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Curry SH, Marler M. Effects of ecgonine methyl ester on cognition in scopolamine-impaired and aged rats. Psychopharmacology (Berl) 2020; 237:1331-1342. [PMID: 32034448 DOI: 10.1007/s00213-020-05460-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Accepted: 01/15/2020] [Indexed: 10/24/2022]
Abstract
RATIONALE Searches for antidotes to cocaine, and for cognition enhancers potentially applicable to Alzheimer's disease, have revealed a novel regulatory site on nicotinic acetylcholine receptors. In the presence of an agonist, inhibitors binding to this site changed the ion channel equilibrium from the open-channel form towards the closed form. Other, related, molecules could bind to the site without changing the equilibrium. These latter compounds were predicted to displace the inhibitors without affecting receptor function per se. These compounds alleviated the inhibition. One of them is ecgonine methyl ester (EME), which is generally described as inactive, but this work suggested a beneficial effect on cognition. OBJECTIVE This in vivo study tested for cognitive enhancement by EME in scopolamine-impaired, and aged, rats. METHODS Memory was the primary endpoint, but thigmotaxis became an important secondary endpoint in the light of observations made during the study. Impaired cognition was pharmacologically induced by scopolamine in young rats, and spontaneously present in aged rats. Learning ability before and after administration of EME was tested in Morris water maze protocols. Concentrations of EME in the brain and plasma were analyzed by gas chromatography-mass spectrometry. RESULTS A single dose of EME reversed scopolamine impairment, indicating involvement of acetylcholine receptors. Longer-term treatment improved cognition in aged rats, with enhanced rates of learning in the absence of an exogenous cognition-impairing compound. Impairment returned with a new challenge; the improvement could be re-established with continued dosing. EME also reversed thigmotaxis seen in aged rats; thigmotaxis is believed to indicate anxiety. The concentrations of EME in the brain proved adequate drug exposure. CONCLUSIONS Since other investigators have shown cognition impairment caused by cocaine in aged rats, this work shows that cocaine and EME have opposite effects in Morris water maze models. EME might induce cognitive enhancement and relief of anxiety in cocaine-impaired humans, and in other cognitive disorders.
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Ma ZG, Jiang N, Huang YB, Ma XK, Brek Eaton J, Gao M, Chang YC, Lukas RJ, Whiteaker P, Neisewander J, Wu J. Cocaine potently blocks neuronal α 3β 4 nicotinic acetylcholine receptors in SH-SY5Y cells. Acta Pharmacol Sin 2020; 41:163-172. [PMID: 31399700 PMCID: PMC7471406 DOI: 10.1038/s41401-019-0276-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Accepted: 06/23/2019] [Indexed: 02/05/2023] Open
Abstract
Cocaine is one of the most abused illicit drugs worldwide. It is well known that the dopamine (DA) transporter is its major target; but cocaine also acts on other targets including nicotinic acetylcholine receptors (nAChRs). In this study, we investigated the effects of cocaine on a special subtype of neuronal nAChR, α3β4-nAChR expressed in native SH-SY5Y cells. α3β4-nAChR-mediated currents were recorded using whole-cell recordings. Drugs were applied using a computer-controlled U-tube drug perfusion system. We showed that bath application of nicotine induced inward currents in a concentration-dependent manner with an EC50 value of 20 µM. Pre-treatment with cocaine concentration-dependently inhibited nicotine-induced current with an IC50 of 1.5 μM. Kinetic analysis showed that cocaine accelerated α3β4-nAChR desensitization, which caused a reduction of the amplitude of nicotine-induced currents. Co-application of nicotine and cocaine (1.5 μM) depressed the maximum response on the nicotine concentration-response curve without changing the EC50 value, suggesting a non-competitive mechanism. The cocaine-induced inhibition of nicotine response exhibited both voltage- and use-dependence, suggesting an open-channel blocking mechanism. Furthermore, intracellular application of GDP-βS (via recording electrode) did not affect cocaine-induced inhibition, suggesting that cocaine did not alter receptor internalization. Moreover, intracellular application of cocaine (30 µM) failed to alter the nicotine response. Finally, cocaine (1.5 μM) was unable to inhibit the nicotine-induced inward current in heterologous expressed α6/α3β2β3-nAChRs and α4β2-nAChRs expressed in human SH-EP1 cells. Collectively, our results suggest that cocaine is a potent blocker for native α3β4-nAChRs expressed in SH-SY5Y cells.
