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Sarka BC, Liu S, Banerjee A, Stucky CL, Liu Q, Olsen CM. Neuropathic pain has sex-specific effects on oxycodone-seeking and non-drug-seeking ensemble neurons in the dorsomedial prefrontal cortex of mice. Addict Biol 2024; 29:e13430. [PMID: 39121884 PMCID: PMC11315577 DOI: 10.1111/adb.13430] [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: 05/15/2024] [Revised: 07/06/2024] [Accepted: 07/12/2024] [Indexed: 08/12/2024]
Abstract
Approximately 50 million Americans suffer from chronic pain, and nearly a quarter of chronic pain patients have reported misusing opioid prescriptions. Repeated drug seeking is associated with reactivation of an ensemble of neurons sparsely scattered throughout the dorsomedial prefrontal cortex (dmPFC). Prior research has demonstrated that chronic pain increases intrinsic excitability of dmPFC neurons, which may increase the likelihood of reactivation during drug seeking. We tested the hypothesis that chronic pain would increase oxycodone-seeking behaviour and that the pain state would differentially increase intrinsic excitability in dmPFC drug-seeking ensemble neurons. TetTag mice self-administered intravenous oxycodone. After 7 days of forced abstinence, a drug-seeking session was performed, and the ensemble was tagged. Mice received spared nerve injury (SNI) to induce chronic pain during the period between the first and second seeking session. Following the second seeking session, we performed electrophysiology on individual neurons within the dmPFC to assess intrinsic excitability of the drug-seeking ensemble and non-ensemble neurons. SNI had no impact on sucrose seeking or intrinsic excitability of dmPFC neurons from these mice. In females, SNI increased oxycodone seeking and intrinsic excitability of non-ensemble neurons. In males, SNI had no impact on oxycodone seeking or neuron excitability. Data from females are consistent with clinical reports that chronic pain can promote drug craving and relapse and support the hypothesis that chronic pain itself may lead to neuroadaptations which promote opioid seeking.
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Affiliation(s)
- Bailey C. Sarka
- Department of Pharmacology and ToxicologyMedical College of WisconsinMilwaukeeWisconsinUSA
- Neuroscience Research CenterMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Shuai Liu
- Department of Pharmacology and ToxicologyMedical College of WisconsinMilwaukeeWisconsinUSA
- Neuroscience Research CenterMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Anjishnu Banerjee
- Division of BiostatisticsMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Cheryl L. Stucky
- Neuroscience Research CenterMedical College of WisconsinMilwaukeeWisconsinUSA
- Department of Cell Biology, Neurobiology and AnatomyMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Qing‐song Liu
- Department of Pharmacology and ToxicologyMedical College of WisconsinMilwaukeeWisconsinUSA
- Neuroscience Research CenterMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Christopher M. Olsen
- Department of Pharmacology and ToxicologyMedical College of WisconsinMilwaukeeWisconsinUSA
- Neuroscience Research CenterMedical College of WisconsinMilwaukeeWisconsinUSA
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Doyle MA, Salimando GJ, Altemus ME, Badt JK, Bedenbaugh MN, Vardy AS, Adank DN, Park AS, Winder DG. BNST GluN2D-containing NMDARs contribute to ethanol intake but not negative affective behaviors in female mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.19.590258. [PMID: 38659775 PMCID: PMC11042366 DOI: 10.1101/2024.04.19.590258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Alcohol use disorder (AUD) is a chronic, relapsing disease, highly comorbid with anxiety and depression. The bed nucleus of the stria terminalis (BNST), and Crh + neurons in this region are thought to play a key role in chronic ethanol-induced increases in volitional ethanol intake. This role has been hypothesized to be driven by emergent BNST-dependent negative affective behaviors. Indeed, we report here that in female mice undergoing a home cage chronic drinking forced abstinence model (CDFA), excitatory transmission undergoes time-dependent upregulation in BNST Crh + cells. Excitatory NMDA receptors (NMDARs) are a major target of ethanol, and chronic ethanol exposure has been shown to regulate NMDAR function and expression. GluN2D subunit-containing NMDARs have emerged as a target of interest due to their limited distribution and potential roles in affective behavior. We find that knockdown of dorsal BNST (dBNST) GluN2D expression significantly decreases ethanol intake in female, but not male, mice. While BNST Grin2b expression was significantly increased in protracted abstinence following CDFA, no differences in Grin2d expression were observed in dBNST or specifically in dBNST Crh + neurons. Finally, to determine the impact of GluN2D expression on negative affective behaviors, open field, elevated zero maze, and forced swim tasks were used to measure anxiety- and depressive-like behaviors in constitutive and conditional BNST GluN2D knockout mice. Surprisingly, we find that deletion of GluN2D fails to alter negative affect in ethanol-naïve female mice. Together, these data suggest a role for BNST GluN2D-containing NMDARs in ethanol drinking behaviors but not abstinence from ethanol, highlighting potential sex differences and behavioral specificity in the context of AUD behaviors. Overall, these data further suggest roles for BNST synaptic signaling in volitional ethanol intake that are partially independent of actions on affective behavior.
