A BASIC STUDY ON THE MECHANISM OF FATTY LIVER OCCURRENCE IN DAIRY CATTLE

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The fatty liver in dairy cattle is known to be closely linked to periparturient diseases. Therefore, it is essential to elucidate the mechanism in the induction of fatty liver together with analyzing the patho genesis in order to investigate the prophylaxis of the diseases. In this study, 4-days-fasting model reported previously by us was mainly used as a experimental induction of fatty liver. The changes of pathogenesis in the development of fatty liver were scrutinized biochemically, molecularbiologically and micromorphologically. The samples from cow with ethionine-induced fatty liver were also utilized in a part of study. Besides, a cow with focal fatty liver (FFL) we came across by chance was also investigated.1. By fasting for 4 days, serum concentration of free fatty acid was markedly increased and fatty liver was induced.2. Insulin resistance was observed in the development of fatty liver.3. In micromorphological analysis of fatty liver, increased thickness of basal lamina and decreased stellate cell was observed.. Increased TNF a were also admitted immunohistologically.4. The extraction rate of total bile acid from portal blood to hepatic cell was reduced with the development of fatty liver.5. Decreased secretion of very low density lipoprotein to hepatic blood was shown in the fatty liver.6. The decreased pattern of apolipoprotein (apo) C-III was distinctly different from that of apo B-100 in cow with ethionine-induced fatty liver. The change of apo C-III concentration was similar to that of the m-RNA.7. The lesion of FFL was localized around hepatic portal vein Endotoxin may be one of causes. As stated above, valuable findings regarding to the pathogenesis of fatty liver were obtained. We are planning to investigate the relation among basal lamina, stellate cell and TNFα in detail.