Construction of Normal Database of Neurotransmission System in the Human Brain using Positron emission tomography

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The central dopaminergic system is of interest in the pathophysiology of neuropsychiatric diseases. Both pre and postsynaptic dopaminergic functions can be estimated by PET. However, the integrated database of both pre and postsynaptic dopaminergic functions including receptors, transporter, and endogenous neurotransmitter synthesis has not been reported. In the present study, we have built the normal database of pre and postsynaptic dopaminergic functions in the living human brain using PET. Tb measure the striatal and extrastriatal dopamine D_2 receptor binding, dopamine transporter binding, and endogenous dopamine synthesis, PET scans were performed on total of 37 healthy men after intravenous injection of C-11-raclopride, C-11-FLB457, C-11-PE2I, or C-11-DOPA. The binding potential was calculated by the reference tissue model method on a voxel by voxel basis. For C-11-DOPA study, the dopamine synthesis index was calculated from the ratio of area under the time-activity curve of brai … More n regions to a reference region. All PET images were anatomically standardized using SPM2, and database was built for each radiotracer. These databases allow to compare regional distributions of the striatal and extrastriatal dopamine D_2 receptor binding, dopamine transporter binding, and endogenous dopamine synthesis. In the striatum, greatest bindings to dopamine D_2 receptors and transporters and greatest dopamine synthesis were observed. For the limbic system, relatively high bindings of dopamine D2 receptors and relatively high dopamine synthesis were observed in the amygdala and anterior cingulate. Among the neocortical regions, highest binding to dopamine a receptors was observed in the temporal cortex. The binding to dopamine transporter was very low in the neocortical regions. These distributions were in good agreement with those in the human post mortem studies. This database is useful to understand physiology of dopaminergic neurotransmission in the living human brain, and can be applied to investigate regional abnormality of dopaminergic functions in neuropsychiatric diseases. Less