1
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Fox AE, Nicholson AM, Singha D, Thieret BAS, Ortiz M, Visser EJ. Timing and delay discounting in attention-deficit/hyperactivity disorder: A translational approach. Dev Psychobiol 2023; 65:e22399. [PMID: 37338253 DOI: 10.1002/dev.22399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 03/16/2023] [Accepted: 04/20/2023] [Indexed: 06/21/2023]
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder that often presents with abnormal time perception and increased impulsive choice behavior. The spontaneously hypertensive rat (SHR) is the most widely used preclinical model of the ADHD-Combined and ADHD-Hyperactive/Impulsive subtypes of the disorder. However, when testing the spontaneously hypertensive rat from Charles River (SHR/NCrl) on timing and impulsive choice tasks, the appropriate control strain is not clear, and it is possible that one of the possible control strains, the Wistar Kyoto from Charles River (WKY/NCrl), is an appropriate model for ADHD-Predominately Inattentive. Our goals were to test the SHR/NCrl, WKY/NCrl, and Wistar (WI; the progenitor strain for the SHR/NCrl and WKY/NCrl) strains on time perception and impulsive choice tasks to assess the validity of SHR/NCrl and WKY/NCrl as models of ADHD, and the validity of the WI strain as a control. We also sought to assess impulsive choice behavior in humans diagnosed with the three subtypes of ADHD and compare them with our findings from the preclinical models. We found SHR/NCrl rats timed faster and were more impulsive than WKY/NCrl and WI rats, and human participants diagnosed with ADHD were more impulsive compared to controls, but there were no differences between the three ADHD subtypes.
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Affiliation(s)
- Adam E Fox
- Department of Psychology, St. Lawrence University, Canton, New York, USA
| | - Alycia M Nicholson
- Department of Psychology, St. Lawrence University, Canton, New York, USA
| | - Depika Singha
- Department of Psychology, St. Lawrence University, Canton, New York, USA
| | - Bryana A S Thieret
- Department of Psychology, St. Lawrence University, Canton, New York, USA
| | - Marcelo Ortiz
- Department of Psychology, St. Lawrence University, Canton, New York, USA
| | - Emma J Visser
- Department of Psychology, St. Lawrence University, Canton, New York, USA
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2
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Silic B, Aggarwal M, Liyanagama K, Tripp G, Wickens JR. Conditioned approach behavior of SHR and SD rats during Pavlovian conditioning. Behav Brain Res 2023; 443:114348. [PMID: 36796486 DOI: 10.1016/j.bbr.2023.114348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 02/04/2023] [Accepted: 02/13/2023] [Indexed: 02/16/2023]
Abstract
Individual differences in reward-related learning are relevant to many behavioral disorders. Sensory cues that predict reward can become incentive stimuli that adaptively support behavior, or alternatively, cause maladaptive behaviors. The spontaneously hypertensive rat (SHR) expresses a genetically determined elevated sensitivity to delay of reward, and has been extensively studied as a behavioral model for attention deficit hyperactivity disorder (ADHD). We investigated reward-related learning in the SHR, comparing them to Sprague-Dawley (SD) rats as a reference strain. A standard Pavlovian conditioned approach task was used, in which a lever cue was followed by reward. Lever presses could occur while the lever was extended, but had no effect on reward delivery. The behavior of both the SHRs and the SD rats showed that they learnt that the lever cue predicted reward. However, the pattern of behavior differed between the strains. During lever cue presentation, SD rats pressed the lever more often and made fewer magazine entries than SHRs. When lever contacts that did not result in lever presses were analyzed, there was no significant difference between SHRs and SDs. These results suggest that the SHRs attributed less incentive value to the conditioned stimulus than the SD rats. During the presentation of the conditioned cue, cue directed responses are called sign tracking responses, whereas responses directed towards the food magazine are called goal tracking responses. Analysis of behavior using a standard Pavlovian conditioned approach index to quantify sign and goal tracking tendencies showed that both strains had a tendency towards goal tracking in this task. However, the SHRs showed a significantly greater goal tracking tendency than the SD rats. Taken together, these findings suggest that attribution of incentive value to reward predicting cues is attenuated in SHRs, which might explain their elevated sensitivity to delay of reward.
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Affiliation(s)
- Bozena Silic
- Neurobiology Research Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Mayank Aggarwal
- Laboratory for Integrated Theoretical Neuroscience, Center for Brain Science, RIKEN, Japan
| | - Kavinda Liyanagama
- Neurobiology Research Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Gail Tripp
- Human Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Jeffery R Wickens
- Neurobiology Research Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan.
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3
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Spontaneously hypertensive rats manifest deficits in emotional response to 22-kHz and 50-kHz ultrasonic playback. Prog Neuropsychopharmacol Biol Psychiatry 2023; 120:110615. [PMID: 36007820 DOI: 10.1016/j.pnpbp.2022.110615] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 08/03/2022] [Accepted: 08/13/2022] [Indexed: 10/15/2022]
Abstract
Many symptoms used routinely for human psychiatric diagnosis cannot be directly observed in animals which cannot describe their internal states. However, the ultrasonic vocalizations (USV) rodents use to communicate their emotional states can be measured. USV have therefore become a particularly useful tool in brain disease models. Spontaneously hypertensive rats (SHR) are considered an animal model of attention deficit hyperactivity disorder (ADHD) and schizophrenia. However, the specifics of SHR's behavior have not been fully described and there is very little data on their USV. Recently, we developed a communication model, in which Wistar rats are exposed to pre-recorded playbacks of aversive (22-kHz) or appetitive (50-kHz) USV, and their vocal responses depend on the extent of prior fear conditioning (0, 1, 6 or 10 shocks). Here, we investigated SHR's behavior and heart rate (HR) in our communication model, in comparison to Wistar rats employed as controls. In general, SHR emitted typical USV categories, however, they contained more short 22-kHz and less 50-kHz USV overall. Moreover, fewer SHR, in comparison with Wistar rats, emitted long 22-kHz USV after fear conditioning. SHR did not show a 50-kHz playback-induced HR increase, while they showed a profound 22-kHz playback-induced HR decrease. Finally, the number of previously delivered conditioning shocks appeared to have no effect on the investigated vocal, locomotor and HR responses of SHR. The phenomena observed in SHR are potentially attributable to deficits in emotional perception and processing. A lower number of 50-kHz USV emitted by SHR may reflect observations of speech impairments in human patients and further supports the usefulness of SHR to model ADHD and schizophrenia.
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4
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Galizio A, Odum AL. Reinforced behavioral variability in the valproate rat model of autism spectrum disorder. J Exp Anal Behav 2022; 117:576-596. [PMID: 35467762 DOI: 10.1002/jeab.760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 02/28/2022] [Accepted: 03/29/2022] [Indexed: 11/05/2022]
Abstract
Individuals diagnosed with autism spectrum disorder (ASD) tend to display restricted, repetitive behaviors and deficits in social interaction. Rats exposed to valproate (VPA) in utero have been shown to model symptoms of ASD. In previous research, VPA rats engaged in less social interaction and more repetitive responding than controls. The purpose of the present study was to further investigate behavioral variability in the VPA rat model of ASD by testing VPA and control rats in a reinforced-behavioral-variability operant task. In this procedure, rats emitted sequences of lever presses, some of which produced food. During baseline, food was delivered probabilistically, and variability was not required. Next, rats were exposed either to a variability contingency, in which food was only delivered following sequences that differed sufficiently from previous sequences (i.e., variability required), or to a yoked contingency, in which variability was not required. We hypothesized that VPA rats would behave less variably than controls in this task. However, VPA and control rats responded similarly variably when variability was required. Furthermore, VPA rats behaved slightly more variably than controls during baseline and yoked conditions, when variability was not required. These findings contribute to the complex literature surrounding the VPA rat model of ASD.
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Affiliation(s)
- Ann Galizio
- Utah State University, Department of Psychology
| | - Amy L Odum
- Utah State University, Department of Psychology
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5
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Yde Ohki CM, McNeill RV, Nieberler M, Radtke F, Kittel-Schneider S, Grünblatt E. Promising Developments in the Use of Induced Pluripotent Stem Cells in Research of ADHD. Curr Top Behav Neurosci 2022; 57:483-501. [PMID: 35543866 DOI: 10.1007/7854_2022_346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Although research using animal models, peripheral and clinical biomarkers, multimodal neuroimaging techniques and (epi)genetic information has advanced our understanding of Attention-Deficit Hyperactivity Disorder (ADHD), the aetiopathology of this neurodevelopmental disorder has still not been elucidated. Moreover, as the primary affected tissue is the brain, access to samples is problematic. Alternative models are therefore required, facilitating cellular and molecular analysis. Recent developments in stem cell research have introduced the possibility to reprogram somatic cells from patients, in this case ADHD, and healthy controls back into their pluripotent state, meaning that they can then be differentiated into any cell or tissue type. The potential to translate patients' somatic cells into stem cells, and thereafter to use 2- and 3-dimensional (2D and 3D) neuronal cells to model neurodevelopmental disorders and/or test novel drug therapeutics, is discussed in this chapter.
