AT-403 inhibited D1 receptor-stimulated pGluR1 phosphorylation in striatum
The increase of pGluR1 levels is another biochemical correlate of LID in rodents (Santini et al. , 2007). GluR1 is a subunit of the glutamate AMPA receptor, which is physiologically phosphorylated by PKA activated by dopamine via D1 receptors. We therefore investigated whether CCG-203920 potentiates the ability of AT-403 (0.03 mg kg-1) to modulate pGluR1 levels. As expected, L-Dopa elevated pGluR1 levels in the lesioned stratum (+52%; t=2.272, df=12; Fig. 7A). However, in contrast to the effect on ERK, AT-403 alone was able to normalize pGluR1 levels (Fig. 7A), in line with the well-known inhibitory influence of NOP receptors over canonical D1 signaling. CCG-203920 did not alter the L-Dopa induced increase (+52%; t=2.239, df=10) or the AT-403-driven normalization of pGluR1 levels. Again, neither treatments affected total protein amounts (Fig. 7B).