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Tan X, Ingraham CM, McBride WJ, Ding ZM. The involvement of mesolimbic dopamine system in cotinine self-administration in rats. Behav Brain Res 2022; 417:113596. [PMID: 34562552 PMCID: PMC8578415 DOI: 10.1016/j.bbr.2021.113596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 09/20/2021] [Accepted: 09/20/2021] [Indexed: 01/26/2023]
Abstract
Cotinine is the major metabolite of nicotine and has recently been shown to be self-administered intravenously by rats. However, mechanisms underlying cotinine self-administration remained unknown. Mesolimbic dopamine system projecting from the ventral tegmental area (VTA) to nucleus accumbens (NAC) is closely implicated in drug reinforcement, including nicotine. The objective of the current study was to determine potential involvement of mesolimbic dopamine system in cotinine self-administration. An intracranial self-administration experiment demonstrates that cotinine at 0.88 and 1.76 ng/100 nl/infusion was self-infused into the VTA by rats. Rats produced more infusions of cotinine than vehicle and responded more on active than inactive lever during acquisition, reduced responding when cotinine was replaced by vehicle, and resumed responding during re-exposure to cotinine. Microinjection of cotinine at 1.76 ng/100 nl/infusion into the VTA increased extracellular dopamine levels within the NAC. Subcutaneous injection of cotinine at 1 mg/kg also increased extracellular dopamine levels within the NAC. Administration of the D1-like receptor antagonist SCH 23390 attenuated intravenous cotinine self-administration. On the other hand, bupropion, a catecholamine uptake inhibitor, did not significantly alter intravenous cotinine self-administration. These results suggest that activation of mesolimbic dopamine system may represent one cellular mechanism underlying cotinine self-administration. This shared mechanism between cotinine and nicotine suggests that cotinine may play a role in nicotine reinforcement.
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Affiliation(s)
- Xiaoying Tan
- Department of Anesthesiology & Perioperative Medicine, and Pharmacology, Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA
| | - Cynthia M Ingraham
- Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - William J McBride
- Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Zheng-Ming Ding
- Department of Anesthesiology & Perioperative Medicine, and Pharmacology, Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA.
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2
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Tan X, Vrana K, Ding ZM. Cotinine: Pharmacologically Active Metabolite of Nicotine and Neural Mechanisms for Its Actions. Front Behav Neurosci 2021; 15:758252. [PMID: 34744656 PMCID: PMC8568040 DOI: 10.3389/fnbeh.2021.758252] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 09/27/2021] [Indexed: 11/17/2022] Open
Abstract
Tobacco use disorder continues to be a leading public health issue and cause of premature death in the United States. Nicotine is considered as the major tobacco alkaloid causing addiction through its actions on nicotinic acetylcholine receptors (nAChRs). Current pharmacotherapies targeting nicotine's effects produce only modest effectiveness in promoting cessation, highlighting the critical need for a better understanding of mechanisms of nicotine addiction to inform future treatments. There is growing interest in identifying potential contributions of non-nicotine components to tobacco reinforcement. Cotinine is a minor alkaloid, but the major metabolite of nicotine that can act as a weak agonist of nAChRs. Accumulating evidence indicates that cotinine produces diverse effects and may contribute to effects of nicotine. In this review, we summarize findings implicating cotinine as a neuroactive metabolite of nicotine and discuss available evidence regarding potential mechanisms underlying its effects. Preclinical findings reveal that cotinine crosses the blood brain barrier and interacts with both nAChRs and non-nAChRs in the nervous system, and produces neuropharmacological and behavioral effects. Clinical studies suggest that cotinine is psychoactive in humans. However, reviewing evidence regarding mechanisms underlying effects of cotinine provides a mixed picture with a lack of consensus. Therefore, more research is warranted in order to provide better insight into the actions of cotinine and its contribution to tobacco addiction.
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Affiliation(s)
- Xiaoying Tan
- Department of Anesthesiology & Perioperative Medicine, and Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Kent Vrana
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - Zheng-Ming Ding
- Department of Anesthesiology & Perioperative Medicine, and Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, United States
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Marusich JA, Darna M, Wilson AG, Denehy ED, Ebben A, Deaciuc AG, Dwoskin LP, Bardo MT, Lefever TW, Wiley JL, Reissig CJ, Jackson KJ. Tobacco's minor alkaloids: Effects on place conditioning and nucleus accumbens dopamine release in adult and adolescent rats. Eur J Pharmacol 2017; 814:196-206. [PMID: 28844873 PMCID: PMC6563910 DOI: 10.1016/j.ejphar.2017.08.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 08/18/2017] [Accepted: 08/23/2017] [Indexed: 12/23/2022]
Abstract
Tobacco products are some of the most commonly used psychoactive drugs worldwide. Besides nicotine, alkaloids in tobacco include cotinine, myosmine, and anatabine. Scientific investigation of these constituents and their contribution to tobacco dependence is less well developed than for nicotine. The present study evaluated the nucleus accumbens dopamine-releasing properties and rewarding and/or aversive properties of nicotine (0.2-0.8mg/kg), cotinine (0.5-5.0mg/kg), anatabine (0.5-5.0mg/kg), and myosmine (5.0-20.0mg/kg) through in vivo microdialysis and place conditioning, respectively, in adult and adolescent male rats. Nicotine increased dopamine release at both ages, and anatabine and myosmine increased dopamine release in adults, but not adolescents. The dopamine release results were not related to place conditioning, as nicotine and cotinine had no effect on place conditioning, whereas anatabine and myosmine produced aversion in both ages. While the nucleus accumbens shell is hypothesized to play a role in strengthening drug-context associations following initiation of drug use, it may have little involvement in the motivational effects of tobacco constituents once these associations have been acquired. Effects of myosmine and anatabine on dopamine release may require a fully developed dopamine system, since no effects of these tobacco alkaloids were observed during adolescence. In summary, while anatabine and myosmine-induced dopamine release in nucleus accumbens may play a role in tobacco dependence in adults, the nature of that role remains to be elucidated.
