In most mammals, metaphase II (MII) oocytes having high maturation promoting factor (MPF) activity have been considered as good oocytes and then used for assisted reproductive technologies including somatic cell nuclear transfer (SCNT). Caffeine increases MPF activity in mammalian oocytes by inhibiting p34cdc2 phosphorylation. The objective of this study was to investigate the effects of caffeine treatment during in Vitro maturation (IVM) on oocyte maturation and embryonic development after SCNT in pigs. To this end, morphologically good (MGCOCs) and poor oocytes (MPCOCs) based on the thickness of cumulus cell layer were untreated or treated with 2.5 mM caffeine during 22-42, 34-42, or 38-42 h of IVM according to the experimental design. Caffeine treatment for 20 h during 22-42 h of IVM significantly inhibited nuclear maturation compared to no treatment. Blastocyst formation of SCNT embryos was not influenced by the caffeine treatment during 38-42 h of IVM in MGCOCs (41.1-42.1%) but was significantly improved in MPCOCs compared to no treatment (43.4 vs. 30.1%, P<0.05). No significant effects of caffeine treatment was observed in embryo cleavage (78.7-88.0%) and mean cell number in blastocyst (38.7-43.5 cells). The MPF activity of MII oocytes in terms of p34cdc2 kinase activity was not influenced by the caffeine treatment in MGCOCs (160.4 vs. 194.3 pg/ml) but significantly increased in MPCOCs (133.9 vs. 204.8 pg/ml). Our results demonstrate that caffeine treatment during 38-42 h of IVM improves developmental competence of SCNT embryos derived from MPCOCs by influencing cytoplasmic maturation including increased MPF activity in IVM oocytes in pigs.

• 이주형(강원대학교 동물의학종합연구소) | Joohyeong Lee (Institute of Veterinary Science, Kangwon National University, Chuncheon 24341, Korea)
• 유진영(강원대학교 수의과대학) | Jinyoung You (College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea)
• 이한나(강원대학교 수의과대학) | Hanna Lee (College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea)
• 신혜지(강원대학교 수의과대학) | Hyeji Shin (College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea)
• 이근식(강원대학교 수의과대학) | Geun-Shik Lee (College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea)
• 이승태(강원대학교 동물생명과학대학) | Seung Tae Lee (Division of Applied Animal Science, College of Animal Life Science, Kangwon National University, Chuncheon 24341, Korea)
• 이은송(강원대학교 동물의학종합연구소) | Eunsong Lee (Institute of Veterinary Science, Kangwon National University, Chuncheon 24341, Korea) Corresponding author