1
|
Chen G, Li L, Sun T, Jiang C, Xu W, Chen S, Hu C, Yue Y, Wang T, Jiang W, Yuan Y. The Interaction of LAMA2 and Duration of Illness Affects the Thickness of the Right Transverse Temporal Gyrus in Major Depressive Disorder. Neuropsychiatr Dis Treat 2023; 19:2807-2816. [PMID: 38144699 PMCID: PMC10749177 DOI: 10.2147/ndt.s435025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 12/14/2023] [Indexed: 12/26/2023] Open
Abstract
Background Depression is a heritable brain disorder. Laminin genes were recently identified to affect the brain's overall thickness through neurogenesis, differentiation, and migration in depression. This study aims to explore the effects of the LAMA2's single nucleotide polymorphisms (SNP), a subunit gene of laminin, on the detected brain regions of patients with major depressive disorder (MDD). Methods The study included 89 patients with MDD and 60 healthy controls with T1-weighted structural magnetic resonance imaging and blood samples for genotyping. The interactions between LAMA2 gene SNPs and diagnosis as well as duration of illness (DOI) were explored on brain measures controlled for age, gender, and site. Results The right transverse temporal gyrus and right parahippocampal gyrus showed reduced thickness in MDD. Almost all seven LAMA2 SNPs showed significant interactions with diagnosis on both gyrus (corrected p < 0.05 or trending). In MDD, rs6569604, rs2229848, rs2229849, rs2229850, and rs2784895 interacted with DOI on the right transverse temporal gyrus (corrected p < 0.05), but not the right parahippocampal gyrus. Conclusion The thickness of the right transverse temporal gyrus in patients with MDD may be affected by LAMA2 gene and DOI.
Collapse
Affiliation(s)
- Gang Chen
- Department of Psychosomatics and Psychiatry, ZhongDa Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
- Institute of Psychosomatics, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
- Department of Medical Psychology, Huai’an NO 3 People’s Hospital, Huaian, People’s Republic of China
| | - Lei Li
- Institute of Psychosomatics, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
- Department of Sleep Medicine, The Fourth People’s Hospital of Lianyungang, Lianyungang, People’s Republic of China
| | - Taipeng Sun
- Department of Psychosomatics and Psychiatry, ZhongDa Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
- Institute of Psychosomatics, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
- Department of Medical Psychology, Huai’an NO 3 People’s Hospital, Huaian, People’s Republic of China
| | - Chenguang Jiang
- Department of Psychosomatics and Psychiatry, ZhongDa Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
- Institute of Psychosomatics, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
| | - Wei Xu
- Department of Psychosomatics and Psychiatry, ZhongDa Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
- Institute of Psychosomatics, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
| | - Suzhen Chen
- Department of Psychosomatics and Psychiatry, ZhongDa Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
- Institute of Psychosomatics, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
| | - Changchun Hu
- Department of Psychosomatics and Psychiatry, ZhongDa Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
| | - Yingying Yue
- Department of Psychosomatics and Psychiatry, ZhongDa Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
- Institute of Psychosomatics, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
| | - Tianyu Wang
- Department of Psychosomatics and Psychiatry, ZhongDa Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
- Institute of Psychosomatics, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
| | - Wenhao Jiang
- Department of Psychosomatics and Psychiatry, ZhongDa Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
- Institute of Psychosomatics, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
| | - Yonggui Yuan
- Department of Psychosomatics and Psychiatry, ZhongDa Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
- Institute of Psychosomatics, School of Medicine, Southeast University, Nanjing, Jiangsu, People’s Republic of China
| |
Collapse
|
2
|
Volnova A, Kurzina N, Belskaya A, Gromova A, Pelevin A, Ptukha M, Fesenko Z, Ignashchenkova A, Gainetdinov RR. Noradrenergic Modulation of Learned and Innate Behaviors in Dopamine Transporter Knockout Rats by Guanfacine. Biomedicines 2023; 11:222. [PMID: 36672730 PMCID: PMC9856099 DOI: 10.3390/biomedicines11010222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/11/2023] [Accepted: 01/13/2023] [Indexed: 01/18/2023] Open
Abstract
Investigation of the precise mechanisms of attention deficit and hyperactivity disorder (ADHD) and other dopamine-associated conditions is crucial for the development of new treatment approaches. In this study, we assessed the effects of repeated and acute administration of α2A-adrenoceptor agonist guanfacine on innate and learned forms of behavior of dopamine transporter knockout (DAT-KO) rats to evaluate the possible noradrenergic modulation of behavioral deficits. DAT-KO and wild type rats were trained in the Hebb-Williams maze to perform spatial working memory tasks. Innate behavior was evaluated via pre pulse inhibition (PPI). Brain activity of the prefrontal cortex and the striatum was assessed. Repeated administration of GF improved the spatial working memory task fulfillment and PPI in DAT-KO rats, and led to specific changes in the power spectra and coherence of brain activity. Our data indicate that both repeated and acute treatment with a non-stimulant noradrenergic drug lead to improvements in the behavior of DAT-KO rats. This study further supports the role of the intricate balance of norepinephrine and dopamine in the regulation of attention. The observed compensatory effect of guanfacine on the behavior of hyperdopaminergic rats may be used in the development of combined treatments to support the dopamine-norepinephrine balance.
Collapse
Affiliation(s)
- Anna Volnova
- Institute of Translational Biomedicine, Saint Petersburg State University, Saint Petersburg 199034, Russia
- Biological Faculty, Saint Petersburg State University, Saint Petersburg 199034, Russia
| | - Natalia Kurzina
- Institute of Translational Biomedicine, Saint Petersburg State University, Saint Petersburg 199034, Russia
| | - Anastasia Belskaya
- Institute of Translational Biomedicine, Saint Petersburg State University, Saint Petersburg 199034, Russia
| | - Arina Gromova
- Biological Faculty, Saint Petersburg State University, Saint Petersburg 199034, Russia
| | - Arseniy Pelevin
- Institute of Translational Biomedicine, Saint Petersburg State University, Saint Petersburg 199034, Russia
- Biological Faculty, Saint Petersburg State University, Saint Petersburg 199034, Russia
| | - Maria Ptukha
- Institute of Translational Biomedicine, Saint Petersburg State University, Saint Petersburg 199034, Russia
| | - Zoia Fesenko
- Institute of Translational Biomedicine, Saint Petersburg State University, Saint Petersburg 199034, Russia
| | | | - Raul R. Gainetdinov
- Institute of Translational Biomedicine, Saint Petersburg State University, Saint Petersburg 199034, Russia
- Saint Petersburg University Hospital, Saint Petersburg 199034, Russia
| |
Collapse
|
3
|
Dubois M, Bowler A, Moses-Payne ME, Habicht J, Moran R, Steinbeis N, Hauser TU. Exploration heuristics decrease during youth. COGNITIVE, AFFECTIVE & BEHAVIORAL NEUROSCIENCE 2022; 22:969-983. [PMID: 35589910 PMCID: PMC9458685 DOI: 10.3758/s13415-022-01009-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Accepted: 04/22/2022] [Indexed: 01/01/2023]
Abstract
Deciding between exploring new avenues and exploiting known choices is central to learning, and this exploration-exploitation trade-off changes during development. Exploration is not a unitary concept, and humans deploy multiple distinct mechanisms, but little is known about their specific emergence during development. Using a previously validated task in adults, changes in exploration mechanisms were investigated between childhood (8-9 y/o, N = 26; 16 females), early (12-13 y/o, N = 38; 21 females), and late adolescence (16-17 y/o, N = 33; 19 females) in ethnically and socially diverse schools from disadvantaged areas. We find an increased usage of a computationally light exploration heuristic in younger groups, effectively accommodating their limited neurocognitive resources. Moreover, this heuristic was associated with self-reported, attention-deficit/hyperactivity disorder symptoms in this population-based sample. This study enriches our mechanistic understanding about how exploration strategies mature during development.
Collapse
Affiliation(s)
- Magda Dubois
- Max Planck UCL Centre for Computational Psychiatry and Ageing Research, WC1B 5EH, London, UK.
