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Chan D, Baker KD, Richardson R. The impact of chronic fluoxetine treatment in adolescence or adulthood on context fear memory and perineuronal nets. Dev Psychobiol 2024; 66:e22501. [PMID: 38807259 DOI: 10.1002/dev.22501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 04/19/2024] [Accepted: 05/03/2024] [Indexed: 05/30/2024]
Abstract
Selective serotonin reuptake inhibitors, such as fluoxetine (Prozac), are commonly prescribed pharmacotherapies for anxiety. Fluoxetine may be a useful adjunct because it can reduce the expression of learned fear in adult rodents. This effect is associated with altered expression of perineuronal nets (PNNs) in the amygdala and hippocampus, two brain regions that regulate fear. However, it is unknown whether fluoxetine has similar effects in adolescents. Here, we investigated the effect of fluoxetine exposure during adolescence or adulthood on context fear memory and PNNs in the basolateral amygdala (BLA), the CA1 subregion of the hippocampus, and the medial prefrontal cortex in rats. Fluoxetine impaired context fear memory in adults but not in adolescents. Further, fluoxetine increased the number of parvalbumin (PV)-expressing neurons surrounded by a PNN in the BLA and CA1, but not in the medial prefrontal cortex, at both ages. Contrary to previous reports, fluoxetine did not shift the percentage of PNNs toward non-PV cells in either the BLA or CA1 in the adults, or adolescents. These findings demonstrate that fluoxetine differentially affects fear memory in adolescent and adult rats but does not appear to have age-specific effects on PNNs.
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Affiliation(s)
- Diana Chan
- School of Psychology, UNSW Sydney, Sydney, New South Wales, Australia
| | - Kathryn D Baker
- School of Psychology, UNSW Sydney, Sydney, New South Wales, Australia
| | - Rick Richardson
- School of Psychology, UNSW Sydney, Sydney, New South Wales, Australia
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2
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Premachandran H, Wilkin J, Arruda-Carvalho M. Minimizing Variability in Developmental Fear Studies in Mice: Toward Improved Replicability in the Field. Curr Protoc 2024; 4:e1040. [PMID: 38713136 DOI: 10.1002/cpz1.1040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
In rodents, the first weeks of postnatal life feature remarkable changes in fear memory acquisition, retention, extinction, and discrimination. Early development is also marked by profound changes in brain circuits underlying fear memory processing, with heightened sensitivity to environmental influences and stress, providing a powerful model to study the intersection between brain structure, function, and the impacts of stress. Nevertheless, difficulties related to breeding and housing young rodents, preweaning manipulations, and potential increased variability within that population pose considerable challenges to developmental fear research. Here we discuss several factors that may promote variability in studies examining fear conditioning in young rodents and provide recommendations to increase replicability. We focus primarily on experimental conditions, design, and analysis of rodent fear data, with an emphasis on mouse studies. The convergence of anatomical, synaptic, physiological, and behavioral changes during early life may increase variability, but careful practice and transparency in reporting may improve rigor and consensus in the field. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC.
