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Cognitive impairment and gene expression alterations in a rodent model of binge eating disorder. Physiol Behav 2017; 180:78-90. [PMID: 28821448 DOI: 10.1016/j.physbeh.2017.08.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 08/10/2017] [Accepted: 08/11/2017] [Indexed: 12/21/2022]
Abstract
Binge eating disorder (BED) is defined as recurrent, distressing over-consumption of palatable food (PF) in a short time period. Clinical studies suggest that individuals with BED may have impairments in cognitive processes, executive functioning, impulse control, and decision-making, which may play a role in sustaining binge eating behavior. These clinical reports, however, are limited and often conflicting. In this study, we used a limited access rat model of binge-like behavior in order to further explore the effects of binge eating on cognition. In binge eating prone (BEP) rats, we found novel object recognition (NOR) as well as Barnes maze reversal learning (BM-RL) deficits. Aberrant gene expression of brain derived neurotrophic factor (Bdnf) and tropomyosin receptor kinase B (TrkB) in the hippocampus (HPC)-prefrontal cortex (PFC) network was observed in BEP rats. Additionally, the NOR deficits were correlated with reductions in the expression of TrkB and insulin receptor (Ir) in the CA3 region of the hippocampus. Furthermore, up-regulation of serotonin-2C (5-HT2C) receptors in the orbitoprefrontal cortex (OFC) was associated with BM-RL deficit. Finally, in the nucleus accumbens (NAc), we found decreased dopamine receptor 2 (Drd2) expression among BEP rats. Taken together, these data suggest that binge eating vegetable shortening may induce contextual and reversal learning deficits which may be mediated, at least in part, by the altered expression of genes in the CA3-OFC-NAc neural network.
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Netrakanti PR, Cooper BH, Dere E, Poggi G, Winkler D, Brose N, Ehrenreich H. Fast cerebellar reflex circuitry requires synaptic vesicle priming by munc13-3. THE CEREBELLUM 2016; 14:264-83. [PMID: 25617111 PMCID: PMC4441738 DOI: 10.1007/s12311-015-0645-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Munc13-3 is a member of the Munc13 family of synaptic vesicle priming proteins and mainly expressed in cerebellar neurons. Munc13-3 null mutant (Munc13-3−/−) mice show decreased synaptic release probability at parallel fiber to Purkinje cell, granule cell to Golgi cell, and granule cell to basket cell synapses and exhibit a motor learning deficit at highest rotarod speeds. Since we detected Munc13-3 immunoreactivity in the dentate gyrus, as reported here for the first time, and current studies indicated a crucial role for the cerebellum in hippocampus-dependent spatial memory, we systematically investigated Munc13-3−/− mice versus wild-type littermates of both genders with respect to hippocampus-related cognition and a range of basic behaviors, including tests for anxiety, sensory functions, motor performance and balance, sensorimotor gating, social interaction and competence, and repetitive and compulsive behaviors. Neither basic behavior nor hippocampus-dependent cognitive performance, evaluated by Morris water maze, hole board working and reference memory, IntelliCage-based place learning including multiple reversals, and fear conditioning, showed any difference between genotypes. However, consistent with a disturbed cerebellar reflex circuitry, a reliable reduction in the acoustic startle response in both male and female Munc13-3−/− mice was found. To conclude, complete deletion of Munc13-3 leads to a robust decrease in the acoustic startle response. This readout of a fast cerebellar reflex circuitry obviously requires synaptic vesicle priming by Munc13-3 for full functionality, in contrast to other behavioral or cognitive features, where a nearly perfect compensation of Munc13-3 deficiency by related synaptic proteins has to be assumed.
