Embryotropic effect of insulin-like growth factor (IGF)-I and its receptor on development of porcine preimplantation embryos produced by in vitro fertilization and somatic cell nuclear transfer

• Published in: Molecular reproduction and development 2005-09, Vol.72 (1), p.88-97
• Main Authors: Kim, Sue, Lee, Gab Sang, Lee, So Hyun, Kim, Hye Soo, Jeong, Yeon Woo, Kim, Ji Hye, Kang, Sung Keun, Lee, Byung Chun, Hwang, Woo Suk
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Birth control; Blastocyst - physiology; Cell Nucleus - metabolism; Embryo Culture Techniques; Female; Fertilization in Vitro; Gene Expression Regulation, Developmental - drug effects; Gene Expression Regulation, Developmental - genetics; Gynecology. Andrology. Obstetrics; IGF-I; IGF-I receptor; Insulin-Like Growth Factor I - pharmacology; IVF; Medical sciences; Nuclear Transfer Techniques; porcine; Receptor, IGF Type 1 - biosynthesis; Receptor, IGF Type 1 - genetics; RNA, Messenger - biosynthesis; RNA, Messenger - genetics; SCNT; Sterility. Assisted procreation
• ISSN: 1040-452X; 1098-2795
• DOI: 10.1002/mrd.20327

Insulin‐like growth factor (IGF)‐I is a receptor‐mediated autocrine/paracrine growth/survival factor for mammalian embryo development. The present study investigated the temporal expression and regulation of porcine IGF‐I receptor (IGF‐IR) mRNA and the role of IGF‐I on development of porcine in vitro fertilized (IVF) and somatic cell nuclear transfer (SCNT) embryos. As assessed by semi‐quantitative reverse transcription‐polymerase chain reaction (RT‐PCR), the level of IGF‐IR mRNA expression was high in unfertilized oocytes, 2‐cell and 4‐cell embryos and gradually decreased in 8‐cell embryos, morulae, and blastocysts in both IVF and SCNT series. The IVF or SCNT embryos were cultured with 0, 1, 10, 50, or 100 ng/ml IGF‐I for 168 hr. Supplementing with 50 ng/ml IGF‐I increased blastocyst formation and the number of cells in inner cell masses (ICMs) in both IVF and SCNT embryos. In a second experiment, more blastocysts were obtained when IVF or SCNT embryos were cultured for the first 48 hr or for the entire 168 hr with 50 ng/ml IGF‐I compared to culturing without IGF‐I for 48 hr or with IGF‐I for the last 120 hr or without IGF‐I for the entire 168 hr. Treating IVF or SCNT embryos with 50 ng/ml IGF‐I significantly up‐regulated IGF‐IR mRNA compared to untreated control embryos. In conclusion, the present study demonstrated that IGF‐IR mRNA is expressed in porcine IVF and SCNT embryos, and that IGF‐I improved the developmental competence of IVF and SCNT embryos through its specific receptors. Mol. Reprod. Dev. © 2005 Wiley‐Liss, Inc.