Upregulation of K+ Current in Hippocampal Neurons from Rat with Depressive-Like Behavior Induced by Lipopolysaccharide
脂多糖激活所致大鼠抑郁样行为及对海马神经细胞钾电流变化的影响

Lipopolysaccharide (LPS)-induced immunity activation can result in evident depressive-like behavior,such as anhedonia and reduced locomotion.Earlier studies have shown that K+ channels,such as Kv7 and TREK-1,are involved in the development of depressive-like behavior in animal models.In the present study,we show that LPS (200 μg/kg) could induce significant short-term depressive-like behavior in rat.In order to get insight into the underlying molecular mechanism,we investigated the potential involvement of rat hippocampal neuron voltage-dependent K+ channels in the depressive-like behaviors induced by LPS.Methods: Twenty rats were randomly divided into LPS and control groups,each with ten rats.The rats in the LPS group were injected with LPS (200 μg/kg),while saline was injected in the rats of the control group.The saccharin preference test and open field test were carried out 2 hours and 24 hours after injection of LPS to assess short-term or long-term effects on animal behavior,respectively.Next,12 rats were randomly divided into LPS 2 hr,LPS 24 hr and control groups,each with four rats for assessing the effect of LPS on K+ channel currents of hippocampal neurons by using whole-cell patch-clamp configuration.Results: The data showed that LPS induced depressive-like behavior in rat after 2 hours of single injection.However,this depressive-like behavior was recovered after 24 hours of single LPS injection.In agreement with these behavioral observations,voltage-dependent K+ current density was increased in neurons isolated from rat after 2 hours of single LPS injection,whereas no significant change was found after 24 hours injection.Conclusion: Our results demonstrate that LPS-induced immunity activation can result in evident short term depressive-like behavior in rats,which are coincident with LPS induced up-regulation of voltage-dependent K+ current in rat hippocampal neurons.This result suggests that voltage-dependent K+ current might contribute to the development of the depressive-like behavior induced by LPS.