Yoo Yeon Ho, Kim Dae Won, Chen Bai Hui, Sim Hyejin, Kim Bora, Lee Jae-Chul, Ahn Ji Hyeon, Park Yoonsoo, Cho Jun Hwi, Kang Il Jun, Won Moo-Ho, Lee Tae-Kyeong
Department of Emergency Medicine, Institute of Medical Sciences, School of Medicine, Kangwon National University Hospital, Kangwon National University, 24289, Chuncheon, Gangwon, Republic of Korea.
Department of Biochemistry and Molecular Biology, Research Institute of Oral Sciences, College of Dentistry, Gangnung-Wonju National University, 25457, Gangneung, Gangwon, Republic of Korea.
Lab Anim Res. 2021 Mar 6;37(1):11. doi: 10.1186/s42826-021-00088-y.
Aging is one of major causes triggering neurophysiological changes in many brain substructures, including the hippocampus, which has a major role in learning and memory. Thioredoxin (Trx) is a class of small redox proteins. Among the Trx family, Trx2 plays an important role in the regulation of mitochondrial membrane potential and is controlled by TrxR2. Hitherto, age-dependent alterations in Trx2 and TrxR2 in aged hippocampi have been poorly investigated. Therefore, the aim of this study was to examine changes in Trx2 and TrxR2 in mouse and rat hippocampi by age and to compare their differences between mice and rats.
Trx2 and TrxR2 levels using Western blots in mice were the highest at young age and gradually reduced with time, showing that no significant differences in the levels were found between the two subfields. In rats, however, their expression levels were the lowest at young age and gradually increased with time. Nevertheless, there were no differences in cellular distribution and morphology in their hippocampi when it was observed by cresyl violet staining. In addition, both Trx2 and TrxR2 immunoreactivities in the CA1-3 fields were mainly shown in pyramidal cells (principal cells), showing that their immunoreactivities were altered like changes in their protein levels.
Our current findings suggest that Trx2 and TrxR2 expressions in the brain may be different according to brain regions, age and species. Therefore, further studies are needed to examine the reasons of the differences of Trx2 and TrxR2 expressions in the hippocampus between mice and rats.
衰老为引发包括海马体在内的许多脑亚结构神经生理变化的主要原因之一，海马体在学习和记忆中起主要作用。硫氧还蛋白（Trx）是一类小的氧化还原蛋白。在Trx家族中，Trx2在线粒体膜电位调节中起重要作用，并受TrxR2控制。迄今为止，对老年海马体中Trx2和TrxR2随年龄变化的研究较少。因此，本研究旨在研究小鼠和大鼠海马体中Trx2和TrxR2随年龄的变化，并比较它们在小鼠和大鼠之间的差异。
通过蛋白质免疫印迹法检测，小鼠Trx2和TrxR2水平在年轻时最高，并随时间逐渐降低，表明两个亚区在水平上无显著差异。然而，在大鼠中，它们的表达水平在年轻时最低，并随时间逐渐升高。不过，用甲酚紫染色观察时，它们海马体的细胞分布和形态并无差异。此外，CA1-3区的Trx2和TrxR2免疫反应性主要表现在锥体细胞（主要细胞）中，表明它们的免疫反应性随蛋白质水平的变化而改变。
我们目前的研究结果表明，Trx2和TrxR2在大脑中的表达可能因脑区、年龄和物种而异。因此，需要进一步研究来探讨小鼠和大鼠海马体中Trx2和TrxR2表达差异的原因。
