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Gungor Aydin A, Adiguzel E. The mesocortical dopaminergic system cannot explain hyperactivity in an animal model of attention deficit hyperactivity disorder (ADHD)- Spontaneously hypertensive rats (SHR). Lab Anim Res 2023; 39:20. [PMID: 37710339 PMCID: PMC10500870 DOI: 10.1186/s42826-023-00172-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 08/24/2023] [Accepted: 09/02/2023] [Indexed: 09/16/2023] Open
Abstract
BACKGROUND Attention deficit hyperactivity disorder (ADHD) is one of the most prevalent neuropsychiatric disorders with morphological brain abnormalities. There is a growing body of evidence that abnormalities in the dopaminergic system may account for ADHD pathogenesis. However, it is not clear whether the dopaminergic system is hyper or hypoactive. To determine whether the DA neurons and/or axons deficiency might be the cause of the postulated dopaminergic hypofunction in spontaneously hypertensive rats (SHR, animal model of ADHD), this study examined the dopaminergic neurons and fibers in the brain tissues of SHRs and Wistar Kyoto rats (WKY, control animals). Here, we performed immunohistochemical tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH) staining on brain sections collected on juveniles from SHR and WKY. Moreover, behavioral testing to examine the hyperactivity in the open field area was also elucidated. RESULTS The mesocortical dopaminergic system appears to be normal in juvenile SHR, as suggested by (i) no alteration in the area density of TH-immunoreactive (TH-ir) dopaminergic neurons in the ventral tegmental area (VTA), (ii) no alterations in the volume density of TH-ir fibers in layer I of the prelimbic (PrL) subregion of medial PFC (mPFC), (iii) no alteration in the percentage of TH-ir dopaminergic fibers in layer I of the PrL subregion of mPFC as revealed by TH and/or DBH immunoreactivity. Furthermore, the SHR showed increased locomotor activity than WKY in the open field test. CONCLUSIONS The demonstration of no alteration in mesocortical dopaminergic neurons and fiber in SHR raises some concern about the position of SHR as an animal model of the inattentive subtype of ADHD. However, these results strengthen this strain as an animal model of hyperactive/impulsive subtype ADHD for future studies that may elucidate the underlying mechanism mediating hyperactivity and test various treatment strategies.
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Affiliation(s)
- Aysegul Gungor Aydin
- Department of Psychology, Rutgers University-New Brunswick, Piscataway, NJ, 08854, USA.
| | - Esat Adiguzel
- Department of Anatomy, Faculty of Medicine, Pamukkale University, 20070, Denizli, Turkey
- Department of Neuroscience, Institute of Health Sciences, Pamukkale University, 20070, Denizli, Turkey
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Suto T, Kato D, Koibuchi I, Arai Y, Ohta J, Hiroki T, Obata H, Saito S. Rat model of attention-deficit hyperactivity disorder exhibits delayed recovery from acute incisional pain due to impaired descending noradrenergic inhibition. Sci Rep 2023; 13:5526. [PMID: 37016045 PMCID: PMC10073110 DOI: 10.1038/s41598-023-32512-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 03/28/2023] [Indexed: 04/06/2023] Open
Abstract
Chronic pain and attention-deficit hyperactivity disorder (ADHD) frequently coexist. However, the common pathology is still unclear. Attenuated noradrenergic endogenous analgesia can produce acute pain chronification, and dysfunction of noradrenergic systems in the nervous system is relevant to ADHD symptoms. Noxious stimuli-induced analgesia (NSIA) is measured to estimate noradrenergic endogenous analgesia in spontaneously hypertensive rats (SHR) as an ADHD model and control. Recovery of pain-related behaviors after paw incision was assessed. Contributions of noradrenergic systems were examined by in vivo microdialysis and immunohistochemistry. The SHR showed attenuated NSIA and needed a more extended period for recovery from acute pain. These results suggest ADHD patients exhibit acute pain chronification due to pre-existing attenuated noradrenergic endogenous analgesia. Immunohistochemistry suggests abnormal noradrenaline turnover and downregulation of the target receptor (alpha2a adrenoceptor). Standard ADHD treatment with atomoxetine restored NSIA and shortened the duration of hypersensitivity after the surgery in the SHR. NSIA protocol activated the locus coeruleus, the origin of spinal noradrenaline, of both strains, but only the control exhibited an increase in spinal noradrenaline. This result suggests dysfunction in the noradrenaline-releasing process and can be recognized as a novel mechanism of attenuation of noradrenergic endogenous analgesia.
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Affiliation(s)
- Takashi Suto
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan.
| | - Daiki Kato
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Ikuya Koibuchi
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Yuki Arai
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Jo Ohta
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Tadanao Hiroki
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Hideaki Obata
- Department of Anesthesiology, Saitama Medical Center, Saitama Medical University, 1981 Kamoda, Kawagoe, Saitama, 350-8550, Japan
| | - Shigeru Saito
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
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Chen HY, Yang CY, Hsieh TH, Peng CW, Chuang LL, Chang YL, Chi HJ, Lee HM, Liang SHY. Effects of transcranial direct current stimulation on improving performance of delayed- reinforcement attentional set-shifting tasks in attention-deficit/hyperactivity disorder rat model. Behav Brain Res 2023; 437:114145. [PMID: 36206819 DOI: 10.1016/j.bbr.2022.114145] [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: 04/20/2022] [Revised: 09/13/2022] [Accepted: 10/02/2022] [Indexed: 11/05/2022]
Abstract
Behavioral flexibility (or set-shifting), which is regulated by the prefrontal cortex (PFC), is often impaired in patients with attention-deficit/hyperactivity disorder (ADHD), which is characterized by poor inhibitory control and reinforcement learning. Transcranial direct current stimulation (tDCS) has been proposed as a means of noninvasive brain stimulation and a potential therapeutic tool for modulating behavioral flexibility. Animal studies can pave the way to know if tDCS application can potentially benefit rule- and goal-based activities in ADHD. Spontaneously hypertensive rats (SHRs) and inbred Wistar-Kyoto (WKY) rats were used as an animal model of ADHD and controls, respectively, and their strategy set-shifting abilities, including initial discrimination, set-shifting, and reversal learning tasks under 0-s or 15-s reinforcer delivery delay conditions, were evaluated. The tDCS treatment had a limited effect on the performance of the SHRs and WKY rats in initial discrimination task under 0-s delay condition. Under the 15-s delay condition, the SHRs had longer lever-press reaction times and/or more trial omissions than the WKY rats did when completing set-shifting and reversal-learning tasks. Among the SHRs, tDCS treatment improved the rats' reaction times and/or reduced their trial omissions in the set-shifting and reversal-learning tasks. Although tDCS may improve delayed reinforcement learning set-shifting performance in SHRs, further studies are required to clarify the responsible mechanism.
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Affiliation(s)
- Hsin-Yung Chen
- Department of Occupational Therapy & Graduate Institute of Behavioral Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Department of Neurology and Dementia Center, Chang Gung Memorial Hospital at Taoyuan, Taoyuan, Taiwan
| | - Chia-Yen Yang
- Department of Biomedical Engineering, Ming-Chuan University, Taoyuan, Taiwan
| | - Tsung-Hsun Hsieh
- School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan; Healthy Aging Research Center, Chang Gung University, Taoyuan 33302, Taiwan
| | - Chih-Wei Peng
- Department of Biomedical Engineering, Taipei Medical University, Taipei, Taiwan
| | - Li-Ling Chuang
- School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan
| | - Ying-Ling Chang
- School and Graduate Institute of Traditional Chinese Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Division of Chinese Internal Medicine, Center for Traditional Chinese Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Huang-Ju Chi
- Department of Neurology and Dementia Center, Chang Gung Memorial Hospital at Taoyuan, Taoyuan, Taiwan
| | - Hsin-Min Lee
- Department of Physical Therapy, College of Medicine, I-Shou University, Kaohsiung, Taiwan.
| | - Sophie Hsin-Yi Liang
- Section of Department of Child and Adolescent Psychiatry, Department of Psychiatry, Chang Gung Memorial Hospital at Taoyuan and Chang Gung University College of Medicine, Taoyuan, Taiwan.
