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Baughman DJ, Watson CM, Beich JW, Herboso MNJ, Cuttie LK, Marlyne ABC. Recommendation for Long-term Management of Adult Attention-Deficit/Hyperactivity Disorder in Military Populations, Veterans, and Dependents: A Narrative Review. Mil Med 2024; 189:e1343-e1352. [PMID: 37878798 DOI: 10.1093/milmed/usad403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/11/2023] [Accepted: 09/28/2023] [Indexed: 10/27/2023] Open
Abstract
INTRODUCTION In addition to the higher burden of mental health disease in the military, there is a compounding antecedent association between behavioral health comorbidities and the treatment of attention-deficit/hyperactivity disorder (ADHD) in this population. Despite the low prevalence of new-onset ADHD in adults globally, the rate of stimulant (i.e., amphetamines) prescription is increasing. Stimulants can exacerbate mental health disease (often masquerading as ADHD symptomatology), precluding optimal treatment of the underlying etiology and imposing unnecessary dangerous side effects. This study aimed to evaluate the long-term safety and efficacy of stimulants for managing adult ADHD. METHODS A nine-member multidisciplinary team reviewed a PubMed search with the terms "adult," "ADHD," and "stimulant." Targeted PubMed and Google Scholar searches for "adult ADHD" paired with Food and Drug Administration -approved ADHD medications and Google Scholar literature using forward and reverse snowballing methods were performed for high-quality studies focusing on long-term treatment in ADHD. An evidence table and clinical algorithm were developed from the review. RESULTS Of the 1,039 results, 50 articles were fully reviewed, consisting of 21 descriptive and experimental studies, 18 observational, and 11 systematic reviews and meta-analyses. Illustrative cases within the structured discussion of the results highlighted ADHD and psychiatric comorbidities, risks, harms, and benefits of stimulant use, medication mechanisms of action, and limitations of the current evidence. DISCUSSION The dearth of high-quality studies on long-term ADHD management in adults fails to establish a causal relationship between stimulant use and physiological harm. Despite mixed evidence supporting the benefit of stimulants, there is clear evidence regarding the risk of harm. The serious risks of stimulants include arrhythmias, myocardial infarction, stroke/transient ischemic attack, sudden death, psychosis, and worsening of behavioral health disease. Additionally, there is a possible long-term risk of harm due to chronic sympathetic load (i.e., cardiovascular system remodeling). Stimulants pose a greater risk for addiction and abuse compared to other evidence-based nonstimulant medications that have similar effectiveness. Both stimulants and nonstimulants might promote favorable neuroanatomical changes for long-term improvement of ADHD symptoms, but nonstimulants (atomoxetine) have the pharmacological advantage of also mitigating the effects of sympathetic load (sympatholysis) and anxiety (anxiolysis). Given the physiological uncertainty of extended stimulant use for adults, especially older adults with vulnerable cardiovascular systems, clinicians should proceed cautiously when considering initiating or sustaining stimulant therapy. For long-term treatment of ADHD in adults, clinicians should consider nonstimulant alternatives (including behavioral therapy) due to the comparatively lower side effect risk and the possible additional benefit in patients with behavioral health comorbidities. CONCLUSION Long-term safety of stimulant use for adults with ADHD is uncertain, as existing studies are limited in quality and duration. This is particularly important for military populations with higher rates of mental health conditions. Managing ADHD and related conditions requires prioritizing cardiovascular safety, especially for older adults. Nonstimulant options can be helpful, especially in comorbid psychiatric disease. Before treating ADHD, ruling out and controlling other behavioral health conditions is essential to avoid masking or worsening underlying issues and reducing unnecessary medication side effects.
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Affiliation(s)
- Derek J Baughman
- Medical Director-Primary Care, Barksdale AFB, 2nd Medical Group, Barksdale AFB, LA 71110, USA
| | - Crista M Watson
- Physician Assistant-Family Health, Barksdale AFB, 2nd Medical Group, Barksdale AFB, LA 71110, USA
| | - Jonathan W Beich
- Psychiatrist/MH Element Chief-Behavioral Health, Barksdale AFB, 2nd Medical Group, Barksdale AFB, LA 71110, USA
| | - May N Joresa Herboso
- Aerospace Medical Technician-Primary Care, Barksdale AFB, 2nd Medical Group, Barksdale AFB, LA 71110, USA
| | - Liana K Cuttie
- Nurse Practitioner, Family Health-Primary Care, Barksdale AFB, 2nd Medical Group, Barksdale AFB, LA 71110, USA
| | - Ari-Beth C Marlyne
- Chief of Medical Staff & Family Medicine Physician, Barksdale AFB, 2nd Medical Group, Barksdale AFB, LA 71110, USA
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Sultana P, Novotny J. Rab11 and Its Role in Neurodegenerative Diseases. ASN Neuro 2022; 14:17590914221142360. [PMID: 36464817 PMCID: PMC9726856 DOI: 10.1177/17590914221142360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2022] Open
Abstract
Vesicles mediate the trafficking of membranes/proteins in the endocytic and secretory pathways. These pathways are regulated by small GTPases of the Rab family. Rab proteins belong to the Ras superfamily of GTPases, which are significantly involved in various intracellular trafficking and signaling processes in the nervous system. Rab11 is known to play a key role especially in recycling many proteins, including receptors important for signal transduction and preservation of functional activities of nerve cells. Rab11 activity is controlled by GEFs (guanine exchange factors) and GAPs (GTPase activating proteins), which regulate its function through modulating GTP/GDP exchange and the intrinsic GTPase activity, respectively. Rab11 is involved in the transport of several growth factor molecules important for the development and repair of neurons. Overexpression of Rab11 has been shown to significantly enhance vesicle trafficking. On the other hand, a reduced expression of Rab11 was observed in several neurodegenerative diseases. Current evidence appears to support the notion that Rab11 and its cognate proteins may be potential targets for therapeutic intervention. In this review, we briefly discuss the function of Rab11 and its related interaction partners in intracellular pathways that may be involved in neurodegenerative processes.
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Affiliation(s)
| | - Jiri Novotny
- Jiri Novotny, Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic.
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Wu HF, Yu W, Saito-Diaz K, Huang CW, Carey J, Lefcort F, Hart GW, Liu HX, Zeltner N. Norepinephrine transporter defects lead to sympathetic hyperactivity in Familial Dysautonomia models. Nat Commun 2022; 13:7032. [PMID: 36396637 PMCID: PMC9671909 DOI: 10.1038/s41467-022-34811-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 11/08/2022] [Indexed: 11/19/2022] Open
Abstract
Familial dysautonomia (FD), a rare neurodevelopmental and neurodegenerative disorder affects the sympathetic and sensory nervous system. Although almost all patients harbor a mutation in ELP1, it remains unresolved exactly how function of sympathetic neurons (symNs) is affected; knowledge critical for understanding debilitating disease hallmarks, including cardiovascular instability or dysautonomic crises, that result from dysregulated sympathetic activity. Here, we employ the human pluripotent stem cell (hPSC) system to understand symN disease mechanisms and test candidate drugs. FD symNs are intrinsically hyperactive in vitro, in cardiomyocyte co-cultures, and in animal models. We report reduced norepinephrine transporter expression, decreased intracellular norepinephrine (NE), decreased NE re-uptake, and excessive extracellular NE in FD symNs. SymN hyperactivity is not a direct ELP1 mutation result, but may connect to NET via RAB proteins. We found that candidate drugs lowered hyperactivity independent of ELP1 modulation. Our findings may have implications for other symN disorders and may allow future drug testing and discovery.
