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Sigurdardottir HL, Kranz GS, Rami-Mark C, James GM, Vanicek T, Gryglewski G, Kautzky A, Hienert M, Traub-Weidinger T, Mitterhauser M, Wadsak W, Hacker M, Rujescu D, Kasper S, Lanzenberger R. Effects of norepinephrine transporter gene variants on NET binding in ADHD and healthy controls investigated by PET. Hum Brain Mapp 2015; 37:884-95. [PMID: 26678348 PMCID: PMC4949568 DOI: 10.1002/hbm.23071] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 11/18/2015] [Accepted: 11/18/2015] [Indexed: 01/08/2023] Open
Abstract
Attention deficit hyperactivity disorder (ADHD) is a heterogeneous disorder with a strong genetic component. The norepinephrine transporter (NET) is a key target for ADHD treatment and the NET gene has been of high interest as a possible modulator of ADHD pathophysiology. Therefore, we conducted an imaging genetics study to examine possible effects of single nucleotide polymorphisms (SNPs) within the NET gene on NET nondisplaceable binding potential (BPND ) in patients with ADHD and healthy controls (HCs). Twenty adult patients with ADHD and 20 HCs underwent (S,S)-[18F]FMeNER-D2 positron emission tomography (PET) and were genotyped on a MassARRAY MALDI-TOF platform using the Sequenom iPLEX assay. Linear mixed models analyses revealed a genotype-dependent difference in NET BPND between groups in the thalamus and cerebellum. In the thalamus, a functional promoter SNP (-3081 A/T) and a 5'-untranslated region (5'UTR) SNP (-182 T/C), showed higher binding in ADHD patients compared to HCs depending on the major allele. Furthermore, we detected an effect of genotype in HCs, with major allele carriers having lower binding. In contrast, for two 3'UTR SNPs (*269 T/C, *417 A/T), ADHD subjects had lower binding in the cerebellum compared to HCs depending on the major allele. Additionally, symptoms of hyperactivity and impulsivity correlated with NET BPND in the cerebellum depending on genotype. Symptoms correlated positively with cerebellar NET BPND for the major allele, while symptoms correlated negatively to NET BPND in minor allele carriers. Our findings support the role of genetic influence of the NE system on NET binding to be pertubated in ADHD.
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Affiliation(s)
- Helen L Sigurdardottir
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Georg S Kranz
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Christina Rami-Mark
- Department of Biomedical Imaging and Image-Guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria
| | - Gregory M James
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Thomas Vanicek
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Gregor Gryglewski
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Alexander Kautzky
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Marius Hienert
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Tatjana Traub-Weidinger
- Department of Biomedical Imaging and Image-Guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria
| | - Markus Mitterhauser
- Department of Biomedical Imaging and Image-Guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria
| | - Wolfgang Wadsak
- Department of Biomedical Imaging and Image-Guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria
| | - Marcus Hacker
- Department of Biomedical Imaging and Image-Guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria
| | - Dan Rujescu
- Department of Psychiatry, University of Halle, Halle, Germany
| | - Siegfried Kasper
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Rupert Lanzenberger
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
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Abstract
For many years, the norepinephrine transporter (NET) was considered a 'static' protein that contributed to the termination of the action of norepinephrine in the synapse of noradrenergic neurons. The concept that the NET is dynamically regulated, adjusting noradrenergic transmission by changing its function and/or expression, was considered initially in the mid 1980s. Since that time, a plethora of studies demonstrate that the NET is regulated by several intracellular and extracellular signaling molecules, and that phosphorylation of the NET is a major pathway regulating its cell surface expression and thereby its function. The NET is a target of action of a number of drugs that are used long-term therapeutically or abused chronically. This has driven numerous investigations of how the NET and its function are regulated by long-term exposure to drugs. While repeated exposure to many drugs has been shown to affect NET function and expression, the intracellular mechanisms for these effects remains elusive.
