Parkinson’s disease (PD) afflicts approximately 1.5 million Americans annually. Although drugs such as levodopa (Sinemet) are available for the treatment of parkinsonian symptoms, they often produce disabling side effects called dyskinesias. These side effects are thought to arise as a result of abnormal drug- and disease-induced neurotransmitter interactions in an area of the brain called the basal ganglia. Our proposed studies will use an animal model of PD and examine the utility of combining a new drug (a cyclic nucleotide phosphodiesterase inhibitor called TP-10) with levodopa for treating disease symptoms and associated side effects. We will also assess how this novel drug combination affects neuron activity in the basal ganglia. We anticipate that our proposed studies will identify more efficacious treatment strategies for patients suffering from PD and levodopa-induced dyskinesias.