1
|
Costa A, Ai M, Nunn N, Culotta I, Hunter J, Boudjadja MB, Valencia-Torres L, Aviello G, Hodson DJ, Snider BM, Coskun T, Emmerson PJ, Luckman SM, D'Agostino G. Anorectic and aversive effects of GLP-1 receptor agonism are mediated by brainstem cholecystokinin neurons, and modulated by GIP receptor activation. Mol Metab 2021; 55:101407. [PMID: 34844019 PMCID: PMC8689241 DOI: 10.1016/j.molmet.2021.101407] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/23/2021] [Accepted: 11/24/2021] [Indexed: 02/07/2023] Open
Abstract
Objective Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are effective medications to reduce appetite and body weight. These actions are centrally mediated; however, the neuronal substrates involved are poorly understood. Methods We employed a combination of neuroanatomical, genetic, and behavioral approaches in the mouse to investigate the involvement of caudal brainstem cholecystokinin-expressing neurons in the effect of the GLP-1RA exendin-4. We further confirmed key neuroanatomical findings in the non-human primate brain. Results We found that cholecystokinin-expressing neurons in the caudal brainstem are required for the anorectic and body weight-lowering effects of GLP-1RAs and for the induction of GLP-1RA-induced conditioned taste avoidance. We further show that, while cholecystokinin-expressing neurons are not a direct target for glucose-dependent insulinotropic peptide (GIP), GIP receptor activation results in a reduced recruitment of these GLP-1RA-responsive neurons and a selective reduction of conditioned taste avoidance. Conclusions In addition to disclosing a neuronal population required for the full appetite- and body weight-lowering effect of GLP-1RAs, our data also provide a novel framework for understanding and ameliorating GLP-1RA-induced nausea — a major factor for withdrawal from treatment. CCKAP/NTS neurons are required for the full anorectic and body weight-lowering effect of GLP-1 receptor agonists. GLP-1 receptor agonists promote the formation of conditioned taste avoidance by activating CCKAP/NTS neurons. CCKAP/NTS neurons are not activated in response to GIP receptor agonists. GIP receptor agonists reduce GLP-1 receptor agonist-induced neuronal responses in the caudal brainstem. GIP receptor agonists reduce GLP-1 receptor agonist-induced conditioned taste avoidance.
Collapse
Affiliation(s)
- Alessia Costa
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Minrong Ai
- Lilly Research Laboratories, Eli Lilly & Company, Indianapolis, IN, United States.
| | - Nicolas Nunn
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Isabella Culotta
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Jenna Hunter
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK; The Rowett Institute, University of Aberdeen, Aberdeen, UK
| | - Mehdi Boutagouga Boudjadja
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK; The Rowett Institute, University of Aberdeen, Aberdeen, UK
| | | | - Gabriella Aviello
- The Rowett Institute, University of Aberdeen, Aberdeen, UK; Department of Pharmacy, University of Naples Federico II, Naples, Italy
| | - David J Hodson
- Institute of Metabolism and Systems Research University of Birmingham &Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Brandy M Snider
- Lilly Research Laboratories, Eli Lilly & Company, Indianapolis, IN, United States
| | - Tamer Coskun
- Lilly Research Laboratories, Eli Lilly & Company, Indianapolis, IN, United States
| | - Paul J Emmerson
- Lilly Research Laboratories, Eli Lilly & Company, Indianapolis, IN, United States
| | - Simon M Luckman
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Giuseppe D'Agostino
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK; The Rowett Institute, University of Aberdeen, Aberdeen, UK.
