Increased in vitro binding and fertilizing ability of mouse sperm exposed to a synthetic peptide

We report use of an in vitro assay (Barbato et at., 1998: Biol Reprod 58:68 6-699) to assess binding ability of cauda epididymal mouse sperm to a surro gate zona pellucida and effect of a synthetic peptide (Amann et al., 1999: J Androl 20: 42-46) on fertilization ability in in vitro fertilization (IVF ) tests. Sperm from C57B1/6, CD1, and CF1 mice (4 replicates each) were eva luated for binding ability after exposure to 0 (control) and 80-1280 pM pep tide. For control sperm, endogenous binding was C57Bl/ 6<CD1= CF1 (P<0.05, 1-way ANOVA). Across all three strains, exposure to >320 pM peptide increas ed relative binding of sperm (P<0.05; 2-way general linear model; GLM). Str ains differed both in basal binding ability and in response to synthetic pe ptide. To determine if IVF rate increased after exposure of sperm to peptid e, ova from B6C3 mice (four replicate pools) were collected after eCG and h CG stimulation. Cumulus-oocyte complexes (COC; 8-15 ova in each of 3-6 drop s/treatment) were incubated with hyperactivated C57B1/6 sperm at <similar t o>1500 sperm per ovum. Data for incubations were corrected for false-positi ve classification to yield a better estimate of true cleavage rate, and the n related to results observed with a tenfold greater sperm concentration. R elative cleavage rates were 0 peptide (0.48); 420 pM (0.78, P<0.05); and 84 0 pM (0.90, P<0.01; GLM and Tukey tests). IVF rate was increased by exposur e of mouse sperm to peptide at concentrations effective in the in vitro ass ay, and use of peptide allowed use of 1/10 as many sperm. (C) 2000 Wiley-Li ss, Inc.