PARENT SESSION
PLATFORM SESSION 12: GENETICS AND GENOMICS OF THE REGULATION AND EXECUTION OF SPERMATOGENESIS
Chair: McClean, Derek¹, ¹
Co-chair: Hung-Chang Yao, Humphrey¹, ¹
Harborside A
2:00 PM-4:00 PM

(237) EXPRESSION AND REGULATION OF AQP1 AND 9 IN EFFERENT DUCT AND EPIDIDYMIS OF WILD-TYPE AND ERKO MICE.

Hermo, Louis¹, Badran, Haitham¹, Ruz, Ricardo¹, Zhou, Qing², Nie, Rong², Oliveira, Cleida³, Hess, Rex², ¹ Department of Anatomy and Cell Biology, Montreal, Quebec, Canada² Department of Veterinary Biosciences, Urbana, Illinois³ Departamento de Morfologia, Belo Horizonte, MG, Brazil

ABSTRACT- Aquaporins (AQPs) are membrane protein channels that are expressed in many tissues of the body that require the rapid and low energy passage of water across an epithelium. In the male reproductive tract, the efferent ducts (EDs) resorb 90% of the fluid coming from the testis. This serves to concentrate sperm in the initial part of the epididymis allowing for better interactions of the sperm with the epithelial cell secretions and allowing for their maturation. While several AQPs have been demonstrated in the male tract, little is known about the expression of AQPs in the EDs. Estrogen has been suggested to regulate water movement in these ducts. In fact, aERKO mice are infertile and show tubule dilations characteristic of water retention. The purpose was to determine the role of estrogen in regulating the expression of AQPs in epithelial cells of the EDs of mice and rats. Wild type and controls were compared to ERKO mice and antiestrogen ICI 182,780-treated mice and rats. In wild type mice and rats, AQP1 was expressed in nonciliated cells of the EDs on their microvilli, apical endosomes and basolateral plasma membranes, but only in the vascular endothelium of the initial segment (IS), caput, corpus and cauda epididymidis. In ERKO mice and ICI treated mice and rats, AQP1 was not found on the basolateral plasma membranes, but was expressed on the microvilli and apical endosomes, although decreased substantially in the proximal EDs. After 150 days of ICI, there was no AQP1 expression in proximal EDs. Throughout the EDs and epididymis, AQP1 expression in vascular endothelial cells was unaltered. AQP9 was expressed on microvilli of nonciliated cells in EDs and principal cells of the initial segment in mice and rats. In ERKO or ICI-treated mice and rats, while a small decrease in staining was noted in the distal EDs for AQP9, there was a dramatic decrease in staining in the proximal EDs 150 days after ICI treatment. Thus estrogen does not appear to regulate AQP1 expression in the endothelium of vascular channels, nor does it regulate AQP9 expression in principal cells of the IS. Effects on apical AQP1 and AQP9 in the proximal EDs appear to be secondary to the loss of microvilli, but loss of basolateral staining could be due to estrogen′s regulation of targeting of vesicles that transport AQP1 to the basolateral plasma membrane.

KEY WORDS: Aquaporins, ERKO, Efferent Ducts, Estrogen