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Affiliation(s)
- Pallavi Rao Netrakanti
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany
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Di Giovanni G, De Deurwaerdère P. New therapeutic opportunities for 5-HT2C receptor ligands in neuropsychiatric disorders. Pharmacol Ther 2015; 157:125-62. [PMID: 26617215 DOI: 10.1016/j.pharmthera.2015.11.009] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The 5-HT2C receptor (R) displays a widespread distribution in the CNS and is involved in the action of 5-HT in all brain areas. Knowledge of its functional role in the CNS pathophysiology has been impaired for many years due to the lack of drugs capable of discriminating among 5-HT2R subtypes, and to a lesser extent to the 5-HT1B, 5-HT5, 5-HT6 and 5-HT7Rs. The situation has changed since the mid-90s due to the increased availability of new and selective synthesized compounds, the creation of 5-HT2C knock out mice, and the progress made in molecular biology. Many pharmacological classes of drugs including antipsychotics, antidepressants and anxiolytics display affinities toward 5-HT2CRs and new 5-HT2C ligands have been developed for various neuropsychiatric disorders. The 5-HT2CR is presumed to mediate tonic/constitutive and phasic controls on the activity of different central neurobiological networks. Preclinical data illustrate this complexity to a point that pharmaceutical companies developed either agonists or antagonists for the same disease. In order to better comprehend this complexity, this review will briefly describe the molecular pharmacology of 5-HT2CRs, as well as their cellular impacts in general, before addressing its central distribution in the mammalian brain. Thereafter, we review the preclinical efficacy of 5-HT2C ligands in numerous behavioral tests modeling human diseases, highlighting the multiple and competing actions of the 5-HT2CRs in neurobiological networks and monoaminergic systems. Notably, we will focus this evidence in the context of the physiopathology of psychiatric and neurological disorders including Parkinson's disease, levodopa-induced dyskinesia, and epilepsy.
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Affiliation(s)
- Giuseppe Di Giovanni
- Department of Physiology & Biochemistry, Faculty of Medicine and Surgery, University of Malta; Neuroscience Division, School of Biosciences, Cardiff University, Cardiff, UK.
| | - Philippe De Deurwaerdère
- Centre National de la Recherche Scientifique (Unité Mixte de Recherche 5293) 33076 Bordeaux Cedex, France.
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Grados M, Prazak M, Saif A, Halls A. A review of animal models of obsessive-compulsive disorder: a focus on developmental, immune, endocrine and behavioral models. Expert Opin Drug Discov 2015; 11:27-43. [PMID: 26558411 DOI: 10.1517/17460441.2016.1103225] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
INTRODUCTION Obsessive-compulsive disorder (OCD) is a neuropsychiatric condition characterized by intrusive thoughts (obsessions) and/or repetitive behaviors (compulsions). Several models of OCD exist, many which employ behaviors such as over-grooming or hoarding as correlates for compulsive behaviors - often using a response to serotonergic agents as evidence for their validity. Recent discoveries in the genetics of OCD and the identification of aberrancies of glutamatergic, hormonal, and immune pathways in the OCD phenotype highlight a need to review existing of animal models of OCD. The focus of attention to these pathways may lead to possible new targets for drug discovery. AREAS COVERED In this review, the authors describe frameworks for animal models in OCD conceptualized as either biological (e.g., developmental, genetic, and endocrine pathways), or behavioral (e.g., repetitive grooming, and stereotypies). In addition, the authors give special attention to the emerging role of glutamate in OCD. EXPERT OPINION While many animal models for OCD demonstrate pathologic repetitive behavior phenotypes, which are relieved by serotoninergic agents, animal models based on reversal learning, perseverative responding, and neurodevelopmental mechanisms represent robust new paradigms. Glutamatergic influences in these new animal models suggest that drug discovery using neuroprotective approaches may represent a new stage for pharmacologic developments in OCD.
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Affiliation(s)
- Marco Grados
- a Department of Psychiatry , Johns Hopkins University , 1800 Orleans St. - 12th floor, Baltimore , MD 21287 , USA
| | - Michael Prazak
- b Department of Medicine , Dow University of Health Sciences , Karachi , Pakistan
| | - Aneeqa Saif
- c Department of Psychology Grand Forks , University of North Dakota , ND , USA
| | - Andrew Halls
- a Department of Psychiatry , Johns Hopkins University , 1800 Orleans St. - 12th floor, Baltimore , MD 21287 , USA
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Alsiö J, Nilsson SRO, Gastambide F, Wang RAH, Dam SA, Mar AC, Tricklebank M, Robbins TW. The role of 5-HT2C receptors in touchscreen visual reversal learning in the rat: a cross-site study. Psychopharmacology (Berl) 2015; 232:4017-31. [PMID: 26007324 PMCID: PMC4600472 DOI: 10.1007/s00213-015-3963-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 05/07/2015] [Indexed: 02/02/2023]
Abstract
