Disrupted Neurotransmitter Function

Synaptic transmissionImage from NIA, NIHThe disruption of dopaminergic function, and ultimate loss of dopamine neurons, is the hallmark of PD, and this eventually leads to the cardinal motor symptoms of PD: bradykinesia, rigidity and tremor.

However, PD also involves changes in neurotransmitter biochemistry beyond the dopaminergic system. Evidence for involvement of specific neurotransmitter systems in PD derives from post mortem histology, in vivo functional imaging, and the effects of pharmaceutical treatments. The non-dopaminergic neurotransmitters affected in Parkinson’s disease, and are therefore potential targets for therapeutic development, are noradrenaline (norepinephrine), serotonin (5-hydroxytryptamine; 5-HT), glutamate, gamma-aminobutyric acid (GABA), acetylcholine and neuropeptides (Francis and Perry, 2007).

Some PD symptoms, particularly those that are not responsive to dopamine replacement therapy, may result from this disruption of other neurotransmitter pathways.