Are the mechanisms of nigral cells neurodegeneration in typical and atypical parkinsonism different - MRI and Mössbauer spectroscopy studies (P1.176)

Introduction: Parkinson’s disease (PD) and atypical parkinsonism e.g. progressive supranuclear palsy (PSP) share some similar clinical features. Their motor symptoms are due to death of nervous cells in substantia nigra (SN). As the mechanism of the neurodegeneration in both may be related to the iron mediated oxidative stress injury and as the role of iron may be eventually assessed in the patients by magnetic resonance imaging (MRI) and in the post mortem tissue by Mossbauer spectroscopy (MS), we decided to compare the results of MRI with those obtained with the use of MS for the concentration of iron. Material and methods: T1 and T2 relaxation times obtained from SN were determined by MRI from 46 PD patients, 6 PSP and 18 control subjects. MS was performed on 17 PD SN samples, 10 PSP SN samples and 29 controls. Results: T1 relaxation time from SN was 663±23 ms in PD, 580±12 ms in PSP and 717±4 ms in controls, T2 was 47.2±0.4 ms in PD, 57.3±1.7 ms in PSP and 51.6±0.6 ms in controls. Iron concentrations as assessed by MS in SN samples were 177±18 ng/mg wet tissue for PD, 301±26 ng/mg wet tissue for PSP and 177±14 ng/mg wet tissue for control. Conclusions: In PSP there is a significant increase of the concentration of iron in SN compared to control which is not detected in PD. This increase of iron is reflected by the significant shortening of T1 relaxation time in PSP. This finding is not paralleled by the change of T2 relaxation time which is the shortest in PD and the longest in control. It seems therefore that the changes in relaxation times depend not only on the concentration of iron. Our results suggest that the neurodegeneration in both diseases may be due to different mechanisms. Disclosure: Dr. Friedman has nothing to disclose. Dr. Kulinski has nothing to disclose. Dr. Galazka-Friedman has nothing to disclose.