RATIONALE Reversal learning requires associative learning and executive functioning to suppress non-adaptive responding. Reversal-learning deficits are observed in e.g. schizophrenia and obsessive-compulsive disorder and implicate neural circuitry including the orbitofrontal cortex (OFC). Serotonergic function has been strongly linked to visual reversal learning in humans and experimental animals but less is known about which receptor subtypes are involved. OBJECTIVES The objectives of the study were to test the effects of systemic and intra-OFC 5-HT2C-receptor antagonism on visual reversal learning in rats and assess the psychological mechanisms underlying these effects within novel touchscreen paradigms. METHODS In experiments 1-2, we used a novel 3-stimulus task to investigate the effects of 5-HT2C-receptor antagonism through SB 242084 (0.1, 0.5 and 1.0 mg/kg i.p.) cross-site. Experiment 3 assessed the effects of SB 242084 in 2-choice reversal learning. In experiment 4, we validated a novel touchscreen serial visual reversal task suitable for neuropharmacological microinfusions by baclofen-/muscimol-induced OFC inactivation. In experiment 5, we tested the effect of intra-OFC SB 242084 (1.0 or 3.0 μg/side) on performance in this task. RESULTS In experiments 1-3, SB 242084 reduced early errors but increased late errors to criterion. In experiment 5, intra-OFC SB 242084 reduced early errors without increasing late errors in a reversal paradigm validated as OFC dependent (experiment 4). CONCLUSION Intra-OFC 5-HT2C-receptor antagonism decreases perseveration in novel touchscreen reversal-learning paradigms for the rat. Systemic 5-HT2C-receptor antagonism additionally impairs late learning-a robust effect observed cross-site and potentially linked to impulsivity. These conclusions are discussed in terms of neural mechanisms underlying reversal learning and their relevance to psychiatric disorders.
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Affiliation(s)
- J Alsiö
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK.
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK.
- Department of Neuroscience, Unit of Functional Neurobiology, University of Uppsala, Uppsala, SE-75124, Sweden.
| | - S R O Nilsson
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK
| | - F Gastambide
- Lilly Centre for Cognitive Neuroscience, Eli Lilly & Co. Ltd., Erl Wood Manor, Windlesham, GU20 6PH, UK
| | - R A H Wang
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK
| | - S A Dam
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK
| | - A C Mar
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK
| | - M Tricklebank
- Lilly Centre for Cognitive Neuroscience, Eli Lilly & Co. Ltd., Erl Wood Manor, Windlesham, GU20 6PH, UK
| | - T W Robbins
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK
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Nilsson SRO, Alsiö J, Somerville EM, Clifton PG. The rat's not for turning: Dissociating the psychological components of cognitive inflexibility. Neurosci Biobehav Rev 2015; 56:1-14. [PMID: 26112128 PMCID: PMC4726702 DOI: 10.1016/j.neubiorev.2015.06.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 05/13/2015] [Accepted: 06/10/2015] [Indexed: 11/23/2022]
Abstract
Non-rewarded or irrelevant prior associations are important for flexible responding. Associations of reward and non-reward in reversal learning are neurally dissociable. Disruption of prior irrelevant or rewarded associations cause pathological deficits. Experimental paradigms of cognitive flexibility can be improved to aid translation.
Executive function is commonly assessed by assays of cognitive flexibility such as reversal learning and attentional set-shifting. Disrupted performance in these assays, apparent in many neuropsychiatric disorders, is frequently interpreted as inability to overcome prior associations with reward. However, non-rewarded or irrelevant associations may be of considerable importance in both discrimination learning and cognitive flexibility. Non-rewarded associations can have greater influence on choice behaviour than rewarded associations in discrimination learning. Pathology-related deficits in cognitive flexibility can produce selective disruptions to both the processing of irrelevant associations and associations with reward. Genetic and pharmacological animal models demonstrate that modulation of reversal learning may result from alterations in either rewarded or non-rewarded associations. Successful performance in assays of cognitive flexibility can therefore depend on a combination of rewarded, non-rewarded, and irrelevant associations derived from previous learning, accounting for some inconsistencies observed in the literature. Taking this combination into account may increase the validity of animal models and may also reveal pathology-specific differences in problem solving and executive function.
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Affiliation(s)
- Simon R O Nilsson
- Department of Psychology, University of Cambridge, Cambridge CB2 3EB, UK; MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK..
| | - Johan Alsiö
- Department of Psychology, University of Cambridge, Cambridge CB2 3EB, UK; MRC and Wellcome Trust Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK.; Department of Neuroscience, Unit of Functional Neurobiology, University of Uppsala, SE-75124 Uppsala, Sweden
| | | | - Peter G Clifton
- School of Psychology, University of Sussex, Brighton BN1 9QH, UK
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