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Andrew PM, Feng W, Calsbeek JJ, Antrobus SP, Cherednychenko GA, MacMahon JA, Bernardino PN, Liu X, Harvey DJ, Lein PJ, Pessah IN. The α4 Nicotinic Acetylcholine Receptor Is Necessary for the Initiation of Organophosphate-Induced Neuronal Hyperexcitability. TOXICS 2024; 12:263. [PMID: 38668486 PMCID: PMC11054284 DOI: 10.3390/toxics12040263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/20/2024] [Accepted: 03/27/2024] [Indexed: 04/29/2024]
Abstract
Acute intoxication with organophosphorus (OP) cholinesterase inhibitors can produce seizures that rapidly progress to life-threatening status epilepticus. Significant research effort has been focused on investigating the involvement of muscarinic acetylcholine receptors (mAChRs) in OP-induced seizure activity. In contrast, there has been far less attention on nicotinic AChRs (nAChRs) in this context. Here, we address this data gap using a combination of in vitro and in vivo models. Pharmacological antagonism and genetic deletion of α4, but not α7, nAChR subunits prevented or significantly attenuated OP-induced electrical spike activity in acute hippocampal slices and seizure activity in mice, indicating that α4 nAChR activation is necessary for neuronal hyperexcitability triggered by acute OP exposures. These findings not only suggest that therapeutic strategies for inhibiting the α4 nAChR subunit warrant further investigation as prophylactic and immediate treatments for acute OP-induced seizures, but also provide mechanistic insight into the role of the nicotinic cholinergic system in seizure generation.
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Affiliation(s)
- Peter M. Andrew
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Wei Feng
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Jonas J. Calsbeek
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Shane P. Antrobus
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Gennady A. Cherednychenko
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Jeremy A. MacMahon
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Pedro N. Bernardino
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Xiuzhen Liu
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Danielle J. Harvey
- Department of Public Health Sciences, UC Davis School of Medicine, Davis, CA 95616, USA;
| | - Pamela J. Lein
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Isaac N. Pessah
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
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Chellian R, Behnood-Rod A, Bruijnzeel AW. Mifepristone decreases nicotine intake in dependent and non-dependent adult rats. J Psychopharmacol 2024; 38:280-296. [PMID: 38332661 PMCID: PMC11061865 DOI: 10.1177/02698811241230255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
BACKGROUND Addiction to tobacco and nicotine products has adverse health effects and afflicts more than a billion people worldwide. Therefore, there is an urgent need for new treatments to reduce tobacco and nicotine use. Glucocorticoid receptor blockade shows promise as a novel treatment for drug abuse and stress-related disorders. AIM These studies aim to investigate whether glucocorticoid receptor blockade with mifepristone diminishes the reinforcing properties of nicotine in rats with intermittent or daily long access to nicotine. METHODS The rats self-administered 0.06 mg/kg/inf of nicotine for 6 h per day, with either intermittent or daily access for 4 weeks before treatment with mifepristone. Daily nicotine self-administration models regular smoking, while intermittent nicotine self-administration models occasional smoking. To determine whether the rats were dependent, they were treated with the nicotinic acetylcholine receptor antagonist mecamylamine, and somatic signs were recorded. RESULTS The rats with intermittent access to nicotine had a higher level of nicotine intake per session than those with daily access but only the rats with daily access to nicotine showed signs of physical dependence. Furthermore, mecamylamine increased nicotine intake during the first hour of access in rats with daily access but not in those with intermittent access. Mifepristone decreased total nicotine intake in rats with intermittent and daily access to nicotine. Moreover, mifepristone decreased the distance traveled and rearing in the open field test and operant responding for food pellets. CONCLUSION These findings indicate that mifepristone decreases nicotine intake but this effect may be partially attributed to the sedative effects of mifepristone.
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Affiliation(s)
| | - Azin Behnood-Rod
- Department of Psychiatry, University of Florida, Gainesville, FL, USA
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Kaneko S, Niki Y, Yamada K, Nasukawa D, Ujihara Y, Toda K. Systemic injection of nicotinic acetylcholine receptor antagonist mecamylamine affects licking, eyelid size, and locomotor and autonomic activities but not temporal prediction in male mice. Mol Brain 2022; 15:77. [PMID: 36068635 PMCID: PMC9450238 DOI: 10.1186/s13041-022-00959-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 08/05/2022] [Indexed: 12/26/2022] Open
Abstract
Nicotinic acetylcholine receptors are thought to be associated with a wide range of phenomena, such as movement, learning, memory, attention, and addiction. However, the causal relationship between nicotinic receptor activity and behavior remains unclear. Contrary to the studies that examined the functions of muscarinic acetylcholine receptors, the role of the nicotinic acetylcholine receptors on behavior has not been examined as extensively. Here, we examined the effects of intraperitoneal injection of mecamylamine, a nicotinic acetylcholine receptor antagonist, on the performance of male mice in a head-fixed temporal conditioning task and a free-moving open-field task. The head-fixed experimental setup allowed us to record and precisely quantify the licking response while the mice performed the behavioral task with no external cues. In addition, by combining the utility of the head-fixed experimental design with computer vision analysis based on deep learning algorithms, we succeeded in quantifying the eyelid size of awake mice. In the temporal conditioning task, we delivered a 10% sucrose solution every 10 s using a blunt-tipped needle placed within the licking distance of the mice. After the training, the mice showed increased anticipatory licking toward the timing of sucrose delivery, suggesting that the mice could predict the timing of the reward. Systemic injection of mecamylamine decreased licking behavior and caused eye closure but had no effect on learned conditioned predictive behavior in the head-fixed temporal conditioning task. In addition, the injection of mecamylamine decreased spontaneous locomotor activity in a dose-dependent manner in the free-moving open-field task. The results in the open-field experiments further revealed that the effect of mecamylamine on fecal output and urination, suggesting the effects on autonomic activities. Our achievement of successful eyelid size recording has potential as a useful approach in initial screening for drug discovery. Our study paves a way forward to understanding the role of nicotinic acetylcholine receptors on learning and behavior.
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Affiliation(s)
- Shohei Kaneko
- Department of Psychology, Keio University, Mita 2-15-45, Minato-ku, Tokyo, Japan
| | - Yasuyuki Niki
- Department of Psychology, Keio University, Mita 2-15-45, Minato-ku, Tokyo, Japan
| | - Kota Yamada
- Department of Psychology, Keio University, Mita 2-15-45, Minato-ku, Tokyo, Japan
- Japan Society for Promotion of Science, Tokyo, Japan
| | - Daiki Nasukawa
- Department of Psychology, Keio University, Mita 2-15-45, Minato-ku, Tokyo, Japan
| | - Yusuke Ujihara
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, TN, Memphis, USA
| | - Koji Toda
- Department of Psychology, Keio University, Mita 2-15-45, Minato-ku, Tokyo, Japan.
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Geste JR, Levin B, Wilks I, Pompilus M, Zhang X, Esser KA, Febo M, O'Dell L, Bruijnzeel AW. Relationship Between Nicotine Intake and Reward Function in Rats With Intermittent Short Versus Long Access to Nicotine. Nicotine Tob Res 2020; 22:213-223. [PMID: 30958557 DOI: 10.1093/ntr/ntz052] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 04/01/2019] [Indexed: 11/12/2022]
Abstract
INTRODUCTION Tobacco use improves mood states and smoking cessation leads to anhedonia, which contributes to relapse. Animal studies have shown that noncontingent nicotine administration enhances brain reward function and leads to dependence. However, little is known about the effects of nicotine self-administration on the state of the reward system. METHODS To investigate the relationship between nicotine self-administration and reward function, rats were prepared with intracranial self-stimulation electrodes and intravenous catheters. The rats were trained on the intracranial self-stimulation procedure and allowed to self-administer 0.03 mg/kg/infusion of nicotine. All rats self-administered nicotine daily for 10 days (1 hour/day) and were then switched to an intermittent short access (ShA, 1 hour/day) or long access (LgA, 23 hour/day) schedule (2 days/week, 5 weeks). RESULTS During the first 10 daily, 1-hour sessions, nicotine self-administration decreased the reward thresholds, which indicates that nicotine potentiates reward function. After switching to the intermittent LgA or ShA schedule, nicotine intake was lower in the ShA rats than the LgA rats. The LgA rats increased their nicotine intake over time and they gradually consumed a higher percentage of their nicotine during the light phase. The nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine induced a larger increase in reward thresholds (ie, anhedonia) in the LgA rats than the ShA rats. In the LgA rats, nAChR blockade with mecamylamine decreased nicotine intake for 2 hours and this was followed by a rebound increase in nicotine intake. CONCLUSIONS A brief period of nicotine self-administration enhances reward function and a high level of nicotine intake leads to dependence. IMPLICATIONS These animal studies indicate that there is a strong relationship between the level of nicotine intake and brain reward function. A high level of nicotine intake was more rewarding than a low level of nicotine intake and nicotine dependence was observed after long, but not short, access to nicotine. This powerful combination of nicotine reward and withdrawal makes it difficult to quit smoking. Blockade of nAChRs temporarily decreased nicotine intake, but this was followed by a large rebound increase in nicotine intake. Therefore, nAChR blockade might not decrease the use of combustible cigarettes or electronic cigarettes.
