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Sample records for downregulates dopamine synthesis

  1. Evidence That Sleep Deprivation Downregulates Dopamine D2R in Ventral Striatum in the Human Brain

    SciTech Connect

    Volkow N. D.; Fowler J.; Volkow, N.D.; Tomasi, D.; Wang, G.-J.; Fowler, J.S.; Logan, J.; Benveniste, H.; Kin, R.; Thanos, P.K.; Sergi F.

    2012-03-23

    Dopamine D2 receptors are involved with wakefulness, but their role in the decreased alertness associated with sleep deprivation is unclear. We had shown that sleep deprivation reduced dopamine D2/D3 receptor availability (measured with PET and [{sup 11}C]raclopride in controls) in striatum, but could not determine whether this reflected dopamine increases ([{sup 11}C]raclopride competes with dopamine for D2/D3 receptor binding) or receptor downregulation. To clarify this, we compared the dopamine increases induced by methylphenidate (a drug that increases dopamine by blocking dopamine transporters) during sleep deprivation versus rested sleep, with the assumption that methylphenidate's effects would be greater if, indeed, dopamine release was increased during sleep deprivation. We scanned 20 controls with [{sup 11}C]raclopride after rested sleep and after 1 night of sleep deprivation; both after placebo and after methylphenidate. We corroborated a decrease in D2/D3 receptor availability in the ventral striatum with sleep deprivation (compared with rested sleep) that was associated with reduced alertness and increased sleepiness. However, the dopamine increases induced by methylphenidate (measured as decreases in D2/D3 receptor availability compared with placebo) did not differ between rested sleep and sleep deprivation, and were associated with the increased alertness and reduced sleepiness when methylphenidate was administered after sleep deprivation. Similar findings were obtained by microdialysis in rodents subjected to 1 night of paradoxical sleep deprivation. These findings are consistent with a downregulation of D2/D3 receptors in ventral striatum with sleep deprivation that may contribute to the associated decreased wakefulness and also corroborate an enhancement of D2 receptor signaling in the arousing effects of methylphenidate in humans.

  2. Normative data of dopaminergic neurotransmission functions in substantia nigra measured with MRI and PET: Neuromelanin, dopamine synthesis, dopamine transporters, and dopamine D2 receptors.

    PubMed

    Ito, Hiroshi; Kawaguchi, Hiroshi; Kodaka, Fumitoshi; Takuwa, Hiroyuki; Ikoma, Yoko; Shimada, Hitoshi; Kimura, Yasuyuki; Seki, Chie; Kubo, Hitoshi; Ishii, Shiro; Takano, Harumasa; Suhara, Tetsuya

    2017-09-01

    The central dopaminergic system is of major importance in the pathophysiology of Parkinson's disease, schizophrenia, and other neuropsychiatric disorders. In the present study, the normative data of dopaminergic neurotransmission functions in the midbrain, consisting of neuromelanin, dopamine synthesis, dopamine transporters and dopamine D2 receptors, were constructed using magnetic resonance (MR) imaging and positron emission tomography (PET). PET studies with L-[β-(11)C]DOPA, [(18)F]FE-PE2I and [(11)C]FLB457 and MRI studies were performed on healthy young men. Neuromelanin accumulation measured by MRI was compared with dopaminergic functions, dopamine synthesis capacity, dopamine transporter binding and dopamine D2 receptor binding measured by PET in the substantia nigra. Although neuromelanin is synthesized from DOPA and dopamine in dopaminergic neurons, neuromelanin accumulation did not correlate with dopamine synthesis capacity in young healthy subjects. The role of dopamine transporters in the substantia nigra is considered to be the transport of dopamine into neurons, and therefore dopamine transporter binding might be related to neuromelanin accumulation; however, no significant correlation was observed between them. A positive correlation between dopamine D2 receptor binding and neuromelanin accumulation was observed, indicating a feedback mechanism by dopaminergic autoreceptors. Discrepancies in regional distribution between neuromelanin accumulation and dopamine synthesis capacity, dopamine transporter binding or dopamine D2 receptor binding were observed in the substantia nigra. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Homeostatic mechanisms in dopamine synthesis and release: a mathematical model

    PubMed Central

    Best, Janet A; Nijhout, H Frederik; Reed, Michael C

    2009-01-01

    Background Dopamine is a catecholamine that is used as a neurotransmitter both in the periphery and in the central nervous system. Dysfunction in various dopaminergic systems is known to be associated with various disorders, including schizophrenia, Parkinson's disease, and Tourette's syndrome. Furthermore, microdialysis studies have shown that addictive drugs increase extracellular dopamine and brain imaging has shown a correlation between euphoria and psycho-stimulant-induced increases in extracellular dopamine [1]. These consequences of dopamine dysfunction indicate the importance of maintaining dopamine functionality through homeostatic mechanisms that have been attributed to the delicate balance between synthesis, storage, release, metabolism, and reuptake. Methods We construct a mathematical model of dopamine synthesis, release, and reuptake and use it to study homeostasis in single dopaminergic neuron terminals. We investigate the substrate inhibition of tyrosine hydroxylase by tyrosine, the consequences of the rapid uptake of extracellular dopamine by the dopamine transporters, and the effects of the autoreceoptors on dopaminergic function. The main focus is to understand the regulation and control of synthesis and release and to explicate and interpret experimental findings. Results We show that the substrate inhibition of tyrosine hydroxylase by tyrosine stabilizes cytosolic and vesicular dopamine against changes in tyrosine availability due to meals. We find that the autoreceptors dampen the fluctuations in extracellular dopamine caused by changes in tyrosine hydroxylase expression and changes in the rate of firing. We show that short bursts of action potentials create significant dopamine signals against the background of tonic firing. We explain the observed time courses of extracellular dopamine responses to stimulation in wild type mice and mice that have genetically altered dopamine transporter densities and the observed half-lives of extracellular

  4. Relationship of striatal dopamine synthesis capacity to age and cognition.

    PubMed

    Braskie, Meredith N; Wilcox, Claire E; Landau, Susan M; O'Neil, James P; Baker, Suzanne L; Madison, Cindee M; Kluth, Jennifer T; Jagust, William J

    2008-12-24

    Past research has demonstrated that performance on frontal lobe-dependent tasks is associated with dopamine system integrity and that various dopamine system deficits occur with aging. The positron emission tomography (PET) radiotracer 6-[(18)F]fluoro-l-m-tyrosine (FMT) is a substrate of the dopamine-synthesizing enzyme, aromatic amino acid decarboxylase (AADC). Studies using 6-[(18)F]fluorodopa (FDOPA) (another AADC substrate) to measure how striatal PET signal and age relate have had inconsistent outcomes. The varying results occur in part from tracer processing that renders FDOPA signal subject to aspects of postrelease metabolism, which may themselves change with aging. In contrast, FMT remains a purer measure of AADC function. We used partial volume-corrected FMT PET scans to measure age-related striatal dopamine synthesis capacity in 21 older (mean, 66.9) and 16 younger (mean, 22.8) healthy adults. We also investigated how striatal FMT signal related to a cognitive measure of frontal lobe function. Older adults showed significantly greater striatal FMT signal than younger adults. Within the older group, FMT signal in dorsal caudate (DCA) and dorsal putamen was greater with age, suggesting compensation for deficits elsewhere in the dopamine system. In younger adults, FMT signal in DCA was lower with age, likely related to ongoing developmental processes. Younger adults who performed worse on tests of frontal lobe function showed greater FMT signal in right DCA, independent of age effects. Our data suggest that higher striatal FMT signal represents nonoptimal dopamine processing. They further support a relationship between striatal dopamine processing and frontal lobe cognitive function.

  5. Synthesis and in vitro studies on a potential dopamine prodrug.

    PubMed

    Giannola, L I; De Caro, V; Giandalia, G; Siragusa, M G; Lamartina, L

    2008-10-01

    Dopamine delivery to the central nervous system (CNS) undergoes the permeability limitations of blood-brain barrier (BBB) which is a selective interface that excludes most water-soluble molecules from entering the brain. Neutral amino acids permeate the BBB by specific transport systems. Condensation of dopamine with neutral amino acids could afford potential prodrugs able to interact with the BBB endogenous transporters and easily enter the brain. The synthesis and characterization of the dopamine derivative 2-amino-N-[2-(3,4-dihydroxy-phenyl)-ethyl]-3-phenyl-propionamide (7) is described. The chemical and enzymatic stability of 7 was evaluated. The molecular weight (300 Da) and Log Papp (0.76) indicated that the physico-chemical characteristics of compound 7 are adequate to cross biological membranes. Compound 7 was enzymatically cleaved to free dopamine in rat brain homogenate (t1/2 = 460 min). In human plasma, the t1/2 of 7 was estimated comparable to that reported for L-DOPA. In view of a possible oral administration of 7, studies of its chemical behavior under conditions simulating those of the gastrointestinal tract showed that no dopamine production occurred; furthermore, 7 is able to permeate through a simulated intestinal mucosal membrane. The collected data suggest that compound 7 could beconsidered a very valuable candidate for subsequent in vivo evaluation.

  6. Effects of Dopamine D2 Receptor Partial Agonist Antipsychotic Aripiprazole on Dopamine Synthesis in Human Brain Measured by PET with L-[β-11C]DOPA

    PubMed Central

    Ito, Hiroshi; Takano, Harumasa; Arakawa, Ryosuke; Takahashi, Hidehiko; Kodaka, Fumitoshi; Takahata, Keisuke; Nogami, Tsuyoshi; Suzuki, Masayuki; Suhara, Tetsuya

    2012-01-01

    Dopamine D2 receptor partial agonist antipsychotic drugs can modulate dopaminergic neurotransmission as functional agonists or functional antagonists. The effects of antipsychotics on presynaptic dopaminergic functions, such as dopamine synthesis capacity, might also be related to their therapeutic efficacy. Positron emission tomography (PET) was used to examine the effects of the partial agonist antipsychotic drug aripiprazole on presynaptic dopamine synthesis in relation to dopamine D2 receptor occupancy and the resulting changes in dopamine synthesis capacity in healthy men. On separate days, PET studies with [11C]raclopride and L-[β-11C]DOPA were performed under resting condition and with single doses of aripiprazole given orally. Occupancy of dopamine D2 receptors corresponded to the doses of aripiprazole, but the changes in dopamine synthesis capacity were not significant, nor was the relation between dopamine D2 receptor occupancy and these changes. A significant negative correlation was observed between baseline dopamine synthesis capacity and changes in dopamine synthesis capacity by aripiprazole, indicating that this antipsychotic appears to stabilize dopamine synthesis capacity. The therapeutic effects of aripiprazole in schizophrenia might be related to such stabilizing effects on dopaminergic neurotransmission responsivity. PMID:23029533

  7. Autoregulation of dopamine synthesis in subregions of the rat nucleus accumbens.

    PubMed

    Heidbreder, C A; Baumann, M H

    2001-01-05

    The discovery of a core-shell dichotomy within the nucleus accumbens has opened new lines of investigation into the neuronal basis of psychiatric disorders and drug dependence. In the present study, the autoregulation of dopamine synthesis in subdivisions of the rat nucleus accumbens was examined. We measured the accumulation of L-3,4-dihydroxyphenylalanine (DOPA) after the inhibition of aromatic L-amino acid decarboxylase with 3-hydroxylbenzylhydrazine (NSD-1015, 100 mg kg(-1)) as an in vivo index of dopamine synthesis. The effect of the dopamine D(1)/D(2) receptor agonist apomorphine (0, 20, 100, 500 microgram kg(-1)) and the dopamine D(2)/D(3) receptor agonist quinpirole (0, 20, 100, 500 microgram kg(-1)) on dopamine synthesis was determined in the dorsolateral core, ventromedial shell, and rostral pole of the nucleus accumbens. DOPA accumulation was also measured in the frontal cortex, olfactory tubercle, and caudate nucleus of the same rats for comparative purposes. The results show that the three sectors of the nucleus accumbens had similar basal levels of DOPA. Both apomorphine and quinpirole produced a decrease in the dopamine synthesis rate in all brain regions examined. In general, the dopamine D(2)/D(3) receptor agonist quinpirole produced a significantly greater decrease in DOPA accumulation than the dopamine D(1)/D(2) receptor agonist apomorphine. Within the nucleus accumbens, we found no core-shell differences in the agonist-induced suppression of dopamine synthesis, but the rostral pole was less sensitive to the highest dose of both dopamine agonists. These results suggest that differences in dopamine function between the core and shell might not involve region-specific differences in the receptor-mediated autoregulation of dopamine neurotransmission. Moreover, the blunted effect of dopamine agonists in the rostral pole illustrates that this region of the accumbens is functionally distinct, possibly due to a lower dopamine receptor reserve when

  8. Azepino- and diazepinoindoles: synthesis and dopamine receptor binding profiles.

    PubMed

    Kraxner, J; Hübner, H; Gmeiner, P

    2000-09-01

    Starting from the readily available building blocks 7, 10, 11, and 15, the synthesis of the fused indoles 1, 2, 5, and 6, respectively, is reported. The syntheses involved Pictet-Spengler cyclizations, Michael addition reactions, lactamization, directed metallation, and reductive amination as the key reaction steps. Radioligand displacement studies comprising the dopamine receptor subtypes D1, D2long D2short, D3, and D4.4 were performed when the diazepinoindole 6 revealed D1 and D4 affinities (Ki = 0.11 microM and 1.7 microM, respectively) which are comparable to the partial D1 agonist SKF 38393 (3b). In contrast to the benzazepine 3b, the indole based test compounds turned out less selective over the D2 and D3 receptor subtype.

  9. Prefrontal dopamine regulates fear reinstatement through the downregulation of extinction circuits.

    PubMed

    Hitora-Imamura, Natsuko; Miura, Yuki; Teshirogi, Chie; Ikegaya, Yuji; Matsuki, Norio; Nomura, Hiroshi

    2015-07-30

    Prevention of relapses is a major challenge in treating anxiety disorders. Fear reinstatement can cause relapse in spite of successful fear reduction through extinction-based exposure therapy. By utilising a contextual fear-conditioning task in mice, we found that reinstatement was accompanied by decreased c-Fos expression in the infralimbic cortex (IL) with reduction of synaptic input and enhanced c-Fos expression in the medial subdivision of the central nucleus of the amygdala (CeM). Moreover, we found that IL dopamine plays a key role in reinstatement. A reinstatement-inducing reminder shock induced c-Fos expression in the IL-projecting dopaminergic neurons in the ventral tegmental area, and the blocking of IL D1 signalling prevented reduction of synaptic input, CeM c-Fos expression, and fear reinstatement. These findings demonstrate that a dopamine-dependent inactivation of extinction circuits underlies fear reinstatement and may explain the comorbidity of substance use disorders and anxiety disorders.

  10. Prefrontal dopamine regulates fear reinstatement through the downregulation of extinction circuits

    PubMed Central

    Hitora-Imamura, Natsuko; Miura, Yuki; Teshirogi, Chie; Ikegaya, Yuji; Matsuki, Norio; Nomura, Hiroshi

    2015-01-01

    Prevention of relapses is a major challenge in treating anxiety disorders. Fear reinstatement can cause relapse in spite of successful fear reduction through extinction-based exposure therapy. By utilising a contextual fear-conditioning task in mice, we found that reinstatement was accompanied by decreased c-Fos expression in the infralimbic cortex (IL) with reduction of synaptic input and enhanced c-Fos expression in the medial subdivision of the central nucleus of the amygdala (CeM). Moreover, we found that IL dopamine plays a key role in reinstatement. A reinstatement-inducing reminder shock induced c-Fos expression in the IL-projecting dopaminergic neurons in the ventral tegmental area, and the blocking of IL D1 signalling prevented reduction of synaptic input, CeM c-Fos expression, and fear reinstatement. These findings demonstrate that a dopamine-dependent inactivation of extinction circuits underlies fear reinstatement and may explain the comorbidity of substance use disorders and anxiety disorders. DOI: http://dx.doi.org/10.7554/eLife.08274.001 PMID:26226637

  11. Rapid substrate-induced down-regulation in function and surface localization of dopamine transporters: rat dorsal striatum versus nucleus accumbens

    PubMed Central

    Richards, Toni L.; Zahniser, Nancy R.

    2010-01-01

    The dopamine transporter (DAT) substrates dopamine, d-amphetamine (AMPH), and methamphetamine are known to rapidly and transiently reduce DAT activity and/or surface expression in dorsal striatum and heterologous expression systems. We sought to determine if similar substrate-induced regulation of DATs occurs in rat nucleus accumbens. In dorsal striatum synaptosomes, brief (15-min) in vitro substrate pre-exposure markedly decreased maximal [3H]dopamine uptake velocity whereas identical substrate pre-exposure in nucleus accumbens synaptosomes produced a smaller, non-significant reduction. However, 45 min after systemic AMPH administration, maximal ex vivo [3H]dopamine uptake velocity was significantly reduced in both brain regions. Protein kinase C inhibition blocked AMPH’s down-regulation of DAT activity. DAT synaptosomal surface expression was not modified following either the brief in vitro or in vivo AMPH pre-exposure but was reduced after a longer (1-h) in vitro pre-exposure in both brain regions. Together, our findings suggest that relatively brief substrate exposure results in greater down-regulation of DAT activity in dorsal striatum than in nucleus accumbens. Moreover, exposure to AMPH appears to regulate striatal dopamine transporters in a biphasic manner, with an initial protein kinase C-dependent decrease in DAT-mediated uptake velocity and then, with longer exposure, a reduction in DAT expression. PMID:19183252

  12. Rapid substrate-induced down-regulation in function and surface localization of dopamine transporters: rat dorsal striatum versus nucleus accumbens.

    PubMed

    Richards, Toni L; Zahniser, Nancy R

    2009-03-01

    The dopamine transporter (DAT) substrates dopamine, d-amphetamine (AMPH), and methamphetamine are known to rapidly and transiently reduce DAT activity and/or surface expression in dorsal striatum and heterologous expression systems. We sought to determine if similar substrate-induced regulation of DATs occurs in rat nucleus accumbens. In dorsal striatum synaptosomes, brief (15-min) in vitro substrate pre-exposure markedly decreased maximal [(3)H]dopamine uptake velocity whereas identical substrate pre-exposure in nucleus accumbens synaptosomes produced a smaller, non-significant reduction. However, 45 min after systemic AMPH administration, maximal ex vivo [(3)H]dopamine uptake velocity was significantly reduced in both brain regions. Protein kinase C inhibition blocked AMPH's down-regulation of DAT activity. DAT synaptosomal surface expression was not modified following either the brief in vitro or in vivo AMPH pre-exposure but was reduced after a longer (1-h) in vitro pre-exposure in both brain regions. Together, our findings suggest that relatively brief substrate exposure results in greater down-regulation of DAT activity in dorsal striatum than in nucleus accumbens. Moreover, exposure to AMPH appears to regulate striatal DATs in a biphasic manner, with an initial protein kinase C-dependent decrease in DAT-mediated uptake velocity and then, with longer exposure, a reduction in DAT surface expression.

  13. In vivo downregulation of protein synthesis in the snail Helix apersa during estivation.

    PubMed

    Pakay, Julian L; Withers, Philip C; Hobbs, Andrew A; Guppy, Michael

    2002-07-01

    Protein synthesis is downregulated during metabolic depression in a number of systems where the metabolic depression is effected by obvious extrinsic cues. The metabolic depression of the estivating land snail Helix apersa occurs in the absence of any obvious physiological stress and has an intrinsic component independent of temperature, pH, O(2) status, or osmolality. We show that this metabolic depression is accompanied by a downregulation of protein synthesis in vivo. The rate of protein synthesis decreases in two major tissues during estivation: to 23% and 53% of the awake rate in hepatopancreas and foot muscle, respectively. We show from calculations of the theoretical contribution of protein synthesis to total O(2) consumption that the depression of protein synthesis must be a significant, obligate, in vivo component of metabolic depression in H. aspersa.

  14. Tyrosine administration enhances dopamine synthesis and release in light-activated rat retina

    NASA Technical Reports Server (NTRS)

    Gibson, C. J.; Watkins, C. J.; Wurtman, R. J.

    1983-01-01

    Exposure of dark-adapted albino rats to light (350 lux) significantly elevated retinal levels of the dopamine metabolite dihydroxyphenyl acetic acid during the next hour; their return to a dark environment caused dihydroxyphenyl acetic acid levels to fall. Retinal dopamine levels were increased slightly by light exposure, suggesting that the increase in dihydroxyphenyl acetic acid reflected accelerated dopamine synthesis. Administration of tyrosine (100 mg/kg, i.p.) further elevated retinal dihydroxyphenyl acetic acid among light-exposed animals, but failed to affect dopamine release among animals in the dark. These observations show that a physiological stimulus - light exposure - can cause catecholaminergic neurons to become tyrosine-dependent; they also suggest that food consumption may affect neurotransmitter release within the retina.

  15. Strontium vanadate nanoribbons: Synthesis, characterization and detection of dopamine

    SciTech Connect

    Zhou, Qing; Shao, Mingwang; Chen, Tao; Xu, Hongyan

    2010-09-15

    Large-scale, high-purity and uniform strontium vanadate (Sr{sub 2}V{sub 2}O{sub 7}) nanoribbons were easily synthesized via a hydrothermal process without any surfactants. The as-prepared products were up to hundreds of micrometers in length, 200-600 nm in width, and 20 nm in thickness. These nanomaterials were employed to modify glassy carbon electrode, which displayed excellent electrochemical sensitivity in detecting dopamine in the presence of ascorbic acid. A linear relationship between the concentrations of dopamine and its oxidation peak currents was obtained. The modified electrode exhibited high reproducibility and stability, which might be found potential application in the biosensors.

  16. Ventral striatal prediction error signaling is associated with dopamine synthesis capacity and fluid intelligence.

    PubMed

    Schlagenhauf, Florian; Rapp, Michael A; Huys, Quentin J M; Beck, Anne; Wüstenberg, Torsten; Deserno, Lorenz; Buchholz, Hans-Georg; Kalbitzer, Jan; Buchert, Ralph; Bauer, Michael; Kienast, Thorsten; Cumming, Paul; Plotkin, Michail; Kumakura, Yoshitaka; Grace, Anthony A; Dolan, Raymond J; Heinz, Andreas

    2013-06-01

    Fluid intelligence represents the capacity for flexible problem solving and rapid behavioral adaptation. Rewards drive flexible behavioral adaptation, in part via a teaching signal expressed as reward prediction errors in the ventral striatum, which has been associated with phasic dopamine release in animal studies. We examined a sample of 28 healthy male adults using multimodal imaging and biological parametric mapping with (1) functional magnetic resonance imaging during a reversal learning task and (2) in a subsample of 17 subjects also with positron emission tomography using 6-[(18) F]fluoro-L-DOPA to assess dopamine synthesis capacity. Fluid intelligence was measured using a battery of nine standard neuropsychological tests. Ventral striatal BOLD correlates of reward prediction errors were positively correlated with fluid intelligence and, in the right ventral striatum, also inversely correlated with dopamine synthesis capacity (FDOPA K inapp). When exploring aspects of fluid intelligence, we observed that prediction error signaling correlates with complex attention and reasoning. These findings indicate that individual differences in the capacity for flexible problem solving relate to ventral striatal activation during reward-related learning, which in turn proved to be inversely associated with ventral striatal dopamine synthesis capacity.

  17. Dopamine as a Carbon Source: The Controlled Synthesis of Hollow Carbon Spheres and Yolk-Structured Carbon Nanocomposites

    SciTech Connect

    Dai, Sheng; Liu, Rui; Mahurin, Shannon Mark; Li, Chen; Unocic, Raymond R; Idrobo Tapia, Juan C; Gao, Hongjun; Pennycook, Stephen J

    2011-01-01

    A facile and versatile synthesis using dopamine as a carbon source gives hollow carbon spheres and yolk-shell Au{at}Carbon nanocomposites. The uniform nature of dopamine coatings and their high carbon yield endow the products with high structural integrity. The Au{at}C nanocomposites are catalytically active.

  18. Sonochemical synthesis of Ag nanoclusters: electrogenerated chemiluminescence determination of dopamine.

    PubMed

    Liu, Tao; Zhang, Lichun; Song, Hongjie; Wang, Zhonghui; Lv, Yi

    2013-01-01

    We report a facile one-pot sonochemical approach to preparing highly water-soluble Ag nanoclusters (NCs) using bovine serum albumin as a stabilizing agent and reducing agent in aqueous solution. Intensive electrogenerated chemiluminescence (ECL) was observed from the as-prepared Ag (NCs) and successfully applied for the ECL detection of dopamine with high sensitivity and a wide detection range. A possible ECL mechanism is proposed for the preparation of Ag NCs. With this method, the dopamine concentration was determined in the range of 8.3 × 10(-9) to 8.3 × 10(-7) mol/L without the obvious interference of uric acid, ascorbic acid and some other neurotransmitters, such as serotonin, epinephrine and norepinephrine, and the detection limit was 9.2 × 10(-10) mol/L at a signal/noise ratio of 3.

  19. Synthesis and characterization of Dopamine graft compound N-methacryloyl 3,4-dihydroxyl-phenylamine

    NASA Astrophysics Data System (ADS)

    Xiong, Xiong; Shu-xin, Qu; Yu-mei, Liu

    2013-03-01

    In order to obtain adhesive biomaterials inspired by mussels, the intermediate derivatives of dopamine, N-methacryloyl 3,4-dihydroxyl-phenylamine (dopamine methacryla-mide DMA), was synthesized by grafting methacrylate anhydride to dopamine. The structure of the compound was confirmed by fourier transform infrared spectroscopy and nuclear magnetic resonance. The thermal stability of DMA was also characterized by thermo gravimetric analysis and differential scanning calorimeters techniques. The surface morphology of DMA crystal was analysed by scanning electron microscope analyses. The present result showed that the synthesis of new monomers was successfully fulfilled and the new compounds retain the hydroxyl functional groups. The surface morphologies and thermal stability of DMA crystal were also altered by grafting reaction.

  20. Synthesis of dopamine in E. coli using plasmid-based expression system and its marked effect on host growth profiles.

    PubMed

    Das, Arunangshu; Verma, Anita; Mukherjee, Krishna J

    2017-09-14

    L-Dopa and dopamine are important pathway intermediates toward the synthesis of catecholamine such as epinephrine and norepinephrine from amino acid L-tyrosine. Dopamine, secreted from dopaminergic nerve cells, serves as an important neurotransmitter. We report the synthesis of dopamine by extending the aromatic amino acid pathway of Escherichia coli DH5α by the expression of 4-hydroxyphenylacetate-3-hydrolase (HpaBC) from E. coli and an engineered dopa decarboxylase (DDC) from pig kidney cell. The activity of HpaBC and DDC require 200 µM iron supplementation and 50 µM vitamin B6, respectively as additives to the growth media. The maximum concentration of L-dopa and dopamine obtained from the broth was around 26 and 27 mg/L after 24 hr of separate shake flask studies. We observed that in the presence of dopamine synthesized in vivo host growth was remarkably enhanced. These observations lead us to an interesting finding about the role of these catecholamines on bacterial growth. It is clear that synthesis of dopamine in vivo actually promotes growth much efficiently as compared to when dopamine is added to the system from outside. From HPLC and GC-MS data it was further observed that L-dopa was stable within the observable time of experiments whereas dopamine actually was subjected to degradation via oxidation and host consumption.

  1. A potential benefit of albinism in Astyanax cavefish: downregulation of the oca2 gene increases tyrosine and catecholamine levels as an alternative to melanin synthesis.

    PubMed

    Bilandžija, Helena; Ma, Li; Parkhurst, Amy; Jeffery, William R

    2013-01-01

    Albinism, the loss of melanin pigmentation, has evolved in a diverse variety of cave animals but the responsible evolutionary mechanisms are unknown. In Astyanax mexicanus, which has a pigmented surface dwelling form (surface fish) and several albino cave-dwelling forms (cavefish), albinism is caused by loss of function mutations in the oca2 gene, which operates during the first step of the melanin synthesis pathway. In addition to albinism, cavefish have evolved differences in behavior, including feeding and sleep, which are under the control of the catecholamine system. The catecholamine and melanin synthesis pathways diverge after beginning with the same substrate, L-tyrosine. Here we describe a novel relationship between the catecholamine and melanin synthesis pathways in Astyanax. Our results show significant increases in L-tyrosine, dopamine, and norepinephrine in pre-feeding larvae and adult brains of Pachón cavefish relative to surface fish. In addition, norepinephrine is elevated in cavefish adult kidneys, which contain the teleost homologs of catecholamine synthesizing adrenal cells. We further show that the oca2 gene is expressed during surface fish development but is downregulated in cavefish embryos. A key finding is that knockdown of oca2 expression in surface fish embryos delays the development of pigmented melanophores and simultaneously increases L-tyrosine and dopamine. We conclude that a potential evolutionary benefit of albinism in Astyanax cavefish may be to provide surplus L-tyrosine as a precursor for the elevated catecholamine synthesis pathway, which could be important for adaptation to the challenging cave environment.

  2. A Potential Benefit of Albinism in Astyanax Cavefish: Downregulation of the oca2 Gene Increases Tyrosine and Catecholamine Levels as an Alternative to Melanin Synthesis

    PubMed Central

    Parkhurst, Amy; Jeffery, William R.

    2013-01-01

    Albinism, the loss of melanin pigmentation, has evolved in a diverse variety of cave animals but the responsible evolutionary mechanisms are unknown. In Astyanax mexicanus, which has a pigmented surface dwelling form (surface fish) and several albino cave-dwelling forms (cavefish), albinism is caused by loss of function mutations in the oca2 gene, which operates during the first step of the melanin synthesis pathway. In addition to albinism, cavefish have evolved differences in behavior, including feeding and sleep, which are under the control of the catecholamine system. The catecholamine and melanin synthesis pathways diverge after beginning with the same substrate, L-tyrosine. Here we describe a novel relationship between the catecholamine and melanin synthesis pathways in Astyanax. Our results show significant increases in L-tyrosine, dopamine, and norepinephrine in pre-feeding larvae and adult brains of Pachón cavefish relative to surface fish. In addition, norepinephrine is elevated in cavefish adult kidneys, which contain the teleost homologs of catecholamine synthesizing adrenal cells. We further show that the oca2 gene is expressed during surface fish development but is downregulated in cavefish embryos. A key finding is that knockdown of oca2 expression in surface fish embryos delays the development of pigmented melanophores and simultaneously increases L-tyrosine and dopamine. We conclude that a potential evolutionary benefit of albinism in Astyanax cavefish may be to provide surplus L-tyrosine as a precursor for the elevated catecholamine synthesis pathway, which could be important for adaptation to the challenging cave environment. PMID:24282555

  3. The monoamine stabilizer (-)-OSU6162 counteracts downregulated dopamine output in the nucleus accumbens of long-term drinking Wistar rats.

    PubMed

    Feltmann, Kristin; Fredriksson, Ida; Wirf, Malin; Schilström, Björn; Steensland, Pia

    2016-03-01

    We recently established that the monoamine stabilizer (-)-OSU6162 (OSU6162) decreased voluntary alcohol-mediated behaviors, including alcohol intake and cue/priming-induced reinstatement, in long-term drinking rats, while blunting alcohol-induced dopamine output in the nucleus accumbens (NAc) of alcohol-naïve rats. Therefore, we hypothesized that OSU6162 attenuates alcohol-mediated behaviors by blunting alcohol's rewarding effects. Here, we evaluated the effects of long-term drinking and OSU6162 treatment (30 mg/kg, sc) on basal and alcohol-induced (2.5 g/kg, ip) NAc dopamine outputs in Wistar rats after 10 months of intermittent access to 20% alcohol. The results showed that basal and alcohol-induced NAc dopamine outputs were significantly lower in long-term drinking rats, compared with alcohol-naïve rats. In the long-term drinking rats, OSU6162 slowly increased and maintained the dopamine output significantly elevated compared with baseline for at least 4 hours. Furthermore, OSU6162 pre-treatment did not blunt the alcohol-induced output in the long-term drinking rats, a finding that contrasted with our previous results in alcohol-naïve rats. Finally, OSU6162 did not induce conditioned place preference (CPP) in either long-term drinking or alcohol-naïve rats, indicating that OSU6162 has no reinforcing properties. To verify that the CPP results were not due to memory acquisition impairment, we demonstrated that OSU6162 did not affect novel object recognition. In conclusion, these results indicate that OSU6162 attenuates alcohol-mediated behaviors by counteracting NAc dopamine deficits in long-term drinking rats and that OSU6162 is not rewarding on its own. Together with OSU6162's beneficial side-effect profile, the present study merits evaluation of OSU6162's clinical efficacy to attenuate alcohol use in alcohol-dependent patients. © 2015 The Authors.Addiction Biology published by John Wiley & Sons Ltd on behalf of Society for the Study of Addiction.

