[Neurochemistry of Parkinson's disease and parkinsonism plus]

The neurochemistry of Parkinson's disease and other degenerative parkinsonisms is reviewed, emphasizing the changes described in the dopaminergic system. Presynaptic dopaminergic markers are reduced over the striatum in all these degenerative parkinsonisms, dopamine receptor changes being more heterogeneous. While in Parkinson's disease D1 and D2 receptors remain preserved as compared to controls, in progressive supranuclear palsy there is a loss of nigral D1 receptors and of striatal D2 receptors. This finding has also been described in striatonigral degeneration. There are no clear data about the status of D3, D4 and D5 dopamine receptors in these conditions. The alterations in other neurotransmission systems, cholinegic, adrenergic, serotoninergic and peptidergic are, in general, less dramatic, although they have not been studied in detail. To conclude, further studies are necessary in these field, in these moment, however, the preservation of striatal D2 dopamine receptors is the neurochemical finding with the best correlation with the response to levodopa or other dopaminergic agonists.