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Mathieson E, Irving C, Koberna S, Nicholson M, Otto MW, Kantak KM. Role of preexisting inhibitory control deficits vs. drug use history in mediating insensitivity to aversive consequences in a rat model of polysubstance use. Psychopharmacology (Berl) 2022; 239:2377-2394. [PMID: 35391547 PMCID: PMC8989405 DOI: 10.1007/s00213-022-06134-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 03/30/2022] [Indexed: 10/26/2022]
Abstract
RATIONALE The nature and predictors of insensitivity to aversive consequences of heroin + cocaine polysubstance use are not well characterized. OBJECTIVES Translational methods incorporating a tightly controlled animal model of drug self-administration and measures of inhibitory control and avoidance behavior might be helpful for clarifying this issue. METHODS The key approach for distinguishing potential contributions of pre-existing inhibitory control deficits vs. drug use history in meditating insensitivity to aversive consequences was comparison of two rat strains: Wistar (WIS/Crl), an outbred strain, and the spontaneously hypertensive rat (SHR/NCrl), an inbred strain shown previously to exhibit heightened cocaine and heroin self-administration and poor inhibitory control relative to WIS/Crl. RESULTS In separate tasks, SHR/NCrl displayed greater impulsive action and compulsive-like behavior than WIS/Crl prior to drug exposure. Under two different schedules of drug delivery, SHR/NCrl self-administered more cocaine than WIS/Crl, but self-administered a similar amount of heroin + cocaine as WIS/Crl. When half the session cycles were punished by random foot shock, SHR/NCrl initially were less sensitive to punishment than WIS/Crl when self-administering cocaine, but were similarly insensitive to punishment when self-administering heroin + cocaine. Based on correlation analyses, only trait impulsivity predicted avoidance capacity in rats self-administering cocaine and receiving yoked-saline. In contrast, only amount of drug use predicted avoidance capacity in rats self-administering heroin + cocaine. Additionally, baseline drug seeking and taking predicted punishment insensitivity in rats self-administering cocaine or heroin + cocaine. CONCLUSIONS Based on the findings revealed in this animal model, human laboratory research concerning the nature and predictors of insensitivity to aversive consequences in heroin and cocaine polysubstance vs. monosubstance users is warranted.
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Affiliation(s)
- Elon Mathieson
- Department of Psychological and Brain Sciences, Boston University, 64 Cummington Mall, Boston, MA, 02215, USA
| | - Carolyn Irving
- Department of Psychological and Brain Sciences, Boston University, 64 Cummington Mall, Boston, MA, 02215, USA
| | - Sarah Koberna
- Department of Psychological and Brain Sciences, Boston University, 64 Cummington Mall, Boston, MA, 02215, USA
| | - Megan Nicholson
- Department of Psychological and Brain Sciences, Boston University, 64 Cummington Mall, Boston, MA, 02215, USA
| | - Michael W Otto
- Department of Psychological and Brain Sciences, Boston University, 64 Cummington Mall, Boston, MA, 02215, USA
| | - Kathleen M Kantak
- Department of Psychological and Brain Sciences, Boston University, 64 Cummington Mall, Boston, MA, 02215, USA.
- Center for Systems Neuroscience, Boston University, Boston, MA, USA.
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Kantak KM. Rodent models of attention-deficit hyperactivity disorder: An updated framework for model validation and therapeutic drug discovery. Pharmacol Biochem Behav 2022; 216:173378. [DOI: 10.1016/j.pbb.2022.173378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 03/22/2022] [Accepted: 03/28/2022] [Indexed: 01/21/2023]
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Park D, Mabunga DFN, Adil KJ, Ryu O, Valencia S, Kim R, Kim HJ, Cheong JH, Kwon KJ, Kim HY, Han SH, Jeon SJ, Shin CY. Synergistic efficacy and diminished adverse effect profile of composite treatment of several ADHD medications. Neuropharmacology 2021; 187:108494. [PMID: 33587920 DOI: 10.1016/j.neuropharm.2021.108494] [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: 05/07/2020] [Revised: 01/05/2021] [Accepted: 02/07/2021] [Indexed: 11/26/2022]
Abstract
Although attention-deficit/hyperactivity disorder (ADHD) is widely studied, problems regarding the adverse effect risks and non-responder problems still need to be addressed. Combination pharmacotherapy using standard dose regimens of existing medication is currently being practiced mainly to augment the therapeutic efficacy of each drug. The idea of combining different pharmacotherapies with different molecular targets to alleviate the symptoms of ADHD and its comorbidities requires scientific evidence, necessitating the investigation of their therapeutic efficacy and the mechanisms underlying the professed synergistic effects. Here, we injected male ICR mice with MK-801 to induce ADHD behavioral condition. We then modeled a "combined drug" using sub-optimal doses of methylphenidate, atomoxetine, and fluoxetine and investigated the combined treatment effects in MK-801-treated mice. No sub-optimal dose monotherapy alleviated ADHD behavioral condition in MK-801-treated mice. However, treatment with the combined drug attenuated the impaired behavior of MK-801-treated animals. Growth impediment, sleep disturbances, or risk of substance abuse were not observed in mice treated subchronically with the combined drugs. Finally, we observed that the combined ADHD drug rescued alterations in p-AKT and p-ERK1/2 levels in the prefrontal cortex and hippocampus, respectively, of MK-801-treated mice. Our results provide experimental evidence of a possible new pharmacotherapy option in ameliorating the ADHD behavioral condition without the expected adverse effects. The detailed mechanism of action underlying the synergistic therapeutic efficacy and reduced adverse reaction by combinatorial drug treatment should be investigated further in future studies.
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Affiliation(s)
- Donghyun Park
- School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul, 05029, Republic of Korea
| | - Darine Froy N Mabunga
- School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul, 05029, Republic of Korea
| | - Keremkleroo Jym Adil
- School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul, 05029, Republic of Korea
| | - Onjeon Ryu
- School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul, 05029, Republic of Korea
| | - Schley Valencia
- School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul, 05029, Republic of Korea
| | - Ryeongeun Kim
- School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul, 05029, Republic of Korea
| | - Hee Jin Kim
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarangro, Nowon-gu, Seoul, 01795, Republic of Korea
| | - Jae Hoon Cheong
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarangro, Nowon-gu, Seoul, 01795, Republic of Korea
| | - Kyung Ja Kwon
- School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul, 05029, Republic of Korea
| | - Hahn Young Kim
- Department of Neurology, Konkuk University Medical Center, Center for Geriatric Neuroscience Research, Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Seoul, 05029, Republic of Korea
| | - Seol-Heui Han
- Department of Neurology, Konkuk University Medical Center, Center for Geriatric Neuroscience Research, Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Seoul, 05029, Republic of Korea
| | - Se Jin Jeon
- School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul, 05029, Republic of Korea; TriNeuro Inc., 120 Neungdong-ro, Gwangjin-gu, Seoul, 05029, Republic of Korea.
| | - Chan Young Shin
- School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul, 05029, Republic of Korea; TriNeuro Inc., 120 Neungdong-ro, Gwangjin-gu, Seoul, 05029, Republic of Korea.
