Breed and seasonal variation of plasminogen activator activity and plasminogen activator inhibition in spermatozoa and seminal plasma of the ram in correlation with testosterone in the blood.

Plasminogen activator activity (PAA) and plasminogen activator inhibition (PAI), against t-PA (t-PAI) or u-PA (u-PAI), in spermatozoa and seminal plasma as well as testosterone in the blood of Friesland, Chios, and Karagouniki rams all showed a seasonal variation with the highest values during the corresponding breeding season of the ewes (Autumn-Winter). The seasonal variation of PAA and PAI in spermatozoa or seminal plasma as well as blood testosterone was different among the three breeds studied. Increased spermatozoal PAA was observed in November and May in Friesland rams, in October and November in Chios rams, and in October in Karagouniki rams. Spermatozoal t-PAI was increased in December and June in Friesland rams, in November and December in Chios rams, and in November in Karagouniki rams. Spermatozoal u-PAI was increased in December in Friesland rams, in October and December in Chios rams, and in November and December in Karagouniki rams. Plasminogen activator activity and PAI in seminal plasma also showed similar seasonal variations. Plasminogen activator activity and PAI in spermatozoa and seminal plasma showed a positive correlation with blood testosterone. The results of the present study support our previous findings on the possible role of spermatozoal PAA and PAI in the fertilizing ability of spermatozoa.