Sensitivity and Decreases Brain Oxidative Stress in Fructose Fed Rats

Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: December 9, 2007
Publication Date: April 1, 2008
Citation: Roussel, A., Hininger, I., Coves, S., Cao, H., Anderson, R.A. 2008. Green Tea Increases Insulin Sensitivity and Decreases Brain Oxidative Stress in Fructose Fed Rats. Journal of Federation of American Societies for Experimental Biology. 22:445.4.

Technical Abstract: Hyperglycemia and insulin resistance are leading causes of early brain alterations. Our objective was to investigate the in vivo effects of green tea extract on insulin sensitivity, insulin signaling, and brain oxidative stress using an experimental rodent model of diet-induced insulin resistance, the fructose-fed rat. Wistar rats, 10 per group, received a fructose rich diet (FD) or FD plus 1g green tea extract/kg diet. After consuming tea extracts, plasma insulin decreased from 412 ± 100 to 13 ± 28 pmol/L. There were also associated decreases in glucose and triglycerides. Real-time PCR measurements showed that increases in insulin sensitivity were associated with an up-regulation of GLUT4, insulin receptor, IRS-2, glycogen synthetase kinase, p-110 phosphoinositol kinase (PI3-K), and protein kinase B in the liver. Addition of green tea extract to the diet resulted in significant decreases in lipid oxidation and DNA oxidative damage in brain tissue while sulfhydryl groups and glutathione remained unchanged. Ferric-reducing/antioxidant power (FRAP) in brain was also enhanced. This study shows that green tea extract protected against brain oxidative damage and suggests possible neuroprotective effects against insulin resistance-induced, early oxidative brain alterations. (Funded by USDA/ARS and Unilever, France).