| |
Collapse
|
2
|
Valencia-Torres L, Olarte-Sánchez CM, Lyons DJ, Georgescu T, Greenwald-Yarnell M, Myers MG, Bradshaw CM, Heisler LK. Activation of Ventral Tegmental Area 5-HT 2C Receptors Reduces Incentive Motivation. Neuropsychopharmacology 2017; 42:1511-1521. [PMID: 27882999 PMCID: PMC5362069 DOI: 10.1038/npp.2016.264] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 11/01/2016] [Accepted: 11/16/2016] [Indexed: 11/20/2022]
Abstract
Obesity is primarily due to food intake in excess of the body's energetic requirements, intake that is not only associated with hunger but also the incentive value of food. The 5-hydroxytryptamine 2C receptor (5-HT2CR) is a target for the treatment of human obesity. Mechanistically, 5-HT2CRs are positioned to influence both homeostatic feeding circuits within the hypothalamus and reward circuits within the ventral tegmental area (VTA). Here we investigated the role of 5-HT2CRs in incentive motivation using a mathematical model of progressive ratio (PR) responding in mice. We found that the 5-HT2CR agonist lorcaserin significantly reduced both ad libitum chow intake and PR responding for chocolate pellets and increased c-fos expression in VTA 5-HT2CR expressing γ-aminobutyric acid (GABA) neurons, but not 5-HT2CR expressing dopamine (DA) neurons. We next adopted a chemogenetic approach using a 5-HT2CRCRE line to clarify the function of subset of 5-HT2C receptor expressing VTA neurons in the modulation of appetite and food-motivated behavior. Activation of VTA 5-HT2C receptor expressing neurons significantly reduced ad libitum chow intake, operant responding for chocolate pellets, and the incentive value of food. In contrast, chemogenetic inhibition of VTA 5-HT2C receptor expressing neurons had no effect on the feeding behavior. These results indicate that activation of the subpopulation of 5-HT2CR neurons within the VTA is sufficient to significantly reduce homeostatic feeding and effort-based intake of palatable food, and that this subset has an inhibitory role in motivational processes. These findings are relevant to the treatment of obesity.
Collapse
Affiliation(s)
- Lourdes Valencia-Torres
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK,Rowett Institute of Nutrition and Health, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK, Tel/Fax: +44 (0) 1224 438750, E-mail: or
| | | | - David J Lyons
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Teodora Georgescu
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Megan Greenwald-Yarnell
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Martin G Myers
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Christopher M Bradshaw
- Division of Psychiatry, University of Nottingham, Queen's Medical Centre, Nottingham, UK
| | - Lora K Heisler
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK,Rowett Institute of Nutrition and Health, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK, Tel/Fax: +44 (0) 1224 438750, E-mail: or
| |
Collapse
|
3
|
Xu P, He Y, Cao X, Valencia-Torres L, Yan X, Saito K, Wang C, Yang Y, Hinton A, Zhu L, Shu G, Myers MG, Wu Q, Tong Q, Heisler LK, Xu Y. Activation of Serotonin 2C Receptors in Dopamine Neurons Inhibits Binge-like Eating in Mice. Biol Psychiatry 2017; 81:737-747. [PMID: 27516377 PMCID: PMC5148733 DOI: 10.1016/j.biopsych.2016.06.005] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 05/24/2016] [Accepted: 06/03/2016] [Indexed: 01/08/2023]
Abstract
BACKGROUND Neural networks that regulate binge eating remain to be identified, and effective treatments for binge eating are limited. METHODS We combined neuroanatomic, pharmacologic, electrophysiological, Cre-lox, and chemogenetic approaches to investigate the functions of 5-hydroxytryptamine (5-HT) 2C receptor (5-HT2CR) expressed by dopamine (DA) neurons in the regulation of binge-like eating behavior in mice. RESULTS We showed that 5-HT stimulates DA neural activity through a 5-HT2CR-mediated mechanism, and activation of this midbrain 5-HT→DA neural circuit effectively inhibits binge-like eating behavior in mice. Notably, 5-HT medications, including fluoxetine, d-fenfluramine, and lorcaserin (a selective 5-HT2CR agonist), act on 5-HT2CRs expressed by DA neurons to inhibit binge-like eating in mice. CONCLUSIONS We identified the 5-HT2CR population in DA neurons as one potential target for antibinge therapies, and provided preclinical evidence that 5-HT2CR agonists could be used to treat binge eating.
