Expression of estrogen receptor alpha switches off secretory activity in the epididymal channel of the lizard Podarcis sicula

Abstract

The epididymis in the male reproductive tract allows the survival, viability, and storage of spermatozoa from the testis. In the lizard Podarcis sicula, the epididymis can be regionalized to an initial segment called the caput that comprises the efferent ductules, followed by the middle and terminal segments, respectively termed the corpus and cauda. By means of in situ hybridization and immunocytochemistry, we analyzed the expression of the estrogen receptors of the alpha and beta type (ERα and ERβ) in Podarcis to test the responsiveness of the epididymal regions to estrogen in the annual reproductive cycle of this seasonal breeder. The results show that the efferent ductules and the cauda always express both ERα and ERβ throughout the year. In the corpus, the expression of ERα takes place only at the end of the mating period and continues in the non-reproductive season whereas ERβ is expressed in all phases of the cycle. During the mating season, the cells of the corpus are engaged in massive secretory activity and do not express ERα. Experimental administration of E(2) during this season does not change the expression of ERβ, nor does it affect the efferent ductules and cauda; instead, it inhibits the secretory activity in the corpus and induces the expression of ERα. Taken together, our findings suggest that in the epididymis of Podarcis, the expression of ERα may act as a switch for the secretory activity of the epididymal corpus.

The Involvement of the Androgen Receptor in the Secretion of the Epididymalcorpusin the LizardPodarcis sicula

“…The lumen of the cauda is empty during the nonreproductive season [15]. In Podarcis, we recently found that the expression of ER may act as a switch off for the secretory activity of the epididymal corpus [15]. Now by means of in situ hybridization (ISH) with the homologous Podarcis AR probe just obtained, it is demonstrated that in this lizard the AR expression is continuously present along the epididymis also in animals experimentally 2 International Journal of Zoology treated in the mating period with estradiol-17 (E 2 ).…”

“…In this period the lumen is filled with spermatozoa and secretory granules that pass in the third region, cauda, whose epithelium does not show any changes throughout the year. The lumen of the cauda is empty during the nonreproductive season [15]. In Podarcis, we recently found that the expression of ER may act as a switch off for the secretory activity of the epididymal corpus [15].…”

“…The histological structure of the Podarcis epididymis, the evolution of its reproductive cycle, and the pattern of steroid hormones have been already described in detail [13][14][15]. Briefly, in this lizard the epididymis is a channel of 7-8 mm in length and has been divided into three regions according to the morphological and functional characteristics of the surrounding epithelium [15].…”

“…Briefly, in this lizard the epididymis is a channel of 7-8 mm in length and has been divided into three regions according to the morphological and functional characteristics of the surrounding epithelium [15]. In the region defined caput are including small efferent ductules with ciliate cubic epithelium that does not change during the year [15].…”

“…This expression may be related to the morphophysiology of the epididymal channel during the annual reproductive cycle. To compare the AR expression to the known ERs fluctuation [15] ISH with ER and ER probes on adjacent section was performed.…”