A BASIC APPROACH TO ASSOCIATION OF INSULIN RESISTANCE WITH TNF α IN COWS WITH FATTY LIVER

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It has been recently reported that cows with insulin resistance are sometime observed during the periparturient period, and their milk production are remarkably decreased. It is pointed out that fatty liver is closely linked to that pathogenesis. Tumor necrosis factor ct (TNFα) secreted from fatty cell is considered to be the most important factor in the insulin resistance. We designed two experiments for induction of fatty liver. In experiment-1, cows were fasted for 4 day to be fallen into negative energy balance. Moreover, as experiment-2, cows were administrated ethionine, analogous substance of methionine, to reduce the production of proteins in the liver. Insulin resistance and TNF α of used cows were analyzed in each experiment.Experiment-11. Liver triglyceride (TG) content was apparently increased after fasting.2. The increase of insulin resistance was observed in the development of fatty liver.3. Serum concentration of TNFα was not significantly changed in the fasted cow.4. In micromorphological analysis of liver, hepatic basal lamina in the cow with fatty liver remarkably became thicker compared to that in control.Experiment-21. Liver TG contents were remarkably increased in ethionine-treated cows.2. Serum concentration of apolipoprotein B-100 was significantly decreased in the development of fatty liver.3. Hepatic lipidosis apparently induced insulin resistance.4. Hyperglycemia and hyperinsulinism were observed in treated cows.5. The apparent association of fatty liver with serum concentration of TNFα was not detected.From these results, two experiments were suggested to be effective for induction of fatty liver. Although TNFα of sampled liver tissues were analyzed biochemically and histologically, its relevance to hepatic lipidosis was not detected. We are planning to improve TNFα determination and histological specimens to scrutinize these experiments.