40 Administration of 0.1 μM melatonin during in vitro maturation of bovine oocytes regulates autophagy levels in produced embryos

Melatonin, the antioxidant pineal hormone, is a strong regulator for various cellular processes essential for reproduction. Although the protective role of 0.1 µM melatonin against the toxicity of different anti-developmental compounds has been elucidated in numerous studies, its effect on the autophagy level in invitro-produced blastocysts has not been entirely clarified. In this study, oocytes were incubated for 24 h in the presence and absence of melatonin, administered during IVM, to investigate the effect of 0.1 µM melatonin on the developmental competence of bovine oocytes and pre-implantation embryos, autophagy, and quality of embryos. The developmental potential of embryos were basically the stages from oocytes fertilization to blastocyst production. Gene expression levels were evaluated in matured oocytes, whereas blastocysts were used for immunofluorescence experiments. The differences between treated and control groups were analysed using Student’s t-test (GraphPad Prism version 6; GraphPad Inc.), where P-values  0.05), whereas the level of reactive oxygen species (ROS) was reduced (P   0.05) were overexpressed, in Day-8 embryos of melatonin-treatment. Additionally, the total number of cells per blastocysts, inspected via nuclei-based 4′,6-diamidino-2-phenylindole (DAPI) staining was higher in the melatonin-treated group (P < 0.05). Taken together, our study demonstrates that 0.1 µM melatonin treatment during IVM does not interfere with developmental competence, but improves the quality of IVF-produced embryos by lowering the incidence of autophagy.