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D'Agostino G, Lyons D, Cristiano C, Lettieri M, Olarte-Sanchez C, Burke LK, Greenwald-Yarnell M, Cansell C, Doslikova B, Georgescu T, Martinez de Morentin PB, Myers MG, Rochford JJ, Heisler LK. Nucleus of the Solitary Tract Serotonin 5-HT 2C Receptors Modulate Food Intake. Cell Metab 2018; 28:619-630.e5. [PMID: 30146485 PMCID: PMC6371983 DOI: 10.1016/j.cmet.2018.07.017] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 02/12/2018] [Accepted: 07/27/2018] [Indexed: 12/14/2022]
Abstract
To meet the challenge to human health posed by obesity, a better understanding of the regulation of feeding is essential. Medications targeting 5-hydroxytryptamine (5-HT; serotonin) 2C receptors (htr2c; 5-HT2CR) improve obesity. Here we probed the functional significance of 5-HT2CRs specifically within the brainstem nucleus of the solitary tract (5-HT2CRNTS) in feeding behavior. Selective activation of 5-HT2CRNTS decreased feeding and was sufficient to mediate acute food intake reductions elicited by the 5-HT2CR agonist obesity medication lorcaserin. Similar to pro-opiomelanocortin neurons expressed within the hypothalamic arcuate nucleus (POMCARC), a subset of POMCNTS neurons co-expressed 5-HT2CRs and were activated by 5-HT2CR agonists. Knockdown of POMCNTS prevented the acute appetite-suppressive effect of lorcaserin, whereas POMCARC knockdown prevented the full anorectic effect. These data identify 5-HT2CRNTS as a sufficient subpopulation of 5-HT2CRs in reducing food intake when activated and reveal that 5-HT2CR agonist obesity medications require POMC within the NTS and ARC to reduce food intake.
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Affiliation(s)
- Giuseppe D'Agostino
- Rowett Institute, University of Aberdeen, Aberdeen, UK; Department of Pharmacology, University of Cambridge, Cambridge, UK.
| | - David Lyons
- Rowett Institute, University of Aberdeen, Aberdeen, UK
| | | | | | | | - Luke K Burke
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Megan Greenwald-Yarnell
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | | | | | | | | | - Martin G Myers
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Lora K Heisler
- Rowett Institute, University of Aberdeen, Aberdeen, UK; Department of Pharmacology, University of Cambridge, Cambridge, UK.
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Bezzina G, Body S, Cheung THC, Hampson CL, Bradshaw CM, Glennon JC, Szabadi E. Evidence for a role of 5-HT2C receptors in the motor aspects of performance, but not the efficacy of food reinforcers, in a progressive ratio schedule. Psychopharmacology (Berl) 2015; 232:699-711. [PMID: 25134499 DOI: 10.1007/s00213-014-3700-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 07/28/2014] [Indexed: 12/25/2022]
Abstract
RATIONALE 5-Hydroxytryptamine2C (5-HT2C) receptor agonists reduce the breakpoint in progressive ratio schedules of reinforcement, an effect that has been attributed to a decrease of the efficacy of positive reinforcers. However, a reduction of the breakpoint may also reflect motor impairment. Mathematical models can help to differentiate between these processes. OBJECTIVE The effects of the 5-HT2C receptor agonist Ro-600175 ((αS)-6-chloro-5-fluoro-α-methyl-1H-indole-1-ethanamine) and the non-selective 5-HT receptor agonist 1-(m-chlorophenyl)piperazine (mCPP) on rats' performance on a progressive ratio schedule maintained by food pellet reinforcers were assessed using a model derived from Killeen's Behav Brain Sci 17:105-172, 1994 general theory of schedule-controlled behaviour, 'mathematical principles of reinforcement'. METHOD Rats were trained under the progressive ratio schedule, and running and overall response rates in successive ratios were analysed using the model. The effects of the agonists on estimates of the model's parameters, and the sensitivity of these effects to selective antagonists, were examined. RESULTS Ro-600175 and mCPP reduced the breakpoint. Neither agonist significantly affected a (the parameter expressing incentive value), but both agonists increased δ (the parameter expressing minimum response time). The effects of both agonists could be attenuated by the selective 5-HT2C receptor antagonist SB-242084 (6-chloro-5-methyl-N-{6-[(2-methylpyridin-3-yl)oxy]pyridin-3-yl}indoline-1-carboxamide). The effect of mCPP was not altered by isamoltane, a selective 5-HT1B receptor antagonist, or MDL-100907 ((±)2,3-dimethoxyphenyl-1-(2-(4-piperidine)methanol)), a selective 5-HT2A receptor antagonist. CONCLUSIONS The results are consistent with the hypothesis that the effect of the 5-HT2C receptor agonists on progressive ratio schedule performance is mediated by an impairment of motor capacity rather than by a reduction of the incentive value of the food reinforcer.
