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Smart K, Naganawa M, Baldassarri SR, Nabulsi N, Ropchan J, Najafzadeh S, Gao H, Navarro A, Barth V, Esterlis I, Cosgrove KP, Huang Y, Carson RE, Hillmer AT. PET Imaging Estimates of Regional Acetylcholine Concentration Variation in Living Human Brain. Cereb Cortex 2021; 31:2787-2798. [PMID: 33442731 PMCID: PMC8355478 DOI: 10.1093/cercor/bhaa387] [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: 08/04/2020] [Revised: 11/06/2020] [Accepted: 12/01/2020] [Indexed: 11/13/2022] Open
Abstract
Acetylcholine (ACh) has distinct functional roles in striatum compared with cortex, and imbalance between these systems may contribute to neuropsychiatric disease. Preclinical studies indicate markedly higher ACh concentrations in the striatum. The goal of this work was to leverage positron emission tomography (PET) imaging estimates of drug occupancy at cholinergic receptors to explore ACh variation across the human brain, because these measures can be influenced by competition with endogenous neurotransmitter. PET scans were analyzed from healthy human volunteers (n = 4) and nonhuman primates (n = 2) scanned with the M1-selective radiotracer [11C]LSN3172176 in the presence of muscarinic antagonist scopolamine, and human volunteers (n = 10) scanned with the α4β2* nicotinic ligand (-)-[18F]flubatine during nicotine challenge. In all cases, occupancy estimates within striatal regions were consistently lower (M1/scopolamine human scans, 31 ± 3.4% occupancy in striatum, 43 ± 2.9% in extrastriatal regions, p = 0.0094; nonhuman primate scans, 42 ± 26% vs. 69 ± 28%, p < 0.0001; α4β2*/nicotine scans, 67 ± 15% vs. 74 ± 16%, p = 0.0065), indicating higher striatal ACh concentration. Subject-level measures of these concentration differences were estimated, and whole-brain images of regional ACh concentration gradients were generated. These results constitute the first in vivo estimates of regional variation in ACh concentration in the living brain and offer a novel experimental method to assess potential ACh imbalances in clinical populations.
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Affiliation(s)
- Kelly Smart
- Yale PET Center, Yale School of Medicine, New Haven, CT 06510, USA
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, CT 06520, USA
| | - Mika Naganawa
- Yale PET Center, Yale School of Medicine, New Haven, CT 06510, USA
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, CT 06520, USA
| | - Stephen R Baldassarri
- Department of Internal Medicine, Section of Pulmonary, Critical Care, and Sleep Medicine, Yale School of Medicine, New Haven, CT 06510, USA
| | - Nabeel Nabulsi
- Yale PET Center, Yale School of Medicine, New Haven, CT 06510, USA
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, CT 06520, USA
| | - Jim Ropchan
- Yale PET Center, Yale School of Medicine, New Haven, CT 06510, USA
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, CT 06520, USA
| | | | - Hong Gao
- Yale PET Center, Yale School of Medicine, New Haven, CT 06510, USA
| | | | | | - Irina Esterlis
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511, USA
| | - Kelly P Cosgrove
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, CT 06520, USA
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511, USA
| | - Yiyun Huang
- Yale PET Center, Yale School of Medicine, New Haven, CT 06510, USA
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, CT 06520, USA
| | - Richard E Carson
- Yale PET Center, Yale School of Medicine, New Haven, CT 06510, USA
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, CT 06520, USA
- Department of Biomedical Engineering, Yale University, New Haven, CT 06511, USA
| | - Ansel T Hillmer
- Yale PET Center, Yale School of Medicine, New Haven, CT 06510, USA
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, CT 06520, USA
- Department of Psychiatry, Yale School of Medicine, New Haven, CT 06511, USA
- Department of Biomedical Engineering, Yale University, New Haven, CT 06511, USA
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Newman LA, Gold PE. Attenuation in rats of impairments of memory by scopolamine, a muscarinic receptor antagonist, by mecamylamine, a nicotinic receptor antagonist. Psychopharmacology (Berl) 2016; 233:925-32. [PMID: 26660295 PMCID: PMC4752895 DOI: 10.1007/s00213-015-4174-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/23/2015] [Indexed: 01/08/2023]
Abstract
RATIONALE Scopolamine, a muscarinic antagonist, impairs learning and memory for many tasks, supporting an important role for the cholinergic system in these cognitive functions. The findings are most often interpreted to indicate that a decrease in postsynaptic muscarinic receptor activation mediates the memory impairments. However, scopolamine also results in increased release of acetylcholine in the brain as a result of blocking presynaptic muscarinic receptors. OBJECTIVES The present experiments assess whether scopolamine-induced increases in acetylcholine release may impair memory by overstimulating postsynaptic cholinergic nicotinic receptors, i.e., by reaching the high end of a nicotinic receptor activation inverted-U dose-response function. RESULTS Rats tested in a spontaneous alternation task showed dose-dependent working memory deficits with systemic injections of mecamylamine and scopolamine. When an amnestic dose of scopolamine (0.15 mg/kg) was co-administered with a subamnestic dose of mecamylamine (0.25 mg/kg), this dose of mecamylamine significantly attenuated the scopolamine-induced memory impairments. We next assessed the levels of acetylcholine release in the hippocampus in the presence of scopolamine and mecamylamine. Mecamylamine injections resulted in decreased release of acetylcholine, while scopolamine administration caused a large increase in acetylcholine release. CONCLUSIONS These findings indicate that a nicotinic antagonist can attenuate impairments in memory produced by a muscarinic antagonist. The nicotinic antagonist may block excessive activation of nicotinic receptors postsynaptically or attenuate increases in acetylcholine release presynaptically. Either effect of a nicotinic antagonist-to decrease scopolamine-induced increases in acetylcholine output or to decrease postsynaptic acetylcholine receptor activation-may mediate the negative effects on memory of muscarinic antagonists.
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Affiliation(s)
- L A Newman
- Department of Biology, Syracuse University, 114 Life Sciences Complex, Syracuse, NY, 13244, USA
| | - P E Gold
- Department of Biology, Syracuse University, 114 Life Sciences Complex, Syracuse, NY, 13244, USA.
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Takechi K, Suemaru K, Kiyoi T, Tanaka A, Araki H. The α4β2 nicotinic acetylcholine receptor modulates autism-like behavioral and motor abnormalities in pentylenetetrazol-kindled mice. Eur J Pharmacol 2016; 775:57-66. [PMID: 26868186 DOI: 10.1016/j.ejphar.2016.02.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 01/20/2016] [Accepted: 02/04/2016] [Indexed: 01/22/2023]
Abstract
Epilepsy is associated with several psychiatric disorders, including cognitive impairment, autism and attention deficit/hyperactivity disorder (ADHD). However, the psychopathology of epilepsy is frequently unrecognized and untreated in patients. In the present study, we investigated the effects of ABT-418, a neuronal nicotinic acetylcholine receptor agonist, on pentylenetetrazol (PTZ)-kindled mice with behavioral and motor abnormalities. PTZ-kindled mice displayed impaired motor coordination (in the rotarod test), anxiety (in the elevated plus maze test) and social approach impairment (in the three-chamber social test) compared with control mice. ABT-418 treatment (0.05 mg/kg, intraperitoneally) alleviated these behavioral abnormalities in PTZ-kindled mice. Immunolabeling of tissue sections demonstrated that expression of the α4 nicotinic acetylcholine receptor subunit in the medial habenula was similar in control and PTZ-kindled mice. However, expression was significantly decreased in the piriform cortex in PTZ-kindled mice. In addition, we examined the expression of the synaptic adhesion molecule neuroligin 3 (NLG3). NLG3 expression in the piriform cortex was significantly higher in PTZ-kindled mice compared with control mice. Collectively, our findings suggest that ADHD-like or autistic-like behavioral abnormalities associated with epilepsy are closely related to the downregulation of the α4 nicotinic receptor and the upregulation of NLG3 in the piriform cortex. In summary, this study indicates that ABT-418 might have therapeutic potential for attentional impairment in epileptic patients with psychiatric disorders such as autism and ADHD.
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Affiliation(s)
- Kenshi Takechi
- Division of Pharmacy, Ehime University Hospital, Shitsukawa, Toon, Ehime 791-0295, Japan.
| | - Katsuya Suemaru
- School of Pharmacy, Shujitsu University, 1-6-1 Nishikawara, Naka-ku, Okayama 703-8516, Japan
| | - Takeshi Kiyoi
- Integrated Center for Science, Ehime University, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Akihiro Tanaka
- Division of Pharmacy, Ehime University Hospital, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Hiroaki Araki
- Division of Pharmacy, Ehime University Hospital, Shitsukawa, Toon, Ehime 791-0295, Japan
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Nicotinic modulation of hippocampal cell signaling and associated effects on learning and memory. Physiol Behav 2015; 155:162-71. [PMID: 26687895 DOI: 10.1016/j.physbeh.2015.12.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 11/30/2015] [Accepted: 12/10/2015] [Indexed: 11/21/2022]
Abstract
The hippocampus is a key brain structure involved in synaptic plasticity associated with long-term declarative memory formation. Importantly, nicotine and activation of nicotinic acetylcholine receptors (nAChRs) can alter hippocampal plasticity and these changes may occur through modulation of hippocampal kinases and transcription factors. Hippocampal kinases such as cAMP-dependent protein kinase (PKA), calcium/calmodulin-dependent protein kinases (CAMKs), extracellular signal-regulated kinases 1 and 2 (ERK1/2), and c-jun N-terminal kinase 1 (JNK1), and the transcription factor cAMP-response element-binding protein (CREB) that are activated either directly or indirectly by nicotine may modulate hippocampal plasticity and in parallel hippocampus-dependent learning and memory. Evidence suggests that nicotine may alter hippocampus-dependent learning by changing the time and magnitude of activation of kinases and transcription factors normally involved in learning and by recruiting additional cell signaling molecules. Understanding how nicotine alters learning and memory will advance basic understanding of the neural substrates of learning and aid in understanding mental disorders that involve cognitive and learning deficits.
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Stevens KE, Zheng L, Floyd KL, Stitzel JA. Maximizing the effect of an α7 nicotinic receptor PAM in a mouse model of schizophrenia-like sensory inhibition deficits. Brain Res 2015; 1611:8-17. [PMID: 25744161 DOI: 10.1016/j.brainres.2015.02.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 02/20/2015] [Accepted: 02/21/2015] [Indexed: 12/30/2022]
Abstract
Positive allosteric modulators (PAMs) for the α7 nicotinic receptor hold promise for the treatment of sensory inhibition deficits observed in schizophrenia patients. Studies of these compounds in the DBA/2 mouse, which models the schizophrenia-related deficit in sensory inhibition, have shown PAMs to be effective in improving the deficit. However, the first published clinical trial of a PAM for both sensory inhibition deficits and related cognitive difficulties failed, casting a shadow on this therapeutic approach. The present study used both DBA/2 mice, and C3H Chrna7 heterozygote mice to assess the ability of the α7 PAM, PNU-120596, to improve sensory inhibition. Both of these strains of mice have reduced hippocampal α7 nicotinic receptor numbers and deficient sensory inhibition similar to schizophrenia patients. Low doses of PNU-120596 (1 or 3.33mg/kg) were effective in the DBA/2 mouse but not the C3H Chrna7 heterozygote mouse. Moderate doses of the selective α7 nicotinic receptor agonist, choline chloride (10 or 33mg/kg), were also ineffective in improving sensory inhibition in the C3H Chrna7 heterozygote mouse. However, combining the lowest doses of both PNU-120596 and choline chloride in this mouse model did improve sensory inhibition. We propose here that the difference in efficacy of PNU-120596 between the 2 mouse strains is driven by differences in hippocampal α7 nicotinic receptor numbers, such that C3H Chrna7 heterozygote mice require additional direct stimulation of the α7 receptors. These data may have implications for further clinical testing of putative α7 nicotinic receptor PAMs.
