Piracetam induces plasma membrane depolarization in rat brain synaptosomes

• Published in: Neuroscience letters Vol. 553; pp. 206 - 210
• Main Author: Fedorovich, Sergei V.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 11.10.2013
• Subjects: Animals; Benzothiazoles; Biological Transport; Brain - drug effects; Brain - physiology; Carbocyanines; Cell Membrane - physiology; Cell Polarity; Chloride; Chlorides - metabolism; Fluorescent Dyes; GABA; GABA Antagonists - pharmacology; Kainate; Male; Membrane Potentials - drug effects; Nootropic Agents - pharmacology; Nootropic drug; Piracetam; Quinolinium Compounds; Rats, Wistar; Receptors, AMPA - antagonists & inhibitors; Receptors, Kainic Acid - antagonists & inhibitors; Synaptosomes; Synaptosomes - drug effects; Synaptosomes - physiology; Kainate; AMPA; Nootropic drug; CNQX; PPO; Tris; DiSC3; Chloride; SPQ; HEPES; GABA; Synaptosomes; Piracetam; POPOP; NBQX; 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide hydrate; 2,5-diphenyloxazole; 6-cyano-7-nitroquinoxaline-2,3-dione; α-amino-3-hydroxy-5-methylisoxazole-4-propionate; methoxy-N-(3-sulfopropyl)quinolinium; 1,4-di(5-phenyl-2-oxazolyl)benzene; 3,3′-dipropylthiadicarbocianyne; γ-aminobutyric acid; Tris(hydroxymethyl)aminomethane; N-[2-hydroxyethyl]piperazine-N′-[2-ethanesulfonic acid]
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2013.08.045

•Piracetam induces plasma membrane depolarization in rat brain synaptosomes.•Piracetam-induced depolarization was sensitive to GABA receptors inhibitors.•Piracetam-induced depolarization was sensitive to AMPA/kainate receptor inhibitors.•Piracetam induces chloride efflux in rat brain synaptosomes. 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 (1mM) induces slow weak plasma membrane depolarization. This effect was decreased on 43% and 58% by both AMPA/kainate receptor blockers NBQX (10μM) and CNQX (100μM), respectively, on 84% by GABA ionotropic receptor blocker picrotoxin (50μM) and on 91% upon withdrawal of HCO3− ions from incubation medium. GABA (1mM) and kainate (100μM) 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.