Effect of Sodium Fluoride on Reproductive Function Through Regulating Reproductive Hormone Level and Circulating SIRT1 in Female Rats.

Fluorosis causes female reproductive dysfunction with reduced fertility without established pathogenesis. To clarify the mechanism, Sprague-Dawley female rats were selected with drinking water containing 0, 50 (low), 100 (moderate), and 150 mg/L (high) sodium fluoride (NaF) for a short (2 months), medium (4 months), and long term (6 months). The water consumption and body weight of female rats were recorded daily. The effect of NaF on the estrous cycle was examined by vaginal smears and recorded in different term treatments. Female and male rats were mated in a 2:1 ratio for 1 week at 2-, 4-, and 6-month treatment time for mating performance and fertility rate. Selected female rats were executed for tissue and blood collection at different treatment terms. Twenty-four-hour urine sample from each female rat was collected using the metabolic cage. The levels of steroid hormones and silent information regulator 2 homolog 1 (SIRT1) in serum were measured by appropriate ELISA kits. Body weight of the high NaF group was significantly less during short-term treatment than that of other treatment groups or control group. Urinary fluoride concentration was increased linearly with treatment time. Treatment of NaF significantly decreased steroid hormone level while increased SIRT1 level in the serum. In addition, NaF treatment significantly decreased pregnancy rate. It is concluded that NaF inhibits the secretion of hormone and estradiol (E2) release from the ovary, thereby reducing the rate of pregnant. SIRT1 may be involved in this NaF-induced reproductive dysfunction in female rats through regulating reproductive hormone, FSH, and LH secretion.