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Mendoza C, Barreto GE, Iarkov A, Tarasov VV, Aliev G, Echeverria V. Cotinine: A Therapy for Memory Extinction in Post-traumatic Stress Disorder. Mol Neurobiol 2018; 55:6700-6711. [PMID: 29335846 DOI: 10.1007/s12035-018-0869-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 01/07/2018] [Indexed: 12/14/2022]
Abstract
Post-traumatic stress disorder (PTSD) is a mental disorder that may develop after exposure to exceptionally threatening or unescapable horrifying events. Actual therapies fail to alleviate the emotional suffering and cognitive impairment associated with this disorder, mostly because they are ineffective in treating the failure to extinguish trauma memories in a great percentage of those affected. In this review, current behavioral, cellular, and molecular evidence supporting the use of cotinine for treating PTSD are reviewed. The role of the positive modulation by cotinine of the nicotinic acetylcholine receptors (nAChRs) and their downstream effectors, the protection of astroglia, and the inhibition of microglia in the PTSD brain are also discussed.
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Affiliation(s)
- Cristhian Mendoza
- Facultad de Ciencias de la Salud, Universidad San Sebastián, Lientur 1457, 4030000, Concepción, Chile
| | - George E Barreto
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia.,Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Santiago, Chile
| | - Alexandre Iarkov
- Facultad de Ciencias de la Salud, Universidad San Sebastián, Lientur 1457, 4030000, Concepción, Chile
| | - Vadim V Tarasov
- Institute of Pharmacy and Translational Medicine, Sechenov First Moscow State Medical University, 119991, Moscow, Russia
| | - Gjumrakch Aliev
- Institute of Physiologically Active Compounds of the Russian Academy of Sciences, Severniy Proezd, Chernogolovka, Moscow Region, 1142432, Russia. .,"GALLY" International Biomedical Research Consulting LLC, San Antonio, TX, 78229, USA. .,School of Health Sciences and Healthcare Administration, University of Atlanta, Johns Creek, GA, 30097, USA.
| | - Valentina Echeverria
- Facultad de Ciencias de la Salud, Universidad San Sebastián, Lientur 1457, 4030000, Concepción, Chile. .,Bay Pines VA Healthcare System, Research and Development, Bay Pines, FL, 33744, USA.
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Koob GF. Antireward, compulsivity, and addiction: seminal contributions of Dr. Athina Markou to motivational dysregulation in addiction. Psychopharmacology (Berl) 2017; 234:1315-1332. [PMID: 28050629 DOI: 10.1007/s00213-016-4484-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 11/08/2016] [Indexed: 02/02/2023]
Abstract
RATIONALE AND OBJECTIVES Addiction is defined as a chronically relapsing disorder characterized by compulsive drug seeking that is hypothesized to derive from multiple sources of motivational dysregulation. METHODS AND RESULTS Dr. Athina Markou made seminal contributions to our understanding of the neurobiology of addiction with her studies on the dysregulation of reward function using animal models with construct validity. Repeated overstimulation of the reward systems with drugs of abuse decreases reward function, characterized by brain stimulation reward and presumbably reflecting dysphoria-like states. The construct of negative reinforcement, defined as drug taking that alleviates a negative emotional state that is created by drug abstinence, is particularly relevant as a driving force in both the withdrawal/negative affect and preoccupation/anticipation stages of the addiction cycle. CONCLUSIONS The negative emotional state that drives such negative reinforcement is hypothesized to derive from the dysregulation of key neurochemical circuits that drive incentive-salience/reward systems (dopamine, opioid peptides) in the ventral striatum and from the recruitment of brain stress systems (corticotropin-releasing factor, dynorphin) within the extended amygdala. As drug taking becomes compulsive-like, the factors that motivate behavior are hypothesized to shift to drug-seeking behavior that is driven not only by positive reinforcement but also by negative reinforcement. This shift in motivation is hypothesized to reflect the allostatic misregulation of hedonic tone such that drug taking makes the hedonic negative emotional state worse during the process of seeking temporary relief with compulsive drug taking.
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Affiliation(s)
- George F Koob
- National Institute on Alcohol Abuse and Alcoholism, 5635 Fishers Lane, Room 2001, Suite 2000, Rockville, MD, 20852, USA.
