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Seemiller LR, Logue SF, Gould TJ. Inbred mouse strain differences in alcohol and nicotine addiction-related phenotypes from adolescence to adulthood. Pharmacol Biochem Behav 2022; 218:173429. [PMID: 35820468 DOI: 10.1016/j.pbb.2022.173429] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 06/18/2022] [Accepted: 07/06/2022] [Indexed: 11/20/2022]
Abstract
Understanding the genetic basis of a predisposition for nicotine and alcohol use across the lifespan is important for public health efforts because genetic contributions may change with age. However, parsing apart subtle genetic contributions to complex human behaviors is a challenge. Animal models provide the opportunity to study the effects of genetic background and age on drug-related phenotypes, while controlling important experimental variables such as amount and timing of drug exposure. Addiction research in inbred, or isogenic, mouse lines has demonstrated genetic contributions to nicotine and alcohol abuse- and addiction-related behaviors. This review summarizes inbred mouse strain differences in alcohol and nicotine addiction-related phenotypes including voluntary consumption/self-administration, initial sensitivity to the drug as measured by sedative, hypothermic, and ataxic effects, locomotor effects, conditioned place preference or place aversion, drug metabolism, and severity of withdrawal symptoms. This review also discusses how these alcohol and nicotine addiction-related phenotypes change from adolescence to adulthood.
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Affiliation(s)
- Laurel R Seemiller
- Department of Biobehavioral Health, Penn State University, University Park, PA, USA
| | - Sheree F Logue
- Department of Biobehavioral Health, Penn State University, University Park, PA, USA
| | - Thomas J Gould
- Department of Biobehavioral Health, Penn State University, University Park, PA, USA.
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Banna FKE, Otto JM, Mulloy SM, Tsai W, McElroy SM, Wong AL, Cutts G, Vrieze SI, Lee AM. Back-translating GWAS findings to animal models reveals a role for Hgfac and Slc39a8 in alcohol and nicotine consumption. Sci Rep 2022; 12:9336. [PMID: 35661789 PMCID: PMC9167284 DOI: 10.1038/s41598-022-13283-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 05/23/2022] [Indexed: 11/09/2022] Open
Abstract
Alcohol and tobacco are the most commonly used addictive substances, with high comorbidity rates between alcohol use disorder and tobacco use disorder. Risk for alcohol and nicotine addiction is highly heritable, and they share common genetic factors. A GWAS in over 1 million individuals has revealed 566 genetic variants in 406 loci associated with multiple stages of alcohol and tobacco use. Three novel genes-SLC39A8, GRK4 and HGFAC-within loci associated with altered alcoholic drinks per week (ADW) or cigarettes per day (CPD) were selected to further study their role in alcohol and tobacco use disorder. The role of these genes was assessed using the two-bottle choice addiction paradigm in transgenic mice for each of the genes. We found significant decreases in chronic alcohol consumption and preference in female Hgfac knockout (KO) mice, and decreased nicotine preference in male Hgfac KO compared with wild-type (WT) mice. Additionally, male Slc39a8 hypomorph mice showed greater overall nicotine preference compared with WT mice, while no differences were detected for Grk4 KO mice in alcohol or nicotine consumption and preference in either sex. Thus, this study implicates Hgfac and Slc39a8 in alcohol and tobacco use in a sex-specific manner.
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Affiliation(s)
- F K El Banna
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA.,Department of Psychology, University of Minnesota, Minneapolis, MN, USA
| | - J M Otto
- Department of Psychology, University of Minnesota, Minneapolis, MN, USA
| | - S M Mulloy
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - W Tsai
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - S M McElroy
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - A L Wong
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - G Cutts
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - S I Vrieze
- Department of Psychology, University of Minnesota, Minneapolis, MN, USA
| | - A M Lee
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA.
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Carstens E, Carstens MI. Sensory Effects of Nicotine and Tobacco. Nicotine Tob Res 2022; 24:306-315. [PMID: 33955474 PMCID: PMC8842437 DOI: 10.1093/ntr/ntab086] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 04/28/2021] [Indexed: 12/21/2022]
Abstract
INTRODUCTION Ingestion of nicotine by smoking, vaping, or other means elicits various effects including reward, antinociception, and aversion due to irritation, bitter taste, and unpleasant side effects such as nausea and dizziness. AIMS AND METHODS Here we review the sensory effects of nicotine and the underlying neurobiological processes. RESULTS AND CONCLUSIONS Nicotine elicits oral irritation and pain via the activation of neuronal nicotinic acetylcholine receptors (nAChRs) expressed by trigeminal nociceptors. These nociceptors excite neurons in the trigeminal subnucleus caudalis (Vc) and other brainstem regions in a manner that is significantly reduced by the nAChR antagonist mecamylamine. Vc neurons are excited by lingual application of nicotine and exhibit a progressive decline in firing to subsequent applications, consistent with desensitization of peripheral sensory neurons and progressively declining ratings of oral irritation in human psychophysical experiments. Nicotine also elicits a nAChR-mediated bitter taste via excitation of gustatory afferents. Nicotine solutions are avoided even when sweeteners are added. Studies employing oral self-administration have yielded mixed results: Some studies show avoidance of nicotine while others report increased nicotine intake over time, particularly in adolescents and females. Nicotine is consistently reported to increase human pain threshold and tolerance levels. In animal studies, nicotine is antinociceptive when delivered by inhalation of tobacco smoke or systemic infusion, intrathecally, and by intracranial microinjection in the pedunculopontine tegmentum, ventrolateral periaqueductal gray, and rostral ventromedial medulla. The antinociception is thought to be mediated by descending inhibition of spinal nociceptive transmission. Menthol cross-desensitizes nicotine-evoked oral irritation, reducing harshness that may account for its popularity as a flavor additive to tobacco products. IMPLICATIONS Nicotine activates brain systems underlying reward and antinociception, but at the same time elicits aversive sensory effects including oral irritation and pain, bitter taste, and other unpleasant side effects mediated largely by nicotinic acetylcholine receptors (nAChRs). This review discusses the competing aversive and antinociceptive effects of nicotine and exposure to tobacco smoke, and the underlying neurobiology. An improved understanding of the interacting effects of nicotine will hopefully inform novel approaches to mitigate nicotine and tobacco use.