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Affiliation(s)
- Ze-Gang Ma
- Department of Physiology, Institute of Brain Science and Disorders, Medical College of Qingdao University, Qingdao, 266071, China
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Nan Jiang
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
- Department of Ophthalmology, the Affiliated Hospital of Qingdao University, Qingdao, 266003, China
| | - Yuan-Bing Huang
- Department of Neurology, Yunfu People's Hospital, Yunfu, 527300, China
| | - Xiao-Kuang Ma
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
- Department of Physiology, Shantou University Medical College, Shantou, 515004, China
| | - Jason Brek Eaton
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Ming Gao
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Yong-Chang Chang
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Ronald J Lukas
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Paul Whiteaker
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Janet Neisewander
- School of Life Sciences, Arizona State University, Tempe, AZ, 85287-4501, USA
| | - Jie Wu
- Department of Physiology, Institute of Brain Science and Disorders, Medical College of Qingdao University, Qingdao, 266071, China.
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA.
- Department of Neurology, Yunfu People's Hospital, Yunfu, 527300, China.
- Department of Physiology, Shantou University Medical College, Shantou, 515004, China.
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Krivoshein AV. Anticonvulsants Based on the α-Substituted Amide Group Pharmacophore Bind to and Inhibit Function of Neuronal Nicotinic Acetylcholine Receptors. ACS Chem Neurosci 2016; 7:316-26. [PMID: 26741746 DOI: 10.1021/acschemneuro.5b00259] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Although the antiepileptic properties of α-substituted lactams, acetamides, and cyclic imides have been known for over 60 years, the mechanism by which they act remains unclear. I report here that these compounds bind to the nicotinic acetylcholine receptor (nAChR) and inhibit its function. Using transient kinetic measurements with functionally active, nondesensitized receptors, I have discovered that (i) α-substituted lactams and cyclic imides are noncompetitive inhibitors of heteromeric subtypes (such as α4β2 and α3β4) of neuronal nAChRs and (ii) the binding affinity of these compounds toward the nAChR correlates with their potency in preventing maximal electroshock (MES)-induced convulsions in mice. Based on the hypothesis that α-substituted amide group is the essential pharmacophore of these drugs, I found and tested a simple compound, 2-phenylbutyramide. This compound indeed inhibits nAChR and shows good anticonvulsant activity in mice. Molecular docking simulations suggest that α-substituted lactams, acetamides, and cyclic imides bind to the same sites on the extracellular domain of the receptor. These new findings indicate that inhibition of brain nAChRs may play an important role in the action of these antiepileptic drugs, a role that has not been previously recognized.
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Affiliation(s)
- Arcadius V. Krivoshein
- Department of Basic and Social
Sciences, Albany College of Pharmacy and Health Sciences, 106
New Scotland Avenue, Albany, New York 12208, United States
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McConnell EM, Holahan MR, DeRosa MC. Aptamers as promising molecular recognition elements for diagnostics and therapeutics in the central nervous system. Nucleic Acid Ther 2015; 24:388-404. [PMID: 25296265 DOI: 10.1089/nat.2014.0492] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Oligonucleotide aptamers are short, synthetic, single-stranded DNA or RNA able to recognize and bind to a multitude of targets ranging from small molecules to cells. Aptamers have emerged as valuable tools for fundamental research, clinical diagnosis, and therapy. Due to their small size, strong target affinity, lack of immunogenicity, and ease of chemical modification, aptamers are an attractive alternative to other molecular recognition elements, such as antibodies. Although it is a challenging environment, the central nervous system and related molecular targets present an exciting potential area for aptamer research. Aptamers hold promise for targeted drug delivery, diagnostics, and therapeutics. Here we review recent advances in aptamer research for neurotransmitter and neurotoxin targets, demyelinating disease and spinal cord injury, cerebrovascular disorders, pathologies related to protein aggregation (Alzheimer's, Parkinson's, and prions), brain cancer (glioblastomas and gliomas), and regulation of receptor function. Challenges and limitations posed by the blood brain barrier are described. Future perspectives for the application of aptamers to the central nervous system are also discussed.
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Affiliation(s)
- Erin M McConnell
- 1 Department of Chemistry, Carleton University , Ottawa, Ontario, Canada
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Nery AA, Magdesian MH, Trujillo CA, Sathler LB, Juliano MA, Juliano L, Ulrich H, Ferreira ST. Rescue of amyloid-Beta-induced inhibition of nicotinic acetylcholine receptors by a peptide homologous to the nicotine binding domain of the alpha 7 subtype. PLoS One 2013; 8:e67194. [PMID: 23894286 PMCID: PMC3718777 DOI: 10.1371/journal.pone.0067194] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 05/15/2013] [Indexed: 11/19/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by brain accumulation of the neurotoxic amyloid-β peptide (Aβ) and by loss of cholinergic neurons and nicotinic acetylcholine receptors (nAChRs). Recent evidence indicates that memory loss and cognitive decline in AD correlate better with the amount of soluble Aβ than with the extent of amyloid plaque deposits in affected brains. Inhibition of nAChRs by soluble Aβ40 is suggested to contribute to early cholinergic dysfunction in AD. Using phage display screening, we have previously identified a heptapeptide, termed IQ, homologous to most nAChR subtypes, binding with nanomolar affinity to soluble Aβ40 and blocking Aβ-induced inhibition of carbamylcholine-induced currents in PC12 cells expressing α7 nAChRs. Using alanine scanning mutagenesis and whole-cell current recording, we have now defined the amino acids in IQ essential for reversal of Aβ40 inhibition of carbamylcholine-induced responses in PC12 cells, mediated by α7 subtypes and other endogenously expressed nAChRs. We further investigated the effects of soluble Aβ, IQ and analogues of IQ on α3β4 nAChRs recombinantly expressed in HEK293 cells. Results show that nanomolar concentrations of soluble Aβ40 potently inhibit the function of α3β4 nAChRs, and that subsequent addition of IQ or its analogues does not reverse this effect. However, co-application of IQ makes the inhibition of α3β4 nAChRs by Aβ40 reversible. These findings indicate that Aβ40 inhibits different subtypes of nAChRs by interacting with specific receptor domains homologous to the IQ peptide, suggesting that IQ may be a lead for novel drugs to block the inhibition of cholinergic function in AD.
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Affiliation(s)
- Arthur A. Nery
- Department of Biochemistry, Chemistry Institute, São Paulo University, São Paulo, SP, Brazil
| | - Margaret H. Magdesian
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Cleber A. Trujillo
- Department of Biochemistry, Chemistry Institute, São Paulo University, São Paulo, SP, Brazil
| | - Luciana B. Sathler
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Maria A. Juliano
- Department of Biophysics, Federal University of São Paulo, São Paulo, SP, Brazil
| | - Luiz Juliano
- Department of Biophysics, Federal University of São Paulo, São Paulo, SP, Brazil
| | - Henning Ulrich
- Department of Biochemistry, Chemistry Institute, São Paulo University, São Paulo, SP, Brazil
- * E-mail: (HU); (STF)
| | - Sergio T. Ferreira
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- * E-mail: (HU); (STF)
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Nunes-Alves A, Nery AA, Ulrich H. Tobacco nitrosamine N-nitrosonornicotine as inhibitor of neuronal nicotinic acetylcholine receptors. J Mol Neurosci 2012; 49:52-61. [PMID: 22847530 DOI: 10.1007/s12031-012-9859-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 07/12/2012] [Indexed: 12/22/2022]
Abstract
Nitrosamines are well known for their carcinogenic potential. Recently, it was found that some of them may also interact with human nicotinic acetylcholine receptor (nAChR) subtypes. This work studied the effects of N-nitrosonornicotine (NNN) on recombinant rat α3β4 nAChR in HEK cells as well as on nAChR endogenously expressed in PC12 pheochromocytoma cells and in BC3H1 muscle-type cells. Whole-cell recording in combination with the cell-flow technique for agonist and inhibitor application in the millisecond time region revealed that NNN inhibits the activity of neuronal nAChR expressed in HEK or PC12, whereas weak inhibitory effects on muscle-type nAChR were observed at NNN concentrations up to 3 mM. Pharmacological actions of NNN and the inhibition mechanism were studied in detail using recombinant α3β4 nAChR expressed in HEK cells as a model. NNN-induced inhibition of nicotine-evoked α3β4 nAChR activity was dose-dependent with an inhibitory constant (IC(50)) of 0.92 ± 0.05 mM. Analysis based on mathematical models indicated a noncompetitive inhibition mechanism of the rat α3β4 nAChR by NNN. NNN's mechanism of action involves acceleration of conversion of the receptor from active to desensitized forms. In summary, this work shows that NNN inhibits rat α3β4 nAChR in a noncompetitive way and interacts weakly with muscular nAChR.
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Affiliation(s)
- Ariane Nunes-Alves
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, São Paulo, São Paulo 05508-900, Brazil
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Cheffer A, Ulrich H. Inhibition mechanism of rat α₃β₄ nicotinic acetylcholine receptor by the Alzheimer therapeutic tacrine. Biochemistry 2011; 50:1763-70. [PMID: 21247200 DOI: 10.1021/bi101789y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) were studied in detail in the past regarding their interaction with therapeutic and drug addiction related compounds. Using fast kinetic whole-cell recording, we have now studied effects of tacrine, an agent used clinically to treat Alzheimer's disease, on currents elicited by activation of rat α(3)β(4) nAChR heterologously expressed in KXα3β4R2 cells. Characterization of receptor activation by nicotine used as agonist revealed a K(d) of 23 ± 0.2 μM and 4.3 ± 1.3 for the channel opening equilibrium constant, Φ(-1). Experiments were performed to investigate whether tacrine is able to activate the α(3)β(4) nAChR. Tacrine did not activate whole-cell currents in KXα3β4R2 cells but inhibited receptor activity at submicromolar concentration. Dose-response curves obtained with increasing agonist or inhibitor concentration revealed competitive inhibition of nAChRs by tacrine, with an apparent inhibition constant, K(I), of 0.8 μM. The increase of Φ(-1) in the presence of tacrine suggests that the drug stabilizes a nonconducting open channel form of the receptor. Binding studies with TCP and MK-801 ruled out tacrine binding to common allosteric sites of the receptor. Our study suggests a novel mechanism for action of tacrine on nAChRs besides inhibition of acetylcholine esterase.