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3
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Koob GF. The dark side of emotion: the addiction perspective. Eur J Pharmacol 2015; 753:73-87. [PMID: 25583178 PMCID: PMC4380644 DOI: 10.1016/j.ejphar.2014.11.044] [Citation(s) in RCA: 232] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 11/06/2014] [Accepted: 11/26/2014] [Indexed: 01/04/2023]
Abstract
Emotions are "feeling" states and classic physiological emotive responses that are interpreted based on the history of the organism and the context. Motivation is a persistent state that leads to organized activity. Both are intervening variables and intimately related and have neural representations in the brain. The present thesis is that drugs of abuse elicit powerful emotions that can be interwoven conceptually into this framework. Such emotions range from pronounced euphoria to a devastating negative emotional state that in the extreme can create a break with homeostasis and thus an allostatic hedonic state that has been considered key to the etiology and maintenance of the pathophysiology of addiction. Drug addiction can be defined as a three-stage cycle-binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation-that involves allostatic changes in the brain reward and stress systems. Two primary sources of reinforcement, positive and negative reinforcement, have been hypothesized to play a role in this allostatic process. The negative emotional state that drives negative reinforcement is hypothesized to derive from dysregulation of key neurochemical elements involved in the brain incentive salience and stress systems. Specific neurochemical elements in these structures include not only decreases in incentive salience system function in the ventral striatum (within-system opponent processes) but also recruitment of the brain stress systems mediated by corticotropin-releasing factor (CRF), dynorphin-κ opioid systems, and norepinephrine, vasopressin, hypocretin, and substance P in the extended amygdala (between-system opponent processes). Neuropeptide Y, a powerful anti-stress neurotransmitter, has a profile of action on compulsive-like responding for drugs similar to a CRF1 receptor antagonist. Other stress buffers include nociceptin and endocannabinoids, which may also work through interactions with the extended amygdala. The thesis argued here is that the brain has specific neurochemical neurocircuitry coded by the hedonic extremes of pleasant and unpleasant emotions that have been identified through the study of opponent processes in the domain of addiction. These neurochemical systems need to be considered in the context of the framework that emotions involve the specific brain regions now identified to differentially interpreting emotive physiological expression.
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Affiliation(s)
- George F Koob
- National Institute on Alcohol Abuse and Alcoholism, Washington, DC, USA.
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4
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Henderson BJ, Lester HA. Inside-out neuropharmacology of nicotinic drugs. Neuropharmacology 2015; 96:178-93. [PMID: 25660637 DOI: 10.1016/j.neuropharm.2015.01.022] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 01/20/2015] [Accepted: 01/20/2015] [Indexed: 02/05/2023]
Abstract
Upregulation of neuronal nicotinic acetylcholine receptors (AChRs) is a venerable result of chronic exposure to nicotine; but it is one of several consequences of pharmacological chaperoning by nicotine and by some other nicotinic ligands, especially agonists. Nicotinic ligands permeate through cell membranes, bind to immature AChR oligomers, elicit incompletely understood conformational reorganizations, increase the interaction between adjacent AChR subunits, and enhance the maturation process toward stable AChR pentamers. These changes and stabilizations in turn lead to increases in both anterograde and retrograde traffic within the early secretory pathway. In addition to the eventual upregulation of AChRs at the plasma membrane, other effects of pharmacological chaperoning include modifications to endoplasmic reticulum stress and to the unfolded protein response. Because these processes depend on pharmacological chaperoning within intracellular organelles, we group them as "inside-out pharmacology". This term contrasts with the better-known, acute, "outside-in" effects of activating and desensitizing plasma membrane AChRs. We review current knowledge concerning the mechanisms and consequences of inside-out pharmacology. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
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Affiliation(s)
- Brandon J Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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Grizzell JA, Echeverria V. New Insights into the Mechanisms of Action of Cotinine and its Distinctive Effects from Nicotine. Neurochem Res 2014; 40:2032-46. [PMID: 24970109 DOI: 10.1007/s11064-014-1359-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 06/10/2014] [Indexed: 12/20/2022]
Abstract
Tobacco consumption is far higher among a number of psychiatric and neurological diseases, supporting the notion that some component(s) of tobacco may underlie the oft-reported reduction in associated symptoms during tobacco use. Popular dogma holds that this component is nicotine. However, increasing evidence support theories that cotinine, the main metabolite of nicotine, may underlie at least some of nicotine's actions in the nervous system, apart from its adverse cardiovascular and habit forming effects. Though similarities exist, disparate and even antagonizing actions between cotinine and nicotine have been described both in terms of behavior and physiology, underscoring the need to further characterize this potentially therapeutic compound. Cotinine has been shown to be psychoactive in humans and animals, facilitating memory, cognition, executive function, and emotional responding. Furthermore, recent research shows that cotinine acts as an antidepressant and reduces cognitive-impairment associated with disease and stress-induced dysfunction. Despite these promising findings, continued focus on this potentially safe alternative to tobacco and nicotine use is lacking. Here, we review the effects of cotinine, including comparisons with nicotine, and discuss potential mechanisms of cotinine-specific actions in the central nervous system which are, to date, still being elucidated.
