Caffeine increased progressive motility of human spermatozoa in normozoospermic and asthenozoospermic semen samples and enhanced activity of seminal creatine kinase.

Even though the effect of caffeine on humans' health has been revealed in various research studies, its effect on semen quality has yet to be well explained. Here, we measured the effect of caffeine at 1, 5, 10 and 20 mM on motility of human spermatozoa in normozoospermic and asthenozoospermic semen samples, level of seminal nitric oxide, chelation of seminal calcium ions and activity of seminal creatine kinase. Fifty-one normozoospermic and ten asthenozoospermic semen samples were recruited in this study. Sperm motility was evaluated by Makler counter, and seminal nitric oxide, seminal-free calcium and activity of seminal creatine kinase were measured spectrophotometrically. Caffeine at 10 mM significantly (p < .05) increased progressive motility of spermatozoa in both tested groups. Also, caffeine significantly increased (p < .05) activity of creatine kinase and insignificantly (p > .05) altered nitric oxide and free calcium levels in seminal plasma. In conclusion, progressive motility of human spermatozoa was found to be higher in the presence of caffeine at 10 mM in normozoospermic and asthenozoospermic semen samples; this increase, albeit partially, could be due to increased activity of seminal creatine kinase, but not to increased production of nitric oxide or chelation of free calcium ions.