Abstract: Objective To study antagonistic effect of selenium on sodium fluoride-induced apoptosis of NRK-52E cells.Methods NRK-52E cells were cultured and divided into following groups:a control group,two sodium fluoride (NaF)-treated (5,20 mg/L) groups,two sodium selenite (Na₂SeO₃)-treated (17.1,34.2 μg/L) groups,and four NaF+Na₂SeO₃-treated (5 or 20 mg/L NaF+17.1 or 34.2 μg/L Na₂SeO₃) groups.Cell apoptosis was detected by flow cytometry 72 hours after the treatments.Protein expressions of adenosine monophosphate-activated protein kinase (AMPK) and related mitochondria pathway proteins were determined using Western blot.Results Compared to the control group(5.97±0.09%),the cell apoptosis rate of the 5 and 20 mg/L NaF-treated groups (7.92±0.24% and 11.06±0.17%) were remarkably increased (P<0.05),while the rates of 20 mg/L NaF+17.1 and 34.2 g/L Na₂SeO₃-treated groups (8.46±0.09% and 9.88±0.08%) were statistically significantly decreased compared to that of the 20 mg/L NaF-treated groups (both P<0.05).Compared to those of the control group,the expression levels of phosphorylated-AMPK (0.73±0.16),bax (0.99±0.16),cytochrome C (Cyt-C)(0.73±0.08),caspase-9 (1.17±0.17),and caspase-3 (1.51±0.42) were obviously up-regulated in 20 mg/L NaF-treated group (P<0.05).Compared to those of the 20 mg/L NaF-treated group,the expression levels of phosphorylated -AMPK(046±0.12,0.48±0.15),bax(0.55±0.09,0.61±0.16),Cyt-C (0.30±0.06,0.34±0.05),caspase-9 (0.76±0.11,0.40±0.12),caspase-3 (0.35±0.1,0.27±0.04) were down-regulated in 20 mg/L NaF+17.1 and 34.2 g/L Na₂SeO₃-treated groups (all P<0.05).Conclusion Fluoride can induce apoptosis in NRK-52E cells and the effect can be ameliorated by selenium by regulation of AMPK mediated mitochondrial pathway.