Effects of the purified IGF-I complex on the capacitation and acrosome reaction of rabbit spermatozoa.

A protein complex containing IGF-I, purified from rabbit seminal plasma, was used to investigate its effects on the capacitation and acrosome reaction of rabbit spermatozoa. Uncapacitated sperm (Pattern F), capacitated sperm (Pattern B), and acrosome-reacted sperm (Pattern AR) were determined by CTC staining, and the results were validated by PSA-staining. The addition of the IGF-I complex to the capacitative medium directed the spermatozoa to spontaneous acrosome reaction. On the other hand, IGF-I complex, added to capacitated spermatozoa, acted as inducer of the acrosome reaction. Results of IVF experiments showed high rates of fertilization with capacitated spermatozoa, acrosome-reacted by either A23187 or IGF I complex, whereas significantly lower rates were obtained with spermatozoa capacitated in the presence of IGF-I complex. Copyright 2001 Wiley-Liss, Inc.