REGIONAL DISTRIBUTION OF 5-ALPHA-REDUCTASE TYPE-1 AND TYPE-2 MESSENGER-RNA ALONG THE HUMAN EPIDIDYMIS

Objective: To determine the regional distribution and relative express ion of 5 alpha-reductase type 1 and type 2 mRNA within the human testi s and regions of the epididymis. Design: Prospective observational stu dy. Setting: University academic medical center. Patient(s): Two young adult male organ donors. Intervention(s): None Main Outcome Measure(s ): The distribution of 5 alpha-reductase type 1 and type 2 mRNA in the testis and regions of the epididymis was detected by Northern blot an alysis. The relative abundance of each 5 alpha-reductase mRNA was eval uated using semiquantitative reverse transcriptase-polymerase chain re action (RT-PCR) in which cyclophilin mRNA, a housekeeping gene product , was coamplified as the reference standard. Result(s): Northern blot analysis revealed the 5 alpha-reductase type 2 transcript in the midca put, distal caput, corpus, and proximal cauda of the epididymis, but t he transcript was undetectable in the testis, proximal caput, and dist al cauda region. No transcript for the type 1 isozyme was detected by Northern blot. The more sensitive RT-PCR showed low levels of type 1 m RNA in the testis and epididymis, with the highest abundance in the pr oximal caput. Type 2 mRNA of 5 alpha-reductase was most abundant in th e midcaput, was decreased in the more distal regions, and was more abu ndant than type 1 mRNA in all epididymal regions except for the proxim al caput. Conclusion(s): Both Sa-reductase type 1 and type 2 mRNAs are present in the human epididymis. The type 2 isozyme mRNA is predomina nt, being more highly expressed than the low-abundance type 1 mRNA. (C )1998 by American Society for Reproductive Medicine.