1
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Mayer FP, Stewart A, Varman DR, Moritz AE, Foster JD, Owens AW, Areal LB, Gowrishankar R, Velez M, Wickham K, Phelps H, Katamish R, Rabil M, Jayanthi LD, Vaughan RA, Daws LC, Blakely RD, Ramamoorthy S. Kappa Opioid Receptor Antagonism Restores Phosphorylation, Trafficking and Behavior induced by a Disease Associated Dopamine Transporter Variant. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.03.539310. [PMID: 37205452 PMCID: PMC10187322 DOI: 10.1101/2023.05.03.539310] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Aberrant dopamine (DA) signaling is implicated in schizophrenia, bipolar disorder (BPD), autism spectrum disorder (ASD), substance use disorder, and attention-deficit/hyperactivity disorder (ADHD). Treatment of these disorders remains inadequate, as exemplified by the therapeutic use of d-amphetamine and methylphenidate for the treatment of ADHD, agents with high abuse liability. In search for an improved and non-addictive therapeutic approach for the treatment of DA-linked disorders, we utilized a preclinical mouse model expressing the human DA transporter (DAT) coding variant DAT Val559, previously identified in individuals with ADHD, ASD, or BPD. DAT Val559, like several other disease-associated variants of DAT, exhibits anomalous DA efflux (ADE) that can be blocked by d-amphetamine and methylphenidate. Kappa opioid receptors (KORs) are expressed by DA neurons and modulate DA release and clearance, suggesting that targeting KORs might also provide an alternative approach to normalizing DA-signaling disrupted by perturbed DAT function. Here we demonstrate that KOR stimulation leads to enhanced surface trafficking and phosphorylation of Thr53 in wildtype DAT, effects achieved constitutively by the Val559 mutant. Moreover, these effects can be rescued by KOR antagonism of DAT Val559 in ex vivo preparations. Importantly, KOR antagonism also corrected in vivo DA release as well as sex-dependent behavioral abnormalities observed in DAT Val559 mice. Given their low abuse liability, our studies with a construct valid model of human DA associated disorders reinforce considerations of KOR antagonism as a pharmacological strategy to treat DA associated brain disorders.
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Affiliation(s)
- Felix P. Mayer
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Adele Stewart
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Durairaj Ragu Varman
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Amy E. Moritz
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - James D. Foster
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Anthony W. Owens
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, TX, USA
| | - Lorena B. Areal
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Raajaram Gowrishankar
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Michelle Velez
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Kyria Wickham
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Hannah Phelps
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Rania Katamish
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Maximilian Rabil
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Lankupalle D. Jayanthi
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Roxanne A. Vaughan
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Lynette C. Daws
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, TX, USA
- Department of Pharmacology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Randy D. Blakely
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Sammanda Ramamoorthy
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
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2
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Mayer FP, Stewart A, Blakely RD. Leaky lessons learned: Efflux prone dopamine transporter variant reveals sex and circuit specific contributions of D2 receptor signalling to neuropsychiatric disease. Basic Clin Pharmacol Toxicol 2024; 134:206-218. [PMID: 37987120 DOI: 10.1111/bcpt.13964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 11/14/2023] [Accepted: 11/17/2023] [Indexed: 11/22/2023]
Abstract
Aberrant dopamine (DA) signalling has been implicated in various neuropsychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), schizophrenia, bipolar disorder (BPD) and addiction. The availability of extracellular DA is sculpted by the exocytotic release of vesicular DA and subsequent transporter-mediated clearance, rendering the presynaptic DA transporter (DAT) a crucial regulator of DA neurotransmission. D2-type DA autoreceptors (D2ARs) regulate multiple aspects of DA homeostasis, including (i) DA synthesis, (ii) vesicular release, (iii) DA neuron firing and (iv) the surface expression of DAT and DAT-mediated DA clearance. The DAT Val559 variant, identified in boys with ADHD or ASD, as well as in a girl with BPD, supports anomalous DA efflux (ADE), which we have shown drives tonic activation of D2ARs. Through ex vivo and in vivo studies of the DAT Val559 variant using transgenic knock-in mice, we have uncovered a circuit and sex-specific capacity of D2ARs to regulate DAT, which consequently disrupts DA signalling and behaviour differently in males and females. Our studies reveal the ability of the construct-valid DAT Val559 model to elucidate endogenous mechanisms that support DA signalling, findings that may be of translational and/or therapeutic importance.
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Affiliation(s)
- Felix P Mayer
- Department of Biomedical Science, Florida Atlantic University, Jupiter, Florida, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida, USA
| | - Adele Stewart
- Department of Biomedical Science, Florida Atlantic University, Jupiter, Florida, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida, USA
| | - Randy D Blakely
- Department of Biomedical Science, Florida Atlantic University, Jupiter, Florida, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida, USA
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3
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Fang Q, Frohlich F. Dissection of neuronal circuits underlying sustained attention with the five-choice serial reaction time task. Neurosci Biobehav Rev 2023; 152:105306. [PMID: 37419229 PMCID: PMC10517644 DOI: 10.1016/j.neubiorev.2023.105306] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 07/09/2023]
Abstract
Attention deficits are common in psychiatric and neurological disorders. The transdiagnostic nature of impaired attention suggests a common set of underlying neural circuits. Yet, there are no circuit-based treatments such as non-invasive brain stimulation currently available due to the lack of sufficiently delineated network targets. Therefore, to better treat attentional deficits, a comprehensive functional dissection of neural circuits underlying attention is imperative. This can be achieved by taking advantage of preclinical animal models and well-designed behavioral assays of attention. The resulting findings in turn can be translated to the development of novel interventions with the goal of advancing them to clinical practice. Here we show that the five-choice serial reaction time task has greatly facilitated the study of the neural circuits underlying attention in a well-controlled setting. We first introduce the task and then focus on its application in preclinical studies on sustained attention, especially in the context of state-of-the-art neuronal perturbations.
