动物造模,药效评价,脂肪肝 z-bio 2024-09-02 451

　　(1) Method of replication: Adult rats were fed a high-fat diet containing 2% cholesterol, 10% lard, 0.3% sodium cholate, and other ingredients daily for 8 weeks, or adult rabbits were fed a high-fat diet containing 1% cholesterol and 10% lard at 40g/kg body weight and a high cholesterol diet at 80mg/kg body weight daily for 12 weeks. After modeling, whole blood was immediately drawn and liver tissue was extracted to measure total cholesterol (TC), triglycerides (TG), free fatty acids (FFA), very low-density lipoprotein (VLDL), alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), as well as the content of total cholesterol (TC), triglycerides (TG), free fatty acids (FFA), glutathione peroxidase (GSH Px), and malondialdehyde (MDA) in liver tissue. Reverse transcription polymerase chain reaction (RT-PCR) was used to measure the expression of acetyl CoA oxidase (AOX) in liver tissue, and histological examination of the liver was performed.

　　(2) Model characteristics: The serum levels of TC, TG, FFA, AST, and ALT in the model rats increased, while the liver tissue levels of TC, TG, and FFA increased and the expression of AOX increased; Hepatic lobular steatosis is characterized by large vesicular lesions, with lipid vesicles formed by the fusion of large vesicles; Fatty liver cells are most pronounced around the central vein; 100% of cases have inflammation within the lobules, mainly characterized by infiltration of monocytes and lymphocytes, with visible punctate, focal, and fragmented necrosis. The liver coefficient, serum TC, and levels of GSH Px and MDA in liver tissue of model rabbits increased; The liver is swollen, with a yellow white and greasy surface. The liver tissue has degeneration (granular degeneration or eosinophilic degeneration) and necrosis (dissolution and spot necrosis), showing focal distribution with lymphocyte infiltration, and a large number of circular lipid droplets of varying sizes can be seen filling the cytoplasm; The arrangement of liver lobules is disordered and the boundaries are unclear, but false lobules have not formed; Dysregulation of hepatic cord structure, mild proliferation of fibrous tissue, and accumulation of red blood cells between hepatic sinusoids and central veins.

　　(3) The liver is the central organ for lipid metabolism in comparative medicine. Under physiological conditions, the liver absorbs FFA from food and releases it into the bloodstream through chylomicrons or adipocytes, which is used to synthesize TG, TC, phospholipids, and glycolipids. These synthesized lipids bind to specific lipoproteins and are secreted into the plasma. When the FFA from diet or mobilization from adipose tissue sharply increases and exceeds the balance of the liver's lipid metabolism cycle, fat begins to accumulate in large quantities in liver cells, forming fatty liver. This fatty liver model is caused by long-term feeding of high-fat diet. High fat feed refers to adding a certain proportion of fatty foods, such as 5% to 20% lard, 1% to 10% cholesterol, 5% to 15% egg yolk powder, etc., to the basic feed. In order to promote the formation of lesions, sodium cholate or substances rich in unsaturated fatty acids such as corn oil and fish oil can also be added to high-fat feed, which can easily induce fatty liver with inflammation and fibrosis. Rats and rabbits are usually used as model animals for this study. When model rats are continuously fed with high-fat diet for 2-4 weeks, they may develop hyperlipidemia. After 8-12 weeks, the liver shows moderate to severe bullous steatosis with elevated transaminase levels. The establishment of a fatty liver model using rats has the advantages of convenient feeding, strong resistance, similar diet to humans, and high success rate of model replication. Since rabbits have high absorption rate of exogenous cholesterol and low clearance rate of lipid in blood, as long as they are fed with high-fat diet without additional factors, the rabbit fatty liver model can be reproduced after 12 weeks. Its pathological characteristics are that the cytoplasm of liver cells is full of lipid droplets, the liver lobule center is fibrotic and the vascular wall is atherosclerotic plaque. Compared to the model rats, the limitations of using rabbits to replicate the fatty liver model mainly include two aspects. Firstly, rabbits, as herbivores, have significant differences in lipid metabolism compared to humans. Secondly, animals have poor resistance and are prone to secondary infections and death. However, due to their simple operation method, similar lesion characteristics to humans, high success rate of model replication, and convenient blood sampling and testing, they are still widely used as fatty liver models.