Effects of insulin-like growth factor-1 on cellular and molecular characteristics of bovine blastocysts produced in vitro.
Addition of insulin-like growth factor-1 (IGF-1) to culture medium increases the proportion of bovine embryos that develop to the blastocyst stage and increases embryo survival following transfer to heat-stressed, lactating dairy cows. The objective of the present study was to determine molecular and cellular correlates of these actions of IGF-1. Embryos were produced in vitro and cultured for 7 days with or without 100 ng/ml IGF-1. On d 7 after insemination, grade 1 expanded blastocysts were harvested and used to determine total cell number, percent apoptosis, cell allocation to the inner cell mass and trophectoderm, and the relative abundance of several developmentally important gene transcripts. There was no significant effect of IGF-1 treatment on blastocyst cell number, the proportion of blastomeres that were apoptotic, or the number of cells in the inner cell mass and trophectoderm. However, differences in the relative abundance of several mRNA transcripts were observed between control and IGF-1 treated embryos. Addition of IGF-1 increased (P < 0.02) amounts of mRNA for IGF binding protein-3 and desmocollin II and tended (P < 0.08) to increase amounts of mRNA for Na/K ATPase and Bax. Moreover, IGF-1 treatment decreased (P < 0.05) steady-state amounts of transcripts for heat shock protein 70 and tended (P < 0.08) to reduce amounts of IGF-1 receptor mRNA. In conclusion, increased survival of embryos treated with IGF-1 does not appear due to effects on cell number, percent apoptosis, or cell allocation. Addition of IGF-1 to culture can, however, alter expression of several transcripts which may be important for embryo development and survival following transfer.
Block
Jeremy
J
Department of Animal Sciences, University of Florida, Gainesville, Florida 32611, USA.
Wrenzycki
Christine
C
Niemann
Heiner
H
Herrmann
Doris
D
Hansen
Peter J
PJ
D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001755:Blastocyst / Q000166:cytology / Q000378:metabolism*; D002417:Cattle; D051187:Desmocollins / Q000096:biosynthesis; D046149:Embryo Culture Techniques; D004624:Embryo Transfer; D047108:Embryonic Development / Q000187:drug effects* / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects* / Q000502:physiology; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000096:biosynthesis; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007774:Lactation; D008297:Male; D000254:Sodium-Potassium-Exchanging ATPase / Q000096:biosynthesis; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis
D051187:Desmocollins; D018840:HSP70 Heat-Shock Proteins; D018972:Insulin-Like Growth Factor Binding Protein 3; D051028:bcl-2-Associated X Protein; D007334:Insulin-Like Growth Factor I; D000254:Sodium-Potassium-Exchanging ATPase