ABSTRACT

Parkinson’s disease is a neurodegenerative illness that to date cannot be treated curatively. The pathophysiology of the illness is known: in the extrapyramidal system there is a neurotransmitter imbalance in the sense of a lack of dopamine and a surplus of acetylcholine. Moreover, in this neuronal system two presynaptic inhibitory neurotransmitters are involved: GABA (which is increased) and glutamate (which is decreased). Thus, different treatments have been attempted in Parkinson’s disease since the neuronal circuits containing classically known neurotransmitters are altered in the extrapyramidal system.

It is also known that in addition to the above neurotransmitters, other neuropeptides are altered in Parkinson’s disease; for example altered concentrations of substance P, neuropeptide Y and thyrotropin-releasing hormone are found in the extrapyramidal system, and increased concentrations of galanin in the basal nucleus of Meynert have been demonstrated. In the light of this, our aim here is to review the alterations found in the concentrations of classical neuro-transmitters and neuropeptides in Parkinson’s disease. In order to optimize the treatment of Parkinson’s disease, we pose the question of whether an early diagnosis and an earlier onset of therapy with different drugs might improve the course of the disease. We shall discuss whether or not treatment with neuropeptide agonists or antagonists, as supplementary therapy, might improve the symptoms of Parkinson’s disease.