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7
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Kantak KM. Adolescent-onset vs. adult-onset cocaine use: Impact on cognitive functioning in animal models and opportunities for translation. Pharmacol Biochem Behav 2020; 196:172994. [PMID: 32659242 DOI: 10.1016/j.pbb.2020.172994] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/25/2020] [Accepted: 07/02/2020] [Indexed: 01/03/2023]
Abstract
Animal models are poised to make key contributions to the study of cognitive deficits associated with chronic cocaine use in people. Advantages of animal models include use of a longitudinal experimental design that can control for drug use history and onset-age, sex, drug consumption, and abstinence duration. Twenty-two studies were reviewed (13 in adult male rats, 5 in adolescent vs. adult male rats, 3 in adult male monkeys, and 1 in adult female monkeys), and it was demonstrated repeatedly that male animals with adult-onset cocaine self-administration exposure had impairments in sustained attention, decision making, stimulus-reward learning, working memory, and cognitive flexibility, but not habit learning and spatial learning and memory. These findings have translational relevance because adult cocaine users exhibit a similar range of cognitive deficits. In the limited number of studies available, male rats self-administering cocaine during adolescence were less susceptible than adults to impairment in cognitive flexibility, stimulus-reward learning, and decision making, but were more susceptible than adults to impairment in working memory, a finding also reported in the few studies performed in early-onset cocaine users. These findings suggest that animal models can help fill an unmet need for investigating important but yet-to-be-fully-addressed research questions in people. Research priorities include further investigation of differences between adolescents and adults as well as between males and females following chronic cocaine self-administration. A comprehensive understanding of the broad range of cognitive consequences of chronic cocaine use and the role of developmental plasticity can be of value for improving neuropsychological recovery efforts.
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Affiliation(s)
- Kathleen M Kantak
- Department of Psychological and Brain Sciences, Boston University, Boston, MA 02215, United States of America.
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Leffa DT, Panzenhagen AC, Salvi AA, Bau CHD, Pires GN, Torres ILS, Rohde LA, Rovaris DL, Grevet EH. Systematic review and meta-analysis of the behavioral effects of methylphenidate in the spontaneously hypertensive rat model of attention-deficit/hyperactivity disorder. Neurosci Biobehav Rev 2019; 100:166-179. [PMID: 30826386 DOI: 10.1016/j.neubiorev.2019.02.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Revised: 02/27/2019] [Accepted: 02/27/2019] [Indexed: 12/19/2022]
Abstract
The spontaneously hypertensive rats (SHR) are the most widely used model for ADHD. While face and construct validity are consolidated, questions remain about the predictive validity of the SHR model. We aim at summarizing the evidence for the predictive validity of SHR by evaluating its ability to respond to methylphenidate (MPH), the most well documented treatment for ADHD. A systematic review was carried out to identify studies evaluating MPH effects on SHR behavior. Studies (n=36) were grouped into locomotion, attention, impulsivity or memory, and a meta-analysis was performed. Meta-regression, sensitivity, heterogeneity, and publication bias analyses were also conducted. MPH increased attentional and mnemonic performances in the SHR model and decreased impulsivity in a dose-dependent manner. However, MPH did not reduce hyperactivity in low and medium doses, while increased locomotor activity in high doses. Thus, since the paradoxical effect of stimulant in reducing hyperactivity was not observed in the SHR model, our study does not fully support the predictive validity of SHR, questioning their validity as an animal model for ADHD.
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Affiliation(s)
- Douglas T Leffa
- Post-Graduate Program in Medicine: Medical Sciences, School of Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Laboratory of Pain Pharmacology and Neuromodulation: Pre-clinical studies - Pharmacology Department, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Alana C Panzenhagen
- Department of Genetics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; ADHD Outpatient Program, Hospital de Clínicas de Porto Alegre, Brazil
| | - Artur A Salvi
- Laboratory of Pain Pharmacology and Neuromodulation: Pre-clinical studies - Pharmacology Department, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Claiton H D Bau
- Department of Genetics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; ADHD Outpatient Program, Hospital de Clínicas de Porto Alegre, Brazil; Department of Psychiatry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Gabriel N Pires
- Departamento de Psicobiologia, Universidade Federal de São Paulo, São Paulo, Brazil; Department of Physiological Sciences, Santa Casa de São Paulo School of Medical Sciences, São Paulo, Brazil
| | - Iraci L S Torres
- Laboratory of Pain Pharmacology and Neuromodulation: Pre-clinical studies - Pharmacology Department, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Animal Experimentation Unit - GPPG - Hospital de Clínicas de Porto Alegre - Porto, Alegre, Brazil
| | - Luis A Rohde
- ADHD Outpatient Program, Hospital de Clínicas de Porto Alegre, Brazil; Department of Psychiatry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; National Institute of Developmental Psychiatry for Children and Adolescents, Brazil
| | - Diego L Rovaris
- Department of Genetics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; ADHD Outpatient Program, Hospital de Clínicas de Porto Alegre, Brazil; Department of Psychiatry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
| | - Eugenio H Grevet
- ADHD Outpatient Program, Hospital de Clínicas de Porto Alegre, Brazil; Department of Psychiatry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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Newman LA, Baraiolo J, Mokler DJ, Rabinowitz AG, Galler JR, McGaughy JA. Prenatal Protein Malnutrition Produces Resistance to Distraction Similar to Noradrenergic Deafferentation of the Prelimbic Cortex in a Sustained Attention Task. Front Neurosci 2019; 13:123. [PMID: 30853881 PMCID: PMC6396814 DOI: 10.3389/fnins.2019.00123] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 02/04/2019] [Indexed: 12/03/2022] Open
Abstract
Exposure to malnutrition early in development increases likelihood of neuropsychiatric disorders, affective processing disorders, and attentional problems later in life. Many of these impairments are hypothesized to arise from impaired development of the prefrontal cortex. The current experiments examine the impact of prenatal malnutrition on the noradrenergic and cholinergic axons in the prefrontal cortex to determine if these changes contribute to the attentional deficits seen in prenatal protein malnourished rats (6% casein vs. 25% casein). Because prenatally malnourished animals had significant decreases in noradrenergic fibers in the prelimbic cortex with spared innervation in the anterior cingulate cortex and showed no changes in acetylcholine innervation of the prefrontal cortex, we compared deficits produced by malnutrition to those produced in adult rats by noradrenergic lesions of the prelimbic cortex. All animals were able to perform the baseline sustained attention task accurately. However, with the addition of visual distractors to the sustained attention task, animals that were prenatally malnourished and those that were noradrenergically lesioned showed cognitive rigidity, i.e., were less distractible than control animals. All groups showed similar changes in behavior when exposed to withholding reinforcement, suggesting specific attentional impairments rather than global difficulties in understanding response rules, bottom-up perceptual problems, or cognitive impairments secondary to dysfunction in sensitivity to reinforcement contingencies. These data suggest that prenatal protein malnutrition leads to deficits in noradrenergic innervation of the prelimbic cortex associated with cognitive rigidity.
