The binding of recombinant human relaxin to human spermatozoa

Abstract

Porcine relaxin has been reported to stimulate various human sperm functions. In this paper we report that human recombinant relaxin binds to human sperm with a high affinity (Kd = 6.5 X 10⁻¹⁰). The bound ¹²⁵I- relaxin was not displaced by insulin, or human chorionic gonadotropin, however, it was displaced by unlabeled relaxin. In sperm function studies, recombinant human relaxin stimulated sperm motility, zona-free hamster egg penetration, and the acrosome reaction.