- Wellcome Centre for Human Neuroimaging, University College London, WC1N 3BG, London, UK.
| | - Aislinn Bowler
- Max Planck UCL Centre for Computational Psychiatry and Ageing Research, WC1B 5EH, London, UK
- Wellcome Centre for Human Neuroimaging, University College London, WC1N 3BG, London, UK
- Centre for Brain and Cognitive Development, Birkbeck, University of London, WC1E 7HX, London, UK
| | - Madeleine E Moses-Payne
- Max Planck UCL Centre for Computational Psychiatry and Ageing Research, WC1B 5EH, London, UK
- Wellcome Centre for Human Neuroimaging, University College London, WC1N 3BG, London, UK
- UCL Institute of Cognitive Neuroscience, WC1N 3AZ, London, UK
| | - Johanna Habicht
- Max Planck UCL Centre for Computational Psychiatry and Ageing Research, WC1B 5EH, London, UK
- Wellcome Centre for Human Neuroimaging, University College London, WC1N 3BG, London, UK
| | - Rani Moran
- Max Planck UCL Centre for Computational Psychiatry and Ageing Research, WC1B 5EH, London, UK
- Wellcome Centre for Human Neuroimaging, University College London, WC1N 3BG, London, UK
| | - Nikolaus Steinbeis
- Division of Psychology and Language Sciences, University College London, WC1H 0AP, London, UK
| | - Tobias U Hauser
- Max Planck UCL Centre for Computational Psychiatry and Ageing Research, WC1B 5EH, London, UK
- Wellcome Centre for Human Neuroimaging, University College London, WC1N 3BG, London, UK
| |
Collapse
|
4
|
Kurzina N, Belskaya A, Gromova A, Ignashchenkova A, Gainetdinov RR, Volnova A. Modulation of Spatial Memory Deficit and Hyperactivity in Dopamine Transporter Knockout Rats via α2A-Adrenoceptors. Front Psychiatry 2022; 13:851296. [PMID: 35401264 PMCID: PMC8990031 DOI: 10.3389/fpsyt.2022.851296] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 02/28/2022] [Indexed: 12/21/2022] Open
Abstract
Attention deficit hyperactivity disorder (ADHD) is manifested by a specific set of behavioral deficits such as hyperactivity, impulsivity, and inattention. The dopamine neurotransmitter system is postulated to be involved in the pathogenesis of ADHD. Guanfacine, a selective α2A-adrenoceptor agonist, is prescribed for ADHD treatment. ADHD also is known to be associated with impairment of multiple aspects of cognition, including spatial memory, however, it remains unclear how modulation of the norepinephrine system can affect these deficits. Hyperdopaminergic dopamine transporter knockout (DAT-KO) rats are a valuable model for investigating ADHD. The DAT-KO rats are hyperactive and deficient in spatial working memory. This work aimed to evaluate the effects of noradrenergic drugs on the fulfillment of spatial cognitive tasks by DAT-KO rats. The rats were tested in the Hebb - Williams maze during training and following noradrenergic drugs administration. The efficiency of spatial orientation was assessed as to how fast the animal finds an optimal way to the goal box. Testing in a new maze configuration allowed us to evaluate the effects of drug administration after the acquisition of the task rules. The behavioral variables such as the distance traveled, the time to reach the goal box, and the time spent in the error zones were analyzed. It has been observed that α2A-adrenoceptor agonist Guanfacine (0.25 mg/kg) had only a minimal inhibitory effect on hyperactivity of DAT-KO rats in the maze but significantly ameliorated their perseverative pattern of activity and reduced the time spent in the error zones. In contrast, α2A-adrenoceptor antagonist Yohimbine, at the dose of 1 mg/kg, increased the distance traveled by DAT-KO rats and elevated the number of perseverative reactions and the time spent in the error zones. Guanfacine caused minimal effects in wild-type rats, while Yohimbine altered several parameters reflecting a detrimental effect on the performance in the maze. These data indicate that modulation of α2A-adrenoceptor activity potently affects both dopamine-dependent hyperactivity and cognitive dysfunctions. Similar mechanisms may be involved in the beneficial effects of Guanfacine on cognitive deficits in ADHD patients. This study further supports the translational potential of DAT-KO rats for testing new pharmacological drugs.
Collapse
Affiliation(s)
- Natalia Kurzina
- Institute of Translational Biomedicine, Saint Petersburg State University, Saint Petersburg, Russia
| | - Anastasia Belskaya
- Biological Faculty, Saint Petersburg State University, Saint Petersburg, Russia
| | - Arina Gromova
- Biological Faculty, Saint Petersburg State University, Saint Petersburg, Russia
| | - Alla Ignashchenkova
- Institute of Translational Biomedicine, Saint Petersburg State University, Saint Petersburg, Russia
| | - Raul R Gainetdinov
- Institute of Translational Biomedicine, Saint Petersburg State University, Saint Petersburg, Russia.,Saint Petersburg University Hospital, Saint Petersburg, Russia
| | - Anna Volnova
- Institute of Translational Biomedicine, Saint Petersburg State University, Saint Petersburg, Russia.,Biological Faculty, Saint Petersburg State University, Saint Petersburg, Russia
| |
Collapse
|
5
|
Netter P. Between Temperament and Psychopathology: Examples from Neuropharmacological Challenge Tests in Healthy Humans. Neuropsychobiology 2021; 80:84-100. [PMID: 33647900 DOI: 10.1159/000514074] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 12/21/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND This paper tries to demonstrate that the questionnaire-based continuum between temperament traits and psychopathology can also be shown on the biochemical level. A common feature is the incapacity to adapt to external demands, as demonstrated by examples of disturbed hormone cycles as well as neurotransmitter (TM) responses related to affective and impulse control disorders. METHODS Pharmacological challenge tests performed in placebo-controlled balanced crossover experiments with consecutive challenges by serotonin (5-HT), noradrenaline (NA), and dopamine (DA) agonistic drugs were applied to healthy subjects, and individual responsivities of each TM system assessed by respective cortisol and prolactin responses were related to questionnaire-based facets of depressiveness and impulsivity, respectively. RESULTS The depression-related traits "Fatigue" and "Physical Anhedonia" were characterized by low and late responses to DA stimulation as opposed to "Social Anhedonia," which rather mirrored the pattern of schizophrenia. Reward-related and premature responding-related impulsivity represented by high scores on "Disinhibition" and "Motor Impulsivity," respectively, as well as the questionnaire-based components of attention deficit hyperactivity disorder, "Cognitive" and "Motor Impulsivity," could be discriminated by their patterns of DA/NA responses. 5-HT responses suggested that instead of the expected low availability of 5-HT claimed to be associated with impulse control disorders, low NA responses indicated lack of inhibition in impulsivity and high NA responses in depression-related "Anhedonia" indicated suppression of approach motivation. CONCLUSIONS In spite of the flaws of pharmacological challenge tests, they may be suitable for demonstrating similarities in TM affinities between psychopathological disturbances and respective temperament traits and for separating sub-entities of larger disease spectra.
Collapse
Affiliation(s)
- Petra Netter
- Department of Psychology, University of Gießen, Gießen, Germany,
| |
Collapse
|
6
|
Findling RL, Candler SA, Nasser AF, Schwabe S, Yu C, Garcia-Olivares J, O'Neal W, Newcorn JH. Viloxazine in the Management of CNS Disorders: A Historical Overview and Current Status. CNS Drugs 2021; 35:643-653. [PMID: 34003459 PMCID: PMC8219567 DOI: 10.1007/s40263-021-00825-w] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/03/2021] [Indexed: 12/12/2022]
Abstract
Viloxazine has a long history of clinical use in Europe as an antidepressant, and has recently been repurposed into an extended-release form for the treatment of attention-deficit/hyperactivity disorder in the USA. An immediate-release formulation was approved for the treatment of depression in the UK in 1974, and was subsequently marketed there and in several European countries for 30 years with no major safety concerns. In contrast to first-generation antidepressants (e.g., tricyclic antidepressants, monoamine oxidase inhibitors), viloxazine was associated with a relatively low risk for cardiotoxicity. Gastrointestinal symptoms were the most commonly reported side effects. The therapeutic effects of viloxazine are thought to be primarily the result of its action as a norepinephrine reuptake inhibitor, although in vitro and preclinical in vivo animal data suggest that viloxazine may also impact the serotoninergic system. This review summarizes the evolving knowledge of viloxazine based on information from previously published preclinical and clinical investigations, and acquired unpublished historical study reports from both open-label and blinded controlled clinical trials. We review the chemical properties, mechanism of action, safety, and tolerability across these studies, and discuss the contemporary rationale for the development of this agent as an extended-release oral formulation for the treatment of attention-deficit/hyperactivity disorder.
