RESUMO
<p><b>OBJECTIVE</b>To compare the phosphorylation and protein expression of extracellular-signal regulated protein kinase (ERK) and P38 mitogen activated protein kinase (P38 MAPK) in the ejaculated spermatozoa of healthy volunteers and asthenospermia males, and to explore the correlation of ERK and P38 MAPK with human sperm motility.</p><p><b>METHODS</b>Semen samples were collected from 20 healthy volunteers (sperm concentration > or = 20 x 10(6)/ml, grade a sperm > or = 25% or grade a + b sperm > or = 50%) and 20 infertile males with asthenospermia (sperm concentration > or = 20 x 10(6)/ml, grade a sperm < 25% and grade a + b sperm < or = 40%) and classified as a control and an asthenospermia group. Total protein in spermatozoa was extracted from all the subjects, and Western blotting was used to detect phosphorylation and protein expression levels of ERK and P38 MAPK.</p><p><b>RESULTS</b>Compared with the control group, the protein expression levels of ERK and P38 MAPK and the phosphorylation level of P38 MAPK were significantly increased in the asthenospermia group (P < 0.05), but there were no statistically significant differences in the phosphorylation level of ERK between the two groups (P > 0.05).</p><p><b>CONCLUSION</b>The up-regulated protein expressions of ERK and P38MAPK and increased phosphorylation level of P38 MAPK in human sperm may be involved in the pathogenesis of asthenospermia.</p>