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Affiliation(s)
- Hsueh-Fu Wu
- Center for Molecular Medicine, University of Georgia, Athens, GA, USA
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA
| | - Wenxin Yu
- Regenerative Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA, USA
| | - Kenyi Saito-Diaz
- Center for Molecular Medicine, University of Georgia, Athens, GA, USA
| | - Chia-Wei Huang
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | - Joseph Carey
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Frances Lefcort
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Gerald W Hart
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | - Hong-Xiang Liu
- Regenerative Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA, USA
| | - Nadja Zeltner
- Center for Molecular Medicine, University of Georgia, Athens, GA, USA.
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA.
- Department of Cellular Biology, University of Georgia, Athens, GA, USA.
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Blunted Amphetamine-induced Reinforcing Behaviors and Transporter Downregulation in Knock-in Mice Carrying Alanine Mutations at Threonine-258 and Serine-259 of Norepinephrine Transporter. J Mol Neurosci 2022; 72:1965-1976. [DOI: 10.1007/s12031-022-01988-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 01/12/2022] [Indexed: 10/17/2022]
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Sun Y, Li J, Wang L, Cong T, Zhai X, Li L, Wu H, Li S, Xiao Z. Identification of Potential Diagnoses Based on Immune Infiltration and Autophagy Characteristics in Major Depressive Disorder. Front Genet 2022; 13:702366. [PMID: 35559009 PMCID: PMC9087348 DOI: 10.3389/fgene.2022.702366] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 03/25/2022] [Indexed: 12/12/2022] Open
Abstract
Background: Major depressive disorder (MDD) is a serious mental illness characterized by mood changes and high suicide rates. However, no studies are available to support a blood test method for MDD diagnosis. The objective of this research was to identify potential peripheral blood biomarkers for MDD and characterize the novel pathophysiology. Methods: We accessed whole blood microarray sequencing data for MDD and control samples from public databases. Biological functions were analysed by GO and KEGG pathway enrichment analyses using the clusterprofile R package. Infiltrated immune cell (IIC) proportions were identified using the CIBERSORT algorithm. Clustering was performed using the ConsensusClusterPlus R package. Protein–protein interactions (PPI) were assessed by constructing a PPI network using STRING and visualized using Cytoscape software. Rats were exposed to chronic unpredictable mild stress (CUMS) for 6 weeks to induce stress behaviour. Stress behaviour was evaluated by open field experiments and forced swimming tests. Flow cytometry was used to analyse the proportion of CD8+ T cells. The expression of the corresponding key genes was detected by qRT–PCR. Results: We divided MDD patients into CD8H and CD8L clusters. The functional enrichment of marker genes in the CD8H cluster indicated that autophagy-related terms and pathways were significantly enriched. Furthermore, we obtained 110 autophagy-related marker genes (ARMGs) in the CD8H cluster through intersection analysis. GO and KEGG analyses further showed that these ARMGs may regulate a variety of autophagy processes and be involved in the onset and advancement of MDD. Finally, 10 key ARMGs were identified through PPI analysis: RAB1A, GNAI3, VAMP7, RAB33B, MYC, LAMP2, RAB11A, HIF1A, KIF5B, and PTEN. In the CUMS model, flow cytometric analysis confirmed the above findings. qRT–PCR revealed significant decreases in the mRNA levels of Gnai3, Rab33b, Lamp2, and Kif5b in the CUMS groups. Conclusion: In this study, MDD was divided into two subtypes. We combined immune infiltrating CD8+ T cells with autophagy-related genes and screened a total of 10 ARMG genes. In particular, RAB1A, GNAI3, RAB33B, LAMP2, and KIF5B were first reported in MDD. These genes may offer new hope for the clinical diagnosis of MDD.
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Affiliation(s)
- Ye Sun
- Department of Anesthesiology, The Second Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Jinying Li
- Department of Anesthesiology, The Second Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Lin Wang
- Department of Anesthesiology, The Second Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Ting Cong
- Department of Anesthesiology, The Second Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Xiuli Zhai
- Department of Anesthesiology, Inner Mongolia People's Hospital, Hohhot, China
| | - Liya Li
- Department of Anesthesiology, The Second Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Haikuo Wu
- Department of Anesthesiology, The Second Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Shouxin Li
- Department of Anesthesiology, The Second Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Zhaoyang Xiao
- Department of Anesthesiology, The Second Affiliated Hospital of Dalian Medical University, Dalian, China
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Mannangatti P, Ragu Varman D, Ramamoorthy S, Jayanthi LD. Neurokinin-1 Antagonism Distinguishes the Role of Norepinephrine Transporter from Dopamine Transporter in Mediating Amphetamine Behaviors. Pharmacology 2021; 106:597-605. [PMID: 34515205 DOI: 10.1159/000518033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 06/21/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND Amphetamine (AMPH) and other psychostimulants act on the norepinephrine (NE) transporter (NET) and the dopamine (DA) transporter (DAT) and enhance NE and DA signaling. Both NET and DAT share anatomical and functional characteristics and are regulated similarly by psychostimulants and receptor-linked signaling pathways. We and others have demonstrated that NET and DAT are downregulated by AMPH and substance P/neurokinin-1 receptor (NK1R)-mediated protein kinase C pathway. OBJECTIVES Since both NET and DAT are downregulated by AMPH and NK1R activation and share high sequence homology, the objective of the study was to determine the catecholamine transporter specificity in NK1R modulation of AMPH-induced behaviors. METHODS The effect of NK1R antagonism on AMPH-induced conditioned place preference (CPP) as well as AMPH-induced NET and DAT downregulation was examined using NET and DAT knockout mice (NET-KO and DAT-KO) along with their wild-type littermates. RESULTS Aprepitant (5 mg/kg i.p.) significantly attenuated AMPH (2 mg/kg i.p.)-induced CPP in the wild-type and DAT-KO but not in the NET-KO. Locomotor activity measured during the post-conditioning test (in the absence of AMPH) showed higher locomotor activity in DAT-KO compared to wild-type or NET-KO. However, the locomotor activity of all 3 genotypes remained unchanged following aprepitant. Additionally, in the ventral striatum of wild-type, the AMPH-induced downregulation of NET function and surface expression but not that of DAT was attenuated by aprepitant. CONCLUSIONS The results from the current study demonstrate that aprepitant attenuates the expression of AMPH-induced CPP in DAT-KO mice but not in NET-KO mice suggesting a role for NK1R-mediated NET regulation in AMPH-induced behaviors.
