THE EFFECT OF SODIUM FLUORIDE INTOXICATION ON THE ESTROUS CYCLE AND OVARIAN HORMONES IN RATS

The objective of this study was to investigate the toxic effects of different concentrations of sodium fluoride (0 [control], 5, 10, 15, and 20 mg NaF/kg body weight/day) administered in drinking water for 30 days, on estrous cycle and ovarian hormones of adult female albino rats (Rattus norvegicus). The rats in the two higher dose groups (15 and 20 mg NaF/kg body weight/day) showed clinical signs of toxicity unlike those exposed to NaF at a concentration of 5 mg NaF/kg body weight/day. Body weight (bw) was significantly reduced in the rats ingesting 10 (p <= 0.05), 15 (p <= 0.001), and 20 (p <= 0.001) mg NaF/kg bw/day and ovarian weight was significantly reduced in the rats ingesting 15 (p <= 0.05) and 20 (p <= 0.001) mg NaF/kg bw/day. Vaginal secretions from the 30 female rats were collected every morning for a month and the changes in the estrous stages observed. The duration of the proestrous phase was significantly increased in the 10 mg (p <= 0.05), 15 (p <= 0.001), and 20 mg (p <= 0.001) NaF/kg bw/day groups. In the 15 and 20 mg NaF/kg bw/day groups there were significant decreases in the diestrous (p <= 0.001), estrous (p <= 0.05), and metaestrous (p <= 0.05) phases. The marked alteration in the estrous cycle was caused by decreased hormonal concentrations of luteinising hormone (LH) (p <= 0.05 in the 15 and 20 NaF/kg bw/day groups), follicle-stimulating hormone (FSH) (p <= 0.001 in the 10, 15, and 20 NaF/kg bw/day groups), and estrogen (p <= 0.05 in the 10 NaF/kg bw/day group; p <= 0.001 in the 15 and 20 NaF/kg bw/day groups). These hormones are responsible for ovulation. The results indicate that exposure of female albino rats to NaF in drinking water might have some immediate harmful effects on the reproductive system.