Effects of lithium and valproate on serum and hippocampal neurotrophin-3 levels in an animal model of mania

It has been demonstrated that lithium (Li) and valproate (VPT), first line mood stabilizers, increase BDNF content in rat hippocampus and frontal cortex, which suggests that the regulation of neurotrophic factors might be associated with their pharmacological effects. In sight of the scarcity of studies with other neurotrophins, and the possible relevance of multiple neurotrophic signaling systems in bipolar disorder we investigated the effects of Li and VPT on NT-3 levels in rat serum and hippocampus, using an animal model of mania induced by amphetamine (AMPH). In the reversal model, adult male Wistar rats received AMPH or saline for 14 days, and between the 8th and 14th days, animals were treated with Li, VPT or saline. In the prevention model, rats were pretreated with Li, VPT or saline, and between the 8th and 14th days, the animals received AMPH or saline. Li increased serum and hippocampal NT-3 levels in all conditions, whereas VPT increased hippocampal NT-3 in the prevention model only. Li reversed AMPH changes in NT-3 in the reversal model, and VPT prevented AMPH changes in NT-3 in the prevention model. These results suggest that both Li and VPT modulate serum and central (hippocampal) NT-3 levels, and further support that the regulation of neurotrophic signaling systems may be related to the mechanisms of action of mood stabilizers.