Rats with mild bile duct ligation show hepatic encephalopathy with cognitive and motor impairment in the absence of cirrhosis: effects of alcohol ingestion.

Abstract

Studies in animal models allow identifying mechanisms and treatments for cognitive and motor alterations in hepatic encephalopathy (HE). Liver diseases leading to HE in humans have different aetiologies (alcoholic, viral, etc.). The International Society for Hepatic Encephalopathy points out that satisfactory model for HE resulting from alcoholic cirrhosis are lacking. This work aimed to develop and characterize an animal model for HE in alcoholic liver cirrhosis. To potentiate the effects of alcohol on liver we administered it (5, 8 or 10% in drinking water) to rats showing mild liver damage induced by "mild" bile duct ligation (MBDL), obtained by sectioning 3 out of 5 bile ducts. MBDL rats show increased markers of cholestasis and liver damage, hyperammonemia and inflammation. MBDL rats also show motor in-coordination, hypokinesia, impaired learning ability in a Y maze and reduced spatial memory in the Morris water maze. Ingesting 10% ethanol does not induce relevant liver damage in control rats but potentiates liver damage in MBDL rats. In contrast, ethanol did not enhance the biochemical or neurological alterations in MBDL rats. This supports that the combination of certain levels of hyperammonemia and inflammation is enough to induce mild cognitive impairment, even in the absence of liver cirrhosis. Rats with MBDL and MBDL-OH survived more than 3 months, allowing performing long-term studies on cognitive and motor alterations and on underlying mechanisms. MBDL-OH rats are a good model to study the mechanisms of ethanol-induced liver cirrhosis and the factors making the liver susceptible to ethanol damage.