The Correlation Between Mitogen-activated Protein Kinase Signal Transduction Pathway And Human Sperm Motility

PartⅠCorrelation of ERK and P38MAPK expression level with human sperm motilityObjective: The phosphorylation and protein expression level of extracellular-signal regulated protein kinase(ERK)and P38 mitogen activated protein kinase (P38 MAPK) in ejaculated spermatozoa of healthy volunteers and infertile males with asthenospermia were investigated in order to explore the correlation of ERK and P38 MAPK with human sperm motility and concentration. Methods: After standard semen analysis, 20 healthy volunteers (sperm concentration≥20×106 /ml, a≥25% or a + b≥50% ) and 20 infertile males with asthenospermia (sperm concentration≥20×106 /ml, a<25% and a+b≤40%) were classified as control group and asthenospermia group. Total protein in spermatozoa was extracted from all subjects, and western blotting was used to detect phosphorylation and protein expression level of ERK and P38 MAPK. Results: Compared with control group, the phosphorylation level of ERK and P38 MAPK were significantly increased in asthenospermia group(P<0.05), but there were no correlations between the sperm concentration and the level of ERK and P38MAPK in both groups. Conclusions: The down-regulation of ERK and up-regulation P38MAPK may take part in pathogenesis of asthenospermia; there may be no correlation between the level of ERK and P38 MAPK and sperm generation. PartⅡEffect of MAPK inhibitor on human sperm motility and its mechanismObjective: To investigate the effect of PD98059(inhibitor of ERK) and SB203580 (inhibitor of P38)on human sperm motility and its mechanism. Methods: The semens of 15 healthy volunteers (sperm density≥20×106 /ml, a≥25% or a + b≥50% ) and 15 infertile males with asthenospermia (sperm density≥20×106 /ml, a<25% and a+b≤40%) were collected,and the isolated spermatozoa of healthy volunteers and infertile males with asthenospermia were incubated with different dosage of PD98059 and SB203580, respectively. At different action times, sperm motility were detected under Markler counters,meanwhile,the total protein in spermatozoa was extracted from all subjects for detecting the phosphorylation and protein expression level of ERK and P38MAPK by the method of western blotting. Results: After incubation with 80μmol/LPD98059, sperm motility in healthy volunteers decreased significantly and reached its maximum at 40min incubation, however, sperm motility in asthenospermia increased significantly after incubation with 60μmol/LSB203580 and reached its maximum at 10min incubation. The phosphorylation level of ERK and p38MAPK were both decreased under the action of inhibitors. Conclusions: PD98059 and SB203580 can regulate sperm motility by inhibit ERK and P38MAPK signal transduction pathway, MAPK signal transduction pathway may play an important role in regulating sperm motility, which might be a new target for treating asthenospermia. PartⅢThe effect of PKC on human sperm motility and its mechanismObjective: To explore the effect of PKC on sperm motility and its mechanism. Methods: After standard semen analysis, 30 healthy volunteers (sperm density≥20×106 /ml, a≥25% or a + b≥50% ) and 20 infertile males with asthenospermia (sperm density≥20×106 /ml, a<25% and a+b≤40%) were classified as control group and asthenospermia group,and the PKCβⅠof spermatozoa in two groups were measured by flow cytometry(FCM) . Meanwhile,spermatozoa in control group were treated by PMA (PKC activator) and GF109203X(PKC inhibitor), then the phosphorylation and protein expression level of ERK were detected by western blotting. Results: The results showed that the level of PKCβⅠin asthenospermia group decreased significantly compared with control group. After incubation with PMA, the phosphorylation level of ERK in spermatozoa increased significantly, meanwhile, which decreased significantly after incubation with GF109203X. Conclusions: PKC may involve in the regulation of sperm motility through MAPK signal transduction pathway,and the level of PKC in spermatozoa may play an important role in pathogenesis of asthenospermia.