cytochrome-c-t and Cholestasis

This study clarified the role of Cygb, the fourth globin in mammals originally discovered in rat hepatic stellate cells (HSCs), in cholestatic liver disease. Bile duct ligation (BDL) augmented inflammatory reactions as revealed by increased infiltrating neutrophils, CD68

Topics: Animals; Carrier Proteins; Caspase 3; Cholestasis; Cytochromes c; Cytoglobin; Globins; Hepatocytes; Liver Cirrhosis; Male; Membrane Glycoproteins; Mice; Mice, Inbred C57BL; Neprilysin; Nitric Oxide

Endoplasmic reticulum (ER) stress is involved in the development of several liver diseases and tumors. This study investigated the underlying mechanisms of α-naphthyl isothiocyanate (ANIT)-induced liver injury with cholestasis in mice and found ER stress contributes to the injury. All animals were randomly divided into three groups. In the ANIT-intoxicated group, mice were intragastrically given 100mg/kg ANIT (dissolved in corn oil), while the other groups received an equal volume of vehicle as control. After 24 and 48h of ANIT administration, blood samples and liver tissues of all animals were collected for serum biochemistry and hepatic histopathological examinations to evaluate liver injuries with cholestasis. Hepatocellular apoptosis was assessed by the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. The expression of hepatic ER stress-related markers was determined by real-time PCR, immunohistochemical assay and Western blot. ANIT was found to significantly induce liver injury with cholestasis compared with control mice as evidenced by the increase of serum transaminases and total bilirubin (TBil), and histopathological changes in mice. ANIT remarkably induced hepatocellular apoptosis, upregulated the expression of caspase-9 and cytochrome c, and inhibited the gene and protein expression of proliferating cell nuclear antigen (PCNA). The gene expression of ER stress-related markers, including glucose-regulated protein 78 (GRP78), protein kinase R-like ER kinase (PERK), eukaryotic initiation factor 2α (eIF2α), inositol requiring enzyme-1α (IRE-1α) and activating transcription factor 6 (ATF6) was upregulated by ANIT in mice. ANIT also upregulated the protein expression of GRP78 and activated the phosphorylation of IRE1. These results suggested that ANIT induced liver injury with cholestasis partly due to its ability to activate the ER stress pathway.

Topics: Animals; Apoptosis; Caspase 9; Chemical and Drug Induced Liver Injury; Cholestasis; Cytochromes c; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Isocyanates; Liver; Male; Mice; Mice, Inbred ICR; Naphthalenes

Hydrophobic bile acids are implicated in the pathogenesis of cholestatic liver disorders through mechanisms involving oxidative stress and mitochondrial dysfunction. Antioxidants ameliorate bile acid-induced cytotoxicity in rat hepatocyte suspensions. The purpose of the current study was to evaluate the potential protective role of beta-carotene (betaC), a putative fat-soluble antioxidant that is reduced in patients with cholestasis, against bile acid-induced hepatotoxicity. In freshly isolated rat hepatocyte suspensions that were exposed to the toxic hydrophobic bile acid glycochenodeoxycholic acid (100 or 500 microM), betaC (100 microM) decreased generation of reactive oxygen species by >50%, similar to the inhibition afforded by alpha-tocopherol. Commensurate with this antioxidant effect, 100 microM betaC also protected hepatocytes against both glycochenodeoxycholic acid-induced cellular necrosis and apoptosis, which was associated with reduction in caspase 3 activation, inhibition of mitochondrial cytochrome c release in rat hepatocytes, and prevention of the mitochondrial permeability transition in both liver mitochondria and rat hepatocytes. A lower concentration of betaC (50 microM) produced similar antioxidant and anti-apoptotic protection but with less inhibition against cell necrosis, suggesting that the higher concentration of betaC may have conferred additional cytoprotection not directly related to its antioxidant function. These results demonstrate that the antioxidant effects of betaC may provide hepatoprotection against cholestatic liver injury by preventing bile acid-induced oxidative stress and mitochondrial perturbations.

Topics: Animals; Antioxidants; Apoptosis; beta Carotene; Bile Acids and Salts; Caspase 3; Caspases; Cholestasis; Cytochromes c; Cytosol; Enzyme Activation; Flow Cytometry; Glycochenodeoxycholic Acid; Hepatocytes; Immunoblotting; Liver; Membrane Potentials; Mitochondria; Mitochondria, Liver; Necrosis; Oxidative Stress; Rats; Reactive Oxygen Species; Time Factors