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Costas-Ferreira C, Durán R, Faro LRF. Evaluation of the potential role of glutamatergic, cholinergic, and nitrergic systems in the dopamine release induced by the pesticide glyphosate in rat striatum. J Appl Toxicol 2024. [PMID: 38828527 DOI: 10.1002/jat.4651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 05/14/2024] [Accepted: 05/20/2024] [Indexed: 06/05/2024]
Abstract
Glyphosate (GLY) is a pesticide that severely alters nigrostriatal dopaminergic neurotransmission, inducing great increases in dopamine release from rat dorsal striatum. This GLY-induced striatal dopamine overflow occurs through mechanisms not yet fully understood, hence the interest in evaluating the role of other neurotransmitter systems in such effects. So, the main objective of this mechanistic study was to evaluate the possible mediation of the glutamatergic, cholinergic, and nitrergic systems in the GLY-induced in vivo dopamine release from rat dorsal striatum. The extracellular dopamine levels were measured by cerebral microdialysis and HPLC with electrochemical detection. Intrastriatal administration of GLY (5 mmol/L) significantly increased the dopamine release (1102%). Pretreatment with MK-801 (50 or 400 μmol/L), a non-competitive antagonist of NMDA receptors, significantly decreased the effect of GLY (by 70% and 74%, respectively), whereas AP-5 (400 μmol/L), a competitive antagonist of NMDA receptors, or CNQX (500 μmol/L), an AMPA/kainate receptor antagonist, had no significant effect. Administration of the nitric oxide synthase inhibitors, L-nitroarginine (L-NAME, 100 μmol/L) or 7-nitroindazole (7-NI, 100 μmol/L), also did not alter the effect of GLY on dopamine release. Finally, pretreatment of the animals with mecamylamine, an antagonist of nicotinic receptors, decreased the effect of GLY on dopamine release by 49%, whereas atropine, a muscarinic antagonist, had no significant effect. These results indicate that GLY-induced dopamine release largely depends on the activation of NMDA and nicotinic receptors in rat dorsal striatum. Future research is needed to determine the effects of this pesticide at environmentally relevant concentrations.
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Affiliation(s)
- Carmen Costas-Ferreira
- Department of Functional Biology and Health Sciences, Faculty of Biology, University of Vigo, Vigo, Spain
| | - Rafael Durán
- Department of Functional Biology and Health Sciences, Faculty of Biology, University of Vigo, Vigo, Spain
| | - Lilian R F Faro
- Department of Functional Biology and Health Sciences, Faculty of Biology, University of Vigo, Vigo, Spain
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2
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O’Brien BCV, Thao S, Weber L, Danielson HL, Boldt AD, Hueffer K, Weltzin MM. The human alpha7 nicotinic acetylcholine receptor is a host target for the rabies virus glycoprotein. Front Cell Infect Microbiol 2024; 14:1394713. [PMID: 38836054 PMCID: PMC11148329 DOI: 10.3389/fcimb.2024.1394713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2024] [Accepted: 04/29/2024] [Indexed: 06/06/2024] Open
Abstract
The rabies virus enters the nervous system by interacting with several molecular targets on host cells to modify behavior and trigger receptor-mediated endocytosis of the virion by poorly understood mechanisms. The rabies virus glycoprotein (RVG) interacts with the muscle acetylcholine receptor and the neuronal α4β2 subtype of the nicotinic acetylcholine receptor (nAChR) family by the putative neurotoxin-like motif. Given that the neurotoxin-like motif is highly homologous to the α7 nAChR subtype selective snake toxin α-bungarotoxin (αBTX), other nAChR subtypes are likely involved. The purpose of this study is to determine the activity of the RVG neurotoxin-like motif on nAChR subtypes that are expressed in brain regions involved in rabid animal behavior. nAChRs were expressed in Xenopus laevis oocytes, and two-electrode voltage clamp electrophysiology was used to collect concentration-response data to measure the functional effects. The RVG peptide preferentially and completely inhibits α7 nAChR ACh-induced currents by a competitive antagonist mechanism. Tested heteromeric nAChRs are also inhibited, but to a lesser extent than the α7 subtype. Residues of the RVG peptide with high sequence homology to αBTX and other neurotoxins were substituted with alanine. Altered RVG neurotoxin-like peptides showed that residues phenylalanine 192, arginine 196, and arginine 199 are important determinants of RVG peptide apparent potency on α7 nAChRs, while serine 195 is not. The evaluation of the rabies ectodomain reaffirmed the observations made with the RVG peptide, illustrating a significant inhibitory impact on α7 nAChR with potency in the nanomolar range. In a mammalian cell culture model of neurons, we confirm that the RVG peptide binds preferentially to cells expressing the α7 nAChR. Defining the activity of the RVG peptide on nAChRs expands our understanding of basic mechanisms in host-pathogen interactions that result in neurological disorders.
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Affiliation(s)
- Brittany C. V. O’Brien
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Shelly Thao
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Lahra Weber
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Helen L. Danielson
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Agatha D. Boldt
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Karsten Hueffer
- Department of Veterinary Medicine, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Maegan M. Weltzin
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, United States
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3
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Williams BM, Steed ND, Woolley JT, Moedl AA, Nelson CA, Jones GC, Burris MD, Arias HR, Kim OH, Jang EY, Hone AJ, McIntosh JM, Yorgason JT, Steffensen SC. Catharanthine Modulates Mesolimbic Dopamine Transmission and Nicotine Psychomotor Effects via Inhibition of α6-Nicotinic Receptors and Dopamine Transporters. ACS Chem Neurosci 2024; 15:1738-1754. [PMID: 38613458 DOI: 10.1021/acschemneuro.3c00478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2024] Open
Abstract
Iboga alkaloids, also known as coronaridine congeners, have shown promise in the treatment of alcohol and opioid use disorders. The objective of this study was to evaluate the effects of catharanthine and 18-methoxycoronaridine (18-MC) on dopamine (DA) transmission and cholinergic interneurons in the mesolimbic DA system, nicotine-induced locomotor activity, and nicotine-taking behavior. Utilizing ex vivo fast-scan cyclic voltammetry (FSCV) in the nucleus accumbens core of male mice, we found that catharanthine or 18-MC differentially inhibited evoked DA release. Catharanthine inhibition of evoked DA release was significantly reduced by both α4 and α6 nicotinic acetylcholine receptors (nAChRs) antagonists. Additionally, catharanthine substantially increased DA release more than vehicle during high-frequency stimulation, although less potently than an α4 nAChR antagonist, which confirms previous work with nAChR antagonists. Interestingly, while catharanthine slowed DA reuptake measured via FSCV ex vivo, it also increased extracellular DA in striatal dialysate from anesthetized mice in vivo in a dose-dependent manner. Superfusion of catharanthine or 18-MC inhibited the firing rate of striatal cholinergic interneurons in a concentration dependent manner, which are known to potently modulate presynaptic DA release. Catharanthine or 18-MC suppressed acetylcholine currents in oocytes expressing recombinant rat α6/α3β2β3 or α6/α3β4 nAChRs. In behavioral experiments using male Sprague-Dawley rats, systemic administration of catharanthine or 18-MC blocked nicotine enhancement of locomotor activity. Importantly, catharanthine attenuated nicotine self-administration in a dose-dependent manner while having no effect on food reinforcement. Lastly, administration of catharanthine and nicotine together greatly increased head twitch responses, indicating a potential synergistic hallucinogenic effect. These findings demonstrate that catharanthine and 18-MC have similar, but not identical effects on striatal DA dynamics, striatal cholinergic interneuron activity and nicotine psychomotor effects.
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Affiliation(s)
- Benjamin M Williams
- Department of Psychology/Neuroscience, Brigham Young University, Provo, Utah 84602, United States
| | - Nathan D Steed
- Department of Psychology/Neuroscience, Brigham Young University, Provo, Utah 84602, United States
| | - Joel T Woolley
- Department of Psychology/Neuroscience, Brigham Young University, Provo, Utah 84602, United States
| | - Aubrey A Moedl
- Department of Psychology/Neuroscience, Brigham Young University, Provo, Utah 84602, United States
| | - Christina A Nelson
- Department of Psychology/Neuroscience, Brigham Young University, Provo, Utah 84602, United States
| | - Gavin C Jones
- Department of Psychology/Neuroscience, Brigham Young University, Provo, Utah 84602, United States
| | - Matthew D Burris
- Department of Psychology/Neuroscience, Brigham Young University, Provo, Utah 84602, United States
| | - Hugo R Arias
- Department of Pharmacology and Physiology, Oklahoma State University College of Osteopathic Medicine, Tahlequah, Oklahoma 74464, United States
| | - Oc-Hee Kim
- Department of Advanced Toxicology Research, Korea Institute of Toxicology, 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, Korea
| | - Eun Young Jang
- Department of Advanced Toxicology Research, Korea Institute of Toxicology, 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, Korea
| | - Arik J Hone
- George E. Wahlen Veterans Affairs Medical Center, and Departments of Psychiatry and Biology, University of Utah, Salt Lake City, Utah 84112, United States
| | - J Michael McIntosh
- George E. Wahlen Veterans Affairs Medical Center, and Departments of Psychiatry and Biology, University of Utah, Salt Lake City, Utah 84112, United States
| | - Jordan T Yorgason
- Department of Psychology/Neuroscience, Brigham Young University, Provo, Utah 84602, United States
| | - Scott C Steffensen
- Department of Psychology/Neuroscience, Brigham Young University, Provo, Utah 84602, United States
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4
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Nagori K, Pradhan M, Sharma M, Ajazuddin, Badwaik HR, Nakhate KT. Current Progress on Central Cholinergic Receptors as Therapeutic Targets for Alzheimer's Disease. Curr Alzheimer Res 2024; 21:50-68. [PMID: 38529600 DOI: 10.2174/0115672050306008240321034006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 02/22/2024] [Accepted: 02/26/2024] [Indexed: 03/27/2024]
Abstract
Acetylcholine (ACh) is ubiquitously present in the nervous system and has been involved in the regulation of various brain functions. By modulating synaptic transmission and promoting synaptic plasticity, particularly in the hippocampus and cortex, ACh plays a pivotal role in the regulation of learning and memory. These procognitive actions of ACh are mediated by the neuronal muscarinic and nicotinic cholinergic receptors. The impairment of cholinergic transmission leads to cognitive decline associated with aging and dementia. Therefore, the cholinergic system has been of prime focus when concerned with Alzheimer's disease (AD), the most common cause of dementia. In AD, the extensive destruction of cholinergic neurons occurs by amyloid-β plaques and tau protein-rich neurofibrillary tangles. Amyloid-β also blocks cholinergic receptors and obstructs neuronal signaling. This makes the central cholinergic system an important target for the development of drugs for AD. In fact, centrally acting cholinesterase inhibitors like donepezil and rivastigmine are approved for the treatment of AD, although the outcome is not satisfactory. Therefore, identification of specific subtypes of cholinergic receptors involved in the pathogenesis of AD is essential to develop future drugs. Also, the identification of endogenous rescue mechanisms to the cholinergic system can pave the way for new drug development. In this article, we discussed the neuroanatomy of the central cholinergic system. Further, various subtypes of muscarinic and nicotinic receptors involved in the cognition and pathophysiology of AD are described in detail. The article also reviewed primary neurotransmitters that regulate cognitive processes by modulating basal forebrain cholinergic projection neurons.
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Affiliation(s)
- Kushagra Nagori
- Department of Pharmaceutical Chemistry, Rungta College of Pharmaceutical Sciences and Research, Kurud Road, Kohka, Bhilai 490024, Chhattisgarh, India
| | - Madhulika Pradhan
- Department of Pharmaceutical Technology, Gracious College of Pharmacy, Abhanpur 493661, Chhattisgarh, India
| | - Mukesh Sharma
- Department of Pharmacognosy, Rungta College of Pharmaceutical Sciences and Research, Kurud Road, Kohka, Bhilai 490024, Chhattisgarh, India
| | - Ajazuddin
- Department of Pharmaceutics, Rungta College of Pharmaceutical Sciences and Research, Kurud Road, Kohka, Bhilai 490024, Chhattisgarh, India
| | - Hemant R Badwaik
- Department of Pharmaceutical Chemistry, Shri Shankaracharya Institute of Pharmaceutical Sciences and Research, Junwani, Bhilai 490020, Chhattisgarh, India
| | - Kartik T Nakhate
- Department of Pharmacology, Shri Vile Parle Kelavani Mandal's Institute of Pharmacy, Dhule 424001, Maharashtra, India
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5
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Pei S, Xu C, Tan Y, Wang M, Yu J, Zhangsun D, Zhu X, Luo S. Synthesis, Activity, and Application of Fluorescent Analogs of [D1G, Δ14Q]LvIC Targeting α6β4 Nicotinic Acetylcholine Receptor. Bioconjug Chem 2023; 34:2194-2204. [PMID: 37748043 DOI: 10.1021/acs.bioconjchem.3c00283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
α6β4* nicotinic acetylcholine receptor (nAChR) (* represents the possible presence of additional subunits) is mainly distributed in the central and peripheral nervous system and is associated with neurological diseases, such as neuropathic pain; however, the ability to explore its function and distribution is limited due to the lack of pharmacological tools. As one of the analogs of α-conotoxin (α-CTx) LvIC from Conus lividus, [D1G, Δ14Q]LvIC (Lv) selectively and potently blocks α6/α3β4 nAChR (α6/α3 represents a chimera). Here, we synthesized three fluorescent analogs of Lv by connecting fluorescent molecules 6-carboxytetramethylrhodamine succinimidyl ester (6-TAMRA-SE, R), Cy3 NHS ester (Cy3, C) and BODIPY-FL NHS ester (BDP, B) to the N-terminus of the peptide and obtained Lv-R, Lv-C, and Lv-B, respectively. The potency and selectivity of three fluorescent peptides were evaluated using two-electrode voltage-clamp recording on nAChR subtypes expressed in Xenopus laevis oocytes, and the potency and selectivity of Lv-B were almost maintained with the half-maximal inhibition (IC50) of 64 nM. Then, we explored the stability of Lv-B in artificial cerebrospinal fluid and stained rat brain slices with Lv-B. The results indicated that the stability of Lv-B was slightly improved compared to that of native Lv. Additionally, we detected the distribution of the α6β4* nAChR subtype in the cerebral cortex using green fluorescently labeled peptide and fluorescence microscopy. Our findings not only provide a visualized pharmacological tool for exploring the distribution of the α6β4* nAChR subtype in various situ tissues and organs but also extend the application of α-CTx [D1G, Δ14Q]LvIC to demonstrate the involvement of α6β4 nAChR function in pathophysiology and pharmacology.
