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Fox ME, Wightman RM. Contrasting Regulation of Catecholamine Neurotransmission in the Behaving Brain: Pharmacological Insights from an Electrochemical Perspective. Pharmacol Rev 2017; 69:12-32. [PMID: 28267676 DOI: 10.1124/pr.116.012948] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Catecholamine neurotransmission plays a key role in regulating a variety of behavioral and physiologic processes, and its dysregulation is implicated in both neurodegenerative and neuropsychiatric disorders. Over the last four decades, in vivo electrochemistry has enabled the discovery of contrasting catecholamine regulation in the brain. These rapid and spatially resolved measurements have been conducted in brain slices, and in anesthetized and freely behaving animals. In this review, we describe the methods enabling in vivo measurements of dopamine and norepinephrine, and subsequent findings regarding their release and regulation in intact animals. We thereafter discuss key studies in awake animals, demonstrating that these catecholamines are not only differentially regulated, but are released in opposition of each other during appetitive and aversive stimuli.
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Affiliation(s)
- Megan E Fox
- Department of Chemistry and Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina
| | - R Mark Wightman
- Department of Chemistry and Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina
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Rajkumar R, Kumar JR, Dawe GS. Priming locus coeruleus noradrenergic modulation of medial perforant path-dentate gyrus synaptic plasticity. Neurobiol Learn Mem 2016; 138:215-225. [PMID: 27400867 DOI: 10.1016/j.nlm.2016.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 06/30/2016] [Accepted: 07/06/2016] [Indexed: 01/09/2023]
Abstract
Priming phenomenon, in which an earlier exposure to a stimulus or condition alters synaptic plasticity in response to a subsequent stimulus or condition, known as a challenge, is an example of metaplasticity. In this review, we make the case that the locus coeruleus noradrenergic system-medial perforant path-dentate gyrus pathway is a neural ensemble amenable to studying priming-challenge effects on synaptic plasticity. Accumulating evidence points to a tyrosine hydroxylase-dependent priming effect achieved by pharmacological (nicotine and antipsychotics) or physiological (septal theta driving) manipulations of the locus coeruleus noradrenergic system that can facilitate noradrenaline-induced synaptic plasticity in the dentate gyrus of the hippocampus. The evidence suggests the hypothesis that behavioural experiences inducing tyrosine hydroxylase expression in the locus coeruleus may be sufficient to prime this form of metaplasticity. We propose exploring this phenomenon of priming and challenge physiologically, to determine whether behavioural experiences are sufficient to prime the locus coeruleus, enabling subsequent pharmacological or behavioural challenge conditions that increase locus coeruleus firing to release sufficient noradrenaline to induce long-lasting potentiation in the dentate gyrus. Such an approach may contribute to unravelling mechanisms underlying this form of metaplasticity and its importance in stress-related mnemonic processes.
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Affiliation(s)
- Ramamoorthy Rajkumar
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, 117600, Singapore; Neurobiology and Ageing Programme, Life Sciences Institute, National University of Singapore, 117456, Singapore; Singapore Institute for Neurotechnology (SINAPSE), 117456, Singapore
| | - Jigna Rajesh Kumar
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, 117600, Singapore; Neurobiology and Ageing Programme, Life Sciences Institute, National University of Singapore, 117456, Singapore; Singapore Institute for Neurotechnology (SINAPSE), 117456, Singapore; NUS Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, 117456, Singapore
| | - Gavin S Dawe
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, 117600, Singapore; Neurobiology and Ageing Programme, Life Sciences Institute, National University of Singapore, 117456, Singapore; Singapore Institute for Neurotechnology (SINAPSE), 117456, Singapore; NUS Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, 117456, Singapore.
