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

Mariailaria Verderame

doi:10.1155/2014/457830

Abstract

A crucial role in the maintenance of male reproductive functions is carried out by the androgen through its receptor in balance with the estrogen receptors (ERs). The distribution of the androgen receptor (AR) is well documented in the testis and in the reproductive tissues of mammals but the findings about the AR in nonmammalian vertebrates and in particular in reptiles are very scarce. Here by means ofin situhybridization (ISH) we investigated the AR expression along the epididymal channel (efferent ductules,corpus, andcauda) ofPodarcis siculaduring the mating and nonmating period. The results show that in this seasonal breeding species the AR expression pattern is always constant throughout the epididymis. The administration of estradiol-17βin the mating period does not affect the AR expression but inhibits the secretory activity of the epididymalcorpus. To verify the expression pattern of ERs, we also conducted ISH investigations on adjacent sections with ERs probes. The findings suggest that AR induces the secretory activity in the epithelial cells of the epididymalcorpusand confirm our previous results that showed the role of ERalpha (ERα) as switch off for the secretion of this compartment.

Highlights

The epididymis can be regionalized, depending on the species, into the initial segment or caput which includes the efferent ductules, the middle piece or corpus characterized by a high secretory activity, and terminal segment or cauda
The findings suggest that androgen receptor (AR) induces the secretory activity in the epithelial cells of the epididymal corpus and confirm our previous results that showed the role of ERalpha (ERα) as switch off for the secretion of this compartment
During the mating period the epithelium becomes cylindrical and the cells appear elongated, often, binucleated, and engaged in a massive secretory activity. 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

Summary

Introduction

The epididymis can be regionalized, depending on the species, into the initial segment or caput which includes the efferent ductules, the middle piece or corpus characterized by a high secretory activity, and terminal segment or cauda. In these compartments the maturation of spermatozoa takes place before ejaculation [1,2,3,4]. 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] 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 Podarcis, we recently found that the expression of ERα may act as a switch off for the secretory activity of the epididymal corpus [15]

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Discussion

Conclusion