Collapse
Affiliation(s)
- Pingwen Xu
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Yanlin He
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Xuehong Cao
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | | | - Xiaofeng Yan
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Kenji Saito
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Chunmei Wang
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Yongjie Yang
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Antentor Hinton
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Liangru Zhu
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas,Department of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Sciences and Technology, Wuhan, Hubei, China
| | - Gang Shu
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Martin G. Myers
- Department of Internal Medicine and Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Qi Wu
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Qingchun Tong
- Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, Texas
| | - Lora K. Heisler
- Rowett Institute of Nutrition and Health, Foresterhill, Aberdeen, United Kingdom
| | - Yong Xu
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas; Children's Nutrition Research Center, and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas.
| |
Collapse
|
4
|
Burke LK, Doslikova B, D'Agostino G, Greenwald-Yarnell M, Georgescu T, Chianese R, Martinez de Morentin PB, Ogunnowo-Bada E, Cansell C, Valencia-Torres L, Garfield AS, Apergis-Schoute J, Lam DD, Speakman JR, Rubinstein M, Low MJ, Rochford JJ, Myers MG, Evans ML, Heisler LK. Sex difference in physical activity, energy expenditure and obesity driven by a subpopulation of hypothalamic POMC neurons. Mol Metab 2016; 5:245-252. [PMID: 26977396 PMCID: PMC4770275 DOI: 10.1016/j.molmet.2016.01.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 01/12/2016] [Accepted: 01/14/2016] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Obesity is one of the primary healthcare challenges of the 21st century. Signals relaying information regarding energy needs are integrated within the brain to influence body weight. Central among these integration nodes are the brain pro-opiomelanocortin (POMC) peptides, perturbations of which disrupt energy balance and promote severe obesity. However, POMC neurons are neurochemically diverse and the crucial source of POMC peptides that regulate energy homeostasis and body weight remains to be fully clarified. METHODS Given that a 5-hydroxytryptamine 2c receptor (5-HT2CR) agonist is a current obesity medication and 5-HT2CR agonist's effects on appetite are primarily mediated via POMC neurons, we hypothesized that a critical source of POMC regulating food intake and body weight is specifically synthesized in cells containing 5-HT2CRs. To exclusively manipulate Pomc synthesis only within 5-HT2CR containing cells, we generated a novel 5-HT 2C R (CRE) mouse line and intercrossed it with Cre recombinase-dependent and hypothalamic specific reactivatable Pomc (NEO) mice to restrict Pomc synthesis to the subset of hypothalamic cells containing 5-HT2CRs. This provided a means to clarify the specific contribution of a defined subgroup of POMC peptides in energy balance and body weight. RESULTS Here we transform genetically programed obese and hyperinsulinemic male mice lacking hypothalamic Pomc with increased appetite, reduced physical activity and compromised brown adipose tissue (BAT) into lean, healthy mice via targeted restoration of Pomc function only within 5-HT2CR expressing cells. Remarkably, the same metabolic transformation does not occur in females, who despite corrected feeding behavior and normalized insulin levels remain physically inactive, have lower energy expenditure, compromised BAT and develop obesity. CONCLUSIONS These data provide support for the functional heterogeneity of hypothalamic POMC neurons, revealing that Pomc expression within 5-HT2CR expressing neurons is sufficient to regulate energy intake and insulin sensitivity in male and female mice. However, an unexpected sex difference in the function of this subset of POMC neurons was identified with regard to energy expenditure. We reveal that a large sex difference in physical activity, energy expenditure and the development of obesity is driven by this subpopulation, which constitutes approximately 40% of all POMC neurons in the hypothalamic arcuate nucleus. This may have broad implications for strategies utilized to combat obesity, which at present largely ignore the sex of the obese individual.
