Effect of catalase and thioredoxin addition to sperm incubation medium before in vitro fertilization on sperm capacity to support embryo development

Objective: To determine whether addition of catalase and thioredoxin to sperm incubation medium before IVF improves sperm potential to support embryo development. Design: CD-1 mouse spermatozoa were preincubated without or with catalase or thioredoxin for 1 hour before IVF, and sperm motility parameters, fertilization rate, and embryo development were determined. Setting: A conventional laboratory setting. Intervention(s): Mice were superovulated with pregnant mare serum gonadotropin and hCG. Eggs in cumulus oophorus were collected and used for fertilization with epididymal spermatozoa. Main Outcome Measure(s): Sperm motility parameters, fertilization rate, and embryo development. Result(s): Sperm motility parameters and fertilization rates were not affected by catalase treatment. However, the rates of blastocyst and hatching blastocyst formation when catalase-treated (16 mu g/mL) spermatozoa were used were significantly higher than those observed with nontreated spermatozoa (44% versus 24%, 31% versus 2%, respectively). Addition uf thioredoxin to preincubation media did not affect the percentage of motility and the fertilization rate but increased the rate of blastocyst formation to an extent similar to that triggered by catalase (2.7- and 3.3-fold, respectively). Conclusion(s): These results suggest that H2O2 produced in sperm suspensions before IVF reduces their potential to promote embryo development, that these toxic effects or H2O2 are latent, appearing mainly 3 to 5 days after IVF, and that catalase and thioredoxin are efficient agents to protect sperm potential to support embryo development.