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Affiliation(s)
- Cristine Marie Yde Ohki
- Department of Child and Adolescent Psychiatry and Psychotherapy, Psychiatric University Hospital Zurich (PUK), University of Zurich, Zürich, Switzerland
| | - Rhiannon V McNeill
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Matthias Nieberler
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Franziska Radtke
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Wuerzburg, Würzburg, Germany
| | - Sarah Kittel-Schneider
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital Wuerzburg, Wuerzburg, Germany
| | - Edna Grünblatt
- Department of Child and Adolescent Psychiatry and Psychotherapy, Psychiatric University Hospital Zurich (PUK), University of Zurich, Zürich, Switzerland.
- Neuroscience Center Zurich, University of Zurich and the ETH Zurich, Zürich, Switzerland.
- Zurich Center for Integrative Human Physiology, University of Zurich, Zürich, Switzerland.
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6
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Regan SL, Williams MT, Vorhees CV. Review of rodent models of attention deficit hyperactivity disorder. Neurosci Biobehav Rev 2022; 132:621-637. [PMID: 34848247 PMCID: PMC8816876 DOI: 10.1016/j.neubiorev.2021.11.041] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 01/03/2023]
Abstract
Attention deficit hyperactivity disorder (ADHD) is a polygenic neurodevelopmental disorder that affects 8-12 % of children and >4 % of adults. Environmental factors are believed to interact with genetic predispositions to increase susceptibility to ADHD. No existing rodent model captures all aspects of ADHD, but several show promise. The main genetic models are the spontaneous hypertensive rat, dopamine transporter knock-out (KO) mice, dopamine receptor subtype KO mice, Snap-25 KO mice, guanylyl cyclase-c KO mice, and latrophilin-3 KO mice and rats. Environmental factors thought to contribute to ADHD include ethanol, nicotine, PCBs, lead (Pb), ionizing irradiation, 6-hydroxydopamine, neonatal hypoxia, some pesticides, and organic pollutants. Model validation criteria are outlined, and current genetic models evaluated against these criteria. Future research should explore induced multiple gene KOs given that ADHD is polygenic and epigenetic contributions. Furthermore, genetic models should be combined with environmental agents to test for interactions.
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Affiliation(s)
- Samantha L. Regan
- Neuroscience Graduate Program, University of Cincinnati, Cincinnati, OH 45229
| | - Michael T. Williams
- Department of Pediatrics, University of Cincinnati College of Medicine, and Division of Neurology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229
| | - Charles V. Vorhees
- Department of Pediatrics, University of Cincinnati College of Medicine, and Division of Neurology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229,Corresponding author: Charles V. Vorhees, Ph.D., Div. of Neurology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229, USA:
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7
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Fan HC, Chang YK, Tsai JD, Chiang KL, Shih JH, Yeh KY, Ma KH, Li IH. The Association Between Parkinson's Disease and Attention-Deficit Hyperactivity Disorder. Cell Transplant 2021; 29:963689720947416. [PMID: 33028106 PMCID: PMC7784516 DOI: 10.1177/0963689720947416] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
While Parkinson’s disease (PD) and attention-deficit hyperactivity disorder (ADHD) are two distinct conditions, it has been hypothesized that they share several overlapping anatomical and neurochemical changes. In order to investigate that hypothesis, this study used claims data from Taiwan’s Longitudinal Health Insurance Database 2000 to provide the significant nationwide population-based evidence of an increased risk of PD among ADHD patients, and the connection between the two conditions was not the result of other comorbidities. Moreover, this study showed that the patients with PD were 2.8 times more likely to have a prior ADHD diagnosis compared with those without a prior history of ADHD. Furthermore, an animal model of ADHD was generated by neonatally injecting rats with 6-hydroxydopamine (6-OHDA). These rats were subjected to behavior tests and the 99mTc-TRODAT-1 brain imaging at the juvenile stage. Compared to control group rats, the 6-OHDA rats showed a significantly reduced specific uptake ratio in the striatum, indicating an underlying PD-linked pathology in the brains of these ADHD phenotype-expressing rats. Overall, these results support that ADHD shares a number of anatomical and neurochemical changes with PD. As such, improved knowledge of the neurochemical mechanisms underlying ADHD could result in improved treatments for various debilitating neurological disorders, including PD.
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Affiliation(s)
- Hueng-Chuen Fan
- Department of Pediatrics, 59084Tungs' Taichung Metroharbor Hospital, Wuchi, Taichung.,Department of Medical research, 68866Tungs' Taichung Metroharbor Hospital, Wuchi, Taichung.,Department of Life Sciences, 59084National Chung Hsing University, Taichung.,Department of Rehabilitation, Jen-Teh Junior College of Medicine, Nursing and Management, Miaoli
| | - Yu-Kang Chang
- Department of Medical research, 68866Tungs' Taichung Metroharbor Hospital, Wuchi, Taichung.,Department of Life Sciences, 59084National Chung Hsing University, Taichung.,Department of Rehabilitation, Jen-Teh Junior College of Medicine, Nursing and Management, Miaoli
| | - Jeng-Dau Tsai
- School of Medicine, 34899Chung Shan Medical University, Taichung.,Department of Pediatrics, 34899Chung Shan Medical University Hospital, Taichung
| | - Kuo-Liang Chiang
- Department of Pediatric Neurology, 38009Kuang-Tien General Hospital, Taichung.,Department of Nutrition, Hungkuang University, Taichung
| | - Jui-Hu Shih
- Department of Pharmacy Practice, 63452Tri-Service General Hospital, Taipei.,School of Pharmacy, 71548National Defense Medical Center, Taipei
| | - Kuan-Yi Yeh
- Department of Biology and Anatomy, 71548National Defense Medical Center, Taipei
| | - Kuo-Hsing Ma
- Department of Biology and Anatomy, 71548National Defense Medical Center, Taipei
| | - I-Hsun Li
- Department of Pharmacy Practice, 63452Tri-Service General Hospital, Taipei.,School of Pharmacy, 71548National Defense Medical Center, Taipei
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8
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Cartland SP, Tamer N, Patil MS, Di Bartolo BA, Kavurma MM. A "Western Diet" promotes symptoms of hepatic steatosis in spontaneously hypertensive rats. Int J Exp Pathol 2020; 101:152-161. [PMID: 32783310 DOI: 10.1111/iep.12369] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 06/15/2020] [Accepted: 07/02/2020] [Indexed: 12/23/2022] Open
Abstract
Systemic hypertension, characterized by elevated blood pressure ≥140/90 mm Hg, is a major modifiable risk factor for cardiovascular disease. Hypertension also associates with non-alcoholic fatty liver disease (NAFLD), which is becoming common due to a modern diet and lifestyle. The aim of the present study was to examine whether a high-fat "Western" diet had effects on hypertension and associated NAFLD. Normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) were placed on a normal chow or high-fat diet for 8 weeks; blood pressure was measured fortnightly and body weight recorded weekly. As expected, SHR had elevated blood pressure compared to WKY. Diet did not influence blood pressure. Compared to SHR, WKY rats gained more weight, associating with increased white adipose tissue weight. Normotensive rats also had higher plasma cholesterol and triglycerides in response to a "Western" diet, with no changes in plasma glucose levels. Neither strain developed atherosclerosis. Interestingly, high-fat diet-fed SHR had increased liver weight, associating with a significant level of hepatic lipid accumulation not observed in WKY. Further, they exhibited hepatocellular ballooning and increased hepatic inflammation, indicative of steatohepatitis. These findings suggest that a high-fat "Western" diet promotes features of NAFLD in SHR, but not WKY rats. Importantly, the high-fat diet had no effect on blood pressure.
