Basal and NMDA receptor-dependent changes in reporter gene activity for Bdnf promoter deletions. Basal and NMDA receptor-dependent changes in reporter gene activity for Bdnf promoter deletions. A reporter construct having an intact Bdnf promoter 4, or constructs with a deletions of the CRE, or NF-κB binding sites, or the IS were cotransfected with a CMV-GFP plasmid into hippocampal neurons as described in Materials and Methods. Increasing concentrations of NMDA (0–200 μm) were added to the cultures, and after 36 h, ratios of RED/GFP protein were quantified. Neurons transfected with the intact promoter plasmid in the presence of increasing NMDA concentrations increased DsRed expression over the untreated control up to sixfold. Deletion of CRE, NF-κB, or IS segments decreased responsiveness of the reporter gene to NMDA. Deletion of the entire −117 to −79 region of promoter 4 completely abolished responsiveness to NMDA. Under basal conditions, reporter gene activity of the IS deletion mutant increased more than fivefold relative to the intact promoter, suggesting the presence of a repressor element within the IS. Basal reporter gene levels for a construct lacking the entire promoter region (−117 to −79 deletion), the CREB site, the IS, or the NF-κB site were expressed relative to the intact promoter. Results are expressed as mean ± SEM (n = 6). **p < 0.01 versus intact promoter; *p < 0.05 versus no addition; Δp < 0.05 basal (no addition) ΔIS and ΔNF-κB versus intact promoter (no addition) by ANOVA and by Student's t test. Xueying Jiang et al. J. Neurosci. 2008;28:1118-1130 ©2008 by Society for Neuroscience