A study on vitamin A storage in polar bears in Greenland.

为探讨维生素A的储存机制，采用高效液相色谱法（HPLC）、透射电镜（TEM）形态测定法、氯化金染色法、荧光显微镜检测维生素A自身荧光、苏木精-伊红（H&E）染色、马松三色染色、石井-石井银浸渍法等方法，对成年北极熊和北极狐的肝脏进行了大量维生素A生理储存的研究。高效液相色谱法显示，北极熊和北极狐每克肝脏中含有1.8-1.9微摩尔的总视黄醇（视黄醇加视黄醇酯）。在北极狐中，发现视黄醇酯的组成为51.1%棕榈酸酯，26.6%油酸酯，15.4%硬脂酸酯和7%亚油酸酯。透射电镜显示北极动物的肝星状细胞在其细胞质中含有大量维生素A脂滴。北极动物肝小叶中维生素a的储藏量呈区域梯度，梯度在肝小叶中表现为从门静脉周围区开始，在中间区达到顶峰，向中心区倾斜的对称渐降曲线。肝星状细胞密度（即每面积的细胞数）在各区域间基本相同。肝脏中维生素A含量的不同不影响贮存维生素A的维生素A酯的梯度和组成。这些结果表明，北极狐和北极熊肝星状细胞维生素a储存能力的异质性是由基因决定的。从2004年7月到8月，我们还在格陵兰岛东海岸的Ittoqqortoormiit捕获了4只北极熊。我们用形态学方法分析了肝星状细胞中的脂滴。随着时效的增加，液滴的大小和数量增加；这表明维生素是按时间顺序积累的。结果表明，维生素A是从食物中积累并储存在肝星状细胞中。少

To investigate the storage mechanisms of vitamin A, we examined the liver of adult polar bears and arctic foxes, which physiologically store a large amount of vitamin A, by high-performance liquid chromatography (HPLC), transmission electron microscopy (TEM) morphometry, gold chloride staining, fluorescence microscopy for detection of autofluorescence of vitamin A, staining with hematoxylin-eosin (H&E), Masson's trichrome, and Ishii-Ishii's silver impregnation. HPLC revealed that polar bears and arctic foxes contained 1.8-1.9 micro mole total retinol (retinol plus retinyl esters) per gram liver. In the arctic foxes, the composition of the retinyl esters was found to be 51.1 % palmitate, 26.6 % oleate,15.4 % stearate, and 7% linoleate. The hepatic stellate cells of the arctic animals were demonstrated by TEM to contain the bulk of the vitamin A lipid droplets in their cytoplasm. The liver lobules of the arctic animals showed a zonal gradient in the storage of vitamin A. The gradient was … More expressed as a symmetric crescendo-decrescendo profile starting at the periportal zone, peaking at the middle zone, and sloping down toward the central zone in the liver lobule. The density (namely, cell number per area) of hepatic stellate cells was essentially the same among the zones. The gradient and composition of the vitamin A esters in storing vitamin A were not changed by differences in the vitamin A amount in the livers. These results indicate that the heterogeneity of vitamin A-storage capacity in hepatic stellate cells of arctic foxes and polar bears is genetically determined. We also caught 4 polar bears in Ittoqqortoormiit, in the east coast of Greenland from July through August, 2004. We analyzed the lipid droplets in the hepatic stellate cells by morphological methods. The size and number of the droplets increased due to the aging; this showed the vitamin was accumulated chronologically. This result showed that the vitamin A was accumulated from the food and stored in the hepatic stellate cells. Less