OBJECTIVETo study the mechanism of uPA improving sperm capacitation by investigating the effect of uPA on the mitochondrial function of mouse capacitated-sperm in vitro.

METHODSMitochondrial function of mouse capacitated-spermatozoa was evaluated through the assessment of mitochondrial membrane potential using JC-1 performed by flow cytometer and fluorescent microscope respectively. The experiment and the control groups were designed according to the presence or absence of uPA, each divided into 5 subgroups based on the different time of uPA treatment (or BWW in the control groups) at 0, 5, 15, 30 and 60 min respectively.

RESULTS(1) Compared with that at 0 min, the mean fluorescence intensity of JC-1 within the spermatozoal body and the percentage of orange-red colored spermatozoa in the experiment group were increased significantly at 5 and 15 min respectively after uPA incubation (P < 0.05). (2) The mean fluorescence intensity of JC-1 within the spermatozoal body at 15, 30 and 60 min and the percentage of orange-red colored spermatozoa at 5 and 15 min in the group were significantly higher than those in the control group (P < 0.05).

CONCLUSIONuPA could increase the mitochondrial membrane potential of mouse capacitated-spermatozoa in vitro, and maintain it at a high level for a certain period of time. By enhancing sperm mitochondrial function, uPA may provide sufficient energy for capacitated-spermatozoa to increase their motility and change their motor pattern, which might be one of the therapeutic mechanisms of uPA on male infertility.