ELEVATED 5-S-CYSTEINYLDOPAMINE HOMOVANILLIC ACID RATIO AND REDUCED HOMOVANILLIC-ACID IN CEREBROSPINAL-FLUID - POSSIBLE MARKERS FOR AND POTENTIAL INSIGHTS INTO THE PATHOETIOLOGY OF PARKINSONS-DISEASE/

High-performance liquid chromatography with electrochemical detection has been employed to analyze ultrafiltrates of cerebrospinal fluid of Parkinson's Disease (PD) patients and age-matched controls for the dop amine (DA) metabolites homovanillic acid (HVA) and 5-S-cysteinyldopami ne (5-S-CyS-DA). The mean level of HVA in the CSF of PD patients, meas ured 5 days after withdrawal from L-DOPA therapy, was significantly lo wer than that measured in controls. By contrast, mean levels of 5-S-Cy S-DA were not significantly different in the CSF of PD patients taking L-DOPA (PD-LT patients) the same patients 5 days after discontinuing this drug (PD-LW patients) or controls. However, the mean 5-S-CyS-DA/H VA concentration ratio was significantly (p < 0.05) higher in the CSF of PD-LW patients compared to controls. Although the PD patient popula tion employed in this study had been diagnosed with the disease severa l years previously and had been treated with L-DOPA for prolonged peri ods of time the results of this study suggest that low CSF levels of H VA and a high 5-S-CyS-DA/HVA ratio together might represent useful mar kers for early diagnosis of PD. The high 5-S-CyS-DA/HVA ratio observed in the CSF of PD-LW patients also provides support for the hypothesis that the translocation of glutathione or L-cysteine into neuromelanin -pigmented dopaminergic cell bodies in the substantia nigra might repr esent an early event in the pathogenesis of PD.