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Affiliation(s)
- Earl Carstens
- Department of Neurobiology, Physiology and Behavior University of California, Davis, CA, USA
| | - M Iodi Carstens
- Department of Neurobiology, Physiology and Behavior University of California, Davis, CA, USA
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Moen JK, Lee AM. Sex Differences in the Nicotinic Acetylcholine Receptor System of Rodents: Impacts on Nicotine and Alcohol Reward Behaviors. Front Neurosci 2021; 15:745783. [PMID: 34621155 PMCID: PMC8490611 DOI: 10.3389/fnins.2021.745783] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 08/31/2021] [Indexed: 12/20/2022] Open
Abstract
Alcohol and nicotine are the two most widely used and misused drugs around the world, and co-consumption of both substances is highly prevalent. Multiple lines of evidence show a profound effect of sex in many aspects of alcohol and nicotine reward, with women having more difficulty quitting smoking and showing a faster progression toward developing alcohol use disorder compared with men. Both alcohol and nicotine require neuronal nicotinic acetylcholine receptors (nAChRs) to elicit rewarding effects within the mesolimbic system, representing a shared molecular pathway that likely contributes to the frequent comorbidity of alcohol and nicotine dependence. However, the majority of preclinical studies on the mechanisms of alcohol and nicotine reward behaviors utilize only male rodents, and thus our understanding of alcohol and nicotine neuropharmacology relies heavily on male data. As preclinical research informs the development and refinement of therapies to help patients reduce drug consumption, it is critical to understand the way biological sex and sex hormones influence the rewarding properties of alcohol and nicotine. In this review, we summarize what is known about sex differences in rodent models of alcohol and nicotine reward behaviors with a focus on neuronal nAChRs, highlighting exciting areas for future research. Additionally, we discuss the way circulating sex hormones may interact with neuronal nAChRs to influence reward-related behavior.
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Affiliation(s)
- Janna K Moen
- Graduate Program in Neuroscience, University of Minnesota Twin Cities, Minneapolis, MN, United States
| | - Anna M Lee
- Graduate Program in Neuroscience, University of Minnesota Twin Cities, Minneapolis, MN, United States.,Department of Pharmacology, University of Minnesota Twin Cities, Minneapolis, MN, United States
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Wong AL, McElroy SM, Robinson JM, Mulloy SM, El Banna FK, Harris AC, LeSage MG, Lee AM. Flavor-specific enhancement of electronic cigarette liquid consumption and preference in mice. Drug Alcohol Depend 2020; 211:107995. [PMID: 32354580 PMCID: PMC7328293 DOI: 10.1016/j.drugalcdep.2020.107995] [Citation(s) in RCA: 12] [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: 12/03/2019] [Revised: 03/24/2020] [Accepted: 03/25/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND The use of electronic cigarettes has increased over the past decade. To determine how the abuse liability of electronic cigarette liquids (e-liquids) differs from nicotine alone, and to determine the impact of flavor, we compared nicotine-containing fruit- and tobacco-flavored e-liquids, and their nicotine-free versions, to nicotine alone in mouse models of oral consumption, reward and aversion. METHODS Adult male C57BL/6 J mice voluntarily consumed oral nicotine, equivalent nicotine concentrations of fruit- and tobacco-flavored e-liquid, and equivalent dilutions of the nicotine-free versions in 2-bottle choice tests. Conditioned place preference and place aversion were assessed with peripherally administered e-liquids or nicotine. Serum nicotine and cotinine levels were measured after subcutaneous injections of e-liquid or nicotine. RESULTS Mice showed higher consumption and preference for the fruit-flavored e-liquid compared with nicotine alone. This increase was not due to the flavor itself as consumption of the nicotine-free fruit-flavored e-liquid was not elevated until the highest concentration tested. The increased consumption and preference were not observed with the tobacco-flavored e-liquid. The conditioned place preference, place aversion and nicotine pharmacokinetics of the fruit-flavored e-liquid were not significantly different from nicotine alone. CONCLUSIONS Our data suggest that fruit, but not tobacco flavor, increased the oral consumption of e-liquid compared with nicotine alone. Moreover, this enhancement was not due to increased consumption of the flavor itself, altered rewarding or aversive properties after peripheral administration, or altered pharmacokinetics. This flavor-specific enhancement suggests that some flavors may lead to higher nicotine intake and increased use of e-liquids compared with nicotine alone.
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Affiliation(s)
- A L Wong
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - S M McElroy
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - J M Robinson
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - S M Mulloy
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - F K El Banna
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - A C Harris
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, USA; Department of Medicine, University of Minnesota, Minneapolis, MN, USA; Department of Medicine, Hennepin Healthcare Research Institute, Minneapolis, MN, USA; Department of Psychology, University of Minnesota, Minneapolis, MN, USA
| | - M G LeSage
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA; Department of Medicine, Hennepin Healthcare Research Institute, Minneapolis, MN, USA; Department of Psychology, University of Minnesota, Minneapolis, MN, USA
| | - A M Lee
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA; Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, USA.