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Affiliation(s)
- Siân P Cartland
- Heart Research Institute, Sydney, NSW, Australia.,Faculty of Health and Medicine, University of Sydney, Sydney, NSW, Australia
| | - Nicole Tamer
- Heart Research Institute, Sydney, NSW, Australia
| | | | - Belinda A Di Bartolo
- Heart Research Institute, Sydney, NSW, Australia.,Faculty of Health and Medicine, University of Sydney, Sydney, NSW, Australia.,Kolling Institute of Medical Research, Royal North Shore Hospital, Sydney, NSW, Australia
| | - Mary M Kavurma
- Heart Research Institute, Sydney, NSW, Australia.,Faculty of Health and Medicine, University of Sydney, Sydney, NSW, Australia
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9
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Models of attention-deficit hyperactivity disorder. Behav Processes 2019; 162:205-214. [DOI: 10.1016/j.beproc.2019.01.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 01/16/2019] [Accepted: 01/16/2019] [Indexed: 12/25/2022]
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10
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Delay Gradients for Spout-Licking and Magazine-Entering Induced by a Periodic Food Schedule. PSYCHOLOGICAL RECORD 2018. [DOI: 10.1007/s40732-018-0275-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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11
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The Effect of Methylphenidate on the Microstructure of Schedule-Induced Polydipsia in an animal model of ADHD. Behav Brain Res 2017; 333:211-217. [PMID: 28669538 DOI: 10.1016/j.bbr.2017.06.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 06/23/2017] [Accepted: 06/29/2017] [Indexed: 01/15/2023]
Abstract
Schedule-induced polydipsia (SIP) was established in spontaneously hypertensive rats (SHR), Wistar Kyoto rats (WKY), and Wistar rats, using a multiple fixed-time (FT) schedule of food delivery, with 30- and 90-s components. Thereafter, animals were exposed to methylphenidate (MPH; 2.5mg/kg/d) for six consecutive SIP sessions. A test to assess possible sensitization effects was also conducted four days after termination of the drug treatment. At baseline, FT 90-s produced longer and more frequent drinking episodes in SHR than in WKY. An analysis of the distribution of inter-lick intervals revealed that drinking was organized in bouts, which were shorter in SHR than in WKY. Across strains and schedules, MPH shifted drinking episodes towards the beginning of inter-food intervals, which may reflect a stimulant effect on SIP. MPH transiently reduced the frequency of drinking episodes in WKY in FT 30-s, and more permanently reduced the frequency of licking bouts in Wistar rats. MPH also increased the length of licking bouts in Wistar rats. Overall, SHR displayed a hyperactive-like pattern of drinking (frequent but short bouts), which 2.5mg/kg MPH appears to reduce in WKY and Wistar but not in SHR rats. It appears that therapeutic effects of MPH on hyperactive-like SIP require higher doses in SHR relative to control strains.
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12
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Fox AE, Caramia SR, Haskell MM, Ramey AL, Singha D. Stimulus control in two rodent models of attention-deficit/hyperactivity disorder. Behav Processes 2017; 135:16-24. [DOI: 10.1016/j.beproc.2016.11.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 11/10/2016] [Accepted: 11/14/2016] [Indexed: 12/16/2022]
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13
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Watterson E, Spitzer A, Watterson LR, Brackney RJ, Zavala AR, Olive MF, Sanabria F. Nicotine-induced behavioral sensitization in an adult rat model of attention deficit/hyperactivity disorder (ADHD). Behav Brain Res 2016; 312:333-40. [PMID: 27363925 DOI: 10.1016/j.bbr.2016.06.050] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 06/23/2016] [Accepted: 06/26/2016] [Indexed: 12/23/2022]
Abstract
Attention deficit hyperactivity disorder (ADHD) is associated with increased risk of tobacco dependence. Nicotine, the main psychoactive component of tobacco, appears to be implicated in ADHD-related tobacco dependence. However, the behavioral responsiveness to nicotine of the prevalent animal model of ADHD, the spontaneously hypertensive rat (SHR), is currently underinvestigated. The present study examined the activational effects of acute and chronic nicotine on the behavior of adult male SHRs, relative to Wistar Kyoto (WKY) controls. Experiment 1 verified baseline strain differences in open-field locomotor activity. Experiment 2 tested for baseline strain differences in rotational behavior using a Rotorat apparatus. Adult SHR and WKY rats were then exposed to a 7-day regimen of 0.6mg/kg/d s.c. nicotine, or saline, prior to each assessment. A separate group of SHRs underwent similar training, but was pre-treated with mecamylamine, a cholinergic antagonist. Nicotine sensitization, context conditioning, and mecamylamine effects were then tested. Baseline strain differences were observed in open-field performance and in the number of full rotations in the Rotorat apparatus, but not in the number of 90° rotations or direction changes. In these latter measures, SHRs displayed weaker nicotine-induced rotational suppression than WKYs. Both strains expressed nicotine-induced sensitization of rotational activity, but evidence for strain differences in sensitization was ambiguous; context conditioning was not observed. Mecamylamine reversed the effects of nicotine on SHR performance. These findings are consistent with the hypothesis that a reduced aversion to nicotine (expressed in rats as robust locomotion) may facilitate smoking among adults with ADHD.
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Affiliation(s)
- Elizabeth Watterson
- Arizona State University, Department of Psychology, P.O. Box 871104, Tempe, AZ 85287, United States
| | - Alexander Spitzer
- Arizona State University, Department of Psychology, P.O. Box 871104, Tempe, AZ 85287, United States
| | - Lucas R Watterson
- Arizona State University, Department of Psychology, P.O. Box 871104, Tempe, AZ 85287, United States; Center for Substance Abuse Research Temple University School of Medicine, 3500N. Broad St., Medical Education and Research Bldg., 8th Floor, Philadelphia, PA 19140, United States
| | - Ryan J Brackney
- Arizona State University, Department of Psychology, P.O. Box 871104, Tempe, AZ 85287, United States
| | - Arturo R Zavala
- California State University, Long Beach, CA 90840, United States
| | - M Foster Olive
- Arizona State University, Department of Psychology, P.O. Box 871104, Tempe, AZ 85287, United States
| | - Federico Sanabria
- Arizona State University, Department of Psychology, P.O. Box 871104, Tempe, AZ 85287, United States.
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14
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Íbias J, Miguéns M, Pellón R. Effects of dopamine agents on a schedule-induced polydipsia procedure in the spontaneously hypertensive rat and in Wistar control rats. J Psychopharmacol 2016; 30:856-66. [PMID: 27296274 DOI: 10.1177/0269881116652598] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The spontaneously hypertensive rat (SHR) has been proposed as an animal model for attention deficit hyperactivity disorder (ADHD), and typically develops excessive patterns of response under most behavioural protocols. Schedule-induced polydipsia (SIP) is the excessive water consumption that occurs as a schedule effect when food is intermittently delivered and animals are partially food- but not water-deprived. SIP has been used as a model of excessive behaviour, and considerable evidence has involved the dopaminergic system in its development and maintenance. The aim of this study was to evaluate the effects of the most common psychostimulants used in ADHD treatment on SIP, comparing their effects in SHRs with rats from control populations. SHR, Wistar Kyoto (WKY) and Wistar rats were submitted to a multiple fixed time (FT) food schedule with two components: 30 s and 90 s. The acute effects of different dopaminergic compounds were evaluated after 40 sessions of SIP acquisition. All animals showed higher adjunctive drinking under FT 30 s than FT 90 s, and SHRs displayed higher asymptotic SIP levels in FT 90 s compared to WKY and Wistar rats. SHRs were less sensitive to dopaminergic agents than control rats in terms of affecting rates of adjunctive drinking. These differences point to an altered dopaminergic system in the SHR and provide new insights into the neurobiological basis of ADHD pharmacological treatments.
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Affiliation(s)
- Javier Íbias
- Animal Behaviour Laboratories, Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain
| | - Miguel Miguéns
- Animal Behaviour Laboratories, Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain
| | - Ricardo Pellón
- Animal Behaviour Laboratories, Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain
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15
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Huang J, Zhong Z, Wang M, Chen X, Tan Y, Zhang S, He W, He X, Huang G, Lu H, Wu P, Che Y, Yan YL, Postlethwait JH, Chen W, Wang H. Circadian modulation of dopamine levels and dopaminergic neuron development contributes to attention deficiency and hyperactive behavior. J Neurosci 2015; 35:2572-87. [PMID: 25673850 PMCID: PMC4323534 DOI: 10.1523/jneurosci.2551-14.2015] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 12/14/2014] [Accepted: 12/19/2014] [Indexed: 01/16/2023] Open
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is one of the most prevalent psychiatric disorders in children and adults. While ADHD patients often display circadian abnormalities, the underlying mechanisms are unclear. Here we found that the zebrafish mutant for the circadian gene period1b (per1b) displays hyperactive, impulsive-like, and attention deficit-like behaviors and low levels of dopamine, reminiscent of human ADHD patients. We found that the circadian clock directly regulates dopamine-related genes monoamine oxidase and dopamine β hydroxylase, and acts via genes important for the development or maintenance of dopaminergic neurons to regulate their number and organization in the ventral diencephalic posterior tuberculum. We then found that Per1 knock-out mice also display ADHD-like symptoms and reduced levels of dopamine, thereby showing highly conserved roles of the circadian clock in ADHD. Our studies demonstrate that disruption of a circadian clock gene elicits ADHD-like syndrome. The circadian model for attention deficiency and hyperactive behavior sheds light on ADHD pathogenesis and opens avenues for exploring novel targets for diagnosis and therapy for this common psychiatric disorder.
