脂肪肝动物模型述评

脂肪肝是一种由多种病因引起的获得性疾病,当脂质[主要为甘油三酯(TG)]在肝细胞内大量沉积,超过肝重量(浸重)的10％(正常值为3％～5％)或在组织学上,超过50％的肝实质脂肪化时,称为脂肪肝。严重者脂肪含量可以高至40％～50％。引起本病的原因是多方面的,国际肝脏病信息学小组将其归纳为:①营养因素引起的脂肪肝,其中包括恶性营养不良病(多见于儿童)。

脂肝乐胶囊治疗痰湿瘀阻型脂肪肝的临床与实验研究

为探讨脂肝乐胶囊治疗痰湿瘀阻型脂肪肝疗效机理。方法：运用脂肝乐胶囊治疗痰湿瘀阻型脂肪肝患者１４６例（治疗组），并与用东宝肝素片治疗的４７例（对照组）作对照，实验研究观察两药对乙硫氨酸所致脂肪肝模型及大鼠高脂血症模型的影响。结果：治疗组在减轻或去除症状、改变Ｂ超回声，降脂，降酶，改善血液流变性等方面明显优于对照组（Ｐ＜０．０５～０．０１）。动物实验显示：该药可降低血脂，抑制脂肪在肝脏沉积，３个用药组在降低甘油三酯方面与模型组比较有显著性差异（Ｐ＜０．０１）。结论：脂肝乐胶囊具有明显降低甘油三酯，抑制脂肪在肝脏沉积，改善血液流变性的作用。

参苓白术散和膈下逐瘀汤对实验性脂肪肝早期的影响

目的:比较早期应用活血化瘀法和健脾益气法两种治疗法则对高脂饲料导致的大鼠脂肪肝模型的影响。方法:饲喂高脂饲料复制大鼠脂肪肝模型,造模的同时分别以健脾益气法代表方参苓白术散和活血化瘀法代表方膈下逐瘀汤进行干预,观察两方对模型大鼠早期的血脂、肝脂、肝功能以及超氧化物歧化酶(SOD)、丙二醛(MDA)、血小板聚集的影响。结果:两方均能降低模型大鼠的血脂、肝脂水平,从作用强度来看,膈下逐瘀汤作用优于参苓白术散,膈下逐瘀汤能够改善肝功能,参苓白术散对肝功能作用不明显;两方均能升高SOD,作用以膈下逐瘀汤更为显著,对MDA两方均无明显影响;参苓白术散对模型大鼠血小板聚集没有明显作用,而膈下逐瘀汤早期应用能够显著对抗血小板聚集。结论:早期应用活血化瘀法对改善脂肪肝预后有重要意义。

Effect of Sinai San decoction on the development of non-alcoholic steatohepatitis in rats

AIM: To explore the effect of Sinai san decoction on the development of non-alcoholic steatohepatitis induced by CCL4 combined with a fat-rich diet in rats.METHODS: Twenty-seven Sprague-Dawley rats were divided into three groups randomly: control group (n = 9),model group (n = 9) and treatment group (n = 9). The rats of model group and treatment group were given small dosage of CCL4 combined with a fat-rich diet, andthose of control group were given normal diet. After four weeks of fat-rich diet feeding, the rats of treatment group were given Sinai san decoction. The serum levels of aminotransferase and lipid were measured, and the pathology of livers was observed by HE staining after the rats were sacrificed at eight weeks.RESULTS: The rats' livers presented the pathology of steatosis and inflammation with higher serum levels of ALT and AST in the model group. In the treatment group the serum ALT and AST levels decreased significantly and were close to the control group. The hepatic inflammation scores also decreased markedly, but were still higher than those of control group. And the degree of hepatocyte steatosis was similar to that of model group.CONCLUSION: Sinai san decoction may ameliorate the hepatic inflammation of rats with steatohepatitis induced by small dosage of CCL4 combined with a fat-rich diet,but does not prevent the development of hepatocyte steatosis.

N-acetylcysteine attenuates oxidative stress and liver pathology in rats with non-alcoholic steatohepatitis

AIM: To evaluate attenuating properties of N-acetylcysteine (NAC) on oxidative stress and liver pathology in rats with non-alcoholic steatohepatitis (NASH). METHODS: Male Sprague-Dawley rats were randomly divided into three groups. Group 1 (control, n = 8) was free accessed to regular dry rat chow (RC) for 6 wk. Group 2 (NASH, n = 8) was fed with 100% fat diet for 6 wk. Group 3 (NASH + NAC20, n = 9) was fed with 100% fat diet plus 20 mg/kg per day of NAC orally for 6 wk. All rats were sacrificed to collect blood and liver samples at the end of the study. RESULTS: The levels of total glutathione (GSH) and hepatic malondialdehyde (MDA) were increased significantly in the NASH group as compared with the control group (GSH; 2066.7 ± 93.2 vs 1337.5 ± 31.5 μmol/L and MDA; 209.9± 43.9 vs 3.8 ±1.7 μmol/g protein, respectively, P < 0.05). Liver histopathology from group 2 showed moderate to severe macrovesicular steatosis, hepatocyte ballooning, and necroinflammation. NAC treatment improved the level of GSH (1394.8 ± 81.2 μmol/L, P < 0.05), it did not affect MDA (150.1 ± 27.0 μmol/g protein), but led to a decrease in fat deposition and necroinflammation. CONCLUSION: NAC treatment could attenuate oxidative stress and improve liver histology in rats with NASH.