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Affiliation(s)
- Lori A. Newman
- Department of Psychology, University of New Hampshire, Durham, NH, United States
- Department of Psychological Science, Vassar College, Poughkeepsie, NY, United States
| | - Jaime Baraiolo
- Department of Psychology, University of New Hampshire, Durham, NH, United States
| | - David J. Mokler
- Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, ME, United States
| | | | - Janina R. Galler
- Department of Psychiatry, Harvard Medical School, Boston, MA, United States
- Division of Pediatric Gastroenterology and Nutrition, Mucosal Immunology and Biology Research Center, MassGeneral Hospital for Children, Boston, MA, United States
| | - Jill A. McGaughy
- Department of Psychology, University of New Hampshire, Durham, NH, United States
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Natividad LA, Steinman MQ, Laredo SA, Irimia C, Polis IY, Lintz R, Buczynski MW, Martin-Fardon R, Roberto M, Parsons LH. Phosphorylation of calcium/calmodulin-dependent protein kinase II in the rat dorsal medial prefrontal cortex is associated with alcohol-induced cognitive inflexibility. Addict Biol 2018; 23:1117-1129. [PMID: 28940879 PMCID: PMC5862723 DOI: 10.1111/adb.12568] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Repeated cycles of alcohol [ethanol (EtOH)] intoxication and withdrawal dysregulate excitatory glutamatergic systems in the brain and induce neuroadaptations in the medial prefrontal cortex (mPFC) that contribute to cognitive dysfunction. The mPFC is composed of subdivisions that are functionally distinct, with dorsal regions facilitating drug-cue associations and ventral regions modulating new learning in the absence of drug. A key modulator of glutamatergic activity is the holoenzyme calcium/calmodulin-dependent protein kinase II (CaMKII) that phosphorylates ionotropic glutamate receptors. Here, we examined the hypothesis that abstinence from chronic intermittent EtOH (CIE) exposure dysregulates CaMKII activity in the mPFC to impair cognitive flexibility. We used an operant model of strategy set shifting in male Long-Evans rats demonstrating reduced susceptibility to trial omissions during performance in a visual cue-guided task versus albino strains. Relative to naïve controls, rats experiencing approximately 10 days of abstinence from CIE vapor exposure demonstrated impaired performance during a procedural shift from visual cue to spatial location discrimination. Phosphorylation of CaMKII subtype α was upregulated in the dorsal, but not ventral mPFC of CIE-exposed rats, and was positively correlated with perseverative-like responding during the set shift. The findings suggest that abstinence from CIE exposure induces an undercurrent of kinase activity (e.g. CaMKII), which may promote aberrant glutamatergic responses in select regions of the mPFC. Given the role of the mPFC in modulating executive control of behavior, we propose that increased CaMKII subtype α activity reflects a dysregulated 'top-down' circuit that interferes with adaptive behavioral performance under changing environmental demands.
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Affiliation(s)
| | | | - Sarah A. Laredo
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California, 92037, USA
| | - Cristina Irimia
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California, 92037, USA
| | - Ilham Y. Polis
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California, 92037, USA
| | - Robert Lintz
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California, 92037, USA
| | - Matthew W. Buczynski
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California, 92037, USA
| | - Rémi Martin-Fardon
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California, 92037, USA
| | - Marisa Roberto
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California, 92037, USA
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Chronic atomoxetine treatment during adolescence does not influence decision-making on a rodent gambling task, but does modulate amphetamine's effect on impulsive action in adulthood. Behav Pharmacol 2017; 27:350-63. [PMID: 26650252 DOI: 10.1097/fbp.0000000000000203] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In addition to the symptoms of inattention, hyperactivity, and impulsivity, individuals with attention deficit hyperactivity disorder exhibit impaired performance on tests of real-world cost/benefit decision-making. Atomoxetine, a nonstimulant drug approved for the treatment of attention deficit hyperactivity disorder, is a selective norepinephrine reuptake inhibitor administered chronically during adolescence, a time during which the frontal brain regions necessary for executive function undergo extensive maturation. This treatment protocol can affect behavior well into adulthood, but whether it produces long-term changes in complex decision-making has not been investigated. Twenty-four Long-Evans rats were administered saline or 1.0 mg/kg atomoxetine daily from postnatal day 40 to 54. Two weeks after treatment, the adult rats were trained and assessed on the rodent gambling task, in which the animals chose from four options varying in reward, punishment, and uncertainty. Impulsive action was also measured by recording the number of premature responses made. Regardless of the treatment administered during adolescence, rats learned to favor the advantageous options characterized by small, low-penalty rewards in lieu of the larger, higher-penalty reward options. Rodent gambling task performance was then assessed following acute treatment with atomoxetine (0.1-1.0 mg/kg) and amphetamine (0.3-1.5 mg/kg). Across groups, the highest dose of atomoxetine impaired decision-making and decreased premature responding at all doses tested. Amphetamine also impaired choice performance, but selectively increased impulsive action in rats that had previously received atomoxetine treatment during adolescence. These findings contribute to our understanding of the long-term effects associated with chronic adolescent atomoxetine exposure and suggest that this treatment does not alter decision-making under conditions of risk and uncertainty in adulthood.
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12
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Blockade of α2-adrenergic receptors in prelimbic cortex: impact on cocaine self-administration in adult spontaneously hypertensive rats following adolescent atomoxetine treatment. Psychopharmacology (Berl) 2017; 234:2897-2909. [PMID: 28730282 PMCID: PMC5693724 DOI: 10.1007/s00213-017-4681-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 06/25/2017] [Indexed: 12/17/2022]
Abstract
RATIONALE Research with the spontaneously hypertensive rat (SHR) model of attention deficit/hyperactivity disorder demonstrated that chronic methylphenidate treatment during adolescence increased cocaine self-administration established during adulthood under a progressive ratio (PR) schedule. Compared to vehicle, chronic atomoxetine treatment during adolescence failed to increase cocaine self-administration under a PR schedule in adult SHR. OBJECTIVES We determined if enhanced noradrenergic transmission at α2-adrenergic receptors within prefrontal cortex contributes to this neutral effect of adolescent atomoxetine treatment in adult SHR. METHODS Following treatment from postnatal days 28-55 with atomoxetine (0.3 mg/kg) or vehicle, adult male SHR and control rats from Wistar-Kyoto (WKY) and Wistar (WIS) strains were trained to self-administer 0.3 mg/kg cocaine. Self-administration performance was evaluated under a PR schedule of cocaine delivery following infusion of the α2-adrenergic receptor antagonist idazoxan (0 and 10-56 μg/side) directly into prelimbic cortex. RESULTS Adult SHR attained higher PR break points and had greater numbers of active lever responses and infusions than WKY and WIS. Idazoxan dose-dependently increased PR break points and active lever responses in SHR following adolescent atomoxetine vs. vehicle treatment. Behavioral changes were negligible after idazoxan pretreatment in SHR following adolescent vehicle or in WKY and WIS following adolescent atomoxetine or vehicle. CONCLUSIONS α2-Adrenergic receptor blockade in prelimbic cortex of SHR masked the expected neutral effect of adolescent atomoxetine on adult cocaine self-administration behavior. Moreover, greater efficacy of acute idazoxan challenge in adult SHR after adolescent atomoxetine relative to vehicle is consistent with the idea that chronic atomoxetine may downregulate presynaptic α2A-adrenergic autoreceptors in SHR.
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13
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Fole A, Miguéns M, Morales L, González-Martín C, Ambrosio E, Del Olmo N. Lewis and Fischer 344 rats as a model for genetic differences in spatial learning and memory: Cocaine effects. Prog Neuropsychopharmacol Biol Psychiatry 2017; 76:49-57. [PMID: 28263897 DOI: 10.1016/j.pnpbp.2017.02.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 02/21/2017] [Accepted: 02/28/2017] [Indexed: 01/31/2023]
Abstract
Lewis (LEW) and Fischer 344 (F344) rats are considered a model of genetic vulnerability to drug addiction. We previously showed important differences in spatial learning and memory between them, but in contrast with previous experiments demonstrating cocaine-induced enhanced learning in Morris water maze (MWM) highly demanding tasks, the eight-arm radial maze (RAM) performance was not modified either in LEW or F344 rats after chronic cocaine treatment. In the present work, chronically cocaine-treated LEW and F344 adult rats have been evaluated in learning and memory performance using the Y-maze, two RAM protocols that differ in difficulty, and a reversal protocol that tests cognitive flexibility. After one of the RAM protocols, we quantified dendritic spine density in hippocampal CA1 neurons and compared it to animals treated with cocaine but not submitted to RAM. LEW cocaine treated rats showed a better performance in the Y maze than their saline counterparts, an effect that was not evident in the F344 strain. F344 rats significantly took more time to learn the RAM task and made a greater number of errors than LEW animals in both protocols tested, whereas cocaine treatment induced deleterious effects in learning and memory in the highly difficult protocol. Moreover, hippocampal spine density was cocaine-modulated in LEW animals whereas no effects were found in F344 rats. We propose that differences in addictive-like behavior between LEW and F344 rats could be related to differences in hippocampal learning and memory processes that could be on the basis of individual vulnerability to cocaine addiction.
