Ginkgo biloba extract EGb 761 or trolox C prevent the ascorbic acid/Fe2+ induced decrease in synaptosomal membrane fluidity.
The ability of synaptosomes, prepared from striata, to take up 3H-dopamine declined rapidly during incubation at 37 degrees C, in an oxygenated Krebs-Ringer medium with 0.1 mM ascorbic acid. Ascorbic acid was responsible for this decrease. Its effectiveness after a 60 min incubation was concentration dependent from 1 microM and virtually complete for 0.1 mM. Furthermore, a decrease of synaptosomal membrane fluidity was revealed by measurements of fluorescence polarization using 1,6-diphenyl-1,3,5-hexatriene. This decrease was potentiated by Fe2+ ions (1 microM). In contrast, it was prevented by the Fe2+ ion chelator, desferrioxamine (0.1 mM), by the Ginkgo biloba extract EGb 761 [2-16 micrograms/ml], as well as by the flavonoid quercetin (0.1 microM). This preventive effect was shared by trolox C (from 0.1 mM). It is concluded that peroxidation of neuronal membrane lipids induced by ascorbic acid/Fe2+ is associated with a decrease in membrane fluidity which, in turn, reduces the ability of the dopamine transporter to take up dopamine.
Ramassamy
C
C
Unité de Neuropsychopharmacologie Expérimentale, U.R.A. 1170 du C.N.R.S., Faculté de Médecine & Pharmacie de Rouen, Saint-Etienne du Rouvray, France.
Girbe
F
F
Christen
Y
Y
Costentin
J
J
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D002839:Chromans / Q000494:pharmacology*; D004161:Diphenylhexatriene; D004298:Dopamine / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005296:Ferrous Compounds / Q000494:pharmacology*; D005453:Fluorescence; D005663:Furans / Q000494:pharmacology; D020441:Ginkgo biloba; D066298:In Vitro Techniques; D008297:Male; D008560:Membrane Fluidity / Q000187:drug effects*; D051379:Mice; D010936:Plant Extracts / Q000494:pharmacology*; D011794:Quercetin / Q000494:pharmacology; D013570:Synaptic Membranes / Q000187:drug effects* / Q000378:metabolism; D000096983:Ginkgo Extract
D000975:Antioxidants; D001205:Ascorbic Acid; D002839:Chromans; D004161:Diphenylhexatriene; D004298:Dopamine; D005296:Ferrous Compounds; D005663:Furans; D010936:Plant Extracts; D011794:Quercetin; C063170:Ginkgo biloba extract; D000096983:Ginkgo Extract; C018674:tetrahydrofuran; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid