Effect of linoleic acid supplementation on in vitro maturation, embryo development and apoptotic related gene expression in ovine

BACKGROUND Linoleic acid (LA) is a polyunsaturated fatty acid present in high concentrations in follicular fluid, when added to maturation culture media, it affects oocyte competence. OBJECTIVE In the present study, we investigated effect of linoleic acid supplementation on in vitro maturation, embryo development and apoptotic related gene expression in ovine. MATERIALS AND METHODS The experiments conducted on 450 ovine Cumulus-oocyte complexes (COCs) with homogenous ooplasm and more than two compact layers of cumulus cells. For in vitro maturation COCs were randomly allocated into four treatment groups for 24 hr period. Treatment groups were as follow: control maturation media, 0 µM LA, 50 µM LA, 100 µM LA and 200 µM LA. The cumulus cell expansion and blastocysts rates were recorded. Total RNA was isolated from embryo pools, reverse transcribed into cDNA, and subjected to apoptotic gene expression by real-time PCR. RESULTS Highest concentration (200 µM/mL) of LA significantly decreased the rate of fully expanded cumulus cells 24 hr after in vitro maturation (IVM) and the percentage of blastocyste rate compared with the control (p<0.05). These inhibitory effects were associated with an increased in relative mRNA expression of Bax (Bcl-2- associated X) gene compared with controls. CONCLUSION Data obtained in present study suggest that low concentration of LA used for maturation had no deleterious effect on subsequent embryonic development compared to high concentration of LA. Relative expression of Bcl-2 (B-cell lymphoma 2) and Bax in embryos seems to be associated with LA concentration.