Cecil H. and Ida Green Center for Reproductive Biology Sciences, Departments of Biochemistry and Obstetrics and Gynecology, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75235.
Mol Cell Neurosci. 1993 Dec;4(6):526-31. doi: 10.1006/mcne.1993.1064.
In (28- to 40-day-old) male rats, the influence of castration or hormone-replacement treatment with dihydrotestosterone (5alpha-DHT) upon pituitary or hypothalamic 5alpha-reductase was assessed. The efficacy of the treatments was demonstrated by measuring serum LH and ventral prostate weight. Pituitary 5alpha-reductase enzyme activity was estimated by isolating [5alpha-(3)H]DHT by thin-layer chromatography after incubations with [(3)H]testosterone, and the identity of the [5alpha-(3)H]DHT formed was confirmed by recrystallization experiments. Pituitary and hypothalamic 5alpha-reductase mRNA content was determined by RNA blot analysis utilizing a rat 5alpha-reductase (type 1 or type 2) cDNA as probe. Pituitary 5alpha-reductase activity was significantly increased as a function of days after castration, whereas castration plus DHT treatment (at Day 12 post-castration) significantly decreased the activity to less than one-third of control levels. In controls, pituitary 5alpha-reductase mRNA content was barely detectable using the rat 5alpha-reductase (type 1) cDNA as probe. However, castration resulted in a clear increase in mRNA abundance, while in DHT-injected castrated animals pituitary mRNA content was undetectable. Hypothalamic mRNA content was clearly detectable in all treatment groups with the rat 5alpha-reductase type 1 probe. However, there were no apparent changes in hypothalamic mRNA abundance as affected by the treatments. On the other hand, pituitary or hypothalamic 5alpha-reductase mRNA was undetectable using the rat 5alphareductase (type 2) cDNA as probe. These results indicate that in the rat pituitary the content of mRNA encoding 5alpha-reductase is negatively regulated by DHT. The increase in pituitary 5alpha-reductase enzymatic activity in castrates is due, in part, to higher mRNA levels detected by the 5alpha-reductase type 1 probe. Hypothalamic 5alpha-reductase mRNA levels (type 1) encoding this protein are not regulated by DHT, but presumably are, to some extent, under transcriptional control.
在（28-40 日龄）雄性大鼠中，评估了去势或用二氢睾酮（5alpha-DHT）进行激素替代治疗对垂体或下丘脑 5alpha-还原酶的影响。通过测量血清 LH 和腹侧前列腺重量来证明治疗的效果。通过用[3H]睾酮孵育后用薄层色谱法分离[5alpha-（3）H]DHT来估计垂体 5alpha-还原酶酶活性，并且通过重结晶实验确认形成的[5alpha-（3）H]DHT 的身份。通过 RNA 印迹分析利用大鼠 5alpha-还原酶（1 型或 2 型）cDNA 作为探针来确定垂体和下丘脑 5alpha-还原酶 mRNA 含量。垂体 5alpha-还原酶活性随着去势后天数的增加而显著增加，而去势加 DHT 处理（去势后第 12 天）则将活性降低至对照水平的三分之一以下。在对照组中，使用大鼠 5alpha-还原酶（1 型）cDNA 作为探针几乎无法检测到垂体 5alpha-还原酶 mRNA 含量。然而，去势导致 mRNA 丰度明显增加，而在 DHT 注射去势的动物中，垂体 mRNA 含量无法检测到。用大鼠 5alpha-还原酶 1 型探针在所有治疗组中均可清晰检测到下丘脑 mRNA 含量。然而，处理对下丘脑 mRNA 丰度没有明显影响。另一方面，用大鼠 5alpha-还原酶（2 型）cDNA 作为探针无法检测到垂体或下丘脑 5alpha-还原酶 mRNA。这些结果表明，在大鼠垂体中，编码 5alpha-还原酶的 mRNA 含量受 DHT 的负调控。去势大鼠垂体 5alpha-还原酶酶活性的增加部分归因于 5alpha-还原酶 1 型探针检测到的更高 mRNA 水平。该蛋白的下丘脑 5alpha-还原酶 mRNA 水平（1 型）不受 DHT 调节，但推测在某种程度上受转录控制。