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Nagashima T, Mikami K, Tohyama S, Konno A, Hirai H, Watabe AM. State-dependent modulation of positive and negative affective valences by a parabrachial nucleus-to-ventral tegmental area pathway in mice. Front Neural Circuits 2023; 17:1273322. [PMID: 38094239 PMCID: PMC10716301 DOI: 10.3389/fncir.2023.1273322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Accepted: 11/14/2023] [Indexed: 12/18/2023] Open
Abstract
Appropriately responding to various sensory signals in the environment is essential for animal survival. Accordingly, animal behaviors are closely related to external and internal states, which include the positive and negative emotional values of sensory signals triggered by environmental factors. While the lateral parabrachial nucleus (LPB) plays a key role in nociception and supports negative valences, it also transmits signals including positive valences. However, the downstream neuronal mechanisms of positive and negative valences have not been fully explored. In the present study, we investigated the ventral tegmental area (VTA) as a projection target for LPB neurons. Optogenetic activation of LPB-VTA terminals in male mice elicits positive reinforcement in an operant task and induces both avoidance and attraction in a place-conditioning task. Inhibition of glutamic acid decarboxylase (GAD) 65-expressing cells in the VTA promotes avoidance behavior induced by photoactivation of the LPB-VTA pathway. These findings indicate that the LPB-VTA pathway is one of the LPB outputs for the transmission of positive and negative valence signals, at least in part, with GABAergic modification in VTA.
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Affiliation(s)
- Takashi Nagashima
- Institute of Clinical Medicine and Research, Research Center for Medical Sciences, The Jikei University School of Medicine, Chiba, Japan
| | - Kaori Mikami
- Institute of Clinical Medicine and Research, Research Center for Medical Sciences, The Jikei University School of Medicine, Chiba, Japan
| | - Suguru Tohyama
- Institute of Clinical Medicine and Research, Research Center for Medical Sciences, The Jikei University School of Medicine, Chiba, Japan
| | - Ayumu Konno
- Gunma University Graduate School of Medicine, Maebashi, Japan
- Viral Vector Core, Gunma University Initiative for Advanced Research (GIAR), Maebashi, Japan
| | - Hirokazu Hirai
- Gunma University Graduate School of Medicine, Maebashi, Japan
- Viral Vector Core, Gunma University Initiative for Advanced Research (GIAR), Maebashi, Japan
| | - Ayako M. Watabe
- Institute of Clinical Medicine and Research, Research Center for Medical Sciences, The Jikei University School of Medicine, Chiba, Japan
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4
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Farahbakhsh ZZ, Song K, Branthwaite HE, Erickson KR, Mukerjee S, Nolan SO, Siciliano CA. Systemic kappa opioid receptor antagonism accelerates reinforcement learning via augmentation of novelty processing in male mice. Neuropsychopharmacology 2023; 48:857-868. [PMID: 36804487 PMCID: PMC10156709 DOI: 10.1038/s41386-023-01547-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 01/20/2023] [Accepted: 02/02/2023] [Indexed: 02/19/2023]
Abstract
Selective inhibition of kappa opioid receptors (KORs) is highly anticipated as a pharmacotherapeutic intervention for substance use disorders and depression. The accepted explanation for KOR antagonist-induced amelioration of aberrant behaviors posits that KORs globally function as a negative valence system; antagonism thereby blunts the behavioral influence of negative internal states such as anhedonia and negative affect. While effects of systemic KOR manipulations have been widely reproduced, explicit evaluation of negative valence as an explanatory construct is lacking. Here, we tested a series of falsifiable hypotheses generated a priori based on the negative valence model by pairing reinforcement learning tasks with systemic pharmacological KOR blockade in male C57BL/6J mice. The negative valence model failed to predict multiple experimental outcomes: KOR blockade accelerated contingency learning during both positive and negative reinforcement without altering innate responses to appetitive or aversive stimuli. We next proposed novelty processing, which influences learning independent of valence, as an alternative explanatory construct. Hypotheses based on novelty processing predicted subsequent observations: KOR blockade increased exploration of a novel, but not habituated, environment and augmented the reinforcing efficacy of novel visual stimuli in a sensory reinforcement task. Together, these results revise and extend long-standing theories of KOR system function.
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Affiliation(s)
- Zahra Z Farahbakhsh
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Keaton Song
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Hannah E Branthwaite
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Kirsty R Erickson
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Snigdha Mukerjee
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Suzanne O Nolan
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Cody A Siciliano
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA.
