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Grimm JW, Sauter F, MacDougall D, Spaulding E, Stensgaard K, Hardy M, Griffin K, Marx R. The mGlu2/3 agonist LY379268 reduces sucrose taking, seeking, and motivation in male and female rats. Behav Pharmacol 2023; 34:340-349. [PMID: 37462142 PMCID: PMC10527415 DOI: 10.1097/fbp.0000000000000740] [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] [Indexed: 08/03/2023]
Abstract
OBJECTIVES The mGlu2/3 receptor agonist LY379268 reduces sucrose-seeking, but not sucrose-taking, in male rats. This study explored the generality of this effect across the sexes. In addition, the effect of the drug on motivation to receive sucrose was assessed. METHODS Adult male and female Long-Evans rats ( N = 91) were challenged with LY379268 in three experiments: (1) a fixed ratio (FR) schedule of reinforcement (taking), (2) extinction of responding previously reinforced on the FR (seeking) or (3) responding reinforced on a progressive ratio (PR) schedule of reinforcement (motivation). For each experiment, rats first responded to 10% liquid sucrose on an FR in 10 daily 2-h sessions. For the PR study, this was followed by training on a PR for 7 daily 3-h sessions. Rats were then challenged in a counterbalanced order with LY379268 (0, 1.5, 3 and 6 mg/kg; IP; 30-min pretreatment) on test days, followed by either three reacquisition days of FR (experiments 1 and 2) or PR (experiment 3) responding. RESULTS Female rats responded more to sucrose on the FR and PR. LY379268 reduced responding in all three experiments. LY379268 challenge to sucrose taking on the FR produced an inverted U-shaped function while extinction responding and responding for sucrose on the PR were decreased dose-dependently, with PR responding insensitive to the 1.5 mg/kg dose. There were no sex-dependent effects of the drug on sucrose-directed responding. CONCLUSIONS The sucrose anti-taking, -seeking, and -motivation effects of LY379268 across male and female rats support further evaluation of glutamate modulation as an antiaddiction pharmacotherapy.
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Affiliation(s)
- Jeffrey William Grimm
- Department of Psychology and Program in Behavioral Neuroscience, Western Washington University, Bellingham, Washington, USA
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Shipman ML, Corbit LH. Diet-induced deficits in goal-directed control are rescued by agonism of group II metabotropic glutamate receptors in the dorsomedial striatum. Transl Psychiatry 2022; 12:42. [PMID: 35091538 PMCID: PMC8799694 DOI: 10.1038/s41398-022-01807-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 01/06/2022] [Accepted: 01/12/2022] [Indexed: 11/09/2022] Open
Abstract
Many overweight or obese people struggle to sustain the behavioural changes necessary to achieve and maintain weight loss. In rodents, obesogenic diet can disrupt goal-directed control of responding for food reinforcers, which may indicate that diet can disrupt brain regions associated with behavioural control. We investigated a potential glutamatergic mechanism to return goal-directed control to rats who had been given an obesogenic diet prior to operant training. We found that an obesogenic diet reduced goal-directed control and that systemic injection of LY379268, a Group II metabotropic glutamate receptor (mGluR2/3) agonist, returned goal-directed responding in these rats. Further, we found that direct infusion of LY379268 into the dorsomedial striatum, a region associated with goal-directed control, also restored goal-directed responding in the obesogenic-diet group. This indicates that one mechanism through which obesogenic diet disrupts goal-directed control is glutamatergic, and infusion of a mGluR2/3 agonist into the DMS is sufficient to ameliorate deficits in goal-directed control.
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Affiliation(s)
- Megan L Shipman
- University of Toronto Department of Psychology, 100 St. George Street, Toronto, ON, M5S 3G3, Canada
| | - Laura H Corbit
- University of Toronto Department of Psychology, 100 St. George Street, Toronto, ON, M5S 3G3, Canada.
