Possible Protective Effect of Onion Supplementation on Hepatic Functional and Structural Alterations Induced by Cholestasis

Abstract
Background: Cholestasis is the obstruction or the reduction in bile flow that results in intrahepatic accumulation of bile constituents, which progresses to develop liver pathology. Common bile duct ligation (BDL) in rodents is an experimental model of cholestasis that has been carried out in research for many years. BDL model of cholestatic liver injury involves other mechanisms, including oxidative stress, inflammation, and fibrogenesis. Antioxidant, anti-inflammatory or antiapop-totic properties gained much interest for the amelioration of liver dysfunction.
Aim of Study: The aim of this study is to assess the possible protective effects of onion supplementation on hepatic struc-tural and functional alterations induced by BDL in rats, which reflect the effects of cholestasis resulting from intrahepatic accumulation of bile.
Material and Methods: Thirty adult female Wistar albino rats were randomly and equally allocated into three groups: (1) Control group, (2) BDL group; subjected to ligation of the common bile duct and (3) Onion-supplemented BDL groups (O-BDL). Both control and BDL groups received distilled water (solvent for onion powder) daily by gavage for 4 weeks. Onion-supplemented BDL group (O-BDL); subjected to ligation of the common bile duct and then received 500mg/kg of onion powder dissolved in distilled water, daily by gavage for 4 weeks. At the end of the experimental period, plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), direct bilirubin, total proteins, total antioxidant capacity (TAC), tumor necrosis factor-a  (TNF-a), and hepatic tissue level of malondialdehyde (MDA) and transforming growth factor-b1 (TGF-b1) were measured for all groups. In addition, his-topathological examination of liver tissue samples was per-formed for the three groups.
Results: Plasma levels of ALT, AST, ALP, direct bilirubin, TNF-a  and hepatic tissue levels of MDA and TGF-b1 were significantly increased and TAC was significantly decreased in the BDL group compared to the control group. In addition, altered architecture was detected in hepatic tissue samples of BDL group. Onion supplementation significantly decreased the plasma levels of ALT, AST, ALP, direct bilirubin, TNF-a and hepatic tissue levels of MDA and TGF-b1 in the O-BDL group when compared to the BDL group. Total proteins level was not significantly different among all the studied groups. In addition in O-BDL group, histopathological exam-ination of liver revealed near normal structure of hepatic tissue.
Conclusion: BDL induces hepatic structural alterations and functional disturbances. Onion supplementation inhibits inflammation and oxidative insults that associate BDL, and subsequently protects against BDL-induced liver injury.