GRIA2 and Parkinson disease: The AMPA receptor subunit modulation also revealed key differences: while GluA1 expression increased and GluA2 and GluA3 decreased in the PD group, the PD + Ex group exhibited reduced expression of GluA1 and increased GluA2 and GluA3 (VanLeeuwen et al., 2010; Kintz et al., 2013; Garcia et al., 2017).