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Affiliation(s)
- Padmanabhan Mannangatti
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Durairaj Ragu Varman
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Sammanda Ramamoorthy
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Lankupalle D Jayanthi
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
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Sorkina T, Ma S, Larsen MB, Watkins SC, Sorkin A. Small molecule induced oligomerization, clustering and clathrin-independent endocytosis of the dopamine transporter. eLife 2018; 7:32293. [PMID: 29630493 PMCID: PMC5896956 DOI: 10.7554/elife.32293] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 03/22/2018] [Indexed: 12/14/2022] Open
Abstract
Clathrin-independent endocytosis (CIE) mediates internalization of many transmembrane proteins but the mechanisms of cargo recruitment during CIE are poorly understood. We found that the cell-permeable furopyrimidine AIM-100 promotes dramatic oligomerization, clustering and CIE of human and mouse dopamine transporters (DAT), but not of their close homologues, norepinephrine and serotonin transporters. All effects of AIM-100 on DAT and the occupancy of substrate binding sites in the transporter were mutually exclusive, suggesting that AIM-100 may act by binding to DAT. Surprisingly, AIM-100-induced DAT endocytosis was independent of dynamin, cholesterol-rich microdomains and actin cytoskeleton, implying that a novel endocytic mechanism is involved. AIM-100 stimulated trafficking of internalized DAT was also unusual: DAT accumulated in early endosomes without significant recycling or degradation. We propose that AIM-100 augments DAT oligomerization through an allosteric mechanism associated with the DAT conformational state, and that oligomerization-triggered clustering leads to a coat-independent endocytosis and subsequent endosomal retention of DAT.
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Affiliation(s)
- Tatiana Sorkina
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Shiqi Ma
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Mads Breum Larsen
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Simon C Watkins
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Alexander Sorkin
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
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Mannangatti P, Ramamoorthy S, Jayanthi LD. Interference of norepinephrine transporter trafficking motif attenuates amphetamine-induced locomotor hyperactivity and conditioned place preference. Neuropharmacology 2017; 128:132-141. [PMID: 28986281 DOI: 10.1016/j.neuropharm.2017.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/15/2017] [Accepted: 10/03/2017] [Indexed: 11/28/2022]
Abstract
Amphetamine (AMPH)-mediated norepinephrine transporter (NET) downregulation requires NET-T258/S259 trafficking motif. The present study utilizes cell permeable NET-T258/S259 motif interfering peptide, which blocks AMPH-induced NET downregulation, to explore the role of this form of NET regulation in AMPH-mediated behaviors. In rats receiving intra-accumbal microinjections of TAT-conjugated peptides encompassing NET-T258/S259 motif, acute systemic AMPH failed to inhibit NE transport in the TAT-NET-T258/S259 wild-type (WT) peptide injected hemisphere but not in the vehicle or scrambled peptide injected hemisphere. Acute AMPH-induced hyperactivity was significantly reduced in rats receiving intra-accumbal TAT-NET-T258/S259 WT peptide compared to those receiving intra-accumbal vehicle or TAT-NET-T258A/S259A mutant peptide or corresponding TAT-conjugated scrambled peptide. Basal locomotor activity was not altered by peptide infusions alone. Similarly AMPH-induced locomotor sensitization was significantly reduced in rats receiving intra-accumbal TAT-NET-T258/S259 WT peptide prior to AMPH challenge and not in rats receiving the mutant or scrambled peptide. In conditioned place preference (CPP) paradigm, a single bilateral intra-accumbal microinjection of TAT-NET-T258/S259 WT peptide prior to CPP testing significantly reduced AMPH-induced CPP expression. Likewise, a single bilateral intra-accumbal microinjection of TAT-NET-T258/S259 WT peptide prior to drug-challenge significantly attenuated AMPH-primed CPP reinstatement. On the other hand, bilateral intra-accumbal microinjection of scrambled peptide did not affect AMPH-induced CPP expression or reinstatement. These data demonstrate a role for T258/S259-dependent NET regulation in AMPH-induced hyperactivity and sensitization as well as AMPH-induced CPP expression and reinstatement.
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Affiliation(s)
- Padmanabhan Mannangatti
- 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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Sung U, Binda F, Savchenko V, Owens WA, Daws LC. Ca 2+ dependent surface trafficking of norepinephrine transporters depends on threonine 30 and Ca 2+ calmodulin kinases. J Chem Neuroanat 2016; 83-84:19-35. [PMID: 28017803 DOI: 10.1016/j.jchemneu.2016.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 12/09/2016] [Accepted: 12/15/2016] [Indexed: 11/28/2022]
Abstract
The antidepressant-sensitive norepinephrine (NE) transporter (NET) inactivates NE released during central and peripheral neuronal activity by transport into presynaptic cells. Altered NE clearance due to dysfunction of NET has been associated with the development of mental illness and cardiovascular diseases. NET activity in vivo is influenced by stress, neuronal activity, hormones and drugs. We investigated the mechanisms of Ca2+ regulation of NET and found that Ca2+ influenced both Vmax and Km for NE transport into cortical synaptosomes. Changes in extracellular Ca2+ triggered rapid and bidirectional surface trafficking of NET expressed in cultured cells. Deletion of residues 28-47 in the NET NH2-terminus abolished the Ca2+ effect on surface trafficking. Mutagenesis studies identified Thr30 in this region as the essential residue for both Ca2+- dependent phosphorylation and trafficking of NET. Depolarization of excitable cells increased surface NET in a Thr30 dependent manner. A proteomic analysis, RNA interference, and pharmacological inhibition supported roles of CaMKI and CaMKII in Ca2+-modulated NE transport and NET trafficking. Depolarization of primary noradrenergic neurons in culture with elevated K+ increased NET surface expression in a process that required external Ca2+ and depended on CaMK activity. Hippocampal NE clearance in vivo was also stimulated by depolarization, and inhibitors of CaMK signaling prevented this stimulation. In summary, Ca2+ signaling influenced surface trafficking of NET through a CaMK-dependent mechanism requiring Thr30.
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Affiliation(s)
- Uhna Sung
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232-8548, United States.
| | - Francesca Binda
- Institute of Cellular and Integrative Neurosciences, CNRS, Strasbourg, France
| | - Valentina Savchenko
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232-8548, United States
| | - William A Owens
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, United States
| | - Lynette C Daws
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, United States.
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Bermingham DP, Blakely RD. Kinase-dependent Regulation of Monoamine Neurotransmitter Transporters. Pharmacol Rev 2016; 68:888-953. [PMID: 27591044 PMCID: PMC5050440 DOI: 10.1124/pr.115.012260] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Modulation of neurotransmission by the monoamines dopamine (DA), norepinephrine (NE), and serotonin (5-HT) is critical for normal nervous system function. Precise temporal and spatial control of this signaling in mediated in large part by the actions of monoamine transporters (DAT, NET, and SERT, respectively). These transporters act to recapture their respective neurotransmitters after release, and disruption of clearance and reuptake has significant effects on physiology and behavior and has been linked to a number of neuropsychiatric disorders. To ensure adequate and dynamic control of these transporters, multiple modes of control have evolved to regulate their activity and trafficking. Central to many of these modes of control are the actions of protein kinases, whose actions can be direct or indirectly mediated by kinase-modulated protein interactions. Here, we summarize the current state of our understanding of how protein kinases regulate monoamine transporters through changes in activity, trafficking, phosphorylation state, and interacting partners. We highlight genetic, biochemical, and pharmacological evidence for kinase-linked control of DAT, NET, and SERT and, where applicable, provide evidence for endogenous activators of these pathways. We hope our discussion can lead to a more nuanced and integrated understanding of how neurotransmitter transporters are controlled and may contribute to disorders that feature perturbed monoamine signaling, with an ultimate goal of developing better therapeutic strategies.
