2-[I-123]-IODOLISURIDE SPET VISUALIZES DOPAMINERGIC LOSS IN DE-NOVO PARKINSONIAN-PATIENTS - IS IT A MARKER OF STRIATAL PRESYNAPTIC DEGENERATION

The aim of this study was to assess the correlation between the functi onal integrity and density of striatal dopaminergic receptors and clin ical data in 15 de-novo patients with idiopathic Parkinson's disease b y single photon emission tomography (SPET) using 2-[I-123]-iodolisurid e (ILIS), a tracer based on the D-2-dopamine receptor agonist lisuride . Deficient striatal uptake of ILIS correlated with the severity of th e disorder, scored by the Unified Parkinson's Disease Rating Scale (UP DRS) (n = 15; ratio of ILIS uptake: basal ganglia/cerebellum [B/C] & U PDRS I-III, Spearman R = -0.562, P = 0.013), Beck's Depression Invento ry (BDI) (n = 12; B/C & BDI, Spearman R = -0.825, P = 0.0009) and the ZUNG Depression Scale (ZDS) (n = 11; B/C & ZDS, Spearman R = -0.7425, P = 0.008). Experimental data indicate that lisuride shows a higher af finity for pre-synaptic dopaminergic autoreceptors than for post-synap tic D-2-dopamine receptors under conditions of low applied ILIS concen trations as in this study. From the results of this study and these ex perimental data, we speculate that ILIS-SPET can visualize pre-synapti c striatal dopaminergic degeneration in Parkinson's disease.