131 APOPTOSIS AND DEVELOPMENT OF IN VITRO-PRODUCED BOVINE EMBRYOS EXPOSED TO SUPRAPHYSIOLOGICAL CONCENTRATIONS OF INSULIN-LIKE GROWTH FACTOR-1 (IGF-1)
M. A. Velazquez A B and H. Niemann AA Institute of Farm Animal Genetics, Mariensee, Neustadt, Germany;
B Escuela Superior de Ciencias Agropecuarias, Escárcega, Campeche, México
Reproduction, Fertility and Development 21(1) 165-165 https://doi.org/10.1071/RDv21n1Ab131
Published: 9 December 2008
Abstract
It has been hypothesized that high non-physiological IGF-1 levels are partially responsible for the recurrent pregnancy loss observed in women with the polycystic ovary syndrome (Eng GS et al. 2007 Diabetes 56, 2228–2234). The aim of this study was to determine the effect of supraphysiological concentrations of IGF-1 on blastocyst production and the occurrence of apoptosis in bovine embryos, which are a good model for human embryo development (Baumann CG et al. 2007 Mol. Reprod. Dev. 74, 1345–1353). COC obtained by slicing from abattoir ovaries were matured (TCM-199, Sigma) for 24 h and fertilized (Fert-TALP) for 18 h (Day 0) in vitro. Two different IGF-1 (Recombinant human IGF-1, R&D Systems GmbH, Wiesbaden, Germany) concentrations (supraphysiological = 1000 ng mL–1 and physiological = 100 ng mL–1) were added to the culture media (Synthetic oviduct fluid/BSA) and compared with a control group (no IGF-1 supplementation). On Day 8, blastocyst rates (22 replicates) were recorded and DNA degradation was detected in blastocyst nuclei using a cell death detection kit (Roche Diagnostics GmbH, Mannheim, Germany) based on the terminal deoxinucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) principle. Embryos (n = 27 [control], n = 29 [both IGF-1 groups]) from 4 replicates were examined by confocal laser scanning microscopy. Data were analyzed by ANOVA and the Fisher exact test using the SigmaStat 2.0 software package (Jandel Scientific, San Rafael, CA). Cleavage was numerically improved by both, 1000 (59.1 ± 1.8) and 100 (58.2 ± 2.8) ng IGF-1 over controls (53.5 ± 2.2), but the differences did not reach statistical significance (P = 0.22). The proportion of hatched blastocysts was enhanced by 100 (5.8 ± 1.0, P = 0.03) and 1000 (5.1 ± 0.7, P = 0.03) ng IGF-1 compared to controls (2.8 ± 0.6). Total blastocyst rate was increased by 100 ng IGF-1 (34.4 ± 1.9, P = 0.02) over controls (28.3 ± 1.7), but not by 1000 ng IGF-1 (29.1 ± 1.6 P = 0.75). The 100 ng IGF-1 group (38.5 ± 3.7) had fewer degenerated embryos (P = 0.01) compared to 1000 ng IGF-1 (49.7 ± 3.3). The proportion of embryos displaying at least one apoptotic cell was greater in the 1000 ng IGF-1 group over controls (96% v. 77% P = 0.04). The number of blastomeres with TUNEL-positive nuclei per embryo was higher in the supraphysiological group (5.5 ± 0.6, P < 0.001) compared with the control (2.3 ± 0.4) and the physiological group (2.5 ± 0.3). There were no significant differences between the control and the 100 ng IGF-1 group in this regard (P = 0.49). In conclusion, supraphysiological concentrations of IGF-1 do not increase blastocyst production but increase levels of apoptosis in bovine embryos produced in vitro.
M. A. V. is in the PhD program of the University of Veterinary medicine, Hannover, Germany, and is supported by the German Academic Exchange Service (DAAD)
