Schumacher M, Robel P, Baulieu E E
Lab. Hormones, INSERM U33, Bicêtre, France.
Dev Neurosci. 1996;18(1-2):6-21. doi: 10.1159/000111391.
Several steroids, termed 'neurosteroids', are synthesized from cholesterol within both the central and peripheral nervous systems. These include pregnenolone and its sulfate ester, progesterone and its 5 alpha-reduced metabolites. Dehydroepiandrosterone, mainly in its sulfated form, also remains present in the brain long after removal of the steroidogenic endocrine glands. Its biosynthesis in brain remains an open possibility, but the pathways involved are unknown. Little information is available concerning the role of neurosteroids during the maturation of the nervous system, although they are already synthesized by glial cells and by some populations of neurons during embryonic life. Cell culture experiments suggest that neurosteroids may increase the survival and differentiation of both neurons and glial cells. In the adult nervous system, neurosteroids modulate neurotransmission by acting directly on the neuronal membrane and also produce structural changes in neurons and in astrocytes. Studies of neurosteroid levels are currently conducted to examine their possible role during aging. We have recently reported that progesterone, synthesized by Schwann cells, promotes the formation of new myelin sheaths after lesion of the mouse sciatic nerve. Thus, neurosteroids may also play an important role during regeneration of the nervous system.
几种被称为“神经甾体”的甾体化合物是在中枢神经系统和外周神经系统内由胆固醇合成的。这些包括孕烯醇酮及其硫酸酯、孕酮及其5α-还原代谢产物。脱氢表雄酮，主要以其硫酸化形式，在去除产生甾体的内分泌腺后很长时间仍存在于大脑中。其在大脑中的生物合成仍有可能，但相关途径尚不清楚。关于神经甾体在神经系统成熟过程中的作用，目前所知甚少，尽管在胚胎期它们就已由神经胶质细胞和一些神经元群体合成。细胞培养实验表明，神经甾体可能会增加神经元和神经胶质细胞的存活及分化。在成体神经系统中，神经甾体通过直接作用于神经元膜来调节神经传递，还会在神经元和星形胶质细胞中产生结构变化。目前正在进行神经甾体水平的研究，以检验它们在衰老过程中可能发挥的作用。我们最近报道，雪旺细胞合成的孕酮可促进小鼠坐骨神经损伤后新髓鞘的形成。因此，神经甾体在神经系统再生过程中也可能发挥重要作用。