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Affiliation(s)
- Qi Fang
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA
| | - Flavio Frohlich
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA; Carolina Center for Neurostimulation, University of North Carolina, Chapel Hill, NC, USA; Neuroscience Center, University of North Carolina, Chapel Hill, NC, USA; Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC, USA; Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA; Department of Neurology, University of North Carolina, Chapel Hill, NC, USA.
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4
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Male DAT Val559 Mice Exhibit Compulsive Behavior under Devalued Reward Conditions Accompanied by Cellular and Pharmacological Changes. Cells 2022; 11:cells11244059. [PMID: 36552823 PMCID: PMC9777203 DOI: 10.3390/cells11244059] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/05/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022] Open
Abstract
Identified across multiple psychiatric disorders, the dopamine (DA) transporter (DAT) Ala559Val substitution triggers non-vesicular, anomalous DA efflux (ADE), perturbing DA neurotransmission and behavior. We have shown that DAT Val559 mice display a waiting impulsivity and changes in cognitive performance associated with enhanced reward motivation. Here, utilizing a within-subject, lever-pressing paradigm designed to bias the formation of goal-directed or habitual behavior, we demonstrate that DAT Val559 mice modulate their nose poke behavior appropriately to match context, but demonstrate a perseverative checking behavior. Although DAT Val559 mice display no issues with the cognitive flexibility required to acquire and re-learn a visual pairwise discrimination task, devaluation of reward evoked habitual reward seeking in DAT Val559 mutants in operant tasks regardless of reinforcement schedule. The direct DA agonist apomorphine also elicits locomotor stereotypies in DAT Val559, but not WT mice. Our observation that dendritic spine density is increased in the dorsal medial striatum (DMS) of DAT Val559 mice speaks to an imbalance in striatal circuitry that might underlie the propensity of DAT Val559 mutants to exhibit compulsive behaviors when reward is devalued. Thus, DAT Val559 mice represent a model for dissection of how altered DA signaling perturbs circuits that normally balance habitual and goal-directed behaviors.
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5
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Stewart A, Mayer FP, Gowrishankar R, Davis GL, Areal LB, Gresch PJ, Katamish RM, Peart R, Stilley SE, Spiess K, Rabil MJ, Diljohn FA, Wiggins AE, Vaughan RA, Hahn MK, Blakely RD. Behaviorally penetrant, anomalous dopamine efflux exposes sex and circuit dependent regulation of dopamine transporters. Mol Psychiatry 2022; 27:4869-4880. [PMID: 36117213 DOI: 10.1038/s41380-022-01773-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 08/18/2022] [Accepted: 08/31/2022] [Indexed: 01/19/2023]
Abstract
Virtually all neuropsychiatric disorders display sex differences in prevalence, age of onset, and/or clinical symptomology. Although altered dopamine (DA) signaling is a feature of many of these disorders, sex-dependent mechanisms uniquely responsive to DA that drive sex-dependent behaviors remain unelucidated. Previously, we established that anomalous DA efflux (ADE) is a prominent feature of the DA transporter (DAT) variant Val559, a coding substitution identified in two male-biased disorders: attention-deficit/hyperactivity disorder and autism spectrum disorder. In vivo, Val559 ADE induces activation of nigrostriatal D2-type DA autoreceptors (D2ARs) that magnifies inappropriate, nonvesicular DA release by elevating phosphorylation and surface trafficking of ADE-prone DAT proteins. Here we demonstrate that DAT Val559 mice exhibit sex-dependent alterations in psychostimulant responses, social behavior, and cognitive performance. In a search for underlying mechanisms, we discovered that the ability of ADE to elicit D2AR regulation of DAT is both sex and circuit-dependent, with dorsal striatum D2AR/DAT coupling evident only in males, whereas D2AR/DAT coupling in the ventral striatum is exclusive to females. Moreover, systemic administration of the D2R antagonist sulpiride, which precludes ADE-driven DAT trafficking, can normalize DAT Val559 behavioral changes unique to each sex and without effects on the opposite sex or wildtype mice. Our studies support the sex- and circuit dependent capacity of D2ARs to regulate DAT as a critical determinant of the sex-biased effects of perturbed DA signaling in neurobehavioral disorders. Moreover, our work provides a cogent example of how a shared biological insult drives alternative physiological and behavioral trajectories as opposed to resilience.
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Affiliation(s)
- Adele Stewart
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, USA.,Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Felix P Mayer
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, USA
| | | | - Gwynne L Davis
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, USA
| | - Lorena B Areal
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, USA
| | - Paul J Gresch
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, USA.,Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Rania M Katamish
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, USA
| | - Rodeania Peart
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL, USA
| | - Samantha E Stilley
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, USA
| | - Keeley Spiess
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, USA
| | - Maximilian J Rabil
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, USA
| | | | - Angelica E Wiggins
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, USA
| | - Roxanne A Vaughan
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Maureen K Hahn
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, USA.,Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Randy D Blakely
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, USA. .,Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL, USA.
