Activity and expression of 5alpha-reductase in human sebaceous glands and apocrine glands

双氢睾酮是由睾酮在靶组织中通过5 α还原酶形成的，在雄激素作用中起着关键作用。本研究的目的是确定在人类皮脂腺和大汗腺中存在哪种5 - α还原酶同工酶（型或2型）。在显微镜下，从吸痰手术中获得的皮肤样本中解剖大汗腺。分离的大汗腺在70℃下保存，大汗腺匀浆与50nM或1muM的^ 3h -睾酮和1mM的NADPH孵育20分钟。得到了以下结果：(1) pH的影响：两种浓度的睾酮均在pH6-7.5时活性最佳。在三个病例中得到了类似的结果。(2)睾酮浓度与5α -还原酶活性的关系：睾酮浓度从2nM变化到60muM。结果表明存在一种单一的酶。根据Lineweaver-Burk图估计，Michaelis常数约为21muM。(3) 1型抑制剂MK386的作用：在睾酮浓度为50nM时，加入25nM的MK386，酶活性降低至近20%。(4) RT-PCR分析显示，在25个循环时检测到type1 mRNA的表达，而在35个循环时也未检测到type2 mRNA。因此，结合我们之前的研究表明，双氢睾酮在汗腺核中占主导地位，我们目前的数据清楚地表明，1型同工酶负责大汗腺中的雄激素作用，就像皮脂腺一样，而不是像前列腺一样。

Dihydrotestosterone, which is formed from testosterone by 5alpha-reductase in the target tissue, plays a key role in the androgen action. The goals of this study were to identify which isozyme of 5alpha-reductase (typel or type2) is present in the human sebaceous glands and apocrine glands.Apocrine sweat glands were dissected under a microscope from skin samples obtained by suction at surgical treatment of osmidrosis. Isolated apocrine glands were stored at-70 C.Homogenates of apocrine glands were incubated with 50nM or 1muM of ^3H-testosterone and 1mM of NADPH for 20 min. The following results were obtained. (1) Effect of pH : Optimal activity was observed at pH6-7.5 at both concentrations of testosterone. Similar results were obtained in three cases. (2) Relation between testosterone concentraion and 5alpha-reductase activity : Testosterone concentrations were changed from 2nM to 60muM.The results suggested the presence of a single enzyme. The Michaelis constant was about 21muM as estimated from Lineweaver-Burk plots. (3) Effexts of type1 inhibitor, MK386 : The enzyme activity was decreased to nearly 20% by the addition of 25nM of MK386 at the testosterone concentration of 50nM.(4) RT-PCR analysis revealed that type1 mRNA expression was detected at 25 cycles, whereas type2 mRNA was not detected even at 35 cycles.Thus, together with our previous study which showed the predominance of dihydrotestosterone in the nuclei of the apocrine gland of osmidrosis, our present data clearly demonstrate that type1 isozyme is responsible for the androgen action in the apocrine gland like in the sebaceous gland, but not like in the prostate.