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Affiliation(s)
- Prashant Mandela
- Department of Pharmacology & Toxicology, University of Mississippi Medical Center, Jackson, USA
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Salbaum JM, Cirelli C, Walcott E, Krushel LA, Edelman GM, Tononi G. Chlorotoxin-mediated disinhibition of noradrenergic locus coeruleus neurons using a conditional transgenic approach. Brain Res 2004; 1016:20-32. [PMID: 15234248 DOI: 10.1016/j.brainres.2004.03.078] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/02/2004] [Indexed: 10/26/2022]
Abstract
The noradrenergic locus coeruleus (LC) has been implicated in the promotion of arousal, in focused attention and learning, and in the regulation of the sleep/waking cycle. The complex biological functions of the central noradrenergic system have been investigated largely through electrophysiological recordings and neurotoxic lesions of LC neurons. Activation of LC neurons through electrical or chemical stimulation has also led to important insights, although these techniques have limited cellular specificity and short-term effects. Here, we describe a novel method aimed at stimulating the central noradrenergic system in a highly selective manner for prolonged periods of time. This was achieved through the conditional expression of a transgene for chlorotoxin (Cltx) in the LC of adult mice. Chlorotoxin is a component of scorpion venom that partially blocks small conductance chloride channels. In this manner, the influence of GABAergic and glycinergic inhibitory inputs on LC cells is greatly reduced, while their ability to respond to excitatory inputs is unaffected. We demonstrate that the unilateral induction of Cltx expression in the LC is associated with a concomitant ipsilateral increase in the expression of markers of noradrenergic activity in LC neurons. Moreover, LC disinhibition is associated with the ipsilateral induction of the immediate early gene NGFI-A in cortical and subcortical target areas. Unlike previous gain of function approaches, transgenic disinhibition of LC cells is highly selective and persists for at least several weeks. This method represents a powerful new tool to assess the long-term effects of LC activation and is potentially applicable to other neuronal systems.
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Affiliation(s)
- J Michael Salbaum
- The Neurosciences Institute, 10640 John J. Hopkins Drive, San Diego, CA 92121, USA.
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Zahniser NR, Doolen S. Chronic and acute regulation of Na+/Cl- -dependent neurotransmitter transporters: drugs, substrates, presynaptic receptors, and signaling systems. Pharmacol Ther 2001; 92:21-55. [PMID: 11750035 DOI: 10.1016/s0163-7258(01)00158-9] [Citation(s) in RCA: 219] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Na+/Cl- -dependent neurotransmitter transporters, which constitute a gene superfamily, are crucial for limiting neurotransmitter activity. Thus, it is critical to understand their regulation. This review focuses primarily on the norepinephrine transporter, the dopamine transporter, the serotonin transporter, and the gamma-aminobutyric acid transporter GAT1. Chronic administration of drugs that alter neurotransmitter release or inhibit transporter activity can produce persistent compensatory changes in brain transporter number and activity. However, regulation has not been universally observed. Transient alterations in norepinephrine transporter, dopamine transporter, serotonin transporter, and GAT1 function and/or number occur in response to more acute manipulations, including membrane potential changes, substrate exposure, ethanol exposure, and presynaptic receptor activation/inhibition. In many cases, acute regulation has been shown to result from a rapid redistribution of the transporter between the cell surface and intracellular sites. Second messenger systems involved in this rapid regulation include protein kinases and phosphatases, of which protein kinase C has been the best characterized. These signaling systems share the common characteristic of altering maximal transport velocity and/or cell surface expression, consistent with regulation of transporter trafficking. Although less well characterized, arachidonic acid, reactive oxygen species, and nitric oxide also alter transporter function. In addition to post-translational modifications, cytoskeleton interactions and transporter oligomerization regulate transporter activity and trafficking. Furthermore, promoter regions involved in transporter transcriptional regulation have begun to be identified. Together, these findings suggest that Na+/Cl- -dependent neurotransmitter transporters are regulated both long-term and in a more dynamic manner, thereby providing several distinct mechanisms for altering synaptic neurotransmitter concentrations and neurotransmission.
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Affiliation(s)
- N R Zahniser
- Department of Pharmacology, C-236, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, Denver, CO 80262, USA.
