Sperm cryodamage occurs after rapid freezing phase: flow cytometry approach and antioxidant enzymes activity at different stages of cryopreservation

Autor(es)

Castro, L. S. ; Hamilton, T. R. S. ; Mendes, C. M. ; Nichi, M. ; Barnabe, V. H. ; Visintin, J. A. ; Assumpcao, M. E. O. A.

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF ANIMAL SCIENCE AND BIOTECHNOLOGY; v. 7, p. 9-pg., 2016-03-05.

Resumo

Background: In order to improve the efficiency of bovine sperm cryopreservation process, it is important to understand how spermatozoa respond to differences in temperature as well as the ability to recover its own metabolism. The combination between flow cytometry approach and antioxidant enzymes activity allows a more sensible evaluation of sperm cell during cryopreservation. The aim of this study was to evaluate sperm attributes and antioxidant enzymes activity during different stages of cryopreservation process. Semen samples from Holstein bulls (n = 4) were separated in 3 treatments: fresh (37 degrees C); cooled (5 degrees C); and thawed. Evaluation occurred at 0 h and 2 h after incubation. Membrane integrity, mitochondrial membrane potential (MMP) and DNA damages were evaluated by flow cytometry; activities of antioxidant enzymes such as catalase, superoxide dismutase and gluthatione peroxidase were measured by spectrofotometry. Results: There was an increase in the percentage of sperm with DNA damage in the thawed group, compared to fresh and cooled, and for 2 hs of incubation when compared to 0 h. Considering MMP, there was an increase in the percentage of cells with medium potential in thawed group when compared to fresh and cooled groups. Opposingly, a decrease was observed in the thawed group considering high mitochondrial potential. Also in the thawed group, there was an increase on cells with damaged acrosome and membrane when compared to fresh and cooled groups. Significant correlations were found between antioxidant enzymes activity and membrane or mitochondrial parameters. Conclusion: Based on our results, we conclude that cryopreservation affects cellular and DNA integrity and that the critical moment is when sperm cells are exposed to freezing temperature. Also, our study indicates that intracellular antioxidant machinery (SOD and GPX enzymes) is not enough to control cryodamage. (AU)

• Processo FAPESP: 07/58487-1 - Influencia dos indices espermaticos de protamina sobre a fertilidade in vitro em bovinos.
• Beneficiário: Mayra Elena Ortiz D' Avila Assumpcao
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 10/18978-9 - Avaliação da fragmentação do DNA espermático em diferentes etapas da criopreservação
• Beneficiário: Letícia Signori de Castro
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica