1
|
Bukanova JV, Solntseva EI, Skrebitsky VG. Factors promoting the release of picrotoxin from the trap in the GABA(A) receptor pore. Neurochem Int 2024; 175:105703. [PMID: 38395151 DOI: 10.1016/j.neuint.2024.105703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/31/2024] [Accepted: 02/21/2024] [Indexed: 02/25/2024]
Abstract
Picrotoxin (PTX), a convulsant of plant origin, has been used in many studies as research tool. PTX is the open channel blocker of the GABAA receptor (GABAAR). Being in the pore, PTX initiates transfer of the channel to the closed state and thus it falls into the "trap". The consequence of this PTX trapping is so-called aftereffect, i.e. continuation of the blockade of the GABA-induced chloride current (IGABA) after removal of PTX from the external solution. The present work shows that the positive allosteric modulators (PAMs) of the GABAA receptor, allopregnanolone (Allo) and zolpidem (Zolp) as well as a high concentration of GABA shortened the PTX aftereffect. Experiments were carried out on isolated Purkinje neurons of the rat cerebellum using the whole-cell patch-clamp method. IGABA was induced by applications of 5 μM GABA (EC30) for 1 s with 30 s intervals. 50 μM PTX completely blocked IGABA, and recovery upon PTX washout occurred with a time constant (τrec) of 20.2 min. 1 μM Allo reduced the blocking effect of PTX by 30% and accelerated the recovery of IGABA by almost 10 times (τrec = 2.4 min). 0.5 μM Zolp did not change the IGABA block in the presence of PTX but accelerated the recovery of IGABA by more than 3 times (τrec = 5.6 min). Increasing the GABA concentration to 20 μM did not change the blocking effect of PTX, but accelerated recovery by 6 times (τrec = 3.3 min). The mechanism of the shortening of the PTX aftereffect is presumably the expansion of the GABAAR pore in the presence of PAMs and a high concentration of the agonist and, as a consequence, the escape of PTX from the "trap". The work describes new pharmacological properties of Allo and Zolp.
Collapse
Affiliation(s)
- Julia V Bukanova
- Brain Research Institute, Research Center of Neurology, Moscow, Russia
| | - Elena I Solntseva
- Brain Research Institute, Research Center of Neurology, Moscow, Russia.
| | | |
Collapse
|
2
|
Solntseva EI, Bukanova JV, Kondratenko R, Kudova E. Corticosteroids as Selective and Effective Modulators of Glycine Receptors. ACS Chem Neurosci 2023; 14:3132-3142. [PMID: 37584305 PMCID: PMC10485894 DOI: 10.1021/acschemneuro.3c00287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 08/07/2023] [Indexed: 08/17/2023] Open
Abstract
The mechanism of the negative impact of corticosteroids on the induction and progress of mental illness remains unclear. In this work, we studied the effects of corticosteroids on the activity of neuronal glycine receptors (GlyR) and GABA-A receptors (GABAAR) by measuring the chloride current induced by the application of GABA (2 or 5 μM) to isolated cerebellar Purkinje cells (IGABA) and by the application of glycine (100 μM) to pyramidal neurons of the rat hippocampus (IGly). It was found that corticosterone, 5α-dihydrodeoxycorticosterone, allotetrahydrocorticosterone, cortisol, and 17α,21-dihydroxypregnenolone were able to accelerate the desensitization of the IGly at physiological concentrations (IC50 values varying from 0.39 to 0.72 μM). Next, cortisone, 11-deoxycortisol, 11-deoxycorticosterone, 5β-dihydrodeoxycorticosterone, and tetrahydrocorticosterone accelerated the desensitization of IGly with IC50 values varying from 10.3 to 15.2 μM. Allotetrahydrocorticosterone and tetrahydrocorticosterone potentiated the IGABA albeit with high EC50 values (18-23 μM). The rest of the steroids had no effect on IGABA in the range of concentrations of 1-100 μM. Finally, our study has suggested a structural relationship of the 3β-hydroxyl group/3-oxo group with the selective modulatory activity on GlyRs in contrast to the 3α-hydroxyl group that is pivotal for GABAARs. In summary, our results suggest that increased GlyR desensitization by corticosteroids may contribute to brain dysfunction under chronic stress and identify corticosteroids for further development as selective modulators of GlyRs.
Collapse
Affiliation(s)
- Elena I. Solntseva
- Functional
Synaptology Laboratory, Brain Research Institute,
Research Center of Neurology, Moscow 125367, Russia
| | - Julia V. Bukanova
- Functional
Synaptology Laboratory, Brain Research Institute,
Research Center of Neurology, Moscow 125367, Russia
| | - Rodion Kondratenko
- Functional
Synaptology Laboratory, Brain Research Institute,
Research Center of Neurology, Moscow 125367, Russia
| | - Eva Kudova
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague 166 10, Czech Republic
| |
Collapse
|
3
|
Bukanova JV, Kondratenko RV, Solntseva EI. Positive allosteric modulators of GABA A receptor restore chloride current from blockade by competitive antagonists in a ligand-dependent manner. J Steroid Biochem Mol Biol 2022; 224:106158. [PMID: 35931327 DOI: 10.1016/j.jsbmb.2022.106158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/26/2022] [Accepted: 07/30/2022] [Indexed: 10/31/2022]
Abstract
γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter. GABA receptor type A (GABAAR) possesses binding sites for a large group of pharmacological agents which are supposed to interact allosterically with each other. The aim of this work was to study the interaction between the positive allosteric modulators (PAMs) and the competitive antagonists of GABAARs. The GABA-induced chloride current (IGABA) was measured in isolated Purkinje cells of rat cerebellum using the patch-clamp technique. PAMs, neurosteroid allopregnanolone (Allo) and zolpidem (Zolp), a drug that positively modulates the GABAAR through interaction with the benzodiazepine (BDZ) site, doubled the IGABA amplitude in the control solution. Competitive antagonist of GABAARs, bicuculline (Bic, 5 µM) blocked the IGABA by 90%. The addition of 1 μM Allo or 0.5 µM Zolp to the Bic solution caused an unblocking effect, so that the IGABA amplitude increased 10 and 4 times from control value, correspondingly. This unblocking effect developed slowly, as evidenced by a threefold increase in the current rise time. Competitive antagonist of GABAARs, gabazine (GBZ, 0.5 µM) blocked the IGABA by 87%. The addition of 1 μM Allo to the GBZ solution caused an unblocking effect, so that the IGABA amplitude increased 7-fold. However, the addition of 0.5 µM Zolp to the GBZ solution did not cause an unblocking effect. So, Allo appeared to have a stronger unblocking potential than Zolp, and Bic binding site showed a higher sensitivity to the action of unblocking PAMs than GBZ binding site. The results indicate for the first time the existence of an allosteric relationship between the sites binding PAMs and the competitive antagonists of GABAAR.
Collapse
|
4
|
Solntseva EI, Bukanova JV, Skrebitsky VG, Kudova E. Pregnane neurosteroids exert opposite effects on GABA and glycine-induced chloride current in isolated rat neurons. Hippocampus 2022; 32:552-563. [PMID: 35703084 DOI: 10.1002/hipo.23449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 05/16/2022] [Accepted: 06/01/2022] [Indexed: 11/11/2022]
Abstract
The ability of endogenous neurosteroids (NSs) with pregnane skeleton modified at positions C-3 and C-5 to modulate the functional activity of inhibitory glycine receptors (GlyR) and ionotropic ɣ-aminobutyric acid receptors (GABAA R) was estimated. The glycine and GABA-induced chloride current (IGly and IGABA ) were measured in isolated pyramidal neurons of the rat hippocampus and in isolated rat cerebellar Purkinje cells, respectively. Our experiments demonstrated that pregnane NSs affected IGABA and IGly in a different manner. At low concentrations (up to 5 μM), tested pregnane NSs increased or did not change the peak amplitude of the IGABA , but reduced the IGly by decreasing the peak amplitude and/or accelerating desensitization. Namely, allopregnanolone (ALLO), epipregnanolone (EPI), pregnanolone (PA), pregnanolone sulfate (PAS) and 5β-dihydroprogesterone (5β-DHP) enhanced the IGABA in Purkinje cells. Dose-response curves plotted in the concentration range from 1 nM to 100 μM were smooth for EPI and 5β-DHP, but bell-shaped for ALLO, PA and PAS. The peak amplitude of the IGly was reduced by PA, PAS, and 5α- and 5β-DHP. In contrast, ALLO, ISO and EPI did not modulate it. Dose-response curves for the inhibition of the IGly peak amplitude were smooth for all active compounds. All NSs accelerated desensitization of the IGly . The dose-response relationship for this effect was smooth for ALLO, PA, PAS and 5β-DHP, but it was U-shaped for EPI, 5α-DHP and ISO. These results, together with our previous results on NSs with androstane skeleton, offer comprehensive overview for understanding the mechanisms of effects of NSs on IGly and IGABA .
Collapse
Affiliation(s)
- Elena I Solntseva
- Functional Synaptology Laboratory, Brain Research Department, Research Center of Neurology, Moscow, Russia
| | - Julia V Bukanova
- Functional Synaptology Laboratory, Brain Research Department, Research Center of Neurology, Moscow, Russia
| | - Vladimir G Skrebitsky
- Functional Synaptology Laboratory, Brain Research Department, Research Center of Neurology, Moscow, Russia
| | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| |
Collapse
|
5
|
Solntseva EI, Bukanova JV, Kondratenko RV, Skrebitsky VG. Copper Ions Reduce the Effect of Protons on Desensitization of Glycine Receptors. Bull Exp Biol Med 2020; 169:791-794. [PMID: 33098514 DOI: 10.1007/s10517-020-04980-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Indexed: 11/28/2022]
Abstract
Chloride current (IGly) evoked by the rapid (600 msec) application of glycine on isolated pyramidal neurons of the rat hippocampus was recorded using the patch clamp technique. We studied the effect of individual or combined application of copper ions (Cu2+) and protons (H+) on IGly. It was found that both Cu2+ (10 μM) and H+ (pH 7.0 and 6.0) applied separately caused a fast and reversible effect on IGly that included two components: a decrease in peak amplitude (Ipeak) and a decrease in the desensitization time constant (τdes). During combined application, the effects on Ipeak were additive, which indicates the independence of the mechanisms of these effects. At the same time, the effect of combined application of Cu2+ and H+ on τdes was not additive and sometimes a slowdown of the total desensitization was observed. The latter result suggests that H+ and Cu2+ can play the role of mutual antagonists when they affect the desensitization of GlyR.
Collapse
|
6
|
Bukanova JV, Solntseva EI, Kudova E. Neurosteroids as Selective Inhibitors of Glycine Receptor Activity: Structure-Activity Relationship Study on Endogenous Androstanes and Androstenes. Front Mol Neurosci 2020; 13:44. [PMID: 32265652 PMCID: PMC7098970 DOI: 10.3389/fnmol.2020.00044] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 03/04/2020] [Indexed: 12/21/2022] Open
Abstract
The ability of androstane and androstene neurosteroids with modifications at C-17, C-5, and C-3 (compounds 1-9) to influence the functional activity of inhibitory glycine and γ-aminobutyric acid (GABA) receptors was estimated. The glycine- and GABA-induced chloride current (IGly and IGABA) were measured in isolated pyramidal neurons of the rat hippocampus and isolated rat cerebellar Purkinje cells, correspondingly, using the patch-clamp technique. Our results demonstrate that all the nine neurosteroids display similar biological activity, namely, they strongly inhibited IGly and weakly inhibited IGABA. The threshold concentration of neurosteroids inducing effects on IGly was 0.1 μM, and for effects on IGABA was 10–50 μM. Moreover, our compounds accelerated desensitization of the IGly with the IC50 values varying from 0.12 to 0.49 μM and decreased the peak amplitude with IC50 values varying from 16 to 22 μM. Interestingly, our study revealed that only compounds 4 (epiandrosterone) and 8 (dehydroepiandrosterone) were able to cause a significant change in IGABA in 10 μM concentration. Moreover, compounds 3 (testosterone), 5 (epitestosterone), 6 (dihydroandrostenedione), and 9 (etiocholanedione) did not modulate IGABA up to the concentration of 50 μM. Thus, we conclude that compounds 3, 5, 6, and 9 may be identified as selective modulators of IGly. Our results offer new avenues of investigation in the field of drug-like selective modulators of IGly.
Collapse
Affiliation(s)
| | | | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czechia
| |
Collapse
|
7
|
Rossokhin AV, Sharonova IN, Dvorzhak A, Bukanova JV, Skrebitsky VG. The mechanisms of potentiation and inhibition of GABA A receptors by non-steroidal anti-inflammatory drugs, mefenamic and niflumic acids. Neuropharmacology 2019; 160:107795. [PMID: 31560908 DOI: 10.1016/j.neuropharm.2019.107795] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 09/02/2019] [Accepted: 09/23/2019] [Indexed: 11/27/2022]
Abstract
Fenamates mefanamic and niflumic acids (MFA and NFA) induced dual potentiating and inhibitory effects on GABA currents recorded in isolated cerebellar Purkinje cells using the whole-cell patch-clamp and fast-application techniques. Regardless of the concentration, both drugs induced a pronounced prolongation of the current response. We demonstrated that the same concentration of drugs can produce both potentiating and inhibitory effects, depending on the GABA concentration, which indicates that both processes take place simultaneously and the net effect depends on the concentrations of both the agonist and fenamate. We found that the NFA-induced block is strongly voltage-dependent. The Woodhull analysis of the block suggests that NFA has two binding sites in the pore - shallow and deep. We built a homology model of the open GABAAR based on the cryo-EM structure of the open α1 GlyR and applied Monte-Carlo energy minimization to optimize the ligand-receptor complexes. A systematic search for MFA/NFA binding sites in the GABAAR pore revealed the existence of two sites, the location of which coincides well with predictions of the Woodhull model. In silico docking suggests that two fenamate molecules are necessary to occlude the pore. We showed that MFA, acting as a PAM, competes with an intravenous anesthetic etomidate for a common binding site. We built structural models of MFA and NFA binding at the transmembrane β(+)/α(-) intersubunit interface. We suggested a hypothesis on the molecular mechanism underlying the prolongation of the receptor lifetime in open state after MFA/NFA binding and β subunit specificity of the fenamate potentiation.
Collapse
Affiliation(s)
| | | | - Anton Dvorzhak
- Charité-Universitätsmedizin, Neuroscience Research Center, Berlin, Germany
| | | | | |
Collapse
|
8
|
Tikhonova TA, Rassokhina IV, Kondrakhin EA, Fedosov MA, Bukanova JV, Rossokhin AV, Sharonova IN, Kovalev GI, Zavarzin IV, Volkova YA. Development of 1,3-thiazole analogues of imidazopyridines as potent positive allosteric modulators of GABA A receptors. Bioorg Chem 2019; 94:103334. [PMID: 31711764 DOI: 10.1016/j.bioorg.2019.103334] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 09/17/2019] [Accepted: 09/30/2019] [Indexed: 12/14/2022]
Abstract
Structure-activity relationship studies were conducted in the search for 1,3-thiazole isosteric analogs of imidazopyridine drugs (Zolpidem, Alpidem). Three series of novel γ-aminobutyric acid receptor (GABAAR) ligands belonging to imidazo[2,1-b]thiazoles, imidazo[2,1-b][1,3,4]thiadiazoles, and benzo[d]imidazo[2,1-b]thiazoles were synthesized and characterized as active agents against GABAAR benzodiazepine-binding site. In each of these series, potent compounds were discovered using a radioligand competition binding assay. The functional properties of highest-affinity compounds 28 and 37 as GABAAR positive allosteric modulators (PAMs) were determined by electrophysiological measurements. In vivo studies on zebrafish demonstrated their potential for the further development of anxiolytics. Using the OECD "Fish, Acute Toxicity Test" active compounds were found safe and non-toxic. Structural bases for activity of benzo[d]imidazo[2,1-b]thiazoles were proposed using molecular docking studies. The isosteric replacement of the pyridine nuclei by 1,3-thiazole, 1,3,4-thiadiazole, or 1,3-benzothiazole in the ring-fused imidazole class of GABAAR PAMs was shown to be promising for the development of novel hypnotics, anxiolytics, anticonvulsants, and sedatives drug-candidates.
Collapse
Affiliation(s)
- Tatyana A Tikhonova
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russia
| | - Irina V Rassokhina
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russia
| | - Eugeny A Kondrakhin
- V. V. Zakusov Institute of Pharmacology, Russian Academy of Sciences, 8 Baltiyskaya Str., 125315 Moscow, Russia
| | - Mikhail A Fedosov
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russia
| | - Julia V Bukanova
- Research Center of Neurology, 5 By-str. Obukha, 105064 Moscow, Russia
| | | | - Irina N Sharonova
- Research Center of Neurology, 5 By-str. Obukha, 105064 Moscow, Russia
| | - Georgy I Kovalev
- V. V. Zakusov Institute of Pharmacology, Russian Academy of Sciences, 8 Baltiyskaya Str., 125315 Moscow, Russia
| | - Igor V Zavarzin
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russia
| | - Yulia A Volkova
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russia.
| |
Collapse
|
9
|
Bukanova JV, Solntseva EI, Kolbaev SN, Kudova E. Modulation of GABA and glycine receptors in rat pyramidal hippocampal neurones by 3α5β-pregnanolone derivatives. Neurochem Int 2018; 118:145-151. [PMID: 29886074 DOI: 10.1016/j.neuint.2018.06.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 05/25/2018] [Accepted: 06/06/2018] [Indexed: 12/28/2022]
Abstract
The ability of pregnanolone glutamate (PA-Glu), pregnanolone hemisuccinate (PA-hSuc) and pregnanolone hemipimelate (PA-hPim), neuroactive steroids with a negative modulatory effect on excitatory N-methyl-d-aspartate receptors, to influence the functional activity of inhibitory γ-aminobutyric acid and glycine receptors was estimated. The GABA- and glycine-induced chloride currents (IGABA and IGly) were measured in isolated pyramidal neurons of the rat hippocampus using the patch-clamp technique. Compound PA-Glu was found to potentiate IGABA and to inhibit IGly, while PA-hSuc and PA-hPim inhibited both IGABA and IGly. Moreover, PA-Glu, PA-hSuc, and PA-hPim had a greater effect on desensitization than on the peak amplitude of IGly. At a high concentration of glycine (500 μM), the effect of neurosteroids on the peak amplitude of IGly disappeared, and the acceleration of desensitization remained. The conversion of PA-Glu into androstane glutamate (AND-Glu), an analogue that lacks the C-17 acetyl moiety, completely eliminated the effects on these receptors. Our results indicate that the C-17 acetyl moiety is crucial for the action on IGABA and IGly. Our results indicate that the pregnanolone derivatives, in contrast to the androstane analogues, modulate IGABA and IGly at low micromolar concentrations and this family of neurosteroids can be useful for future structure-activity relationship studies of the steroid modulation of other receptor types.
Collapse
Affiliation(s)
| | | | | | - Eva Kudova
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic.
| |
Collapse
|
10
|
Bukanova JV, Solntseva EI, Kondratenko RV, Skrebitsky VG. The influence of acidic media on the effect of beta-amyloid peptide on the function of glycine receptor in hippocampal neurons. Neurochem Int 2017; 110:69-74. [PMID: 28919253 DOI: 10.1016/j.neuint.2017.09.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 09/05/2017] [Accepted: 09/13/2017] [Indexed: 11/25/2022]
Abstract
We have previously shown that application of beta-amyloid peptide 1-42 (Aβ) at picomolar/nanomolar concentrations caused a decrease in the peak amplitude and acceleration of desensitization of the glycine-activated chloride current (IGly) in hippocampal pyramidal neurons (Bukanova et al., 2016). The aim of this work was to study the effect of Aβ on IGly in an acidified medium. The relevance of this work is determined by the fact that the pathogenic effects of Aβ in Alzheimer's disease are usually accompanied by inflammatory processes and acidosis. The IGly was induced by 600 ms application of 100 μM (nearly EC50) or 500 μM (nearly saturating) glycine on isolated rat hippocampal neurons. The solution of glycine was neutral (pH 7.4) or acidic over a pH range of 5.0-7.0. It was found that 600 ms application of protons rapidly, reversibly and in dose-dependent manner decreased the peak amplitude and accelerated the desensitization of IGly. The effect of H+ on IGly desensitization did not depend on glycine concentration and may be considered noncompetitive, while the effect on IGly peak disappeared at saturating glycine concentration and can be regarded as a competitive. These characteristics of the proton effects on IGly coincide with the characteristics of the Aβ effects on IGly. Experiments with joint application of Aβ and H+ showed interdependence of their effects. Addition of Aβ to perfusing solution reduced H+ effects on IGly while long pretreatment of Aβ with acid solution prevented the effects of the peptide on IGly. Our results suggest the existence of common sites for Aβ and H+ on the GlyR and indicate a mutual weakening of the inhibitory action of these molecules on IGly.
