Expressions of sperm-specific genes in carnitine-cultured testis sperm of obstructive azoospermia patients

OBJECTIVE: To investigate the effects of carnitine on human sperm motility and its potential role in the treatment of male infertility diseases. METHODS: We obtained sperm by testis puncture from obstructive azoospermia patients and cultured them in vitro with normal culture solution (the control group) and the solution with L-carnitine at the concentration of 100 and 250 mmol/L, respectively. We observed the changes in sperm motility and morphology before and after the treatment, detected the expressions of the germ-specific genes, Vasa, Dazl, Acr, Prm1 and ATPase 6.0 by RT-PCR, and investigated the relationship between L-carnitine and the genes associated with sperm development and maturation. RESULTS: After 24 -72 hours of treatment, the percentage of motile sperm was significantly higher in the 100 mmol/L L-carnitine group than in the control and 250 mmol/L L-carnitine groups (P < 0.01); the number of forward moving sperm was obviously increased and sperm morphology remained normal in the 100 mmol/L L-carnitine group. RT-PCR showed that L-carnitine increased the expressions of Acr, Prm1, Dazl and ATPase 6. 0 at the concentration of 100 mmol/L, and decreased the expressions of Dazl, Acr and Prm1 at 250 mmol/L. CONCLUSION: L-carnitine at a proper concentration may improve the motility of incubated testicular sperm by upregulating the expressions of some sperm-specific genes, which helps sperm selection for intracytoplasmic sperm injection. However, a higher concentration of L-carnitine may reduce the expressions of these genes, probably due to its increased toxicity.