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Affiliation(s)
- Julie A Marusich
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27709, USA.
| | - Mahesh Darna
- College of Pharmacy, University of Kentucky, Lexington, KY 40536-0596, USA
| | - A George Wilson
- Center for Drug Abuse Research Translation, University of Kentucky, Lexington, KY 40536-0509, USA
| | - Emily D Denehy
- Center for Drug Abuse Research Translation, University of Kentucky, Lexington, KY 40536-0509, USA
| | - Amanda Ebben
- College of Pharmacy, University of Kentucky, Lexington, KY 40536-0596, USA
| | - Agripina G Deaciuc
- College of Pharmacy, University of Kentucky, Lexington, KY 40536-0596, USA
| | - Linda P Dwoskin
- College of Pharmacy, University of Kentucky, Lexington, KY 40536-0596, USA
| | - Michael T Bardo
- Center for Drug Abuse Research Translation, University of Kentucky, Lexington, KY 40536-0509, USA
| | - Timothy W Lefever
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27709, USA
| | - Jenny L Wiley
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27709, USA
| | - Chad J Reissig
- US Food and Drug Administration, Center for Tobacco Products, 10903 New Hampshire Ave., Silver Spring, MD 20993, USA
| | - Kia J Jackson
- US Food and Drug Administration, Center for Tobacco Products, 10903 New Hampshire Ave., Silver Spring, MD 20993, USA
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Terry AV, Callahan PM, Bertrand D. R-(+) and S-(-) isomers of cotinine augment cholinergic responses in vitro and in vivo. J Pharmacol Exp Ther 2014; 352:405-18. [PMID: 25503389 DOI: 10.1124/jpet.114.219881] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The nicotine metabolite cotinine (1-methyl-5-[3-pyridynl]-2-pyrrolidinone), like its precursor, has been found to exhibit procognitive and neuroprotective effects in some model systems; however, the mechanism of these effects is unknown. In this study, both the R-(+) and S-(-) isomers of cotinine were initially evaluated in an extensive profiling screen and found to be relatively inactive across a wide range of potential pharmacologic targets. Electrophysiological studies on human α4β2 and α7 nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus oocytes confirmed the absence of agonistic activity of cotinine at α4β2 or α7 nAChRs. However, a significant increase in the current evoked by a low concentration of acetylcholine was observed at α7 nAChRs exposed to 1.0 μM R-(+)- or S-(-)-cotinine. Based on these results, we used a spontaneous novel object recognition (NOR) procedure for rodents to test the hypothesis that R-(+)- or S-(-)-cotinine might improve recognition memory when administered alone or in combination with the Alzheimer's disease (AD) therapeutic agent donepezil. Although both isomers enhanced NOR performance when they were coadministered with donepezil, neither isomer was active alone. Moreover, the procognitive effects of the drug combinations were blocked by methyllycaconitine and dihydro-β-erythroidine, indicating that both α7 and α4β2 nAChRs contribute to the response. These results indicate that cotinine may sensitize α7 nAChRs to low levels of acetylcholine (a previously uncharacterized mechanism), and that cotinine could be used as an adjunctive agent to improve the effective dose range of cholinergic compounds (e.g., donepezil) in the treatment of AD and other memory disorders.
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Affiliation(s)
- Alvin V Terry
- Department of Pharmacology and Toxicology, and Small Animal Behavior Core, Georgia Regents University, Augusta, Georgia (A.V.T., P.M.C.); and HiQScreen Sàrl, Geneva, Switzerland (D.B.)
| | - Patrick M Callahan
- Department of Pharmacology and Toxicology, and Small Animal Behavior Core, Georgia Regents University, Augusta, Georgia (A.V.T., P.M.C.); and HiQScreen Sàrl, Geneva, Switzerland (D.B.)
| | - Daniel Bertrand
- Department of Pharmacology and Toxicology, and Small Animal Behavior Core, Georgia Regents University, Augusta, Georgia (A.V.T., P.M.C.); and HiQScreen Sàrl, Geneva, Switzerland (D.B.)
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Gao J, Adam BL, Terry AV. Evaluation of nicotine and cotinine analogs as potential neuroprotective agents for Alzheimer's disease. Bioorg Med Chem Lett 2014; 24:1472-8. [PMID: 24581918 DOI: 10.1016/j.bmcl.2014.02.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 01/27/2014] [Accepted: 02/04/2014] [Indexed: 02/05/2023]
Abstract
The currently available therapies for Alzheimer's disease (AD) and related forms of dementia are limited by modest efficacy, adverse side effects, and the fact that they do not prevent the relentless progression of the illness. The purpose of the studies described here was to investigate the neuroprotective effects of the nicotine metabolite cotinine as well as a small series of cotinine and nicotine analogs (including stereoisomers) and to compare their effects to the four clinically prescribed AD therapies.
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Affiliation(s)
- Jie Gao
- Department of Pharmacology and Toxicology, CB-3545, Georgia Regents University, 1120 Fifteenth Street, Augusta, GA 30912-2450, United States
| | - Bao-Ling Adam
- Department of Pharmacology and Toxicology, CB-3545, Georgia Regents University, 1120 Fifteenth Street, Augusta, GA 30912-2450, United States
| | - Alvin V Terry
- Department of Pharmacology and Toxicology, CB-3545, Georgia Regents University, 1120 Fifteenth Street, Augusta, GA 30912-2450, United States.