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Koed K, Linnet K. Opposing changes in serotonin and norepinephrine transporter mRNA levels after serotonin depletion. Eur Neuropsychopharmacol 2000; 10:501-9. [PMID: 11115741 DOI: 10.1016/s0924-977x(00)00121-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We and others have earlier shown that severe serotonin depletion leads to a compensatory down-regulation in the expression of the serotonin transporter (5HTT) gene. We have now investigated the expression of both the 5HTT and the norepinephrine transporter (NET) gene to assess the possible interaction between the noradrenergic and the serotonergic neurotransmitter systems. Acute severe serotonin depletion induced by p-chlorophenylalanine (PCPA) treatment leads to enhanced NET(Long) mRNA levels and reduced 5HTT mRNA level. This change in transporter mRNA expression was paralleled by a non-significant change in protein expression. Chronic severe serotonin depletion combined with treatment with the antidepressant imipramine leads to enhanced NET(Long) mRNA levels. Acute treatment with the monoamine oxidase A inhibitor clorgyline, acute moderate NE reduction (alpha-methyl-p-tyrosine treatment) or less severe depletion for 3 weeks have no effect on the gene expression of the transporters. Taken together, the present data demonstrate that the NET gene expression is enhanced in case of severe serotonin depletion.
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Affiliation(s)
- K Koed
- Institute for Basic Research in Psychiatry, Department of Biological Psychiatry, Psychiatric Hospital in Aarhus, The Aarhus University Hospital, Skovagervej 2, DK-8240, Risskov, Denmark.
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Habecker BA, Klein MG, Cox BC, Packard BA. Norepinephrine transporter expression in cholinergic sympathetic neurons: differential regulation of membrane and vesicular transporters. Dev Biol 2000; 220:85-96. [PMID: 10720433 DOI: 10.1006/dbio.2000.9631] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sympathetic neurons that undergo a noradrenergic to cholinergic change in phenotype provide a useful model system to examine the developmental regulation of proteins required to synthesize, store, or remove a particular neurotransmitter. This type of change occurs in the sympathetic sweat gland innervation during development and can be induced in cultured sympathetic neurons by extracts of sweat gland-containing footpads or by leukemia inhibitory factor. Sympathetic neurons initially produce norepinephrine (NE) and contain the vesicular monoamine transporter 2 (VMAT2), which packages NE into vesicles, and the norepinephrine transporter (NET), which removes NE from the synaptic cleft to terminate signaling. We have used a variety of biochemical and molecular techniques to test whether VMAT2 and NET levels decrease in sympathetic neurons which stop producing NE and make acetylcholine. In cultured sympathetic neurons, NET protein and mRNA decreased during the switch to a cholinergic phenotype but VMAT2 mRNA and protein did not decline. NET immunoreactivity disappeared from the developing sweat gland innervation in vivo as it acquired cholinergic properties. Surprisingly, NET simultaneously appeared in sweat gland myoepithelial cells. The presence of NET in myoepithelial cells did not require sympathetic innervation. VMAT2 levels did not decrease as the sweat gland innervation became cholinergic, indicating that NE synthesis and vesicular packaging are not coupled in this system. Thus, production of NE and the transporters required for noradrenergic transmission are not coordinately regulated during cholinergic development.
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Affiliation(s)
- B A Habecker
- Department of Physiology and Pharmacology, Oregon Health Sciences University, Portland, Oregon 97201-3098, USA.
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Shores MM, White SS, Veith RC, Szot P. Tyrosine hydroxylase mRNA is increased in old age and norepinephrine uptake transporter mRNA is decreased in middle age in locus coeruleus of Brown-Norway rats. Brain Res 1999; 826:143-7. [PMID: 10216207 DOI: 10.1016/s0006-8993(99)01200-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In normal aging, cell loss occurs in the locus coeruleus (LC), the major noradrenergic nucleus in the brain. This study examined changes in the LC of aged rats by measuring mRNA expression for tyrosine hydroxylase (TH) and the norepinephrine uptake transporter (NET). TH and NET mRNA expression were measured by in situ hybridization in young, middle-aged and aged rats. It appears that in middle age, the transporter system responds initially to LC cell loss by decreasing NET mRNA expression. Then, with further aging and cell loss, TH mRNA expression increases which may potentially increase NE synthesis in the remaining neurons. These findings suggest that multiple regulatory components are used to maintain stable noradrenergic synaptic levels despite neuronal loss. Published by Elsevier Science B.V.
