title: Insulin-like growth factor-1 (IGF-1) enhances developmental competence of cat embryos cultured singly by modulating the expression of its receptor (IGF-1R) and reducing developmental block.
abstract: OBJECTIVE
  The aim of this study is to determine the effects of insulin-like growth factor-1 (IGF-1) and the mRNA expression of IGF-1 receptor (IGF-1R) during the in vitro development of cat embryos cultured in groups versus singly.
  
  
  METHODS
  Cumulus-oocyte complexes (COCs) were matured and fertilized in vitro with frozen-thawed semen. Cleaved embryos (48h post-fertilization) were randomly assigned to one of the following treatments: 1) group embryo culture without IGF-1 (10 embryos per 50μl droplet), 2) single-embryo culture without IGF-1, and 3) to 6) single-embryo culture (50μl droplet per embryo) supplemented with different concentrations of IGF-1 (5, 25, 50 and 100ng/ml, respectively). During in vitro culture, the embryos were analyzed for development to the morula, blastocyst and hatching blastocyst stage. Relative mRNA expression of IGF-1R was also examined by qPCR at the morula and blastocyst stages. In addition, the mRNA expression of IGF-1R in morula-stage embryos treated with IGF-1 was determined. The influence of IGF-1 to preimplantation embryo development was then explored by co-incubation with 0.5μM IGF-1R inhibitor (Picropodophyllin; PPP).
  
  
  RESULTS
  Group embryo culture led to a significantly higher blastocyst development rate compared with single-embryo culture (P<0.05). The poor development of singly cultured embryos coincided with the significantly lower IGF-1R expression in morulae than in group-cultured morulae. IGF-1 (25 or 50ng/ml) supplementation significantly improved the blastocyst formation rate of single embryos to a level similar to group culture by promoting the morula-to-blastocyst transition. IGF-1 supplementation (25 or 50ng/ml) of singly cultured embryos upregulated the expression of IGF-1R mRNA in morula-stage embryos to the same level as that observed in group-cultured embryos (without IGF-1). The beneficial effects of IGF-1 on singly cultured embryo were (P<0.05) suppressed by PPP even in the group culture embryo without growth factor supplementation.
  
  
  CONCLUSIONS
  IGF-1 supplementation improves the developmental competence of feline embryos cultured individually and also increases IGF-1R gene expression to levels similar to group-cultured embryos.
authors.affiliation: Department of Obstetrics, Gynaecology and Reproduction, Chulalongkorn University, Faculty of Veterinary Science, Bangkok 10330, Thailand.
authors.forename: Chommanart
authors.initials: C
authors.lastname: Thongkittidilok
authors.affiliation: Department of Obstetrics, Gynaecology and Reproduction, Chulalongkorn University, Faculty of Veterinary Science, Bangkok 10330, Thailand.
authors.forename: Theerawat
authors.initials: T
authors.lastname: Tharasanit
authors.affiliation: Department of Obstetrics, Gynaecology and Reproduction, Chulalongkorn University, Faculty of Veterinary Science, Bangkok 10330, Thailand.
authors.forename: Thanida
authors.initials: T
authors.lastname: Sananmuang
authors.affiliation: Department of Obstetrics, Gynaecology and Reproduction, Chulalongkorn University, Faculty of Veterinary Science, Bangkok 10330, Thailand.
authors.forename: Sirirak
authors.initials: S
authors.lastname: Buarpung
authors.affiliation: Department of Obstetrics, Gynaecology and Reproduction, Chulalongkorn University, Faculty of Veterinary Science, Bangkok 10330, Thailand. Electronic address: tmongkol@chula.ac.th.
authors.forename: Mongkol
authors.initials: M
authors.lastname: Techakumphu
mesh_terms: D000818:Animals; D002415:Cats / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D002478:Cells, Cultured; D002970:Cleavage Stage, Ovum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D003470:Culture Media / Q000494:pharmacology; D046149:Embryo Culture Techniques / Q000662:veterinary; D004622:Embryo, Mammalian; D047108:Embryonic Development / Q000187:drug effects*; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008297:Male; D017526:Receptor, IGF Type 1 / Q000235:genetics* / Q000378:metabolism
chemical_list: D003470:Culture Media; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1
keywords: Cat; Cultured singly; Embryo; Insulin like growth factor-1 receptor (IGF-1R); Insulin-like growth factor-1 (IGF-1); mRNA expression