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Affiliation(s)
- Jian Huang
- Center for Circadian Clocks, School of Biology & Basic Medical Sciences, Medical College
| | - Zhaomin Zhong
- Center for Circadian Clocks, School of Biology & Basic Medical Sciences, Medical College
| | - Mingyong Wang
- Center for Circadian Clocks, School of Biology & Basic Medical Sciences, Medical College
| | - Xifeng Chen
- Center for Circadian Clocks, School of Biology & Basic Medical Sciences, Medical College
| | - Yicheng Tan
- Center for Circadian Clocks, School of Biology & Basic Medical Sciences, Medical College
| | - Shuqing Zhang
- Center for Circadian Clocks, School of Biology & Basic Medical Sciences, Medical College
| | - Wei He
- Center for Circadian Clocks, School of Biology & Basic Medical Sciences, Medical College
| | - Xiong He
- Center for Circadian Clocks, School of Biology & Basic Medical Sciences, Medical College
| | - Guodong Huang
- Center for Circadian Clocks, School of Biology & Basic Medical Sciences, Medical College
| | - Haiping Lu
- Department of Pediatrics and Child Health, Affiliated Children's Hospital, Soochow University, Suzhou 215003, Jiangsu, China
| | - Ping Wu
- School of Biology & Basic Medical Sciences, Medical College
| | - Yi Che
- School of Biology & Basic Medical Sciences, Medical College
| | - Yi-Lin Yan
- Center for Circadian Clocks, Institute of Neuroscience, University of Oregon, Eugene, Oregon 97403, and
| | | | - Wenbiao Chen
- Center for Circadian Clocks, Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Han Wang
- Center for Circadian Clocks, School of Biology & Basic Medical Sciences, Medical College,
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Ibias J, Pellón R. Different relations between schedule-induced polydipsia and impulsive behaviour in the Spontaneously Hypertensive Rat and in high impulsive Wistar rats: questioning the role of impulsivity in adjunctive behaviour. Behav Brain Res 2014; 271:184-94. [PMID: 24931797 DOI: 10.1016/j.bbr.2014.06.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Revised: 06/03/2014] [Accepted: 06/06/2014] [Indexed: 12/17/2022]
Abstract
Rats belonging to three different strains (15 Wistar, 8 Spontaneously Hypertensive - SHR- and 8 Wistar Kyoto - WKY-) were used to evaluate the possible relationship between different levels of impulsivity and development of schedule-induced polydipsia (SIP). We first measured the rats' levels of impulsivity by means of delay-discounting and indifference-point procedures. Secondly, development of SIP was studied under a series of fixed time 15, 30, 60 and 120s food schedules, which were counterbalanced by means of a Latin-square design. Finally, we re-assessed the rats' levels of impulsivity by replicating the delay-discounting test. The findings showed that, starting from equivalent levels of impulsivity, development of SIP differed among the groups of rats. In comparison with the rest of the animals, the SHRs were observed to attain elevated drinking rates under SIP. On the other hand, the Wistar rats which had initial high impulsivity levels similar to those of the SHRs, displayed the lowest rates of induced drinking. Moreover, low levels of impulsivity in Wistar rats prior to SIP acquisition were reflected into high drinking rates. Relation of SIP and impulsivity is questioned by present results, which gives ground to the understanding of the behavioural mechanisms involved in adjunctive behaviour and its usefulness as an animal model of excessive behaviour.
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Affiliation(s)
- Javier Ibias
- Animal Behaviour Laboratories, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), C/Juan del Rosal 10, Ciudad Universitaria, 28040 Madrid, Spain
| | - Ricardo Pellón
- Animal Behaviour Laboratories, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), C/Juan del Rosal 10, Ciudad Universitaria, 28040 Madrid, Spain.
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Kim P, Choi I, Pena ICD, Kim HJ, Kwon KJ, Park JH, Han SH, Ryu JH, Cheong JH, Shin CY. A simple behavioral paradigm to measure impulsive behavior in an animal model of attention deficit hyperactivity disorder (ADHD) of the spontaneously hypertensive rats. Biomol Ther (Seoul) 2013; 20:125-31. [PMID: 24116285 PMCID: PMC3792196 DOI: 10.4062/biomolther.2012.20.1.125] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 11/18/2011] [Accepted: 11/23/2011] [Indexed: 11/24/2022] Open
Abstract
Impulsiveness is an important component of many psychiatric disorders including Attention-deficit/hyperactivity disorder (ADHD). Although the neurobiological basis of ADHD is unresolved, behavioral tests in animal models have become indispensable tools for improving our understanding of this disorder. In the punishment/extinction paradigm, impulsivity is shown by subjects that persevere with responding despite punishment or unrewarded responses. Exploiting this principle, we developed a new behavioral test that would evaluate impulsivity in the most validated animal model of ADHD of the Spontaneously Hypertensive rat (SHR) as compared with the normotensive “control” strain, the Wistar Kyoto rat (WKY). In this paradigm we call the Electro-Foot Shock aversive water Drinking test (EFSDT), water-deprived rats should pass over an electrified quadrant of the EFSDT apparatus to drink water. We reasoned that impulsive animals show increased frequency to drink water even with the presentation of an aversive consequence (electro-shock). Through this assay, we showed that the SHR was more impulsive than the WKY as it demonstrated more “drinking attempts” and drinking frequency. Methylphenidate, the most widely used ADHD medication, significantly reduced drinking frequency of both SHR and WKY in the EFSDT. Thus, the present assay may be considered as another behavioral tool to measure impulsivity in animal disease models, especially in the context of ADHD.
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Affiliation(s)
- Pitna Kim
- Center for Neuroscience Research, IBST and School of Medicine, Konkuk University, Seoul 143-701
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18
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Somkuwar SS, Darna M, Kantak KM, Dwoskin LP. Adolescence methylphenidate treatment in a rodent model of attention deficit/hyperactivity disorder: dopamine transporter function and cellular distribution in adulthood. Biochem Pharmacol 2013; 86:309-16. [PMID: 23623751 DOI: 10.1016/j.bcp.2013.04.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 04/17/2013] [Accepted: 04/17/2013] [Indexed: 02/08/2023]
Abstract
Attention deficit/hyperactivity disorder (ADHD) is attributed to dysfunction of the prefrontal cortex. Methylphenidate, an inhibitor of dopamine and norepinephrine transporters (DAT and NET, respectively), is a standard treatment for ADHD. The Spontaneously Hypertensive Rat (SHR) is a well-established animal model of ADHD. Our previous results showed that methylphenidate treatment in adolescent SHR enhanced cocaine self-administration during adulthood, and alterations in DAT function in prefrontal cortex play a role in this response. Importantly, prefrontal cortex subregions, orbitofrontal cortex (OFC) and medial prefrontal cortex (mPFC), have been shown to have distinct roles in ADHD and cocaine self-administration. In the current study, SHR, Wistar-Kyoto (WKY) and Wistar (WIS) rats received a therapeutically relevant dose of methylphenidate (1.5mg/kg, p.o.) or vehicle during adolescence and then OFC and mPFC DAT function and cellular expression were assessed during adulthood. In both OFC and mPFC, no strain differences in Vmax or Km for dopamine uptake into synaptosomes were found between vehicle-treated SHR, WKY and WIS. Methylphenidate increased DAT Vmax in SHR mPFC and decreased DAT Vmax in WKY OFC. Also, methylphenidate decreased DAT Km in WIS OFC. Further, methylphenidate did not alter DAT cellular localization, indicating that methylphenidate treatment during adolescence regulated DAT function in SHR mPFC in a trafficking-independent manner. Thus, the increase in mPFC DAT function was an SHR-specific long term consequence of methylphenidate treatment during adolescence, which may be responsible for the treatment-induced alterations in behavior including the observed increases in cocaine self-administration.
