Melcangi R C, Celotti F, Ballabio M, Castano P, Poletti A, Milani S, Martini L
Institute of Endocrinology, University of Milano, Italy.
Brain Res Dev Brain Res. 1988 Dec 1;44(2):181-8. doi: 10.1016/0165-3806(88)90216-7.
In the central nervous system of the rat, the 5 alpha-reductase, the enzyme which converts testosterone into dihydrotestosterone, appears to be concentrated in the white matter and in particular to be associated with myelin. In order to verify whether a temporal correlation might exist between the formation of myelin membranes and the variations of the 5 alpha-reductase activity observed in the brain, the enzymatic activity was studied in the cerebral cortex and in the hypothalamus of male rat in the age range of 3-60 days, in myelin purified from animals of 15-60 days of life and in oligodendrocytes (i.e. in the cells responsible for the formation of the myelin) isolated from the brain of adult and very young rats (7th day of life, when the myelination process is not yet initiated). The results show that the formation of 5 alpha-androstane-17 beta-ol-3-one (DHT) in the cerebral cortex and in the hypothalamus has a peak activity in the first two weeks of life, before the beginning of the myelination process; purified myelin has an enzymatic activity always much higher than that present in the cerebral cortex and in the hypothalamus and shows a peak in the formation of DHT in the first period of myelinogenesis, on the third week of life. Finally the oligodendrocytes of young rats possess a much higher ability to convert testosterone into the 5 alpha-reduced metabolites than the oligodendrocytes of adult animals. A possible involvement of this enzyme in the myelin function may be hypothesized.
在大鼠的中枢神经系统中，5α-还原酶（将睾酮转化为二氢睾酮的酶）似乎集中在白质中，尤其与髓磷脂相关。为了验证髓磷脂膜的形成与大脑中观察到的5α-还原酶活性变化之间是否可能存在时间相关性，我们研究了3至60日龄雄性大鼠大脑皮层和下丘脑、从15至60日龄动物纯化得到的髓磷脂以及从成年大鼠和幼龄大鼠（出生第7天，此时髓鞘形成过程尚未开始）大脑中分离得到的少突胶质细胞（即负责形成髓磷脂的细胞）中的酶活性。结果表明，大脑皮层和下丘脑5α-雄甾烷-17β-醇-3-酮（双氢睾酮，DHT）的形成在髓鞘形成过程开始前的生命前两周具有峰值活性；纯化的髓磷脂的酶活性始终远高于大脑皮层和下丘脑，并且在髓鞘形成的第一阶段，即出生后第三周，DHT的形成出现峰值。最后，幼龄大鼠的少突胶质细胞比成年动物的少突胶质细胞具有更高的将睾酮转化为5α-还原代谢物的能力。可以推测这种酶可能参与髓磷脂的功能。
