(P-252) Effect of antioxidant procyanidin B2 (PCB2) on ovine oocyte developmental potential in response to in vitro maturation (IVM) and vitrification stress

Abstract Authors: Jiachen Bai, Xxiangwei Fu, Pengcheng Wan

Abstract Text: It was demonstrated that external stress, such as IVM and vitrification process would induce significantly reduced development capacity in oocytes. Previous studies indicated that antioxidants played a pivotal part in the acquisition of adaptation in changed conditions. At present, the role of a natural potent antioxidant PCB2 in response to IVM and vitrification during ovine oocyte manipulation is not explored yet. It aimed to investigate whether PCB2 treatment could improve the developmental potential of ovine oocytes under IVM and vitrification stimuli. The experiment was divided into two parts. Firstly, un-supplemented and 5μg/mL PCB2-supplemented in the IVM solution were considered as control and experimental groups (C + 5μg/mL PCB2). The polar body extrusion (PBE) rate, mitochondrial membrane potential (MMP), ATP, reactive oxygen species (ROS) levels and early apoptosis of oocytes were measured after IVM. Secondly, survival rate, PBE rate and early apoptosis of oocytes were compared within fresh group, vitrified group and 5μg/mL PCB2-supplemented in the IVM solution after vitrification (V + 5μg/mL PCB2). Compared to the control group, adding PCB2 significantly increased PBE rate (79.40% vs. 62.84%, P < 0.01) and MMP level (1.85 vs. 1.30 Δφm, P < 0.01), and decreased ROS level (47.07 vs. 145.33 pixels, P < 0.01). However, there was no significant difference in ATP content and early apoptosis. Compared to the fresh group, vitrification significantly reduced oocytes viability (43.04% vs. 90.78%, P < 0.01) and PBE rate (24.19% vs. 60.57%, P < 0.05). However, 5μg/mL PCB2-supplemention during maturation had no effect on survival rate, PBE rate or early apoptosis in vitrified oocytes. PCB2 could effectively antagonist the oxidative stress during IVM statge and promote oocyte development.