Expression and molecular characterization of estrogen receptor alpha messenger RNA in male reproductive organs of adult goats

The fact that male estrogen receptor alpha (ER alpha) knockout mice are inf ertile indicates a role for this receptor in male reproduction. Here, objec tives were to evaluate ER alpha expression in male goat reproductive tissue s at the transcriptional level using RNase protection assay (RPA) and in si tu hybridization (ISH), and to clone a partial cDNA for caprine ER alpha us ing reverse transcription-polymerase chain reaction (RT-PCR). For RPA and I SH procedures, a radiolabeled antisense cRNA probe, generated in vitro from the ovine oER8 cDNA template, was employed. Evaluations were made on indiv idual samples obtained from adult goats. Labeled cRNA sense probe was used as a negative control in ISH. A 530-base pair amplicon was generated by RT- PCR from efferent ductules (EDs), epididymis (EP), and testis, cloned from the ED and EP, and sequenced. The caprine ER alpha (cER alpha) cDNA display ed 81%-96% sequence identity with that of other species. A signal indicativ e of ER alpha mRNA was identified by both RT-PCR and RPA in all tissues, bu t was strongest in the ED. Compared with ED, ER alpha signal was sixfold lo wer in the EP, and 66-fold lower in the testis. Similarly, strong ER alpha expression was observed in ED epithelium, whereas little or no signal was d etected in EP or testis by ISH. Thus, among different segments of the male reproductive tract and testis, the highest level of ER alpha mRNA expressio n was found in epithelium of the ED.