Effects of gamma-amino butyric acid, progesterone and oestradiol on human spermatozoa acrosome reaction

Summary The acrosome reaction (AR) is influenced by the action of several molecules such as GABA, P 4 , and E 2 . Objective: to determine the interaction between GABA / E 2 , and GABA / P 4 in the AR. Methods: Washed human spermatozoa capacitated for 2 h were incubated in the following conditions: BWW medium alone (control) or BWW plus: P 4, E 2, GABA, GABA+ P 4 or GABA+ E 2. The % of AR was determined by FITC-PSA. Results: Spermatozoa incubated with GABA or P 4 showed higher % of AR; additionally, separate and simultaneous P 4 and GABA incubations showed no significant difference in the % of AR. GABA plus E 2 incubation showed lower % of AR than GABA only incubated spermatozoa. Conclusions: The AR would be modulated by inductors such as GABA and P 4 ; there is not synergistic interaction between these molecules on AR induction; besides, there are inhibitory hormones such as E 2 , whose effect prevails in a combined GABA/E 2 incubation. The localisation of these compounds would determine timely AR occurrence.