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Affiliation(s)
- Shengrong Pei
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
| | - Chenxing Xu
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
| | - Yao Tan
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
| | - Meiting Wang
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
| | - Jinpeng Yu
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
| | - Dongting Zhangsun
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou 570228, China
| | - Xiaopeng Zhu
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
| | - Sulan Luo
- Guangxi Key Laboratory of Special Biomedicine; School of Medicine, Guangxi University, Nanning 530004, China
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou 570228, China
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6
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Christie LA, Brice NL, Rowland A, Dickson L, Anand R, Teall M, Doyle KJ, Narayana L, Mitchell C, Harvey JRM, Mulligan V, Dawson LA, Cragg SJ, Carlton M, Bürli RW. Discovery of CVN417, a Novel Brain-Penetrant α6-Containing Nicotinic Receptor Antagonist for the Modulation of Motor Dysfunction. J Med Chem 2023; 66:11718-11731. [PMID: 37651656 DOI: 10.1021/acs.jmedchem.3c00630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
Nicotinic acetylcholine receptor (nAChR) α6 subunit RNA expression is relatively restricted to midbrain regions and is located presynaptically on dopaminergic neurons projecting to the striatum. This subunit modulates dopamine neurotransmission and may have therapeutic potential in movement disorders. We aimed to develop potent and selective α6-containing nAChR antagonists to explore modulation of dopamine release and regulation of motor function in vivo. High-throughput screening (HTS) identified novel α6-containing nAChR antagonists and led to the development of CVN417. This molecule blocks α6-containing nAChR activity in recombinant cells and reduces firing frequency of noradrenergic neurons in the rodent locus coeruleus. CVN417 modulated phasic dopaminergic neurotransmission in an impulse-dependent manner. In a rodent model of resting tremor, CVN417 attenuated this behavioral phenotype. These data suggest that selective antagonism of α6-containing nAChR, with molecules such as CVN417, may have therapeutic utility in treating the movement dysfunctions observed in conditions such as Parkinson's disease.
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Affiliation(s)
- Louisa A Christie
- Cerevance Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
- Takeda Cambridge Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
| | - Nicola L Brice
- Cerevance Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
- Takeda Cambridge Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
| | - Anna Rowland
- Cerevance Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
- Takeda Cambridge Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
| | - Louise Dickson
- Cerevance Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
- Takeda Cambridge Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
| | - Rishi Anand
- Centre for Cellular and Molecular Neurobiology, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Martin Teall
- Cerevance Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
- Takeda Cambridge Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
| | - Kevin J Doyle
- Cerevance Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
| | - Lakshminarayana Narayana
- Aragen Lifesciences Limited, Plot #284A (part), Bommasandra-Jigani Link Road Industrial Area, Bengaluru 562106, India
| | - Christine Mitchell
- Takeda Cambridge Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
| | - Jenna R M Harvey
- Cerevance Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
- Takeda Cambridge Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
| | - Victoria Mulligan
- Cerevance Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
- Takeda Cambridge Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
| | - Lee A Dawson
- Cerevance Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
| | - Stephanie J Cragg
- Centre for Cellular and Molecular Neurobiology, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, United Kingdom
| | - Mark Carlton
- Cerevance Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
- Takeda Cambridge Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
| | - Roland W Bürli
- Cerevance Limited, 418 Cambridge Science Park, Cambridge CB4 0PZ, United Kingdom
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Liu X, Gao L, Peng Y, Fang Z, Wang J. PheSom: a term frequency-based method for measuring human phenotype similarity on the basis of MeSH vocabulary. Front Genet 2023; 14:1185790. [PMID: 37496714 PMCID: PMC10366691 DOI: 10.3389/fgene.2023.1185790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 06/21/2023] [Indexed: 07/28/2023] Open
Abstract
Background: Phenotype similarity calculation should be used to help improve drug repurposing. In this study, based on the MeSH terms describing the phenotypes deposited in OMIM, we proposed a method, namely, PheSom (Phenotype Similarity On MeSH), to measure the similarity between phenotypes. PheSom counted the number of overlapping MeSH terms between two phenotypes and then took the weight of every MeSH term within each phenotype into account according to the term frequency-inverse document frequency (FIDC). Phenotype-related genes were used for the evaluation of our method. Results: A 7,739 × 7,739 similarity score matrix was finally obtained and the number of phenotype pairs was dramatically decreased with the increase of similarity score. Besides, the overlapping rates of phenotype-related genes were remarkably increased with the increase of similarity score between phenotypes, which supports the reliability of our method. Conclusion: We anticipate our method can be applied to identifying novel therapeutic methods for complex diseases.
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Affiliation(s)
- Xinhua Liu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, Zhejiang, China
- School of Biomedical Engineering and Technology, Tianjin Medical University, Tianjin, China
| | - Ling Gao
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, Zhejiang, China
| | - Yonglin Peng
- Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zhonghai Fang
- School of Biomedical Engineering and Technology, Tianjin Medical University, Tianjin, China
| | - Ju Wang
- School of Biomedical Engineering and Technology, Tianjin Medical University, Tianjin, China
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8
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Dong J, Zhang P, Xie J, Xie T, Zhu X, Zhangsun D, Yu J, Luo S. Loop2 Size Modification Reveals Significant Impacts on the Potency of α-Conotoxin TxID. Mar Drugs 2023; 21:md21050286. [PMID: 37233480 DOI: 10.3390/md21050286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 04/27/2023] [Accepted: 04/29/2023] [Indexed: 05/27/2023] Open
Abstract
α4/6-conotoxin TxID, which was identified from Conus textile, simultaneously blocks rat (r) α3β4 and rα6/α3β4 nicotinic acetylcholine receptors (nAChRs) with IC50 values of 3.6 nM and 33.9 nM, respectively. In order to identify the effects of loop2 size on the potency of TxID, alanine (Ala) insertion and truncation mutants were designed and synthesized in this study. An electrophysiological assay was used to evaluate the activity of TxID and its loop2-modified mutants. The results showed that the inhibition of 4/7-subfamily mutants [+9A]TxID, [+10A]TxID, [+14A]TxID, and all the 4/5-subfamily mutants against rα3β4 and rα6/α3β4 nAChRs decreased. Overall, ala-insertion or truncation of the 9th, 10th, and 11th amino acid results in a loss of inhibition and the truncation of loop2 has more obvious impacts on its functions. Our findings have strengthened the understanding of α-conotoxin, provided guidance for further modifications, and offered a perspective for future studies on the molecular mechanism of the interaction between α-conotoxins and nAChRs.
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Affiliation(s)
- Jianying Dong
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Panpan Zhang
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Junjie Xie
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Ting Xie
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Xiaopeng Zhu
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China
| | - Jinpeng Yu
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Sulan Luo
- School of Medicine, Guangxi University, Nanning 530004, China
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou 570228, China
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9
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Kamens HM, Flarend G, Horton WJ. The role of nicotinic receptors in alcohol consumption. Pharmacol Res 2023; 190:106705. [PMID: 36813094 PMCID: PMC10083870 DOI: 10.1016/j.phrs.2023.106705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 02/14/2023] [Accepted: 02/19/2023] [Indexed: 02/22/2023]
Abstract
The use of alcohol causes significant morbidity and mortality across the globe. Alcohol use disorder (AUD) is defined by the excessive use of this drug despite a negative impact on the individual's life. While there are currently medications available to treat AUD, they have limited efficacy and several side effects. As such, it is essential to continue to look for novel therapeutics. One target for novel therapeutics is nicotinic acetylcholine receptors (nAChRs). Here we systematically review the literature on the involvement of nAChRs in alcohol consumption. Data from both genetic and pharmacology studies provide evidence that nAChRs modulate alcohol intake. Interestingly, pharmacological modulation of all nAChR subtypes examined can decrease alcohol consumption. The reviewed literature demonstrates that nAChRs should continue to be investigated as novel therapeutics for AUD.
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Affiliation(s)
- Helen M Kamens
- Department of Biobehavioral Health, The Pennsylvania State University, University Park, PA 16802, United States.
| | - Geneva Flarend
- Department of Biobehavioral Health, The Pennsylvania State University, University Park, PA 16802, United States
| | - William J Horton
- Department of Biobehavioral Health, The Pennsylvania State University, University Park, PA 16802, United States
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10
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Zhu X, Wang S, Kaas Q, Yu J, Wu Y, Harvey PJ, Zhangsun D, Craik DJ, Luo S. Discovery, Characterization, and Engineering of LvIC, an α4/4-Conotoxin That Selectively Blocks Rat α6/α3β4 Nicotinic Acetylcholine Receptors. J Med Chem 2023; 66:2020-2031. [PMID: 36682014 DOI: 10.1021/acs.jmedchem.2c01786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
α6β4 nicotinic acetylcholine receptors (nAChRs) are expressed in the central and peripheral nervous systems, but their functions are not fully understood, largely because of a lack of specific ligands. Here, we characterized a novel α-conotoxin, LvIC, and designed a series of analogues to probe structure-activity relationships at the α6β4 nAChR. The potency and selectivity of these conotoxins were tested using two-electrode voltage-clamp recording on nAChR subtypes expressed in Xenopus laevis oocytes. One of the analogues, [D1G,ΔQ14]LvIC, potently blocked α6/α3β4 nAChRs (α6/α3 is a chimera) with an IC50 of 19 nM, with minimal activity at other nAChR subtypes, including the structurally similar α6/α3β2β3 and α3β4 subtypes. Using NMR, molecular docking, and receptor mutation, structure-activity relationships of [D1G,ΔQ14]LvIC at the α6/α3β4 nAChR were defined. It is a potent and specific antagonist of α6β4 nAChRs that could potentially serve as a novel molecular probe to explore α6β4 nAChR-related neurophysiological and pharmacological functions.
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Affiliation(s)
- Xiaopeng Zhu
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Shuai Wang
- Center for Novel Target and Therapeutic Intervention, Institute of Life Sciences, Chongqing Medical University, Chongqing 400016, China
| | - Quentin Kaas
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane 4072, Queensland, Australia
| | - Jinpeng Yu
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Yong Wu
- School of Medicine, Guangxi University, Nanning 530004, China
| | - Peta J Harvey
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane 4072, Queensland, Australia
| | - Dongting Zhangsun
- School of Medicine, Guangxi University, Nanning 530004, China.,Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou 570228, China
| | - David J Craik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane 4072, Queensland, Australia
| | - Sulan Luo
- School of Medicine, Guangxi University, Nanning 530004, China.,Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou 570228, China
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11
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Huang Q, Chu X, Zhang H, Yu S, Zhang L, Zhang X, Yu R, Guo C, Dai Q. Discovery and Structural and Functional Characterization of a Novel A-Superfamily Conotoxin Targeting α9α10 Nicotinic Acetylcholine Receptor. ACS Chem Biol 2022; 17:2483-2494. [PMID: 36048451 DOI: 10.1021/acschembio.2c00315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels widely distributed in the central peripheral nervous system and muscles which participate in rapid synaptic transmission. The α9α10 nAChR is an acetylcholine receptor subtype and is involved in chronic pain. In the present study, a new A-superfamily conotoxin Bt14.12 cloned from Conus betulinus was found to selectively inhibit α9α10 nAChRs with an IC50 of 62.3 nM. Unlike α-conotoxins and other A-superfamily conotoxins, Bt14.12 contains a four Cys (C-C-C-C) framework with a unique disulfide bond connection "C1-C4, C2-C3". The structure-activity studies of Bt14.12 demonstrate that all amino acid residues contribute to its potency. Interestingly, mutation experiments show that the deletion of Asp2 or the addition of three Arg residues at the N-terminus of Bt14.12 significantly enhances its inhibitory activity (IC50 is 21.9 nM or 12.7 nM, respectively) by 2- or 4-fold compared to the wild-type Bt14.12. The NMR structure of Bt14.12 shows that it contains α-helix- and β-turn-like elements, and further computational modelings of the interaction between Bt14.12 and the α9α10 nAChR demonstrate that Bt14.12 possesses a distinctive mode of action and displays a different structure-activity relationship from known α9α10 nAChR targeting α-conotoxins. Our findings provide a novel conotoxin that potently targets α9α10 nAChRs and a new motif for designing potent inhibitors against α9α10 nAChRs.
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Affiliation(s)
- Qiuyuan Huang
- Beijing Institute of Biotechnology, Beijing 100071, China.,Life Sciences Institute of Guangxi Medical University, Nanning, Guangxi 530021, China
| | - Xin Chu
- Beijing Institute of Biotechnology, Beijing 100071, China.,Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Haoran Zhang
- Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Shuo Yu
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Longxiao Zhang
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Xuerong Zhang
- Life Sciences Institute of Guangxi Medical University, Nanning, Guangxi 530021, China
| | - Rilei Yu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Chenyun Guo
- Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Qiuyun Dai
- Beijing Institute of Biotechnology, Beijing 100071, China
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12
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Lian M, Hueffer K, Weltzin MM. Interactions between the rabies virus and nicotinic acetylcholine receptors: A potential role in rabies virus induced behavior modifications. Heliyon 2022; 8:e10434. [PMID: 36091963 PMCID: PMC9450143 DOI: 10.1016/j.heliyon.2022.e10434] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 04/06/2022] [Accepted: 08/19/2022] [Indexed: 11/15/2022] Open
Affiliation(s)
- Marianne Lian
- University of Alaska Fairbanks, Department of Veterinary Medicine, 2141 Koyukuk Drive, Fairbanks, AK, 99775, USA
- Inland Norway University of Applied Sciences, Department of Forestry and Wildlife Management, Koppang, NO-2480, Norway
| | - Karsten Hueffer
- University of Alaska Fairbanks, Department of Veterinary Medicine, 2141 Koyukuk Drive, Fairbanks, AK, 99775, USA
| | - Maegan M. Weltzin
- University of Alaska Fairbanks, Department of Chemistry and Biochemistry, 1930 Yukon Dr. Fairbanks, AK, 99775, USA
- Corresponding author.
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13
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Kato M, Kunisawa N, Shimizu S, Iha HA, Ohno Y. Mechanisms Underlying Dopaminergic Regulation of Nicotine-Induced Kinetic Tremor. Front Pharmacol 2022; 13:938175. [PMID: 35784764 PMCID: PMC9243423 DOI: 10.3389/fphar.2022.938175] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Accepted: 05/30/2022] [Indexed: 11/13/2022] Open
Abstract
Nicotine induces kinetic tremor, which resembles pharmacological features of essential tremors, via activating the inferior olive (IO) neurons. Since nicotine is known to enhance dopamine release by stimulating α4β2 and/or α6 nACh receptors, we examined the effects of various dopamine receptor ligands on nicotine-induced tremor to clarify the role of the dopaminergic system in modulating nicotine tremor. A tremorgenic dose of nicotine increased the dopamine level in the pons and medulla oblongata (P/MO), and the levels of dopamine metabolites in the hippocampus, P/MO, and striatum. Treatment of animals with the D1/5 agonist SKF-38393 inhibited the induction of nicotine tremor, whereas the D3 agonist PD-128,907 facilitated nicotine-induced tremor. The D2 agonist sumanirole showed no effect. In addition, nicotine tremor was significantly enhanced by the D1/5 antagonist SCH-23390 and inhibited by the D3 antagonist U-99194. Neither the D2 (L-741,626) nor D4 (L-745,870) antagonist affected the generation of nicotine tremor. Furthermore, microinjection of U-99194 into the cerebellum significantly inhibited nicotine-induced tremor, whereas its injection into IO or the striatum did not affect tremor generation. Although intrastriatal injection of SCH-23390 showed no effects, its injection into IO tended to enhance nicotine-induced tremor. The present study suggests that dopamine D3 and D1/5 receptors regulate the induction of nicotine tremor in an opposite way, D3 receptors facilitately and D1/5 receptors inhibitorily. In addition, the cerebellar D3 receptors may play an important role in modulating the induction of nicotine tremor mediated by the olivo-cerebellar system.
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14
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Sex- and Genotype-Dependent Nicotine-Induced Behaviors in Adolescent Rats with a Human Polymorphism (rs2304297) in the 3'-UTR of the CHRNA6 Gene. Int J Mol Sci 2022; 23:ijms23063145. [PMID: 35328565 PMCID: PMC8948824 DOI: 10.3390/ijms23063145] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/10/2022] [Accepted: 03/11/2022] [Indexed: 12/04/2022] Open
Abstract
In human adolescents, a single nucleotide polymorphism (SNP), rs2304297, in the 3′-UTR of the nicotinic receptor subunit gene, CHRNA6, has been associated with increased smoking. To study the effects of the human CHRNA6 3′-UTR SNP, our lab generated knock-in rodent lines with either C or G SNP alleles. The objective of this study was to determine if the CHRNA6 3′-UTR SNP is functional in the knock-in rat lines. We hypothesized that the human CHRNA6 3′-UTR SNP knock-in does not impact baseline but enhances nicotine-induced behaviors. For baseline behaviors, rats underwent food self-administration at escalating schedules of reinforcement followed by a locomotor assay and a series of anxiety tests (postnatal day (PN) 25-39). In separate cohorts, adolescent rats underwent 1- or 4-day nicotine pretreatment (2×, 30 μg/kg/0.1 mL, i.v.). After the last nicotine injection (PN 31), animals were assessed behaviorally in an open-field chamber, and brain tissue was collected. We show the human CHRNA6 3′-UTR SNP knock-in does not affect food reinforcement, locomotor activity, or anxiety. Further, 4-day, but not 1-day, nicotine exposure enhances locomotion and anxiolytic behavior in a genotype- and sex-specific manner. These findings demonstrate that the human CHRNA6 3′-UTR SNP is functional in our in vivo model.
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15
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Acquah FA, Paramel M, Kuta A, Hussaini SR, Wallace DR, Mooers BHM. Simulations of Promising Indolizidine- α6- β2 Nicotinic Acetylcholine Receptor Complexes. Int J Mol Sci 2021; 22:7934. [PMID: 34360698 PMCID: PMC8347036 DOI: 10.3390/ijms22157934] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 07/08/2021] [Accepted: 07/20/2021] [Indexed: 11/24/2022] Open
Abstract
Smoking-cessation drugs bind many off-target nicotinic acetylcholine receptors (nAChRs) and cause severe side effects if they are based on nicotine. New drugs that bind only those receptors, such as α6β2* nAChR, implicated in nicotine addiction would avoid the off-target binding. Indolizidine (-)-237D (IND (-)-237D), a bicyclic alkaloid, has been shown to block α6β2* containing nAChRs and functionally inhibit the nicotine-evoked dopamine release. To improve the affinity of indolizidine (-)-237D for α6β2*, we built a library of 2226 analogs. We screened virtually the library against a homology model of α6β2 nAChR that we derived from the recent crystal structure of α4β2 nAChR. We also screened the crystal structure of α4β2 nAChR as a control on specificity. We ranked the compounds based on their predicted free energy of binding. We selected the top eight compounds bound in their best pose and subjected the complexes to 100 ns molecular dynamics simulations to assess the stability of the complexes. All eight analogs formed stable complexes for the duration of the simulations. The results from this work highlight nine distinct analogs of IND (-)-237D with high affinity towards α6β2* nAChR. These leads can be synthesized and tested in in vitro and in vivo studies as lead candidates for drugs to treat nicotine addiction.
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Affiliation(s)
- Francis A. Acquah
- Department of Biochemistry and Molecular Biology, University of Oklahoma of Health Sciences Center, Oklahoma City, OK 73104, USA;
| | - Matthew Paramel
- Department of Chemistry and Biochemistry, The University of Tulsa, Tulsa, OK 74104, USA; (M.P.); (A.K.); (S.R.H.)
| | - Adama Kuta
- Department of Chemistry and Biochemistry, The University of Tulsa, Tulsa, OK 74104, USA; (M.P.); (A.K.); (S.R.H.)
| | - Syed R. Hussaini
- Department of Chemistry and Biochemistry, The University of Tulsa, Tulsa, OK 74104, USA; (M.P.); (A.K.); (S.R.H.)
| | - David R. Wallace
- Department of Pharmacology and Physiology, Oklahoma State University Center for Health Sciences, Tulsa, OK 74107, USA;
| | - Blaine H. M. Mooers
- Department of Biochemistry and Molecular Biology, University of Oklahoma of Health Sciences Center, Oklahoma City, OK 73104, USA;
- Peggy and Charles Stephenson Cancer Center, Oklahoma City, OK 73104, USA
- Laboratory of Biomolecular Structure and Function, University of Oklahoma of Health Sciences Center, Oklahoma City, OK 73104, USA
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16
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Ning H, Huang B, Tae HS, Liu Z, Yu S, Li L, Zhang L, Adams DJ, Guo C, Dai Q. α-Conotoxin Bt1.8 from Conus betulinus selectively inhibits α6/α3β2β3 and α3β2 nicotinic acetylcholine receptor subtypes. J Neurochem 2021; 159:90-100. [PMID: 34008858 DOI: 10.1111/jnc.15434] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 04/16/2021] [Accepted: 04/27/2021] [Indexed: 12/01/2022]
Abstract
α-Conotoxins are small disulfide-rich peptides found in the venom of marine cone snails and are potent antagonists of nicotinic acetylcholine receptors (nAChRs). They are valuable pharmacological tools and have potential therapeutic applications for the treatment of chronic pain or neurological diseases and disorders. In the present study, we synthesized and functionally characterized a novel α-conotoxin Bt1.8, which was cloned from Conus betulinus. Bt1.8 selectively inhibited ACh-evoked currents in Xenopus oocytes expressing rat(r) α6/α3β2β3 and rα3β2 nAChRs with an IC50 of 2.1 nM and 9.4 nM, respectively, and similar potency for human (h) α6/α3β2β3 and hα3β2 nAChRs. Additionally, Bt1.8 had higher binding affinity with a slower dissociation rate for the rα6/α3β2β3 subtype compared to rα3β2. The amino acid sequence of Bt1.8 is significantly different from other reported α-conotoxins targeting the two nAChR subtypes. Further Alanine scanning analyses demonstrated that residues Ile9, Leu10, Asn11, Asn12 and Asn14 are critical for its inhibitory activity at the α6/α3β2β3 and α3β2 subtypes. Moreover, the NMR structure of Bt1.8 indicated the presence of a relatively larger hydrophobic zone than other α4/7-conotoxins which may explain its potent inhibition at α6/α3β2β3 nAChRs.
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Affiliation(s)
- Huying Ning
- Beijing Institute of Biotechnology, Beijing, China
| | - Biling Huang
- Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Han-Shen Tae
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Zhuguo Liu
- Beijing Institute of Biotechnology, Beijing, China
| | - Shuo Yu
- Beijing Institute of Biotechnology, Beijing, China
| | - Liang Li
- Beijing Institute of Biotechnology, Beijing, China
| | | | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Chenyun Guo
- Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China
| | - Qiuyun Dai
- Beijing Institute of Biotechnology, Beijing, China
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17
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Sherafat Y, Bautista M, Fowler CD. Multidimensional Intersection of Nicotine, Gene Expression, and Behavior. Front Behav Neurosci 2021; 15:649129. [PMID: 33828466 PMCID: PMC8019722 DOI: 10.3389/fnbeh.2021.649129] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Accepted: 02/24/2021] [Indexed: 12/16/2022] Open
Abstract
The cholinergic system plays a crucial role in nervous system function with important effects on developmental processes, cognition, attention, motivation, reward, learning, and memory. Nicotine, the reinforcing component of tobacco and e-cigarettes, directly acts on the cholinergic system by targeting nicotinic acetylcholine receptors (nAChRs) in the brain. Activation of nAChRs leads to a multitude of immediate and long-lasting effects in specific cellular populations, thereby affecting the addictive properties of the drug. In addition to the direct actions of nicotine in binding to and opening nAChRs, the subsequent activation of circuits and downstream signaling cascades leads to a wide range of changes in gene expression, which can subsequently alter further behavioral expression. In this review, we provide an overview of the actions of nicotine that lead to changes in gene expression and further highlight evidence supporting how these changes can often be bidirectional, thereby inducing subsequent changes in behaviors associated with further drug intake.
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Affiliation(s)
- Yasmine Sherafat
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, Unites States
| | - Malia Bautista
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, Unites States
| | - Christie D Fowler
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, Unites States
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18
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Nourse JB, Harshefi G, Marom A, Karmi A, Cohen Ben-Ami H, Caldwell KA, Caldwell GA, Treinin M. Conserved nicotine-activated neuroprotective pathways involve mitochondrial stress. iScience 2021; 24:102140. [PMID: 33665559 PMCID: PMC7900352 DOI: 10.1016/j.isci.2021.102140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 01/03/2021] [Accepted: 01/29/2021] [Indexed: 12/14/2022] Open
Abstract
Tobacco smoking is a risk factor for several human diseases. Conversely, smoking also reduces the prevalence of Parkinson's disease, whose hallmark is degeneration of substantia nigra dopaminergic neurons (DNs). We use C. elegans as a model to investigate whether tobacco-derived nicotine activates nicotinic acetylcholine receptors (nAChRs) to selectively protect DNs. Using this model, we demonstrate conserved functions of DN-expressed nAChRs. We find that DOP-2, a D3-receptor homolog; MCU-1, a mitochondrial calcium uniporter; PINK-1 (PTEN-induced kinase 1); and PDR-1 (Parkin) are required for nicotine-mediated protection of DNs. Together, our results support involvement of a calcium-modulated, mitochondrial stress-activated PINK1/Parkin-dependent pathway in nicotine-induced neuroprotection. This suggests that nicotine-selective protection of substantia nigra DNs is due to the confluence of two factors: first, their unique vulnerability to mitochondrial stress, which is mitigated by increased mitochondrial quality control due to PINK1 activation, and second, their specific expression of D3-receptors.
