Abstract
Previous studies demonstrate that kudzu root extract and its major isoflavone (puerarin) improve glucose metabolism in animal models of insulin resistance and type 2 diabetes; however, these beneficial effects have not been investigated in normal glycemic mice. The present study investigates the effect of acute and chronic kudzu root extract supplementation on glucose tolerance in normoglycemic CD-1 mice. Male, adult CD-1 mice were fed a phytoestrogen-free diet containing 0.2% or 0.0% kudzu root extract for 6 weeks. Thereafter, they were acutely administered kudzu root extract (75 mg/kg BW; oral) or vehicle followed by a glucose challenge (2 g/kg BW; oral). In control fed mice, the acute glucose challenge increased blood glucose ~300% after 30 minutes, and acute kudzu root extract administration significantly blunted this response by ~50%. In mice chronically fed a kudzu-supplemented diet, glucose tolerance was improved, and acute treatment caused no additional improvement. Irrespective of treatment, all mice were normoglycemic at the start of each glucose challenge. Administration of insulin resulted in a larger decrease in blood glucose in chronic kudzu-supplemented compared to control mice. Co-administration of phloridzin (a specific inhibitor of SGLT-mediated glucose uptake), improved glucose tolerance in acutely kudzu-treated mice but had no significant effect on glucose tolerance in chronically treated mice. These results indicate that both acute and chronic administration of kudzu root extract improves glucose tolerance in a normal glycemic mouse strain and that the effects of chronic kudzu feeding may be mediated, in part, by enhanced insulin sensitivity (chronic) and inhibition of sodium dependent glucose transport.