Luteolin supplementation during porcine oocyte maturation improves the developmental competence of parthenogenetic activation and cloned embryos.

Luteolin (Lut), a polyphenolic compound that belongs to the flavone subclass of flavonoids, possesses anti-inflammatory, cytoprotective, and antioxidant activities. However, little is known regarding its role in mammalian oocyte maturation. This study examined the effect of Lut supplementation during in vitro maturation (IVM) on oocyte maturation and subsequent developmental competence after somatic cell nuclear transfer (SCNT) in pigs. Lut supplementation significantly increased the proportions of complete cumulus cell expansion and metaphase II (MII) oocytes, compared with control oocytes. After parthenogenetic activation or SCNT, the developmental competence of Lut-supplemented MII oocytes was significantly enhanced, as indicated by higher rates of cleavage, blastocyst formation, expanded or hatching blastocysts, and cell survival, as well as increased cell numbers. Lut-supplemented MII oocytes exhibited significantly lower levels of reactive oxygen species and higher levels of glutathione than control MII oocytes. Lut supplementation also activated lipid metabolism, assessed according to the levels of lipid droplets, fatty acids, and ATP. The active mitochondria content and mitochondrial membrane potential were significantly increased, whereas cytochrome c and cleaved caspase-3 levels were significantly decreased, by Lut supplementation. These results suggest that Lut supplementation during IVM improves porcine oocyte maturation through the reduction of oxidative stress and mitochondria-mediated apoptosis.

Exogenous γ-tocotrienol promotes preimplantation development and improves the quality of porcine embryos.

γ-tocotrienol (GTT), an isomer of vitamin E, has been the subject of increasing interest due to its strong anti-oxidant effects. Therefore, in this study, the effects of GTT on blastocyst development, expression levels of reactive oxygen species (ROS) and apoptotic index were investigated in preimplantation porcine embryos. After in vitro maturation and fertilisation, porcine embryos were cultured for 6 days in porcine zygote medium 3 supplemented with or without GTT (200µM) under oxidative stress conditions (200µM hydrogen peroxide (H2O2)). Blastocyst development was significantly improved in the GTT-treated group when compared with the H2O2-treated group (P<0.05). Subsequent evaluation of the intracellular levels of ROS and numbers of apoptotic nuclei in GTT-treated blastocysts revealed that ROS levels of GTT-treated porcine blastocysts were decreased (P<0.05) and the numbers of apoptotic nuclei were reduced by GTT treatment in porcine embryos. Moreover, the total cell numbers of blastocysts were significantly increased in the GTT-treated group relative to the untreated group under H2O2-induced oxidative stress (P<0.05). The expression levels of apoptosis-related genes (BCL-XL, BAX) in GTT-treated blastocysts were then investigated using real-time reverse transcription polymerase chain reaction. Expression of the anti-apoptotic BCL-XL gene was shown to be increased in the GTT-treated blastocyst group, whereas expression of the pro-apoptotic BAX gene was decreased. Taken together, these results suggest that GTT (200µM) under H2O2-induced oxidative stress, thereby improving the developmental competence of porcine embryos via modulation of intracellular levels of ROS and the apoptotic index during the preimplantation stage.

Prostacyclin stimulates embryonic development via regulation of the cAMP response element-binding protein-cyclo-oxygenase-2 signalling pathway in cattle.

Prostacyclin (PGI(2)) in oviducal fluid is synthesised from arachidonic acid by cyclo-oxygenase (COX) and prostacyclin synthetase and enhances the implantation and live birth potential of mouse embryos. In the present study, we investigated the developmental competence of bovine embryos by examining the effects of the PGI(2) analogue iloprost on blastocyst development, quality and COX-2 expression during IVF and somatic cell nuclear transfer (SCNT). Bovine IVF and SCNT embryos were cultured in CR1-aa medium supplemented with 0.3% bovine serum albumin in either the presence or absence of 1 mum iloprost at 38.5 degrees C and 5% CO(2). After 3 days of culture, cleaved embryos were cultured for 4 days in the same medium supplemented with 10% fetal bovine serum. For both IVF and SCNT embryos, iloprost improved the blastocyst developmental rate and cell numbers. In the presence of iloprost, the proportion of expanded blastocysts was significantly higher among the IVF embryos and fewer apoptotic cell nuclei were observed. Expression of COX-2 mRNA and protein, evaluated using real-time polymerase chain reaction and immunoblotting, respectively, was increased in the presence of iloprost. These results suggest that PGI(2) improves the developmental competence of embryos via regulation of the cAMP response element-binding protein-COX-2 signalling pathway in cattle.