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6
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Regan SL, Williams MT, Vorhees CV. Review of rodent models of attention deficit hyperactivity disorder. Neurosci Biobehav Rev 2022; 132:621-637. [PMID: 34848247 PMCID: PMC8816876 DOI: 10.1016/j.neubiorev.2021.11.041] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 01/03/2023]
Abstract
Attention deficit hyperactivity disorder (ADHD) is a polygenic neurodevelopmental disorder that affects 8-12 % of children and >4 % of adults. Environmental factors are believed to interact with genetic predispositions to increase susceptibility to ADHD. No existing rodent model captures all aspects of ADHD, but several show promise. The main genetic models are the spontaneous hypertensive rat, dopamine transporter knock-out (KO) mice, dopamine receptor subtype KO mice, Snap-25 KO mice, guanylyl cyclase-c KO mice, and latrophilin-3 KO mice and rats. Environmental factors thought to contribute to ADHD include ethanol, nicotine, PCBs, lead (Pb), ionizing irradiation, 6-hydroxydopamine, neonatal hypoxia, some pesticides, and organic pollutants. Model validation criteria are outlined, and current genetic models evaluated against these criteria. Future research should explore induced multiple gene KOs given that ADHD is polygenic and epigenetic contributions. Furthermore, genetic models should be combined with environmental agents to test for interactions.
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Affiliation(s)
- Samantha L. Regan
- Neuroscience Graduate Program, University of Cincinnati, Cincinnati, OH 45229
| | - Michael T. Williams
- Department of Pediatrics, University of Cincinnati College of Medicine, and Division of Neurology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229
| | - Charles V. Vorhees
- Department of Pediatrics, University of Cincinnati College of Medicine, and Division of Neurology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229,Corresponding author: Charles V. Vorhees, Ph.D., Div. of Neurology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229, USA:
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7
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Ragu Varman D, Subler MA, Windle JJ, Jayanthi LD, Ramamoorthy S. Novelty-induced hyperactivity and suppressed cocaine induced locomotor activation in mice lacking threonine 53 phosphorylation of dopamine transporter. Behav Brain Res 2021; 408:113267. [PMID: 33794225 DOI: 10.1016/j.bbr.2021.113267] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 03/03/2021] [Accepted: 03/24/2021] [Indexed: 12/26/2022]
Abstract
Dopamine (DA) transporter (DAT) is dynamically regulated by several protein kinases and the Thr53 phosphorylation of DAT (pT53-DAT) is documented in heterologous cell models and in rat brain. However, the role of endogenous pT53-DAT in living animals has never been addressed. Here we generated and studied the pT53-lacking DAT mouse model (DAT-Ala53) by CRISPR/Cas9 technology. DAT-Ala53 mice showed normal growth, body weight, body temperature, grip strength, and sucrose preference while pT53-DAT was completely absent. However, DAT-Ala53 mice showed hyperlocomotion, pronounced vertical exploratory behavior, and stereotypy in a novel environment compared to wild-type littermates (WT). DAT-Ala53 mice displayed unaltered levels of monoamines, glutamate, and GABA in the striatum compared to WT. There were also no significant differences between DAT-Ala53 mice and WT in tyrosine hydroxylase (TH) and phospho-TH levels, or in total and surface DAT levels, or in DA-transport kinetic parameters Vmax and Km. Immunohistochemical and colocalization analyses of TH and DAT in caudate-putamen and nucleus accumbens revealed no significant differences between DAT-Ala53 and WT mice. Interestingly, cocaine's potency to inhibit striatal DA transport and cocaine-induced locomotor activation were significantly reduced in the DAT-Ala53 mice. Also, ERK1/2 inhibitors completely failed to inhibit striatal DA uptake in DAT-Ala53 mice. Collectively, our findings reveal that the mice lacking pT53-DAT display novelty-induced hyperactive phenotype despite having normal transporter protein expression, DA-transport kinetics and DA-linked markers. The results also reveal that the lack of endogenous pT53-DAT renders DAT resistant to ERK1/2 inhibition and also less susceptible to cocaine inhibition and cocaine-evoked locomotor stimulation.
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Affiliation(s)
- Durairaj Ragu Varman
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Mark A Subler
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Jolene J Windle
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Lankupalle D Jayanthi
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Sammanda Ramamoorthy
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, 23298, USA.
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8
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Delva NC, Stanwood GD. Dysregulation of brain dopamine systems in major depressive disorder. Exp Biol Med (Maywood) 2021; 246:1084-1093. [PMID: 33593109 DOI: 10.1177/1535370221991830] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Major depressive disorder (MDD or depression) is a debilitating neuropsychiatric syndrome with genetic, epigenetic, and environmental contributions. Depression is one of the largest contributors to chronic disease burden; it affects more than one in six individuals in the United States. A wide array of cellular and molecular modifications distributed across a variety of neuronal processes and circuits underlie the pathophysiology of depression-no established mechanism can explain all aspects of the disease. MDD suffers from a vast treatment gap worldwide, and large numbers of individuals who require treatment do not receive adequate care. This mini-review focuses on dysregulation of brain dopamine (DA) systems in the pathophysiology of MDD and describing new cellular targets for potential medication development focused on DA-modulated micro-circuits. We also explore how neurodevelopmental factors may modify risk for later emergence of MDD, possibly through dopaminergic substrates in the brain.
