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

二氢睾酮是由睾酮通过靶组织中的5 α-还原酶形成的，在雄激素作用中起关键作用。本研究的目的是确定5 α-还原酶（1型或2型）的同工酶是目前在人类皮脂腺和顶泌腺。顶泌汗腺在显微镜下解剖从手术治疗的腋臭抽吸获得的皮肤样本。将分离的顶泌腺保存在-70 ℃。将顶泌腺匀浆与50 nM或1 μ M的^3H-睾酮和1 mM NADPH孵育20分钟。(1)pH的影响：在两种浓度的睾酮下，在pH 6 - 7.5下观察到最佳活性。在三个案例中获得了类似的结果。(2)睾酮浓度与5 α-还原酶活性的关系：睾酮浓度从2nM变化到60 μ M，结果表明存在单一酶。根据Lineweaver-Burk作图法估计米氏常数约为21 μ M。(3)1型抑制剂MK386的作用：在睾酮浓度为50 nM时加入25 nM MK386，酶活性降低至近20%。(4)RT-PCR分析显示，在25个周期时检测到1型mRNA的表达，而在35个周期时未检测到2型mRNA。因此，结合我们先前的研究，我们的数据清楚地表明，1型同工酶是负责雄激素在顶泌腺中的作用，如在皮脂腺中，但不像前列腺

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.