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Affiliation(s)
- Karen E Stevens
- Department of Psychiatry, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA.
| | - Lijun Zheng
- Department of Psychiatry, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Kirsten L Floyd
- Department of Psychiatry, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Jerry A Stitzel
- Institute for Behavioral Genetics, University of Colorado, Boulder, Boulder, CO, USA
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The novel α7 nicotinic acetylcholine receptor agonist EVP-6124 enhances dopamine, acetylcholine, and glutamate efflux in rat cortex and nucleus accumbens. Psychopharmacology (Berl) 2014; 231:4541-51. [PMID: 24810107 DOI: 10.1007/s00213-014-3596-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 04/20/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Alpha7 and α4β2 nicotinic acetylcholine receptor (nAChR) agonists have been shown to improve cognition in various animal models of cognitive impairment and are of interest as treatments for schizophrenia, Alzheimer's disease, and other cognitive disorders. Increased release of dopamine (DA), acetylcholine (ACh), glutamate (Glu), and γ-aminobutyric acid (GABA) in cerebral cortex, hippocampus, and nucleus accumbens (NAC) has been suggested to contribute to their beneficial effects on cognition. RESULTS Using in vivo microdialysis, we found that EVP-6124 [(R)-7-chloro-N-quinuclidin-3-yl)benzo[b]thiophene-2-carboxamide], a high-affinity α7 nAChR partial agonist, at 0.1 mg/kg, s.c., increased DA efflux in the medial prefrontal cortex (mPFC) and NAC. EVP-6124, 0.1 and 0.3 mg/kg, also increased efflux of ACh in the mPFC but not in the NAC. Similarly, EVP-6124, 0.1 mg/kg, but not 0.03 and 0.3 mg/kg, significantly increased mPFC Glu efflux. Thus, EVP-6124 produced an inverted U-shaped curve for DA and Glu release, as previously reported for other α7 nAChR agonists. The three doses of EVP-6124 did not produce a significant effect on GABA efflux in either region. Pretreatment with the selective α7 nAChR antagonist, methyllycaconitine (MLA, 1.0 mg/kg), significantly blocked cortical DA and Glu efflux induced by EVP-6124 (0.1 mg/kg), suggesting that the effects of EVP-6124 on these neurotransmitters were due to α7 nAChR agonism. MLA only partially blocked the effects of EVP-6124 on ACh efflux in the mPFC. CONCLUSION These results suggest increased cortical DA, ACh, and Glu release, which may contribute to the ability of the α7 nAChR agonist, EVP-6124, to treat cognitive impairment and possibly other dimensions of psychopathology.
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Huang M, Felix AR, Kwon S, Lowe D, Wallace T, Santarelli L, Meltzer HY. The alpha-7 nicotinic receptor partial agonist/5-HT3 antagonist RG3487 enhances cortical and hippocampal dopamine and acetylcholine release. Psychopharmacology (Berl) 2014; 231:2199-210. [PMID: 24317442 DOI: 10.1007/s00213-013-3373-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 11/21/2013] [Indexed: 12/16/2022]
Abstract
RATIONALE Alpha-7 nicotinic acetylcholine receptor (nAChR) agonists may ameliorate cognitive deficits in schizophrenia, in part, because of their ability to enhance dopaminergic and cholinergic neurotransmission. OBJECTIVES In the current study, the effects of partial nAChR agonist and 5-HT3 receptor antagonist RG3487 (previously R3487/MEM3454) on dopamine (DA) and acetylcholine (ACh) effluxes in rat prefrontal cortex (mPFC) and hippocampus (HIP) were investigated in awake, freely moving rats. RESULTS R3487/MEM3454, at doses of 0.1-10 mg/kg, s.c., enhanced DA and ACh effluxes in rat mPFC and (HIP), with a peak effect at 0.3- to 0.6-mg/kg doses, producing a bell-shaped dose-response curve. Pretreatment with the selective nAChR antagonist, methyllycaconitine (1.0 mg/kg), completely blocked RG3487-induced (0.45 mg/kg) DA but not ACh efflux, while the selective 5-HT3 receptor agonist 1-(m-chlorophenyl)-biguanide (1.0 mg/kg) partially inhibited cortical ACh but not DA efflux. RG3487 (0.45 mg/kg) combined with atypical antipsychotic drug (APD) risperidone (0.1 mg/kg), but not typical APD haloperidol (0.1 mg/kg), induced a significantly greater increase in HIP ACh efflux. Their combined effect on DA efflux was additive. RG3487, combined with other atypical APDs, namely aripiprazole (0.3 mg/kg), olanzapine (1.0 mg/kg), and quetiapine (30 mg/kg), also produced additive effects on DA efflux. CONCLUSIONS These results suggest that RG3487 enhances DA efflux by nAChR stimulation, whereas ACh efflux is primarily mediated via 5-HT3 receptor antagonism, and that RG3487 alone or as augmentation may improve cognitive impairment in schizophrenia.
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Affiliation(s)
- Mei Huang
- Division of Psychopharmacology, Vanderbilt University School of Medicine, Nashville, TN, 37212, USA
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Gould TJ, Leach PT. Cellular, molecular, and genetic substrates underlying the impact of nicotine on learning. Neurobiol Learn Mem 2013; 107:108-32. [PMID: 23973448 DOI: 10.1016/j.nlm.2013.08.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Revised: 08/13/2013] [Accepted: 08/13/2013] [Indexed: 12/27/2022]
Abstract
Addiction is a chronic disorder marked by long-lasting maladaptive changes in behavior and in reward system function. However, the factors that contribute to the behavioral and biological changes that occur with addiction are complex and go beyond reward. Addiction involves changes in cognitive control and the development of disruptive drug-stimuli associations that can drive behavior. A reason for the strong influence drugs of abuse can exert on cognition may be the striking overlap between the neurobiological substrates of addiction and of learning and memory, especially areas involved in declarative memory. Declarative memories are critically involved in the formation of autobiographical memories, and the ability of drugs of abuse to alter these memories could be particularly detrimental. A key structure in this memory system is the hippocampus, which is critically involved in binding multimodal stimuli together to form complex long-term memories. While all drugs of abuse can alter hippocampal function, this review focuses on nicotine. Addiction to tobacco products is insidious, with the majority of smokers wanting to quit; yet the majority of those that attempt to quit fail. Nicotine addiction is associated with the presence of drug-context and drug-cue associations that trigger drug seeking behavior and altered cognition during periods of abstinence, which contributes to relapse. This suggests that understanding the effects of nicotine on learning and memory will advance understanding and potentially facilitate treating nicotine addiction. The following sections examine: (1) how the effects of nicotine on hippocampus-dependent learning change as nicotine administration transitions from acute to chronic and then to withdrawal from chronic treatment and the potential impact of these changes on addiction, (2) how nicotine usurps the cellular mechanisms of synaptic plasticity, (3) the physiological changes in the hippocampus that may contribute to nicotine withdrawal deficits in learning, and (4) the role of genetics and developmental stage (i.e., adolescence) in these effects.
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Affiliation(s)
- Thomas J Gould
- Temple University Department of Psychology, Neuroscience Program, Temple University, Philadelphia, PA 19122, United States.
| | - Prescott T Leach
- Temple University Department of Psychology, Neuroscience Program, Temple University, Philadelphia, PA 19122, United States
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Müller CP. Episodic memories and their relevance for psychoactive drug use and addiction. Front Behav Neurosci 2013; 7:34. [PMID: 23734106 PMCID: PMC3661997 DOI: 10.3389/fnbeh.2013.00034] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 05/09/2013] [Indexed: 01/06/2023] Open
Abstract
The majority of adult people in western societies regularly consume psychoactive drugs. While this consumption is integrated in everyday life activities and controlled in most consumers, it may escalate and result in drug addiction. Non-addicted drug use requires the systematic establishment of highly organized behaviors, such as drug-seeking and -taking. While a significant role for classical and instrumental learning processes is well established in drug use and abuse, declarative drug memories have largely been neglected in research. Episodic memories are an important part of the declarative memories. Here a role of episodic drug memories in the establishment of non-addicted drug use and its transition to addiction is suggested. In relation to psychoactive drug consumption, episodic drug memories are formed when a person prepares for consumption, when the drug is consumed and, most important, when acute effects, withdrawal, craving, and relapse are experienced. Episodic drug memories are one-trial memories with emotional components that can be much stronger than "normal" episodic memories. Their establishment coincides with drug-induced neuronal activation and plasticity. These memories may be highly extinction resistant and influence psychoactive drug consumption, in particular during initial establishment and at the transition to "drug instrumentalization." In that, understanding how addictive drugs interact with episodic memory circuits in the brain may provide crucial information for how drug use and addiction are established.
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Affiliation(s)
- Christian P. Müller
- Section of Addiction Medicine, Department of Psychiatry and Psychotherapy, Friedrich-Alexander-University of Erlangen-NurembergErlangen, Germany
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Noori HR, Fliegel S, Brand I, Spanagel R. The impact of acetylcholinesterase inhibitors on the extracellular acetylcholine concentrations in the adult rat brain: A meta-analysis. Synapse 2012; 66:893-901. [DOI: 10.1002/syn.21581] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 06/19/2012] [Indexed: 01/23/2023]
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Effects of piclozotan (SUN N4057), a partial serotonin 1A receptor agonist, on motor complications induced by repeated administration of levodopa in parkinsonian rats. Eur J Pharmacol 2010; 649:218-23. [DOI: 10.1016/j.ejphar.2010.09.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 08/23/2010] [Accepted: 09/09/2010] [Indexed: 11/17/2022]
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Abreu-Villaca Y, Filgueiras CC, Guthierrez M, Medeiros AHD, Mattos MA, Pereira MDS, Manhaes AC, Kubrusly RCC. Exposure to tobacco smoke containing either high or low levels of nicotine during adolescence: Differential effects on choline uptake in the cerebral cortex and hippocampus. Nicotine Tob Res 2010; 12:776-80. [DOI: 10.1093/ntr/ntq075] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Convergent evidence that choline acetyltransferase gene variation is associated with prospective smoking cessation and nicotine dependence. Neuropsychopharmacology 2010; 35:1374-82. [PMID: 20147892 PMCID: PMC2855736 DOI: 10.1038/npp.2010.7] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ability to quit smoking is heritable, yet few genetic studies have investigated prospective smoking cessation. We conducted a systems-based genetic association analysis in a sample of 472 treatment-seeking smokers of European ancestry after 8 weeks of transdermal nicotine therapy for smoking cessation. The genotyping panel included 169 single-nucleotide polymorphisms (SNPs) in 7 nicotinic acetylcholine receptor subunit genes and 4 genes in the endogenous cholinergic system. The primary outcome was smoking cessation (biochemically confirmed) at the end of treatment. SNPs clustered in the choline acetyltransferase (ChAT) gene were individually identified as nominally significant, and a 5-SNP haplotype (block 6) in ChAT was found to be significantly associated with quitting success. Single SNPs in ChAT haplotype block 2 were also associated with pretreatment levels of nicotine dependence in this cohort. To replicate associations of SNPs in haplotype blocks 2 and 6 of ChAT with nicotine dependence in a non-treatment-seeking cohort, we used data from an independent community-based sample of 629 smokers representing 200 families of European ancestry. Significant SNP and haplotype associations were identified for multiple measures of nicotine dependence. Although the effect sizes in both cohorts are modest, converging data across cohorts and phenotypes suggest that ChAT may be involved in nicotine dependence and ability to quit smoking. Additional sequencing and characterization of ChAT may reveal functional variants that contribute to nicotine dependence and smoking cessation.