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Affiliation(s)
- J Brucker Nourse
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, 35487 AL, USA
| | - Gilad Harshefi
- Department of Medical Neurobiology, Hebrew University - Hadassah Medical School, Jerusalem 91120, Israel
| | - Adi Marom
- Department of Medical Neurobiology, Hebrew University - Hadassah Medical School, Jerusalem 91120, Israel
| | - Abdelrahaman Karmi
- Department of Medical Neurobiology, Hebrew University - Hadassah Medical School, Jerusalem 91120, Israel
| | - Hagit Cohen Ben-Ami
- Department of Medical Neurobiology, Hebrew University - Hadassah Medical School, Jerusalem 91120, Israel
| | - Kim A Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, 35487 AL, USA.,Departments of Neurology and Neurobiology, Center for Neurodegeneration and Experimental Therapeutics, Nathan Shock Center of Excellence in the Basic Biology of Aging, University of Alabama at Birmingham School of Medicine, Birmingham, 35294 AL, USA
| | - Guy A Caldwell
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, 35487 AL, USA.,Departments of Neurology and Neurobiology, Center for Neurodegeneration and Experimental Therapeutics, Nathan Shock Center of Excellence in the Basic Biology of Aging, University of Alabama at Birmingham School of Medicine, Birmingham, 35294 AL, USA
| | - Millet Treinin
- Department of Medical Neurobiology, Hebrew University - Hadassah Medical School, Jerusalem 91120, Israel
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19
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Characterization of AN317, a novel selective agonist of α6β2-containing nicotinic acetylcholine receptors. Biochem Pharmacol 2020; 174:113786. [DOI: 10.1016/j.bcp.2019.113786] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 12/23/2019] [Indexed: 11/23/2022]
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20
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Li X, Wang S, Zhu X, Zhangsun D, Wu Y, Luo S. Effects of Cyclization on Activity and Stability of α-Conotoxin TxIB. Mar Drugs 2020; 18:E180. [PMID: 32235388 PMCID: PMC7230940 DOI: 10.3390/md18040180] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 03/25/2020] [Accepted: 03/25/2020] [Indexed: 11/17/2022] Open
Abstract
α-Conotoxin TxIB specifically blocked α6/α3β2β3 acetylcholine receptors (nAChRs), and it could be a potential probe for studying addiction and other diseases related to α6/α3β2β3 nAChRs. However, as a peptide, TxIB may suffer from low stability, short half-life, and poor bioavailability. In this study, cyclization of TxIB was used to improve its stability. Four cyclic mutants of TxIB (cTxIB) were synthesized, and the inhibition of these analogues on α6/α3β2β3 nAChRs as well as their stability in human serum were measured. All cyclized analogues had similar activity compared to wild-type TxIB, which indicated that backbone cyclization of TxIB had no significant effect on its activity. Cyclization of TxIB with a seven-residue linker improved its stability significantly in human serum. Besides this, the results showed that cyclization maintained the activity of α-conotoxin TxIB, which is conducive to its future application.
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Affiliation(s)
- Xincan Li
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China; (X.L.); (S.W.); (X.Z.); (D.Z.)
| | - Shuai Wang
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China; (X.L.); (S.W.); (X.Z.); (D.Z.)
| | - Xiaopeng Zhu
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China; (X.L.); (S.W.); (X.Z.); (D.Z.)
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China; (X.L.); (S.W.); (X.Z.); (D.Z.)
- Medical School, Guangxi University, Nanning 530004, China
| | - Yong Wu
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China; (X.L.); (S.W.); (X.Z.); (D.Z.)
- Medical School, Guangxi University, Nanning 530004, China
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Key Laboratory for Marine Drugs of Haikou, School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228, China; (X.L.); (S.W.); (X.Z.); (D.Z.)
- Medical School, Guangxi University, Nanning 530004, China
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21
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Cardenas A, Elabd M, Lotfipour S. Specificity of a rodent alpha(α)6 nicotinic acetylcholine receptor subunit antibody. Psychopharmacology (Berl) 2020; 237:283-285. [PMID: 31786649 PMCID: PMC6954311 DOI: 10.1007/s00213-019-05413-x] [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: 08/20/2019] [Accepted: 11/21/2019] [Indexed: 10/25/2022]
Abstract
Alpha(α)6-containing nicotinic acetylcholine receptors (nAChRs) have been implicated in nicotine reward and reinforcement. To date, a commercially available, validated α6 nAChR subunit antibody has not been reported. To evaluate a commercially available neuronal α6 nAChR subunit antibody we performed quantitative western blots on protein from the ventral tegmental area of wild type Sprague Dawley rats. As a first approach to determine the specificity of the antibody, we used a control antigen to block the α6 antibody from binding. Next, we tested the antibody in brain tissue of wild type and α6 knockout (KO) C57BL/6J mice. The α6 antibody was present at a higher than expected molecular weight (63 versus 57 kDa) and the control antigen blocked the α6 antibody, suggesting specificity. However, when we genetically validated the antibody, bands were present in both α6 KO mice and C57BL/6J samples. Taken together, our study highlights the necessity to genetically validate antibodies when possible and we report that a commercially available α6 nAChR subunit antibody is non-specific.
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Affiliation(s)
- Anjelica Cardenas
- Department of Pharmacuetical Sciences, College of Health Sciences, University of California, Irvine, Irvine CA, USA
| | - Mina Elabd
- Biological Sciences, University of California, Irvine, Irvine CA, USA
| | - Shahrdad Lotfipour
- Department of Pharmacuetical Sciences, College of Health Sciences, University of California Irvine, Irvine, CA, USA. .,Department of Emergency Medicine, School of Medicine, University of California Irvine, Irvine, CA, 92697-4625, USA.
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22
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van Hout M, Klein J, Ahring PK, Brown DT, Thaneshwaran S, Dos Santos AB, Jensen AA, Kohlmeier KA, Christophersen P, Dyhring T. Characterization of AN6001, a positive allosteric modulator of α6β2-containing nicotinic acetylcholine receptors. Biochem Pharmacol 2019; 174:113788. [PMID: 31887290 DOI: 10.1016/j.bcp.2019.113788] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 12/23/2019] [Indexed: 01/23/2023]
Abstract
α6β2-Containing nicotinic acetylcholine receptors (α6β2* nAChRs) are predominantly expressed in midbrain dopaminergic neurons, including substantia nigra pars compacta (SNc) neurons and their projections to striatal regions, where they regulate dopamine release and nigrostriatal activity. It is well established that nAChR agonists exert protection against dopaminergic neurotoxicity in cellular assays and parkinsonian animal models. Historically, drug development in the nAChR field has been mostly focused on development of selective agonists and positive allosteric modulators (PAMs) for the predominant neuronal nAChRs, α7 and α4β2. Here, we report the discovery and characterization of AN6001, a novel selective α6β2* nAChR PAM. AN6001 mediated increases in both nicotine potency and efficacy at the human α6/α3β2β3V9'S nAChR in HEK293 cells, and it positively modulated ACh-evoked currents through both α6/α3β2β3V9'S and a concatenated β3-α6-β2-α6-β2 receptor in Xenopus oocytes, displaying EC50 values of 0.58 µM and 0.40 µM, respectively. In contrast, the compound did not display significant modulatory activity at α4β2, α3β4, α7 and muscle nAChRs. AN6001 also increased agonist-induced dopamine release from striatal synaptosomes and augmented agonist-induced global cellular responses and inward currents in dopaminergic neurons in SNc slices (measured by Ca2+ imaging and patch clamp recordings, respectively). Finally, AN6001 potentiated the neuroprotective effect of nicotine at MPP+-treated primary dopaminergic neurons. Overall, our studies demonstrate the existence of allosteric sites on α6β2* nAChRs and that positive modulation of native α6β2* receptors strengthens DA signaling. Hence, AN6001 represents an important tool for studies of α6β2* nAChRs and furthermore underlines the therapeutic potential in these receptors in Parkinson's disease.
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Affiliation(s)
- Marloes van Hout
- Saniona A/S, Ballerup, Denmark; Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | | | - Philip K Ahring
- Saniona A/S, Ballerup, Denmark; School of Pharmacy, Brain and Mind Centre, The University of Sydney, Sydney, Australia
| | | | - Siganya Thaneshwaran
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Altair B Dos Santos
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Kristi A Kohlmeier
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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α-Conotoxin TxIB: A Uniquely Selective Ligand for α6/α3β2β3 Nicotinic Acetylcholine Receptor Attenuates Nicotine-Induced Conditioned Place Preference in Mice. Mar Drugs 2019; 17:md17090490. [PMID: 31443523 PMCID: PMC6780885 DOI: 10.3390/md17090490] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Revised: 08/17/2019] [Accepted: 08/20/2019] [Indexed: 11/17/2022] Open
Abstract
α-Conotoxin TxIB is a specific antagonist of α6/α3β2β3(α6β2*) nicotinic acetylcholine receptor (nAChR) with an IC50 of 28 nM. Previous studies have shown that α6β2* nAChRs are abundantly expressed in midbrain dopaminergic neurons and play an important role in mediating the mechanism of nicotine and other drugs reward effect. It provided important targets for the development of anti-addiction drugs. The present study evaluated the pharmacological activity of TxIB in vivo with conditioned place preference (CPP) model, which were induced by subcutaneous injection (s.c.) of nicotine (NIC, 0.5 mg/kg). α-Conotoxin TxIB inhibited the expression and reinstatement of CPP in mice dose-dependently, but had no significant effect on locomotor activity. The concentrations of dopamine (DA), γ-aminobutyric acid (GABA) and noradrenaline (NE) in different brain regions were measured by enzyme-linked immunosorbent assay (ELISA). We found that TxIB could inhibit the concentrations of DA, GABA and NE in different brain regions (such as nucleus accumbens (NAc), hippocampus (HIP) and prefrontal cortex (PFC)) in NIC-induced mice. The concentrations of DA and NE were decreased in ventral tegmental area (VTA), while GABA had little change. The current work described the inhibition activity of TxIB in NIC-induced CPP, suggesting that α6β2* nAChR-targeted compound may be a promising drug for nicotine addiction treatment.
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24
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van Hout M, Valdes A, Christensen SB, Tran PT, Watkins M, Gajewiak J, Jensen AA, Olivera BM, McIntosh JM. α-Conotoxin VnIB from Conus ventricosus is a potent and selective antagonist of α6β4* nicotinic acetylcholine receptors. Neuropharmacology 2019; 157:107691. [PMID: 31255696 DOI: 10.1016/j.neuropharm.2019.107691] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/05/2019] [Accepted: 06/26/2019] [Indexed: 01/20/2023]
Abstract
α6-containing (α6*) nicotinic acetylcholine receptors (nAChRs) are expressed throughout the periphery and the central nervous system and constitute putative therapeutic targets in pain, addiction and movement disorders. The α6β2* nAChRs are relatively well studied, in part due to the availability of target specific α-conotoxins (α-Ctxs). In contrast, all native α-Ctxs identified that potently block α6β4 nAChRs exhibit higher potencies for the closely related α6β2β3 and/or α3β4 subtypes. In this study, we have identified a novel peptide from Conus ventricosus with pronounced selectivity for the α6β4 nAChR. The peptide-encoding gene was cloned from genomic DNA and the predicted mature peptide, α-Ctx VnIB, was synthesized. The functional properties of VnIB were characterized at rat and human nAChRs expressed in Xenopus oocytes by two-electrode voltage clamp electrophysiology. VnIB potently inhibited ACh-evoked currents at rα6β4 and rα6/α3β4 nAChRs, displayed ∼20-fold and ∼250-fold lower potencies at rα3β4 and rα6/α3β2β3 receptors, respectively, and exhibited negligible effects at eight other nAChR subtypes. Interestingly, even higher degrees of selectivity were observed for hα6/α3β4 over hα6/α3β2β3 and hα3β4 receptors. Finally, VnIB displayed fast binding kinetics at rα6/α3β4 (on-rate t½ = 0.87 min-1, off-rate t½ = 2.7 min-1). The overall preference of VnIB for β4* over β2* nAChRs is similar to the selectivity profiles of other 4/6 α-Ctxs. However, in contrast to previously identified native α-Ctxs targeting α6* nAChRs, VnIB displays pronounced selectivity for α6β4 nAChRs over both α3β4 and α6β2β3 receptors. VnIB thus represents a novel molecular probe for elucidating the physiological role and therapeutic properties of α6β4* nAChRs.
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Affiliation(s)
- Marloes van Hout
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Amanda Valdes
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA
| | - Sean B Christensen
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA.
| | - Phuong T Tran
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA
| | - Maren Watkins
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA; Department of Pathology, University of Utah, Salt Lake City, UT, 84112, USA.
| | - Joanna Gajewiak
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA.
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | | | - J Michael McIntosh
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA; Department of Psychiatry, University of Utah, Salt Lake City, UT, 84108, USA; George E. Wahlen Veterans Affair Medical Center, Salt Lake City, UT, 84148, USA.
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25
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Huang C, Zhang Z, Cui W. Marine-Derived Natural Compounds for the Treatment of Parkinson's Disease. Mar Drugs 2019; 17:md17040221. [PMID: 30978965 PMCID: PMC6520879 DOI: 10.3390/md17040221] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 03/23/2019] [Accepted: 04/05/2019] [Indexed: 12/29/2022] Open
Abstract
Parkinson’s disease (PD) is a neurodegenerative disorder caused by the loss of dopaminergic neurons, leading to the motor dysfunctions of patients. Although the etiology of PD is still unclear, the death of dopaminergic neurons during PD progress was revealed to be associated with the abnormal aggregation of α-synuclein, the elevation of oxidative stress, the dysfunction of mitochondrial functions, and the increase of neuroinflammation. However, current anti-PD therapies could only produce symptom-relieving effects, because they could not provide neuroprotective effects, stop or delay the degeneration of dopaminergic neurons. Marine-derived natural compounds, with their novel chemical structures and unique biological activities, may provide anti-PD neuroprotective effects. In this study, we have summarized anti-PD marine-derived natural products which have shown pharmacological activities by acting on various PD targets, such as α-synuclein, monoamine oxidase B, and reactive oxygen species. Moreover, marine-derived natural compounds currently evaluated in the clinical trials for the treatment of PD are also discussed.