Collapse
Affiliation(s)
- Luke K Burke
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK; Department of Medicine and Institute of Metabolic Science, University of Cambridge, Wellcome Trust/Medical Research Council, Cambridge, UK; Department of Pharmacology, University of Cambridge, Cambridge, UK
| | | | - Giuseppe D'Agostino
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK; 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, USA
| | - Teodora Georgescu
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Raffaella Chianese
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | | | - Emmanuel Ogunnowo-Bada
- Department of Medicine and Institute of Metabolic Science, University of Cambridge, Wellcome Trust/Medical Research Council, Cambridge, UK
| | - Celine Cansell
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Lourdes Valencia-Torres
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK; Department of Pharmacology, University of Cambridge, Cambridge, UK
| | | | | | - Daniel D Lam
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - John R Speakman
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK; State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Marcelo Rubinstein
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428, Buenos Aires, Argentina
| | - Malcolm J Low
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Justin J Rochford
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Martin G Myers
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Mark L Evans
- Department of Medicine and Institute of Metabolic Science, University of Cambridge, Wellcome Trust/Medical Research Council, Cambridge, UK.
| | - Lora K Heisler
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK.
| |
Collapse
|
5
|
Valencia-Torres L, Olarte-Sánchez CM, Body S, Bradshaw CM, Szabadi E. Investigations of the Neurobiological Bases of Inter-Temporal Choice Behaviour. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/15021149.2013.11434457] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
6
|
Olarte-Sánchez CM, Valencia-Torres L, Cassaday HJ, Bradshaw CM, Szabadi E. Quantitative analysis of performance on a progressive-ratio schedule: effects of reinforcer type, food deprivation and acute treatment with Δ⁹-tetrahydrocannabinol (THC). Behav Processes 2015; 113:122-31. [PMID: 25637881 PMCID: PMC4534516 DOI: 10.1016/j.beproc.2015.01.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 01/26/2015] [Accepted: 01/26/2015] [Indexed: 12/27/2022]
Abstract
Rats' performance on a progressive-ratio schedule maintained by sucrose (0.6M, 50 μl) and corn oil (100%, 25 μl) reinforcers was assessed using a model derived from Killeen's (1994) theory of schedule-controlled behaviour, 'Mathematical Principles of Reinforcement'. When the rats were maintained at 80% of their free-feeding body weights, the parameter expressing incentive value, a, was greater for the corn oil than for the sucrose reinforcer; the response-time parameter, δ, did not differ between the reinforcer types, but a parameter derived from the linear waiting principle (T0), indicated that the minimum post-reinforcement pause was longer for corn oil than for sucrose. When the rats were maintained under free-feeding conditions, a was reduced, indicating a reduction of incentive value, but δ was unaltered. Under the food-deprived condition, the CB1 cannabinoid receptor agonist Δ(9)-tetrahydrocannabinol (THC: 0.3, 1 and 3 mg kg(-1)) increased the value of a for sucrose but not for corn oil, suggesting a selective enhancement of the incentive value of sucrose; none of the other parameters was affected by THC. The results provide new information about the sensitivity of the model's parameters to deprivation and reinforcer quality, and suggest that THC selectively enhances the incentive value of sucrose.
Collapse
Affiliation(s)
- C M Olarte-Sánchez
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, UK.
| | - L Valencia-Torres
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, UK.
| | - H J Cassaday
- School of Psychology, University of Nottingham, UK.
| | - C M Bradshaw
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, UK.
| | - E Szabadi
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, UK.
