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 μg/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 (5μg/kg/d), lower than the tolerable daily intake of 50 μg/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 TNFα, 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.

Prolactin plays an important role in maintaining a normal glucose homeostasis during pregnancy and beyond. Studies investigating the association between prolactin and type 2 diabetes beyond pregnancy are rare and none is prospective. We aimed to examine whether prolactin associates with type 2 diabetes prospectively in a Chinese population. In 2009, 2,377 participants aged 40 years or older were enrolled from Shanghai, China. Among 1,596 diabetes-free participants at baseline, 1,510 completed the follow-up investigation in 2013. Participants who had a fasting plasma glucose ≥126 mg/dL and/or a 2-hour plasma glucose ≥200 mg/dL during a 75-g oral glucose tolerance test had a definite diagnosis of type 2 diabetes or received antidiabetic therapies during follow-up were classified as having type 2 diabetes. During a mean follow-up of 3.7 years, 189 new cases of type 2 diabetes were documented. After multivariate adjustment, women in the highest quartile of prolactin showed the lowest risk for diabetes compared with those in the lowest quartile (hazard ratio = 0.48, 95% confidence interval: 0.26, 0.90). However, such significant associations were not observed in men. Prolactin may be a mediator in the pathogenesis of type 2 diabetes in women; however, more studies are needed to elucidate the underlying sex-specific mechanism.

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