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Affiliation(s)
- Hanista Premachandran
- Department of Psychology, University of Toronto Scarborough, Toronto, Ontario, Canada
- These authors contributed equally to this work
| | - Jennifer Wilkin
- Department of Psychology, University of Toronto Scarborough, Toronto, Ontario, Canada
- These authors contributed equally to this work
| | - Maithe Arruda-Carvalho
- Department of Psychology, University of Toronto Scarborough, Toronto, Ontario, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
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Colyer-Patel K, Kuhns L, Weidema A, Lesscher H, Cousijn J. Age-dependent effects of tobacco smoke and nicotine on cognition and the brain: A systematic review of the human and animal literature comparing adolescents and adults. Neurosci Biobehav Rev 2023; 146:105038. [PMID: 36627063 DOI: 10.1016/j.neubiorev.2023.105038] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 10/21/2022] [Accepted: 01/05/2023] [Indexed: 01/09/2023]
Abstract
Cigarette smoking is often initiated during adolescence and an earlier age of onset is associated with worse health outcomes later in life. Paradoxically, the transition towards adulthood also marks the potential for recovery, as the majority of adolescents are able to quit smoking when adulthood emerges. This systematic review aimed to evaluate the evidence from both human and animal studies for the differential impact of adolescent versus adult repeated and long-term tobacco and nicotine exposure on cognitive and brain outcomes. The limited human studies and more extensive yet heterogeneous animal studies, provide preliminary evidence of heightened fear learning, anxiety-related behaviour, reward processing, nicotinic acetylcholinergic receptors expression, dopamine expression and serotonin functioning after adolescent compared to adult exposure. Effects of nicotine or tobacco use on impulsivity were comparable across age groups. These findings provide novel insights into the mechanisms underlying adolescents' vulnerability to tobacco and nicotine. Future research is needed to translate animal to human findings, with a focus on directly linking a broader spectrum of brain and behavioural outcomes.
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Affiliation(s)
- Karis Colyer-Patel
- Neuroscience of Addiction (NofA) Lab, Department of Psychology, Education & Child Studies, Erasmus University Rotterdam, the Netherlands.
| | - Lauren Kuhns
- Department of Psychology, University of Amsterdam, Amsterdam, the Netherlands
| | - Alix Weidema
- Neuroscience of Addiction (NofA) Lab, Department of Psychology, Education & Child Studies, Erasmus University Rotterdam, the Netherlands
| | - Heidi Lesscher
- Department Population Health Sciences, Animals in Science and Society, Division of Behavioural Neuroscience, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Janna Cousijn
- Neuroscience of Addiction (NofA) Lab, Department of Psychology, Education & Child Studies, Erasmus University Rotterdam, the Netherlands; Department of Psychology, University of Amsterdam, Amsterdam, the Netherlands
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Seemiller LR, Goldberg LR, Garcia-Trevizo P, Gould TJ. Interstrain differences in adolescent fear conditioning after acute alcohol exposure. Brain Res Bull 2023; 194:35-44. [PMID: 36681252 PMCID: PMC10921434 DOI: 10.1016/j.brainresbull.2023.01.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 01/03/2023] [Accepted: 01/17/2023] [Indexed: 01/20/2023]
Abstract
Adolescent sensitivity to alcohol is a predictor of continued alcohol use and misuse later in life. Thus, it is important to understand the many factors that can impact alcohol sensitivity. Data from our laboratory suggested that susceptibility to alcohol-associated contextual fear learning deficits varied among adolescent and adult mice from two mouse strains. To investigate the extent of genetic background's influences on adolescent learning after alcohol exposure, we examined how 9 inbred mouse strains differed in vulnerability to alcohol-induced contextual and cued fear conditioning deficits. We demonstrated significant strain- and sex-dependent effects of acute alcohol exposure on adolescent fear learning, with alcohol having most pronounced effects on contextual fear learning. Female adolescents were more susceptible than males to alcohol-induced impairments in contextual, but not cued, fear learning, independent of genetic background. Heritability for contextual and cued fear learning after alcohol exposure was estimated to be 31 % and 18 %, respectively. Learning data were compared to Blood Ethanol Concentrations (BEC) to assess whether strain differences in alcohol metabolism contributed to strain differences in learning after alcohol exposure. There were no clear relationships between BEC and learning outcomes, suggesting that strains differed in learning outcomes for reasons other than strain differences in alcohol metabolism. Genetic analyses revealed polymorphisms across strains in notable genes, such as Chrna7, a promising genetic candidate for susceptibility to alcohol-induced fear conditioning deficits. These results are the first to demonstrate the impact of genetic background on alcohol-associated fear learning deficits during adolescence and suggest that the mechanisms underlying this sensitivity are distinct from alcohol metabolism.