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Affiliation(s)
- Sucharita S Somkuwar
- Department of Pharmaceutical Sciences, 789 South Limestone, University of Kentucky, Lexington, KY 40536, USA
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19
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Strain differences in self-administration of methylphenidate and sucrose pellets in a rat model of attention-deficit hyperactivity disorder. Behav Pharmacol 2013; 22:794-804. [PMID: 22015805 DOI: 10.1097/fbp.0b013e32834d623e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Despite its abuse potential, methylphenidate (MPH) is widely prescribed for treatment of attention-deficit hyperactivity disorder (ADHD). The purpose of the present study was to examine MPH self-administration in a rat model of ADHD. Experiment 1 examined the acquisition of MPH self-administration and assessed the MPH dose-effect curve in spontaneously hypertensive rats (SHR), an inbred rat model of ADHD, Wistar Kyotos (WKY), the progenitor strain for SHR, and Sprague-Dawley (SD), an outbred control strain. Experiment 2 replicated Experiment 1, but replaced MPH infusions with sucrose pellets. Initial acquisition of MPH self-administration was greater in SHR and SD than WKY. However, with extended training using an incrementing fixed ratio schedule SHR and WKY did not differ in responding for MPH using the training dose (0.3 mg/kg/infusion) or other unit doses, except that SHR showed greater responding than WKY at 0.1 mg/kg/infusion. SHR also showed greater acquisition and maintenance of sucrose-reinforced responding compared with both WKY and SD. Greater initial acquisition of MPH self-administration in SHR than WKY may not be due to a strain-specific difference in sensitivity to the reinforcing effect of MPH.
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20
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Brackney RJ, Cheung THC, Herbst K, Hill JC, Sanabria F. Extinction learning deficit in a rodent model of attention-deficit hyperactivity disorder. Behav Brain Funct 2012; 8:59. [PMID: 23237608 PMCID: PMC3542014 DOI: 10.1186/1744-9081-8-59] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 11/25/2012] [Indexed: 11/27/2022] Open
Abstract
Background Deficient operant extinction has been hypothesized to be constitutive of ADHD dysfunction. In order to elucidate the behavioral mechanisms underlying this deficit, the performance of an animal model of ADHD, the spontaneously hypertensive rat (SHR), was compared against the performance of a control strain, the Wistar-Kyoto rat (WKY) during extinction. Method Following extensive training of lever pressing under variable interval schedules of food reinforcement (reported previously), SHR and WKY rats were exposed to two sessions of extinction training. Extinction data was analyzed using the Dynamic Bi-Exponential Refractory Model (DBERM) of operant performance. DBERM assumes that operant responses are organized in bouts separated by pauses; during extinction, bouts may decline across multiple dimensions, including frequency and length. DBERM parameters were estimated using hierarchical Bayesian modeling. Results SHR responded more than WKY during the first extinction session. DBERM parameter estimates revealed that, at the onset of extinction, SHR produced more response bouts than WKY. Over the course of extinction, response bouts progressively shortened for WKY but not for SHR. Conclusions Based on prior findings on the sensitivity of DBERM parameters to motivational and schedule manipulations, present data suggests that (1) more frequent response bouts in SHR are likely related to greater incentive motivation, and (2) the persistent length of bouts in SHR are likely related to a slower updating of the response-outcome association. Overall, these findings suggest specific motivational and learning deficits that may explain ADHD-related impairments in operant performance.
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Affiliation(s)
- Ryan J Brackney
- Arizona State University, PO Box 871104, Tempe, AZ 85287-1104, USA.
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21
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Pardey MC, Kumar NN, Goodchild AK, Clemens KJ, Homewood J, Cornish JL. Long-term effects of chronic oral Ritalin administration on cognitive and neural development in adolescent wistar kyoto rats. Brain Sci 2012; 2:375-404. [PMID: 24961199 PMCID: PMC4061802 DOI: 10.3390/brainsci2030375] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 08/24/2012] [Accepted: 08/28/2012] [Indexed: 11/17/2022] Open
Abstract
The diagnosis of Attention Deficit Hyperactivity Disorder (ADHD) often results in chronic treatment with psychostimulants such as methylphenidate (MPH, Ritalin®). With increases in misdiagnosis of ADHD, children may be inappropriately exposed to chronic psychostimulant treatment during development. The aim of this study was to assess the effect of chronic Ritalin treatment on cognitive and neural development in misdiagnosed “normal” (Wistar Kyoto, WKY) rats and in Spontaneously Hypertensive Rats (SHR), a model of ADHD. Adolescent male animals were treated for four weeks with oral Ritalin® (2 × 2 mg/kg/day) or distilled water (dH2O). The effect of chronic treatment on delayed reinforcement tasks (DRT) and tyrosine hydroxylase immunoreactivity (TH-ir) in the prefrontal cortex was assessed. Two weeks following chronic treatment, WKY rats previously exposed to MPH chose the delayed reinforcer significantly less than the dH2O treated controls in both the DRT and extinction task. MPH treatment did not significantly alter cognitive performance in the SHR. TH-ir in the infralimbic cortex was significantly altered by age and behavioural experience in WKY and SHR, however this effect was not evident in WKY rats treated with MPH. These results suggest that chronic treatment with MPH throughout adolescence in “normal” WKY rats increased impulsive choice and altered catecholamine development when compared to vehicle controls.
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Affiliation(s)
- Margery C Pardey
- Department of Psychology, Macquarie University, Sydney 2109, Australia.
| | - Natasha N Kumar
- The Australian School of Advanced Medicine, Macquarie University, Sydney 2109, Australia.
| | - Ann K Goodchild
- The Australian School of Advanced Medicine, Macquarie University, Sydney 2109, Australia.
| | - Kelly J Clemens
- Department of Psychology, Macquarie University, Sydney 2109, Australia.
| | - Judi Homewood
- Department of Psychology, Macquarie University, Sydney 2109, Australia.
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Miller EM, Pomerleau F, Huettl P, Russell VA, Gerhardt GA, Glaser PEA. The spontaneously hypertensive and Wistar Kyoto rat models of ADHD exhibit sub-regional differences in dopamine release and uptake in the striatum and nucleus accumbens. Neuropharmacology 2012; 63:1327-34. [PMID: 22960443 DOI: 10.1016/j.neuropharm.2012.08.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 07/31/2012] [Accepted: 08/21/2012] [Indexed: 10/27/2022]
Abstract
The most widely used animal model of attention-deficit/hyperactivity disorder (ADHD) is the spontaneously hypertensive rat (SHR/NCrl), which best represents the combined subtype (ADHD-C). Recent evidence has revealed that a progenitor strain, the Wistar Kyoto from Charles River Laboratories (WKY/NCrl), is useful as a model of the inattentive subtype (ADHD-PI) and the Wistar Kyoto from Harlan Laboratories (WKY/NHsd) and the Sprague Dawley (SD) have been suggested as controls. Dopamine (DA) dysfunction in the striatum (Str) and nucleus accumbens core (NAc) is thought to play a significant role in the pathophysiology of ADHD but data obtained with the SHR is equivocal. Using high-speed chronoamperometric recordings with carbon fiber microelectrodes, we found that the SHR/NCrl displayed decreased KCl-evoked DA release versus the WKY/NCrl model of ADHD-PI in the dorsal Str. The WKY/NCrl and the WKY/NHsd control did not differ from each other; however, the control SD released less DA than the WKY/NCrl model of ADHD-PI in the dorsal Str and less than the control WKY/NHsd in the intermediate Str. The SHR/NCrl had faster DA uptake in the ventral Str and NAc versus both control strains, while the WKY/NCrl model of ADHD-PI exhibited faster DA uptake in the NAc versus the SD control. These results suggest that increased surface expression of DA transporters may explain the more rapid uptake of DA in the Str and NAc of these rodent models of ADHD.
