Reproduction, Fertility and Development Reproduction, Fertility and Development Society
Vertebrate reproductive science and technology
RESEARCH ARTICLE

The influence of dopaminergic system inhibition on biosynthesis of gonadotrophin-releasing hormone (GnRH) and GnRH receptor in anoestrous sheep; hierarchical role of kisspeptin and RFamide-related peptide-3 (RFRP-3)

M. Ciechanowska A D , M. Łapot A , E. Paruszewska A , W. Radawiec B and F. Przekop C
+ Author Affiliations
- Author Affiliations

A Department of Pharmacology and Toxicology, The General Karol Kaczkowski Military Institute of Hygiene and Epidemiology, Kozielska 4, 01-163 Warsaw, Poland.

B The University of Warmia and Mazury, M. Oczapowskiego 2, 10-719 Olsztyn, Poland.

C Department of Neuroendocrinology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Instytucka 3, 05-110 Jabłonna, Poland.

D Corresponding author. Email: mciechanowska@wihe.waw.pl

Reproduction, Fertility and Development - https://doi.org/10.1071/RD16309
Submitted: 9 August 2016  Accepted: 14 September 2017   Published online: 12 October 2017

Abstract

This study aimed to explain how prolonged inhibition of central dopaminergic activity affects the cellular processes governing gonadotrophin-releasing hormone (GnRH) and LH secretion in anoestrous sheep. For this purpose, the study included two experimental approaches: first, we investigated the effect of infusion of sulpiride, a dopaminergic D2 receptor antagonist (D2R), on GnRH and GnRH receptor (GnRHR) biosynthesis in the hypothalamus and on GnRHR in the anterior pituitary using an immunoassay. This analysis was supplemented by analysis of plasma LH levels by radioimmunoassay. Second, we used real-time polymerase chain reaction to analyse the influence of sulpiride on the levels of kisspeptin (Kiss1) mRNA in the preoptic area and ventromedial hypothalamus including arcuate nucleus (VMH/ARC), and RFamide-related peptide-3 (RFRP-3) mRNA in the paraventricular nucleus (PVN) and dorsomedial hypothalamic nucleus. Sulpiride significantly increased plasma LH concentration and the levels of GnRH and GnRHR in the hypothalamic–pituitary unit. The abolition of dopaminergic activity resulted in a significant increase in transcript level of Kiss1 in VMH/ARC and a decrease of RFRP-3 in PVN. The study demonstrates that dopaminergic neurotransmission through D2R is involved in the regulatory pathways of GnRH and GnRHR biosynthesis in the hypothalamic–pituitary unit of anoestrous sheep, conceivably via mechanisms in which Kiss1 and RFRP-3 participate.

Additional keywords: dopamine, ewe, GnRHR, hypothalamus, pituitary.


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