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The mGluR2/3 agonist pomaglumetad methionil normalizes aberrant dopamine neuron activity via action in the ventral hippocampus. Neuropsychopharmacology 2020; 45:2106-2113. [PMID: 32663839 PMCID: PMC7547679 DOI: 10.1038/s41386-020-0764-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 05/27/2020] [Accepted: 07/08/2020] [Indexed: 11/09/2022]
Abstract
The group 2 metabotropic glutamate receptor (mGluR2/3) agonist, pomaglumetad methionil (POM), showed promise as a novel antipsychotic in preclinical research but failed to show efficacy in clinical trials, though it has been suggested that it may be effective in certain patient populations. Although previous studies have shown that mGluR2/3 agonists have no effect on dopamine (DA) in wild type rats, we used the methylzoxymethanol acetate (MAM) model to determine whether POM may indirectly normalize DA neuron activity in a model representative of the hyperdopaminergic state thought to underlie psychosis, compared to SAL rats, using in vivo, anesthetized, electrophysiological recordings. POM dose-dependently reduced the number of spontaneously active DA neurons in the VTA of MAM rats to control levels without affecting DA firing in SAL rats, which persisted following 14d repeated treatment with POM. In female MAM rats, POM significantly reduced DA neuron population activity only during proestrous and estrous stages. MAM rats also demonstrated dose-dependent improvement in novel object recognition following acute POM, which was not observed in SAL rats. Similar to the MAM rats, DA neuron population activity was increased in a hippocampal-dependent manner following acute restraint stress. Administration of POM prior to 2 h restraint stress prevented the restraint-induced increase in DA neuron population activity, and this effect was blocked by pretreatment with an mGluR2/3 antagonist. Thus, the ability of POM to reduce the hyperdopaminergic activity in both MAM rats and in wild type rats following restraint stress suggests that it can indirectly regulate DA neuron activity, which may underlie its potential therapeutic effects.
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Hankosky ER, Westbrook SR, Haake RM, Marinelli M, Gulley JM. Reduced sensitivity to reinforcement in adolescent compared to adult Sprague-Dawley rats of both sexes. Psychopharmacology (Berl) 2018; 235:861-871. [PMID: 29197983 PMCID: PMC5963930 DOI: 10.1007/s00213-017-4804-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 11/27/2017] [Indexed: 10/18/2022]
Abstract
RATIONALE Adolescence is a period of considerable development of brain and behavior and is the time during which most drug use is initiated. OBJECTIVE Age-dependent differences in motivated behaviors may be one of the factors that contribute to heightened vulnerability to developing substance use disorders, so we sought to compare age differences in methamphetamine (METH) and saccharin seeking. METHODS Beginning during adolescence or adulthood, male and female Sprague-Dawley rats were trained to self-administer 0.1% saccharin (via liquid dipper cup) or intravenous METH at one of three doses (0.02, 0.05, 0.08 mg/kg/inf) under increasing fixed ratio schedules of reinforcement. Subsequently, responding for METH (0.02, 0.05, 0.08, or 0.1 mg/kg/inf) under progressive ratio response requirements was assessed in rats that acquired METH self-administration at the highest dose (0.08 mg/kg/inf). RESULTS We found that adult-onset rats acquired METH self-administration more readily and exhibited higher motivation compared to adolescent-onset rats, although there were no differences in METH intake during acquisition. Adult rats also acquired saccharin self-administration more readily, but in contrast to METH, there were age and sex differences in saccharin intake driven by high levels of responding in adult females. CONCLUSIONS These findings challenge the prevailing notion that adolescents are hypersensitive to reward and instead raise questions about the potential role of methodological factors on which rodent studies often differ.