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Slosky LM, Pires A, Bai Y, Clark NB, Hauser ER, Gross JD, Porkka F, Zhou Y, Chen X, Pogorelov VM, Toth K, Wetsel WC, Barak LS, Caron MG. Establishment of multi-stage intravenous self-administration paradigms in mice. Sci Rep 2022; 12:21422. [PMID: 36503898 PMCID: PMC9742147 DOI: 10.1038/s41598-022-24740-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 11/18/2022] [Indexed: 12/14/2022] Open
Abstract
Genetically tractable animal models provide needed strategies to resolve the biological basis of drug addiction. Intravenous self-administration (IVSA) is the gold standard for modeling psychostimulant and opioid addiction in animals, but technical limitations have precluded the widespread use of IVSA in mice. Here, we describe IVSA paradigms for mice that capture the multi-stage nature of the disorder and permit predictive modeling. In these paradigms, C57BL/6J mice with long-standing indwelling jugular catheters engaged in cocaine- or remifentanil-associated lever responding that was fixed ratio-dependent, dose-dependent, extinguished by withholding the drug, and reinstated by the presentation of drug-paired cues. The application of multivariate analysis suggested that drug taking in both paradigms was a function of two latent variables we termed incentive motivation and discriminative control. Machine learning revealed that vulnerability to drug seeking and relapse were predicted by a mouse's a priori response to novelty, sensitivity to drug-induced locomotion, and drug-taking behavior. The application of these behavioral and statistical-analysis approaches to genetically-engineered mice will facilitate the identification of neural circuits driving addiction susceptibility and relapse and focused therapeutic development.
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Affiliation(s)
- Lauren M Slosky
- Department of Cell Biology, Duke University, Durham, NC, USA.
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA.
| | - Andrea Pires
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - Yushi Bai
- Department of Cell Biology, Duke University, Durham, NC, USA
| | | | - Elizabeth R Hauser
- Department of Biostatistics and Bioinformatics, Duke University, Durham, NC, USA
| | - Joshua D Gross
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - Fiona Porkka
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - Yang Zhou
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - Xiaoxiao Chen
- School of Industrial and Systems Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Vladimir M Pogorelov
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC, USA
| | - Krisztian Toth
- Department of Pharmaceutical Sciences, Campbell University, Buies Creek, NC, USA
| | - William C Wetsel
- Department of Cell Biology, Duke University, Durham, NC, USA
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC, USA
- Department of Neurobiology, Duke University, Durham, NC, USA
- Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University, Durham, NC, USA
| | | | - Marc G Caron
- Department of Cell Biology, Duke University, Durham, NC, USA
- Department of Neurobiology, Duke University, Durham, NC, USA
- Department of Medicine, Duke University, Durham, NC, USA
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6
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López AJ, Johnson AR, Kunnath AJ, Morris AD, Zachry JE, Thibeault KC, Kutlu MG, Siciliano CA, Calipari ES. An optimized procedure for robust volitional cocaine intake in mice. Exp Clin Psychopharmacol 2021; 29:319-333. [PMID: 32658535 PMCID: PMC7890946 DOI: 10.1037/pha0000399] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Substance use disorder (SUD) is a behavioral disorder characterized by volitional drug consumption. Mouse models of SUD allow for the use of molecular, genetic, and circuit-level tools, providing enormous potential for defining the underlying mechanisms of this disorder. However, the relevance of results depends on the validity of the mouse models used. Self-administration models have long been the preferred preclinical model for SUD as they allow for volitional drug consumption, thus providing strong face validity. While previous work has defined the parameters that influence intravenous cocaine self-administration in other species-such as rats and primates-many of these parameters have not been explicitly assessed in mice. In a series of experiments, we showed that commonly used mouse models of self-administration, where behavior is maintained on a fixed-ratio schedule of reinforcement, show similar levels of responding in the presence and absence of drug delivery-demonstrating that it is impossible to determine when drug consumption is and is not volitional. To address these issues, we have developed a novel mouse self-administration procedure where animals do not need to be pretrained on sucrose and behavior is maintained on a variable-ratio schedule of reinforcement. This procedure increases rates of reinforcement behavior, increases levels of drug intake, and results in clearer delineation between drug-reinforced and saline conditions. Together, these data highlight a major issue with fixed-ratio models in mice that complicates subsequent analysis and provide a simple approach to minimize these confounds with variable-ratio schedules of reinforcement. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
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Affiliation(s)
- Alberto J López
- Department of Pharmacology, Vanderbilt University/Vanderbilt University School of Medicine
| | - Amy R Johnson
- Department of Pharmacology, Vanderbilt University/Vanderbilt University School of Medicine
| | - Ansley J Kunnath
- Vanderbilt University Medical Scientists Training Program, Vanderbilt University/Vanderbilt University School of Medicine
| | - Allison D Morris
- Department of Pharmacology, Vanderbilt University/Vanderbilt University School of Medicine
| | - Jennifer E Zachry
- Department of Pharmacology, Vanderbilt University/Vanderbilt University School of Medicine
| | - Kimberly C Thibeault
- Department of Pharmacology, Vanderbilt University/Vanderbilt University School of Medicine
| | - Munir G Kutlu
- Department of Pharmacology, Vanderbilt University/Vanderbilt University School of Medicine
| | - Cody A Siciliano
- Department of Pharmacology, Vanderbilt Center for Addiction Research, Vanderbilt University/Vanderbilt University School of Medicine
| | - Erin S Calipari
- Department of Pharmacology, Vanderbilt University/Vanderbilt University School of Medicine
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7
