Shelley H. Huang, R. Duke, M. Chebib
Mar 7, 2003
Citations
3
Influential Citations
69
Citations
Quality indicators
Journal
European Journal of Pharmacology
Abstract
Abstract The sesquiterpene trilactone bilobalide is one of the active constituents of the 50:1 Ginkgo biloba leaf extract widely used to enhance memory and learning. Bilobalide was found to antagonise the direct action of γ-aminobutyric acid (GABA) on recombinant α1β2γ2L GABAA receptors. The effect of bilobalide on the direct action of GABA at α1β2γ2L GABAA receptors expressed in Xenopus laevis oocytes using two-electrode voltage-clamp method was evaluated and compared with the effects of the classical GABAA receptor competitive antagonist bicuculline and noncompetitive antagonist picrotoxinin. Bilobalide (IC50=4.6±0.5 μM) was almost as potent as bicuculline and pictrotoxinin (IC50=2.0±0.1 and 2.4±0.5 μM, respectively) at α1β2γ2L GABAA receptors against 40 μM GABA (GABA EC50). While bilobalide and picrotoxinin were clearly noncompetitive antagonists, the potency of bilobalide decreased at high GABA concentrations suggesting a component of competitive antagonism.