Effect of antioxidant and poli-unsaturated fatty acids on epididymal sperm in bulls

Author(s)

Marcilio Nichi

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2009-11-27

Examining board members

Valquiria Hyppólito Barnabe; Ricardo Pimenta Bertolla; Sony Dimas Bicudo; Carmen Neusa Martins Cortada; Camila Infantosi Vannucchi

• Advisor: Valquiria Hyppólito Barnabe; Peter Eliza Josef Bols

Abstract

Sperm recovery from the cauda epididymis can be very advantageous, for example: in case of the unexpected death of a genetically highly valuable animal, as an experimental model for research on semen and for the use in endangered species. However, the efficiency of this technique demands the study of several issues such as the storage conditions of the testicles prior semen collection, the effects of cryopreservation and semen extenders, among others. The objective of the present study was: 1- to evaluate the ideal temperature for testicles storage after slaughter (4 or 34ºC) based on functional tests and on in vitro fertility; 2- to evaluate the effect of storage temperature on fresh and cryopreserved semen samples, and; 3- to test the addition of decosaexanoic acid (DHA) and antioxidants to the semen extender. Sperm samples were collected from the caudae epididymides of testicles collected from abattoirs. To test the effect of temperature of storage, testicles were kept under 4 or 34ºC, between two to four hours after slaughter. Semen was then collected from the caudae epididymides and cryopreserved or not. Samples were then evaluated for computer assisted sperm analysis (CASA), membrane integrity and mitochondrial potential (propidium iodide, SYBR and JC1), in vitro fertilization outcomes, and susceptibility to the oxidative stress (TBARS). Results of this study indicated that, with no doubt, storage of testicles under 4ºC is the most appropriate in order to improve post-thaw sperm quality and in vitro fertility. Therefore, this temperature was used in the rest of the study to test the effect of DHA and antioxidant treatments to the semen extender. In this part of the study, semen was evaluated for membrane and acrosome integrities (eosin/nigrosin and fast green/bengal rose stain, respectively), mitochondrial activity (diaminobenzidine stain), DNA integrity (sperm chromatin structure assay SCSA) and, sperm susceptibility to the oxidative stress (TBARS). Results of the present study indicate that due to the treatment with DHA, epididymal sperm became more susceptible to the oxidative stress. On the other hand, different results were found regarding the association between DHA and antioxidant. The association between DHA and superoxide dismutase (SOD) and between DHA and reduced glutathione (GSH) showed better results on sperm motility and membrane integrity, respectively. On the other hand, when associated to the Vitamin E, the DHA showed poor results on mitochondrial activity. Results of the present study indicate that the treatment with DHA and SOD or GSH to epididymal sperm samples collected from testicles stored at 4ºC for up to 4 hours, may improve post-thaw sperm quality. (AU)

• FAPESP's process: 06/05736-1 - Effect of antioxidant and polyunsaturated fatty acid treatment on epididymal sperm samples from Bos taurus taurus bulls
• Grantee: Marcilio Nichi
• Support Opportunities: Scholarships in Brazil - Doctorate