Progressive degeneration of the dopaminergic nigro-striatal fibre system is the main neuropathological correlate of Parkinson's disease (PD). More recently, neurochemical changes have been described in other basal ganglia disorders either with overt parkinsonian symptomatology or responsive to L-DOPA (e.g. DOPA-Responsive-Dystonia).
Changes in dopaminergic markers in animal models based on the neurotoxin MPTP suggest that the accumulation of endogenously formed, toxic dopamine transporter substrates such as isoquinoline or β-carboline derivatives, may represent the primary cause of substantia nigra cell degeneration specifically in patients with the idiopathic (most common) variety of PD.
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