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Affiliation(s)
- Laurel R Seemiller
- Department of Biobehavioral Health, Penn State University, University Park, PA, USA
| | - Lisa R Goldberg
- 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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5
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Unique effects of nicotine across the lifespan. Pharmacol Biochem Behav 2022; 214:173343. [PMID: 35122768 DOI: 10.1016/j.pbb.2022.173343] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 01/27/2022] [Accepted: 01/28/2022] [Indexed: 12/23/2022]
Abstract
Smoking remains the leading cause of preventable death in the United States. Although combustible cigarettes are largely being replaced by tobacco-free products, nicotine use continues to increase in vulnerable populations, including youth, adolescents, and pregnant women. Nicotine exerts unique effects on specific brain regions during distinct developmental periods due to the dynamic expression of nicotinic acetylcholine receptors (nAChRs) throughout the lifespan. Nicotine exposure is a health concern not only for adults but also has neurotoxic effects on the fetus, newborn, child, and adolescent. In this review, we aim to highlight the dynamic roles of nAChRs throughout gestation, adolescence, and adulthood. We also provide clinical and preclinical evidence of the neurodevelopmental, cognitive, and behavioral consequences of nicotine exposure at different developmental periods. This comprehensive review highlights unique effects of nicotine throughout the lifespan to help elucidate interventions and public health measures to protect sensitive populations from nicotine exposure.
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Bisby MA, Stylianakis AA, Baker KD, Richardson R. Fear extinction learning and retention during adolescence in rats and mice: A systematic review. Neurosci Biobehav Rev 2021; 131:1264-1274. [PMID: 34740753 DOI: 10.1016/j.neubiorev.2021.10.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 10/20/2021] [Accepted: 10/29/2021] [Indexed: 10/19/2022]
Abstract
Despite exposure-based treatments being recommended for anxiety disorders, these treatments are ineffective for over half of all adolescents who receive them. The limited efficacy of exposure during adolescence may be driven by a deficit in extinction. Although indications of diminished extinction learning during adolescence were first reported over 10 years ago, these findings have yet to be reviewed and compared. This review (k = 34) found a stark inter-species difference in extinction performance: studies of adolescent mice reported deficits in extinction learning and retention of both cued and context fear. In contrast, studies of adolescent rats only reported poor extinction retention specific to cued fear. Adolescent mice and rats appeared to have only one behavioral outcome in common, being poor extinction retention of cued fear. These findings suggest that different behavioral phenotypes are present across rodent species in adolescence and highlight that preclinical work in rats and mice is not interchangeable. Further investigation of these differences offers the opportunity to better understand the etiology, maintenance, and treatment of fear-based disorders.
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Affiliation(s)
- Madelyne A Bisby
- School of Psychology, UNSW Sydney, Sydney, 2052, NSW, Australia; eCentreClinic, School of Psychological Sciences, Faculty of Medicine and Health, Macquarie University, Sydney, 2109, NSW, Australia.
