Figure 6.

D₁R stimulation and inhibition of PP1 modulates the level of pS421-htt in the striatum. A, B, Dopamine or the D₁-specific agonist SKF-81297 were either injected into the peritoneum (A) or via stereotactic surgery directly into the striatum (B) of WT mice. Mice were killed 15 min later, and the level of pS421-htt was determined in the striatum after immunoprecipitation of htt and Western blot. In all experiments, membranes were probed with Abs against pS421-htt and total htt followed by probing with secondary Abs and quantification of immunoreactivity. The relative level of htt phosphorylation at S421 was determined and expressed relative to vehicle-injected controls. *p < 0.05, **p < 0.005, by t test. Error bars denote ±SEM.