  4. Dipeptides Inhibit Melanin Synthesis in Mel-Ab Cells through Down-Regulation of Tyrosinase

    PubMed Central

    Lee, Hyun-e; Kim, Eun-Hyun; Choi, Hye-Ryung; Sohn, Uy Dong; Yun, Hye-Young; Baek, Kwang Jin; Kwon, Nyoun Soo; Park, Kyoung-Chan

    2012-01-01

    This study investigated the effects of proline-serine (PS) and valine-serine (VS) dipeptides on melanogenesis in Mel-Ab cells. Proline-serine and VS significantly inhibited melanin synthesis in a concentration-dependent manner, though neither dipeptide directly inhibited tyrosinase activity in a cell-free system. Both PS and VS down-regulated the expression of microphthalmia-associated transcription factor (MITF) and tyrosinase. In a follow-up study also described here, the effects of these dipeptides on melanogenesis-related signal transduction were quantified. Specifically, PS and VS induced ERK phosphorylation, though they had no effect on phosphorylation of the cAMP response element binding protein (CREB). These data suggest that PS and VS inhibit melanogenesis through ERK phosphorylation and subsequent down-regulation of MITF and tyrosinase. Properties of these dipeptides are compatible with application as skin-whitening agents. PMID:22915995

  5. Chromatographic assay to study the activity of multiple enzymes involved in the synthesis and metabolism of dopamine and serotonin.

    PubMed

    Morgan, Lindsay D; Baker, Hannah; Yeoman, Mark S; Patel, Bhavik Anil

    2012-03-21

    Serotonin and dopamine are crucial regulators of signalling in the peripheral and central nervous systems. We present an ex-vivo, isocratic chromatographic method that allows for the measurement of tyrosine, L-3,4-dihydroxyphenylalanine (L-DOPA), dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC), tryptophan, 5-hydroxytryptophan (5-HTP), serotonin and 5-hydroxy-3-indoleacetic acid (5-HIAA) in a model central nervous (CNS) system, to study the role of key enzymes involved in the synthesis and metabolism of serotonin and dopamine. By utilising a sample splitting technique, we could test a single CNS sample at multiple time points under various pharmacological treatments. In, addition, we were able to conduct this assay by utilising the endogenous biochemical components of the CNS to study the synthesis and metabolism of serotonin and dopamine, negating the requirement of additional enzyme activators or stabilisers in the biological matrix. Finally we utilised NSD-1015, an aromatic amino acid decarboxylase enzyme inhibitor used to study the synthesis of dopamine and serotonin to monitor alterations in levels of key neurochemicals. 3-hydroxybenzylhydrazine dihydrochloride (NSD-1015) was able to reduce levels of serotonin and dopamine, whilst elevating precursors L-DOPA and 5-HTP.

  6. Triiodothyronine (T3) inhibits hyaluronate synthesis in a human dermal equivalent by downregulation of HAS2.

    PubMed

    Pouyani, Tara; Sadaka, Basma H; Papp, Suzanne; Schaffer, Lana

    2013-03-01

    Triiodothyronine (T3) is a thyroid hormone that can have varying effects on skin. In order to assess the effects of T3 on the human dermis, we prepared dermal equivalents using neonatal dermal cells via the process of self-assembly in the presence of differing concentrations of T3. These dermal equivalents were prepared in the absence of serum and a three dimensional matrix allowing for the direct assessment of different concentrations of T3 on dermal extracellular matrix formation. Three different concentrations of T3 were chosen, 20 pM, which is part of the base medium, 0.2 nM T3 and 2 nM T3. We find that self-assembled dermal equivalents formed under these conditions show a progressive "thinning" with increasing T3 concentrations. While we observed no change in total collagen content, inhibition of hyaluronate (HA) synthesis was observed in the 0.2- and 2-nM T3 constructs as compared to the 20-pM construct. Other glycosaminoglycan synthesis was not affected by increasing T3 concentrations. In order to identify the gene(s) responsible for inhibition of HA synthesis in the 2-nM T3 dermal equivalent, we conducted a differential gene array analysis. The results of these experiments demonstrate the differential expression of 40 genes, of these, 34 were upregulated and 6 genes were downregulated. The results from these experiments suggest that downregulation of HAS2 may be responsible for inhibition of hyaluronate synthesis in the self-assembled 2-nM T3 human dermal matrix.

  7. Zeolitic imidazolate framework-8 (ZIF-8) as a sacrificial template: one-pot synthesis of hollow poly(dopamine) nanocapsules and yolk-structured poly(dopamine) nanocomposites

    NASA Astrophysics Data System (ADS)

    Ran, Jingyu; Xiao, Lihua; Wu, Weidang; Liu, Yike; Qiu, Wei; Wu, Jianming

    2017-02-01

    Hollow poly(dopamine) (PDA) nanocapsules and yolk-structured PDA nanocomposites were prepared by an aqueous one-pot synthesis method utilizing zeolitic imidazolate framework-8 (ZIF-8) nanocrystals as a sacrificial template without any special etchant. The resulting PDA nanocapsules show negligible cytotoxicity in HeLa cells after incubation for 48 h at various doses, which implies their potential as candidates for practical applications in drug transport and targeting.

  8. Zeolitic imidazolate framework-8 (ZIF-8) as a sacrificial template: one-pot synthesis of hollow poly(dopamine) nanocapsules and yolk-structured poly(dopamine) nanocomposites.

    PubMed

    Ran, Jingyu; Xiao, Lihua; Wu, Weidang; Liu, Yike; Qiu, Wei; Wu, Jianming

    2017-02-03

    Hollow poly(dopamine) (PDA) nanocapsules and yolk-structured PDA nanocomposites were prepared by an aqueous one-pot synthesis method utilizing zeolitic imidazolate framework-8 (ZIF-8) nanocrystals as a sacrificial template without any special etchant. The resulting PDA nanocapsules show negligible cytotoxicity in HeLa cells after incubation for 48 h at various doses, which implies their potential as candidates for practical applications in drug transport and targeting.

  9. Downregulation of de Novo Fatty Acid Synthesis in Subcutaneous Adipose Tissue of Moderately Obese Women

    PubMed Central

    Guiu-Jurado, Esther; Auguet, Teresa; Berlanga, Alba; Aragonès, Gemma; Aguilar, Carmen; Sabench, Fàtima; Armengol, Sandra; Porras, José Antonio; Martí, Andreu; Jorba, Rosa; Hernández, Mercè; del Castillo, Daniel; Richart, Cristóbal

    2015-01-01

    The purpose of this work was to evaluate the expression of fatty acid metabolism-related genes in human adipose tissue from moderately obese women. We used qRT-PCR and Western Blot to analyze visceral (VAT) and subcutaneous (SAT) adipose tissue mRNA expression involved in de novo fatty acid synthesis (ACC1, FAS), fatty acid oxidation (PPARα, PPARδ) and inflammation (IL6, TNFα), in normal weight control women (BMI < 25 kg/m2, n = 35) and moderately obese women (BMI 30–38 kg/m2, n = 55). In SAT, ACC1, FAS and PPARα mRNA expression were significantly decreased in moderately obese women compared to controls. The downregulation reported in SAT was more pronounced when BMI increased. In VAT, lipogenic-related genes and PPARα were similar in both groups. Only PPARδ gene expression was significantly increased in moderately obese women. As far as inflammation is concerned, TNFα and IL6 were significantly increased in moderate obesity in both tissues. Our results indicate that there is a progressive downregulation in lipogenesis in SAT as BMI increases, which suggests that SAT decreases the synthesis of fatty acid de novo during the development of obesity, whereas in VAT lipogenesis remains active regardless of the degree of obesity. PMID:26694359

  10. Downregulation of de Novo Fatty Acid Synthesis in Subcutaneous Adipose Tissue of Moderately Obese Women.

    PubMed

    Guiu-Jurado, Esther; Auguet, Teresa; Berlanga, Alba; Aragonès, Gemma; Aguilar, Carmen; Sabench, Fàtima; Armengol, Sandra; Porras, José Antonio; Martí, Andreu; Jorba, Rosa; Hernández, Mercè; del Castillo, Daniel; Richart, Cristóbal

    2015-12-16

    The purpose of this work was to evaluate the expression of fatty acid metabolism-related genes in human adipose tissue from moderately obese women. We used qRT-PCR and Western Blot to analyze visceral (VAT) and subcutaneous (SAT) adipose tissue mRNA expression involved in de novo fatty acid synthesis (ACC1, FAS), fatty acid oxidation (PPARα, PPARδ) and inflammation (IL6, TNFα), in normal weight control women (BMI < 25 kg/m², n = 35) and moderately obese women (BMI 30-38 kg/m², n = 55). In SAT, ACC1, FAS and PPARα mRNA expression were significantly decreased in moderately obese women compared to controls. The downregulation reported in SAT was more pronounced when BMI increased. In VAT, lipogenic-related genes and PPARα were similar in both groups. Only PPARδ gene expression was significantly increased in moderately obese women. As far as inflammation is concerned, TNFα and IL6 were significantly increased in moderate obesity in both tissues. Our results indicate that there is a progressive downregulation in lipogenesis in SAT as BMI increases, which suggests that SAT decreases the synthesis of fatty acid de novo during the development of obesity, whereas in VAT lipogenesis remains active regardless of the degree of obesity.

  11. Regulation of dopamine synthesis and release in striatal and prefrontal cortical brain slices

    SciTech Connect

    Wolf, M.E.

    1986-01-01

    Brain slices were used to investigate the role of nerve terminal autoreceptors in modulating dopamine (DA) synthesis and release in striatum and prefrontal cortex. Accumulation of dihydroxyphenylalanine (DOPA) was used as an index of tyrosine hydroxylation in vitro. Nomifensine, a DA uptake blocker, inhibited DOPA synthesis in striatal but not prefrontal slices. This effect was reversed by the DA antagonist sulpiride, suggesting it involved activation of DA receptors by elevated synaptic levels of DA. The autoreceptor-selective agonist EMD-23-448 also inhibited striatal but not prefrontal DOPA synthesis. DOPA synthesis was stimulated in both brain regions by elevated K/sup +/, however only striatal synthesis could be further enhanced by sulpiride. DA release was measured by following the efflux of radioactivity from brain slices prelabeled with (/sup 3/H)-DA. EMD-23-448 and apomorphine inhibited, while sulpiride enhanced, the K/sup +/-evoked overflow of radioactivity from both striatal and prefrontal cortical slices. These findings suggest that striatal DA nerve terminals possess autoreceptors which modulate tyrosine hydroxylation as well as autoreceptors which modulate release. Alternatively, one site may be coupled to both functions through distinct transduction mechanisms. In contrast, autoreceptors on prefrontal cortical terminals appear to regulate DA release but not DA synthesis.

  12. Midbrain dopamine neurons sustain inhibitory transmission using plasma membrane uptake of GABA, not synthesis

    PubMed Central

    Tritsch, Nicolas X; Oh, Won-Jong; Gu, Chenghua; Sabatini, Bernardo L

    2014-01-01

    Synaptic transmission between midbrain dopamine neurons and target neurons in the striatum is essential for the selection and reinforcement of movements. Recent evidence indicates that nigrostriatal dopamine neurons inhibit striatal projection neurons by releasing a neurotransmitter that activates GABAA receptors. Here, we demonstrate that this phenomenon extends to mesolimbic afferents, and confirm that the released neurotransmitter is GABA. However, the GABA synthetic enzymes GAD65 and GAD67 are not detected in midbrain dopamine neurons. Instead, these cells express the membrane GABA transporters mGAT1 (Slc6a1) and mGAT4 (Slc6a11) and inhibition of these transporters prevents GABA co-release. These findings therefore indicate that GABA co-release is a general feature of midbrain dopaminergic neurons that relies on GABA uptake from the extracellular milieu as opposed to de novo synthesis. This atypical mechanism may confer dopaminergic neurons the flexibility to differentially control GABAergic transmission in a target-dependent manner across their extensive axonal arbors. DOI: http://dx.doi.org/10.7554/eLife.01936.001 PMID:24843012

  13. Dopamine synthesis and D3 receptor activation in pancreatic β-cells regulates insulin secretion and intracellular [Ca(2+)] oscillations.

    PubMed

    Ustione, Alessandro; Piston, David W

    2012-11-01

    Pancreatic islets are critical for glucose homeostasis via the regulated secretion of insulin and other hormones. We propose a novel mechanism that regulates insulin secretion from β-cells within mouse pancreatic islets: a dopaminergic negative feedback acting on insulin secretion. We show that islets are a site of dopamine synthesis and accumulation outside the central nervous system. We show that both dopamine and its precursor l-dopa inhibit glucose-stimulated insulin secretion, and this inhibition correlates with a reduction in frequency of the intracellular [Ca(2+)] oscillations. We further show that the effects of dopamine are abolished by a specific antagonist of the dopamine receptor D3. Because the dopamine transporter and dopamine receptors are expressed in the islets, we propose that cosecretion of dopamine with insulin activates receptors on the β-cell surface. D3 receptor activation results in changes in intracellular [Ca(2+)] dynamics, which, in turn, lead to lowered insulin secretion. Because blocking dopaminergic negative feedback increases insulin secretion, expanding the knowledge of this pathway in β-cells might offer a potential new target for the treatment of type 2 diabetes.

  14. Dopamine Synthesis and D3 Receptor Activation in Pancreatic β-Cells Regulates Insulin Secretion and Intracellular [Ca2+] Oscillations

    PubMed Central

    Ustione, Alessandro

    2012-01-01

    Pancreatic islets are critical for glucose homeostasis via the regulated secretion of insulin and other hormones. We propose a novel mechanism that regulates insulin secretion from β-cells within mouse pancreatic islets: a dopaminergic negative feedback acting on insulin secretion. We show that islets are a site of dopamine synthesis and accumulation outside the central nervous system. We show that both dopamine and its precursor l-dopa inhibit glucose-stimulated insulin secretion, and this inhibition correlates with a reduction in frequency of the intracellular [Ca2+] oscillations. We further show that the effects of dopamine are abolished by a specific antagonist of the dopamine receptor D3. Because the dopamine transporter and dopamine receptors are expressed in the islets, we propose that cosecretion of dopamine with insulin activates receptors on the β-cell surface. D3 receptor activation results in changes in intracellular [Ca2+] dynamics, which, in turn, lead to lowered insulin secretion. Because blocking dopaminergic negative feedback increases insulin secretion, expanding the knowledge of this pathway in β-cells might offer a potential new target for the treatment of type 2 diabetes. PMID:22918877

  15. Histamine H3 receptor activation inhibits dopamine synthesis but not release or uptake in rat nucleus accumbens.

    PubMed

    Aquino-Miranda, Guillermo; Escamilla-Sánchez, Juan; González-Pantoja, Raúl; Bueno-Nava, Antonio; Arias-Montaño, José-Antonio

    2016-07-01

    We studied the effect of activating histamine H3 receptors (H3Rs) on rat nucleus accumbens (rNAcc) dopaminergic transmission by analyzing [(3)H]-dopamine uptake by synaptosomes, and dopamine synthesis and depolarization-evoked [(3)H]-dopamine release in slices. The uptake of [(3)H]-dopamine by rNAcc synaptosomes was not affected by the H3R agonist RAMH (10(-10)-10(-6) M). In rNAcc slices perfusion with RAMH (1 μM) had no significant effect on [(3)H]-dopamine release evoked by depolarization with 30 mM K(+) (91.4 ± 4.5% of controls). The blockade of dopamine D2 autoreceptors with sulpiride (1 μM) enhanced K(+)-evoked [(3)H]-dopamine release (168.8 ± 15.5% of controls), but under this condition RAMH (1 μM) also failed to affect [(3)H]-dopamine release. Dopamine synthesis was evaluated in rNAcc slices incubated with the l-dihydroxyphenylalanine (DOPA) decarboxylase inhibitor NSD-1015 (1 mM). Forskolin-induced DOPA accumulation (220.1 ± 10.4% of controls) was significantly reduced by RAMH (41.1 ± 6.5% and 43.5 ± 9.1% inhibition at 100 nM and 1 μM, respectively), and this effect was prevented by the H3R antagonist ciproxifan (10 μM). DOPA accumulation induced by preventing cAMP degradation with IBMX (iso-butyl-methylxantine, 1 mM) or by activating receptors for the vasoactive intestinal peptide (VIP)/pituitary adenylate cyclase-activating peptide (PACAP) with PACAP-27 (1 μM) was reduced (IBMX) or prevented (PACAP-27) by RAMH (100 nM). In contrast, DOPA accumulation induced by 8-Bromo-cAMP (1 mM) was not affected by RAMH (100 nM). These results indicate that in rNAcc H3Rs do not modulate dopamine uptake or release, but regulate dopamine synthesis by inhibiting cAMP formation and thus PKA activation. This article is part of the Special Issue entitled 'Histamine Receptors'.

  16. Dopamine D2-Receptor Antagonists Down-Regulate CYP1A1/2 and CYP1B1 in the Rat Liver

    PubMed Central

    Harkitis, P.; Lang, M. A.; Marselos, M.; Fotopoulos, A.; Albucharali, G.; Konstandi, M.

    2015-01-01

    Dopaminergic systems regulate the release of several hormones including growth hormone (GH), thyroid hormones, insulin, glucocorticoids and prolactin (PRL) that play significant roles in the regulation of various Cytochrome P450 (CYP) enzymes. The present study investigated the role of dopamine D2-receptor-linked pathways in the regulation of CYP1A1, CYP1A2 and CYP1B1 that belong to a battery of genes controlled by the Aryl Hydrocarbon Receptor (AhR) and play a crucial role in the metabolism and toxicity of numerous environmental toxicants. Inhibition of dopamine D2-receptors with sulpiride (SULP) significantly repressed the constitutive and benzo[a]pyrene (B[a]P)-induced CYP1A1, CYP1A2 and CYP1B expression in the rat liver. The expression of AhR, heat shock protein 90 (HSP90) and AhR nuclear translocator (ARNT) was suppressed by SULP in B[a]P-treated livers, whereas the AhRR expression was increased by the drug suggesting that the SULP-mediated repression of the CYP1 inducibility is due to inactivation of the AhR regulatory system. At signal transduction level, the D2-mediated down-regulation of constitutive CYP1A1/2 and CYP1B1 expression appears to be mediated by activation of the insulin/PI3K/AKT pathway. PRL-linked pathways exerting a negative control on various CYPs, and inactivation of the glucocorticoid-linked pathways that positively control the AhR-regulated CYP1 genes, may also participate in the SULP-mediated repression of both, the constitutive and induced CYP1 expression. The present findings indicate that drugs acting as D2-dopamine receptor antagonists can modify several hormone systems that regulate the expression of CYP1A1, CYP1A2 and CYP1B1, and may affect the toxicity and carcinogenicity outcome of numerous toxicants and pre-carcinogenic substances. Therefore, these drugs could be considered as a part of the strategy to reduce the risk of exposure to environmental pollutants and pre-carcinogens. PMID:26466350

  17. Royal jelly reduces melanin synthesis through down-regulation of tyrosinase expression.

    PubMed

    Han, Sang Mi; Yeo, Joo Hong; Cho, Yoon Hee; Pak, Sok Cheon

    2011-01-01

    For cosmetic reasons, the demand for effective and safe skin-whitening agents is high. Since the key enzyme in the melanin synthetic pathway is tyrosinase, many depigmenting agents in the treatment of hyperpigmentation act as tyrosinase inhibitors. In this study, we have investigated the hypo-pigmentary mechanism of royal jelly in a mouse melanocyte cell line, B16F1. Treatment of B16F1 cells with royal jelly markedly inhibited melanin biosynthesis in a dose-dependent manner. Decreased melanin content occurred through the decrease of tyrosinase activity. The mRNA levels of tyrosinase were also reduced by royal jelly. These results suggest that royal jelly reduces melanin synthesis by down-regulation of tyrosinase mRNA transcription and serves as a new candidate in the design of new skin-whitening or therapeutic agents.

  18. Additional nitrogen fertilization at heading time of rice down-regulates cellulose synthesis in seed endosperm.

    PubMed

    Midorikawa, Keiko; Kuroda, Masaharu; Terauchi, Kaede; Hoshi, Masako; Ikenaga, Sachiko; Ishimaru, Yoshiro; Abe, Keiko; Asakura, Tomiko

    2014-01-01

    The balance between carbon and nitrogen is a key determinant of seed storage components, and thus, is of great importance to rice and other seed-based food crops. To clarify the influence of the rhizosphere carbon/nitrogen balance during the maturation stage of several seed components, transcriptome analysis was performed on the seeds from rice plants that were provided additional nitrogen fertilization at heading time. As a result, it was assessed that genes associated with molecular processes such as photosynthesis, trehalose metabolism, carbon fixation, amino acid metabolism, and cell wall metabolism were differentially expressed. Moreover, cellulose and sucrose synthases, which are involved in cellulose synthesis, were down-regulated. Therefore, we compared cellulose content of mature seeds that were treated with additional nitrogen fertilization with those from control plants using calcofluor staining. In these experiments, cellulose content in endosperm from plants receiving additional nitrogen fertilization was less than that in control endosperm. Other starch synthesis-related genes such as starch synthase 1, starch phosphorylase 2, and branching enzyme 3 were also down-regulated, whereas some α-amylase and β-amylase genes were up-regulated. On the other hand, mRNA expression of amino acid biosynthesis-related molecules was up-regulated. Moreover, additional nitrogen fertilization caused accumulation of storage proteins and up-regulated Cys-poor prolamin mRNA expression. These data suggest that additional nitrogen fertilization at heading time changes the expression of some storage substance-related genes and reduces cellulose levels in endosperm.

  19. A biochemical and functional protein complex involving dopamine synthesis and transport into synaptic vesicles.

    PubMed

    Cartier, Etienne A; Parra, Leonardo A; Baust, Tracy B; Quiroz, Marisol; Salazar, Gloria; Faundez, Victor; Egaña, Loreto; Torres, Gonzalo E

    2010-01-15

    Synaptic transmission depends on neurotransmitter pools stored within vesicles that undergo regulated exocytosis. In the brain, the vesicular monoamine transporter-2 (VMAT(2)) is responsible for the loading of dopamine (DA) and other monoamines into synaptic vesicles. Prior to storage within vesicles, DA synthesis occurs at the synaptic terminal in a two-step enzymatic process. First, the rate-limiting enzyme tyrosine hydroxylase (TH) converts tyrosine to di-OH-phenylalanine. Aromatic amino acid decarboxylase (AADC) then converts di-OH-phenylalanine into DA. Here, we provide evidence that VMAT(2) physically and functionally interacts with the enzymes responsible for DA synthesis. In rat striata, TH and AADC co-immunoprecipitate with VMAT(2), whereas in PC 12 cells, TH co-immunoprecipitates with the closely related VMAT(1) and with overexpressed VMAT(2). GST pull-down assays further identified three cytosolic domains of VMAT(2) involved in the interaction with TH and AADC. Furthermore, in vitro binding assays demonstrated that TH directly interacts with VMAT(2). Additionally, using fractionation and immunoisolation approaches, we demonstrate that TH and AADC associate with VMAT(2)-containing synaptic vesicles from rat brain. These vesicles exhibited specific TH activity. Finally, the coupling between synthesis and transport of DA into vesicles was impaired in the presence of fragments involved in the VMAT(2)/TH/AADC interaction. Taken together, our results indicate that DA synthesis can occur at the synaptic vesicle membrane, where it is physically and functionally coupled to VMAT(2)-mediated transport into vesicles.

  20. Effects of dopamine agonists bromocriptine, pergolide, cabergoline, and SKF-38393 on GDNF, NGF, and BDNF synthesis in cultured mouse astrocytes.

    PubMed

    Ohta, Kiyoe; Kuno, Sadako; Mizuta, Ikuko; Fujinami, Aya; Matsui, Hidehito; Ohta, Mitsuhiro

    2003-06-20

    We examined the stimulatory effects of the dopamine agonists bromocriptine, pergolide, cabergoline, and SKF-38393 on the synthesis and secretion of neurotrophic factors (nerve growth factor, NGF; brain-derived neurotrophic factor, BDNF; and glial cell line-derived neurotrophic factor, GDNF) in cultured mouse astrocytes, and clarified the role of dopamine D1 and D2 receptors in these effects. Bromocriptine, a D2 agonist, elevated NGF levels in the culture medium 6.8-fold vs. control, and significantly decreased GDNF and BDNF levels, at 24 h. Both pergolide, a D1/D2 agonist, and cabergoline, a D2/weak D1 agonist, rapidly elevated NGF and GDNF levels at 4-6 h, respectively to 21- and 1.5-fold, respectively, and 84- and 9-fold, respectively, of control levels at 24 h. SKF-38393, a D1 agonist, elevated NGF and GDNF levels to 20- and 2.8-fold of controls, respectively, at 24 h. Relative levels of NGF and GDNF mRNA detected by Northern blot analysis or semiquantitative reverse transcriptase-polymerase chain reaction confirmed that increases in levels of the 2 proteins in culture medium were due to overexpression as opposed to leakage from cells. Cabergoline rapidly increased GDNF mRNA expression at 4 h, producing a potent and long-lasting increase in GDNF levels. Bromocriptine significantly suppressed GDNF synthesis. These findings suggest that stimulation of dopamine D1 receptors may be required for GDNF synthesis and secretion, and that concurrent stimulation of dopamine D1 and D2 receptors may augment synthesis and secretion of NGF and GDNF. These dopamine agonists may play a role in neuronal survival by stimulating NGF and GDNF synthesis in the brain, and as drugs are good candidates as NGF and GDNF inducers.

  1. Circadian-related heteromerization of adrenergic and dopamine D₄ receptors modulates melatonin synthesis and release in the pineal gland.

    PubMed

    González, Sergio; Moreno-Delgado, David; Moreno, Estefanía; Pérez-Capote, Kamil; Franco, Rafael; Mallol, Josefa; Cortés, Antoni; Casadó, Vicent; Lluís, Carme; Ortiz, Jordi; Ferré, Sergi; Canela, Enric; McCormick, Peter J

    2012-01-01

    The role of the pineal gland is to translate the rhythmic cycles of night and day encoded by the retina into hormonal signals that are transmitted to the rest of the neuronal system in the form of serotonin and melatonin synthesis and release. Here we describe that the production of both melatonin and serotonin by the pineal gland is regulated by a circadian-related heteromerization of adrenergic and dopamine D₄ receptors. Through α(₁B)-D₄ and β₁-D₄ receptor heteromers dopamine inhibits adrenergic receptor signaling and blocks the synthesis of melatonin induced by adrenergic receptor ligands. This inhibition was not observed at hours of the day when D₄ was not expressed. These data provide a new perspective on dopamine function and constitute the first example of a circadian-controlled receptor heteromer. The unanticipated heteromerization between adrenergic and dopamine D₄ receptors provides a feedback mechanism for the neuronal hormone system in the form of dopamine to control circadian inputs.

  2. Aberrant Salience Is Related to Reduced Reinforcement Learning Signals and Elevated Dopamine Synthesis Capacity in Healthy Adults.

    PubMed

    Boehme, Rebecca; Deserno, Lorenz; Gleich, Tobias; Katthagen, Teresa; Pankow, Anne; Behr, Joachim; Buchert, Ralph; Roiser, Jonathan P; Heinz, Andreas; Schlagenhauf, Florian

    2015-07-15

    The striatum is known to play a key role in reinforcement learning, specifically in the encoding of teaching signals such as reward prediction errors (RPEs). It has been proposed that aberrant salience attribution is associated with impaired coding of RPE and heightened dopamine turnover in the striatum, and might be linked to the development of psychotic symptoms. However, the relationship of aberrant salience attribution, RPE coding, and dopamine synthesis capacity has not been directly investigated. Here we assessed the association between a behavioral measure of aberrant salience attribution, the salience attribution test, to neural correlates of RPEs measured via functional magnetic resonance imaging while healthy participants (n = 58) performed an instrumental learning task. A subset of participants (n = 27) also underwent positron emission tomography with the radiotracer [(18)F]fluoro-l-DOPA to quantify striatal presynaptic dopamine synthesis capacity. Individual variability in aberrant salience measures related negatively to ventral striatal and prefrontal RPE signals and in an exploratory analysis was found to be positively associated with ventral striatal presynaptic dopamine levels. These data provide the first evidence for a specific link between the constructs of aberrant salience attribution, reduced RPE processing, and potentially increased presynaptic dopamine function.

  3. The Design, Synthesis and Structure-Activity Relationship of Mixed Serotonin, Norepinephrine and Dopamine Uptake Inhibitors

    NASA Astrophysics Data System (ADS)

    Chen, Zhengming; Yang, Ji; Skolnick, Phil

    The evolution of antidepressants over the past four decades has involved the replacement of drugs with a multiplicity of effects (e.g., TCAs) by those with selective actions (i.e., SSRIs). This strategy was employed to reduce the adverse effects of TCAs, largely by eliminating interactions with certain neurotransmitters or receptors. Although these more selective compounds may be better tolerated by patients, selective drugs, specifically SSRIs, are not superior to older drugs in treating depressed patients as measured by response and remission rates. It may be an advantage to increase synaptic levels of both serotonin and norepinephrine, as in the case of dual uptake inhibitors like duloxetine and venlafaxine. An important recent development has been the emergence of the triple-uptake inhibitors (TUIs/SNDRIs), which inhibit the uptake of the three neurotransmitters most closely linked to depression: serotonin, norepinephrine, and dopamine. Preclinical studies and clinical trials indicate that a drug inhibiting the reuptake of all three of these neurotransmitters could produce more rapid onset of action and greater efficacy than traditional antidepressants. This review will detail the medicinal chemistry involved in the design, synthesis and discovery of mixed serotonin, norepinephrine and dopamine transporter uptake inhibitors.

  4. Synthesis and characterization of a series of chiral alkoxymethyl morpholine analogs as dopamine receptor 4 (D4R) antagonists

    PubMed Central

    Witt, Jonathan O.; McCollum, Andrea L.; Hurtado, Miguel A.; Huseman, Eric D.; Jeffries, Daniel E.; Temple, Kayla J.; Plumley, Hyekyung C.; Blobaum, Anna L.; Lindsley, Craig W.; Hopkins, Corey R.

    2017-01-01

    Herein, we report the synthesis and structure–activity relationship of a series of chiral alkoxymethyl morpholine analogs. Our efforts have culminated in the identification of (S)-2-(((6-chloropyridin-2-yl) oxy)methyl)-4-((6-fluoro-1H-indol-3-yl)methyl)morpholine as a novel potent and selective dopamine D4 receptor antagonist with selectivity against the other dopamine receptors tested (<10% inhibition at 1 µM against D1, D2L, D2S, D3, and D5). PMID:27080176

  5. Ventral striatal dopamine synthesis capacity is associated with individual differences in behavioral disinhibition

    PubMed Central

    Lawrence, Andrew D.; Brooks, David J.

    2014-01-01

    Pathological gambling, alongside addictive and antisocial disorders, forms part of a broad psychopathological spectrum of externalizing disorders, which share an underlying genetic vulnerability. The shared externalizing propensity is a highly heritable, continuously varying trait. Disinhibitory personality traits such as impulsivity and novelty seeking (NS) function as indicators of this broad shared externalizing tendency, which may reflect, at the neurobiological level, variation in the reactivity of dopaminergic (DAergic) brain reward systems centered on the ventral striatum (VS). Here, we examined whether individual differences in ventral striatal dopamine (DA) synthesis capacity were associated with individual variation in disinhibitory personality traits. Twelve healthy male volunteers underwent 6-[18F]Fluoro-L-DOPA (FDOPA) positron emission tomography (PET) scanning to measure striatal DA synthesis capacity, and completed a measure of disinhibited personality (NS). We found that levels of ventral, but not dorsal, striatal DA synthesis capacity were significantly correlated with inter-individual variation in disinhibitory personality traits, particularly a propensity for financial extravagance and irresponsibility. Our results are consistent with preclinical models of behavioral disinhibition and addiction proneness, and provide novel insights into the neurobiology of personality based vulnerability to pathological gambling and other externalizing disorders. PMID:24672449

  6. Part 1: synthesis of irreversible inhibitors of aldose reductase with subsequent development of a carbon-13 NMR protein probe. Part 2: synthesis of selenium analogs of dopamine as potential dopamine receptor agonists

    SciTech Connect

    Ares, J.J.

    1986-01-01

    Aldose reductase converts glucose into sorbitol using NADPH as a cofactor. Sorbitol accumulation in various tissues is believed to play a major role in the development of debilitating complications of diabetes; thus, much effort has been directed toward the preparation of aldose reductase inhibitors. Of the compounds prepared, the most active are the isothiocyanate and azide analogs of the reversible aldose reductase inhibitor alrestatin. The potency of the alrestatin isothiocyanate prompted the authors to examine the possibility that isothiocyanates enriched with carbon-13 could be used as carbon-13 NMR protein probes. Toward this end, a synthesis of carbon-13 enriched phenylisothiocyanate has been developed. This reagent has been successfully utilized to study peptides via carbon-13 NMR spectroscopy. Research in their laboratory over the years has focused on answering two fundamental questions regarding the interaction of dopamine with its receptor. First, can the concept of bioisosterism be applied to dopamine agonists. Secondly, what is the actual molecular species of dopamine which interacts with the dopamine receptor. In an effort to answer these questions, methyl selenide and dimethyl selenonium analogs of dopamine have been synthesized.

  7. Stimulation of dopamine synthesis and activation of tyrosine hydroxylase by phorbol diesters in rat striatum

    SciTech Connect

    Onali, P.; Olianas, M.C.