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Affiliation(s)
- Daniel P Bermingham
- Department of Pharmacology (D.P.B., R.D.B.) and Psychiatry (R.D.B.), Vanderbilt University Medical Center, Nashville, Tennessee; and Department of Biomedical Sciences, Charles E. Schmidt College of Medicine and Brain Institute, Florida Atlantic University, Jupiter, Florida (R.D.B.)
| | - Randy D Blakely
- Department of Pharmacology (D.P.B., R.D.B.) and Psychiatry (R.D.B.), Vanderbilt University Medical Center, Nashville, Tennessee; and Department of Biomedical Sciences, Charles E. Schmidt College of Medicine and Brain Institute, Florida Atlantic University, Jupiter, Florida (R.D.B.)
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Vuorenpää A, Jørgensen TN, Newman AH, Madsen KL, Scheinin M, Gether U. Differential Internalization Rates and Postendocytic Sorting of the Norepinephrine and Dopamine Transporters Are Controlled by Structural Elements in the N Termini. J Biol Chem 2016; 291:5634-5651. [PMID: 26786096 DOI: 10.1074/jbc.m115.702050] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Indexed: 11/06/2022] Open
Abstract
The norepinephrine transporter (NET) mediates reuptake of synaptically released norepinephrine in central and peripheral noradrenergic neurons. The molecular processes governing availability of NET in the plasma membrane are poorly understood. Here we use the fluorescent cocaine analogue JHC 1-64, as well as several other approaches, to investigate the trafficking itinerary of NET in live noradrenergic neurons. Confocal imaging revealed extensive constitutive internalization of JHC 1-64-labeled NET in the neuronal somata, proximal extensions and presynaptic boutons. Phorbol 12-myristate 13-acetate increased intracellular accumulation of JHC 1-64-labeled NET and caused a parallel reduction in uptake capacity. Internalized NET strongly colocalized with the "long loop" recycling marker Rab11, whereas less overlap was seen with the "short loop" recycling marker Rab4 and the late endosomal marker Rab7. Moreover, mitigating Rab11 function by overexpression of dominant negative Rab11 impaired NET function. Sorting of NET to the Rab11 recycling compartment was further supported by confocal imaging and reversible biotinylation experiments in transfected differentiated CATH.a cells. In contrast to NET, the dopamine transporter displayed markedly less constitutive internalization and limited sorting to the Rab11 recycling compartment in the differentiated CATH.a cells. Exchange of domains between the two homologous transporters revealed that this difference was determined by non-conserved structural elements in the intracellular N terminus. We conclude that NET displays a distinct trafficking itinerary characterized by continuous shuffling between the plasma membrane and the Rab11 recycling compartment and that the functional integrity of the Rab11 compartment is critical for maintaining proper presynaptic NET function.
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Affiliation(s)
- Anne Vuorenpää
- From the Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Panum Institute 18.6, University of Copenhagen, DK-2200 Copenhagen, Denmark,; the Department of Pharmacology, Drug Development, and Therapeutics, University of Turku, Turku FI-20014, Finland,; the Unit of Clinical Pharmacology, Turku University Hospital, Turku FI-20520, Finland, and
| | - Trine N Jørgensen
- From the Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Panum Institute 18.6, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Amy H Newman
- the Medicinal Chemistry Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224
| | - Kenneth L Madsen
- From the Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Panum Institute 18.6, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Mika Scheinin
- the Department of Pharmacology, Drug Development, and Therapeutics, University of Turku, Turku FI-20014, Finland,; the Unit of Clinical Pharmacology, Turku University Hospital, Turku FI-20520, Finland, and
| | - Ulrik Gether
- From the Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Panum Institute 18.6, University of Copenhagen, DK-2200 Copenhagen, Denmark,.
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Chu R, Shumsky J, Waterhouse BD. Differentiation of rodent behavioral phenotypes and methylphenidate action in sustained and flexible attention tasks. Brain Res 2015; 1641:306-19. [PMID: 26688113 DOI: 10.1016/j.brainres.2015.11.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 11/23/2015] [Accepted: 11/25/2015] [Indexed: 01/15/2023]
Abstract
Methyphenidate (MPH) is the primary drug treatment of choice for ADHD. It is also frequently used off-label as a cognitive enhancer by otherwise healthy individuals from all age groups and walks of life. Military personnel, students, and health professionals use MPH illicitly to increase attention and improve workplace performance over extended periods of work activity. Despite the frequency of its use, the efficacy of MPH to enhance cognitive function across individuals and in a variety of circumstances is not well characterized. We sought to better understand MPH׳s cognitive enhancing properties in two different rodent models of attention. We found that MPH could enhance performance in a sustained attention task, but that its effects in this test were subject dependent. More specifically, MPH increased attention in low baseline performing rats but had little to no effect on high performing rats. MPH exerted a similar subject specific effect in a test of flexible attention, i.e. the attention set shifting task. In this test MPH increased behavioral flexibility in animals with poor flexibility but impaired performance in more flexible animals. Overall, our results indicate that the effects of MPH are subject-specific and depend on the baseline level of performance. Furthermore, good performance in in the sustained attention task was correlated with good performance in the flexible attention task; i.e. animals with better vigilance exhibited greater behavioral flexibility. The findings are discussed in terms of potential neurobiological substrates, in particular noradrenergic mechanisms, that might underlie subject specific performance and subject specific responses to MPH. This article is part of a Special Issue entitled SI: Noradrenergic System.
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Affiliation(s)
- Richard Chu
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, United States
| | - Jed Shumsky
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, United States
| | - Barry D Waterhouse
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, United States.
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13
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Bellot M, Galandrin S, Boularan C, Matthies HJ, Despas F, Denis C, Javitch J, Mazères S, Sanni SJ, Pons V, Seguelas MH, Hansen JL, Pathak A, Galli A, Sénard JM, Galés C. Dual agonist occupancy of AT1-R-α2C-AR heterodimers results in atypical Gs-PKA signaling. Nat Chem Biol 2015; 11:271-9. [PMID: 25706338 DOI: 10.1038/nchembio.1766] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 01/09/2015] [Indexed: 12/25/2022]
Abstract
Hypersecretion of norepinephrine (NE) and angiotensin II (AngII) is a hallmark of major prevalent cardiovascular diseases that contribute to cardiac pathophysiology and morbidity. Herein, we explore whether heterodimerization of presynaptic AngII AT1 receptor (AT1-R) and NE α2C-adrenergic receptor (α2C-AR) could underlie their functional cross-talk to control NE secretion. Multiple bioluminescence resonance energy transfer and protein complementation assays allowed us to accurately probe the structures and functions of the α2C-AR-AT1-R dimer promoted by ligand binding to individual protomers. We found that dual agonist occupancy resulted in a conformation of the heterodimer different from that induced by active individual protomers and triggered atypical Gs-cAMP-PKA signaling. This specific pharmacological signaling unit was identified in vivo to promote not only NE hypersecretion in sympathetic neurons but also sympathetic hyperactivity in mice. Thus, we uncovered a new process by which GPCR heterodimerization creates an original functional pharmacological entity and that could constitute a promising new target in cardiovascular therapeutics.