Collapse
|
11
|
Rossokhin AV, Sharonova IN, Bukanova JV, Kolbaev SN, Skrebitsky VG. Block of GABA(A) receptor ion channel by penicillin: electrophysiological and modeling insights toward the mechanism. Mol Cell Neurosci 2014; 63:72-82. [PMID: 25305478 DOI: 10.1016/j.mcn.2014.10.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 09/29/2014] [Accepted: 10/07/2014] [Indexed: 11/26/2022] Open
Abstract
GABA(A) receptors (GABA(A)R) mainly mediate fast inhibitory neurotransmission in the central nervous system. Different classes of modulators target GABA(A)R properties. Penicillin G (PNG) belongs to the class of noncompetitive antagonists blocking the open GABA(A)R and is a prototype of β-lactam antibiotics. In this study, we combined electrophysiological and modeling approaches to investigate the peculiarities of PNG blockade of GABA-activated currents recorded from isolated rat Purkinje cells and to predict the PNG binding site. Whole-cell patch-сlamp recording and fast application system was used in the electrophysiological experiments. PNG block developed after channel activation and increased with membrane depolarization suggesting that the ligand binds within the open channel pore. PNG blocked stationary component of GABA-activated currents in a concentration-dependent manner with IC50 value of 1.12mM at -70mV. The termination of GABA and PNG co-application was followed by a transient tail current. Protection of the tail current from bicuculline block and dependence of its kinetic parameters on agonist affinity suggest that PNG acts as a sequential open channel blocker that prevents agonist dissociation while the channel remains blocked. We built the GABA(A)R models based on nAChR and GLIC structures and performed an unbiased systematic search of the PNG binding site. Monte-Carlo energy minimization was used to find the lowest energy binding modes. We have shown that PNG binds close to the intracellular vestibule. In both models the maximum contribution to the energy of ligand-receptor interactions revealed residues located on the level of 2', 6' and 9' rings formed by a bundle of M2 transmembrane segments, indicating that these residues most likely participate in PNG binding. The predicted structural models support the described mechanism of PNG block.
Collapse
Affiliation(s)
- Alexey V Rossokhin
- Research Center of Neurology, Russian Academy of Medical Sciences, 105064 Moscow, Russia.
| | - Irina N Sharonova
- Research Center of Neurology, Russian Academy of Medical Sciences, 105064 Moscow, Russia
| | - Julia V Bukanova
- Research Center of Neurology, Russian Academy of Medical Sciences, 105064 Moscow, Russia
| | - Sergey N Kolbaev
- Research Center of Neurology, Russian Academy of Medical Sciences, 105064 Moscow, Russia
| | - Vladimir G Skrebitsky
- Research Center of Neurology, Russian Academy of Medical Sciences, 105064 Moscow, Russia
| |
Collapse
|
12
|
Bukanova JV, Solntseva EI, Kondratenko RV, Skrebitsky VG. Glycine receptor in hippocampal neurons as a target for action of extracellular cyclic nucleotides. Neurosci Lett 2013; 561:58-63. [PMID: 24373992 DOI: 10.1016/j.neulet.2013.12.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 12/10/2013] [Accepted: 12/17/2013] [Indexed: 11/17/2022]
Abstract
Cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) are well known intracellular second messengers. At present study, we describe the effects of extracellularly applied cAMP and cGMP on glycine-induced chloride currents (I(Gly)) in isolated rat hippocampal pyramidal neurons. 50 or 500 μM glycine was applied for 600 ms with 1 min intervals. cAMP and cGMP were co-applied with glycine. We found that both cAMP and cGMP rapidly, reversibly and in a dose-dependent manner accelerated the I(Gly) desensitization. The effect was more prominent on I(Gly) induced by 500 μM than by 50 μM glycine. Dose-response curves were constructed in the 0.1-100,000 nM range of cAMP and cGMP concentrations. They demonstrate that threshold concentration of both compounds was about 1 nM and maximal effect was manifested at 100 nM. When cAMP and cGMP were added to the recording pipette, their extracellular application caused the effects similar to those obtained with normal intracellular medium. The effects of cyclic nucleotides remained unchanged in the presence of the antagonist of adenosine receptors in extracellular solution, and the agonist of adenosine receptors did not mimic the effect of cyclic nucleotides. The changes in the decay kinetics were equally pronounced at negative and positive membrane potentials. When co-administered 1 nM cAMP and 1 nM cGMP caused a weaker effect than either of the compounds alone which suggests a negative interaction between binding sites for cAMP and cGMP. This work describes a novel mode of action of cyclic nucleotides, namely, the modulation of GlyRs functions from extracellular side.
