Short-Term culture of in vitro produced bovine preimplantation embryos with insulin-like growth factor-i prevents heat shock-induced apoptosis through activation of the Phosphatidylinositol 3-Kinase/Akt pathway

• Published in: Molecular reproduction and development Vol. 75; no. 4; pp. 681 - 688
• Main Authors: Jousan, F. Dean, Oliveira, Lilian J., Hansen, Peter J.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.04.2008; Wiley-Liss
• Subjects: Animals; apoptosis; Apoptosis - drug effects; Apoptosis - physiology; Biological and medical sciences; bovine; Cattle; Cell physiology; Effects of physical and chemical agents; embryo; Embryo Culture Techniques; Embryonic Development - drug effects; Embryonic Development - physiology; Fertilization in Vitro; Fundamental and applied biological sciences. Psychology; heat shock; Heat-Shock Response - physiology; Hot Temperature - adverse effects; Insulin-Like Growth Factor I - pharmacology; insulin-like growth factor-I; Molecular and cellular biology; Phosphatidylinositol 3-Kinases - antagonists & inhibitors; Phosphatidylinositol 3-Kinases - metabolism; Phosphorylation; Proto-Oncogene Proteins c-akt - antagonists & inhibitors; Proto-Oncogene Proteins c-akt - metabolism; Time Factors; Culture medium; Temperature; Embryo; Environmental factor; Ox; heat shock; In vitro; Phosphatidylinositol; insulin-like growth factor-I; Vertebrata; Heat; Insulin like growth factor; Mammalia; Thermal shock; bovine; Artiodactyla; Protection; Ungulata; Apoptosis
• ISSN: 1040-452X; 1098-2795
• DOI: 10.1002/mrd.20830

Insulin‐like growth factor (IGF‐I) has been implicated as a thermoprotective molecule for the preimplantation bovine embryo. Here, it was shown that effects of heat shock (41°C for 15 hr) on induction of apoptosis and reduction in cell number in bovine embryos collected at Day 5 after fertilization were blocked by addition of 100 ng/ml IGF‐I at the initiation of heat shock. This action of IGF‐I to block heat shock‐induced apoptosis was eliminated if embryos were cultured with either a phosphatidylinositol 3‐kinase (PI3K) inhibitor (wortmannin) or an Akt inhibitor (1L‐6‐hydroxymethyl‐chiro‐inositol 2‐(R)‐2‐o‐methyl‐3‐o‐octadecylcarbonate). Immunofluorescence microscopy confirmed the expression of phosphorylated Akt for IGF‐I and control embryos. Immunoblotting using an antibody to Akt (phospho S473) indicated increased phosphorylation of Akt in IGF‐I‐treated embryos. In conclusion, short‐term treatment of embryos with IGF‐I can block induction of apoptosis caused by heat shock through signaling events requiring PI3K and Akt. Mol. Reprod. Dev. 75: 681–688, 2008. © 2007 Wiley‐Liss, Inc.