The beta subunit increases the ginkgolide B sensitivity of inhibitory glycine receptors.

We investigated the effect of ginkgolide B (GB), a component of the extract from the leaves of the Ginkgo biloba tree, on recombinant glycine receptors (GlyRs) expressed in Xenopus oocytes by using voltage-clamp recording. GB (0.01-10 microM) inhibited glycine-induced currents of homo-oligomeric alpha1, alpha2 and alpha 3 GlyRs, with the highest potency being found at the alpha1 GlyR (IC(50) value=0.

Ginkgolide B preferentially blocks chloride channels formed by heteromeric glycine receptors in hippocampal pyramidal neurons of rat.

It has been found recently that the platelet activating factor antagonist ginkgolide B is a selective use-dependent blocker of glycine-gated chloride channels. GABAA receptor antagonist picrotoxin is known to block alpha homomeric glycine (Gly) receptors, being less effective for heteromeric alpha1/beta glycine receptors. Studying pyramidal hippocampal neurons of rat, we have confirmed that the effect of picrotoxin depends on the age of the animals.

Inhibition of hippocampal LTP by ginkgolide B is mediated by its blocking action on PAF rather than glycine receptors.

Platelet-activating factor (PAF), a biologically active lipid (1-O-alkyl-2-acetyl-sn-glycero-3-phosphoholine), is identified in different regions of brain, including hippocampus. Specific PAF-activated receptors (PAFRs) are expressed in corresponding brain areas. PAF has been proposed to be a retrograde messenger of long-term potentiation (LTP): the antagonist of PAFRs, ginkgolide B (or BN52021) prevents induction of LTP.

BN52021, a platelet activating factor antagonist, is a selective blocker of glycine-gated chloride channel.

We have found that the platelet activating factor antagonist (BN52021) is an effective blocker of the glycine (Gly) receptor-mediated responses in the hippocampal pyramidal neurons of rat. Using the whole-cell voltage clamp and concentration clamp recording techniques, we investigated the mechanism underlying the inhibitory action of this terpenoid on the glycine-induced chloride current. BN52021 selectively and reversibly inhibits glycine current in a non-competitive and voltage-dependent fashion.