Collapse
Affiliation(s)
- Robert L Findling
- VCU Department of Psychiatry, 501 North 2nd Street, Richmond, VA, 23298-0308, USA.
| | | | | | | | - Chungping Yu
- Supernus Pharmaceuticals, Inc., Rockville, MD, USA
| | | | | | - Jeffrey H Newcorn
- Departments of Psychiatry and Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| |
Collapse
|
7
|
Faison SL, Fry N, Adewole T, Odebo O, Schwabe S, Wang Z, Maletic V, Nasser A. Pharmacokinetics of Coadministered Viloxazine Extended-Release (SPN-812) and Methylphenidate in Healthy Adults. Clin Drug Investig 2020; 41:149-159. [PMID: 33368026 PMCID: PMC7886742 DOI: 10.1007/s40261-020-00992-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2020] [Indexed: 11/30/2022]
Abstract
BACKGROUND AND OBJECTIVES Viloxazine extended-release (viloxazine ER, SPN-812) is a novel non-stimulant with activity at serotonin receptors and the norepinephrine transporter, which is under investigation as a potential treatment for attention-deficit/hyperactivity disorder. Given the potential for viloxazine ER to be coadministered with other pharmacotherapies, this trial investigated the pharmacokinetics and safety of combination viloxazine ER + methylphenidate versus viloxazine ER or methylphenidate alone. METHODS In this single-center, crossover, open-label trial, healthy adult participants received oral administration of 700 mg viloxazine ER alone, 36 mg methylphenidate alone, and combination viloxazine ER (700 mg) + methylphenidate (36 mg), with blood samples collected over 4 days post-administration. The active drug in viloxazine ER (viloxazine) and methylphenidate was measured using chromatographic tandem mass spectrometry. Safety assessments included adverse events (AEs), vital signs, echocardiograms, and clinical laboratory evaluations. RESULTS Of 36 healthy adults who were enrolled, 34 completed the trial. The geometric least squares mean ratios are reported as [combination/single drug (90% confidence intervals)]. For viloxazine ER, maximum measured plasma concentration (Cmax) = 100.98% (96.21-105.99), area under the concentration-time curve from time zero to the last measurable time (AUCt) = 98.62% (96.21-101.08), and area under the concentration-time curve from time zero to infinity (AUC∞) = 98.96% (96.55-101.44). For methylphenidate, Cmax = 103.55% (97.42-110.07), AUCt = 106.67% (101.01-112.64), and AUC∞ = 106.61% (100.99-112.54). All reported AEs were mild in severity. CONCLUSIONS Coadministration of viloxazine ER and methylphenidate did not impact the pharmacokinetics of viloxazine or methylphenidate relative to administration of either drug alone. The combination appeared to be safe and well tolerated.
Collapse
Affiliation(s)
- Shamia L Faison
- Supernus Pharmaceuticals, Inc., 9715 Key West Avenue, Rockville, MD, 20850, USA
| | - Nicholas Fry
- Supernus Pharmaceuticals, Inc., 9715 Key West Avenue, Rockville, MD, 20850, USA
| | - Toyin Adewole
- Supernus Pharmaceuticals, Inc., 9715 Key West Avenue, Rockville, MD, 20850, USA
| | - Oyinkansola Odebo
- Supernus Pharmaceuticals, Inc., 9715 Key West Avenue, Rockville, MD, 20850, USA
| | - Stefan Schwabe
- Supernus Pharmaceuticals, Inc., 9715 Key West Avenue, Rockville, MD, 20850, USA
| | - Zhao Wang
- Supernus Pharmaceuticals, Inc., 9715 Key West Avenue, Rockville, MD, 20850, USA
| | - Vladimir Maletic
- Department of Psychiatry/Behavioral Science, University of South Carolina School of Medicine, Greenville, SC, USA
| | - Azmi Nasser
- Supernus Pharmaceuticals, Inc., 9715 Key West Avenue, Rockville, MD, 20850, USA.
| |
Collapse
|
8
|
Duggins P, Stewart TC, Choo X, Eliasmith C. The Effects of Guanfacine and Phenylephrine on a Spiking Neuron Model of Working Memory. Top Cogn Sci 2016; 9:117-134. [DOI: 10.1111/tops.12247] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 11/05/2016] [Accepted: 11/15/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Peter Duggins
- Centre for Theoretical Neuroscience University of Waterloo
| | | | - Xuan Choo
- Centre for Theoretical Neuroscience University of Waterloo
| | | |
Collapse
|
9
|
Beiranvand A, Nasehi M, Zarrindast MR, Moghaddasi M. Involvement of medial prefrontal cortex alpha-2 adrenoceptors on memory acquisition deficit induced by arachidonylcyclopropylamide, a cannabinoid CB1 receptor agonist, in rats; possible involvement of Ca2+ channels. J Psychopharmacol 2016; 30:945-54. [PMID: 27317021 DOI: 10.1177/0269881116652585] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Functional interactions between cannabinoid and alpha-2 adrenergic systems in cognitive control in the medial prefrontal cortex (mPFC) seem possible. The present study evaluated the possible role of alpha-2 adrenoceptors of the prefrontal cortex on effect of arachidonylcyclopropylamide (ACPA), a cannabinoid CB1 receptor (CB1R) agonist, in adult male Wistar rats. The animals were bilaterally implanted with chronic cannulae in the mPFC, trained in a step-through task, and tested 24 h after training to measure step-through latency. Results indicate that pre-training microinjection of ACPA (0.05 and 0.5 μg/rat) and clonidine (alpha-2 adrenoceptor agonist; 1 and 2 μg/rat) reduce memory acquisition. Pre-training subthreshold dose of clonidine (0.5 µg/rat) restored memory-impairing effect of ACPA (0.05 and 0.5 µg/rat). On the other hand, pre-training administration of the alpha-2 adrenoceptor antagonist yohimbine in all doses used (0.5, 1, and 2 μg/rat) did not affect memory acquisition by itself, while a subthreshold dose of yohimbine (2 µg/rat) potentiated memory impairment induced by ACPA (0.005 µg/rat). Finally, a subthreshold dose of SKF96365 (a Ca(2+) channel blocker) blocked clonidine and yohimbine effect of memory responses induced by ACPA. In conclusion, these data indicate that mPFC alpha-2 adrenoceptors play an important role in ACPA-induced amnesia and Ca(2+) channels have a critical role this phenomenon.
Collapse
Affiliation(s)
| | - Mohammad Nasehi
- Cognitive and Neuroscience Research Center (CNRC), Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran
| | - Mohammad-Reza Zarrindast
- Institute for Cognitive Science Studies (ICSS), Tehran, Iran Cognitive and Neuroscience Research Center (CNRC), Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, Tehran, Iran School of Cognitive Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran Medical Genomics Research Center, Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran
| | - Mehrnoush Moghaddasi
- Razi Herbal Medicines Research Center, Department of Physiology, Lorestan University of Medical Sciences, Khorramabad, Iran
| |
Collapse
|
10
|
Hauser TU, Fiore VG, Moutoussis M, Dolan RJ. Computational Psychiatry of ADHD: Neural Gain Impairments across Marrian Levels of Analysis. Trends Neurosci 2016; 39:63-73. [PMID: 26787097 PMCID: PMC4746317 DOI: 10.1016/j.tins.2015.12.009] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 11/23/2015] [Accepted: 12/18/2015] [Indexed: 01/08/2023]
Abstract
Attention-deficit hyperactivity disorder (ADHD), one of the most common psychiatric disorders, is characterised by unstable response patterns across multiple cognitive domains. However, the neural mechanisms that explain these characteristic features remain unclear. Using a computational multilevel approach, we propose that ADHD is caused by impaired gain modulation in systems that generate this phenotypic increased behavioural variability. Using Marr's three levels of analysis as a heuristic framework, we focus on this variable behaviour, detail how it can be explained algorithmically, and how it might be implemented at a neural level through catecholamine influences on corticostriatal loops. This computational, multilevel, approach to ADHD provides a framework for bridging gaps between descriptions of neuronal activity and behaviour, and provides testable predictions about impaired mechanisms.
