title: Coexistence of hyperlipidemia and acute cerebral ischemia/reperfusion induces severe liver damage in a rat model.
abstract: OBJECTIVE
  To investigate the correlation of hyperlipemia (HL) and acute cerebral ischemia/reperfusion (I/R) injury on liver damage and its mechanism.
  
  
  METHODS
  Rats were divided into 4 groups: control, HL, I/R and HL+I/R. After the induction of HL via a high-fat diet for 18 wk, middle cerebral artery occlusion was followed by 24 h of reperfusion to capture I/R. Serum alanine transaminase (ALT) and aspartate aminotransferase (AST) were analyzed as part of liver function tests and liver damage was further assessed by histological examination. Hepatocyte apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. The expression of genes related to apoptosis (caspase-3, bcl-2) was assayed by immunohistochemistry and Western blotting. Serum tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1) and liver mitochondrial superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA) and Ca(2+) levels were measured to determine inflammatory and oxidative/antioxidative status respectively. Microsomal hydroxylase activity of the cytochrome P450 2E1 (CYP2E1)-containing enzyme was measured with aniline as the substrate, and CYP2E1 expression in the liver tissue and microsome was determined by immunohistochemistry and Western blotting respectively.
  
  
  RESULTS
  HL alone induced by high-fat diet for 18 wk resulted in liver damage, indicated by histopathological analysis, and a considerable increase in serum ALT (25.13 ± 16.90 vs 9.56 ± 1.99, P < 0.01) and AST levels (18.01 ± 10.00 vs 11.33 ± 4.17, P < 0.05) compared with control. Moreover, HL alone induced hepatocyte apoptosis, which was determined by increased TUNEL-positive cells (4.47 ± 0.45 vs 1.5 ± 0.22, P < 0.01), higher caspase-3 and lower bcl-2 expression. Interestingly, compared with those in control, HL or I/R groups, massive increases of serum ALT (93.62 ± 24.00 vs 9.56 ± 1.99, 25.13 ± 16.90 or 12.93 ± 6.14, P < 0.01) and AST (82.32 ± 26.92 vs 11.33 ± 4.17, 18.01 ± 10.00 or 14.00 ± 6.19, P < 0.01) levels in HL+I/R group were observed suggesting severe liver damage, which was confirmed by liver histology. In addition, HL combined with I/R also caused significantly increased hepatocyte apoptosis, as evidenced by increased TUNEL-positive cells (6.20 ± 0.29 vs 1.5 ± 0.22, 4.47 ± 0.45 or 1.97 ± 0.47, P < 0.01), elevated expression of caspase-3 and lower expression of bcl-2. Furthermore, when compared to HL or I/R alone, HL plus I/R enhanced serum TNF-α, IL-1, liver mitochondrial MDA and Ca(2+) levels, suppressed SOD and GSH-Px in liver mitochondria, and markedly up-regulated the activity (11.76 ± 2.36 vs 4.77 ± 2.31 or 3.11 ± 1.35, P < 0.01) and expression (3.24 ± 0.38 vs 1.98 ± 0.88 or 1.72 ± 0.58, P < 0.01) of CYP2E1 in liver.
  
  
  CONCLUSIONS
  The coexistence of HL and acute cerebral I/R induces severe liver damage, suggesting that cerebral ischemic stroke would exaggerate the damage of liver caused by HL. This effect is possibly due to enhanced CYP2E1 induction which further promotes oxidative damage, inflammation and hepatocyte apoptosis.
authors.affiliation: Department of Pharmacology, College of Medicine, Wuhan University of Science and Technology, Wuhan, Hubei Province, China.
authors.forename: Wei-Hong
authors.initials: WH
authors.lastname: Gong
authors.forename: Wen-Xia
authors.initials: WX
authors.lastname: Zheng
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Shi-Hui
authors.initials: SH
authors.lastname: Chen
authors.forename: Bo
authors.initials: B
authors.lastname: Pang
authors.forename: Xia-Min
authors.initials: XM
authors.lastname: Hu
authors.forename: Xiao-Lu
authors.initials: XL
authors.lastname: Cao
mesh_terms: D000208:Acute Disease; D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D017209:Apoptosis; D001219:Aspartate Aminotransferases / Q000097:blood; D015415:Biomarkers / Q000097:blood; D015153:Blotting, Western; D001921:Brain / Q000098:blood supply*; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D019392:Cytochrome P-450 CYP2E1 / Q000378:metabolism; D059305:Diet, High-Fat; D004195:Disease Models, Animal; D005979:Glutathione Peroxidase / Q000378:metabolism; D006949:Hyperlipidemias / Q000150:complications* / Q000209:etiology / Q000378:metabolism; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D020244:Infarction, Middle Cerebral Artery / Q000150:complications; D007375:Interleukin-1 / Q000097:blood; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008107:Liver Diseases / Q000097:blood / Q000209:etiology* / Q000473:pathology; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000150:complications* / Q000209:etiology / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D015415:Biomarkers; D007375:Interleukin-1; D019253:Proto-Oncogene Proteins c-bcl-2; D014409:Tumor Necrosis Factor-alpha; D008315:Malondialdehyde; D005979:Glutathione Peroxidase; D019392:Cytochrome P-450 CYP2E1; D013482:Superoxide Dismutase; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; C505410:Casp3 protein, rat; D053148:Caspase 3; D002118:Calcium