| | | | - Kathryn D Baker
- School of Psychology, UNSW Sydney, Sydney, 2052, NSW, Australia
| | - Rick Richardson
- School of Psychology, UNSW Sydney, Sydney, 2052, NSW, Australia
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Seemiller LR, Gould TJ. Adult and adolescent C57BL/6J and DBA/2J mice are differentially susceptible to fear learning deficits after acute ethanol or MK-801 treatment. Behav Brain Res 2021; 410:113351. [PMID: 33974921 PMCID: PMC8403488 DOI: 10.1016/j.bbr.2021.113351] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 04/19/2021] [Accepted: 05/06/2021] [Indexed: 12/31/2022]
Abstract
Ethanol and other drugs of abuse disrupt learning and memory processes, creating problems associated with drug use and addiction. Understanding individual factors that determine susceptibility to drug-induced cognitive deficits, such as genetic background, age, and sex, is important for prevention and treatment. Comparison of adolescent and adult mice of both sexes across inbred mouse strains can reveal age, sex, and genetic contributions to phenotypes. We treated adolescent and adult, male and female, C57BL/6J and DBA/2J inbred mice with ethanol (1 g/kg or 1.5 g/kg) or MK-801 (0.05 mg/kg or 0.1 mg/kg), an NMDA receptor antagonist, prior to fear conditioning training. Contextual and cued fear retention were tested one day and eight or nine days after training. After ethanol exposure, adult C57BL/6J mice experienced greater deficits in contextual learning than adult DBA/2J mice. C57BL/6 J adolescents were less susceptible to ethanol-induced contextual learning disruptions than C57BL/6J adults, and adolescent males of both strains exhibited greater ethanol-induced contextual learning deficits than adolescent females. After MK-801 exposure, adolescent C57BL/6J mice experienced more severe contextual learning deficits than adolescent DBA/2J mice. Both ethanol and MK-801 had greater effects on contextual learning than cued learning. Collectively, we demonstrate that genetic background contributes to contextual and cued learning outcomes after ethanol or MK-801 exposure. Further, we report age-dependent drug sensitivities that are strain-, sex-, and drug-specific, suggesting that age, sex, and genetic background interact to determine contextual and cued learning impairments after ethanol or MK-801 exposure.
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Affiliation(s)
- L R Seemiller
- Department of Biobehavioral Health, Penn State University, 219 Biobehavioral Health Building, University Park, PA, 16801, United States
| | - T J Gould
- Department of Biobehavioral Health, Penn State University, 219 Biobehavioral Health Building, University Park, PA, 16801, United States.
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Goldberg LR, Zeid D, Kutlu MG, Cole RD, Lallai V, Sebastian A, Albert I, Fowler CD, Parikh V, Gould TJ. Paternal nicotine enhances fear memory, reduces nicotine administration, and alters hippocampal genetic and neural function in offspring. Addict Biol 2021; 26:e12859. [PMID: 31782218 DOI: 10.1111/adb.12859] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 10/07/2019] [Accepted: 11/07/2019] [Indexed: 12/22/2022]
Abstract
Nicotine use remains highly prevalent with tobacco and e-cigarette products consumed worldwide. However, increasing evidence of transgenerational epigenetic inheritance suggests that nicotine use may alter behavior and neurobiology in subsequent generations. We tested the effects of chronic paternal nicotine exposure in C57BL6/J mice on fear conditioning in F1 and F2 offspring, as well as conditioned fear extinction and spontaneous recovery, nicotine self-administration, hippocampal cholinergic functioning, RNA expression, and DNA methylation in F1 offspring. Paternal nicotine exposure was associated with enhanced contextual and cued fear conditioning and spontaneous recovery of extinguished fear memories. Further, nicotine reinforcement was reduced in nicotine-sired mice, as assessed in a self-administration paradigm. These behavioral phenotypes were coupled with altered response to nicotine, upregulated hippocampal nicotinic acetylcholine receptor binding, reduced evoked hippocampal cholinergic currents, and altered methylation and expression of hippocampal genes related to neural development and plasticity. Gene expression analysis suggests multigenerational effects on broader gene networks potentially involved in neuroplasticity and mental disorders. The changes in fear conditioning similarly suggest phenotypes analogous to anxiety disorders similar to post-traumatic stress.
