Sonderfan A J, Arlotto M P, Dutton D R, McMillen S K, Parkinson A
Arch Biochem Biophys. 1987 May 15;255(1):27-41. doi: 10.1016/0003-9861(87)90291-8.
The pathways of testosterone oxidation catalyzed by purified and membrane-bound forms of rat liver microsomal cytochrome P-450 were examined with an HPLC system capable of resolving 14 potential hydroxylated metabolites of testosterone and androstenedione. Seven pathways of testosterone oxidation, namely the 2 alpha-, 2 beta-, 6 beta-, 15 beta-, 16 alpha-, and 18-hydroxylation of testosterone and 17-oxidation to androstenedione, were sexually differentiated in mature rats (male/female = 7-200 fold) but not in immature rats. Developmental changes in two cytochrome P-450 isozymes largely accounted for this sexual differentiation. The selective expression of cytochrome P-450h in mature male rats largely accounted for the male-specific, postpubertal increase in the rate of testosterone 2 alpha-, 16 alpha, and 17-oxidation, whereas the selective repression of cytochrome P-450p in female rats accounted for the female-specific, postpubertal decline in testosterone 2 beta-, 6 beta-, 15 beta-, and 18-hydroxylase activity. A variety of cytochrome P-450p inducers, when administered to mature female rats, markedly increased (up to 130-fold) the rate of testosterone 2 beta-, 6 beta-, 15 beta-, and 18-hydroxylation. These four pathways of testosterone hydroxylation were catalyzed by partially purified cytochrome P-450p, and were selectively stimulated when liver microsomes from troleandomycin- or erythromycin estolate-induced rats were treated with potassium ferricyanide, which dissociates the complex between cytochrome P-450p and these macrolide antibiotics. Just as the testosterone 2 beta-, 6 beta-, 15 beta-, and 18-hydroxylase activity reflected the levels of cytochrome P-450p in rat liver microsomes, so testosterone 7 alpha-hydroxylase activity reflected the levels of cytochrome P-450a; 16 beta-hydroxylase activity the levels of cytochrome P-450b; and 2 alpha-hydroxylase activity the levels of cytochrome P-450h. It is concluded that the regio- and stereoselective hydroxylation of testosterone provides a functional basis to study simultaneously the regulation of several distinct isozymes of rat liver microsomal cytochrome P-450.
利用能够分离睾酮和雄烯二酮的14种潜在羟基化代谢物的高效液相色谱系统，研究了纯化的和膜结合形式的大鼠肝脏微粒体细胞色素P-450催化的睾酮氧化途径。睾酮氧化的7条途径，即睾酮的2α-、2β-、6β-、15β-、16α-和18-羟基化以及17-氧化生成雄烯二酮，在成熟大鼠中存在性别差异（雄性/雌性=7-200倍），但在未成熟大鼠中不存在。两种细胞色素P-450同工酶的发育变化在很大程度上解释了这种性别差异。成熟雄性大鼠中细胞色素P-450h的选择性表达在很大程度上解释了青春期后睾酮2α-、16α-和17-氧化速率的雄性特异性增加，而雌性大鼠中细胞色素P-450p的选择性抑制则解释了青春期后睾酮2β-、6β-、15β-和18-羟化酶活性的雌性特异性下降。当给成熟雌性大鼠施用多种细胞色素P-450p诱导剂时，睾酮2β-、6β-、15β-和18-羟基化速率显著增加（高达130倍）。睾酮羟基化的这四条途径由部分纯化的细胞色素P-450p催化，当用铁氰化钾处理来自三乙酰竹桃霉素或依托红霉素诱导的大鼠的肝脏微粒体时，这些途径被选择性刺激，铁氰化钾可使细胞色素P-450p与这些大环内酯类抗生素之间的复合物解离。正如睾酮2β-、6β-、15β-和18-羟化酶活性反映了大鼠肝脏微粒体中细胞色素P-450p的水平一样，睾酮7α-羟化酶活性反映了细胞色素P-450a的水平；16β-羟化酶活性反映了细胞色素P-450b的水平；2α-羟化酶活性反映了细胞色素P-450h的水平。结论是，睾酮的区域和立体选择性羟基化为同时研究大鼠肝脏微粒体细胞色素P-450的几种不同同工酶的调节提供了功能基础。