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Liu YP, Huang TS, Tung CS, Lin CC. Effects of atomoxetine on attention and impulsivity in the five-choice serial reaction time task in rats with lesions of dorsal noradrenergic ascending bundle. Prog Neuropsychopharmacol Biol Psychiatry 2015; 56:81-90. [PMID: 25151304 DOI: 10.1016/j.pnpbp.2014.08.007] [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: 05/19/2014] [Revised: 08/04/2014] [Accepted: 08/16/2014] [Indexed: 10/24/2022]
Abstract
Atomoxetine, a noradrenaline reuptake inhibitor (NRI), which is a non-stimulating medicine that is used for the treatment of patients with attention deficit hyperactivity disorder (ADHD), has been found to be effective in reducing behavioral impulsivity in rodents, but its efficacy in a dorsal noradrenergic ascending bundle (DNAB)-lesioned condition has not been examined. The present study aimed to investigate the effects of DNAB lesions on attention and impulsive control in the five-choice serial reaction time task (5-CSRTT) in rats treated with atomoxetine. The drug-induced changes in noradrenaline efflux in the medial prefrontal cortex were also measured. 5-CSRTT-trained rats were included in one of the following groups: N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4)/Atomoxetine, Sham/Atomoxetine, DSP-4/Saline, or Sham/Saline. Acute atomoxetine (0.3 mg/kg) was administered 14 days after the DSP-4 regime. The behavioral testing included manipulations of the inter-trial interval (ITI), stimulation duration and food satiety. In vivo microdialysis of the noradrenaline efflux in the medial prefrontal cortex and the expression of the noradrenaline transporter (NAT) in the DNAB areas were examined. Atomoxetine reduced impulsivity and perseveration in the long-ITI condition with no effects on any other variables. This phenomenon was not influenced by DSP-4 pre-treatment. The DNAB-lesioned rats had lower noradrenaline efflux in the medial prefrontal cortex. DSP-4 caused no change in NAT expression in the DNAB areas. These findings suggested that noradrenaline reuptake may not be exclusively responsible for the atomoxetine effects in adjusting impulsivity. The role of DNAB should also be considered, particularly in conditions requiring greater behavioral inhibition.
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Affiliation(s)
- Yia-Ping Liu
- Department of Physiology and Biophysics, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Psychiatry, Tri-Service General Hospital, Taipei, Taiwan, ROC.
| | - Teng-Shun Huang
- Department of Physiology and Biophysics, National Defense Medical Center, Taipei, Taiwan, ROC
| | - Che-Se Tung
- Division of Medical Research & Education, Cheng Hsin General Hospital, Taipei, Taiwan, ROC
| | - Chen-Cheng Lin
- Department of Physiology and Biophysics, National Defense Medical Center, Taipei, Taiwan, ROC
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Long-term modulation of learning following locus coeruleus stimulation: Behavioral and neurochemical data. ACTA ACUST UNITED AC 2013. [DOI: 10.3758/bf03326516] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Functional hypotheses of the coeruleocortical noradrenergic projection: A review of recent experimentation and theory. ACTA ACUST UNITED AC 2013. [DOI: 10.3758/bf03326514] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Park J, Bucher ES, Fontillas K, Owesson-White C, Ariansen JL, Carelli RM, Wightman RM. Opposing catecholamine changes in the bed nucleus of the stria terminalis during intracranial self-stimulation and its extinction. Biol Psychiatry 2013; 74:69-76. [PMID: 23260335 PMCID: PMC3609919 DOI: 10.1016/j.biopsych.2012.11.008] [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: 06/11/2012] [Revised: 10/24/2012] [Accepted: 11/12/2012] [Indexed: 01/23/2023]
Abstract