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Affiliation(s)
- Morgane Bellot
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université Toulouse III Paul Sabatier, Toulouse, France
| | - Ségolène Galandrin
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université Toulouse III Paul Sabatier, Toulouse, France
| | - Cédric Boularan
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université Toulouse III Paul Sabatier, Toulouse, France
| | - Heinrich J Matthies
- 1] Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA. [2] Neuroscience Program in Substance Abuse, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Fabien Despas
- 1] Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université Toulouse III Paul Sabatier, Toulouse, France. [2] Service de Pharmacologie Clinique, Centre Hospitalier Universitaire de Toulouse, Faculté de Médecine, Toulouse, France
| | - Colette Denis
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université Toulouse III Paul Sabatier, Toulouse, France
| | - Jonathan Javitch
- 1] Center for Molecular Recognition and Departments of Psychiatry and Pharmacology, Columbia University, New York, New York, USA. [2] College of Physicians and Surgeons, Columbia University, New York, New York, USA. [3] Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York, USA
| | - Serge Mazères
- Institut de Pharmacologie et de Biologie Structurale (IPBS), CNRS, UMR 508, Université Toulouse III Paul Sabatier, Toulouse, France
| | - Samra Joke Sanni
- 1] Department of Clinical Biochemistry, Glostrup Hospital, Glostrup, Denmark. [2] Diabetes Biology and Metabolism, Novo Nordisk, Måløv, Denmark
| | - Véronique Pons
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université Toulouse III Paul Sabatier, Toulouse, France
| | - Marie-Hélène Seguelas
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université Toulouse III Paul Sabatier, Toulouse, France
| | - Jakob L Hansen
- Diabetes Biology and Metabolism, Novo Nordisk, Måløv, Denmark
| | - Atul Pathak
- 1] Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université Toulouse III Paul Sabatier, Toulouse, France. [2] Service de Pharmacologie Clinique, Centre Hospitalier Universitaire de Toulouse, Faculté de Médecine, Toulouse, France
| | - Aurelio Galli
- 1] Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA. [2] Neuroscience Program in Substance Abuse, Vanderbilt University School of Medicine, Nashville, Tennessee, USA. [3] Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee, USA. [4] Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Jean-Michel Sénard
- 1] Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université Toulouse III Paul Sabatier, Toulouse, France. [2] Service de Pharmacologie Clinique, Centre Hospitalier Universitaire de Toulouse, Faculté de Médecine, Toulouse, France
| | - Céline Galés
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, U1048, Université Toulouse III Paul Sabatier, Toulouse, France
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14
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Rahbek-Clemmensen T, Bay T, Eriksen J, Gether U, Jørgensen TN. The serotonin transporter undergoes constitutive internalization and is primarily sorted to late endosomes and lysosomal degradation. J Biol Chem 2014; 289:23004-23019. [PMID: 24973209 DOI: 10.1074/jbc.m113.495754] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The serotonin transporter (SERT) plays a critical role in regulating serotonin signaling by mediating reuptake of serotonin from the extracellular space. The molecular and cellular mechanisms controlling SERT levels in the membrane remain poorly understood. To study trafficking of the surface resident SERT, two functional epitope-tagged variants were generated. Fusion of a FLAG-tagged one-transmembrane segment protein Tac to the SERT N terminus generated a transporter with an extracellular epitope suited for trafficking studies (TacSERT). Likewise, a construct with an extracellular antibody epitope was generated by introducing an HA (hemagglutinin) tag in the extracellular loop 2 of SERT (HA-SERT). By using TacSERT and HA-SERT in antibody-based internalization assays, we show that SERT undergoes constitutive internalization in a dynamin-dependent manner. Confocal images of constitutively internalized SERT demonstrated that SERT primarily co-localized with the late endosomal/lysosomal marker Rab7, whereas little co-localization was observed with the Rab11, a marker of the "long loop" recycling pathway. This sorting pattern was distinct from that of a prototypical recycling membrane protein, the β2-adrenergic receptor. Furthermore, internalized SERT co-localized with the lysosomal marker LysoTracker and not with transferrin. The sorting pattern was further confirmed by visualizing internalization of SERT using the fluorescent cocaine analog JHC1-64 and by reversible and pulse-chase biotinylation assays showing evidence for lysosomal degradation of the internalized transporter. Finally, we found that SERT internalized in response to stimulation with 12-myristate 13-acetate co-localized primarily with Rab7- and LysoTracker-positive compartments. We conclude that SERT is constitutively internalized and that the internalized transporter is sorted mainly to degradation.
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Affiliation(s)
- Troels Rahbek-Clemmensen
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, and University of Copenhagen, DK-2200 Copenhagen, Denmark; Lundbeck Foundation Center for Biomembranes in Nanomedicine, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Tina Bay
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, and University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Jacob Eriksen
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, and University of Copenhagen, DK-2200 Copenhagen, Denmark; Lundbeck Foundation Center for Biomembranes in Nanomedicine, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Ulrik Gether
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, and University of Copenhagen, DK-2200 Copenhagen, Denmark; Lundbeck Foundation Center for Biomembranes in Nanomedicine, University of Copenhagen, DK-2200 Copenhagen, Denmark.
| | - Trine Nygaard Jørgensen
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, and University of Copenhagen, DK-2200 Copenhagen, Denmark
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15
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Matsunami N, Hensel CH, Baird L, Stevens J, Otterud B, Leppert T, Varvil T, Hadley D, Glessner JT, Pellegrino R, Kim C, Thomas K, Wang F, Otieno FG, Ho K, Christensen GB, Li D, Prekeris R, Lambert CG, Hakonarson H, Leppert MF. Identification of rare DNA sequence variants in high-risk autism families and their prevalence in a large case/control population. Mol Autism 2014; 5:5. [PMID: 24467814 PMCID: PMC4098669 DOI: 10.1186/2040-2392-5-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 12/24/2013] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Genetics clearly plays a major role in the etiology of autism spectrum disorders (ASDs), but studies to date are only beginning to characterize the causal genetic variants responsible. Until recently, studies using multiple extended multi-generation families to identify ASD risk genes had not been undertaken. METHODS We identified haplotypes shared among individuals with ASDs in large multiplex families, followed by targeted DNA capture and sequencing to identify potential causal variants. We also assayed the prevalence of the identified variants in a large ASD case/control population. RESULTS We identified 584 non-conservative missense, nonsense, frameshift and splice site variants that might predispose to autism in our high-risk families. Eleven of these variants were observed to have odds ratios greater than 1.5 in a set of 1,541 unrelated children with autism and 5,785 controls. Three variants, in the RAB11FIP5, ABP1, and JMJD7-PLA2G4B genes, each were observed in a single case and not in any controls. These variants also were not seen in public sequence databases, suggesting that they may be rare causal ASD variants. Twenty-eight additional rare variants were observed only in high-risk ASD families. Collectively, these 39 variants identify 36 genes as ASD risk genes. Segregation of sequence variants and of copy number variants previously detected in these families reveals a complex pattern, with only a RAB11FIP5 variant segregating to all affected individuals in one two-generation pedigree. Some affected individuals were found to have multiple potential risk alleles, including sequence variants and copy number variants (CNVs), suggesting that the high incidence of autism in these families could be best explained by variants at multiple loci. CONCLUSIONS Our study is the first to use haplotype sharing to identify familial ASD risk loci. In total, we identified 39 variants in 36 genes that may confer a genetic risk of developing autism. The observation of 11 of these variants in unrelated ASD cases further supports their role as ASD risk variants.
