Role of Pt and SRO electrodes in polarization fatigue of PLZT film ferroelectric capacitors is studied. We show that asymmetrical Pt/SRO/PLZT/Pt structure exhibits unusual dependence of the endurance of switching polarization on the driving ac electric field amplitude. Specifically, for high ac electric field amplitude it shows a good switching endurance similar to SRO/PLZT/SRO capacitors, whereas for amplitude lower than 80 kV/cm a pronounced polarization fatigue similar to that of conventional Pt/PLZT/Pt capacitors is observed. Based on the analysis of these results we conclude that the polarization switching endurance under high-amplitude fatiguing cycling is governed only by the top SRO-interface which is not subjected to degradation, whereas the degradation properties of the bottom Pt-interface do not play any role.