Clinically relevant concentrations of valproic acid modulate melatonin MT1 receptor, HDAC and MeCP2 mRNA expression in C6 glioma cells

C6 glioma cells were treated with clinically relevant concentrations of valproic acid (0.5 or 1.0 mM) for 1–7 days and RT-PCR used to examine expression of the melatonin MT1 receptor and selected epigenetic modulators. Valproic acid caused significant time-dependent changes in the mRNA expression of the melatonin MT1 receptor, histone deacetylase (HDAC) 1, 2 and 3, and methyl CpG binding protein 2 (MeCP2). A structurally distinct HDAC inhibitor, trichostatin A, also caused a significant concentration-dependent induction of melatonin MT1 receptor mRNA expression, suggesting involvement of an epigenetic mechanism. The ability of clinical concentrations of valproic acid to significantly alter melatonin MT1 receptor expression, suggests a role for this receptor in the diverse neuropharmacological and oncostatic effects of this agent.