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Updated: Jun 18, 2026
In Vitro Culture Strategy for Oocytes from Early Antral Follicle in Cattle
Published on: July 8, 2020
Unexpected detrimental effect of Insulin like growth factor-1 on bovine oocyte developmental competence under heat
Mahdi Zhandi1, Armin Towhidi, Mohammad Hossein Nasr-Esfahani
1Department of Animal Science, University College of Agriculture and Natural Resources, University of Tehran, POBox#4111, Karaj, Iran. mzhandi@ut.ac.ir
Purpose:
To investigate the effects of Insulin like growth factor-1 (IGF-1) on bovine oocyte developmental competence under heat stress.
Methods:
In Experiment 1, bovine cumulus-oocyte complexes (COCs) were cultured at 38.5 or 41 degrees C for the first 12 h of maturation in the presence of either 100 ng/ml human recombinant (hr)-IGF-1 or acetic acid. In Experiment 2, COCs were cultured in 38.5 or 41 degrees C for the first 12 h of maturation in the presence either of 100 ng/ml hr-IGF-1 or acetic acid. After fertilization, putative zygotes were cultured for 8 days.
Results:
In experiment 1, addition of rh-IGF-1 to maturation medium at 38.5 degrees C significantly increased the proportion of M II oocytes and decreased the percentage of TUNEL-positive oocytes compared to the other groups. However, addition of rh-IGF-1 to maturation medium under heat stress increased the percentage of TUNEL-positive oocytes. In experiment 2, addition of rh-IGF-1 under heat sress did not affect cleavage rate, whereas, blastocyst formation rate decreased in heat-stressed and heat-stressed plus rh-IGF-1 groups. Similarly, The number of trophectoderm cells and total cell number were decreased in heat-stressed and heat-stressed plus rh-IGF-1 groups and the percentage of TUNEL-positive nuclei were increased in heat-stressed and heat-stressed plus rh-IGF-1 groups compared to the other groups.
Conclusion:
The results of the present study demonstrate that IGF-1 decreases oocyte developmental competence and total cell number and increases TUNEL-positive nuclei at heat stress condition. These unexpected results of IGF-1 during maturation period under heat stress condition warrant further optimizations and investigations.