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Bagdas D, Diester CM, Riley J, Carper M, Alkhlaif Y, AlOmari D, Alayoubi H, Poklis JL, Damaj MI. Assessing nicotine dependence using an oral nicotine free-choice paradigm in mice. Neuropharmacology 2019; 157:107669. [PMID: 31220484 DOI: 10.1016/j.neuropharm.2019.107669] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 06/03/2019] [Accepted: 06/12/2019] [Indexed: 01/30/2023]
Abstract
Models to assess the addictive-like properties of nicotine in mice are limited. Therefore, we aimed to characterize and validate an addiction index by using an oral nicotine free-choice paradigm in mice. Adult C57BL/6J, DBA/2J, or genetically modified mice carrying deletions for nicotinic acetylcholine receptor (nAChR) subunits, (n = 8-10/sex/group) were given a choice of water or nicotine (10-960 μg/ml) solution using a two-bottle free-choice (2BC) paradigm. In general, oral nicotine intake and preference were higher in female mice compared to males. Absence of nicotine led to withdrawal, and intermittent access resulted in an escalation in consumption and greater nicotine withdrawal than continuous exposure. Additionally, oral nicotine consumption increased nucleus accumbens tyrosine hydroxylase levels. While β2 and α6 KO mice showed a significant decrease in nicotine intake, deletion of α5 nAChRs increased nicotine consumption at high concentrations. Deletion of the α7 subunit altered the observed sex difference in nicotine consumption, with females consuming less than males. The α4β2 partial agonist varenicline decreased oral nicotine consumption. Although addition of quinine to the nicotine solution lowered nicotine intake, mice primed with nicotine did not lower their intake after quinine addition. Nicotine deprivation followed by re-exposure showed increased nicotine consumption, and DBA/2J mice consumed less nicotine compared to C57BL/6J. We validated the mouse 2BC paradigm to study nicotine's addictive-like properties including nicotine intake, preference, withdrawal, and escalation of nicotine consumption during binge drinking or after reinstatement of a deprivation period.
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Affiliation(s)
- Deniz Bagdas
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, 23298-0613, USA; The Center for the Study for Tobacco Products, Virginia Commonwealth University, Richmond, VA, 23298-0613, USA
| | - Clare M Diester
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, 23298-0613, USA
| | - Jason Riley
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, 23298-0613, USA
| | - Moriah Carper
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, 23298-0613, USA
| | - Yasmin Alkhlaif
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, 23298-0613, USA
| | - Dana AlOmari
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, 23298-0613, USA
| | - Hala Alayoubi
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, 23298-0613, USA
| | - Justin L Poklis
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, 23298-0613, USA
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, 23298-0613, USA; The Center for the Study for Tobacco Products, Virginia Commonwealth University, Richmond, VA, 23298-0613, USA.
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7
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Weera MM, Agim ZS, Cannon JR, Chester JA. Genetic correlations between nicotine reinforcement-related behaviors and propensity toward high or low alcohol preference in two replicate mouse lines. GENES, BRAIN, AND BEHAVIOR 2019; 18:e12515. [PMID: 30129253 PMCID: PMC6384161 DOI: 10.1111/gbb.12515] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 08/15/2018] [Accepted: 08/17/2018] [Indexed: 11/26/2022]
Abstract
Common genetic factors may contribute to the high comorbidity between tobacco smoking and alcohol use disorder. Here, we assessed behavioral and biological effects of nicotine in replicate mouse lines selectively bred for high (HAP2/3) or low alcohol preference (LAP2/3). In Experiment 1, free-choice (FC) oral nicotine and quinine intake were assessed in HAP2/3 and LAP2/3 mice. Effects of nicotinic acetylcholine receptor blockade by mecamylamine on nicotine intake in HAP2 mice were also examined. In Experiment 2, HAP2/3 and LAP2/3 mice were tested for differences in sensitivity to nicotine-induced taste conditioning. In Experiment 3, the effects of a single nicotine injection on nucleus accumbens (NAc) and dorsal striatum monoamine levels in HAP2/3 and LAP2/3 mice were tested. In Experiment 1, HAP2/3 mice showed greater nicotine intake and intake ratio than LAP2/3 mice. There were no line differences in quinine intake. Mecamylamine reduced nicotine intake and intake ratio in HAP2 mice. In Experiment 2, HAP2/3 mice showed weaker nicotine-induced conditioned taste aversion (CTA) compared with LAP2/3 mice. In Experiment 3, nicotine treatment increased NAc dopamine turnover across both HAP2/3 and LAP2/3 mouse lines. These results show that there is a positive genetic correlation between oral alcohol intake (high alcohol intake/preference selection phenotype) and oral nicotine intake and a negative genetic correlation between oral alcohol intake and sensitivity to nicotine-induced CTA.
