The Effects of anEchinaceaPreparation on Synaptic Transmission and the Firing Properties of CA1 Pyramidal Cells in the Hippocampus

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Abstract

Traditionally,Echinaceapreparations are used as antiinflammatory agents and immune-enhancers. In addition to these effects, their anxiolytic potency has been recognized recently in laboratory tests. Our aim in this study was to uncover the potential effects of anEchinaceapreparation on neuronal operations in the hippocampus, a brain region that is involved in anxiety and anxiety-related behaviors. Usingin vitroelectrophysiological techniques, we observed that excitatory synaptic transmission in hippocampal slices was significantly suppressed by anEchinaceaextract found to be effective in anxiety tests. In contrast, no change in inhibitory synaptic transmission could be detected upon application of this extract. In addition, our experiments revealed that at low concentration theEchinaceaextract reduced the spiking activity of CA1 pyramidal cells, while at high concentration increased it. This latter observation was parallel to the reduction in the magnitude of the h-current-mediated voltage responses in pyramidal cells. At any concentrations, the passive membrane properties of CA1 pyramidal cells were found to be unaltered by theEchinaceaextract. In summary, theEchinaceaextract can significantly regulate excitatory, but not inhibitory, synaptic transmission in the hippocampus, and this action might be involved in its anxiolytic effects observed in behaviour tests. Copyright © 2011 John Wiley & Sons, Ltd.

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