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Affiliation(s)
- J Alex Grizzell
- Department of Psychiatry and Behavioral Neurosciences, Morsani College of Medicine, University of South Florida, Tampa, FL, 33611, USA.,Department of Research and Development, Bay Pines VA Healthcare System, 10,000 Bay Pines Blvd., Bldg. 23, Rm. 123, Bay Pines, FL, 33744, USA
| | - Valentina Echeverria
- Department of Research and Development, Bay Pines VA Healthcare System, 10,000 Bay Pines Blvd., Bldg. 23, Rm. 123, Bay Pines, FL, 33744, USA. .,Universidad Autónoma de Chile, Carlos Antúnez 1920, Providencia, Santiago, Chile. .,Department of Molecular Medicine, University of South Florida, Tampa, FL, 33647, USA.
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Cohen A, George O. Animal models of nicotine exposure: relevance to second-hand smoking, electronic cigarette use, and compulsive smoking. Front Psychiatry 2013; 4:41. [PMID: 23761766 PMCID: PMC3671664 DOI: 10.3389/fpsyt.2013.00041] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 05/13/2013] [Indexed: 12/23/2022] Open
Abstract
Much evidence indicates that individuals use tobacco primarily to experience the psychopharmacological properties of nicotine and that a large proportion of smokers eventually become dependent on nicotine. In humans, nicotine acutely produces positive reinforcing effects, including mild euphoria, whereas a nicotine abstinence syndrome with both somatic and affective components is observed after chronic nicotine exposure. Animal models of nicotine self-administration and chronic exposure to nicotine have been critical in unveiling the neurobiological substrates that mediate the acute reinforcing effects of nicotine and emergence of a withdrawal syndrome during abstinence. However, important aspects of the transition from nicotine abuse to nicotine dependence, such as the emergence of increased motivation and compulsive nicotine intake following repeated exposure to the drug, have only recently begun to be modeled in animals. Thus, the neurobiological mechanisms that are involved in these important aspects of nicotine addiction remain largely unknown. In this review, we describe the different animal models available to date and discuss recent advances in animal models of nicotine exposure and nicotine dependence. This review demonstrates that novel animal models of nicotine vapor exposure and escalation of nicotine intake provide a unique opportunity to investigate the neurobiological effects of second-hand nicotine exposure, electronic cigarette use, and the mechanisms that underlie the transition from nicotine use to compulsive nicotine intake.
