Synaptotagmins (Syts) I and IV are synaptic proteins involved in the regulation of neurosecretion. Dopaminergic drugs have been shown to modulate their expression. Here we investigate whether dopaminergic regulation of syt I and syt IV expression could play a role in the hypersensitive striatum of rats with unilateral lesions of dopaminergic nigrostriatal neurons with 6-hydroxydopamine. We show that chronic dopaminergic denervation resulted in a small down-regulation of striatal syt I mRNA, whereas acute treatment with SKF-82958, a dopamine D1 receptor agonist, induced a massive syt IV mRNA upregulation in the striatum on the lesioned side. We conclude that chronic lack of dopamine and treatment with dopamine D1 receptor agonists alter the synaptic plasticity in dopamine depleted basal ganglia.