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Affiliation(s)
- Marcus M. Weera
- Department of Psychology, Purdue University, West Lafayette, IN 47907
| | - Zeynep S. Agim
- School of Health Sciences, Purdue University, West Lafayette, IN 47907
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Jason R. Cannon
- School of Health Sciences, Purdue University, West Lafayette, IN 47907
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907
| | - Julia A. Chester
- Department of Psychology, Purdue University, West Lafayette, IN 47907
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8
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Kasten CR, Frazee AM, Boehm SL. Developing a model of limited-access nicotine consumption in C57Bl/6J mice. Pharmacol Biochem Behav 2016; 148:28-37. [PMID: 27242276 DOI: 10.1016/j.pbb.2016.05.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 05/26/2016] [Accepted: 05/26/2016] [Indexed: 01/31/2023]
Abstract
Although United States smoking rates have been on the decline over the past few decades, cigarette smoking still poses a critical health and economic threat. Very few treatment options for smoking exist, and many of them do not lead to long-term abstinence. Preclinical models are necessary for understanding the effects of nicotine and developing treatments. Current self-administration models of nicotine intake may require surgical procedures and often result in low levels of intake. Further, they do not lend themselves to investigating treatments. The current study sought to develop a limited-access model of nicotine intake using the Drinking-in-the-Dark paradigm, which results in high levels of binge-like ethanol consumption that can be pharmacologically manipulated. The present study found that mice will consume nicotine under a range of parameters. Intakes under the preferred condition of 0.14mg/ml nicotine in 0.2% saccharin reached over 6mg/kg in two hours and were reduced by an injection of R(+)-baclofen. Mecamylamine did not significantly affect nicotine consumption. As nicotine and ethanol are often co-abused, nicotine intake was also tested in the presence of ethanol. When presented in the same bottle, mice altered nicotine intake under various concentrations to maintain consistent levels of ethanol intake. When nicotine and ethanol were presented in separate bottles, mice greatly reduced their nicotine intake while maintaining ethanol intake. In conclusion, these studies characterize a novel model of limited-access nicotine intake that can be pharmacologically manipulated.
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Affiliation(s)
- C R Kasten
- Department of Psychology, Indianapolis University Purdue University - Indianapolis, 402 N Blackford St LD 124, Indianapolis, IN 46202, United States.
| | - A M Frazee
- Department of Psychology, Indianapolis University Purdue University - Indianapolis, 402 N Blackford St LD 124, Indianapolis, IN 46202, United States
| | - S L Boehm
- Department of Psychology, Indianapolis University Purdue University - Indianapolis, 402 N Blackford St LD 124, Indianapolis, IN 46202, United States; Indiana Alcohol Research Center, 545 Barnhill Drive EH 317, Indianapolis, IN, United States.
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Roebber JK, Izenwasser S, Chaudhari N. Cocaine decreases saccharin preference without altering sweet taste sensitivity. Pharmacol Biochem Behav 2015; 133:18-24. [PMID: 25812471 PMCID: PMC4430401 DOI: 10.1016/j.pbb.2015.03.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 03/10/2015] [Accepted: 03/16/2015] [Indexed: 10/23/2022]
Abstract
In rodents, saccharin consumption is suppressed when the sweet taste stimulus is paired with moderate doses of cocaine. Several hypotheses have been used to explain the seemingly contradictory effect of decreased consumption of a normally preferred substance following a highly rewarding drug. A common theme across these hypotheses is that saccharin is interpreted as less rewarding after cocaine pairing. We considered the alternative possibility that suppression is caused not by a change in reward circuitry, but rather by a change in taste detection, for instance by altering the afferent taste response and decreasing sensitivity to sweet taste stimuli. To evaluate this possibility, we measured saccharin taste sensitivity of mice before and after a standard cocaine-pairing paradigm. We measured taste sensitivity using a brief-access lickometer equipped with multiple concentrations of saccharin solution and established concentration-response curves before and after saccharin-cocaine pairing. Our results indicate that the EC50 for saccharin was unaltered following pairing. Instead, the avidity of licking saccharin, an indicator of motivation, was depressed. Latency to first-lick, a negative indicator of motivation, was also dramatically increased. Thus, our findings are consistent with the interpretation that saccharin-cocaine pairing results in devaluing of the sweet taste reward.
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Affiliation(s)
- Jennifer K Roebber
- Graduate Program in Neurosciences, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Sari Izenwasser
- Graduate Program in Neurosciences, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Nirupa Chaudhari
- Graduate Program in Neurosciences, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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10
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Nesil T, Kanit L, Pogun S. Bitter taste and nicotine preference: evidence for sex differences in rats. THE AMERICAN JOURNAL OF DRUG AND ALCOHOL ABUSE 2014; 41:57-67. [DOI: 10.3109/00952990.2014.990091] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Balsevich G, Poon A, Goldowitz D, Wilking JA. The effects of pre- and post-natal nicotine exposure and genetic background on the striatum and behavioral phenotypes in the mouse. Behav Brain Res 2014; 266:7-18. [PMID: 24607511 DOI: 10.1016/j.bbr.2014.02.038] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 02/07/2014] [Accepted: 02/25/2014] [Indexed: 02/03/2023]
Abstract
Maternal tobacco use increases the risk of complications in pregnancy and also the risk of adverse fetal outcomes. Studies have established nicotine as the principal component of tobacco smoke that leads to the majority of negative reproductive outcomes associated with maternal tobacco use. It appears the neuroteratogenicity of nicotine is mediated by complex gene-environment interactions. Genetic background contributes to individual differences in nicotine-related phenotypes. The aim of the current study was to investigate the interaction between pre- and post-natal nicotine exposure and genetic background on the histology of the striatum and behavioral measures using DBA/2J (D2) and C57BL/6J (B6) inbred mice. Alterations in neuronal cell populations, striatal brain volume, and behavior - open field (OF) activity, novel object recognition (NOR), elevated plus maze (EPM), and passive avoidance (PA) - were evaluated on post-natal day (PN) 24 and PN75. Histological data showed that pre- and post-natal nicotine exposure resulted in decreased striatal volume among preadolescent B6 and reduced neuronal number within the striatum of preadolescent B6 mice. Behavioral data showed that pre- and post-natal nicotine exposure promoted hyperactivity in D2 female mice and disrupted NOR and PA memory. Specifically, NOR deficits were significant amongst adult male mice whereas PA deficits were seen across genetic background and sex. These data suggest that nicotine treatment, genetic background, developmental stage, and sex effect striatal morphology can lead to neurobehavioral alterations.