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Affiliation(s)
- Nori Matsunami
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | | | - Lisa Baird
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Jeff Stevens
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Brith Otterud
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Tami Leppert
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Tena Varvil
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Dexter Hadley
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Joseph T Glessner
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Renata Pellegrino
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Cecilia Kim
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Kelly Thomas
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Fengxiang Wang
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Frederick G Otieno
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Karen Ho
- Lineagen, Inc, Salt Lake City, UT, USA
| | | | - Dongying Li
- Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Rytis Prekeris
- Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | | | - Hakon Hakonarson
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Mark F Leppert
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
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16
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Saunders C, Siuta M, Robertson SD, Davis AR, Sauer J, Matthies HJG, Gresch PJ, Airey D, Lindsley CW, Schetz JA, Niswender KD, Veenstra-Vanderweele JM, Galli A. Neuronal ablation of p-Akt at Ser473 leads to altered 5-HT1A/2A receptor function. Neurochem Int 2013; 73:113-121. [PMID: 24090638 DOI: 10.1016/j.neuint.2013.09.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 09/16/2013] [Accepted: 09/19/2013] [Indexed: 02/08/2023]
Abstract
The serotonergic system regulates a wide range of behavior, including mood and impulsivity, and its dysregulation has been associated with mood disorders, autism spectrum disorder, and addiction. Diabetes is a risk factor for these conditions. Insulin resistance in the brain is specifically associated with susceptibility to psychostimulant abuse. Here, we examined whether phosphorylation of Akt, a key regulator of the insulin signaling pathway, controls serotonin (5-HT) signaling. To explore how impairment in Akt function regulates 5-HT homeostasis, we used a brain-specific rictor knockout (KO) mouse model of impaired neuronal phosphorylation of Akt at Ser473. Cortical 5-HT1A and 5-HT2A receptor binding was significantly elevated in rictor KO mice. Concomitant with this elevated receptor expression, the 5-HT1A receptor agonist 8-Hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) led to an increased hypothermic response in rictor KO mice. The increased cortical 5-HT1A receptor density was associated with higher 5-HT1A receptor levels on the cortical cell surface. In contrast, rictor KO mice displayed significantly reduced head-twitch response (HTR) to the 5-HT2A/C agonist 2,5-dimethoxy-4-iodoamphetamine (DOI), with evidence of impaired 5-HT2A/C receptor signaling. In vitro, pharmacological inhibition of Akt significantly increased 5-HT1A receptor expression and attenuated DOI-induced 5-HT2A receptor signaling, thereby lending credence to the observed in vivo cross-talk between neuronal Akt signaling and 5-HT receptor regulation. These data reveal that defective central Akt function alters 5-HT signaling as well as 5-HT-associated behaviors, demonstrating a novel role for Akt in maintaining neuronal 5-HT receptor function.
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Affiliation(s)
- Christine Saunders
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN
| | - Michael Siuta
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN
| | - Sabrina D Robertson
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN
| | - Adeola R Davis
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN
| | - Jennifer Sauer
- Department of Psychiatry, Vanderbilt University Medical Center, Nashville, TN
| | - Heinrich J G Matthies
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN
| | - Paul J Gresch
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN
| | - David Airey
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN
| | - Craig W Lindsley
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN
| | - John A Schetz
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX
| | - Kevin D Niswender
- Department of Medicine Vanderbilt University Medical Center, Nashville, TN
| | - Jeremy M Veenstra-Vanderweele
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN.,Department of Psychiatry, Vanderbilt University Medical Center, Nashville, TN
| | - Aurelio Galli
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN.,Department of Neuroscience Program in Substance Abuse, Vanderbilt University Medical Center, Nashville, TN
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17
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Hong WC, Amara SG. Differential targeting of the dopamine transporter to recycling or degradative pathways during amphetamine- or PKC-regulated endocytosis in dopamine neurons. FASEB J 2013; 27:2995-3007. [PMID: 23612789 DOI: 10.1096/fj.12-218727] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The dopamine transporter (DAT) clears the extracellular dopamine released during neurotransmission and is a major target for both therapeutic and addictive psychostimulant amphetamines. Amphetamine exposure or activation of protein kinase C (PKC) by the phorbol ester PMA has been shown to down-regulate cell surface DAT. However, in dopamine neurons, the trafficking itinerary and fate of internalized DAT has not been elucidated. By monitoring surface-labeled DAT in transfected dopamine neurons from embryonic rat mesencephalic cultures, we find distinct sorting and fates of internalized DAT after amphetamine or PMA treatment. Although both drugs promote DAT internalization above constitutive endocytosis in dopamine neurons, PMA induces ubiquitination of DAT and leads to accumulation of DAT on LAMP1-positive endosomes. In contrast, after amphetamine exposure DAT is sorted to recycling endosomes positive for Rab11 and the transferrin receptor. Furthermore, quantitative assessment of DAT recycling using an antibody-feeding assay reveals that significantly less DAT returns to the surface of dopamine neurons after internalization by PMA, compared with vehicle or amphetamine treatment. These results demonstrate that, in neurons, the DAT is sorted differentially to recycling and degradative pathways after psychostimulant exposure or PKC activation, which may allow for either the transient or sustained inhibition of DAT during dopamine neurotransmission.
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Affiliation(s)
- Weimin C Hong
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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18
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Baetz NW, Goldenring JR. Rab11-family interacting proteins define spatially and temporally distinct regions within the dynamic Rab11a-dependent recycling system. Mol Biol Cell 2013; 24:643-58. [PMID: 23283983 PMCID: PMC3583667 DOI: 10.1091/mbc.e12-09-0659] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The Rab11-family interacting proteins (Rab11-FIPs) facilitate Rab11-dependent vesicle recycling. We hypothesized that Rab11-FIPs define discrete subdomains and carry out temporally distinct roles within the recycling system. We used live-cell deconvolution microscopy of HeLa cells expressing chimeric fluorescent Rab11-FIPs to examine Rab11-FIP localization, transferrin passage through Rab11-FIP-containing compartments, and overlap among Rab11-FIPs within the recycling system. FIP1A, FIP2, and FIP5 occupy widely distributed mobile tubules and vesicles, whereas FIP1B, FIP1C, and FIP3 localize to perinuclear tubules. Internalized transferrin entered Rab11-FIP-containing compartments within 5 min, reaching maximum colocalization with FIP1B and FIP2 early in the time course, whereas localization with FIP1A, FIP1C, FIP3, and FIP5 was delayed until 10 min or later. Whereas direct interactions with FIP1A were only observed for FIP1B and FIP1C, FIP1A also associated with membranes containing FIP3. Live-cell dual-expression studies of Rab11-FIPs revealed the tubular dynamics of Rab11-FIP-containing compartments and demonstrated a series of selective associations among Rab11-FIPs in real time. These findings suggest that Rab11-FIP1 proteins participate in spatially and temporally distinct steps of the recycling process along a complex and dynamic tubular network in which Rab11-FIPs occupy discrete domains.
