Estrogen receptors alpha and beta in human testis: both isoforms are expressed

Currently, clinical and experimental evidence point to an essential role of estrogens and estrogen receptors in male fertility. The expression of estrogen receptor alpha (ERalpha) and beta (ERbeta) in human testis has been described. However, some studies were unable to detect ERalpha, while others report the expression of both isoforms, with ERbeta presenting a wide distribution within somatic and germinal testicular cells. This has suggested that estrogens may exert their testicular effects exclusively through ERbeta. The present work aims to study the expression of ERalpha and ERbeta in testicular biopsies of men with conserved and disrupted spermatogenesis, in order to better clarify the positive cell populations. Human testicular tissue was obtained from 10 men undergoing testicular biopsy for infertility relief due to azoospermia: two patients had secondary obstructive azoospermia with conserved spermatogenesis, five had Sertoli cell-only syndrome, two had hypospermatogenesis and one had meiotic arrest. Reverse-transcription polymerase chain reaction (RT-PCR) allowed the detection of both ERalpha and ERbeta mRNAs in all samples. Immunohistochemistry revealed that ERalpha was present in Leydig cells, Sertoli cells, spermatogonia, spermatocytes, round spermatids and elongated spermatids/spermatozoa, while ERbeta was present in the same cell types except spermatogonia and Sertoli cells. This study demonstrates ERalpha mRNA expression in human testis and describes its localization in somatic and germ cell subtypes. These findings suggest that both ER isoforms are involved in the control of testicular function.