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Effects of Systemic Nicotine, Alcohol or Their Combination on Cholinergic Markers in the Frontal Cortex and Hippocampus of Rat. Neurochem Res 2010; 35:1064-70. [DOI: 10.1007/s11064-010-0155-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/10/2010] [Indexed: 11/25/2022]
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Pasumarthi RK, Fadel J. Stimulation of lateral hypothalamic glutamate and acetylcholine efflux by nicotine: implications for mechanisms of nicotine-induced activation of orexin neurons. J Neurochem 2010; 113:1023-35. [PMID: 20236223 DOI: 10.1111/j.1471-4159.2010.06666.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The hypothalamus is a prominent target of nicotine action. We have previously shown that acute systemic nicotine treatment induces Fos expression in the lateral hypothalamus and perifornical area (LH/PFA), with orexin/hypocretin neurons being particularly responsive. However, the neurochemical correlates of acute nicotine treatment in the LH/PFA have not been described. Anatomical studies have revealed that this area receives afferents from cholinergic, glutamatergic, and GABAergic telencephalic brain regions, suggesting a potential role for these neurotransmitters in mediating the hypothalamic component of nicotine effects on homeostatic phenomena, such as arousal and appetite. Here, we used in vivo microdialysis to determine the effect of acute systemic or local nicotine on glutamate, acetylcholine, and GABA efflux in the LH/PFA of rats. Local administration of nicotine significantly increased acetylcholine and glutamate, but not GABA, in the LH/PFA. Thus, we further tested the role of afferent sources of glutamate and acetylcholine in mediating acute nicotine-induced activation of orexin neurons by unilaterally lesioning the prefrontal cortex or basal forebrain cholinergic regions. Lesioned animals showed reduced Fos-positive orexin neurons following nicotine treatment. These data suggest that both acetylcholine and glutamate may mediate the effects of acute nicotine on the activity of hypothalamic neurons, including orexin/hypocretin cells. Changes in cholinergic or glutamatergic transmission in this region with chronic nicotine may contribute to long-term alterations in functions mediated by LH/PFA neurons, including feeding and arousal.
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Affiliation(s)
- Ravi K Pasumarthi
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina 29208, USA
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Konradsson-Geuken A, Gash CR, Alexander K, Pomerleau F, Huettl P, Gerhardt GA, Bruno JP. Second-by-second analysis of alpha 7 nicotine receptor regulation of glutamate release in the prefrontal cortex of awake rats. Synapse 2010; 63:1069-82. [PMID: 19637277 DOI: 10.1002/syn.20693] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
These experiments utilized an enzyme-based microelectrode selective for the second-by-second detection of extracellular glutamate to reveal the alpha 7-based nicotinic modulation of glutamate release in the prefrontal cortex (PFC) of freely moving rats. Rats received intracortical infusions of the nonselective nicotinic agonist nicotine (12.0 mM, 1.0 microg/0.4 microl) or the selective alpha 7 agonist choline (2.0 mM/0.4 microl). The selectivity of drug-induced glutamate release was assessed in subgroups of animals pretreated with the alpha 7 antagonist, alpha-bungarotoxin (alpha-BGT, 10 microM), or kynurenine (10 microM) the precursor of the astrocyte-derived, negative allosteric alpha 7 modulator kynurenic acid. Local administration of nicotine increased glutamate signals (maximum amplitude = 4.3 +/- 0.6 microM) that were cleared to baseline levels in 493 +/- 80 seconds. Pretreatment with alpha-BGT or kynurenine attenuated nicotine-induced glutamate by 61% and 60%, respectively. Local administration of choline also increased glutamate signals (maximum amplitude = 6.3 +/- 0.9 microM). In contrast to nicotine-evoked glutamate release, choline-evoked signals were cleared more quickly (28 +/- 6 seconds) and pretreatment with alpha-BGT or kynurenine completely blocked the stimulated glutamate release. Using a method that reveals the temporal dynamics of in vivo glutamate release and clearance, these data indicate a nicotinic modulation of cortical glutamate release that is both alpha 7- and non-alpha 7-mediated. Furthermore, these data may also provide a mechanism underlying the recent focus on alpha 7 full and partial agonists as therapeutic agents in the treatment of cortically mediated cognitive deficits in schizophrenia.
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Regulation of cortical acetylcholine release: insights from in vivo microdialysis studies. Behav Brain Res 2010; 221:527-36. [PMID: 20170686 DOI: 10.1016/j.bbr.2010.02.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Accepted: 02/10/2010] [Indexed: 01/12/2023]
Abstract
Acetylcholine release links the activity of presynaptic neurons with their postsynaptic targets and thus represents the intercellular correlate of cholinergic neurotransmission. Here, we review the regulation and functional significance of acetylcholine release in the mammalian cerebral cortex, with a particular emphasis on information derived from in vivo microdialysis studies over the past three decades. This information is integrated with anatomical and behavioral data to derive conclusions regarding the role of cortical cholinergic transmission in normal behavioral and how its dysregulation may contribute to cognitive correlates of several neuropsychiatric conditions. Some unresolved issues regarding the regulation and significance of cortical acetylcholine release and the promise of new methodology for advancing our knowledge in this area are also briefly discussed.
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Nguyen QT, Schroeder LF, Mank M, Muller A, Taylor P, Griesbeck O, Kleinfeld D. An in vivo biosensor for neurotransmitter release and in situ receptor activity. Nat Neurosci 2010; 13:127-132. [PMID: 20010818 PMCID: PMC3992257 DOI: 10.1038/nn.2469] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Accepted: 11/17/2009] [Indexed: 11/09/2022]
Abstract
Tools from molecular biology, combined with in vivo optical imaging techniques, provide new mechanisms for noninvasively observing brain processes. Current approaches primarily probe cell-based variables, such as cytosolic calcium or membrane potential, but not cell-to-cell signaling. We devised cell-based neurotransmitter fluorescent engineered reporters (CNiFERs) to address this challenge and monitor in situ neurotransmitter receptor activation. CNiFERs are cultured cells that are engineered to express a chosen metabotropic receptor, use the G(q) protein-coupled receptor cascade to transform receptor activity into a rise in cytosolic [Ca(2+)] and report [Ca(2+)] with a genetically encoded fluorescent Ca(2+) sensor. The initial realization of CNiFERs detected acetylcholine release via activation of M1 muscarinic receptors. We used chronic implantation of M1-CNiFERs in frontal cortex of the adult rat to elucidate the muscarinic action of the atypical neuroleptics clozapine and olanzapine. We found that these drugs potently inhibited in situ muscarinic receptor activity.
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Affiliation(s)
| | - Lee F. Schroeder
- Medical Scientist Training Program, UCSD, La Jolla, CA
- Graduate Program in Neurosciences, UCSD, La Jolla, CA
| | - Marco Mank
- Max-Planck Institut für Neurobiologie, Martinsried, Germany
| | | | - Palmer Taylor
- Skaggs School of Pharmacy and Pharmaceutical Sciences, UCSD, La Jolla, CA
| | | | - David Kleinfeld
- Physics Department, UCSD, La Jolla, CA
- Graduate Program in Neurosciences, UCSD, La Jolla, CA
- Center for Neural Circuits and Behavior, UCSD, La Jolla, CA
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The role of nicotinic receptors in the amelioration of cholinesterase inhibitors in scopolamine-induced memory deficits. Psychopharmacology (Berl) 2009; 206:259-65. [PMID: 19639304 DOI: 10.1007/s00213-009-1603-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Accepted: 06/24/2009] [Indexed: 10/20/2022]
Abstract
RATIONALE Nicotine receptors in the brain are closely related with memory amelioration induced by cholinesterase inhibitors. OBJECTIVE The present study was undertaken to clarify the role of nicotinic receptors in the ameliorative effects of cholinesterase inhibitors on scopolamine-induced memory deficit. METHOD Drug effects were measured using an eight-arm radial maze with four arms baited. Hippocampal theta rhythm during the radial maze task was also recorded with a polygraph system using a telemetric technique. RESULTS Scopolamine (0.5 mg/kg, i.p.) caused a spatial memory deficit as well as an increase in hippocampal theta power during radial maze performance. Pilocarpine, nicotine, physostigmine, and donepezil antagonized the effects of scopolamine. The ameliorative effects of nicotine, physostigmine, and donepezil but not piocarpine on memory performance and hippocampal theta activity were reversed by mecamylamine. CONCLUSION These results indicate that nicotinic receptors have an essential role in the ameliorative effects of cholinesterase inhibitors in both scopolamine-induced memory deficit and the increase in hippocampal theta activity.
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Yano K, Koda K, Ago Y, Kobayashi H, Kawasaki T, Takuma K, Matsuda T. Galantamine improves apomorphine-induced deficits in prepulse inhibition via muscarinic ACh receptors in mice. Br J Pharmacol 2009; 156:173-80. [PMID: 19133998 DOI: 10.1111/j.1476-5381.2008.00037.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Galantamine, a weak acetylcholine esterase (AChE) inhibitor and allosteric potentiator of nicotinic ACh receptors (nAChRs), improves apomorphine-induced deficits in prepulse inhibition (PPI), sensory information-processing deficits, via a nAChR-independent mechanism. The present study examined the role of muscarinic ACh receptors (mAChRs) in the effect of galantamine, and studied the mechanism of galantamine-induced increases in prefrontal ACh levels in mice. EXPERIMENTAL APPROACH Apomorphine (1 mg kg(-1)) was administered to male ddY mice (9-10 weeks old) to create a PPI deficit model. Extracellular ACh concentrations in the prefrontal cortex were measured by in vivo microdialysis. KEY RESULTS Galantamine- and donepezil-mediated improvements in apomorphine-induced PPI deficits were blocked by the preferential M(1) mAChR antagonist telenzepine. The mAChR agonist oxotremorine also improved apomorphine-induced PPI deficits. Galantamine, like donepezil, increased extracellular ACh concentrations in the prefrontal cortex. Galantamine-induced increases in prefrontal ACh levels were partially blocked by the dopamine D(1) receptor antagonist SCH23390, but not by antagonists of mAChRs (telenzepine) and nAChRs (mecamylamine). Galantamine increased dopamine, but not 5-HT, release in the prefrontal cortex. CONCLUSIONS AND IMPLICATIONS Galantamine improves apomorphine-induced PPI deficits by stimulating mAChRs through increasing brain ACh levels via a dopamine D(1) receptor-dependent mechanism and AChE inhibition.
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Affiliation(s)
- K Yano
- Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka, Japan
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Masuda H, Chancellor MB, Kihara K, Sakai Y, Koga F, Azuma H, de Groat WC, Yoshimura N. Effects of cholinesterase inhibition in supraspinal and spinal neural pathways on the micturition reflex in rats. BJU Int 2009; 104:1163-9. [PMID: 19338542 DOI: 10.1111/j.1464-410x.2009.08515.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To investigate whether activation of brain and spinal cholinergic pathways affects the micturition reflex in rats. MATERIALS AND METHODS The effects of intracerebroventricular (i.c.v.) or intrathecal (i.t.) administration of neostigmine as a cholinesterase inhibitor and oxotremorine-M (OXO-M) as a muscarinic acetylcholine receptor (mAChRs) agonist, on the micturition reflex were evaluated by infusion cystometrography (CMG) in urethane-anaesthetized untreated rats or rats pretreated with capsaicin. RESULTS Neostigmine injected i.c.v. increased bladder capacity (BC) and pressure threshold (PT) dose-dependently, with an increase in maximum voiding pressure (MVP) and a decrease in voiding efficiency (VE) at higher doses. Also, neostigmine injected i.t. increased the BC and PT dose-dependently without changing MVP or VE, and these effects were not apparent in capsaicin-pretreated rats. In both routes, atropine as an antagonist of mAChRs, but not mecamylamine as a nicotinic-AChR antagonist, almost completely antagonized the effects of neostigmine. The rank order of potencies of the antagonists for increasing effects of BC induced by 1 nmol of neostigmine was: pirenzepine (an M(1) mAChR antagonist) = atropine > 4-DAMP (an M(3) mAChR antagonist) " methoctramine (an M(2) mAChR antagonist) and tropicamide (an M(4) mAChR antagonist) via the i.c.v. route; and atropine > methoctramine > pirenzepine > tropicamide and 4-DAMP via the i.t. route, respectively. OXO-M injected via i.c.v. and i.t. had the same effects on BC, PT, MVP and VE as neostigmine by i.c.v. and i.t., respectively. CONCLUSIONS These results indicate that activation of muscarinic cholinergic mechanisms by the cholinesterase inhibitor in the brain and spinal cord can inhibit the micturition reflex, mainly by affecting afferent pathways. These mAChR-induced inhibitory effects seem to be mediated through M(1)/M(3) receptor subtypes in the brain, while in the spinal cord, the M(1)/M(2) receptor subtypes might be involved in inhibitory effects, which are mediated via inhibition of mechanoceptive C-fibre afferent pathways.
