Progesterone and Androstenedione Are Important Follicular Fluid Factors Regulating Porcine Oocyte Maturation Quality

Abstract

Oocytes matured in vitro are useful for assisted human and farm animal reproduction. However, the quality of in vitro matured oocytes is usually lower than that of in vivo matured oocytes, possibly due to the absence of some important signal regulators in vitro. In this study, untargeted metabolomics was used to detect the changes in the metabolites in the follicular fluid (FF) during in vivo pig oocyte maturation and in the culture medium during in vitro maturation. Our results showed that the total metabolite changing profile of the in vivo FF was different from that of the in vitro maturation medium, but the levels of 23 differentially expressed metabolites (DEMs) changed by following the same trend during both in vivo and in vitro pig oocyte maturation. These 23 metabolites may be important regulators of porcine oocyte maturation. We found that progesterone and androstenedione, two factors in the ovarian steroidogenesis pathway enriched from the DEMs, were upregulated in the FF during in vivo pig oocyte maturation. The levels of these two factors were 31 and 20 fold, respectively, and they were higher in the FF than in the culture medium at the oocyte mature stage. The supplementation of progesterone and androstenedione during in vitro maturation significantly improved the pig oocyte maturation rate and subsequent embryo developmental competence. Our finding suggests that a metabolic abnormality during in vitro pig oocyte maturation affects the quality of the matured oocytes. This study identified some important metabolites that regulate oocyte maturation and their developmental potential, which will be helpful to improve assisted animal and human reproduction.

Effect of methylparaben on the expression of genes involved in the in vitro maturation of porcine oocytes

“…Because in the pig species, the processes of meiotic resumption as well as oocyte transition to MII are steroid-dependent (Zavareh, et al, 2013), decrease in P4 concentrations could affect IVM. It has been previously reported that adding RU486, a P4 inhibitor, to porcine oocyte maturation medium, decreases IVM and embryo development (Yuan, et al, 2016), while 100 µM of P4 added to porcine COCs culture medium increases IVM and embryo development (Zhao, et al, 2023). Therefore, the decrease in P4 concentrations in oocytes exposed to 650 and 780 µM MePB could explain one of the mechanisms by which IVM decreases.…”

“…It has been previously reported that the concentration of P4 present in the follicular uid is positively related to the development potential of oocytes, making it an indicator of the quality of IVM (Zhao, et al, 2023). Because in the pig species, the processes of meiotic resumption as well as oocyte transition to MII are steroid-dependent (Zavareh, et al, 2013), decrease in P4 concentrations could affect IVM.…”