Objective: To investigate the effect of natural hyperoxic environment on liver lipid metabolism and liver function based on the bile acid-farnesoid X receptor pathway in sub-healthy rats. Methods: Forty adult male Wistar rats were randomly divided into control group (n = 10) and sub-healthy model group (n = 30). The control group was fed a normal diet, and the model group was fed a high-fat-sugar diet with limited daily activities for 5 weeks. The sub-healthy model was successfully established and the feeding conditions were restored. The hyperoxic intervention group (healthy group) were placed in a natural hyperoxic environment for 7 days. The rats feeding status in the spontaneous recovery group were unchanged. The appearance and exhaustive swimming time were compared before and after in healthy rats. Peripheral blood was collected for biochemical measurement. The fluorescence intensity of FXR and peroxisome proliferator activated receptor α (PPAR α) in liver tissue was detected by fluorescence double staining. Real-time fluorescent semi-quantitative PCR and Western blot were used to detect the RNA and protein expression condition of bile acid-FXR signaling pathway related indicators (FXR, PPARα, and SREBP-1c) in liver tissues. Results: Compared with the control group, the model group had gained body weight, and the vitality was decreased, while triglycerides [TG, (1.18 ± 0.20) mmol/L vs. (0.65 ± 0.12) mmol/L] and total cholesterol [TC, (1.23 ± 0.29) mmol/L vs. (1.00 ± 0.25) mmol/L] level was increased, (P < 0.05), which suggests the presence of hepatic steatosis. TG and TC level in the healthy group and spontaneous recovery group were lower than the model group, and the differences between the healthy group and the model group were statistically significant (P < 0.05). Compared with the model group, the expression of FXR and PPARα in the liver of the healthy and the spontaneous recovery group was enhanced, while the expression of the sterol regulatory element binding protein 1c (SREBP-1c) was decreased. FXR and PPARα mRNA levels in the healthy group and the model group were (9.27 ± 0.26 vs. 6.77 ± 0.20), and (9.71 ± 0.21 vs. 7.09 ± 0.24), P < 0.01, respectively. Compared with the model group, spontaneous recovery group mRNA levels were 7.99 ± 0.30 and 8.44 ± 0.28, P < 0.05, respectively. FXR and SREBP-1c protein levels between the healthy group and the model group were (1.30 ± 0.19 vs.0.43 ± 0.28), and (1.56 ± 0.22 vs. 2.43 ± 0.19), P < 0.01, respectively. Compared with the model group, the FXR and SREBP-1c protein levels of the spontaneous recovery group were 0.81 ± 0.33 vs. 2.10 ± 0.38, P < 0.05, respectively. In addition, natural hyperoxic environment had enhanced liver lipid metabolism and improved lipid disorders. Conclusion: The natural hyperoxic environment have the ability to regulate liver lipid metabolism and can improve mild hyperlipidemia to a certain extent.
目的： 基于胆汁酸-法尼醇X受体（FXR）-脂质代谢通路探讨天然高负氧离子对亚健康大鼠肝脏功能的影响。 方法： 将40只成年雄性Wistar大鼠，随机分为对照组10只、亚健康模型组30只。对照组予普通饲料，模型组予高脂高糖饮食及限制日常活动，造模时长5周。亚健康模型建立成功，恢复饲养条件，高负氧离子干预组（康养组）带往天然高负氧离子环境康养7 d，自然恢复组大鼠喂养地点不变。比较康养前后大鼠外观、力竭游泳时间。收集外周血进行血生物化学检测。荧光双染法检测肝组织FXR及过氧化物酶体增殖物激活受体α（PPARα）荧光强度。实时荧光半定量PCR及蛋白质印迹法(Western blot)检测肝组织胆汁酸-FXR信号通路相关指标[FXR、PPARα、固醇调节元件结合蛋白1c（SREBP-1c）]的RNA及蛋白表达情况。多组间均数比较采用单因素方差分析。 结果： 与对照组相比，模型组大鼠体质量增加，活力下降，甘油三酯[TG，(1.18±0.20）mmol/L与（0.65±0.12）mmol/L]及总胆固醇[TC，(1.23±0.29）mmol/L与（1.00±0.25）mmol/L]水平升高，P值均< 0.05，提示存在肝脂肪变性；康养组与自然恢复组大鼠TG、TC水平均较模型组下降，康养组与模型组比较，差异均有统计学意义（P < 0.05）。与模型组相比，康养组及自然恢复组大鼠肝脏内FXR、PPARα的表达增强，而SREBP-1c的表达下降；康养组与模型组FXR、PPARα的mRNA相对表达水平分别为9.27±0.26与6.77±0.20、9.71±0.21与7.09±0.24，P值均< 0.01；自然恢复组FXR、PPARα的mRNA相对表达水平分别为7.99±0.30、8.44±0.28，与模型组比较，P值均< 0.05。康养组与模型组的FXR、SREBP-1c的蛋白水平比较，分别为1.30±0.19与0.43±0.28、1.56±0.22与2.43±0.19，P值均< 0.01；自然恢复组的FXR、SREBP-1c蛋白水平分别为0.81±0.33、2.10±0.38，与模型组比较，P值均< 0.05。表明天然高负氧离子环境可增强肝脏脂质代谢能力，改善脂质紊乱情况。 结论： 天然高负氧离子具有调节肝脏脂质代谢的能力，对轻度高脂血症有一定的改善作用。.
Keywords: Lipid metabolism; Natural high negative oxygen ions; Sub-healthy.