Collapse
Affiliation(s)
- Tobias U Hauser
- Wellcome Trust Centre for Neuroimaging, University College London, London, WC1N 3BG, UK; Max Planck UCL Centre for Computational Psychiatry and Ageing Research, London, WC1B 5EH, UK.
| | - Vincenzo G Fiore
- Wellcome Trust Centre for Neuroimaging, University College London, London, WC1N 3BG, UK
| | - Michael Moutoussis
- Wellcome Trust Centre for Neuroimaging, University College London, London, WC1N 3BG, UK
| | - Raymond J Dolan
- Wellcome Trust Centre for Neuroimaging, University College London, London, WC1N 3BG, UK; Max Planck UCL Centre for Computational Psychiatry and Ageing Research, London, WC1B 5EH, UK
| |
Collapse
|
11
|
Sallee FR. The Role of Alpha2-Adrenergic Agonists in Attention-Deficit/Hyperactivity Disorder. Postgrad Med 2015; 122:78-87. [DOI: 10.3810/pgm.2010.09.2204] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Floyd R. Sallee
- Department of Psychiatry, University of Cincinnati, Cincinnati, OH
| |
Collapse
|
12
|
Moon SJ, Kim CJ, Lee YJ, Hong M, Han J, Bahn GH. Effect of atomoxetine on hyperactivity in an animal model of attention-deficit/hyperactivity disorder (ADHD). PLoS One 2014; 9:e108918. [PMID: 25271814 PMCID: PMC4182750 DOI: 10.1371/journal.pone.0108918] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 08/27/2014] [Indexed: 12/02/2022] Open
Abstract
Background Hyperactivity related behaviors as well as inattention and impulsivity are regarded as the nuclear symptoms of attention-deficit/hyperactivity disorder (ADHD). Purpose To investigate the therapeutic effects of atomoxetine on the motor activity in relation to the expression of the dopamine (DA) D2 receptor based on the hypothesis that DA system hypofunction causes ADHD symptoms, which would correlate with extensive D2 receptor overproduction and a lack of DA synthesis in specific brain regions: prefrontal cortex (PFC), striatum, and hypothalamus. Methods Young male spontaneously hypertensive rats (SHR), animal models of ADHD, were randomly divided into four groups according to the daily dosage of atomoxetine and treated for 21 consecutive days. The animals were assessed using an open-field test, and the DA D2 receptor expression was examined. Results The motor activity improved continuously in the group treated with atomoxetine at a dose of 1 mg/Kg/day than in the groups treated with atomoxetine at a dose of 0.25 mg/Kg/day or 0.5 mg/Kg/day. With respect to DA D2 receptor immunohistochemistry, we observed significantly increased DA D2 receptor expression in the PFC, striatum, and hypothalamus of the SHRs as compared to the WKY rats. Treatment with atomoxetine significantly decreased DA D2 expression in the PFC, striatum, and hypothalamus of the SHRs, in a dose-dependent manner. Conclusion Hyperactivity in young SHRs can be improved by treatment with atomoxetine via the DA D2 pathway.
Collapse
Affiliation(s)
- Su Jin Moon
- Department of Psychiatry, Daedong Hospital, Daegu, Korea
| | - Chang Ju Kim
- Department of Physiology, Kyung Hee University School of Medicine, Seoul, Korea
| | - Yeon Jung Lee
- Department of Psychiatry, Kyung Hee University School of Medicine, Seoul, Korea
| | - Minha Hong
- Department of Psychiatry, Dankook University Medical College, Cheonan, Korea
| | - Juhee Han
- Department of Psychiatry, Kyung Hee University School of Medicine, Seoul, Korea
| | - Geon Ho Bahn
- Department of Psychiatry, Kyung Hee University School of Medicine, Seoul, Korea
- * E-mail:
| |
Collapse
|
13
|
Freund N, MacGillivilray HT, Thompson BS, Lukkes JL, Stanis JJ, Brenhouse HC, Andersen SL. Sex-dependent changes in ADHD-like behaviors in juvenile rats following cortical dopamine depletion. Behav Brain Res 2014; 270:357-63. [PMID: 24861711 DOI: 10.1016/j.bbr.2014.05.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 05/04/2014] [Accepted: 05/09/2014] [Indexed: 02/06/2023]
Abstract
Reduced cortical dopamine levels have been observed in individuals with attention deficit hyperactivity disorder (ADHD). Global dopamine depletions by 6-hydroxydopamine (6-OHDA; with noradrenergic protection) in neonatal rats produces locomotor hyperactivity, with less known about how cortical depletion modulates risky behaviors. Here, we determined the effect of a medial prefrontal cortex (PFC) 6-OHDA depletions (30-60%) or sham microinjection at postnatal day 11 on behavior in male and female juvenile rats. Separate groups were studied for delay discounting (impulsive choice), novelty-preference, and preferences for cues and environments associated with cocaine (10, 20, and 40 mg/kg), their extinction, and reinstatement with place conditioning. Because PFC D1 receptors play a role in these behaviors, confocal microscopy was used to measure D1-immunoreactive projections to the nucleus accumbens core. Both 6-OHDA males and females increased delay discounting relative to sham controls, although only 6-OHDA females increased novelty preferences. Preferences for cocaine-associated environments, their extinction, and reinstatement with a priming dose of cocaine were reduced in 6-OHDA subjects overall. However, impulsive choice at 5s positively correlated with preferences for cocaine-associated environments in 6-OHDA subjects, but not sham controls. As possible compensation for low dopamine levels, D1-immunoreactivity on traced neurons increased in 6-OHDA females; dopamine levels did not remain low in adolescent 6-OHDA males and D1 did not change. We believe that these modest depletions restricted to the PFC demonstrate the role of dopamine, and not norepinephrine, in understanding these behaviors in other animal models where cortical dopamine is reduced during development.
Collapse
Affiliation(s)
- Nadja Freund
- Laboratory for Developmental Neuropharmacology, McLean Hospital and Harvard Medical School, 115 Mill Street, Mail Stop 333, Belmont, MA 02478, USA.
| | - Heather T MacGillivilray
- Laboratory for Developmental Neuropharmacology, McLean Hospital and Harvard Medical School, 115 Mill Street, Mail Stop 333, Belmont, MA 02478, USA
| | - Britta S Thompson
- Laboratory for Developmental Neuropharmacology, McLean Hospital and Harvard Medical School, 115 Mill Street, Mail Stop 333, Belmont, MA 02478, USA.
| | - Jodi L Lukkes
- Laboratory for Developmental Neuropharmacology, McLean Hospital and Harvard Medical School, 115 Mill Street, Mail Stop 333, Belmont, MA 02478, USA.
| | - Jessica J Stanis
- Laboratory for Developmental Neuropharmacology, McLean Hospital and Harvard Medical School, 115 Mill Street, Mail Stop 333, Belmont, MA 02478, USA.
| | - Heather C Brenhouse
- Laboratory for Developmental Neuropharmacology, McLean Hospital and Harvard Medical School, 115 Mill Street, Mail Stop 333, Belmont, MA 02478, USA.
| | - Susan L Andersen
- Laboratory for Developmental Neuropharmacology, McLean Hospital and Harvard Medical School, 115 Mill Street, Mail Stop 333, Belmont, MA 02478, USA.
| |
Collapse
|
14
|
Gold MS, Blum K, Oscar-Berman M, Braverman ER. Low dopamine function in attention deficit/hyperactivity disorder: should genotyping signify early diagnosis in children? Postgrad Med 2014; 126:153-77. [PMID: 24393762 DOI: 10.3810/pgm.2014.01.2735] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Attention deficit/hyperactivity disorder (ADHD) is present in 8% to 12% of children, and 4% of adults worldwide. Children with ADHD can have learning impairments, poor selfesteem, social dysfunction, and an increased risk of substance abuse, including cigarette smoking. Overall, the rate of treatment with medication for patients with ADHD has been increasing since 2008, with ≥ 2 million children now being treated with stimulants. The rise of adolescent prescription ADHD medication abuse has occurred along with a concomitant increase of stimulant medication availability. Of adults presenting with a substance use disorder (SUD), 20% to 30% have concurrent ADHD, and 20% to 40% of adults with ADHD have a history of SUD. Following a brief review of the etiology of ADHD, its diagnosis and treatment, we focus on the benefits of early and appropriate testing for a predisposition to ADHD. We suggest that by genotyping patients for a number of known, associated dopaminergic polymorphisms, especially at an early age, misdiagnoses and/or over-diagnosis can be reduced. Ethical and legal issues of early genotyping are considered. As many as 30% of individuals with ADHD are estimated to either have secondary side-effects or are not responsive to stimulant medication. We also consider the benefits of non-stimulant medication and alternative treatment modalities, which include diet, herbal medications, iron supplementation, and neurofeedback. With the goals of improving treatment of patients with ADHD and SUD prevention, we encourage further work in both genetic diagnosis and novel treatment approaches.
