Criopreservação de espermatozóides eqüinos comparando duas curvas de congelamento combinadas com diluentes comerciais: uma análise laboratorial / Cryopreservation of equine spermatozoa comparing different freezing rates combined with commercial extenders: laboratorial analysis

RESUMO

Durante o processo de criopreservação de sêmen, os espermatozóides sofrem alguns danos que resultam na diminuição da fertilidade deste. O presente estudo foi realizado com o objetivo de avaliar os efeitos da utilização combinada de duas curvas de congelamento com dois diluentes comerciais (FR-5® e Botu-Crio®) sobre a criopreservação de sêmen eqüino. Foram analisados 20 ejaculados de dois garanhões. As amostras foram avaliadas por microscopia de contraste de fase e microscopia de epifluorescência, observando-se a motilidade progressiva e total do sêmen pós-descongelamento e a integridade e a funcionalidade da membrana dos espermatozóides. A combinação entre curva automatizada e Botu-Crio® apresentou as maiores médias nas análises de motilidade total e progressiva, após o descongelamento. O diluente Botu-Crio®, isoladamente, preservou também as membranas destes, quando foram realizadas as análises de integridade utilizando teste com diacetato de carboxifluoresceína e iodeto de propídio e funcionalidade de membrana pelo teste hiposmótico.

ABSTRACT

During semen cryopreservation, sperm cells were submitted to several deleterious events leading to membrane damage which result in fertility decrease. This study was designed to compare the effects of two freezing techniques (conventional and automated), and the use of two commercial extenders as cryoprotectants (FR-5® and Botu-Crio®) on total and progressive motility, integrity and functionality of spermatic membranes during the cryopreservation of equine semen. Twenty ejaculates from two stallions were analyzed. The total and progressive motility of fresh and post-thawing semen samples were evaluated by patterns assays. Function of plasmatic membrane was measured by the hipoosmotic swelling test. Integrity of plasmatic membrane was evaluated using carboxifluorescein diacatate and iodidium propide fluorescent probes. There were significant differences between the two freezing techniques and/or between cryoprotectants for all assessed parameters. The combination of Botu-Crio® and automated curves showed better results on total and progressive post-thawing motility. The extender Botu-Crio®, alone, showed to better preserve the membrane integrity and function.