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Affiliation(s)
- Ami Cohen
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
| | - Olivier George
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA
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Ellis JR, Nathan PJ, Villemagne VL, Mulligan RS, Saunder T, Young K, Smith CL, Welch J, Woodward M, Wesnes KA, Savage G, Rowe CC. Galantamine-induced improvements in cognitive function are not related to alterations in alpha(4)beta (2) nicotinic receptors in early Alzheimer's disease as measured in vivo by 2-[18F]fluoro-A-85380 PET. Psychopharmacology (Berl) 2009; 202:79-91. [PMID: 18949462 DOI: 10.1007/s00213-008-1347-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Accepted: 09/19/2008] [Indexed: 01/25/2023]
Abstract
INTRODUCTION The nicotinic acetylcholine receptor (nAChR) system plays a regulatory role in a number of cognitive processes. Cholinesterase inhibitors (i.e., galantamine) that potentiate cholinergic neurotransmission improve cognitive function in Alzheimer's disease (AD); however, the relationship between these effects and associated changes in nAChRs are yet to be established in vivo. MATERIALS AND METHODS 2-[18F]Fluoro-A-85380 (2-FA) binds to nAChRs and with positron emission tomography (PET) imaging provides a composite measure of receptor density and ligand affinity. This study aimed to: (1) quantify nAChRs in vivo in 15 drug-naïve patients with mild AD before and after chronic treatment with galantamine, using 2-FA and PET, and (2) examine the relationship between treatment-induced changes in nAChRs and improvements in cognitive function. Participants were nonsmokers and underwent extensive cognitive testing and a PET scan after injection of approximately 200 MBq of 2-FA on two occasions (before and after 12 weeks, galantamine treatment). A 3-day washout period preceded the second scan. Brain regional 2-FA binding was assessed through a simplified estimation of distribution volume (DV(S)). RESULTS Performance on global measures of cognition significantly improved following galantamine treatment (p < 0.05). This improvement extended to specific cognitive measures of language and verbal learning. No significant differences in nAChR DV(S) before and after galantamine treatment were found. The treatment-induced improvement in cognition was not correlated with regional or global nAChR DV(S), suggesting that changes in nAChRs may not be responsible for the improvements in cognition following galantamine in patients with mild AD.
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Affiliation(s)
- J R Ellis
- School of Psychology, Psychiatry, and Psychological Medicine, Monash University, Melbourne, Victoria, Australia.
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Guo X, Lester RAJ. Regulation of Nicotinic Acetylcholine Receptor Desensitization by Ca2+. J Neurophysiol 2007; 97:93-101. [PMID: 17050825 DOI: 10.1152/jn.01047.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The relationship between the concentration of intracellular Ca2+ ([Ca2+]i) and recovery from desensitization of nicotinic acetylcholine receptors (nAChRs) in rat medial habenula (MHb) neurons was investigated using the whole cell patch-clamp techniques in combination with microfluoresecent [Ca2+]i measurements. Recovery from desensitization was assessed with a paired-pulse agonist application protocol. Application of 100 μM nicotine (5 s) caused pronounced desensitization of nAChRs, after which recovery proceeded with two components. The relative weight of the two phases of recovery was sensitive to the nature of the intracellular Ca2+ chelator, with a greater fraction of channels recovering during the fast phase in the presence of BAPTA than EGTA. Recovery was affected by differential Ca2+ buffering only when Ca2+ was present in the extracellular solution, implying that Ca2+ influx through nAChRs was responsible for slowing the recovery. Simultaneous [Ca2+]i measurements showed that recovery from desensitization was inversely correlated with the instantaneous [Ca2+]i, further supporting the suggestion that elevation of [Ca2+]i limits the return of nAChRs to the resting state. In a separate set of experiments, activation of voltage-gated Ca2+ channels during the recovery phase produced a sufficiently large increase in [Ca2+]i to reduce recovery from desensitization even in the absence of Ca2+ influx through nAChRs. Overall, it is suggested that Ca2+ entry through both nAChRs and voltage-gated Ca2+ channels exerts a negative feedback on nAChR activity through stabilization of desensitized states. The interaction of these two Ca2+ sources could form the basis of a coincidence detector under specific circumstances.
