脂肪肝牛における血清中ビタミンA濃度と肝臓星細胞の関連性

Abstract

Vitamin A (VA) is stored mainly in lipid droplets in hepatic stellate cells (HSCs) of the liver. Apparently, when the level of serum VA drops below the basic-requirement level, lipid droplets in an HSC either decrease in number or disappear altogether. Fatty-liver disease (fat-cow syndrome), which is common in periparturient cattle and makes the animals highly susceptible to ketosis, is a major cause of significant economic loss. In the past, some reports have dealt with the relationships between VA serum concentrations and pathological changes in cattle with fatty-liver disease. The present study aims to determine the correlation between morphological changes in HSCs and VA serum concentration in both normal (control) cattle (n= 5) and cattle with fatty-liver disease (experimental group). In the experimental group (n= 15), the number of HSCs per unit area decreased significantly with the disappearance of lipid droplets and collagen from the perisinusoidal space. The basementmembrane of the subsinusoidal endothelium, however, became significantly thicker than in the control group because of an accumulation of both cellular and noncellular substance in situ. Moreover, in the experimental group, nuclei and lipid droplets in HSCs were comparatively small. In the control group, on the other hand, lipid droplets in HSCs were notably large. Numbers of lipid droplets, VA serum concentrations and HSC formation in the controlgroup increased significantly. These findings clearly show correlation between VA serum concentration and HSC numbers and indicate the need to maintain blood CA concentrations in cattle with fatty-liver disease.