    1987-03-23

    In rat striatal synaptosomes, 4..beta..-phorbol 12-myristate 13-acetate (PMA) and 4 ..beta..-phorbol 12,13-dibutyrate (PDBu), two activators of Ca/sup 2 +/-phospholipid-dependent protein kinase (protein kinase C) increased dopamine (DA) synthesis measured by following the release of /sup 14/CO/sub 2/ from L-(1-/sup 14/C) tyrosine. Maximal stimulation (21-28% increase of basal rate) was produced by 0.5 ..mu..M PMA and 1 ..mu..M PDBu. 4 ..beta..-Phorbol and 4 ..beta..-phorbol 13-acetate, which are not activators of protein kinase C, were ineffective at 1 ..mu..M. PMA did not change the release of /sup 14/CO/sub 2/ from L-(1-/sup 14/C)DOPA. Addition of 1 mM EGTA to a Ca/sup 2 +/-free incubation medium failed to affect PMA stimulation. KCl (60 mM) enhanced DA synthesis by 25%. Exposure of synaptosomes to either PMA or PDBu prior to KCl addition resulted in a more than additive increase (80-100%) of DA synthesis. A similar synergistic effect was observed when the phorbol diesters were combined with either veratridine or d-amphetamine but not with forskolin and dibutyryl cyclic AMP. Pretreatment of striatal synaptosomes with phorbol diesters produced an activation of tyrosine hydroxylase (TH) associated with a 60% increase of the Vmax and a decrease of the Km for the pterine cofactor 6-methyl-5,6,7,8-tetrahydropterin. These results indicate that protein kinase C participates in the regulation of striatal TH in situ and that its activation may act synergistically with DA releasing agents in stimulating DA synthesis. 37 references, 3 figures, 3 tables.

  8. Perturbations in dopamine synthesis lead to discrete physiological effects and impact oxidative stress response in Drosophila

    PubMed Central

    Hanna, Marley E.; Bednár̂ová, Andrea; Rakshit, Kuntol; Chaudhuri, Anathbandhu; O’Donnell, Janis M.; Krishnan, Natraj

    2015-01-01

    The impact of mutations in four essential genes involved in dopamine (DA) synthesis and transport on longevity, motor behavior, and resistance to oxidative stress was monitored in Drosophila melanogaster. The fly lines used for this study were: (i) a loss of function mutation in Catecholamines up (Catsup26), which is a negative regulator of the rate limiting enzyme for DA synthesis, (ii) a mutant for the gene pale (ple2) that encodes for the rate limiting enzyme tyrosine hydroxylase (TH), (iii) a mutant for the gene Punch (PuZ22) that encodes guanosine triphosphate cyclohydrolase, required for TH activity, and (iv) a mutant in the vesicular monoamine transporter (VMATΔ14), which is required for packaging of DA as vesicles inside DA neurons. Median lifespans of ple2, PuZ22 and VMATΔ14 mutants were significantly decreased compared to Catsup26 and wild type controls that did not significantly differ between each other. Catsup26 flies survived longer when exposed to hydrogen peroxide (80 μM) or paraquat (10 mM) compared to ple2, PuZ22 or VMATΔ14 and controls. These flies also exhibited significantly higher negative geotaxis activity compared to ple2, PuZ22, VMATΔ14 and controls. All mutant flies demonstrated rhythmic circadian locomotor activity in general, albeit Catsup26 and VMATΔ14 flies had slightly weaker rhythms. Expression analysis of some key antioxidant genes revealed that glutathione S-transferase Omega-1 (GSTO1) expression was significantly up-regulated in all DA synthesis pathway mutants and especially in Catsup26 and VMATΔ14 flies at both mRNA and protein levels. Taken together, we hypothesize that DA could directly influence GSTO1 transcription and thus play a significant role in the regulation of response to oxidative stress. Additionally, perturbations in DA synthesis do not appear to have a significant impact on circadian locomotor activity rhythms per se, but do have an influence on general locomotor activity levels. PMID:25585352

  9. Sodium-dependence and ouabain-sensitivity of the synthesis of dopamine in renal tissues of the rat.

    PubMed Central

    Soares-da-Silva, P.; Fernandes, M. H.

    1992-01-01

    1. The present study has examined the influence of sodium chloride (0-160 mM) and ouabain (100 and 500 microM), an inhibitor of the enzyme Na(+)-K+ ATPase, on the synthesis of dopamine in slices of rat renal cortex loaded with exogenous L-dihydroxyphenylalanine (L-DOPA). The deamination of newly-formed dopamine into 3,4-dihydroxyphenylacetic acid (DOPAC) was also examined. The assay of L-DOPA, dopamine and DOPAC in kidney slices was performed by high performance liquid chromatography (h.p.l.c.) with electrochemical detection. 2. The accumulation of newly-formed dopamine and DOPAC in kidney slices loaded with L-DOPA (50 and 100 microM) was found to be dependent on the concentration of NaCl in the medium. A similar picture could be observed for DOPAC. The fractional rate of accumulation (k; mM NaCl-1) was at 50 and 100 microM L-DOPA, respectively, 0.00305 +/- 0.00036 and 0.00328 +/- 0.00029 for dopamine and 0.00672 +/- 0.00072 and 0.00641 +/- 0.00069 for DOPAC. The sodium-dependent formation of dopamine was completely abolished when the experiments were performed in the absence of oxygen. 3. In experiments performed in the presence of 120 mM NaCl, but not in conditions of low sodium (20 mM NaCl in the medium), ouabain (100 and 500 microM) was found to inhibit the accumulation of newly-formed dopamine and DOPAC (14-57% reduction; P less than 0.05); this effect was more marked at 50 and 100 microM L-DOPA.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1504714

  10. Insulin-like growth factor I enhances proenkephalin synthesis and dopamine. beta. -hydroxylase activity in adrenal chromaffin cells

    SciTech Connect

    Wilson, S.P. )

    1991-01-01

    Insulin-like growth factor I (IGF-I) increased both the contents of proenkephalin derived enkephalin-containing peptides and the activity of dopamine {beta}-hydroxylase in bovine adrenal chromaffin cells. These increases in dopamine {beta}-hydroxylase and enkephalin-containing peptides continued for at least 8 days. The half-maximal IGF-I concentration for these effects was {approximately} 1 nM, with maximal effects observed at 10-30 nM. In contrast, insulin was 1,000-fold less potent. Pretreatment of chromaffin cells with IGF-I increased the rate of ({sup 35}S)proenkephalin synthesis 4-fold compared to untreated cells. Total protein synthesis increased only 1.5-fold under these conditions. These results suggest that IGF-I may be a normal regulator of chromaffin cell function.

  11. Mapping the Catechol Binding Site in Dopamine D1 Receptors: Synthesis and Evaluation of Two Parallel Series of Bicyclic Dopamine Analogues

    PubMed Central

    Bonner, Lisa A.; Laban, Uros; Chemel, Benjamin R.; Juncosa, Jose I.; Lill, Markus A.; Watts, Val J.; Nichols, David E.

    2012-01-01

    A novel class of isochroman dopamine analogues, 1, originally reported by Abbott Laboratories, had greater than 100-fold selectivity for D1-like vs. D2-like receptors. We synthesized a parallel series of chroman compounds, 2, and showed that repositioning the oxygen in the heterocyclic ring reduced potency and conferred D2-like receptor selectivity to these compounds. In silico modeling supported the hypothesis that the altered pharmacology for 2 was due to potential intramolecular hydrogen bonding between the oxygen in the chroman ring and the meta-hydroxyl of the catechol moiety. This interaction realigns the catechol hydroxyl groups and disrupts key interactions between these ligands and critical serine residues in TM5 of the D1-like receptors. This hypothesis was tested by the synthesis and pharmacological evaluation of a parallel series of carbocyclic compounds, 3. Our results suggest that when the potential for intramolecular hydrogen bonding is removed, D1-like receptor potency and selectivity is restored. PMID:21538900

  12. Regulation of the synthesis and metabolism of striatal dopamine after disruption of nerve conduction in the medial forebrain bundle.

    PubMed Central

    Commissiong, J. W.; Slimovitch, C.; Toffano, G.

    1990-01-01

    1. After physical (knife-cut) or chemically-mediated (tetrodotoxin 300 nM, 1.5 microliters; 1.0 microliters min-1) interruption of nerve conduction in the nigrostriatal tract, there was a marked increase in the synthesis and metabolism of dopamine in the isolated dopaminergic nerve terminals of the striatum. The effect peaked at 4 h post-transection, at which time 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were increased by 300% and 700% respectively (DOPAC: 27 +/- 13 vs 80 +/- 17 nmol g-1; HVA: 6.66 +/- 3.57 vs 54 +/- 18 nmol g-1). The increases in dopamine content and metabolism are secondary to an increase in the rate of synthesis on the lesioned side, versus the intact, control side. 2. In both experimental situations, haloperidol (1.0 mg kg-1, i.p.) retained its known ability to induce a significant increase in DOPAC and HVA in the striatum, despite the interruption of nerve conduction in the nigrostriatal tract. 3. Six days after cutting the left nigrostriatal tract, dopamine in the left striatum was reduced to less than 5% of the control value, and DOPAC and HVA were not detectable. In the denervated, left striatum, the synthesis of dopamine (from injected L-DOPA), and its metabolism to DOPAC and HVA, occurred to the same degree as in the intact right side. In these DOPA-treated rats, haloperidol (1.0 mg kg-1, i.p.) caused a further increase in DOPAC and HVA in the intact striatum, but not in the denervated striatum.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2361171

  13. One-step synthesis of boronic acid functionalized gold nanoclusters for photoluminescence sensing of dopamine

    NASA Astrophysics Data System (ADS)

    Chen, Huide; Liu, Chunxiu; Xia, Yunsheng

    2017-03-01

    This study is the first to report one-step synthesis of boronic acid functionalized gold nanoclusters (AuNCs) using mixed ligands of 4-mercaptophenylboronic acid (MPBA) and glutathione. Furthermore, the emission color of the products can be fancily tuned from green to near-infrared by simply changing the proportion of the two stabilizers. In basic media, dopamine (DA) molecules themselves polymerize each other and form polydopamine with large amounts of cis-diol groups, which then react with boronic acid groups on the AuNC’s surface based on the formation of boronate esters. As a result, the photoluminescence of the AuNCs is well quenched by the electron transfer effect. Accordingly, DA molecules are assayed from 0.5 to 9 μM, and the detection limit is as low as 0.1 μM. The as-prepared AuNCs exhibit high selectivity; the existing biomolecules including various amino acids, ascorbic acid, uric acid, glucose, etc, do not interfere with the assay. The proposed method is successfully applied to the assay of DA in human serum, indicating its practical potential.

  14. Dopamine Polymerization in Liquid Marbles: A General Route to Janus Particle Synthesis.

    PubMed

    Sheng, Yifeng; Sun, Guanqing; Ngai, To

    2016-04-05

    Coating a liquid with a particle shell not only renders a droplet superhydrophobic but also isolates a well-confined microenvironment for miniaturized chemical processes. Previously, we have demonstrated that particles at the liquid marble interface provide an ideal platform for the site-selective modification of superhydrophobic particles. However, the need for a special chemical reaction limits their potential use for the fabrication of Janus particles with various properties. Herein, we combine the employment of liquid marbles as microreactors with the remarkable adhesive ability of polydopamine to develop a general route for the synthesis of Janus particles from micrometer-sized superhydrophobic particles. We demonstrate that dopamine polymerization and deposition inside liquid marbles could be used for the selective surface modification of microsized silica particles, resulting in the formation of Janus particles. Moreover, it is possible to manipulate the Janus balance of the particles via the addition of surfactants and/or organic solvents to tune the interfacial energy. More importantly, owing to the many functional groups in polydopamine, we show that versatile strategies could be introduced to use these partially polydopamine-coated silica particles as platforms for further modification, including nanoparticle immobilization, metal ion chelation and reduction, as well as for chemical reactions. Given the flexibility in the choice of cores and the modification strategies, this developed method is distinctive in its high universality, good controllability, and great practicability.

  15. 2beta-Substituted analogues of 4'-iodococaine: synthesis and dopamine transporter binding potencies.

    PubMed

    Avor, K S; Singh, S; Seale, T W; Pouw, B; Basmadjian, G P

    1998-06-18

    A series of 2beta-substituted analogues of 4'-iodococaine (3) was synthesized and evaluated in an in vitro dopamine transporter (DAT) binding assay. Selective hydrolysis at the 2beta-position of 3 gave the carboxylic acid 15 that served as the intermediate for the synthesis of compounds 4, 5, and 6-11. The 2beta-alkyl derivatives were obtained from ecgonine methyl ester (17) through a series of reactions leading to the aldehyde 20. Wittig reaction of 20 with methyltriphenylphosphorane followed by hydrogenation and benzoylation gave the products 12 and 13. The binding affinity of 4'-iodococaine (3) was 10-fold less than that of cocaine. The hydroxymethane, acetate, amide, benzyl ester, oxidazole, and ethane derivatives of 3 exhibited decreased binding while the vinyl, phenyl, and ethyl esters showed a moderate increase in binding affinity. Only the isopropyl derivative 8 exhibited a 2-fold increase in binding affinity compared with 4'-iodococaine (3). Hydroxylation of 8 at the 2'-position gave 14 which enhanced not only the binding potency at the DAT by another 2-fold but also the selectivity at the DAT over the norepinephrine and serotonin transporters. Compound 14 failed to stimulate locomotor activity in C57BL/6J mice over a wide dose range and blocked cocaine-induced locomotor stimulant action.

  16. Down-regulation of tryptamine binding sites following chronic molindone administration. A comparison with responses of dopamine and 5-hydroxytryptamine receptors.

    PubMed

    Nguyen, T V; Juorio, A V

    1989-10-01

    The present study assessed changes of tryptamine, dopamine D2, 5-HT1 and 5-HT2 binding sites in rat brain following chronic treatment with low (5 mg/kg/day) and high (40 mg/kg/day) doses of molindone, a clinically effective psychotropic drug. The high-dose molindone treatment produced a decrease in the number of tryptamine binding sites while both high and low doses caused an increase in the number of dopamine D2 binding sites in the striatum. No significant changes were observed in either 5-HT1 or 5-HT2 binding sites in the cerebral cortex. Competition binding experiments showed that molindone was a potent inhibitor at dopamine D2 but less effective at tryptamine, 5-HT1 and 5-HT2 binding sites. The inhibition activity of molindone towards type A monoamine oxidase produced a significant increase in endogenous tryptamine accumulation rate which was much higher than that of dopamine and 5-HT. These findings suggest that the reduction in the number of tryptamine binding sites produced by chronic molindone administration is related to monoamine oxidase inhibition and that the increase in the number of dopamine D2 binding sites is correlated to receptor blocking activity of the drug.

  17. The human testis determining factor SRY localizes in midbrain dopamine neurons and regulates multiple components of catecholamine synthesis and metabolism

    PubMed Central

    Czech, Daniel P.; Lee, Joohyung; Sim, Helena; Parish, Clare L.; Vilain, Eric; Harley, Vincent R.

    2012-01-01

    The male sex is determined by the sex determining region on the Y chromosome (SRY) transcription factor. The unexpected action of SRY in the control of voluntary movement in male rodents suggests a role in regulation of dopamine transmission and dopamine-related disorders with sex bias such as Parkinson’s disease. We investigated SRY expression in the human brain and function in vitro. SRY immunoreactivity was detected in the human male, but not female, substantia nigra pars compacta (SNc) within a sub-population of tyrosine hydroxylase (TH) positive neurons. SRY protein also co-localised with TH positive neurons in the ventral tegmental area and GAD-positive neurons in the substantia nigra pars reticulate (SNr). Retinoic acid-induced differentiation of precursor NT2 cells into dopaminergic cells (NT2N) increased expression of TH, NURR1, D2R and SRY. In the human neuroblastoma cell line, M17, SRY knockdown resulted in a reduction in TH, DDC, DBH and MAO-A expression; enzymes which control dopamine synthesis and metabolism. Conversely, SRY overexpression increased TH, DDC, DBH, D2R and MAO-A levels, which was accompanied by increased extracellular dopamine levels. A luciferase assay demonstrated that SRY activated a 4.6 kb 5′ upstream regulatory region of the human TH promoter/nigral enhancer. Combined, these results suggest that SRY may play a role as a positive regulator of catecholamine synthesis and metabolism in the human male midbrain. Given the limitations of human tissue analysis, further studies are required to provide a definitive answer on SRY expression in human brain regions. PMID:22568433

  18. The neurobiology of glucocerebrosidase-associated parkinsonism: a positron emission tomography study of dopamine synthesis and regional cerebral blood flow.

    PubMed

    Goker-Alpan, Ozlem; Masdeu, Joseph C; Kohn, Philip D; Ianni, Angela; Lopez, Grisel; Groden, Catherine; Chapman, Molly C; Cropp, Brett; Eisenberg, Daniel P; Maniwang, Emerson D; Davis, Joie; Wiggs, Edythe; Sidransky, Ellen; Berman, Karen F

    2012-08-01

    Mutations in GBA, the gene encoding glucocerebrosidase, the enzyme deficient in Gaucher disease, are common risk factors for Parkinson disease, as patients with Parkinson disease are over five times more likely to carry GBA mutations than healthy controls. Patients with GBA mutations generally have an earlier onset of Parkinson disease and more cognitive impairment than those without GBA mutations. We investigated whether GBA mutations alter the neurobiology of Parkinson disease, studying brain dopamine synthesis and resting regional cerebral blood flow in 107 subjects (38 women, 69 men). We measured dopamine synthesis with (18)F-fluorodopa positron emission tomography, and resting regional cerebral blood flow with H(2)(15)O positron emission tomography in the wakeful, resting state in four study groups: (i) patients with Parkinson disease and Gaucher disease (n = 7, average age = 56.6 ± 9.2 years); (ii) patients with Parkinson disease without GBA mutations (n = 11, 62.1 ± 7.1 years); (iii) patients with Gaucher disease without parkinsonism, but with a family history of Parkinson disease (n = 14, 52.6 ± 12.4 years); and (iv) healthy GBA-mutation carriers with a family history of Parkinson disease (n = 7, 50.1 ± 18 years). We compared each study group with a matched control group. Data were analysed with region of interest and voxel-based methods. Disease duration and Parkinson disease functional and staging scores were similar in the two groups with parkinsonism, as was striatal dopamine synthesis: both had greatest loss in the caudal striatum (putamen Ki loss: 44 and 42%, respectively), with less reduction in the caudate (20 and 18% loss). However, the group with both Parkinson and Gaucher diseases showed decreased resting regional cerebral blood flow in the lateral parieto-occipital association cortex and precuneus bilaterally. Furthermore, two subjects with Gaucher disease without parkinsonian manifestations showed diminished striatal dopamine. In conclusion

  19. Controllable Synthesis of Functional Hollow Carbon Nanostructures with Dopamine As Precursor for Supercapacitors.

    PubMed

    Liu, Chao; Wang, Jing; Li, Jiansheng; Luo, Rui; Shen, Jinyou; Sun, Xiuyun; Han, Weiqing; Wang, Lianjun

    2015-08-26

    N-doped hollow carbon spheres (N-HCSs) are promising candidates as electrode material for supercapacitor application. In this work, we report a facile one-step synthesis of discrete and highly dispersible N-HCSs with dopamine (DA) as a carbon precursor and TEOS as a structure-assistant agent in a mixture containing water, ethanol, and ammonia. The architectures of resultant N-HCSs, including yolk-shell hollow carbon spheres (YS-HCSs), single-shell hollow carbon spheres (SS-HCSs), and double-shells hollow carbon spheres (DS-HCSs), can be efficiently controlled through the adjustment of the amount of ammonia. To explain the relation and formation mechanism of these hollow carbon structures, the samples during the different synthetic steps, including polymer/silica spheres, carbon/silica spheres and silica spheres by combustion in air, were characterized by TEM. Electrochemical measurements performed on YS-HCSs, SS-HCSs, and DS-HCSs showed high capacitance with 215, 280, and 381 F g(-1), respectively. Moreover, all the nitrogen-doped hollow carbon nanospheres showed a good cycling stability 97.0% capacitive retention after 3000 cycles. Notably, the highest capacitance of DS-HCSs up to 381 F g(-1) is higher than the capacitance reported so far for many carbon-based materials, which may be attributed to the high surface area, hollow structure, nitrogen functionalization, and double-shell architecture. These kinds of N-doped hollow-structured carbon spheres may show promising prospects as advanced energy storage materials and catalyst supports.

  20. Synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel for electrochemical detection of dopamine.

    PubMed

    Li, Ruiyi; Yang, Tingting; Li, Zaijun; Gu, Zhiguo; Wang, Guangli; Liu, Junkang

    2017-02-15

    Integration of noble metal nanomaterials on graphene nanosheets potentially paves one way to improve their electronic, chemical and electrochemical properties. The study reported synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel composite (Pd@Au/N,S-MGA). The as-prepared composite offers a well-defined three-dimensional architecture with rich of mesopores. The Pd@Au nanoalloys were dispersed on the graphene framework networks and their active sites were fully exposed. The unique structure achieves to ultra high electron/ion conductivity, electrocatalytic activity and structural stability. The sensor based on the Pd@Au/N,S-MGA creates ultrasensitive electrochemical response towards dopamine due to significantly electrochemical synergy between Pd, Au and N,S-MGA. Its differential pulse voltammetric signal linearly increases with the increase of dopamine concentration in the range from 1.0 × 10(-9) M to 4.0 × 10(-5) M with the detection limit of 3.6 × 10(-10) M (S/N = 3). The analytical method provides the advantage of sensitivity, reproducibility, rapidity and long-term stability. It has been successfully applied in the detection of trace dopamine in biological samples. The study also opens a window on the electronic properties of graphene aerogel and metal nanomaterials as well their nanohybrids to meet needs of further applications as nanoelectronics in diagnosis, bioanalysis and catalysis.

  1. Synthesis and dopamine receptor selectivity of the benzyltetrahydroisoquinoline, (R)-(+)-nor-roefractine.

    PubMed

    Cabedo, N; Protais, P; Cassels, B K; Cortes, D

    1998-06-26

    (R)-(+)-nor-Roefractine (1) was synthesized by the Bischler-Napieralski route, using asymmetric reduction of the 1, 2-didehydro precursor imine with sodium (S)-N-CBZ-prolinyloxyborohydride. Compound 1 was able to displace [3H]-raclopride (a D2 dopamine receptor-selective ligand) from its specific binding sites in rat striatum with selectivity vs [3H]-SCH23390 (D1 dopamine receptor-selective ligand).

  2. Low dose pramipexole is neuroprotective in the MPTP mouse model of Parkinson's disease, and downregulates the dopamine transporter via the D3 receptor

    PubMed Central

    Joyce, Jeffrey N; Woolsey, Cheryl; Ryoo, Han; Borwege, Sabine; Hagner, Diane

    2004-01-01

    Background Our aim was to determine if pramipexole, a D3 preferring agonist, effectively reduced dopamine neuron and fiber loss in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model when given at intraperitoneal doses corresponding to clinical doses. We also determined whether subchronic treatment with pramipexole regulates dopamine transporter function, thereby reducing intracellular transport of the active metabolite of MPTP, 1-methyl-4-phenylpyridinium (MPP+). Methods Ten 12-month old C57BL/6 mice were treated with MPTP (or saline) twice per day at 20 mg/kg s.c. (4 injections over 48 h). Mice were pretreated for 3 days and during the 2-day MPTP regimen with pramipexole (0.1 mg/kg/day) or saline. Stereological quantification of dopamine neuron number and optical density measurement of dopamine fiber loss were carried out at 1 week after treatment, using immunostaining for dopamine transporter (DAT) and tyrosine hydroxylase (TH). Additional wild-type (WT) and D3 receptor knockout (KO) mice were treated for 5 days with pramipexole (0.1 mg/kg/day) or vehicle. The kinetics of [3H]MPP+ and [3H]DA uptake (Vmax and Km) were determined 24 h later; and at 24 h and 14 days dopamine transporter density was measured by quantitative autoradiography. Results Pramipexole treatment completely antagonized the neurotoxic effects of MPTP, as measured by substantia nigra and ventral tegmental area TH-immunoreactive cell counts. MPTP- induced loss of striatal innervation, as measured by DAT-immunoreactivity, was partially prevented by pramipexole, but not with regard to TH-IR. Pramipexole also reduced DAT- immunoreactivity in non-MPTP treated mice. Subchronic treatment with pramipexole lowered the Vmax for [3H]DA and [3H]MPP+ uptake into striatal synaptosomes of WT mice. Pramipexole treatment lowered Vmax in WT but not D3 KO mice; however, D3 KO mice had lower Vmax for [3H]DA uptake. There was no change in DAT number in WT with pramipexole treatment or D3 KO mice at

  3. The inhibition of dopamine synthesis in fetuses changes the pattern of T-lymphocyte maturation in the thymus of adult rats.

    PubMed

    Lifantseva, N V; Koneeva, Ts O; Voronova, S N; Zakharova, L A; Melnikova, V I

    2016-09-01

    The mRNA for dopamine receptors of type D1, D3, D5, but not type D2, was detected in the thymus of rats starting from day 16 of embryonic development (E16). Dopamine at concentrations of 10(-8)-10(‒6) M inhibited fetus thymocyte response to mitogen, confirming the functionality of the receptors and the possibility of a direct effect of dopamine on the developing thymus. Pharmacological inhibition of catecholamine synthesis in the crucial period of thymus development leads to long-term changes in the T-system immunity due to increased production of natural regulatory T-lymphocytes. The presence and functional activity of dopamine receptors in the fetal thymus indicates its ability to influence the development of the immune system of rats during ontogeny.

  4. D1-like dopamine receptors downregulate Na+-K+-ATPase activity and increase cAMP production in the posterior gills of the blue crab Callinectes sapidus.

    PubMed

    Arnaldo, Francis B; Villar, Van Anthony M; Konkalmatt, Prasad R; Owens, Shaun A; Asico, Laureano D; Jones, John E; Yang, Jian; Lovett, Donald L; Armando, Ines; Jose, Pedro A; Concepcion, Gisela P

    2014-09-15

    Dopamine-mediated regulation of Na(+)-K(+)-ATPase activity in the posterior gills of some crustaceans has been reported to be involved in osmoregulation. The dopamine receptors of invertebrates are classified into three groups based on their structure and pharmacology: D1- and D2-like receptors and a distinct invertebrate receptor subtype (INDR). We tested the hypothesis that a D1-like receptor is expressed in the blue crab Callinectes sapidus and regulates Na(+)-K(+)-ATPase activity. RT-PCR, using degenerate primers, showed the presence of D1βR mRNA in the posterior gill. The blue crab posterior gills showed positive immunostaining for a dopamine D5 receptor (D5R or D1βR) antibody in the basolateral membrane and cytoplasm. Confocal microscopy showed colocalization of Na(+)-K(+)-ATPase and D1βR in the basolateral membrane. To determine the effect of D1-like receptor stimulation on Na(+)-K(+)-ATPase activity, intact crabs acclimated to low salinity for 6 days were given an intracardiac infusion of the D1-like receptor agonist fenoldopam, with or without the D1-like receptor antagonist SCH23390. Fenoldopam increased cAMP production twofold and decreased Na(+)-K(+)-ATPase activity by 50% in the posterior gills. This effect was blocked by coinfusion with SCH23390, which had no effect on Na(+)-K(+)-ATPase activity by itself. Fenoldopam minimally decreased D1βR protein expression (10%) but did not affect Na(+)-K(+)-ATPase α-subunit protein expression. This study shows the presence of functional D1βR in the posterior gills of euryhaline crabs chronically exposed to low salinity and highlights the evolutionarily conserved function of the dopamine receptors on sodium homeostasis.

  5. Dopamine transporter down-regulation following repeated cocaine: implications for 3,4-methylenedioxymethamphetamine-induced acute effects and long-term neurotoxicity in mice

    PubMed Central

    Peraile, I; Torres, E; Mayado, A; Izco, M; Lopez-Jimenez, A; Lopez-Moreno, JA; Colado, MI; O'Shea, E

    2010-01-01

    Background and purpose: 3,4-Methylenedioxymethamphetamine (MDMA) and cocaine are two widely abused psychostimulant drugs targeting the dopamine transporter (DAT). DAT availability regulates dopamine neurotransmission and uptake of MDMA-derived neurotoxic metabolites. We aimed to determine the effect of cocaine pre-exposure on the acute and long-term effects of MDMA in mice. Experimental approach: Mice received a course of cocaine (20 mg·kg−1, ×2 for 3 days) followed by MDMA (20 mg·kg−1, ×2, 3 h apart). Locomotor activity, extracellular dopamine levels and dopaminergic neurotoxicity were determined. Furthermore, following the course of cocaine, DAT density in striatal plasma membrane and endosome fractions was measured. Key results: Four days after the course of cocaine, challenge with MDMA attenuated the MDMA-induced striatal dopaminergic neurotoxicity. Co-administration of the protein kinase C (PKC) inhibitor NPC 15437 prevented cocaine protection. At the same time, after the course of cocaine, DAT density was reduced in the plasma membrane and increased in the endosome fraction, and this effect was prevented by NPC 15437. The course of cocaine potentiated the MDMA-induced increase in extracellular dopamine and locomotor activity, following challenge 4 days later, compared with those pretreated with saline. Conclusions and implications: Repeated cocaine treatment followed by withdrawal protected against MDMA-induced dopaminergic neurotoxicity by internalizing DAT via a mechanism which may involve PKC. Furthermore, repeated cocaine followed by withdrawal induced behavioural and neurochemical sensitization to MDMA, measures which could be indicative of increased rewarding effects of MDMA. PMID:20015297

  6. D1-like dopamine receptors downregulate Na+-K+-ATPase activity and increase cAMP production in the posterior gills of the blue crab Callinectes sapidus

    PubMed Central

    Arnaldo, Francis B.; Villar, Van Anthony M.; Konkalmatt, Prasad R.; Owens, Shaun A.; Asico, Laureano D.; Jones, John E.; Yang, Jian; Lovett, Donald L.; Armando, Ines; Concepcion, Gisela P.

    2014-01-01

    Dopamine-mediated regulation of Na+-K+-ATPase activity in the posterior gills of some crustaceans has been reported to be involved in osmoregulation. The dopamine receptors of invertebrates are classified into three groups based on their structure and pharmacology: D1- and D2-like receptors and a distinct invertebrate receptor subtype (INDR). We tested the hypothesis that a D1-like receptor is expressed in the blue crab Callinectes sapidus and regulates Na+-K+-ATPase activity. RT-PCR, using degenerate primers, showed the presence of D1βR mRNA in the posterior gill. The blue crab posterior gills showed positive immunostaining for a dopamine D5 receptor (D5R or D1βR) antibody in the basolateral membrane and cytoplasm. Confocal microscopy showed colocalization of Na+-K+-ATPase and D1βR in the basolateral membrane. To determine the effect of D1-like receptor stimulation on Na+-K+-ATPase activity, intact crabs acclimated to low salinity for 6 days were given an intracardiac infusion of the D1-like receptor agonist fenoldopam, with or without the D1-like receptor antagonist SCH23390. Fenoldopam increased cAMP production twofold and decreased Na+-K+-ATPase activity by 50% in the posterior gills. This effect was blocked by coinfusion with SCH23390, which had no effect on Na+-K+-ATPase activity by itself. Fenoldopam minimally decreased D1βR protein expression (10%) but did not affect Na+-K+-ATPase α-subunit protein expression. This study shows the presence of functional D1βR in the posterior gills of euryhaline crabs chronically exposed to low salinity and highlights the evolutionarily conserved function of the dopamine receptors on sodium homeostasis. PMID:25080496

  7. The monoamine stabilizer (−)‐OSU6162 counteracts downregulated dopamine output in the nucleus accumbens of long‐term drinking Wistar rats

    PubMed Central

    Feltmann, Kristin; Fredriksson, Ida; Wirf, Malin; Schilström, Björn

    2015-01-01

    Abstract We recently established that the monoamine stabilizer (−)‐OSU6162 (OSU6162) decreased voluntary alcohol‐mediated behaviors, including alcohol intake and cue/priming‐induced reinstatement, in long‐term drinking rats, while blunting alcohol‐induced dopamine output in the nucleus accumbens (NAc) of alcohol‐naïve rats. Therefore, we hypothesized that OSU6162 attenuates alcohol‐mediated behaviors by blunting alcohol's rewarding effects. Here, we evaluated the effects of long‐term drinking and OSU6162 treatment (30 mg/kg, sc) on basal and alcohol‐induced (2.5 g/kg, ip) NAc dopamine outputs in Wistar rats after 10 months of intermittent access to 20% alcohol. The results showed that basal and alcohol‐induced NAc dopamine outputs were significantly lower in long‐term drinking rats, compared with alcohol‐naïve rats. In the long‐term drinking rats, OSU6162 slowly increased and maintained the dopamine output significantly elevated compared with baseline for at least 4 hours. Furthermore, OSU6162 pre‐treatment did not blunt the alcohol‐induced output in the long‐term drinking rats, a finding that contrasted with our previous results in alcohol‐naïve rats. Finally, OSU6162 did not induce conditioned place preference (CPP) in either long‐term drinking or alcohol‐naïve rats, indicating that OSU6162 has no reinforcing properties. To verify that the CPP results were not due to memory acquisition impairment, we demonstrated that OSU6162 did not affect novel object recognition. In conclusion, these results indicate that OSU6162 attenuates alcohol‐mediated behaviors by counteracting NAc dopamine deficits in long‐term drinking rats and that OSU6162 is not rewarding on its own. Together with OSU6162's beneficial side‐effect profile, the present study merits evaluation of OSU6162's clinical efficacy to attenuate alcohol use in alcohol‐dependent patients. PMID:26464265

  8. Synthesis, pharmacological evaluation and molecular modeling studies of triazole containing dopamine D3 receptor ligands.

