Influence of bisphenol A on intestinal mucosal barrier in rats with nonalcoholic fatty liver disease

Objective To investigate the influence of bisphenol A (BPA) , an environmental endocrine disruptor, on inflammatory response in rats with nonalcoholic fatty liver disease (NAFLD) , as well as its adverse effect on intestinal mucosal barrier. Methods A total of 18 mature male rats were randomly divided into normal group, NAFLD group, and NAFLD + BPA group, with 6 rats in each group. liver pathological changes were observed under a light microscope; ELISA was used to measure the serum levels of tumor necrosis factor-α (TNF-α) , interleukin-1β (IL-1β) , interleukin-6 (IL-6) , and interleukin-8 (IL-8) ; the terminal colorimetric analysis with Limulus amebocyte lysate was used to measure the level of endotoxin; an immunofluorescence assay was used to measure the expression of occluding protein in the intestinal mucosa; real-time PCR was used to measure the mRNA expression of ZO-1 in the intestinal mucosa. A one-way analysis of variance was used for comparison of continuous data between multiple groups, and the SNK-q test was used for further comparison between two groups. Results Liver pathological examination showed that the rat model of NAFLD was established successfully. After the 8-week treatment with 100 nmol/L BPA, compared with the normal group and the NAFLD group, the NAFLD + BPA group had significant increases in the expression of TNF-α (127. 65 ± 22. 4 pg/ml vs 64. 87 ± 10. 83 pg/ml and 92. 34 ± 10. 68 pg/ml, P < 0. 05) , IL-6 (199. 34 ± 17. 46 pg/ml vs 91. 27 ± 9. 82 pg/ml and 181. 93 ± 20. 11 pg/ml, P < 0. 05) , and IL-8 (258. 79 ± 12. 82 pg/ml vs 123. 76 ±19. 68 pg/ml and 201. 64 ± 22. 34 pg/ml, P < 0. 05) and the level of endotoxin (0. 88 ± 0. 26 EU/ml vs 0. 27 ± 0. 09 EU/ml and 0. 63 ±0. 15 EU/ml, P < 0. 05) . The NAFLD group and the NAFLD + BPA group had a significantly higher level of IL-1β than the normal group (186. 31 ± 20. 06 pg/ml and 208. 78 ± 13. 77 pg/ml vs 112. 84 ± 23. 12 pg/ml, both P < 0. 05) , but there was no significant difference between these two groups. Compared with the normal group, the NAFLD group and the NAFLD + BPA group had significant reductions in the expression of occluding protein and the mRNA expression of ZO-1 in the intestinal mucosa, and the NAFLD + BPA group had a significantly greater reduction in the mRNA expression of ZO-1 than the control group and the NAFLD group (33. 25 ± 11. 04 vs 68. 03 ± 11. 73/45. 24 ±6. 98, P < 0. 05) . Conclusion In the background of NAFLD, long-time exposure to low-dose BPA can increase the release of some inflammatory factors, promote endotoxemia, and thus damage intestinal mucosal barrier.