The differences in absorption and metabolism of bisphenol A between rats and mice

Objective To investigate the mechanism of the different levels of serum bisphenol A(BPA) between rat and mouse after oral administration. Methods A total of 18 specific pathogen free(SPF) male rats and 18 mice were treated with 300 mg/kg BPA by oral administration,blood samples were taken from rats and mice after BPA administration at 0.5,1.0,12.0 h time points(n =6 at each point).Serum BPA levels were quantified using fluorescence-high performance liquid chromatography (FL-HPLC)analysis. The rats and mice (n = 6, respectively ) were perfused with 100 ml of 0.1 mmol/L BPA by intestinal absorption in situ,then the BPA levels of perfusion fluid at 0.5,1.0,2.0 h time points and serum at 2.0 h after BPA perfusion were determined by FL-HPLC analysis. The levels of UDP-glucuronosyltransferase 2B1 ( UGT2B1 ) mRNA expression in the liver of rats and mice were analyzed by semi-quantitative RT-PCR and UGT2B1 enzymatic activity was determined by FL-HPLC method. The rats and mice (n = 6,respectively) were treated with 300 mg/kg BPA by omal administration after fasting 24 h,the feces were collected during 24 h and the levels of BPA in feces were determined by FL-HPLC analysis. Results At 0.5,1.0,12.0 h after oral administration at 300 mg/kg BPA, the levels of serum BPA in mice ( (66.57 ± 14.95 ), ( 51.16 ± 16.06 ), ( 22.73 ± 5.00 ) μg/ml, respectively) were significantly higher than in rats ( ( 15.63 ± 5.65 ), ( 18.34 ± 5.02 ), (7.65 ± 2.58 ) μg/ml, respectively) (F values were 50.660,17.957,8.420,respectively,P ＜ 0.05) ,the rates of absorption in mice small intestine during 0 h -,0.5 h- ,1.0-2.0 h ((10.20 ±4.20),(1.49 ±0.67),(1.31 ±0.55) μg · cm-2 · min-1 ,respectively)were higher than that in rats ((1.87 ±0.69),(0.47 ± 0.13),(0.36 ±0.08) μg · cm-2 · min-1,respectively) ( F values were 14.954,8.877,11.536, respectively, P ＜ 0.05 ), the serum BPA levels in mice( (22.64 ±4.35) μg/ml) were significantly higher than in rats ( (4.13 ±0.83) μg/ml) after 2 h perfusion with 0.1 mmol/L BPA (F = 74.643, P = 0.000), the levels of UGT2B1 mRNA expression and enzymatic activity in the rats liver were obviously higher than in the mice liver. After oral administration at 300 mg/kg BPA,the feces BPA levels of rats ( ( 1.50 ± 0.32) mg/g) were significantly higher than that of the mice((0.57 ±0.35) mg/g) (F=21.215,P=0.001) during 24 h. Conclusion The serum BPA level of mouse is significantly higher than the rat after oral administration at 300 mg/kg BPA, which may be caused by BPA high absorption rate of mouse small intestine and strong ability of BPA glucuronidation and excretion of the rat. Key words: Phenols;  Rats;  Mice;  Intestinal absorption;  Metabolism