Experimental Study On Alcoholic Liver Disease In Rat

Objective: To establish a relatively simple and applicable alcholic liver disease (AID) model in rats by intragastric infusion of a certain concentration and quantity of ethanol. Further study of the initiating mechanism of alcoholic Alcoholic Fibrosis (AF) was set on such model. Methodes: This study was consisted of two steps :experiment I and II. In experiment T all rats were served with balanced diat while rats in model group were administrated ethanol by gavage at a dose of 8g kg-1 d-1 three times daily at a concentration of 40v/v for four weeks. In experiment II rats in model group were treated same as experiment I. in the first four weeks then the dose and concent ration of ethanol was shifted to 8g kg-1 d-1 and 45v/v respectively. Rats were sacrificed at the end of each experient. Aspartate aminotransferase(AST) and alanine aminotransferase (ALT)values in serum wers detected in each group to evaluate the injure extent of hepatocytes. Direct Red was used in histchemistry stain to visualize collagen deposition in extracellular matr i x. Tumor necrotic Factor-alpha and alpha-sooth muscul act in ant ibody were adopted in immunohistochemistry stain to reveal the activation of Kupper cells in liver and the circulating monocytes recruitment and transformation and proliferation of Hepatic stellate cells. Ultrastructures of hepatocytes were observed by electron microscopy.Results: (1) Serum determination: ALT and AST levels were increased significantly (P<0.05) in model groups than those in control groups in experiment I and II. (2) Hematoxylin-Eosin (H-E) stain: mild or medialsteatosis, dotted necrosis and infiltration of inflammatory cells were evident in experiment I and these ethanol-induced injury changes were severe in experiment II except slight fatty lesion after eight weeks continual ethanol administration under light miscropy. (3) Histochemistry detection with Direct Red: collagen were deposited around central vein in liver lobules in experiment I while the collagen stretch to the sinusoid in experiment II and in some area fibrosis septa were formed. (4) Immunohistochemical stain of a-SM: a-SMA positive cells were seldom expressed around terminal tributaries vein of hepatic in experiment I and the number of positive cells increased in experiment II with stretch to the sinusoid. TNF- a secreting cells detection: positive cells were seldom found in model of experiment I but abundantly expressed in model group of experiment II. (5) Ultras trueture observation: lipid bubbles and abnormal mitochondria and marlod proliferation of smooth endoplasmic reticulum in livers of rats fed ethanol were revealed in experiment I model group and all these changes were observed besides with deposition of collagen bundles around hepatic cells in experiment II. Conclusion: Kupffer cells are activated by the continuous stimulation of ethanol. Proliferated Kupffer cells are mportant in the process of ethanol - induced hepatic fibrosis by releasing some cytokines in which TNI;- a is critical thus Hepatic stellate cells were transformed to Myofibroblast lead to excessive secretion of collagen bundles; this process was initiated at fourth week and reinforced at eighth week in such rat model.