Striatal perfusion with PD-102807 and tropicamide alleviated LID and inhibited nigral GABA and Glu along with striatal Glu release
In order to evaluate whether striatal M4 receptors influence LID and its neurochemical correlates, the M4 preferential antagonist PD-102807 and the putative M4 preferential antagonist tropicamide were perfused through the probe implanted in striatum. PD-102807 (3 μM) reduced LID expression by ~60% (U=0.00, p=0.0009; Fig. 2A), and inhibited the L-DOPA-induced rise of GABA (F2,21=12.64, p=0.0002; Fig. 2B) and Glu (F2,21=8.93, p=0.0016; Fig. 2C) in SNr, and Glu in striatum (F2,21=14.04, p=0.0001; Fig. 2D). Likewise, tropicamide (100 nM) attenuated LID expression by ~50% (U=24.50, p=0.0163; Fig 3A) and simultaneously prevented the rise of GABA (F2,21=8.04, p=0.0025; Fig. 3B) and Glu (F2,21=7.91; p=0.0027; Fig. 3C) in SNr and the elevation of Glu in striatum (F2,21=6.75; p=0.0054; Fig. 3D) associated with LID appearance.