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6
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The nicotine metabolite, cotinine, attenuates glutamate (NMDA) antagonist-related effects on the performance of the five choice serial reaction time task (5C-SRTT) in rats. Biochem Pharmacol 2012; 83:941-51. [PMID: 22244928 DOI: 10.1016/j.bcp.2011.12.043] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 12/29/2011] [Accepted: 12/30/2011] [Indexed: 12/11/2022]
Abstract
Cotinine, the most predominant metabolite of nicotine in mammalian species, has a pharmacological half-life that greatly exceeds its precursor. However, until recently, relatively few studies had been conducted to systematically characterize the behavioral pharmacology of cotinine. Our previous work indicated that cotinine improves prepulse inhibition of the auditory startle response in rats in pharmacological impairment models and that it improves working memory in non-human primates. Here we tested the hypothesis that cotinine improves sustained attention in rats and attenuates behavioral alterations induced by the glutamate (NMDA) antagonist MK-801. The effects of acute subcutaneous (dose range 0.03-10.0 mg/kg) and chronic oral administration (2.0 mg/kg/day in drinking water) of cotinine were evaluated in fixed and variable stimulus duration (VSD) as well as variable intertrial interval (VITI) versions of a five choice serial reaction time task (5C-SRTT). The results indicated only subtle effects of acute cotinine (administered alone) on performance of the 5C-SRTT (e.g., decreases in timeout responses). However, depending on dose, acute treatment with cotinine attenuated MK-801-related impairments in accuracy and elevations in timeout responses, and it increased the number of completed trials. Moreover, chronic cotinine attenuated MK-801-related impairments in accuracy and it reduced premature and timeout responses when the demands of the task were increased (i.e., by presenting VSDs or VITIs in addition to administering MK-801). These data suggest that cotinine may represent a prototype for compounds that have therapeutic potential for neuropsychiatric disorders (i.e., by improving sustained attention and decreasing impulsive and compulsive behaviors), especially those characterized by glutamate receptor alterations.
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Hauser SR, Getachew B, Oster SM, Dhaher R, Ding ZM, Bell RL, McBride WJ, Rodd ZA. Nicotine modulates alcohol-seeking and relapse by alcohol-preferring (P) rats in a time-dependent manner. Alcohol Clin Exp Res 2011; 36:43-54. [PMID: 21689122 DOI: 10.1111/j.1530-0277.2011.01579.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND Alcohol is frequently co-abused with smoking. In humans, nicotine use can increase alcohol craving and consumption. The objectives of the current study were to assess the acute effects of nicotine on alcohol seeking and relapse at 2 different time points. METHODS Adult female alcohol-preferring (P) rats were trained in 2-lever operant chambers to self-administer 15% ethanol (EtOH) (v/v) and water on a concurrent fixed-ratio 5-fixed-ratio 1 (FR5-FR1) schedule of reinforcement in daily 1-hour sessions. Following 10 weeks of daily 1-hour sessions, rats underwent 7 extinction sessions, followed by 2 weeks in their home cages. Rats were then returned to the operant chambers without EtOH or water being present for 4 sessions (Pavlovian Spontaneous Recovery [PSR]). Rats were then given a week in their home cage before being returned to the operant chambers with access to EtOH and water (relapse). Nicotine (0, 0.1, 0.3, or 1.0 mg/kg) was injected subcutaneously immediately or 4 hours prior to PSR or relapse testing. RESULTS Injections of nicotine immediately prior to testing reduced (5 to 10 responses PSR; 50 to 60 responses relapse), whereas injections of nicotine 4 hours prior to testing increased (up to 150 responses for PSR; up to 400 responses for relapse with 1.0 mg/kg dose) responses on the EtOH lever during PSR and relapse tests. CONCLUSIONS The results of this study demonstrate that acute effects of nicotine on EtOH-seeking and relapse behaviors may be time dependent, with the immediate effects being a result of nicotine possibly acting as a substitute for EtOH, whereas with a delay of 4 hours, priming effects of nicotine alterations in nicotinic receptors, and/or the effects of nicotine's metabolites (i.e., cotinine and nornicotine) may enhance the expression of EtOH-seeking and relapse behaviors.
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Affiliation(s)
- Sheketha R Hauser
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indiana University-Purdue University at Indianapolis, 46202-4887, USA.
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8
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O'Leary K, Parameswaran N, McIntosh JM, Quik M. Cotinine selectively activates a subpopulation of alpha3/alpha6beta2 nicotinic receptors in monkey striatum. J Pharmacol Exp Ther 2008; 325:646-54. [PMID: 18305015 DOI: 10.1124/jpet.108.136838] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The nicotine metabolite cotinine is an abundant long-lived bio-active compound that may contribute to the overall physiological effects of tobacco use. Although its mechanism of action in the central nervous system has not been extensively investigated, cotinine is known to evoke dopamine release in the nigrostriatal pathway through an interaction at nicotinic receptors (nAChRs). Because considerable evidence now demonstrates the presence of multiple nAChRs in the striatum, the present experiments were done to determine the subtypes through which cotinine exerts its effects in monkeys, a species that expresses similar densities of striatal alpha4beta2* (nAChR containing the alpha4 and beta2 subunits, but not alpha3 or alpha6) and alpha3/alpha6beta2* (nAChR composed of the alpha3 or alpha6 subunits and beta2) nAChRs. Competition binding studies showed that cotinine interacts with both alpha4beta2* and alpha3/alpha6beta2* nAChR subtypes in the caudate, with cotinine IC(50) values for inhibition of 5-[(125) I]iodo-3-[2(S)-azetinylmethoxy]pyridine-2HCl ([(125)I]A-85380) and (125)I-alpha-conotoxinMII binding in the micromolar range. This interaction at the receptor level is of functional significance because cotinine stimulated both alpha4beta2* and alpha3/alpha6beta2* nAChR [(3)H]dopamine release from caudate synaptosomes. Our results unexpectedly showed that nicotine evokes [(3)H]dopamine release from two alpha3/alpha6beta2* nAChR populations, one of which was sensitive to cotinine and the other was not. This cotinine-insensitive subtype was only present in the medial caudate and was preferentially lost with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced nigrostriatal damage. In contrast, cotinine and nicotine elicited equivalent levels of alpha4beta2* nAChR-mediated dopamine release. These data demonstrate that cotinine functionally discriminates between two alpha3/alpha6beta2* nAChRs in monkey striatum, with the cotinine-insensitive alpha3/alpha6beta2* nAChR preferentially vulnerable to nigrostriatal damage.