    PubMed

    Peng, Xin; Wang, Qi; Mishra, Yogesh; Xu, Jinbin; Reichert, David E; Malik, Maninder; Taylor, Michelle; Luedtke, Robert R; Mach, Robert H

    2015-02-01

    A series of 2-methoxyphenyl piperazine analogues containing a triazole ring were synthesized and their in vitro binding affinities at human dopamine D2 and D3 receptors were evaluated. Compounds 5b, 5c, 5d, and 4g, demonstrate high affinity for dopamine D3 receptors and moderate selectivity for the dopamine D3 versus D2 receptor subtypes. To further examine their potential as therapeutic agents, their intrinsic efficacy at both D2 and D3 receptors was determined using a forskolin-dependent adenylyl cyclase inhibition assay. Affinity at dopamine D4 and serotonin 5-HT1A receptors was also determined. In addition, information from previous molecular modeling studies of the binding of a panel of 163 structurally-related benzamide analogues at dopamine D2 and D3 receptors was applied to this series of compounds. The results of the modeling studies were consistent with our previous experimental data. More importantly, the modeling study results explained why the replacement of the amide linkage with the hetero-aromatic ring leads to a reduction in the affinity of these compounds at D3 receptors.

  9. Relation between Dopamine Synthesis Capacity and Cell-Level Structure in Human Striatum: A Multi-Modal Study with Positron Emission Tomography and Diffusion Tensor Imaging

    PubMed Central

    Kawaguchi, Hiroshi; Obata, Takayuki; Takano, Harumasa; Nogami, Tsuyoshi; Suhara, Tetsuya; Ito, Hiroshi

    2014-01-01

    Positron emission tomography (PET) study has shown that dopamine synthesis capacity varied among healthy individuals. This interindividual difference might be due to a difference in the cell-level structure of presynaptic dopaminergic neurons, i.e., cellular density and/or number. In this study, the relations between the dopamine synthesis capacity measured by PET and the parameter estimates in diffusion tensor imaging (DTI) in striatal subregions were investigated in healthy human subjects. DTI and PET studies with carbon-11 labeled L-DOPA were performed in ten healthy subjects. Age-related changes in the above parameters were also considered. Fractional anisotropy showed a significant positive correlation with age in the posterior caudate. There was significant negative correlation between dopamine synthesis capacity and mean diffusivity in the posterior caudate and putamen. Assuming that mean diffusivity reflects the density of wide-spreading axonal terminals in the striatum, the result suggests that dopamine synthesis may be related to the density of dopaminergic neuronal fibers. It is evident that PET/DTI combined measurements can contribute to investigations of the pathophysiology of neuropsychiatric diseases involving malfunction of dopaminergic neurons. PMID:24498218

  10. Synthesis and evaluation of tamoxifen derivatives with a long alkyl side chain as selective estrogen receptor down-regulators.

    PubMed

    Shoda, Takuji; Kato, Masashi; Harada, Rintaro; Fujisato, Takuma; Okuhira, Keiichiro; Demizu, Yosuke; Inoue, Hideshi; Naito, Mikihiko; Kurihara, Masaaki

    2015-07-01

    Estrogen receptors (ERs) play a major role in the growth of human breast cancer cells. An antagonist that acts as not only an inhibitor of ligand binding but also an inducer of the down-regulation of ER would be useful for the treatment for ER-positive breast cancer. We previously reported the design and synthesis of a selective estrogen receptor down-regulator (SERD), (E/Z)-4-(1-{4-[2-(dodecylamino)ethoxy]phenyl}-2-phenylbut-1-en-1-yl)phenol (C12), which is a tamoxifen derivative having a long alkyl chain on the amine moiety. This compound induced degradation of ERα via a proteasome-dependent pathway and showed an antagonistic effect in MCF-7 cells. With the aim of increasing the potency of SERDs, we designed and synthesized various tamoxifen derivatives that have various lengths and terminal groups of the long alkyl side chain. During the course of our investigation, C10F having a 10-fluorodecyl group on the amine moiety of 4-OHT was shown to be the most potent compound among the tamoxifen derivatives. Moreover, computational docking analysis suggested that the long alkyl chain interacted with the hydrophobic region on the surface of the ER, which is a binding site of helix 12 and coactivator. These results provide useful information to develop promising candidates as SERDs.

  11. Altered pattern of brain dopamine synthesis in male adolescents with attention deficit hyperactivity disorder

    PubMed Central

    Forssberg, Hans; Fernell, Elisabeth; Waters, Susanna; Waters, Nicholas; Tedroff, Joakim

    2006-01-01

    Background Limited data from positron emission tomography (PET) studies of subjects with attention-deficit/hyperactivity disorder (ADHD) indicate alterations in brain dopamine neurotransmission. However, these studies have used conventional univariate approaches that are less sensitive to detect complex interactions that may exist between different brain dopamine pathways and individual symptoms of ADHD. We aimed to investigate these potential interactions in adolescents with ADHD. Methods We used a 3D PET scan to measure utilization of native L-[11C]-DOPA to map dopamine presynaptic function in various cortical, striatal and midbrain regions in a group of 8 male adolescents with ADHD and 6 age matched controls. To evaluate the interactions between the studied brain regions, multivariate statistical methods were used. Results Abnormal dopaminergic function was found in multiple brain regions of patients with ADHD. A main finding was lower L-[11C]-DOPA utilization in adolescent with ADHD as compared to control subjects, especially in subcortical regions. This pattern of dopaminergic activity was correlated specifically with symptoms of inattention. Conclusion Dopamine signalling in the brain plays an important modulatory role in a variety of motor and cognitive functions. We have identified region-specific functional abnormalities in dopaminergic function, which may help better account for the symptoms of ADHD. PMID:17144907

  12. Colorimetric detection of copper ions in tap water during the synthesis of silver/dopamine nanoparticles.

    PubMed

    Ma, Yu-rong; Niu, Hong-yun; Zhang, Xiao-le; Cai, Ya-qi

    2011-12-21

    A facile, economic and eco-friendly colorimetric sensor for Cu(2+) using dopamine/silver nanoparticles was developed. The sensor shows excellent sensitivity and selectivity toward Cu(2+) in the range of 3.2-512 ppb and can be applied for Cu(2+) detection in tap water.

  13. Synthesis and characterization of iodobenzamide analogues: Potential D-2 dopamine receptor imaging agents

    SciTech Connect

    Murphy, R.A.; Kung, H.F.; Kung, M.P.; Billings, J. )

    1990-01-01

    (S)-N-((1-Ethyl-2-pyrrolidinyl)methyl)-2-hydroxy-3-iodo-6- methoxybenzamide (({sup 123}I)IBZM) is a central nervous system (CNS) D-2 dopamine receptor imaging agent. In order to investigate the versatility of this parent structure in specific dopamine receptor localization and the potential for developing new dopamine receptor imaging agents, a series of new iodinated benzamides with fused ring systems, naphthalene (INAP) and benzofuran (IBF), was synthesized and radiolabeled, and the in vivo and in vitro biological properties were characterized. The best analogue of IBZM is IBF (21). The specific binding of ({sup 125}I)IBF (21) with rat striatal tissue preparation was found to be saturable and displayed a Kd of 0.106 {plus minus} 0.015 nM. Competition data of various receptor ligands for ({sup 125}I)IBF (21) binding show the following rank order of potency: spiperone greater than IBF (21) greater than IBZM greater than (+)-butaclamol greater than ({plus minus})-ADTN,6,7 greater than ketanserin greater than SCH-23390 much greater than propranolol. The in vivo biodistribution results confirm that ({sup 125}I)IBF (21) concentrated in the striatal area after iv injection into rats. The study demonstrates that ({sup 123}I)IBF (21) is a potential agent for imaging CNS D-2 dopamine receptors.

  14. Downregulation of ALAS1 by nicarbazin treatment underlies the reduced synthesis of protoporphyrin IX in shell gland of laying hens.

    PubMed

    Samiullah, Sami; Roberts, Juliet; Wu, Shu-Biao

    2017-07-24

    Shell colour is an important trait for eggs and an understanding of pigment deposition will assist potential management of egg shell colour loss. We demonstrated that nicarbazin feeding down-regulated ALAS1 and reduced protoporphyrin IX (PP IX) in both shell gland and eggshell, indicating the role of nicarbazin in inhibiting the synthesis of PP IX. Additionally, the expression levels of the genes did not show sequential upregulation in the same order of diurnal time-points (TP) during egg formation. The gene SLC25A38, responsible for transporting glycine from cytoplasm to mitochondria, and the gene ALAS1, encoding rate-limiting enzyme (delta-aminolevulinic acid synthase 1), had higher expression at 15 hr, as compared with 2, 5 and 23.5 hrs postoviposition. Interestingly, ABCB6, a gene encoding an enzyme responsible for transporting coproporphyrinogen III, showed higher expression level at 2 and 5 hrs. However, the expression of CPOX that converts coproporphyrinogen III to protoporphyrinogen III, and ABCG2 that transports PP IX out from mitochondria did not alter. Nevertheless, mitochondrial count per cell did not show consistent change in response to time-points postoviposition and nicarbazin feeding. The information obtained in the study sheds light on how nicarbazin disrupts the synthesis of PP IX.

  15. Iron chelation down-regulates dopamine transporter expression by decreasing mRNA stability and increasing endocytosis in N2a cells.

    PubMed

    Hegde, Narasimha V; Jensen, Gordon L; Unger, Erica L

    2011-02-15

    Cell surface expression of the dopamine transporter (DAT) is determined by the relative rates of its internalization and recycling. Changes in the cellular labile iron pool (LIP) affect many cellular mechanisms including those that regulate DAT trafficking. In this study, we analyzed DAT expression and posttranslational modifications in response to changes in cellular iron in transfected neuroblastoma cells (N2a). Iron chelation by desferrioxamine (DFO) altered DAT protein levels by decreasing the stability of DAT mRNA. Increased phosphorylation and ubiquitination of this transporter protein following DFO treatment were also observed. Cellular iron depletion elevated protein levels of the early endosomal marker Rab5. Moreover, confocal microscopy studies showed increased localization of DAT into the endosomal compartment in DFO-treated cells compared to control. Together, these findings suggest that cellular iron depletion regulates DAT expression through reducing mRNA stability as well as an increasing in endocytosis.

  16. A one-step automated synthesis of the dopamine transporter ligand [(18)F]FECNT from the chlorinated precursor.

    PubMed

    Pijarowska-Kruszyna, Justyna; Jaron, Antoni; Kachniarz, Artur; Malkowski, Bogdan; Garnuszek, Piotr; Mikolajczak, Renata

    2016-03-01

    The use of [(18)F]labelled nortropane derivative 2β-carbomethoxy-3β-(4-chlorophenyl)-8-(2-fluoroethyl)-nortropane (FECNT) as a dopamine transporter ligand for PET imaging is dependent on efficient radiosynthesis method. Herein, the automated synthesis of [(18)F]FECNT from its chlorinated precursor in commercially available SynChrom [(18)F] R&D module has been developed. The synthesis unit was readily configured for the one-step synthesis from corresponding chlorinated precursor. The radiolabeling process involved a classical [(18)F]fluoride nucleophilic substitution performed at 110 °C for 12 min and finally HPLC and SPE purification. Crude [(18)F]FECNT was obtained with a radiolabeling yield of 59 ± 12% (n = 5). The average uncorrected amount of [(18)F]FECNT in the final formulated dose was 2.0 ± 0.5 GBq (32 ± 7% overall decay-corrected yields) obtained with radiochemical purity over 99% and specific activity of 55 GBq/µmol. The total duration of the procedure was 80-90 min. An automated radiosynthesis of [(18)F]FECNT with high radiochemical purity may provide a simple and robust method of radiopharmaceutical preparation for routine clinical applications.

  17. Depression of brain dopamine and its metabolite after mating in European honeybee (Apis mellifera) queens

    NASA Astrophysics Data System (ADS)

    Harano, Ken-Ichi; Sasaki, Ken; Nagao, Takashi

    2005-07-01

    To explore neuro-endocrinal changes in the brain of European honeybee (Apis mellifera) queens before and after mating, we measured the amount of several biogenic amines, including dopamine and its metabolite in the brain of 6- and 12-day-old virgins and 12-day-old mated queens. Twelve-day-old mated queens showed significantly lower amounts of dopamine and its metabolite (N-acetyldopamine) than both 6- and 12-day-old virgin queens, whereas significant differences in the amounts of these amines were not detected between 6- and 12-day-old virgin queens. These results are explained by down-regulation of both synthesis and secretion of brain dopamine after mating. It is speculated that higher amounts of brain dopamine in virgin queens might be involved in activation of ovarian follicles arrested in previtellogenic stages, as well as regulation of their characteristic behaviors.

  18. Incorporation of 5-hydroxyindazole into the self-polymerization of dopamine for novel polymer synthesis.

    PubMed

    Peterson, Matthew B; Le-Masurier, Solomon P; Lim, Khoon; Hook, James M; Martens, Penny; Granville, Anthony M

    2014-02-01

    Investigation into the mussel-inspired polymerization of dopamine has led to the realization that other compounds possessing potential quinone structures could undergo similar self-polymerizations in mild buffered aqueous conditions. To this end, 5-hydroxyindazole was added to a dopamine polymerization matrix in varying amounts, to study its incorporation into a polydopamine coating of silica particles. Solid-state (13) C NMR spectroscopy confirmed the presence of the indazole in the polymer shell when coated onto silica gel. SEM and DLS analysis also confirmed that the presence of the indazole in the reaction matrix yielded monodisperse polymer-coated particles, which retained their polymer shell upon HF etching, except when high levels of the indazole were used. Characterization data and examination of incorporation mechanism suggests that the 5-hydroxyindazole performs the function of a chain-terminating agent. Cytotoxicity studies of the polymer particles containing 5-hydroxyindazole showed dramatically lower toxicity levels compared to polydopamine alone.

  19. Effects of systemic carbidopa on dopamine synthesis in rat hypothalamus and striatum

    NASA Technical Reports Server (NTRS)

    Kaakkola, S.; Tuomainen, P.; Wurtman, R. J.; Mannisto, P. T.

    1992-01-01

    Significant concentrations of carbidopa (CD) were found in rat hypothalamus, striatum, and in striatal microdialysis efflux after intraperitoneal administration of the drug. Efflux levels peaked one hour after administration of 100 mg/kg at 0.37 micrograms/ml, or about 2% of serum levels. Concurrent CD levels in hypothalamus and striatum were about 2.5% and 1.5%, respectively, of corresponding serum levels. Levels of dopamine and its principal metabolites in striatal efflux were unaffected. The removal of the brain blood by saline perfusion decreased the striatal and hypothalamic CD concentrations only by 33% and 16%, respectively. In other rats receiving both CD and levodopa (LD), brain L-dopa, dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) levels after one hour tended to be proportionate to LD dose. When the LD dose remained constant, increasing the CD dose dose-dependently enhanced L-dopa levels in the hypothalamus and striatum. However dopamine levels did not increase but, in contrast, decreased dose-dependently (although significantly only in the hypothalamus). CD also caused dose-dependent decrease in striatal 3-O-methyldopa (3-OMD) and in striatal and hypothalamic homovanillic acid (HVA), when the LD dose was 50 mg/kg. We conclude that, at doses exceeding 50 mg/kg, sufficient quantities of CD enter the brain to inhibit dopamine formation, especially in the hypothalamus. Moreover, high doses of LD/CD, both of which are themselves catechols, can inhibit the O-methylation of brain catecholamines formed from the LD.

  20. Effects of systemic carbidopa on dopamine synthesis in rat hypothalamus and striatum

    NASA Technical Reports Server (NTRS)

    Kaakkola, S.; Tuomainen, P.; Wurtman, R. J.; Maennistoe, P. T.

    1991-01-01

    Significant concentrations of carbidopa (CD) were found in rat hypothalamus, striatum, and in striatal microdialysis efflux after intraperitoneal administration of the drug. Efflux levels peaked one hour after administration of 100 mg/kg at 0.37 microg/kg or about 2 percent of serum levels. Concurrent CD levels in hypothalamus and striatum were about 2.5 percent and 1.5 percent, respectively, of corresponding serum levels. Levels of dopamine and its principal metabolites in striatal efflux were unaffected. The removal of the brain blood by saline perfusion decreased the striatal and hypothalamic CD concentrations only by 33 percent and 16 percent, respectively. In other rats receiving both CD and levodopa (LD), brain L-dopa, dopamine, and 3,4-dihydroxyphenvlacetic acid (DOPAC) levels after one hour tended to be proportionate to LD dose. When the LD dose remained constant, increasing the CD dose dose-dependently enhanced L-dopa levels in the hypothalamus and striatum. However, dopamine levels did not increase but, in contrast, decreased dose-dependently (although significantly only in the hypothalamus). CD also caused dose-dependent decrease in striatal 3-O-methyldopa (3-OMD) and in striatal and hypothalamic homovanillic acid (HVA), when the LD dose was 50 mg/kg. We conclude that, at doses exceedimg 50 mg/kg, sufficient quantities of CD enter the brain to inhibit dopamine formation, especially in the hypothalamus. Moreover, high doses of LD/CD, both of which are themselves catechols, can inhibit the O-methylation of brain catecholamines formed from the LD.

  1. Effects of systemic carbidopa on dopamine synthesis in rat hypothalamus and striatum

    NASA Technical Reports Server (NTRS)

    Kaakkola, S.; Tuomainen, P.; Wurtman, R. J.; Mannisto, P. T.

    1992-01-01

    Significant concentrations of carbidopa (CD) were found in rat hypothalamus, striatum, and in striatal microdialysis efflux after intraperitoneal administration of the drug. Efflux levels peaked one hour after administration of 100 mg/kg at 0.37 micrograms/ml, or about 2% of serum levels. Concurrent CD levels in hypothalamus and striatum were about 2.5% and 1.5%, respectively, of corresponding serum levels. Levels of dopamine and its principal metabolites in striatal efflux were unaffected. The removal of the brain blood by saline perfusion decreased the striatal and hypothalamic CD concentrations only by 33% and 16%, respectively. In other rats receiving both CD and levodopa (LD), brain L-dopa, dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) levels after one hour tended to be proportionate to LD dose. When the LD dose remained constant, increasing the CD dose dose-dependently enhanced L-dopa levels in the hypothalamus and striatum. However dopamine levels did not increase but, in contrast, decreased dose-dependently (although significantly only in the hypothalamus). CD also caused dose-dependent decrease in striatal 3-O-methyldopa (3-OMD) and in striatal and hypothalamic homovanillic acid (HVA), when the LD dose was 50 mg/kg. We conclude that, at doses exceeding 50 mg/kg, sufficient quantities of CD enter the brain to inhibit dopamine formation, especially in the hypothalamus. Moreover, high doses of LD/CD, both of which are themselves catechols, can inhibit the O-methylation of brain catecholamines formed from the LD.

  2. Down-Regulation by Resveratrol of Basic Fibroblast Growth Factor-Stimulated Osteoprotegerin Synthesis through Suppression of Akt in Osteoblasts

    PubMed Central

    Kuroyanagi, Gen; Otsuka, Takanobu; Yamamoto, Naohiro; Matsushima-Nishiwaki, Rie; Nakakami, Akira; Mizutani, Jun; Kozawa, Osamu; Tokuda, Haruhiko

    2014-01-01

    It is firmly established that resveratrol, a natural food compound abundantly found in grape skins and red wine, has beneficial properties for human health. In the present study, we investigated the effect of basic fibroblast growth factor (FGF-2) on osteoprotegerin (OPG) synthesis in osteoblast-like MC3T3-E1 cells and whether resveratrol affects the OPG synthesis. FGF-2 stimulated both the OPG release and the expression of OPG mRNA. Resveratrol significantly suppressed the FGF-2-stimulated OPG release and the mRNA levels of OPG. SRT1720, an activator of SIRT1, reduced the FGF-2-induced OPG release and the OPG mRNA expression. PD98059, an inhibitor of upstream kinase activating p44/p42 mitogen-activated protein (MAP) kinase, had little effect on the FGF-2-stimulated OPG release. On the other hand, SB203580, an inhibitor of p38 MAP kinase, SP600125, an inhibitor of stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), and Akt inhibitor suppressed the OPG release induced by FGF-2. Resveratrol failed to affect the FGF-2-induced phosphorylation of p44/p42 MAP kinase, p38 MAP kinase or SAPK/JNK. The phosphorylation of Akt induced by FGF-2 was significantly suppressed by resveratrol or SRT1720. These findings strongly suggest that resveratrol down-regulates FGF-2-stimulated OPG synthesis through the suppression of the Akt pathway in osteoblasts and that the inhibitory effect of resveratrol is mediated at least in part by SIRT1 activation. PMID:25290095

  3. Genetic and pharmacological correction of aberrant dopamine synthesis using patient iPSCs with BH4 metabolism disorders.

    PubMed

    Ishikawa, Taizo; Imamura, Keiko; Kondo, Takayuki; Koshiba, Yasushi; Hara, Satoshi; Ichinose, Hiroshi; Furujo, Mahoko; Kinoshita, Masako; Oeda, Tomoko; Takahashi, Jun; Takahashi, Ryosuke; Inoue, Haruhisa

    2016-12-01

    Dopamine (DA) is a neurotransmitter in the brain, playing a central role in several disease conditions, including tetrahydrobiopterin (BH4) metabolism disorders and Parkinson's disease (PD). BH4 metabolism disorders present a variety of clinical manifestations including motor disturbance via altered DA metabolism, since BH4 is a cofactor for tyrosine hydroxylase (TH), a rate-limiting enzyme for DA synthesis. Genetically, BH4 metabolism disorders are, in an autosomal recessive pattern, caused by a variant in genes encoding enzymes for BH4 synthesis or recycling, including 6-pyruvoyltetrahydropterin synthase (PTPS) or dihydropteridine reductase (DHPR), respectively. Although BH4 metabolism disorders and its metabolisms have been studied, it is unclear how gene variants cause aberrant DA synthesis in patient neurons. Here, we generated induced pluripotent stem cells (iPSCs) from BH4 metabolism disorder patients with PTPS or DHPR variants, corrected the gene variant in the iPSCs using the CRISPR/Cas9 system, and differentiated the BH4 metabolism disorder patient- and isogenic control iPSCs into midbrain DA neurons. We found that by the gene correction, the BH4 amount, TH protein level and extracellular DA level were restored in DA neuronal culture using PTPS deficiency iPSCs. Furthermore, the pharmacological correction by BH4 precursor sepiapterin treatment also improved the phenotypes of PTPS deficiency. These results suggest that patient iPSCs with BH4 metabolism disorders provide an opportunity for screening substances for treating aberrant DA synthesis-related disorders. © The Author 2016. Published by Oxford University Press.

  4. Extremely low-frequency electromagnetic field exposure during chronic morphine treatment strengthens downregulation of dopamine D2 receptors in rat dorsal hippocampus after morphine withdrawal.

    PubMed

    Wang, Xiusong; Liu, Yadong; Lei, Yanlin; Zhou, Dongming; Fu, Yu; Che, Yi; Xu, Ruchang; Yu, Hualin; Hu, Xintian; Ma, Yuanye

    2008-03-15

    The aim of this study was to investigate the effect of extremely low-frequency electromagnetic field (ELF-EMF) exposure during morphine treatment on dopamine D2 receptor (D2R) density in the rat dorsal hippocampus following withdrawal. Rats were exposed to ELF-EMF (20 Hz, 14 mT) or sham exposed for 1h per day before injection of morphine (10mg/kg, i.p.) once daily for 12 days. The saline control group was sham exposed for the same period. Immunohistochemistry was used to detect the density of D2Rs on the 1st, 3rd and 5th morphine withdrawal days. The results showed that the density of D2Rs in sham-exposed morphine-treated rats on the 1st and 3rd days of morphine withdrawal was significantly lower than that of the saline control group. The ELF-EMF-exposed morphine group also exhibited a significantly lower density of D2Rs on the 1st and 3rd withdrawal days relative to the sham-exposed morphine group. However, the D2R density in both groups tended to recover as morphine withdrawal days increased. The results suggest that dorsal hippocampal D2Rs are sensitive to morphine withdrawal and that this is potentiated by ELF-EMF pre-exposure during morphine treatment.

  5. Chinese Medicine Formula “Jian-Pi-Zhi-Dong Decoction” Attenuates Tourette Syndrome via Downregulating the Expression of Dopamine Transporter in Mice

    PubMed Central

    Wang, Dao-han; Li, Wei; Liu, Xiao-fang; Zhang, Jin-ming; Wang, Su-mei

    2013-01-01

    Jian-Pi-Zhi-Dong Decoction (JPZDD) is dedicated to the treatment for Tourette syndrome (TS) with the guidance of the theories of Traditional Chinese Medicine (TCM). This study aims to investigate the expression of dopamine transporter (DAT) in the striatum and stereotyped behavior of TS mice model by intervention of JPZDD. Mice were induced by 3,3′-iminodipropionitrile (IDPN, 350 mg kg−1 day−1, i.p.) for 7 days and divided into 4 groups (n = 20, each): control and IDPN groups were gavaged with saline and the remaining 2 groups with Tiapride (Tia, 50 mg kg−1 day−1) and JPZDD (20 g kg−1 day−1), respectively. The results showed that the scores of stereotyped behavior in IDPN+JPZDD group were significantly reduced. A noticeably increased 11C-β-CFT binding at bilateral striatum was observed after administration of JPZDD versus that of IDPN or Tia. Immunohistochemistry and in situ hybridization studies manifested higher levels of DAT protein and mRNA in IDPN+JPZDD group. These findings not only demonstrated that JPZDD could effectively inhibit the abnormal behaviors of TS mice model, but also increase the level of DAT in striatum. Therefore, JPZDD could be one of potential treatments of patients with TS. PMID:23431337

  6. Chinese Medicine Formula "Jian-Pi-Zhi-Dong Decoction" Attenuates Tourette Syndrome via Downregulating the Expression of Dopamine Transporter in Mice.

    PubMed

    Wang, Dao-Han; Li, Wei; Liu, Xiao-Fang; Zhang, Jin-Ming; Wang, Su-Mei

    2013-01-01

    Jian-Pi-Zhi-Dong Decoction (JPZDD) is dedicated to the treatment for Tourette syndrome (TS) with the guidance of the theories of Traditional Chinese Medicine (TCM). This study aims to investigate the expression of dopamine transporter (DAT) in the striatum and stereotyped behavior of TS mice model by intervention of JPZDD. Mice were induced by 3,3'-iminodipropionitrile (IDPN, 350 mg kg(-1) day(-1), i.p.) for 7 days and divided into 4 groups (n = 20, each): control and IDPN groups were gavaged with saline and the remaining 2 groups with Tiapride (Tia, 50 mg kg(-1) day(-1)) and JPZDD (20 g kg(-1) day(-1)), respectively. The results showed that the scores of stereotyped behavior in IDPN+JPZDD group were significantly reduced. A noticeably increased (11)C-β-CFT binding at bilateral striatum was observed after administration of JPZDD versus that of IDPN or Tia. Immunohistochemistry and in situ hybridization studies manifested higher levels of DAT protein and mRNA in IDPN+JPZDD group. These findings not only demonstrated that JPZDD could effectively inhibit the abnormal behaviors of TS mice model, but also increase the level of DAT in striatum. Therefore, JPZDD could be one of potential treatments of patients with TS.

  7. One-pot synthesis of dendritic Pt3Ni nanoalloys as nonenzymatic electrochemical biosensors with high sensitivity and selectivity for dopamine detection.

    PubMed

    Gao, Ge; Zhang, Zongkui; Wang, Kai; Yuan, Qiang; Wang, Xun

    2017-08-10

    Preparation of Pt-based nanocatalysts with high catalytic activity and exploration of their novel applications have attracted significant interest in the nanoscale field. Herein, we report a facile synthesis of dendritic Pt3Ni nanoalloys and their applications for electrochemical nonenzymatic dopamine biosensors. As a result of their unique structure, the dendritic Pt3Ni nanoalloys show high electrocatalytic activity towards dopamine oxidation. Amperometric dopamine biosensors based on dendritic Pt3Ni nanoalloy microelectrode exhibit a wide linear detection ranges from 0.5 μM to 250 μM with ultrahigh sensitivity, fast response, and excellent selectivity at a potential of 0.3 V in a 0.1 M phosphate buffered solution (pH = 7.2). The limit of detection on dendritic Pt3Ni nanoalloy microelectrodes can decrease down to 10 nM, which is the least concentration of dopamine in serum samples with a value of sensitivity up to 4.6 μA mg(-1)Pt cm(-2). This study shows an effective approach for the development of dendritic Pt3Ni nanoalloys as electrocatalysts for electrochemical nonenzymatic dopamine biosensors.

  8. Agonist and antagonist effects of aripiprazole on D₂-like receptors controlling rat brain dopamine synthesis depend on the dopaminergic tone.

    PubMed

    Ma, Guo Fen; Raivio, Noora; Sabrià, Josefa; Ortiz, Jordi

    2014-10-31

    The atypical antipsychotic drug aripiprazole binds with high affinity to a number of G protein coupled receptors, including dopamine D₂ receptors, where its degree of efficacy as a partial agonist remains controversial. We examined the properties of aripiprazole at D₂-like autoreceptors by monitoring the changes of dopamine synthesis in adult rat brain striatal minces incubated ex vivo. The effects of the dopaminergic tone on the properties of aripiprazole were assayed by comparing a basal condition (2 mM K(+), low dopaminergic tone) and a stimulated condition (15 mM K(+), where dopamine release mimics a relatively higher dopaminergic tone). We also used 2 reference compounds: quinpirole showed a clear agonistic activity and preclamol (S-(-)-PPP) showed partial agonism under both basal and stimulated conditions. Aripiprazole under the basal condition acted as an agonist at D₂-like autoreceptors and fully activated them at about 10 nM, inhibiting dopamine synthesis similarly to quinpirole. Higher concentrations of aripiprazole had effects not restricted to D₂-like autoreceptor activation. Under the stimulated (15 mM K(+)) condition, nanomolar concentrations of aripiprazole failed to decrease dopamine synthesis but could totally block the effect of quinpirole. Under high dopaminergic tone, aripiprazole acts as a D₂-like autoreceptor antagonist rather than as an agonist. These data show that, ex vivo, alteration of dopaminergic tone by depolarization affects the actions of aripiprazole on D₂-like autoreceptors. Such unusual effects were not seen with the typical partial agonist preclamol and are consistent with the hypothesis that aripiprazole is a functionally selective D₂R ligand. © The Author 2015. Published by Oxford University Press on behalf of CINP.

  9. Design and synthesis of a piperazinylalkylisoxazole library for subtype selective dopamine receptor ligands.

    PubMed

    Cha, Mi Young; Choi, Byung Chul; Kang, Kyung Ho; Pae, Ae Nim; Choi, Kung Il; Cho, Yong Seo; Koh, Hun Yeong; Lee, Hee-Yoon; Jung, Daeyoung; Kong, Jae Yang

    2002-05-20

    A piperazinylbutylisoxazole libary was designed, synthesized and screened for the binding affinities to dopamine D2, D3, and D4 receptors. Several ligands were identified to possess high binding affinity and selectivity for the D3 and D4 receptors over the D2 receptor. Compounds 6s and 6t showed K(i) values of 2.6 nM and 3.9 nM for the D3 receptor with 46- and 50-fold selectivity over the D2 receptor, respectively.

  10. Cooperation of taurine uptake and dopamine D1 receptor activation facilitates the induction of protein synthesis-dependent late LTP.

