Effects of activation of group I mGluRs with DHPG on expression of a transfected AP-1 luciferase fusion construct in cultured rat striatal neurons. A, DHPG, but not dopamine (DA), activated transcription of an AP-1 luciferase construct. DHPG or dopamine at 1, 10, or 100 μm was added 18 h after transfection of the construct, and cells were harvested 2 h after DHPG or dopamine treatment for luciferase activity assay. B, The DHPG-induced AP-1 transcription was reduced by MPEP and SP600125 but not by CPCCOet. MPEP (1μm), CPCCOet (5μm), or SP600125 (5μm) was added 30 min before the addition of DHPG (100μm), and cells were harvested 2 h after the DHPG treatment for luciferase activity assay. Values for luciferase activity measured as RLUs are given as fold induction, and data are represented as mean ± SEM of percentage of transfected control values (n = 4). *p < 0.05 versus basal levels. +p < 0.05 versus DHPG alone.