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Affiliation(s)
- Erin M Miller
- Department of Anatomy & Neurobiology, University of Kentucky College of Medicine, 138 Leader Avenue, Lexington, KY 40506, USA
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23
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Wickens JR, Hyland BI, Tripp G. Animal models to guide clinical drug development in ADHD: lost in translation? Br J Pharmacol 2012; 164:1107-28. [PMID: 21480864 DOI: 10.1111/j.1476-5381.2011.01412.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We review strategies for developing animal models for examining and selecting compounds with potential therapeutic benefit in attention-deficit hyperactivity disorder (ADHD). ADHD is a behavioural disorder of unknown aetiology and pathophysiology. Current understanding suggests that genetic factors play an important role in the aetiology of ADHD. The involvement of dopaminergic and noradrenergic systems in the pathophysiology of ADHD is probable. We review the clinical features of ADHD including inattention, hyperactivity and impulsivity and how these are operationalized for laboratory study. Measures of temporal discounting (but not premature responding) appear to predict known drug effects well (treatment validity). Open-field measures of overactivity commonly used do not have treatment validity in human populations. A number of animal models have been proposed that simulate the symptoms of ADHD. The most commonly used are the spontaneously hypertensive rat (SHR) and the 6-hydroxydopamine-lesioned (6-OHDA) animals. To date, however, the SHR lacks treatment validity, and the effects of drugs on symptoms of impulsivity and inattention have not been studied extensively in 6-OHDA-lesioned animals. At the present stage of development, there are no in vivo models of proven effectiveness for examining and selecting compounds with potential therapeutic benefit in ADHD. However, temporal discounting is an emerging theme in theories of ADHD, and there is good evidence of increased value of delayed reward following treatment with stimulant drugs. Therefore, operant behaviour paradigms that measure the effects of drugs in situations of delayed reinforcement, whether in normal rats or selected models, show promise for the future.
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Van Voorhees EE, Mitchell JT, McClernon FJ, Beckham JC, Kollins SH. Sex, ADHD symptoms, and smoking outcomes: an integrative model. Med Hypotheses 2012; 78:585-93. [PMID: 22341778 DOI: 10.1016/j.mehy.2012.01.034] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 01/19/2012] [Indexed: 10/28/2022]
Abstract
Both females and individuals with Attention-Deficit/Hyperactivity Disorder (ADHD) have been found to be at increased risk for a range of smoking outcomes, and recent empirical findings have suggested that women with ADHD may be particularly vulnerable to nicotine dependence. On a neurobiological level, the dopamine reward processing system may be implicated in the potentially unique interaction of nicotine with sex and with ADHD status. Specifically, nicotine appears to mitigate core ADHD symptoms through interaction with the dopamine reward processing system, and ovarian hormones have been found to interact with nicotine within the dopamine reward processing system to affect neurotransmitter release and functioning. This article synthesizes data from research examining smoking in women and in individuals with ADHD to build an integrative model through which unique risk for cigarette smoking in women with ADHD can be systematically explored. Based upon this model, the following hypotheses are proposed at the intersection of each of the three variables of sex, ADHD, and smoking: (1) individuals with ADHD have altered functioning of the dopamine reward system, which diminishes their ability to efficiently form conditioned associations based on environmental contingencies; these deficits are partially ameliorated by nicotine; (2) nicotine interacts with estrogen and the dopamine reward system to increase the positive and negative reinforcement value of smoking in female smokers; (3) in adult females with ADHD, ovarian hormones interact with the dopamine reward system to exacerbate ADHD-related deficits in the capacity to form conditioned associations; and (4) during different phases of the menstrual cycle, nicotine and ovarian hormones may interact differentially with the dopamine reward processing system to affect the type and value of reinforcement smoking provides for women with ADHD. Understanding the bio-behavioral mechanisms underlying cigarette addiction in specific populations will be critical to developing effectively tailored smoking prevention and cessation programs for these groups. Overall, the goal of this paper is to examine the interaction of sex, smoking, and ADHD status within the context of the dopamine reward processing system not only to elucidate potential mechanisms specific to female smokers with ADHD, but also to stimulate consideration of how the examination of such individual differences can inform our understanding of smoking more broadly.
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Affiliation(s)
- Elizabeth E Van Voorhees
- VISN 6 Mid-Atlantic Mental Illness Research, Education, and Clinical Center, Durham Veterans Affairs Medical Center, 508 Fulton Street, Durham, NC 27705, USA.
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Hill JC, Herbst K, Sanabria F. Characterizing operant hyperactivity in the Spontaneously Hypertensive Rat. Behav Brain Funct 2012; 8:5. [PMID: 22277367 PMCID: PMC3292830 DOI: 10.1186/1744-9081-8-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 01/26/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Operant hyperactivity, the emission of reinforced responses at an inordinately high rate, has been reported in children with ADHD and in the Spontaneously Hypertensive Rat (SHR), the most widely studied animal model of ADHD. The SHR emits behavior at hyperactive levels, relative to a normoactive strain, only when such behavior is seldom reinforced. Because of its dependence on rate of reinforcement, operant hyperactivity appears to be driven primarily by incentive motivation, not motoric capacity. This claim was evaluated in the present study using a novel strategy, based on the organization of behavior in bouts of reinforced responses separated by pauses. METHOD Male SHR, Wistar-Kyoto (WKY) and Wistar rats (WIS) were exposed each to a multiple variable-interval schedule of sucrose reinforcement (12, 24, 48, 96, and 192 s) between post-natal days (PND) 48 and 93. Responding in each schedule was examined in two epochs, PND 58-62 and 89-93. Parameters of response-reinforcement functions (Herrnstein's hyperbola) and bout-organized behavior were estimated in each epoch. RESULTS SHR emitted higher response rates than WKY and WIS, but only when rate of reinforcement was low (fewer than 2 reinforcers per minute), and particularly in the second epoch. Estimates of Herrnstein's hyperbola parameters suggested the primacy of motivational over motoric factors driving the response-rate differential. Across epochs and schedules, a more detailed analysis of response bouts by SHR revealed that these were shorter than those by WKY, but more frequent than those by WKY and WIS. Differences in bout length subsided between epochs, but differences in bout-initiation rate were exacerbated. These results were interpreted in light of robust evidence linking changes in bout-organization parameters and experimental manipulations of motivation and response-reinforcement contingency. CONCLUSIONS Operant hyperactivity in SHR was confirmed. Although incentive motivation appears to play an important role in operant hyperactivity and motoric capacity cannot be ruled out as a factor, response-bout patterns suggest that operant hyperactivity is primarily driven by steeper delay-of-reinforcement gradients. Convergence of this conclusion with theoretical accounts of ADHD and with free-operant performance in children with ADHD supports the use of SHR as an animal model of ADHD.
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Affiliation(s)
- Jade C Hill
- Department of Psychology, Arizona State University, Tempe, Arizona 85287-1104, USA
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26
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Wigestrand MB, Mineur YS, Heath CJ, Fonnum F, Picciotto MR, Walaas SI. Decreased α4β2 nicotinic receptor number in the absence of mRNA changes suggests post-transcriptional regulation in the spontaneously hypertensive rat model of ADHD. J Neurochem 2011; 119:240-50. [PMID: 21824140 DOI: 10.1111/j.1471-4159.2011.07415.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The spontaneously hypertensive rat (SHR) is widely used as a model of attention-deficit/hyperactivity disorder (ADHD). Deficits in central nicotinic receptors (nAChRs) have been previously observed in SHRs, which is interesting since epidemiological studies have identified an association between smoking and ADHD symptoms in humans. Here, we examine whether nAChR deficits in SHRs compared with Wistar Kyoto rat (WKY) controls are nAChR subtype-specific and whether these deficits correlate with changes at the level of mRNA transcription in specific brain regions. Levels of binding sites (B(max) ) and dissociation constants (K(d)) for nAChRs were determined from saturation curves of high-affinity [³H]epibatidine- and [³H] Methyllycaconitine (MLA) binding to membranes from cortex, striatum, hippocampus and cerebellum. In additional brain regions, nAChRs were examined by autoradiography with [¹²⁵I]A-85380 and [¹²⁵I]α-bungarotoxin. Levels of mRNA encoding nAChR subunits were measured using quantitative real-time PCR (qPCR). We showed that the number of α4β2 nAChR binding sites is lower globally in the SHR brain compared with WKY in the absence of significant differences in mRNA levels, with the exception of lower α4 mRNA in cerebellum of SHR compared with WKY. Furthermore, nAChR deficits were subtype- specific because no strain difference was found in α7 nAChR binding or α7 mRNA levels. Our results suggest that the lower α4β2 nAChR number in SHR compared with WKY may be a consequence of dysfunctional post-transcriptional regulation of nAChRs.