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Affiliation(s)
- Chunhui Huang
- Ningbo Key Laboratory of Behavioral Neuroscience, Zhejiang Provincial Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, Ningbo 315211, China.
- Laboratory of Marine Natural Products, School of Marine Sciences, Ningbo University, Ningbo 315211, China.
| | - Zaijun Zhang
- Institute of New Drug Research, Guangdong Province Key Laboratory of Pharmacodynamic, Constituents of Traditional Chinese Medicine and New Drug Research, College of Pharmacy, Jinan University, Guangzhou 510632, China.
| | - Wei Cui
- Ningbo Key Laboratory of Behavioral Neuroscience, Zhejiang Provincial Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, Ningbo 315211, China.
- Laboratory of Marine Natural Products, School of Marine Sciences, Ningbo University, Ningbo 315211, China.
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26
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Gu S, Matta JA, Davini WB, Dawe GB, Lord B, Bredt DS. α6-Containing Nicotinic Acetylcholine Receptor Reconstitution Involves Mechanistically Distinct Accessory Components. Cell Rep 2019; 26:866-874.e3. [PMID: 30673609 DOI: 10.1016/j.celrep.2018.12.103] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/26/2018] [Accepted: 12/21/2018] [Indexed: 01/29/2023] Open
Abstract
Acetylcholine gates a large family of nicotinic receptor cation channels that control neuronal excitation and neurotransmitter release. These receptors are key targets for neuropsychiatric disorders; however, difficulties in expressing nicotinic acetylcholine (nACh) receptors hamper elaboration of their pharmacology and obscure elucidation of their biological functions. Particularly intriguing are α6-containing nACh receptors, which mediate nicotine-induced dopamine release in striatum-nucleus accumbens. Using genome-wide cDNA screening, we identify three accessory proteins, β-anchoring and -regulatory protein (BARP), lysosomal-associated membrane protein 5 (LAMP5), and SULT2B1, that complement the nACh receptor chaperone NACHO to reconstitute α6β2β3 channel function. Whereas NACHO mediates α6β2β3 assembly, BARP primarily enhances channel gating and LAMP5 and SULT2B1 promote receptor surface trafficking. BARP knockout mice show perturbations in presynaptic striatal nACh receptors that are consistent with BARP modulation of receptor desensitization. These studies unravel the molecular complexity of α6β2β3 biogenesis and enable physiological studies of this crucial neuropharmacological target.
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Affiliation(s)
- Shenyan Gu
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson & Johnson, 3210 Merryfield Row, San Diego, CA 92121, USA
| | - Jose A Matta
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson & Johnson, 3210 Merryfield Row, San Diego, CA 92121, USA
| | - Weston B Davini
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson & Johnson, 3210 Merryfield Row, San Diego, CA 92121, USA
| | - G Brent Dawe
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson & Johnson, 3210 Merryfield Row, San Diego, CA 92121, USA
| | - Brian Lord
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson & Johnson, 3210 Merryfield Row, San Diego, CA 92121, USA
| | - David S Bredt
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson & Johnson, 3210 Merryfield Row, San Diego, CA 92121, USA.
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27
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Chang M, Kawai HD. A characterization of laminar architecture in mouse primary auditory cortex. Brain Struct Funct 2018; 223:4187-4209. [PMID: 30187193 DOI: 10.1007/s00429-018-1744-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 08/29/2018] [Indexed: 12/19/2022]
Abstract
Laminar architecture of primary auditory cortex (A1) has long been investigated by traditional histochemical techniques such as Nissl staining, retrograde and anterograde tracings. Uncertainty still remains, however, about laminar boundaries in mice. Here we investigated the cortical lamina structure by combining neuronal tracing and immunofluorochemistry for laminar specific markers. Most retrogradely labeled corticothalamic neurons expressed Forkhead box protein P2 (Foxp2) and distributed within the laminar band of Foxp2-expressing cells, identifying layer 6. Cut-like homeobox 1 (Cux1) expression in layer 2-4 neurons divided the upper layers into low expression layers 2/3 and high expression layers 3/4, which overlapped with the dense terminals of vesicular glutamate transporter 2 (vGluT2) and anterogradely labeled lemniscal thalamocortical axons. In layer 5, between Cux1-expressing layers 2-4 and Foxp2-defined layer 6, retrogradely labeled corticocollicular projection neurons mostly expressed COUP-TF interacting protein 2 (Ctip2). Ctip2-expressing neurons formed a laminar band in the middle of layer 5 distant from layer 6, creating a laminar gap between the two laminas. This gap contained a high population of commissural neurons projecting to contralateral A1 compared to other layers and received vGluT2-immunopositive, presumptive thalamocortical axon collateral inputs. Our study shows that layer 5 is much wider than layer 6, and layer 5 can be divided into at least three sublayers. The thalamorecipient layers 3/4 may be separated from layers 2/3 using Cux1 and can be also divided into layer 4 and layer 3 based on the neuronal soma size. These data provide a new insight for the laminar structure of mouse A1.
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Affiliation(s)
- Minzi Chang
- Department of Bioinformatics, Graduate School of Engineering, Soka University, Hachioji, Tokyo, 192-8577, Japan
| | - Hideki Derek Kawai
- Department of Bioinformatics, Graduate School of Engineering, Soka University, Hachioji, Tokyo, 192-8577, Japan. .,Department of Science and Engineering for Sustainable Innovation, Faculty of Science and Engineering, Soka University, Hachioji, Tokyo, 192-8577, Japan.
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28
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Rollema H, Hurst RS. The contribution of agonist and antagonist activities of α4β2* nAChR ligands to smoking cessation efficacy: a quantitative analysis of literature data. Psychopharmacology (Berl) 2018; 235:2479-2505. [PMID: 29980822 DOI: 10.1007/s00213-018-4921-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Accepted: 04/29/2018] [Indexed: 12/14/2022]
Abstract
RATIONALE AND OBJECTIVE Two mechanisms underlie smoking cessation efficacies of α4β2* nicotinic acetylcholine receptor (nAChR) agonists: a "nicotine-like" agonist activity reduces craving by substituting for nicotine during a quit attempt, and a "nicotine-blocking" antagonist activity attenuates reinforcement by competing with inhaled nicotine during a relapse. To evaluate the contribution of each mechanism to clinical efficacy, we estimated the degree of agonist and antagonist activities of nicotine replacement therapy (NRT), varenicline, cytisine, and the discontinued nAChR agonists dianicline, ABT-418, ABT-089, CP-601927, and CP-601932, relative to the functional effects of nicotine from smoking. METHODS Functional activities that occur in vivo with clinical doses were predicted from literature data on binding and functional potencies at the target α4β2 nAChR, as well as at α6β2* nAChRs, and from estimates of free drug exposures in human brain. Agonist activity is comprised of nAChR activation and desensitization, which were expressed as percentages of desensitization and activation by nicotine from smoking. Antagonist activity was expressed as the reduction in nAChR occupancy by nicotine during smoking in the presence of an agonist. RESULTS Comparisons with odds ratios at end of treatment suggest that extensive α4β2 and α6β2* nAChR desensitization combined with α6β2* nAChR activation at similar levels as nicotine from smoking is associated with clinical efficacy (NRT, varenicline, cytisine, ABT-418). Effective competition with inhaled nicotine for α4β2 and α6β2* nAChRs further improves clinical efficacy (varenicline). Other discontinued nAChR agonists have lower agonist and antagonist activities at α4β2 nAChRs and are inactive or less efficacious than NRT (dianicline, ABT-089, CP-601927, CP-601932). CONCLUSION Three pharmacological effects appear to be key factors underlying smoking cessation efficacy: the degree of activation of α6β2* nAChRs, desensitization of α4β2 and α6β2* nAChRs (agonist activity), and the reduction of nicotine occupancy at α4β2 and α6β2* nAChRs (antagonist activity). No single activity is dominant, and the level of smoking cessation efficacy depends on the profile of these activities achieved at clinical doses. While adequate agonist activity alone seems sufficient for a clinical effect (e.g., NRT, cytisine), clinical efficacy is improved with substantial competitive antagonism of α4β2 nAChRs, i.e., if the drug has a dual agonist-antagonist mechanism of action (e.g., varenicline).
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Affiliation(s)
- Hans Rollema
- Rollema Biomedical Consulting, 20 Holdridge Court, Mystic, CT, 06355, USA.
| | - Raymond S Hurst
- Hurst Neuropharmacology Consulting, 30 Brook Trail Road, Wayland, MA, 01778, USA
- Concert Pharmaceuticals, Inc., 99 Hayden Avenue, Suite 500, Lexington, MA, 02421, USA
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29
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Collo G, Cavalleri L, Zoli M, Maskos U, Ratti E, Merlo Pich E. Alpha6-Containing Nicotinic Acetylcholine Receptors Mediate Nicotine-Induced Structural Plasticity in Mouse and Human iPSC-Derived Dopaminergic Neurons. Front Pharmacol 2018; 9:572. [PMID: 29910731 PMCID: PMC5992464 DOI: 10.3389/fphar.2018.00572] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 05/14/2018] [Indexed: 12/23/2022] Open
Abstract
Midbrain dopamine (DA) neurons are considered a critical substrate for the reinforcing and sensitizing effects of nicotine and tobacco dependence. While the role of the α4 and β2 subunit containing nicotinic acetylcholine receptors (α4β2∗nAChRs) in mediating nicotine effects on DA release and DA neuron activity has been widely explored, less information is available on their role in the morphological adaptation of the DA system to nicotine, eventually leading to dysfunctional behaviors observed in nicotine dependence. In particular, no information is available on the role of α6∗nAChRs in nicotine-induced structural plasticity in rodents and no direct evidence exists regarding the occurrence of structural plasticity in human DA neurons exposed to nicotine. To approach this problem, we used two parallel in vitro systems, mouse primary DA neuron cultures from E12.5 embryos and human DA neurons differentiated from induced pluripotent stem cells (iPSCs) of healthy donors, identified using TH+ immunoreactivity. In both systems, nicotine 1–10 μM produced a dose-dependent increase of maximal dendrite length, number of primary dendrites, and soma size when measured after 3 days in culture. These effects were blocked by pretreatments with the α6∗nAChR antagonists α-conotoxin MII and α-conotoxin PIA, as well as by the α4β2nAChR antagonist dihydro-β-erythroidine (DHβE) in both mouse and human DA neurons. Nicotine was also ineffective when the primary DA neurons were obtained from null mutant mice for either the α6 subunit or both the α4 and α6 subunits of nAChR. When pregnant mice were exposed to nicotine from gestational day 15, structural plasticity was also observed in the midbrain DA neurons of postnatal day 1 offspring only in wild-type mice and not in both null mutant mice. This study confirmed the critical role of α4α6∗nAChRs in mediating nicotine-induced structural plasticity in both mouse and human DA neurons, supporting the translational relevance of neurons differentiated from human iPSCs for pharmacological studies.
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Affiliation(s)
- Ginetta Collo
- Section of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Laura Cavalleri
- Section of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Michele Zoli
- Department of Biomedical, Metabolic and Neural Sciences, Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, Modena, Italy
| | - Uwe Maskos
- Unité de Neurobiologie Intégrative des Systèmes Cholinergiques, CNRS UMR 3571, Institut Pasteur, Paris, France
| | - Emiliangelo Ratti
- Neuroscience Therapeutic Area Unit, Takeda Pharmaceuticals International Co., Cambridge, MA, United States
| | - Emilio Merlo Pich
- The Division of Brain Science, Imperial College London, London, United Kingdom.,Neuroscience Therapeutic Area Unit, Takeda Pharmaceuticals International, Zurich, Switzerland
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30
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Coughlin JM, Slania S, Du Y, Rosenthal HB, Lesniak WG, Minn I, Smith GS, Dannals RF, Kuwabara H, Wong DF, Wang Y, Horti AG, Pomper MG. 18F-XTRA PET for Enhanced Imaging of the Extrathalamic α4β2 Nicotinic Acetylcholine Receptor. J Nucl Med 2018; 59:1603-1608. [PMID: 29496987 DOI: 10.2967/jnumed.117.205492] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Accepted: 02/03/2018] [Indexed: 11/16/2022] Open
Abstract
Reduced density of the α4β2 nicotinic acetylcholine receptor (α4β2-nAChR) in the cortex and hippocampus of the human brain has been reported in aging and patients with neurodegenerative disease. This study assessed the pharmacokinetic behavior of 18F-(-)-JHU86428 (18F-XTRA), a new radiotracer for in vivo PET imaging of the α4β2-nAChR, particularly in extrathalamic regions of interest in which the α4β2-nAChR is less densely expressed than in thalamus. 18F-XTRA was also used to evaluate the α4β2-nAChR in the hippocampus in human aging. Methods: Seventeen healthy nonsmoker adults (11 men, 6 women; age, 30-82 y) underwent PET neuroimaging over 90 or 180 min in a high-resolution research tomograph after bolus injection of 18F-XTRA. Methods to quantify binding of 18F-XTRA to the α4β2-nAChR in the human brain were compared, and the relationship between age and binding in the hippocampus was tested. Results: 18F-XTRA rapidly entered the brain, and time-activity curves peaked within 10 min after injection for extrathalamic regions and at approximately 70 min in the thalamus. The 2-tissue-compartment model (2TCM) predicted the regional time-activity curves better than the 1-tissue-compartment model, and total distribution volume (VT) was well identified by the 2TCM in all ROIs. VT values estimated using Logan analysis with metabolite-corrected arterial input were highly correlated with those from the 2TCM in all regions, and values from 90-min scan duration were on average within 5% of those values from 180 min of data. Parametric images of VT were consistent with the known distribution of the α4β2-nAChR across the brain. Finally, an inverse correlation between VT in the hippocampus and age was observed. Conclusion: Our results extend support for use of 18F-XTRA with 90 min of emission scanning in quantitative human neuroimaging of the extrathalamic α4β2-nAChR, including in studies of aging.