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Affiliation(s)
- Emily R. Hankosky
- Department of Psychology, University of Illinois, Urbana-Champaign, 603 E. Daniel St., Champaign, IL, 61820, USA
| | - Sara R. Westbrook
- Department of Psychology, University of Illinois, Urbana-Champaign, 603 E. Daniel St., Champaign, IL, 61820, USA
| | - Rachel M. Haake
- Department of Psychology, University of Illinois, Urbana-Champaign, 603 E. Daniel St., Champaign, IL, 61820, USA
| | - Michela Marinelli
- College of Pharmacy, University of Texas at Austin, 107 W. Dean Keeton Street Stop C0800, Austin, TX, 78712
| | - Joshua M. Gulley
- Department of Psychology, University of Illinois, Urbana-Champaign, 603 E. Daniel St., Champaign, IL, 61820, USA,Neuroscience Program, University of Illinois, Urbana-Champaign, 505 S. Goodwin Avenue, Urbana, IL, 61801, USA
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Gutiérrez-Martos M, Girard B, Mendonça-Netto S, Perroy J, Valjent E, Maldonado R, Martin M. Cafeteria diet induces neuroplastic modifications in the nucleus accumbens mediated by microglia activation. Addict Biol 2018; 23:735-749. [PMID: 28872733 DOI: 10.1111/adb.12541] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 06/22/2017] [Accepted: 06/28/2017] [Indexed: 12/28/2022]
Abstract
High-palatable and caloric foods are widely overconsumed due to hedonic mechanisms that prevail over caloric necessities leading to overeating and overweight. The nucleus accumbens (NAc) is a key brain area modulating the reinforcing effects of palatable foods and is crucially involved in the development of eating disorders. We describe that prolonged exposure to high-caloric chocolate cafeteria diet leads to overeating and overweight in mice. NAc functionality was altered in these mice, presenting structural plasticity modifications in medium spiny neurons, increased expression of neuroinflammatory factors and activated microglia, and abnormal responses after amphetamine-induced hyperlocomotion. Chronic inactivation of microglia normalized these neurobiological and behavioural alterations exclusively in mice exposed to cafeteria diet. Our data suggest that prolonged exposure to cafeteria diet produces neuroplastic and functional changes in the NAc that can modify feeding behaviour. Microglia activation and neuroinflammation play an important role in the development of these neurobiological alterations.
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Affiliation(s)
- Miriam Gutiérrez-Martos
- Laboratory of Neuropharmacology (DCEXS); Parc de Recerca Biomèdica de Barcelona/Universitat Pompeu Fabra (PRBB/UPF); Spain
| | - Benoit Girard
- Pathophysiology of Synaptic Transmission Laboratory; Institut de Génomique Fonctionnelle; France
| | - Sueli Mendonça-Netto
- Laboratory of Neuropharmacology (DCEXS); Parc de Recerca Biomèdica de Barcelona/Universitat Pompeu Fabra (PRBB/UPF); Spain
| | - Julie Perroy
- Pathophysiology of Synaptic Transmission Laboratory; Institut de Génomique Fonctionnelle; France
| | - Emmanuel Valjent
- Inserm U1191, CNRS UMR5203, Laboratory of Neural Circuit and Signal Transduction; University Montpellier; France
| | - Rafael Maldonado
- Laboratory of Neuropharmacology (DCEXS); Parc de Recerca Biomèdica de Barcelona/Universitat Pompeu Fabra (PRBB/UPF); Spain
- IMIM (Hospital del Mar Medical Research Institute); Barcelona Spain
| | - Miquel Martin
- Laboratory of Neuropharmacology (DCEXS); Parc de Recerca Biomèdica de Barcelona/Universitat Pompeu Fabra (PRBB/UPF); Spain
- IMIM (Hospital del Mar Medical Research Institute); Barcelona Spain
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Shin CB, Templeton TJ, Chiu AS, Kim J, Gable ES, Vieira PA, Kippin TE, Szumlinski KK. Endogenous glutamate within the prelimbic and infralimbic cortices regulates the incubation of cocaine-seeking in rats. Neuropharmacology 2017; 128:293-300. [PMID: 29061508 DOI: 10.1016/j.neuropharm.2017.10.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 10/05/2017] [Accepted: 10/19/2017] [Indexed: 12/30/2022]
Abstract
