Effects Of UPA And UPAR On Bovine Oocyte Nuclear Maturation In Vitro

In order to investigate the possible role of urokinase type plasminogen activator(uPA)and its specific receptor uPAR on bovine oocyte nuclear maturation,the protein localization and expression of uPA and uPAR in immature bovine cumulus-oocyte complexes(COCs)were investigated by immunohistochemistry,the effects of uPA on bovine oocyte nuclear maturation after 3 hours,6 hours and 12 hours of maturation in vitro were studied by using and the orcein staining technique,and the possible regulatory effect of uPA,Amiloride(uPA activity inhibitor)and uPAR antibody on cAMP level in bovine COCs and oocytes after 6 hours of maturation in vitro was detected by competitive enzyme-linked immuno sorbent assay.The results show that:(1)In bovine COCs,uPA is expressed only on the cumulus layer,and uPAR is expressed on both cumulus cells and oocytes;(2)Compared with the control,uPA could block oocyte nuclear maturation significantly after 3,6,and 12 h of treatment(P<0.05).(3)After 6h of maturation in vitro,c AMP level in bovine COCs and oocytes is up-regulated after treatment with uPA and down-regulated when u PA activity inhibited with amiloride or uPAR pathway blocked with its antibody.In summary,the present study indicates that uPA could promote cAMP production in bovine COCs and oocytes during in vitro maturation,thus delaying or arresting oocyte nuclear maturation;the increasing cAMP levels in oocytes may originate from its cumulus layer;and whether uPA can stimulate bovine oocytes to produce cAMP itself needs to be further validated.