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Affiliation(s)
- Nicholas W Baetz
- Section of Surgical Sciences and Epithelial Biology Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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19
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Hysek CM, Simmler LD, Nicola VG, Vischer N, Donzelli M, Krähenbühl S, Grouzmann E, Huwyler J, Hoener MC, Liechti ME. Duloxetine inhibits effects of MDMA ("ecstasy") in vitro and in humans in a randomized placebo-controlled laboratory study. PLoS One 2012; 7:e36476. [PMID: 22574166 PMCID: PMC3344887 DOI: 10.1371/journal.pone.0036476] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Accepted: 03/31/2012] [Indexed: 12/01/2022] Open
Abstract
This study assessed the effects of the serotonin (5-HT) and norepinephrine (NE) transporter inhibitor duloxetine on the effects of 3,4–methylenedioxymethamphetamine (MDMA, ecstasy) in vitro and in 16 healthy subjects. The clinical study used a double-blind, randomized, placebo-controlled, four-session, crossover design. In vitro, duloxetine blocked the release of both 5-HT and NE by MDMA or by its metabolite 3,4-methylenedioxyamphetamine from transmitter-loaded human cells expressing the 5-HT or NE transporter. In humans, duloxetine inhibited the effects of MDMA including elevations in circulating NE, increases in blood pressure and heart rate, and the subjective drug effects. Duloxetine inhibited the pharmacodynamic response to MDMA despite an increase in duloxetine-associated elevations in plasma MDMA levels. The findings confirm the important role of MDMA-induced 5-HT and NE release in the psychotropic effects of MDMA. Duloxetine may be useful in the treatment of psychostimulant dependence.
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Affiliation(s)
- Cédric M. Hysek
- Psychopharmacology Research Group, Division of Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Internal Medicine, University Hospital and University of Basel, Basel, Switzerland
| | - Linda D. Simmler
- Psychopharmacology Research Group, Division of Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Internal Medicine, University Hospital and University of Basel, Basel, Switzerland
| | - Valentina G. Nicola
- Psychopharmacology Research Group, Division of Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Internal Medicine, University Hospital and University of Basel, Basel, Switzerland
| | - Nerina Vischer
- Psychopharmacology Research Group, Division of Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Internal Medicine, University Hospital and University of Basel, Basel, Switzerland
| | - Massimiliano Donzelli
- Psychopharmacology Research Group, Division of Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Internal Medicine, University Hospital and University of Basel, Basel, Switzerland
| | - Stephan Krähenbühl
- Psychopharmacology Research Group, Division of Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Internal Medicine, University Hospital and University of Basel, Basel, Switzerland
| | - Eric Grouzmann
- Divisions of Clinical Pharmacology and Toxicology, University Hospital, Lausanne, Switzerland
| | - Jörg Huwyler
- Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Marius C. Hoener
- Pharmaceuticals Division, Neuroscience Research, F. Hoffmann-La Roche Ltd., Basel, Switzerland
| | - Matthias E. Liechti
- Psychopharmacology Research Group, Division of Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Internal Medicine, University Hospital and University of Basel, Basel, Switzerland
- * E-mail:
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20
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Esposito G, Ana Clara F, Verstreken P. Synaptic vesicle trafficking and Parkinson's disease. Dev Neurobiol 2011; 72:134-44. [DOI: 10.1002/dneu.20916] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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21
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Li X, DiFiglia M. The recycling endosome and its role in neurological disorders. Prog Neurobiol 2011; 97:127-41. [PMID: 22037413 DOI: 10.1016/j.pneurobio.2011.10.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 10/14/2011] [Accepted: 10/17/2011] [Indexed: 02/08/2023]
Abstract
The recycling endosome (RE) is an organelle in the endocytic pathway where plasma membranes (proteins and lipids) internalized by endocytosis are processed back to the cell surface for reuse. Endocytic recycling is the primary way for the cell to maintain constituents of the plasma membrane (Griffiths et al., 1989), i.e., to maintain the abundance of receptors and transporters on cell surfaces. Membrane traffic through the RE is crucial for several key cellular processes including cytokinesis and cell migration. In polarized cells, including neurons, the RE is vital for the generation and maintenance of the polarity of the plasma membrane. Many RE dependent cargo molecules are known to be important for neuronal function and there is evidence that improper function of key proteins in RE-associated pathways may contribute to the pathogenesis of neurological disorders, including Huntington's disease. The function of the RE in neurons is poorly understood. Therefore, there is need to understand how membrane dynamics in RE-associated pathways are affected or participate in the development or progression of neurological diseases. This review summarizes advances in understanding endocytic recycling associated with the RE, challenges in elucidating molecular mechanisms underlying RE function, and evidence for RE dysfunction in neurological disorders.
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Affiliation(s)
- Xueyi Li
- Laboratory of Cellular Neurobiology and Department of Neurology, Massachusetts General Hospital, 114 16th Street, Charlestown, MA 02129, USA
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Speed N, Saunders C, Davis AR, Owens WA, Matthies HJG, Saadat S, Kennedy JP, Vaughan RA, Neve RL, Lindsley CW, Russo SJ, Daws LC, Niswender1 KD, Galli A. Impaired striatal Akt signaling disrupts dopamine homeostasis and increases feeding. PLoS One 2011; 6:e25169. [PMID: 21969871 PMCID: PMC3182178 DOI: 10.1371/journal.pone.0025169] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 08/26/2011] [Indexed: 11/18/2022] Open
Abstract
Background The prevalence of obesity has increased dramatically worldwide. The obesity epidemic begs for novel concepts and therapeutic targets that cohesively address “food-abuse” disorders. We demonstrate a molecular link between impairment of a central kinase (Akt) involved in insulin signaling induced by exposure to a high-fat (HF) diet and dysregulation of higher order circuitry involved in feeding. Dopamine (DA) rich brain structures, such as striatum, provide motivation stimuli for feeding. In these central circuitries, DA dysfunction is posited to contribute to obesity pathogenesis. We identified a mechanistic link between metabolic dysregulation and the maladaptive behaviors that potentiate weight gain. Insulin, a hormone in the periphery, also acts centrally to regulate both homeostatic and reward-based HF feeding. It regulates DA homeostasis, in part, by controlling a key element in DA clearance, the DA transporter (DAT). Upon HF feeding, nigro-striatal neurons rapidly develop insulin signaling deficiencies, causing increased HF calorie intake. Methodology/Principal Findings We show that consumption of fat-rich food impairs striatal activation of the insulin-activated signaling kinase, Akt. HF-induced Akt impairment, in turn, reduces DAT cell surface expression and function, thereby decreasing DA homeostasis and amphetamine (AMPH)-induced DA efflux. In addition, HF-mediated dysregulation of Akt signaling impairs DA-related behaviors such as (AMPH)-induced locomotion and increased caloric intake. We restored nigro-striatal Akt phosphorylation using recombinant viral vector expression technology. We observed a rescue of DAT expression in HF fed rats, which was associated with a return of locomotor responses to AMPH and normalization of HF diet-induced hyperphagia. Conclusions/Significance Acquired disruption of brain insulin action may confer risk for and/or underlie “food-abuse” disorders and the recalcitrance of obesity. This molecular model, thus, explains how even short-term exposure to “the fast food lifestyle” creates a cycle of disordered eating that cements pathological changes in DA signaling leading to weight gain and obesity.