BACKGROUND While studies suggest that both dopamine and norepinephrine neurotransmission support reinforcement learning, the role of dopamine has been emphasized. As a result, little is known about norepinephrine signaling during reward learning and extinction. Both dopamine and norepinephrine projections innervate distinct regions of the bed nucleus of the stria terminalis (BNST), a structure that mediates behavioral and autonomic responses to stress and anxiety. We investigated whether norepinephrine release in the ventral BNST (vBNST) and dopamine release in the dorsolateral BNST (dlBNT) correlate with reward learning during intracranial self-stimulation (ICSS). METHODS Using fast-scan cyclic voltammetry, norepinephrine concentration changes in the vBNST (n = 12 animals) during ICSS were compared with dopamine changes in the dlBNST (n = 7 animals) and nucleus accumbens (NAc) (n = 5 animals). Electrical stimulation was in the ventral tegmental area/substantia nigra region. RESULTS Whereas dopamine release was evoked by presentation of a cue predicting reward availability in both dlBNST and NAc, cue-evoked norepinephrine release did not occur in the vBNST. Release of both catecholamines was evoked by the electrical stimulation. Extracellular changes in norepinephrine were also studied during extinction of ICSS and compared with results obtained for dopamine. During extinction of ICSS, norepinephrine release in the vBNST occurred at the time where the stimulation was anticipated, whereas dopamine release transiently decreased. CONCLUSIONS The data demonstrate that norepinephrine release in the vBNST differs from dopamine release in the dlBNST and the NAc in that it signals the absence of reward rather than responding to reward predictive cues.
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Affiliation(s)
- Jinwoo Park
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
| | - Elizabeth S. Bucher
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
| | - Khristy Fontillas
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
| | - Catarina Owesson-White
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
| | - Jennifer L. Ariansen
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
| | - Regina M. Carelli
- Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
,Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
| | - R. Mark Wightman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
,Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
,Corresponding author: R. Mark Wightman, Ph.D., Department of Chemistry, CB # 3290, Venable Hall, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-3290, USA, Tel : +1 (919) 962-1472, Fax : +1 (919) 962-2388,
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A cognitive/information-processing approach to the relationship between stress and depression. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00010712] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
AbstractAversive experiences have been thought to provoke or exacerbate clinical depression. The present review provides a brief survey of the stress-depression literature and suggests that the effects of stressful experiences on affective state may be related to depletion of several neurotransmitters, including norepinephrine, dopamine, and serotonin. A major element in determining the neurochemical changes is the organism's ability to cope with the aversive stimuli through behavioral means. Aversive experiences give rise to behavioral attempts to cope with the stressor, coupled with increased utilization and synthesis of brain amines to contend with environmental demands. When behavioral coping is possible, neurochemical systems are not overly taxed, and behavioral pathology will not ensue. However, when there can be no behavioral control over the stressful stimuli, or when the aversive experience is perceived as uncontrollable, increased emphasis is placed on coping through endogenous neurochemical mechanisms. Amine utilization increases appreciably and may exceed synthesis, resulting in a net reduction of amine stores, which in turn promotes or exacerbates affective disorder. The processes governing the depletions may be subject to sensitization or conditioning, such that exposure to traumatic experiences may have long-term repercussions when the organism subsequently encounters related stressful stimuli. With continued uncontrollable stimulation, adaptation occurs in the form of increased activity of synthetic enzymes, and levels of amines approach basal values. It is suggested that either the initial amine depletion provoked by aversive experiences or a dysfunction of the adaptive processes, resulting in persistent amine depletion, contributes to behavioral depression. Aside from the contribution of behavioral coping, several organismic, experiential, and environmental variables will influence the effects of aversive experiences on neurochemical activity, and may thus influence vulnerability to depression.