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Affiliation(s)
- Lisa R. Goldberg
- Department of Biobehavioral Health Penn State University University Park Pennsylvania
| | - Dana Zeid
- Department of Biobehavioral Health Penn State University University Park Pennsylvania
| | - Munir Gunes Kutlu
- Department of Pharmacology Vanderbilt School of Medicine Nashville Tennessee
| | - Robert D. Cole
- College of Pharmacy University of Kentucky Lexington Kentucky
| | - Valeria Lallai
- Department of Neurobiology and Behavior University of California Irvine Irvine California
| | - Aswathy Sebastian
- Bioinformatics, Biochemistry and Molecular Biology Penn State University University Park PA
| | - Istvan Albert
- Bioinformatics, Biochemistry and Molecular Biology Penn State University University Park PA
| | - Christie D. Fowler
- Department of Neurobiology and Behavior University of California Irvine Irvine California
| | - Vinay Parikh
- Department of Psychology Temple University Philadelphia Pennsylvania
| | - Thomas J. Gould
- Department of Biobehavioral Health Penn State University University Park Pennsylvania
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Kutlu MG, Connor DA, Tumolo JM, Cann C, Garrett B, Gould TJ. Nicotine modulates contextual fear extinction through changes in ventral hippocampal GABAergic function. Neuropharmacology 2018; 141:192-200. [PMID: 30170085 DOI: 10.1016/j.neuropharm.2018.08.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 07/31/2018] [Accepted: 08/19/2018] [Indexed: 01/12/2023]
Abstract
Numerous studies have attributed the psychopathology of anxiety and stress disorders to maladaptive behavioral responses such as an inability to extinguish fear. Therefore, understanding neural substrates of fear extinction is imperative for developing more effective therapies for anxiety and stress disorders. Although several studies indicated a role for cholinergic transmission and nicotinic acetylcholine receptors (nAChRs) in anxiety and stress disorder symptomatology, very little is known about the specific contribution of nAChRs in the fear extinction process. In the present study, we first examined the involvement of several brain regions essential for fear extinction (i.e., dorsal and ventral hippocampus, dHPC and vHPC; infralimbic, IL, and prelimbic, PL of the medial prefrontal cortex, mPFC; basolateral nucleus of the amygdala, BLA) in the impairing effects of a nAChR agonist, nicotine, on contextual fear extinction in mice. Our results showed that systemic administration of nicotine during contextual fear extinction increased c-fos expression in the vHPC and BLA while not affecting dHPC, IL or PL. In line with these results, local nicotine infusions into the vHPC, but not dHPC, resulted in impaired contextual fear extinction. Interestingly, we found that local nicotine infusions into the PL also resulted in impairment of contextual fear extinction. Second, we measured the protein levels of the GABA synthesizing enzymes GAD65 and GAD67 in the dHPC and vHPC during contextual fear extinction. Our results showed that in the group that received acute nicotine, both GAD65 and GAD67 protein levels were downregulated in the vHPC, but not in dHPC. This effect was negatively correlated with the level of freezing response during fear extinction suggesting that the downregulated GAD65/67 levels were associated with disrupted fear extinction. Finally, using c-fos/GAD65/67 double immunofluorescence, we showed that nicotine mainly increased c-fos expression in non-GABAergic ventral hippocampal cells, indicating that acute nicotine increases vHPC excitability. Overall, our results suggest that acute nicotine's impairing effects on fear extinction are associated with ventral hippocampal disinhibition. Therefore, these results further our understanding of the interaction between nicotine addiction and anxiety and stress disorders by describing novel neural mechanisms mediating fear extinction.
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Affiliation(s)
- Munir Gunes Kutlu
- The Department of Biobehavioral Health, Pennsylvania State University, University Park, PA, USA.
