Annals of Clinical and Experimental NeurologyAnnals of Clinical and Experimental Neurology2075-54732409-2533Research Center of Neurology70110.25692/ACEN.2020.4.8UnknownEffects of zolpidem and protons on GABA-induced current in the hippocampal pyramidal neurons in the presence of penicillinSolntsevaElena I.synaptology@mail.ruBukanovaJulia V.synaptology@mail.ruSkrebitskyVladimir G.synaptology@mail.ruResearch Center of Neurology26122020144616526122020Copyright © 2020, Solntseva E.I., Bukanova J.V., Skrebitsky V.G.2020<p><strong>Introduction.</strong> Type A receptors activated by gamma-aminobutyric acid (GABA<sub>A</sub>R) play an inhibitory role in the nervous system due to the generation of chlorine current (<em>I</em><sub>GABA</sub>). Penicillin is a sequential blocker of the GABA<sub>A</sub>R open channel, which can inhibit dissociation of the GABA-receptor complex. This GABA site modulation suggests that the effects of competitive GABA<sub>A</sub>R modulators may change in the presence of penicillin.</p>
<p>The <strong>aim</strong> of the study was to evaluate the effect of zolpidem, the positive competitive GABA<sub>A</sub>R modulator, and hydrogen ions (protons), the negative competitive GABA<sub>A</sub>R modulator, on <em>I</em><sub>GABA</sub> in the presence of penicillin.</p>
<p><strong>Materials and methods. </strong><em>I</em><sub>GABA</sub> was measured on isolated pyramidal neurons of the rat hippocampus, using the patch clamp technique and fast application system. GABA, penicillin, and zolpidem were applied to the neuron for 600 msec via a lateral shift pipette. To study the effect of protons on <em>I</em><sub>GABA</sub>, the GABA solution in the application pipette was acidified to pH 6.07.0.</p>
<p><strong>Results.</strong> The application of 1 mmol of penicillin reduced the <em>I</em><sub>GABA</sub> amplitude to 67 4% of the control value. Zolpidem, with a concentration of 0.5 mol,increased the <em>I</em><sub>GABA</sub> amplitude to 167 9% of the control value. When penicillin and zolpidem were co-applied, the stimulating effect of zolpidem was not observed, and the <em>I</em><sub>GABA</sub> amplitude was 68 4%. Reducing the pH of the GABA solution to 7.0 or 6.0 caused the <em>I</em><sub>GABA</sub> amplitude to decrease to 804 and 35 4%, respectively. The effect of protons on <em>I</em><sub>GABA</sub> did not change in the presence of penicillin.</p>
<p><strong>Conclusion.</strong> For the first time, it has been shown that the stimulating effect of zolpidem on <em>I</em><sub>GABA</sub> is cancelled out by penicillin, while the inhibitory effect of protons on <em>I</em><sub>GABA</sub> is preserved.</p>GABA receptorspenicillinzolpidemprotonsГАМК-рецепторыпенициллинзолпидемпротоны[Sigel E., Steinmann M.E. Structure, function, and modulation of GABA(A) receptors. J Biol Chem 2012; 287: 40224–40231. DOI: 10.1074/jbc.R112.386664. PMID: 23038269.][Sieghart W. Allosteric modulation of GABAA receptors via multiple drug-binding sites. Adv Pharmacol 2015; 72: 53–96. DOI: 10.1016/bs.apha.2014.10.002. PMID: 25600367.][Klinger F., Bajric M., Salzer I. et al. δ Subunit-containing GABAA receptors are preferred targets for the centrally acting analgesic flupirtine. Br J Pharmacol 2015; 172: 4946–4958. DOI: 10.1111/bph.13262. PMID: 26211808.][Benveniste M., Mayer M.L. Trapping of glutamate and glycine during open channel block of rat hippocampal neuron NMDA receptors by 9-aminoacridine. J Physiol 1995; 483: 367–384. DOI: 10.1113/jphysiol.1995.sp020591. PMID: 7650609.][Rossokhin A.V., Sharonova I.N., Bukanova J.V. et al. Block of GABA(A) receptor ion channel by penicillin: electrophysiological and modeling insights toward the mechanism. Mol Cell Neurosci 2014; 63: 72–82. DOI: 10.1016/j.mcn.2014.10.001. PMID: 25305478.][Wisden W., Yu X., Franks N.P. GABA receptors and the pharmacology of sleep. Handb Exp Pharmacol 2019; 253: 279–304. DOI: 10.1007/164_2017_56. PMID: 28993837.][Bomalaski M.N., Claflin E.S., Townsend W., Peterson M.D. Zolpidem for the treatment of neurologic disorders: a systematic review. JAMA Neurol 2017; 74: 1130–1139. DOI: 10.1001/jamaneurol.2017.1133. PMID: 28655027.][Hanson S.M., Czajkowski C. Disulphide trapping of the GABA(A) receptor reveals the importance of the coupling interface in the action of benzodiazepines. Br J Pharmacol 2011; 162: 673–687. DOI: 10.1111/j.1476-5381.2010.01073.x. PMID: 20942818.][Chen Z.L., Huang R.Q. Extracellular pH modulates GABAergic neurotransmission in rat hypothalamus. Neuroscience 2014; 271: 64–76. DOI: 10.1016/j.neuroscience.2014.04.028. PMID: 24780768.][Huang R.Q., Chen Z., Dillon G.H. Molecular basis for modulation of recombinant alpha1beta2gamma2 GABAA receptors by protons. J Neurophysiol 2004; 92: 883–894. DOI: 10.1152/jn.01040.2003. PMID: 15028749.][Zhou C., Xiao C., Deng C., Hong Ye J. Extracellular proton modulates GABAergic synaptic transmission in rat hippocampal CA3 neurons. Brain Res 2007; 1145: 213–220. DOI: 10.1016/j.brainres.2007.01.121. PMID: 17321506.][Leng T.D., Si H.F., Li J. et al. Amiloride analogs as ASIC1a inhibitors. CNS Neurosci Ther 2016; 22: 468–476. DOI: 10.1111/cns.12524. PMID: 26890278.][Chow K.M., Hui A.C., Szeto C.C. Neurotoxicity induced by beta-lactam antibiotics: from bench to bedside. Eur J Clin Microbiol Infect Dis 2005; 24: 649–653. DOI: 10.1007/s10096-005-0021-y. PMID: 16261307.][Wilkins M.E., Hosie A.M., Smart T.G. Identification of a beta subunit TM2 residue mediating proton modulation of GABA type A receptors. J Neurosci 2002; 22: 5328–5333. DOI: 10.1523/JNEUROSCI.22-13-05328.2002. PMID: 12097484.][Kisiel M., Jatczak-Śliwa M., Mozrzymas J.W. Protons modulate gating of recombinant α1β2γ2 GABAA receptor by affecting desensitization and opening transitions. Neuropharmacology 2019; 146: 300–315. DOI: 10.1016/j.neuropharm.2018.10.016. PMID: 30326242.]