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Abstract
AbstractA comparative method of studying the biological bases of personality compares human trait dimensions with likely animal models in terms of genetic determination and common biological correlates. The approach is applied to the trait of sensation seeking, which is defined on the human level by a questionnaire, reports of experience, and observations of behavior, and on the animal level by general activity, behavior in novel situations, and certain types of naturalistic behavior in animal colonies. Moderately high genetic determination has been found for human sensation seeking, and marked strain differences in rodents have been found in open-field behavior that may be related to basic differences in brain neurochemistry. Agonistic and sociable behaviors in both animals and humans and the trait measure of sensation seeking in humans have been related to certain common biological correlates such as gonadal hormones, monoamine oxidase (MAO), and augmenting of the cortical evoked potential.The monoamine systems in the rodent brain are involved in general activity, exploratory behavior, emotionality, socialization, dominance, sexual and consummately behaviors, and intracranial self-stimulation. Preliminary studies have related norepinephrine and enzymes involved in its production and degradation to human sensation seeking. A model is suggested that relates mood, behavioral activity, sociability, and clinical states to activity of the central catecholamine neurotransmitters and to neuroregulators and other transmitters that act in opposite ways on behavior or stabilize activity in the arousal systems. Stimulation and behavioral activity act on the catecholamine systems in a brain–behavior feedback loop. At optimal levels of catecholamine systems activity (CSA) mood is positive and activity and sociability are adaptive. At very low or very high levels of CSA mood is dysphoric, activity is restricted or stereotyped, and the organism is unsocial or aggressively antisocial. Novelty, in the absence of threat, may be rewarding through activation of noradrenergic neurons.
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Précis ofThe neuropsychology of anxiety: An enquiry into the functions of the septo-hippocampal system. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00013066] [Citation(s) in RCA: 722] [Impact Index Per Article: 51.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractA model of the neuropsychology of anxiety is proposed. The model is based in the first instance upon an analysis of the behavioural effects of the antianxiety drugs (benzodiazepines, barbiturates, and alcohol) in animals. From such psychopharmacologi-cal experiments the concept of a “behavioural inhibition system” (BIS) has been developed. This system responds to novel stimuli or to those associated with punishment or nonreward by inhibiting ongoing behaviour and increasing arousal and attention to the environment. It is activity in the BIS that constitutes anxiety and that is reduced by antianxiety drugs. The effects of the antianxiety drugs in the brain also suggest hypotheses concerning the neural substrate of anxiety. Although the benzodiazepines and barbiturates facilitate the effects of γ-aminobutyrate, this is insufficient to explain their highly specific behavioural effects. Because of similarities between the behavioural effects of certain lesions and those of the antianxiety drugs, it is proposed that these drugs reduce anxiety by impairing the functioning of a widespread neural system including the septo-hippocampal system (SHS), the Papez circuit, the prefrontal cortex, and ascending monoaminergic and cholinergic pathways which innervate these forebrain structures. Analysis of the functions of this system (based on anatomical, physiological, and behavioural data) suggests that it acts as a comparator: it compares predicted to actual sensory events and activates the outputs of the BIS when there is a mismatch or when the predicted event is aversive. Suggestions are made as to the functions of particular pathways within this overall brain system. The resulting theory is applied to the symptoms and treatment of anxiety in man, its relations to depression, and the personality of individuals who are susceptible to anxiety or depression.
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Stress, neurochemical substrates, and depression: Concomitants are not necessarily causes. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00010669] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Gray'sNeuropsychology of anxiety: An enquiry into the functions of septohippocampal theories. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00013170] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Anxiety viewed from the upper brain stem: Though panic and fear yield trepidation, should both be called anxiety? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00013200] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Yamano E, Isowa T, Nakano Y, Matsuda F, Hashimoto-Tamaoki T, Ohira H, Kosugi S. Association study between reward dependence temperament and a polymorphism in the phenylethanolamine N-methyltransferase gene in a Japanese female population. Compr Psychiatry 2008; 49:503-7. [PMID: 18702937 DOI: 10.1016/j.comppsych.2008.03.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 03/01/2008] [Accepted: 03/07/2008] [Indexed: 11/30/2022] Open
Abstract
Cloninger's theory is that specific dimensions of temperament are associated with single neurotransmitter systems, and it is based on neurophysiologic and genetic approaches to the human traits. It suggests that overexpression of temperament could cause psychiatric illness. Based on this theory, we examined the correlation between reward dependence (RD) trait, measured with the Temperament and Character Inventory, and 5 polymorphisms in genes of norepinephrine pathways, ADRB1, COMT, PNMT, SLC18A1, and SLC6A2, in 85 Japanese female nursing students. We found that rs3764351 in PNMT was significantly associated with RD on Fisher's exact test (P = .029, P(corr) = .236). When haplotype analysis was performed for rs3764351 and rs876493 polymorphisms in the 5' flanking region of PNMT, 3 haplotypes were identified. Rs3764351 itself appeared to be correlated with RD in the present study of a specific population, although we could not demonstrate an association between RD and any of the haplotypes. Our findings have implications for the understanding of temperament using neurophysiologic approaches.
