title: Ginkgo biloba extract improves spatial memory in rats mainly but not exclusively via a histaminergic mechanism.
abstract: In order to clarify the mechanism of Ginkgo biloba extract (GBE) on learning and memory, we studied the effect of GBE on spatial memory deficits induced by diphenhydramine, pyrilamine and scopolamine using the eight-arm radial maze performance of rats, in comparison with donepezil. Total error (TE), reference memory error (RME) and working memory error (WME) were used as indices of spatial memory deficits. Both GBE and donepezil caused a potent antagonistic effect on the increase in TE, RME and WME induced by diphenhydramine. GBE and donepezil also antagonized scopolamine-induced spatial memory deficits. Although the antagonistic effect of GBE on pyrilamine-induced spatial memory deficits was weak, a significant difference was observed with TE and WME. However, donepezil caused no antagonistic effect on pyrilamine-induced memory deficits. From these findings, we concluded that the effects of GBE are mainly contributable to cholinergic activity and perhaps partly due to a histaminergic mechanism.
authors.affiliation: Department of Medicinal Pharmacology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8530, Japan.
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Adachi
authors.forename: Yoko
authors.initials: Y
authors.lastname: Fujii
authors.forename: Chiaki
authors.initials: C
authors.lastname: Kamei
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D001923:Brain Chemistry / Q000187:drug effects / Q000502:physiology; D004155:Diphenhydramine / Q000009:adverse effects; D000077265:Donepezil; D020441:Ginkgo biloba; D006632:Histamine / Q000378:metabolism*; D006634:Histamine H1 Antagonists; D007189:Indans / Q000494:pharmacology; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D008568:Memory / Q000187:drug effects / Q000502:physiology; D008569:Memory Disorders / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D018727:Muscarinic Antagonists / Q000009:adverse effects; D009434:Neural Pathways / Q000187:drug effects / Q000378:metabolism; D018697:Nootropic Agents / Q000494:pharmacology / Q000627:therapeutic use; D010880:Piperidines / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use; D011738:Pyrilamine / Q000009:adverse effects; D051381:Rats; D017208:Rats, Wistar; D012601:Scopolamine / Q000009:adverse effects; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D016896:Treatment Outcome
chemical_list: D006634:Histamine H1 Antagonists; D007189:Indans; D018727:Muscarinic Antagonists; D018697:Nootropic Agents; D010880:Piperidines; D010936:Plant Extracts; D006632:Histamine; D004155:Diphenhydramine; D000077265:Donepezil; D012601:Scopolamine; D011738:Pyrilamine; D000109:Acetylcholine