Fig. 8.

Forskolin-induced arg3.1/arc mRNA levels are blocked by MAPK/ERK kinase inhibitor in PC12 cells and primary cultures of hippocampal neurons. PC12 cells and primary cultures of hippocampal neurons were pretreated with the MAPK/ERK kinase blocker PD098059 (50 μm) and subsequently stimulated by forskolin (n = 3). Hippocampal neurons were also pretreated with the PKA blocker H-89 (compare with Fig.7D,E). A,C, Autoradiographs of Northern blots loaded with RNA from PC12 cells (A) and RNA from hippocampal neurons (C). Hybridization was with probes specific for arg3.1/arc, c-fos, and GAPDH.B,D, Quantification of arg3.1/arc and c-fos hybridization signals from analyses of PC12 cells and hippocampal neurons, respectively. Error bars represent SEM; *p < 0.05 (two-tailed Student'st test); NS, not significant,p > 0.05. Although the induction of arg3.1/arc mRNA by forskolin was blocked in PC12 cells and hippocampal neurons by the MAPK/ERK kinase inhibitor, induction of c-fos mRNA was affected to a much lesser extent.