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Affiliation(s)
- Emi Yamano
- Department of Genome Epidemiology, Kyoto University Graduate School of Public Health, Kyoto 606-8501, Japan
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Bruno KJ, Freet CS, Twining RC, Egami K, Grigson PS, Hess EJ. Abnormal latent inhibition and impulsivity in coloboma mice, a model of ADHD. Neurobiol Dis 2006; 25:206-16. [PMID: 17064920 PMCID: PMC1761697 DOI: 10.1016/j.nbd.2006.09.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Revised: 09/13/2006] [Accepted: 09/16/2006] [Indexed: 10/24/2022] Open
Abstract
Attention deficit hyperactivity disorder (ADHD) is characterized by hyperactivity, inattention, and impulsivity. The coloboma mouse model of ADHD exhibits profound hyperactivity. To determine whether coloboma mice exhibit other signs of ADHD, we assessed latent inhibition as a test of attention, and impulsivity in a delayed reinforcement paradigm. Latent inhibition was present in control mice but was disrupted in coloboma mice. Coloboma mice also exhibited impaired performance on the delayed reinforcement task and were not able to wait as long as control mice to obtain the greater reinforcer. Because norepinephrine mediates hyperactivity in coloboma mice, we examined the role of norepinephrine in disrupted latent inhibition and impulsivity. Reduction of norepinephrine with DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride) restored latent inhibition but did not ameliorate impulsivity. In summary, coloboma mice exhibit hyperactivity, inattention as determined by latent inhibition, and impulsivity, and norepinephrine mediates hyperactivity and inattention but not impulsivity in these mice.
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Affiliation(s)
| | - Christopher S. Freet
- Department of Neural and Behavioral Sciences Pennsylvania State University School of Medicine Hershey, PA 17033
| | - Robert C. Twining
- Department of Neural and Behavioral Sciences Pennsylvania State University School of Medicine Hershey, PA 17033
| | | | - Patricia S. Grigson
- Department of Neural and Behavioral Sciences Pennsylvania State University School of Medicine Hershey, PA 17033
| | - Ellen J. Hess
- Departments of Neurology and
- Neuroscience Johns Hopkins University School of Medicine Baltimore, MD 21287
- Corresponding author: Ellen J. Hess, Ph.D., Department of Neurology, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Meyer Building, Room 6-181, Baltimore, MD 21287 Telephone: 410-502-7511 FAX: 410-502-6737
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Siesser WB, Zhao J, Miller LR, Cheng SY, McDonald MP. Transgenic mice expressing a human mutant beta1 thyroid receptor are hyperactive, impulsive, and inattentive. GENES BRAIN AND BEHAVIOR 2006; 5:282-97. [PMID: 16594981 DOI: 10.1111/j.1601-183x.2005.00161.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Attention deficit hyperactivity disorder (ADHD) is the most commonly diagnosed childhood psychiatric disorder. We have found that a transgenic mouse bearing a human mutant thyroid receptor (TRbeta1) expresses all of the defining symptoms of ADHD--inattention, hyperactivity, and impulsivity--as well as a 'paradoxical' response to methylphenidate (MPH). As with ADHD, the behavioral phenotypes expressed by the TRbeta transgenic mice are dynamic and sensitive to changes in environmental conditions, stress, and reinforcement. TRbeta transgenic mice are euthyroid except for a brief period during postnatal development, but the behavioral phenotypes, elevated dopamine turnover, and paradoxical response to MPH persist into adulthood. Thus, like the vast majority of children with ADHD, the TRbeta transgenic mice exhibit the symptoms of ADHD in the complete absence of thyroid abnormalities. This suggests that even transient perturbations in developmental thyroid homeostasis can have long-lasting behavioral and cognitive consequences, including producing the full spectrum of symptoms of ADHD.