Collapse
Affiliation(s)
- Julia V Bukanova
- Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia
| | - Elena I Solntseva
- Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia.
| | - Rodion V Kondratenko
- Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia
| | | |
Collapse
|
13
|
Solntseva EI, Bukanova JV, Skrebitsky VG. Donepezil in low micromolar concentrations modulates voltage-gated potassium currents in pyramidal neurons of rat hippocampus. Biochem Biophys Res Commun 2013; 430:1066-71. [DOI: 10.1016/j.bbrc.2012.12.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 12/08/2012] [Indexed: 02/05/2023]
|
14
|
Solntseva EI, Bukanova JV, Marchenko EV, Skrebitsky VG. Impact of amyloid-β peptide (1-42) on voltage-gated ion currents in molluscan neurons. Bull Exp Biol Med 2012; 151:671-4. [PMID: 22485204 DOI: 10.1007/s10517-011-1412-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Different types of voltage-gated ion currents were recorded in isolated neurons of snail Helix pomatia using the two-microelectrode voltage-clamp technique. Application of amyloid-β peptide (1-42, 1-10 μM) in the bathing solution did not change delayed rectifier K(+)-current and leakage current, but enhanced inactivation of Ca(2+)-current and blocked Ca(2+)-dependent K(+)-current.
Collapse
Affiliation(s)
- E I Solntseva
- Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia.
| | | | | | | |
Collapse
|
15
|
Kapai NA, Bukanova JV, Solntseva EI, Skrebitsky VG. Donepezil in a narrow concentration range augments control and impaired by beta-amyloid peptide hippocampal LTP in NMDAR-independent manner. Cell Mol Neurobiol 2011; 32:219-26. [PMID: 21968642 DOI: 10.1007/s10571-011-9751-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 08/18/2011] [Indexed: 01/27/2023]
Abstract
Acetylcholinesterase (AChE) inhibitor donepezil is widely used for the treatment of Alzheimer's disease (AD). The mechanisms of therapeutic effects of the drug are not well understood. The ability of donepezil to reverse a known pathogenic effect of β-amyloid peptide (Abeta), namely, the impairment of hippocampal long-term potentiation (LTP), was not studied yet. The goal of the present study was to study the influence of donepezil in 0.1-10 μM concentrations on control and Abeta-impaired hippocampal LTP. Possible involvement of N-methyl-D: -aspartate receptors (NMDARs) into mechanisms of donepezil action was also studied. LTP of population spike (PS) was studied in the CA1 region of rat hippocampal slices. Change of LTP by donepezil treatment had a bell-shaped dose-response curve. The drug in concentrations of 0.1 and 1 μM did not change LTP while in concentration of 0.5 μM significantly increased it, and in concentration of 5 and 10 μM suppressed LTP partially or completely. Abeta (200 nM) markedly suppressed LTP. Addition of 0.1, 0.5 or 1 μM donepezil to Abeta solution caused a restoration of LTP. N-methyl-D: -aspartate (NMDA) currents were studied in acutely isolated pyramidal neurons from CA1 region of rat hippocampus. Neither Abeta, nor 0.5 μM donepezil were found to change NMDA currents, while 10 μM donepezil rapidly and reversibly depressed it. Results suggest that donepezil augments control and impaired by Abeta hippocampal LTP in NMDAR-independent manner. In general, our findings extend the understanding of mechanisms of therapeutic action of donepezil, especially at an early stage of AD, and maybe taken into account while considering the possibility of donepezil overdose.
Collapse
Affiliation(s)
- Nadezhda A Kapai
- Department of Brain Research, Center of Neurology RAMS, 5 per. Obukha, 105064 Moscow, Russia
| | | | | | | |
Collapse
|
16
|
Abstract
In isolated neurons of Helix pomatia, a two-microelectrode voltage clamp technique was used to study the effect of Fe3+ on voltage-gated potassium currents: a low-threshold fast-inactivating current (I(A)) and a high threshold slow-inactivating current with calcium-dependent (I(C)) and calcium-independent (I(DR)) components. Extracellular application of FeCl3 rapidly, reversibly and dose-dependently reduced the amplitude of I(A), I(C) and I(DR) with IC50 values of 49, 45 and 70 microM, respectively. Complete inhibition of K+ currents was reached at 100-500 microM Fe3+. The threshold for the total slow-inactivating potassium current shifted in a positive direction by 10-30 mV in the presence of Fe3+ (50-300 microM). Our work is the first demonstration of the strong blocking effect of Fe3+ on potassium currents of neuronal membrane.
Collapse
Affiliation(s)
- Julia V Bukanova
- Department of Brain Research, Institute of Neurology, Russian Academy of Medical Sciences, Moscow, Russia.
