Pyrroloquinoline quinone promotes porcine oocyte in vitro maturation and subsequent embryo development by enhancing lipid metabolism and improving mitochondrial func-tion.

Objective: The present study evaluated the beneficial effects of pyrroloquinoline quinone (PQQ) on porcine oocyte in vitro maturation (IVM) and early embryo development.

Methods: Porcine cumulus oocyte complexes were cultured in IVM medium supplemented with 0, 200 nM, 400 nM, 800 nM or 1600 nM PQQ for 42 h. We first examined cumulus expansion index (CEI) and oocyte nuclear maturation rate, and then assessed oocyte mitochondrial function, oxidative stress levels, lipid metabolism and subsequent embryonic development.

Results: We found that PQQ (800 nM) supplementation significantly increased CEI and the nuclear maturation rate of oocytes after IVM. Furthermore, PQQ (800 nM)-supplemented oocytes showed significantly higher mitochondrial content, mitochondrial membrane potential (MMP) and activity, and the mRNA expression levels of genes related to mitochondria biogenesis (PGC-1a, NRF1, NRF2 and TFAM). Moreover, PQQ significantly reduced the levels of reactive oxygen species (ROS), lipid droplets and fatty acids content, and increased the mRNA expression levels of genes related to antioxidant (SOD1, SOD2, GPX and CAT), lipolysis (ATGL and HSL) and β-oxidation (CPT1B and CPT2) in porcine oocytes. Ultimately, PQQ (800 nM) supplementation significantly increased cleavage rate, blastocyst formation rate, and total blastocyst cell numbers after parthenogenetic activation.

Conclusion: PQQ supplementation during IVM exerts a positive influence on oocyte maturation quality and subsequent embryo development by enhancing mitochondrial function and lipid metabolism and alleviating oxidative stress.