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Affiliation(s)
- Jean R Geste
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Brandon Levin
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Isaac Wilks
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Marjory Pompilus
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Xiping Zhang
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL
| | - Karyn A Esser
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL
| | - Marcelo Febo
- Department of Psychiatry, University of Florida, Gainesville, FL.,Department of Neuroscience, University of Florida, Gainesville, FL
| | - Laura O'Dell
- Department of Psychology, University of Texas at El Paso, El Paso, TX
| | - Adriaan W Bruijnzeel
- Department of Psychiatry, University of Florida, Gainesville, FL.,Department of Neuroscience, University of Florida, Gainesville, FL
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Reno CM, Bayles J, Huang Y, Oxspring M, Hirahara AM, Dosdall DJ, Fisher SJ. Severe Hypoglycemia-Induced Fatal Cardiac Arrhythmias Are Mediated by the Parasympathetic Nervous System in Rats. Diabetes 2019; 68:2107-2119. [PMID: 31439645 PMCID: PMC7118248 DOI: 10.2337/db19-0306] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 08/09/2019] [Indexed: 12/17/2022]
Abstract
The contribution of the sympathetic nervous system (SNS) versus the parasympathetic nervous system (PSNS) in mediating fatal cardiac arrhythmias during insulin-induced severe hypoglycemia is not well understood. Therefore, experimental protocols were performed in nondiabetic Sprague-Dawley rats to test the SNS with 1) adrenal demedullation and 2) chemical sympathectomy, and to test the PSNS with 3) surgical vagotomy, 4) nicotinic receptor (mecamylamine) and muscarinic receptor (AQ-RA 741) blockade, and 5) ex vivo heart perfusions with normal or low glucose, acetylcholine (ACh), and/or mecamylamine. In protocols 1-4, 3-h hyperinsulinemic (0.2 units/kg/min) and hypoglycemic (10-15 mg/dL) clamps were performed. Adrenal demedullation and chemical sympathectomy had no effect on mortality or arrhythmias during severe hypoglycemia compared with controls. Vagotomy led to a 6.9-fold decrease in mortality; reduced first- and second-degree heart block 4.6- and 4-fold, respectively; and prevented third-degree heart block compared with controls. Pharmacological blockade of nicotinic receptors, but not muscarinic receptors, prevented heart block and mortality versus controls. Ex vivo heart perfusions demonstrated that neither low glucose nor ACh alone caused arrhythmias, but their combination induced heart block that could be abrogated by nicotinic receptor blockade. Taken together, ACh activation of nicotinic receptors via the vagus nerve is the primary mediator of severe hypoglycemia-induced fatal cardiac arrhythmias.
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Affiliation(s)
- Candace M Reno
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Justin Bayles
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Yiqing Huang
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Milan Oxspring
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Annie M Hirahara
- Nora Eccles Harrison Cardiovascular Research & Training Institute, University of Utah, Salt Lake City, UT
| | - Derek J Dosdall
- Nora Eccles Harrison Cardiovascular Research & Training Institute, University of Utah, Salt Lake City, UT
| | - Simon J Fisher
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, UT
- Department of Biochemistry, University of Utah, Salt Lake City, UT
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Correa VL, Flores RJ, Carcoba LM, Arreguin MC, O'Dell LE. Sex differences in cholinergic systems in the interpeduncular nucleus following nicotine exposure and withdrawal. Neuropharmacology 2019; 158:107714. [PMID: 31325431 DOI: 10.1016/j.neuropharm.2019.107714] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 07/01/2019] [Accepted: 07/15/2019] [Indexed: 12/27/2022]
Abstract
The medial habenula-interpeduncular nucleus (MHb-IPN) pathway modulates negative affective states produced by nicotine withdrawal. Sex differences in the contribution of acetylcholine (ACh) systems in this pathway have not been explored. Thus, this study assessed ACh levels and gene expression of α- and β-containing nicotinic acetylcholine receptor (nAChR) subunits in the IPN of female and male rats following nicotine treatment and withdrawal. Rats were prepared with a pump that delivered nicotine for 14 days, and naïve controls received a sham surgery. In Study 1, rats were prepared with a probe in the IPN, and ACh levels were measured following saline and then mecamylamine administration. In Study 2, separate groups of naïve control or nicotine-treated rats received saline or mecamylamine and physical signs and anxiety-like behavior were assessed using elevated plus maze (EPM) procedures. The IPN was then dissected and mRNA levels were assessed using RT-qPCR methods. Nicotine treatment increased ACh levels to a larger extent in females than males. Nicotine withdrawal produced a similar increase in physical signs; however, females displayed greater anxiety-like behavior than males. In females, gene expression of α5 increased following nicotine treatment and withdrawal. In males, α7 increased following nicotine treatment and α2 and α3 increased during nicotine withdrawal. Both females and males displayed an increase in β3 and β4 during nicotine withdrawal. In females, anxiety-like behavior was correlated with α4, α5, and β2 gene expression in the IPN. These results suggest that sex differences in withdrawal are modulated via cholinergic systems in the IPN.
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Affiliation(s)
- Victor L Correa
- Department of Psychology, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX, USA
| | - Rodolfo J Flores
- Department of Psychology, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX, USA
| | - Luis M Carcoba
- Department of Psychology, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX, USA
| | - Montserrat C Arreguin
- Department of Psychology, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX, USA
| | - Laura E O'Dell
- Department of Psychology, The University of Texas at El Paso, 500 West University Avenue, El Paso, TX, USA.
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Self-administration of the synthetic cathinone MDPV enhances reward function via a nicotinic receptor dependent mechanism. Neuropharmacology 2018; 137:286-296. [PMID: 29778945 DOI: 10.1016/j.neuropharm.2018.05.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 03/30/2018] [Accepted: 05/06/2018] [Indexed: 01/28/2023]
Abstract
Methylenedioxypyrovalerone (MDPV) is an addictive synthetic drug with severe side effects. Previous studies have shown that MDPV has positive reinforcing properties. However, little is known about the effect of MDPV self-administration on the state of the brain reward system and the neuronal mechanisms by which MDPV mediates its effects. The goal of the present studies was to determine the effect of MDPV self-administration on reward function and the role of cholinergic neurotransmission in the reinforcing effects of MDPV. To study the effect of MDPV self-administration on the brain reward system, rats were prepared with intravenous catheters and intracranial self-stimulation electrodes (ICSS). For 10 days, the reward thresholds were assessed immediately before (23 h post prior session) and after 1 h of MDPV self-administration. The reward thresholds were decreased immediately after MDPV self-administration, which is indicative of a potentiation of brain reward function. The reward thresholds 23 h after MDPV intake gradually increased over time, which is indicative of anhedonia. Pretreatment with the nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine decreased the self-administration of MDPV and completely prevented the decrease in reward thresholds. A control study with palatable chocolate pellets showed that responding for a natural reinforcer does not affect the state of the brain reward system. Furthermore, mecamylamine did not affect responding for food pellets. In conclusion, the self-administration of MDPV potentiates reward function and nAChR blockade prevents the reward enhancing effects of MDPV self-administration. Preventing the MDPV-induced increase in cholinergic neurotransmission might be a safe approach to diminish MDPV abuse.
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Harris AC, Muelken P, Smethells JR, Krueger M, LeSage MG. Similar precipitated withdrawal effects on intracranial self-stimulation during chronic infusion of an e-cigarette liquid or nicotine alone. Pharmacol Biochem Behav 2017; 161:1-5. [PMID: 28867606 DOI: 10.1016/j.pbb.2017.08.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 08/28/2017] [Accepted: 08/30/2017] [Indexed: 11/19/2022]
Abstract
The FDA recently extended their regulatory authority to electronic cigarettes (ECs). Because the abuse liability of ECs is a leading concern of the FDA, animal models are urgently needed to identify factors that influence the relative abuse liability of these products. The ability of tobacco products to induce nicotine dependence, defined by the emergence of anhedonia and other symptoms of nicotine withdrawal following cessation of their use, contributes to tobacco abuse liability. The present study compared the severity of precipitated withdrawal during chronic infusion of nicotine alone or nicotine-dose equivalent concentrations of three different EC refill liquids in rats, as indicated by elevations in intracranial self-stimulation (ICSS) thresholds (anhedonia-like behavior). Because these EC liquids contain constituents that may enhance their abuse liability (e.g., minor alkaloids), we hypothesized that they would be associated with greater withdrawal effects than nicotine alone. Results indicated that the nicotinic acetylcholine receptor antagonist mecamylamine precipitated elevations in ICSS thresholds in rats receiving a chronic infusion of nicotine alone or EC liquids (3.2mg/kg/day, via osmotic pump). Magnitude of this effect did not differ between formulations. Our findings indicate that nicotine alone is the primary CNS determinant of the ability of ECs to engender dependence. Combined with our previous findings that nicotine alone and these EC liquids do not differ in other preclinical addiction models, these data suggest that product standards set by the FDA to reduce EC abuse liability should primarily target nicotine, other constituents with peripheral sensory effects (e.g. flavorants), and factors that influence product appeal (e.g., marketing).