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Affiliation(s)
- Xiaochuan Guo
- Department of Neurobiology, McKnight Brain Institute, University of Alabama at Birmingham, 1825 University Boulevard, Birmingham AL 35294-2182, USA
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Terry AV, Williamson R, Gattu M, Beach JW, McCurdy CR, Sparks JA, Pauly JR. Lobeline and structurally simplified analogs exhibit differential agonist activity and sensitivity to antagonist blockade when compared to nicotine. Neuropharmacology 2001; 37:93-102. [PMID: 9680262 DOI: 10.1016/s0028-3908(97)00142-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
In the present study, lobeline and two structurally simplified analogs were evaluated for activity in muscarinic and nicotinic binding assays, a functional assay for nicotinic receptor activation (86Rb+ efflux from striatal synaptosomes) and an acetylcholinesterase (AChE) assay. Lobeline displaced [3H]cytisine binding to rat cortical membranes with a mean inhibition constant (KI) value of 16.0 nM, while the lobeline analogs CRM-I-13-1 and CRM-I-32-1 exhibited values of 15.0 and 5.4 microM, respectively. [3H]methylscopolamine was displaced by lobeline with a mean KI value of 37.0 microM while CRM-I-13-1 and CRM-I-32-1 exhibited values of 55.0 and 16.0 microM, respectively. While nicotine stimulated 86Rb+ efflux from striatal synaptosomes in a mecamylamine reversible manner at each concentration tested, lobeline slightly increased 86Rb+ efflux at lower concentrations and reduced efflux at higher concentrations. Further, none of the lobeline effects were reversed with mecamylamine. Although less potent, the two lobeline analogs exhibited a similar pattern of activity. These data may suggest that lobeline and structurally similar compounds bind with different subtype selectivity than nicotine, or exert their agonists effects through non-nicotinic mechanisms. All of the compounds tested were at least several hundred times less potent than physostigmine as AChE inhibitors. While some differences were apparent between the lobeline analog which contained the 2-keto-ethyl portion of lobeline and the analog which contained the phenyl 2-hydroxy-ethyl moiety, each compound was much less active than lobeline in most parameters assessed.
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Affiliation(s)
- A V Terry
- University of Georgia Clinical Pharmacy Program, Medical College of Georgia, Augusta 30912-2390, USA.
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Kempsill FE, Pratt JA. Mecamylamine but not the alpha7 receptor antagonist alpha-bungarotoxin blocks sensitization to the locomotor stimulant effects of nicotine. Br J Pharmacol 2000; 131:997-1003. [PMID: 11053222 PMCID: PMC1572401 DOI: 10.1038/sj.bjp.0703560] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The involvement of alpha7 receptors in the locomotor stimulant effects of nicotine has been examined by determining the ability of intracerebroventricular (i.c.v.) administration of the alpha7 receptor antagonist alpha-bungarotoxin (alpha-bgt) to modify sensitization to the locomotor activating effects of chronic nicotine. Intracerebroventricular administration of alpha-bgt (0.02 - 8 nmoles) produced a dose dependent increase in convulsive behaviour. At doses less than 1.0 nmole, minimal convulsive behaviour occurred but larger doses evoked convulsions in all rats which displayed a more rapid onset time as the dose increased. The binding distribution of alpha7 receptors 20 min and 3 h following an i.c.v. administration of [(125)I]-alpha-bgt (0.02 nmoles) revealed clear binding in the hippocampus, cingulate cortex and hypothalamus which was more intense after 3 h. Rats chronically treated with nicotine (0.4 mg kg(-1)) and exposed to the locomotor activity apparatus daily acquired an increase in locomotor activity relative to the control group after 3 days of treatment which reached a maximum after 7 days of treatment and was maintained for the 2 week treatment period. Pre-treatment with mecamylamine (1 mg kg(-1)) prevented the expression of the locomotor stimulant effects of nicotine but pre-treatment with i.c.v. alpha-bgt (0.02 nmoles) did not affect nicotine-induced changes in locomotor activity. The results of this study support the conclusion that nicotinic receptors of the alpha4beta2 subtype rather than the alpha7 subtype are important in mediating the expression of the locomotor stimulant effects of nicotine.
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Affiliation(s)
- F E Kempsill
- Department of Physiology and Pharmacology, University of Strathclyde, Strathclyde Institute for Biomedical Sciences, Taylor Street, Glasgow G4 ONR
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Abstract
The neuropeptide corticotropin-releasing factor (CRE) and related neuropeptides not only mediate hormonal responses to stressors but also have a neurotropic role in the central nervous system to mediate behavioral responses to stressors. CRF antagonists effectively block CRF responses and have effects opposite those of CRF in many stress-related situations. Recent advances suggest that in addition to CRF itself there is another CRF-related neuropeptide, urocortin, that may be involved in stress-related responses, particularly those involving appetite. At least two CRF receptors have been discovered to date, CRF-1 and CRF-2. CRF may be involved in various aspects of the addiction cycle associated with drugs of abuse. CRF appears to be activated during stress-induced reinstatement of drug taking as well as acute withdrawal from all major drugs of abuse. CRF is hypothesized to be part of an allostatic change leading to vulnerability to relapse during prolonged abstinence from drugs of abuse.
