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Lee KM, Coelho MA, Class MA, Sern KR, Bocz MD, Szumlinski KK. mGlu5 Receptor Blockade Within the Nucleus Accumbens Shell Reduces Behavioral Indices of Alcohol Withdrawal-Induced Anxiety in Mice. Front Pharmacol 2018; 9:1306. [PMID: 30483137 PMCID: PMC6243038 DOI: 10.3389/fphar.2018.01306] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 10/25/2018] [Indexed: 11/13/2022] Open
Abstract
Withdrawal from binge-drinking increases negative affect, coinciding with increased expression of the metabotropic glutamate receptor 5 (mGlu5) within the shell of the nucleus accumbens (AcbSh). Supporting a causal-effect relationship, systemic treatment with the mGlu5 receptor antagonist MTEP [3-((2-Methyl-4-thiazolyl)ethynyl)pyridine] is anxiolytic in binge-drinking adult and adolescent mice. Here, we employed neuropharmacological approaches to examine the functional relevance of AcbSh mGlu5 for behavioral indices of alcohol withdrawal-induced hyper-anxiety. Adult (PND 56) and adolescent (PND 28) male C57BL/6J mice consumed alcohol under modified Drinking-in-the-Dark procedures (10, 20, and 40% alcohol v/v) for 14 days. At an alcohol withdrawal time-point when mice manifest robust behavioral signs of hyper-anxiety (1 and 28 days withdrawal for adults and adolescents, respectively), mice were infused intra-AcbSh with 0, 1 or 10 μg MTEP and then affect was assayed in the light-dark shuttle box, marble-burying and forced swim tests. Brain tissue was collected to evaluate changes in Egr1 (early growth response protein 1) induction to index AcbSh neuronal activity. As expected, alcohol-experienced mice exhibited behavioral signs of hyper-emotionality. The anxiolytic effects of intra-AchSh MTEP were modest, but dose-dependent, and varied with age of drinking-onset. In adult-onset mice, only the 1 μg MTEP dose reduced withdrawal-induced hyper-anxiety, whereas only the higher dose was effective in adolescent-onset animals. MTEP reduced Egr1 expression within the AcbSh, irrespective of alcohol drinking history or age of drinking-onset. However, only the high MTEP dose reduced Egr1 expression in adolescent-onset binging mice. These results implicate AcbSh mGlu5 in modulating alcohol withdrawal-induced negative affect and suggest age differences in the neurobiological effects of alcohol withdrawal and behavioral responsiveness to mGlu5 blockade within the AcbSh.
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Affiliation(s)
- Kaziya M. Lee
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Michal A. Coelho
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - MacKayla A. Class
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Kimberly R. Sern
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Mark D. Bocz
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Karen K. Szumlinski
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
- Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, United States
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Lee KM, Coelho MA, Sern KR, Class MA, Bocz MD, Szumlinski KK. Anxiolytic effects of buspirone and MTEP in the Porsolt Forced Swim Test. Chronic Stress (Thousand Oaks) 2017; 1. [PMID: 28884167 PMCID: PMC5584874 DOI: 10.1177/2470547017712985] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Traditionally, a reduction in floating behavior or immobility in the Porsolt forced swim
test is employed as a predictor of anti-depressant efficacy. However, over the past
several years, our studies of alcohol withdrawal-induced negative affect consistently
indicate the coincidence of increased anxiety-related behaviors on various behavioral
tests with reduced immobility in the forced swim test. Further, this
behavioral profile correlates with increased mGlu5 protein expression within limbic brain
regions. As the role for mGlu5 in anxiety is well established, we hypothesized that the
reduced immobility exhibited by alcohol-withdrawn mice when tested in the forced swim test
might reflect anxiety, possibly a hyper-reactivity to the acute swim stressor. Herein, we
evaluated whether or not the decreased forced swim test immobility during alcohol
withdrawal responds to systemic treatment with a behaviorally effective dose of the
prototypical anxiolytic, buspirone (5 mg/kg). We also determined the functional relevance
of the withdrawal-induced increase in mGlu5 expression for forced swim test behavior by
comparing the effects of buspirone to a behaviorally effective dose of the mGlu5 negative
allosteric modulator MTEP (3 mg/kg). Adult male C57BL/6J mice were subjected to a 14-day,
multi-bottle, binge-drinking protocol that elicits hyper-anxiety and increases
glutamate-related protein expression during early withdrawal. Control animals received
only water. At 24-h withdrawal, animals from each drinking condition were subdivided into
groups and treated with an intraperitoneal injection of buspirone, MTEP, or vehicle,
30 min prior to the forced swim test. Drug effects on general locomotor activity were also
assessed. As we reported previously, alcohol-withdrawn animals exhibited significantly
reduced immobility in the forced swim test compared to water controls. Both buspirone and
MTEP significantly increased immobility in alcohol-withdrawn animals, with a modest
increase also seen in water controls. No significant group differences were observed for
locomotor activity, indicating that neither anxiolytic was sedating. These results provide
predictive validity for increased swimming/reduced immobility in the forced swim test as a
model of anxiety and provide novel evidence in favor of mGlu5 inhibition as an effective
therapeutic strategy for treating hyper-anxiety during alcohol withdrawal.
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Affiliation(s)
- Kaziya M Lee
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, USA, 93106-9660
| | - Michal A Coelho
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, USA, 93106-9660
| | - Kimberly R Sern
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, USA, 93106-9660
| | - MacKayla A Class
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, USA, 93106-9660
| | - Mark D Bocz
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, USA, 93106-9660
| | - Karen K Szumlinski
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, USA, 93106-9660.,Department of Molecular, Cellular and Developmental Biology and the Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA, USA, 93106-9625
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