Exercise Modifies α-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic Acid Receptor Expression in Striatopallidal Neurons in the 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine-Lesioned Mouse

The -amino-3-hydroxy-5-methyl-4-isoxazolepropionic-acid-type glutamate receptor (AMPAR) plays a critical role in modulating experience-dependent neuroplasticity, and alterations in AMPAR expression may underlie synaptic dysfunction and disease pathophysiology. Using the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of dopamine (DA) depletion, our previous work showed exercise increases total GluA2 subunit expression and the contribution of GluA2-containing channels in MPTP mice. The purpose of this study was to determine whether exercise-dependent changes in AMPAR expression after MPTP are specific to the striatopallidal (D2R) or striatonigral (D1R) medium spiny neuron (MSN) striatal projection pathways. Drd(2)-eGFP-BAC transgenic mice were used to delineate differences in AMPAR expression between striatal D2R-MSNs and D1R-MSNs. Striatal AMPAR expression was assessed by immunohistochemical (IHC) staining, Western immunoblotting (WB) of preparations enriched for postsynaptic density (PSD), and alterations in the current-voltage relationship of MSNs. We found DA depletion results in the emergence of GluA2-lacking AMPARs selectively in striatopallidal D2R-MSNs and that exercise reverses this effect in MPTP mice. Exercise-induced changes in AMPAR channels observed after DA depletion were associated with alterations in GluA1 and GluA2 subunit expression in postsynaptic protein, D2R-MSN cell surface expression, and restoration of corticostriatal plasticity. Mechanisms regulating experience-dependent changes in AMPAR expression may provide innovative therapeutic targets to increase the efficacy of treatments for basal ganglia disorders, including Parkinson's disease. (c) 2013 Wiley Periodicals, Inc.