Dopamine agonists and neuroprotection in Parkinson's disease.

Dopamine agonists are effective in reversing the motor symptoms of Parkinson's disease (PD). They have also shown that they can delay or prevent the onset of motor complications associated with levodopa use. Recent attention has focused on the possible role for dopamine agonists in neuroprotection. Numerous studies have demonstrated that a variety of dopamine agonists can protect dopaminergic neuronal function in several toxin model systems. Pramipexole in particular has shown efficacy in reducing toxicity to MPTP, MPP, rotenone and 6-hydroxydopamine. Recent studies in early PD using imaging parameters as a surrogate marker of dopaminergic neuronal integrity have shown that pramipexole and ropinirole can apparently retard the rate of cell loss. These observations are of considerable interest, but additional studies are required to confirm a neuroprotective function for these dopamine agonists.