The incubation of cue-reinforced cocaine-seeking coincides with increased extracellular glutamate within the ventromedial prefrontal cortex (vmPFC). The vmPFC is comprised of two subregions that oppositely regulate drug-seeking, with infralimbic (IL) activity inhibiting, and prelimibic (PL) activity facilitating, drug-seeking. Thus, we hypothesized that increasing and decreasing endogenous glutamate within the IL would attenuate and potentiate, respectively, cue-reinforced drug-seeking behavior, with the converse effects observed upon manipulations of endogenous glutamate within the PL. Male Sprague-Dawley rats were trained to self-administer cocaine (0.25 mg/infusion; 6 h/day X 10 days), the delivery of which was signaled by a tone-light cue. Rats were then subdivided into 3 or 30 day withdrawal groups. For testing, rats were microinjected with vehicle, 20 mM of the mGlu2/3 agonist LY379268 (to lower endogenous glutamate), or 300 μM of the excitatory amino acid transporter inhibitor threo-β-benzyloxyaspartate (TBOA; to raise endogenous glutamate) into either the IL or PL (0.5 μl/side) and then given a 30-min test for cue-reinforced drug-seeking. Vehicle-infused rats exhibited incubated responding on the cocaine-associated lever. Neither LY379268 nor TBOA altered behavior at 3 days withdrawal, indicating that glutamate within neither subregion regulates cue-reinforced drug-seeking during early withdrawal. At 30 days withdrawal, intra-PL LY379268 microinjection significantly decreased drug-seeking behavior, while the effect was more modest when infused intra-IL. Interestingly, intra-IL TBOA attenuated incubated drug-seeking during protracted withdrawal, but did not affect behavior when infused intra-PL. These results argue that glutamate release within the PL in response to drug-seeking likely drives the manifestation of incubated cocaine-seeking during protracted withdrawal.
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Affiliation(s)
- Christina B Shin
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Taylor J Templeton
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Alvin S Chiu
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Jennifer Kim
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Ellen S Gable
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Philip A Vieira
- Center for Collaborative Biotechnology, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Tod E Kippin
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA; Department of Molecular, Cellular and Developmental Biology, Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA; Center for Collaborative Biotechnology, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA
| | - Karen K Szumlinski
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA; Department of Molecular, Cellular and Developmental Biology, Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA 93106-9660, USA.
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Antagonism of mGlu2/3 receptors in the nucleus accumbens prevents oxytocin from reducing cued methamphetamine seeking in male and female rats. Pharmacol Biochem Behav 2017; 161:13-21. [PMID: 28870523 DOI: 10.1016/j.pbb.2017.08.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 08/28/2017] [Accepted: 08/30/2017] [Indexed: 11/23/2022]
Abstract
Methamphetamine (meth) addiction is a prevalent health concern worldwide, yet remains without approved pharmacological treatments. Preclinical evidence suggests that oxytocin may decrease relapse, but the neuronal underpinnings driving this effect remain unknown. Here we investigate whether oxytocin's effect is dependent on presynaptic glutamatergic regulation in the nucleus accumbens core (NAcore) by blocking metabotropic glutamate receptors 2/3 (mGluR2/3). Male and female Sprague-Dawley rats self-administered meth or sucrose on an escalating fixed ratio, followed by extinction and cue-induced reinstatement sessions. Reinstatement tests consisted of systemic (Experiment 1) or site-specific application of the drugs into the NAcore (Experiments 2 and 3). Before reinstatement sessions, rats received LY341495, an mGluR2/3 antagonist, or its vehicle followed by a second infusion/injection of oxytocin or saline. As expected, both males and females reinstated lever pressing to meth associated cues, and LY341495 alone did not impact this behavior. Oxytocin injected systemically or infused into the NAcore decreased cued meth seeking. Importantly, combined LY341495 and oxytocin administration restored meth cued reinstatement. Interestingly, neither oxytocin nor LY341495 impacted sucrose-cued reinstatement, suggesting distinct mechanisms between meth and sucrose. These findings were consistent between males and females. Overall, we report that oxytocin reduced responding to meth-associated cues and blocking presynaptic mGluR2/3 reversed this effect. Further, oxytocin's effects were specific to meth cues as NAcore oxytocin was without an effect on sucrose cued reinstatement. Results are discussed in terms of oxytocin receptor localization in the NAcore and modulation of presynaptic regulation of glutamate in response to drug associated cues.
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