| |
Collapse
|
7
|
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] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
|
8
|
Orduña V, Valencia-Torres L, Cruz G, Bouzas A. Sensitivity to delay is affected by magnitude of reinforcement in rats. Behav Processes 2013; 98:18-24. [DOI: 10.1016/j.beproc.2013.04.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 04/02/2013] [Accepted: 04/11/2013] [Indexed: 10/26/2022]
|
9
|
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: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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
| |
Collapse
|
10
|
Valencia-Torres L, Olarte-Sánchez CM, Body S, Cheung THC, Fone KCF, Bradshaw CM, Szabadi E. Fos expression in the prefrontal cortex and ventral striatum after exposure to a free-operant timing schedule. Behav Brain Res 2012; 235:273-9. [PMID: 22917527 PMCID: PMC3657143 DOI: 10.1016/j.bbr.2012.08.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Revised: 08/06/2012] [Accepted: 08/08/2012] [Indexed: 12/01/2022]
Abstract
It has been proposed that cortico-striato-thalamo-cortical circuits that incorporate the prefrontal cortex and corpus striatum regulate interval timing behaviour. In the present experiment regional Fos expression was compared between rats trained under an immediate timing schedule, the free-operant psychophysical procedure (FOPP), which entails temporally regulated switching between two operanda, and a yoked variable-interval (VI) schedule matched to the timing task for food deprivation level, reinforcement rate and overall response rate. The density of Fos-positive neurones (counts mm−2) in the orbital prefrontal cortex (OPFC) and the shell of the nucleus accumbens (AcbS) was greater in rats exposed to the FOPP than in rats exposed to the VI schedule, suggesting a greater activation of these areas during the performance of the former task. The enhancement of Fos expression in the OPFC is consistent with previous findings with both immediate and retrospective timing schedules. Enhanced Fos expression in the AcbS was previously found in retrospective timing schedules based on conditional discrimination tasks, but not in a single-operandum immediate timing schedule, the fixed-interval peak procedure. It is suggested that the ventral striatum may be engaged during performance on timing schedules that entail operant choice, irrespective of whether they belong to the immediate or retrospective categories.
Collapse
Affiliation(s)
- L Valencia-Torres
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, UK.
| | | | | | | | | | | | | |
Collapse
|
11
|
Valencia-Torres L, Olarte-Sánchez C, Body S, Fone K, Bradshaw C, Szabadi E. Fos expression in the orbital prefrontal cortex after exposure to the fixed-interval peak procedure. Behav Brain Res 2012; 229:372-7. [PMID: 22301352 PMCID: PMC3657145 DOI: 10.1016/j.bbr.2012.01.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 01/13/2012] [Accepted: 01/14/2012] [Indexed: 12/26/2022]
Abstract
It has been proposed that cortico-striato-thalamo-cortical circuits that incorporate the prefrontal cortex and dorsal striatum regulate interval timing behaviour. The present experiment examined whether performance on the fixed-interval peak procedure (FIPP), an immediate timing schedule, would induce neuronal activity in cortical and striatal areas, as revealed by enhanced expression of the Fos protein, a marker for neuronal activation. Regional Fos expression was compared between rats trained on the FIPP and rats trained on a variable-interval (VI) schedule matched to the FIPP for overall response rate and reinforcer delivery. Response rate in the peak trials of the FIPP conformed to a temporally differentiated pattern, which was well described by a modified Gaussian function; in agreement with previous findings, the peak time occurred close to the time at which the reinforcer was delivered in the fixed-interval trials, and the Weber fraction was within the range of values reported previously. The density of Fos-positive neurones (counts mm−2) in the orbital prefrontal cortex (OPFC) was greater in rats exposed to the FIPP than in rats exposed to the VI schedule, suggesting a greater activation of this area during the performance of the former task. This is consistent with the results of previous studies that have implicated the OPFC in interval timing behaviour. However, there was no significant difference between the levels of Fos expression in the dorsal or ventral striatum of the rats trained under the two schedules.