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Affiliation(s)
- G F Koob
- Department of Neuropharmacology, Scripps Research Institute, La Jolla, California 92037, USA.
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Kanýt L, Stolerman IP, Chandler CJ, Saigusa T, Pöğün S. Influence of sex and female hormones on nicotine-induced changes in locomotor activity in rats. Pharmacol Biochem Behav 1999; 62:179-87. [PMID: 9972862 DOI: 10.1016/s0091-3057(98)00140-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The acute and chronic effects of nicotine (0.4 mg/kg s.c.) on locomotor activity in photocell cages have been compared in male, female, and ovariectomized hooded rats. In Experiment 1, female rats displayed higher locomotion than males (n = 12); acutely, nicotine-reduced locomotion, and this effect was slightly larger in females than males. Daily administration of nicotine for 21 days produced a similar, gradual increase in activity in both sexes. Tests then confirmed greater activity in females than males and as a function of previous chronic exposure to nicotine (n = 6); there was an activating effect of nicotine challenge but no interaction of nicotine effects with sex. In Experiment 2, ovariectomized rats were primed with 17-beta-estradiol (50 microg/kg s.c.) and progesterone (2.5 mg/kg s.c.) or vehicle only. Acute administration of nicotine reduced activity in both groups similarly (n = 12). After nicotine daily for 21 days, there was increased activity as a function of both chronic nicotine and hormonal priming, and challenge with nicotine increased activity (n = 6). The effects of these challenges with nicotine were also slightly greater, as a function of previous nicotine exposure and priming. As a whole, these experiments showed robust effects of acute and chronic nicotine administration, sex, and hormonal priming; neither sex nor gonadal hormones had marked influences on changes in locomotor activity produced by nicotine.
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Affiliation(s)
- L Kanýt
- EGE University Center for Brain Research, School of Medicine, Department of Physiology, Bornova, Izmir, Turkey
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13
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Pietilä K, Salminen O, Leikola-Pelho T, Ahtee L. Tolerance to nicotine's effects on striatal dopamine metabolism in nicotine-withdrawn mice. Eur J Pharmacol 1996; 318:17-22. [PMID: 9007507 DOI: 10.1016/s0014-2999(96)00767-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
After 7-week chronic administration of nicotine to mice in their drinking water, nicotine was withdrawn for 24 h. Acute nicotine challenge (1 mg/kg s.c., 60 min) elevated the striatal concentrations of dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) and decreased the concentration of 3-methoxytyramine significantly less in the mice withdrawn for 24 h from nicotine than in the control mice which had been drinking tap water under identical conditions for 7 weeks. Neither withdrawal nor the acute nicotine challenge altered the striatal dopamine concentration. No alterations were found in the density or affinity of the specific binding of [3H]SCH 23390 or [3H]spiperone to striatal membrane homogenates during nicotine treatment or after its withdrawal. Thus, our results show that tolerance to the acute effects of nicotine on striatal dopamine metabolism can be induced by administering nicotine to mice in the drinking water. However, neither chronic nicotine treatment nor its withdrawal seem to affect dopamine D1 and D2 receptors in the striatum.
