Neuroprotective effects mediated by dopamine receptor agonists against malonate-induced lesion in the rat striatum

In rats, intrastriatal injection of malonate, a reversible inhibitor of the mitochondrial enzyme succinate dehydrogenase, induces a lesion similar to that observed following focal ischemia or in Huntington's disease. In this study we used the malonate model to explore the neuroprotective potential of dopamine agonists. Rats were injected intraperitoneally with increasing concentrations of D₁, D₂, or mixed D₁/D₂ dopamine agonists prior to intrastriatal injection of malonate. Administration of increasing doses of the D₂-specific agonist quinpirole resulted in increased protection against malonate toxicity. Conversely, the D₁-specific agonist SKF-38393, as well as the mixed D₁/D₂ agonist apomorphine, conferred higher neuroprotection at lower than at higher drug concentrations. Our data suggest that malonate-induced striatal toxicity can be attenuated by systemic administration of dopamine agonists, with D₁ and D₂ agonists showing different profiles of efficacy.