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Affiliation(s)
- Jennifer M Coughlin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland.,Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Stephanie Slania
- Department of Biomedical Engineering, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Yong Du
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Hailey B Rosenthal
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Wojciech G Lesniak
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Il Minn
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Gwenn S Smith
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland.,Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Robert F Dannals
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Hiroto Kuwabara
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Dean F Wong
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland.,Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland.,Department of Neuroscience, Johns Hopkins Medical Institutions, Baltimore, Maryland; and.,Department of Neurology, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Yuchuan Wang
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Andrew G Horti
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Martin G Pomper
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland .,Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland.,Department of Biomedical Engineering, Johns Hopkins Medical Institutions, Baltimore, Maryland
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31
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The striatal cholinergic system in L-dopa-induced dyskinesias. J Neural Transm (Vienna) 2018; 125:1251-1262. [PMID: 29492663 DOI: 10.1007/s00702-018-1845-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 01/23/2018] [Indexed: 12/18/2022]
Abstract
Cholinergic signaling plays a key role in regulating striatal function. The principal source of acetylcholine in the striatum is the cholinergic interneurons which, although low in number, densely arborize to modulate striatal neurotransmission. This modulation occurs via strategically positioned nicotinic and muscarinic acetylcholine receptors that influence striatal dopamine, GABA and other neurotransmitter release. Cholinergic interneurons integrate multiple striatal synaptic inputs and outputs to regulate motor activity under normal physiological conditions. Consequently, an imbalance between these systems is associated with basal ganglia disorders. Here, we provide an overview of how striatal cholinergic interneurons modulate striatal activity under normal and pathological conditions. Numerous studies show that nigrostriatal damage such as that occurs with Parkinson's disease affects cholinergic receptor-mediated striatal activity. This altered cholinergic signaling is an important contributor to Parkinson's disease as well as to the dyskinesias that develop with L-dopa therapy, the gold standard for treatment. Indeed, multiple preclinical studies show that cholinergic receptor drugs may be beneficial for the treatment of L-dopa-induced dyskinesias. In this review, we discuss the evidence indicating that therapeutic modulation of the cholinergic system, particularly targeting of nicotinic cholinergic receptors, may offer a novel approach to manage this debilitating side effect of dopamine replacement therapy for Parkinson's disease.
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Dumont G, Maex R, Gutkin B. Dopaminergic Neurons in the Ventral Tegmental Area and Their Dysregulation in Nicotine Addiction. COMPUTATIONAL PSYCHIATRY 2018. [DOI: 10.1016/b978-0-12-809825-7.00003-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Deletion of lynx1 reduces the function of α6* nicotinic receptors. PLoS One 2017; 12:e0188715. [PMID: 29206881 PMCID: PMC5716591 DOI: 10.1371/journal.pone.0188715] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 11/13/2017] [Indexed: 11/19/2022] Open
Abstract
The α6 nicotinic acetylcholine receptor (nAChR) subunit is an attractive drug target for treating nicotine addiction because it is present at limited sites in the brain including the reward pathway. Lynx1 modulates several nAChR subtypes; lynx1-nAChR interaction sites could possibly provide drug targets. We found that dopaminergic cells from the substantia nigra pars compacta (SNc) express lynx1 mRNA transcripts and, as assessed by co-immunoprecipitation, α6 receptors form stable complexes with lynx1 protein, although co-transfection with lynx1 did not affect nicotine-induced currents from cell lines transfected with α6 and β2. To test whether lynx1 is important for the function of α6 nAChRs in vivo, we bred transgenic mice carrying a hypersensitive mutation in the α6 nAChR subunit (α6L9′S) with lynx1 knockout mice, providing a selective probe of the effects of lynx1 on α6* nAChRs. Lynx1 removal reduced the α6 component of nicotine-mediated rubidium efflux and dopamine (DA) release from synaptosomal preparations with no effect on numbers of α6β2 binding sites, indicating that lynx1 is functionally important for α6* nAChR activity. No effects of lynx1 removal were detected on nicotine-induced currents in slices from SNc, suggesting that lynx1 affects presynaptic α6* nAChR function more than somatic function. In the absence of agonist, lynx1 removal did not alter DA release in dorsal striatum as measured by fast scan cyclic voltammetry. Lynx1 removal affected some behaviors, including a novel-environment assay and nicotine-stimulated locomotion. Trends in 24-hour home-cage behavior were also suggestive of an effect of lynx1 removal. Conditioned place preference for nicotine was not affected by lynx1 removal. The results show that some functional and behavioral aspects of α6-nAChRs are modulated by lynx1.
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Yu J, Zhu X, Yang Y, Luo S, Zhangsun D. Expression in Escherichia coli of fusion protein comprising α-conotoxin TxIB and preservation of selectivity to nicotinic acetylcholine receptors in the purified product. Chem Biol Drug Des 2017; 91:349-358. [PMID: 28891599 DOI: 10.1111/cbdd.13104] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 06/04/2017] [Accepted: 08/21/2017] [Indexed: 12/19/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels, which are widely distributed in the central and peripheral nervous system. The α6β2* nAChR is an important subtype, which is closely associated with nicotine addiction and movement disorders etc. α-conotoxin TxIB with 16-amino acid residues specifically targets α6β2* nAChR with no obvious effect on other nAChR subtypes. However, chemical synthesis of TxIB is expensive, and the quantity of native TxIB extracted from cone snail is limited. In the present study, we attempted to obtain TxIB using biological method based on the recombinant expression in Escherichia coli (E. coli). The synthetic gene encoding mature peptide of TxIB was inserted in pET-31b(+) vector and transformed into E. coli strain BLR(DE3)pLysS for expression. The recombinant fusion protein KSI-TxIB-His6 (KSI, ketosteroid isomerase) was expressed successfully as inclusion body in E. coli, which was purified by Ni-NTA affinity chromatography column and cleaved by cyanogen bromide (CNBr) to release recombinant α-conotoxin TxIB (rTxIB). Then, rTxIB was purified by reverse-phase high-performance liquid chromatography (RP-HPLC) and was identified by electrospray ionization mass spectrometry (ESI-MS). Pharmacological activity of rTxIB was assessed by electrophysiological approaches. The results indicated that it preserved about 50% of potency, but, was even more important, had the same selectivity as the natural conotoxin which may provide an alternative method for quantity production of small peptides with low cost on the premise of not changing their potency.
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Affiliation(s)
- Jinpeng Yu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China.,College of Agriculture, Hainan University, Haikou, China
| | - Xiaopeng Zhu
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China
| | - Yang Yang
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China.,College of Agriculture, Hainan University, Haikou, China
| | - Sulan Luo
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China
| | - Dongting Zhangsun
- Key Laboratory of Tropical Biological Resources, Ministry of Education, Key Laboratory for Marine Drugs of Haikou, Hainan University, Haikou, China
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α6β2 nicotinic acetylcholine receptors influence locomotor activity and ethanol consumption. Alcohol 2017; 61:43-49. [PMID: 28457669 DOI: 10.1016/j.alcohol.2017.02.178] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 02/10/2017] [Accepted: 02/11/2017] [Indexed: 12/13/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) in the mesolimbic dopamine system have been implicated in ethanol behaviors. In particular, work in genetically engineered mice has demonstrated that α6-containing nAChRs are involved in ethanol consumption and sedation. A limitation of these studies is that the alteration in the receptor was present throughout development. The recently described α6β2 antagonist, N,N-decane-1,10-diyl-bis-3-picolinium diiodide (bPiDI), now makes it possible to test for the involvement of these receptors using a pharmacological approach. The aim of this study was to examine the role of α6β2 nAChRs in ethanol behaviors using a pharmacological approach. Adolescent C57BL/6J mice were treated with bPiDI 30 min prior to testing the mice for binge-like ethanol consumption in the drinking-in-the-dark (DID) test, ethanol-induced motor incoordination using the balance beam, and ethanol-induced sedation using the Loss of Righting Reflex (LORR) paradigm. Adolescent animals were chosen because they express a high amount of α6 mRNA relative to adult animals. Control studies were also performed to determine the effect of bPiDI on locomotor activity and ethanol metabolism. Female mice treated with 20 mg/kg bPiDI had reduced locomotor activity compared to saline-treated animals during the first 30 min following an acute injection. Pretreatment with the α6β2 antagonist reduced adolescent ethanol consumption but also reduced saccharin consumption. No significant effects were observed on ethanol-induced ataxia, sedation, or metabolism. This study provides evidence that α6β2 nAChRs are involved in locomotor activity as well as ethanol and saccharin consumption in adolescent animals.
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Armstrong LC, Kirsch GE, Fedorov NB, Wu C, Kuryshev YA, Sewell AL, Liu Z, Motter AL, Leggett CS, Orr MS. High-Throughput Patch Clamp Screening in Human α6-Containing Nicotinic Acetylcholine Receptors. SLAS DISCOVERY 2017; 22:686-695. [PMID: 28298165 PMCID: PMC5480602 DOI: 10.1177/2472555217696794] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Nicotine, the addictive component of tobacco products, is an agonist at nicotinic acetylcholine receptors (nAChRs) in the brain. The subtypes of nAChR are defined by their α- and β-subunit composition. The α6β2β3 nAChR subtype is expressed in terminals of dopaminergic neurons that project to the nucleus accumbens and striatum and modulate dopamine release in brain regions involved in nicotine addiction. Although subtype-dependent selectivity of nicotine is well documented, subtype-selective profiles of other tobacco product constituents are largely unknown and could be essential for understanding the addiction-related neurological effects of tobacco products. We describe the development and validation of a recombinant cell line expressing human α6/3β2β3V273S nAChR for screening and profiling assays in an automated patch clamp platform (IonWorks Barracuda). The cell line was pharmacologically characterized by subtype-selective and nonselective reference agonists, pore blockers, and competitive antagonists. Agonist and antagonist effects detected by the automated patch clamp approach were comparable to those obtained by conventional electrophysiological assays. A pilot screen of a library of Food and Drug Administration–approved drugs identified compounds, previously not known to modulate nAChRs, which selectively inhibited the α6/3β2β3V273S subtype. These assays provide new tools for screening and subtype-selective profiling of compounds that act at α6β2β3 nicotinic receptors.
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Affiliation(s)
| | | | | | - Caiyun Wu
- 1 Charles River Discovery, Cleveland, OH, USA
| | | | | | - Zhiqi Liu
- 1 Charles River Discovery, Cleveland, OH, USA
| | - Arianne L Motter
- 2 U.S. Food and Drug Administration/Center for Tobacco Products, Silver Spring, MD, USA
| | - Carmine S Leggett
- 2 U.S. Food and Drug Administration/Center for Tobacco Products, Silver Spring, MD, USA
| | - Michael S Orr
- 2 U.S. Food and Drug Administration/Center for Tobacco Products, Silver Spring, MD, USA.,PAREXEL International, Bethesda, MD, USA
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Neuronal Nicotinic Acetylcholine Receptor Modulators Reduce Sugar Intake. PLoS One 2016; 11:e0150270. [PMID: 27028298 PMCID: PMC4814119 DOI: 10.1371/journal.pone.0150270] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 02/11/2016] [Indexed: 12/21/2022] Open
Abstract
Excess sugar consumption has been shown to contribute directly to weight gain, thus contributing to the growing worldwide obesity epidemic. Interestingly, increased sugar consumption has been shown to repeatedly elevate dopamine levels in the nucleus accumbens (NAc), in the mesolimbic reward pathway of the brain similar to many drugs of abuse. We report that varenicline, an FDA-approved nicotinic acetylcholine receptor (nAChR) partial agonist that modulates dopamine in the mesolimbic reward pathway of the brain, significantly reduces sucrose consumption, especially in a long-term consumption paradigm. Similar results were observed with other nAChR drugs, namely mecamylamine and cytisine. Furthermore, we show that long-term sucrose consumption increases α4β2 * and decreases α6β2* nAChRs in the nucleus accumbens, a key brain region associated with reward. Taken together, our results suggest that nAChR drugs such as varenicline may represent a novel treatment strategy for reducing sugar consumption.
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Vieira-Brock PL, McFadden LM, Nielsen SM, Ellis JD, Walters ET, Stout KA, McIntosh JM, Wilkins DG, Hanson GR, Fleckenstein AE. Chronic Nicotine Exposure Attenuates Methamphetamine-Induced Dopaminergic Deficits. J Pharmacol Exp Ther 2015; 355:463-72. [PMID: 26391161 DOI: 10.1124/jpet.114.221945] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 09/18/2015] [Indexed: 01/14/2023] Open
Abstract
Repeated methamphetamine (METH) administrations cause persistent dopaminergic deficits resembling aspects of Parkinson's disease. Many METH abusers smoke cigarettes and thus self-administer nicotine; yet few studies have investigated the effects of nicotine on METH-induced dopaminergic deficits. This interaction is of interest because preclinical studies demonstrate that nicotine can be neuroprotective, perhaps owing to effects involving α4β2 and α6β2 nicotinic acetylcholine receptors (nAChRs). This study revealed that oral nicotine exposure beginning in adolescence [postnatal day (PND) 40] through adulthood [PND 96] attenuated METH-induced striatal dopaminergic deficits when METH was administered at PND 89. This protection did not appear to be due to nicotine-induced alterations in METH pharmacokinetics. Short-term (i.e., 21-day) high-dose nicotine exposure also protected when administered from PND 40 to PND 61 (with METH at PND 54), but this protective effect did not persist. Short-term (i.e., 21-day) high-dose nicotine exposure did not protect when administered postadolescence (i.e., beginning at PND 61, with METH at PND 75). However, protection was engendered if the duration of nicotine exposure was extended to 39 days (with METH at PND 93). Autoradiographic analysis revealed that nicotine increased striatal α4β2 expression, as assessed using [(125)I]epibatidine. Both METH and nicotine decreased striatal α6β2 expression, as assessed using [(125)I]α-conotoxin MII. These findings indicate that nicotine protects against METH-induced striatal dopaminergic deficits, perhaps by affecting α4β2 and/or α6β2 expression, and that both age of onset and duration of nicotine exposure affect this protection.
