Dopaminergic system: Clinical relevance for Parkinson's disease

Parkinson's disease is the most prevalent and progressive movement disorder in Germany. The occurrence of dyskinesias and motor fluctuations is the most common cause for motor disability in affected patients. During recent decades dopaminergic stimulation using levodopa and dopamine agonists is a very widely used and highly effective approach for the symptomatic therapy in Parkinson's disease to alleviate motor symptoms. Levodopa-induced motor complications in the early stages of treatment and the increased prevalence of fibrotic valvular heart disease after ergot-derived dopamine agonists have a major and dramatic impact for the therapeutic concept in Parkinson's disease. Besides its role as neurotransmitter dopamine plays an important role in the regulation of endogenous neurogenesis in the adult brain as well as in the diseased brain. An impaired olfactory bulb neurogenesis may be linked to the olfactory deficits in Parkinson's disease. It is important to note that the substantia nigra lacks the potential to replace endogenously dopaminergic neurons.