Pentoxifylline stimulates hyperactivation in human spermatozoa

The effects of pentoxifylline on the movement characteristics of human spermatozoa incubated under capacitating conditions were examined using automated digital image analysis. Washed spermatozoa from cryopreserved and fresh normozoospermic, and fresh oligozoospermic semen were incubated in the presence of pentoxifylline (3.6 mM) for 30 min. In each group, pentoxifylline caused an increase in the average lateral head displacement and curvilinear velocity and a decrease in the linearity of progression. This related to a significant increase in the population of spermatozoa developing hyperactivation. The effect was maximal at between 15 and 75 min incubation. No detrimental effect on sperm vitality was demonstrated. It was shown that hyper activation remained elevated compared with the control after washing pentoxifylline from the suspension. This effect was maintained for 1 h, but became insignificant after 3 h. These data demonstrate that pentoxifylline stimulates the development of hyperactivation in washed human spermatozoa, a phenomenon which may be of value in the treatment of some forms of male factor infertility.