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Affiliation(s)
- M M Shores
- Geriatric Research, Education and Clinical Center (GRECC), VA Puget Sound Health Care System, 1660 S. Columbian Way (182B), Seattle, WA 98195, USA.
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Shang Y, Boja JW, Dluzen DE. Castration differentially alters [3H]nisoxetine binding to norepinephrine uptake sites in olfactory bulb and frontal cortex of male rats. Synapse 1999; 31:250-5. [PMID: 10051105 DOI: 10.1002/(sici)1098-2396(19990315)31:4<250::aid-syn2>3.0.co;2-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In the present study, [3H]nisoxetine binding to norepinephrine (NE) uptake sites and [3H]norepinephrine uptake were investigated within olfactory bulb (OB) and frontal cortex homogenates from intact and castrated male rats. Statistically significant reductions in the number of [3H]nisoxetine binding sites (Bmax) were found in OB from the castrates, while significantly increased Bmax values were obtained in the frontal cortex. Castration also significantly altered the affinity (Kd) of [3H]nisoxetine binding in the frontal cortex, but not in the OB. Assessment of [3H]norepinephrine uptake showed that in neither brain regions were there any statistically significant differences in Km nor Vmax between the castrated and intact male rats, indicating that the basal uptake process is not changed following castration in either of these brain areas. These results demonstrate the differential effects of castration upon [3H]nisoxetine binding sites between the OB and frontal cortex. Such findings provide new evidence for one of the mechanisms by which androgens may modulate central noradrenergic activity.
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Affiliation(s)
- Y Shang
- Department of Anatomy, Northeastern Ohio Universities College of Medicine, Rootstown 44272-0095, USA
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Soto-Moyano R, Alarcon S, Hernández A, Pérez H, Ruiz S, Carreño P, Kusch C, Belmar J. Prenatal malnutrition-induced functional alterations in callosal connections and in interhemispheric asymmetry in rats are prevented by reduction of noradrenaline synthesis during gestation. J Nutr 1998; 128:1224-31. [PMID: 9649610 DOI: 10.1093/jn/128.7.1224] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Prenatal malnutrition results in increased concentration and release of central noradrenaline, a neurotransmitter that is an important regulator of normal regressive events such as axonal pruning and synaptic elimination. This suggests that some of the functional disturbances in brain induced by prenatal malnutrition could be due at least in part to increased noradrenaline activity that may enhance regressive events during early stages of development. To test this hypothesis we studied whether chronic administration of alpha-methyl-p-tyrosine, an inhibitor of tyrosine hydroxylase, to rats during gestation might prevent long-term deleterious effects of prenatal malnutrition on functional properties of interhemispheric connections of the visual cortex, and on asymmetry of visual evoked responses. The experiments were conducted on normal and malnourished rats 45-50 d of age. Prenatal malnutrition was induced by restricting the food consumption of pregnant rats to 40%, from d 8 postconception to parturition. At birth, prenatally malnourished rats had significantly greater whole-brain noradrenaline concentration as well as significantly enhanced noradrenaline release in the visual cortex. At 45-50 d of age, the malnourished group had a significantly smaller cortical area, exhibiting transcallosal evoked responses; in addition, the amplitude of these responses was significantly smaller. Malnourished rats showed a significant reduction of the normal interhemispheric asymmetry of visual evoked responses. The addition of 0.3% alpha-methyl-p-tyrosine to the diet of malnourished pregnant rats during the last 2 wk of gestation prevented functional disorders induced in the offspring by prenatal malnutrition on interhemispheric connectivity of visual areas and on interhemispheric bioelectrical asymmetry, probably by reducing the elevated brain noradrenaline activity and thereby restoring the normal trophic role of this neurotransmitter.
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Affiliation(s)
- R Soto-Moyano
- Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Casilla 138-11, Santiago, Chile
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