EFFECTS OF VALPROIC ACID ON EXPRESSION OF THE MELATONIN RECEPTORS MT1 AND MT2, AND THE NEUROTROPHIC FACTORS BDNF AND GDNF IN VIVO

Abstract

<p>Valproic acid (VPA) is clinically utilized as an anti-convulsant and mood stabilizer, though its mechanism of action has not been fully elucidated.<strong> </strong>Evidence suggests an interaction between VPA and the melatonergic system as VPA up-regulated the melatonin MT₁ receptor subtype in rat C6 glioma cells. To determine if the observed effects can translate to an <em>in vivo </em>model, we investigated the effects of chronic VPA administration in a rat model on the expression of MT₁ and MT₂ receptors in the hippocampus. We also investigated the effect of chronic VPA treatment on the expression of the neurotrophic factors BDNF and GDNF in the rat hippocampus and striatum.</p> <p>(1) Animals were separated into two groups with the experimental group receiving VPA (4 mg/mL) for 17 days, and the control receiving vehicle. The hippocampus was dissected and MT₁, MT₂, BDNF and GDNF mRNA were analyzed with RT-PCR. (2) Animals were separated into three groups with the first group receiving VPA (4 mg/mL), the second receiving VPA (3 mg/mL) for 16 days, and the control receiving vehicle. MT₂ mRNA in the hippocampal subregions were analyzed with in situ hybridization.</p> <p>VPA induced the expression of MT₁ and MT₂ mRNA in the hippocampus in the experimental group compared to the control group. VPA also increased MT₂ mRNA expression in the subregions of the hippocampus. Additionally, BDNF and GDNF mRNA expression were increased in the VPA treatment group.</p> <p>These findings raise the interesting question of whether the diverse clinical effects of VPA involve an interaction with the melatonergic system.</p>