Lactobacillus rhamnosus GG improves glucose tolerance through alleviating ER stress and suppressing macrophage activation in db/db mice

Although recent studies have reported that Lactobacillus rhamnosus GG (LGG), the most extensively studied probiotic strain, exerts an anti -hyperglycemic effect on several rodent models, the underlying mechanism remains unclear. In this study, twenty male C57BL/KsJdb/db (db/db) mice were divided into 2 groups, LGG-treated and control group, which received a daily dose of LGG (1 x 10(8) CFU per mouse) and PBS orally for 4 weeks, respectively. We observed that glucose tolerance was significantly improved in LGG-treated db/db mice. Insulin-stimulated Akt phosphorylation and GLUT4 translocation were higher in skeletal muscle of LGG-treated mice relative to their controls. It was also observed that LGG treatment caused significant reductions in endoplasmic reticulum (ER) stress in skeletal muscle and M1-like macrophage activation in white adipose tissues. Our results indicate that the anti-diabetic effect of LGG in db/db mice is associated with alleviated ER stress and suppressed macrophage activation, resulting in enhanced insulin sensitivity. These findings suggest a therapeutic potential of probiotics for prevention and treatment of type 2 diabetes.