| | - David A Connor
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania Medical School, Philadelphia, PA, USA
| | - Jessica M Tumolo
- Department of Psychology, Temple University, Philadelphia, PA, USA
| | - Courtney Cann
- The Department of Biobehavioral Health, Pennsylvania State University, University Park, PA, USA
| | - Brendan Garrett
- Department of Psychology, Temple University, Philadelphia, PA, USA
| | - Thomas J Gould
- The Department of Biobehavioral Health, Pennsylvania State University, University Park, PA, USA
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Zeid D, Gould TJ. Chronic nicotine exposure in preadolescence enhances later spontaneous recovery of fear memory. Behav Neurosci 2018; 132:240-246. [PMID: 29975080 DOI: 10.1037/bne0000247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Preadolescent mice have been shown to be differentially susceptible to the effects of both acute and chronic nicotine exposure on contextual fear learning relative to adults. For this study, we tested the effects of chronic nicotine exposure in preadolescence on adulthood extinction and spontaneous recovery of fear memory in a model in which contextual fear acquisition occurred prior to nicotine exposure. Preadolescent (postnatal day 23) and adult (postnatal day 53) male C57BL/6J mice underwent contextual fear conditioning and were then exposed to chronic nicotine at 12.6 mg/kg/day for 12 days via osmotic minipump. Eighteen days following the removal of nicotine, both groups of mice underwent fear extinction, followed by a spontaneous recovery session a week later. History of chronic nicotine did not affect later extinction of fear memory in adult-trained mice, whereas adolescent-trained mice exhibited a global impairment in retention of fear memory that precluded detection of effects of early nicotine on later fear extinction. However, it was found that adult spontaneous recovery of fear memory was impaired in mice exposed to nicotine as adults and enhanced in mice exposed to nicotine as preadolescents. These results may indicate greater vulnerability to recurrence of traumatic memory as well as compromised inhibitory control in young smokers. (PsycINFO Database Record
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Differential effects of α4β2 nicotinic receptor antagonists and partial-agonists on contextual fear extinction in male C57BL/6 mice. Psychopharmacology (Berl) 2018; 235:1211-1219. [PMID: 29383396 PMCID: PMC5871575 DOI: 10.1007/s00213-018-4837-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 01/19/2018] [Indexed: 02/06/2023]
Abstract
RATIONALE Numerous studies have attributed the psychopathology of post-traumatic stress disorder (PTSD) to maladaptive behavioral responses such as an inability to extinguish fear. While exposure therapies are mostly effective in treating these disorders by enhancing extinction learning, relapse of PTSD symptoms is common. Although several studies indicated a role for cholinergic transmission and nicotinic acetylcholine receptors (nAChRs) in anxiety and stress disorder symptomatology, very little is known about the specific contribution of nAChRs to fear extinction OBJECTIVES: In the present study, we examined the effects of inhibition and desensitization of α4β2 nAChRs via a full antagonist (Dihydro-beta-erythroidine (DhβE)) and two α4β2 nAChR partial-agonists (varenicline and sazetidine-A) on contextual fear extinction, locomotor activity, and spontaneous recovery of contextual fear in mice. METHODS We trained and tested the subjects in a contextual fear extinction as well as an open field paradigm and spontaneous recovery following injections of DhβE, varenicline, and sazetidine-A. RESULTS Our results demonstrated that lower doses of DhβE (1 mg/kg) and sazetidine-A (0.01 mg/kg) enhanced contextual fear extinction whereas higher doses of varenicline (0.1 mg/kg) and sazetidine-A (0.1 mg/kg) resulted in impaired contextual fear extinction. However, the higher dose of sazetidine-A (0.1 mg/kg) decreased locomotor activity, which may contribute to increased freezing response observed during fear extinction. Finally, we found that the low dose of DhβE, but not sazetidine-A, also decreased spontaneous recovery of contextual fear following fear extinction. CONCLUSIONS Overall, these results suggest that inhibition and desensitization of α4β2 nAChRs enhance extinction of contextual fear memories. This suggests that modulation of α4β2 nAChRs may be employed as an alternative pharmacological strategy to aid exposure therapies associated with PTSD by augmenting contextual fear extinction processes.
