title: Effects of melatonin on in vitro maturation of porcine oocyte and expression of melatonin receptor RNA in cumulus and granulosa cells.
abstract: Melatonin is a multifunctional molecule that mediates several circadian and seasonal processes in animal reproduction. Melatonin and its metabolites are antioxidants and free radical scavengers. We investigated the effects of melatonin on porcine oocyte maturation and embryo development. We then investigated the local expression of the melatonin receptor 1 (MT1) gene in cumulus cells, granulosa cells, and the oocytes with the reverse transcription-polymerase chain reaction (RT-PCR) method. We further evaluated the antioxidant effects [reactive oxygen species (ROS) levels in cumulus-oocytes complexes] of melatonin supplementation during in vitro maturation (IVM). Compared with control, melatonin supplementation (10 ng/mL) during IVM resulted in a greater proportion of oocytes extruding the polar body (75.6% versus 84.6%). Significantly greater proportion of parthenogenetically activated oocytes developed to blastocysts when the in vitro medium was supplemented with melatonin; however, cleavage frequency and blastocyst cell number were not affected by the treatment. RT-PCR analysis revealed the expression of MT1 gene in cumulus and granulosa cells but not in oocytes. Melatonin-treated oocytes had significantly lower levels of ROS than did control (untreated) oocytes. We conclude that exogenous melatonin has beneficial effects on nuclear and cytoplasmic maturation during porcine IVM. Some of the observed effects may be mediated by receptor binding and while others may have been receptor independent, e.g., direct free radical scavenging.
authors.affiliation: Department of Theriogenology and Biotechnology, College of Veterinary Medicine, Seoul National University, Seoul, Korea.
authors.forename: Jung-Taek
authors.initials: JT
authors.lastname: Kang
authors.forename: Ok-Jae
authors.initials: OJ
authors.lastname: Koo
authors.forename: Dae-Kee
authors.initials: DK
authors.lastname: Kwon
authors.forename: Hee-Jung
authors.initials: HJ
authors.lastname: Park
authors.forename: Goo
authors.initials: G
authors.lastname: Jang
authors.forename: Sung-Keun
authors.initials: SK
authors.lastname: Kang
authors.forename: Byeong-Chun
authors.initials: BC
authors.lastname: Lee
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002970:Cleavage Stage, Ovum; D054885:Cumulus Cells / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D004622:Embryo, Mammalian; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006861:Hydrogen Peroxide / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D009865:Oocytes / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D044122:Receptor, Melatonin, MT1 / Q000096:biosynthesis / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine
chemical_list: D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D044122:Receptor, Melatonin, MT1; D006861:Hydrogen Peroxide; D008550:Melatonin