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Affiliation(s)
- Alberto Fole
- Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Spain
| | - Miguel Miguéns
- Departamento de Psicología Básica I, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Spain
| | - Lidia Morales
- Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Spain
| | - Carmen González-Martín
- Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Spain
| | - Emilio Ambrosio
- Departamento de Psicobiología, Facultad de Psicología, Universidad Nacional de Educación a Distancia (UNED), Spain
| | - Nuria Del Olmo
- Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad CEU-San Pablo, Spain.
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14
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Amodeo LR, Jacobs-Brichford E, McMurray MS, Roitman JD. Acute and long-term effects of adolescent methylphenidate on decision-making and dopamine receptor mRNA expression in the orbitofrontal cortex. Behav Brain Res 2017; 324:100-108. [PMID: 28212944 DOI: 10.1016/j.bbr.2017.02.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 02/01/2017] [Accepted: 02/11/2017] [Indexed: 01/09/2023]
Abstract
Though commonly used as a treatment for ADHD, the psychostimulant methylphenidate (MPH) is also misused and abused in adolescence in both clinical and general populations. Although MPH acts via pathways activated by other drugs of abuse, the short- and long-term effects of MPH on reward processing in learning and decision-making are not clearly understood. We examined the effect of adolescent MPH treatment on a battery of reward-directed behaviors both in adolescence during its administration and in adulthood after its discontinuation. We further measured whether MPH had lasting effects on dopamine receptor mRNA expression in orbitofrontal cortex (OFC) that may correspond with behavior. Long-Evans rats were injected with MPH (0, 1, 2.5, or 5mg/kg IP) twice daily from middle to late adolescence (PD38-57). During adolescence, the high dose of MPH reduced preference for large rewards in a Reward Magnitude Discrimination task, but did not affect preference for smaller-sooner rewards in a Delay Discounting task. In adulthood, after discontinuation of MPH, animals previously treated with the moderate dose of MPH showed improved acquisition, but not reversal, in a Reversal Learning task. MPH exposure did not increase preference for large-risky rewards in a Risk task in adulthood. We then quantified mRNA expression of D1, D2, and D3 receptors in the OFC using qPCR. MPH increased mRNA expression of dopamine D3 receptor subtype, but not D1 or D2. Overall, these results indicate that MPH has both immediate and lasting effects on reward-dependent learning and decisions, as well as dopaminergic function in rodents.
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Affiliation(s)
- Leslie R Amodeo
- Department of Psychology, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607, USA
| | - Eliza Jacobs-Brichford
- Department of Psychology, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607, USA
| | - Matthew S McMurray
- Department of Psychology, Miami University, 90 N Patterson Ave, Oxford, OH 45056, USA
| | - Jamie D Roitman
- Department of Psychology, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607, USA; Laboratory of Integrative Neuroscience, University of Illinois at Chicago,1007 West Harrison Street, Chicago, IL 60607, USA.
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15
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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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16
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Kantak KM, Dwoskin LP. Necessity for research directed at stimulant type and treatment-onset age to access the impact of medication on drug abuse vulnerability in teenagers with ADHD. Pharmacol Biochem Behav 2016; 145:24-6. [PMID: 27012495 DOI: 10.1016/j.pbb.2016.03.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 03/17/2016] [Accepted: 03/19/2016] [Indexed: 01/08/2023]
Affiliation(s)
- Kathleen M Kantak
- Department of Psychological and Brain Sciences, Boston University, Boston, MA 02215, USA.
| | - Linda P Dwoskin
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, USA
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17
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Bradshaw SE, Agster KL, Waterhouse BD, McGaughy JA. Age-related changes in prefrontal norepinephrine transporter density: The basis for improved cognitive flexibility after low doses of atomoxetine in adolescent rats. Brain Res 2016; 1641:245-57. [PMID: 26774596 DOI: 10.1016/j.brainres.2016.01.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 12/14/2015] [Accepted: 01/01/2016] [Indexed: 11/19/2022]
Abstract
Adolescence is a period of major behavioral and brain reorganization. As diagnoses and treatment of disorders like attention deficit hyperactivity disorder (ADHD) often occur during adolescence, it is important to understand how the prefrontal cortices change and how these changes may influence the response to drugs during development. The current study uses an adolescent rat model to study the effect of standard ADHD treatments, atomoxetine and methylphenidate on attentional set shifting and reversal learning. While both of these drugs act as norepinephrine reuptake inhibitors, higher doses of atomoxetine and all doses of methylphenidate also block dopamine transporters (DAT). Low doses of atomoxetine, were effective at remediating cognitive rigidity found in adolescents. In contrast, methylphenidate improved performance in rats unable to form an attentional set due to distractibility but was without effect in normal subjects. We also assessed the effects of GBR 12909, a selective DAT inhibitor, but found no effect of any dose on behavior. A second study in adolescent rats investigated changes in norepinephrine transporter (NET) and dopamine beta hydroxylase (DBH) density in five functionally distinct sub-regions of the prefrontal cortex: infralimbic, prelimbic, anterior cingulate, medial and lateral orbitofrontal cortices. These regions are implicated in impulsivity and distractibility. We found that NET, but not DBH, changed across adolescence in a regionally selective manner. The prelimbic cortex, which is critical to cognitive rigidity, and the lateral orbitofrontal cortex, critical to reversal learning and some forms of response inhibition, showed higher levels of NET at early than mid- to late adolescence. This article is part of a Special Issue entitled SI: Noradrenergic System.
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Affiliation(s)
- Sarah E Bradshaw
- Department of Psychology, University of New Hampshire, Durham, NH 03824, United States
| | - Kara L Agster
- Department of Neurobiology and Anatomy, Drexel College of Medicine, Philadelphia, PA 19129, United States
| | - Barry D Waterhouse
- Department of Neurobiology and Anatomy, Drexel College of Medicine, Philadelphia, PA 19129, United States
| | - Jill A McGaughy
- Department of Psychology, University of New Hampshire, Durham, NH 03824, United States.
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18
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Adolescent methylphenidate treatment differentially alters adult impulsivity and hyperactivity in the Spontaneously Hypertensive Rat model of ADHD. Pharmacol Biochem Behav 2015; 141:66-77. [PMID: 26657171 DOI: 10.1016/j.pbb.2015.12.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 09/30/2015] [Accepted: 12/01/2015] [Indexed: 12/30/2022]
Abstract
Impulsivity and hyperactivity are two facets of attention deficit/hyperactivity disorder (ADHD). Impulsivity is expressed as reduced response inhibition capacity, an executive control mechanism that prevents premature execution of an intermittently reinforced behavior. During methylphenidate treatment, impulsivity and hyperactivity are decreased in adolescents with ADHD, but there is little information concerning levels of impulsivity and hyperactivity in adulthood after adolescent methylphenidate treatment is discontinued. The current study evaluated impulsivity, hyperactivity as well as cocaine sensitization during adulthood after adolescent methylphenidate treatment was discontinued in the Spontaneously Hypertensive Rat (SHR) model of ADHD. Treatments consisted of oral methylphenidate (1.5mg/kg) or water vehicle provided Monday-Friday from postnatal days 28-55. During adulthood, impulsivity was measured in SHR and control strains (Wistar Kyoto and Wistar rats) using differential reinforcement of low rate (DRL) schedules. Locomotor activity and cocaine sensitization were measured using the open-field assay. Adult SHR exhibited decreased efficiency of reinforcement under the DRL30 schedule and greater levels of locomotor activity and cocaine sensitization compared to control strains. Compared to vehicle, methylphenidate treatment during adolescence reduced hyperactivity in adult SHR, maintained the lower efficiency of reinforcement, and increased burst responding under DRL30. Cocaine sensitization was not altered following adolescent methylphenidate in adult SHR. In conclusion, adolescent treatment with methylphenidate followed by discontinuation in adulthood had a positive benefit by reducing hyperactivity in adult SHR rats; however, increased burst responding under DRL compared to SHR given vehicle, i.e., elevated impulsivity, constituted an adverse consequence associated with increased risk for cocaine abuse liability.
