PT - JOURNAL ARTICLE AU - Antonini, A. AU - Schwarz, J. AU - Oertel, W. H. AU - Beer, H. F. AU - Madeja, U. D. AU - Leenders, K. L. TI - [<sup>11</sup>C]raclopride and positron emission tomography in previously untreated patients with Parkinson's disease AID - 10.1212/WNL.44.7.1325 DP - 1994 Jul 01 TA - Neurology PG - 1325--1325 VI - 44 IP - 7 4099 - http://n.neurology.org/content/44/7/1325.short 4100 - http://n.neurology.org/content/44/7/1325.full SO - Neurology1994 Jul 01; 44 AB - We studied cerebral dopamine D2-receptor binding using [11C]raclopride and PET in 18 previously untreated patients with Parkinson's disease (PD) and 14 healthy volunteer subjects. Sixteen patients were scanned before and after 3 to 4 months of stable oral therapy with either L-dopa (300 mg/d) (n = 7) or lisuride (0.8 to 1.2 mg/d) (n = 9). Two additional patients were investigated before and after a continuous IV infusion of L-dopa. In addition, we studied the effect of acute IV L-dopa and lisuride administration on [11C]raclopride binding in a healthy rhesus monkey. At baseline, PD patients showed higher uptake values in the putamen than did healthy subjects (p &lt; 0.0001). Oral lisuride treatment lowered [11C]raclopride uptake in the putamen (-19%) and in the caudate nucleus (-15%) compared with baseline, but the difference did not reach significance upon Bonferroni correction for multiple comparisons. However, putamen tracer uptake returned to baseline in two patients when we repeated [11C]raclopride scans 4 days after lisuride withdrawal. Oral L-dopa treatment did not induce changes in the putamen or caudate nucleus indices. Acute lisuride (25 μg) administration in a healthy monkey reduced striatal uptake values, but acute injection of L-dopa (300 mg) did not. The results suggest that lisuride blocks [nC]raclopride binding at dopamine D2-receptor sites and demonstrate that 3 to 4 months' oral therapy with L-dopa or lisuride does not change striatal dopamine D2-receptor density in PD patients.