The Effect of Lysophosphatidic Acid duringIn VitroMaturation of Bovine Oocytes: Embryonic Development and mRNA Abundances of Genes Involved in Apoptosis and Oocyte Competence

Abstract

In the present study we examined whether LPA can be synthesized and act duringin vitromaturation of bovine cumulus oocyte complexes (COCs). We found transcription of genes coding for enzymes of LPA synthesis pathway (ATXandPLA2) and of LPA receptors (LPAR 1–4) in bovine oocytes and cumulus cells, followingin vitromaturation. COCs were maturedin vitroin presence or absence of LPA (10−5 M) for 24 h. Supplementation of maturation medium with LPA increased mRNA abundance ofFSTandGDF9in oocytes and decreased mRNA abundance ofCTSsin cumulus cells. Additionally, oocytes stimulated with LPA had higher transcription levels ofBCL2and lower transcription levels ofBAXresulting in the significantly lowerBAX/BCL2ratio. Blastocyst rates on day 7 were similar in the control and the LPA-stimulated COCs. Our study demonstrates for the first time that bovine COCs are a potential source and target of LPA action. We postulate that LPA exerts an autocrine and/or paracrine signaling, through several LPARs, between the oocyte and cumulus cells. LPA supplementation of maturation medium improves COC quality, and although this was not translated into an enhancedin vitrodevelopment until the blastocyst stage, improved oocyte competence may be relevant for subsequentin vivosurvival.