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Affiliation(s)
- Kathryn O'Leary
- The Parkinson's Institute, 675 Almanor Ave., Sunnyvale, CA 94085-2934, USA
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Pogocki D, Ruman T, Danilczuk M, Danilczuk M, Celuch M, Wałajtys-Rode E. Application of nicotine enantiomers, derivatives and analogues in therapy of neurodegenerative disorders. Eur J Pharmacol 2007; 563:18-39. [PMID: 17376429 DOI: 10.1016/j.ejphar.2007.02.038] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 02/04/2007] [Accepted: 02/15/2007] [Indexed: 12/21/2022]
Abstract
This review gives a brief overview over the major aspects of application of the nicotine alkaloid and its close derivatives in the therapy of some neurodegenerative disorders and diseases (e.g. Alzheimer's disease, Parkinson's disease, Tourette's syndrome, schizophrenia etc.). The issues concerning methods of nicotine analysis and isolation, and some molecular aspects of nicotine pharmacology are included. The natural and synthetic analogues of nicotine that are considered for medical practice are also mentioned. The molecular properties of two naturally occurring nicotine enantiomers are compared--the less-common but less-toxic (R)-nicotine is suggested as a natural compound that may find its place in pharmaceutical practice.
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Affiliation(s)
- Dariusz Pogocki
- Rzeszów University of Technology, Faculty of Chemistry, Department of Biochemistry and Biotechnology, 6 Powstańców Warszawy Ave. 35-959 Rzeszów, Poland
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Riah O, Dousset JC, Bofill-Cardona E, Courrière P. Isolation and microsequencing of a novel cotinine receptor. Cell Mol Neurobiol 2000; 20:653-64. [PMID: 11100974 DOI: 10.1023/a:1007094623775] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
1. Nicotine and its main derivative. cotinine, are reported to have distinct central activities in mammals. In this study, the cotinine receptor was separated by biochemical procedures including radio receptor, affinity-chromatography, SDS-PAGE, and N-terminal sequencing assays. 2. Consistently, the results showed that distinctive cotinine receptors exist in different tissues of mammals. In rat brain, the affinity chromatography and [125I]cotinine receptor essays were used to isolate a 40-kDa protein (p40) with higher affinity for cotinine than alpha-bungarotoxin and nicotine. The N-terminus amino acid sequences of the p40 and its internal tryptic peptides showed no identity to recently described protein sequences, with the exception of homology to the human p205 synovial fluid protein. 3. These results, in agreement with other behavioral studies, are the first molecular evidence for distinctive nicotine and cotinine receptors in mammals.
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Affiliation(s)
- O Riah
- Laboratoire des Mécanismes d'Action des Nicotianées, Faculté des Sciences Pharmaceutiques, Toulouse, France.
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11
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Copeland JR, Adem A, Jacob P, Nordberg A. A comparison of the binding of nicotine and nornicotine stereoisomers to nicotinic binding sites in rat brain cortex. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1991; 343:123-7. [PMID: 2067586 DOI: 10.1007/bf00168598] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Both stereoisomers of nicotine and nornicotine were tested for their ability to competitively displace 3H-(-)-nicotine and 3H-acetylcholine (in the presence of atropine), in rat cortex tissue. 3H-acetylcholine was displaced from two binding sites, super-high and high, by (+)-nicotine, (-)-nornicotine and (+)-nornicotine but from a high affinity site by (-)-nicotine. 3H-nicotine was displaced from two sites, high and low affinity by nicotine and nornicotine stereoisomers. The high-affinity 3H-(-)-nicotine binding site showed similar binding characteristics to one of the sites labelled by 3H-acetylcholine. IC50 values showed (-)-nicotine to be 13 and 25-fold more potent than (+)-nicotine for displacing 3H-(-)-nicotine and 3H-acetylcholine, respectively, but no difference was observed for nornicotine stereoisomers. While (-)-nicotine preferentially bound to the high affinity site of 3H-(-)-nicotine (+)-nicotine preferred the low affinity site. The study provides further evidence for multiple nicotine receptors in brain.
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Affiliation(s)
- J R Copeland
- Department of Pharmacology, Uppsala University, Sweden
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12
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Clarke PB. Mapping of brain nicotinic receptors by autoradiographic techniques and the effect of experimental lesions. PROGRESS IN BRAIN RESEARCH 1989; 79:65-71. [PMID: 2685908 DOI: 10.1016/s0079-6123(08)62465-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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13
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Lippiello PM. Properties of putative nicotine receptors identified on cultured cortical neurons. PROGRESS IN BRAIN RESEARCH 1989; 79:129-35. [PMID: 2587739 DOI: 10.1016/s0079-6123(08)62472-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Cultured cortical neurons derived from fetal rat brain contain putative high-affinity nicotinic receptors. Cortical glial cells do not contain any high-affinity binding sites for nicotine. The affinity, kinetic binding properties and pharmacological specificity of neuronal sites are the same as those determined for adult brain tissue. However, the number of sites in cultured neurons is lower than in adult cortex. Cultured cortical neurons appear to be a suitable model system for defining the location(s) and functional properties of high-affinity nicotinic receptors in mammalian brain.