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Salimando GJ, Hyun M, Boyt KM, Winder DG. BNST GluN2D-Containing NMDA Receptors Influence Anxiety- and Depressive-like Behaviors and ModulateCell-Specific Excitatory/Inhibitory Synaptic Balance. J Neurosci 2020; 40:3949-3968. [PMID: 32277042 PMCID: PMC7219300 DOI: 10.1523/jneurosci.0270-20.2020] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 02/26/2020] [Indexed: 12/23/2022] Open
Abstract
Excitatory signaling mediated by NMDARs has been shown to regulate mood disorders. However, current treatments targeting NMDAR subtypes have shown limited success in treating patients, highlighting a need for alternative therapeutic targets. Here, we identify a role for GluN2D-containing NMDARs in modulating emotional behaviors and neural activity in the bed nucleus of the stria terminalis (BNST). Using a GluN2D KO mouse line (GluN2D-/-), we assessed behavioral phenotypes across tasks modeling emotional behavior. We then used a combination of ex vivo electrophysiology and in vivo fiber photometry to assess changes in BNST plasticity, cell-specific physiology, and cellular activity profiles. GluN2D-/- male mice exhibit evidence of exacerbated negative emotional behavior, and a deficit in BNST synaptic potentiation. We also found that GluN2D is functionally expressed on corticotropin-releasing factor (CRF)-positive BNST cells implicated in driving negative emotional states, and recordings in mice of both sexes revealed increased excitatory and reduced inhibitory drive onto GluN2D-/- BNST-CRF cells ex vivo and increased activity in vivo Using a GluN2D conditional KO line (GluN2Dflx/flx) to selectively delete the subunit from the BNST, we find that BNST-GluN2Dflx/flx male mice exhibit increased depressive-like behaviors, as well as altered NMDAR function and increased excitatory drive onto BNST-CRF neurons. Together, this study supports a role for GluN2D-NMDARs in regulating emotional behavior through their influence on excitatory signaling in a region-specific manner, and suggests that these NMDARs may serve as a novel target for selectively modulating glutamate signaling in stress-responsive structures and cell populations.SIGNIFICANCE STATEMENT Excitatory signaling mediated through NMDARs plays an important role in shaping emotional behavior; however, the receptor subtypes/brain regions through which this occurs are poorly understood. Here, we demonstrate that loss of GluN2D-containing NMDARs produces an increase in anxiety- and depressive-like behaviors in mice, deficits in BNST synaptic potentiation, and increased activity in BNST-CRF neurons known to drive negative emotional behavior. Further, we determine that deleting GluN2D in the BNST leads to increased depressive-like behaviors and increased excitatory drive onto BNST-CRF cells. Collectively, these results demonstrate a role for GluN2D-NMDARs in regulating the activity of stress-responsive structures and neuronal populations in the adult brain, suggesting them as a potential target for treating negative emotional states in mood-related disorders.
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Affiliation(s)
- Gregory J Salimando
- Department of Molecular Physics & Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, 37212
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee, 37212
- Vanderbilt University Medical Center, Vanderbilt Kennedy Center, Nashville, Tennessee, 37203
- Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, Tennessee, 37232
| | - Minsuk Hyun
- Howard Hughes Medical Institute, Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, 02115
| | - Kristen M Boyt
- Bowles Center for Alcohol Studies, Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, 27599
| | - Danny G Winder
- Department of Molecular Physics & Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, 37212
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee, 37212
- Vanderbilt University Medical Center, Vanderbilt Kennedy Center, Nashville, Tennessee, 37203
- Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, Tennessee, 37232
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, 37212
- Department of Psychiatry & Behavioral Sciences, Vanderbilt University School of Medicine, Nashville, Tennessee, 37212
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8
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Centanni SW, Morris BD, Luchsinger JR, Bedse G, Fetterly TL, Patel S, Winder DG. Endocannabinoid control of the insular-bed nucleus of the stria terminalis circuit regulates negative affective behavior associated with alcohol abstinence. Neuropsychopharmacology 2019; 44:526-537. [PMID: 30390064 PMCID: PMC6333805 DOI: 10.1038/s41386-018-0257-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 10/19/2018] [Accepted: 10/21/2018] [Indexed: 01/04/2023]
Abstract
Negative affect is a core symptom domain associated with an array of neurological and psychiatric disorders and is only partially targeted by current therapies, highlighting the need for better, more targeted treatment options. This study focuses on negative affective symptoms associated with prolonged alcohol abstinence, one of the leading causes of relapse. Using a mouse model of chronic alcohol consumption followed by forced abstinence (CDFA), prolonged alcohol abstinence increased c-fos expression and spontaneous glutamatergic neurotransmission in the dorsal bed nucleus of the stria terminalis (dBNST), a region heavily implicated in negative affect in both humans and rodents. Further, pharmacologically enhancing endogenous cannabinoids (eCB) with JZL184 prevents abstinence-induced increases in dBNST neuronal activity, underscoring the therapeutic potential of drugs targeting the brain's eCB system. Next, we used a channelrhodopsin-assisted mapping strategy to identify excitatory inputs to the dBNST that could contribute to CDFA-induced negative affect. We identified the insular cortex (insula), a region involved in regulating interoception, as a dense, functional, eCB-sensitive input to the dBNST. Using a chemogenetic strategy to locally mimic eCB signaling, we demonstrate that the insula strongly influences the CDFA behavioral phenotype and dBNST neuronal activity. Lastly, we used an anterograde strategy for transynaptic targeting of Cre expression in combination with a Gq-DREADD to selectively recruit dBNST neurons receiving insula projections. Chemogenetic recruitment of these neurons mimicked behavioral and c-fos responses observed in CDFA. Collectively, this study supports a role for the insula-BNST neural circuit in negative affective disturbances and highlights the therapeutic potential of the eCB system for treating negative affective disorders.
