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Vertebrate reproductive science and technology
RESEARCH ARTICLE

Androgen and oestrogen modulation by D-aspartate in rat epididymis

S. Falvo A , M. M. Di Fiore A , L. Burrone A , G. Chieffi Baccari A , S. Longobardi B and A. Santillo A C
+ Author Affiliations
- Author Affiliations

A Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Seconda Università di Napoli, Via Vivaldi 43, 81100, Caserta, Italy.

B Medical Liaison Office, Merck Serono S.p.A., Via Casilina 125, 00176, Roma, Italy.

C Corresponding author. Email: alessandra.santillo@unina2.it

Reproduction, Fertility and Development 28(12) 1865-1872 https://doi.org/10.1071/RD15092
Submitted: 8 March 2015  Accepted: 5 May 2015   Published: 5 June 2015

Abstract

Testosterone (T) synthesised in Leydig cells enters the epididymis and may there be converted into dihydrotestosterone (DHT) by 5α-reductase (5α-red) or into 17β-oestradiol (E2) by P450 aromatase (P450-aro). D-aspartate (D-Asp) is known to induce T synthesis in the testis. In this study, we investigated the effects of in vivo D-Asp administration in two major regions of the rat epididymis (Region I: initial segment, caput, corpus; Region II: cauda). The results suggest that exogenous D-Asp was taken up by both regions of rat epididymis. D-Asp administration induced a rapid increase in T, followed by a more gradual decrease in the T : DHT ratio in Region I. In Region II, T levels rapidly decreased and the T : DHT ratio was consistently lower relative to the control. Expression of 5α-red and androgen receptor genes showed a good correlation with DHT levels in both regions. D-Asp treatment also induced an increase of both E2 levels and oestradiol receptor-α (ERα) expression in Region I, whereas neither E2 levels nor ERα expression were affected in Region II. The early increase of P450-aro expression in Region I and late increase in Region II suggests a direct involvement of D-Asp modulation in P450-aro gene expression. Our results suggest that D-Asp modulates androgen and oestrogen levels and expression of androgen and oestrogen receptors in the rat epididymis by acting on the expression of 5α-red and P450-aro genes.

Additional keywords: 17β-oestradiol, 5α-reductase, testosterone.


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