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Affiliation(s)
- Nicole Speed
- Department of Pharmacology, School of Medicine, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Christine Saunders
- Department of Pharmacology, School of Medicine, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Adeola R. Davis
- Department of Molecular Physiology and Biophysics, School of Medicine, Vanderbilt University, Nashville, Tennessee, United States of America
| | - W. Anthony Owens
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Heinrich J. G. Matthies
- Department of Molecular Physiology and Biophysics, School of Medicine, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Sanaz Saadat
- Tennessee Valley Healthcare System, Nashville, Tennessee, United States of America
| | - Jack P. Kennedy
- Department of Pharmacology, School of Medicine, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Roxanne A. Vaughan
- Department of Biochemistry and Molecular Biology, School of Medicine and Health Science, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Rachael L. Neve
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Craig W. Lindsley
- Department of Pharmacology, School of Medicine, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Scott J. Russo
- Department of Neuroscience, Mount Sinai Medical Center, New York, New York, United States of America
| | - Lynette C. Daws
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Kevin D. Niswender1
- Tennessee Valley Healthcare System, Nashville, Tennessee, United States of America
- Department of Medicine, School of Medicine, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Aurelio Galli
- Department of Molecular Physiology and Biophysics, School of Medicine, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pharmacology, School of Medicine, Vanderbilt University, Nashville, Tennessee, United States of America
- Center for Molecular Neuroscience, School of Medicine, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail:
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Kristensen AS, Andersen J, Jørgensen TN, Sørensen L, Eriksen J, Loland CJ, Strømgaard K, Gether U. SLC6 neurotransmitter transporters: structure, function, and regulation. Pharmacol Rev 2011; 63:585-640. [PMID: 21752877 DOI: 10.1124/pr.108.000869] [Citation(s) in RCA: 591] [Impact Index Per Article: 45.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The neurotransmitter transporters (NTTs) belonging to the solute carrier 6 (SLC6) gene family (also referred to as the neurotransmitter-sodium-symporter family or Na(+)/Cl(-)-dependent transporters) comprise a group of nine sodium- and chloride-dependent plasma membrane transporters for the monoamine neurotransmitters serotonin (5-hydroxytryptamine), dopamine, and norepinephrine, and the amino acid neurotransmitters GABA and glycine. The SLC6 NTTs are widely expressed in the mammalian brain and play an essential role in regulating neurotransmitter signaling and homeostasis by mediating uptake of released neurotransmitters from the extracellular space into neurons and glial cells. The transporters are targets for a wide range of therapeutic drugs used in treatment of psychiatric diseases, including major depression, anxiety disorders, attention deficit hyperactivity disorder and epilepsy. Furthermore, psychostimulants such as cocaine and amphetamines have the SLC6 NTTs as primary targets. Beginning with the determination of a high-resolution structure of a prokaryotic homolog of the mammalian SLC6 transporters in 2005, the understanding of the molecular structure, function, and pharmacology of these proteins has advanced rapidly. Furthermore, intensive efforts have been directed toward understanding the molecular and cellular mechanisms involved in regulation of the activity of this important class of transporters, leading to new methodological developments and important insights. This review provides an update of these advances and their implications for the current understanding of the SLC6 NTTs.
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Affiliation(s)
- Anders S Kristensen
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Narita M, Niikura K, Nanjo-Niikura K, Narita M, Furuya M, Yamashita A, Saeki M, Matsushima Y, Imai S, Shimizu T, Asato M, Kuzumaki N, Okutsu D, Miyoshi K, Suzuki M, Tsukiyama Y, Konno M, Yomiya K, Matoba M, Suzuki T. Sleep disturbances in a neuropathic pain-like condition in the mouse are associated with altered GABAergic transmission in the cingulate cortex. Pain 2011; 152:1358-1372. [DOI: 10.1016/j.pain.2011.02.016] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 02/04/2011] [Accepted: 02/07/2011] [Indexed: 11/17/2022]
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Ramamoorthy S, Shippenberg TS, Jayanthi LD. Regulation of monoamine transporters: Role of transporter phosphorylation. Pharmacol Ther 2010; 129:220-38. [PMID: 20951731 DOI: 10.1016/j.pharmthera.2010.09.009] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 09/24/2010] [Indexed: 10/18/2022]
Abstract
Presynaptic biogenic amine transporters mediate reuptake of released amines from the synapse, thus regulating serotonin, dopamine and norepinephrine neurotransmission. Medications utilized in the treatment of depression, attention deficit-hyperactivity disorder and other psychiatric disorders possess high affinity for amine transporters. In addition, amine transporters are targets for psychostimulants. Altered expression of biogenic amine transporters has long been implicated in several psychiatric and degenerative disorders. Therefore, appropriate regulation and maintenance of biogenic amine transporter activity is critical for the maintenance of normal amine homoeostasis. Accumulating evidence suggests that cellular protein kinases and phosphatases regulate amine transporter expression, activity, trafficking and degradation. Amine transporters are phosphoproteins that undergo dynamic control under the influence of various kinase and phosphatase activities. This review presents a brief overview of the role of amine transporter phosphorylation in the regulation of amine transport in the normal and diseased brain. Understanding the molecular mechanisms by which phosphorylation events affect amine transporter activity is essential for understanding the contribution of transporter phosphorylation to the regulation of monoamine neurotransmission and for identifying potential new targets for the treatment of various brain diseases.
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Affiliation(s)
- Sammanda Ramamoorthy
- Department of Neurosciences, Division of Neuroscience Research, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
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Insulin reveals Akt signaling as a novel regulator of norepinephrine transporter trafficking and norepinephrine homeostasis. J Neurosci 2010; 30:11305-16. [PMID: 20739551 DOI: 10.1523/jneurosci.0126-10.2010] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Noradrenergic signaling in the CNS plays an essential role in circuits involving attention, mood, memory, and stress as well as providing pivotal support for autonomic function in the peripheral nervous system. The high-affinity norepinephrine (NE) transporter (NET) is the primary mechanism by which noradrenergic synaptic transmission is terminated. Data indicate that NET function is regulated by insulin, a hormone critical for the regulation of metabolism. Given the high comorbidity of metabolic disorders such as diabetes and obesity with mental disorders such as depression and schizophrenia, we sought to determine how insulin signaling regulates NET function and thus noradrenergic homeostasis. Here, we show that acute insulin treatment, through the downstream kinase protein kinase B (Akt), significantly decreases NET surface expression in mouse hippocampal slices and superior cervical ganglion neuron boutons (sites of synaptic NE release). In vivo manipulation of insulin/Akt signaling, with streptozotocin, a drug that induces a type 1-like diabetic state in mice, also results in aberrant NET function and NE homeostasis. Notably, we also demonstrate that Akt inhibition or stimulation, independent of insulin, is capable of altering NET surface availability. These data suggest that aberrant states of Akt signaling such as in diabetes and obesity have the potential to alter NET function and noradrenergic tone in the brain. Furthermore, they provide one potential molecular mechanism by which Akt, a candidate gene for mood disorders such as schizophrenia and depression, can impact brain monoamine homeostasis.
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