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Affiliation(s)
- Georgia Balsevich
- Department of Neuroscience, University of British Columbia, 950 W. 28th Ave, Vancouver, BC, Canada V5Z 4H4; Centre for Molecular Medicine & Therapeutics, University of British Columbia, 950 W. 28th Ave, Vancouver, BC, Canada V5Z 4H4; Child and Family Research Institute, University of British Columbia, 950 W. 28th Ave, Vancouver, BC, Canada V5Z 4H4
| | - Anna Poon
- Department of Medical Genetics, University of British Columbia, 950 W. 28th Ave, Vancouver, BC, Canada V5Z 4H4; Centre for Molecular Medicine & Therapeutics, University of British Columbia, 950 W. 28th Ave, Vancouver, BC, Canada V5Z 4H4; Child and Family Research Institute, University of British Columbia, 950 W. 28th Ave, Vancouver, BC, Canada V5Z 4H4
| | - Dan Goldowitz
- Department of Medical Genetics, University of British Columbia, 950 W. 28th Ave, Vancouver, BC, Canada V5Z 4H4; Centre for Molecular Medicine & Therapeutics, University of British Columbia, 950 W. 28th Ave, Vancouver, BC, Canada V5Z 4H4; Child and Family Research Institute, University of British Columbia, 950 W. 28th Ave, Vancouver, BC, Canada V5Z 4H4
| | - Jennifer A Wilking
- Department of Medical Genetics, University of British Columbia, 950 W. 28th Ave, Vancouver, BC, Canada V5Z 4H4; Centre for Molecular Medicine & Therapeutics, University of British Columbia, 950 W. 28th Ave, Vancouver, BC, Canada V5Z 4H4; Child and Family Research Institute, University of British Columbia, 950 W. 28th Ave, Vancouver, BC, Canada V5Z 4H4.
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12
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Slimak MA, Ables JL, Frahm S, Antolin-Fontes B, Santos-Torres J, Moretti M, Gotti C, Ibañez-Tallon I. Habenular expression of rare missense variants of the β4 nicotinic receptor subunit alters nicotine consumption. Front Hum Neurosci 2014; 8:12. [PMID: 24478678 PMCID: PMC3902282 DOI: 10.3389/fnhum.2014.00012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 01/07/2014] [Indexed: 01/23/2023] Open
Abstract
The CHRNA5-CHRNA3-CHRNB4 gene cluster, encoding the α5, α3, and β4 nicotinic acetylcholine receptor (nAChR) subunits, has been linked to nicotine dependence. The habenulo-interpeduncular (Hb-IPN) tract is particularly enriched in α3β4 nAChRs. We recently showed that modulation of these receptors in the medial habenula (MHb) in mice altered nicotine consumption. Given that β4 is rate-limiting for receptor activity and that single nucleotide polymorphisms (SNPs) in CHRNB4 have been linked to altered risk of nicotine dependence in humans, we were interested in determining the contribution of allelic variants of β4 to nicotine receptor activity in the MHb. We screened for missense SNPs that had allele frequencies >0.0005 and introduced the corresponding substitutions in Chrnb4. Fourteen variants were analyzed by co-expression with α3. We found that β4A90I and β4T374I variants, previously shown to associate with reduced risk of smoking, and an additional variant β4D447Y, significantly increased nicotine-evoked current amplitudes, while β4R348C, the mutation most frequently encountered in sporadic amyotrophic lateral sclerosis (sALS), showed reduced nicotine currents. We employed lentiviruses to express β4 or β4 variants in the MHb. Immunoprecipitation studies confirmed that β4 lentiviral-mediated expression leads to specific upregulation of α3β4 but not β2 nAChRs in the Mhb. Mice injected with the β4-containing virus showed pronounced aversion to nicotine as previously observed in transgenic Tabac mice overexpressing Chrnb4 at endogenous sites including the MHb. Habenular expression of the β4 gain-of-function allele T374I also resulted in strong aversion, while transduction with the β4 loss-of function allele R348C failed to induce nicotine aversion. Altogether, these data confirm the critical role of habenular β4 in nicotine consumption, and identify specific SNPs in CHRNB4 that modify nicotine-elicited currents and alter nicotine consumption in mice.
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Affiliation(s)
- Marta A Slimak
- Molecular Neurobiology Group, Max Delbrück Center for Molecular Medicine Berlin, Germany
| | - Jessica L Ables
- Laboratory of Molecular Biology, The Rockefeller University New York, NY, USA
| | - Silke Frahm
- Molecular Neurobiology Group, Max Delbrück Center for Molecular Medicine Berlin, Germany
| | - Beatriz Antolin-Fontes
- Molecular Neurobiology Group, Max Delbrück Center for Molecular Medicine Berlin, Germany ; Laboratory of Molecular Biology, The Rockefeller University New York, NY, USA
| | - Julio Santos-Torres
- Molecular Neurobiology Group, Max Delbrück Center for Molecular Medicine Berlin, Germany
| | - Milena Moretti
- Consiglio Nazionale delle Ricerche Institute of Neuroscience and Biometra Department, University of Milan Milan, Italy
| | - Cecilia Gotti
- Consiglio Nazionale delle Ricerche Institute of Neuroscience and Biometra Department, University of Milan Milan, Italy
| | - Inés Ibañez-Tallon
- Molecular Neurobiology Group, Max Delbrück Center for Molecular Medicine Berlin, Germany ; Laboratory of Molecular Biology, The Rockefeller University New York, NY, USA
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13
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Yoo JH, Kitchen I, Bailey A. The endogenous opioid system in cocaine addiction: what lessons have opioid peptide and receptor knockout mice taught us? Br J Pharmacol 2012; 166:1993-2014. [PMID: 22428846 DOI: 10.1111/j.1476-5381.2012.01952.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Cocaine addiction has become a major concern in the UK as Britain tops the European 'league table' for cocaine abuse. Despite its devastating health and socio-economic consequences, no effective pharmacotherapy for treating cocaine addiction is available. Identifying neurochemical changes induced by repeated drug exposure is critical not only for understanding the transition from recreational drug use towards compulsive drug abuse but also for the development of novel targets for the treatment of the disease and especially for relapse prevention. This article focuses on the effects of chronic cocaine exposure and withdrawal on each of the endogenous opioid peptides and receptors in rodent models. In addition, we review the studies that utilized opioid peptide or receptor knockout mice in order to identify and/or clarify the role of different components of the opioid system in cocaine-addictive behaviours and in cocaine-induced alterations of brain neurochemistry. The review of these studies indicates a region-specific activation of the µ-opioid receptor system following chronic cocaine exposure, which may contribute towards the rewarding effect of the drug and possibly towards cocaine craving during withdrawal followed by relapse. Cocaine also causes a region-specific activation of the κ-opioid receptor/dynorphin system, which may antagonize the rewarding effect of the drug, and at the same time, contribute to the stress-inducing properties of the drug and the triggering of relapse. These conclusions have important implications for the development of effective pharmacotherapy for the treatment of cocaine addiction and the prevention of relapse.