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Affiliation(s)
- G Bezzina
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Medical School, Nottingham, NG7 2UH, UK
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Wheeler DS, Wan S, Miller A, Angeli N, Adileh B, Hu W, Holland PC. Role of lateral hypothalamus in two aspects of attention in associative learning. Eur J Neurosci 2014; 40:2359-77. [PMID: 24750426 PMCID: PMC4641454 DOI: 10.1111/ejn.12592] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 03/12/2014] [Accepted: 03/17/2014] [Indexed: 11/28/2022]
Abstract
Orexin (hypocretin) and melanin-concentrating hormone (MCH) neurons are unique to the lateral hypothalamic (LH) region, but project throughout the brain. These cell groups have been implicated in a variety of functions, including reward learning, responses to stimulants, and the modulation of attention, arousal and the sleep/wakefulness cycle. Here, we examined roles for LH in two aspects of attention in associative learning shown previously to depend on intact function in major targets of orexin and MCH neurons. In experiments 1 and 2, unilateral orexin-saporin lesions of LH impaired the acquisition of conditioned orienting responses (ORs) and bilaterally suppressed FOS expression in the amygdala central nucleus (CeA) normally observed in response to food cues that provoke conditioned ORs. Those cues also induced greater FOS expression than control cues in LH orexin neurons, but not in MCH neurons. In experiment 3, unilateral orexin-saporin lesions of LH eliminated the cue associability enhancements normally produced by the surprising omission of an expected event. The magnitude of that impairment was positively correlated with the amount of LH damage and with the loss of orexin neurons in particular, but not with the loss of MCH neurons. We suggest that the effects of the LH orexin-saporin lesions were mediated by their effect on information processing in the CeA, known to be critical to both behavioral phenomena examined here. The results imply close relations between LH motivational amplification functions and attention, and may inform our understanding of disorders in which motivational and attentional impairments co-occur.
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Affiliation(s)
- Daniel S Wheeler
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, 21218, USA
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Valencia-Torres L, Bradshaw CM, Bouzas A, Hong E, Orduña V. Effect of streptozotocin-induced diabetes on performance on a progressive ratio schedule. Psychopharmacology (Berl) 2014; 231:2375-84. [PMID: 24402135 DOI: 10.1007/s00213-013-3401-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 12/02/2013] [Indexed: 12/29/2022]
Abstract
RATIONALE It has been suggested that streptozotocin (STZ)-induced diabetes causes a motivational deficit in rodents. However, some of the evidence adduced in support of this suggestion may be interpreted in terms of a motor impairment rather than a motivational deficit. OBJECTIVE This experiment examined the effect of STZ-induced diabetes on performance on a progressive ratio schedule. The data were analysed using a new model derived from Killeen's (Behav Brain Sci 17:105-172, 1994) Mathematical Principles of Reinforcement model which enables the effects of interventions on motivation or incentive value to be separated from effects on motor function. METHOD Animals were trained under a progressive ratio schedule using food-pellet reinforcement. Then they received a single intraperitoneal injection of 50 mg/kg of STZ or the vehicle. Training continued for 30 sessions after treatment. Running and overall response rates in successive ratios were analysed using the new model, and estimates of the model's parameters were compared between groups. RESULTS The parameter expressing incentive value was reduced in the group treated with STZ, whereas the parameters expressing motor capacity and post-reinforcement pausing were not affected by the treatment. Blood glucose concentration was significantly elevated in the STZ-treated group compared to the vehicle-treated group. CONCLUSIONS The results are consistent with the suggestion that STZ-induced diabetes is associated with a reduction of the incentive value of food.
