Carreau S, Bilinska B, Levallet J
Endocrinology & Tissue Culture Laboratory, Jagiellonian University, Krakow, Poland.
Ann Endocrinol (Paris). 1998 Jul;59(2):79-92.
Cytochrome P450 aromatase (P450arom), which catalyzes irreversible transformation of androgens into estrogens, has been immunolocalized in mouse, brown bear and rooster germ cells. In the immature rat, P450arom is found in Sertoli cells while in the mature rat it is found in Leydig cells. In the pig, ram, and human, it is mainly present in Leydig cells. Our purpose was first to investigate the testicular presence of cytochrome P450arom mRNA in adult rat germ cells using RT-PCR. The amplified product from germ cells showed 100% homology with the corresponding fragments of the rat ovary cDNAs and was detectable not only in rat Leydig and Sertoli cells but also in pachytene spermatocytes, round spermatids and testicular spermatozoa. In purified Leydig cells and pachytene spermatocytes the P450arom mRNA level was 10-fold higher than in Sertoli cells. The amount of P450arom mRNA transcript decreased according to the stage of germ cell maturation, being more elevated in younger than in mature germ cells. By contrast, the aromatase activity in the microsomal fractions was 2- to 4-fold greater in spermatozoa than in the other enriched germ cell preparations studied. We also demonstrated the presence of a 55kDa protein in a mixed germ cell preparation and have been able to immunolocalize the P450arom on mature rat testicular slices, namely in Leydig cells and elongated spermatids. The overall data confirm the presence of a functional cytochrome P450arom in the male rat testis and consequently, the existence of an additional source of estrogens within the genital tract of the male which may likely suggest a physiological role for these hormones in the regulation of spermatogenesis.
细胞色素P450芳香化酶（P450arom）催化雄激素不可逆地转化为雌激素，已在小鼠、棕熊和公鸡的生殖细胞中进行了免疫定位。在未成熟大鼠中，P450arom存在于支持细胞中，而在成熟大鼠中，它存在于间质细胞中。在猪、公羊和人类中，它主要存在于间质细胞中。我们的目的首先是使用逆转录聚合酶链反应（RT-PCR）研究成年大鼠生殖细胞中细胞色素P450arom mRNA在睾丸中的存在情况。生殖细胞的扩增产物与大鼠卵巢cDNA的相应片段显示出100%的同源性，不仅在大鼠间质细胞和支持细胞中可检测到，在粗线期精母细胞、圆形精子细胞和睾丸精子中也可检测到。在纯化的间质细胞和粗线期精母细胞中，P450arom mRNA水平比支持细胞高10倍。P450arom mRNA转录本的量根据生殖细胞成熟阶段而降低，在较年轻的生殖细胞中比成熟生殖细胞中更高。相比之下，微粒体部分的芳香化酶活性在精子中比在其他研究的富集生殖细胞制剂中高2至4倍。我们还在混合生殖细胞制剂中证明了一种55kDa蛋白质的存在，并能够在成熟大鼠睾丸切片上对P450arom进行免疫定位，即在间质细胞和伸长的精子细胞中。总体数据证实了雄性大鼠睾丸中存在功能性细胞色素P450arom，因此，雄性生殖道内存在雌激素的额外来源，这可能暗示这些激素在精子发生调节中的生理作用。
