PARENT SESSION
MINISYMPOSIUM XI: Sperm Surface Modifications in the Epididymis
Wednesday, August 1, 2001, 10:30 AM-12:00 PM
Westin-Confederation I
Chair: Edda Toepfer-Peterson
Speakers: Edda Toepfer-Peterson, Louis Hermo, Jean-Jacques Lareyre

EXPRESSION AND REGULATION OF AQUAPORINS 1, 8, AND 9 IN THE TESTIS, EFFERENT DUCTS, AND EPIDIDYMIS OF ADULT RATS AND DURING POSTNATAL DEVELOPMENT.

Hermo, Louis¹, Badram, Haitham¹, ¹

ABSTRACT- Aquaporins (AQPs) are membrane protein channels that allow rapid passage of water through an epithelium containing tight junctions. In the present study, light microscope immunocytochemistry was utilized to localize several members of the aquaporin family in the testis, efferent ducts and epididymis of normal adult animals, during postnatal development and after various experimental procedures on adult animals. In the testis of normal adult animals, AQP-8 was expressed exclusively in Sertoli cells, while AQP-9 outlined Leydig cells. AQP-1 and -9 were both present in the efferent ducts being distributed on the microvilli and/or apical subsurface vesicles of the nonciliated epithelial cells. In the epididymis, AQP-9 was localized to the microvilli of principal cells of all regions with the most intense reaction being noted in the initial segment and cauda regions. Clear cells of the cauda region only expressed AQP-9. AQP-1, was not expressed in the testis or epididymal epithelium, but was expressed over the endothelial cells of vascular channels of the efferent ducts and epididymis. After efferent duct ligation or orchidectomy, there was no change in the expression of AQP-1 or AQP-9 in the case of the efferent ducts suggesting that testicular factors do not regulate their expression in this site. In contrast, AQP-9 expression in principal cells of the initial segment only and clear cells of the cauda region was dramatically reduced. As expression was not maintained at control levels by testosterone replacement, the data suggest that a luminal factor(s) derived from the testis regulates AQP-9 expression in principal and clear cells of the epididymis but in a region specific manner. Postnatal studies revealed that expression of AQP-1 and -9 in the different cell types of the efferent ducts and epididymis occurred between day 7 and 29, eliminating sperm and high androgen levels as possible regulating factors. Taken together, these data suggest cell specificity with respect to expression of AQP-8 and -9 in the testis. In the efferent ducts and epididymis, a cell, region and tissue specificity exists with respect to expression of AQP-1 and -9, and their expression does not appear to be regulated by androgens.

KEY WORDS: Epididymis, Aquaporins, Testis, Efferent Ducts