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Affiliation(s)
- Nella C Delva
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306, USA
| | - Gregg D Stanwood
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306, USA.,Center for Brain Repair, Florida State University College of Medicine, Tallahassee, FL 32306, USA
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9
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Baumann P, Schriever SC, Kullmann S, Zimprich A, Peter A, Gailus-Durner V, Fuchs H, Hrabe de Angelis M, Wurst W, Tschöp MH, Heni M, Hölter SM, Pfluger PT. Diabetes type 2 risk gene Dusp8 is associated with altered sucrose reward behavior in mice and humans. Brain Behav 2021; 11:e01928. [PMID: 33131190 PMCID: PMC7821601 DOI: 10.1002/brb3.1928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/28/2020] [Accepted: 10/18/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Dusp8 is the first GWAS-identified gene that is predominantly expressed in the brain and has previously been linked with the development of diabetes type 2 in humans. In this study, we unravel how Dusp8 is involved in the regulation of sucrose reward behavior. METHODS Female, chow-fed global Dusp8 WT and KO mice were tested in an observer-independent IntelliCage setup for self-administrative sucrose consumption and preference followed by a progressive ratio task with restricted sucrose access to monitor seeking and motivation behavior. Sixty-three human carriers of the major C and minor T allele of DUSP8 SNP rs2334499 were tested for their perception of food cues by collecting a rating score for sweet versus savory high caloric food. RESULTS Dusp8 KO mice showed a comparable preference for sucrose, but consumed more sucrose compared to WT mice. In a progressive ratio task, Dusp8 KO females switched to a "trial and error" strategy to find sucrose while control Dusp8 WT mice kept their previously established seeking pattern. Nonetheless, the overall motivation to consume sucrose, and the levels of dopaminergic neurons in the brain areas NAcc and VTA were comparable between genotypes. Diabetes-risk allele carriers of DUSP8 SNP rs2334499 preferred sweet high caloric food compared to the major allele carriers, rating scores for savory food remained comparable between groups. CONCLUSION Our data suggest a novel role for Dusp8 in the perception of sweet high caloric food as well as in the control of sucrose consumption and foraging in mice and humans.
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Affiliation(s)
- Peter Baumann
- Research Unit Neurobiology of Diabetes, Helmholtz Zentrum München, Neuherberg, Germany.,Institute for Diabetes and Obesity, Helmholtz Zentrum München, Neuherberg, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany.,Neurobiology of Diabetes, TUM School of Medicine, Technical University of Munich, Munich, Germany
| | - Sonja C Schriever
- Research Unit Neurobiology of Diabetes, Helmholtz Zentrum München, Neuherberg, Germany.,Institute for Diabetes and Obesity, Helmholtz Zentrum München, Neuherberg, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Stephanie Kullmann
- German Center for Diabetes Research (DZD), Neuherberg, Germany.,Institute for Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany.,Department of Internal Medicine IV, University Hospital of Tübingen, Tübingen, Germany
| | - Annemarie Zimprich
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Neuherberg, Germany.,Institute of Developmental Genetics, Helmholtz Zentrum München, Neuherberg, Germany.,Chair of Developmental Genetics, c/o Helmholtz Zentrum München, Technische Universität München-Weihenstephan, Neuherberg, Germany
| | - Andreas Peter
- German Center for Diabetes Research (DZD), Neuherberg, Germany.,Institute for Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany.,Institute for Clinical Chemistry and Pathobiochemistry, Department for Diagnostic Laboratory Medicine, University Hospital of Tübingen, Tübingen, Germany
| | - Valerie Gailus-Durner
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Martin Hrabe de Angelis
- German Center for Diabetes Research (DZD), Neuherberg, Germany.,German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Neuherberg, Germany.,Chair of Experimental Genetics, School of Life Science Weihenstephan, Technische Universität München, Freising, Germany
| | - Wolfgang Wurst
- Institute of Developmental Genetics, Helmholtz Zentrum München, Neuherberg, Germany.,Chair of Developmental Genetics, c/o Helmholtz Zentrum München, Technische Universität München-Weihenstephan, Neuherberg, Germany.,German Center for Neurodegenerative Diseases (DZNE) Site Munich, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Ludwig-Maximilians-Universität München, Munich, Germany
| | - Matthias H Tschöp
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, Neuherberg, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany.,Division of Metabolic Diseases, Technische Universität München, Munich, Germany
| | - Martin Heni
- German Center for Diabetes Research (DZD), Neuherberg, Germany.,Institute for Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany.,Department of Internal Medicine IV, University Hospital of Tübingen, Tübingen, Germany.,Institute for Clinical Chemistry and Pathobiochemistry, Department for Diagnostic Laboratory Medicine, University Hospital of Tübingen, Tübingen, Germany
| | - Sabine M Hölter
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Neuherberg, Germany.,Institute of Developmental Genetics, Helmholtz Zentrum München, Neuherberg, Germany.,Chair of Developmental Genetics, c/o Helmholtz Zentrum München, Technische Universität München-Weihenstephan, Neuherberg, Germany
| | - Paul T Pfluger
- Research Unit Neurobiology of Diabetes, Helmholtz Zentrum München, Neuherberg, Germany.,Institute for Diabetes and Obesity, Helmholtz Zentrum München, Neuherberg, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany.,Neurobiology of Diabetes, TUM School of Medicine, Technical University of Munich, Munich, Germany
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10
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Bhat S, El-Kasaby A, Freissmuth M, Sucic S. Functional and Biochemical Consequences of Disease Variants in Neurotransmitter Transporters: A Special Emphasis on Folding and Trafficking Deficits. Pharmacol Ther 2020; 222:107785. [PMID: 33310157 PMCID: PMC7612411 DOI: 10.1016/j.pharmthera.2020.107785] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 12/02/2020] [Indexed: 01/30/2023]
Abstract
Neurotransmitters, such as γ-aminobutyric acid, glutamate, acetyl choline, glycine and the monoamines, facilitate the crosstalk within the central nervous system. The designated neurotransmitter transporters (NTTs) both release and take up neurotransmitters to and from the synaptic cleft. NTT dysfunction can lead to severe pathophysiological consequences, e.g. epilepsy, intellectual disability, or Parkinson’s disease. Genetic point mutations in NTTs have recently been associated with the onset of various neurological disorders. Some of these mutations trigger folding defects in the NTT proteins. Correct folding is a prerequisite for the export of NTTs from the endoplasmic reticulum (ER) and the subsequent trafficking to their pertinent site of action, typically at the plasma membrane. Recent studies have uncovered some of the key features in the molecular machinery responsible for transporter protein folding, e.g., the role of heat shock proteins in fine-tuning the ER quality control mechanisms in cells. The therapeutic significance of understanding these events is apparent from the rising number of reports, which directly link different pathological conditions to NTT misfolding. For instance, folding-deficient variants of the human transporters for dopamine or GABA lead to infantile parkinsonism/dystonia and epilepsy, respectively. From a therapeutic point of view, some folding-deficient NTTs are amenable to functional rescue by small molecules, known as chemical and pharmacological chaperones.