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Pharmacological studies of performance on the free-operant psychophysical procedure. Behav Processes 2013; 95:71-89. [PMID: 23428704 DOI: 10.1016/j.beproc.2013.02.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Revised: 02/10/2013] [Accepted: 02/11/2013] [Indexed: 12/30/2022]
Abstract
In the free-operant psychophysical procedure (FOPP), reinforcement is provided intermittently for responding on lever A in the first half and lever B in the second half of a trial. Temporal differentiation is measured from the psychometric function (percent responding on B, %B, versus time from trial onset, t), the index of timing being T50, the value of t at %B=50. T50 is reduced by acute treatment with 5-hydroxytryptamine (5-HT1A, 5-HT2A) and dopamine (D1-like, D2-like) receptor agonists. The effects of the agonists can be reversed by the respective antagonists of these receptors. Evidence is reviewed suggesting that the effect of endogenous 5-HT is mediated by 5-HT2A receptors and the effect of endogenous dopamine by D1-like receptors. Data are presented on the effects of lesions of the prefrontal cortex and corpus striatum on the sensitivity of performance on the FOPP to D1-like and D2-like receptor agonists. Lesions of the nucleus accumbens, but not the dorsal striatum or prefrontal cortex, attenuated the effects of a D1-like receptor agonist, 6-chloro-2,3,4,5-tetrahydro-1-phenyl-1H-3-benzazepine [SKF-81297], but not a D2-like receptor agonist, quinpirole, on T50. The results indicate that a population of D1-like receptors in the ventral striatum may contribute to the control of timing performance on the FOPP.
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Olarte-Sánchez CM, Valencia-Torres L, Cassaday HJ, Bradshaw CM, Szabadi E. Effects of SKF-83566 and haloperidol on performance on progressive ratio schedules maintained by sucrose and corn oil reinforcement: quantitative analysis using a new model derived from the Mathematical Principles of Reinforcement (MPR). Psychopharmacology (Berl) 2013; 230:617-30. [PMID: 23828157 PMCID: PMC3838603 DOI: 10.1007/s00213-013-3189-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 06/11/2013] [Indexed: 01/08/2023]
Abstract
RATIONALE Mathematical models can assist the interpretation of the effects of interventions on schedule-controlled behaviour and help to differentiate between processes that may be confounded in traditional performance measures such as response rate and the breakpoint in progressive ratio (PR) schedules. OBJECTIVE The effects of a D1-like dopamine receptor antagonist, 8-bromo-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin-7-ol hydrobromide (SKF-83566), and a D2-like receptor antagonist, haloperidol, on rats' performance on PR schedules maintained by sucrose and corn oil reinforcers were assessed using a new model derived from Killeen's (Behav Brain Sci 17:105-172, 1994) Mathematical Principles of Reinforcement. METHOD Separate groups of rats were trained under a PR schedule using sucrose or corn oil reinforcers. SKF-83566 (0.015 and 0.03 mg kg(-1)) and haloperidol (0.05 and 0.1 mg kg(-1)) were administered intraperitoneally (five administrations of each treatment). Running and overall response rates in successive ratios were analysed using the new model, and estimates of the model's parameters were compared between treatments. RESULTS Haloperidol reduced a (the parameter expressing incentive value) in the case of both reinforcers, but did not affect the parameters related to response time and post-reinforcement pausing. SKF-83566 reduced a and k (the parameter expressing sensitivity of post-reinforcement pausing to the prior inter-reinforcement interval) in the case of sucrose, but did not affect any of the parameters in the case of corn oil. CONCLUSIONS The results are consistent with the hypothesis that blockade of both D1-like and D2-like receptors reduces the incentive value of sucrose, whereas the incentive value of corn oil is more sensitive to blockade of D2-like than D1-like receptors.
