[PET study of dopamine metabolism and dopamine D2 receptor in juvenile parkinsonism].

Positron emission tomographic(PET) study using 18F-6-fluoro-L-dopa (18FDOPA) can provide efficient information on the pre-synaptic function of nigrostriatal dopaminergic neurons. In juvenile parkinsonism(JP), the accumulation of 18FDOPA is markedly decreased in the caudate nucleus and putamen on both hemispheres. This finding is different from those in dystonia syndromes such as dopa-responsive dystonia (DRD) and hereditary progressive dystonia with marked diurnal fluctuation(HPD), and it is rather similar to late onset of Parkinson's disease. Furthermore, we studied dopamine D2 receptor binding activity on the post-synaptic sites of the striatum using 11C-YM-09151-2(11C-YM), a highly selective dopamine D2 receptor antagonist. In JP, 11C-YM was highly accumulated in the striatum, and D2 receptor binding activity is not significantly different from that of age-matched young normal subjects, but much higher than that of aged subjects. This finding suggests that post-synaptic dopamine receptor function keeps still normal or hypersensitive in JP, and may be different from other degenerative disorders such as multiple system atrophy. Glucose metabolism using 18F-fluoro-2-deoxy-D-glucose(18FDG) was also within normal range in the cerebral cortex in JP, but was more increased in the striatum than in the cerebral cortex in some patients. These PET studies can provide efficient informations about the pathologic condition of JP.