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Affiliation(s)
- W B Siesser
- Program in Neuroscience, Vanderbilt University, Nashville, TN 37232-0325, USA
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Abstract
Substantial evidence suggests that alterations in noradrenergic function contribute to the cognitive impairments of schizophrenia. Activation of post-junctional alpha 2a-adrenergic receptors in the prefrontal cortex by the alpha 2a-selective agonist guanfacine has demonstrated some preliminary benefit in subjects with schizophrenia treated with atypical antipsychotics. alpha 1-adrenergic receptor activity may be less important in mediating the cognitive impairments of schizophrenia. beta-adrenergic receptors may serve as another potential target for cognitive remediation in schizophrenia. However, the potential increase in memory consolidation in schizophrenia patients produced by beta-adrenergic agonists may be outweighed by the impairment in cognitive flexibility and executive functioning produced by beta-adrenergic agonists. Finally, norepinephrine reuptake inhibitors, such as atomoxetine, hold promise as potential cognitive enhancers in schizophrenia because of their ability to indirectly but selectively increase extracellular dopamine concentrations in the prefrontal cortex.
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Affiliation(s)
- Joseph I Friedman
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY, USA.
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Friedman JI, Adler DN, Davis KL. The role of norepinephrine in the pathophysiology of cognitive disorders: potential applications to the treatment of cognitive dysfunction in schizophrenia and Alzheimer's disease. Biol Psychiatry 1999; 46:1243-52. [PMID: 10560029 DOI: 10.1016/s0006-3223(99)00232-2] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The role of noradrenergic neurotransmission in normal cognitive functions has been extensively investigated, however, the involvement of noradrenergic functions in the cognitive impairment associated with schizophrenia and Alzheimer's disease has not been as intensively considered. The limited ability of atypical antipsychotics to treat the cognitive impairment of schizophrenia, and cholinomimetics to treat the cognitive impairment of Alzheimer's disease, may be related to the influence of a multiplicity of neurotransmitter abnormalities including noradrenergic dysfunction, which these treatments do not address. The evidence of noradrenergic dysfunction occurring concomitantly with dopamine dysfunction in schizophrenia and acetylcholine dysfunction in Alzheimer's disease supports therapeutic approaches using noradrenergic drugs in combination with neuroleptics and cholinesterase inhibitors, respectively, to enhance the treatment of cognitive impairment. Given the results of animal and human studies, it appears that alpha-2A agonists may be the optimal choice for this purpose.
