Regional Distribution of 5α‐Reductase Type 1 and Type 2 mRNA Along the Nonhuman Primate (Macaca fascicularis) Epididymis

The 5α-reduced metabolites of testosterone, including dihydrotestosterone, are considered the primary regulators of epididymal function. Two genes encode two 5α-reductase isozymes. We examined 5α-reductase type 1 and type 2 mRNA tissue distribution and relative abundance in cynomolgus monkey (Macaca fascicularis) testicular and epididymal tissues using semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). mRNA extracted from monkey tissues including the testis (T) and the proximal caput (PCp), the caput (Cp), the midcorpus (Co), and the distal cauda (Cd) epididymis was reverse transcribed to produce cDNAs. 5α-reductase type 1 and 2 cDNAs were subsequently coamplified with the housekeeping gene, cyclophilin, in a PCR spiked with 33 P-dCTP. Relative abundance was reported as the cpm ratios of type 1 or type 2/cyclophilin mRNA. Semiquantitative RT-PCR results indicated that type 1 mRNA was most abundant in the testis (0.48 ± 0.06) and significantly decreased distally along the monkey epididymis (PCp: 0.29 ± 0.04; Cp: 0.29 ± 0.04; Co: 0.21 ± 0.03; Cd: 0.07 ± 0.01) (P < 0.001). Type 2 mRNA was undetectable in the testis but was present throughout the epididymis at uniform levels (PCp: 1.6 ± 0.2; Cp: 1.4 ± 0.3; Co: 1.6 ± 0.2; Cd: 1.5 ± 0.2). These data demonstrate that 5α-reductase type 1 mRNA is differentially expressed but of low abundance along the nonhuman primate epididymis, whereas 5α-reductase type 2 gene expression is uniform.