OBJECTIVETo study the effects of the urokinase-type plasminogen activator (uPA) on the chemotactic responses of spermatozoa in vitro, and to explore the possible action mechanisms of uPA for male infertility.

METHODSThe chemotactic responses of spermatozoa were measured using spermatozoal accumulation in the capillary. According to the gradient directions of chemoattractant concentrations in the capillary, the recruits were divided into three groups: Group A (the ascending gradient of chemoattractant), Group B (the descending gradient of chemoattractant) and Group C (control). The chemoattractant in the capillary and the treating fluid in spermatozoal wells of Group A were uPA of different concentrations and Hamś F-10, respectively, while those of Group B were just opposite to Group A, and those of Group C were both Hamś F-10. Then the sperm densities in different capillaries were measured at different points of time.

RESULTS(1) Spermatozoa moved chemotactically following the concentrations of uPA. The accumulative action of spermatozoa in Group A was obviously stronger than in Groups B and C (P < 0.05 ). (2) The effects of 20 IU/ml uPA on the chemotactic responses of spermatozoa were most significant. (3) The sperm densities in the three groups increased with time, significantly different at 20 min and 30 min (P < 0.05). (4) uPA could increase sperm motility and promote sperm movement, as well as induce sperm chemotactic responses.

CONCLUSIONuPA could induce sperm chemotactic responses and increase sperm motility, which is presumably one of the action mechanisms of uPA on male infertility.