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Affiliation(s)
- A C Harris
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN, USA; Department of Medicine, University of Minnesota, Minneapolis, MN, USA; Department of Psychology, University of Minnesota, Minneapolis, MN, USA.
| | - P Muelken
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN, USA
| | - J R Smethells
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN, USA; Department of Psychiatry, University of Minnesota, Minneapolis, MN, USA
| | - M Krueger
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN, USA; Department of Psychology, University of Minnesota, Minneapolis, MN, USA
| | - M G LeSage
- Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN, USA; Department of Medicine, University of Minnesota, Minneapolis, MN, USA; Department of Psychology, University of Minnesota, Minneapolis, MN, USA
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Carpenter-Hyland EP, Griffeth J, Bunting K, Terry A, Vazdarjanova A, Blake DT. Tone identification behavior in Rattus norvegicus: muscarinic receptor blockage lowers responsiveness in nontarget selective neurons, while nicotinic receptor blockage selectively lowers target responses. Eur J Neurosci 2017; 46:1779-1789. [PMID: 28544049 DOI: 10.1111/ejn.13611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 04/24/2017] [Accepted: 05/14/2017] [Indexed: 11/30/2022]
Abstract
Learning to associate a stimulus with reinforcement causes plasticity in primary sensory cortex. Neural activity caused by the associated stimulus is paired with reinforcement, but population analyses have not found a selective increase in response to that stimulus. Responses to other stimuli increase as much as, or more than, responses to the associated stimulus. Here, we applied population analysis at a new time point and additionally evaluated whether cholinergic receptor blockers interacted with the plastic changes in cortex. Three days of tone identification behavior caused responsiveness to increase broadly across primary auditory cortex, and target responses strengthened less than overall responsiveness. In pharmacology studies, behaviorally impairing doses of selective acetylcholine receptor blockers were administered during behavior. Neural responses were evaluated on the following day, while the blockers were absent. The muscarinic group, blocked by scopolamine, showed lower responsiveness and an increased response to the tone identification target that exceeded both the 3-day control group and task-naïve controls. Also, a selective increase in the late phase of the response to the tone identification stimulus emerged. Nicotinic receptor antagonism, with mecamylamine, more modestly lowered responses the following day and lowered target responses more than overall responses. Control acute studies demonstrated the muscarinic block did not acutely alter response rates, but the nicotinic block did. These results lead to the hypothesis that the decrease in the proportion of the population spiking response that is selective for the target may be explained by the balance between effects modulated by muscarinic and nicotinic receptors.
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Affiliation(s)
| | - Jackson Griffeth
- Department of Neurology, Brain and Behavior Discovery Institute, Augusta University, 1120 15th St CL-3031, Augusta, GA, 30912, USA
| | - Kristopher Bunting
- Department of Pharmacology and Toxicology, Augusta University, Augusta, GA, USA
| | - Alvin Terry
- Department of Pharmacology and Toxicology, Augusta University, Augusta, GA, USA
| | - Almira Vazdarjanova
- Department of Pharmacology and Toxicology, Augusta University, Augusta, GA, USA.,VA Research Service, Charlie Norwood VA Medical Center, Augusta, GA, USA
| | - David T Blake
- Department of Neurology, Brain and Behavior Discovery Institute, Augusta University, 1120 15th St CL-3031, Augusta, GA, 30912, USA
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Bruijnzeel AW. Neuropeptide systems and new treatments for nicotine addiction. Psychopharmacology (Berl) 2017; 234:1419-1437. [PMID: 28028605 PMCID: PMC5420481 DOI: 10.1007/s00213-016-4513-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 12/12/2016] [Indexed: 01/08/2023]
Abstract
RATIONALE The mildly euphoric and cognitive enhancing effects of nicotine play a role in the initiation of smoking, while dysphoria and anxiety associated with smoking cessation contribute to relapse. After the acute withdrawal phase, smoking cues, a few cigarettes (i.e., lapse), and stressors can cause relapse. Human and animal studies have shown that neuropeptides play a critical role in nicotine addiction. OBJECTIVES The goal of this paper is to describe the role of neuropeptide systems in the initiation of nicotine intake, nicotine withdrawal, and the reinstatement of extinguished nicotine seeking. RESULTS The reviewed studies indicate that several drugs that target neuropeptide systems diminish the rewarding effects of nicotine by preventing the activation of dopaminergic systems. Other peptide-based drugs diminish the hyperactivity of brain stress systems and diminish withdrawal-associated symptom severity. Blockade of hypocretin-1 and nociceptin receptors and stimulation of galanin and neurotensin receptors diminishes the rewarding effects of nicotine. Both corticotropin-releasing factor type 1 and kappa-opioid receptor antagonists diminish dysphoria and anxiety-like behavior associated with nicotine withdrawal and inhibit stress-induced reinstatement of nicotine seeking. Furthermore, blockade of vasopressin 1b receptors diminishes dysphoria during nicotine withdrawal, and melanocortin 4 receptor blockade prevents stress-induced reinstatement of nicotine seeking. The role of neuropeptide systems in nicotine-primed and cue-induced reinstatement is largely unexplored, but there is evidence for a role of hypocretin-1 receptors in cue-induced reinstatement of nicotine seeking. CONCLUSION Drugs that target neuropeptide systems might decrease the euphoric effects of smoking and improve relapse rates by diminishing withdrawal symptoms and improving stress resilience.
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Affiliation(s)
- Adriaan W. Bruijnzeel
- Department of Psychiatry, University of Florida, Gainesville, Florida, USA,Department of Neuroscience, University of Florida, Gainesville, Florida, USA,Center for Addiction Research and Education, University of Florida, Gainesville, Florida, USA
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A Two-Day Continuous Nicotine Infusion Is Sufficient to Demonstrate Nicotine Withdrawal in Rats as Measured Using Intracranial Self-Stimulation. PLoS One 2015; 10:e0144553. [PMID: 26658557 PMCID: PMC4684239 DOI: 10.1371/journal.pone.0144553] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 11/19/2015] [Indexed: 01/23/2023] Open
Abstract
Avoidance of the negative affective (emotional) symptoms of nicotine withdrawal (e.g., anhedonia, anxiety) contributes to tobacco addiction. Establishing the minimal nicotine exposure conditions required to demonstrate negative affective withdrawal signs in animals, as well as understanding moderators of these conditions, could inform tobacco addiction-related research, treatment, and policy. The goal of this study was to determine the minimal duration of continuous nicotine infusion required to demonstrate nicotine withdrawal in rats as measured by elevations in intracranial self-stimulation (ICSS) thresholds (anhedonia-like behavior). Administration of the nicotinic acetylcholine receptor antagonist mecamylamine (3.0 mg/kg, s.c.) on alternate test days throughout the course of a 2-week continuous nicotine infusion (3.2 mg/kg/day via osmotic minipump) elicited elevations in ICSS thresholds beginning on the second day of infusion. Magnitude of antagonist-precipitated withdrawal did not change with further nicotine exposure and mecamylamine injections, and was similar to that observed in a positive control group receiving mecamylamine following a 14-day nicotine infusion. Expression of a significant withdrawal effect was delayed in nicotine-infused rats receiving mecamylamine on all test days rather than on alternate test days. In a separate study, rats exhibited a transient increase in ICSS thresholds following cessation of a 2-day continuous nicotine infusion (3.2 mg/kg/day). Magnitude of this spontaneous withdrawal effect was similar to that observed in rats receiving a 9-day nicotine infusion. Our findings demonstrate that rats exhibit antagonist-precipitated and spontaneous nicotine withdrawal following a 2-day continuous nicotine infusion, at least under the experimental conditions studied here. Magnitude of these effects were similar to those observed in traditional models involving more prolonged nicotine exposure. Further development of these models, including evaluation of more clinically relevant nicotine dosing regimens and other measures of nicotine withdrawal (e.g., anxiety-like behavior, somatic signs), may be useful for understanding the development of the nicotine withdrawal syndrome.
