|
(574) ACTIVIN RECEPTOR IIA mRNA and PROTEIN EXPRESSION IN THE NONHUMAN PRIMATE EPIDIDYMIS. Lewis, Rachel1,2, Billeter, Michelle1, Leslie, Susan1, Hermon, Tonia1, Swanson, R. James2, Mahony, Mary1, 1 Department of Obstetrics and Gynecology, Norfolk, VA2 Department of Biological Sciences, Norfolk, VA ABSTRACT- The mammalian epididymis, the major site of sperm maturation and storage, is primarily regulated by androgens and possibly other testicular factors such as activin and inhibin. Previously we reported potent in vitro inhibition of DHT-stimulated 5 KEY WORDS: nonhuman primate epididymis, activin receptor IIA, mRNA, protein |
-reductase type 2 mRNA expression in the macaque epididymis by inhibin. In this study, we determined the localization of the activin receptor IIA (A-RIIA), through which inhibin (and activin) may exert influence on primate epididymal physiology. Semiquantitative RT-PCR, in situ hybridization and immunocytochemistry were employed to measure A-RIIA mRNA and protein expression in testis and epididymal caput (Cp), midcorpus (Co), proximal cauda (pCd) and distal cauda (dCd) regions of four male cynomolgus monkeys (Macaca fascicularis). Semiquantitative RT-PCR expression of A-RIIA mRNA was observed in the epididymal regions although at a decreased level compared to its abundance in the testis (2.5 times more abundant). A-RIIA mRNA expression was confirmed with in situ hybridization. An intense signal was observed in epididymal epithelial cells, where A-RIIA mRNA expression was localized both to the nucleus and scattered throughout the cytoplasm; A-RIIA mRNA expression was only detected in nuclei of epididymal stromal cells. A-RIIA immunoreactivity was observed in the testis, specifically in the primary spermatocytes and spermatids and intertubular regions. In the epididymal epithelium, immunoreactivity was maximal in the Cp and decreased regionally from the Cp to the dCd. Epididymal luminal contents also demonstrated region-specific expression with a decrease of A-RIIA immunoreactivity throughout the length of the epididymis. Late spermatids in the lumen of paraffin-embedded sections of testes exhibited immunoreactivity in the cytoplasmic droplet within the neck region. Flushed epididymal sperm showed immunoreactivity was localized to the acrosomal region and to the cytoplasmic droplet in Cp epididymal sperm, with decreased intensity observed in the acrosomal region of sperm from the distal epididymis. These results suggest both local production of the A-RIIA within the epididymis and its regional distribution in testicular and epididymal sperm providing further insight into a potential role for activin/inhibin in epididymal physiology.