Fluoride Action Network


Effects of fluoride (as NaF) on cell cycle, DNA content, and apoptosis of mouse fetal long bone cultures were examined and analyzed by flow cytometry (FCM). The results showed that NaF at 2.5–5.0 µg/mL (2.5–5.0 ppm) had only slight effects on the DNA content and cell cycle distributions. At 10.0 µg/mL, however, NaF increased the number of cells in S phase but did not change the frequency of the G0/G1 and G2/M phase. At 20.0 µg /mL NaF not only increased the number of cells in S phase but also decreased the frequency of the G2/M phase. Cell proliferation was also influenced. At 2.5–10.0 µg/mL NaF did not induce increased apoptosis, but the number of apoptotic cells was significantly increased at 20.0 µg NaF/mL. Therefore F damage to bone may involve promoting apoptosis and disordering cell cycle distributions. Although the differences in DNA content, cell cycle distributions, and apoptosis between controls and the two lower NaF concentrations were not statistically significant, there was evidence of hormesis (paradoxical stimulatory) effects. The results indicate that F exerts a dual influence on osteocytes.