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Qi X, Guzhva L, Ji Y, Bruijnzeel AW. Chronic treatment with the vasopressin 1b receptor antagonist SSR149415 prevents the dysphoria associated with nicotine withdrawal in rats. Behav Brain Res 2015; 292:259-65. [PMID: 26112757 DOI: 10.1016/j.bbr.2015.06.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 06/15/2015] [Accepted: 06/19/2015] [Indexed: 11/29/2022]
Abstract
Nicotine addiction is a chronic brain disorder that is characterized by dysphoria upon smoking cessation and relapse after brief periods of abstinence. It has been hypothesized that the negative mood state associated with nicotine withdrawal is partly mediated by a heightened activity of brain stress systems. Animal studies suggest that blockade of vasopressin 1b (V1b) receptors diminishes high levels of drug intake in dependent animals and attenuates the emotional response to stressors. The goal of the present studies was to investigate the effect of acute and chronic treatment with the V1b receptor antagonist SSR149415 on the negative mood state associated with nicotine withdrawal in rats. An intracranial self-stimulation (ICSS) procedure was used to assess mood states and nicotine dependence was induced using minipumps. The nicotinic receptor antagonist mecamylamine was used to precipitate withdrawal. Mecamylamine elevated the brain reward thresholds of the nicotine dependent rats, which reflects a negative mood state. Mecamylamine did not affect the brain reward thresholds of the saline-treated control rats. Chronic treatment with SSR149415 completely prevented the elevations in brain reward thresholds associated with nicotine withdrawal while acute treatment only partly prevented nicotine withdrawal. These data suggest that chronic treatment with V1b receptor antagonists may prevent the dysphoria associated with smoking cessation and thereby improve relapse rates.
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Affiliation(s)
- Xiaoli Qi
- Department of Psychiatry, University of Florida, Gainesville, Florida 32611, USA
| | - Lidia Guzhva
- Department of Psychiatry, University of Florida, Gainesville, Florida 32611, USA
| | - Yue Ji
- Department of Psychiatry, University of Florida, Gainesville, Florida 32611, USA
| | - Adriaan W Bruijnzeel
- Department of Psychiatry, University of Florida, Gainesville, Florida 32611, USA; Department of Neuroscience, University of Florida, Gainesville, Florida 32611, USA
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Madsen HB, Koghar HS, Pooters T, Massalas JS, Drago J, Lawrence AJ. Role of α4- and α6-containing nicotinic receptors in the acquisition and maintenance of nicotine self-administration. Addict Biol 2015; 20:500-12. [PMID: 24750355 DOI: 10.1111/adb.12148] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Tobacco smoking is a major cause of death and disease and as such there is a critical need for the development of new therapeutic approaches to treat nicotine addiction. Here, we utilize genetic and pharmacological tools to further investigate the nicotinic acetylcholine receptor (nAChR) subtypes that support intravenous self-administration of nicotine. α4-S248F mice contain a point mutation within the α4 nAChR subunit which confers increased sensitivity to nicotine and resistance to mecamylamine. Here, we show that acute administration of mecamylamine (2 mg/kg, i.p.) reduces established nicotine self-administration (0.05 mg/kg/infusion) in wild-type (WT), but not in α4-S248F heterozygous mice, demonstrating a role for α4* nAChRs in the modulation of ongoing nicotine self-administration. Administration of N,N-decane-1,10-diyl-bis-3-picolinium diiodide (bPiDI), a selective α6β2* nAChR antagonist, dose dependently (5 and 10 mg/kg, i.p.) impairs the acquisition of nicotine self-administration and reduces established nicotine self-administration in WT mice when administered acutely (10 mg/kg, i.p.). This was not due to a general reduction in locomotor activity and the same dose of bPiDI did not affect operant responding for sucrose. bPiDI treatment (10 mg/kg, i.p.) also impaired both the acquisition and maintenance of nicotine self-administration in α4-S248F heterozygous mice. This provides further evidence for the involvement of α6β2* nAChRs in the reinforcing effects of nicotine that underlies its ability to support ongoing self-administration. Taken together, selective targeting of α6β2* or α4α6β2* nAChRs may prove to be an effective strategy for the development of smoking cessation therapies.
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Affiliation(s)
- Heather B. Madsen
- Florey Institute of Neuroscience and Mental Health; University of Melbourne; Australia
| | - Harcharan S. Koghar
- Florey Institute of Neuroscience and Mental Health; University of Melbourne; Australia
| | - Tine Pooters
- Florey Institute of Neuroscience and Mental Health; University of Melbourne; Australia
- Laboratory of Biological Psychology; University of Leuven; Belgium
| | - Jim S. Massalas
- Florey Institute of Neuroscience and Mental Health; University of Melbourne; Australia
| | - John Drago
- Florey Institute of Neuroscience and Mental Health; University of Melbourne; Australia
| | - Andrew J. Lawrence
- Florey Institute of Neuroscience and Mental Health; University of Melbourne; Australia
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Song JN, Zhang M, Li DD, Li M, An JY, Cheng MF, Guo XY. Dynamic expression of the suppressor of cytokine signaling-3 and cytokines in the cerebral basilar artery of rats with subarachnoid hemorrhage, and the effect of acetylcholine. Acta Neurochir (Wien) 2014; 156:941-9; discussion 949. [PMID: 24463741 DOI: 10.1007/s00701-014-1998-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 01/09/2014] [Indexed: 11/30/2022]
Abstract
BACKGROUND There are complex interactions between acetylcholine (ACh), the suppressor of cytokine signaling-3 (SOCS-3), and cytokines, however, little is known about their dynamic expression or their effects on cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH). Therefore, we aimed to describe and clarify the dynamic expression of SOCS-3 and cytokines after SAH, as well as the relationships between the levels of SOCS-3, cytokines, and ACh. METHODS The rat model of single cisterna magna injection was used to mimic acute SAH. The degree of CVS was indicated by lumen diameter and artery wall thickness under H&E staining. A semi-quantitative immunohistochemical analysis method was used to clarify the role of SOCS-3 in the CVS after SAH. We also measured the content of IL-6 and IL-10 in cerebrospinal fluid. RESULTS We found that SOCS-3 expression levels increased rapidly within 12 h after SAH, more slowly after 12 h, and did not reach a peak within 48 h. Interleukin 6 (IL-6) levels rapidly increased within 24 h after SAH, reached a peak 24 h after SAH, and decreased slightly at 48 h. IL-10 levels increased during the first 6 h after SAH, after which this increase tapered off. ACh treatment reduced IL-6 levels and resulted in elevated levels of SOCS-3, but had no effect on IL-10 expression. Furthermore, ACh treatment relieved basilar arterial vasospasm, whereas mecamylamine pretreatment counteracted the activity of ACh. CONCLUSIONS Taken together, these data indicate that SOCS-3 was involved in vasospasm via an IL-6- and IL-10-related mechanism, and that CVS following SAH could be reversed by the intraventricular injection of ACh.
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Affiliation(s)
- Jin-Ning Song
- Department of Neurosurgery, The First Affiliated Hospital, Medical School of Xi'an Jiaotong University, Xi' an, Shaanxi, People's Republic of China,
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15
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Varenicline and cytisine diminish the dysphoric-like state associated with spontaneous nicotine withdrawal in rats. Neuropsychopharmacology 2014; 39:455-65. [PMID: 23966067 PMCID: PMC3870769 DOI: 10.1038/npp.2013.216] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/07/2013] [Accepted: 08/11/2013] [Indexed: 02/04/2023]
Abstract
Tobacco addiction is characterized by a negative mood state upon smoking cessation and relapse after periods of abstinence. Clinical studies indicate that negative mood states lead to craving and relapse. The partial α4/α6/β2* nicotinic acetylcholine receptor (nAChR) agonists varenicline and cytisine are widely used as smoking cessation treatments. Varenicline has been approved in the United States for smoking cessation and cytisine is used in Eastern European countries. Despite the widespread use of these compounds, very little is known about their effects on mood states. These studies investigated the effects of varenicline, cytisine, and the cytisine-derivative 3-(pyridin-3'-yl)-cytisine (3-pyr-Cyt) on brain reward function in nicotine-naive and nicotine-withdrawing rats. The cytisine-derivative 3-pyr-Cyt is a very weak α4β2* nAChR partial agonist and like cytisine and varenicline has antidepressant-like effects in animal models. The intracranial self-stimulation (ICSS) procedure was used to investigate the effects of these compounds on brain reward function. Elevations in ICSS thresholds reflect a dysphoric state and a lowering of thresholds is indicative of a potentiation of brain reward function. It was shown that acute administration of nicotine and varenicline lowered ICSS thresholds. Acute administration of cytisine or 3-pyr-Cyt did not affect ICSS thresholds. Discontinuation of chronic, 14 days, nicotine administration led to elevations in ICSS thresholds that lasted for about 2 days. Varenicline and cytisine, but not 3-pyr-Cyt, diminished the nicotine withdrawal-induced elevations in ICSS thresholds. In conclusion, these studies indicate that varenicline and cytisine diminish the dysphoric-like state associated with nicotine withdrawal and may thereby prevent relapse to smoking in humans.