Collapse
Affiliation(s)
- L. Valencia-Torres
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - C.M. Olarte-Sánchez
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - S. Body
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - K.C.F. Fone
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
- School of Biomedical Sciences, University of Nottingham, Room E20, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - C.M. Bradshaw
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
- Corresponding author. Tel.: +44 0115 823 0219; fax: +44 0115 823 0220.
| | - E. Szabadi
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
| |
Collapse
|
12
|
Valencia-Torres L, Olarte-Sánchez CM, da Costa Araújo S, Body S, Bradshaw CM, Szabadi E. Nucleus accumbens and delay discounting in rats: evidence from a new quantitative protocol for analysing inter-temporal choice. Psychopharmacology (Berl) 2012; 219:271-83. [PMID: 21894486 DOI: 10.1007/s00213-011-2459-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 08/15/2011] [Indexed: 11/24/2022]
Abstract
RATIONALE There is evidence that the core of the nucleus accumbens (AcbC) is involved in inter-temporal choice behaviour. OBJECTIVE A new behavioural protocol was used to examine the effect of destruction of the AcbC on delay discounting in inter-temporal choice schedules in rats. METHOD Rats with excitotoxic lesions of the AcbC or sham lesions made repeated choices on an adjusting-delay schedule between a smaller reinforcer (A) that was delivered immediately and a larger reinforcer (B) that was delivered after a delay which increased or decreased depending on the subject's choices. In two phases of the experiment, reinforcer sizes were selected which enabled theoretical parameters expressing delay discounting and sensitivity to reinforcer size to be estimated from the ratio of the indifference delays (i.e. the quasi-stable values of the adjusting delay seen after extended training) obtained in the two phases. RESULTS In both groups, indifference delays were shorter when the sizes of A and B were 14 and 25 μl than when they were 25 and 100 μl of a 0.6 M sucrose solution. Indifference delays were shorter in AcbC-lesioned than in sham-lesioned rats. Estimates of delay discounting rate based on the ratio of the indifference delays were lower in the AcbC-lesioned than in the sham-lesioned rats. The size sensitivity parameter did not differ between the groups. Adjusting delays in successive blocks of trials were analysed using Fourier transform. The period corresponding to the dominant frequency of the power spectrum and power within the dominant frequency band did not differ between the groups. CONCLUSIONS Destruction of the AcbC increased the rate of delay discounting.
Collapse
Affiliation(s)
- L Valencia-Torres
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Room B109, Medical School, Queen's Medical Centre, Nottingham, NG7 2UH, UK
| | | | | | | | | | | |
Collapse
|
13
|
Orduña V, Valencia-Torres L, Bouzas A. DRL performance of spontaneously hypertensive rats: dissociation of timing and inhibition of responses. Behav Brain Res 2009; 201:158-65. [PMID: 19428629 DOI: 10.1016/j.bbr.2009.02.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 11/14/2008] [Accepted: 02/06/2009] [Indexed: 11/16/2022]
Abstract
In this experiment, we used a differential reinforcement of low rates (DRL) schedule to evaluate the performance of spontaneously hypertensive rats (SHR), Wistar Kyoto (WKY) and Wistar (WIS) rats, with the goal of dissociating the processes of timing and inhibition of responses through the use of two quantitative models: the peak deviation analysis and the temporal regulation model. The subjects were divided in two groups; the first group was exposed to 70 sessions under a DRL 10s schedule. SHR rats showed an apparent temporary deficit in the inhibition of responses process; however, no differences among strains were observed in terms of the timing process. The second group of rats was exposed to 30 sessions in DRL 10s schedule, before receiving three doses (2 mg/kg, 4 mg/kg and 8 mg/kg) of methylphenidate. The results obtained through both models were consistent and indicated that at higher drug doses, the performance of all three strains of rats deteriorated. The impulsivity exhibited by SHR during acquisition supports the idea of these rats as an adequate animal model of ADHD. In contrast, evidence against this relies on the normal temporal processing found and in the worsening effect that methylphenidate produced in the process of inhibition of responses. These mixed results suggest the necessity of exploring timing behavior of other animal models in order to find a reliable animal model of ADHD.
Collapse
Affiliation(s)
- Vladimir Orduña
- Facultad de Psicologia, Universidad Nacional Autónoma de México, México, DF, Mexico.
| | | | | |
Collapse
|