Conversely, reduced expression levels of striatal Homer1 and mGluR1a were previously observed after dopaminergic neuron death in the neurotoxic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD [41], while animals with nigrostriatal denervation exhibit DA supersensitivity and abnormal expression of several IEGs, such as HOMER1a [9]. The gene discussed is HOMER1; the disease is Parkinson disease.