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Affiliation(s)
- Shreyas Bhat
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Ali El-Kasaby
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria.
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11
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Areal LB, Blakely RD. Neurobehavioral changes arising from early life dopamine signaling perturbations. Neurochem Int 2020; 137:104747. [PMID: 32325191 PMCID: PMC7261509 DOI: 10.1016/j.neuint.2020.104747] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 04/11/2020] [Accepted: 04/14/2020] [Indexed: 12/11/2022]
Abstract
Dopamine (DA) signaling is critical to the modulation of multiple brain functions including locomotion, reinforcement, attention and cognition. The literature provides strong evidence that altered DA availability and actions can impact normal neurodevelopment, with both early and enduring consequences on anatomy, physiology and behavior. An appreciation for the developmental contributions of DA signaling to brain development is needed to guide efforts to preclude and remedy neurobehavioral disorders, such as attention-deficit/hyperactivity disorder, addiction, bipolar disorder, schizophrenia and autism spectrum disorder, each of which exhibits links to DA via genetic, cellular and/or pharmacological findings. In this review, we highlight research pursued in preclinical models that use genetic and pharmacological approaches to manipulate DA signaling at sensitive developmental stages, leading to changes at molecular, circuit and/or behavioral levels. We discuss how these alterations can be aligned with traits displayed by neuropsychiatric diseases. Lastly, we review human studies that evaluate contributions of developmental perturbations of DA systems to increased risk for neuropsychiatric disorders.
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Affiliation(s)
- Lorena B Areal
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, 33458, USA
| | - Randy D Blakely
- Department of Biomedical Science, Florida Atlantic University, Jupiter, FL, 33458, USA; Brain Institute, Florida Atlantic University, Jupiter, FL, 33458, USA.
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12
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Trujillo-Pisanty I, Conover K, Solis P, Palacios D, Shizgal P. Dopamine neurons do not constitute an obligatory stage in the final common path for the evaluation and pursuit of brain stimulation reward. PLoS One 2020; 15:e0226722. [PMID: 32502210 PMCID: PMC7274413 DOI: 10.1371/journal.pone.0226722] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 05/05/2020] [Indexed: 11/19/2022] Open
Abstract
The neurobiological study of reward was launched by the discovery of intracranial self-stimulation (ICSS). Subsequent investigation of this phenomenon provided the initial link between reward-seeking behavior and dopaminergic neurotransmission. We re-evaluated this relationship by psychophysical, pharmacological, optogenetic, and computational means. In rats working for direct, optical activation of midbrain dopamine neurons, we varied the strength and opportunity cost of the stimulation and measured time allocation, the proportion of trial time devoted to reward pursuit. We found that the dependence of time allocation on the strength and cost of stimulation was similar formally to that observed when electrical stimulation of the medial forebrain bundle served as the reward. When the stimulation is strong and cheap, the rats devote almost all their time to reward pursuit; time allocation falls off as stimulation strength is decreased and/or its opportunity cost is increased. A 3D plot of time allocation versus stimulation strength and cost produces a surface resembling the corner of a plateau (the “reward mountain”). We show that dopamine-transporter blockade shifts the mountain along both the strength and cost axes in rats working for optical activation of midbrain dopamine neurons. In contrast, the same drug shifted the mountain uniquely along the opportunity-cost axis when rats worked for electrical MFB stimulation in a prior study. Dopamine neurons are an obligatory stage in the dominant model of ICSS, which positions them at a key nexus in the final common path for reward seeking. This model fails to provide a cogent account for the differential effect of dopamine transporter blockade on the reward mountain. Instead, we propose that midbrain dopamine neurons and neurons with non-dopaminergic, MFB axons constitute parallel limbs of brain-reward circuitry that ultimately converge on the final-common path for the evaluation and pursuit of rewards.
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Affiliation(s)
- Ivan Trujillo-Pisanty
- Centre for Studies in Behavioural Neurobiology, Concordia University, Montreal, Québec, Canada
| | - Kent Conover
- Centre for Studies in Behavioural Neurobiology, Concordia University, Montreal, Québec, Canada
| | - Pavel Solis
- Centre for Studies in Behavioural Neurobiology, Concordia University, Montreal, Québec, Canada
| | - Daniel Palacios
- Centre for Studies in Behavioural Neurobiology, Concordia University, Montreal, Québec, Canada
| | - Peter Shizgal
- Centre for Studies in Behavioural Neurobiology, Concordia University, Montreal, Québec, Canada
- * E-mail:
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13
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Whoolery CW, Yun S, Reynolds RP, Lucero MJ, Soler I, Tran FH, Ito N, Redfield RL, Richardson DR, Shih HY, Rivera PD, Chen BPC, Birnbaum SG, Stowe AM, Eisch AJ. Multi-domain cognitive assessment of male mice shows space radiation is not harmful to high-level cognition and actually improves pattern separation. Sci Rep 2020; 10:2737. [PMID: 32066765 PMCID: PMC7026431 DOI: 10.1038/s41598-020-59419-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/23/2020] [Indexed: 12/20/2022] Open
Abstract
Astronauts on interplanetary missions - such as to Mars - will be exposed to space radiation, a spectrum of highly-charged, fast-moving particles that includes 56Fe and 28Si. Earth-based preclinical studies show space radiation decreases rodent performance in low- and some high-level cognitive tasks. Given astronaut use of touchscreen platforms during training and space flight and given the ability of rodent touchscreen tasks to assess functional integrity of brain circuits and multiple cognitive domains in a non-aversive way, here we exposed 6-month-old C57BL/6J male mice to whole-body space radiation and subsequently assessed them on a touchscreen battery. Relative to Sham treatment, 56Fe irradiation did not overtly change performance on tasks of visual discrimination, reversal learning, rule-based, or object-spatial paired associates learning, suggesting preserved functional integrity of supporting brain circuits. Surprisingly, 56Fe irradiation improved performance on a dentate gyrus-reliant pattern separation task; irradiated mice learned faster and were more accurate than controls. Improved pattern separation performance did not appear to be touchscreen-, radiation particle-, or neurogenesis-dependent, as 56Fe and 28Si irradiation led to faster context discrimination in a non-touchscreen task and 56Fe decreased new dentate gyrus neurons relative to Sham. These data urge revisitation of the broadly-held view that space radiation is detrimental to cognition.
