Adult male rat hippocampus synthesizes estradiol from pregnenolone by cytochromes P45017α and P450 aromatase localized in neurons
Adult male rat hippocampus synthesizes estradiol from pregnenolone by cytochromes P45017α and P450 aromatase localized in neurons
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DOI：
10.1073/pnas.2630225100
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发表时间：
2004-01-20
影响因子：
11.1
通讯作者：
Kawato, S
中科院分区：
文献类型：
--
作者：
Hojo, Y;Hattori, T;Kawato, S
在成年哺乳动物大脑中，由于无法检测到脱氢表雄酮合成酶p45017 α，内源性胆固醇合成雌二醇的发生一直受到怀疑。在成年雄性大鼠海马形成中，通过免疫组化染色切片，我们发现细胞色素p45017 α和P450芳香化酶在CA1-CA3区的锥体神经元以及齿状回的颗粒细胞中都有明显的定位。仅在星形胶质细胞和少突胶质细胞中观察到这些p450的弱免疫反应。免疫金电镜显示P45017a和P450芳香化酶定位于突触前和突触后室以及主要神经元的内质网。Western blot和RT-PCR进一步验证了这些细胞色素的表达。用n -甲基- d -天冬氨酸刺激海马神经元诱导雌二醇的显著净生成。放射性代谢物分析表明[H-3]孕烯醇酮通过脱氢表雄酮和睾酮转化为[H-3]雌二醇。这种活性被细胞色素p450的特异性抑制剂所消除。有趣的是，雌二醇并没有明显转化为其他类固醇代谢物。结合我们之前发现的含有p450scc的孕烯醇酮合成神经元系统，这些结果表明17 -雌二醇是由内源性胆固醇定位在海马神经元中的p45017α和P450芳香化酶合成的。这种合成可能由谷氨酸介导的突触通讯调节，引起Ca2+信号。
In adult mammalian brain, occurrence of the synthesis of estradiol from endogenous cholesterol has been doubted because of the inability to detect dehydroepiandrosterone synthase, P45017alpha. In adult male rat hippocampal formation, significant localization was demonstrated for both cytochromes P45017alpha and P450 aromatase, in pyramidal neurons in the CA1-CA3 regions, as well as in the granule cells in the dentate gyrus, by means of immunohistochemical staining of slices. Only a weak immunoreaction of these P450s was observed in astrocytes and oligodendrocytes. ImmunoGold electron microscopy revealed that P45017a and P450 aromatase were localized in pre- and postsynaptic compartments as well as in the endoplasmic reticulum in principal neurons. The expression of these cytochromes was further verified by using Western blot analysis and RT-PCR. Stimulation of hippocampal neurons with N-methyl-D-aspartate induced a significant net production of estradiol. Analysis of radioactive metabolites demonstrated the conversion from [H-3]pregnenolone to [H-3]estradiol through dehydroepiandrosterone and testosterone. This activity was abolished by the application of specific inhibitors of cytochrome P450s. Interestingly, estradiol was not significantly converted to other steroid metabolites. Taken together with our previous finding of a P450scc-containing neuronal system for pregnenolone synthesis, these results imply that 17beta-estradiol is synthesized by P45017alpha and P450 aromatase localized in hippocampal neurons from endogenous cholesterol. This synthesis may be regulated by a glutamate-mediated synaptic communication that evokes Ca2+ signals.