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Affiliation(s)
- Mattis B Wigestrand
- Department of Biochemistry, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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27
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Wooters TE, Bardo MT. Methylphenidate and fluphenazine, but not amphetamine, differentially affect impulsive choice in spontaneously hypertensive, Wistar-Kyoto and Sprague-Dawley rats. Brain Res 2011; 1396:45-53. [PMID: 21570676 DOI: 10.1016/j.brainres.2011.04.040] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 04/20/2011] [Accepted: 04/21/2011] [Indexed: 12/21/2022]
Abstract
Impulsivity is one of the core symptoms of attention-deficit/hyperactivity disorder (ADHD). The spontaneously hypertensive rat (SHR), a putative animal model of ADHD, has been used to investigate the neurobiology of impulsivity, although this model has been questioned over concerns that use of Wistar-Kyoto rats (WKY) as a comparison strain may exaggerate effects. The present study compared SHR, WKY and standard, outbred Sprague-Dawley (SD) rats on a delay discounting task where the primary measure was mean adjusted delay (MAD), or the indifference point (in sec) between choice of an immediate delivery of 1 grain-based pellet versus 3 pellets delivered after varying delays. The acute dose effects of the ADHD medications amphetamine (0.1-1.0 mg/kg) and methylphenidate (1.0-10 mg/kg) were then determined; in addition, the effect of the dopamine receptor antagonist fluphenazine (0.1-1.0 mg/kg) was also assessed for comparison with the indirect agonists. While there were no strain differences in the rate of task acquisition or stabilization of baseline MAD scores, SHR had significantly lower MAD scores than WKY but not SD due to the greater individual variability of MAD scores in SD. Although amphetamine did not alter MAD scores in any strain, methylphenidate selectively increased MAD scores in WKY and fluphenazine selectively increased MAD scores in SHR. WKY were also more sensitive than SHR and SD to the response-impairing effects of each drug. The finding that SHR showed a decrease in impulsivity following fluphenazine, but not following either amphetamine or methylphenidate, suggests that delay discounting in SHR may not represent a valid predictive model for screening effective ADHD medications in humans.
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Affiliation(s)
- Thomas E Wooters
- Department of Psychology, University of Kentucky, Lexington, 40536, USA
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28
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Russell VA. Overview of animal models of attention deficit hyperactivity disorder (ADHD). ACTA ACUST UNITED AC 2011; Chapter 9:Unit9.35. [PMID: 21207367 DOI: 10.1002/0471142301.ns0935s54] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is a heterogeneous, highly heritable, behavioral disorder that affects ∼5% to 10% of children worldwide. Although animal models cannot truly reflect human psychiatric disorders, they can provide insight into the disorder that cannot be obtained from human studies because of the limitations of available techniques. Genetic models include the spontaneously hypertensive rat (SHR), the Naples High Excitability (NHE) rat, poor performers in the 5-choice serial reaction time (5-CSRT) task, the dopamine transporter (DAT) knock-out mouse, the SNAP-25 deficient mutant coloboma mouse, mice expressing a human mutant thyroid hormone receptor, a nicotinic receptor knock-out mouse, and a tachykinin-1 (NK1) receptor knock-out mouse. Chemically induced models of ADHD include prenatal or early postnatal exposure to ethanol, nicotine, polychlorinated biphenyls, or 6-hydroxydopamine (6-OHDA). Environmentally induced models have also been suggested; these include neonatal anoxia and rat pups reared in social isolation. The major insight provided by animal models was the consistency of findings regarding the involvement of dopaminergic, noradrenergic, and sometimes also serotonergic systems, as well as more fundamental defects in neurotransmission.
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Affiliation(s)
- Vivienne Ann Russell
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory, South Africa
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Meneses A, Perez-Garcia G, Ponce-Lopez T, Tellez R, Gallegos-Cari A, Castillo C. Spontaneously hypertensive rat (SHR) as an animal model for ADHD: a short overview. Rev Neurosci 2011; 22:365-71. [DOI: 10.1515/rns.2011.024] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Abstract
Studies employing animal models of attention-deficit/hyperactivity disorder (ADHD) present clear inherent advantages over human studies. Animal models are invaluable tools for the study of underlying neurochemical, neuropathological and genetic alterations that cause ADHD, because they allow relatively fast, rigorous hypothesis testing and invasive manipulations as well as selective breeding. Moreover, especially for ADHD, animal models with good predictive validity would allow the assessment of potential new therapeutics. In this chapter, we describe and comment on the most frequently used animal models of ADHD that have been created by genetic, neurochemical and physical alterations in rodents. We then discuss that an emerging and promising direction of the field is the analysis of individual behavioural differences among a normal population of animals. Subjects presenting extreme characteristics related to ADHD can be studied, thereby avoiding some of the problems that are found in other models, such as functional recovery and unnecessary assumptions about aetiology. This approach is justified by the theoretical need to consider human ADHD as the extreme part of a spectrum of characteristics that are distributed normally in the general population, as opposed to the predominant view of ADHD as a separate pathological category.
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Affiliation(s)
- A Bari
- Department of Experimental Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Downing Street, Cambridge, CB2 3EB, UK,
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Focus on the positive: computational simulations implicate asymmetrical reward prediction error signals in childhood attention-deficit/hyperactivity disorder. Brain Res 2010; 1365:18-34. [PMID: 20875804 DOI: 10.1016/j.brainres.2010.09.065] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Revised: 08/30/2010] [Accepted: 09/17/2010] [Indexed: 02/02/2023]
Abstract
A number of hypotheses have suggested that the principal neurological dysfunction responsible for the behavioural symptoms associated with Attention-Deficit/Hyperactive Disorder (ADHD) is likely rooted in abnormal phasic signals coded by the firing rate of midbrain dopamine neurons. We present a formal investigation of the impact atypical phasic dopamine signals have on behaviour by applying a TD(λ) reinforcement learning model to simulations of operant conditioning tasks that have been argued to quantify the hyperactive, inattentive and impulsive behaviour associated with ADHD. The results presented here suggest that asymmetrically effective dopamine signals encoded by a punctate increase or decrease in dopamine levels provide the best account for the behaviour of children with ADHD as well as an animal model of ADHD, the spontaneously hypertensive rat (SHR). The biological sources of this asymmetry are considered, as are other computational models of ADHD.
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Qian Y, Lei G, Castellanos FX, Forssberg H, Heijtz RD. Deficits in fine motor skills in a genetic animal model of ADHD. Behav Brain Funct 2010; 6:51. [PMID: 20809977 PMCID: PMC2940855 DOI: 10.1186/1744-9081-6-51] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Accepted: 09/01/2010] [Indexed: 01/25/2023] Open
Abstract
Background In an attempt to model some behavioral aspects of Attention Deficit/Hyperactivity Disorder (ADHD), we examined whether an existing genetic animal model of ADHD is valid for investigating not only locomotor hyperactivity, but also more complex motor coordination problems displayed by the majority of children with ADHD. Methods We subjected young adolescent Spontaneously Hypertensive Rats (SHRs), the most commonly used genetic animal model of ADHD, to a battery of tests for motor activity, gross motor coordination, and skilled reaching. Wistar (WIS) rats were used as controls. Results Similar to children with ADHD, young adolescent SHRs displayed locomotor hyperactivity in a familiar, but not in a novel environment. They also had lower performance scores in a complex skilled reaching task when compared to WIS rats, especially in the most sensitive measure of skilled performance (i.e., single attempt success). In contrast, their gross motor performance on a Rota-Rod test was similar to that of WIS rats. Conclusion The results support the notion that the SHR strain is a useful animal model system to investigate potential molecular mechanisms underlying fine motor skill problems in children with ADHD.
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Affiliation(s)
- Yu Qian
- Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
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Sontag TA, Tucha O, Walitza S, Lange KW. Animal models of attention deficit/hyperactivity disorder (ADHD): a critical review. ACTA ACUST UNITED AC 2010; 2:1-20. [DOI: 10.1007/s12402-010-0019-x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Accepted: 01/02/2010] [Indexed: 01/04/2023]
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Luman M, Tripp G, Scheres A. Identifying the neurobiology of altered reinforcement sensitivity in ADHD: a review and research agenda. Neurosci Biobehav Rev 2009; 34:744-54. [PMID: 19944715 DOI: 10.1016/j.neubiorev.2009.11.021] [Citation(s) in RCA: 212] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 11/20/2009] [Accepted: 11/21/2009] [Indexed: 10/20/2022]
Abstract
ADHD is associated with altered reinforcement sensitivity, despite a number of inconsistent findings. This review focuses on the overlap and differences between seven neurobiologically valid models and lists 15 predictions assessing reinforcement sensitivity in ADHD. When comparing the models it becomes clear that there are great differences in the level of explanation. For example, some models try to explain a single core deficit in terms lower-level reinforcement systems, such as the dopamine transfer to reward back in time. Other models explain multiple deficits, by describing higher-level systems, such as impaired bottom-up prefrontal activation. When reviewing the available experimental evidence in support of the predictions, most experimental studies have been focusing on behavioral changes in the face of reward and response cost over no-reward, and on delay discounting. There is currently a lack in studies that focus on explaining underlying cognitive or neural mechanisms of altered reinforcement sensitivity in ADHD. Additionally, there is a lack in studies that try to understand what subgroup of children with ADHD shows alterations in reinforcement sensitivity. The scarcity in studies testing the neurobiological predictions is explained partly by a lack in knowledge how to test some of these predictions in humans. Nevertheless, we believe that these predictions can serve as a useful guide to the systematic evaluation of altered reinforcement sensitivity in ADHD.
