In vitro effects of relaxin on gene expression in porcine cumulus-oocyte complexes and developing embryos

Jean M Feugang,Jonathan M Greene,Peter L Ryan,Scott T Willard

doi:10.1186/1477-7827-9-15

Jean M Feugang, Jonathan M Greene + Show 2 more

Open Access

https://doi.org/10.1186/1477-7827-9-15

Copy DOI

Abstract

BackgroundRelaxin hormone peptide is found in porcine follicular and utero-tubal fluids, but its possible actions during early embryo development are still undetermined. Here, we investigated the effects of porcine relaxin during oocyte maturation and embryo development, and gene expression in the pig.MethodsImmature cumulus-oocyte complexes (COCs) were obtained from ovarian follicles of sows. In experiment 1, COCs were matured in the presence of 0, 20, or 40 ng relaxin/ml, or 10% (v/v) porcine follicular fluid. In experiment 2, COCs were in vitro matured, fertilized and resulting embryos were cultured in the presence of 0, 20, or 40 ng relaxin/ml. In experiment 3, COCs were matured in the presence of 40 ng relaxin/ml, fertilized and zygotes were cultured as indicated in experiment 2. We evaluated the proportions of matured oocytes in experiment 1, cleaved and blastocysts on Day 2 and Day 7 post insemination in all experiments. The total cell number of blastocysts was also evaluated. In parallel, transcription levels of both relaxin and its receptors (RXFP1 and RXFP2), as well as a pro- (Bax) and anti- (Bcl2-like 1) apoptotic-related genes were determined. All data were analyzed by ANOVA and significant differences were fixed for P < 0.05.ResultsIn experiment 1, relaxin significantly increased the proportions of matured oocytes and cleaved embryos, as well as the expression level of RXFP2 mRNA compared to RXFP1 (P < 0.05). There was no effect on endogenous expression of relaxin and Bcl2-like1/Bax ratios. In all experiments, relaxin did not affect the proportions of blastocysts, but did significantly increase their total cell numbers (P < 0.05). Furthermore, no effect of relaxin was observed on Bcl2-like1/Bax expression ratios, which were similar between groups.ConclusionsExogenous relaxin influences its own receptors expression, improves oocyte nuclear maturation. Its beneficial effect on total cell number of blastocysts appears to be through a Bcl2-like1/Bax-independent mechanism.

Highlights

Relaxin hormone peptide is found in porcine follicular and utero-tubal fluids, but its possible actions during early embryo development are still undetermined
Gene expression is one of the major events occurring during oocyte maturation and early embryo development, and its perturbation in culture system may contribute to the limited production of high quality blastocysts [1,2,3]
We evaluated the effect of relaxin on embryo development by maturing a total of 1,169 cumulus-oocyte complexes (COCs) in the presence of 0, 20 and 40 ng pRLN/ml (4 to 7 independent replicates, Table 3)

Summary

Introduction

Relaxin hormone peptide is found in porcine follicular and utero-tubal fluids, but its possible actions during early embryo development are still undetermined. Gene expression is one of the major events occurring during oocyte maturation and early embryo development, and its perturbation in culture system may contribute to the limited production of high quality blastocysts [1,2,3] Numerous strategies such as low oxygen tension during culture, co-culture, and utilization of simple or complex media supplemented with various molecules have been developed to improve embryo culture efficiencies [1,4,5,6]. Numerous studies have reported various actions of relaxin on pig reproductive tissues such as cervical and uterine tissues, including modulation of embryo implantation during pregnancy in rats [19,20,21] Despite these physiological conditions, it is not known whether relaxin influences oocyte maturation and/or embryo development in the pig

Methods

Results

Discussion

Conclusion