Animal models of alcoholic liver disease

Ethanol dosage regimes in studies of ethanol toxicity: influence of nutrition and surgical interventions

In this review we consider some of the practical facets of acute and chronic drug regimes. In particular, we illustrate our arguments with specific reference to alcohol and draw attention to methodological constraints that might alter biochemical or physiological processes. These includes the imposition of nutritional abnormalities and surgical procedures. These two areas are highlighted because there is evidence to show that they have marked influences on metabolic parameters, exemplified by tissue protein synthesis. In general, there is no controversy as to methods for acute studies with alcohol, although some reports have failed to investigate whether intravenous, intragastric or intraperitoneal regimes more accurately mimic the clinical situation. With regard to chronic feeding regimes, evidence is provided to support the argument that, currently, the most appropriate feeding protocol ensures that both control and treated groups receive identical amounts of nutrients albeit with differences in the calories apportioned to ethanol, which is substituted by isocaloric glucose or other carbohydrates in controls. However, there are still other methods being employed: these are subject to misinterpretation as the principle of ensuring that control and ethanol-fed rats receive identical amounts of nutrients, is ignored. In this review we also draw attention to the fact that surgical procedures, which are often employed to facilitate the measurement of body parameters (for example, implantation of cannulae), themselves alter tissue metabolism. The importance of this relates to the concept of metabolic superimposition, which implicates interacting responses when two or more stresses (i.e. surgery and drug administration) are superimposed.

Hepatic haemodynamics and reticuloendothelial function in the rat in response to chronic ethanol administration

This study investigated the effects of chronic ethanol intake on hepatic haemodynamics and reticuloendothelial system function in the rat. Comparisons were also made with blood flow to pancreas, kidney, spleen, lung and skin. Male Wistar rats, approximately 0.15 kg initial body weight, were fed a diet containing 35% of the total calories as ethanol. Controls were pair-fed identical amounts of the same diet in which ethanol was replaced by isocaloric glucose. The hepatic perfusion index and reticuloendothelial function was determined with [(99m) Tc]-labelled sulphur colloid [(99m) Tc]-SC) and blood flow with radiolabelled microspheres under anaesthesia. After 4-5 weeks the weights of liver and skin of alcohol fed rats decreased by 10% (p= 0.040) and 23% (p= 0.024), respectively, compared to controls and there was a small increase in kidney weight (15%, p = 0.001). Blood flow to liver, pancreas, kidney, spleen, lung and skin was not altered significantly by chronic alcohol administration, irrespective of whether the data were expressed as a percentage of cardiac output, blood flow per minute per organ or blood flow per minute per g tissue weight (p > 0.113 in all instances). However, there was a significant increase in splenic reticuloendothelial system activity (+ 121%, p = 0.018). Hepatic reticuloendothelial system activity was also increased (+ 22%, p = 0.061). Chronic alcohol administration resulted in significant increases in portal pressure (+ 55%, p = 0.042) and portal venous resistance (+ 66%, p = 0.001), but portal venous inflow and hepatic perfusion index were not altered compared to controls The results of this study indicated that chronic alcohol administration did not alter visceral blood flow significantly, but did increase portal pressure, portal vascular resistance and reticuloendothelial system activity.