Localization of plasminogen activator and inhibitor, LH and androgen receptors and inhibin subunits in monkey epididymis

Epididymis is a site of sperm maturation and storage. Limited anddirected-proteolysis regulated by plasminogen activator (PA), plasminogenactivator inhibitor type-1 (PAI-1) and other related factors may play anessential role in these processes. Our previous studies have demonstratedthat rat epididymis expressed luteinizing hormone receptor (LHR), tissuetype (t) and urokinase type (u)PA, mRNAs, and tPA activity was stimulatedin vitro by human chorionic gonoadotrophin (HCG). In the present study wefurther examined localization of mRNAs for tPA, uPA, LHR, androgen receptor(AR), as well as inhibin subunits alpha, betaA and betaB in rhesus monkeyepididymis. Using in-situ hybridization with digoxygenin-labelled cRNAprobes, we have demonstrated that tPA and PAI-1 mRNAs were localized inepithelial cells of adult monkey epididymis. uPA mRNA was localized in thesame areas, but to a much smaller extent. tPA, uPA and PAI-1 mRNAs weregreatly expressed in the caput and corpus of adult epididymis than in otherregions. In-vitro experiments showed that both tPA and uPA activities inepididymal cells were dramatically stimulated by HCG, but not by folliclestimulating hormone (FSH). LHR (but not FSH receptor) and AR mRNAs werelocalized in the epithelial cells of the epididymis. However, LHR mRNA wasdetected in both adult and immature infant monkeys, whereas AR was foundonly in the adult. Inhibin alpha, betaA and betaB mRNAs were also detectedin this organ, betaA mRNA being more strongly expressed in the caput thanin other regions of the epididymis. We suggest that LH and androgen may bethe key hormones in coordination with the PA-PAI-1 system in regulatingepididymal differentiation and sperm maturation.