PARENT SESSION
MINISYMPOSIUM VIII. Intragonadal Actions of Estrogen.
11:00 AM-12:30 PM
Harborside D
Chair: Findlay, Jock¹, ¹

(M24) ESTROGEN RECEPTORS AND MALE FERTILITY.

Hess, Rex¹, Zhou, Qing¹, Oliveira, Cleida², Nie, Rong¹, Carnes, Kay, Bahr, Janice, ¹ Reproductive Biology & Toxicology, Urbana, IL² Morphology and Physiology, Belo Horizonte-MG, Brazil

ABSTRACT- Testosterone is considered the primary sex steroid in man. However, estrogen is produced in the male and is found in high concentrations in semen. Estrogen in rete testis fluid is now thought to be derived from the conversion of testosterone to estradiol by P450 aromatase, which is found in germ cells of the testis and spermatozoa traversing the male reproductive tract. This luminal source of estrogen targets the estrogen receptors (ER) present in epithelia lining the male tract, and in particular the efferent ductule region, where ER is abundant. ER and ER are expressed in a species-dependent manner in various regions of the epididymal duct and vas deferens. Based upon the ERKO and ERKO mouse models and antiestrogen studies, estrogen's major role in male fertility appears to be focused on the efferent ductules and head of the epididymis. Treatment with the antiestrogen ICI 182,780 in adult wild-type rodents inhibited fluid reabsorption in the efferent ductules of the testis, caused abnormal morphology of the ductal epithelium and testicular atrophy (in the rat), which are pathological changes similar to those seen in ERKO mice. Recent studies have shown that ER is responsible for the expression of NHE₃ (Na⁺/H⁺ exchanger) and transcellular Na⁺ flux across the efferent ductule epithelium. Estrogen is also responsible for what appears to be indirect expression of several other proteins, some of which may be responsible for epithelial morphology. Other labs have found that ER may also be involved by regulating the Cl^-/HCO₃-exchanger and CFTR, but ER function is not essential to fertility. Because of the significance of nuclear steroid receptors to our understanding of reproductive biology, it is important to continue the examination of comparative expressions of ER and down stream events in the male reproductive tract of different mammalian species.

KEY WORDS: estrogen, testis, epididymis, fertility