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Affiliation(s)
- Hitoshi Masuda
- Department of Urology, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan.
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Rao TS, Adams PB, Correa LD, Santori EM, Sacaan AI, Reid RT, Cosford NDP. Pharmacological characterization of (S)-(2)-5-ethynyl-3-(1-methyl-2-pyrrolidinyl)pyridine HCl (SIB-1508Y, Altinicline), a novel nicotinic acetylcholine receptor agonist. Brain Res 2008; 1234:16-24. [PMID: 18692487 DOI: 10.1016/j.brainres.2008.07.063] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 07/12/2008] [Accepted: 07/17/2008] [Indexed: 11/26/2022]
Abstract
(S)-(2)-5-ethynyl-3-(1-methyl-2-pyrrolidinyl)pyridine HCl (SIB-1508Y, Altinicline), is a subtype-selective neuronal nicotinic acetylcholine receptor (nAChR) agonist. In rodents, SIB-1508Y exhibited antidepressant activity, reversed age-related decrements in vigilance, and improved motor and cognitive function in primate models of Parkinson's disease. The goal of the study was to explore neurochemical effects of SIB-1508Y and its isomer, SIB-1680WD. In vitro, SIB-1508Y increased dopamine (DA) release from slices of rat striatum, nucleus accumbens (NAc), olfactory tubercles (OT) and prefrontal cortices (PFC) in a concentration-dependent manner. Relative to its robust effects on DA release from various brain regions, SIB-1508Y was minimally effective at increasing NE release from hippocampus or PFC, and 5-HT release from PFC. SIB-1680WD was less potent and efficacious than SIB-1508Y, but did not act as a partial agonist. Subcutaneous injection of SIB-1508Y (10 mg/kg) increased striatal DA release and this release was sensitive to blockade by the non-competitive nAChR antagonist, mecamylamine (Mec). SIB-1508Y also increased hippocampal ACh release selectively without affecting striatal ACh release. Hippocampal ACh release evoked by SIB-1508Y was attenuated by nAChR antagonists Mec and Dihydro-beta-erythroidine (DHbetaE), and also by the DA D1 receptor antagonist, SCH-23390. These results are consistent with previously established pharmacology of nAChR regulation of hippocampal ACh release. Repeated administration of SIB-1508Y did not result in an enhanced striatal DA release or hippocampal ACh release. In summary, the abilities of SIB-1508Y to release multiple neurotransmitters in distinct brain regions may contribute to its behavioral profile.
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Affiliation(s)
- Tadimeti S Rao
- Merck Research Laboratories, 3535 General Atomics Court, San Diego, CA 92121, USA.
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Comparative effects of the alpha7 nicotinic partial agonist, S 24795, and the cholinesterase inhibitor, donepezil, against aging-related deficits in declarative and working memory in mice. Psychopharmacology (Berl) 2008; 197:499-508. [PMID: 18265960 DOI: 10.1007/s00213-007-1063-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Accepted: 12/20/2007] [Indexed: 01/19/2023]
Abstract
INTRODUCTION The comparative effects of a newly described specific alpha7 nAChR partial agonist, S 24795, and a cholinesterase inhibitor, donepezil, currently used as a symptomatic Alzheimer's disease treatment were studied in two mouse models of aging-related memory deficits. MATERIALS AND METHODS We employed radial arm-maze paradigms assessing short-term working memory (STWM, experiment A) and mnemonic flexibility, a cardinal property of long-term declarative (LTDM, experiment B). Both compounds were administered daily at 0.3 and 1 mg/kg subcutaneously (~3 weeks). RESULTS In the STWM experiment, vehicle-treated aged mice displayed a severe and persistent deficit in the retention of successive arm visits in comparison to younger controls. S 24795 at 1 mg/kg (trends at 0.3 mg/kg) and donepezil at 0.3 mg/kg (but not 1 mg/kg) exerted beneficial effects on this deficit: The performance of aged mice treated with these drugs remarkably increased across the testing days and almost reached young adult performance level. In the critical test trials of memory flexibility (i.e., LTDM), in experiment B, S 24795 at 1 mg/kg (trends at 0.3 mg/kg) and donepezil at the dose of 1 mg/kg (but not 0.3 mg/kg) improved aged mice performance. CONCLUSION This preclinical demonstration that S 24795 restored specific age-related memory deficits with as much efficacy as donepezil adds to recent literature in highlighting the potential interest of an alpha7 nAChR drug as a symptomatic AD therapeutic.
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Tietje KR, Anderson DJ, Bitner RS, Blomme EA, Brackemeyer PJ, Briggs CA, Browman KE, Bury D, Curzon P, Drescher KU, Frost JM, Fryer RM, Fox GB, Gronlien JH, Håkerud M, Gubbins EJ, Halm S, Harris R, Helfrich RJ, Kohlhaas KL, Law D, Malysz J, Marsh KC, Martin RL, Meyer MD, Molesky AL, Nikkel AL, Otte S, Pan L, Puttfarcken PS, Radek RJ, Robb HM, Spies E, Thorin-Hagene K, Waring JF, Ween H, Xu H, Gopalakrishnan M, Bunnelle WH. Preclinical Characterization of A-582941: A Novel α7 Neuronal Nicotinic Receptor Agonist with Broad Spectrum Cognition-Enhancing Properties. CNS Neurosci Ther 2008. [DOI: 10.1111/j.1755-5949.2008.00037.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Tietje KR, Anderson DJ, Bitner RS, Blomme EA, Brackemeyer PJ, Briggs CA, Browman KE, Bury D, Curzon P, Drescher KU, Frost JM, Fryer RM, Fox GB, Gronlien JH, Håkerud M, Gubbins EJ, Halm S, Harris R, Helfrich RJ, Kohlhaas KL, Law D, Malysz J, Marsh KC, Martin RL, Meyer MD, Molesky AL, Nikkel AL, Otte S, Pan L, Puttfarcken PS, Radek RJ, Robb HM, Spies E, Thorin‐Hagene K, Waring JF, Ween H, Xu H, Gopalakrishnan M, Bunnelle WH. Preclinical characterization of A-582941: a novel alpha7 neuronal nicotinic receptor agonist with broad spectrum cognition-enhancing properties. CNS Neurosci Ther 2008; 14:65-82. [PMID: 18482100 PMCID: PMC6494002 DOI: 10.1111/j.1527-3458.2008.00037.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Among the diverse sets of nicotinic acetylcholine receptors (nAChRs), the alpha7 subtype is highly expressed in the hippocampus and cortex and is thought to play important roles in a variety of cognitive processes. In this review, we describe the properties of a novel biaryl diamine alpha7 nAChR agonist, A-582941. A-582941 was found to exhibit high-affinity binding and partial agonism at alpha7 nAChRs, with acceptable pharmacokinetic properties and excellent distribution to the central nervous system (CNS). In vitro and in vivo studies indicated that A-582941 activates signaling pathways known to be involved in cognitive function such as ERK1/2 and CREB phosphorylation. A-582941 enhanced cognitive performance in behavioral models that capture domains of working memory, short-term recognition memory, memory consolidation, and sensory gating deficit. A-582941 exhibited a benign secondary pharmacodynamic and tolerability profile as assessed in a battery of assays of cardiovascular, gastrointestinal, and CNS function. The studies summarized in this review collectively provide preclinical validation that alpha7 nAChR agonism offers a mechanism with potential to improve cognitive deficits associated with various neurodegenerative and psychiatric disorders.
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Affiliation(s)
- Karin R. Tietje
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - David J. Anderson
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - R. Scott Bitner
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Eric A. Blomme
- Department of Cellular and Molecular Toxicology, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Paul J. Brackemeyer
- Manufacturing Science and Technology, Global Pharmaceutical Operations, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Clark A. Briggs
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Kaitlin E. Browman
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Dagmar Bury
- Toxicology & Pathology, Global Pharmaceutical Research and Development, Abbott Laboratories, Ludwigshafen, Germany
| | - Peter Curzon
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Karla U. Drescher
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Ludwigshafen, Germany
| | - Jennifer M. Frost
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Ryan M. Fryer
- Department of Integrative Pharmacology, Global Pharmaceutical Research & Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Gerard B. Fox
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Jens Halvard Gronlien
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Monika Håkerud
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Earl J. Gubbins
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Sabine Halm
- Toxicology & Pathology, Global Pharmaceutical Research and Development, Abbott Laboratories, Ludwigshafen, Germany
| | - Richard Harris
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Rosalind J. Helfrich
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Kathy L. Kohlhaas
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Devalina Law
- Manufacturing Science and Technology, Global Pharmaceutical Operations, Abbott Laboratories, Abbott Park, Illinois, USA
| | - John Malysz
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Kennan C. Marsh
- Pharmacokinetics and Metabolism, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Ilinois, USA
| | - Ruth L. Martin
- Department of Integrative Pharmacology, Global Pharmaceutical Research & Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Michael D. Meyer
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Angela L. Molesky
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Arthur L. Nikkel
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Stephani Otte
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Liping Pan
- Pharmacokinetics and Metabolism, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Ilinois, USA
| | - Pamela S. Puttfarcken
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Richard J. Radek
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Holly M. Robb
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Eva Spies
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Ludwigshafen, Germany
| | - Kirsten Thorin‐Hagene
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Jeffrey F. Waring
- Department of Cellular and Molecular Toxicology, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Hilde Ween
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - Hongyu Xu
- Pharmacokinetics and Metabolism, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Ilinois, USA
| | - Murali Gopalakrishnan
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
| | - William H. Bunnelle
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois, USA
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Briand LA, Gritton H, Howe WM, Young DA, Sarter M. Modulators in concert for cognition: modulator interactions in the prefrontal cortex. Prog Neurobiol 2007; 83:69-91. [PMID: 17681661 PMCID: PMC2080765 DOI: 10.1016/j.pneurobio.2007.06.007] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Revised: 04/06/2007] [Accepted: 06/22/2007] [Indexed: 12/19/2022]
Abstract
Research on the regulation and function of ascending noradrenergic, dopaminergic, serotonergic, and cholinergic systems has focused on the organization and function of individual systems. In contrast, evidence describing co-activation and interactions between multiple neuromodulatory systems has remained scarce. However, commonalities in the anatomical organization of these systems and overlapping evidence concerning the post-synaptic effects of neuromodulators strongly suggest that these systems are recruited in concert; they influence each other and simultaneously modulate their target circuits. Therefore, evidence on the regulatory and functional interactions between these systems is considered essential for revealing the role of neuromodulators. This postulate extends to contemporary neurobiological hypotheses of major neuropsychiatric disorders. These hypotheses have focused largely on aberrations in the integrity or regulation of individual ascending modulatory systems, with little regard for the likely possibility that dysregulation in multiple ascending neuromodulatory systems and their interactions contribute essentially to the symptoms of these disorders. This review will paradigmatically focus on neuromodulator interactions in the PFC and be further constrained by an additional focus on their role in cognitive functions. Recent evidence indicates that individual neuromodulators, in addition to their general state-setting or gating functions, encode specific cognitive operations, further substantiating the importance of research concerning the parallel recruitment of neuromodulator systems and interactions between these systems.
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Affiliation(s)
- Lisa A Briand
- University of Michigan, Department of Psychology and Neuroscience Program, Ann Arbor, MI 48109, USA.
