Guadaño-Ferraz A, Obregón M J, St Germain D L, Bernal J
Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Cientí ficas 28029 Madrid, Spain.
Proc Natl Acad Sci U S A. 1997 Sep 16;94(19):10391-6. doi: 10.1073/pnas.94.19.10391.
Thyroid hormone plays an essential role in mammalian brain maturation and function, in large part by regulating the expression of specific neuronal genes. In this tissue, the type 2 deiodinase (D2) appears to be essential for providing adequate levels of the active thyroid hormone 3,5,3'-triiodothyronine (T3) during the developmental period. We have studied the regional and cellular localization of D2 mRNA in the brain of 15-day-old neonatal rats. D2 is expressed in the cerebral cortex, olfactory bulb, hippocampus, caudate, thalamus, hypothalamus, and cerebellum and was absent from the white matter. At the cellular level, D2 is expressed predominantly, if not exclusively, in astrocytes and in the tanycytes lining the third ventricle and present in the median eminence. These results suggest a close metabolic coupling between subsets of glial cells and neurons, whereby thyroxine is taken up from the blood and/or cerebrospinal fluid by astrocytes and tanycytes, is deiodinated to T3, and then is released for utilization by neurons.
甲状腺激素在哺乳动物脑成熟和功能中起着至关重要的作用，很大程度上是通过调节特定神经元基因的表达来实现的。在该组织中，2型脱碘酶（D2）似乎对于在发育期间提供足够水平的活性甲状腺激素3,5,3'-三碘甲腺原氨酸（T3）至关重要。我们研究了15日龄新生大鼠脑中D2 mRNA的区域和细胞定位。D2在大脑皮层、嗅球、海马体、尾状核、丘脑、下丘脑和小脑中表达，而白质中没有。在细胞水平上，D2主要（如果不是唯一）在星形胶质细胞以及衬于第三脑室的伸长细胞中表达，并存在于正中隆起中。这些结果表明神经胶质细胞亚群与神经元之间存在紧密的代谢耦合，即甲状腺素被星形胶质细胞和伸长细胞从血液和/或脑脊液中摄取，脱碘转化为T3，然后释放供神经元利用。
