Antagonism of GABAA-receptor complex allosteric modulators – propoxazepam and bemegride, possessing affinity to different macromolecule subunits
DOI:
https://doi.org/10.11603/mcch.2410-681X.2018.v0.i2.8638Keywords:
propoxazepam, bemegride, seizures, chemoconvulsants.Abstract
Introduction. Both GABA and its agonists/antagonists do not compete with benzodiazepines for binding sites and their action takes place only in the presence of GABA. The fact that benzodiazepines mitigate antagonists-induced seizures is the evidence of the GABA-receptor agglomerate complexity, as well as tight junction of its components. Analgesic and antoconvulsive components of propoxazepam (new 1.4-benzodiazepine alcoxy derivative) assume its interaction with GABAA-receptor which differs from binding sites for other benzodiazepines.
The aim of the study – propoxazepam anticonvulsive action pharmacological estimation on the bemegrideinduced convulsions experimental model for determining its binding sites.
Research Methods. Anticonvulsive action of propoxazepam (intraperitoneally administered) was estimated after bemegride-induced seizures (58 mg/kg subcutaneously, 0.5 hours after propoxazepam administration) as their quantity and appearance time (for both myoclonic and tonic components) and total animals survival time.
Results and Discussion. Propoxazepam administration increases the time of different seizures development on experimental animals. Even in low doses which do not exhibit significant protective action (from 0.35 mg/kg) animals survival time increases substantially in compare to control group but not in a dose-dependent manner. Antagonism between propoxazepam and bemegride in vivo seems to take place through different binding sites what determinates dose-dependence absence between survival time and propoxazepam dose. There is no significant difference between time of different seizures types (myoclonic or tonic) appearance and their quantity (bemegrideor picrotoxine-inuced) after their suppression with propoxazepam.
Conclusions. It was found that propoxazepam ED50 on this model is 0,96±0,12 μmol/kg. Propoxazepam dose increase lead to increasing of myoclonic seisures appearance time, which indicates GABA-ergic functionality increase, impaired by bemegride. Relatively high propoxazepam doses (>1.5 mg/kg) inhibited tonic seizures with mainly represented myoclonic component. At the dose of 4 mg/kg propoxazepam totally blocked these seizures appearance.
References
Sige, E., & Steinmann, M.E. (2012). Structure, function, and modulation of GABAA receptors. J. Biol. Chem., 287 (48), 40224-40231.
Semyanov, A.B. (2002). GAMK-ergicheskoe tormozhenie v TsNS: tipy GAML-retseptorov i mekhanizmy tonicheskogo GAMK oposredovannogo tormoznogo deystviya [GABA-ergic inhibition in CNS: types of GABAreceptors
and mechanisms of tonic GABA-mediated inhibitory action]. Neyrofiziologiya – Neurophysiology, 34 (1), 82-92 [in Russian].
Smith, T.A. (2001). Type A gamma-aminobutyric acid (GABAA) receptor subunits and benzodiazepine binding: significance to clinical syndromes and their treatment. Br. J. Biomed. Sci., 58 (2), 111-121.
Jentsch, T.J., Stein, V., Weinreich, F., & Zdebik, A.A. (2002). Molecular structure and physiological function of chloride channels. Physiol. Rev., 82, 503-568.
Lapach, S.N., Chubenko, A.B., & Babich, P.N. (2001). Statisticheskie metody v mediko-biologicheskikh issledovaniyakh s ispolzovaniem Excel [Statistical methods in medical-biological studies using Excel]. Morion:
Kyiv [in Russian].
Glants, S. (1999). Mediko-biologicheskaya statistika [Medical-biological statistics]. Moscow: Praktika [in Russian].
Holovenko, N.Ya., Larionov, V.B., Reder, A.S., Voloshchuk, N.I., Valivodz, I.P., & Taran, I.V. (2016). Aktyvatsiia GAMK-erhichnoi systemy рropyloksipokhidnym 1.4-benzdiazepinu na modeliakh neiropatychnoho
boliu ta sudom, shcho vyklykani korazolom [GABA-ergic system activation by propyloxyderivative of 1,4-benzodiazepine in models of neuropathic pain and corazol-induced seizures]. Zhurnal NAMNU – Journal of the NAMNU, 22
(3-4), 318-324 [in Ukrainian].