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Affiliation(s)
- J I Friedman
- Department of Psychiatry, Mount Sinai School of Medicine, New York, NY 10029, USA
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Highfield DA, Lilliquist MW, Amsel A. Reversal of a Postnatal Alcohol-Induced Deficit in Learned Persistence in the Rat by d-Amphetamine. Alcohol Clin Exp Res 1999. [DOI: 10.1111/j.1530-0277.1999.tb04230.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
There is recognition that the cognitive symptoms of schizophrenia have the most substantial impact on illness outcome. Domains of cognition reported to be significantly affected include serial learning, executive function, vigilance, and distractibility, to name a few. Dopamine activity at D1 receptors mediates many cognitive processes subserved by the prefrontal cortex (PFC), particularly working memory. The number of D1 receptors in the PFC is decreased in schizophrenics and is unaffected by chronic administration of typical neuroleptics. Therefore, medications that increase dopamine in the PFC, such as atypical neuroleptics, or that directly activate the D1 receptor may prove useful in the remediation of prefrontal-dependent cognitive deficits in schizophrenia. Decreased levels of cortical norepinephrine (NE) are associated with impaired learning and working memory in animal models, and can be reversed by drugs that restore NE activity. More specifically, alpha-2 adrenergic receptor agonists have been particularly effective in improving delayed response performance in young monkeys with localized 6-hydroxydopamine lesions in the PFC. Furthermore, human postmortem studies have demonstrated decreased NE in the frontal cortex of demented schizophrenic patients. Therefore, alpha-2 receptor agonists hold promise as drugs to improve cognitive performance on tasks dependent upon PFC function in schizophrenics. Finally, the finding that cortical choline acetyl transferase activity correlates with Clinical Dementia Rating scores in schizophrenic patients and that cholinomimetic drugs enhance cognition in healthy subjects suggests that cholinergic drugs may also treat cognitive symptoms in schizophrenia. Two potential types of cholinomimetics for use in schizophrenics are the acetylcholinesterase inhibitors and M1/M4 muscarinic agonists, both of which increase cortical cholinergic activity.
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Affiliation(s)
- J I Friedman
- Department of Psychiatry, Mount Sinai School of Medicine, New York, New York 10029, USA
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Dawson R, Marschall EG, Chan KC, Millard WJ, Eppler B, Patterson TA. Neurochemical and neurobehavioral effects of neonatal administration of beta-N-methylamino-L-alanine and 3,3'-iminodipropionitrile. Neurotoxicol Teratol 1998; 20:181-92. [PMID: 9536463 DOI: 10.1016/s0892-0362(97)00078-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that is characterized by a loss of motor neurons in the spinal cord, brain stem, and cortex. The present study examined the neurochemical and neurobehavioral consequences of the neonatal administration of IDPN and BMAA, two neurotoxins previously considered as experimental models of ALS. Sprague-Dawley rat pups (male and female) were injected SC with IDPN or BMAA. The following treatment groups (n = 5-14 per group) were studied; IDPN [100 mg/kg on postnatal days (PNDs) 2, 4, and 6], BMAA-A (500 mg/kg PND 5 only), BMAA-B (500 mg/kg PND 2 and 5), and BMAA-C (100 mg/kg PND 2 and 5). Neurobehavioral testing was performed and the rats were sacrificed at 101 days of age. Monoamine and amino acid content was measured by HPLC in brain regions and the spinal cord. IDPN treatment impaired the righting reflex and decreased forepaw suspension times. BMAA-A and BMAA-B males exhibited an increase in open field behavior. The hindlimb splay of BMAA-A females was increased. Other significant behavioral and endocrine effects were also seen with neonatal IDPN or BMAA treatment. IDPN females had increased spinal cord content of norepinephrine (NE), serotonin, and 5-hydroxyindoleacetic acid (5-HIAA). IDPN males had no alterations in spinal cord content of NE or Glu, but serotonin and 5-HIAA content were increased. BMAA-A and BMAA-B males also had elevated spinal cord 5-HIAA content whereas females were unaffected. Glu and Asp content in the spinal cord was elevated in the female BMAA-C group. Monoamines were also altered in the cerebellum, mediobasal hypothalamus, and hippocampus by IDPN and BMAA treatment. alpha 2-Adrenergic binding sites were increased in the spinal cord by IDPN and in the cerebellum by BMAA treatment. The results of this study clearly demonstrated that both IDPN and BMAA given neonatally can produce changes in motor function and spinal cord neurochemistry, although the pattern of the effects is both treatment and sex dependent. Neonatal exposure to either IDPN or BMAA resulted in permanent changes in adult neurochemistry that may be related to reorganizational effects induced by toxin-mediated neuroplasticity in developing neurons.