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14
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Abood L, Banerjee S, Kanne D. Sites, Mechanisms, and Structural Characteristics of the Brain's Nicotine Receptor. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/s0899-3289(18)30003-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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15
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Scimeca JA, Martin BR. The effect of acute dyflos (DFP) treatment on [3H]nicotine binding to mouse brain homogenate. J Pharm Pharmacol 1988; 40:793-7. [PMID: 2907560 DOI: 10.1111/j.2042-7158.1988.tb05174.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
One possible adaptive mechanism that might arise due to inhibition of cholinesterase in the brain is a down regulation of central cholinergic receptors. Therefore studies were performed to determine the effect of acute dyflos exposure on [3H]nicotine binding. Specific [3H] nicotine binding was demonstrated to be saturable, reversible, stereospecific, and inhibited by a number of nicotinic compounds. Scatchard analysis of specific [3H] nicotine binding produced a curvilinear plot that was resolved into high- and low-affinity sites with Kd values of 6.1 +/- 2.5 and 114 +/- 13 nM, and Bmax values of 11.8 +/- 3.5 and 182 +/- 24 fmol (mg protein)-1, respectively. The nicotinic binding sites in brain homogenate from dyflos-treated mice that were killed 20 min or 10 h after exposure did not exhibit significant alterations in binding parameters from control mouse brain homogenate. However, brain homogenate from treated mice that were killed 24 h after exposure resulted in statistically significant differences in the low-affinity K(D) and Bmax values from controls. Since no alterations were found in the high-affinity binding parameters and dyflos had only a minimal effect on the low-affinity site at 24 h, it was concluded that nicotinic receptor down regulation does not appear to be the mechanism through which the mouse functionally adapts to cholinesterase inhibition caused by acute dyflos treatment.
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Affiliation(s)
- J A Scimeca
- Department of Pharmacology and Toxicology, Medical College of Virginia-Virginia Commonwealth University, Richmond 23298
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16
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Abood LG, Shahid Salles K, Maiti A. Structure-activity studies of carbamate and other esters: agonists and antagonists to nicotine. Pharmacol Biochem Behav 1988; 30:403-8. [PMID: 3174772 DOI: 10.1016/0091-3057(88)90475-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A number of aromatic, cycloalkyl, and heterocyclic carbamic acid esters, thiocarbamic acid esters, and carboxylic acid esters of di- and trial-kylaminoalkyl and heterocyclic amino alcohols have been synthesized and tested for their pharmacologic and receptor binding characteristics at the nicotine receptor. Receptor binding was measured in rat brain membranes using (-)-3H-nicotine or 3H-methylcarbamylcholine as radioligands. The compounds were tested for their ability to produce seizures and prostration and to antagonize the nicotine-induced prostration and seizures as well as the hypertensive action of nicotine in rats. Among the potent agonists were the N-methylcarbamyl and N-methylthiocarbamyl esters of choline (trimethylaminoethanol), with the tertiary amino derivatives between considerably less potent than the quaternary. Potent antagonists included trimethylaminoethyl benzoate, 3-quinuclidinyl benzoate, and trimethylaminoethyl esters of phenyl and phenylthiocarbamic acids. One of the most potent antagonists to nicotine was alpha-lobeline.
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Affiliation(s)
- L G Abood
- Department of Pharmacology, University of Rochester, School of Medicine and Dentistry, NY 14642
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17
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Sloan JW, Martin WR, Bostwick M, Hook R, Wala E. The comparative binding characteristics of nicotinic ligands and their pharmacology. Pharmacol Biochem Behav 1988; 30:255-67. [PMID: 3174751 DOI: 10.1016/0091-3057(88)90454-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Five drugs [(-)- and (+)-nicotine, (-)-lobeline, (-)-anabasine and (-)-cytisine] were infused IV into the urethane-pentobarbital anesthetized rat. Changes in heart rate, blood pressure, respiratory rate, minute and tidal volume, which appeared to be largely centrally mediated, were studied. Each of these compounds produced different pharmacologic profiles. The nature of these dissimilarities is not readily explained on the basis of pharmacokinetic considerations suggesting that the drugs have different mechanisms of action. Binding data obtained with these compounds using the rat brain P2 preparation also show differences. (-)-Lobeline and (-)-anabasine, like the nicotinic antagonists mecamylamine and hexamethonium, bind predominantly to low affinity sites with KDs in the micromolar range whereas (-)-cytisine binds only to a single high affinity site with a KD in the nanomolar range. Further, the binding patterns of these drugs are different from (-)- and (+)-nicotine which bind to both high and low affinity sites but differ from each other in binding characteristics. Thus the binding data are consistent with the pharmacologic data in suggesting that the drugs have different modes of action and support the concept that the low affinity site has an important role in the central nervous system action of these compounds.
