鸡（家鸡）胚胎卵巢和睾丸切片中睾酮和雌二醇-17β的生物合成途径。

Imataka H, Suzuki K, Inano H, Kohmoto K, Tamaoki B

Department of Animal Breeding, Faculty of Agriculture, University of Tokyo, Japan.

Gen Comp Endocrinol. 1989 Jan;73(1):69-79. doi: 10.1016/0016-6480(89)90056-7.

To elucidate synthetic pathways of testosterone and estradiol-17 beta in embryonic gonads of the chicken, metabolism of various 14C-labeled steroids in slices of the left ovaries and paired testes of 15- and 9-day-old chicken embryos was examined. (1) Fifteen-day-old chicken embryos: From pregnenolone, more 17 alpha-hydroxypregnenolone was produced than progesterone in the ovary, while more progesterone was produced than 17 alpha-hydroxypregnenolone in the testis. From 17 alpha-hydroxypregnenolone, however, only dehydroepiandrosterone was detected as a product in both gonads. Dehydroepiandrosterone was converted mainly into androstenedione and its 5 beta-reduced derivatives by both gonads. Progesterone was converted into 5 beta-pregnane-3,20-dione more than into 17 alpha-hydroxyprogesterone by both gonads. Both gonads metabolized 17 alpha-hydroxyprogesterone, androstenedione, and testosterone predominantly into their corresponding 5 beta-reduced steroids, while production of androstenedione from 17 alpha-hydroxyprogesterone and of testosterone from androstenedione was limited. Estradiol-17 beta was produced from androstenedione and testosterone only by the ovary. (2) Nine-day-old chicken embryos: From pregnenolone, production of progesterone and 17 alpha-hydroxypregnenolone was similar in the ovary. On the other hand, in the testis, more progesterone was produced than 17 alpha-hydroxypregnenolone from pregnenolone. For delta 4-3-oxo steroids, strong activity of 5 beta-reductase was demonstrated in both gonads. From these results, both delta 4- and delta 5-pathways are involved in the formation of testosterone and then finally of estradiol-17 beta by the embryonic gonads of the chicken, and relative preference for the pathway seems to depend on sexes and embryonic ages. In addition, it is suggested that steroidogenesis in these embryonic gonads is characterized by marked activity of 5 beta-reductase, irrespective of sexes or ages.

为阐明鸡胚胎性腺中睾酮和雌二醇 - 17β 的合成途径，检测了 15 日龄和 9 日龄鸡胚胎的左卵巢切片及配对睾丸中各种 14C 标记类固醇的代谢情况。（1）15 日龄鸡胚胎：在卵巢中，从孕烯醇酮生成的 17α - 羟孕烯醇酮比孕酮多，而在睾丸中，生成的孕酮比 17α - 羟孕烯醇酮多。然而，从 17α - 羟孕烯醇酮生成的产物中，在两个性腺中仅检测到脱氢表雄酮。两个性腺都将脱氢表雄酮主要转化为雄烯二酮及其 5β - 还原衍生物。两个性腺将孕酮转化为 5β - 孕烷 - 3,20 - 二酮的量比转化为 17α - 羟孕酮的量多。两个性腺都将 17α - 羟孕酮、雄烯二酮和睾酮主要代谢为其相应的 5β - 还原类固醇，而从 17α - 羟孕酮生成雄烯二酮以及从雄烯二酮生成睾酮的量有限。仅卵巢能从雄烯二酮和睾酮生成雌二醇 - 17β。（2）9 日龄鸡胚胎：在卵巢中，从孕烯醇酮生成孕酮和 17α - 羟孕烯醇酮的情况相似。另一方面，在睾丸中，从孕烯醇酮生成的孕酮比 17α - 羟孕烯醇酮多。对于 Δ4 - 3 - 氧代类固醇，在两个性腺中都显示出 5β - 还原酶的强活性。从这些结果可知，Δ4 和 Δ5 途径都参与鸡胚胎性腺中睾酮的形成，最终参与雌二醇 - 17β 的形成，并且对途径的相对偏好似乎取决于性别和胚胎年龄。此外，提示这些胚胎性腺中的类固醇生成以 5β - 还原酶的显著活性为特征，而与性别或年龄无关。