CCG-203920 targets RGS4 in vivo
To confirm the RGS4 selectivity of CCG-20920 in vivo, the neuroleptic-induced akinesia/catalepsy model was used since we previously reported that the RGS4 inhibitor CCG-203769 reversed raclopride-induced akinesia in mice (Blazeret al. , 2015). RGS4-/- mice were slightly hypokinetic at baseline, showing >2-fold greater immobility time in the bar test (14.45 ± 1.40 s, n=20) and 40% reduced stepping activity in the drag test (6.59 ± 0.56 steps, n=20) compared to controls (5.7 ± 0.48 s and 10.08 ± 0.45 steps, respectively; n=20 each). Two-way ANOVA revealed that raclopride caused a prolonged and marked increase of the immobility time (time F3,108=117.3, p<0.0001; treatment F3,36=11.34, p<0.0001, time X treatment interaction F9,108=6.35, p<0.0001) and a reduction of stepping activity (time F3,95=67.50, p<0.0001; treatment F3.36=18.95, p<0.0001, time X treatment interaction F9,108=4.09, p=0.0002) in both wild-type and RGS4-/- mice (Fig. 4). CCG-203920 administration significantly reversed raclopride-induced hypokinesia in wild-type animals but was ineffective in RGS4-/- mice, suggesting RGS4 targeting at this dose.