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

1996 Fiscal Year Final Research Report Summary

• Project/Area Number: 07670953
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Dermatology
• Research Institution: Oita Medical University
• Principal Investigator: TAKAYASU Susumu Oita Medical University, Dermatology, Professor, 医学部, 教授 (20028468)
• Co-Investigator(Kenkyū-buntansha): SATO Toshihiro Oita Medical University, Dermatology, Instructor, 医学部, 助手 (70244176) ; KURATA Sotaro Oita Medical University, Dermatology, Assistant professor, 医学部, 講師 (40186490)
• Project Period (FY): 1995 – 1996
• Keywords: Apocrine gland / 5alpha-Reductase / Isozyme

Research Abstract

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.