Collapse
Affiliation(s)
- Mark S Gold
- Department of Psychiatry, School of Medicine and McKnight Brain Institute, University of Florida, Gainesville, FL.
| | | | | | | |
Collapse
|
15
|
Elia J, Wilson Z, La Porta LS, Algon SA, Prowler ML, Cartwright ST, McKenna PA, Laracy S, Takeda T, Borgmann-Winter K. Methylphenidate transdermal system: clinical applications for attention-deficit/hyperactivity disorder. Expert Rev Clin Pharmacol 2014; 4:311-28. [DOI: 10.1586/ecp.11.11] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
16
|
Fox H, Sinha R. The role of guanfacine as a therapeutic agent to address stress-related pathophysiology in cocaine-dependent individuals. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 69:217-65. [PMID: 24484979 DOI: 10.1016/b978-0-12-420118-7.00006-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The pathophysiology of cocaine addiction is linked to changes within neural systems and brain regions that are critical mediators of stress system sensitivity and behavioral processes associated with the regulation of adaptive goal-directed behavior. This is characterized by the upregulation of core adrenergic and corticotropin-releasing factor mechanisms that subserve negative affect and anxiety and impinge upon intracellular pathways in the prefrontal cortex underlying cognitive regulation of stress and negative emotional state. Not only are these mechanisms essential to the severity of cocaine withdrawal symptoms, and hence the trajectory of clinical outcome, but also they may be particularly pertinent to the demography of cocaine dependence. The ability of guanfacine to target overlapping stress, reward, and anxiety pathophysiology suggests that it may be a useful agent for attenuating the stress- and cue-induced craving state not only in women but also in men. This is supported by recent research findings from our own laboratory. Additionally, the ability of guanfacine to improve regulatory mechanisms that are key to exerting cognitive and emotional control over drug-seeking behavior also suggests that guanfacine may be an effective medication for reducing craving and relapse vulnerability in many drugs of abuse. As cocaine-dependent individuals are typically polydrug abusers and women may be at a greater disadvantage for compulsive drug use than men, it is plausible that medications that target catecholaminergic frontostriatal inhibitory circuits and simultaneously reduce stress system arousal may provide added benefits for attenuating cocaine dependence.
Collapse
Affiliation(s)
- Helen Fox
- Yale Stress Center, Yale University School of Medicine, New Haven Connecticut USA.
| | - Rajita Sinha
- Yale Stress Center, Yale University School of Medicine, New Haven Connecticut USA
| |
Collapse
|
17
|
Levy F. Child psychopharmacology: politics versus science. Aust N Z J Psychiatry 2013; 47:961. [PMID: 23888073 DOI: 10.1177/0004867413498938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Florence Levy
- School of Psychiatry, Prince of Wales Hospital, Sydney, Australia
| |
Collapse
|
18
|
Bari A, Robbins TW. Inhibition and impulsivity: Behavioral and neural basis of response control. Prog Neurobiol 2013; 108:44-79. [DOI: 10.1016/j.pneurobio.2013.06.005] [Citation(s) in RCA: 1193] [Impact Index Per Article: 108.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 05/24/2013] [Accepted: 06/26/2013] [Indexed: 11/17/2022]
|
19
|
Sallee F, Connor DF, Newcorn JH. A review of the rationale and clinical utilization of α2-adrenoceptor agonists for the treatment of attention-deficit/hyperactivity and related disorders. J Child Adolesc Psychopharmacol 2013; 23:308-19. [PMID: 23782125 DOI: 10.1089/cap.2013.0028] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Interest in the potential role for the α2-adrenoceptor agonists clonidine and guanfacine as treatments for attention-deficit/hyperactivity disorder (ADHD) has driven additional clinical studies as well as development of new formulations of these agents. This article reviews the published data that supported United States Food and Drug Administration approval and subsequent clinical use of α2-adrenoceptor agonists in the treatment of ADHD, and identifies promising directions for future research. METHODS Electronic searches were performed in PubMed through October 2012 using the base terms ADHD or attention deficit hyperactivity disorder and alpha agonists, as well as the following limits: humans, clinical trial, meta-analysis, practice guideline, randomized controlled trial, review, English. The electronic searches were complemented with reference lists from the articles retrieved by informal search of the literature, producing a qualitative review of published, pertinent drug-class preclinical and clinical data. Articles were selected for greater exposition based on hierarchy of evidence (e.g., randomized controlled trials), relevance, and quality of individual studies, as well as generalizability to clinical practice. RESULTS Results of clinical studies of immediate-release and extended-release formulations of α2-adrenoceptor agonists and basic science investigations of cognitive effects of these drugs are discussed. Studies of both clonidine and guanfacine extended-release formulations as monotherapy and adjunctive therapy with psychostimulants for the treatment of ADHD are also reviewed. CONCLUSIONS Large, randomized, placebo-controlled clinical trials support the efficacy and safety of α2-adrenoceptor agonists as monotherapy and adjunctive therapy with psychostimulants for the symptomatic treatment of ADHD. Future research could reveal whether there are cognitive benefits associated with this drug class and thus further define the role of α2-adrenoceptor agonists in the treatment of ADHD.
Collapse
Affiliation(s)
- Floyd Sallee
- Department of Psychiatry, University of Cincinnati, Cincinnati, OH 45219, USA.
| | | | | |
Collapse
|
20
|
Cognitive and emotional behavioural changes associated with methylphenidate treatment: a review of preclinical studies. Int J Neuropsychopharmacol 2012; 15:41-53. [PMID: 21439107 DOI: 10.1017/s1461145711000472] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
There is evidence from animal studies that repeated exposure to methylphenidate (MPH), a widely used psychostimulant for the treatment of attention deficit hyperactivity disorder (ADHD), produces behavioural, structural and neurochemical changes that persist long after drug administration has ended. However, the translational utility of much of this work is compromised by the use of drug doses and routes of administration that produce plasma and brain MPH levels that fall outside the clinical range, i.e. experimental parameters more relevant to drug abuse than ADHD. We used PubMed to identify pre-clinical studies that employed repeated MPH administration at low doses in young rodents and examined long-term effects on cognition, emotion, and brain structure and function. A review of this work suggests that repeated MPH treatment during early development can modify a number of cognitive, behavioural and brain processes, but these are reduced when low therapeutic doses are employed. Moreover, MPH sites of action extend beyond those implicated in ADHD. Studies that combined neurobiological and behavioural approaches provide important insights into the mechanisms underlying MPH-produced effects on cognitive and behavioural processes, which may be relevant to MPH therapeutic efficacy. There is an emerging consensus that pharmacological treatment of childhood psychiatric disorders produces persistent neuroadaptations, highlighting the need for studies that assess long-term effects of early developmental pharmacotherapy. In this regard, studies that mimic clinical therapy with rodents are useful experimental approaches for defining the behavioural and neural plasticity associated with stimulant therapy in paediatric populations.
Collapse
|
21
|
Freese L, Signor L, Machado C, Ferigolo M, Barros HMT. Non-medical use of methylphenidate: a review. TRENDS IN PSYCHIATRY AND PSYCHOTHERAPY 2012; 34:110-5. [DOI: 10.1590/s2237-60892012000200010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 11/11/2011] [Indexed: 11/21/2022]
Abstract
INTRODUCTION: Methylphenidate is a psychostimulant medication used for the treatment of attention deficit hyperactivity disorder and narcolepsy. However, it has also been used for non-medical purposes, e.g. to produce euphoria, to increase self-esteem, and to achieve the so-called neurocognitive enhancement, decreasing the feeling of tiredness and increasing focus and attention. OBJECTIVE: To describe, from theoretical and contextual points of view, the potential for abuse and non-medical use of methylphenidate. METHOD: The PubMed, SciELO and Cochrane databases were searched using the following keywords in Portuguese: metilfenidato, transtorno do déficit de atenção com hiperatividade, facilitadores dos processos cognitivos or agentes nootrópicos, and abuso de substâncias; and in English: methylphenidate, attention deficit disorder with hyperactivity, cognitive enhancement or nootropic agents, and substance abuse. Studies published between 1990 and 2010 were selected for review. RESULTS: Non-medical use of methylphenidate is a relevant topic that raises important ethical and scientific questions in several areas, e.g. pharmacological and neurobiological characteristics, evidence of methylphenidate use, forms of non-medical use of methylphenidate, mechanisms of action, and therapeutic application of methylphenidate. According to the review, methylphenidate can generally influence performance as a result of its stimulatory effect. Notwithstanding, evidence does not support the conclusion that it can enhance cognitive performance. CONCLUSION: Health professionals need to acquire expert knowledge and inform patients and their families on the methylphenidate potential for abuse when used with non-medical purposes.