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Affiliation(s)
- Samuel W Centanni
- Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt J.F. Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Bridget D Morris
- Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Joseph R Luchsinger
- Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt J.F. Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Gaurav Bedse
- Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt J.F. Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Tracy L Fetterly
- Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt J.F. Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Sachin Patel
- Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, USA
- Vanderbilt J.F. Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Danny G Winder
- Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, TN, USA.
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA.
- Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, USA.
- Vanderbilt J.F. Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, TN, USA.
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
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9
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α 2A-Adrenergic Receptor Activation Decreases Parabrachial Nucleus Excitatory Drive onto BNST CRF Neurons and Reduces Their Activity In Vivo. J Neurosci 2018; 39:472-484. [PMID: 30478032 DOI: 10.1523/jneurosci.1035-18.2018] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 10/18/2018] [Accepted: 11/19/2018] [Indexed: 11/21/2022] Open
Abstract
Stress contributes to numerous psychiatric disorders. Corticotropin releasing factor (CRF) signaling and CRF neurons in the bed nucleus of the stria terminalis (BNST) drive negative affective behaviors, thus agents that decrease activity of these cells may be of therapeutic interest. Here, we show that acute restraint stress increases cFos expression in CRF neurons in the mouse dorsal BNST, consistent with a role for these neurons in stress-related behaviors. We find that activation of α2A-adrenergic receptors (ARs) by the agonist guanfacine reduced cFos expression in these neurons both in stressed and unstressed conditions. Further, we find that α- and β-ARs differentially regulate excitatory drive onto these neurons. Pharmacological and channelrhodopsin-assisted mapping experiments suggest that α2A-ARs specifically reduce excitatory drive from parabrachial nucleus (PBN) afferents onto CRF neurons. Given that the α2A-AR is a Gi-linked GPCR, we assessed the impact of activating the Gi-coupled DREADD hM4Di in the PBN on restraint stress regulation of BNST CRF neurons. CNO activation of PBN hM4Di reduced stress-induced Fos in BNST Crh neurons. Further, using Prkcd as an additional marker of BNST neuronal identity, we uncovered a female-specific upregulation of the coexpression of Prkcd/Crh in BNST neurons following stress, which was prevented by ovariectomy. These findings show that stress activates BNST CRF neurons, and that α2A-AR activation suppresses the in vivo activity of these cells, at least in part by suppressing excitatory drive from PBN inputs onto CRF neurons.SIGNIFICANCE STATEMENT Stress is a major variable contributing to mood disorders. Here, we show that stress increases activation of BNST CRF neurons that drive negative affective behavior. We find that the clinically well tolerated α2A-AR agonist guanfacine reduces activity of these cells in vivo, and reduces excitatory PBN inputs onto these cells ex vivo Additionally, we uncover a novel sex-dependent coexpression of Prkcd with Crh in female BNST neurons after stress, an effect abolished by ovariectomy. These results demonstrate input-specific interactions between norepinephrine and CRF, and point to an action by which guanfacine may reduce negative affective responses.