    PubMed

    Suárez, Luz M; Bustamante, Julián; Orensanz, Luís M; Martín del Río, Rafael; Solís, José M

    2014-04-01

    Co-activation of NMDA and dopamine receptors is required for the induction of the late phase of LTP (L-LTP) that is dependent on new protein synthesis. Other neuromodulatory substances may also contribute to this process. Here, we examined whether taurine is one of the neuromodulators contributing to L-LTP induction, since it is known that taurine uptake induces a long-lasting synaptic potentiation dependent on protein synthesis, and taurine uptake inhibition blocks L-LTP induced by tetanization. Experiments were conducted using rat hippocampal slices where field synaptic potentials were evoked and recorded in CA3-CA1 synapses. Taurine (1 mM) applied 10 min before a high frequency stimulation (HFS) train converted a transitory early-LTP (E-LTP) into an L-LTP dependent on protein synthesis. This taurine effect was blocked by a taurine uptake inhibitor. A facilitation of L-LTP induction was also obtained by pre-application of SKF38393, a D1/D5 dopamine receptor (D1R) agonist. In this case, LTP facilitation was not affected by the taurine uptake inhibitor. Nevertheless, when taurine and SKF38393 were simultaneously pre-applied at a concentration that individually did not modify E-LTP, they produced a synergistic mechanism that facilitated the induction of L-LTP with a sole HFS train. This facilitation of L-LTP was blocked by inhibiting either taurine uptake or D1R activation. Taurine and SKF38393 activated different signaling pathways to transform E-LTP into L-LTP. Taurine-induced L-LTP facilitation required MAPK activation, while D1R-agonist-induced facilitation depended mainly on PKA activation and partially on MAPK activation. On the other hand, the synergistic mechanisms induced by the cooperative action of taurine and SKF38393 were impaired by inhibitors against MAPK, PKA and PI3-K. This pharmacological profile resembles that displayed by L-LTP induced by three HFS trains at 10-min intervals. These results indicate that taurine uptake is necessary and

  11. Synthesis and carbonic anhydrase inhibitory properties of sulfamides structurally related to dopamine.

    PubMed

    Aksu, Kadir; Nar, Meryem; Tanc, Muhammet; Vullo, Daniela; Gülçin, Ilhami; Göksu, Süleyman; Tümer, Ferhan; Supuran, Claudiu T

    2013-06-01

    A series of novel sulfamides incorporating the dopamine scaffold were synthesized. Reaction of amines and tert-butyl-alcohol/benzyl alcohol in the presence of chlorosulfonyl isocyanate (CSI) afforded sulfamoyl carbamates, which were converted to the title compounds by treatment with trifluoroacetic acid or by palladium-catalyzed hydrogenolysis. Inhibition of six α-carbonic anhydrases (CAs, EC 4.2.1.1), that is, CA I, CA II, CA VA, CA IX, CA XII and CA XIV, and two β-CAs from Candida glabrata (CgCA) and Mycobacterium tuberculosis (Rv3588) with these sulfamides was investigated. All CA isozymes were inhibited in the low micromolar to nanomolar range by the dopamine sulfamide analogues. K(i)s were in the range of 0.061-1.822 μM for CA I, 1.47-2.94 nM for CA II, 2.25-3.34 μM for CA VA, 0.041-0.37 μM for CA IX, 0.021-1.52 μM for CA XII, 0.007-0.219 μM for CA XIV, 0.35-5.31 μM for CgCA and 0.465-4.29 μM for Rv3588. The synthesized sulfamides may lead to inhibitors targeting medicinally relevant CA isoforms with potential applications as antiepileptic, antiobesity antitumor agents or anti-infective.

  12. Synthesis and characterization of selective dopamine D₂ receptor ligands using aripiprazole as the lead compound.

    PubMed

    Vangveravong, Suwanna; Zhang, Zhanbin; Taylor, Michelle; Bearden, Melissa; Xu, Jinbin; Cui, Jinquan; Wang, Wei; Luedtke, Robert R; Mach, Robert H

    2011-06-01

    A series of compounds structurally related to aripiprazole (1), an atypical antipsychotic and antidepressant used clinically for the treatment of schizophrenia, bipolar disorder, and depression, have been prepared and evaluated for affinity at D(₂-like) dopamine receptors. These compounds also share structural elements with the classical D(₂-like) dopamine receptor antagonists, haloperidol, N-methylspiperone, domperidone and benperidol. Two new compounds, 7-(4-(4-(2-methoxyphenyl)piperazin-1-yl)butoxy)-3,4-dihydroquinolin-2(1H)-one oxalate (6) and 7-(4-(4-(2-(2-fluoroethoxy)phenyl)piperazin-1-yl)butoxy)-3,4-dihydroquinolin-2(1H)-one oxalate (7) were found to (a) bind to the D₂ receptor subtype with high affinity (K(i) values < 0.3 nM), (b) exhibit >50-fold D₂ versus D₃ receptor binding selectivity and (c) be partial agonists at both the D₂ and D₃ receptor subtype. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Synthesis and characterization of selective dopamine D2 receptor ligands using aripiprazole as the lead compound

    PubMed Central

    Vangveravong, Suwanna; Zhang, Zhanbin; Taylor, Michelle; Bearden, Melissa; Xu, Jinbin; Cui, Jinquan; Wang, Wei; Luedtke, Robert R.; Mach, Robert H.

    2011-01-01

    A series of compounds structurally related to aripiprazole (1), an atypical antipsychotic and antidepressant used clinically for the treatment of schizophrenia, bipolar disorder, and depression, have been prepared and evaluated for affinity at D2-like dopamine receptors. These compounds also share structural elements with the classical D2-like dopamine receptor antagonists, haloperidol, N-methylspiperone, domperidone and benperidol. Two new compounds, 7-(4-(4-(2-methoxyphenyl)piperazin-1-yl)butoxy)-3,4-dihydroquinolin-2(1H)-one oxalate (6) and 7-(4-(4-(2-(2-fluoroethoxy)phenyl)piperazin-1-yl)butoxy)-3,4-dihydroquinolin-2(1H)-one oxalate (7) were found to (a) bind to the D2 receptor subtype with high affinity (Ki values <0.3 nM), (b) exhibit >50-fold D2 versus D3 receptor binding selectivity and (c) be partial agonists at both the D2 and D3 receptor subtype. PMID:21536445

  14. A thyroid hormone analogue, triiodothyroacetic acid, corrects corticosteroid-downregulated collagen synthesis.

    PubMed

    Yazdanparast, Parviz; Carlsson, Bo; Oikarinen, Aarne; Risteli, Juha; Faergemann, Jan

    2004-05-01

    The aim of this study was to compare the change in collagen synthesis between topical treatments with two doses of triiodothyroacetic acid (TRIAC), a thyroid hormone analogue, and placebo, after pretreatment with topical betamethasone 17-valerate (BM). Eighteen healthy volunteers were pretreated with BM on abdominal skin for 3 days, and were then treated for 14 days with a cream containing TRIAC (0.03% or 0.1%) or a placebo cream. Collagen production was assessed by quantifying the amino terminal propeptides of human type I and type III procollagen (PINP and PIIINP) in fluids from suction-induced blisters on the treated skin. Three days of treatment with BM led to an average reduction of PINP of 70% and of PIIINP of 50%. Seven days after treatment, the median increase in PINP was 230% (p = 0.03) in the Triac 0.03% group, 148% (p = 0.2) in the TRIAC 0.1% and 5% in the placebo group. The median increase in PINP in the skin area from the start of treatment to the end of treatment was 521% (p = 0.06) in the TRIAC 0.03% group, 339% (p = 0.2) in the TRIAC 0.1% group, and 55% in the placebo group (the p values are related to baseline). Seven days after treatment, the median increase in PIIINP was 24% (p = 0.6) in the Triac 0.03% group, 23% (p = 0.6) in the TRIAC 0.1% group, and -12% in the placebo group. The median increase in PIIINP in the skin area from the start of treatment to the end of treatment was 137% (p = 0.7) in the TRIAC 0.03% group, 230% (p = 0.9) in the TRIAC 0.1% group and 58% in the placebo group (the p values are related to baseline). Histologic examinations of sections from punch biopsies taken at the end of the treatment showed more thickened collagen fibers and increased density of PINP-producing dermal fibroblasts in the TRIAC groups compared to the placebo group. The result suggests a potential role for TRIAC-containing cream concomitant with anti-inflammatory topical treatment with potent glucocorticoids to prevent their suppressive activity on

  15. The human testis-determining factor SRY localizes in midbrain dopamine neurons and regulates multiple components of catecholamine synthesis and metabolism.

    PubMed

    Czech, Daniel P; Lee, Joohyung; Sim, Helena; Parish, Clare L; Vilain, Eric; Harley, Vincent R

    2012-07-01

    The male gender is determined by the sex-determining region on the Y chromosome (SRY) transcription factor. The unexpected action of SRY in the control of voluntary movement in male rodents suggests a role in the regulation of dopamine transmission and dopamine-related disorders with gender bias, such as Parkinson's disease. We investigated SRY expression in the human brain and function in vitro. SRY immunoreactivity was detected in the human male, but not female substantia nigra pars compacta, within a sub-population of tyrosine hydroxylase (TH) positive neurons. SRY protein also co-localized with TH positive neurons in the ventral tegmental area, and with GAD-positive neurons in the substantia nigra pars reticulata. Retinoic acid-induced differentiation of human precursor NT2 cells into dopaminergic cells increased expression of TH, NURR1, D2 R and SRY. In the human neuroblastoma cell line, M17, SRY knockdown resulted in a reduction in TH, DDC, DBH and MAO-A expression; enzymes which control dopamine synthesis and metabolism. Conversely, SRY over-expression increased TH, DDC, DBH, D2 R and MAO-A levels, accompanied by increased extracellular dopamine levels. A luciferase assay demonstrated that SRY activated a 4.6 kb 5' upstream regulatory region of the human TH promoter/nigral enhancer. Combined, these results suggest that SRY plays a role as a positive regulator of catecholamine synthesis and metabolism in the human male midbrain. This ancillary genetic mechanism might contribute to gender bias in fight-flight behaviours in men or their increased susceptibility to dopamine disorders, such as Parkinson's disease and schizophrenia.

  16. Synthesis and radioiodination of ergoline derivatives: potential in-vivo dopamine receptor site mapping radiopharmaceuticals

    SciTech Connect

    Mikhail, E.A.

    1985-01-01

    The need of a dopamine-receptor based radiopharmaceutical for brain imaging is apparent. If such an agent is made available to physicians, it could provide means for detecting brain tumors, and diagnose such mental disorders as parkinsonism, schizophrenia and psychosis. Currently, such agents are yet to be discovered. Procedures were developed to synthesize and label four ergoline derivatives which could potentially exhibit affinity to dopamine receptors. Labelling with /sup 125/I was accomplished in some cases by displacing a suitably positioned leaving group with /sup 125/I-anion, while in other cases iodine exchange procedures were utilized. Formulations of the labeled derivatives were achieved via the formation of their water soluble tartarate salts. Biodistribution studies in mature Sprague-Dawley rats showed that of the four radioactive compounds injected, the highest uptake in the brain and adrenals was achieved with 8 ..beta..-(I-125)-iodomethyl-6-propylergoline. In addition, high target/nontarget ratios were obtained with the above mentioned compound. On the other hand, the least brain and adrenal uptake as well as the lowest target/nontarget ratios were exhibited by 8 ..beta..-(I-125)-(p-iodobenzenesulfonyl)-lysergol presumably due to its in-vivo instability. A comparative biodistribution study for ergoline derivatives and N-isopropyl-(I-123)-p-iodoamphetamine was conducted. The biodistribution studies showed that the brain to blood ratio for the ergoline derivative 8 ..beta..-(I-125)-iodomethyl-6-propylergoline to be very close to that for /sup 125/I-IMP at 1 minute after dose administration. However after 15 minutes the brain/blood ratio of compound XLVI was half the value of /sup 123/I-IMP. Different mechanisms of brain influx and efflux are known to occur with the amphetamine and ergoline derivatives.

  17. Sensitivity of kinetic macro parameters to changes in dopamine synthesis, storage, and metabolism: a simulation study for [¹⁸F]FDOPA PET by a model with detailed dopamine pathway.

    PubMed

    Matsubara, Keisuke; Watabe, Hiroshi; Kumakura, Yoshitaka; Hayashi, Takuya; Endres, Christopher J; Minato, Kotaro; Iida, Hidehiro

    2011-08-01

    Quantitative interpretation of brain [¹⁸F]FDOPA PET data has been made possible by several kinetic modeling approaches, which are based on different assumptions about complex [¹⁸F]FDOPA metabolic pathways in brain tissue. Simple kinetic macro parameters are often utilized to quantitatively evaluate metabolic and physiological processes of interest, which may include DDC activity, vesicular storage, and catabolism from (18) F-labeled dopamine to DOPAC and HVA. A macro parameter most sensitive to the changes of these processes would be potentially beneficial to identify impaired processes in a neurodegenerative disorder such as Parkinson's disease. The purpose of this study is a systematic comparison of several [¹⁸F]FDOPA macro parameters in terms of sensitivities to process-specific changes in simulated time-activity curve (TAC) data of [¹⁸F]FDOPA PET. We introduced a multiple-compartment kinetic model to simulate PET TACs with physiological changes in the dopamine pathway. TACs in the alteration of dopamine synthesis, storage, and metabolism were simulated with a plasma input function obtained by a non-human primate [¹⁸F]FDOPA PET study. Kinetic macro parameters were calculated using three conventional linear approaches (Gjedde-Patlak, Logan, and Kumakura methods). For simulated changes in dopamine storage and metabolism, the slow clearance rate (k(loss) ) as calculated by the Kumakura method showed the highest sensitivity to these changes. Although k(loss) performed well at typical ROI noise levels, there was large bias at high noise level. In contrast, for simulated changes in DDC activity it was found that K(i) and V(T), estimated by Gjedde-Patlak and Logan method respectively, have better performance than k(loss).

  18. The ligand binding ability of dopamine D1 receptors synthesized using a wheat germ cell-free protein synthesis system with liposomes.

    PubMed

    Arimitsu, Eiji; Ogasawara, Tomio; Takeda, Hiroyuki; Sawasaki, Tatsuya; Ikeda, Yoshio; Hiasa, Yoichi; Maeyama, Kazutaka

    2014-12-15

    G-protein coupled receptors (GPCRs) share a common seven-transmembrane topology and mediate cellular responses to a variety of extracellular signals. However, structural and functional approaches to GPCRs have often been limited by the difficulty of producing a sufficient amount of receptor protein using conventional expression systems. We synthesized human dopamine D1 receptors using a wheat cell-free protein synthesis system with liposomes and then analyzed their receptor binding ability. We determined the specific binding of [(3)H]SCH23390 to the synthesized receptors generated from a cell-free protein synthesis system or rat striatal membranes. From Scatchard plot analysis, the dissociation constant (Kd) and the maximum density (Bmax) of the synthesized receptors were 6.61±0.06 nM and 1.85±0.05 pmol/mg protein, respectively. The same analysis for rat striatal membrane gave a Kd of 2.67±0.05 nM and Bmax of 0.70±0.10 pmol/mg protein. Using a competition binding assay, Ki values of antagonists, SCH23390, LE300 and SKF83566, for the synthetic receptors were the same as those for rat striatal membranes, but Ki values of agonists, A68930, SKF38393 and dopamine, were 5-17 fold higher than those for rat striatal membranes. These results suggest that the dopamine D1 receptors synthesized in liposomes have a functional binding capacity. The different patterns of binding of antagonists and agonists to the synthetic receptors and rat striatal membranes indicate that G proteins are involved in agonist binding to dopamine D1 receptors. The cell-free protein synthesis method with liposomes will be invaluable for the functional analysis of GPCRs.

  19. Downregulated Translation Initiation Signaling Predisposes Low-Birth-Weight Neonatal Pigs to Slower Rates of Muscle Protein Synthesis.

    PubMed

    Chen, Ying; McCauley, Sydney R; Johnson, Sally E; Rhoads, Robert P; El-Kadi, Samer W

    2017-01-01

    Low-birth-weight (LBWT) neonates experience restricted muscle growth in their perinatal life. Our aim was to investigate the mechanisms that contribute to slower skeletal muscle growth of LBWT neonatal pigs. Twenty-four 1-day old male LBWT (816 ± 55 g) and normal-birth-weight (NBWT; 1,642 ± 55 g) littermates (n = 12) were euthanized to collect blood and longissimus dorsi (LD) muscle subsamples. Plasma glucose, insulin, and insulin-like growth factor-I (IGF-I) were lower in LBWT compared with NBWT pigs. Muscle IGF-I mRNA expression were lower in LBWT than NBWT pigs. However, IGF-I receptor mRNA and protein abundance was greater in LD of LBWT pigs. Abundance of myostatin and its receptors, and abundance and phosphorylation of smad3 were lower in LBWT LD by comparison with NBWT LD. Abundance of eukaryotic initiation factor (eIF) 4E binding protein 1 and mitogen-activated protein kinase-interacting kinases was lower in muscle of LBWT pigs compared with NBWT siblings, while eIF4E abundance and phosphorylation did not differ between the two groups. Furthermore, phosphorylation of ribosomal protein S6 kinase 1 (S6K1) was less in LBWT muscle, possibly due to lower eIF3e abundance. In addition, abundance and phosphorylation of eIF4G was reduced in LBWT pigs by comparison with NBWT littermates, suggesting translation initiation complex formation is compromised in muscle of LBWT pigs. In conclusion, diminished S6K1 activation and translation initiation signaling are likely the major contributors to impaired muscle growth in LBWT neonatal pigs. The upregulated IGF-I R expression and downregulated myostatin signaling seem to be compensatory responses for the reduction in protein synthesis signaling.

  20. Modulation of impulsivity and reward sensitivity in intertemporal choice by striatal and midbrain dopamine synthesis in healthy adults.

    PubMed

    Smith, Christopher T; Wallace, Deanna L; Dang, Linh C; Aarts, Esther; Jagust, William J; D'Esposito, Mark; Boettiger, Charlotte A

    2016-03-01

    Converging evidence links individual differences in mesolimbic and mesocortical dopamine (DA) to variation in the tendency to choose immediate rewards ("Now") over larger, delayed rewards ("Later"), or "Now bias." However, to date, no study of healthy young adults has evaluated the relationship between Now bias and DA with positron emission tomography (PET). Sixteen healthy adults (ages 24-34 yr; 50% women) completed a delay-discounting task that quantified aspects of intertemporal reward choice, including Now bias and reward magnitude sensitivity. Participants also underwent PET scanning with 6-[(18)F]fluoro-l-m-tyrosine (FMT), a radiotracer that measures DA synthesis capacity. Lower putamen FMT signal predicted elevated Now bias, a more rapidly declining discount rate with increasing delay time, and reduced willingness to accept low-interest-rate delayed rewards. In contrast, lower FMT signal in the midbrain predicted greater sensitivity to increasing magnitude of the Later reward. These data demonstrate that intertemporal reward choice in healthy humans varies with region-specific measures of DA processing, with regionally distinct associations with sensitivity to delay and to reward magnitude.

  1. One-pot synthesis of magnetite nanorods/graphene composites and its catalytic activity toward electrochemical detection of dopamine.

    PubMed

    Salamon, J; Sathishkumar, Y; Ramachandran, K; Lee, Yang Soo; Yoo, Dong Jin; Kim, Ae Rhan; Gnana Kumar, G

    2015-02-15

    Magnetite (Fe3O4) nanorods anchored over reduced graphene oxide (rGO) were synthesized through a one-pot synthesis method, where the reduction of GO and in-situ generation of Fe3O4 nanorods occurred concurrently. The average head and tail diameter of Fe3O4 nanorods anchored over the rGO matrix are found to be 32 and 11 nm, respectively, and morphology, structure and diameter of bare Fe3O4 nanorods were not altered even after the composite formation with rGO. The increased structural disorders and decrement in the sp(2) domains stimulated the high electrical conductivity and extended catalytic active sites for the prepared rGO/Fe3O4 nanocomposite. The constructed rGO/Fe3O4/GCE sensor exhibited excellent electrocatalytic activity toward the electrooxidation of dopamine (DA) with a quick response time of 6s, a wide linear range between 0.01 and 100.55 µM, high sensitivity of 3.15 µA µM(-1) cm(-2) and a lower detection limit of 7 nM. Furthermore, the fabricated sensor exhibited a practical applicability in the quantification of DA in urine samples with an excellent recovery rate. The excellent electroanalytical performances and straight-forward, surfactant and template free preparation method construct the rGO/Fe3O4 composite as an extremely promising material for the diagnosis of DA related diseases in biomedical applications.

  2. Modulation of impulsivity and reward sensitivity in intertemporal choice by striatal and midbrain dopamine synthesis in healthy adults

    PubMed Central

    Smith, Christopher T.; Wallace, Deanna L.; Dang, Linh C.; Aarts, Esther; Jagust, William J.; D'Esposito, Mark

    2015-01-01

    Converging evidence links individual differences in mesolimbic and mesocortical dopamine (DA) to variation in the tendency to choose immediate rewards (“Now”) over larger, delayed rewards (“Later”), or “Now bias.” However, to date, no study of healthy young adults has evaluated the relationship between Now bias and DA with positron emission tomography (PET). Sixteen healthy adults (ages 24–34 yr; 50% women) completed a delay-discounting task that quantified aspects of intertemporal reward choice, including Now bias and reward magnitude sensitivity. Participants also underwent PET scanning with 6-[18F]fluoro-l-m-tyrosine (FMT), a radiotracer that measures DA synthesis capacity. Lower putamen FMT signal predicted elevated Now bias, a more rapidly declining discount rate with increasing delay time, and reduced willingness to accept low-interest-rate delayed rewards. In contrast, lower FMT signal in the midbrain predicted greater sensitivity to increasing magnitude of the Later reward. These data demonstrate that intertemporal reward choice in healthy humans varies with region-specific measures of DA processing, with regionally distinct associations with sensitivity to delay and to reward magnitude. PMID:26683066

  3. Facile synthesis of hexagonal-shaped polypyrrole self-assembled particles for the electrochemical detection of dopamine

    NASA Astrophysics Data System (ADS)

    Lee, Chung-Yi; Hsu, Di-Yao; Prasannan, Adhimoorthy; Kalaivani, Raman; Hong, Po-Da

    2016-02-01

    Nanomaterials have been used as an electroactive medium to enhance the efficiency of bio/chemical sensors, primarily when synergy is reached upon mixing different materials. In this study, we report on the facile synthesis of hexagonal-shaped plate-like polypyrrole (PPY-IC) prepared through inclusion polymerization of the host-guest pyrrole monomeric inclusion complex of β-cyclodextrin (β-CD) to be used in the detection of the neurotransmitter dopamine (DA). The amount of the monomer complex plays a crucial role in the fabrication of well-defined hexagonal-shaped PPY-IC through intermolecular interactions such as π-π interactions and hydrogen bonding between the β-CD and PPY. The microstructure and morphology of the PPY-IC were examined by using various analytical techniques and a tentative mechanism for the growth process proposed which elucidates the formation of the hierarchical structure of the PPY-IC. Cyclo-voltammetry was performed with a PPY-IC modified glassy carbon electrode (GCE) for the electrochemical detection of DA. The concepts behind the novel architecture of the PPY-IC modified electrodes have potential for the production of materials to be used in electrochemical sensors and biosensors.

  4. Synthesis of glycosyl derivatives as dopamine prodrugs: interaction with glucose carrier GLUT-1.

    PubMed

    Fernández, Caridad; Nieto, Ofelia; Fontenla, José Angel; Rivas, Emilia; de Ceballos, María L; Fernández-Mayoralas, Alfonso

    2003-03-07

    Glucosyl dopamine (DA) derivatives may represent a new class of DA prodrugs that would interact with glucose transporter GLUT-1, present in the blood-brain barrier, and generate DA in the brain. Therefore, compounds bearing the sugar moiety linked to either the amino group or the catechol ring of DA through amide, ester, carbamate, peptide or glycosidic bonds were synthesized. The behavior of the compounds as prodrugs was monitored in different media and the affinity of the glycoconjugates for the glucose carrier GLUT-1 using human erythrocytes was also studied. Most of the compounds were markedly stable in buffer and plasma, and several compounds released DA when incubated with brain extracts and the rate was related to the bond linking DA with glucose. The new glucosyl conjugates substituted at the C-6 position of the sugar were more potent inhibitors of glucose transport when compared to C-1 and C-3 substituted derivatives. This work provides structure-activity information about the interaction of substituted glucose with the GLUT-1 transporter.

  5. 2'-substituted analogs of cocaine: synthesis and dopamine transporter binding potencies.

    PubMed

    el-Moselhy, T F; Avor, K S; Basmadjian, G P

    2001-09-01

    A series of 2'-substituted cocaine analogs (4-8) was prepared and evaluated in an in vitro dopamine transporter (DAT) binding assay. Compounds 4-7 were prepared by esterifying the 3 beta-hydroxyl group of ecgonine methyl ester (3) using the appropriate acid chloride in the presence of Et3N and benzene. Compound 3 was obtained from cocaine (1) by hydrolysis using 1N HCl to afford ecgonine.HCl which was subjected to acid catalyzed esterification using methanol saturated with HCl gas. Compound 8 was obtained by hydrogenation of 7 using H2/Pd-C. The IC50 values were calculated from displacement experiment of the radioligand [3H]WIN-35,428 (2). 2'-Aminococaine (8) showed high binding affinity to the DAT (14- and 1.3-fold more active than cocaine and the radioligand 2, respectively). These results, along with previous results, emphasize the importance of a hydrogen-bond donor group at the 2'-position of cocaine to enhance binding affinity to the DAT.

  6. Oxidative Status of DJ-1-dependent Activation of Dopamine Synthesis through Interaction of Tyrosine Hydroxylase and 4-Dihydroxy-l-phenylalanine (l-DOPA) Decarboxylase with DJ-1*

    PubMed Central

    Ishikawa, Shizuma; Taira, Takahiro; Niki, Takeshi; Takahashi-Niki, Kazuko; Maita, Chinatsu; Maita, Hiroshi; Ariga, Hiroyoshi; Iguchi-Ariga, Sanae M. M.

    2009-01-01

    Parkinson disease (PD) is caused by loss of dopamine, which is synthesized from tyrosine by two enzymes, tyrosine hydroxylase (TH) and 4-dihydroxy-l-phenylalanine decarboxylase (DDC). DJ-1 is a causative gene for the familial form of PD, but little is known about the roles of DJ-1 in dopamine synthesis. In this study, we found that DJ-1 directly bound to TH and DDC and positively regulated their activities in human dopaminergic cells. Mutants of DJ-1 found in PD patients, including heterozygous mutants, lost their activity and worked as dominant-negative forms toward wild-type DJ-1. When cells were treated with H2O2, 6-hydroxydopamine, or 1-methyl-4-phenylpyridinium, changes in activities of TH and DDC accompanied by oxidation of cysteine 106 of DJ-1 occurred. It was found that DJ-1 possessing Cys-106 with SH and SOH forms was active and that DJ-1 possessing Cys-106 with SO2H and SO3H forms was inactive in terms of stimulation of TH and DDC activities. These findings indicate an essential role of DJ-1 in dopamine synthesis and contribution of DJ-1 to the sporadic form of PD. PMID:19703902

  7. Oxidative status of DJ-1-dependent activation of dopamine synthesis through interaction of tyrosine hydroxylase and 4-dihydroxy-L-phenylalanine (L-DOPA) decarboxylase with DJ-1.

    PubMed

    Ishikawa, Shizuma; Taira, Takahiro; Niki, Takeshi; Takahashi-Niki, Kazuko; Maita, Chinatsu; Maita, Hiroshi; Ariga, Hiroyoshi; Iguchi-Ariga, Sanae M M

    2009-10-16

    Parkinson disease (PD) is caused by loss of dopamine, which is synthesized from tyrosine by two enzymes, tyrosine hydroxylase (TH) and 4-dihydroxy-L-phenylalanine decarboxylase (DDC). DJ-1 is a causative gene for the familial form of PD, but little is known about the roles of DJ-1 in dopamine synthesis. In this study, we found that DJ-1 directly bound to TH and DDC and positively regulated their activities in human dopaminergic cells. Mutants of DJ-1 found in PD patients, including heterozygous mutants, lost their activity and worked as dominant-negative forms toward wild-type DJ-1. When cells were treated with H(2)O(2), 6-hydroxydopamine, or 1-methyl-4-phenylpyridinium, changes in activities of TH and DDC accompanied by oxidation of cysteine 106 of DJ-1 occurred. It was found that DJ-1 possessing Cys-106 with SH and SOH forms was active and that DJ-1 possessing Cys-106 with SO(2)H and SO(3)H forms was inactive in terms of stimulation of TH and DDC activities. These findings indicate an essential role of DJ-1 in dopamine synthesis and contribution of DJ-1 to the sporadic form of PD.

  8. Nicotine-induced retardation of chondrogenesis through down-regulation of IGF-1 signaling pathway to inhibit matrix synthesis of growth plate chondrocytes in fetal rats

    SciTech Connect

    Deng, Yu; Cao, Hong; Cu, Fenglong; Xu, Dan; Lei, Youying; Tan, Yang; Magdalou, Jacques; Wang, Hui; Chen, Liaobin

    2013-05-15

    Previous studies have confirmed that maternal tobacco smoking causes intrauterine growth retardation (IUGR) and skeletal growth retardation. Among a multitude of chemicals associated with cigarette smoking, nicotine is one of the leading candidates for causing low birth weights. However, the possible mechanism of delayed chondrogenesis by prenatal nicotine exposure remains unclear. We investigated the effects of nicotine on fetal growth plate chondrocytes in vivo and in vitro. Rats were given 2.0 mg/kg·d of nicotine subcutaneously from gestational days 11 to 20. Prenatal nicotine exposure increased the levels of fetal blood corticosterone and resulted in fetal skeletal growth retardation. Moreover, nicotine exposure induced the inhibition of matrix synthesis and down-regulation of insulin-like growth factor 1 (IGF-1) signaling in fetal growth plates. The effects of nicotine on growth plates were studied in vitro by exposing fetal growth plate chondrocytes to 0, 1, 10, or 100 μM of nicotine for 10 days. Nicotine inhibited matrix synthesis and down-regulated IGF-1 signaling in chondrocytes in a concentration-dependent manner. These results suggest that prenatal nicotine exposure induces delayed chondrogenesis and that the mechanism may involve the down-regulation of IGF-1 signaling and the inhibition of matrix synthesis by growth plate chondrocytes. The present study aids in the characterization of delayed chondrogenesis caused by prenatal nicotine exposure, which might suggest a candidate mechanism for intrauterine origins of osteoporosis and osteoarthritis. - Highlights: ► Prenatal nicotine-exposure could induce delayed chondrogenesis in fetal rats. ► Nicotine inhibits matrix synthesis of fetal growth plate chondrocytes. ► Nicotine inhibits IGF-1 signaling pathway in fetal growth plate chondrocytes.

  9. Synthesis and dopamine transporter binding of 2beta-isopropyl ester analogs of cocaine.

    PubMed

    El-Moselhy, Tarek F; Avor, Kwasi S; Basmadjian, Garo P

    2002-02-01

    A series of 2beta-isopropyl ester analogs of cocaine (7-11) was synthesised and evaluated in an in vitro dopamine transporter (DAT) binding assays. Ecgonine HCl (5) was obtained from (-)-cocaine (1) by hydrolysis using 1 N HCl. Acid catalysed esterification of 5 using 2-propanol and HCl gas afforded 2beta-isopropyl ecgonine (6). Compounds 7-9 were obtained via esterification of the 3beta-hydroxyl group of 6 using the appropriate acid chloride. Compound 10 was obtained via selective hydrolysis and re-esterification of 7 using 2-propanol and HCl gas. Compound 11 was obtained by reduction of 9 using H(2)/Pd-C. Compounds 7, 10 and 11 showed high binding affinity to the DAT (as indicated from the inhibition of the binding of [(3)H]WIN 35,428 (3)) with IC(50) values (mean +/- S.E.M.) 208.5 +/- 9.5, 47.43 +/- 1.79 and 11.25 +/- 3.37 nM, respectively). Compound 7 is comparatively as active as cocaine, 10 is ca. fivefold more active than cocaine and 11 is ca. 20-fold more active than cocaine and even twice more active than the radioligand 3. Compound 11, like its methyl ester analog (2' aminococaine), exhibited the highest affinity to the DAT. These results, along with previous results, emphasise the importance of a hydrogen-bond donor group at the 2'-position of cocaine and its isopropyl ester analogs to enhance binding affinity to the DAT.

  10. Human cytomegalovirus miR-US33-5p inhibits viral DNA synthesis and viral replication by down-regulating expression of the host Syntaxin3.

    PubMed

    Guo, Xin; Qi, Ying; Huang, Yujing; Liu, Zhongyang; Ma, Yanping; Shao, Yaozhong; Jiang, Shujuan; Sun, Zhengrong; Ruan, Qiang

    2015-02-13

    During infection with human cytomegalovirus (HCMV), overexpression of hcmv-miR-US33 can inhibit the lytic viral replication and down-regulate US29 mRNA. However, it remains unknown whether inhibition of viral replication by miR-US33 is mediated by down-regulation of expression of US29 or another host gene. Here, we identified the host gene Syntaxin3 (STX3) to be a direct target of hcmv-miR-US33-5p using Hybrid-PCR and luciferase-reporter assays. It was further demonstrated that the levels of STX3 protein were down-regulated in hcmv-miR-US33-5p-overexpressing cells. Experiments with STX3-specific siRNA, or with an inhibitor of hcmv-miR-US33-5p confirmed that hcmv-miR-US33-5p-mediated inhibition of HCMV DNA synthesis and of viral replication are specifically mediated by down-regulation of STX3 expression.

  11. 4-Methylumbelliferone inhibits hyaluronan synthesis by depletion of cellular UDP-glucuronic acid and downregulation of hyaluronan synthase 2 and 3

    SciTech Connect

    Kultti, Anne; Pasonen-Seppaenen, Sanna; Jauhiainen, Marjo; Rilla, Kirsi J.; Kaernae, Riikka; Pyoeriae, Emma; Tammi, Raija H.; Tammi, Markku I.

