Department of Cell Biology and Morphology, Akita University Graduate School of Medicine, Akita 010-8543, Japan.
Anat Rec (Hoboken). 2012 Oct;295(10):1660-8. doi: 10.1002/ar.22555. Epub 2012 Aug 21.
We performed a systematic characterization of the hepatic vitamin A storage in mammals and birds of the Svalbard Archipelago and Greenland. The liver of top predators, including polar bear, Arctic fox, bearded seal, and glaucous gull, contained about 10-20 times more vitamin A than the liver of all other arctic animals studied, as well as their genetically related continental top predators. The values are also high compared to normal human and experimental animals like mouse and rat. This massive amount of hepatic vitamin A was located in large autofluorescent lipid droplets in hepatic stellate cells (HSCs; also called vitamin A-storing cells, lipocytes, interstitial cells, fat-storing cells, or Ito cells). The droplets made up most of the cells' cytoplasm. The development of such an efficient vitamin A-storing mechanism in HSCs may have contributed to the survival of top predators in the extreme environment of the arctic. These animals demonstrated no signs of hypervitaminosis A. We suggest that HSCs have capacity to take-up and store large amounts of vitamin A, which may play a pivotal role in maintenance of the food web, food chain, biodiversity, and eventually ecology of the arctic.
我们对斯瓦尔巴群岛和格陵兰岛的哺乳动物和鸟类的肝脏维生素 A 储存进行了系统的描述。包括北极熊、北极狐、髯海豹和贼鸥在内的顶级捕食者的肝脏中维生素 A 的含量比我们研究的所有其他北极动物，以及与其具有遗传关系的大陆顶级捕食者的肝脏中的维生素 A 含量高 10-20 倍。与正常人类和实验动物（如老鼠）相比，这些数值也很高。这种大量的肝脏维生素 A 存在于肝星状细胞（HSCs；也称为维生素 A 储存细胞、脂细胞、间质细胞、脂肪储存细胞或 Ito 细胞）中的大的自发荧光脂质滴中。这些液滴构成了细胞细胞质的大部分。HSCs 中如此高效的维生素 A 储存机制的发展可能有助于顶级捕食者在北极的极端环境中生存。这些动物没有出现维生素 A 过多症的迹象。我们认为 HSCs 有能力摄取和储存大量的维生素 A，这可能在维持食物网、食物链、生物多样性以及最终的北极生态方面发挥关键作用。
