Damage to the dopaminergic neurons

Damage to the dopaminergic neurons found in the substantia nigra has been the suggested cause of Parkinson disease. After the results of remarkable symptomatic relief by levodopa treatment, restoring dopaminergic activity has been the basis of the pharmacological treatment of Parkinson disease by administering dopamine precursors, dopamine receptor agonists, and inhibitors of dopamine metabolism.

Various dopamine agonists can increase dopamine activity in the brain. The majority of dopamine agonists used in Parkinson disease are D2 dopamine receptor agonists.

Ergot derivatives, older dopamine agonists, interact not only with dopamine D1 and D2 receptors but many other neurotransmitter receptors such as serotonin and adrenergic receptors. Newer dopamine agonists, which are non-ergot alkaloids, have a high affinity to dopamine D2 and D3 receptors.

Dopamine agonists stimulate the parts of the brain influenced by dopamine. In effect, dopamine agonists trick the brain into thinking it is receiving the dopamine it needs. In general, dopamine agonists are not as potent as carbidopa-levodopa and may be less likely to cause dyskinesias.