Collapse
|
22
|
Abstract
Clonidine, an α(2)-adrenergic agonist, is approved in the US as an extended-release (XR) tablet for the treatment of attention-deficit hyperactivity disorder (ADHD) in children and adolescents (aged 6-17 years). In two, randomized, double-blind, multicenter, phase III trials of 8 weeks' duration, clonidine XR improved the symptoms of ADHD in children and adolescents. Significantly greater reductions from baseline in ADHD rating scale IV (ADHD-RS-IV) total scores at week 5 (primary endpoint) were achieved by recipients of clonidine XR 0.2 and 0.4 mg/day monotherapy than by recipients of placebo. When added to patients' normal stimulant regimen, significantly greater reductions from baseline in ADHD-RS-IV total scores at week 5 (primary endpoint) were achieved with a flexible dose of clonidine XR 0.1-0.4 mg/day than with placebo. Symptomatic improvement of ADHD was achieved following 2 weeks' treatment with clonidine XR. In both trials, significantly greater reductions from baseline in ADHD-RS-IV total scores were apparent at week 2 onwards for recipients of clonidine XR than for recipients of placebo. Clonidine XR was generally well tolerated as monotherapy and as adjunctive therapy with stimulant regimens in clinical trials in children and adolescents.
Collapse
|
23
|
Sallee FR, Eaton K. Guanfacine extended-release for attention-deficit/hyperactivity disorder (ADHD). Expert Opin Pharmacother 2011; 11:2549-56. [PMID: 20831361 DOI: 10.1517/14656566.2010.517523] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
IMPORTANCE OF THE FIELD Guanfacine extended-release (GXR) is a non-stimulant approved in the US for treatment of attention deficit/hyperactivity disorder (ADHD). GXR is a 'first in class' α(2A)-adrenoceptor agonist reformulated to optimize efficacy. GXR enters a rapidly growing but crowded ADHD market as an alternative not only to psychostimulants but also to atomoxetine. AREAS COVERED IN THIS REVIEW Pharmacodynamics, pharmacokinetics, clinical efficacy and safety of GXR are covered based on a literature review (MEDLINE and EMBASE) from 1980 to 2010. Two large pivotal controlled trials are reviewed along with companion safety studies over 24 months. Collateral studies in ADHD children with oppositional symptoms and combination use of GXR in psychostimulant partial-responders are featured. WHAT THE READER WILL GAIN Novel aspects of apparent GXR mechanism of action may complement existing treatments. Study evidence indicates that GXR is a well-tolerated and effective treatment for children and adolescents with ADHD, and appears efficacious to reduce oppositional symptoms in children with these complicating features. The GXR safety database reflects mild and asymptomatic decreases in both blood pressure and heart rate throughout, with most adverse events being somnolence-related and time-limited. TAKE HOME MESSAGE This review of GXR will allow the reader to determine the place for GXR in the ADHD treatment landscape.
Collapse
Affiliation(s)
- Floyd R Sallee
- University of Cincinnati, Department of Psychiatry, OH 45219, USA.
| | | |
Collapse
|
24
|
Ancín I, Cabranes JA, Vázquez-Álvarez B, Santos JL, Sánchez-Morla E, García-Jiménez MÁ, Fernández C, Barabash A. Sensory gating deficit is associated with catechol-O-methyltransferase polymorphisms in bipolar disorder. World J Biol Psychiatry 2011; 12:376-84. [PMID: 21595525 DOI: 10.3109/15622975.2011.552192] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVES. Recent studies have evidenced that bipolar patients show a sensory gating deficit (P50). Among the neural systems that could be influencing this electrophysiological phenotype, dopamine seems to play an important role. We hypothesize that catechol-O-methyltransferase (COMT), the main metabolizer of dopamine in prefrontal cortex, is related to this deficit. METHODS. We selected three polymorphisms in COMT gene: rs2075507 (Promoter 2 region), Val158Met (rs4680) and rs165599 (3' region). A case-control study was performed in 784 controls and 238 bipolar patients. Besides, 122 euthymic bipolar subjects and 95 healthy subjects carried out a sensory gating task (P50). RESULTS. Polymorphism rs165599 in the COMT gene was associated with susceptibility to bipolar disorder (BD), mainly in women (AG: OR = 1.46; GG: OR = 1.84; P = 0.03). In the female group, haplotype AAG was associated with an OR = 7.6. Subjects who carried Val158 allele evidenced a deficit in suppression (P = 0.046) and rs165599 allele G carriers (mainly in homozygosis) had a bigger S2 amplitude and a higher S2/S1 ratio (1.6(e-5) < P < 0.01). Not a single association was proven in the control group. CONCLUSIONS. Our results support the association of the COMT gene with BD and with one of its potential endophenotypes, auditory sensory gating deficit, measured by the P50 paradigm.
Collapse
Affiliation(s)
- Inés Ancín
- Laboratory of Psychoneuroendocrinology and Molecular Genetics. Biomedical Research Foundation, Clínico San Carlos Hospital, Madrid, Spain
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Koziol LF, Budding DE, Chidekel D. Adaptation, expertise, and giftedness: towards an understanding of cortical, subcortical, and cerebellar network contributions. THE CEREBELLUM 2011; 9:499-529. [PMID: 20680539 DOI: 10.1007/s12311-010-0192-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Current cortico-centric models of cognition lack a cohesive neuroanatomic framework that sufficiently considers overlapping levels of function, from "pathological" through "normal" to "gifted" or exceptional ability. While most cognitive theories presume an evolutionary context, few actively consider the process of adaptation, including concepts of neurodevelopment. Further, the frequent co-occurrence of "gifted" and "pathological" function is difficult to explain from a cortico-centric point of view. This comprehensive review paper proposes a framework that includes the brain's vertical organization and considers "giftedness" from an evolutionary and neurodevelopmental vantage point. We begin by discussing the current cortico-centric model of cognition and its relationship to intelligence. We then review an integrated, dual-tiered model of cognition that better explains the process of adaptation by simultaneously allowing for both stimulus-based processing and higher-order cognitive control. We consider the role of the basal ganglia within this model, particularly in relation to reward circuitry and instrumental learning. We review the important role of white matter tracts in relation to speed of adaptation and development of behavioral mastery. We examine the cerebellum's critical role in behavioral refinement and in cognitive and behavioral automation, particularly in relation to expertise and giftedness. We conclude this integrated model of brain function by considering the savant syndrome, which we believe is best understood within the context of a dual-tiered model of cognition that allows for automaticity in adaptation as well as higher-order executive control.
Collapse
|
26
|
Fragile X syndrome and associated disorders. ADVANCES IN CHILD DEVELOPMENT AND BEHAVIOR 2011; 39:211-35. [PMID: 21189809 DOI: 10.1016/b978-0-12-374748-8.00006-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
27
|
Hertz L, Lovatt D, Goldman SA, Nedergaard M. Adrenoceptors in brain: cellular gene expression and effects on astrocytic metabolism and [Ca(2+)]i. Neurochem Int 2010; 57:411-20. [PMID: 20380860 PMCID: PMC2934885 DOI: 10.1016/j.neuint.2010.03.019] [Citation(s) in RCA: 163] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2009] [Revised: 03/02/2010] [Accepted: 03/31/2010] [Indexed: 11/24/2022]
Abstract
Recent in vivo studies have established astrocytes as a major target for locus coeruleus activation (Bekar et al., 2008), renewing interest in cell culture studies on noradrenergic effects on astrocytes in primary cultures and calling for additional information about the expression of adrenoceptor subtypes on different types of brain cells. In the present communication, mRNA expression of alpha(1)-, alpha(2)- and beta-adrenergic receptors and their subtypes was determined in freshly isolated, cell marker-defined populations of astrocytes, NG2-positive cells, microglia, endothelial cells, and Thy1-positive neurons (mainly glutamatergic projection neurons) in murine cerebral cortex. Immediately after dissection of frontal, parietal and occipital cortex of 10-12-week-old transgenic mice, which combined each cell-type marker with a specific fluorescent signal, the tissue was digested, triturated and centrifuged, yielding a solution of dissociated cells of all types, which were separated by fluorescence-activated cell sorting (FACS). mRNA expression in each cell fraction was determined by microarray analysis. alpha(1A)-Receptors were unequivocally expressed in astrocytes and NG2-positive cells, but absent in other cell types, and alpha(1B)-receptors were not expressed in any cell population. Among alpha(2)-receptors only alpha(2A)-receptors were expressed, unequivocally in astrocytes and NG-positive cells, tentatively in microglia and questionably in Thy1-positive neurons and endothelial cells. beta(1)-Receptors were unequivocally expressed in astrocytes, tentatively in microglia, and questionably in neurons and endothelial cells, whereas beta(2)-adrenergic receptors showed tentative expression in neurons and astrocytes and unequivocal expression in other cell types. This distribution was supported by immunochemical data and its relevance established by previous studies in well-differentiated primary cultures of mouse astrocytes, showing that stimulation of alpha(2)-adrenoceptors increases glycogen formation and oxidative metabolism, the latter by a mechanism depending on intramitochondrial Ca(2+), whereas alpha(1)-adrenoceptor stimulation enhances glutamate uptake, and beta-adrenoceptor activation causes glycogenolysis and increased Na(+), K(+)-ATPase activity. The Ca(2+)- and cAMP-mediated association between energy-consuming and energy-yielding processes is emphasized.
