Herbert Ehringer and Oleh Hornykiewicz* found in 1960 that basal ganglia dopamine levels in Parkinson’s patients were about one-tenth of normal levels, a finding that dovetails with consistent degeneration of the substantia nigra. However, signs of the disease do not typically appear until dopamine levels have decreased by at least 80 to 90%. A standard treatment is to administer the drug L-dopa (Sinemet), which can be converted to extra dopamine by the few remaining neurons of the substantial nigra. This can temporarily compensate for the loss of dopaminergic cells, but it does not halt the disease process. Another treatment is deep brain stimulation: electrodes are surgically implanted in the thalamus to inactivate essential tremors and in the globus pallidus, the main output of the basal ganglia, to combat the effects of dystonia. Parkinson’s disease was first accurately described by James Parkinson (1755-1824) in 1817, and later in more detail by Jean-Martin Charcot (1825-1893).
See Acetylcholine (AcH), Akinesia, Basal ganglia (anatomy), Basal ganglia (disorders), Dopamine, Dystonia, Extrapyramidal system, Glial-derived neurotrophic factor (GDNF), Hypertonia, Nerve Growth Factor (NGF), Red nucleus, Thalamus
* Ehringer, H., & Hornykiewicz, O. (1960). Verteilung von noradrenalin und Dopamin(3-hydroxy tryptamin) im Gehrin des Menschen und ihr Verhalten beiErkrankungen des extrapyramidalen Systems. Klin Wochenscher, 38, 1236-9.