Effect of sodium fluoride on the expression of Bcl-2 family and osteopontin in rat renal tubular cells

Our earlier studies showed that the apoptosis of renal tubules can be induced by sodium fluoride (NaF). The present study was designed to estimated the effects of B-cell lymphoma/leukemia 2 (Bcl-2), Bcl-2-associated protein X (Bax), and osteopontin (OPN) on the apoptosis of renal tubular cells induced by NaF at different levels. The technique of reverse transcription-polymerase chain reaction and densitometer scanning volume density were used to evaluate the changes of Bcl-2, Bax, and OPN mRNA in tubular cells treated with different doses of NaF (0, 1, 5, 7.5, 12.5 mgF(-)/L) for 48 h. Compared to control, the level of Bax mRNA significantly increased at cells of the 7.5- and 12.5-mg F-/L groups and the expression of Bcl-2 mRNA obviously decreased at cells of the 5- and 7.5-mg F-/L groups. The NaF also enhanced the expression of OPN mRNA in a dose-dependent manner, but the strongest expression of OPN mRNA was observed at cells of the 7.5-mg F-/L group. The results suggested that NaF induces the apoptosis in renal tubules via activation of the Bax expression and Bcl-2 suppression; OPN probably acts as protective role against apoptosis in fluoride-treated renal cells.