title: Piracetam induces plasma membrane depolarization in rat brain synaptosomes.
abstract: Piracetam is a cyclic derivative of γ-aminobutyric acid (GABA). It was the first nootropic drug approved for clinical use. However, mechanism of its action is still not clear. In present paper, I investigated effects of piracetam on neurotransmitter release, plasma membrane potential monitored by fluorescent dye DiSC3(5) and chloride transport monitored by fluorescent dye SPQ in rat brain synaptosomes. It was shown that piracetam (1 mM) induces slow weak plasma membrane depolarization. This effect was decreased on 43% and 58% by both AMPA/kainate receptor blockers NBQX (10 μM) and CNQX (100 μM), respectively, on 84% by GABA ionotropic receptor blocker picrotoxin (50 μM) and on 91% upon withdrawal of HCO(3-) ions from incubation medium. GABA (1 mM) and kainate (100 μM) were found not to produce changes of plasma membrane potential. Also, it was found that piracetam induces chloride efflux which seems to be the reason of depolarization. Thereby, piracetam induces depolarization of plasma membrane of isolated neuronal presynaptic endings by picrotoxin-sensitive way.
authors.affiliation: Laboratory of Biophysics and Engineering of Cell, Institute of Biophysics and Cell Engineering, Akademicheskaya Street, 27, Minsk 220072, Belarus. Electronic address: fedorovich@ibp.org.by.
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Fedorovich
mesh_terms: D000818:Animals; D052160:Benzothiazoles; D001692:Biological Transport; D001921:Brain / Q000187:drug effects* / Q000502:physiology; D002232:Carbocyanines; D002462:Cell Membrane / Q000502:physiology*; D016764:Cell Polarity; D002712:Chlorides / Q000378:metabolism; D005456:Fluorescent Dyes; D018756:GABA Antagonists / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D018697:Nootropic Agents / Q000494:pharmacology*; D011806:Quinolinium Compounds; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors; D018092:Kainic Acid Receptors / Q000037:antagonists & inhibitors; D013574:Synaptosomes / Q000187:drug effects* / Q000502:physiology
chemical_list: D052160:Benzothiazoles; D002232:Carbocyanines; D002712:Chlorides; D005456:Fluorescent Dyes; D018756:GABA Antagonists; D018697:Nootropic Agents; D011806:Quinolinium Compounds; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; C012944:3,3'-dipropyl-2,2'-thiadicarbocyanine; C052335:6-methoxy-N-(3-sulfopropyl)quinolinium
keywords: 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide hydrate; 1,4-di(5-phenyl-2-oxazolyl)benzene; 2,5-diphenyloxazole; 3,3′-dipropylthiadicarbocianyne; 6-cyano-7-nitroquinoxaline-2,3-dione; AMPA; CNQX; Chloride; DiSC3(5); GABA; HEPES; Kainate; N-[2-hydroxyethyl]piperazine-N′-[2-ethanesulfonic acid]; NBQX; Nootropic drug; POPOP; PPO; Piracetam; SPQ; Synaptosomes; Tris; Tris(hydroxymethyl)aminomethane; methoxy-N-(3-sulfopropyl)quinolinium; α-amino-3-hydroxy-5-methylisoxazole-4-propionate; γ-aminobutyric acid