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Affiliation(s)
- Paula L Vieira-Brock
- Departments of Pharmacology and Toxicology (P.V.-B., L.M.M., S.M.N., J.D.E., E.T.W., K.A.S., G.R.H.), Psychiatry and Biology (J.M.M.), and Pathology (D.G.W.), School of Dentistry (G.R.H., A.E.F.), University of Utah, Salt Lake City, Utah; and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - Lisa M McFadden
- Departments of Pharmacology and Toxicology (P.V.-B., L.M.M., S.M.N., J.D.E., E.T.W., K.A.S., G.R.H.), Psychiatry and Biology (J.M.M.), and Pathology (D.G.W.), School of Dentistry (G.R.H., A.E.F.), University of Utah, Salt Lake City, Utah; and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - Shannon M Nielsen
- Departments of Pharmacology and Toxicology (P.V.-B., L.M.M., S.M.N., J.D.E., E.T.W., K.A.S., G.R.H.), Psychiatry and Biology (J.M.M.), and Pathology (D.G.W.), School of Dentistry (G.R.H., A.E.F.), University of Utah, Salt Lake City, Utah; and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - Jonathan D Ellis
- Departments of Pharmacology and Toxicology (P.V.-B., L.M.M., S.M.N., J.D.E., E.T.W., K.A.S., G.R.H.), Psychiatry and Biology (J.M.M.), and Pathology (D.G.W.), School of Dentistry (G.R.H., A.E.F.), University of Utah, Salt Lake City, Utah; and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - Elliot T Walters
- Departments of Pharmacology and Toxicology (P.V.-B., L.M.M., S.M.N., J.D.E., E.T.W., K.A.S., G.R.H.), Psychiatry and Biology (J.M.M.), and Pathology (D.G.W.), School of Dentistry (G.R.H., A.E.F.), University of Utah, Salt Lake City, Utah; and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - Kristen A Stout
- Departments of Pharmacology and Toxicology (P.V.-B., L.M.M., S.M.N., J.D.E., E.T.W., K.A.S., G.R.H.), Psychiatry and Biology (J.M.M.), and Pathology (D.G.W.), School of Dentistry (G.R.H., A.E.F.), University of Utah, Salt Lake City, Utah; and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - J Michael McIntosh
- Departments of Pharmacology and Toxicology (P.V.-B., L.M.M., S.M.N., J.D.E., E.T.W., K.A.S., G.R.H.), Psychiatry and Biology (J.M.M.), and Pathology (D.G.W.), School of Dentistry (G.R.H., A.E.F.), University of Utah, Salt Lake City, Utah; and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - Diana G Wilkins
- Departments of Pharmacology and Toxicology (P.V.-B., L.M.M., S.M.N., J.D.E., E.T.W., K.A.S., G.R.H.), Psychiatry and Biology (J.M.M.), and Pathology (D.G.W.), School of Dentistry (G.R.H., A.E.F.), University of Utah, Salt Lake City, Utah; and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - Glen R Hanson
- Departments of Pharmacology and Toxicology (P.V.-B., L.M.M., S.M.N., J.D.E., E.T.W., K.A.S., G.R.H.), Psychiatry and Biology (J.M.M.), and Pathology (D.G.W.), School of Dentistry (G.R.H., A.E.F.), University of Utah, Salt Lake City, Utah; and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - Annette E Fleckenstein
- Departments of Pharmacology and Toxicology (P.V.-B., L.M.M., S.M.N., J.D.E., E.T.W., K.A.S., G.R.H.), Psychiatry and Biology (J.M.M.), and Pathology (D.G.W.), School of Dentistry (G.R.H., A.E.F.), University of Utah, Salt Lake City, Utah; and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
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Zoli M, Pistillo F, Gotti C. Diversity of native nicotinic receptor subtypes in mammalian brain. Neuropharmacology 2015; 96:302-11. [DOI: 10.1016/j.neuropharm.2014.11.003] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/11/2014] [Accepted: 11/08/2014] [Indexed: 01/01/2023]
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Gonzales KK, Smith Y. Cholinergic interneurons in the dorsal and ventral striatum: anatomical and functional considerations in normal and diseased conditions. Ann N Y Acad Sci 2015; 1349:1-45. [PMID: 25876458 DOI: 10.1111/nyas.12762] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Striatal cholinergic interneurons (ChIs) are central for the processing and reinforcement of reward-related behaviors that are negatively affected in states of altered dopamine transmission, such as in Parkinson's disease or drug addiction. Nevertheless, the development of therapeutic interventions directed at ChIs has been hampered by our limited knowledge of the diverse anatomical and functional characteristics of these neurons in the dorsal and ventral striatum, combined with the lack of pharmacological tools to modulate specific cholinergic receptor subtypes. This review highlights some of the key morphological, synaptic, and functional differences between ChIs of different striatal regions and across species. It also provides an overview of our current knowledge of the cellular localization and function of cholinergic receptor subtypes. The future use of high-resolution anatomical and functional tools to study the synaptic microcircuitry of brain networks, along with the development of specific cholinergic receptor drugs, should help further elucidate the role of striatal ChIs and permit efficient targeting of cholinergic systems in various brain disorders, including Parkinson's disease and addiction.
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Affiliation(s)
- Kalynda K Gonzales
- Yerkes National Primate Research Center, Department of Neurology and Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia.,Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York
| | - Yoland Smith
- Yerkes National Primate Research Center, Department of Neurology and Udall Center of Excellence for Parkinson's Disease Research, Emory University, Atlanta, Georgia
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41
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Barreto GE, Iarkov A, Moran VE. Beneficial effects of nicotine, cotinine and its metabolites as potential agents for Parkinson's disease. Front Aging Neurosci 2015; 6:340. [PMID: 25620929 PMCID: PMC4288130 DOI: 10.3389/fnagi.2014.00340] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 12/04/2014] [Indexed: 01/10/2023] Open
Abstract
Parkinson’s disease (PD) is a progressive neurodegenerative disorder, which is characterized by neuroinflammation, dopaminergic neuronal cell death and motor dysfunction, and for which there are no proven effective treatments. The negative correlation between tobacco consumption and PD suggests that tobacco-derived compounds can be beneficial against PD. Nicotine, the more studied alkaloid derived from tobacco, is considered to be responsible for the beneficial behavioral and neurological effects of tobacco use in PD. However, several metabolites of nicotine, such as cotinine, also increase in the brain after nicotine administration. The effect of nicotine and some of its derivatives on dopaminergic neurons viability, neuroinflammation, and motor and memory functions, have been investigated using cellular and rodent models of PD. Current evidence shows that nicotine, and some of its derivatives diminish oxidative stress and neuroinflammation in the brain and improve synaptic plasticity and neuronal survival of dopaminergic neurons. In vivo these effects resulted in improvements in mood, motor skills and memory in subjects suffering from PD pathology. In this review, we discuss the potential benefits of nicotine and its derivatives for treating PD.
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Affiliation(s)
- George E Barreto
- Department of Nutrition and Biochemistry, Pontificia Universidad Javeriana Bogotá, D. C., Colombia
| | - Alexander Iarkov
- Center of Research in Biomedical Sciences, Universidad Autónoma de Chile Santiago, Chile ; Research & Development Service, Bay Pines VA Healthcare System Bay Pines, FL, USA
| | - Valentina Echeverria Moran
- Center of Research in Biomedical Sciences, Universidad Autónoma de Chile Santiago, Chile ; Research & Development Service, Bay Pines VA Healthcare System Bay Pines, FL, USA ; Research Service, James A Haley Veterans' Hospital Tampa, FL, USA ; Department of Molecular Medicine, Morsani College of Medicine, University of South Tampa, FL, USA
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42
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Garção P, Szabó EC, Wopereis S, Castro AA, Tomé ÂR, Prediger RD, Cunha RA, Agostinho P, Köfalvi A. Functional interaction between pre-synaptic α6β2-containing nicotinic and adenosine A2A receptors in the control of dopamine release in the rat striatum. Br J Pharmacol 2014; 169:1600-11. [PMID: 23638679 DOI: 10.1111/bph.12234] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 04/17/2013] [Accepted: 04/19/2013] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND AND PURPOSE Pre-synaptic nicotinic ACh receptors (nAChRs) and adenosine A2A receptors (A2A Rs) are involved in the control of dopamine release and are putative therapeutic targets in Parkinson's disease and addiction. Since A2A Rs have been reported to interact with nAChRs, here we aimed at mapping the possible functional interaction between A2A Rs and nAChRs in rat striatal dopaminergic terminals. EXPERIMENTAL APPROACH We pharmacologically characterized the release of dopamine and defined the localization of nAChR subunits in rat striatal nerve terminals in vitro and carried out locomotor behavioural sensitization in rats in vivo. KEY RESULTS In striatal nerve terminals, the selective A2A R agonist CGS21680 inhibited, while the A2A R antagonist ZM241385 potentiated the nicotine-stimulated [(3) H]dopamine ([(3) H]DA) release. Upon blockade of the α6 subunit-containing nAChRs, the remaining nicotine-stimulated [(3) H]DA release was no longer modulated by A2A R ligands. In the locomotor sensitization experiments, nicotine enhanced the locomotor activity on day 7 of repeated nicotine injection, an effect that no longer persisted after 1 week of drug withdrawal. Notably, ZM241385-injected rats developed locomotor sensitization to nicotine already on day 2, which remained persistent upon nicotine withdrawal. CONCLUSIONS AND IMPLICATIONS These results provide the first evidence for a functional interaction between nicotinic and adenosine A2A R in striatal dopaminergic terminals, with likely therapeutic consequences for smoking, Parkinson's disease and other dopaminergic disorders.
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Affiliation(s)
- P Garção
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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Wang J, Kuryatov A, Lindstrom J. Expression of cloned α6* nicotinic acetylcholine receptors. Neuropharmacology 2014; 96:194-204. [PMID: 25446669 DOI: 10.1016/j.neuropharm.2014.10.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 09/19/2014] [Accepted: 10/07/2014] [Indexed: 10/24/2022]
Abstract
Nicotinic acetylcholine receptors (AChRs) are ACh-gated ion channels formed from five homologous subunits in subtypes defined by their subunit composition and stoichiometry. Some subtypes readily produce functional AChRs in Xenopus oocytes and transfected cell lines. α6β2β3* AChRs (subtypes formed from these subunits and perhaps others) are not easily expressed. This may be because the types of neurons in which they are expressed (typically dopaminergic neurons) have unique chaperones for assembling α6β2β3* AChRs, especially in the presence of the other AChR subtypes. Because these relatively minor brain AChR subtypes are of major importance in addiction to nicotine, it is important for drug development as well as investigation of their functional properties to be able to efficiently express human α6β2β3* AChRs. We review the issues and progress in expressing α6* AChRs. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
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Affiliation(s)
- Jingyi Wang
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Alexander Kuryatov
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Jon Lindstrom
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA.
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Yu LF, Zhang HK, Caldarone BJ, Eaton JB, Lukas RJ, Kozikowski AP. Recent developments in novel antidepressants targeting α4β2-nicotinic acetylcholine receptors. J Med Chem 2014; 57:8204-23. [PMID: 24901260 PMCID: PMC4207546 DOI: 10.1021/jm401937a] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
![]()
Nicotinic acetylcholine receptors
(nAChRs) have been investigated
for developing drugs that can potentially treat various central nervous
system disorders. Considerable evidence supports the hypothesis that
modulation of the cholinergic system through activation and/or desensitization/inactivation
of nAChR holds promise for the development of new antidepressants.
The introductory portion of this Miniperspective discusses the basic
pharmacology that underpins the involvement of α4β2-nAChRs
in depression, along with the structural features that are essential
to ligand recognition by the α4β2-nAChRs. The remainder
of this Miniperspective analyzes reported nicotinic ligands in terms
of drug design considerations and their potency and selectivity, with
a particular focus on compounds exhibiting antidepressant-like effects
in preclinical or clinical studies. This Miniperspective aims to provide
an in-depth analysis of the potential for using nicotinic ligands
in the treatment of depression, which may hold some promise in addressing
an unmet clinical need by providing relief from depressive symptoms
in refractory patients.
