Participation of lactate dehydrogenase in capacitation and acrosome reaction of fresh and cryopreserved, with or without α-tocopherol, boar sperm

The aim of this work was to study the participation of lactate dehydrogenase (LDH) enzyme in capacitation and acrosome reaction in porcine sperm by determining its enzymatic activity and the effect of its inhibition on these processes. Semen samples, from four crossbred boars (Pietrain x Yorkshire) of proven fertility, 1-1.5 year of age, were analysed. The enzymatic activity of LDH was determined spectrophotometrically in extracts from fresh and cryopreserved, with and without α-tocopherol, porcine sperm. Besides, sperm suspensions were incubated in the presence of bicarbonate (40 mM), a well-known capacitation inducer, follicular fluid (30%), as an acrosome reaction inducer, and different concentrations of sodium oxamate, a specific inhibitor of the enzyme. The activity of LDH in enzymatic extracts of fresh, cryopreserved without or cryopreserved with α-tocopherol porcine sperm were 3.85±0.27, 0.7±0.04 and 1.73±0.23 U/1010 sperm, respectively (p<0.05). The addition of sodium oxamate inhibited capacitation or acrosome reaction in fresh and cryopreserved with or without α-tocopherol porcine sperm, affecting (at different concentrations) motility and sperm viability (P