Bisphenol A Impairs Hepatic Glucose Sensing in C57BL/6 Male Mice

AIMS/HYPOTHESIS Glucose sensing (eg. glucokinase activity) becomes impaired in the development of type 2 diabetes, the etiology of which is unclear. Estrogen can stimulate glucokinase activity, whereas the pervasive environmental pollutant bisphenol A (BPA) can inhibit estrogen action, hence we aimed to determine the effect of BPA on glucokinase activity directly. METHODS To evaluate a potential acute effect on hepatic glucokinase activity, BPA in water (n = 5) vs. water alone (n = 5) was administered at the EPA's purported "safe dose" (50 µg/kg) by gavage to lean 6-month old male C57BL/6 mice. Two hours later, animals were euthanized and hepatic glucokinase activity measured over glucose levels from 1-20 mmol/l in liver homogenate. To determine the effect of chronic BPA exposure on hepatic glucokinase activity, lean 6-month old male C57BL/6 mice were provided with water (n = 15) or water with 1.75 mM BPA (∼50 µg/kg/day; n = 14) for 2 weeks. Following the 2-week exposure, animals were euthanized and glucokinase activity measured as above. RESULTS Hepatic glucokinase activity was signficantly suppressed after 2 hours in animals given an oral BPA bolus compared to those who received only water (p = 0.002-0.029 at glucose 5-20 mmol/l; overall treatment effect p<0.001). Exposure to BPA over 2 weeks also suppressed hepatic glucokinase activity in exposed vs. unexposed mice (overall treatment effect, p = 0.003). In both experiments, the Hill coefficient was higher and Vmax lower in mice treated with BPA. CONCLUSIONS/INTERPRETATION Both acute and chronic exposure to BPA significantly impair hepatic glucokinase activity and function. These findings identify a potential mechanism for how BPA may increase risk for diabetes.