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Affiliation(s)
- Ji Hoon Yoo
- Division of Biochemistry, Faculty of Health & Medical Sciences, University of Surrey, Guildford, Surrey, UK
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14
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Gyekis JP, Dingman MA, Revitsky AR, Bryant BP, Vandenbergh DJ, Frank ME, Blizard DA. Gustatory, trigeminal, and olfactory aspects of nicotine intake in three mouse strains. Behav Genet 2012; 42:820-9. [PMID: 22618163 DOI: 10.1007/s10519-012-9546-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 05/05/2012] [Indexed: 12/16/2022]
Abstract
Studies of nicotine consumption in rodents often intend to investigate nicotine's post-absorptive effects, yet little is known about the pre-absorptive sensory experience of nicotine drinking, including gustatory, trigeminal, and olfactory influences. We conditioned taste aversion (CTA) to nicotine in males of 3 inbred mouse strains: C57BL/6J, DBA/2J, and 129X1/SvJ by repeatedly pairing 150 μg/ml nicotine drinking with lithium chloride injections. Generalization to a variety of bitter, sour, sweet, salty, and irritant solutions and to nicotine odor was then examined. Nicotine CTA generalized to the bitter stimulus quinine hydrochloride and the chemosensory irritant spilanthol in all strains. It also showed strain specificity, generalizing to hydrogen peroxide (an activator of TRPA1) in C57BL/6J mice and to the olfactory cue of nicotine in DBA/2J mice. These behavioral assays demonstrate that the sensory properties of nicotine are complex and include multiple gustatory, irritant, and olfactory components. How these qualities combine at the level of perception remains to be assessed, but sensory factors clearly exert an important influence on nicotine ingestion and their contribution to net intake of nicotine should not be neglected in animal or human studies.
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Affiliation(s)
- Joseph P Gyekis
- Department of Biobehavioral Health, Pennsylvania State University, 201 Research Building D, University Park, PA 16802, USA
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15
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Locklear LL, McDonald CG, Smith RF, Fryxell KJ. Adult mice voluntarily progress to nicotine dependence in an oral self-selection assay. Neuropharmacology 2012; 63:582-92. [PMID: 22583831 DOI: 10.1016/j.neuropharm.2012.04.037] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2011] [Revised: 04/11/2012] [Accepted: 04/28/2012] [Indexed: 12/12/2022]
Abstract
Nicotine has both rewarding and aversive properties in rodents, as shown by intravenous self-administration, intracranial self-stimulation, and conditioned place preference experiments. However, high throughput models of nicotine reward have not been developed in mice. In previous two-bottle studies, mice often chose to drink less from the nicotine bottle than from the water bottle, which raises the question whether these paradigms provide a model of the reinforcing properties of oral nicotine. We hypothesized that previous two-bottle choice paradigms included factors (such as the brief duration of trials, the addition of flavorings to both bottles, water bottles located relatively close to each other, etc.) that may have obstructed the formation of a learned association between the taste of nicotine and its delayed pharmacological effects. Here we show that a paradigm designed to simplify the acquisition of a learned association resulted in nicotine consumption by various strains and sexes that diverged progressively over a period of seven weeks. The strain and sex with the highest nicotine consumption (C57BL/6J females) showed steady and statistically significant increases in nicotine consumption throughout this period. C57BL/6J females were clearly responding to the reinforcing properties of nicotine because they chose to drink over 70% of their fluids from the nicotine bottle. Moreover, they became nicotine dependent, as shown by highly significant nicotine withdrawal symptoms after the nicotine bottle was removed. The strain and sex with the lowest consumption (A/J males) showed a significant decrease in nicotine consumption, and by the end of the experiment were drinking only 24% of their fluids from the nicotine bottle.
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Affiliation(s)
- Laura L Locklear
- School of Systems Biology, George Mason University, Manassas, VA, USA
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16
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Hall FS, Markou A, Levin ED, Uhl GR. Mouse models for studying genetic influences on factors determining smoking cessation success in humans. Ann N Y Acad Sci 2012; 1248:39-70. [PMID: 22304675 DOI: 10.1111/j.1749-6632.2011.06415.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Humans differ in their ability to quit using addictive substances, including nicotine, the major psychoactive ingredient in tobacco. For tobacco smoking, a substantial body of evidence, largely derived from twin studies, indicates that approximately half of these individual differences in ability to quit are heritable genetic influences that likely overlap with those for other addictive substances. Both twin and molecular genetic studies support overlapping influences on nicotine addiction vulnerability and smoking cessation success, although there is little formal analysis of the twin data that support this important point. None of the current datasets provides clarity concerning which heritable factors might provide robust dimensions around which individuals differ in ability to quit smoking. One approach to this problem is to test mice with genetic variations in genes that contain human variants that alter quit success. This review considers which features of quit success should be included in a comprehensive approach to elucidate the genetics of quit success, and how those features may be modeled in mice.