Voloshchuk, N.I., Reder, А.S., Holovenko, M.Ya., Taran, I.V., & Pashynska, О.S. (2017). Farmakolohichnyi analiz neiirokhimichnykh ta ntynotsytseptyvnykh mekhanizmiv dii propoksazepamu [Pharmacological analysis of neurochemical antinociceptive mechanisms of propoxazepam action]. Farmakolohiia ta lik. Toksykolohiia – Pharmacology and Drug Toxicology, 1 (52), 3-11 [in Ukrainian].
Reder, A.S., Andronati, S.A., Holovenko, M.Ya., Pavlovskyi, V.I., Kabanova, T.A., Khalimova O.I., Larionov, V.B. et al. (2017). Zastosuvannia 7-brom-5-(o-khlorfenil)- 3propoksi-1,2-dihidro-3H-1,4-benzdiazepin-2-onu
dlia halmuvannia neiropatychnoho boliu ta sudom riznoi etiolohii [The use of 7-bromo-5 (o-chlorophenyl)-3-propoxy- 1,2-dihydro-3H-1,4-enzodiazepin-2-one for inhibition of neuropathic pain and seizures of different etiology.].
Patent Ukrainy – Ukrainian Patent No. 115205; 2017, Sept 25 [in Ukrainian].
Sigel, E., & Luscher, B.P. (2011). A closer look at the high affinity binding site for benzodiazepines on GABAA receptors. Cur. Top Med. Chem., 11, 241-246.
Larionov, V.B., & Holovenko, M.Ya. (2017). Molekuliarnyi dokinh benzdiazepiniv – alosterychnykh moduliatoriv GAMK-retseptory [Molecular docking of benzodiazepines – GABA receptor allosteric modulators]. Farmakolohiia ta lik. Toksykolohiia – Pharmacology and Drug Toxicology, 4-5 (53), 38-49 [in Ukrainian].
Holovenko, M.Ya., Pavlovskyi, V.I., Larionov, V.B., & Valivodz, I.P. (2017). Napivempirychnyi analiz vzaiemodii alkoksipokhidnykh 1,4-benzdiazepiny z GAMKA-retseptorom na pidstavi dannykh molekuliarnoho dokinhy ta armakolohichnoho efekty [Semi-empirical analysis of 1.4-benzodiazepine alcoxy derivatives interaction with GABAA-receptor on the base of molecular docking data and pharmacological effect]. Medychna ta klinichna khimiia
– Medical and Clinical Chemistry, 19 (4), 23-30 [in Ukrainian].
Mistry, D.K., & Cottrell, G.A. (1990). Actions of steroids and bemegride on the GABAA receptor of mouse spinal neurones in culture. Exp. Physiol., 75 (2), 199-209.
Olsen, R. (2006). Picrotoxin-like channel blockers of GABAA receptors. Proc. Natl. Acad. Sci. USA, 18; 103 (16), 6081-6082.
Golovenko, N.Ya., Larionov, V.B., Reder, A.S., & Valivodz’, I.P. (2017). [An effector analysis of the interaction of propoxazepam with antagonists of GABA and glycine receptors]. Neurochemical Journal, 11 (4), 302-308.
Sigel, E., & Steinmann, M. (2012). Structure, function, and modulation of GABAA receptors. The Journal of Biological Chemistry, 287 (48), 40224-40231.
Shaikh, M.F., Sancheti, J., & Sathaye, S. (2013). Effect of Eclipta alba on acute seizure models: a GABAA- mediated effect. Indian J. Pharm. Sci., 75 (3), 380-384.
Glykys, J., & Mody, I. (2007). Activation of GABAA receptors: Views from outside the synaptic cleft. Neuron, 56, 763-770.
Gatch, M.B. (2002). The discriminative stimulus effects of рentylenetetrazol as a model of anxiety: recent developments. Neurosci. Biobehav. Rev. 26 (4), 429-439.
Chang, Y., & Weiss, D.S. (2002). Site specific fluorescence reveals distinct structural changes with GABA receptor activation and antagonism. Nat. Neurosci., 5, 1163-1168.
