Androgen Receptors Expression in Pituitary of Male Viscacha in relation to Growth and Reproductive Cycle.

Verónica Palmira Filippa,Albana Andrea Marina Cruceño,Gabriela Judith Rosales,Fabian Heber Mohamed

doi:10.1155/2015/168047

Abstract

The aim of this work was to study the androgen receptors (AR) expression in pituitary pars distalis (PD) of male viscachas in relation to growth and reproductive cycle. AR were detected by immunocytochemistry and quantified by image analysis. Pituitary glands from fetus, immature, prepubertal, and adult viscachas during their reproductive cycle were used. In the fetal PD, the immunoreactivity (ir) was mainly cytoplasmic. In immature and prepubertal animals, AR-ir was cytoplasmic (ARc-ir) and nuclear (ARn-ir) in medial region. In adult animals, ARn-ir cells were numerous at caudal end. AR regionalization varied between the PD zones in relation to growth. In immature animals, the ARn-ir increased whereas the cytoplasmic expression decreased in relation to the fetal glands. The percentage of ARc-ir cells increased in prepubertal animals whereas the nuclear AR expression was predominant in adult viscachas. The AR expression changed in adults, showing minimum percentage in the gonadal regression period. The variation of nuclear AR expression was directly related with testosterone concentration. These results demonstrated variations in the immunostaining pattern, regionalization, and number of AR-ir cells throughout development, growth, and reproductive cycle, suggesting the involvement of AR in the regulation of the pituitary activity of male viscacha.

Highlights

Androgens are important steroidal hormones involved in the sexual development and reproduction of male mammals
The androgen receptors (AR)-ir cells were observed throughout the pars distalis (PD) parenchyma, and immunohistochemical results revealed their presence in the nuclei (ARnir) and in the cytoplasm (ARc-ir)
The analysis of the AR expression in the viscacha pituitary gland is essential for a better understanding of the regulatory systems since androgens are involved in the control of the reproductive function

Summary

Introduction

Androgens are important steroidal hormones involved in the sexual development and reproduction of male mammals. They are essential during development and for the maintenance of secondary male characteristics, initiation and continuation of spermatogenesis, and gonadotropin regulation [1]. It has been demonstrated that there is an inverse relationship between the cytoplasmic and nuclear localization, and testosterone administration increases the nuclear expression of AR [6]. Studies of the ontogeny of the AR expression in the developing pituitary gland have been performed in monkeys [14], chickens [15], mice [16], rats [17], and sheep [18], and it has been demonstrated that pituitary AR in mammals is conservative

Objectives

Results

Conclusion