梓醇对高脂诱导小鼠非酒精性脂肪肝的干预作用

目的 通过高脂饮食诱导小鼠非酒精性脂肪肝病(NAFLD)模型,探讨梓醇对NAFLD的干预作用及可能的作用机制。方法 选用SPF级C57BL/6J雄性小鼠60只,随机分为正常对照组(低脂饲料),模型组(高脂饲料),梓醇低(100 mg/kg)、中(200 mg/kg)、高(400 mg/kg)3个剂量组和阳性对照阿托伐他汀钙组(30 mg/kg)。采用高脂饮食建立小鼠NAFLD模型,同时灌胃给予梓醇或阿托伐他汀钙,各组均连续灌胃18周,每周称量体重1次。实验结束后测定各组小鼠体重、肝重,血清总胆固醇(TC)、三酰甘油(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、丙氨酸氨基转移酶(ALT)和天冬氨酸氨基转移酶(AST)含量;油红O和HE染色法观察肝组织脂质蓄积和脂肪变性;ELISA法检测血清中炎症因子肿瘤坏死因子-α(TNF-α)、白细胞介素(IL)-1β和IL-6的含量;Western-blot法检测肝组织中核因子κB(NF-κB)p65、核因子抑制蛋白α(IκBα)、B淋巴细胞瘤-2(Bcl-2)、B淋巴细胞瘤-2相关x蛋白(Bax)和半胱天冬酶-3蛋白表达水平。结果 与模型组相比,梓醇各组处理后小鼠体重(P均=0.001)、肝指数(P=0.083,P=0.001,P=0.001)、ALT(P=0.004,P=0.001,P=0.001)和AST(P=0.008,P=0.001,P=0.001)含量显著降低,中、高剂量组血清TC(P=0.005,P=0.001)、TG(P均=0.001)、LDL-C(P均=0.001)显著降低,高剂量组HDL-C(P=0.009)含量显著升高;病理结果显示NAFLD小鼠肝脂肪变性和损伤程度明显减轻;ELISA结果显示梓醇显著抑制NAFLD小鼠血清炎性因子TNF-α、IL-1β和IL-6的释放(P均=0.001);Western-blot结果显示梓醇干预后,NAFLD小鼠肝组织中NF-κB p65(P=0.014,P=0.001,P=0.001)和半胱天冬酶-3(P均=0.001)蛋白表达水平显著降低,IκBα蛋白表达水平显著增加(P=0.028,P=0.001,P=0.001),高剂量组中Bcl-2/Bax比值显著升高(P=0.003)。结论 梓醇可降低高脂饮食诱导的非酒精性脂肪肝小鼠体重、肝指数和肝脏脂质的蓄积程度及调节血脂紊乱,并能抑制炎症因子的释放和肝细胞凋亡,从而对高脂饮食诱导的NAFLD发挥预防作用。

Intervention of Catalpol on High-fat Diet Induced Nonalcoholic Fatty Liver Disease in Mice

Objective To investigate the effect of catalpol on high-fat diet(HFD)-induced nonalcoholic fatty liver disease(NAFLD)and its underlying molecular mechanisms.Methods Sixty C57BL/6J male mice were randomly divided into six groups:control group;HFD group;HFD+catalpol(100 mg/kg)group;HFD+catalpol(200 mg/kg)group;HFD+catalpol(400 mg/kg)group;and HFD+atorvastatin calcium(ATC)(30 mg/kg)group.The control group was fed a normal diet containing 4.4 kJ/g fat,whereas the other five groups were fed a high-fat diet containing 19.8 kJ/g fat.Mice in the catalpol or ATC treatment groups were administered by gavage for different doses of catalpol or ATC,whereas other mice were treated with saline.Body weight was measured once a week.Experiments were terminated after 18 weeks,and blood and liver samples were collected after an overnight fast(12 hours)for analysis.The body weight and liver weight were measured and the levels of serum total cholesterol(TC),triglyceride(TG),high-density lipoprotein cholesterol(HDL-C),low-density lipoprotein cholesterol(LDL-C),alanine aminotransferase(ALT),and aspartate transaminase(AST)as well as inflammatory factors tumor necrosis factor-α(TNF-α),interleukin(IL)-1β,and IL-6 were determined by commercially available kits.Liver sections were stained with Oil Red O and HE to investigate the lipid accumulation and histopathological changes.The protein expressions of nuclear factor kappa-B(NF-κB)p65,inhibitor of nuclear factor kappa-B α(IκBα),B-cell lymphoma-2(Bcl-2),Bcl-2 associated x protein(Bax),and Caspase-3 were determined by Western blot.Results Compared to the model group,the body weight gains(all P=0.001),liver index(P=0.008,P=0.001,P=0.001),ALT(P=0.004,P=0.001,P=0.001),and AST(P=0.008,P=0.001,P=0.001)were significantly decreased in catalpol treatment groups,and the serum levels of TC(P=0.005,P=0.001),TG (all P=0.001),and LDL-C(all P=0.001)were also significantly decreased in middle and high dose groups,and the serum level of HDL-C was significantly increased in high group(P=0.009).Moreover,compared to the model group,the degree of liver injury and lipid accumulation were obviously decreased in the catalpol treatment groups according to the pathology.Similarly,the release of inflammatory factors was significantly inhibited by the treatment with catalpol.The results of Western blot showed that the protein levels of NF-κB p65(P=0.014,P=0.001,P=0.001)and Caspase-3(all P=0.001)in the livers of HFD-fed mice were significantly reduced by catalpol treatment.In addition,the protein level of IκBα(P=0.028,P=0.001,P=0.001)and the ratio of Bcl-2/Bax in high dose group(P=0.003)was increased by treatment with catalpol.Conclusion Catalpol can effectively improve the body weight gains,liver index,dyslipidemia,and lipid accumulation in HFD-fed mice and inhibit the release of inflammatory factors and hepatocyte apoptosis,thereby preventing the development of NAFLD induced by HFD.