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Affiliation(s)
- F Scott Hall
- Molecular Neurobiology Branch, NIH-IRP, NIDA, Baltimore, Maryland 21224, USA
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17
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Abstract
Nicotine addiction is a complex process that begins with self-administration. Consequently, this process has been studied extensively using animal models. A person is usually not called "smoker" if s/he has smoked for a week or a month in a lifetime; in general, a smoker has been smoking for many years. Furthermore, a smoker has free access to cigarettes and can smoke whenever she/he wants, provided there are no social/legal restraints. Subsequently, in an animal model of tobacco addiction, it will be desirable to expose the animal to free access nicotine for 24 hours/day for many weeks, starting at different stages of development.
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Affiliation(s)
- Allan C Collins
- Institute for Behavioral Genetics, University of Colorado, Boulder, Colorado, USA
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18
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Frahm S, Slimak MA, Ferrarese L, Santos-Torres J, Antolin-Fontes B, Auer S, Filkin S, Pons S, Fontaine JF, Tsetlin V, Maskos U, Ibañez-Tallon I. Aversion to nicotine is regulated by the balanced activity of β4 and α5 nicotinic receptor subunits in the medial habenula. Neuron 2011; 70:522-35. [PMID: 21555077 DOI: 10.1016/j.neuron.2011.04.013] [Citation(s) in RCA: 230] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/08/2011] [Indexed: 12/19/2022]
Abstract
Nicotine dependence is linked to single nucleotide polymorphisms in the CHRNB4-CHRNA3-CHRNA5 gene cluster encoding the α3β4α5 nicotinic acetylcholine receptor (nAChR). Here we show that the β4 subunit is rate limiting for receptor activity, and that current increase by β4 is maximally competed by one of the most frequent variants associated with tobacco usage (D398N in α5). We identify a β4-specific residue (S435), mapping to the intracellular vestibule of the α3β4α5 receptor in close proximity to α5 D398N, that is essential for its ability to increase currents. Transgenic mice with targeted overexpression of Chrnb4 to endogenous sites display a strong aversion to nicotine that can be reversed by viral-mediated expression of the α5 D398N variant in the medial habenula (MHb). Thus, this study both provides insights into α3β4α5 receptor-mediated mechanisms contributing to nicotine consumption, and identifies the MHb as a critical element in the circuitry controlling nicotine-dependent phenotypes.
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Affiliation(s)
- Silke Frahm
- Molecular Neurobiology Group, Max-Delbrück-Centrum, Berlin, Germany
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19
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Fowler CD, Kenny PJ. Intravenous nicotine self-administration and cue-induced reinstatement in mice: effects of nicotine dose, rate of drug infusion and prior instrumental training. Neuropharmacology 2011; 61:687-98. [PMID: 21640128 DOI: 10.1016/j.neuropharm.2011.05.012] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 05/11/2011] [Accepted: 05/15/2011] [Indexed: 01/08/2023]
Abstract
Intravenous nicotine self-administration is the most direct measure of nicotine reinforcement in laboratory animals, but this procedure has proven difficult to establish in mice. We found that stable responding for nicotine in C57BL6/J mice was facilitated by prior instrumental training for food reward, initial exposure of mice to a lower unit dose of nicotine (0.03 mg kg(-1) per infusion) before access to higher doses, a slower rate of drug delivery (3-s versus 1-s infusion), consistency in schedule of daily testing, and low extraneous noise during testing. Under these conditions, we found that mice lever-pressed for nicotine (0.03-0.4 mg kg(-1) per infusion; 60-min test sessions) under a fixed-ratio 5 time-out 20-s (FR5TO20) reinforcement schedule and consumed the drug according to an inverted 'U'-shaped dose-response curve. Mice switched their responding onto a previously non-reinforced lever to continue earning nicotine infusions when the active/inactive lever assignment was reversed. The nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine decreased responding for nicotine, but not food rewards, verifying that nAChRs regulate nicotine self-administration in mice. The cue-light paired with nicotine delivery did not support responding when delivered independently of nicotine infusions, further verifying that mice responded selectivity for the drug. Nicotine-seeking responses extinguished when nicotine infusions and the cue-light were withheld, and exposure to the cue-light reinstated responding. Finally, mice without prior instrumental food training acquired stable responding for nicotine under the FR5TO20 schedule, but required a greater number of sessions. These data demonstrate that nicotine is an effective reinforcer in mice and establish conditions under which the drug is reliably self-administered by mice.