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Affiliation(s)
- K Pietilä
- Department of Pharmacy, University of Helsinki, Finland
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Affiliation(s)
- Jed E. Rose
- Department of Psychiatry, Duke University, Durham, North Carolina
| | - Eric C. Westman
- VA Medical Center, Duke University, Durham, North Carolina
- Department of Medicine, Duke University, Durham, North Carolina
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15
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Abdulla FA, Bradbury E, Calaminici MR, Lippiello PM, Wonnacott S, Gray JA, Sinden JD. Relationship between up-regulation of nicotine binding sites in rat brain and delayed cognitive enhancement observed after chronic or acute nicotinic receptor stimulation. Psychopharmacology (Berl) 1996; 124:323-31. [PMID: 8739547 DOI: 10.1007/bf02247437] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
(-)-Nicotine tartrate (2 mg/kg), and a nicotinic agonist, RJR 2403 (1.4 mg/kg), and antagonist, mecamylamine (1 mg/kg), were administered to separate groups of rats SC twice daily for 10 days. Two other groups received the same doses of nicotine or RJR 2403 for 1 day followed by saline for 9 days. Twenty-four hours after the final injection, the rats were compared to a 10-day saline-injected group on acquisition of a hidden platform position in the Morris water maze (20 trials, 30-min inter-trial interval). The rats were killed 48 h after the last drug injection and frontal, entorhinal and posterior cingulate cortex and dorsal and ventral hippocampus assayed for [3H]-nicotine binding density. Chronic nicotine significantly increased the number of frontal and entorhinal cortical and dorsal hippocampal, but not posterior cingulate cortical or ventral hippocampal, nicotinic receptors, and improved rate of learning. Chronic mecamylamine and RJR 2403 also significantly increased the number of nicotinic receptors in frontal cortex, though not other regions, but retarded rate of learning. Nicotine given for 1 day 11 days earlier marginally increased nicotinic receptors in entorhinal cortex (but not other regions) and significantly increased rate of learning, though significantly less than 10-day nicotine. Entorhinal cortical and dorsal hippocampal nicotinic receptor numbers were positively associated with rate of learning but not performance at asymptote. Thus cognitive enhancement after chronic nicotine is in part a delayed consequence of nicotine administration 11 days earlier, and may reflect regional changes in nicotinic receptor up-regulation.
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Affiliation(s)
- F A Abdulla
- Department of Psychology, Institute of Psychiatry, London, UK
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16
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el-Bizri H, Clarke PB. Regulation of nicotinic receptors in rat brain following quasi-irreversible nicotinic blockade by chlorisondamine and chronic treatment with nicotine. Br J Pharmacol 1994; 113:917-25. [PMID: 7858886 PMCID: PMC1510460 DOI: 10.1111/j.1476-5381.1994.tb17080.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
1. Chronic administration of nicotinic agonists in vivo increases the density of brain nicotinic binding sites. It has been proposed that this up-regulation results from agonist-induced functional blockade of nicotinic receptors. This hypothesis was tested by examining post mortem [3H]-nicotine and [125I]-alpha-bungarotoxin ([125I]-alpha BTX) binding following treatment in vivo with the quasi-irreversible and insurmountable CNS nicotinic blocker chlorisondamine, given either alone or in combination with chronic nicotine administration. 2. In rats that had not received chlorisondamine pretreatment, chronic nicotine administration (0.6 mg kg-1 s.c., twice daily for 12 days) increased [3H]-nicotine binding density (Bmax) in forebrain tissue sections by 19%, with no change in the apparent dissociation constant (KD). Chlorisondamine (10 mg kg-1, s.c.), given once prior to the chronic treatment phase, neither increased [3H]-nicotine binding by itself, nor altered the extent of nicotine-induced up-regulation. Nevertheless, chlorisondamine pretreatment resulted in a persistent blockade of CNS nicotinic receptors, as demonstrated by complete block of acute locomotor responses to nicotine. 3. In a second experiment, [3H]-nicotine and [125I]-alpha BTX binding was measured in tissue homogenates prepared from several brain regions. In the absence of chlorisondamine pretreatment, chronic nicotine administration (1 mg kg-1 s.c., twice daily for 12 days) increased the Bmax of [3H]-nicotine binding in the cerebral cortex (by 34%), striatum (by 28%), midbrain (by 16%) and hippocampus (by 36%); KD was unchanged. As before, this up-regulation was neither mimicked nor blocked by chlorisondamine pretreatment (10 mg kg-1, s.c., given twice), despite persistent blockade of acute locomotor responses to nicotine. Chronic nicotine treatment also increased the Bmax (but not KD) of [125I]-alpha BTX binding in cerebral cortex (by 35%), hippocampus (by 46%) and midbrain (by 35%). Chlorisondamine altered neither Bmax nor KD when given alone, but significantly attenuated the nicotine-induced up-regulation of toxin binding sites in midbrain, with a similar trend in the other two regions.4. The finding that chronic receptor blockade neither mimicked nor blocked the agonist-induced up-regulation of [3H]-nicotine binding sites suggests that up-regulation of these receptors is not determined by their functional status. In contrast, it appears that chronic nicotine-induced up-regulation of[125I]-alpha BTX binding sites may result from receptor activation.
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Affiliation(s)
- H el-Bizri
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
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