Efeito de diferentes concentrações de plasma seminal na criopreservação de sêmen eqüino

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

One of the major limiting factors of equine frozen semen is the low fertility obtained. During freezing process spermatozoa undergoes a series of damages such as changes in membrane components, premature capacitation, chromatin damages and oxidative stress. Sperm cells are very susceptible to oxidative stress due to high concentration of polyunsaturated fatty acids in the membrane and low concentration of antioxidant enzymes in their cytoplasm. It has been shown that there is a correlation between low antioxidant capacity of semen and fertility of the animal and it may be due to seminal plasma removal during cooling or freezing process. Recent studies have shown a beneficial effect of seminal plasma in the storage of equine spermatozoa either by cooling or by cryopreservation. The objective of the present study was to evaluate the effect of different concentrations of seminal plasma in the protection against oxidative stress during cryopresenvation of equine spermatozoa, and to verify that effect in cell viability. In this experiment, four stallions were used and four ejaculates were obtained from each animal. After collection, seminal plasma was removed and spermatozoa ressuspended in extender with seminal plasma in different concentrations 0% (T1), 5% (T2), 25% (T3) e 50% (T4). Motility, vigor, morphology, membrane, acrossome and DNA integrity, lipid peroxidation and protein oxidation were analyzed after freezing and xi thawing. Seminal plasma did not affect (p>0,05) sperm morphology and DNA integrity. Frozen spermatozoa with 5% (T2) of seminal plasma were similar (p>0,05) to control (T1) in all variables studied, except in lipid peroxidation analysis, in which the results were higher (p<0,05) in control in comparison with the other treatments. T4 presented lower (p<0,05) motility, vigor, membrane and acrossome intact cells percentage. Effect of seminal plasma protection against protein oxidation was not observed (p>0,05). In conclusion, seminal plasma presented antioxidant effect during cryopreservation, however, this effect does not protect the spermatozoa viability from other cryopreservation damages and it may even exacerbate theses damages in concentrations of 25% or higher.

ASSUNTO(S)

eqüino estresse oxidativo cryopreservation viabilidade espermática. equine sperm viability plasma seminal ciencias agrarias criopreservação oxidative stress seminal plasma

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