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INHIBITION OF IN VITRO FERTILIZATION IN THE HAMSTER BY ANTIBODIES RAISED AGAINST THE RAT SPERM PROTEIN SP22
Citation:
Jeffay, S C., S P. Darney, K L. Bobseine, J. E. WELCH, AND G. R. KLINEFELTER. INHIBITION OF IN VITRO FERTILIZATION IN THE HAMSTER BY ANTIBODIES RAISED AGAINST THE RAT SPERM PROTEIN SP22. Presented at International Congress of Andrology, Montreal, CANADA, June 15 - 19, 2001.
Description:
INHIBITION OF IN VITRO FERTILIZATION IN THE HAMSTER BY ANTIBODIES RAISED AGAINST THE RAT SPERM PROTEIN SP22. SC Jeffay*, SD Perreault, KL Bobseine*, JE Welch*, GR Klinefelter, US EPA, Research Triangle Park, NC.
SP22, a rat sperm membrane protein that is highly-correlated with fertility, is being investigated as a biomarker of sperm function. Antibodies raised against SP22 have been shown to inhibit in vitro fertilization (IVF) in the rat, and localize to the equatorial segment of rat and hamster spermatozoa, suggesting a role for SP22 in fertilization. Herein, we examine whether SP22 antibodies inhibit IVF in the hamster. Affinity-purified, polyclonal sheep anti-recombinant SP22 (rSP22) was added to hamster sperm during the final hour of a 3 hour capacitating incubation. Sperm were then used to inseminate zona-intact (ZI) and zona-free (ZF) hamster oocytes. rSP22 Ig inhibited fertilization of ZI oocytes in a concentration-dependent manner, without apparent effect on sperm motility. Mean fertilization for 3 experiments was 95, 64*, 18*, and 6*% for undiluted, 1:50, 1:10, and 1:5 Ig dilutions, respectively (* denotes p < 0.05). These results suggest that SP22 may function in sperm binding to and/or penetration of the zona pellucida. Mean fertilization of ZF oocytes was 98, 100, 92, and 53*% across dilutions, and polyspermy was 5.6, 5.6, 3.0, and 0.8* sperm/oocyte across dilutions. Thus, SP22 might also play a role in sperm-oolemma fusion; or this may be a non-specific effect of increased Ig. Taken together, these findings suggest that antibodies to SP22 can be used to evaluate SP22 expression in other species, supporting the concept that SP22 might serve as a useful biomarker of fertility in toxicology, or as a target in contraceptive studies, in animal models and humans.