The correlation between exposure to BPA and the decrease of the ovarian reserve

This study aimed to evaluate whether exposure to bisphenol A (BPA) affects the ovarian reserve.

Follicular fluid (FF) was collected from diminished ovarian reserve (DOR) and non-DOR patients who underwent in vitro fertilization or intracytoplasmic sperm injection. ELISA was used to detect the BPA and hormones levels in 54 cases of DOR and 67 cases of non-DOR. A total of 64, five-week-old SPF C57BL/6 mice were randomly divided into four groups, of which three were exposed to 5, 50, and 500 µg/kg/day of BPA solution, and one was exposed to con oil only as the control. The weight and estrus of each mouse were recorded daily, and the E2 hormone and anti-Müllerian hormone (AMH) in the serum were detected by ELISA. The expression levels of AMH mRNA and protein were also detected.

The BPA levels in the FF of DOR patients were significantly higher than those of non-DOR patients (234.048±81.736 ng/L vs. 193.300±67.225 ng/L, P<0.01); The AMH and E2 levels in the FF of DOR patients were lower than those of non-DOR patients ([555.689+74.224] pg/ml vs. [587.178+77.731] pg/ml, P<0.05, [209.720+31.556] pg/ml vs. [221.845+32.632] pg/ml, P<0.05). The BPA concentration was correlated with the AMH and E2 levels in the FF (r_{BPA & AMH}=-0.312, P<0.05; r_{BPA & E2}=-0.290, P<0.05); in the animal experiment, the levels of serum AMH and E2 as well as the expression levels of the AMH gene and protein in the BPA treatment group displayed downward trends. The concentrations of the 5 and 500 µg/kg/day groups decreased significantly (P<0.05).

The increased BPA in the FF may promote the pathogenesis of DOR. BPA did not present a single-dose effect on the mouse ovary. Sub-chronic exposure to a low dose of BPA can reduce the ovarian reserve in female mice.