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Kutlu MG, Cole RD, Connor DA, Natwora B, Gould TJ. Tyrosine receptor kinase B receptor activation reverses the impairing effects of acute nicotine on contextual fear extinction. J Psychopharmacol 2018; 32:367-372. [PMID: 29493350 PMCID: PMC6524773 DOI: 10.1177/0269881118758305] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Anxiety and stress disorders have been linked to deficits in fear extinction. Our laboratory and others have demonstrated that acute nicotine impairs contextual fear extinction, suggesting that nicotine exposure may have negative effects on anxiety and stress disorder symptomatology. However, the neurobiological mechanisms underlying the acute nicotine-induced impairment of contextual fear extinction are unknown. Therefore, based on the previous studies showing that brain-derived neurotrophic factor is central for fear extinction learning and acute nicotine dysregulates brain-derived neurotrophic factor signaling, we hypothesized that the nicotine-induced impairment of contextual fear extinction may involve changes in tyrosine receptor kinase B signaling. To test this hypothesis, we systemically, intraperitoneally, injected C57BL/6J mice sub-threshold doses (2.5 and 4.0 mg/kg) of 7,8-dihydroxyflavone, a small-molecule tyrosine receptor kinase B agonist that fully mimics the effects of brain-derived neurotrophic factor, or vehicle an hour before each contextual fear extinction session. Mice also received injections, intraperitoneally, of acute nicotine (0.18 mg/kg) or saline 2-4 min before extinction sessions. While the animals that received only 7,8-dihydroxyflavone did not show any changes in contextual fear extinction, 4.0 mg/kg of 7,8-dihydroxyflavone ameliorated the extinction deficits in mice administered acute nicotine. Overall, these results suggest that acute nicotine-induced impairment of context extinction may be related to a disrupted brain-derived neurotrophic factor signaling.
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Affiliation(s)
- Munir Gunes Kutlu
- Department of Biobehavioral Health, Pennsylvania State University, USA
| | - Robert D Cole
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University School of Medicine, Nashville, USA
| | - David A Connor
- Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, USA
| | - Brendan Natwora
- Department of Biobehavioral Health, Pennsylvania State University, USA
| | - Thomas J Gould
- Department of Biobehavioral Health, Pennsylvania State University, USA
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Oliver CF, Kutlu MG, Zeid D, Gould TJ. Sex differences in the effects of nicotine on contextual fear extinction. Pharmacol Biochem Behav 2017; 165:25-28. [PMID: 29253499 DOI: 10.1016/j.pbb.2017.12.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 12/13/2017] [Accepted: 12/15/2017] [Indexed: 11/15/2022]
Abstract
Anxiety and stress disorders occur at a higher rate in women compared to men as well as in smokers in comparison to non-smoker population. Nicotine is known to impair fear extinction, which is altered in anxiety disorders. However, nicotine differentially affects fear learning in men and women, which may mean that sex and nicotine-product use can interact to also alter fear extinction. For this study, we examined sex differences in the effects of acute and chronic nicotine administration on fear memory extinction in male and female C57BL/6J mice. To study the acute effects of nicotine, animals trained in a background contextual fear conditioning paradigm were administered nicotine (0.09, 0.18 or 0.36mg/kg) prior to extinction sessions. For chronic nicotine, animals continuously receiving nicotine (12.6, 18, or 24mg/kg/day) were trained in a background contextual fear conditioning paradigm followed by fear extinction sessions. Males exhibited contextual fear extinction deficits following acute and chronic nicotine exposure. Females also exhibited extinction deficits, but only at the highest doses of acute nicotine (0.36mg/kg) while chronic nicotine did not result in extinction deficits in female mice. These results suggest that sex mediates sensitivity to nicotine's effects on contextual fear memory extinction.
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Affiliation(s)
- Chicora F Oliver
- Department of Biobehavioral Health, 219 Biobehavioral Health Bldg, The Pennsylvania State University, University Park, PA 16802
| | - Munir Gunes Kutlu
- Department of Biobehavioral Health, 219 Biobehavioral Health Bldg, The Pennsylvania State University, University Park, PA 16802
| | - Dana Zeid
- Department of Biobehavioral Health, 219 Biobehavioral Health Bldg, The Pennsylvania State University, University Park, PA 16802
| | - Thomas J Gould
- Department of Biobehavioral Health, 219 Biobehavioral Health Bldg, The Pennsylvania State University, University Park, PA 16802.
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