FIGURE 3

Lithium and valproic acid (VPA) potentiate KCl-induced brain-derived neurotrophic factor promoter IV activation and increase the promoter activity in a construct devoid of calcium-responsive elements (CaREs). (a) Cortical neurons at 7 days in vitro (DIV) were treated with 1 mM LiCl or 0.5 mM VPA for 3 days, and at 8-DIV were transfected with each reporter vector and pRL-TK. Forty hours after transfection, cells were stimulated with 50 mM KCl, and 8 h later, luciferase activity was measured. The values were normalized to those of pGL3 basic and shown as meanss.e.m. from four experiments. ^** P<0.01, ^*** P<0.001 compared with KCl alone. (b and c) pGL3-710CaRE luc, which is devoid of the region of -74 to -31 bp, as shown in (b), was transfected into cortical neurons at 0-DIV by electroporation. The cultures at 8-DIV were then treated with LiCl (1 mM) and VPA (0.5 mM) for 48 h or exposed to KCl (50 mM) for 8 h. Luciferase activity from cell lysates was measured at 10-DIV (c). The values shown are relative to the vehicle control and expressed as meanss.e.m. from four independent cultures. ^* P<0.05, ^** P<0.01 compared with vehicle control.