Institute of Theoretical and Experimental Biophysics RAS, Pushchino, Moscow, Region 142290, Russia.
Pushchino State Institute of Natural Sciences, Pushchino, Moscow, Region 142290, Russia.
J Bioenerg Biomembr. 2018 Aug;50(4):289-295. doi: 10.1007/s10863-018-9758-8. Epub 2018 May 3.
In the present work, ultrastructural changes of rat liver mitochondria in hyperthyroidism were studied. Hyperthyroidism was induced in male Wistar rats by daily administration of 100 μg thyroxin per 100 g body weight for 5 days. The level of triiodothyronine and thyroxine increased 3- and 4-fold, respectively, in comparison with the same parameters in the control group, indicating the development of hyperthyroidism in experimental animals. It was found that under this experimental pathology 58% of the mitochondria are swollen, with their matrix enlightened, as compared to the control. In 40% of the profiles, the swollen mitochondria in the liver under hyperthyroidism exhibited rounded mono- or multilayer membrane structures, called lamellar bodies (LBs), presumably at different stages of their development: from the formation to the release from the organelles. Most LBs were located in the mitochondria near the nuclear zone (27%), while their number was reduced in the part of the cell adjacent to the plasma membrane. In a number of swollen mitochondria the cristae were shown to change their orientation, being directed radially toward the center of the mitochondria. We suggested that it is the first stage of formation of LBs. The second stage can be attributed to the formation of monomembrane structures in the center of the organelles. The third stage is characterized by the fact that the membrane of the lamellar bodies consists of several layers, and in this case the bodies were located closer to the outer mitochondrial membrane. The evagination of the outer mitochondrial membrane and its connection with lamellar structure can be recognized as the fourth stage of formation of LBs. At the fifth stage the developed lamellar formations exited the mitochondria. At the same time, following the exit of LBs from the mitochondria, no damage to the mitochondrial membrane was registered, and the structure of the remaining part of the mitochondria was similar to the control. The nucleus of the hepatocyte also underwent structural changes in hyperthyroidism, exhibiting changes in the membrane configuration, and chromatin condensation. The nature and structure of the LBs, as well as their functional role in the liver mitochondria in hyperthyroidism, require further investigation.
在本工作中，研究了甲状腺功能亢进症大鼠肝线粒体的超微结构变化。雄性 Wistar 大鼠每天经口给予 100μg甲状腺素/100g 体重，共 5 天，诱导甲状腺功能亢进。与对照组相比，三碘甲状腺原氨酸和甲状腺素的水平分别增加了 3 倍和 4 倍，表明实验动物发生了甲状腺功能亢进。结果发现，在这种实验病理学中，58%的线粒体肿胀，基质变亮，与对照组相比。在 40%的图谱中，甲状腺功能亢进大鼠肝脏中的肿胀线粒体表现出圆形的单层或多层膜结构，称为板层小体（LBs），推测处于不同的发育阶段：从形成到从细胞器中释放。大多数 LBs 位于靠近核区的线粒体中（27%），而在靠近质膜的细胞部分，其数量减少。在一些肿胀的线粒体中，嵴被发现改变了它们的方向，朝向线粒体的中心呈放射状。我们认为这是 LBs 形成的第一阶段。第二阶段可归因于细胞器中心单膜结构的形成。第三阶段的特征是板层小体的膜由几层组成，在这种情况下，小体更靠近外线粒体膜。外线粒体膜的外凸及其与板层结构的连接可被认为是 LBs 形成的第四阶段。在第五阶段，发育良好的板层结构离开线粒体。同时，在 LBs 从线粒体中逸出后，没有观察到线粒体膜的损伤，并且剩余部分的线粒体结构与对照组相似。肝细胞的核也在甲状腺功能亢进中发生了结构变化，表现为膜结构的改变和染色质的浓缩。LBs 的性质和结构，以及它们在甲状腺功能亢进症大鼠肝线粒体中的功能作用，需要进一步研究。
