SUMMARYSodium nitroprusside is a nitric oxide donor involved in the regulation of the motility, hyperactivation, capacitation, and acrosome reaction (AR) of spermatozoa. However, the molecular mechanism underlying this regulation has not yet been elucidated. Therefore, this study was designed to evaluate the molecular basis for the effects of sodium nitroprusside on different processes in spermatozoa and its consequences on subsequent oocyte fertilization and embryo development. In this in vitro study, mouse spermatozoa were incubated with various concentrations of sodium nitroprusside (1, 10, and 100 lM) for 90 min. Our results showed that sodium nitroprusside inhibited sperm motility and motion kinematics in a dose-dependent manner by significantly enhancing intracellular iron and reactive oxygen species (ROS), and decreasing Ca 2+ , and adenosine triphosphate levels in spermatozoa. Moreover, short-term exposure of spermatozoa to sodium nitroprusside increased the tyrosine phosphorylation of sperm proteins involved in PKA-dependent regulation of intracellular calcium levels, which induced a robust AR. Finally, sodium nitroprusside significantly decreased the rates of fertilization and blastocyst formation during embryo development. Based on these results, we propose that sodium nitroprusside increases ROS production and precocious AR may alter overall sperm physiology, leading to poor fertilization and compromised embryonic development.

SUMMARYConventional semen analysis offers basic information on infertility; however, its clinical value in predicting fertility status is unclear. To establish an accurate diagnosis of male fertility, semen analysis under capacitation condition is necessary because only capacitated spermatozoa are capable of fertilizing oocytes. The objective of this study was to verify male fertility based on conventional semen analysis before and after capacitation, including the assessment of motility (%), motion kinematics, and capacitation status of spermatozoa. A computer-assisted sperm analysis system and chlortetracycline staining were applied to evaluate the motility parameters and capacitation status, respectively. To enable efficacy of the two methods for predicting fertility, correlation analysis was performed with the historic litter size. Our results showed that sperm motility (%), motion kinematics, and their variations before and after capacitation represented a statistical non-significant correlation with litter size. Litter size showed significant correlation with acrosome reaction (AR) after capacitation (r = 0.375), as well as differences (D) in AR (r = 0.333) and capacitated (B) pattern (r = À0.447) before and after capacitation. The overall accuracy of the assay for predicting litter sizes using the AR and differences (D) in the AR and B pattern was 70%. On the basis of these results, we propose that capacitation status of spermatozoa is a more reliable indicator for evaluating male fertility status compared to motility parameters. Therefore, we suggest that analysis of capacitation status in company with conventional semen analysis may accept to evaluate more accurate diagnosis or prognosis of male fertility.

SUMMARYThe actin-related protein 2/3 (Arp2/3) complex is critical for regulation of actin polymerization, which is associated with sperm motility and capacitation status. However, the function of the Arp2/3 complex in male fertility has not yet been fully elucidated. Therefore, this study was designed to investigate the role of the Arp2/3 complex in different processes in spermatozoa and its consequences on fertilization and early embryonic development. In this in vitro study, mouse spermatozoa were incubated with different concentrations (10, 100, and 500 lM) of CK-636, an Arp2/3 complex antagonist. Our results demonstrated that inhibition of the Arp2/ 3 complex by high concentrations (100 and 500 lM) of CK-636 induced hyper-activated motility and acrosomal reaction, whereas intracellular calcium and tyrosine phosphorylation levels in spermatozoa were inhibited. Moreover, exposure of spermatozoa to the highest concentration of CK-636 reduced fertilization and embryo development. Interestingly, fertilization was significantly increased after treatment with 100 lM CK-636, whereas embryonic development was significantly decreased. Therefore, we conclude that the Arp2/3 complex plays a decisive role in regulation of sperm function and male fertility via actin polymerization. We anticipate that the Arp2/3 complex may have clinical application as marker for male fertility and male contraceptive targeting.