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[Effects of fluoride on osteoclastic activity of rats in vitro].

OBJECTIVE
To investigate the effects of fluoride on activities of tartrate-resistant acid phosphate (TRAP) and matrix metalloproteinase-9 (MMP-9) in rat osteoclasts cultured in vitro.


METHODS
Osteoclast was isolated mechanically from long bones of neonatal rats and cultured in vitro. Histochemical stain was applied to detect the effects of fluoride on activities of TRAP and in-situ hybridization was used to study the expression of MMP-9 mRNA in rat osteoclasts in vitro.


RESULTS
Number of TRAP positive cells was 154.2, 160.0, 170.6, 179.0 and 180.0 per cm(2), respectively for the rats with varied doses of fluoride, in a dose-response pattern but without statistical significance. The expression of MMP-9 mRNA increased with elevating dose of fluoride, especially in the rats with 1.00, 2.00 and 4.00 mg/L of fluoride, to 94.50, 94.64 and 104.97, respectively, significantly different from those in control group.


CONCLUSIONS
Fluoride can enhance the MMP-9 mRNA expression in cultured osteoclasts of rats.