Animal models of nonalcoholic fatty liver disease/nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease(NAFLD) is a condition in which excess fat accumulates in the liver of a patient without a history of alcohol abuse.Nonalcoholic steatohepatitis(NASH),a severe form of NAFLD,can progress to liver cirrhosis and hepatocellular carcinoma.NAFLD is regarded as a hepatic manifestation of metabolic syndrome and incidence has been increasing worldwide in line with the increased prevalence of obesity,type 2 diabetes,and hyperlipemia.Animal models of NAFLD/NASH give crucial information,not only in elucidating pathogenesis of NAFLD/NASH but also in examining therapeutic effects of various agents.An ideal model of NAFLD/NASH should correctly reflect both hepatic histopathology and pathophysiology of human NAFLD/NASH.Animal models of NAFLD/NASH are divided into genetic,dietary,and combination models.In this paper,we review commonly used animal models of NAFLD/NASH referring to their advantages and disadvantages.

Genetically modified mouse models for the study of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease(NAFLD) is associated with obesity,insulin resistance,and type 2 diabetes.NAFLD represents a large spectrum of diseases ranging from(1) fatty liver(hepatic steatosis);(2) steatosis with inflammation and necrosis;to(3) cirrhosis.The animal models to study NAFLD/nonalcoholic steatohepatitis(NASH) are extremely useful,as there are still many events to be elucidated in the pathology of NASH.The study of the established animal models has provided many clues in the pathogenesis of steatosis and steatohepatitis,but these remain incompletely understood.The different mouse models can be classified in two large groups.The first one includes genetically modified(transgenic or knockout) mice that spontaneously develop liver disease,and the second one includes mice that acquire the disease after dietary or pharmacological manipulation.Although the molecular mechanism leading to the development of hepatic steatosis in the pathogenesis of NAFLD is complex,genetically modified animal models may be a key for the treatment of NAFLD.Ideal animal models for NASH should closely resemble the pathological characteristics observed in humans.To date,no single animal model has encompassed the full spectrum of human disease progression,but they can imitate particular characteristics of human disease.Therefore,it is important that the researchers choose the appropriate animal model.This review discusses various genetically modified animal models developed and used in research on NAFLD.

Alleviation of ischemia/reperfusion injury in ob/ob mice by inhibiting UCP-2 expression in fatty liver

AIM： To investigate the protective effect of target suppression of uncoupling protein-2 （UCP-2） on ischemia/ reperfusion （I/R） injury in fatty liver in ob/ob mice. METHODS： Plasmids suppressing UCP-2 expression were constructed, and transfected into fatty liver cells cultured in vitro and the ob/ob mouse I/R injury model. Serum tumor necrosis factor （TNF）-α levels, UCP-2 mRNA expression, alanine aminotransferase （ALT） levels in ob/ob mice were tested, and the pathological changes in fatty liver were observed in experimental and control groups. RESULTS： In ob/ob mouse I/R models, serum TNF-α levels were significantly higher than in normal controls. After the plasmids were transfected into the cultured cells and animal models, expression of UCP-2 rnRNA was significantly reduced as compared with that in the control group （2^1.56± 0.15 vs 2^-0.45± 0.15, p 〈 0.05）. In ob/ob mouse models, in which expression of UCP-2 was suppressed, serum ALT levels were significantly lower than those of other groups, and pathological analysis revealed that injury of liver tissues was significantly alleviated. CONCLUSION： The target suppression of UCP-2 expression in fatty liver can alleviate the I/R injury in the ob/ob mice.

Hepatic steatosis prevents heme oxygenase-1 induction by isoflurane in the rat liver

AIM:To characterize the inductive effects of isoflurane(ISO) on hepatic heme oxygenase-1(HO-1) in an animal model of hepatic steatosis.METHODS:Lean(LEAN) and obese(FAT) Zucker rats were randomized into 4 groups:1:LEAN + pentobarbital sodium(PEN);2:LEAN + ISO;3:FAT + PEN;4:FAT + ISO.The animals were mechanically ventilated for 6 h.In vitro analyses of liver tissue included determination of HO-1 mRNA and protein expression as well as measurement of HO enzyme activity and immunohistochemical analyses.RESULTS:Compared to PEN treatment,ISO administration profoundly induced hepatic HO-1 mRNA and protein expression and significantly increased HO enzyme activity in lean Zucker rats.In contrast,no difference in HO-1 gene expression was observed after ISO or PEN anesthesia in obese Zucker rats.CONCLUSION:The present study demonstrates that ISO is an inducer of hepatic HO-1 gene expression in non-steatotic organs but failed to upregulate HO-1 in steatotic livers.

The relationship between the contents of 13 amino acids in brain tissues and the progression of NAFLD via C57BL/6 model mice

Non-alcoholic fatty liver disease(NAFLD)is the steatosis of liver parenchyma unrelated to alcoholism,autoimmunity,and viral infection.It is also a metabolism-related syndrome,which has an unseparated relationship with adipose tissue dysfunction and obesity.Hepatic encephalopathy(HE)is one of the severe complications of chronic liver disease and one of the end-stage syndromes of liver disease.Some researchers have suggested that NAFLD,like other forms of liver injury,may be related to the metabolic disorder of branched-chain amino acids(BCAAs),which have been approved to be associated with HE influencing ammonia and energy metabolism.However,several studies have revealed the relationship among amino acids in serum,HE,and chronic liver disease;there are few studies on the contents of amino acids in brain tissues of an animal model with NAFLD.In the present research,we established a NAFLD mouse model with C57 BL/6 mice and determined the contents of 13 amino acids in brain tissues of model mice by HPLC-FLD derivatization method using ortho-phthalaldehyde(OPA)to explore the relationship between the contents of amino acids in brain tissues and the progression of NAFLD.Moreover,the study showed that the changes of amino acid contents in the brain of the C57 BL/6 mice were associated with the advancement of NAFLD,and this change might be related to the mechanism of HE.