Collapse
MESH Headings
- Animals
- Astrocytes/metabolism
- Brain Chemistry/genetics
- Brain Chemistry/physiology
- Calcium Signaling/physiology
- Cell Separation
- Cells, Cultured
- Flow Cytometry
- Gene Expression/physiology
- Glucose/metabolism
- Glycogen/metabolism
- Mice
- Mice, Transgenic/physiology
- Microarray Analysis
- Mitochondria/metabolism
- Oxidation-Reduction
- Pyruvic Acid/metabolism
- RNA/biosynthesis
- RNA/genetics
- Receptors, Adrenergic/biosynthesis
- Receptors, Adrenergic/genetics
- Receptors, Adrenergic, alpha-1/biosynthesis
- Receptors, Adrenergic, alpha-1/genetics
- Receptors, Adrenergic, alpha-2/biosynthesis
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, beta/biosynthesis
- Receptors, Adrenergic, beta/genetics
Collapse
Affiliation(s)
- Leif Hertz
- Department of Clinical Pharmacology, College of Basic Medical Sciences, China Medical University, Shenyang, P. R. China
| | - Ditte Lovatt
- Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY 14642
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642
| | - Steven A. Goldman
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642
| | - Maiken Nedergaard
- Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY 14642
| |
Collapse
|
28
|
Engert V, Pruessner JC. Dopaminergic and noradrenergic contributions to functionality in ADHD: the role of methylphenidate. Curr Neuropharmacol 2010; 6:322-8. [PMID: 19587853 PMCID: PMC2701285 DOI: 10.2174/157015908787386069] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 07/18/2008] [Accepted: 08/04/2008] [Indexed: 12/23/2022] Open
Abstract
Attention Deficit Hyperactivity Disorder (ADHD) is a childhood psychiatric condition characterized by severe impulsiveness, inattention and overactivity. Methylphenidate (MPH), a psychostimulant affecting both the dopaminergic and the noradrenergic systems, is one of the most frequently prescribed treatments for ADHD. Despite the widespread use of MPH and its proven effectiveness, its precise neurochemical mechanisms of action are under debate. For the most part, MPH’s influence on subcortical dopamine neurotransmission is thought to play a crucial role in its behavioral and cognitive effects. In their hypothesis of biphasic MPH action, Seeman and Madras [42, 43] suggest that therapeutic doses of MPH elevate tonic dopamine while inhibiting phasic transmitter release in subcortical structures, leading to reduced postsynaptic receptor stimulation and psychomotor activation in response to salient stimuli. Volkow and colleagues [56] suggest that by amplifying a weak striatal dopamine signal, MPH increases the perception of a stimulus or task as salient. The enhanced interest for the task is thought to increase attention and improve performance. Recent animal studies have however shown that when administered at doses producing clinically relevant drug plasma levels and enhancing cognitive function, MPH preferentially activates dopamine and noradrenaline efflux within the prefrontal cortex relative to the subcortical structures [5]. Overall, we suggest that the delineated theories of MPH therapeutic action should not be discussed as exclusive. Studies are outlined that allow integrating the different findings and models.
Collapse
Affiliation(s)
- Veronika Engert
- Douglas Mental Health University Institute, Department of Psychiatry, McGill University, Montreal, Quebec, Canada H4H 1R3.
| | | |
Collapse
|
29
|
Affiliation(s)
- Diane E May
- Department of Psychiatry, University of Nebraska Medical Center, Omaha, Nebraska 68198-5581, USA
| | | |
Collapse
|
30
|
Gyires K, Zádori ZS, Török T, Mátyus P. α2-Adrenoceptor subtypes-mediated physiological, pharmacological actions. Neurochem Int 2009; 55:447-53. [DOI: 10.1016/j.neuint.2009.05.014] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 05/16/2009] [Accepted: 05/18/2009] [Indexed: 11/29/2022]
|
31
|
Vilkman H, Kajander J, Aalto S, Vahlberg T, Någren K, Allonen T, Syvälahti E, Hietala J. The effects of lorazepam on extrastriatal dopamine D(2/3)-receptors-A double-blind randomized placebo-controlled PET study. Psychiatry Res 2009; 174:130-7. [PMID: 19846281 DOI: 10.1016/j.pscychresns.2009.04.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 04/19/2009] [Accepted: 04/19/2009] [Indexed: 11/28/2022]
Abstract
Lorazepam is a widely used anxiolytic drug of the benzodiazepine class. The clinical actions of benzodiazepines are thought to be mediated via specific allosteric benzodiazepine binding sites and enhancement of GABAergic neurotransmission in the brain. However, the indirect effects of benzodiazepines on other neurotransmitter systems have not been extensively studied. Previous experimental evidence suggests that benzodiazepines inhibit striatal dopamine release by enhancing the GABAergic inhibitory effect on dopamine neurons whereas very little is known about cortical or thalamic gamma-amino-butyric (GABA)-dopamine interactions during benzodiazepine administration. We explored the effects of lorazepam (a single 2.5 mg dose) on cortical and thalamic D(2/3) receptor binding using Positron-Emission Tomography (PET) and the high-affinity D(2/3)-receptor ligand [(11)C]FLB 457 in 12 healthy male volunteers. We used a randomized, double-blind and placebo-controlled study design. Dopamine D(2)/D(3) receptor binding potential was measured with the reference tissue method in several extrastriatal D(2)-receptor areas including frontal, parietal, temporal cortices and thalamus. The main subjective effect of lorazepam was sedation. Lorazepam induced a statistically significant decrease of D(2)/D(3) receptor BP(ND) in medial temporal and dorsolateral prefrontal cortex (DLPFC) that was also confirmed by a voxel-level analysis. The sedative effect of lorazepam was associated with a decrease in D(2)/D(3) receptor BP(ND) in the DLPFC. In conclusion, lorazepam decreased [(11)C]FLB 457 binding in frontal and temporal cortex, suggesting that cortical GABA-dopamine interaction may be involved in the central actions of lorazepam in healthy volunteers. The correlation between lorazepam-induced sedation and D(2)/D(3) receptor binding potential (BP) change further supports this hypothesis.
Collapse
Affiliation(s)
- Harry Vilkman
- Turku PET Centre, University of Turku, Turku, Finland
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Livingstone PD, Wonnacott S. Nicotinic acetylcholine receptors and the ascending dopamine pathways. Biochem Pharmacol 2009; 78:744-55. [DOI: 10.1016/j.bcp.2009.06.004] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 06/04/2009] [Accepted: 06/04/2009] [Indexed: 11/28/2022]
|
33
|
Amphetamine decreases behavioral inhibition by stimulation of dopamine D2, but not D3, receptors. Behav Pharmacol 2009; 20:484-91. [DOI: 10.1097/fbp.0b013e3283305e3b] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
|
34
|
Curatolo P, Paloscia C, D'Agati E, Moavero R, Pasini A. The neurobiology of attention deficit/hyperactivity disorder. Eur J Paediatr Neurol 2009; 13:299-304. [PMID: 18644740 DOI: 10.1016/j.ejpn.2008.06.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Revised: 05/25/2008] [Accepted: 06/01/2008] [Indexed: 10/21/2022]
Abstract
ADHD is a brain based disorder with structural and functional abnormalities in widespread but specific areas of the brain. The most significant and consistent structural imaging findings include smaller total brain volumes, and reduced volumes in the right frontal lobe, right parietal cortex, caudate nucleus, cerebellar hemispheres, and posterior-inferior lobules of the cerebellar vermis. ADHD involves hypofunction of catecholaminergic circuits, particularly those that project to the prefrontal cortex. A minimum of 18 genes have been reported to be associated with the disorder; among them the DRD4 7-repeat allele has been found associated with a thinner prefrontal and posterior parietal cortex. Epigenetic factors acting during critical periods of prenatal and postnatal development may interact with genetic determinants. Methylphenidate, as well as the catecholaminergic nonstimulant atomoxetine, are effective in improving ADHD symptoms.