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19
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Adolescent D-amphetamine treatment in a rodent model of ADHD: Pro-cognitive effects in adolescence without an impact on cocaine cue reactivity in adulthood. Behav Brain Res 2015; 297:165-79. [PMID: 26467602 DOI: 10.1016/j.bbr.2015.10.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 10/02/2015] [Accepted: 10/06/2015] [Indexed: 12/17/2022]
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is comorbid with cocaine abuse. Whereas initiating ADHD medication in childhood does not alter later cocaine abuse risk, initiating medication during adolescence may increase risk. Preclinical work in the Spontaneously Hypertensive Rat (SHR) model of ADHD found that adolescent methylphenidate increased cocaine self-administration in adulthood, suggesting a need to identify alternatively efficacious medications for teens with ADHD. We examined effects of adolescent d-amphetamine treatment on strategy set shifting performance during adolescence and on cocaine self-administration and reinstatement of cocaine-seeking behavior (cue reactivity) during adulthood in male SHR, Wistar-Kyoto (inbred control), and Wistar (outbred control) rats. During the set shift phase, adolescent SHR needed more trials and had a longer latency to reach criterion, made more regressive errors and trial omissions, and exhibited slower and more variable lever press reaction times. d-Amphetamine improved performance only in SHR by increasing choice accuracy and decreasing errors and latency to criterion. In adulthood, SHR self-administered more cocaine, made more cocaine-seeking responses, and took longer to extinguish lever responding than control strains. Adolescent d-amphetamine did not alter cocaine self-administration in adult rats of any strain, but reduced cocaine seeking during the first of seven reinstatement test sessions in adult SHR. These findings highlight utility of SHR in modeling cognitive dysfunction and comorbid cocaine abuse in ADHD. Unlike methylphenidate, d-amphetamine improved several aspects of flexible learning in adolescent SHR and did not increase cocaine intake or cue reactivity in adult SHR. Thus, adolescent d-amphetamine was superior to methylphenidate in this ADHD model.
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20
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D-amphetamine improves attention performance in adolescent Wistar, but not in SHR rats, in a two-choice visual discrimination task. Psychopharmacology (Berl) 2015; 232:3269-86. [PMID: 26037943 DOI: 10.1007/s00213-015-3974-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 05/24/2015] [Indexed: 01/30/2023]
Abstract
The validity of spontaneous hypertensive rat (SHR) as a model of attention deficit hyperactivity disorder (ADHD) has been explored by comparing SHR with Wistar rats in a test of attention, the two-choice visual discrimination task (2-CVDT). Animals were 4-5 weeks old during the training phase of the experiment and 6-7 weeks old during the testing phase in which they were tested with D-amphetamine, a stimulant drug used for the treatment of ADHD. As compared to Wistar, SHR showed a slightly better attention performance, a slightly lower impulsivity level, and a lower general activity during the training phase, but these differences disappeared or lessened thereafter, during the testing phase. D-amphetamine (0.5, 1 mg/kg) improved attention performance in Wistar, but not in SHR, and did not modify impulsivity and activity in the two strains. In conclusion, the present study did not demonstrate that SHR represents a valid model of ADHD, since it did not show face validity regarding the behavioral symptoms of ADHD and predictive validity regarding the effect of a compound used for the treatment of ADHD. On the other hand, this study showed that the 2-CVDT may represent a suitable tool for evaluating in adolescent Wistar rats the effect on attention of compounds intended for the treatment of ADHD.
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21
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Blum K, Febo M, Smith DE, Roy AK, Demetrovics Z, Cronjé FJ, Femino J, Agan G, Fratantonio JL, Pandey SC, Badgaiyan RD, Gold MS. Neurogenetic and epigenetic correlates of adolescent predisposition to and risk for addictive behaviors as a function of prefrontal cortex dysregulation. J Child Adolesc Psychopharmacol 2015; 25:286-92. [PMID: 25919973 PMCID: PMC4442554 DOI: 10.1089/cap.2014.0146] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
As addiction professionals, we are becoming increasingly concerned about preteenagers and young adults' involvement with substance abuse as a way of relieving stress and anger. The turbulent underdeveloped central nervous system, especially in the prefrontal cortex (PFC), provides impetus to not only continue important neuroimaging studies in both human and animal models, but also to encourage preventive measures and cautions embraced by governmental and social media outlets. It is well known that before people reach their 20s, PFC development is undergoing significant changes and, as such, hijacks appropriate decision making in this population. We are further proposing that early genetic testing for addiction risk alleles will offer important information that could potentially be utilized by their parents and caregivers prior to use of psychoactive drugs by these youth. Understandably, family history, parenting styles, and attachment may be modified by various reward genes, including the known bonding substances oxytocin/vasopressin, which effect dopaminergic function. Well-characterized neuroimaging studies continue to reflect region-specific differential responses to drugs and food (including other non-substance-addictive behaviors) via either "surfeit" or "deficit." With this in mind, we hereby propose a "reward deficiency solution system" that combines early genetic risk diagnosis, medical monitoring, and nutrigenomic dopamine agonist modalities to combat this significant global dilemma that is preventing our youth from leading normal productive lives, which will in turn make them happier.
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Affiliation(s)
- Kenneth Blum
- Department of Psychiatry and McKnight Brain Institute, University of Florida, College of Medicine, Gainesville, Florida.,Division of Addiction Services, Dominion Diagnostics, LLC, North Kingstown, Rhode Island.,Department of Addiction Research & Therapy, Malibu Beach Recovery Center, Malibu Beach, California.,Human Integrative Services & Translational Science, Department of Psychiatry, University of Vermont College of Medicine, Burlington, Vermont
| | - Marcelo Febo
- Department of Psychiatry and McKnight Brain Institute, University of Florida, College of Medicine, Gainesville, Florida
| | - David E. Smith
- Division of Addiction Services, Dominion Diagnostics, LLC, North Kingstown, Rhode Island.,Institute of Health & Aging, University of California, San Francisco, California
| | | | - Zsolt Demetrovics
- Department of Clinical Psychology and Addiction, Institute of Psychology, Eötvös Loránd University, Budapest, Hungary
| | | | - John Femino
- Department of Clinical Medicine, Meadows Edge Recovery Center, North Kingston, Rhode Island
| | - Gozde Agan
- Division of Addiction Services, Dominion Diagnostics, LLC, North Kingstown, Rhode Island
| | - James L. Fratantonio
- Division of Applied Clinical Research, Dominion Diagnostics, LLC, North Kingstown, Rhode Island
| | - Subhash C. Pandey
- Department of Psychiatry, University of Illinois at Chicago and Jesse Brown VA Medical Center, Chicago, Illinois
| | - Rajendra D. Badgaiyan
- Department of Psychiatry, University of Minnesota College of Medicine, Minneapolis, Minnesota
| | - Mark S. Gold
- Department of Psychiatry and McKnight Brain Institute, University of Florida, College of Medicine, Gainesville, Florida.,Department of Addiction Research & Therapy, Malibu Beach Recovery Center, Malibu Beach, California
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22
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Somkuwar SS, Kantak KM, Dwoskin LP. Effect of methylphenidate treatment during adolescence on norepinephrine transporter function in orbitofrontal cortex in a rat model of attention deficit hyperactivity disorder. J Neurosci Methods 2015; 252:55-63. [PMID: 25680322 DOI: 10.1016/j.jneumeth.2015.02.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 01/27/2015] [Accepted: 02/03/2015] [Indexed: 11/16/2022]
Abstract
Attention deficit hyperactivity disorder (ADHD) is associated with hypofunctional medial prefrontal cortex (mPFC) and orbitofrontal cortex (OFC). Methylphenidate (MPH) remediates ADHD, in part, by inhibiting the norepinephrine transporter (NET). MPH also reduces ADHD-like symptoms in spontaneously hypertensive rats (SHRs), a model of ADHD. However, effects of chronic MPH treatment on NET function in mPFC and OFC in SHR have not been reported. In the current study, long-term effects of repeated treatment with a therapeutically relevant oral dose of MPH during adolescence on NET function in subregions of mPFC (cingulate gyrus, prelimbic cortex and infralimbic cortex) and in the OFC of adult SHR, Wistar-Kyoto (WKY, inbred control) and Wistar (WIS, outbred control) rats were determined using in vivo voltammetry. Following local ejection of norepinephrine (NE), uptake rate was determined as peak amplitude (Amax)× first-order rate constant (k-1). In mPFC subregions, no strain or treatment effects were found in NE uptake rate. In OFC, NE uptake rate in vehicle-treated adult SHR was greater than in adult WKY and WIS administered vehicle. MPH treatment during adolescence normalized NE uptake rate in OFC in SHR. Thus, the current study implicates increased NET function in OFC as an underlying mechanism for reduced noradrenergic transmission in OFC, and consequently, the behavioral deficits associated with ADHD. MPH treatment during adolescence normalized NET function in OFC in adulthood, suggesting that the therapeutic action of MPH persists long after treatment cessation and may contribute to lasting reductions in deficits associated with ADHD.