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10
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Dickson PE, Roy TA, McNaughton KA, Wilcox TD, Kumar P, Chesler EJ. Systems genetics of sensation seeking. GENES BRAIN AND BEHAVIOR 2018; 18:e12519. [PMID: 30221471 PMCID: PMC6399063 DOI: 10.1111/gbb.12519] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Revised: 09/09/2018] [Accepted: 09/11/2018] [Indexed: 02/06/2023]
Abstract
Sensation seeking is a multifaceted, heritable trait which predicts the development of substance use and abuse in humans; similar phenomena have been observed in rodents. Genetic correlations among sensation seeking and substance use indicate shared biological mechanisms, but the genes and networks underlying these relationships remain elusive. Here, we used a systems genetics approach in the BXD recombinant inbred mouse panel to identify shared genetic mechanisms underlying substance use and preference for sensory stimuli, an intermediate phenotype of sensation seeking. Using the operant sensation seeking (OSS) paradigm, we quantified preference for sensory stimuli in 120 male and 127 female mice from 62 BXD strains and the C57BL/6J and DBA/2J founder strains. We used relative preference for the active and inactive levers to dissociate preference for sensory stimuli from locomotion and exploration phenotypes. We identified genomic regions on chromosome 4 (155.236‐155.742 Mb) and chromosome 13 (72.969‐89.423 Mb) associated with distinct behavioral components of OSS. Using publicly available behavioral data and mRNA expression data from brain regions involved in reward processing, we identified (a) genes within these behavioral QTL exhibiting genome‐wide significant cis‐eQTL and (b) genetic correlations among OSS phenotypes, ethanol phenotypes and mRNA expression. From these analyses, we nominated positional candidates for behavioral QTL associated with distinct OSS phenotypes including Gnb1 and Mef2c. Genetic covariation of Gnb1 expression, preference for sensory stimuli and multiple ethanol phenotypes suggest that heritable variation in Gnb1 expression in reward circuitry partially underlies the widely reported relationship between sensation seeking and substance use.
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Affiliation(s)
- Price E. Dickson
- Center for Systems Neurogenetics of AddictionThe Jackson LaboratoryBar HarborMaine
| | - Tyler A. Roy
- Center for Systems Neurogenetics of AddictionThe Jackson LaboratoryBar HarborMaine
| | | | - Troy D. Wilcox
- Center for Systems Neurogenetics of AddictionThe Jackson LaboratoryBar HarborMaine
| | - Padam Kumar
- Center for Systems Neurogenetics of AddictionThe Jackson LaboratoryBar HarborMaine
| | - Elissa J. Chesler
- Center for Systems Neurogenetics of AddictionThe Jackson LaboratoryBar HarborMaine
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Dorsal BNST α 2A-Adrenergic Receptors Produce HCN-Dependent Excitatory Actions That Initiate Anxiogenic Behaviors. J Neurosci 2018; 38:8922-8942. [PMID: 30150361 DOI: 10.1523/jneurosci.0963-18.2018] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Revised: 08/15/2018] [Accepted: 08/20/2018] [Indexed: 11/21/2022] Open
Abstract
Stress is a precipitating agent in neuropsychiatric disease and initiates relapse to drug-seeking behavior in addicted patients. Targeting the stress system in protracted abstinence from drugs of abuse with anxiolytics may be an effective treatment modality for substance use disorders. α2A-adrenergic receptors (α2A-ARs) in extended amygdala structures play key roles in dampening stress responses. Contrary to early thinking, α2A-ARs are expressed at non-noradrenergic sites in the brain. These non-noradrenergic α2A-ARs play important roles in stress responses, but their cellular mechanisms of action are unclear. In humans, the α2A-AR agonist guanfacine reduces overall craving and uncouples craving from stress, yet minimally affects relapse, potentially due to competing actions in the brain. Here, we show that heteroceptor α2A-ARs postsynaptically enhance dorsal bed nucleus of the stria terminalis (dBNST) neuronal activity in mice of both sexes. This effect is mediated by hyperpolarization-activated cyclic nucleotide-gated cation channels because inhibition of these channels is necessary and sufficient for excitatory actions. Finally, this excitatory action is mimicked by clozapine-N-oxide activation of the Gi-coupled DREADD hM4Di in dBNST neurons and its activation elicits anxiety-like behavior in the elevated plus maze. Together, these data provide a framework for elucidating cell-specific actions of GPCR signaling and provide a potential mechanism whereby competing anxiogenic and anxiolytic actions of guanfacine may affect its clinical utility in the treatment of addiction.SIGNIFICANCE STATEMENT Stress affects the development of neuropsychiatric disorders including anxiety and addiction. Guanfacine is an α2A-adrenergic receptor (α2A-AR) agonist with actions in the bed nucleus of the stria terminalis (BNST) that produces antidepressant actions and uncouples stress from reward-related behaviors. Here, we show that guanfacine increases dorsal BNST neuronal activity through actions at postsynaptic α2A-ARs via a mechanism that involves hyperpolarization-activated cyclic nucleotide gated cation channels. This action is mimicked by activation of the designer receptor hM4Di expressed in the BNST, which also induces anxiety-like behaviors. Together, these data suggest that postsynaptic α2A-ARs in BNST have excitatory actions on BNST neurons and that these actions can be phenocopied by the so-called "inhibitory" DREADDs, suggesting that care must be taken regarding interpretation of data obtained with these tools.