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Li S, Cullen WK, Anwyl R, Rowan MJ. Muscarinic acetylcholine receptor-dependent induction of persistent synaptic enhancement in rat hippocampus in vivo. Neuroscience 2007; 144:754-61. [PMID: 17101232 DOI: 10.1016/j.neuroscience.2006.10.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2006] [Revised: 09/30/2006] [Accepted: 10/02/2006] [Indexed: 11/23/2022]
Abstract
Presynaptic terminal autoinhibitory muscarinic acetylcholine (ACh) receptors are predominantly of the M2/M4 subtypes and antagonists at these receptors may facilitate cognitive processes by increasing ACh release. The present study examined the ability of the M2/M4 muscarinic ACh receptor antagonist N,N'-bis [6-[[(2-methoxyphenyl)methyl]amino]hexyl]-1,8-octane diamine tetrahydrochloride (methoctramine) to induce and modulate synaptic plasticity in the CA1 area of the hippocampus in urethane-anesthetized rats. Both methoctramine and another M2/M4 antagonist, {11-[[2-[(diethylamino)methyl]-1-piperidinyl]acetyl]-5,11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepin-6-one} (AF-DX 116), caused a rapid onset and persistent increase in baseline synaptic transmission after i.c.v. injection. Consistent with a requirement for activation of non-M2 receptors by endogenously released ACh, the M1/M3 receptor selective antagonists 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) and 4,9-dihydro-3-methyl-4-[(4-methyl-1-piperazinyl)acetyl]-10H-thieno[3,4-b][1,5]benzodiazepin-10-one dihydrochloride (telenzepine) prevented the induction of the persistent synaptic enhancement by methoctramine. The requirement for cholinergic activation was transient and independent of nicotinic ACh receptor stimulation. The synaptic enhancement was inhibited by the prior induction of long-term potentiation (LTP) by high frequency stimulation but induction of the synaptic enhancement by methoctramine before high frequency stimulation did not inhibit LTP. Unlike high frequency stimulation-evoked LTP, the synaptic enhancement induced by methoctramine appeared to be NMDA receptor-independent. The present studies provide evidence for the rapid induction of a persistent potentiation at hippocampal glutamatergic synapses by endogenous ACh in vivo following disinhibition of inhibitory M2 muscarinic autoreceptors.
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Affiliation(s)
- S Li
- Department of Pharmacology and Therapeutics, Biotechnology Building, Trinity College Institute of Neuroscience, Trinity College, Dublin 2, Ireland
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Mudo G, Belluardo N, Fuxe K. Nicotinic receptor agonists as neuroprotective/neurotrophic drugs. Progress in molecular mechanisms. J Neural Transm (Vienna) 2006; 114:135-47. [PMID: 16906354 DOI: 10.1007/s00702-006-0561-z] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Accepted: 07/11/2006] [Indexed: 11/29/2022]
Abstract
In the present work we reviewed recent advances concerning neuroprotective/neurotrophic effects of acute or chronic nicotine exposure, and the signalling pathways mediating these effects, including mechanisms implicated in nicotine addiction and nAChR desensitization. Experimental and clinical data largely indicate long-lasting effects of nicotine and nicotinic agonists that imply a neuroprotective/neurotrophic role of nAChR activation, involving mainly alpha7 and alpha4beta2 nAChR subtypes, as evidenced using selective nAChR agonists. Compounds interacting with neuronal nAChRs have the potential to be neuroprotective and treatment with nAChR agonists elicits long-lasting neurotrophic effects, e.g. improvement of cognitive performance in a variety of behavioural tests in rats, monkeys and humans. Nicotine addiction, which is mediated by interaction with nACh receptors, is believed to involve the modification of signalling cascades that modulate synaptic plasticity and gene expression. Desensitization, in addition to protecting cells from uncontrolled excitation, is recently considered as a form of signal plasticity. nAChR can generate these longe-lasting effects by elaboration of complex intracellular signals that mediate medium to long-term events crucial for neuronal maintenance, survival and regeneration. Although a comprehensive survey of the gene-based molecular mechanisms that underlie nicotine effects has yet not been performed a growing amount of data is beginning to improve our understanding of signalling mechanisms that lead to neurotrophic/neuroprotective responses. Evidence for an involvement of the fibroblast growth factor-2 gene in nAChR mechanisms mediating neuronal survival, trophism and plasticity has been obtained. However, more work is needed to establish the mechanisms involved in the effects of nicotinic receptor subtype activation from cognition-enhancing and neurotrophic effects to smoking behaviour and to determine more precisely the therapeutic objectives in potential nicotinic drug treatments of neurodegenerative diseases.
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Affiliation(s)
- G Mudo
- Department of Experimental Medicine, Section of Human Physiology, University of Palermo, Palermo, Italy.
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Fallon S, Shearman E, Sershen H, Lajtha A. The Effects of Glutamate and GABA Receptor Antagonists on Nicotine-induced Neurotransmitter Changes in Cognitive Areas*. Neurochem Res 2006; 32:535-53. [PMID: 16909314 DOI: 10.1007/s11064-006-9113-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2006] [Indexed: 10/24/2022]
Abstract
In the present study, we tested the effects of glutamate and GABA receptor antagonists on nicotine-induced neurotransmitter changes in the hippocampal (dorsal and ventral) and cortical (medial temporal and prefrontal) brain areas of conscious freely moving rats via microdialysis. Both the antagonists and nicotine were administered intracerebrally. The antagonists tested were NMDA, AMPA-kainate, and metabotropic glutamate receptor subtype antagonists (MK801, CNQX, and LY 341495, respectively) and GABA(A) and GABA(B) receptor subtype antagonists (bicuculline and hydroxysaclofen, respectively). We assayed nicotine-induced changes in dopamine (DA), norepinephrine (NE), serotonin (5-HT), and their metabolites. We found with the antagonists, both decreases and increases in nicotine-induced neurotransmitter responses. In the presence of nicotine all the antagonists (except LY 341495) caused a decrease in DA levels in the regions tested. NE levels were decreased in the cortex by all antagonists. In the hippocampus, GABA antagonists decreased NE levels, as did the metabotropic glutamate antagonist, LY 341495, while the other glutamate antagonists increased NE levels. The results of the 5-HT assay were more variable and dependent on the region and antagonist examined; increases were found slightly more often than decreases. The changes in metabolites were not often parallel with changes in their associated neurotransmitters, indicating that the antagonists also affect the metabolism of the neurotransmitters. The effect of the antagonists in the absence of nicotine was mostly to decrease the level of neurotransmitters, although increases were seen in a few cases. The results suggest that the excitatory glutamatergic- and inhibitory GABAergic-amino acid receptors are both involved in mediating nicotine-induced neurotransmitter responses, and their inhibitory or stimulatory effects are receptor subtype and brain region dependent.
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Affiliation(s)
- S Fallon
- Nathan Kline Institute, Orangeburg, NY 10962, USA
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Campos F, Durán R, Vidal L, Faro LRF, Alfonso M. In vivo Effects of the Anatoxin-a on Striatal Dopamine Release. Neurochem Res 2006; 31:491-501. [PMID: 16758357 DOI: 10.1007/s11064-006-9042-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2006] [Indexed: 10/24/2022]
Abstract
Anatoxin-a is an important neurotoxin that acts a potent nicotinic acetylcholine receptor agonist. This characteristic makes anatoxin-a an important tool for the study of nicotinic receptors. Anatoxin-a has been used extensively in vitro experiments, however anatoxin-a has never been studied by in vivo microdialysis studies. This study test the effect of anatoxin-a on striatal in vivo dopamine release by microdialysis.The results of this work show that anatoxin-a evoked dopamine release in a concentration-dependent way. Atropine had not any effect on dopamine release evoked by 3.5 mM anatoxin-a. However, perfusion of nicotinic antagonists mecamylamine and alpha-bungarotoxin induced a total inhibition of the striatal dopamine release. Perfusion of alpha7*-receptors antagonists, metillycaconitine or alpha-bungarotoxin, partially inhibits the release of dopamine stimulated by anatoxin-a. These results show that anatoxin-a can be used as an important nicotinic agonist in the study of nicotinic receptor by in vivo microdialysis technique and also support further in vivo evidences that alpha7*nicotinic AChRs are implicated in the regulation of striatal dopamine release.
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Affiliation(s)
- F Campos
- Department of Functional Biology and Health Sciences, Faculty of Biology, University of Vigo, Pontevedra, Spain.
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31
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Lockman PR, Gaasch J, McAfee G, Abbruscato TJ, Van der Schyf CJ, Allen DD. Nicotine Exposure Does not Alter Plasma to Brain Choline Transfer. Neurochem Res 2006; 31:503-8. [PMID: 16758358 DOI: 10.1007/s11064-006-9047-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/10/2006] [Indexed: 12/15/2022]
Abstract
Acute and chronic nicotine exposure in rats is associated with an increase in brain acetylcholine (ACh) transmission. The acquisition of choline for neuronal ACh synthesis occurs primarily via two pathways; first, free choline is transported from the blood across the blood-brain barrier (BBB) and/or second, from synaptic choline generated by either hydrolysis of non-bound ACh or membrane phosphatidylcholine catabolism. To determine if nicotine-induced cholinergic demand is associated with increased choline transport rates into brain, we measured BBB choline transport in naïve and S-(-) nicotine exposed rats (acute and chronic, 4.5 mg/kg/d for 1, 14, 21 and 28 d; osmotic minipumps) using the in situ rat brain perfusion technique. No significant changes in choline uptake after acute or chronic nicotine exposure were observed in whole brain or cortex. Of considerable interest was a significant decrease in regional brain choline uptake measured in the hippocampus after chronic nicotine exposure (28 d). Our data suggest that the increased ACh transmission observed after nicotine exposure does not correlate with increased blood-to-brain transfer of choline. Considering these data and previous literature reports, we propose that the additional free choline required under conditions of nicotine exposure (for ACh synthesis) is primarily recruited from membrane phospholipid metabolism.
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Affiliation(s)
- Paul R Lockman
- Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo, 79106-1712, USA.
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32
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The Nemertine Toxin Anabaseine and Its Derivative DMXBA (GTS-21): Chemical and Pharmacological Properties. Mar Drugs 2006. [DOI: 10.3390/md403255] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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33
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Chen J, Nakamura M, Kawamura T, Takahashi T, Nakahara D. Roles of pedunculopontine tegmental cholinergic receptors in brain stimulation reward in the rat. Psychopharmacology (Berl) 2006; 184:514-22. [PMID: 16385418 DOI: 10.1007/s00213-005-0252-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Accepted: 10/31/2005] [Indexed: 12/24/2022]
Abstract
RATIONALE The brainstem pedunculopontine tegmental nucleus (PPTg) is proposed to mediate hypothalamic self-stimulation reward via cholinergic activation of the ventral tegmental area (VTA). However, to date there is little direct evidence to support this hypothesis. OBJECTIVES To further study the role of PPTg in hypothalamic self-stimulation reward. METHODS By using in vivo microdialysis, the levels of extracellular acetylcholine (ACh) in the PPTg and VTA were detected during lateral hypothalamic (LH) self-stimulation in rats. Rate-frequency curve shift procedure was used to evaluate the effects of nonselective muscarinic antagonist scopolamine (1 approximately 100 microg/microl) and nicotinic antagonist mecamylamine (5 approximately 100 microg/microl) microinjected into the PPTg on the rewarding efficacy of LH self-stimulation. Subsequently, the drugs were injected into the PPTg, and the extracellular ACh in the VTA was measured. RESULTS LH self-stimulation produced a concurrent ACh release in the PPTg and VTA. Intra-PPTg injection of scopolamine (100 microg/microl) significantly reduced the frequency threshold for LH self-stimulation reward, but nicotinic antagonist mecamylamine did not shift the threshold. However, mecamylamine (10, 25 microg/microl) injected into the PPTg robustly diminished the nicotine-potentiated LH self-stimulation reward. The extracellular ACh in the VTA was dramatically increased by intra-PPTg scopolamine (10, 100 microg/microl), but not by mecamylamine. CONCLUSIONS Results confirm that PPTg plays an important role in brain stimulation reward by modulating the cholinergic activity of the VTA. The PPTg muscarinic receptors contribute to an inhibitory modulation of reward effects by self-stimulation, whereas nicotinic receptors seem to be more involved in nicotine potentiation of brain stimulation reward.
