[Dysfunction of serotonergic systems in thiamine-deficient diet fed mice: effects of SSRI on abnormality induced by...

Mice fed a thiamine deficient (TD) diet, showed some abnormal behaviors such as amnesia and mood abnormality. It is known that several neurons, especially marked in serotonergic neuron, are damaged in humans and rodents in the earlier phase of TD. The symptoms derived from dysfunction of serotonergic neurons are observed in Wernicke-Korsakoff patients (WKS)-derived TD, and it is known that fluvoxamine is effective for WKS. However, the mechanism of this dysfunction is still unclear. For that reason, we studied the relative mechanism between abnormal behaviors and selective dysfunction of serotonergic neurons in TD animals. As a result, this dysfunction by TD is much affected by the brainstem region. But the effect of fluvoxamine on depressive symptoms in WKS patients is not reported; therefore we also studied the effects of fluvoxamine on the depressive behaviors in TD mice as a model of WKS. The increase of immobility time in a forced swimming test as depressive behavior in TD mice was significantly inhibited by fluvoxamine, suggesting an improvable effect on depressive symptoms. With those results of ours, the possible mechanisms between the abnormal behaviors derived from the dysfunction of serotonergic neurons and the role of serotonin in TD and WKS are reviewed here.