| | | | | |
Collapse
|
17
|
Solntseva EI, Bukanova JV, Marchenko E, Skrebitsky VG. Donepezil is a strong antagonist of voltage-gated calcium and potassium channels in molluscan neurons. Comp Biochem Physiol C Toxicol Pharmacol 2007; 144:319-26. [PMID: 17126610 DOI: 10.1016/j.cbpc.2006.10.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Revised: 10/04/2006] [Accepted: 10/15/2006] [Indexed: 11/24/2022]
Abstract
Donepezil is an acetylcholinesterase inhibitor used in Alzheimer's disease therapy. The neuroprotective effect of donepezil has been demonstrated in a number of different models of neurodegeneration including beta-amyloid toxicity. Since the mechanisms of neurodegeneration involve the activation of both Ca(2+)- and K(+)-channels, the study of donepezil action on voltage-gated ionic currents looked advisable. In the present study, the action of donepezil on voltage-gated Ca(2+)- and K(+)-channels was investigated on isolated neurons of the edible snail (Helix pomatia) using the two-microelectrodes voltage-clamp technique. Donepezil rapidly and reversibly inhibited voltage activated Ca(2+)-current (I(Ca)) (IC(50)=7.9 microM) and three types of high threshold K(+)-current: Ca(2+)-dependent K(+)-current (I(C)) (IC(50)=6.4 microM), delayed rectifier K(+)-current (I(DR)) (IC(50)=8.0 microM) and fast transient K(+)-current (I(Adepol)) (IC(50)=9.1 microM). The drug caused a dual effect on low-threshold fast transient K(+)-current (I(A)), potentiating it at low (5 microM) concentration, but inhibiting at higher (7 microM and above) concentration. Donepezil also caused a significant hyperpolarizing shift of the voltage-current relationship of I(Ca) (but not of any type of K(+)-current). Results suggest the possible contribution of the blocking effect of donepezil on the voltage-gated Ca(2+)- and K(+)-channels to the neuroprotective effect of the drug.
Collapse
Affiliation(s)
- Elena I Solntseva
- Brain Research Institute, Russian Academy of Medical Sciences, Per. Obukha, 5, 105064, Moscow, Russia
| | | | | | | |
Collapse
|
18
|
Bukanova JV, Solntseva EI, Skrebitsky VG. Cyclic nucleotides induce long-term augmentation of glutamate-activated chloride current in molluscan neurons. Cell Mol Neurobiol 2006; 25:1185-94. [PMID: 16388331 DOI: 10.1007/s10571-005-8371-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Accepted: 09/07/2005] [Indexed: 10/25/2022]
Abstract
1. Literature data indicate that serotonin induces the long-term potentiation of glutamate (Glu) response in molluscan neurons. The aim of present work was to elucidate whether cyclic nucleotides can cause the same effect. 2. Experiments were carried out on isolated neurons of the edible snail (Helix pomatia) using a two-microelectrode voltage-clamp method. 3. In the majority of the cells examined, the application of Glu elicited a Cl- -current. The reversal potential (Er) of this current lied between -35 and -55 mV in different cells. 4. Picrotoxin, a blocker of Cl- -channels, suppressed this current equally on both sides of Er. Furosemide, an antagonist of both Cl- -channels and the Na+/K+/Cl- -cotransporter, had a dual effect on Glu-response: decrease in conductance, and shift of Er to negative potentials. 5. A short-term (2 min) cell treatment with 8-Br-cAMP or 8-Br-cGMP caused long-term (up to 30 min) change in Glu-response. At a holding potential of -60 mV, which was close to the resting level, an increase in Glu-activated inward current was observed. This potentiation seems to be related to the right shift of Er of Glu-activated Cl- -current rather than to the increase in conductance of Cl- -channels. The blocking effect of picrotoxin rested after 8-Br-cAMP treatment. 6. The change in the Cl- -homeostasis as a possible mechanism for the observed effect of cyclic nucleotides is discussed.
Collapse
Affiliation(s)
- Julia V Bukanova
- Brain Research Institute, Russian Academy of Medical Sciences, Per. Obukha 5, 105064, Moscow, Russia.
| | | | | |
Collapse
|
19
|
Solntseva EI, Bukanova JV, Skrebitsky VG. Potassium channel modulation by acetylcholinesterase inhibitor donepezil. Dokl Biol Sci 2005; 405:417-20. [PMID: 16485632 DOI: 10.1007/s10630-005-0153-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Affiliation(s)
- E I Solntseva
- Research Institute of Brain, Russian Academy of Medical Sciences, per. Obukha 5, Moscow, 105064 Russia
| | | | | |
Collapse
|
20
|
Bukanova JV, Solntseva EI, Skrebitsky VG. Selective suppression of the slow-inactivating potassium currents by nootropics in molluscan neurons. Int J Neuropsychopharmacol 2002; 5:229-37. [PMID: 12366875 DOI: 10.1017/s1461145702002997] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Revised: 04/21/2002] [Indexed: 11/07/2022] Open
Abstract
The role of the voltage-gated K+ channels in the effect of some nootropics was investigated. Earlier, the multiple effect of high concentrations of two nootropics, piracetam and its peptide analogue GVS-111 [Seredenin et al. (1995), US Patent No. 5,439,930], on Ca2+ and K+ currents of molluscan neurons was shown [Solntseva et al. (1997), General Pharmacology 29, 85-89]. In the present work, we describe the selective effect of low concentrations of these nootropics as well as vinpocetine on certain types of K+ current. The experiments were performed on isolated neurons of the land snail Helix pomatia using a two-microelectrode voltage-clamp method. The inward voltage-gated Ca2+ current (ICa) and three subtypes of the outward voltage-gated K+ current were recorded: Ca2+-dependent K+ current (IK(Ca)), delayed rectifying current (IKD), and fast-inactivating K+ current (IA). It has been found that I Ca was not changed in the presence of 30 microM vinpocetine, 100 microM piracetam or 10 nM GVS-111, while slow-inactivating, TEA-sensitive IK(Ca) and IKD were inhibited (IK(Ca) more strongly than IKD). In contrast, the fast-inactivating, 4-AP-sensitive K+ current (IA) was not diminished by low concentrations of piracetam and GVS-111, while vinpocetine even augmented it. A possible role of slow-inactivating subtypes of the K+ channels in the development of different forms of dementia is discussed.
