الفهرس 
AbstractOnly 14 pages are availabe for public view
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Abstract
Liver fibrosis is one of the most widespread hepatic diseases with an increased risk of progression to cirrhosis and even hepatic carcinoma. Nevertheless, the fibrosis process is reversible at an early stage of hepatic injury, and adequate treatment would result in restoring normal liver architecture. Carvacrol (CRV) is a natural phenolic monoterpenoid with antioxidant and anti-inflammatory effects. Cilostazol (CLZ) is a selective phosphodiesterase-III (PDE-III) inhibitor with antioxidant, anti-inflammatory and antiapoptotic properties. The present study aimed to investigate the hepatoprotective effects of CRV and CLZ alone and in combination against alcoholic liver fibrosis (ALF) rat model (both offer protection in several experimental models), and the related mechanisms conceivably implicated therein, using silymarin (SLY) as a reference hepatoprotective anti-fibrotic agent. Male albino rats were used and equally divided into 6 groups (8 animals in each group); (1) Control group received 0.5% CMC daily for 6 weeks; (2) Ethanol (EtOH) group received (1 ml/100 g/P.O.) EtOH thrice per week for six weeks; (3) SLY + EtOH group received (100 mg/kg/P.O.) SLY for six weeks plus EtOH; (4) CRV + EtOH group received (70 mg/kg/P.O.) CRV for six weeks plus EtOH; (5) CLZ + EtOH group received (50 mg/kg/P.O.) CLZ for six weeks plus EtOH; (6) CRV + CLZ + EtOH group received (70 mg/kg/P.O.) CRV and (50 mg/kg/P.O.) CLZ for six weeks plus EtOH. At the end of the experiment, rats were anaesthetized to collect blood and liver tissue samples for evaluation of hepatic changes. Blood samples were used to quantify serum biomarkers of liver injury [alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and gamma glutamyl transferase (GGT)] and transforming growth factor beta 1 (TGF-β1) as a profibrotic growth factor. The liver tissue samples of rats were divided into two parts. One part was utilized for histopathological scoring and immunohistochemical assay of alpha-smooth muscle actin (α-SMA) as a marker of hepatic stellate cells (HSCs) activation. The second part was used for assessment of oxidative stress markers as hepatic malondialdehyde (MDA), reduced glutathione (GSH) and nitric oxide (NOx). Interleukin (IL)-10 as anti-inflammatory cytokine, 4-hydroxyproline (4-HYP) as a collagen synthesis indicator and hepatic sirtuin-1 (SIRT1), nuclear factor-erythroid 2-related factor 2 (Nrf2), and hemeoxygenase-1 (HO-1) gene expressions were also evaluated. The current results showed that oral administration of EtOH produced a significant elevation in serum markers of liver injury (ALT, AST, ALP and GGT), histopathological changes (fibrosis and necroinflammation scores) as well as α-SMA expression in hepatocytes. Also, there was a significant elevation in serum TGF-β1, hepatic MDA, hepatic NOx and hepatic 4-HYP with a significant depletion in hepatic GSH and IL-10 content. These effects were accompanied by a significant downregulation in the expression of hepatic SIRT1, Nrf2, and HO-1 genes compared to control group. On the other hand, rats received CRV and/or CLZ concomitantly with EtOH showed a significant reduction in serum activities of liver enzymes, histopathological changes as well as α-SMA expression in hepatocytes. A significant reduction in serum TGF-β1, hepatic MDA, hepatic NOx and hepatic 4-HYP with a significant elevation in hepatic GSH and IL-10 contents were also observed. These effects were accompanied by a significant upregulation in the expression of hepatic SIRT1, Nrf2, and HO-1 genes compared to EtOH group. Compared to SLY group, combination of CRV and CLZ showed a significant improvement of the liver function tests, histopathological features changes and hepatic α-SMA immunostaining. Additionally, there was a significant reduction in serum TGF-β1, hepatic MDA, hepatic NOx and hepatic 4-HYP with a significant elevation in hepatic GSH and IL-10 contents. A significant upregulation in the expression of hepatic SIRT1, Nrf2, and HO-1 genes was also observed. This study disclosed for the first time the hepatoprotective effects of CRV against liver fibrosis induced by EtOH in rats. Interestingly, combination of CRV and CLZ showed a significant augmented effect compared to each drug alone. These effects could be partially attributed to activation of SIRT1/Nrf2/HO-1 signaling pathway with consequent antioxidant, anti-inflammatory, and anti-fibrotic properties.