    2009-07-01

    Hyaluronan accumulation on cancer cells and their surrounding stroma predicts an unfavourable disease outcome, suggesting that hyaluronan enhances tumor growth and spreading. 4-Methylumbelliferone (4-MU) inhibits hyaluronan synthesis and retards cancer spreading in experimental animals through mechanisms not fully understood. These mechanisms were studied in A2058 melanoma cells, MCF-7 and MDA-MB-361 breast, SKOV-3 ovarian and UT-SCC118 squamous carcinoma cells by analysing hyaluronan synthesis, UDP-glucuronic acid (UDP-GlcUA) content, and hyaluronan synthase (HAS) mRNA levels. The maximal inhibition in hyaluronan synthesis ranged 22-80% in the cell lines tested. Active glucuronidation of 4-MU produced large quantities of 4-MU-glucuronide, depleting the cellular UDP-GlcUA pool. The maximal reduction varied between 38 and 95%. 4-MU also downregulated HAS mRNA levels: HAS3 was 84-60% lower in MDA-MB-361, A2058 and SKOV-3 cells. HAS2 was the major isoenzyme in MCF-7 cells and lowered by 81%, similar to 88% in A2058 cells. These data indicate that both HAS substrate and HAS2 and/or HAS3 mRNA are targeted by 4-MU. Despite different target point sensitivities, the reduction of hyaluronan caused by 4-MU was associated with a significant inhibition of cell migration, proliferation and invasion, supporting the importance of hyaluronan synthesis in cancer, and the therapeutic potential of hyaluronan synthesis inhibition.

  12. Stimulus-Dependent Dopamine Release in Attention-Deficit/Hyperactivity Disorder

    ERIC Educational Resources Information Center

    Sikstrom, Sverker; Soderlund, Goran

    2007-01-01

    Attention-deficit/hyperactivity disorder (ADHD) is related to an attenuated and dysfunctional dopamine system. Normally, a high extracellular dopamine level yields a tonic dopaminergic input that down-regulates stimuli-evoked phasic dopamine responses through autoreceptors. Abnormally low tonic extracellular dopamine in ADHD up-regulates the…

  13. Stimulus-Dependent Dopamine Release in Attention-Deficit/Hyperactivity Disorder

    ERIC Educational Resources Information Center

    Sikstrom, Sverker; Soderlund, Goran

    2007-01-01

    Attention-deficit/hyperactivity disorder (ADHD) is related to an attenuated and dysfunctional dopamine system. Normally, a high extracellular dopamine level yields a tonic dopaminergic input that down-regulates stimuli-evoked phasic dopamine responses through autoreceptors. Abnormally low tonic extracellular dopamine in ADHD up-regulates the…

  14. Synthesis of hybrid cellulose nanocomposite bonded with dopamine SiO2/TiO2 and its antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Ramesh, Sivalingam; Kim, Gwang-Hoon; Kim, Jaehwan; Kim, Joo-Hyung

    2015-04-01

    Organic-inorganic hybrid material based cellulose was synthesized by the sol-gel approach. The explosion of activity in this area in the past decade has made tremendous progress in industry or academic both fundamental understanding of sol-gel process and applications of new functionalized hybrid materials. In this present research work, we focused on cellulose-dopamine functionalized SiO2/TiO2 hybrid nanocomposite by sol-gel process. The cellulose-dopamine hybrid nanocomposite was synthesized via γ-aminopropyltriethoxysilane (γ-APTES) coupling agent by in-situ sol-gel process. The chemical structure of cellulose-amine functionalized dopamine bonding to cellulose structure with covalent cross linking hybrids was confirmed by FTIR spectral analysis. The morphological analysis of cellulose-dopamine nanoSiO2/TiO2 hybrid nanocomposite materials was characterized by XRD, SEM and TEM. From this different analysis results indicate that the optical transparency, thermal stability, control morphology of cellulose-dopamine-SiO2/TiO2 hybrid nanocomposite. Furthermore cellulose-dopamine-SiO2/TiO2 hybrid nanocomposite was tested against pathogenic bacteria for antimicrobial activity.

  15. Treadmill exercise and methylphenidate ameliorate symptoms of attention deficit/hyperactivity disorder through enhancing dopamine synthesis and brain-derived neurotrophic factor expression in spontaneous hypertensive rats.

    PubMed

    Kim, Hong; Heo, Hong-Im; Kim, Dong-Hyun; Ko, Il-Gyu; Lee, Su-Shin; Kim, Sung-Eun; Kim, Bo-Kyun; Kim, Tae-Woon; Ji, Eun-Sang; Kim, Jae-Deung; Shin, Mal-Soon; Choi, Young-Woong; Kim, Chang-Ju

    2011-10-17

    Attention deficit/hyperactivity disorder (ADHD) is a developmental disorder of cognition. Behavioral symptoms of ADHD are inattention, hyperactivity, and impulsivity. We investigated the effects of treadmill exercise and methylphenidate (MPH) on activity and spatial learning memory in relation to dopamine synthesis and brain-derived neurotrophic factor (BDNF) expression using spontaneously hypertensive adult male rats. The rats in the MPH-treated group received 1mg/kg MPH orally once a day for 28days. The rats in the treadmill exercise group were made to run on a treadmill for 30min once a day, five times a week, for 28days. Activity was determined by an open-field test and spatial learning memory was evaluated by an 8-arm maze test. Immunohistochemistry and Western blotting were conducted to examine the levels of tyrosine hydroxylase (TH), the rate-limiting enzyme in the synthesis of dopamine, and BDNF. The rats in the ADHD group showed hyperactivity and spatial learning memory deficit. Reduction of TH in the striatum and substantia nigra and BDNF in the hippocampus was observed of the rats in the ADHD group. Treadmill exercise and MPH alleviated the ADHD-induced hyperactivity and spatial learning memory impairment. Expressions of TH and BDNF in the ADHD rats were also increased by both treadmill exercise and MPH. These findings provide a possibility that exercise may be used as an effective therapeutic intervention for ADHD patients as MPH treatment.

  16. Down-regulation of the mitochondrial aspartate-glutamate carrier isoform 1 AGC1 inhibits proliferation and N-acetylaspartate synthesis in Neuro2A cells.

    PubMed

    Profilo, Emanuela; Peña-Altamira, Luis Emiliano; Corricelli, Mariangela; Castegna, Alessandra; Danese, Alberto; Agrimi, Gennaro; Petralla, Sabrina; Giannuzzi, Giulia; Porcelli, Vito; Sbano, Luigi; Viscomi, Carlo; Massenzio, Francesca; Palmieri, Erika Mariana; Giorgi, Carlotta; Fiermonte, Giuseppe; Virgili, Marco; Palmieri, Luigi; Zeviani, Massimo; Pinton, Paolo; Monti, Barbara; Palmieri, Ferdinando; Lasorsa, Francesco Massimo

    2017-02-21

    The mitochondrial aspartate-glutamate carrier isoform 1 (AGC1) catalyzes a Ca(2+)-stimulated export of aspartate to the cytosol in exchange for glutamate, and is a key component of the malate-aspartate shuttle which transfers NADH reducing equivalents from the cytosol to mitochondria. By sustaining the complete glucose oxidation, AGC1 is thought to be important in providing energy for cells, in particular in the CNS and muscle where this protein is mainly expressed. Defects in the AGC1 gene cause AGC1 deficiency, an infantile encephalopathy with delayed myelination and reduced brain N-acetylaspartate (NAA) levels, the precursor of myelin synthesis in the CNS. Here, we show that undifferentiated Neuro2A cells with down-regulated AGC1 display a significant proliferation deficit associated with reduced mitochondrial respiration, and are unable to synthesize NAA properly. In the presence of high glutamine oxidation, cells with reduced AGC1 restore cell proliferation, although oxidative stress increases and NAA synthesis deficit persists. Our data suggest that the cellular energetic deficit due to AGC1 impairment is associated with inappropriate aspartate levels to support neuronal proliferation when glutamine is not used as metabolic substrate, and we propose that delayed myelination in AGC1 deficiency patients could be attributable, at least in part, to neuronal loss combined with lack of NAA synthesis occurring during the nervous system development.

  17. 3-Chlorotyramine Acting as Ligand of the D2 Dopamine Receptor. Molecular Modeling, Synthesis and D2 Receptor Affinity.

    PubMed

    Angelina, Emilio; Andujar, Sebastian; Moreno, Laura; Garibotto, Francisco; Párraga, Javier; Peruchena, Nelida; Cabedo, Nuria; Villecco, Margarita; Cortes, Diego; Enriz, Ricardo D

    2015-01-01

    We synthesized and tested 3-chlorotyramine as a ligand of the D2 dopamine receptor. This compound displayed a similar affinity by this receptor to that previously reported for dopamine. In order to understand further the experimental results we performed a molecular modeling study of 3-chlorotyramine and structurally related compounds. By combining molecular dynamics simulations with semiempirical (PM6), ab initio and density functional theory calculations, a simple and generally applicable procedure to evaluate the binding energies of these ligands interacting with the D2 dopamine receptors is reported here. These results provided a clear picture of the binding interactions of these compounds from both structural and energetic view points. A reduced model for the binding pocket was used. This approach allowed us to perform more accurate quantum mechanical calculations as well as to obtain a detailed electronic analysis using the Quantum Theory of Atoms in Molecules (QTAIM) technique. Molecular aspects of the binding interactions between ligands and the D2 dopamine receptor are discussed in detail. A good correlation between the relative binding energies obtained from theoretical calculations and experimental IC50 values was obtained. These results allowed us to predict that 3-chlorotyramine possesses a significant affinity by the D2 -DR. Our theoretical predictions were experimentally corroborated when we synthesized and tested 3-chlorotyramine which displayed a similar affinity by the D2 -DR to that reported for DA. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Down-regulation of sorbitol dehydrogenase and up-regulation of sucrose synthase in shoot tips of the transgenic apple trees with decreased sorbitol synthesis.

    PubMed

    Zhou, Rui; Cheng, Lailiang; Dandekar, Abhaya M

    2006-01-01

    Both sorbitol and sucrose are translocated to, and utilized in, sink tissues of apple (Malus domestica). Considering that antisense suppression of aldose 6-phosphate reductase resulted in lower concentrations of sorbitol and higher concentrations of sucrose in source leaves without altering the vegetative growth of apple trees, it was hypothesized that sorbitol metabolism is down-regulated and sucrose metabolism is up-regulated in shoot tips of the transgenic plants. Carbohydrate measurements indicated that sorbitol concentration was lower whereas sucrose concentration was higher in the shoot tips of transgenic apple plants with decreased sorbitol synthesis compared with the untransformed control. However, the shoot relative growth rate was not altered in the transgenic plants. Sorbitol dehydrogenase (SDH) activity was decreased; acid invertase activity and neutral invertase activity remained the same, whereas sucrose synthase (SUSY) activity was increased in shoot tips of the transgenic plants. The SDH transcript level was lower whereas the SUSY transcript level was higher in shoot tips of the transgenic plants. SDH activity and SDH transcript level were specifically stimulated by exogenous sorbitol fed to the shoot tips via the transpiration stream but were specifically inhibited by sucrose. SUSY activity and SUSY transcript level were dramatically enhanced by sucrose, but decreased by glucose and fructose. Neither acid invertase nor neutral invertase activity responded to sucrose, glucose, fructose, or any other sugars tested. It is concluded that sorbitol dehydrogenase is down-regulated, whereas sucrose synthase is up-regulated in shoot tips of the transgenic apple trees with decreased sorbitol synthesis, leading to homeostasis of vegetative growth. Sorbitol and sucrose act as signal molecules to modulate the expression and activities of sorbitol dehydrogenase and sucrose synthase, both of which play an important role in determining the sink strength of apple

  19. Synthesis of Nitric Oxide Donors Derived from Piloty's Acid and Study of Their Effects on Dopamine Secretion from PC12 Cells.

    PubMed

    Sanna, Daniele; Rocchitta, Gaia; Serra, Maria; Abbondio, Marcello; Serra, Pier Andrea; Migheli, Rossana; De Luca, Lidia; Garribba, Eugenio; Porcheddu, Andrea

    2017-09-05

    This study investigated the mechanisms and kinetics of nitric oxide (NO) generation by derivatives of Piloty's acid (NO-donors) under physiological conditions. In order to qualitatively and quantitatively measure NO release, electron paramagnetic resonance (EPR) was carried out with NO spin trapping. In addition, voltammetric techniques, including cyclic voltammetry and constant potential amperometry, were used to confirm NO release from Piloty's acid and its derivatives. The resulting data showed that Piloty's acid derivatives are able to release NO under physiological conditions. In particular, electron-withdrawing substituents favoured NO generation, while electron-donor groups reduced NO generation. In vitro microdialysis, performed on PC12 cell cultures, was used to evaluate the dynamical secretion of dopamine induced by the Piloty's acid derivatives. Although all the studied molecules were able to induce DA secretion from PC12, only those with a slow release of NO have not determined an autoxidation of DA itself. These results confirm that the time-course of NO-donors decomposition and the amount of NO released play a key role in dopamine secretion and auto-oxidation. This information could drive the synthesis or the selection of compounds to use as potential drugs for the therapy of Parkinson's disease (PD).

  20. Facile in Situ Synthesis of Silver Nanoparticles on the Surface of Metal-Organic Framework for Ultrasensitive Surface-Enhanced Raman Scattering Detection of Dopamine.

    PubMed

    Jiang, Zhongwei; Gao, Pengfei; Yang, Lin; Huang, Chengzhi; Li, Yuanfang

    2015-12-15

    Surface-enhanced Raman scattering (SERS) signals are intensively dominated by the Raman hot spots and distance between analyte molecules and metallic nanostructures. Herein, an efficient SERS substrate was developed by in situ synthesis of silver nanoparticles (AgNPs) on the surface of MIL-101 (Fe), a typical metal-organic framework (MOF). The as-prepared SERS substrate combines the numerous Raman hot spots between the high-density Ag NPs and the excellent adsorption performance of MOFs, making it an excellent SERS substrate for highly sensitive SERS detection by effectively concentrating analytes in close proximity to the Raman hot spots domains between the adjacent AgNPs. The resulting hybrid material was used for ultrasensitive SERS detection of dopamine based on the peroxidase-like activity of MIL-101 (Fe) by utilizing the enzyme-linked immunosorbent assay (ELISA) colorimetric substrate, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as a SERS marker. This new developed method showed good linearity in the range from 1.054 pM to 210.8 nM for dopamine with the correlation coefficient of 0.992, detection limit of approximately 0.32 pM [signal-to-noise ratio (S/N) = 3], and acceptable recoveries ranging from 99.8% to 108.0% in human urine. These results predict that the proposed SERS system may open up a new opportunity for chemical and biological assay applications.

  1. New series of morpholine and 1,4-oxazepane derivatives as dopamine D4 receptor ligands: synthesis and 3D-QSAR model.

    PubMed

    Audouze, Karine; Nielsen, Elsebet Østergaard; Peters, Dan

    2004-06-03

    Since the identification of the dopamine D(4) receptor subtype and speculations about its possible involvement in schizophrenia, much work has been put into development of selective D(4) ligands. These selective ligands may be effective antipsychotics without extrapyramidal side effects. This work describes the synthesis of a new series of 2,4-disubstituted morpholines and 2,4-disubstituted 1,4-oxazepanes with selectivity for the dopamine D(4) receptor. A 3D-QSAR analysis using the GRID/GOLPE methodology was performed with the purpose to get a better understanding of the relationship between chemical structure and biological activity. Inspection of the coefficient plots allowed us to identify that regions which are important for affinity are situated around the two benzene ring systems, a p-chlorobenzyl group, and the aliphatic amine belonging to the morpholine or 1,4-oxazepane system. In addition, the size of the morpholine or 1,4-oxazepane ring seems to be important for affinity.

  2. LKB1 promotes cell survival by modulating TIF-IA-mediated pre-ribosomal RNA synthesis under uridine downregulated conditions.

    PubMed

    Liu, Fakeng; Jin, Rui; Liu, Xiuju; Huang, Henry; Wilkinson, Scott C; Zhong, Diansheng; Khuri, Fadlo R; Fu, Haian; Marcus, Adam; He, Yulong; Zhou, Wei

    2016-01-19

    We analyzed the mechanism underlying 5-aminoimidazole-4-carboxamide riboside (AICAR) mediated apoptosis in LKB1-null non-small cell lung cancer (NSCLC) cells. Metabolic profile analysis revealed depletion of the intracellular pyrimidine pool after AICAR treatment, but uridine was the only nucleotide precursor capable of rescuing this apoptosis, suggesting the involvement of RNA metabolism. Because half of RNA transcription in cancer is for pre-ribosomal RNA (rRNA) synthesis, which is suppressed by over 90% after AICAR treatment, we evaluated the role of TIF-IA-mediated rRNA synthesis. While the depletion of TIF-IA by RNAi alone promoted apoptosis in LKB1-null cells, the overexpression of a wild-type or a S636A TIF-IA mutant, but not a S636D mutant, attenuated AICAR-induced apoptosis. In LKB1-null H157 cells, pre-rRNA synthesis was not suppressed by AICAR when wild-type LKB1 was present, and cellular fractionation analysis indicated that TIF-IA quickly accumulated in the nucleus in the presence of a wild-type LKB1 but not a kinase-dead mutant. Furthermore, ectopic expression of LKB1 was capable of attenuating AICAR-induced death in AMPK-null cells. Because LKB1 promotes cell survival by modulating TIF-IA-mediated pre-rRNA synthesis, this discovery suggested that targeted depletion of uridine related metabolites may be exploited in the clinic to eliminate LKB1-null cancer cells.

  3. Withdrawal from chronic ethanol increases the sensitivity of presynaptic 5-HT(1A) receptors modulating serotonin and dopamine synthesis in rat brain in vivo.

    PubMed

    Esteban, Susana; Moranta, David; Sastre-Coll, Antoni; Miralles, Antonio; García-Sevilla, Jesús A

    2002-06-28

    The in vivo sensitivity of presynaptic 5-HT(1A) receptors (autoreceptors and heteroreceptors) modulating the synthesis of 5-hydroxytryptophan/serotonin (5-HTP/5-HT) and 3,4-dihydroxyphenylalanine/dopamine (DOPA/DA) in rat brain was investigated after ethanol treatment and withdrawal. In saline-treated rats as well as in acute ethanol (2 g/kg, intraperitoneally (i.p.), 2 h)- and chronic ethanol (2 g/kg for 7 days)-treated rats, a low dose of the 5-HT(1A) receptor agonist 8-hydroxy-2-di-n-propylamino-tetralin (8-OH-DPAT; 0.1 mg/kg, i.p., 1 h) did not decrease the synthesis of 5-HTP in brain (except modestly in striatum; 20% after the chronic treatment) or that of DOPA in striatum. In contrast, in chronic ethanol-withdrawn rats (24 h), 8-OH-DPAT significantly decreased the synthesis of 5-HTP in the hippocampus (29%), cerebral cortex (41%) and striatum (33%) and that of DOPA in the striatum (28%). Similar effects were induced by the mixed 5-HT(1A) agonist/D(2) antagonist buspirone (1 mg/kg, i.p., 1 h) which also decreased 5-HTP synthesis in the hippocampus (24%), cerebral cortex (36%) and striatum (35%) of chronic ethanol-withdrawn rats. These results indicate that chronic ethanol and more clearly the spontaneous withdrawal from chronic ethanol induce supersensitivity of 5-HT(1A)-auto/heteroreceptors modulating the synthesis of 5-HT and DA in rat brain.

  4. Extra virgin olive oil phenols down-regulate lipid synthesis in primary-cultured rat-hepatocytes.

    PubMed

    Priore, Paola; Siculella, Luisa; Gnoni, Gabriele Vincenzo

    2014-07-01

    Hydroxytyrosol, tyrosol, and oleuropein, the main phenols present in extra virgin olive oil, have been reported to exert several biochemical and pharmacological effects. Here, we investigated the short-term effects of these compounds on lipid synthesis in primary-cultured rat-liver cells. Hydroxytyrosol, tyrosol and oleuropein inhibited both de novo fatty acid and cholesterol syntheses without an effect on cell viability. The inhibitory effect of individual compounds was already evident within 2 h of 25 μM phenol addition to the hepatocytes. The degree of cholesterogenesis reduction was similar for all phenol treatments (-25/30%), while fatty acid synthesis showed the following order of inhibition: hydroxytyrosol (-49%) = oleuropein (-48%) > tyrosol (-30%). A phenol-induced reduction of triglyceride synthesis was also detected. To clarify the lipid-lowering mechanism of these compounds, their influence on the activity of key enzymes of fatty acid biosynthesis (acetyl-CoA carboxylase and fatty acid synthase), triglyceride synthesis (diacylglycerol acyltransferase) and cholesterogenesis (3-hydroxy-3-methyl-glutaryl-CoA reductase) was investigated in situ by using digitonin-permeabilized hepatocytes. Acetyl-CoA carboxylase, diacylglycerol acyltransferase and 3-hydroxy-3-methyl-glutaryl-CoA reductase activities were reduced after 2 h of 25 μM phenol treatment. No change in fatty acid synthase activity was observed. Acetyl-CoA carboxylase inhibition (hydroxytyrosol, -41%, = oleuropein, -38%, > tyrosol, -17%) appears to be mediated by phosphorylation of AMP-activated protein kinase. These findings suggest that a decrease in hepatic lipid synthesis may represent a potential mechanism underlying the reported hypolipidemic effect of phenols of extra virgin olive oil.

  5. Synthesis and characterization of 4-(2-aminoethyl)aniline imprinted polymer as a highly effective sorbent of dopamine.

    PubMed

    Luliński, Piotr; Dana, Mariusz; Maciejewska, Dorota

    2014-02-01

    The aim of the study was to develop an efficient sorbent for the separation of dopamine. 4-(2-Aminoethyl)aniline was chosen as a pseudo-template to produce the imprinted polymers from seven different functional monomers in the presence of ethylene glycol dimethacrylate as a cross-linker. The binding capacity showed that the highest binding specificity towards dopamine was achieved when methacrylic acid was used as the monomer in methanol solution to form a polymer matrix. The imprinting factor value was equal to 22.96. Other biogenic amines were bound much more weakly. A simple theoretical model was used to give an insight into the imprinting process and the selectivity of polymer matrix. Two artificial urine samples were used as the complex matrices to show the usefulness of the new sorbent for bioanalysis.

  6. The natural yeast extract isolated by ethanol precipitation inhibits melanin synthesis by modulating tyrosinase activity and downregulating melanosome transfer.

    PubMed

    Lee, Woo Jin; Rhee, Do Young; Bang, Seung Hyun; Kim, Su Yeon; Won, Chong Hyun; Lee, Mi Woo; Choi, Jee Ho; Chang, Sung Eun

    2015-01-01

    This study was conducted to examine the effects of EP-2, a natural yeast extract isolated by ethanol precipitation from Saccharomyces cerevisiae, on melanogenesis and to determine its underlying mechanism of action. Our results show that although EP-2 is not a direct tyrosinase inhibitor, when EP-2 was added to the culture media of B16F10 melanoma cells, intracellular tyrosinase activity was decreased. However, EP-2 had no effect on the expression of microphthalmia-associated transcription factor or tyrosinase. EP-2 was found to inhibit melanogenesis and melanosome transfer when it was added to melanocytes and keratinocytes in coculture. In addition, protease-activated receptor 2, a key protein associated with melanosome transfer from melanocytes to keratinocytes, was downregulated in the presence of EP-2. In conclusion, EP-2 is a potent inhibitor of melanogenesis and its hypomelanogenic effect is related to the inhibition of tyrosinase activity and transfer of melanosomes.

  7. Design, synthesis and preliminary evaluation of dopamine-amino acid conjugates as potential D1 dopaminergic modulators.

    PubMed

    Tutone, Marco; Chinnici, Aurora; Almerico, Anna Maria; Perricone, Ugo; Sutera, Flavia Maria; De Caro, Viviana

    2016-11-29

    The dopamine-amino acid conjugate DA-Phen was firstly designed to obtain a useful prodrug for the therapy of Parkinson's disease, but experimental evidence shows that it effectively interacts with D1 dopamine receptors (D1DRs), leading to an enhancement in cognitive flexibility and to the development of adaptive strategies in aversive mazes, together with a decrease in despair-like behavior. In this paper, homology modelling, molecular dynamics, and site mapping of D1 receptor were carried out with the aim of further performing docking studies on other dopamine conjugates compared with D1 agonists, in the attempt to identify new compounds with potential dopaminergic activity. Two new conjugates (DA-Trp 2C, and DA-Leu 3C) have been identified as the most promising candidates, and consequently synthesized. Preliminary evaluation in terms of distribution coefficient (D(pH7.4)), stability in rat brain homogenate, and in human plasma confirmed that DA-Trp (2C), and DA-Leu (3C) could be considered as very valuable candidates for further in vivo studies as new dopaminergic drugs.

  8. Synthesis and ligand binding studies of 4'-iodobenzoyl esters of tropanes and piperidines at the dopamine transporter.

    PubMed

    Singh, S; Basmadjian, G P; Avor, K S; Pouw, B; Seale, T W

    1997-08-01

    Four analogs and two homologs of cocaine, designed as potent cocaine antagonists, were synthesized. The SN2 reaction between ecgonine methyl ester (13) or appropriately substituted piperidinol (19, 21) and appropriately substituted 4-iodobenzoyl chloride gave 4-iodobenzoyl esters of tropanes and piperidines (5-8). 2'-Hydroxycocaine (9) was obtained from 2'-acetoxycocaine (12) by selective transesterification with MeOH saturated with dry HCl gas. 2'-Acetoxycocaine (12) was synthesized from acetylsalicyloyl chloride (23) and ecgonine methyl ester (13). The binding affinities of these compounds were determined at the dopamine transporter for the displacement of [3H]WIN-35428. An iodo group substitution at the 4'-position of cocaine decreased dopamine transporter binding potency, while a hydroxy or acetoxy group at the 2'-position exhibited increased binding potency for the dopamine transporter compared to cocaine (10- and 3.58-fold, respectively). 2'-Hydroxylation also enhanced the bidning potency of 4'-iodococaine (5) by 10-fold. Replacement of the tropane ring with piperidine led to poor binding affinities.

  9. Metabolic Downregulation

    PubMed Central

    Yenari, Midori; Kitagawa, Kazuo; Lyden, Patrick; Perez-Pinzon, Miguel

    2008-01-01

    Background and Purpose The search for effective neuroprotectants remains frustrating, particularly with regard to specific pharmaceuticals. However, laboratory studies have consistently shown remarkable neuroprotection with 2 nonpharmacological strategies—therapeutic hypothermia and ischemic preconditioning. Recent studies have shown that the mechanism of protection underlying both of these treatments is correlated to downregulation of cellular and tissue metabolism. Thus, understanding the mechanisms underlying such robust protective effects could lead to appropriate translation at the clinical level. In fact, hypothermia is already being used at many centers to improve neurological outcome from cardiac arrest. Methods A systematic review of both topics is presented in terms of underlying pathophysiological mechanisms and application at the clinical level. Results Although the mechanisms of protection for both therapeutic strategies are multifold, both share features of downregulating metabolism. Both therapeutic strategies are robust neuroprotectants, but translating them to the clinical arena is challenging, though not impossible, and clinical studies have shown or suggest benefits of both treatments. Conclusions The strategy of metabolic downregulation should be further explored to identify effective neuroprotectants that can be easily applied clinically. PMID:18658035

  10. LKB1 promotes cell survival by modulating TIF-IA-mediated pre-ribosomal RNA synthesis under uridine downregulated conditions

    PubMed Central

    Liu, Xiuju; Huang, Henry; Wilkinson, Scott C.; Zhong, Diansheng; Khuri, Fadlo R.; Fu, Haian; Marcus, Adam; He, Yulong; Zhou, Wei

    2016-01-01

    We analyzed the mechanism underlying 5-aminoimidazole-4-carboxamide riboside (AICAR) mediated apoptosis in LKB1-null non-small cell lung cancer (NSCLC) cells. Metabolic profile analysis revealed depletion of the intracellular pyrimidine pool after AICAR treatment, but uridine was the only nucleotide precursor capable of rescuing this apoptosis, suggesting the involvement of RNA metabolism. Because half of RNA transcription in cancer is for pre-ribosomal RNA (rRNA) synthesis, which is suppressed by over 90% after AICAR treatment, we evaluated the role of TIF-IA-mediated rRNA synthesis. While the depletion of TIF-IA by RNAi alone promoted apoptosis in LKB1-null cells, the overexpression of a wild-type or a S636A TIF-IA mutant, but not a S636D mutant, attenuated AICAR-induced apoptosis. In LKB1-null H157 cells, pre-rRNA synthesis was not suppressed by AICAR when wild-type LKB1 was present, and cellular fractionation analysis indicated that TIF-IA quickly accumulated in the nucleus in the presence of a wild-type LKB1 but not a kinase-dead mutant. Furthermore, ectopic expression of LKB1 was capable of attenuating AICAR-induced death in AMPK-null cells. Because LKB1 promotes cell survival by modulating TIF-IA-mediated pre-rRNA synthesis, this discovery suggested that targeted depletion of uridine related metabolites may be exploited in the clinic to eliminate LKB1-null cancer cells. PMID:26506235

  11. Interleukin-8 induces DNA synthesis, migration and down-regulation of cleaved caspase-3 in cultured human gingival epithelial cells.

    PubMed

    Fujita, T; Yoshimoto, T; Matsuda, S; Kajiya, M; Kittaka, M; Imai, H; Iwata, T; Uchida, Y; Shiba, H; Kurihara, H

    2015-08-01

    Migration of the junctional epithelium occurs in association with the formation of a periodontal pocket. Although the migration of junctional epithelium is known to be related to the proliferation and migration of gingival junctional epithelial cells, the mechanism has not been clarified. In patients with periodontitis, the levels of interleukin-8 (IL-8) in both gingival tissue and gingival crevicular fluid are dramatically increased. IL-8 has broad bioactive functions. In this study, we examined the role of IL-8 in DNA synthesis, migration and protection against apoptosis in cultured human gingival epithelial cells (HGEC). DNA synthesis was estimated by measuring the incorporation of bromodeoxyuridine. The migration of gingival epithelial cells was assessed in a wound-healing assay. The expression of integrin beta-1 was analyzed using immunofluorescence confocal microscopy and western blotting. Cleaved caspase-3 was detected using western blotting and a Caspase-Glo assay kit. IL-8 increased the synthesis of DNA in HGEC, and the maximal effect was seen at 25 or 50 ng/mL of IL-8. In addition, 50 ng/mL of IL-8 induced cell migration, and a neutralizing antibody of integrin beta-1 inhibited the migration. IL-8 also activated expression of integrin beta-1. Furthermore, IL-8 reduced the Aggregatibacter actinomycetemcomitans-induced increase in caspase-3 expression in HGEC. IL-8 may facilitate the migration of gingival junctional epithelium by enhancing DNA synthesis, migration and preventing apoptosis of gingival epithelial cells. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  12. 1α,25-dihydroxyvitamin D inhibits de novo fatty acid synthesis and lipid accumulation in metastatic breast cancer cells through down-regulation of pyruvate carboxylase.

    PubMed

    Wilmanski, Tomasz; Buhman, Kimberly; Donkin, Shawn S; Burgess, John R; Teegarden, Dorothy

    2017-02-01

    Both increased de novo fatty acid synthesis and higher neutral lipid accumulation are a common phenotype observed in aggressive breast cancer cells, making lipid metabolism a promising target for breast cancer prevention. In the present studies, we demonstrate a novel effect of the active metabolite of vitamin D, 1α,25-dihydroxyvitamin D (1,25(OH)₂D) on lipid metabolism in malignant breast epithelial cells. Treatment of MCF10CA1a breast epithelial cells with 1,25(OH)₂D (10 nM) for 5 and 7 days decreased the level of triacylglycerol, the most abundant form of neutral lipids, by 20%(±3.9) and 50%(±5.9), respectively. In addition, 1,25(OH)₂D treatment for 5 days decreased palmitate synthesis from glucose, the major fatty acid synthesized de novo (48%±5.5 relative to vehicle). We have further identified the anaplerotic enzyme pyruvate carboxylase (PC) as a target of 1,25(OH)₂D-mediated regulation and hypothesized that 1,25(OH)₂D regulates breast cancer cell lipid metabolism through inhibition of PC. PC mRNA expression was down-regulated with 1,25(OH)₂D treatment at 2 (73%±6 relative to vehicle) and 5 (56%±8 relative to vehicle) days. Decrease in mRNA abundance corresponded with a decrease in PC protein expression at 5 days of treatment (54%±12 relative to vehicle). Constitutive overexpression of PC in MCF10CA1a cells using a pCMV6-PC plasmid inhibited the effect of 1,25(OH)₂D on both TAG accumulation and de novo palmitate synthesis from glucose. Together, these studies demonstrate a novel mechanism through which 1,25(OH)₂D regulates lipid metabolism in malignant breast epithelial cells.

  13. Effects of VMAT2 inhibitors lobeline and GZ-793A on methamphetamine-induced changes in dopamine release, metabolism and synthesis in vivo

    PubMed Central

    Meyer, Andrew C.; Neugebauer, Nichole M.; Zheng, Guangrong; Crooks, Peter A.; Dwoskin, Linda P.; Bardo, Michael T.

