Converging Effects of Ginkgo biloba Extract at the Level of Transmitter Release, NMDA and Sodium Currents and Dendritic Spikes

Abstract

In this study, an attempt was made to integrate the effects of Ginkgo biloba extract (GBE) in different experimental systems (in vitro cochlea, brain slice preparations and cortical cell culture) to elucidate whether these processes converge to promote neuroprotection or interfere with normal neural function. GBE increased the release of dopamine in the cochlea. NMDA-evoked currents were dose-dependently inhibited by rapid GBE application in cultured cortical cells. GBE moderately inhibited Na⁺ channels at depolarised holding potential in cortical cells. These inhibitory effects by GBE may sufficiently contribute to the prevention of excitotoxic damage in neurons. However, these channels also interact with memory formation at the cellular level. The lack of effect by GBE on dendritic spike initiation in neocortical layer 5 pyramidal neurons indicates that the integrative functions may remain intact during the inhibitory actions of GBE.

Abbreviations

bAP:backpropagating action potentials

DA:dopamine

FR:fractional release

GBE:Ginkgo biloba extract

NMDA:N-methyl-d-aspartate

AS:adenine sulfate

Key words

Ginkgo biloba - Ginkgoaceae - dopamine release - ion channel - NMDA receptor - dendritic spike

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