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Affiliation(s)
- Li-Fang Yu
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago , 833 South Wood Street, Chicago, Illinois 60612, United States
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Marks MJ, Grady SR, Salminen O, Paley MA, Wageman CR, McIntosh JM, Whiteaker P. α6β2*-subtype nicotinic acetylcholine receptors are more sensitive than α4β2*-subtype receptors to regulation by chronic nicotine administration. J Neurochem 2014; 130:185-98. [PMID: 24661093 DOI: 10.1111/jnc.12721] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 03/04/2014] [Accepted: 03/21/2014] [Indexed: 11/28/2022]
Abstract
Nicotinic acetylcholine receptors (nAChR) of the α6β2* subtype (where *indicates the possible presence of additional subunits) are prominently expressed on dopaminergic neurons. Because of this, their role in tobacco use and nicotine dependence has received much attention. Previous studies have demonstrated that α6β2*-nAChR are down-regulated following chronic nicotine exposure (unlike other subtypes that have been investigated - most prominently α4β2* nAChR). This study examines, for the first time, effects across a comprehensive chronic nicotine dose range. Chronic nicotine dose-responses and quantitative ligand-binding autoradiography were used to define nicotine sensitivity of changes in α4β2*-nAChR and α6β2*-nAChR expression. α6β2*-nAChR down-regulation by chronic nicotine exposure in dopaminergic and optic-tract nuclei was ≈three-fold more sensitive than up-regulation of α4β2*-nAChR. In contrast, nAChR-mediated [(3) H]-dopamine release from dopamine-terminal region synaptosomal preparations changed only in response to chronic treatment with high nicotine doses, whereas dopaminergic parameters (transporter expression and activity, dopamine receptor expression) were largely unchanged. Functional measures in olfactory tubercle preparations were made for the first time; both nAChR expression levels and nAChR-mediated functional measures changed differently between striatum and olfactory tubercles. These results show that functional changes measured using synaptosomal [(3) H]-DA release are primarily owing to changes in nAChR, rather than in dopaminergic, function. This study examined dose-response relationships for murine α6β2*-nicotinic acetylcholine receptor (nAChR) down-regulation by chronic nicotine treatment. The ID50 value for α6β2* down-regulation (35 nM) is ≈ 3x lower than the ED50 value for α4β2* nAChR up-regulation (95 nM), both well within the range reached by human smokers. Chronic nicotine treatment altered α6β2*- and α4β2*-nAChR-mediated [(3) H]-dopamine release from striatal and olfactory tubercle synaptosomes, but dopaminergic parameters were largely unaffected. We conclude that functional changes are primarily driven by altered nAChR activity.
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Affiliation(s)
- Michael J Marks
- Institute for Behavioral Genetics, University of Colorado, Boulder, Colorado, USA
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Brunzell DH, McIntosh JM, Papke RL. Diverse strategies targeting α7 homomeric and α6β2* heteromeric nicotinic acetylcholine receptors for smoking cessation. Ann N Y Acad Sci 2014; 1327:27-45. [PMID: 24730978 DOI: 10.1111/nyas.12421] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Preclinical studies suggest that a diversity of nicotinic acetylcholine receptors (nAChRs) with different sensitivities to nicotine may contribute to tobacco addiction. Using rodent intravenous nicotine self-administration as a preclinical model with good predictive validity for therapeutic efficacy for tobacco cessation, investigators have identified heteromeric α6β2* and homomeric α7 nAChRs as promising novel therapeutic targets to promote smoking abstinence (*denotes possible assembly with other subunits). The data suggest that diverse strategies that target these subclasses of nAChRs, namely inhibition of α6β2* nAChRs and stimulation of α7 nAChRs, will support tobacco cessation. α6β2* nAChRs, members of the high-affinity family of β2* nAChRs, function similarly to α4β2* nAChRs, the primary target of the FDA-approved drug varenicline, but have a much more selective neuroanatomical pattern of expression in catecholaminergic nuclei. Although activation of β2* nAChRs facilitates nicotine self-administration, stimulation of α7 nAChRs appears to negatively modulate both nicotine reinforcement and β2* nAChR function in the mesolimbic dopamine system. Although challenges and caveats must be considered in the development of therapeutics that target these nAChR subpopulations, an accumulation of data suggests that α7 nAChR agonists, partial agonists, or positive allosteric modulators and α6β2* nAChR antagonists, partial agonists, or negative allosteric modulators may prove to be effective therapeutics for tobacco cessation.
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Affiliation(s)
- Darlene H Brunzell
- Department of Pharmacology and Toxicology, Interdisciplinary Neuroscience Program and Institute for Drug and Alcohol Studies, Virginia Commonwealth University School of Medicine, Richmond, Virginia
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Subsynaptic localization of nicotinic acetylcholine receptor subunits: A comparative study in the mouse and rat striatum. Neurosci Lett 2014; 566:106-10. [DOI: 10.1016/j.neulet.2014.02.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 02/05/2014] [Accepted: 02/09/2014] [Indexed: 11/20/2022]
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Schilaty ND, Hedges DM, Jang EY, Folsom RJ, Yorgason JT, McIntosh JM, Steffensen SC. Acute ethanol inhibits dopamine release in the nucleus accumbens via α6 nicotinic acetylcholine receptors. J Pharmacol Exp Ther 2014; 349:559-67. [PMID: 24643637 DOI: 10.1124/jpet.113.211490] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Electrophysiology and microdialysis studies have provided compelling evidence that moderate to high ethanol concentrations enhance dopamine (DA) neurotransmission in the nucleus accumbens (NAc) through the mesolimbic DA system. However, with fast-scan cyclic voltammetry, short-term exposure to moderate to high doses of ethanol decreases evoked DA release at terminals in the NAc. The aim of this study was to evaluate the involvement of nicotinic acetylcholine receptors (nAChRs) in modulating the effects of ethanol on DA release in the NAc of C57BL/6 mice ex vivo and in vivo. Local stimulation evoked robust, frequency-dependent DA release in the NAc slice preparation, with maximal release at 40 Hz in the shell and 20 Hz in the core. Nicotine decreased DA release in a concentration-dependent (0.01-10 μM) manner in the shell and core, with an IC50 of 0.1 μM ex vivo and 0.5 mg/kg in vivo. Nicotine and ethanol inhibition of DA release was blocked by the α6*-nAChR antagonist α-conotoxins CtxMII and α-CtxMII [H9A; L15A] ex vivo (100 nM) in the core but not the shell. Furthermore, the nonspecific nAChR antagonist mecamylamine (2 mg/kg) blocked the effects of ethanol in the core in vivo. These findings suggest that DA release is inhibited by ethanol via nAChRs in the NAc and that DA modulation by nAChRs differs in the core versus the shell, with α6*-nAChRs affecting DA release in the core but not in the shell.
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Affiliation(s)
- Nathan D Schilaty
- Department of Psychology and Center for Neuroscience, Brigham Young University, Provo, Utah (N.D.S., D.M.H., E.Y.J., R.J.F., S.C.S.); Vollum Institute, Oregon Health and Science University, Portland, Oregon (J.T.Y.); and Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, Utah (J.M.M.)
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Yu LF, Brek Eaton J, Zhang HK, Sabath E, Hanania T, Li GN, van Breemen RB, Whiteaker P, Liu Q, Wu J, Chang YC, Lukas RJ, Brunner D, Kozikowski AP. The potent and selective α4β2*/α6*-nicotinic acetylcholine receptor partial agonist 2-[5-[5-((S)Azetidin-2-ylmethoxy)-3-pyridinyl]-3-isoxazolyl]ethanol demonstrates antidepressive-like behavior in animal models and a favorable ADME-tox profile. Pharmacol Res Perspect 2014; 2:e00026. [PMID: 25505580 PMCID: PMC4184702 DOI: 10.1002/prp2.26] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 12/20/2013] [Accepted: 01/08/2014] [Indexed: 11/11/2022] Open
Abstract
Preclinical and clinical studies demonstrated that the inhibition of cholinergic supersensitivity through nicotinic antagonists and partial agonists can be used successfully to treat depressed patients, especially those who are poor responders to selective serotonin reuptake inhibitors (SSRIs). In our effort to develop novel antidepressant drugs, LF-3-88 was identified as a potent nicotinic acetylcholine receptor (nAChR) partial agonist with subnanomolar to nanomolar affinities for β2-containing nAChRs (α2β2, α3β2, α4β2, and α4β2*) and superior selectivity away from α3β4 - (K i > 10(4) nmol/L) and α7-nAChRs (K i > 10(4) nmol/L) as well as 51 other central nervous system (CNS)-related neurotransmitter receptors and transporters. Functional activities at different nAChR subtypes were characterized utilizing (86)Rb(+) ion efflux assays, two-electrode voltage-clamp (TEVC) recording in oocytes, and whole-cell current recording measurements. In mouse models, administration of LF-3-88 resulted in antidepressive-like behavioral signatures 15 min post injection in the SmartCube® test (5 and 10 mg/kg, i.p.; about 45-min session), decreased immobility in the forced swim test (1-3 mg/kg, i.p.; 1-10 mg/kg, p.o.; 30 min pretreatment, 6-min trial), and decreased latency to approach food in the novelty-suppressed feeding test after 29 days chronic administration once daily (5 mg/kg but not 10 mg/kg, p.o.; 15-min trial). In addition, LF-3-88 exhibited a favorable profile in pharmacokinetic/ADME-Tox (absorption, distribution, metabolism, excretion, and toxicity) assays. This compound was also shown to cause no mortality in wild-type Balb/CJ mice when tested at 300 mg/kg. These results further support the potential of potent and selective nicotinic partial agonists for use in the treatment of depression.
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Affiliation(s)
- Li-Fang Yu
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago 833 South Wood Street, Chicago, Illinois, 60612 ; Institute of Drug Design and Development, Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, East China Normal University 3663 North Zhongshan Road, Shanghai, 200062, China
| | - J Brek Eaton
- Division of Neurobiology, Barrow Neurological Institute 350 West Thomas Road, Phoenix, Arizona, 85013
| | - Han-Kun Zhang
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago 833 South Wood Street, Chicago, Illinois, 60612 ; Institute of Biomedical Sciences and School of Life Sciences, East China Normal University 500 Dongchuan Road, Shanghai, 200241, China
| | - Emily Sabath
- PsychoGenics, Inc. 765 Old Saw Mill River Road, Tarrytown, New York, 10591
| | - Taleen Hanania
- PsychoGenics, Inc. 765 Old Saw Mill River Road, Tarrytown, New York, 10591
| | - Guan-Nan Li
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago 833 South Wood Street, Chicago, Illinois, 60612
| | - Richard B van Breemen
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago 833 South Wood Street, Chicago, Illinois, 60612
| | - Paul Whiteaker
- Division of Neurobiology, Barrow Neurological Institute 350 West Thomas Road, Phoenix, Arizona, 85013
| | - Qiang Liu
- Division of Neurobiology, Barrow Neurological Institute 350 West Thomas Road, Phoenix, Arizona, 85013 ; Division of Neurology, Barrow Neurological Institute 350 West Thomas Road, Phoenix, Arizona, 85013
| | - Jie Wu
- Division of Neurology, Barrow Neurological Institute 350 West Thomas Road, Phoenix, Arizona, 85013
| | - Yong-Chang Chang
- Division of Neurobiology, Barrow Neurological Institute 350 West Thomas Road, Phoenix, Arizona, 85013
| | - Ronald J Lukas
- Division of Neurobiology, Barrow Neurological Institute 350 West Thomas Road, Phoenix, Arizona, 85013
| | - Dani Brunner
- PsychoGenics, Inc. 765 Old Saw Mill River Road, Tarrytown, New York, 10591 ; Department of Psychiatry, Columbia University, NYSPI 1051 Riverside Drive, New York, New York, 10032
| | - Alan P Kozikowski
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago 833 South Wood Street, Chicago, Illinois, 60612
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Luo S, Zhangsun D, Schroeder CI, Zhu X, Hu Y, Wu Y, Weltzin MM, Eberhard S, Kaas Q, Craik DJ, McIntosh JM, Whiteaker P. A novel α4/7-conotoxin LvIA from Conus lividus that selectively blocks α3β2 vs. α6/α3β2β3 nicotinic acetylcholine receptors. FASEB J 2014; 28:1842-53. [PMID: 24398291 DOI: 10.1096/fj.13-244103] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
This study was performed to discover and characterize the first potent α3β2-subtype-selective nicotinic acetylcholine receptor (nAChR) ligand. A novel α4/7-conotoxin, α-CTxLvIA, was cloned from Conus lividus. Its pharmacological profile at Xenopus laevis oocyte-expressed rat nAChR subtypes was determined by 2-electrode voltage-clamp electrophysiology, and its 3-dimensional (3D) structure was determined by NMR spectroscopy. α-CTx LvIA is a 16-aa C-terminally-amidated peptide with 2-disulfide bridges. Using rat subunits expressed in Xenopus oocytes, we found the highest affinity of α-CTxLvIA was for α3β2 nAChRs (IC50 8.7 nM), where blockade was reversible within 2 min. IC50 values were >100 nM at α6/α3β2β3, α6/α3β4, and α3β4 nAChRs, and ≥3 μM at all other subtypes tested. α3β2 vs. α6β2 subtype selectivity was confirmed for human-subunit nAChRs with much greater preference (300-fold) for α3β2 over α6β2 nAChRs. This is the first α-CTx reported to show high selectivity for human α3β2 vs. α6β2 nAChRs. α-CTxLvIA adopts two similarly populated conformations water: one (assumed to be bioactive) is highly structured, whereas the other is mostly random coil in nature. Selectivity differences with the similarly potent, but less selective, α3β2 nAChR antagonist α-CTx PeIA probably reside within the three residues, which differ in loop 2, given their otherwise similar 3D structures. α4/7-CTx LvIA is a new, potent, selective α3β2 nAChR antagonist, which will enable detailed studies of α3β2 nAChR structure, function, and physiological roles.
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Affiliation(s)
- Sulan Luo
- 1Key Laboratory of Tropical Biological Resources, Ministry of Education, Hainan University; Haikou, Hainan, 570228 China.
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