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16
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Effects of oxytocin on nicotine withdrawal in rats. Pharmacol Biochem Behav 2014; 116:84-9. [DOI: 10.1016/j.pbb.2013.11.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 10/31/2013] [Accepted: 11/07/2013] [Indexed: 12/16/2022]
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Scheidweiler KB, Shakleya DM, Huestis MA. Simultaneous quantification of nicotine, cotinine, trans-3'-hydroxycotinine, norcotinine and mecamylamine in human urine by liquid chromatography-tandem mass spectrometry. Clin Chim Acta 2012; 413:978-84. [PMID: 22394455 PMCID: PMC3319642 DOI: 10.1016/j.cca.2012.02.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 02/10/2012] [Accepted: 02/11/2012] [Indexed: 11/22/2022]
Abstract
BACKGROUND Mecamylamine is a nicotine antagonist under investigation in combination with nicotine replacement for smoking treatment. METHODS A simple, rapid and reliable liquid chromatography tandem mass spectrometry (LCMSMS) method was developed and validated for quantifying nicotine, cotinine, trans-3'-hydroxycotinine, norcotinine and mecamylamine in human urine. Chromatography was performed on a Synergi PolarRP column with a gradient of 0.1% formic acid and 0.1% formic acid in acetonitrile at 0.25 ml/min with an 8-min total runtime. Analytes were monitored by positive mode electrospray ionization and multiple reaction monitoring mass spectrometry. RESULTS Linear dynamic ranges were 1-500 ng/ml for nicotine and norcotinine, 0.5-500 ng/ml for trans-3'-hydroxycotinine, 0.2-500 ng/ml for cotinine, and 0.1-100 ng/ml for mecamylamine; correlation coefficients were consistently greater than 0.99, and all calibrator concentrations were within 20% of target. Extensive endogenous and exogenous interferences were evaluated. At 3 concentrations spanning the linear dynamic range of the assay, mean extraction efficiencies from urine were 55.1-109.1% with analytical recovery (bias) 82.0-118.7% and total imprecision of 0.7-9.1%. Analytes were stable for 24h at room temperature, 72 h at 4 °C, 72 h in autosampler at 15 °C and after three freeze/thaw cycles. CONCLUSION This method is useful for monitoring mecamylamine, nicotine and nicotine metabolites in smoking cessation and other clinical nicotine research.
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Affiliation(s)
- Karl B. Scheidweiler
- Chemistry and Drug Metabolism, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Diaa M. Shakleya
- Chemistry and Drug Metabolism, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Marilyn A. Huestis
- Chemistry and Drug Metabolism, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
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Bruijnzeel AW, Ford J, Rogers JA, Scheick S, Ji Y, Bishnoi M, Alexander JC. Blockade of CRF1 receptors in the central nucleus of the amygdala attenuates the dysphoria associated with nicotine withdrawal in rats. Pharmacol Biochem Behav 2012; 101:62-8. [PMID: 22182462 PMCID: PMC3315052 DOI: 10.1016/j.pbb.2011.12.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 11/23/2011] [Accepted: 12/03/2011] [Indexed: 11/26/2022]
Abstract
The majority of smokers relapse during the acute withdrawal phase when withdrawal symptoms are most severe. The goal of the present studies was to investigate the role of corticotropin-releasing factor (CRF) and noradrenergic transmission in the central nucleus of the amygdala (CeA) in the dysphoria associated with smoking cessation. It was investigated if blockade of CRF1 receptors, blockade of α1-adrenergic receptors, or stimulation of α2-adrenergic receptors in the CeA diminishes the deficit in brain reward function associated with nicotine withdrawal in rats. Nicotine dependence was induced by implanting minipumps that delivered a nicotine solution. Withdrawal was precipitated with the nicotinic acetylcholine receptor antagonist mecamylamine. A discrete-trial intracranial self-stimulation procedure was used to assess the negative affective aspects of nicotine withdrawal. Elevations in brain reward thresholds are indicative of a deficit in brain reward function. In all the experiments, mecamylamine elevated the brain reward thresholds of the rats chronically treated with nicotine and did not affect the brain reward thresholds of the saline-treated control rats. Intra-CeA administration of the CRF1 receptor antagonist R278995/CRA0450 completely prevented the mecamylamine-induced elevations in brain reward thresholds in the nicotine-treated rats and did not affect the brain reward thresholds of the saline-treated control rats. R278995/CRA0450 has also been shown to block sigma-1 receptors but there is no evidence that this could affect negative mood states. Intra-CeA administration of the α1-adrenergic receptor antagonist prazosin or the α2-adrenergic receptor agonist clonidine did not affect the brain reward thresholds of the nicotine or saline-treated rats. These studies suggest that CRF1 receptor antagonists may diminish the dysphoria associated with smoking cessation by blocking CRF1 receptors in the CeA.
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Affiliation(s)
- Adrie W Bruijnzeel
- Department of Psychiatry, McKnight Brain Institute, University of Florida, 100 S. Newell Dr., Gainesville, Florida 32610, USA.
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Park DI, Kim HG, Jung WR, Shin MK, Kim KL. Mecamylamine attenuates dexamethasone-induced anxiety-like behavior in association with brain derived neurotrophic factor upregulation in rat brains. Neuropharmacology 2011; 61:276-82. [DOI: 10.1016/j.neuropharm.2011.04.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 03/22/2011] [Accepted: 04/08/2011] [Indexed: 11/27/2022]
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The necessity of α4* nicotinic receptors in nicotine-driven behaviors: dissociation between reinforcing and motor effects of nicotine. Neuropsychopharmacology 2011; 36:1505-17. [PMID: 21430644 PMCID: PMC3096818 DOI: 10.1038/npp.2011.35] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Here we utilize a mouse line with a targeted deletion of the α4 subunit (α4-/- mice), to investigate the role of α4* nAChRs in reinforcing and locomotor effects of nicotine. Within a conditioned place preference paradigm, both α4-/- mice and wild-type (WT) littermates showed a similar place preference to nicotine (0.5 mg/kg i.p.) conditioning. When assessed for operant intravenous self-administration of nicotine (0.05 mg/kg/infusion), α4-/- mice did not differ from their WT littermates in self-administration behavior. To further examine a modulatory role for α4* nAChRs in the reinforcing effects of nicotine, a transgenic mouse with a point mutation of the α4 subunit (α4-S248F) that renders increased sensitivity to low dose nicotine, was assessed for nicotine self-administration over a range of doses. At higher doses examined (0.05 and 0.07 mg/kg/infusion) there was no difference in intravenous nicotine self-administration; however, when mice were offered a lower dose of nicotine (0.03 mg/kg/infusion), α4-S248F mice showed greater nicotine intake than controls. Acute administration of 0.5 mg/kg nicotine caused significant locomotor depression in WT mice but α4-/- mice instead showed significant hyperactivity. Following chronic, intermittent administration of this dose of nicotine only WT mice displayed significant tolerance. Analogous experiments utilizing administration of the nicotinic antagonist mecamylamine in WT mice confirmed a dissociation between the putative nicotinic receptor subtypes required for mediating psychomotor and reinforcing effects of nicotine. These data demonstrate a necessary role for α4* nAChRs in the locomotor depressant effect of nicotine but not the reinforcing effects that support ongoing self-administration of nicotine.
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Cardiopulmonary arrest and resuscitation disrupts cholinergic anti-inflammatory processes: a role for cholinergic α7 nicotinic receptors. J Neurosci 2011; 31:3446-52. [PMID: 21368056 DOI: 10.1523/jneurosci.4558-10.2011] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Cardiac arrest is a leading cause of death worldwide. While survival rates following sudden cardiac arrest remain relatively low, recent advancements in patient care have begun to increase the proportion of individuals who survive cardiac arrest. However, many of these individuals subsequently develop physiological and psychiatric conditions that likely result from ongoing neuroinflammation and neuronal death. The present study was conducted to better understand the pathophysiological effects of cardiac arrest on neuronal cell death and inflammation, and their modulation by the cholinergic system. Using a well validated model of cardiac arrest, here we show that global cerebral ischemia increases microglial activation, proinflammatory cytokine mRNA expression (interleukin-1β, interleukin-6, tumor necrosis factor-α), and neuronal damage. Cardiac arrest also induces alterations in numerous cellular components of central cholinergic signaling, including a reduction in choline acetyltransferase enzymatic activity and the number of choline acetyltransferase-positive neurons, as well as, reduced acetylcholinesterase and vesicular acetylcholine transporter mRNA. However, treatment with a selective agonist of the α7 nicotinic acetylcholine receptor, the primary receptor mediating the cholinergic anti-inflammatory pathway, significantly decreases the neuroinflammation and neuronal damage resulting from cardiac arrest. These data suggest that global cerebral ischemia results in significant declines in central cholinergic signaling, which may in turn diminish the capacity of the cholinergic anti-inflammatory pathway to control inflammation. Furthermore, we provide evidence that pharmacological activation of α7 nicotinic acetylcholine receptors provide significant protection against ischemia-related cell death and inflammation within a clinically relevant time frame.
