Fig. 4.

Glutamate, dopamine, and forskolin all induce c-fos mRNA, whereas only glutamate induces c-jun mRNA. A, Northern blot analysis for c-jun mRNA and c-fos mRNA induced by glutamate (100 μm). c-jun mRNA levels peak at an 8.5-fold induction 1.5 hr after glutamate stimulation. The more rapidly and more highly inducible c-fos mRNA peaks at 65-fold induction. Mean values ± SEM represent percentages of control levels (n = 3). B,C, Time courses for the effects of glutamate (100 μm), forskolin (10 μm), and dopamine (100 μm) on c-jun, c-fos, andcyclophilin mRNA. Northern blots were first hybridized with a c-jun riboprobe (3.2 and 2.5 kb transcripts), stripped, rehybridized with a c-fos riboprobe (2.2 kb transcript), and then hybridized for the third time with a cyclophilin cDNA probe. Cyclophilin (cyclo) mRNA was used as an internal loading control. All data are representative of at least three independent experiments.