Weiss M, Ford V L
J Steroid Biochem. 1984 Dec;21(6):701-7. doi: 10.1016/0022-4731(84)90034-7.
Steroidogenesis by subcellular fractions of adrenal cortex proper (C.P.) and special zone (S.Z.) of female possum (Trichosurus vulpecula) was studied. Mitochondrial, microsomal and cytosol cell fractions were incubated with appropriate substrates in the presence of an NADPH-generating system. The major products formed from [3H]progesterone and [3H]17 alpha-hydroxyprogesterone by the microsomal fraction of the C.P. were 11-deoxycortisol and 11-deoxycorticosterone and 3 alpha (beta)-hydroxy-5 alpha-androstan-17-one by the S.Z. The mitochondrial fraction converted [3H]11-deoxycortisol to cortisol in yields twenty times higher by the C.P. than by the S.Z. and to 17 alpha, 20 beta,21-trihydroxy-4-pregn-3-one thirty times higher by the S.Z. The conversion of [3H]androstenedione to 11 beta-hydroxyandrostenedione by the C.P. was approximately double that of the S.Z., while 18-hydroxyandrostenedione (tentatively identified) formed the highest yield in both zones. Incubation of the same substrates with cytosol formed two 5 beta-pregnane and two 5 beta-androstane derivatives in total yields less than 5% by C.P. and greater than 60% by S.Z. Aromatase activity, estimated by the release of [3H2O] from [1 beta 3H]testosterone, in the adrenals of 8 possums, was in each experiment negligibly low. Determination of total enzyme activities in the two zones revealed that 11 beta, 18 and 21-hydroxylases were higher in the C.P., while 17 alpha-hydroxylase was higher in the S.Z. Similar results were obtained when the rates of formation of hydroxylated products were estimated in the presence of saturating amounts of substrates. Active 5 alpha- and 5 beta-reductases, C17-20-lyase and 3 alpha (beta) and 20 beta-hydroxysteroid dehydrogenases were found almost exclusively in the S.Z. We conclude that the S.Z. at lower levels of activity than the C.P. could contribute to the basal secretion of corticosteroids. In addition, the S.Z. has a high capacity to form C19 steroids and 5 alpha- and 5 beta-reduced steroids. The possible role of the S.Z. in possum is discussed.
对雌性负鼠（帚尾袋貂）肾上腺皮质固有层（C.P.）和特殊带（S.Z.）的亚细胞组分的类固醇生成进行了研究。将线粒体、微粒体和胞质溶胶细胞组分在存在NADPH生成系统的情况下与合适的底物一起孵育。C.P.的微粒体组分由[3H]孕酮和[3H]17α-羟基孕酮形成的主要产物是11-脱氧皮质醇和11-脱氧皮质酮，而S.Z.形成的主要产物是3α（β）-羟基-5α-雄甾烷-17-酮。线粒体组分将[3H]11-脱氧皮质醇转化为皮质醇，C.P.的产量比S.Z.高20倍，将其转化为17α，20β，21-三羟基-4-孕烯-3-酮，S.Z.的产量比C.P.高30倍。C.P.将[3H]雄烯二酮转化为11β-羟基雄烯二酮的量约为S.Z.的两倍，而在两个区域中，18-羟基雄烯二酮（初步鉴定）的产量最高。将相同底物与胞质溶胶一起孵育，C.P.总共形成两种5β-孕烷和两种5β-雄甾烷衍生物，总产量低于5%，而S.Z.则高于60%。通过[1β3H]睾酮释放[3H2O]来估计8只负鼠肾上腺中的芳香化酶活性，在每个实验中该活性都极低。对两个区域中总酶活性的测定表明，11β、18和21-羟化酶在C.P.中较高，而17α-羟化酶在S.Z.中较高。当在底物饱和量存在的情况下估计羟基化产物的形成速率时，也获得了类似的结果。活性5α-和5β-还原酶、C17-20裂解酶以及3α（β）和20β-羟基类固醇脱氢酶几乎只在S.Z.中发现。我们得出结论，活性低于C.P.的S.Z.可能有助于皮质类固醇的基础分泌。此外，S.Z.具有形成C19类固醇以及5α-和5β-还原类固醇的高能力。讨论了S.Z.在负鼠中的可能作用。
