Role of insulin-like growth factor 1 on cross-bred Bos indicus cattle germinal vesicle oocytes exposed to heat shock.
Germinal vesicle (GV) oocytes are susceptible to heat stress. However, neither the cellular mechanisms triggered by elevated temperature nor the thermoprotective effects of insulin-like growth factor (IGF) on GV oocytes are completely understood. Therefore, a series of experiments was conducted to determine the direct effects of IGF1 (0, 12.5, 25, 50 and 100ng mL-1) on heat-treated GV oocytes. Butyrolactone-arrested GV oocytes were cultured at 38.5°C (control) or 41°C (heat shock; HS) for 14h in the presence of different concentrations of IGF1. Exposure of GV oocytes to 41°C increased (P<0.05) the number of terminal deoxyribonucleotidyl transferase-mediated fluorescein-dUTP nick end-labelling (TUNEL)-positive oocytes. At concentrations of 12.5 and 25ng mL-1, IGF1 tended to minimise these negative effect of HS (P=0.07). However, neither HS nor IGF1 had any effect on caspase activity. HS also decreased (P<0.05) GV oocyte mitochondrial activity and developmental competence to the blastocyst stage. These deleterious effects of HS were alleviated (P<0.05) by 12.5ng mL-1IGF1. This concentration of IGF1 did not affect cleavage rate, the percentage of TUNEL-positive blastomeres and total blastocyst cell number regardless of temperature. In conclusion, exposure of GV oocytes to HS triggered the apoptotic cascade and compromised oocyte developmental competence. Physiological concentrations of IGF1 had a beneficial effect on heat-shocked GV oocytes.
Department of Pharmacology, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, SP, Rubião Júnior, S/N, 18618-970, Brazil.
Rafaela S
RS
Lima
Department of Pharmacology, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, SP, Rubião Júnior, S/N, 18618-970, Brazil.
Pedro H B
PHB
Risolia
Departament of Biological Sciences, Federal University of São Paulo, 275 Prof. Artur Riedel St., Diadema, SP, 09972-270, Brazil.
Jéssica
J
Ispada
Departament of Animal Reproduction, University of São Paulo, 87 Prof. Dr. Orlando Marques de Paiva Av., São Paulo, SP, 05508-010, Brazil.
Mayra E O A
MEOA
Assumpção
Departament of Animal Reproduction, University of São Paulo, 87 Prof. Dr. Orlando Marques de Paiva Av., São Paulo, SP, 05508-010, Brazil.
José A
JA
Visintin
Departament of Biological Sciences, Federal University of São Paulo, 275 Prof. Artur Riedel St., Diadema, SP, 09972-270, Brazil.
Cássia
C
Orlandi
Department of Pharmacology, Institute of Biosciences, São Paulo State University (UNESP), Botucatu, SP, Rubião Júnior, S/N, 18618-970, Brazil.
Fabíola F
FF
Paula-Lopes
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D020169:Caspases / Q000378:metabolism; D002417:Cattle; D053938:DNA Fragmentation / Q000187:drug effects; D005260:Female; D018869:Heat-Shock Response / Q000187:drug effects / Q000502:physiology*; D006824:Hybridization, Genetic; D059471:In Vitro Oocyte Maturation Techniques; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage / Q000502:physiology*; D008540:Meiosis / Q000187:drug effects / Q000502:physiology; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
D007334:Insulin-Like Growth Factor I; D020169:Caspases