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Affiliation(s)
- J Chen
- Department of Psychology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, 431-3192, Japan
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Giessing C, Thiel CM, Rösler F, Fink GR. The modulatory effects of nicotine on parietal cortex activity in a cued target detection task depend on cue reliability. Neuroscience 2006; 137:853-64. [PMID: 16309846 DOI: 10.1016/j.neuroscience.2005.10.005] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Revised: 08/25/2005] [Accepted: 10/05/2005] [Indexed: 11/23/2022]
Abstract
This functional magnetic resonance imaging study investigates the effects of nicotine in a cued target detection task when changing cue reliability. Fifteen non-smoking volunteers were studied under placebo and nicotine (Nicorette polacrilex gum 1 and 2 mg). Validly and invalidly cued trials were arranged in blocks with high, middle and low cue reliability. Two effects of nicotine were investigated: its influence on i) parietal cortex activity underlying the processing of invalid vs. valid trials (i.e. validity effect) and ii) neural activity in the context of low, middle and high informative value of the cue (i.e. cue reliability effect). Nicotine did not affect behavioral performance. However, nicotine reduced the difference in the blood oxygenation level dependent (BOLD) signal between invalid and valid trials in the right intraparietal sulcus. The reduction of parietal activity in invalid trials was smaller in the low cue reliability condition. The same posterior parietal region exhibited a nicotinic modulation of BOLD activity in valid trials which was dependent on cue reliability: Nicotine specifically enhanced the neural activity during valid trials in the context of low cue reliability, i.e. when subjects are already in a state of low certainty. We speculate that the right intraparietal sulcus might be part of two networks working in parallel: one responsible for reorienting attention and the other for the cholinergic modulation of cue reliability. By reducing the use of the cue, nicotine modulates parietal activity related to reorienting attention in conditions with higher cue certainty. On the other hand, nicotine increases parietal activity in states of low certainty. This enhanced activation might influence brain regions, such as the posterior cingulate, directly involved in the processing of cue reliability.
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Affiliation(s)
- C Giessing
- Institute of Medicine, Research Centre Jülich, 52425 Jülich, Germany.
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Rossi S, Singer S, Shearman E, Sershen H, Lajtha A. The effects of cholinergic and dopaminergic antagonists on nicotine-induced cerebral neurotransmitter changes. Neurochem Res 2005; 30:541-58. [PMID: 16076024 DOI: 10.1007/s11064-005-2689-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In a continuing study of nicotine-induced mechanisms in brain areas associated with cognitive processes, the effects of cholinergic and dopaminergic antagonists on nicotine-induced changes in dopamine, norepinephrine, and serotonin were examined. These effects were measured via in vivo microdialysis in the dorsal and ventral hippocampus and in the prefrontal and medial temporal cortex of conscious, freely moving, adult male rats. Nicotine (0.3 mg/kg, free base) was administered subcutaneously and the antagonists were infused locally via the microdialysis probe. Nicotine alone induced an increase of dopamine and its metabolites in all areas, an increase of norepinephrine in the cortex, and an increase of the norepinephrine metabolite 4-hydroxy-3-methoxy-phenylglycol in all areas. Serotonin was decreased in the hippocampus and increased in the cortex. Nicotine-induced dopamine increases were inhibited by nicotinic (mecamylamine 100 microM, methyllycaconitine 500 microM), muscarinic (atropine 100 microM), and dopaminergic D1 (SCH23390 100 microM) and D2 (eticlopride 100 microM) antagonists, in the hippocampal and cortical areas. In the hippocampal areas, these antagonists had less significant effect on norepinephrine and serotonin. However, in the cortical areas, all antagonists inhibited the nicotine-induced increase of serotonin to varying degrees; and some, primarily nicotinic and dopamine D1 antagonists, inhibited the induced increase of norepinephrine. In the hippocampal and cortical areas, the mechanisms of nicotine-induced dopamine increase seem to be similar, but the mechanisms seem to be different for noradrenergic and serotonergic systems, as shown by the fact that nicotine induces no change in norepinephrine and a decrease in serotonin in the hippocampus, while it induces an increase in both in the cortex. Nicotine-induced dopamine release seems to be mediated, in part locally, by nicotinic and muscarinic receptors on dopaminergic cells. In contrast, nicotine's effect on norepinephrine and serotonin is at least partially mediated by initial changes at other than local sites, and through different receptors. Thus, the effects of nicotine and the mechanisms involved differ for different neurotransmitters and in different brain areas.
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Affiliation(s)
- S Rossi
- Nathan Kline Institute, 10962, Orangeburg, New York, USA
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36
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Liu Y, Wang Y, Sun X, Wang H. Evidence that muscarinic receptors are involved in nicotine-facilitated spatial memory. Pharmacol Biochem Behav 2004; 78:775-9. [PMID: 15301934 DOI: 10.1016/j.pbb.2004.05.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2003] [Revised: 05/16/2004] [Accepted: 05/17/2004] [Indexed: 11/15/2022]
Abstract
A delayed nonmatching-to-position task (DNMPT) in a water maze (nine trials per day, 10 days) was used to investigate the role of muscarinic acetylcholinergic receptor (mAChR) in nicotine-facilitated spatial memory in Wistar rats. The index of spatial memory was determined by the number of correct choices made in choice swim (CS) and the time taken to complete the swim in the correct CS. Diazepam (6 mg kg(-1) ip, daily) significantly impaired choice accuracy and increased the swim time for correct CS. In contrast, when nicotine (2 mg kg(-1) sc, twice daily) and diazepam were administered simultaneously in the last three sessions of training, the choice accuracies of CS were similar to controls and significantly higher than in the diazepam group. However, the swim times for correct CS were longer in the nicotine+diazepam group than in controls. Atropine (30 mg kg(-1) ip, daily) significantly decreased the choice accuracies of CS. The choice accuracies of CS swim times for correct CS in the atropine group did not differ significantly from those in the nicotine+atropine group, in which nicotine (2 mg kg(-1) sc, twice daily) and atropine were given simultaneously. These results show that nicotine improves memory performance when the functions of mAChRs are normal; when the mAChRs are blocked, nicotine does not enhance spatial memory. Therefore, mAChRs are involved in the spatial memory-enhancing effect of nicotine.
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Affiliation(s)
- Yue Liu
- Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
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Martin LF, Kem WR, Freedman R. Alpha-7 nicotinic receptor agonists: potential new candidates for the treatment of schizophrenia. Psychopharmacology (Berl) 2004; 174:54-64. [PMID: 15205879 DOI: 10.1007/s00213-003-1750-1] [Citation(s) in RCA: 266] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2003] [Accepted: 11/28/2003] [Indexed: 01/16/2023]
Abstract
RATIONALE AND OBJECTIVE Auditory sensory gating, a biological measurement of the ability to suppress the evoked response to the second of two auditory stimuli, is diminished in people with schizophrenia. Deficits in sensory gating are associated with attentional impairment, and may contribute to cognitive symptoms and perceptual disturbances. This inhibitory process, which involves the alpha(7) nicotinic receptor mediated release of gamma-aminobutyric acid (GABA) by hippocampal interneurons, represents a potential new target for therapeutic intervention in schizophrenia. METHOD This paper will review several lines of evidence implicating the nicotinic-cholinergic, and specifically, the alpha(7) nicotinic receptor system in the pathology of schizophrenia and the evidence that alpha(7) nicotinic receptor agonists may ameliorate some of these deficits. RESULTS Impaired auditory sensory gating has been linked to the alpha(7) nicotinic receptor gene on the chromosome 15q14 locus. Single nucleotide polymorphisms of the promoter region of this gene are more frequent in people with schizophrenia. Although nicotine can acutely reverse diminished auditory sensory gating in people with schizophrenia, this effect is lost on a chronic basis due to receptor desensitization. Clozapine is able to reverse auditory sensory gating impairment, probably through an alpha(7) nicotinic receptor mechanism, in both humans and animal models with repeated dosing. The alpha(7) nicotinic agonist 3-2,4 dimethoxybenzylidene anabaseine (DMXBA) can also enhance auditory sensory gating in animal models. DMXBA is well tolerated in humans and improves several cognitive measures. CONCLUSION Alpha-7 nicotinic receptor agonists appear to be reasonable candidates for the treatment of cognitive and perceptual disturbances in schizophrenia.
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Affiliation(s)
- Laura F Martin
- Department of Psychiatry, Department of Veterans Affairs and University of Colorado Health Sciences Center, 4200 East Ninth Avenue, C268-71, Denver, CO 80262, USA.
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Rao TS, Sacaan AI, Menzaghi FM, Reid RT, Adams PB, Correa LD, Whelan KT, Vernier JM. Pharmacological characterization of SIB-1663, a conformationally rigid analog of nicotine. Brain Res 2004; 1003:42-53. [PMID: 15019562 DOI: 10.1016/j.brainres.2003.12.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/01/2003] [Indexed: 10/26/2022]
Abstract
SIB-1663 ([+/-]-7-methoxy-2,3,3a,4,5,6,9b-hexahydro-1H-pyrrolo-[3,2h]-isoquinoline) is a conformationally restricted analog of nicotine (NIC). SIB-1663 exhibited modest affinities to cholinergic receptors (K(i) values displacing the binding of [(3)H]-nicotine (NIC) and [(3)H]-quinuclinidylbenzilate (QNB) binding were 1.0+/-0.3 and 2.6+/-0.3 microM, respectively) with no appreciable affinity to nearly 40 other receptors. SIB-1663 selectively activated alpha2beta4 and alpha4beta4 human recombinant neuronal nicotinic acetylcholine receptors (nAChRs) with no appreciable activation of alpha4beta2 nAChRs, the presumed high-affinity nAChRs in rodent brain. These properties led us to examine profile of SIB-1663 in native preparations. SIB-1663 increased DA release from the rat striatum (STR) and olfactory tubercles and NE release from hippocampus, thalamus and prefrontal cortex (PFC). SIB-1663 was equiefficacious to NIC in STR-DA and PFC-NE release assays and less efficacious than NIC in other release assays. SIB-1663 appeared to be partial agonist in the hippocampal NE release assay. SIB-1663-induced neurotransmitter release in vitro was relatively insensitive to the nAChR antagonists, mecamylamine (MEC) or dihydro-beta-erythroidine (DHbetaE) providing equivocal evidence for nAChR activity. SIB-1663 (3-30 mg/kg, s.c.) increased locomotor activity in naive rats in a novel environment, increased ipsilateral turning in rats with unilateral 6-OHDA nigrostriatal lesion and increased withdrawal latencies in the tail-flick assay. The in vivo effects of SIB-1663 in these assays showed varying degrees of sensitivity to nAChR antagonists in that the locomotor activity and turning behavior of SIB-1663 were partially sensitive to MEC, whereas the antinociceptive activity was completely sensitive to MEC. In addition, SIB-1663 (s.c. or i.c.v.) attenuated antinociceptive activity NIC given by the same route suggesting a partial agonist activity. SIB-1663 also increased the retention of avoidance learning in normal rats when administered immediately after the acquisition session. These data indicate that SIB-1663, a conformationally restricted analog of NIC, with distinct nAChR subtype selectivity from NIC exhibits contrasting pharmacology with some of its in vivo actions involving nAChRs.
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Affiliation(s)
- Tadimeti S Rao
- Merck Research Laboratories, 3535 General Atomics Court, San Diego, CA 92121, USA.