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Affiliation(s)
- Marjolein Luman
- Department of Clinical Neurpsychology, Vrije Universiteit Amsterdam, Van der Boechorststraat 1, 1081 BT Amsterdam, The Netherlands.
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Dissociation between spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats in baseline performance and methylphenidate response on measures of attention, impulsivity and hyperactivity in a Visual Stimulus Position Discrimination Task. Pharmacol Biochem Behav 2009; 94:374-9. [PMID: 19818805 DOI: 10.1016/j.pbb.2009.09.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 09/16/2009] [Accepted: 09/24/2009] [Indexed: 11/20/2022]
Abstract
The spontaneously hypertensive rat (SHR) is a widely accepted rodent model of Attention Deficit/Hyperactivity Disorder (ADHD), and methylphenidate (MP) is a central nervous system stimulant that has been shown to have a dose-related positive effect on attention task performance in humans with ADHD. The current study was undertaken to compare SHR to its typical control strain, Wistar-Kyoto (WKY) rats, on the performance of a Visual Stimulus Position Discrimination Task (VSPDT) as well as of the responsiveness of the two rat strains to MP treatment. The rats were initially trained on the VSPDT, in which a light cue was presented randomly at three different cue-light intervals (1s, 300ms and 100ms) over one of two levers, and presses on the lever corresponding to the light cue were reinforced with a food pellet. Once rats reached stable performance, the treatment phase of the study began, during which they received daily intraperitoneal (IP) injections of saline, 2mg/kg, 5mg/kg, and 10mg/kg of MP in a randomized order immediately prior to being tested on the VSPDT. Baseline performance accuracy on the VSPDT did not differ between the groups. Furthermore, a striking strain dissociation was evident in the response of the two strains to treatment; VSPDT performance was substantially disrupted by the 5 and 10mg/kg dose in the WKY rats but only mildly in the SHR rats. Response omissions were also increased only in WKY rats. Finally, both strains had increased locomotor activity in the operant chamber following MP treatment. These findings point to an important difference in response tendency to MP in the two strains that supports a view that a critical difference between these strains may suggest neurochemical and neuroadaptive differences associated with the behavioral impairments of ADHD.
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Sagvolden T, Johansen EB, Wøien G, Walaas SI, Storm-Mathisen J, Bergersen LH, Hvalby O, Jensen V, Aase H, Russell VA, Killeen PR, Dasbanerjee T, Middleton FA, Faraone SV. The spontaneously hypertensive rat model of ADHD--the importance of selecting the appropriate reference strain. Neuropharmacology 2009; 57:619-26. [PMID: 19698722 DOI: 10.1016/j.neuropharm.2009.08.004] [Citation(s) in RCA: 159] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 08/10/2009] [Accepted: 08/11/2009] [Indexed: 01/02/2023]
Abstract
Although several molecular and genetic manipulations may produce hyperactive animals, hyperactivity alone is insufficient for the animal to qualify as a model of ADHD. Based on a wider range of criteria - behavioral, genetic and neurobiological - the spontaneously hypertensive rat (SHR) obtained from Charles River, Germany (SHR/NCrl) at present constitutes the best validated animal model of ADHD combined subtype (ADHD-C), and the Wistar Kyoto substrain obtained from Harlan, UK (WKY/NHsd) is its most appropriate control. Although other rat strains may behave like WKY/NHsd rats, genetic results indicate significant differences when compared to the WKY/NHsd substrain, making them less suitable controls for the SHR/NCrl. The use of WKY/NCrl, outbred Wistar, Sprague Dawley or other rat strains as controls for SHRs may produce spurious neurobiological differences. Consequently, data may be misinterpreted if insufficient care is taken in the selection of the control group. It appears likely that the use of different control strains may underlie some of the discrepancies in results and interpretations in studies involving the SHR and WKY. Finally, we argue that WKY rats obtained from Charles River, Germany (WKY/NCrl) provide a promising model for the predominantly inattentive subtype of ADHD (ADHD-PI); in this case also the WKY/NHsd substrain should be used as control.
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Affiliation(s)
- Terje Sagvolden
- Institute of Basic Medical Sciences, University of Oslo, Norway.
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Fox AT, Hand DJ, Reilly MP. Evaluating timing in spontaneously hypertensive and Wistar–Kyoto rats using the peak procedure. Behav Processes 2009; 81:293-7. [DOI: 10.1016/j.beproc.2009.01.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Revised: 01/29/2009] [Accepted: 01/30/2009] [Indexed: 10/21/2022]
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Adenosine receptor antagonists improve short-term object-recognition ability of spontaneously hypertensive rats: a rodent model of attention-deficit hyperactivity disorder. Behav Pharmacol 2009; 20:134-45. [DOI: 10.1097/fbp.0b013e32832a80bf] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Pardey MC, Homewood J, Taylor A, Cornish JL. Re-evaluation of an animal model for ADHD using a free-operant choice task. J Neurosci Methods 2009; 176:166-71. [DOI: 10.1016/j.jneumeth.2008.09.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 09/05/2008] [Accepted: 09/05/2008] [Indexed: 10/21/2022]
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Orduña V, García A, Menez M, Hong E, Bouzas A. Performance of spontaneously hypertensive rats in a peak-interval procedure with gaps. Behav Brain Res 2008; 191:72-6. [DOI: 10.1016/j.bbr.2008.03.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2007] [Revised: 02/24/2008] [Accepted: 03/10/2008] [Indexed: 10/22/2022]
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Cunha RA, Ferré S, Vaugeois JM, Chen JF. Potential therapeutic interest of adenosine A2A receptors in psychiatric disorders. Curr Pharm Des 2008; 14:1512-24. [PMID: 18537674 DOI: 10.2174/138161208784480090] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The interest on targeting adenosine A(2A) receptors in the realm of psychiatric diseases first arose based on their tight physical and functional interaction with dopamine D(2) receptors. However, the role of central A(2A) receptors is now viewed as much broader than just controlling D(2) receptor function. Thus, there is currently a major interest in the ability of A(2A) receptors to control synaptic plasticity at glutamatergic synapses. This is due to a combined ability of A(2A) receptors to facilitate the release of glutamate and the activation of NMDA receptors. Therefore, A(2A) receptors are now conceived as a normalizing device promoting adequate adaptive responses in neuronal circuits, a role similar to that fulfilled, in essence, by dopamine. This makes A(2A) receptors particularly attractive targets to manage psychiatric disorders since adenosine may act as go-between glutamate and dopamine, two of the key players in mood processing. Furthermore, A(2A) receptors also control glia function and brain metabolic adaptation, two other emerging mechanisms to understand abnormal processing of mood, and A(2A) receptors are important players in controlling the demise of neurodegeneration, considered an amplificatory loop in psychiatric disorders. Current data only provide an indirect confirmation of this putative role of A(2A) receptors, based on the effects of caffeine (an antagonist of both A(1) and A(2A) receptors) in psychiatric disorders. However, the introduction of A(2A) receptors antagonists in clinics as anti-parkinsonian agents is hoped to bolster our knowledge on the role of A(2A) receptors in mood disorders in the near future.
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Affiliation(s)
- Rodrigo A Cunha
- Center for Neuroscience of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, Portugal.
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Chronic methylphenidate treatment during adolescence increases anxiety-related behaviors and ethanol drinking in adult spontaneously hypertensive rats. Behav Pharmacol 2008; 19:21-7. [DOI: 10.1097/fbp.0b013e3282f3cfbe] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Impulsive choice in a rodent model of attention-deficit/hyperactivity disorder. Behav Brain Res 2008; 187:146-52. [DOI: 10.1016/j.bbr.2007.09.008] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2007] [Revised: 08/15/2007] [Accepted: 09/07/2007] [Indexed: 11/21/2022]
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Wickens JR, Tripp G, Gerhardt GA. Neurobiology of attention-deficit hyperactivity disorder (ADHD): from gene to therapy. J Neurosci Methods 2007; 166:293. [PMID: 17963845 DOI: 10.1016/j.jneumeth.2007.09.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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