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Bruijnzeel AW, Bishnoi M, van Tuijl IA, Keijzers KFM, Yavarovich KR, Pasek TM, Ford J, Alexander JC, Yamada H. Effects of prazosin, clonidine, and propranolol on the elevations in brain reward thresholds and somatic signs associated with nicotine withdrawal in rats. Psychopharmacology (Berl) 2010; 212:485-99. [PMID: 20697697 PMCID: PMC3042243 DOI: 10.1007/s00213-010-1970-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Accepted: 07/20/2010] [Indexed: 11/26/2022]
Abstract
RATIONALE Tobacco withdrawal is characterized by a negative mood state and relatively mild somatic symptoms. Increased noradrenergic transmission has been reported to play an important role in opioid withdrawal, but little is known about the role of noradrenergic transmission in nicotine withdrawal. OBJECTIVES The aim of these experiments was to investigate the effects of prazosin, clonidine, and propranolol on the negative mood state and somatic signs associated with nicotine withdrawal in rats. METHODS A discrete-trial intracranial self-stimulation procedure was used to assess the negative affective state of nicotine withdrawal. Elevations in brain reward thresholds are indicative of a deficit in brain reward function. RESULTS In all the experiments, the nicotinic acetylcholine receptor antagonist mecamylamine (3 mg/kg) elevated the brain reward thresholds of the nicotine-treated rats and did not affect those of the control rats. The α1-adrenergic receptor antagonist prazosin (0.0625 and 0.125 mg/kg) dose-dependently attenuated the elevations in brain reward thresholds associated with precipitated nicotine withdrawal. The α2-adrenergic receptor agonist clonidine (10-40 μg/kg) and the nonselective β-adrenergic receptor antagonist propranolol (2.5-10 mg/kg) did not attenuate the elevations in brain reward thresholds associated with nicotine withdrawal. Furthermore, mecamylamine (2 mg/kg) induced more somatic signs in the nicotine-treated rats than in the control rats. Clonidine and propranolol, but not prazosin, decreased the total number of somatic signs associated with nicotine withdrawal. CONCLUSION Blockade of α1-adrenergic receptors attenuates the deficit in brain reward function associated with nicotine withdrawal. Antagonism of β-adrenergic receptors or stimulation of α2-adrenergic receptors attenuates the somatic symptoms of nicotine withdrawal.
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Affiliation(s)
- Adrie W Bruijnzeel
- Department of Psychiatry, McKnight Brain Institute, University of Florida, 100 S. Newell Dr., P.O. Box 100256, Gainesville, FL 32610, USA.
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Yamada H, Bishnoi M, Keijzers KFM, van Tuijl IA, Small E, Shah HP, Bauzo RM, Kobeissy FH, Sabarinath SN, Derendorf H, Bruijnzeel AW. Preadolescent tobacco smoke exposure leads to acute nicotine dependence but does not affect the rewarding effects of nicotine or nicotine withdrawal in adulthood in rats. Pharmacol Biochem Behav 2010; 95:401-9. [PMID: 20211642 DOI: 10.1016/j.pbb.2010.02.018] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Revised: 02/24/2010] [Accepted: 02/28/2010] [Indexed: 10/19/2022]
Abstract
Epidemiological studies indicate that parental smoking increases the risk for smoking in children. However, the underlying mechanisms by which parental smoking increases the risk for smoking are not known. The aim of these studies was to investigate if preadolescent tobacco smoke exposure, postnatal days 21-35, affects the rewarding effects of nicotine and nicotine withdrawal in adult rats. The rewarding effects of nicotine were investigated with the conditioned place preference procedure. Nicotine withdrawal was investigated with the conditioned place aversion procedure and intracranial self-stimulation (ICSS). Elevations in brain reward thresholds in the ICSS paradigm reflect a dysphoric state. Plasma nicotine and cotinine levels in the preadolescent rats immediately after smoke exposure were 188 ng/ml and 716 ng/ml, respectively. Preadolescent tobacco smoke exposure led to the development of nicotine dependence as indicated by an increased number of mecamylamine-precipitated somatic withdrawal signs in the preadolescent tobacco smoke exposed rats compared to the control rats. Nicotine induced a similar place preference in adult rats that had been exposed to tobacco smoke or air during preadolescence. Furthermore, mecamylamine induced place aversion in nicotine dependent rats but there was no effect of preadolescent tobacco smoke exposure. Finally, preadolescent tobacco smoke exposure did not affect the elevations in brain reward thresholds associated with precipitated or spontaneous nicotine withdrawal. These studies indicate that passive exposure to tobacco smoke during preadolescence leads to the development of nicotine dependence but preadolescent tobacco smoke exposure does not seem to affect the rewarding effects of nicotine or nicotine withdrawal in adulthood.
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Affiliation(s)
- Hidetaka Yamada
- Department of Psychiatry, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
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24
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Small E, Shah HP, Davenport JJ, Geier JE, Yavarovich KR, Yamada H, Sabarinath SN, Derendorf H, Pauly JR, Gold MS, Bruijnzeel AW. Tobacco smoke exposure induces nicotine dependence in rats. Psychopharmacology (Berl) 2010; 208:143-58. [PMID: 19936715 PMCID: PMC3586198 DOI: 10.1007/s00213-009-1716-z] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Accepted: 10/26/2009] [Indexed: 11/26/2022]
Abstract
RATIONALE Tobacco smoke contains nicotine and many other compounds that act in concert on the brain reward system. Therefore, animal models are needed that allow the investigation of chronic exposure to the full spectrum of tobacco smoke constituents. OBJECTIVES The aim of these studies was to investigate if exposure to tobacco smoke leads to nicotine dependence in rats. METHODS The intracranial self-stimulation procedure was used to assess the negative affective aspects of nicotine withdrawal. Somatic signs were recorded from a checklist of nicotine abstinence signs. Nicotine self-administration sessions were conducted to investigate if tobacco smoke exposure affects the motivation to self-administer nicotine. Nicotinic receptor autoradiography was used to investigate if exposure to tobacco smoke affects central alpha7 nicotinic acetylcholine receptor (nAChR) and non-alpha7 nAChR levels (primarily alpha4beta2 nAChRs). RESULTS The nAChR antagonist mecamylamine dose-dependently elevated the brain reward thresholds of the rats exposed to tobacco smoke and did not affect the brain reward thresholds of the untreated control rats. Furthermore, mecamylamine induced more somatic withdrawal signs in the smoke-exposed rats than in the control rats. Nicotine self-administration was decreased 1 day after the last tobacco smoke exposure sessions and was returned to control levels 5 days later. Tobacco smoke exposure increased the alpha7 nAChR density in the CA2/3 area and the stratum oriens and increased the non-alpha7 nAChR density in the dentate gyrus. CONCLUSION Tobacco smoke exposure leads to nicotine dependence as indicated by precipitated affective and somatic withdrawal signs and induces an upregulation of nAChRs in the hippocampus.
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Affiliation(s)
- Elysia Small
- Department of Psychiatry, College of Medicine, McKnight Brain Institute, University of Florida, 100 S. Newell Dr., PO Box 100256, Gainesville, FL 32610, USA
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Marcinkiewcz CA, Prado MM, Isaac SK, Marshall A, Rylkova D, Bruijnzeel AW. Corticotropin-releasing factor within the central nucleus of the amygdala and the nucleus accumbens shell mediates the negative affective state of nicotine withdrawal in rats. Neuropsychopharmacology 2009; 34:1743-52. [PMID: 19145226 PMCID: PMC2680924 DOI: 10.1038/npp.2008.231] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Tobacco addiction is a chronic disorder that is characterized by a negative affective state upon smoking cessation and relapse after periods of abstinence. Previous research has shown that an increased central release of corticotropin-releasing factor (CRF) at least partly mediates the deficit in brain reward function associated with nicotine withdrawal in rats. The aim of these studies was to investigate the role of CRF in the central nucleus of the amygdala (CeA), the lateral bed nucleus of the stria terminalis (BNST), and the nucleus accumbens shell (Nacc shell) in the deficit in brain reward function associated with precipitated nicotine withdrawal. The intracranial self-stimulation procedure was used to assess the negative affective aspects of nicotine withdrawal. Elevations in brain reward thresholds are indicative of a deficit in brain reward function. In all experiments, the nicotinic receptor antagonist mecamylamine (3 mg/kg) elevated the brain reward thresholds of the nicotine-dependent rats (9 mg/kg per day of nicotine salt) and did not affect the brain reward thresholds of the saline-treated control rats. The administration of the nonspecific CRF1/2 receptor antagonist D-Phe CRF((12-41)) into the CeA and the Nacc shell prevented the mecamylamine-induced elevations in brain reward thresholds in the nicotine-dependent rats. Blockade of CRF1/2 receptors in the lateral BNST did not prevent the mecamylamine-induced elevations in brain reward thresholds in the nicotine-dependent rats. These studies indicate that the negative emotional state associated with precipitated nicotine withdrawal is at least partly mediated by an increased release of CRF in the CeA and the Nacc shell.