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Affiliation(s)
- Sucharita S Somkuwar
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA
| | - Kathleen M Kantak
- Department of Psychological and Brain Sciences, Boston University, Boston, MA 02215, USA
| | - Linda P Dwoskin
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA.
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23
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Baskin BM, Dwoskin LP, Kantak KM. Methylphenidate treatment beyond adolescence maintains increased cocaine self-administration in the spontaneously hypertensive rat model of attention deficit/hyperactivity disorder. Pharmacol Biochem Behav 2015; 131:51-6. [PMID: 25643872 DOI: 10.1016/j.pbb.2015.01.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 01/21/2015] [Accepted: 01/26/2015] [Indexed: 10/24/2022]
Abstract
Past research with the spontaneously hypertensive rat (SHR) model of attention deficit/hyperactivity disorder showed that adolescent methylphenidate treatment enhanced cocaine abuse risk in SHR during adulthood. The acquisition of cocaine self-administration was faster, and cocaine dose-response functions were shifted upward under fixed-ratio and progressive ratio schedules compared to adult SHR that received adolescent vehicle treatment or to control strains that received adolescent methylphenidate treatment. The current study determined if extending treatment beyond adolescence would ameliorate long-term consequences of adolescent methylphenidate treatment on cocaine abuse risk in adult SHR. Treatments (vehicle or 1.5mg/kg/day oral methylphenidate) began on postnatal day 28. Groups of male SHR were treated with vehicle during adolescence and adulthood, with methylphenidate during adolescence and vehicle during adulthood, or with methylphenidate during adolescence and adulthood. The group receiving adolescent-only methylphenidate was switched to vehicle on P56. Cocaine self-administration began on postnatal day 77, and groups receiving methylphenidate during adolescence and adulthood were treated either 1-h before or 1-h after daily sessions. At baseline under a fixed-ratio 1 schedule, cocaine self-administration (2h sessions; 0.3mg/kg unit dose) did not differ among the four treatment groups. Under a progressive ratio schedule (4.5h maximum session length; 0.01-1.0mg/kg unit doses), breakpoints for self-administered cocaine in SHR receiving the adult methylphenidate treatment 1-h pre-session were not different from the vehicle control group. However, compared to the vehicle control group, breakpoints for self-administered cocaine at the 0.3 and 1.0mg/kg unit doses were greater in adult SHR that received adolescent-only methylphenidate or received methylphenidate that was continued into adulthood and administered 1-h post-session. These findings suggest that extending methylphenidate treatment beyond adolescence does not ameliorate explicitly the long-term consequences of adolescent methylphenidate treatment. Pre-session methylphenidate may mask temporarily the detection of an increase in cocaine self-administration following chronic methylphenidate treatment.
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Affiliation(s)
- Britahny M Baskin
- Department of Psychological and Brain Sciences, Boston University, Boston, MA 02215, USA..
| | - Linda P Dwoskin
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536 USA.
| | - Kathleen M Kantak
- Department of Psychological and Brain Sciences, Boston University, Boston, MA 02215, USA..
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24
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Performance on a strategy set shifting task in rats following adult or adolescent cocaine exposure. Psychopharmacology (Berl) 2014; 231:4489-501. [PMID: 24800898 PMCID: PMC4224606 DOI: 10.1007/s00213-014-3598-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 04/14/2014] [Indexed: 10/25/2022]
Abstract
RATIONALE Neuropsychological testing is widespread in adult cocaine abusers, but lacking in teens. Animal models may provide insight into age-related neuropsychological consequences of cocaine exposure. OBJECTIVES The objective of the present study is to determine whether developmental plasticity protects or hinders behavioral flexibility after cocaine exposure in adolescent vs. adult rats. METHODS Using a yoked-triad design, one rat controlled cocaine delivery and the other two passively received cocaine or saline. Rats controlling cocaine delivery (1.0 mg/kg) self-administered for 18 sessions (starting P37 or P77), followed by 18 drug-free days. Rats next were tested in a strategy set shifting task, lasting 11-13 sessions. RESULTS Cocaine self-administration did not differ between age groups. During initial set formation, adolescent-onset groups required more trials to reach criterion and made more errors than adult-onset groups. During the set shift phase, rats with adult-onset cocaine self-administration experience had higher proportions of correct trials and fewer perseverative + regressive errors than age-matched yoked-controls or rats with adolescent-onset cocaine self-administration experience. During reversal learning, rats with adult-onset cocaine experience (self-administered or passive) required fewer trials to reach criterion, and the self-administering rats made fewer perseverative + regressive errors than yoked-saline rats. Rats receiving adolescent-onset yoked-cocaine had more trial omissions and longer lever press reaction times than age-matched rats self-administering cocaine or receiving yoked-saline. CONCLUSIONS Prior cocaine self-administration may impair memory to reduce proactive interference during set shifting and reversal learning in adult-onset but not adolescent-onset rats (developmental plasticity protective). Passive cocaine may disrupt aspects of executive function in adolescent-onset but not adult-onset rats (developmental plasticity hinders).
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Gauthier JM, Tassin DH, Dwoskin LP, Kantak KM. Effects of dopamine D1 receptor blockade in the prelimbic prefrontal cortex or lateral dorsal striatum on frontostriatal function in Wistar and Spontaneously Hypertensive Rats. Behav Brain Res 2014; 268:229-38. [PMID: 24755309 PMCID: PMC4078764 DOI: 10.1016/j.bbr.2014.04.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 04/07/2014] [Accepted: 04/11/2014] [Indexed: 02/06/2023]
Abstract
Attention Deficit Hyperactivity Disorder (ADHD) is associated with dysfunctional prefrontal and striatal circuitry and dysregulated dopamine neurotransmission. Spontaneously Hypertensive Rats (SHR), a heuristically useful animal model of ADHD, were evaluated against normotensive Wistar (WIS) controls to determine whether dopamine D1 receptor blockade of either prelimbic prefrontal cortex (plPFC) or lateral dorsal striatum (lDST) altered learning functions of both interconnected sites. A strategy set shifting task measured plPFC function (behavioral flexibility/executive function) and a reward devaluation task measured lDST function (habitual responding). Prior to tests, rats received bilateral infusions of SCH 23390 (1.0 μg/side) or vehicle into plPFC or lDST. Following vehicle, SHR exhibited longer lever press reaction times, more trial omissions, and fewer completed trials during the set shift test compared to WIS, indicating slower decision-making and attentional/motivational impairment in SHR. After reward devaluation, vehicle-treated SHR responded less than WIS, indicating relatively less habitual responding in SHR. After SCH 23390 infusions into plPFC, WIS expressed the same behavioral phenotype as vehicle-treated SHR during set shift and reward devaluation tests. In SHR, SCH 23390 infusions into plPFC exacerbated behavioral deficits in the set shift test and maintained the lower rate of responding in the reward devaluation test. SCH 23390 infusions into lDST did not modify set shifting in either strain, but produced lower rates of responding than vehicle infusions after reward devaluation in WIS. This research provides pharmacological evidence for unidirectional interactions between prefrontal and striatal brain regions, which has implications for the neurological basis of ADHD and its treatment.