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Affiliation(s)
- Arquimedes Cheffer
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo 05508-900, Brazil
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Nery AA, Trujillo CA, Lameu C, Konno K, Oliveira V, Camargo ACM, Ulrich H, Hayashi MAF. A novel physiological property of snake bradykinin-potentiating peptides-reversion of MK-801 inhibition of nicotinic acetylcholine receptors. Peptides 2008; 29:1708-15. [PMID: 18598727 DOI: 10.1016/j.peptides.2008.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 06/03/2008] [Accepted: 06/05/2008] [Indexed: 11/26/2022]
Abstract
The first naturally occurring angiotensin-converting enzyme (ACE) inhibitors described are pyroglutamyl proline-rich oligopeptides, found in the venom of the viper Bothrops jararaca, and named as bradykinin-potentiating peptides (BPPs). Biochemical and pharmacological properties of these peptides were essential for the development of Captopril, the first active site-directed inhibitor of ACE, currently used for the treatment of human hypertension. However, a number of data have suggested that the pharmacological activity of BPPs could not only be explained by their inhibitory action on enzymatic activity of somatic ACE. In fact, we showed recently that the strong and long-lasting anti-hypertensive effect of BPP-10c [<ENWPHPQIPP] is independent of somatic ACE inhibition. On the other hand, nicotinic acetylcholine receptors expressed in blood vessels have been related to blood pressure regulation. Therefore, we have studied the effects of BPP-10c on acetylcholine receptor function in the PC12 pheochromocytoma cell line, which following induction to neuronal differentiation expresses most of the nicotinic receptor subtypes. BPP-10c did not induce receptor-mediated ion flux, nor potentiated carbamoylcholine-provoked receptor activity as determined by whole-cell recording. This peptide, however, alleviated MK-801-induced inhibition of nicotinic acetylcholine receptor activity. Although more data are needed for understanding the mechanism of the BPP-10c effect on nicotinic receptor activity and its relationship with the anti-hypertensive activity, this work reveals possible therapeutic applications for BPP-10c in establishing normal acetylcholine receptor activity.
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Affiliation(s)
- Arthur A Nery
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CEP 05508-900, São Paulo, SP, Brazil
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Howard JF, Sanders DB. Chapter 12 Neurotoxicology of neuromuscular transmission. HANDBOOK OF CLINICAL NEUROLOGY 2008; 91:369-400. [DOI: 10.1016/s0072-9752(07)01512-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
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Abstract
The SELEX technique (systematic evolution of ligands by exponential enrichment) provides a powerful tool for the in vitro selection of nucleic acid ligands (aptamers) from combinatorial oligonucleotide libraries against a target molecule. In the beginning of the technique's use, RNA molecules were identified that bind to proteins that naturally interact with nucleic acids or to small organic molecules. In the following years, the use of the SELEX technique was extended to isolate oligonucleotide ligands (aptamers) for a wide range of proteins of importance for therapy and diagnostics, such as growth factors and cell surface antigens. These oligonucleotides bind their targets with similar affinities and specificities as antibodies do. The in vitro selection of oligonucleotides with enzymatic activity, denominated aptazymes, allows the direct transduction of molecular recognition to catalysis. Recently, the use of in vitro selection methods to isolate protein inhibitors has been extended to complex targets, such as membrane-bound receptors, and even entire cells. RNA aptamers have also been expressed in living cells. These aptamers, also called intramers, can be used to dissect intracellular signal transduction pathways. The utility of RNA aptamers for in vivo experiments, as well as for diagnostic and therapeutic purposes, is considerably enhanced by chemical modifications, such as substitutions of the 2'-OH groups of the ribose backbone in order to provide resistance against enzymatic degradation in biological fluids. In an alternative approach, Spiegelmers are identified through in vitro selection of an unmodified D-RNA molecule against a mirror-image (i.e. a D-peptide) of a selection target, followed by synthesis of the unnatural nuclease-resistant L-configuration of the RNA aptamer that recognizes the natural configuration of its selection target (i.e. a L-peptide). Recently, nuclease-resistant inhibitory RNA aptamers have been developed against a great variety of targets implicated in disease. Some results have already been obtained in animal models and in clinical trials.
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Affiliation(s)
- H Ulrich
- Department of Biochemistry, Instituto de Química, Universidade de São Paulo, Caixa Postal 26077, São Paulo 05513-970, Brazil.
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