Ibarrola N, Rodríguez-Peña A
Instituto de Investigaciones Biomédicas, C.S.I.C., Madrid, Spain.
Brain Res. 1997 Mar 28;752(1-2):285-93. doi: 10.1016/s0006-8993(96)01480-1.
To assess the role of thyroid hormone on myelin gene expression, we have studied the effect of hypothyroidism on the mRNA steady state levels for the major myelin protein genes: myelin basic protein (MBP), proteolipid protein (PLP), myelin-associated glycoprotein (MAG) and 2':3'-cyclic nucleotide 3'-phosphodiesterase (CNP) in different rat brain regions, during the first postnatal month. We found that hypothyroidism reduces the levels of every myelin protein transcript, with striking differences between the different brain regions. Thus, in the more caudal regions, the effect of hypothyroidism was extremely modest, being only evident at the earlier stages of myelination. In contrast, in the striatum and the cerebral cortex the important decrease in the myelin protein transcripts is maintained beyond the first postnatal month. Therefore, thyroid hormone modulates in a synchronous fashion the expression of the myelin genes and the length of its effect depends on the brain region. On the other hand, hyperthyroidism leads to an increase of the major myelin protein transcripts above control values. Finally, lack of thyroid hormone does not change the expression of the oligodendrocyte progenitor-specific gene, the platelet derived growth factor receptor alpha.
为评估甲状腺激素对髓鞘基因表达的作用，我们研究了甲状腺功能减退对出生后第一个月内不同大鼠脑区主要髓鞘蛋白基因：髓鞘碱性蛋白（MBP）、蛋白脂蛋白（PLP）、髓鞘相关糖蛋白（MAG）和2':3'-环核苷酸3'-磷酸二酯酶（CNP）的mRNA稳态水平的影响。我们发现甲状腺功能减退会降低每种髓鞘蛋白转录本的水平，不同脑区之间存在显著差异。因此，在较尾侧的脑区，甲状腺功能减退的影响非常轻微，仅在髓鞘形成的早期阶段明显。相比之下，在纹状体和大脑皮层，髓鞘蛋白转录本的重要减少在出生后第一个月之后仍持续存在。因此，甲状腺激素以同步方式调节髓鞘基因的表达，其作用的持续时间取决于脑区。另一方面，甲状腺功能亢进导致主要髓鞘蛋白转录本增加至高于对照值。最后，缺乏甲状腺激素不会改变少突胶质细胞祖细胞特异性基因血小板衍生生长因子受体α的表达。
