EFFECT OF THE ACTIVATION AND INHIBITION OF THE PLASMINOGEN/PLASMIN SYSTEM DURING IN VITRO MATURATION OF BOVINE OOCYTES: A BIOLOGICAL AND SPECTROSCOPIC APPROACH

RIZO, GABRIELA; JIMÉNEZ, EMANUEL; GARCÍA, E. VANESA; GARCÍA, DANIELA; BARRERA ANTONIO DANIEL; ÁLVAREZ, ROSA MARÍA SUSANA; ROLDÁN OLARTE, EUGENIA MARIELA

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

Sociedades de Biociencias de Argentina

The Plasminogen (Plg)/Plasmin (Plm) proteolytic system plays acrucial role during the initial steps of mammalian reproduction. Plgmust interact with its activators to become Plm, involved in a broadspectrum of proteolytic processes. Due that Plg is in the zona pellucida(ZP) and plasma membrane of bovine oocytes, this study examinesthe effect of the exogenous activation or inhibition of Plg/Plmduring the in vitro maturation (IVM) of cumulus oocytes complexes(COCs). Three groups were studied: i) control (COCs), ii) with 3.5IU/mL streptokinase, an exogenous Plg activator (COCs/SK) iii) with10 mM ε-aminocaproic acid, a specific inhibitor of Plm proteolyticactivity (COCs/ε-ACA). After 22 h of IVM, oocytes were processedand evaluated. It was observed that in COCs/SK the percentages ofmetaphasic II (MII) oocytes were not modified, while in COCs/ε-ACAa decrease in the number of MII oocytes was evidenced. Cumulusexpansion after IVM was employed to evaluate the effect of Plmactivity. By microphotographs it was observed that ε-ACA inhibitsthe cumulus expansion respect to the control and SK. Modificationsin the ZP were evaluated by measuring the time of digestion of ZP(dtZP) with pronase. No significant differences in the dtZP betweenCOCs and COCs/SK were observed. However, in COCs/ε-ACAthe resistance of ZP to enzymatic digestion was increased. Physicochemicalproperties of the ZP were also studied by Raman microspectroscopy.Spectral differences were related to specific structuralchanges in glycoproteins upon IVM with ε-ACA. The intensitydecrease in the sialic acid band agrees with previous results regardingthe in vitro fertilization: the biological effect of ε-ACA would beinterpreted like a reduced interaction between the ZP oocyte and thesperm. Considering all these results, the inhibition of Plm activity byɛ-ACA produces a negative effect in the in vitro matured oocytes. Onthe contrary, negligible effects were observed with SK.