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Kommalage M, Höglund AU. Nicotinic Acetylcholinergic Receptors Regulate the Intraspinal Release of Acetylcholine in Male Rats. ACTA ACUST UNITED AC 2003; 93:169-73. [PMID: 14629740 DOI: 10.1034/j.1600-0773.2003.930403.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Activation of cholinergic receptors in the spinal cord increases the intraspinal release of acetylcholine (ACh) and produces potent analgesia. The mechanisms that regulate the release of spinal ACh are not fully known. In the present study, we investigated the role of nicotinic ACh receptors in the regulation of intraspinal ACh release. Using an in vivo intraspinal microdialysis technique, nicotine was administered alone and in combination with the nicotinic antagonists mecamylamine (50 microM), dihydro-beta-erythroidine (DbetaE) (500 microM) and methyllycaconitine (MLA) (40 nM). Administration of nicotine (1 microM-1 mM) produced a dose dependent increase of intraspinal ACh release, while 10 mM nicotine resulted in dramatic increase in ACh release followed by a decrease to baseline. Administration of mecamylamine or DbetaE also induced an increased ACh release while MLA caused a decreased release. Mecamylamine and DbetaE, but not MLA pretreatment attenuated the stimulatory effect of 100 microM nicotine on intraspinal ACh release. It is suggested that spinal ACh release is regulated by different nicotinic ACh receptors. These receptors may tonically regulate spinal ACh release either directly or indirectly via inhibitory interneurones. Some of these receptors may be desensitised by high nicotine concentrations leading to a reduction of ACh release.
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Affiliation(s)
- Mahinda Kommalage
- Department of Neuroscience, Division of Comparative Medicine, Uppsala University, Biomedical Centre, Box 572, S-751 23 Uppsala, Sweden
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Rao TS, Reid RT, Correa LD, Santori EM, Gardner MF, Sacaan AI, Lorrain D, Vernier JM. In vivo pharmacological characterization of (+/-)-4-[2-(1-methyl-2-pyrrolidinyl)ethyl]thiophenol hydrochloride (SIB-1553A), a novel cholinergic ligand: microdialysis studies. Brain Res 2003; 986:71-81. [PMID: 12965231 DOI: 10.1016/s0006-8993(03)03174-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
SIB-1553A ((+/-)-4-[2-(1-methyl-2-pyrrolidinyl)ethyl]thiophenol HCl) is a neuronal nicotinic acetylcholine receptor (nAChR) ligand which is active in rodent and primate models of cognition. In functional assays, SIB-1553A exhibits marked subtype selectivity for nAChRs as compared to nicotine. In addition SIB-1553A also exhibits affinities to histaminergic (H3) and serotonergic (5-HT1 and 5HT2) receptors and sigma binding sites. In the present investigation, we characterized SIB-1553A-induced neurotransmitter release in vivo. Following subcutaneous injection (s.c., 10 mg/kg), SIB-1553A rapidly entered the brain achieving concentration of approximately 20 microM 15 min post-injection and was eliminated from plasma with a terminal half-life of approximately 32 min. In freely moving rats, SIB-1553A (1-40 mg/kg, s.c.), markedly increased ACh release in the hippocampus and prefrontal cortex. In both regions, the magnitude of SIB-1553A-induced ACh release was greater than that seen with the prototypical nAChR agonist, nicotine (0.4 mg/kg, s.c.). Both isomers of SIB-1553A induced similar levels of increase in hippocampal ACh release. Increased hippocampal ACh release was also observed following oral administration of SIB-1553A (40 mg/kg) or after local perfusion into the hippocampus (1 mM). SIB-1553A-induced hippocampal ACh release was significantly attenuated by two nAChR antagonists, mecamylamine (MEC) and dihydro-beta-erythroidine (DHbetaE), and by the dopamine (DA) (D1) antagonist, SCH-23390, arguing that ACh release, in part, involves activation of nAChRs and a permissive DA synapse. In contrast to its robust effects on ACh release, SIB-1553A (40 mg/kg, s.c.) modestly increased striatal DA release (approximately 180% of baseline). Due to the proposed role of cholinergic pathways in learning and memory, the neurochemical profile of SIB-1553A suggests a potential for it to treat cognitive dysfunction.
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Affiliation(s)
- Tadimeti S Rao
- Merck Research Laboratories, 3535 General Atomics Court, San Diego, CA 92121, USA.
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Azam L, Winzer-Serhan U, Leslie FM. Co-expression of alpha7 and beta2 nicotinic acetylcholine receptor subunit mRNAs within rat brain cholinergic neurons. Neuroscience 2003; 119:965-77. [PMID: 12831856 DOI: 10.1016/s0306-4522(03)00220-3] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Nicotine enhances cognitive and attentional processes through stimulation of the basal forebrain cholinergic system. Although muscarinic cholinergic autoreceptors have been well characterized, pharmacological characterization of nicotinic autoreceptors has proven more difficult. The present study used double-labeling in situ hybridization to determine expression of nicotinic acetylcholine receptor (nAChR) subunit mRNAs within basal forebrain cholinergic neurons in order to gain information about possible nAChR autoreceptor properties. Cholinergic cells of the mesopontine tegmentum and striatal interneurons were also examined, as were septohippocampal GABAergic neurons that interact with cholinergic neurons to regulate hippocampal activity. alpha7 and beta2 nAChR mRNAs were found to be co-expressed in almost all cholinergic cells and in the majority of GABAergic neurons examined. alpha4 nAChR mRNA expression was restricted to cholinergic cells of the nucleus basalis magnocellularis, and to non-cholinergic cells of the medial septum and mesopontine tegmentum. These data suggest possible regional differences in the pharmacological properties of nicotinic autoreceptors on cholinergic cells. Whereas most cholinergic cells express rapidly desensitizing alpha7 homomers or alpha7beta2 heteromers, cortical projection neurons may also express a pharmacologically distinct alpha4beta2 nAChR subtype. There may also be differential nAChR regulation of cholinergic and non-cholinergic cells within the mesopontine tegmentum that are implicated in acquisition of nicotine self-administration.
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Affiliation(s)
- L Azam
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
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Rao TS, Adams PB, Correa LD, Santori EM, Sacaan AI, Reid RT, Suto CM, Vernier JM. In vitro pharmacological characterization of (+/-)-4-[2-(1-methyl-2-pyrrolidinyl)ethyl]thio]phenol hydrochloride (SIB-1553A), a nicotinic acetylcholine receptor ligand. Brain Res 2003; 981:85-98. [PMID: 12885429 DOI: 10.1016/s0006-8993(03)02979-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
SIB-1553A ((+/-)-4-[2-(1-methyl-2-pyrrolidinyl)ethyl]thio]phenol HCl) is a neuronal nicotinic acetylcholine receptor (nAChR) ligand which displaced the binding of [3H]nicotine (NIC) to the rat brain nAChRs with an IC(50) value of 110 nM with no appreciable affinity to the alpha7 nAhRs. SIB-1553A showed modest affinity for histaminergic (H3) and serotonergic (5-HT1 and 5-HT2) receptors, and sigma binding sites. In calcium flux assays, SIB-1553A (0.1-5 microM), in contrast to nicotine, showed a greater selectivity for beta4-subunit containing recombinant hnAChRs (alpha2beta4, alpha3beta4 and alpha4beta4) vs. beta2-subunit containing nAChRs (alpha4beta2 and alpha3beta2) both in terms of efficacy and potency. While NIC (10-30 microM) and epibatidine (0.01-0.1 microM) fully activated human muscle-type AChRs expressed by RD cell line, SIB-1553A was virtually ineffective for up to >100 microM and elicited less than 10% of the response due to suberyldicholine. SIB-1553A (< or =30 microM) evoked [3H]DA release from striatum, olfactory tubercles and prefrontal cortex (PFC), and [3H]NE release from hippocampus and PFC, and this evoked release was sensitive to mecamylamine (MEC). SIB-1553A-evoked neurotransmitter release exhibited region- and transmitter-specific antagonism by dehydro-beta-erythroidine (DHbetaE). SIB-1553A was less efficacious than NIC at evoking [3H]NE from the rat hippocampus and antagonized NIC response upon co-application implying partial agonist properties. SIB-1553A did not evoke basal [3H]ACh release from the rat striatum or hippocampus, but attenuated NMDA-evoked [3H]ACh release from the rat striatum. SIB-1553A did not inhibit rat brain cholinesterase for up to 1 mM. Multiple receptor affinities and release of several neurotransmitters may underlie the cognitive-enhancing effects of SIB-1553A documented in rodent and primate models.
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Affiliation(s)
- Tadimeti S Rao
- Merck Research Laboratories, 3535 General Atomics Court, San Diego, CA 92121, USA.
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Ueno KI, Togashi H, Matsumoto M, Ohashi S, Saito H, Yoshioka M. Alpha4beta2 nicotinic acetylcholine receptor activation ameliorates impairment of spontaneous alternation behavior in stroke-prone spontaneously hypertensive rats, an animal model of attention deficit hyperactivity disorder. J Pharmacol Exp Ther 2002; 302:95-100. [PMID: 12065705 DOI: 10.1124/jpet.302.1.95] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The objective of the present study was to elucidate the role of nicotine in impairment of spontaneous alternation behavior of juvenile stroke-prone spontaneously hypertensive rats (SHRSP), an animal model of attention deficit hyperactivity disorder (ADHD). Spontaneous alternation behavior assessed by a Y-maze task was significantly lower, and total arm entries were significantly higher in SHRSP than in genetic control Wistar-Kyoto rats. Nicotine (0.1-1 mg/kg, s.c.) dose dependently improved the spontaneous alternation deficit without affecting total arm entries in SHRSP. Nicotine-induced (1 mg/kg, s.c.) improvement was significantly abolished by the centrally acting nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine (1 mg/kg, i.p.), but not by peripherally acting hexamethonium (5 mg/kg, i.p.), suggesting that nicotine-induced improvement is mediated via central nAChR. The alpha4beta2 nAChR antagonist dihydro-beta-erythroidine (3-10 mg/kg, i.p.) dose dependently counteracted nicotine-induced improvement of spontaneous alternation in SHRSP, whereas the alpha7 nAChR antagonist methyllycaconitine (3-10 mg/kg, i.p.) did not. In addition, the alpha4beta2 nAChR agonist RJR-2403 (N-methyl-4-(3-pyridinyl)-3-butene-1-amine; 1-10 mg/kg, s.c.) dose dependently and significantly improved the spontaneous alternation deficit. These findings revealed that nicotine improved spontaneous alternation behavior in SHRSP via the activation of alpha4beta2, but not alpha7, nAChR. Thus, the alpha4beta2 nAChR mechanism might be responsible for the spontaneous alternation deficit in juvenile SHRSP, an animal model of ADHD. This evidence indicates the possibility that selective alpha4beta2 nAChR agonists might be useful for treating attentional dysfunction in ADHD.
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Affiliation(s)
- Ken-Ichi Ueno
- Department of Pharmacology, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo 060-8638, Japan.
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Dwoskin LP, Crooks PA. A novel mechanism of action and potential use for lobeline as a treatment for psychostimulant abuse. Biochem Pharmacol 2002; 63:89-98. [PMID: 11841781 DOI: 10.1016/s0006-2952(01)00899-1] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lobeline, an alkaloidal constituent of Lobelia inflata LINN., has a long history of therapeutic usage ranging from emetic and respiratory stimulant to tobacco smoking cessation agent. Although classified as both an agonist and an antagonist at nicotinic receptors, lobeline has no structural resemblance to nicotine, and structure--function relationships do not suggest a common pharmacophore. Lobeline inhibits nicotine-evoked dopamine release and [3H]nicotine binding, thus acting as a potent antagonist at both alpha3beta2(*) and alpha4beta2(*) neuronal nicotinic receptor subtypes. However, lobeline does not release dopamine from its presynaptic terminal, but appears to induce the metabolism of dopamine intraneuronally. Reevaluation of the mechanism by which lobeline alters dopamine function reveals that its primary mechanism is inhibition of dopamine uptake and promotion of dopamine release from the storage vesicles within the presynaptic terminal, via an interaction with the tetrabenazine-binding site on the vesicular monoamine transporter (VMAT2). Thus, lobeline appears to perturb the fundamental mechanisms of dopamine storage and release. Based on its neurochemical mechanism, the ability of lobeline to functionally antagonize the neurochemical and behavioral effects of the psychostimulants amphetamine and methamphetamine was examined. Lobeline was found to inhibit the amphetamine-induced release of dopamine in vitro, and amphetamine-induced hyperactivity, drug discrimination, and self-administration. However, lobeline does not support self-administration in rats, suggesting a lack of addiction liability. Thus, lobeline may reduce the abuse liability of these psychostimulants. The development of lobeline and lobeline analogs with targeted selectivity at VMAT2 represents a novel class of therapeutic agents having good potential as efficacious treatments for methamphetamine abuse.