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Affiliation(s)
- Jamie M Gauthier
- Department of Psychological and Brain Sciences, 64 Cummington Mall, Boston University, Boston, MA 02215, USA
| | - David H Tassin
- Department of Psychological and Brain Sciences, 64 Cummington Mall, Boston University, Boston, MA 02215, USA
| | - Linda P Dwoskin
- Department of Pharmaceutical Sciences, 789 South Limestone, University of Kentucky, Lexington, KY 40536, USA
| | - Kathleen M Kantak
- Department of Psychological and Brain Sciences, 64 Cummington Mall, Boston University, Boston, MA 02215, USA.
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Jordan CJ, Harvey RC, Baskin BB, Dwoskin LP, Kantak KM. Cocaine-seeking behavior in a genetic model of attention-deficit/hyperactivity disorder following adolescent methylphenidate or atomoxetine treatments. Drug Alcohol Depend 2014; 140:25-32. [PMID: 24811203 PMCID: PMC4075321 DOI: 10.1016/j.drugalcdep.2014.04.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 04/15/2014] [Accepted: 04/15/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND Attention-deficit/hyperactivity disorder (ADHD) is often comorbid with cocaine abuse. Controversy exists regarding long-term consequences of ADHD medications on cocaine abuse liability. Whereas childhood methylphenidate treatment may be preventative, methylphenidate in teens appears to further increase later cocaine abuse risk. In rodents, adolescent methylphenidate treatment further increases adult cocaine self-administration in the Spontaneously Hypertensive Rat (SHR) model of ADHD, whereas adolescent atomoxetine treatment does not. Effects of ADHD medications on cocaine cue reactivity, a critical component of addiction, are unknown. METHODS To investigate this, SHR, Wistar-Kyoto (inbred control) and Wistar (outbred control) rats received therapeutically relevant doses of methylphenidate (1.5 mg/kg, oral) and atomoxetine (0.3 mg/kg, intraperitoneal), or respective vehicles from post-natal day 28-55. Cocaine seeking, reflecting cue reactivity, was measured in adulthood during self-administration maintenance and cue-induced reinstatement tests conducted under a second-order schedule. RESULTS Compared to control strains, SHR earned more cocaine infusions, emitted more cocaine-seeking responses during maintenance and reinstatement testing, and required more sessions to reach the extinction criterion. Compared to vehicle, adolescent methylphenidate, but not atomoxetine, further increased cocaine intake during maintenance testing in SHR. Adolescent atomoxetine, but not methylphenidate, decreased cocaine seeking during reinstatement testing in SHR. Neither medication had effects on cocaine intake or cue reactivity in control strains. CONCLUSIONS The SHR successfully model ADHD and cocaine abuse comorbidity and show differential effects of adolescent ADHD medications on cocaine intake and cue reactivity during adulthood. Thus, SHR have heuristic value for assessing neurobiology underlying the ADHD phenotype and for evaluating pharmacotherapeutics for ADHD.
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Affiliation(s)
- Chloe J. Jordan
- Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts 02215, USA
| | - Roxann C. Harvey
- Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts 02215, USA
| | - Britahny B. Baskin
- Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts 02215, USA
| | - Linda P. Dwoskin
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Kathleen M. Kantak
- Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts 02215, USA
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Stanis JJ, Andersen SL. Reducing substance use during adolescence: a translational framework for prevention. Psychopharmacology (Berl) 2014; 231:1437-53. [PMID: 24464527 PMCID: PMC3969413 DOI: 10.1007/s00213-013-3393-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 11/30/2013] [Indexed: 11/30/2022]
Abstract
RATIONALE Most substance use is initiated during adolescence when substantial development of relevant brain circuitry is still rapidly maturing. Developmental differences in reward processing, behavioral flexibility, and self-regulation lead to changes in resilience or vulnerability to drugs of abuse depending on exposure to risk factors. Intervention and prevention approaches to reducing addiction in teens may be able to capitalize on malleable brain systems in a predictable manner. OBJECTIVE This review will highlight what is known about how factors that increase vulnerability to addiction, including developmental stage, exposure to early life adversity (ranging from abuse, neglect, and bullying), drug exposure, and genetic predisposition, impact the development of relevant systems. RESULTS AND CONCLUSIONS Appropriate, early intervention may restore the normal course of an abnormal trajectory and reduce the likelihood of developing a substance use disorder (SUD) later in life. A considerable amount is known about the functional neuroanatomy and/or pharmacology of risky behaviors based on clinical and preclinical studies, but relatively little has been directly translated to reduce their impact on addiction in high-risk children or teenagers. An opportunity exists to effectively intervene before adolescence when substance use is likely to emerge.
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Affiliation(s)
- Jessica J Stanis
- Laboratory of Developmental Neuropharmacology, McLean Hospital and Department of Psychiatry, Harvard Medical School, Mailstop 333, 115 Mill Street, Belmont, MA, 02478, USA
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Adolescent atomoxetine treatment in a rodent model of ADHD: effects on cocaine self-administration and dopamine transporters in frontostriatal regions. Neuropsychopharmacology 2013; 38:2588-97. [PMID: 23822950 PMCID: PMC3828528 DOI: 10.1038/npp.2013.163] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 06/12/2013] [Accepted: 07/01/2013] [Indexed: 01/09/2023]
Abstract
Cocaine abuse and attention deficit/hyperactivity disorder (ADHD) are often comorbid. Preclinical research indicates that medial prefrontal (mPFC) and orbitofrontal (OFC) cortices are important neural substrates for both disorders. Using the spontaneously hypertensive rat (SHR) model of ADHD, we reported that adolescent treatment with the stimulant methylphenidate, a dopamine (DAT) and norepinephrine (NET) transporter inhibitor, enhanced cocaine self-administration during adulthood, and was associated with increased DAT function in mPFC. This study investigates the effects of atomoxetine ((R)-N-methyl-γ-(2-methylphenoxy)-benzenepropanamine hydrochloride) treatment, a selective NET inhibitor, during adolescence on cocaine self-administration and on DAT function and cell-surface expression in mPFC and OFC during adulthood. SHR acquired cocaine self-administration faster than Wistar-Kyoto and Wistar. Across cocaine doses, SHR earned more cocaine infusions and had higher progressive-ratio breakpoints than Wistar-Kyoto and Wistar, demonstrating that the SHR phenotype models comorbid ADHD and cocaine abuse. Prior atomoxetine treatment did not augment cocaine self-administration in SHR, but acquisition was enhanced in Wistar-Kyoto. No strain differences were found for DAT kinetic parameters or cellular localization in the vehicle controls. Atomoxetine did not alter DAT kinetic parameters or localization in SHR mPFC. Rather, atomoxetine decreased V(max) and DAT cell surface expression in SHR OFC, indicating that inhibition of NET by atomoxetine treatment during adolescence indirectly reduced DAT function and trafficking to the cell surface in OFC, specifically in the ADHD model. Thus, atomoxetine, unlike methylphenidate, does not enhance vulnerability to cocaine abuse in SHR and may represent an important alternative for teens with ADHD when drug addiction is a concern.
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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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