Collapse
Affiliation(s)
- Paolo Curatolo
- Department of Neuroscience, Pediatric Neurology Unit, Tor Vergata University of Rome, Rome, Italy.
| | | | | | | | | |
Collapse
|
35
|
Dinh L, Nguyen T, Salgado H, Atzori M. Norepinephrine homogeneously inhibits alpha-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate- (AMPAR-) mediated currents in all layers of the temporal cortex of the rat. Neurochem Res 2009; 34:1896-906. [PMID: 19357950 DOI: 10.1007/s11064-009-9966-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Accepted: 03/26/2009] [Indexed: 11/25/2022]
Abstract
The primary auditory cortex is subject to the modulation of numerous neurotransmitters including norepinephrine (NE), which has been shown to decrease cellular excitability by yet unclear mechanisms. We investigated the possibility that NE directly affects excitatory glutamatergic synapses. We found that bath applications of NE (20 microM) decreased glutamatergic excitatory post-synaptic currents (EPSCs) in all cortical layers. Changes in the kinetics of synaptic EPSCs, invariance of pair pulse ratio and of the coefficient-of-variation, together with the decrease of responses to pressure-application of AMPA (500 microM), indicated the postsynaptic nature of the adrenergic effect. Pharmacological experiments suggested that the NE-induced depression of EPSCs is caused by the activation of alpha1 adrenoceptors, PLC, and a Ca(2+)-independent PKC. We speculate that the decrease in temporal cortex excitability might promote a posterior-to-anterior shift in cortical activation together with a decrease in spontaneous background activity, resulting eventually in more effective sensory processing.
Collapse
Affiliation(s)
- Lu Dinh
- The University of Texas at Dallas, Richardson, TX 75080, USA
| | | | | | | |
Collapse
|
36
|
Livingstone PD, Srinivasan J, Kew JN, Dawson LA, Gotti C, Moretti M, Shoaib M, Wonnacott S. α7 and non-α7 nicotinic acetylcholine receptors modulate dopamine releasein vitroandin vivoin the rat prefrontal cortex. Eur J Neurosci 2009; 29:539-50. [DOI: 10.1111/j.1460-9568.2009.06613.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
37
|
Abstract
The aim of the present study was to review the dopamine theory of attention-deficit-hyperactivity disorder (ADHD), in light of recent use of noradrenergic therapies. A historical review of pharmacological theories of ADHD was conducted, including inverted-U, spatial working memory and neural circuit aspects. Pharmacological advances, including animal and human studies of dopaminergic and noradrenergic mechanisms at the prefrontal cortex (PFC), indicate that alpha-2A adrenoreceptor stimulation results in increased dendritic firing during delay periods for preferred directions, while moderate levels of D1 receptor stimulation result in reduction of delay-related firing to non-preferred directions, allowing representational control in the PFC. Recent studies of the COMT val/met gene and stimulant medication response may help explain variation in inverted-U responses in individuals. Further studies utilizing delay-related firing paradigms should be useful in the investigation of attentional syndromes, and responses to newer pharmacological treatments.
Collapse
Affiliation(s)
- Florence Levy
- School of Psychiatry, University of New South Wales,, Prince of Wales Hospital, Randwick, New South Wales, Australia.
| |
Collapse
|
38
|
Hyperstimulation of striatal D2 receptors with sleep deprivation: Implications for cognitive impairment. Neuroimage 2009; 45:1232-40. [PMID: 19349237 DOI: 10.1016/j.neuroimage.2009.01.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Revised: 12/30/2008] [Accepted: 01/05/2009] [Indexed: 11/24/2022] Open
Abstract
Sleep deprivation interferes with cognitive performance but the mechanisms are poorly understood. We recently reported that one night of sleep deprivation increased dopamine in striatum (measured with [(11)C]raclopride, a PET radiotracer that competes with endogenous dopamine for binding to D2 receptors) and that these increases were associated with impaired performance in a visual attention task. To better understand this association here we evaluate the relationship between changes in striatal dopamine (measured as changes in D2 receptor availability using PET and [(11)C]raclopride) and changes in brain activation to a visual attention task (measured with BOLD and fMRI) when performed during sleep deprivation versus during rested wakefulness. We find that sleep induced changes in striatal dopamine were associated with changes in cortical brain regions modulated by dopamine (attenuated deactivation of anterior cingulate gyrus and insula) but also in regions that are not recognized targets of dopaminergic modulation (attenuated activation of inferior occipital cortex and cerebellum). Moreover, the increases in striatal dopamine as well as its associated regional activation and deactivation patterns correlated negatively with performance accuracy. These findings therefore suggest that hyperstimulation of D2 receptors in striatum may contribute to the impairment in visual attention during sleep deprivation. Thus, while dopamine increases in prefrontal regions (including stimulation of D1 receptors) may facilitate attention our findings suggest that hyperstimulation of D2 receptors in striatum may impair it. Alternatively, these associations may reflect a compensatory striatal dopamine response (to maintain arousal) that is superimposed on a larger response to sleep deprivation.
Collapse
|
39
|
Bhat V, Grizenko N, Sanche S, Joober R. No Relation between Therapeutic Response to Methylphenidate and its Cardiovascular Side Effects in Children with Attention-Deficit/Hyperactivity Disorder. CLINICAL MEDICINE. PEDIATRICS 2008. [DOI: 10.4137/cmped.s1010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Objective The aim of this study was to examine the relation between therapeutic response to methylphenidate (MPH) and its associated short term cardiovascular side effects (Systolic Blood Pressure-SBP, Diastolic Blood Pressure-DBP and Heart Rate-HR changes) in children with ADHD, based on the hypothesis that these parameters share common underlying mechanisms. Method A double-blind placebo-controlled crossover clinical trial of children 6 to 12 years old diagnosed with ADHD was done. The children were given one week of 0.5 mg/kg MPH and one week of placebo (divided into two equal doses, given twice every day). On the morning of the third day of each week, Blood Pressure (BP) and HR were recorded immediately before (at time 0) and after (at time 10 and 45 minutes) administration of MPH. Children were grouped into 4 categories according to their therapeutic response (large, moderate, mild or no response) to MPH. A mixed model analysis of variance was performed to determine whether response groups were different with regard to cardiovascular side effects. Results All variables were comparable among the four groups 10 min after treatment with MPH and with placebo. Small but significant (p < 0.001) increases were seen in SBP (3.65 mm of Hg) and DBP (3.99 mm of Hg) 45 minutes after administration of MPH. A small but significant decrease in HR (3.3 beats per minute) was observed 45 min after administration of placebo. No significant differences in SBP, DBP and HR were found between response groups. Conclusions MPH causes a small but significant change in BP at 45 minutes after administration. No changes in HR were observed with MPH at 45 minutes. Responders to MPH treatment do not differ from non-responders in occurrence of BP and HR changes, at least within 45 minutes after administration and with the MPH dosage used in the study.
Collapse
Affiliation(s)
| | | | - Steven Sanche
- Douglas Mental Health University Institute, Montreal, Canada
| | - Ridha Joober
- Douglas Mental Health University Institute, Montreal, Canada
| |
Collapse
|
40
|
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is a heterogeneous disease that affects children, adolescents, and adults. Genetic research has confirmed that there is a large hereditary component to this condition and has helped identify some of the genes associated with it. Among these are several genes associated with the catecholaminergic system including the dopamine receptor genes (DRD4 and DRD5), the dopamine transporter gene, and the gene for dopamine beta-hydroxylase, which catalyzes conversion of dopamine to norepinephrine. Attention-deficit/hyperactivity disorder is believed to be a result of abnormalities in the frontal regions of the brain, particularly the prefrontal cortex and associated subcortical structures and circuits. Underpinning these abnormalities are disturbances of catecholamine neurotransmission. Studies have demonstrated that patients with ADHD have depleted levels of dopamine and norepinephrine thought to be largely the result of dysfunction of their respective transporter systems. The efficacy of stimulant agents confirms that the neurotransmitter abnormalities seen in ADHD are primarily catecholaminergic in origin. This article focuses on the catecholaminergic networks of higher cognitive functions such as attention and focus and of motor functions that may be associated with such networks, reviewing both the physiology of such functions and the pathophysiology of ADHD. Researchers are currently investigating whether other neurotransmitter systems may be partially involved and are investigating whether agents that affect these other systems will prove complementary to currently used treatments.
Collapse
|