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Affiliation(s)
- Christie D Fowler
- Department of Molecular Therapeutics, The Scripps Research Institute-Scripps Florida, Jupiter, FL 33458, USA
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20
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Nesil T, Kanit L, Collins AC, Pogun S. Individual differences in oral nicotine intake in rats. Neuropharmacology 2011; 61:189-201. [PMID: 21504750 DOI: 10.1016/j.neuropharm.2011.03.027] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 03/25/2011] [Accepted: 03/30/2011] [Indexed: 12/23/2022]
Abstract
To study individual differences in nicotine preference and intake, male and female rats were given free access to a choice of oral nicotine (10 or 20 mg/L) or water for 24 h/day for periods of at least six weeks, starting at adolescence or adulthood. A total of 341 rats, were used in four different experiments; weight, nicotine intake and total liquid consumption were recorded weekly. Results show that rats can discriminate nicotine from water, can regulate their intake, and that there are readily detected individual differences in nicotine preference. Ward analyses indicated that the animals could be divided into minimum, median and maximum preferring subgroups in all experiments. The effect of saccharine on nicotine intake was also evaluated; although the addition of saccharine increased total intake, rats drank unsweetened nicotine solutions and those with higher preferences for nicotine, preferred nicotine over water with or without saccharine added. Nicotine reduced weight gain and the effect was more pronounced in females than males. The average nicotine consumption of adolescent rats was higher than adults and nicotine exposure during adolescence reduced nicotine intake in adult rats. About half of the rats which had access to nicotine as adolescents and also as adults had a persistent pattern of consumption; the behavior was very stable in the female minimum preferring groups and a much higher ratio of rats sustained their adolescent behavior as adults. The change in preference was more pronounced when there was an interval between adolescent and adult exposure; female rats showed a more stable behavior than males suggesting a greater role for environmental influences on males. In conclusion, marked individual differences were observed in oral nicotine intake as measured in a continuous access 2-bottle choice test. Age and sex of the subjects and previous exposure to nicotine are significant factors which affect preference in rats.
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Affiliation(s)
- Tanseli Nesil
- Center for Brain Research, Ege University, Bornova, 35100 Izmir, Turkey; Institute of Sciences, Biotechnology Dept., Ege University, Bornova, Izmir, Turkey
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21
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Bailey A, Metaxas A, Al-Hasani R, Keyworth HL, Forster DM, Kitchen I. Mouse strain differences in locomotor, sensitisation and rewarding effect of heroin; association with alterations in MOP-r activation and dopamine transporter binding. Eur J Neurosci 2010; 31:742-53. [PMID: 20384817 DOI: 10.1111/j.1460-9568.2010.07104.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
There is growing agreement that genetic factors play an important role in the risk to develop heroin addiction, and comparisons of heroin addiction vulnerability in inbred strains of mice could provide useful information on the question of individual vulnerability to heroin addiction. This study examined the rewarding and locomotor-stimulating effects of heroin in male C57BL/6J and DBA/2J mice. Heroin induced locomotion and sensitisation in C57BL/6J but not in DBA/2J mice. C57BL/6J mice developed conditioned place preference (CPP) to the highest doses of heroin, while DBA/2J showed CPP to only the lowest heroin doses, indicating a higher sensitivity of DBA/2J mice to the rewarding properties of heroin vs C57BL/6J mice. In order to investigate the neurobiological substrate underlying some of these differences, the effect of chronic 'intermittent' escalating dose heroin administration on the opioid, dopaminergic and stress systems was explored. Twofold higher mu-opioid receptor (MOP-r)-stimulated [35S]GTPgammaS binding was observed in the nucleus accumbens and caudate of saline-treated C57BL/6J mice compared with DBA/2J. Heroin decreased MOP-r density in brain regions of C57BL/6J mice, but not in DBA/2J. A higher density of dopamine transporters (DAT) was observed in nucleus accumbens shell and caudate of heroin-treated DBA/2J mice compared with heroin-treated C57BL/6J. There were no effects on D1 and D2 binding. Chronic heroin administration decreased corticosterone levels in both strains with no effect of strain. These results suggest that genetic differences in MOP-r activation and DAT expression may be responsible for individual differences in vulnerability to heroin addiction.
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Affiliation(s)
- Alexis Bailey
- Faculty of Health and Medical Sciences, AY Building, University of Surrey, Guildford, Surrey GU2 7XH, UK.
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22
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Forebrain PENK and PDYN gene expression levels in three inbred strains of mice and their relationship to genotype-dependent morphine reward sensitivity. Psychopharmacology (Berl) 2010; 208:291-300. [PMID: 19997907 DOI: 10.1007/s00213-009-1730-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Accepted: 11/10/2009] [Indexed: 12/18/2022]
Abstract
RATIONALE Vulnerability to drug abuse disorders is determined not only by environmental but also by genetic factors. A body of evidence suggests that endogenous opioid peptide systems may influence rewarding effects of addictive substances, and thus, their individual expression levels may contribute to drug abuse liability. OBJECTIVES The aim of our study was to assess whether basal genotype-dependent brain expression of opioid propeptides genes can influence sensitivity to morphine reward. METHODS Experiments were performed on inbred mouse strains C57BL/6J, DBA/2J, and SWR/J, which differ markedly in responses to morphine administration: DBA/2J and SWR/J show low and C57BL/6J high sensitivity to opioid reward. Proenkephalin (PENK) and prodynorphin (PDYN) gene expression was measured by in situ hybridization in brain regions implicated in addiction. The influence of the kappa opioid receptor antagonist nor-binaltorphimine (nor-BNI), which attenuates effects of endogenous PDYN-derived peptides, on rewarding actions of morphine was studied using the conditioned place preference (CPP) paradigm. RESULTS DBA/2J and SWR/J mice showed higher levels of PDYN and lower levels of PENK messenger RNA in the nucleus accumbens than the C57BL/6J strain. Pretreatment with nor-BNI enhanced morphine-induced CPP in the opioid-insensitive DBA/2J and SWR/J strains. CONCLUSIONS Our results demonstrate that inter-strain differences in PENK and PDYN genes expression in the nucleus accumbens parallel sensitivity of the selected mouse strains to rewarding effects of morphine. They suggest that high expression of PDYN may protect against drug abuse by limiting drug-produced reward, which may be due to dynorphin-mediated modulation of dopamine release in the nucleus accumbens.
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