Striatal dopamine during sensorial stimulations: a [18F]FDOPA PET study in human and cats.

Sensory stimulations of the forelimb in cats are known to increase dopamine release in the ipsilateral striatum and to decrease it in the homologous contralateral structure. Using positron emission tomography in both humans and cats, the present study shows that such sensory stimulations greatly reduce [(18)F]FDOPA accumulation ipsilateral to the stimulation (by 40.4% and 26.4% in the human caudate and putamen, respectively, and by 33.3% in the cat striatum). This decrease in striatal [(18)F]FDOPA uptake suggests a reduced DA storage resulting from the increased amine release. No change was observed in the contralateral striatum in neither human or cat suggesting, in contrast, that [(18)F]FDOPA accumulation is not facilitated by decreased DA release. These results support the hypothesis that sensory stimulations activate a non-synaptic mode of dopamine release.