Comparison and evaluation of capacitation and acrosomal reaction in freeze-thawed human ejaculated spermatozoa treated with L-carnitine and pentoxifylline

Cryopreservation is used to preserve the spermatozoa; however, it leads to a reduction in sperm quality. L-carnitine (LC) influences sperm motility and preserves the sperm membrane and DNA integrity. The objectives of this study were to evaluate the protective effects of LC on the membrane integrity of normal human spermatozoa and compare it with pentoxifylline (PT) during cryopreservation. Thirty normal semen samples, prepared by swim-up procedure, were divided into three aliquots: a control without any treatment and two experimental aliquots that were incubated in PT or LC for 30min. All aliquots were cryopreserved and thawed after 48hr. To evaluate the percentages of intact, acrosomal-reacted and capacitated spermatozoa, lectin histochemistry and flow cytometry were performed by wheat germ agglutinin, peanut agglutinin and Con A. Statistical analyses were performed using ANOVA. LC supplementation elevated the percentage of noncapacitated spermatozoa compared with control and PT-treated samples and the percentages of acrosomal intact spermatozoa compared with PT-treated samples. PT pre-treatment improved the motility but not membrane integrity. LC supplementation reduced the percentages of acrosomal-reacted spermatozoa compared with the control and PT-treated samples. Although LC did not improve motility, it protected the plasma membrane and acrosomal integrity. Therefore, LC may be the superior choice compared to PT for maintaining the sperm integrity.