Collapse
Affiliation(s)
- Julia V Bukanova
- Brain Research Institute, Russian Academy of Medical Sciences, Moscow, Russia.
| | | | | |
Collapse
|
21
|
Solntseva EI, Bukanova JV. Enhancement of low-threshold A-current of the neuronal membrane by vinpocetine. Membr Cell Biol 2001; 14:181-8. [PMID: 11093580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
A low-threshold fast inactivating K+ current (I(Alth)) was recorded in isolated land snail neurons using the two-microelectrode voltage clamp method. A nootropic drug, vinpocetine, applied to the extracellular medium at a concentration of 1-100 microM potentiated I(Alth). The potentiation consisted in a rise of its peak amplitude and an increase of the half-decay time. Vinpocetine did not cause a shift of the steady-state activation and inactivation curves along the potential axis. Dibutyryl cyclic GMP (dcGMP) also increased the peak amplitude but did not change the time of current half-decay. dcAMP did not potentiate I(Alth). The possible role of K+-current potentiation in neuronal membranes in therapy of dementia is discussed.
Collapse
Affiliation(s)
- E I Solntseva
- Institute of Brain Research, Russian Academy of Medical Sciences, Moscow
| | | |
Collapse
|
22
|
Solntseva EI, Bukanova JV, Skrebitsky VG. The nootropic drug vinpocetine modulates different types of potassium currents in molluscan neurons. Comp Biochem Physiol C Toxicol Pharmacol 2001; 128:275-80. [PMID: 11239840 DOI: 10.1016/s1532-0456(01)00202-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Three types of high-threshold K+ currents were recorded in isolated neurons of the snail Helix pomatia using a two-microelectrode voltage clamp technique: transient K+ current (I(A)), delayed rectifier (I(KD)) and Ca2+-dependent K+ current (I(K(Ca))). Vinpocetine (1-100 microM) applied to the bath affected different types of K+ current in different ways: I(A) was increased (35+/-14%), I(KD) was moderately inhibited (20+/-9%) and I(K(Ca)) was strongly suppressed (45+/-15%). When I(A) and I(K(Ca)) were present in the same cell, vinpocetine exerted a dual effect on the total K+ current, depending on the amplitude of the test stimulus. In the presence of vinpocetine, the I-V curve crossed the control I-V curve. The inhibition of I(K(Ca)) by vinpocetine between 1 and 100 microM is unlikely to be a result of Ca2+ current (I(Ca)) suppression, as the latter was inhibited only at vinpocetine concentrations exceeding 300 microM. Dibutyryl cyclic GMP (dbcGMP) (but not dbcAMP) mimicked the effects of vinpocetine in the majority of cells tested (coefficient of correlation r=0.60, P<0.05, n=22). The data suggest that modulation of different types of K+ current in neuronal membrane can contribute, at least partially, to the nootropic effect of vinpocetine through the regulation of intracellular Ca2+ concentration.
Collapse
Affiliation(s)
- E I Solntseva
- Brain Research Institute, Russian Academy of Medical Sciences, per. Obukha 5, 103064, Moscow, Russia.
| | | | | |
Collapse
|
23
|
Solntseva EI, Bukanova JV, Ostrovskaya RU, Gudasheva TA, Voronina TA, Skrebitsky VG. The effects of piracetam and its novel peptide analogue GVS-111 on neuronal voltage-gated calcium and potassium channels. Gen Pharmacol 1997; 29:85-9. [PMID: 9195198 DOI: 10.1016/s0306-3623(96)00529-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
1. With the use of the two-microelectrode voltage-clamp method, three types of voltage-activated ionic currents were examined in isolated neurons of the snail Helix pomatia: high-threshold Ca2+ current (ICa), high-threshold Ca(2+)-dependent K+ current (IK(Ca)) and high-threshold K+ current independent of Ca2+ (IK(V)). 2. The effect of bath application of the nootropics piracetam and a novel piracetam peptide analog, ethyl ester of N-phenyl-acetyl-L-prolyl-glycine (GVS-111), on these three types of voltage-activated ionic currents was studied. 3. In more than half of the tested cells, ICa was resistant to both piracetam and GVS-111. In the rest of the cells, ICa decreased 19 +/- 7% with 2 mM of piracetam and 39 +/- 14% with 2 microM of GVS-111. 4. IK(V) in almost all cells tested was resistant to piracetam at concentrations up to 2 mM. However, IK(V) in two-thirds of the cells was sensitive to GVS-111, being suppressed 49 +/- 18% with 1 microM GVS-111. 5. IK(Ca) appeared to be the most sensitive current of those studied to both piracetam and GVS-111. Piracetam at 1 mM and GVS-111 at 0.1 microM decreased the amplitude of IK(Ca) in most of the cells examined by 49 +/- 19% and 69 +/- 24%, respectively. 6. The results suggest that piracetam and GVS-111 suppression of voltage-activated calcium and potassium currents of the neuronal membrane may regulate (both up and down) Ca2+ influx into neurons.
Collapse
Affiliation(s)
- E I Solntseva
- Institute of Brain Research, Russian Academy of Medical Sciences, Moscow, Russia.
| | | | | | | | | | | |
Collapse
|