Effects of repeated treatments with an extract of Ginkgo biloba (EGb 761), bilobalide and ginkgolide B on the electrical activity of pancreatic beta cells of normal or alloxan-diabetic mice: an ex vivo study with intracellular microelectrodes.
1. The effects of repeated (5-day) treatments with an extract of Ginkgo biloba leaves (EGb 761), bilobalide, and ginkgolide B on the in vitro electrical activity of insulin-secreting pancreatic beta cells of mice have been examined using intracellular microelectrodes. 2. EGb 761 (200 mg/kg/day, p.o.) protected beta cells against the toxic effects of alloxan (50 mg/kg, i.v.), an effect characterized by a restoration of membrane potential (Vr) and an increase in spike frequency (Fs/30), an indicator of insulin secretion. 3. Treatment of non-diabetic mice with EGb 761 (200 mg/kg/day, p.o.) increased Fs/30 of their beta cells, as tested by in vitro exposure of the cells to 11.1 mM glucose, an effect that also occurred with bilobalide (8 mg/kg/day, i.p.) but not with ginkgolide B (4 mg/kg/day, i.p.). 4. Since bilobalide and ginkgolide B caused opposite effects on the sensitivity of beta cells to glucose, the stimulatory effect of EGb 761 on Fs/30 may be attributed to its content of bilobalide. 5. In contrast to its ex vivo effect, the direct in vitro effect of EGb 761 (10 and 25 micrograms/ml) on beta cells favors a decrease in electrical activity, indicating that its in vivo action might be indirect (e.g. via the formation of an active metabolite).
Celaster Etudes Recherche et Production, Celle l'Evescault, France.
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DeFeudis
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Drieu
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002478:Cells, Cultured; D003470:Culture Media; D003517:Cyclopentanes / Q000494:pharmacology*; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology*; D004224:Diterpenes; D005260:Female; D005663:Furans / Q000494:pharmacology*; D020441:Ginkgo biloba; D046934:Ginkgolides; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D007424:Intracellular Fluid / Q000502:physiology; D007515:Islets of Langerhans / Q000187:drug effects* / Q000502:physiology*; D007783:Lactones / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008815:Mice, Inbred Strains; D008839:Microelectrodes; D010936:Plant Extracts / Q000494:pharmacology*; D000096983:Ginkgo Extract
D003470:Culture Media; D003517:Cyclopentanes; D004224:Diterpenes; D005663:Furans; D046934:Ginkgolides; D005947:Glucose; D007783:Lactones; D010936:Plant Extracts; C063170:Ginkgo biloba extract; D000096983:Ginkgo Extract; C045856:ginkgolide B; C073710:bilobalide