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Affiliation(s)
- J W Sloan
- University of Kentucky, College of Medicine, Department of Pharmacology, Lexington 40536
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18
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Stolerman IP. Characterization of central nicotinic receptors by studies on the nicotine cue and conditioned taste aversion in rats. Pharmacol Biochem Behav 1988; 30:235-42. [PMID: 3174748 DOI: 10.1016/0091-3057(88)90451-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Some recent studies on the discriminative stimulus (cue) and conditioned taste aversion (CTA) effects of nicotine are reviewed. The characteristics of the nicotine cue correlate well with those of high affinity nicotine binding in studies comparing different nicotinic agonists. The dose of nicotine used for training a discrimination is an important variable determining patterns of generalization. The effects of antagonists on the nicotine cue are also compatible with ligand-binding studies although the lack of competitive antagonists generates unsolved problems for investigators. The CTA produced by nicotine has pharmacological characteristics like the nicotine cue. Both effects are produced at CNS sites that resemble to a certain extent the cholinoceptive sites in autonomic ganglia. The small differences in the degree of stereoselectivity of the two effects or in their sensitivity to antagonists do not constitute substantive evidence for mediation by different receptors. The major differences between the procedures lies in their general psychopharmacological characteristics rather than in any special qualities of the response to nicotine. For example, the nicotine cue is not produced by agents from other pharmacological classes whereas a wide range of different drugs can produce CTA. The concept of multiple types of CNS nicotinic receptors, as supported by certain biochemical studies, requires further evaluation in behavioural systems.
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Affiliation(s)
- I P Stolerman
- Department of Pharmacology, Institute of Psychiatry, De Crespigny Park, London
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19
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Martin WR, Kumar S, Sloan JW. Opioid and nicotinic medullary hyperalgesic influences in the decerebrated rat. Pharmacol Biochem Behav 1988; 29:725-31. [PMID: 2901113 DOI: 10.1016/0091-3057(88)90194-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effects of ethylketazocine (EKC) administered intraperitoneally and the nicotinic ligands (-)- and (+)-nicotine, (-)-cytisine, (-)-lobeline, and (+)-2-methylpiperidine administered into the 4th ventricle on the latency of the thermally evoked withdrawal reflex of the decerebrate rat were investigated. EKC administered intraperitoneally produced both hyperalgesia and analgesia. (-)-Nicotine administered into the 4th ventricle produced a biphasic dose related effect on the latency of the withdrawal reflex; low doses produced a dose related analgesia while higher doses produced hyperalgesia. (-)-Cytisine and (-)-lobeline administered into the 4th ventricle produced biphasic effects. (+)-2-Methylpiperidine administered into the 4th ventricle produced a significant degree of hyperalgesia. Both the analgesic and hyperalgesic effects of (-)-nicotine were antagonized by mecamylamine (1 mg/kg) and naltrexone (5 mg/kg). The hyperalgesic action of (+)-2-methylpiperidine was antagonized by naltrexone but not by mecamylamine. These observations suggest that there are both medullary opioidergic and nicotinic cholinergic mechanisms for modulating both analgesic and hyperalgesic processes and that nicotinic ligands have multiple mechanisms of action in the brain.
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Affiliation(s)
- W R Martin
- Department of Pharmacology, University of Kentucky College of Medicine, Lexington 40536
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20
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Reavill C, Jenner P, Kumar R, Stolerman IP. High affinity binding of [3H] (-)-nicotine to rat brain membranes and its inhibition by analogues of nicotine. Neuropharmacology 1988; 27:235-41. [PMID: 3374769 DOI: 10.1016/0028-3908(88)90039-1] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Analysis of the characteristics of cerebral binding of [3H] (-)-nicotine revealed a single population of sites with high affinity (KD = 6.0 +/- 0.6 nM). The regional distribution of the binding of [3H] (-)-nicotine was heterogeneous with the largest concentration of binding sites being in the thalamus, cortex and striatum, and a low level of binding activity in the cerebellum and hypothalamus. Competition studies showed that several metabolites and congeners of nicotine potently competed with [3H] (-)-nicotine and their in vitro activity was correlated with behavioural activity, as estimated from previously published data for rats trained to discriminate central effects of nicotine. Conversely, nicotine antagonists, with the exception of dihydro-beta-erythroidine, were weak or inactive in this binding assay. It is concluded that the binding site for [3H] (-)-nicotine investigated probably mediates at least one of the behavioural effects of nicotine, the nicotine discrimative stimulus.
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Affiliation(s)
- C Reavill
- Department of Psychiatry, Institute of Psychiatry, London, U.K
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21
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Stolerman IP, Kumar R, Reavill C. Discriminative stimulus effects of cholinergic agonists and the actions of their antagonists. PSYCHOPHARMACOLOGY SERIES 1988; 4:32-43. [PMID: 3293044 DOI: 10.1007/978-3-642-73223-2_3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Both muscarinic- and nicotinic-cholinergic agonists have been used for discrimination training, but only nicotine has been studied extensively. The limited information available suggests that the discriminative stimulus effects of drugs classified as muscarinic-cholinergic agonists are blocked competitively by atropine but not by ganglion-blockers. The discriminative effects of nicotine are blocked non-competitively by ganglion-blocking drugs that penetrate into the CNS (e.g. mecamylamine), but they are not blocked by atropine. The specificity of the block is shown by the failure of mecamylamine to block several non-nicotinic drugs. The ganglion-blocking drug chlorisondamine penetrates poorly into the CNS when injected systemically; when injected intraventricularly, it is a potent and specific nicotine antagonist with a 4-week duration of effect. Haloperidol attenuates discriminative effects of nicotine but this is not a specific block; there are marked reductions in response rate, the morphine stimulus is also attenuated, and other neuroleptics have much weaker effects. The results support the view that the discriminative effect of nicotine involves predominantly cholinoceptive sites, and they suggest that it is not mediated primarily by the dopamine system. The transduction mechanisms for the nicotine stimulus may include the receptor sites that mediate many of its other CNS effects, but more information is needed about possible subtypes of nicotinic receptors before definitive conclusions are possible.