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Cannabinoid Receptor 1 and Fatty Acid Amide Hydrolase Contribute to Operant Sensation Seeking in Mice. Int J Mol Sci 2017; 18:ijms18081635. [PMID: 28749428 PMCID: PMC5578025 DOI: 10.3390/ijms18081635] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 07/21/2017] [Accepted: 07/25/2017] [Indexed: 11/20/2022] Open
Abstract
A large body of evidence in humans and preclinical models supports a role for the endocannabinoid system in the proper execution of motivated or goal-directed behaviors. Operant sensation seeking (OSS) is a task that uses varied sensory stimuli as a reinforcer to maintain operant responding in mice. The purpose of the studies in this report was to begin to explore the role of endocannabinoid signaling in OSS utilizing cannabinoid receptor 1 (CB1R) and fatty acid amide hydrolase (FAAH) knock out mice. Compared to wild type littermate controls, CB1R knock out mice exhibited significantly fewer active responses and earned significantly fewer reinforcers in fixed ratio and progressive ratio schedules. On the other hand, FAAH knock out mice exhibited increased active responses and earned more reinforcers than wild type littermates in fixed ratio but not progressive ratio schedules. These findings support the role of endocannabinoid signaling in motivated behaviors and also expand our understanding of the signaling processes involved in OSS.
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Muelbl MJ, Nawarawong NN, Clancy PT, Nettesheim CE, Lim YW, Olsen CM. Responses to drugs of abuse and non-drug rewards in leptin deficient ob/ob mice. Psychopharmacology (Berl) 2016; 233:2799-811. [PMID: 27256358 PMCID: PMC5095929 DOI: 10.1007/s00213-016-4323-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 05/09/2016] [Indexed: 12/28/2022]
Abstract
RATIONALE Although leptin receptors are found in hypothalamic nuclei classically associated with homeostatic feeding mechanisms, they are also present in brain regions known to regulate hedonic-based feeding, natural reward processing, and responses to drugs of abuse. The ob/ob mouse is deficient in leptin signaling, and previous work has found altered mesolimbic dopamine signaling and sensitivity to the locomotor activating effects of amphetamine in these mice. OBJECTIVES We directly assessed responses to three drugs of abuse and non-drug rewards in the leptin-deficient ob/ob mouse. METHODS Ob/ob mice were tested in assays of sweet preference, novelty seeking, and drug reward/reinforcement. RESULTS In assays of novelty seeking, novel open field activity and operant sensation seeking were reduced in ob/ob mice, although novel object interaction and novel environment preference were comparable to wild types. We also found that ob/ob mice had specific phenotypes in regard to cocaine: conditioned place preference for 2.5 mg/kg was increased, while the locomotor response to 10 mg/kg was reduced, and cocaine self-administration was the same as wild types. Ob/ob mice also acquired self-administration of the potent opioid remifentanil, but breakpoints for the drug were significantly reduced. Finally, we found significant differences in ethanol drinking in ob/ob mice that correlated negatively with body weight and positively with operant sensation seeking. CONCLUSIONS In conclusion, ob/ob mice displayed task-specific deficits in novelty seeking and dissociable differences in reward/reinforcement associated with cocaine, remifentanil, and ethanol.
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Affiliation(s)
- Matthew J. Muelbl
- Neuroscience Research Center and Department of Pharmacology & Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Natalie N. Nawarawong
- Neuroscience Research Center and Department of Pharmacology & Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Patrick T. Clancy
- Neuroscience Research Center and Department of Pharmacology & Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Catherine E. Nettesheim
- Neuroscience Research Center and Department of Pharmacology & Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Yi Wei Lim
- Neuroscience Research Center and Department of Pharmacology & Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Christopher M. Olsen
- Neuroscience Research Center and Department of Pharmacology & Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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14
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Mueller R, Dawson ES, Meiler J, Rodriguez AL, Chauder BA, Bates BS, Felts AS, Lamb JP, Menon UN, Jadhav SB, Kane AS, Jones CK, Gregory KJ, Niswender CM, Conn PJ, Olsen CM, Winder DG, Emmitte KA, Lindsley CW. Discovery of 2-(2-benzoxazoyl amino)-4-aryl-5-cyanopyrimidine as negative allosteric modulators (NAMs) of metabotropic glutamate receptor 5 (mGlu₅): from an artificial neural network virtual screen to an in vivo tool compound. ChemMedChem 2012; 7:406-14. [PMID: 22267125 DOI: 10.1002/cmdc.201100510] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Indexed: 11/12/2022]
Affiliation(s)
- Ralf Mueller
- Department of Chemistry, Vanderbilt University, 7330 Stevenson Center, Station B 351822, Nashville, TN 37232-6600, USA
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15
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Olsen CM, Winder DG. Stimulus dynamics increase the self-administration of compound visual and auditory stimuli. Neurosci Lett 2012; 511:8-11. [PMID: 22249116 DOI: 10.1016/j.neulet.2011.12.068] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2011] [Revised: 12/29/2011] [Accepted: 12/30/2011] [Indexed: 10/14/2022]
Abstract
Animals will acquire an operant task using sensory stimuli as a primary reinforcer. Many operant tasks use sensory stimuli as cues that are paired with other primary reinforcers. Recent studies have called attention to this potential confound, but there has not been a parametric assessment of the effect of stimulus variability on operant responding. We found that stimulus variability increased the amount of operant responding exhibited by mice, a phenomenon observed under both fixed- and progressive-ratio schedules.
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Affiliation(s)
- Christopher M Olsen
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-0615, USA.