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Affiliation(s)
- Cody W Whoolery
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Sanghee Yun
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Department of Anesthesiology and Critical Care Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ryan P Reynolds
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Melanie J Lucero
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ivan Soler
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Fionya H Tran
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Naoki Ito
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Oriental Medicine Research Center, Kitasato University, Tokyo, Japan
| | - Rachel L Redfield
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Devon R Richardson
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Hung-Ying Shih
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Phillip D Rivera
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biology, Hope College, Holland, MI, USA
| | - Benjamin P C Chen
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Shari G Birnbaum
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ann M Stowe
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, TX, USA
- Department of Neurology, University of Kentucky, Lexington, KY, USA
| | - Amelia J Eisch
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA.
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USA.
- Department of Anesthesiology and Critical Care Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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14
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Arlicot N, Vercouillie J, Malherbe C, Bidault R, Gissot V, Maia S, Barantin L, Cottier JP, Deloye JB, Guilloteau D, Ribeiro MJ. PET imaging of Dopamine Transporter with [18F]LBT-999: initial evaluation in healthy volunteers. THE QUARTERLY JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING : OFFICIAL PUBLICATION OF THE ITALIAN ASSOCIATION OF NUCLEAR MEDICINE (AIMN) [AND] THE INTERNATIONAL ASSOCIATION OF RADIOPHARMACOLOGY (IAR), [AND] SECTION OF THE SOCIETY OF... 2019; 66:148-155. [PMID: 31496203 DOI: 10.23736/s1824-4785.19.03175-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND To evaluate in healthy human brain the distribution, uptake, and kinetics of [18F]LBT-999, a PET ligand targeting the dopamine transporter, to assess its ability to explore dopaminergic innervation, using a shorter protocol, more convenient for patients than currently with [123I]ioflupane. METHODS After intravenous injection of [18F]LBT-999, 8 healthy subjects (53-80y) underwent a dynamic PET-scan. Venous samples were concomitantly obtained for metabolites analysis. Time activity curves (TACs) were generated for several ROIs (caudate, putamen, occipital cortex, substantia nigra and cerebellum). Cerebellum was used as reference region to calculate binding potentials (BPND). RESULTS No adverse events or detectable pharmacological effects were reported. [18F]LBT-999 PET revealed a good cerebral distribution, with an intense and symmetric uptake in both putamen and caudate (BPND of 6.75±1.17 and 6.30±1.17, respectively), without other brain abnormal tracer accumulation. Regional TACs showed a plateau from the maximal uptake, 20min pi, to the end of the acquisition for both caudate and putamen, whereas uptake in substantia nigra decreased progressively. A faster clearance and lowest BPND values were observed in both cortex and cerebellum. Ratios to the cerebellum exhibit value of about 3 in substantia nigra, close to 10 for both caudate and putamen, and remained around the value of 1 in cortex. The parent fraction of [18F]LBT-999 in plasma was 80%, 60% and 45% at 15, 30 and 45 min pi, respectively. CONCLUSIONS These findings support the usefulness of [18F]LBT-999 for a quantitative clinical evaluation of presynaptic dopaminergic innervation.