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Affiliation(s)
- I P Stolerman
- Department of Pharmacology, Institute of Psychiatry, London, UK
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22
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Schmidt J. Biochemistry of nicotinic acetylcholine receptors in the vertebrate brain. INTERNATIONAL REVIEW OF NEUROBIOLOGY 1988; 30:1-38. [PMID: 3061965 DOI: 10.1016/s0074-7742(08)60045-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- J Schmidt
- Department of Biochemistry, State University of New York, Stony Brook 11794
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23
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Collins AC, Romm E, Wehner JM. Nicotine tolerance: an analysis of the time course of its development and loss in the rat. Psychopharmacology (Berl) 1988; 96:7-14. [PMID: 3147478 DOI: 10.1007/bf02431526] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The time course of the development and loss of tolerance to nicotine was measured in female rats that were injected subcutaneously (SC), twice daily with 1.6 mg/kg nicotine. Tolerance to nicotine-induced decreases in locomotor activity and body temperature were observed. Tolerance to the effects of nicotine on both of these measures developed rapidly, with maximal changes occurring within 2-4 days after initiation of treatment. The binding of L-[3H]-nicotine was measured in six brain regions. Chronic nicotine treatment resulted in increases in binding in most brain regions. The increase in binding correlated significantly with the development of tolerance. Rats that had been injected chronically with nicotine did not lose their tolerance throughout a 7-day post-treatment test period. Control levels of binding were regained in all of the brain regions except cortex by 7 days after nicotine treatment was stopped. These findings indicate that changes in receptor binding may relate to the development of tolerance but the retention of tolerance is clearly not related to the number of brain nicotinic receptors, unless nicotine-induced decreases in body temperature and locomotor activity are controlled by cortical [3H]-nicotine binding sites.
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Affiliation(s)
- A C Collins
- Institute for Behavioral Genetics, University of Colorado, Boulder 80309
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Abood LG, Langone JJ, Bjercke R, Lu X, Banerjee S. Characterization of a purified nicotinic receptor from rat brain by using idiotypic and anti-idiotypic antibodies. Proc Natl Acad Sci U S A 1987; 84:6587-90. [PMID: 3498166 PMCID: PMC299124 DOI: 10.1073/pnas.84.18.6587] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The availability of an anti-nicotine monoclonal antibody has made it possible to further establish the nature of the nicotine recognition proteins purified from rat brain by affinity chromatography and to provide a highly sensitive assay for determining [3H]nicotine binding to the purified material. An enantiomeric analogue of nicotine, (-)-6-hydroxymethyl-nicotine, was used to prepare the affinity column. In addition, with the use of anti-idiotypic monoclonal antibody, it was confirmed that the recognition site for nicotine resides on a protein complex composed of two components with molecular masses of 62 and 57 kDa. It was also demonstrated that the same two proteins could be purified by immunoaffinity chromatography with the use of an anti-idiotypic monoclonal antibody. With the use of the anti-nicotine antibody to measure [3H]nicotine binding, the purified material was shown to bind 250 pmol/mg of protein. By utilizing a procedure in which the purified receptor protein was conjugated to membranes by disulfide bonds, a binding activity of 80 pmol/mg was obtained. With the availability of stereospecific monoclonal antibodies to (-)-nicotine as well as monoclonal anti-idiotypic antibodies derived when the anti-nicotine antibodies were used as immunogens, additional procedures became available for the further characterization of the purified nicotine receptor and examining its (-)-[3H]nicotine-binding characteristics.
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25
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Affiliation(s)
- S Wonnacott
- Department of Biochemistry, University of Bath, UK
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26
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Edwards DA, Mather RA, Shirley SG, Dodd GH. Evidence for an olfactory receptor which responds to nicotine--nicotine as an odorant. EXPERIENTIA 1987; 43:868-73. [PMID: 3622727 DOI: 10.1007/bf01951644] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The tobacco alkaloid (S)(-)-nicotine, when applied as a vapour to an in vitro head preparation, stimulates the olfactory epithelium in three strains of rats and to a lesser extent in two strains of mice. The electro-olfactogram (EOG) generated by nicotine has similar characteristics to the EOGs produced by known odorants. The nicotine EOG increases with increasing concentration of nicotine vapour (1-100 nM) applied to the olfactory epithelium. Differential reduction of the nicotine EOG by the lectin concanavalin A is seen in Wistar and Lister Hooded rats. The reduction of the nicotine EOG by concanavalin A is prevented by adding alpha-methyl-D-mannoside to the lectin superfusion medium. This suggests that there is a glyco-moiety associated with at least one olfactory receptor responding to nicotine. Our results suggest that rat olfactory epithelium has receptor sites for nicotine. Nicotine is an unusual compound because it shows both odorant and pharmacological properties.
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27
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Current Concepts on the Effects of Nicotine on Neurotransmitter Release in the Central Nervous System. ACTA ACUST UNITED AC 1987. [DOI: 10.1007/978-1-4613-1911-5_13] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
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Kumar R, Reavill C, Stolerman IP. Nicotine cue in rats: effects of central administration of ganglion-blocking drugs. Br J Pharmacol 1987; 90:239-46. [PMID: 2880625 PMCID: PMC1917277 DOI: 10.1111/j.1476-5381.1987.tb16845.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
In rats trained to discriminate nicotine from saline, a single intraventricular injection of a small dose of the quaternary ganglion-blocking drug chlorisondamine blocked the response to nicotine for four weeks. pentolinium was only weakly active and hexamethonium was inactive as a nicotine antagonist under the conditions used, even in doses that were just below those producing myoclonic jerks. Chlorisondamine had no blocking effect in rats trained to discriminate the non-nicotinic drugs midazolam or morphine from saline. Intraventricular injections of chlorisondamine have a specific and unusually persistent nicotine-blocking action, the mechanism of which requires further investigation.
