Figure 3

The effect of parkin protein loss on striatal dopamine metabolism. (A,B) Mitochondria isolated from the striata of parkin knockout (PKO) and wild type (WT) rats, monitoring the rate of H₂O₂ production over 30 min (Fig. 3A, graph on the right). (A) In the PKO rats, striatal activity of MAO-A and MAO-B was significantly reduced (−27% and −46%, respectively, p < 0.05, Student’s t-test, n = 6) compared to the WT controls. MAO-B activity, measured with p-tyramine as a substrate for both isoforms, was linear over measured 30 min time period. (B) SDS-PAGE and western blotting analysis revealed no difference in the levels of MAO-B protein (n = 6) . (C) Lack of immunoreactivity for proteins modified by DA quinones in the striatal lysates of WT and PKO rats; DA quinone-modified bovine serum albumin serves as a positive control. The data are expresses as mean ± SEM. *p < 0.05. Abbreviations: BSA, bovine serum albumin; DA, dopamine; DAQ, dopamine quinone; MAO, monoamine oxidase.