Bisphenol A Promotes Adiposity and Inflammation in a Nonmonotonic Dose-response Way in 5-week-old Male and Female C57BL/6J Mice Fed a Low-calorie Diet

A growing body of epidemiological research show that Bisphenol A (BPA) is positively correlated with obesity and metabolic disorders. However, the mechanisms of BPA on adiposity remain largely unknown. In this study, we found that 5-week-old male and female C57BL/6J mice exposed to four dosages of BPA (5, 50, 500, and 5000 mu g/kg/d) by oral intake for 30 days showed significantly increased body weight and fat mass in a nonmonotonic dose-dependent manner when fed a chow diet. The effect occurred even at the lowest concentration (5 mu g/kg/d), lower than the tolerable daily intake of 50 mu g/kg/day for BPA. However, no significant difference in body weight and fat mass was observed in either male or female mice fed a high-fat diet, suggesting that BPA may interact with diet in promoting obesity risk. In vitro study showed that BPA treatment drives the differentiation of white adipocyte progenitors from the stromal vascular fraction, partially through glucocorticoid receptor. BPA exposure increased circulating inflammatory factors and the local inflammation in white adipose tissues in both genders fed a chow diet, but not under high-fat diet. We further found that BPA concentration was associated with increased circulating inflammatory factors, including leptin and TNF alpha, in lean female subjects (body mass index < 23.0 kg/m(2)) but not in lean male subjects or in both sexes of overweight/obese subjects (body mass index > 25.0 kg/m(2)). In conclusion, we demonstrated the nonmonotonic dose effects of BPA on adiposity and chronic inflammation in 5-week-old mice, which is related to caloric uptake.