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Abstract
Reported differences in the pharmacology and distribution of [3H]nicotine and [125I]alpha-bungarotoxin binding sites in mammalian brain suggest that these ligands label separate receptor sites. Affinity purification of an alpha-bungarotoxin binding protein from rat brain failed to copurify the high-affinity nicotine binding site, which remained in the nonbound soluble fraction after the affinity chromatography step. This confirms the independence of these putative receptor sites. Nevertheless, the binding of [125I]alpha-bungarotoxin to P2 membranes was inhibited by (-)-nicotine (Ki = 9 X 10(-6) M), and this sensitivity was preserved after affinity purification. It is proposed that alpha-bungarotoxin binds to a population of low-affinity nicotine binding sites. Comparison of the enantiomers of nicotine in competition studies at both radioligand binding sites revealed an 80-fold preference for the (-) form at the high-affinity [3H]nicotine binding site, whereas the site labelled by [125I]alpha-bungarotoxin displayed little stereoselectivity. In this respect, the brain alpha-bungarotoxin binding site resembles the nicotinic acetylcholine receptor from Torpedo electric organ.
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32
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Stolerman IP. Could nicotine antagonists be used in smoking cessation? BRITISH JOURNAL OF ADDICTION 1986; 81:47-53. [PMID: 3516190 DOI: 10.1111/j.1360-0443.1986.tb00292.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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33
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Kachur JF, May EL, Awaya H, Egle JL, Aceto MD, Martin BR. Pharmacological effects of 1,2,3,5,6,10b-hexahydropyrido[2,3g]indolizine, a bridged-nicotine analog. Life Sci 1986; 38:323-30. [PMID: 3945165 DOI: 10.1016/0024-3205(86)90079-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The racemate of a bridged-nicotine (BN) analog was synthesized and resolved into its enantiomers for pharmacological comparisons to (+)- and (-)-nicotine. The EC50 values for (-)- and (+)-nicotine and (-)- and (+)-BN were 4, 170, 53 and 400 microM, respectively, for producing contractions of guinea-pig ilea. (-)-Nicotine was an effective antinociceptive agent in the mouse tail-flick procedure at i.v. doses of 0.1-0.3 mg/kg, whereas the isomers of BN failed to alter tail-flick response in doses up to 5 mg/kg. (-)-Nicotine (0.01-0.3 mg/kg, i.v.) increased blood pressure and decreased heart rate in anesthetized rats. Neither (+)- nor (-)-BN altered blood pressure and heart rate in rats in this dosage range. At doses of 3-100 mg/kg, (+)-BN produced an increase in blood pressure without changing heart rate, while (-)-BN decreased both blood pressure and heart rate. Bridging the pyrrolidine and pyridine rings decreased biologic activity and did not result in stereoselectivity greater than that observed with (+)- and (-)-nicotine. It appears that there may be subpopulations of nicotine receptors to which the isomers of BN do not interact.
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Sloan JW, Martin WR, Hernandez J, Hook R. Binding characteristics of (-)- and (+)-nicotine to the rat brain P2 fraction. Pharmacol Biochem Behav 1985; 23:987-93. [PMID: 4080783 DOI: 10.1016/0091-3057(85)90105-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Saturation studies employing (-)- and (+)-[3H]nicotine indicate that the isomers bind to different very high and high affinity sites since the binding density for (-)-[3H]nicotine is 10 times that for (+)-[3H]nicotine. Both isomers also bind to a low affinity site (KDS = approximately 10(-5) to 10(-4) M). Competition studies employing unlabelled (-)- and (+)-nicotine reveal greater complexities. The isomers also appear to bind to a separate site which enhances binding at the (-)- and (+)-nicotine high affinity sites. (+)-Nicotine is more effective in increasing the binding of (-)-[3H]nicotine at its high affinity site than (-)-nicotine. Further, (+)-nicotine has a greater specificity for enhancing binding than (-)-nicotine in that it enhances (-)-[3H]nicotine binding at lower concentrations and inhibits binding at higher concentrations than (-)-nicotine.
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Sloan JW, Martin WR, Hook R, Bostwick M, Howell A, Smith WT. Stereospecificity of 2-methylpiperidine binding to a nicotinic up-regulatory site in the rat brain P2 preparation. Life Sci 1985; 37:1367-72. [PMID: 4046738 DOI: 10.1016/0024-3205(85)90074-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
(+/-)-2-Methylpiperidine has a high degree of specificity in enhancing the binding of (-)-[3H]nicotine in the rat brain P2 preparation. (-)- and (+)-2-Methylpiperidine have been resolved. The (+) but not the (-) isomer increased the binding of (-)-[3H]nicotine. The two isomers were equally effective in inhibiting the binding of (-)-[3H]nicotine in high concentrations. These data provide additional support for a stereospecific nicotinic up-regulatory site.
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Abood LG, Grassi S, Noggle HD. Comparison of the binding of optically pure (-)- and (+)- [3H]nicotine to rat brain membranes. Neurochem Res 1985; 10:259-67. [PMID: 3990894 DOI: 10.1007/bf00964572] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A comparison of the binding of (-)- and (+)-[3H]nicotine to rat brain membranes revealed that only the (-)-enantiomer showed high affinity binding; while the (+)-enantiomer was at least 1/10 as effective as the (-)-enantiomer when in competition with (-)-[3H]nicotine as the ligand. Positive cooperativity, which is observed with (-)-[3H]nicotine in the presence of low concentrations of (+)-nicotine, may account for the seeming paradox.
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