Objective To observe the changes of fluoride content in serum,bone and urine after rats were exposed to single fluoride,single aluminum or fluoride combined with aluminum and to investigate the effects of different doses of aluminum on fluoride accumulation and excretion in rats.Methods Male Wistar rats were randomly divided into 9 groups based on 3 × 3 factorial design.Different doses of fluoride(NaF,0,50,200 mg/L)and(or) aluminum(AlCl3,0,100,200 mg/L) were administered to rats in each group by drinking water.The rats took food and water ad libitum during the experimental period.After feeding for 18 weeks,rats with obvious dental fluorosis were determined as successful establishment of animal model.The fluoride content in the serum,bones and urine were measured.Results Fluoride affected the fluoride content in serum,bones and urine(F=166.74,577.81,160.96,all P ＜ 0.01 ).The interaction of fluoride and aluminum on serum,bone and urinary fluoride were statistically significant (F =7.95,5.13,6.94,all P ＜ 0.01 ).When the fluoride level was 50 mg/L,the serum fluoride contents were [ (0.08 ± 0.03) and (0.08 ± 0.02) mg/L] in the aluminum levels of 0 and 100 mg/L groups,which was higher than that of the aluminum level of 200 mg/L group[ (0.04 ± 0.01)mg/L,F=7.14,5.78.all P＜ 0.05].The bone fluoride content in the 0 mg/L aluminum level group[ (1996.53 ± 383.73) mg/kg] was higher than that of the 100 and 200 mg/L groups[(1252.51 ± 189.08),( 1160.63 ± 129.63) mg/kg,F=20.54,24.56,all P ＜ 0.01 ].When the fluoride level was 200 mg/L,the bone fluoride contents were decreased with the increasing doses of aluminum[ (4668.70 ± 887.67),(3920.30 ± 528.31 ),(3297.64 ± 396.04) mg/kg].Between any two groups,the differences were statistically significant (F =15.59,52.31,14.38,all P ＜ 0.01 ).When the fluoride level was 50 mg/L,the urinary fluoride content in the 0 mg/L aluminum level group[ (34.054 ± 9.30)mg/L] was higher than that of the 100,200 mg/L groups[( 14.81 ± 6.32),(14.67 ± 3.42) mg/L,F =25.30,24.32,all P ＜ 0.01 ].When the fluoride level was 200 mg/L,the urinary fluoride contents in the 0,100 mg/L aluminum level groups[ (57.14 ± 21.38),(51.75 ± 8.39)mg/L] were higher than that of the 200 mg/L group[(34.839 ± 9.30) mg/L,F=30.04,20.31,all P ＜ 0.01 ].Conclusions Aluminum is an antagonist of fluoride.The antagonism could be enhanced as the dose of aluminum increased.In this study,aluminum could effectively counteract the absorption of fluoride in rat model when the ratio of fluoride to aluminum is 1 ∶ 2.