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Affiliation(s)
- Catherine A Marcinkiewcz
- Department of Psychiatry, College of Medicine, University of Florida, Gainesville, FL 32610 , USA
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Jackson KJ, Kota DH, Martin BR, Damaj MI. The role of various nicotinic receptor subunits and factors influencing nicotine conditioned place aversion. Neuropharmacology 2009; 56:970-4. [PMID: 19371584 DOI: 10.1016/j.neuropharm.2009.01.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 01/26/2009] [Accepted: 01/28/2009] [Indexed: 11/16/2022]
Abstract
Affective nicotine withdrawal symptoms are of major motivational significance in contributing to relapse and continued tobacco use; thus, it is important to understand the molecular and receptor-mediated mechanisms that mediate affective withdrawal behaviors. Previous work using the conditioned place aversion (CPA) model has shown that nicotine withdrawal is associated with a negative affective state, and place aversion to previously neutral environmental stimuli represents a motivational component in the maintenance of drug use. Thus, the purpose of this study was to evaluate the role of genotype, sex, and age and to extend previous studies examining the role of various nicotinic receptor subtypes in the development of nicotine withdrawal aversion using the CPA model. Mice were chronically treated with nicotine and conditioned for two days with various nicotinic receptor antagonists. The major findings showed that mecamylamine and dihydro-beta-erythroidine (DHbetaE), but not hexamethonium or methyllycaconitine citrate (MLA), precipitated significant aversion in the CPA model. This pharmacological data support our previous knockout mouse data suggesting that nicotine CPA is mediated by central beta2-containing nicotinic receptors, but not alpha7 nicotinic receptors. Further, we show that sex and age are contributing factors to the development of nicotine CPA. Overall, the results of our study provide some insight into pharmacological and behavioral factors involved in the development of an aversive motivational component associated with nicotine withdrawal.
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Affiliation(s)
- K J Jackson
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, 410 N. 12th Street, P.O. Box 980613, Richmond, VA 23298, USA.
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27
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Rylkova D, Boissoneault J, Isaac S, Prado M, Shah HP, Bruijnzeel AW. Effects of NPY and the specific Y1 receptor agonist [D-His(26)]-NPY on the deficit in brain reward function and somatic signs associated with nicotine withdrawal in rats. Neuropeptides 2008; 42:215-27. [PMID: 18468678 PMCID: PMC2435593 DOI: 10.1016/j.npep.2008.03.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Accepted: 03/28/2008] [Indexed: 11/25/2022]
Abstract
Tobacco addiction is a chronic disorder that is characterized by dysphoria upon smoking cessation and relapse after periods of abstinence. Previous research suggests that Neuropeptide Y (NPY) and Y1 receptor agonists attenuate negative affective states and somatic withdrawal signs. The aim of the present experiments was to investigate the effects of NPY and the specific Y1 receptor agonist [D-His(26)]-NPY on the deficit in brain reward function and somatic signs associated with nicotine withdrawal in rats. The intracranial self-stimulation procedure was used to assess the effects of nicotine withdrawal on brain reward function as this procedure can provide a quantitative measure of emotional states in rodents. Elevations in brain reward thresholds are indicative of a deficit in brain reward function. In the first experiment, NPY did not prevent the elevations in brain reward thresholds associated with precipitated nicotine withdrawal and elevated the brain reward thresholds of the saline-treated control rats. Similar to NPY, [D-His(26)]-NPY did not prevent the elevations in brain reward thresholds associated with precipitated nicotine withdrawal and elevated the brain reward thresholds of the saline-treated control rats. Neither NPY nor [D-His(26)]-NPY affected the response latencies. In a separate experiment, it was demonstrated that the specific Y1 receptor antagonist BIBP-3226 prevented the NPY-induced elevations in brain reward thresholds. NPY attenuated the overall somatic signs associated with precipitated nicotine withdrawal. [D-His(26)]-NPY did not affect the overall somatic signs associated with precipitated nicotine withdrawal, but decreased the number of abdominal constrictions. Both NPY and [D-His(26)]-NPY attenuated the overall somatic signs associated with spontaneous nicotine withdrawal. These findings indicate that NPY and [D-His(26)]-NPY attenuate somatic nicotine withdrawal signs, but do not prevent the deficit in brain reward function associated with precipitated nicotine withdrawal. In addition, NPY decreases the sensitivity to rewarding electrical stimuli via an Y1 dependent mechanism.
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Affiliation(s)
- Daria Rylkova
- Department of Psychiatry, University of Florida, Gainesville, FL 32610, USA
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28
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Angus DW, Baker JA, Mason R, Martin IJ. The potential influence of CO2, as an agent for euthanasia, on the pharmacokinetics of basic compounds in rodents. Drug Metab Dispos 2007; 36:375-9. [PMID: 18006649 DOI: 10.1124/dmd.107.018879] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Rodent tissue distribution and pharmacokinetic studies were performed on basic compounds Org A and Org B in support of central nervous system drug discovery programs. A consistent observation from these studies was that drug concentrations in plasma obtained by cardiac puncture after CO(2) euthanasia were markedly higher compared with those from other sampling methods (serial sampling, isoflurane anesthesia, or cervical dislocation). Further investigations demonstrated that CO(2) euthanasia led to a reduction in blood pH in both rats and mice, which was not observed with the other sampling methods. The use of CO(2) euthanasia resulted in a decrease in the brain/plasma ratio of Org B, largely as a result of increased plasma concentrations. The pharmacokinetics of a basic drug, raloxifene, in rat were also influenced by sampling technique. CO(2) euthanasia before sampling, resulted in a 2- to 3-fold increase in the area under the drug concentration-time curve, a decrease in plasma clearance, and a decrease in the steady-state volume of distribution compared with isoflurane anesthesia. It is proposed that a decrease in the pH of blood relative to that of other tissues, as a consequence of CO(2) exposure, results in a redistribution of basic compounds out of the tissues, leading to higher concentrations in plasma.
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Affiliation(s)
- Derek W Angus
- Department of Pharmacology, Organon Laboratories Ltd., Newhouse, Lanarkshire, United Kingdom
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29
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CRF-CRF1 system activation mediates withdrawal-induced increases in nicotine self-administration in nicotine-dependent rats. Proc Natl Acad Sci U S A 2007; 104:17198-203. [PMID: 17921249 DOI: 10.1073/pnas.0707585104] [Citation(s) in RCA: 189] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nicotine, the main psychoactive ingredient of tobacco, induces negative emotional symptoms during abstinence that contribute to a profound craving for nicotine. However, the neurobiological mechanisms underlying how nicotine produces dependence remains poorly understood. We demonstrate one mechanism for both the anxiety-like symptoms of withdrawal and excessive nicotine intake observed after abstinence, through recruitment of the extrahypothalamic stress peptide corticotropin-releasing factor (CRF) system and activation of CRF(1) receptors. Overactivation of the CRF-CRF(1) system may contribute to nicotine dependence and may represent a prominent target for investigating the vulnerability to tobacco addiction.
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Zhang Y, Laster MJ, Eger EI, Sharma M, Sonner JM. Blockade of acetylcholine receptors does not change the dose of etomidate required to produce immobility in rats. Anesth Analg 2007; 104:850-2. [PMID: 17377093 DOI: 10.1213/01.ane.0000258018.82583.0b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Administration of drugs blocking muscarinic plus neuronal nicotinic acetylcholine receptors (e.g., atropine and mecamylamine) does not affect the MAC of isoflurane. Although this implies that acetylcholine receptors do not mediate the immobility produced by inhaled anesthetics, another interpretation is possible. Sub-MAC concentrations of isoflurane alone profoundly block acetylcholine receptors, allowing for the possibility that atropine and mecamylamine have no effect because the receptors already are blocked. METHODS In the present study, we indirectly tested this possibility by measuring the capacity of acetylcholine receptor blockade to decrease the anesthetic requirement for etomidate, an anesthetic thought to act solely by enhancing the effect of gamma-aminobutyric acid on gamma-aminobutyric acid(A) receptors. RESULTS Administration of 10 mg/kg atropine plus 5 mg/kg mecamylamine did not change the infusion rate of etomidate, or the blood or brain concentrations of etomidate required to produce immobility in rats. CONCLUSION Acetylcholine receptors do not mediate the capacity of anesthetics to produce immobility in the face of noxious stimulation.
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Affiliation(s)
- Yi Zhang
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, California 94143-0464, USA
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31
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Bruijnzeel AW, Zislis G, Wilson C, Gold MS. Antagonism of CRF receptors prevents the deficit in brain reward function associated with precipitated nicotine withdrawal in rats. Neuropsychopharmacology 2007; 32:955-63. [PMID: 16943772 DOI: 10.1038/sj.npp.1301192] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Nicotine dependence is a chronic mental illness that is characterized by a negative affective state upon tobacco smoking cessation and relapse after periods of abstinence. It has been hypothesized that cessation of nicotine administration results in the activation of brain corticotropin-releasing factor (CRF) systems that leads to the negative affective state of withdrawal. The aim of our experiments was to investigate the role of brain CRF systems in the deficit in brain reward function associated with the cessation of nicotine administration in rats. The intracranial self-stimulation procedure was used to assess to negative affective aspects of nicotine withdrawal as this procedure can provide a quantitative measure of emotional distress in rats. In the first experiment, mecamylamine induced a dose-dependent elevation in brain reward thresholds in nicotine-treated rats. In the follow-up experiment, it was shown that pretreatment with the corticotropin-receptor antagonist D-Phe CRF((12-41)) prevents the elevations in brain reward thresholds associated with precipitated nicotine withdrawal. In the third experiment, the effect of D-Phe CRF((12-41)) on the elevations in brain reward thresholds associated with spontaneous nicotine withdrawal was investigated. Administration of D-Phe CRF((12-41)) 6 h after the explantation of the nicotine pumps, did not result in a lowering of the brain reward thresholds. These findings indicate that antagonism of CRF receptors prevents, but not reverses, the deficit in brain associated with nicotine withdrawal. These data provide support for the hypothesis that a hyperactivity of brain CRF systems may at least partly mediate the initiation of the negative affective aspects of nicotine withdrawal.