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Affiliation(s)
- Nicolas Arlicot
- CHRU de Tours, Unité de Radiopharmacie, Tours, France - .,UMR 1253, iBrain, Université de Tours, Inserm, Tours, France - .,-INSERM CIC 1415, University Hospital, Tours, France -
| | - Johnny Vercouillie
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France.,-INSERM CIC 1415, University Hospital, Tours, France
| | - Cécile Malherbe
- CHRU de Tours, Unité de Radiopharmacie, Tours, France.,UMR 1253, iBrain, Université de Tours, Inserm, Tours, France
| | - Rudy Bidault
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France
| | | | - Serge Maia
- CHRU de Tours, Unité de Radiopharmacie, Tours, France.,UMR 1253, iBrain, Université de Tours, Inserm, Tours, France
| | | | - Jean-Philippe Cottier
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France.,CHRU de Tours, Service de Neuroradiologie, Tours, France
| | | | - Denis Guilloteau
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France.,-INSERM CIC 1415, University Hospital, Tours, France.,CHRU de Tours, Service de Médecine Nucléaire in vitro, Tours, France
| | - Maria-Joao Ribeiro
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France.,-INSERM CIC 1415, University Hospital, Tours, France.,CHRU de Tours, Service de Médecine Nucléaire in vivo, Tours, France
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15
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Stewart A, Davis GL, Gresch PJ, Katamish RM, Peart R, Rabil MJ, Gowrishankar R, Carroll FI, Hahn MK, Blakely RD. Serotonin transporter inhibition and 5-HT 2C receptor activation drive loss of cocaine-induced locomotor activation in DAT Val559 mice. Neuropsychopharmacology 2019; 44:994-1006. [PMID: 30578419 PMCID: PMC6462012 DOI: 10.1038/s41386-018-0301-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 11/19/2018] [Accepted: 12/15/2018] [Indexed: 11/18/2022]
Abstract
Dopamine (DA) signaling dysfunction is believed to contribute to multiple neuropsychiatric disorders including attention-deficit/hyperactivity disorder (ADHD). The rare DA transporter (DAT) coding substitution Ala559Val found in subjects with ADHD, bipolar disorder and autism, promotes anomalous DA efflux in vitro and, in DAT Val559 mice, leads to increased reactivity to imminent handling, waiting impulsivity, and enhanced motivation for reward. Here, we report that, in contrast to amphetamine and methylphenidate, which induce significant locomotor activation, cocaine administration to these mice elicits no locomotor effects, despite retention of conditioned place preference (CPP). Additionally, cocaine fails to elevate extracellular DA. Given that amphetamine and methylphenidate, unlike cocaine, lack high-affinity interactions with the serotonin (5-HT) transporter (SERT), we hypothesized that the lack of cocaine-induced hyperlocomotion in DAT Val559 mice arises from SERT blockade and augmented 5-HT signaling relative to cocaine actions on wildtype animals. Consistent with this idea, the SERT blocker fluoxetine abolished methylphenidate-induced locomotor activity in DAT Val559 mice, mimicking the effects seen with cocaine. Additionally, a cocaine analog (RTI-113) with greater selectivity for DAT over SERT retains locomotor activation in DAT Val559 mice. Furthermore, genetic elimination of high-affinity cocaine interactions at SERT in DAT Val559 mice, or specific inhibition of 5-HT2C receptors in these animals, restored cocaine-induced locomotion, but did not restore cocaine-induced elevations of extracellular DA. Our findings reveal a significant serotonergic plasticity arising in the DAT Val559 model that involves enhanced 5-HT2C signaling, acting independently of striatal DA release, capable of suppressing the activity of cocaine-sensitive motor circuits.
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Affiliation(s)
- Adele Stewart
- 0000 0004 0635 0263grid.255951.fDepartment of Biomedical Science, Florida Atlantic University, Jupiter, FL USA
| | - Gwynne L. Davis
- 0000 0004 0635 0263grid.255951.fDepartment of Biomedical Science, Florida Atlantic University, Jupiter, FL USA ,0000 0001 2264 7217grid.152326.1Neuroscience Graduate Program, Vanderbilt University, Nashville, TN USA
| | - Paul J. Gresch
- 0000 0004 0635 0263grid.255951.fDepartment of Biomedical Science, Florida Atlantic University, Jupiter, FL USA ,0000 0004 0635 0263grid.255951.fBrain Institute, Florida Atlantic University, Jupiter, FL USA
| | - Rania M. Katamish
- 0000 0004 0635 0263grid.255951.fDepartment of Biomedical Science, Florida Atlantic University, Jupiter, FL USA
| | - Rodeania Peart
- 0000 0004 0635 0263grid.255951.fWilkes Honors College, Florida Atlantic University, Jupiter, FL USA
| | - Maximilian J. Rabil
- 0000 0004 0635 0263grid.255951.fDepartment of Biomedical Science, Florida Atlantic University, Jupiter, FL USA
| | - Raajaram Gowrishankar
- 0000 0004 0635 0263grid.255951.fDepartment of Biomedical Science, Florida Atlantic University, Jupiter, FL USA ,0000 0001 2264 7217grid.152326.1Neuroscience Graduate Program, Vanderbilt University, Nashville, TN USA ,0000 0001 2264 7217grid.152326.1International Scholars Program, Vanderbilt University, Nashville, TN USA
| | - F. Ivy Carroll
- 0000000100301493grid.62562.35Research Triangle Institute, Research Triangle Park, NC USA
| | - Maureen K. Hahn
- 0000 0004 0635 0263grid.255951.fDepartment of Biomedical Science, Florida Atlantic University, Jupiter, FL USA ,0000 0004 0635 0263grid.255951.fBrain Institute, Florida Atlantic University, Jupiter, FL USA
| | - Randy D. Blakely
- 0000 0004 0635 0263grid.255951.fDepartment of Biomedical Science, Florida Atlantic University, Jupiter, FL USA ,0000 0004 0635 0263grid.255951.fBrain Institute, Florida Atlantic University, Jupiter, FL USA
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16
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Thal LB, Tomlinson ID, Quinlan MA, Kovtun O, Blakely RD, Rosenthal SJ. Single Quantum Dot Imaging Reveals PKCβ-Dependent Alterations in Membrane Diffusion and Clustering of an Attention-Deficit Hyperactivity Disorder/Autism/Bipolar Disorder-Associated Dopamine Transporter Variant. ACS Chem Neurosci 2019; 10:460-471. [PMID: 30153408 PMCID: PMC6411462 DOI: 10.1021/acschemneuro.8b00350] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The dopamine transporter (DAT) is a transmembrane protein that terminates dopamine signaling in the brain by driving rapid dopamine reuptake into presynaptic nerve terminals. Several lines of evidence indicate that DAT dysfunction is linked to neuropsychiatric disorders such as attention-deficit/hyperactivity disorder (ADHD), bipolar disorder (BPD), and autism spectrum disorder (ASD). Indeed, individuals with these disorders have been found to express the rare, functional DAT coding variant Val559, which confers anomalous dopamine efflux (ADE) in vitro and in vivo. To elucidate the impact of the DAT Val559 variant on membrane diffusion dynamics, we implemented our antagonist-conjugated quantum dot (QD) labeling approach to monitor the lateral mobility of single particle-labeled transporters in transfected HEK-293 and SK-N-MC cells. Our results demonstrate significantly higher diffusion coefficients of DAT Val559 compared to those of DAT Ala559, effects likely determined by elevated N-terminal transporter phosphorylation. We also provide pharmacological evidence that PKCβ-mediated signaling supports enhanced DAT Val559 membrane diffusion rates. Additionally, our results are complimented with diffusion rates of phosphomimicked and phosphorylation-occluded DAT variants. Furthermore, we show DAT Val559 has a lower propensity for membrane clustering, which may be caused by a mutation-derived shift out of membrane microdomains leading to faster lateral membrane diffusion rates. These findings further demonstrate a functional impact of DAT Val559 and suggest that changes in transporter localization and lateral mobility may sustain ADE and contribute to alterations in dopamine signaling underlying multiple neuropsychiatric disorders.
