Effects of polyamines upon capacitation and fertilization in the guinea pig.

The effects of polyamines upon the ability of guinea pig spermatozoa to undergo the acrosome reaction and upon sperm-egg fusion were investigated. All of the polyamines (polyarginines and compound 48/80) stimulated the occurrence of the acrosome reaction, although differences in the duration of the preincubation period required were noted. The stimulatory effect of the polyarginines could not be reversed by washing, while that of 48/80 was abolished by its removal prior to induction of the acrosome reaction. Polyarginine-treated spermatozoa were fully capable of fertilizing intact guinea pig eggs. In contrast, 48/80 completely blocked sperm-egg fusion at only 5-10 micrograms/ml. This inhibition was reversible by washing either treated gamete. The ability of polyamines which may also be present at the time and site of fertilization, in vivo, to inhibit or stimulate gamete functions or interactions is discussed.