Influência das técnicas de seleção Swim-up e gradiente de densidade (Percoll ® e CapriPure ® ) na viabilidade espermática de amostras criopreservadas de sêmen caprino

Abstract

Sperm processing methods are routinely applied on the in vitro fertilization (IVF) systems for various species with the objective to remove seminal plasma/crioprotectant and to increase sperm quality. Aiming at study the sperm viability after use of the Swim-up or density gradient methods (Percoll® and CapriPure®) in frozen-thawed goat semen samples for use in assisted reproduction, six Boer goat semen samples were collected. Following, the samples were evaluated for concentration, progressive motility and morphology, diluted, packaged in straws (0.25 mL), frozen using machine and stored in liquid nitrogen. After thawing (37 oC for 30 s), sperm of all six goat were mixed-up making a pool and then were evaluated for progressive motility, membrane integrity (PI/DCF), acrossomal integrity (FITC/PNA) and mitochondrial membrane potential (JC-1). After that, the pool was split into two aliquots for the accomplishment of the sperm selection using the methods Swim-up and Percoll® (Experiment 1) and centrifugation in Percoll® and CapriPure® density gradient (Experiment 2). After use of each method of selection, the analyses was proceeded it from progressive motility, membrane integrity, acrossomal integrity and of mitochondrial integrity. Exp. 1 evidenced lower percentage of progressive motility spermatozoa (P<0.05) with intact plasma membrane (P<0.01) after use of Swim-up method, when compared with samples submitted to sperm preparation with Percoll®. In the Exp. 2, Percoll® gradient determined reduction (P<0.05) in percentage of acrosome intact spermatozoa when compared with percentage of the sample immediately after thawing, not having significant difference (P>0.05) if comparing submitted samples with the CapriPure® gradient. There were significant differences in the percentage of spermatozoa with high mitochondrial membrane potential inthe samples of semen submitted the selection using Percoll® (P<0.05) and CapriPure® (P<0.01), density gradients, when compared with the values of samples evaluated immediately after thawing. However, there were no significant difference (P<0.05) in the high mitochondrial membrane potential values between Percoll® and CapriPure® density gradients. On the basis the results of mobile spermatozoa and with the intact plasma membrane, are possible to conclude that to select viable sperm of frozen goat semen samples should use density gradient methods and CapriPure® is a good alternative to Percoll®.