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17
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Navratna V, Tosh DK, Jacobson KA, Gouaux E. Thermostabilization and purification of the human dopamine transporter (hDAT) in an inhibitor and allosteric ligand bound conformation. PLoS One 2018; 13:e0200085. [PMID: 29965988 PMCID: PMC6028122 DOI: 10.1371/journal.pone.0200085] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 06/19/2018] [Indexed: 12/17/2022] Open
Abstract
The human dopamine transporter (hDAT) plays a major role in dopamine homeostasis and regulation of neurotransmission by clearing dopamine from the extracellular space using secondary active transport. Dopamine is an essential monoamine chemical messenger that regulates reward seeking behavior, motor control, hormonal release, and emotional response in humans. Psychostimulants such as cocaine primarily target the central binding site of hDAT and lock the transporter in an outward-facing conformation, thereby inhibiting dopamine reuptake. The inhibition of dopamine reuptake leads to accumulation of dopamine in the synapse causing heightened signaling. In addition, hDAT is implicated in various neurological disorders and disease-associated neurodegeneration. Despite its significance, the structural studies of hDAT have proven difficult. Instability of hDAT in detergent micelles has been a limiting factor in its successful biochemical, biophysical, and structural characterization. To overcome this hurdle, we identified ligands that stabilize hDAT in detergent micelles. We then screened ~200 single residue mutants of hDAT using a high-throughput scintillation proximity assay and identified a thermostable variant (I248Y). Here we report a robust strategy to overexpress and successfully purify a thermostable variant of hDAT in an inhibitor and allosteric ligand bound conformation.
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Affiliation(s)
- Vikas Navratna
- Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Dilip K. Tosh
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Eric Gouaux
- Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
- Howard Hughes Medical Institute, Oregon Health & Science University, Portland, Oregon, United States of America
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18
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Region-Specific Regulation of Presynaptic Dopamine Homeostasis by D 2 Autoreceptors Shapes the In Vivo Impact of the Neuropsychiatric Disease-Associated DAT Variant Val559. J Neurosci 2018; 38:5302-5312. [PMID: 29739866 DOI: 10.1523/jneurosci.0055-18.2018] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/19/2018] [Accepted: 04/14/2018] [Indexed: 12/21/2022] Open
Abstract
Disruptions of dopamine (DA) signaling contribute to a broad spectrum of neuropsychiatric disorders, including attention-deficit hyperactivity disorder (ADHD), addiction, bipolar disorder, and schizophrenia. Despite evidence that risk for these disorders derives from heritable variation in DA-linked genes, a better understanding is needed of the molecular and circuit context through which gene variation drives distinct disease traits. Previously, we identified the DA transporter (DAT) variant Val559 in subjects with ADHD and established that the mutation supports anomalous DAT-mediated DA efflux (ADE). Here, we demonstrate that region-specific contributions of D2 autoreceptors (D2AR) to presynaptic DA homeostasis dictate the consequences of Val559 expression in adolescent male mice. We show that activation of D2ARs in the WT dorsal striatum (DS), but not ventral striatum (VS), increases DAT phosphorylation and surface trafficking. In contrast, the activity of tyrosine hydroxylase (TH) is D2AR-dependent in both regions. In the DS but not VS of Val559 mice, tonic activation of D2ARs drives a positive feedback loop that promotes surface expression of efflux-prone DATs, raising extracellular DA levels and overwhelming DAT-mediated DA clearance capacity. Whereas D2ARs that regulate DAT are tonically activated in the Val559 DS, D2ARs that regulate TH become desensitized, allowing maintenance of cytosolic DA needed to sustain ADE. Together with prior findings, our results argue for distinct D2AR pools that regulate DA synthesis versus DA release and inactivation and offer a clear example of how the penetrance of gene variation can be limited to a subset of expression sites based on differences in intersecting regulatory networks.SIGNIFICANCE STATEMENT Altered dopamine (DA) signaling has been linked to multiple neuropsychiatric disorders. In an effort to understand and model disease-associated DAergic disturbances, we previously screened the DA transporter (DAT) in subjects with attention-deficit hyperactivity disorder (ADHD) and identified multiple, functionally impactful, coding variants. One of these variants, Val559, supports anomalous DA efflux (ADE) and in transgenic mice leads to changes in locomotor patterns, psychostimulant sensitivity, and impulsivity. Here, we show that the penetrance of Val559 ADE is dictated by region-specific differences in how presynaptic D2-type autoreceptors (D2ARs) constrain DA signaling, biasing phenotypic effects to dorsal striatal projections. The Val559 model illustrates how the impact of genetic variation underlying neuropsychiatric disorders can be shaped by the differential engagement of synaptic regulatory mechanisms.
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