    2013-01-01

    Vesicular monoamine transporter-2 (VMAT2) inhibitors reduce methamphetamine (METH) reward in rats. The current study determined the effects of VMAT2 inhibitors lobeline (LOB; 1 or 3 mg/kg) and N-(1,2R-dihydroxylpropyl)-2,6-cis-di(4-methoxyphenethyl)piperidine hydrochloride (GZ-793A; 15 or 30 mg/kg) on METH-induced (0.5 mg/kg, SC) changes in extracellular dopamine (DA) and its metabolite dihydroxyphenylacetic acid (DOPAC) in the reward-relevant nucleus accumbens (NAc) shell using in vivo microdialysis. The effect of GZ-793A (15 mg/kg) on DA synthesis in tissue also was investigated in NAc, striatum (STR), medial prefrontal cortex (mPFC) and orbitofrontal cortex (OFC). In NAc shell, METH produced a time-dependent increase in extracellular DA and decrease in DOPAC. Neither LOB nor GZ-793A alone altered extracellular DA; however, both drugs increased extracellular DOPAC. In combination with METH, LOB did not alter the effects of METH on DA; however, GZ-793A, which has greater selectivity than LOB for inhibiting VMAT2, reduced the duration of the METH-induced increase in extracellular DA. Both LOB and GZ-793A enhanced the duration of the METH-induced decrease in extracellular DOPAC. METH also increased tissue DA synthesis in NAc and STR, whereas GZ-793A decreased synthesis; no effect of METH or GZ-793A on DA synthesis was found in mPFC or OFC. These results suggest that selective inhibition of VMAT2 produces a time-dependent decrease in DA release in NAc shell as a result of alterations in tyrosine hydroxylase activity, which may play a role in the ability of GZ-793A to decrease METH reward. PMID:23875705

  14. Effects of VMAT2 inhibitors lobeline and GZ-793A on methamphetamine-induced changes in dopamine release, metabolism and synthesis in vivo.

    PubMed

    Meyer, Andrew C; Neugebauer, Nichole M; Zheng, Guangrong; Crooks, Peter A; Dwoskin, Linda P; Bardo, Michael T

    2013-10-01

    Vesicular monoamine transporter-2 (VMAT2) inhibitors reduce methamphetamine (METH) reward in rats. The current study determined the effects of VMAT2 inhibitors lobeline (LOB; 1 or 3 mg/kg) and N-(1,2R-dihydroxylpropyl)-2,6-cis-di(4-methoxyphenethyl)piperidine hydrochloride (GZ-793A; 15 or 30 mg/kg) on METH-induced (0.5 mg/kg, SC) changes in extracellular dopamine (DA) and its metabolite dihydroxyphenylacetic acid (DOPAC) in the reward-relevant nucleus accumbens (NAc) shell using in vivo microdialysis. The effect of GZ-793A (15 mg/kg) on DA synthesis in tissue also was investigated in NAc, striatum, medial prefrontal cortex and orbitofrontal cortex. In NAc shell, METH produced a time-dependent increase in extracellular DA and decrease in DOPAC. Neither LOB nor GZ-793A alone altered extracellular DA; however, both drugs increased extracellular DOPAC. In combination with METH, LOB did not alter the effects of METH on DA; however, GZ-793A, which has greater selectivity than LOB for inhibiting VMAT2, reduced the duration of the METH-induced increase in extracellular DA. Both LOB and GZ-793A enhanced the duration of the METH-induced decrease in extracellular DOPAC. METH also increased tissue DA synthesis in NAc and striatum, whereas GZ-793A decreased synthesis; no effect of METH or GZ-793A on DA synthesis was found in medial prefrontal cortex or orbitofrontal cortex. These results suggest that selective inhibition of VMAT2 produces a time-dependent decrease in DA release in NAc shell as a result of alterations in tyrosine hydroxylase activity, which may play a role in the ability of GZ-793A to decrease METH reward.

  15. Cooperative synthesis of dopamine by non-dopaminergic neurons as a compensatory mechanism in the striatum of mice with MPTP-induced Parkinsonism.

    PubMed

    Kozina, Elena A; Kim, Aleksandr R; Kurina, Anna Y; Ugrumov, Michael V

    2017-02-01

    Since the late 80s it has been repeatedly shown that besides dopaminergic neurons, the brain contains so-called monoenzymatic neurons possessing one of the enzymes of dopamine (DA) synthesis, tyrosine hydroxylase (TH) or aromatic l-amino acid decarboxylase (AADC). However, the data on the existence of monoenzymatic neurons in the striatum remain controversial, and little is known about their functional significance. The aim of this study was to test our hypothesis that monoenzymatic TH-containing neurons produce DA in cooperation with the neurons containing AADC, which might help to compensate DA deficiency under the failure of the nigrostriatal dopaminergic system. Using a combination of techniques: retrograde tracing, qPCR and immunolabeling for TH, AADC and MAP2, we showed that the striatum of mice with normal and degraded dopaminergic system comprises of monoenzymatic TH- and AADC-containing neurons. To provide evidence for cooperative synthesis of DA, we used an ex vivo model of inhibiting of DA synthesis by blocking transport of l-DOPA, produced in monoenzymatic TH-containing neurons, to neurons containing AADC by means of l-leucine, a competitive inhibitor of the membrane transporter of large neutral amino acids, and l-DOPA. With this original approach, cooperative synthesis of DA in the striatum was proven in MPTP-treated mice but not in the control. Furthermore, we demonstrated that the proportion of DA produced through cooperative synthesis in the striatum of MPTP-treated mice increases as the degradation of dopaminergic system proceeds. An increase in the proportion of cooperative synthesis of DA alongside degradation of the dopaminergic system is also proved by an increase of both TH gene expression and the number of TH-immunoreactive structures in the striatum. Thus, these data suggest that the cooperative synthesis of DA in the degraded striatum is an up-regulated compensatory reaction, which plays an increasing role as DA deficiency rises, and might

  16. Dopamine-Independent Locomotor Actions of Amphetamines in a Novel Acute Mouse Model of Parkinson Disease

    PubMed Central

    Sotnikova, Tatyana D; Beaulieu, Jean-Martin; Barak, Larry S; Wetsel, William C; Gainetdinov, Raul R

    2005-01-01

    Brain dopamine is critically involved in movement control, and its deficiency is the primary cause of motor symptoms in Parkinson disease. Here we report development of an animal model of acute severe dopamine deficiency by using mice lacking the dopamine transporter. In the absence of transporter-mediated recycling mechanisms, dopamine levels become entirely dependent on de novo synthesis. Acute pharmacological inhibition of dopamine synthesis in these mice induces transient elimination of striatal dopamine accompanied by the development of a striking behavioral phenotype manifested as severe akinesia, rigidity, tremor, and ptosis. This phenotype can be reversed by administration of the dopamine precursor, L-DOPA, or by nonselective dopamine agonists. Surprisingly, several amphetamine derivatives were also effective in reversing these behavioral abnormalities in a dopamine-independent manner. Identification of dopamine transporter- and dopamine-independent locomotor actions of amphetamines suggests a novel paradigm in the search for prospective anti-Parkinsonian drugs. PMID:16050778

  17. Dopamine-independent locomotor actions of amphetamines in a novel acute mouse model of Parkinson disease.

    PubMed

    Sotnikova, Tatyana D; Beaulieu, Jean-Martin; Barak, Larry S; Wetsel, William C; Caron, Marc G; Gainetdinov, Raul R

    2005-08-01

    Brain dopamine is critically involved in movement control, and its deficiency is the primary cause of motor symptoms in Parkinson disease. Here we report development of an animal model of acute severe dopamine deficiency by using mice lacking the dopamine transporter. In the absence of transporter-mediated recycling mechanisms, dopamine levels become entirely dependent on de novo synthesis. Acute pharmacological inhibition of dopamine synthesis in these mice induces transient elimination of striatal dopamine accompanied by the development of a striking behavioral phenotype manifested as severe akinesia, rigidity, tremor, and ptosis. This phenotype can be reversed by administration of the dopamine precursor, L-DOPA, or by nonselective dopamine agonists. Surprisingly, several amphetamine derivatives were also effective in reversing these behavioral abnormalities in a dopamine-independent manner. Identification of dopamine transporter- and dopamine-independent locomotor actions of amphetamines suggests a novel paradigm in the search for prospective anti-Parkinsonian drugs.

  18. Resveratrol-Enriched Rice Down-Regulates Melanin Synthesis in UVB-Induced Guinea Pigs Epidermal Skin Tissue

    PubMed Central

    Lee, Taek Hwan; Seo, Jae Ok; Do, Moon Ho; Ji, Eunhee; Baek, So-Hyeon; Kim, Sun Yeou

    2014-01-01

    Synthetic compounds that are used in the clinic to regulate skin hyperpigmentation, such as arbutin, hydroquinone, and kojic acid, are only moderately effective. But, their use is limited by side effects. As part of an effort to overcome the limitations, we developed resveratrol-enriched rice (RR) using genetic engineering technique. Each of resveratrol and rice has been reported to produce anti-melanogenic effects. Therefore, we hypothesized that RR would show more anti-melanogenic effects than those of resveratrol or rice alone. Anti-melanogenic effect of RR was done by using melan-a mouse melanocytes. The depigmenting efficacy was then observed following topical application of the RR to UVB-stimulated hyperpigmented dorsal skin of guinea pigs. Treatment with RR extract resulted a 21.4 ± 0.7% decrease in tyrosinase expression at melan-a cells. Colorimetric analysis showed a significantly lower depigmenting value by day 9 following treatment with RR in UVB-irradiated guinea pigs the dorsal skin (p<0.01), indicating that RR produced a depigmentation effect. By staining with Fontana-Masson stain, we found that the RR-treated group had more effect histopathologically in epidermal melanin production than resveratrol or rice alone-treated group. RR was associated with reduction in the levels of microphthalmia-associated transcription factor (MITF), and downregulation of tyrosinase and tyrosinase-related protein (TRP-2) expression, leading to inhibit epidermal melanin production by western blot analysis. This study suggests that the resveratrol-enriched rice may be a promising candidate in regulating skin pigmentation with UVB exposure. PMID:25414774

  19. Downregulation of AMPK Accompanies Leucine- and Glucose-Induced Increases in Protein Synthesis and Insulin Resistance in Rat Skeletal Muscle

    PubMed Central

    Saha, Asish K.; Xu, X. Julia; Lawson, Ebony; Deoliveira, Rosangela; Brandon, Amanda E.; Kraegen, Edward W.; Ruderman, Neil B.

    2010-01-01

    OBJECTIVE Branched-chain amino acids, such as leucine and glucose, stimulate protein synthesis and increase the phosphorylation and activity of the mammalian target of rapamycin (mTOR) and its downstream target p70S6 kinase (p70S6K). We examined in skeletal muscle whether the effects of leucine and glucose on these parameters and on insulin resistance are mediated by the fuel-sensing enzyme AMP-activated protein kinase (AMPK). RESEARCH DESIGN AND METHODS Rat extensor digitorum longus (EDL) muscle was incubated with different concentrations of leucine and glucose with or without AMPK activators. Muscle obtained from glucose-infused rats was also used as a model. RESULTS In the EDL, incubation with 100 or 200 μmol/l leucine versus no added leucine suppressed the activity of the α2 isoform of AMPK by 50 and 70%, respectively, and caused concentration-dependent increases in protein synthesis and mTOR and p70S6K phosphorylation. Very similar changes were observed in EDL incubated with 5.5 or 25 mmol/l versus no added glucose and in muscle of rats infused with glucose in vivo. Incubation of the EDL with the higher concentrations of both leucine and glucose also caused insulin resistance, reflected by a decrease in insulin-stimulated Akt phosphorylation. Coincubation with the AMPK activators AICAR and α-lipoic acid substantially prevented all of those changes and increased the phosphorylation of specific sites of mTOR inhibitors raptor and tuberous sclerosis complex 2 (TSC2). In contrast, decreases in AMPK activity induced by leucine and glucose were not associated with a decrease in raptor or TSC2 phosphorylation. CONCLUSIONS The results indicate that both leucine and glucose modulate protein synthesis and mTOR/p70S6 and insulin signaling in skeletal muscle by a common mechanism. They also suggest that the effects of both molecules are associated with a decrease in AMPK activity and that AMPK activation prevents them. PMID:20682696

  20. Effective seed-assisted synthesis of gold nanoparticles anchored nitrogen-doped graphene for electrochemical detection of glucose and dopamine.

    PubMed

    Thanh, Tran Duy; Balamurugan, Jayaraman; Lee, Seung Hee; Kim, Nam Hoon; Lee, Joong Hee

    2016-07-15

    A novel gold nanoparticle-anchored nitrogen-doped graphene (AuNP/NG) nanohybrid was synthesized through a seed-assisted growth method, as an effective electrocatalyst for glucose and dopamine detection. The AuNP/NG nanohybrids exhibited high sensitivity and selectivity toward glucose and dopamine sensing applications. The as-synthesized nanohybrids exhibited excellent catalytic activity toward glucose, with a linear response throughout the concentration range from 40μM to 16.1mM, a detection limit of 12μM, and a short response time (∼ 10s). It also exhibited an excellent response toward DA, with a wide detection range from 30nM to 48μM, a low detection limit of 10nM, and a short response time (∼ 8s). Furthermore, it also showed long-term stability and high selectivity for the target analytes. These results imply that such nanohybrids show a great potential for electrochemical biosensing application.

  1. Radiobrominated analog of SCH 23390, a selective dopamine D1 antagonist: Synthesis and biodistribution in mouse brain

    SciTech Connect

    De Jesus, O.T.; Van Moffaert, G.J.C.; Glock, D.; Dinerstein, R.J.; Friedman, A.M.

    1985-05-01

    SCH 23390 (R-(+)-8-chloro-2,3,4, 5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7-ol) is a highly selective dopamine D1 antagonist. The authors have prepared an 8-bromo analog of SCH 23390 (BrSCH) labelled with Br-75 or Br-76 and have studied its distribution in mouse brain. Milligram quantities of BrSCH were synthesized by the reaction of its des-chloro analog with bromide in H/sub 2/O/sub 2/-glacial acetic acid. The product was purified by preparative HPLC and characterized by mass spectrometry, NMR, and a bioassay technique involving the inhibition of DA-induced vasodilation of dog renal artery. Comparison with an authentic sample confirmed that the product obtained was BrSCH. The time course of distribution of this drug in mouse brain was followed and the results showed high uptake in DA receptor-rich striatum. Striatum to cerebellum uptake ratios were observed to be as high as 25 two hours after injection. These results demonstrate that a positron-emitting radiobrominated analog of SCH 23390 would be useful in the imaging of cerebral dopamine D1 receptors.

  2. Dopamine synapse is a neuroligin-2-mediated contact between dopaminergic presynaptic and GABAergic postsynaptic structures.

    PubMed

    Uchigashima, Motokazu; Ohtsuka, Toshihisa; Kobayashi, Kazuto; Watanabe, Masahiko

    2016-04-12

    Midbrain dopamine neurons project densely to the striatum and form so-called dopamine synapses on medium spiny neurons (MSNs), principal neurons in the striatum. Because dopamine receptors are widely expressed away from dopamine synapses, it remains unclear how dopamine synapses are involved in dopaminergic transmission. Here we demonstrate that dopamine synapses are contacts formed between dopaminergic presynaptic and GABAergic postsynaptic structures. The presynaptic structure expressed tyrosine hydroxylase, vesicular monoamine transporter-2, and plasmalemmal dopamine transporter, which are essential for dopamine synthesis, vesicular filling, and recycling, but was below the detection threshold for molecules involving GABA synthesis and vesicular filling or for GABA itself. In contrast, the postsynaptic structure of dopamine synapses expressed GABAergic molecules, including postsynaptic adhesion molecule neuroligin-2, postsynaptic scaffolding molecule gephyrin, and GABAA receptor α1, without any specific clustering of dopamine receptors. Of these, neuroligin-2 promoted presynaptic differentiation in axons of midbrain dopamine neurons and striatal GABAergic neurons in culture. After neuroligin-2 knockdown in the striatum, a significant decrease of dopamine synapses coupled with a reciprocal increase of GABAergic synapses was observed on MSN dendrites. This finding suggests that neuroligin-2 controls striatal synapse formation by giving competitive advantage to heterologous dopamine synapses over conventional GABAergic synapses. Considering that MSN dendrites are preferential targets of dopamine synapses and express high levels of dopamine receptors, dopamine synapse formation may serve to increase the specificity and potency of dopaminergic modulation of striatal outputs by anchoring dopamine release sites to dopamine-sensing targets.

  3. Down-regulation of UDP-glucose dehydrogenase affects glycosaminoglycans synthesis and motility in HCT-8 colorectal carcinoma cells

    SciTech Connect

    Wang, Tsung-Pao; Pan, Yun-Ru; Fu, Chien-Yu; Chang, Hwan-You

    2010-10-15

    UDP-glucose dehydrogenase (UGDH) catalyzes oxidation of UDP-glucose to yield UDP-glucuronic acid, a precursor of hyaluronic acid (HA) and other glycosaminoglycans (GAGs) in extracellular matrix. Although association of extracellular matrix with cell proliferation and migration has been well documented, the importance of UGDH in these behaviors is not clear. Using UGDH-specific small interference RNA to treat HCT-8 colorectal carcinoma cells, a decrease in both mRNA and protein levels of UGDH, as well as the cellular UDP-glucuronic acid and GAG production was observed. Treatment of HCT-8 cells with either UGDH-specific siRNA or HA synthesis inhibitor 4-methylumbelliferone effectively delayed cell aggregation into multicellular spheroids and impaired cell motility in both three-dimensional collagen gel and transwell migration assays. The reduction in cell aggregation and migration rates could be restored by addition of exogenous HA. These results indicate that UGDH can regulate cell motility through the production of GAG. The enzyme may be a potential target for therapeutic intervention of colorectal cancers.

  4. Facile Synthesis of Molecularly Imprinted Graphene Quantum Dots for the Determination of Dopamine with Affinity-Adjustable.

    PubMed

    Zhou, Xi; Wang, Anqi; Yu, Chenfei; Wu, Shishan; Shen, Jian

    2015-06-10

    A facilely prepared fluorescence sensor was developed for dopamine (DA) determination based on polyindole/graphene quantum dots molecularly imprinted polymers (PIn/GQDs@MIPs). The proposed sensor exhibits a high sensitivity with a linear range of 5 × 10(-10) to 1.2 × 10(-6) M and the limit of detection as low as 1 × 10(-10) M in the determination of DA, which is probably due to the tailor-made imprinted cavities for binding DA thought hydrogen bonds between amine groups of DA and oxygen-containing groups of the novel composite. Furthermore, the prepared sensor can rebind DA in dual-type: a low affinity type (noncovalent interaction is off) and a high affinity type (noncovalent interaction is on), and the rebinding interaction can be adjusted by tuning the pH, which shows a unique potential for adjusting the binding interaction while keeping the specificity, allowing for wider applications.

  5. Long-term daily access to alcohol alters dopamine-related synthesis and signaling proteins in the rat striatum.

    PubMed

    Kashem, Mohammed Abul; Ahmed, Selina; Sarker, Ranjana; Ahmed, Eakhlas U; Hargreaves, Garth A; McGregor, Iain S

    2012-12-01

    Chronic alcohol exposure can adversely affect neuronal morphology, synaptic architecture and associated neuroplasticity. However, the effects of moderate levels of long-term alcohol intake on the brain are a matter of debate. The current study used 2-DE (two-dimensional gel electrophoresis) proteomics to examine proteomic changes in the striatum of male Wistar rats after 8 months of continuous access to a standard off-the-shelf beer in their home cages. Alcohol intake under group-housed conditions during this time was around 3-4 g/kg/day, a level below that known to induce physical dependence in rats. After 8 months of access rats were euthanased and 2-DE proteomic analysis of the striatum was conducted. A total of 28 striatal proteins were significantly altered in the beer drinking rats relative to controls. Strikingly, many of these were dopamine (DA)-related proteins, including tyrosine hydroxylase (an enzyme of DA biosynthesis), pyridoxal phosphate phosphatase (a co-enzyme in DA biosynthesis), DA and cAMP regulating phosphoprotein (a regulator of DA receptors and transporters), protein phosphatase 1 (a signaling protein) and nitric oxide synthase (which modulates DA uptake). Selected protein expression changes were verified using Western blotting. We conclude that long-term moderate alcohol consumption is associated with substantial alterations in the rat striatal proteome, particularly with regard to dopaminergic signaling pathways. This provides potentially important evidence of major neuroadaptations in dopamine systems with daily alcohol consumption at relatively modest levels. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Prefrontal and Striatal Glutamate Differently Relate to Striatal Dopamine: Potential Regulatory Mechanisms of Striatal Presynaptic Dopamine Function?

    PubMed

    Gleich, Tobias; Deserno, Lorenz; Lorenz, Robert Christian; Boehme, Rebecca; Pankow, Anne; Buchert, Ralph; Kühn, Simone; Heinz, Andreas; Schlagenhauf, Florian; Gallinat, Jürgen

    2015-07-01

    Theoretical and animal work has proposed that prefrontal cortex (PFC) glutamate inhibits dopaminergic inputs to the ventral striatum (VS) indirectly, whereas direct VS glutamatergic afferents have been suggested to enhance dopaminergic inputs to the VS. In the present study, we aimed to investigate relationships of glutamate and dopamine measures in prefrontostriatal circuitries of healthy humans. We hypothesized that PFC and VS glutamate, as well as their balance, are differently associated with VS dopamine. Glutamate concentrations in the left lateral PFC and left striatum were assessed using 3-Tesla proton magnetic resonance spectroscopy. Striatal presynaptic dopamine synthesis capacity was measured by fluorine-18-l-dihydroxyphenylalanine (F-18-FDOPA) positron emission tomography. First, a negative relationship was observed between glutamate concentrations in lateral PFC and VS dopamine synthesis capacity (n = 28). Second, a positive relationship was revealed between striatal glutamate and VS dopamine synthesis capacity (n = 26). Additionally, the intraindividual difference between PFC and striatal glutamate concentrations correlated negatively with VS dopamine synthesis capacity (n = 24). The present results indicate an involvement of a balance in PFC and striatal glutamate in the regulation of VS dopamine synthesis capacity. This notion points toward a potential mechanism how VS presynaptic dopamine levels are kept in a fine-tuned range. A disruption of this mechanism may account for alterations in striatal dopamine turnover as observed in mental diseases (e.g., in schizophrenia). The present work demonstrates complementary relationships between prefrontal and striatal glutamate and ventral striatal presynaptic dopamine using human imaging measures: a negative correlation between prefrontal glutamate and presynaptic dopamine and a positive relationship between striatal glutamate and presynaptic dopamine are revealed. The results may reflect a regulatory role

  7. Interfacial Polymerization of Dopamine in a Pickering Emulsion: Synthesis of Cross-Linkable Colloidosomes and Enzyme Immobilization at Oil/Water Interfaces.

    PubMed

    Qu, Yanning; Huang, Renliang; Qi, Wei; Su, Rongxin; He, Zhimin

    2015-07-15

    Colloidosomes are promising carriers for immobilizing enzyme for catalytic purposes in aqueous/organic media. However, they often suffer from one or more problems regarding catalytic performance, stability, and recyclability. Here, we report a novel approach for the synthesis of cross-linkable colloidosomes by the selective polymerization of dopamine at oil/water interfaces in a Pickering emulsion. An efficient enzyme immobilization method was further developed by covalently bonding enzymes to the polydopamine (PDA) layer along with the formation of such colloidosomes with lipase as a model enzyme. In this enzyme system, the PDA layer served as a cross-linking layer and enzyme support for simultaneously enhancing the colloidosomes' stability and improving surface availability of the enzymes for catalytic reaction. It was found that the specific activity of lipases immobilized on the colloidosome shells was 8 and 1.4 times higher than that of free lipase and encapsulated lipase positioned in the aqueous cores of colloidosomes, respectively. Moreover, the immobilized lipases demonstrated excellent operational stability and recyclability, retaining 86.6% of enzyme activity after 15 cycles. It is therefore reasonable to expect that this novel approach for enzyme immobilization has great potential to serve as an important technique for the construction of biocatalytic systems.

  8. Facile synthesis of NiAl-layered double hydroxide/graphene hybrid with enhanced electrochemical properties for detection of dopamine

    NASA Astrophysics Data System (ADS)

    Li, Meixia; Zhu, Jun E.; Zhang, Lili; Chen, Xu; Zhang, Huimin; Zhang, Fazhi; Xu, Sailong; Evans, David G.

    2011-10-01

    Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clays, have been investigated widely as promising electrochemical active materials. Due to the inherently weak conductivity, the electrochemical properties of LDHs were improved typically by utilization of either functional molecules intercalated between LDH interlayer galleries, or proteins confined between exfoliated LDH nanosheets. Here, we report a facile protocol to prepare NiAl-LDH/graphene (NiAl-LDH/G) nanocomposites using a conventional coprecipitation process under low-temperature conditions and subsequent reduction of the supporting graphene oxide. Electrochemical tests showed that the NiAl-LDH/G modified electrode exhibited highly enhanced electrochemical performance of dopamine electrooxidation in comparison with the pristine NiAl-LDH modified electrode. Results of high-resolution transmission electron microscopy and Raman spectra provide convincing information on the nanostructure and composition underlying the enhancement. Our results of the NiAl-LDH/G modified electrodes with the enhanced electrochemical performance may allow designing a variety of promising hybrid sensors via a simple and feasible approach.Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clays, have been investigated widely as promising electrochemical active materials. Due to the inherently weak conductivity, the electrochemical properties of LDHs were improved typically by utilization of either functional molecules intercalated between LDH interlayer galleries, or proteins confined between exfoliated LDH nanosheets. Here, we report a facile protocol to prepare NiAl-LDH/graphene (NiAl-LDH/G) nanocomposites using a conventional coprecipitation process under low-temperature conditions and subsequent reduction of the supporting graphene oxide. Electrochemical tests showed that the NiAl-LDH/G modified electrode exhibited highly enhanced electrochemical performance of dopamine

  9. Synthesis and in vitro pharmacological evaluation of indolyl carboxylic amide analogues as D3 dopamine receptor selective ligands†

    PubMed Central

    Tu, Zhude; Li, Shihong; Li, Aixiao; Taylor, Michelle; Ho, David; Malik, Maninder; Luedtke, Robert R.

    2013-01-01

    A series of substituted 1H-indolyl carboxylic acid amides that contain a N-(2-methoxyphenyl)piperazine or N-(2-fluoroethoxy)piperazine group were synthesized and their affinities for human dopamine D2, D3, and D4 receptors were determined. Two of these compounds, 14a and 14b, displayed high binding affinity at D3 (Ki = 0.18 and 0.4 nM, respectively), and selectivity for D3 vs. D2 receptors (87-fold and 60-fold, respectively). These two compounds had low binding affinity at D4 receptors and σ receptor sites. The intrinsic activity of these compounds at D2 and D3 receptors was determined using a forskolin-dependent adenylyl cyclase inhibition assay; both 14a and 14b were found to be partial agonists. Furthermore, for compound 14a, the log D value of 2.85 suggested it has suitable lipophilicity for crossing the blood–brain-barrier. PMID:24156012

  10. One-Pot Green Synthesis of Graphene Nanosheets Encapsulated Gold Nanoparticles for Sensitive and Selective Detection of Dopamine

    PubMed Central

    Thirumalraj, Balamurugan; Rajkumar, Chellakannu; Chen, Shen-Ming; Palanisamy, Selvakumar

    2017-01-01

    We report a simple new approach for green preparation of gallic acid supported reduced graphene oxide encapsulated gold nanoparticles (GA-RGO/AuNPs) via one-pot hydrothermal method. The as-prepared composites were successfully characterized by using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray powder diffraction techniques (XRD), scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM) and elemental analysis. The GA-RGO/AuNPs modified electrode behaves as a hybrid electrode material for sensitive and selective detection of dopamine (DA) in presence of ascorbic acid (AA) and uric acid (UA). The GA-RGO/AuNPs modified electrode displays an excellent electrocatalytic activity towards the oxidation of DA and exhibits a wide linear response range over the DA concentrations from 0.01–100.3 μM with a detection limit (LOD) of 2.6 nM based on S/N = 3. In addition, the proposed sensor could be applied for the determination of DA in human serum and urine samples for practical analysis. PMID:28128225

  11. Finely Composition-Tunable Synthesis of Ultrafine Wavy PtRu Nanowires as Effective Electrochemical Sensors for Dopamine Detection.

    PubMed

    Zhao, Weiyue; Ni, Bing; Yuan, Qiang; Wang, Ye; Zhang, Qinghong; Wang, Xun

    2017-08-15

    Preparing Pt-based one-dimensional (1D) ultrafine nanowires with abundant structural defects/grain boundaries and exploring their novel applications have attracted great interest in real-world applications. Here we introduce an environmentally friendly, facile aqueous solution approach to directly prepare a series of sub-3.0 nm PtRu ultrafine wavy nanowires. Characterizations show that the PtRu nanowires are alloy polycrystalline structures with abundant structural defects/grain boundaries. We first introduce the as-synthesized PtRu nanowires into electrochemical biosensors for the detection of DA and find that the Pt7Ru3 nanowires exhibit excellent electrocatalytic activity to DA with fast response, ultralow limit of detection, and excellent selectivity at a potential of 0.3 V in 0.1 M phosphate buffered solution (pH 7.2). This study shows an effective approach to the development of ultrafine PtRu nanowires as electrocatalysts for electrochemical nonenzymatic dopamine biosensors.

  12. Facile synthesis of NiAl-layered double hydroxide/graphene hybrid with enhanced electrochemical properties for detection of dopamine.

    PubMed

    Li, Meixia; Zhu, Jun E; Zhang, Lili; Chen, Xu; Zhang, Huimin; Zhang, Fazhi; Xu, Sailong; Evans, David G

    2011-10-05

    Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clays, have been investigated widely as promising electrochemical active materials. Due to the inherently weak conductivity, the electrochemical properties of LDHs were improved typically by utilization of either functional molecules intercalated between LDH interlayer galleries, or proteins confined between exfoliated LDH nanosheets. Here, we report a facile protocol to prepare NiAl-LDH/graphene (NiAl-LDH/G) nanocomposites using a conventional coprecipitation process under low-temperature conditions and subsequent reduction of the supporting graphene oxide. Electrochemical tests showed that the NiAl-LDH/G modified electrode exhibited highly enhanced electrochemical performance of dopamine electrooxidation in comparison with the pristine NiAl-LDH modified electrode. Results of high-resolution transmission electron microscopy and Raman spectra provide convincing information on the nanostructure and composition underlying the enhancement. Our results of the NiAl-LDH/G modified electrodes with the enhanced electrochemical performance may allow designing a variety of promising hybrid sensors via a simple and feasible approach.

  13. One-Pot Green Synthesis of Graphene Nanosheets Encapsulated Gold Nanoparticles for Sensitive and Selective Detection of Dopamine

    NASA Astrophysics Data System (ADS)

    Thirumalraj, Balamurugan; Rajkumar, Chellakannu; Chen, Shen-Ming; Palanisamy, Selvakumar

    2017-01-01

    We report a simple new approach for green preparation of gallic acid supported reduced graphene oxide encapsulated gold nanoparticles (GA-RGO/AuNPs) via one-pot hydrothermal method. The as-prepared composites were successfully characterized by using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray powder diffraction techniques (XRD), scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM) and elemental analysis. The GA-RGO/AuNPs modified electrode behaves as a hybrid electrode material for sensitive and selective detection of dopamine (DA) in presence of ascorbic acid (AA) and uric acid (UA). The GA-RGO/AuNPs modified electrode displays an excellent electrocatalytic activity towards the oxidation of DA and exhibits a wide linear response range over the DA concentrations from 0.01–100.3 μM with a detection limit (LOD) of 2.6 nM based on S/N = 3. In addition, the proposed sensor could be applied for the determination of DA in human serum and urine samples for practical analysis.

  14. Dopamine D1 agonist R-[11C]SKF 82957: synthesis and in vivo characterization in rats.

    PubMed

    DaSilva, J N; Schwartz, R A; Greenwald, E R; Lourenco, C M; Wilson, A A; Houle, S

    1999-07-01

    The active enantiomer R-SKF 82957 was labeled with 11C by N-[11C]methylation of the full dopamine (D1) agonist R-SKF 81297, using [11C]methyl iodide in the presence of N-ethyldiisopropylamine, in high specific activity, radiochemical purity and yields. Compared with the D1 agonist R/S-[11C]SKF 82957, R-[11C]SKF 82957 showed higher binding in the D1 rich regions, such as striatum and olfactory tubercles (approximately 1.7 times), thereby improving the tissue contrast. R-[11C]SKF 82957 exhibited high in vivo binding selectivity for D1 receptors in rats, because only high doses of D1 competitors, but not D2 or serotonin (5-HT2) blockers, significantly reduced the radioactivity levels in all brain areas. No labeled metabolites were detected in rat brain. These results indicate that R-[11C]SKF 82957 will provide more sensitive measurements of D1 receptors in in vivo studies than the racemic mixture.

  15. Synthesis of 8-thiabicyclo[3.2.1]octanes and Their Binding Affinity for the Dopamine and Serotonin Transporters

    PubMed Central

    Pham-Huu, Duy-Phong; Deschamps, Jeffrey R.; Liu, Shanghao; Madras, Bertha K.; Meltzer, Peter C.

