The toxicity mechanism of sodium fluoride on fertility in female rats.

Recognition of the harmful effects of sodium fluoride (NaF) on human reproduction is increasing, especially as it relates to female reproduction. However, the mechanism by which NaF interferes with female reproduction is unclear. The aims of the present study were to investigate the effects of fluoride exposure on female fertility and to elucidate the mechanisms underlying these effects. Female Sprague-Dawley rats were divided into three groups: one control group and two NaF-treated groups (100 and 200 mg/L in the drinking water for 12 weeks). Several parameters were evaluated, including: (i) fluoride concentrations; (ii) estrogen (E2) and progesterone (P) concentrations; (iii) estrogen receptor alpha protein (ERα); (iv) progesterone receptor (PgR) protein; (v) follicle-stimulating hormone receptor (FSHR) and luteinizing hormone receptor (LHR) protein. The results indicated that administration of NaF lead to significant decreases in E2 and P levels in the serum and in the expression of FSHR protein. In addition, fluoride exposure significantly increased Erα and PgR protein expression levels and LHR protein expression. These results suggest that the reproductive hormone reduction and the abnormalities of related receptor proteins expression are important factors underlying the decreased fertility observed in female rats that have been exposed to NaF.