沙棘熊果酸对酒精性肝损伤大鼠肝FXR信号通路的影响

目的:初步探讨沙棘熊果酸对酒精性肝损伤大鼠肝法尼醇X受体（Farnesoid X receptor, FXR）信号通路关键蛋白表达的影响。方法:6周龄SPF级SD大鼠随机分为4组，每组9只，分别为正常对照组、酒精模型组、熊果酸对照组和熊果酸+酒精组，干预时间为8周。采用苏木精-伊红（H&E）染色法观察大鼠肝组织病理学变化；测定大鼠血清中谷丙转氨酶（Alanine aminotransferase，ALT）、谷草转氨酶（Aspartateaminotransferase，AST）活力和血清总胆汁酸（Total bile acid，TBA）、肝脏甘油三酯（Triglyceride，TG）、总胆固醇（Total cholesterol，TC）含量；酶联免疫吸附（Enzyme linked immunosorbent assay，ELISA）法检测血清细胞因子肿瘤坏死因子α（Tumor necrosis factor-α，TNF-α）、白细胞介素1β（Interleukin 1β，IL-1β）、白细胞介素10（Interleukin 10，IL-10）含量；免疫印迹法（Western blotting）测定大鼠肝FXR信号通路相关蛋白表达情况。结果:与正常对照组相比，酒精模型组大鼠肝脏存在大小不一的脂肪空泡和大量炎性细胞浸润；血清ALT、AST活力，TNF-ɑ、IL-1β水平，TBA含量和肝脏TG、TC含量均显著升高（P<0.05）、IL-10水平显著下降（P<0.05）。经熊果酸干预后，肝脏脂肪变性得到明显改善，炎性细胞浸润减少；血清ALT、AST活力，TNF-ɑ、IL-1β水平，TBA含量和肝脏TG含量均有不同程度的显著下降（P<0.05），IL-10水平显著提高（P<0.05）。Western blotting结果显示，与正常对照组相比，模型组大鼠肝脏FXR蛋白表达显著降低（P<0.05），CYP7A1和SREBP-1c蛋白表达均显著升高（P<0.05）；而经熊果酸干预后，FXR蛋白表达明显提高，CYP7A1及SREBP-1c蛋白表达明显下调，且差异均具有统计学意义（P<0.05）。结论:沙棘熊果酸能够明显改善酒精诱导的肝脏损伤，其作用机制可能与上调肝FXR、抑制CYP7A1和SREBP-1c的蛋白表达，从而维胆汁酸稳态、调节脂质代谢有关。

Effect of Ursolic Acid Extracted from Hippophae rhamnoides L. on FXR Signaling Pathway in Liver of Rats with Alcoholic Liver Injury

Objective: To investigate the effect of ursolic acid extracted from Hippophae rhamnoides L. on the expression of key proteins of hepatic farnesoid X receptor (FXR) signaling pathway in rats with alcoholic liver injury. Methods: The 6-week-old SPF SD rats were divided randomly into 4 groups: The normal control group, the alcohol model group, the ursolic acid control group and the ursolic acid+alcohol group, 9 mice in each group. The rats were administered by intragastric administration for eight consecutive weeks. The pathological changes of hepatic tissues in rats was observed by hematoxylin eosin (H&E) staining. The activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and the content of total bile acid (TBA) in serum, and the content of triglyceride (TG) and total cholesterol (TC) in liver of rats were tested. The content of the serum cytokine including tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), and interleukin 10 (IL-10) was detected by enzyme linked immunosorbent assay (ELISA). The expression of FXR signal pathway related proteins in liver tissue of rats was detected by Western blotting. Results: Compared with the normal control group, there were fat vacuoles of different sizes and a large number of inflammatory cells in the liver of the alcohol model group. The activities of ALT, AST, the levels of TNF-ɑ, IL-1β, the content of TBA in serum and the content of TG, TC in liver were increased significantly (P<0.05), and the level of IL-10 was decreased significantly (P<0.05). After the ursolic acid intervention, hepatic steatosis was improved significantly and inflammatory cell infiltration was decreased. The activities of ALT, AST, the levels of TNF-ɑ, IL-1β and the content of TBA in serum and the content of TG in liver were significantly decreased in different degrees (P<0.05), and the level of IL-10 was significantly increased (P<0.05). The Western blotting results showed that compared with the normal control group, the protein expression of FXR in the model group was decreased significantly (P<0.05), while the protein expression of CYP7A1 and SREBP-1c were increased significantly (P<0.05). After ursolic acid intervention, the protein expression of FXR expression was increased significantly, while the protein expression of CYP7A1 and SREBP-1c were decreased significantly, and the difference was statistically significant (P<0.05). Conclusion: The ursolic acid extracted from Hippophae rhamnoides L. can improve alcohol induced liver injury significantly, and its mechanism may be related to up regulating hepatic FXR, inhibiting the protein expression of CYP7A1 and SREBP-1c, thus regulating bile acid homeostasis and lipid metabolism.