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Affiliation(s)
- Adrie W Bruijnzeel
- Department of Psychiatry, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
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32
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Phillips JM, Ehrlichman RS, Siegel SJ. Mecamylamine blocks nicotine-induced enhancement of the P20 auditory event-related potential and evoked gamma. Neuroscience 2006; 144:1314-23. [PMID: 17184927 PMCID: PMC1868669 DOI: 10.1016/j.neuroscience.2006.11.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Revised: 10/14/2006] [Accepted: 11/01/2006] [Indexed: 11/22/2022]
Abstract
Cigarette smoking is significantly more prevalent in individuals with schizophrenia than in non-affected populations. Certain neurocognitive deficits and disruptions common in schizophrenia may be altered by smoking, leading to the hypothesis that schizophrenics engage in smoking behavior to alleviate specific neurocognitive symptoms of the disorder. Additionally, research suggests that individuals with schizophrenia have altered auditory event-related potentials (ERPs) and abnormalities in evoked gamma oscillations which are both indices of sensory information processing. This study was conducted to examine the effect of acute administration of nicotine and the non-specific nicotinic antagonist mecamylamine on the P20 and N40 components of the ERP and evoked gamma oscillations in mice. Acute nicotine (1 mg/kg) significantly increased P20 amplitude, an effect that was blocked by pretreatment with mecamylamine (2 mg/kg). Additionally, acute nicotine increased the normal burst of evoked gamma following an auditory stimulus. The increase in evoked gamma was also blocked by mecamylamine pretreatment. Although acute nicotine decreased amplitude of the N40 component, this decrease was not attenuated by mecamylamine. These results replicate findings that nicotine may enhance early sensory information processing through the nicotinic acetylcholinergic receptor system in an established model (ERPs) and extend these findings in an emerging, novel model (evoked gamma oscillations) of sensory information processing. The results also support the hypothesis that nicotine may be beneficial to individuals with deficits in neurocognitive functions, such as those suffering from schizophrenia.
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Affiliation(s)
- J M Phillips
- Department of Psychiatry, University of Pennsylvania, Translational Research Laboratories, Room 2223, 125 South 31st Street, Philadelphia, PA 19104, USA
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33
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Vago DR, Kesner RP. Cholinergic modulation of Pavlovian fear conditioning in rats: differential effects of intrahippocampal infusion of mecamylamine and methyllycaconitine. Neurobiol Learn Mem 2006; 87:441-9. [PMID: 17178240 PMCID: PMC1951534 DOI: 10.1016/j.nlm.2006.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 11/01/2006] [Accepted: 11/03/2006] [Indexed: 11/16/2022]
Abstract
The cholinergic system has consistently been implicated in Pavlovian fear conditioning. Considerable work has been done to localize specific nicotinic receptor subtypes in the hippocampus and determine their functional importance; however, the specific function of many of these subtypes has yet to be determined. An alpha7 nicotinic antagonist methyllycaconitine (MLA) (35 microg), and a broad spectrum non-alpha7 nicotinic antagonist mecamylamine (35 microg) was injected directly into the dorsal hippocampus or overlying cortex either 15 min pre-, 1 min post-, or 6h post-fear conditioning. One week after conditioning, retention of contextual and cue (tone) conditioning were assessed. A significant impairment in retention of contextual fear was observed when mecamylamine was injected 15 min pre- and 1 min post-conditioning. No significant impairment was observed when mecamylamine was injected 6h post-conditioning. Likewise, a significant impairment in retention of contextual fear was observed when MLA was injected 1 min post-conditioning; however, in contrast, MLA did not show any significant impairments when injected 15 min pre-conditioning, but did show a significant impairment when injected 6h post-conditioning. There were no significant impairments observed when either drug was injected into overlying cortex. No significant impairments were observed in cue conditioning for either drug. In general, specific temporal dynamics involved in nicotinic receptor function were found relative to time of receptor dysfunction. The results indicate that the greatest deficits in long-term retention (1 week) of contextual fear are produced by central infusion of MLA minutes to hours post-conditioning or mecamylamine within minutes of conditioning.
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Affiliation(s)
- David R Vago
- Department of Psychology, University of Utah, 380 South 1530 East, Room 502, Salt Lake City, UT 84112, USA
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Bergmann R, Pietzsch J. Small animal positron emission tomography in food sciences. Amino Acids 2005; 29:355-76. [PMID: 16142524 DOI: 10.1007/s00726-005-0237-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Accepted: 07/13/2005] [Indexed: 02/07/2023]
Abstract
Positron emission tomography (PET) is a 3-dimensional imaging technique that has undergone tremendous developments during the last decade. Non-invasive tracing of molecular pathways in vivo is the key capability of PET. It has become an important tool in the diagnosis of human diseases as well as in biomedical and pharmaceutical research. In contrast to other imaging modalities, radiotracer concentrations can be determined quantitatively. By application of appropriate tracer kinetic models, the rate constants of numerous different biological processes can be determined. Rapid progress in PET radiochemistry has significantly increased the number of biologically important molecules labelled with PET nuclides to target a broader range of physiologic, metabolic, and molecular pathways. Progress in PET physics and technology strongly contributed to better scanners and image processing. In this context, dedicated high resolution scanners for dynamic PET studies in small laboratory animals are now available. These developments represent the driving force for the expansion of PET methodology into new areas of life sciences including food sciences. Small animal PET has a high potential to depict physiologic processes like absorption, distribution, metabolism, elimination and interactions of biologically significant substances, including nutrients, 'nutriceuticals', functional food ingredients, and foodborne toxicants. Based on present data, potential applications of small animal PET in food sciences are discussed.
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Affiliation(s)
- R Bergmann
- Positron Emission Tomography Center, Institute of Bioinorganic and Radiopharmaceutical Chemistry, Research Center Rossendorf, Dresden, Germany.
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35
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Sobrio F, Debruyne D, Dhilly M, Chazalviel L, Camsonne R, Kakiuchi T, Tsukada H, Barré L. Evaluation in rats and primates of [11C]-mecamylamine, a potential nicotinic acetylcholine receptor radioligand for positron emission tomography. Neurochem Int 2005; 46:479-88. [PMID: 15769550 DOI: 10.1016/j.neuint.2004.12.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2004] [Revised: 12/03/2004] [Accepted: 12/14/2004] [Indexed: 12/01/2022]
Abstract
Mecamylamine is a well-described non specific antagonist of nicotinic acetylcholine receptors (nAChRs), used in therapy and in psychopharmacological studies. [(11)C]-Mecamylamine was prepared and evaluated as a putative radioligand for positron emission tomography to study nicotinic acetylcholine receptors. The radiosynthesis consisted in the [(11)C]-methylation of the desmethyl precursor within 40 min with 30-40% radiochemical yield decay corrected. Biodistribution studies in rats showed that radioligand crossed the blood-brain barrier (0.39% ID at 30 min) and only unmetabolized tracer was recovered from brain at 45 min. Ex vivo autoradiography studies in rats did not indicate preferential uptake, and pre-treatment mecamylamine or with chlorisondamine, an nicotinic receptor inhibitor, did not demonstrate a significant specific binding. To investigate possible specie differences and effects of anesthesia, in vivo positron emission tomography (PET) studies were carried out on anaesthetized baboons and conscious macaques. The regional brain distribution of [(11)C]-mecamylamine in the two species of primates exhibited similar kinetics as did the rat with steady state reached about 45-50 min after radiotracer administration. Uptake values were two-fold higher in brain of conscious macaque than in anaesthetized baboon (thalamus: 0.258% ID/(kg mL) in conscious macaques and 0.129% ID/(kg mL) in baboons). PET images showed a radioactivity distribution which was quite homogeneous throughout the brain but with somewhat higher uptake in grey matter than in white. Brain distribution was unaltered by saturation or displacement studies. Possible explanation for the failure to establish specific binding in vivo could be long-lived structural modifications of the ionotropic channel by the unlabeled ligand administered before the tracer. In conclusion, [(11)C]-mecamylamine did not satisfy the requirements for a PET tracer of nicotinic acetylcholine receptors.
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Affiliation(s)
- Franck Sobrio
- DRM-DSV-CEA - UMR CEA FRE CNRS 2698, Centre Cyceron, BP 5229, F-14074 Caen, France.
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