Effects of bilobalide, a sesquiterpene in Ginkgo biloba leaves, on population spikes in rat hippocampal slices

The effects of bilobalide, a sesquiterpene isolated from the leaves of Gink go biloba L., were investigated in a rat hippocampal slice preparation. Bil obalide (10-500 mu M) significantly increased the amplitude of population s pikes evoked by electrical stimulation of Schaffer collateral/commissural f ibers in a concentration-dependent manner. Paired-pulse inhibition at inter pulse intervals of 10-50 ms was significantly reduced in the presence of bi lobalide (50 mu M) The inhibitory action of muscimol (1 mu M) was attenuate d by bilobalide (100 mu M). These results suggest that bilobalide induces a n enhancement of excitability of CA1 pyramidal neurons, which involves, at least in part, a reduction in GABAergic inhibition in rat hippocampus. (C) 1999 Elsevier Science Inc. All rights reserved.