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Affiliation(s)
- Linda P Dwoskin
- College of Pharmacy, University of Kentucky, Rose Street, Lexington, KY 40536-0082, USA.
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Tassonyi E, Charpantier E, Muller D, Dumont L, Bertrand D. The role of nicotinic acetylcholine receptors in the mechanisms of anesthesia. Brain Res Bull 2002; 57:133-50. [PMID: 11849819 DOI: 10.1016/s0361-9230(01)00740-7] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Nicotinic acetylcholine receptors are members of the ligand-gated ion channel superfamily, that includes also gamma-amino-butiric-acid(A), glycine, and 5-hydroxytryptamine(3) receptors. Functional nicotinic acetylcholine receptors result from the association of five subunits each contributing to the pore lining. The major neuronal nicotinic acetylcholine receptors are heterologous pentamers of alpha4beta2 subunits (brain), or alpha3beta4 subunits (autonomic ganglia). Another class of neuronal receptors that are found both in the central and peripheral nervous system is the homomeric alpha7 receptor. The muscle receptor subtypes comprise of alphabetadeltagamma (embryonal) or alphabetadeltaepsilon (adult) subunits. Although nicotinic acetylcholine receptors are not directly involved in the hypnotic component of anesthesia, it is possible that modulation of central nicotinic transmission by volatile agents contributes to analgesia. The main effect of anesthetic agents on nicotinic acetylcholine receptors is inhibitory. Volatile anesthetics and ketamine are the most potent inhibitors both at alpha4beta2 and alpha3beta4 receptors with clinically relevant IC(50) values. Neuronal nicotinic acetylcholine receptors are more sensitive to anesthetics than their muscle counterparts, with the exception of the alpha7 receptor. Several intravenous anesthetics such as barbiturates, etomidate, and propofol exert also an inhibitory effect on the nicotinic acetylcholine receptors, but only at concentrations higher than those necessary for anesthesia. Usual clinical concentrations of curare cause competitive inhibition of muscle nicotinic acetylcholine receptors while higher concentrations may induce open channel blockade. Neuronal nAChRs like alpha4beta2 and alpha3beta4 are inhibited by atracurium, a curare derivative, but at low concentrations the alpha4beta2 receptor is activated. Inhibition of sympathetic transmission by clinically relevant concentrations of some anesthetic agents is probably one of the factors involved in arterial hypotension during anesthesia.
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Affiliation(s)
- Edömer Tassonyi
- Division of Anesthesiology, Department of Anesthesiology, Pharmacology and Surgical Intensive Care (APSIC), Geneva University Hospitals, Geneva, Switzerland.
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46
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Stough C, Thompson J, Bates T, Nathan P. Examining neurochemical determinants of inspection time. INTELLIGENCE 2001. [DOI: 10.1016/s0160-2896(01)00077-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hama AT, Lloyd GK, Menzaghi F. The antinociceptive effect of intrathecal administration of epibatidine with clonidine or neostigmine in the formalin test in rats. Pain 2001; 91:131-8. [PMID: 11240085 DOI: 10.1016/s0304-3959(00)00425-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The analgesic effect of intrathecal injection of epibatidine, clonidine and neostigmine, compounds that elevate ACh, was examined in the formalin test, a model of post-injury central sensitization in the rat. The compounds were injected alone and in combination. Intrathecal injection of epibatidine alone did not alter pain behaviors, compared to vehicle-treated rats. Intrathecal injection of clonidine dose-dependently reduced tonic pain behaviors (ED(50)+/-95% confidence limits=6.7+/-4.8 microg). The combination of clonidine and epibatidine (C:E), in the ratio of 26:1, dose-dependently reduced tonic pain behaviors; and the ED(50) of C:E was 1.1+/-0.98 microg a significant 6-fold leftward shift of the dose response curve, compared with clonidine alone. The antinociceptive effect of C:E (26:1) was attenuated by pre-treatment with the nAChR antagonist mecamylamine. Neostigmine dose-dependently reduced tonic pain behaviors (ED(50)=1.5+/-1.3 microg). The combination of neostigmine and epibatidine, in a ratio of 8:1, significantly shifted the dose response curve 4-fold to the left (ED(50)=0.4+/-0.3 microg). The effect is mediated in part by the activation of the nAChR and possibly by the enhanced release of ACh. These data demonstrate significant enhancement of the antinociceptive effects of spinally delivered analgesics by a nAChR agonist, suggesting that this class of compounds may have utility as adjuvants when combined with conventional therapeutics.
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Affiliation(s)
- A T Hama
- Merck Research Laboratories, San Diego, 505 Coast Blvd. South, #300, La Jolla CA 92037, USA.
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Day JC, Kornecook TJ, Quirion R. Application of in vivo microdialysis to the study of cholinergic systems. Methods 2001; 23:21-39. [PMID: 11162147 DOI: 10.1006/meth.2000.1103] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The application of in vivo microdialysis to the study of acetylcholine (ACh) release has contributed greatly to our understanding of cholinergic brain systems. This article reviews standard experimental procedures for dialysis probe selection and implantation, perfusion parameters, neurochemical detection, and data analysis as they relate to microdialysis assessments of cholinergic function. Particular attention is focused on the unique methodological considerations that arise when in vivo microdialysis is dedicated expressly to the recovery and measurement of ACh as opposed to other neurotransmitters. Limitations of the microdialysis technique are discussed, as well as methodological adaptations that may prove useful in overcoming these limitations. This is followed by an overview of recent studies in which the application of in vivo microdialysis has been used to characterize the basic pharmacology and physiology of cholinergic neurons. Finally, the usefulness of the microdialysis approach for testing hypotheses regarding the cholinergic systems' involvement in cognitive processes is examined. It can be concluded that, in addition to being a versatile and practical method for studying the neurochemistry of cholinergic brain systems, in vivo microdialysis represents a valuable tool in our efforts to better comprehend ACh's underlying role in a variety of behavioral processes.
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Affiliation(s)
- J C Day
- Douglas Hospital Research Centre & Department of Psychiatry, McGill University, Verdun, Quebec, H4H 1R3, Canada
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Bancroft A, Levin ED. Ventral hippocampal alpha4beta2 nicotinic receptors and chronic nicotine effects on memory. Neuropharmacology 2000; 39:2770-8. [PMID: 11044746 DOI: 10.1016/s0028-3908(00)00099-x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Chronic nicotine administration has been repeatedly shown to facilitate working memory function in rats on the radial-arm maze. The critical neural mechanisms for this effect are still being discovered. The nicotinic nature of the chronic nicotine induced memory improvement is supported by the finding that it is blocked by chronic mecamylamine co-infusion. The hippocampus also appears to be critically important. Hippocampal ibotenic acid lesions block the effect. Within the hippocampus, we have found that the alpha4beta2 nicotinic receptor subtype is involved in memory functioning. Acute ventral hippocampal infusions of the alpha4beta2 nicotinic antagonist dihydro-beta-erythroidine (DHbetaE) significantly decreased working memory performance in the radial-arm maze. The aim of the current study was to determine the importance of alpha4beta2 receptors within the ventral hippocampus for the memory enhancing effects of chronic nicotine treatment. Adult female Sprague-Dawley rats were trained on the 8-arm radial maze and were cannulated bilaterally in the ventral hippocampus. Osmotic minipumps administering chronic nicotine at a rate of 5 mg per kg per day were also implanted in the nicotine treatment rats. Control rats received saline-only minipumps. For a period of 4 weeks after surgery, each rat received bilateral hippocampal infusions of 0, 2, 6 and 18 microg per side of DHbetaE and tested for memory performance on the radial-arm maze. Radial-arm maze choice accuracy was impaired by acute hippocampal DHbetaE infusion in a dose-related fashion. This acute hippocampal DHbetaE-induced choice accuracy impairment was eliminated by chronic systemic nicotine infusion. Chronic nicotine in combination with acute vehicle hippocampal infusion was not seen to alter choice accuracy. Response latency was not found to be altered by acute hippocampal DHbetaE in the absence of chronic nicotine administration, but it did attenuate the response latency reduction induced by chronic nicotine infusion. Wet dog shakes were not found to be affected by hippocampal DHbetaE when given without chronic nicotine. Wet dog shakes were significantly increased by chronic nicotine infusion. Intra-hippocampal DHbetaE significantly potentiated this effect. The results from the current study reinforce the hypothesis that ventral hippocampal alpha4beta2 nicotinic receptors are important for memory function. These receptors may also have a role to play in the development of other aspects of behavior associated with chronic nicotine treatment.
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Affiliation(s)
- A Bancroft
- Neurobehavioral Research Laboratory, Box 3412, Department of Psychiatry, Duke University Medical Center, Durham, NC 27710, USA
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50
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Kem WR. The brain alpha7 nicotinic receptor may be an important therapeutic target for the treatment of Alzheimer's disease: studies with DMXBA (GTS-21). Behav Brain Res 2000; 113:169-81. [PMID: 10942043 DOI: 10.1016/s0166-4328(00)00211-4] [Citation(s) in RCA: 187] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A large decrease in brain nicotinic receptor levels occurs in Alzheimer's disease, relative to muscarinic and other receptors. Neurons possessing high affinity nicotinic receptors seem particularly vulnerable. The low affinity nicotinic receptors which selectively bind alpha-bungarotoxin are not significantly affected. The major nicotinic receptor subtype which binds this toxin is a homo-oligomer composed of alpha7 subunits. Due to its exceptionally high calcium ion selectivity, this particular receptor can be considered as a ligand-gated calcium channel. Alpha7 receptors are found in regions of the brain which are important for cognition, including cerebral cortex and hippocampus. Hippocampal receptors are largely confined to GABAergic interneurons. Alpha7 receptors seem less likely than alpha4-beta2 receptors to be up-regulated in number and down-regulated in function as a result of chronic agonist exposure. A family of nicotinic agonists based upon the marine animal toxin anabaseine have been synthesized and investigated. One of these compounds, DMXBA [3-(2,4-dimethoxybenzylidene)-anabaseine; code name GTS-21] has displayed promising characteristics during phase I clinical tests. In the rat DMXBA is selectively agonistic upon alpha7 nicotinic receptors. In addition it is a moderately potent antagonist at alpha4-beta2 receptors. DMXBA enhances a variety of cognitive behaviors in mice, monkeys, rats and rabbits. It also displays neuroprotective activity upon cultured neuronal cells exposed to beta-amyloid or deprived of NGF. The compound is much less toxic than nicotine and does not affect autonomic and skeletal muscle systems at doses which enhance cognitive behavior. Phase I clinical tests indicate that large doses can be safely administered orally without adverse effects. Psychological tests on healthy young male subjects indicate a positive effect of DMXBA on some measures of cognition. While DMXBA is a much weaker partial agonist on human alpha7 receptors than upon rat alpha7 receptors, its 4-hydroxy metabolite has been shown to have excellent efficacy on both receptors. Thus, some of the physiological and behavioral effects of GTS-21 may be due to the actions of this primary metabolite.
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Affiliation(s)
- W R Kem
- Department of Pharmacology and Experimental Therapeutics, University of Florida College of Medicine, Gainesville 32610-0267, USA.
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