Cellular alterations induced by heat stress in bovine embryos

  • Rafaela Sanchez de Lima Universidade Estadual Paulista, Instituto de Biociências, Botucatu, SP
  • Mayra Elena Ortiz D’Avila Assumpção Universidade de São Paulo, Faculdade de Medicina Veterinária e Zootecnia, Departamento de Reprodução Animal, São Paulo, SP
  • José Antonio Visitin Universidade de São Paulo, Faculdade de Medicina Veterinária e Zootecnia, Departamento de Reprodução Animal, São Paulo, SP
  • Fabíola Freitas de Paula Lopes Universidade Federal de São Paulo, Departamento de Ciências Biológicas, Diadema, SP
Keywords: Heat stress, Embryo, Bovine, Cellular changes

Abstract

Adverse environmental conditions such as high temperature and humidity increase internal body temperature (hyperthermia) of lactating dairy cows resulting in heat stress and decreased pregnancy rates. Embryonic susceptibility to elevated temperature has been well characterized both in vivo and in vitro. Exposure of zygote and two cells stage bovine embryos to elevated temperature decreases embryonic development to the blastocyst stage. However, the bovine embryo becomes more resistant to the deleterious effects of heat stress as it proceeds in its development. The heat-induced reduction in embryonic developmental competence is due, at least in part, to the numerous cytoplasmic and nuclear changes induced by high temperature. In the embryo cytoplasm heat shock increases the number of swollen mitochondria, disrupts microtubules and microfilaments. In the nuclear compartment, elevate temperature induces DNA fragmentation characteristic of apoptosis. This form of cell death is a phenomenon regulated throughout the preimplantation embryonic development, since high temperatures do not trigger apoptosis in embryos of two or four cells. Heat-induced apoptosis in embryos ≥ 16 cells can be seen as a quality control mechanism for removing damaged blastomeres, since block apoptosis in these embryos increase its susceptibility to heat shock. Furthermore, heat stress can also affect the redox status of the embryo inducing a consequent oxidative stress.

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Published
2013-08-17
How to Cite
Lima, R., Assumpção, M. E., Visitin, J. A., & Lopes, F. (2013). Cellular alterations induced by heat stress in bovine embryos. Brazilian Journal of Veterinary Research and Animal Science, 50(4), 257-264. https://doi.org/10.11606/issn.2318-3659.v50i4p257-264
Section
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