Fig. 2. Activation of ionotropic glutamate receptors and of L-type Ca2+ channels induces CREB phosphorylation, c-fos gene expression, and the3xCRE-luciferase construct in primary striatal cultures.A, Cultures were exposed to glutamate (50 μm), NMDA (50 μm), AMPA (50 μm), kainate (50 μm), and FPL 64176 (FPL; 20 μm) and harvested 15 min after the addition of each drug. Immunoblots were developed with the Ser133 CREB antiserum. All drugs induced CREB phosphorylation to varying degrees. Treatments are shown in duplicates from a representative experiment that was repeated four times.B, Cultures were exposed to glutamate (50 μm), NMDA (50 μm), AMPA (50 μm), kainate (50 μm), and FPL 64176 (20 μm) and harvested 40 min after the addition of each drug. Northern blots were developed with a c-fos riboprobe. All drugs induced c-fos mRNA to varying degrees. Duplicate treatments are shown in two separate blots. The experiment was repeated twice. C, Primary striatal cultures were transfected with a 3xCRE-luciferase construct and treated with glutamate (50 μm), NMDA (50 μm), AMPA (50 μm), kainate (50 μm), and FPL 64176 (20 μm) for 6 hr. Cells were harvested, and luciferase activity was measured. The average fold induction of luciferase activity (± SEM) over control levels is shown (n = 10 for each treatment). − indicates control without agonist.