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Olsen CM. Natural rewards, neuroplasticity, and non-drug addictions. Neuropharmacology 2011; 61:1109-22. [PMID: 21459101 PMCID: PMC3139704 DOI: 10.1016/j.neuropharm.2011.03.010] [Citation(s) in RCA: 237] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 03/08/2011] [Accepted: 03/09/2011] [Indexed: 01/28/2023]
Abstract
There is a high degree of overlap between brain regions involved in processing natural rewards and drugs of abuse. "Non-drug" or "behavioral" addictions have become increasingly documented in the clinic, and pathologies include compulsive activities such as shopping, eating, exercising, sexual behavior, and gambling. Like drug addiction, non-drug addictions manifest in symptoms including craving, impaired control over the behavior, tolerance, withdrawal, and high rates of relapse. These alterations in behavior suggest that plasticity may be occurring in brain regions associated with drug addiction. In this review, I summarize data demonstrating that exposure to non-drug rewards can alter neural plasticity in regions of the brain that are affected by drugs of abuse. Research suggests that there are several similarities between neuroplasticity induced by natural and drug rewards and that, depending on the reward, repeated exposure to natural rewards might induce neuroplasticity that either promotes or counteracts addictive behavior.
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Affiliation(s)
- Christopher M Olsen
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-0615, USA.
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Lindsley CW, Bates BS, Menon UN, Jadhav SB, Kane AS, Jones CK, Rodriguez AL, Conn PJ, Olsen CM, Winder DG, Emmitte KA. (3-Cyano-5-fluorophenyl)biaryl negative allosteric modulators of mGlu(5): Discovery of a new tool compound with activity in the OSS mouse model of addiction. ACS Chem Neurosci 2011; 2:471-482. [PMID: 21927650 DOI: 10.1021/cn100099n] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Glutamate is the major excitatory transmitter in the mammalian CNS, exerting its effects through both ionotropic and metabotropic glutamate receptors. The metabotropic glutamate receptors (mGlus) belong to family C of the G-protein-coupled receptors (GPCRs). The eight mGlus identified to date are classified into three groups based on their structure, preferred signal transduction mechanisms, and pharmacology (Group I: mGlu(1) and mGlu(5); Group II: mGlu(2) and mGlu(3); Group III: mGlu(4), mGlu(6), mGlu(7), and mGlu(8)). Non-competitive antagonists, also known as negative allosteric modulators (NAMs), of mGlu(5) offer potential therapeutic applications in diseases such as pain, anxiety, gastroesophageal reflux disease (GERD), Parkinson's disease (PD), fragile X syndrome, and addiction. The development of SAR in a (3-cyano-5-fluorophenyl)biaryl series using our functional cell-based assay is described in this communication. Further characterization of a selected compound, 3-fluoro-5-(2-methylbenzo[d]thiazol-5-yl)benzonitrile, in additional cell based assays as well as in vitro assays designed to measure its metabolic stability and protein binding indicated its potential utility as an in vivo tool. Subsequent evaluation of the same compound in a pharmacokinetic study using intraperitoneal dosing in mice showed good exposure in both plasma and brain samples. The compound was efficacious in a mouse marble burying model of anxiety, an assay known to be sensitive to mGlu(5) antagonists. A new operant model of addiction termed operant sensation seeking (OSS) was chosen as a second behavioral assay. The compound also proved efficacious in the OSS model and constitutes the first reported example of efficacy with a small molecule mGlu(5) NAM in this novel assay.
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Affiliation(s)
| | | | | | | | | | - Carrie K. Jones
- Tennesse Valley Healthcare System, U.S. Department of Veterans Affairs, Nashville, Tennessee 37212, United States
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Operant sensation seeking requires metabotropic glutamate receptor 5 (mGluR5). PLoS One 2010; 5:e15085. [PMID: 21152045 PMCID: PMC2994905 DOI: 10.1371/journal.pone.0015085] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 10/18/2010] [Indexed: 11/19/2022] Open
Abstract
Pharmacological and genetic studies have suggested that the metabotropic glutamate receptor 5 (mGluR5) is critically involved in mediating the reinforcing effects of drugs of abuse, but not food. The purpose of this study was to use mGluR5 knockout (KO), heterozygous (Het), and wildtype (WT) mice to determine if mGluR5 modulates operant sensation seeking (OSS), an operant task that uses varied sensory stimuli as a reinforcer. We found that mGluR5 KO mice had significantly reduced OSS responding relative to WT mice, while Het mice displayed a paradoxical increase in OSS responding. Neither KO nor Het mice exhibited altered operant responding for food as a reinforcer. Further, we assessed mGluR5 KO, Het and WT mice across a battery of cocaine locomotor, place preference and anxiety related tests. Although KO mice showed expected differences in some locomotor and anxiety measures, Het mice either exhibited no phenotype or an intermediate one. In total, these data demonstrate a key role for mGluR5 in OSS, indicating an important role for this receptor in reinforcement-based behavior.
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