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Affiliation(s)
- C. M. Olarte-Sánchez
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen’s Medical Centre, Nottingham, NG7 2UH UK ,Present Address: School of Psychology, University of Cardiff, Tower Building, 70 Park Place, Cardiff, CF10 3AT UK
| | - L. Valencia-Torres
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen’s Medical Centre, Nottingham, NG7 2UH UK ,Present Address: Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD UK
| | - H. J. Cassaday
- School of Psychology, University of Nottingham, Nottingham, UK
| | - C. M. Bradshaw
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen’s Medical Centre, Nottingham, NG7 2UH UK
| | - E. Szabadi
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen’s Medical Centre, Nottingham, NG7 2UH UK
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den Boon FS, Body S, Hampson CL, Bradshaw CM, Szabadi E, de Bruin N. Effects of amisulpride and aripiprazole on progressive-ratio schedule performance: comparison with clozapine and haloperidol. J Psychopharmacol 2012; 26:1231-43. [PMID: 21969105 DOI: 10.1177/0269881111421974] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Clozapine and some other atypical antipsychotics (e.g. quetiapine, olanzapine) have been found to exert a characteristic profile of action on operant behaviour maintained by progressive-ratio schedules, as revealed by Killeen's Mathematical Principles of Reinforcement model of schedule-controlled behaviour. These drugs increase the value of a parameter that expresses the 'incentive value' of the reinforcer (a) and a parameter that is inversely related to the organism's 'motor capacity' (δ). This experiment examined the effects of two further atypical antipsychotics, aripiprazole and amisulpride, on progressive-ratio schedule performance in rats; the effects of clozapine and a conventional antipsychotic, haloperidol, were also examined. In agreement with previous findings, clozapine (4, 8 mg kg⁻¹) increased a and δ, whereas haloperidol (0.05, 0.1 mg kg⁻¹) reduced a and increased δ. Aripiprazole (3,30 mg kg⁻¹) increased δ but did not affect a. Amisulpride (5, 50 mg kg⁻¹) had a delayed and protracted effect: δ was increased 3-6 hours after treatment; a was increased 1.5 hours, and reduced 12-24 hours after treatment. Interpretation based on Killeen's model suggests that aripiprazole does not share clozapine's ability to enhance reinforcer value. Amisulpride produced a short-lived enhancement, followed by a long-lasting reduction, of reinforcer value. Both drugs impaired motor performance.
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Affiliation(s)
- F S den Boon
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Nottingham, UK
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Bradshaw CM, Killeen PR. A theory of behaviour on progressive ratio schedules, with applications in behavioural pharmacology. Psychopharmacology (Berl) 2012; 222:549-64. [PMID: 22752382 DOI: 10.1007/s00213-012-2771-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 06/03/2012] [Indexed: 10/28/2022]
Abstract
RATIONALE Mathematical principles of reinforcement (MPR) provide the theoretical basis for a family of models of schedule-controlled behaviour. A model of fixed-ratio schedule performance that was applied to behaviour on progressive ratio (PR) schedules showed systematic departures from the data. OBJECTIVE This study aims to derive a new model from MPR that will account for overall and running response rates in the component ratios of PR schedules, and their decline toward 0, the breakpoint. METHOD The role of pausing is represented in a real-time model containing four parameters: T (0) and k are the intercept and slope of the linear relation between post-reinforcement pause duration and the prior inter-reinforcer interval; a (specific activation) measures the incentive value of the reinforcer; δ (response time) sets biomechanical limits on response rate. Running rate is predicted to decrease with negative acceleration as ratio size increments, overall rate to increase and then decrease. Differences due to type of progression are explained as hysteresis in the control by reinforcement rates. Re-analysis of extant data focuses on the effects of acute treatment with antipsychotic drugs, lesions of the nucleus accumbens core, and destruction of orexinergic neurones of the lateral hypothalamus. RESULTS The new model resolves some anomalies evident in earlier analyses, and provides new insights to the results of these interventions. CONCLUSIONS Because they can render biologically relevant parameters, mathematical models can provide greater power in interpreting the effects of interventions on the processes underlying schedule-controlled behaviour than is possible for first-order data such as the breakpoint.
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Affiliation(s)
- C M Bradshaw
- Division of Psychiatry University of Nottingham B109 Medical School, University of Nottingham, Nottingham NG7 2UH, UK.
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