FIGURE 1.

Effects of glutamate, NMDA, AMPA, KCl, and forskolin on DARPP-32 phosphorylation at four major phosphorylation sites in striatal slices. Slices from the dorsal striatum were treated with glutamate (5 mm) (A–D), forskolin (1 μm) (E–H), NMDA (100 μm) (I–L), AMPA (100 μm) (M–P), or KCl (40 mm) (Q–T) for the indicated times. Changes in the phosphorylation of DARPP-32 at Thr-34 (the PKA site), Thr-75 (the Cdk5 site), Ser-97 (the CK2 site), and Ser-130 (the CK1 site) were determined by immunoblotting using phosphorylation state-specific antibodies. Typical immunoblots are shown at the top of each graph. Where samples were separated using 4–12% polyacrylamide Bis-Tris gels, molecular weight markers are indicated with asterisks. The data were normalized to values obtained from untreated slices. Data represent the means ± S.D. The number of experiments is indicated in parentheses. *, p < 0.05; **, p < 0.01; ***, p < 0.001 compared with control slices; one-way ANOVA followed by Newman-Keuls test. A.U., arbitrary units.