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 t o sperm incubation medium before IVF improves sperm potential to suppo rt embryo development. Design: CD-1 mouse spermatozoa were preincubate d without or with catalase or thioredoxin for 1 hour before IVF, and s perm motility parameters, fertilization rate, and embryo development w ere determined. Setting: A conventional laboratory setting. Interventi on(s): Mice were superovulated with pregnant mare serum gonadotropin a nd hCG. Eggs in cumulus oophorus were collected and used for fertiliza tion with epididymal spermatozoa. Main Outcome Measure(s): Sperm motil ity parameters, fertilization rate, and embryo development. Result(s): Sperm motility parameters and fertilization rates were not affected b y catalase treatment. However, the rates of blastocyst and hatching bl astocyst formation when catalase-treated (16 mu g/mL) spermatozoa were used were significantly higher than those observed with nontreated sp ermatozoa (44% versus 24%, 31% versus 2%, respectively). Addition uf t hioredoxin to preincubation media did not affect the percentage of mot ility 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 H2 O2 produced in sperm suspensions before IVF reduces their potential to promote embryo development, that these toxic effects or H2O2 are late nt, appearing mainly 3 to 5 days after IVF, and that catalase and thio redoxin are efficient agents to protect sperm potential to support emb ryo development.