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Affiliation(s)
- R Dawson
- Department of Pharmacodynamics, College of Pharmacy, JHMHC, University of Florida, Gainesville 32610, USA.
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Pennartz CM. The ascending neuromodulatory systems in learning by reinforcement: comparing computational conjectures with experimental findings. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 1995; 21:219-45. [PMID: 8806015 DOI: 10.1016/0165-0173(95)00014-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A central problem in cognitive neuroscience is how animals can manage to rapidly master complex sensorimotor tasks when the only sensory feedback they use to improve their performance is a simple reinforcing stimulus. Neural network theorists have constructed algorithms for reinforcement learning that can be used to solve a variety of biological problems and do not violate basic neurophysiological principles, in contrast to the back-propagation algorithm. A key assumption in these models is the existence of a reinforcement signal, which would be diffusively broadcast throughout one or several brain areas engaged in learning. This signal is further assumed to mediate up- and downward changes in synaptic efficacy by acting as a multiplicative factor in learning rules. The biological plausibility of these algorithms has been defended by the conjecture that the neuromodulators noradrenaline, acetylcholine or dopamine may form the neurochemical substrate of reinforcement signals. In this commentary, the predictions raised by this hypothesis are compared to anatomical, electrophysiological and behavioural findings. The experimental evidence does not support, and often argues against, a general reinforcement-encoding function of these neuromodulatory systems. Nevertheless, the broader concept of evaluative signalling between brain structures implied in learning appears to be reasonable and the available algorithms may open new avenues for constructing more realistic network architectures.
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Affiliation(s)
- C M Pennartz
- California Institute of Technology, Pasadena 91125, USA. pennartz%
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Abstract
Electrophysiological and neurosurgical lesion studies with experimental animals have implicated the ascending dorsal noradrenergic bundle of the locus coeruleus system in cognitive process such as memory, learning and selective attention. However, it has also been suggested that noradrenaline (norepinephrine) is crucial in certain cognitive functions associated with the frontal lobes, particularly the prevention of distractibility by irrelevant stimuli. The alpha 2-receptors of the prefrontal cortex appear to be of particular importance in this respect. Studies with humans and experimental primates provide substantial support for this view. The aged primate brain is prone to degeneration of the locus coeruleus, as well as profound catecholamine depletion in the prefrontal cortex, and so is ideal for psychopharmacological investigation of the role of noradrenaline in frontal lobe function. Elderly monkeys show deficits in performance of the delayed response task, which can be reversed directly by both the mixed alpha 1/alpha 2-agonist clonidine, the more specific alpha 2-agonist guanfacine and also, indirectly, by the alpha 2-antagonist yohimbine. It is suggested that these results can be explained by an attenuation of the distracting properties of irrelevant stimuli following stimulation of noradrenergic activity. Conversely, distractibility is magnified whenever noradrenergic activity is reduced. This is supported by similar findings in psychopharmacological studies of healthy humans. The exception to this is when the locus coeruleus is likely to be firing, e.g. in times of stress or when novel stimuli are encountered. Clonidine attenuates locus coeruleus firing on such occasions, and so counteracts any beneficial (or deleterious) effects of stress on task performance. alpha 2-Adrenoceptor agents have little therapeutic value in patients with dementia of the Alzheimer's type. However, they may have some clinical use in patients who have a cognitive symptomatology similar to that of patients who have received neurosurgical excisions to the frontal lobes, e.g. deficits in working memory, executive function or focused attention, with relative sparing of episodic short term memory. Patients with Korsakoff's disease, attention deficit disorder or schizophrenia may benefit from treatment with alpha 2-agents. In particular, idazoxan has putative therapeutic effects in patients with a neurodegenerative disorder, namely dementia of frontal type.
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Affiliation(s)
- J T Coull
- Department of Experimental Psychology, University of Cambridge, England
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