    2007-01-01

    Cocaine is a potent stimulant of the central nervous system. Its reinforcing and stimulant properties have been associated with inhibition of the dopamine transporter (DAT) on presynaptic neurons. In the search for medications for cocaine abuse, we have prepared 2-carbomethoxy-3-aryl-8-thiabicyclo[3.2.1]octane analogues of cocaine. We report that this class of compounds provides potent and selective inhibitors of the DAT and SERT. The selectivity resulted from reduced activity at the SERT. The 3β-(3,4-dichlorophenyl) analogue inhibits the DAT and SERT with a potency of IC50 = 5.7 nM and 8.0 nM respectively. The 3-(3,4-dichlorophenyl)-2,3-unsaturated analogue inhibits the DAT potently (IC50 = 4.5 nM) and selectively (>800-fold vs. SERT). Biological enantioselectivity of DAT inhibition was limited for both the 3-aryl-2,3-unsaturated and the 3α-aryl analogues (2-fold), but more robust (> 10-fold) for the 3β-aryl analogues. The (1R)-configuration provided the eutomers. PMID:17070057

  16. One-Pot Green Synthesis of Graphene Nanosheets Encapsulated Gold Nanoparticles for Sensitive and Selective Detection of Dopamine.

    PubMed

    Thirumalraj, Balamurugan; Rajkumar, Chellakannu; Chen, Shen-Ming; Palanisamy, Selvakumar

    2017-01-27

    We report a simple new approach for green preparation of gallic acid supported reduced graphene oxide encapsulated gold nanoparticles (GA-RGO/AuNPs) via one-pot hydrothermal method. The as-prepared composites were successfully characterized by using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray powder diffraction techniques (XRD), scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM) and elemental analysis. The GA-RGO/AuNPs modified electrode behaves as a hybrid electrode material for sensitive and selective detection of dopamine (DA) in presence of ascorbic acid (AA) and uric acid (UA). The GA-RGO/AuNPs modified electrode displays an excellent electrocatalytic activity towards the oxidation of DA and exhibits a wide linear response range over the DA concentrations from 0.01-100.3 μM with a detection limit (LOD) of 2.6 nM based on S/N = 3. In addition, the proposed sensor could be applied for the determination of DA in human serum and urine samples for practical analysis.

  17. Synthesis and evaluation of novel azetidine analogs as potent inhibitors of vesicular [3H]dopamine uptake.

    PubMed

    Ding, Derong; Nickell, Justin R; Deaciuc, Agripina G; Penthala, Narsimha Reddy; Dwoskin, Linda P; Crooks, Peter A

    2013-11-01

    Lobelane analogs that incorporate a central piperidine or pyrrolidine moiety have previously been reported by our group as potent inhibitors of VMAT2 function. Further central ring size reduction of the piperidine moiety in lobelane to a four-membered heterocyclic ring has been carried out in the current study to afford novel cis-and trans-azetidine analogs. These azetidine analogs (15a-15c and 22a-22c) potently inhibited [(3)H]dopamine (DA) uptake into isolated synaptic vesicles (Ki⩽66nM). The cis-4-methoxy analog 22b was the most potent inhibitor (Ki=24nM), and was twofold more potent that either lobelane (2a, Ki=45nM) or norlobelane (2b, Ki=43nM). The trans-methylenedioxy analog, 15c (Ki=31nM), was equipotent with the cis-analog, 22b, in this assay. Thus, cis- and trans-azetidine analogs 22b and 15c represent potential leads in the discovery of new clinical candidates for the treatment of methamphetamine abuse. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Particulate wear debris activates protein tyrosine kinases and nuclear factor kappaB, which down-regulates type I collagen synthesis in human osteoblasts.

    PubMed

    Vermes, C; Roebuck, K A; Chandrasekaran, R; Dobai, J G; Jacobs, J J; Glant, T T

    2000-09-01

    Particulate wear debris generated mechanically from prosthetic materials is phagocytosed by a variety of cell types within the periprosthetic space including osteoblasts, which cells with an altered function may contribute to periprosthetic osteolysis. Exposure of osteoblast-like osteosarcoma cells or bone marrow-derived primary osteoblasts to either metallic or polymeric particles of phagocytosable sizes resulted in a marked decrease in the steady-state messenger RNA (mRNA) levels of procollagen alpha1[I] and procollagen alpha1[III]. In contrast, no significant effect was observed for the osteoblast-specific genes, such as osteonectin and osteocalcin (OC). In kinetic studies, particles once phagocytosed, maintained a significant suppressive effect on collagen gene expression and type I collagen synthesis for up to five passages. Large particles of a size that cannot be phagocytosed also down-regulated collagen gene expression suggesting that an initial contact between cells and particles can generate gene responsive signals independently of the phagocytosis process. Concerning such signaling, titanium particles rapidly increased protein tyrosine phosphorylation and nuclear transcription factor kappaB (NF-kappaB) binding activity before the phagocytosis of particles. Protein tyrosine kinase (PTK) inhibitors such as genistein and the NF-kappaB inhibitor pyrrolidine dithiocarbamate (PDTC) significantly reduced the suppressive effect of titanium on collagen gene expression suggesting particles suppress collagen gene expression through the NF-kappaB signaling pathway. These results provide a mechanism by which particulate wear debris can antagonize the transcription of the procollagen alpha1[I] gene in osteoblasts, which may contribute to reduced bone formation and progressive periprosthetic osteolysis.

  19. Levodopa-induced dyskinesias are associated with transient down-regulation of cAMP and cGMP in the caudate-putamen of hemiparkinsonian rats: reduced synthesis or increased catabolism?

    PubMed

    Sancesario, Giuseppe; Morrone, Luigi Antonio; D'Angelo, Vincenza; Castelli, Valentina; Ferrazzoli, Davide; Sica, Francesco; Martorana, Alessandro; Sorge, Roberto; Cavaliere, Federica; Bernardi, Giorgio; Giorgi, Mauro

    2014-12-01

    Second messenger cAMP and cGMP represent a key step in the action of dopamine that modulates directly or indirectly their synthesis. We aimed to verify whether levodopa-induced dyskinesias are associated with changes of the time course of levodopa/dopamine stimulated cAMP and cGMP levels, and/or with changes of their catabolism by phosphodiesterase activity in rats with experimental hemiparkinsonism. Microdialysis and tissue homogenates of the striatal tissues demonstrated that extracellular and intracellular cAMP/cGMP levels were lower in dyskinetic animals during the increasing phase of dyskinesias compared to eukinetic animals, but cAMP/cGMP levels increased in dyskinetic animals during the phase of decreasing and extinction of dyskinesias. Dyskinesias and the abnormal lowering of striatal cGMP and cAMP after levodopa were prevented by pretreatment with the multipotent drug amantadine, outlining the inverse relationship of cAMP/cGMP to dyskinesias. Moreover, dyskinetic animals showed higher striatal hydrolyzing cGMP-phosphodiesterase but not hydrolyzing cAMP-phosphodiesterase activity, suggesting that low cGMP but not cAMP levels could be due to increased catabolism. However, expressions of isozyme phosphodiesterase-1B and -10A highly and specifically located in the basal ganglia were not changed after levodopa in dyskinetic and eukinetic animals: accordingly, selective inhibitors of phosphodiesterase-1B and -10A were ineffective on levodopa dyskinesias. Therefore, the isozyme(s) expressing higher cGMP-phosphodiesterase activity in the striatum of dyskinetic animal should be determined. These observations suggest that dopamine-mediated processes of synthesis and/or degradation of cAMP/cGMP could be acutely impaired in levodopa dyskinesias, opening new ways to understanding physiopathology and treatment.

  20. Effects of aripiprazole and terguride on dopamine synthesis in the dorsal striatum and medial prefrontal cortex of preweanling rats.

    PubMed

    Iñiguez, S D; Cortez, A M; Crawford, C A; McDougall, S A

    2008-01-01

    The purpose of this study was to determine whether aripiprazole, a D2-like partial agonist increasingly prescribed to children, alters DA synthesis via actions at autoreceptors in the dorsal striatum and medial prefrontal cortex (mPFC) of preweanling rats. The ability of dopaminergic agents to alter DOPA accumulation in the striatum and mPFC was measured after NSD-1015 on postnatal day (PD) 20. Dopaminergic tone was manipulated by administering reserpine, gamma-butyrolactone (GBL), or through amphetamine withdrawal. Results showed that the partial agonists aripiprazole and terguride increased striatal DOPA accumulation under normosensitive conditions, but decreased DOPA accumulation in states of low dopaminergic tone. A different pattern of results was observed in the mPFC, because terguride and haloperidol, but not aripiprazole, increased DOPA accumulation under normosensitive conditions. In conclusion, the present data show that aripiprazole affects striatal synthesis modulating autoreceptors in an adult-typical manner during the late preweanling period. Unlike in adult rats, however, the mPFC of preweanling rats appears to contain transitory synthesis modulating autoreceptors that are sensitive to drug manipulation.

  1. Enhanced synthesis and release of dopamine in transgenic mice with gain-of-function α6* nAChRs.

    PubMed

    Wang, Yuexiang; Lee, Jang-Won; Oh, Gyeon; Grady, Sharon R; McIntosh, J Michael; Brunzell, Darlene H; Cannon, Jason R; Drenan, Ryan M

    2014-04-01

    α6β2* nicotinic acetylcholine receptors (nAChRs)s in the ventral tegmental area to nucleus accumbens (NAc) pathway are implicated in the response to nicotine, and recent work suggests these receptors play a role in the rewarding action of ethanol. Here, we studied mice expressing gain-of-function α6β2* nAChRs (α6L9'S mice) that are hypersensitive to nicotine and endogenous acetylcholine. Evoked extracellular dopamine (DA) levels were enhanced in α6L9'S NAc slices compared to control, non-transgenic (non-Tg) slices. Extracellular DA levels in both non-Tg and α6L9'S slices were further enhanced in the presence of GBR12909, suggesting intact DA transporter function in both mouse strains. Ongoing α6β2* nAChR activation by acetylcholine plays a role in enhancing DA levels, as α-conotoxin MII completely abolished evoked DA release in α6L9'S slices and decreased spontaneous DA release from striatal synaptosomes. In HPLC experiments, α6L9'S NAc tissue contained significantly more DA, 3,4-dihydroxyphenylacetic acid, and homovanillic acid compared to non-Tg NAc tissue. Serotonin (5-HT), 5-hydroxyindoleacetic acid, and norepinephrine (NE) were unchanged in α6L9'S compared to non-Tg tissue. Western blot analysis revealed increased tyrosine hydroxylase expression in α6L9'S NAc. Overall, these results show that enhanced α6β2* nAChR activity in NAc can stimulate DA production and lead to increased extracellular DA levels.

  2. Dopamine synapse is a neuroligin-2–mediated contact between dopaminergic presynaptic and GABAergic postsynaptic structures

    PubMed Central

    Uchigashima, Motokazu; Ohtsuka, Toshihisa; Kobayashi, Kazuto; Watanabe, Masahiko

    2016-01-01

    Midbrain dopamine neurons project densely to the striatum and form so-called dopamine synapses on medium spiny neurons (MSNs), principal neurons in the striatum. Because dopamine receptors are widely expressed away from dopamine synapses, it remains unclear how dopamine synapses are involved in dopaminergic transmission. Here we demonstrate that dopamine synapses are contacts formed between dopaminergic presynaptic and GABAergic postsynaptic structures. The presynaptic structure expressed tyrosine hydroxylase, vesicular monoamine transporter-2, and plasmalemmal dopamine transporter, which are essential for dopamine synthesis, vesicular filling, and recycling, but was below the detection threshold for molecules involving GABA synthesis and vesicular filling or for GABA itself. In contrast, the postsynaptic structure of dopamine synapses expressed GABAergic molecules, including postsynaptic adhesion molecule neuroligin-2, postsynaptic scaffolding molecule gephyrin, and GABAA receptor α1, without any specific clustering of dopamine receptors. Of these, neuroligin-2 promoted presynaptic differentiation in axons of midbrain dopamine neurons and striatal GABAergic neurons in culture. After neuroligin-2 knockdown in the striatum, a significant decrease of dopamine synapses coupled with a reciprocal increase of GABAergic synapses was observed on MSN dendrites. This finding suggests that neuroligin-2 controls striatal synapse formation by giving competitive advantage to heterologous dopamine synapses over conventional GABAergic synapses. Considering that MSN dendrites are preferential targets of dopamine synapses and express high levels of dopamine receptors, dopamine synapse formation may serve to increase the specificity and potency of dopaminergic modulation of striatal outputs by anchoring dopamine release sites to dopamine-sensing targets. PMID:27035941

  3. Sunlight assisted synthesis of silver nanoparticles in zeolite matrix and study of its application on electrochemical detection of dopamine and uric acid in urine samples.

    PubMed

    Meenakshi, S; Devi, S; Pandian, K; Devendiran, R; Selvaraj, M

    2016-12-01

    Sunlight assisted reduction of silver ions were accomplished for the synthesis of silver nanoparticles incorporated within the mesoporous silicate framework of zeolite Y. The zeolite-Y and AgNP/Zeo-Y were characterized by field emission scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption BET isotherm and X-ray diffraction techniques. The incorporation of silver nanoparticles within the porous framework was further confirmed by cyclic voltammetry and electrochemical impedance spectroscopy. An enhanced electrocatalytic oxidation of biologically important molecules like dopamine and uric acid using AgNP/Zeo-Y modified glassy carbon electrode has been developed. A simultaneous oxidation of DA and UA peaks were obtained at +0.31V and +0.43V (vs. Ag/AgCl) using AgNP/Zeo-Y/GCE under the optimum experimental condition. A well-resolved peak potential window (~120mV) for the oxidation of both DA and UA were observed at AgNP/Zeo-Y/GCE system. The calibration curves for DA and UA were obtained within the dynamic linear range of 0.02×10(-6) to 0.18×10(-6)M (R(2)=0.9899) and 0.05×10(-6) to 0.7×10(-6)M (R(2)=0.9996) and the detection limits were found to be 1.6×10(-8)M and 2.51×10(-8)M by using differential pulse voltammetry (DPV) method. The proposed method was successfully applied for the determination of both DA and UA in human urine samples with a related standard deviation was <3%, and n=5 using the standard addition method. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. A novel synthesis and pharmacological evaluation of a potential dopamine D1/D2 agonist: 1-propyl-1,2,3,4,4a,5,10,10a-octahydrobenzo[g]quinoline-6,7-diol.

    PubMed

    Liu, Danyang; Dijkstra, Durk; de Vries, Jan B; Wikström, Håkan V

    2008-03-15

    Previously, we have demonstrated that enone prodrugs of dopaminergic catecholamines represent a new type of dopamine (DA) agonist. Trans-1-propyl-1,2,3,4,4a,5,10,10a-octahydrobenzo[g]quinoline-6,7-diol (TL-334), the active form of trans-1-propyl-2,3,4,4a,5,7,8,9,10,10a-decahydro-1H-benzo[g]quinolin-6-one (GMC-6650), in vivo showed an extremely potent dopaminergic activity. Here, we report a novel synthesis and a pharmacological evaluation of TL-334 by means of microdialysis.

  5. Testosterone regulation of sex steroid-related mRNAs and dopamine-related mRNAs in adolescent male rat substantia nigra

    PubMed Central

    2012-01-01

    Background Increased risk of schizophrenia in adolescent males indicates that a link between the development of dopamine-related psychopathology and testosterone-driven brain changes may exist. However, contradictions as to whether testosterone increases or decreases dopamine neurotransmission are found and most studies address this in adult animals. Testosterone-dependent actions in neurons are direct via activation of androgen receptors (AR) or indirect by conversion to 17β-estradiol and activation of estrogen receptors (ER). How midbrain dopamine neurons respond to sex steroids depends on the presence of sex steroid receptor(s) and the level of steroid conversion enzymes (aromatase and 5α-reductase). We investigated whether gonadectomy and sex steroid replacement could influence dopamine levels by changing tyrosine hydroxylase (TH) protein and mRNA and/or dopamine breakdown enzyme mRNA levels [catechol-O-methyl transferase (COMT) and monoamine oxygenase (MAO) A and B] in the adolescent male rat substantia nigra. We hypothesized that adolescent testosterone would regulate sex steroid signaling through regulation of ER and AR mRNAs and through modulation of aromatase and 5α-reductase mRNA levels. Results We find ERα and AR in midbrain dopamine neurons in adolescent male rats, indicating that dopamine neurons are poised to respond to circulating sex steroids. We report that androgens (T and DHT) increase TH protein and increase COMT, MAOA and MAOB mRNAs in the adolescent male rat substantia nigra. We report that all three sex steroids increase AR mRNA. Differential action on ER pathways, with ERα mRNA down-regulation and ERβ mRNA up-regulation by testosterone was found. 5α reductase-1 mRNA was increased by AR activation, and aromatase mRNA was decreased by gonadectomy. Conclusions We conclude that increased testosterone at adolescence can shift the balance of sex steroid signaling to favor androgenic responses through promoting conversion of T to DHT and

  6. Divergence in enzyme regulation between Caenorhabditis elegans and human tyrosine hydroxylase, the key enzyme in the synthesis of dopamine.

    PubMed

    Calvo, Ana C; Pey, Angel L; Miranda-Vizuete, Antonio; Døskeland, Anne P; Martinez, Aurora

    2011-02-15

    TH (tyrosine hydroxylase) is the rate-limiting enzyme in the synthesis of catecholamines. The cat-2 gene of the nematode Caenorhabditis elegans is expressed in mechanosensory dopaminergic neurons and has been proposed to encode a putative TH. In the present paper, we report the cloning of C. elegans full-length cat-2 cDNA and a detailed biochemical characterization of the encoded CAT-2 protein. Similar to other THs, C. elegans CAT-2 is composed of an N-terminal regulatory domain followed by a catalytic domain and a C-terminal oligomerization domain and shows high substrate specificity for L-tyrosine. Like hTH (human TH), CAT-2 is tetrameric and is phosphorylated at Ser35 (equivalent to Ser40 in hTH) by PKA (cAMP-dependent protein kinase). However, CAT-2 is devoid of characteristic regulatory mechanisms present in hTH, such as negative co-operativity for the cofactor, substrate inhibition or feedback inhibition exerted by catecholamines, end-products of the pathway. Thus TH activity in C. elegans displays a weaker regulation in comparison with the human orthologue, resembling a constitutively active enzyme. Overall, our data suggest that the intricate regulation characteristic of mammalian TH might have evolved from more simple models to adjust to the increasing complexity of the higher eukaryotes neuroendocrine systems.

  7. Continuous illumination through larval development suppresses dopamine synthesis in the suprachiasmatic nucleus, causing activation of α-MSH synthesis in the pituitary and abnormal metamorphic skin pigmentation in flounder.

    PubMed

    Itoh, Kae; Washio, Youhei; Fujinami, Yuichiro; Shimizu, Daisuke; Uji, Susumu; Yokoi, Hayato; Suzuki, Tohru

    2012-04-01

    In order to better understand the endocrine aberrations related to abnormal metamorphic pigmentation that appear in flounder larvae reared in tanks, this study examined the effects of continuous 24-h illumination (LL) through larval development on the expression of tyrosine hydroxylase-1 (th1), proopiomelanocortin (pomc), α-melanophore-stimulating hormone (α-MSH) and melanin concentrating hormone (MCH), which are known to participate in the control of background adaptation of body color. We observed two conspicuous deviations in the endocrine system under LL when compared with natural light conditions (LD). First, LL severely suppressed th1 expression in the dopaminergic neurons in the anterior diencephalon, including the suprachiasmatic nucleus (SCN). Second, pomc and α-MSH expression in the pars intermedia melanotrophs was enhanced by LL. Skin color was paler under LL than LD before metamorphic pigmentation, and abnormal metamorphic pigmentation occurred at a higher ratio in LL. We therefore hypothesize that continuous LL inhibited dopamine synthesis in the SCN, which resulted in up-regulation of pomc mRNA expression in the melanotrophs. In spite of the up-regulation of pomc in the melanotrophs, larval skin was adjusted to be pale by MCH which was not affected by LL. Accumulation of α-MSH in the melanotrophs is caused by uncoupling of α-MSH synthesis and secretion due to inhibitory role of MCH on α-MSH secretion, which results in abnormal metamorphic pigmentation by affecting differentiation of adult-type melanophores. Our data demonstrate that continuous illumination at the post-embryonic stage has negative effects on the neuroendocrine system and pituitary in flounder.

  8. Dopamine-Secreting Paraganglioma in the Retroperitoneum.

    PubMed

    Matsuda, Yusuke; Kimura, Noriko; Yoshimoto, Takanobu; Sekiguchi, Yoshihiro; Tomoishi, Junzo; Kasahara, Ichiro; Hara, Yoshihito; Ogawa, Yoshihiro

    2017-03-01

    Pheochromocytomas and paragangliomas, which exclusively produce dopamine, are very rare. Herein, we report for the first time a Japanese case of an exclusively dopamine-producing paraganglioma accompanied by detailed immunohistochemical analyses. A 70-year-old Japanese woman was referred to our hospital for functional examination of her left retroperitoneal mass. Her adrenal functions were normal, except for excessive dopamine secretion. After the tumorectomy, her dopamine level normalized. The histopathological diagnosis of the tumor was paraganglioma; this was confirmed by positive immunostaining of chromogranin A (CgA), tyrosine hydroxylase (TH), dopamine β-hydroxylase (DBH), and succinate dehydrogenase gene subunit B (SDHB). However, the immunostaining of CgA in the tumor cells showed peculiar dot-like staining located corresponding to Golgi complex in the perinuclear area, rather than the diffuse cytoplasmic staining usually observed in epinephrine- or norepinephrine-producing functional pheochromocytomas and paragangliomas. The immunohistochemical results suggested that the tumor cells had sparse neuroendocrine granules in the cytoplasm, resulting in inhibition of catecholamine synthesis from dopamine to norepinephrine in neurosecretory granules. This may be the mechanism responsible for exclusive dopamine secretion in the present case.

  9. Aging-related dysregulation of dopamine and angiotensin receptor interaction.

    PubMed

    Villar-Cheda, Begoña; Dominguez-Meijide, Antonio; Valenzuela, Rita; Granado, Noelia; Moratalla, Rosario; Labandeira-Garcia, Jose L

    2014-07-01

    It is not known whether the aging-related decrease in dopaminergic function leads to the aging-related higher vulnerability of dopaminergic neurons and risk for Parkinson's disease. The renin-angiotensin system (RAS) plays a major role in the inflammatory response, neuronal oxidative stress, and dopaminergic vulnerability via type 1 (AT1) receptors. In the present study, we observed a counterregulatory interaction between dopamine and angiotensin receptors. We observed overexpression of AT1 receptors in the striatum and substantia nigra of young adult dopamine D1 and D2 receptor-deficient mice and young dopamine-depleted rats, together with compensatory overexpression of AT2 receptors or compensatory downregulation of angiotensinogen and/or angiotensin. In aged rats, we observed downregulation of dopamine and dopamine receptors and overexpression of AT1 receptors in aged rats, without compensatory changes observed in young animals. L-Dopa therapy inhibited RAS overactivity in young dopamine-depleted rats, but was ineffective in aged rats. The results suggest that dopamine may play an important role in modulating oxidative stress and inflammation in the substantia nigra and striatum via the RAS, which is impaired by aging.

  10. Recovery of dopamine transporters with methamphetamine detoxification is not linked to changes in dopamine release.

    PubMed

    Volkow, Nora D; Wang, Gene-Jack; Smith, Lisa; Fowler, Joanna S; Telang, Frank; Logan, Jean; Tomasi, Dardo

    2015-11-01

    Methamphetamine's widepread abuse and concerns that it might increase Parkinson's disease led us to assess if the reported loss of dopamine transporters (DAT) in methamphetamine abusers (MA) reflected damage to dopamine neurons. Using PET with [(11)C]cocaine to measure DAT, and with [(11)C]raclopride to measure dopamine release (assessed as changes in specific binding of [(11)C]raclopride between placebo and methylphenidate), which was used as a marker of dopamine neuronal function, we show that MA (n=16), tested during early detoxification, had lower DAT (20-30%) but overall normal DA release in striatum (except for a small decrease in left putamen), when compared to controls (n=15). In controls, DAT were positively correlated with DA release (higher DAT associated with larger DA increases), consistent with DAT serving as markers of DA terminals. In contrast, MA showed a trend for a negative correlation (p=0.07) (higher DAT associated with lower DA increases), consistent with reduced DA re-uptake following DAT downregulation. MA who remained abstinent nine-months later (n=9) showed significant increases in DAT (20%) but methylphenidate-induced dopamine increases did not change. In contrast, in controls, DAT did not change when retested 9 months later but methylphenidate-induced dopamine increases in ventral striatum were reduced (p=0.05). Baseline D2/D3 receptors in caudate were lower in MA than in controls and did not change with detoxification, nor did they change in the controls upon retest. The loss of DAT in the MA, which was not associated with a concomitant reduction in dopamine release as would have been expected if DAT loss reflected DA terminal degneration; as well as the recovery of DAT after protracted detoxification, which was not associated with increased dopamine release as would have been expected if DAT increases reflected terminal regeneration, indicate that the loss of DAT in these MA does not reflect degeneration of dopamine terminals.

  11. Dopamine function in cigarette smokers: an [¹⁸F]-DOPA PET study.

    PubMed

    Bloomfield, Michael A P; Pepper, Fiona; Egerton, Alice; Demjaha, Arsime; Tomasi, Gianpaolo; Mouchlianitis, Elias; Maximen, Levi; Veronese, Mattia; Turkheimer, Federico; Selvaraj, Sudhakar; Howes, Oliver D

    2014-09-01

    Tobacco addiction is a global public health problem. Addiction to tobacco is thought to involve the effects of nicotine on the dopaminergic system. Only one study has previously investigated dopamine synthesis capacity in cigarette smokers. This study, exclusively in male volunteers, reported increased dopamine synthesis capacity in heavy smokers compared with non-smokers. We sought to determine whether dopamine synthesis capacity was elevated in a larger sample of cigarette smokers that included females. Dopamine synthesis capacity was measured in 15 daily moderate smokers with 15 sex- and age-matched control subjects who had never smoked tobacco. Dopamine synthesis capacity (indexed as the influx rate constant K(i)(cer)) was measured with positron emission tomography and 3,4-dihydroxy-6-[(18)F]-fluoro-l-phenylalanine. There was no significant group difference in dopamine synthesis capacity between smokers and non-smoker controls in the whole striatum (t28=0.64, p=0.53) or any of its functional subdivisions. In smokers, there were no significant relationships between the number of cigarettes smoked per day and dopamine synthesis capacity in the whole striatum (r=-0.23, p=0.41) or any striatal subdivision. These findings indicate that moderate smoking is not associated with altered striatal dopamine synthesis capacity.

  12. Synthesis and resolution of (+-)-7-chloro-8-hydroxy-1-(3'-iodophenyl)-3-methyl-2,3,4,5-tetrahydro- 1H-3- benzazepine (TISCH): A high affinity and selective iodinated ligand for CNS D1 dopamine receptor

    SciTech Connect

    Chumpradit, S.; Kung, M.P.; Billings, J.J.; Kung, H.F. )

    1991-03-01

    The synthesis and resolution of (+-)-7-chloro-8-hydroxy-1-(3'-iodophenyl)-3-methyl-2,3,4,5-tetrahydro-1 H-3- benzazepine, (+/-)-TISCH (8) has been achieved by resolution of intermediate 4, the O-methoxyl, 3'-bromo derivative, as the diastereomeric camphor sulfonate salt. The final products, R-(+)-8 and S-(-)-8, were prepared by treatment of R-(+)- or S-(-)-7, the 3'-tributyltin intermediates, with iodine in chloroform, followed by O-demethylation. By using HPLC with a chiral column, the optical purity (greater than 99%) of the intermediates and the final compounds was determined. Radioiodination was achieved by an iodo-destannylation reaction with sodium (125I)iodide and hydrogen peroxide. As expected, the R-(+)-(125I)-8 (the active isomer) displayed high affinity and selectivity to the CNS D-1 receptor in rat striatum tissue preparation (Kd = 0.205 nM). The rank order of potency was as follows: SCH-23390 (1a) greater than (+/-)-8 greater than (+)-butaclamol greater than spiperone, WB4101 greater than dopamine, 5-HT. After an iv injection, the R-(+)-(125I)-8 penetrated the blood-brain barrier with ease and displayed specific regional distribution corresponding to the D-1 receptor density, while the S-(-)-(125I)-8 showed no specific uptake. The data suggest that the ligand may be useful as a pharmacological tool for characterizing the D-1 dopamine receptor. When labeled with I-123, this ligand is a potential agent for in vivo imaging of CNS D-1 dopamine receptor.

  13. Design, synthesis, radiolabeling and in vivo evaluation of carbon-11 labeled N-[2-[4-(3-cyanopyridin-2-yl)piperazin-1-yl]ethyl]-3-methoxybenzamide, a potential Positron Emission Tomography tracer for the dopamine D4 receptors

    PubMed Central

    Lacivita, Enza; De Giorgio, Paola; Lee, Irene T.; Rodeheaver, Sean I.; Weiss, Bryan A.; Fracasso, Claudia; Caccia, Silvio; Berardi, Francesco; Perrone, Roberto; Zhang, Ming-Rong; Maeda, Jun; Higuchi, Makoto; Suhara, Tetsuya; Schetz, John A.; Leopoldo, Marcello

    2010-01-01

    Here we describe the design, synthesis, physicochemical, and pharmacological evaluation of D4 dopamine receptor ligands related to N-[2-[4-(4-chlorophenyl)piperazin-1-yl]ethyl]-3-methoxybenzamide (2). Structural features were incorporated to increase affinity for the target receptor, to improve selectivity over D2 and sigma1 receptors, to enable labeling with carbon-11 or fluorine-18, and to adjust lipophilicity within the range considered optimal for brain penetration and low nonspecific binding. Compounds 7 and 13 showed the overall best characteristics: nanomolar affinity for the D4 receptor, > 100-fold selectivity over D2 and D3 dopamine receptor 5-HT1A, 5-HT2A and 5-HT2C serotonin receptors and sigma1 receptors, and logP = 2.37–2.55. Following intraperitoneal administration, both compounds rapidly entered the central nervous system. The methoxy of N-[2-[4-(3-cyanopyridin-2-yl)piperazin-1-yl]ethyl]-3-methoxybenzamide (7) was radiolabelled with carbon-11 and subjected to PET analysis in non-human primate. [11C]7 time-dependently accumulated to saturation in the posterior eye in the region of the retina, a tissue containing a high density of D4 receptors. PMID:20873719

  14. The effect of alpha-tocopherol on the synthesis, phosphorylation and activity of protein kinase C in smooth muscle cells after phorbol 12-myristate 13-acetate down-regulation.

    PubMed

    Clément, S; Tasinato, A; Boscoboinik, D; Azzi, A

    1997-06-15

    Previous work had established that, in smooth muscle cells, alpha-tocopherol negatively regulates protein kinase C by preventing its activation [Tasinato, A., Boscoboinik, D., Bartoli, G. M., Maroni, P. & Azzi, A. (1995) Proc. Natl Acad. Sci. USA 92, 12190-12194]. In this study, the mechanism by which this event takes place has been analyzed. The regulation by alpha-tocopherol of protein kinase C expression, activity and phosphorylation has been followed during the synthesis of protein kinase C after its down-regulation by phorbol 12-myristate 13-acetate. The data show that protein kinase C isoenzyme alpha is synthesised significantly more (30% 72 h after down-regulation) in the presence of alpha-tocopherol. However, its activity is significantly less (45% diminution) and its phosphorylation state is also decreased (60% diminution). The effect of alpha-tocopherol appears not to be shared by the analogue beta-tocopherol, provided with similar radical-scavenging properties. The data are interpreted in terms of a diminution of protein kinase C phosphorylation, specifically caused by alpha-tocopherol, resulting in a decreased enzyme specific activity.

  15. Role of protein kinase A and class II phosphatidylinositol 3-kinase C2β in the downregulation of KCa3.1 channel synthesis and membrane surface expression by lyso-globotriaosylceramide

    SciTech Connect

    Choi, Ju Yeon; Park, Seonghee

    2016-02-19

    The intermediate conductance calcium-activated potassium channel (KCa3.1) mediates proliferation of many cell types including fibroblasts, and is a molecular target for intervention in various cell proliferative diseases. Our previous study showed that reduction of KCa3.1 channel expression by lyso-globotriaosylceramide (lyso-Gb3) inhibits differentiation into myofibroblasts and collagen synthesis, which might lead to development of ascending thoracic aortic aneurysm secondary to Fabry disease. However, how lyso-Gb3 downregulates KCa3.1 channel expression is unknown. Therefore, we aimed to investigate the underlying mechanisms of lyso-Gb3-mediated KCa3.1 channel downregulation, focusing on the cAMP signaling pathway. We found that lyso-Gb3 increased the intracellular cAMP concentration by upregulation of adenylyl cyclase 6 and inhibited ERK 1/2 phosphorylation through the protein kinase A (PKA) pathway, leading to the inhibition of KCa3.1 channel synthesis, not the exchange protein directly activated by cAMP (Epac) pathway. Moreover, lyso-Gb3 suppressed expression of class II phosphatidylinositol 3-kinase C2β (PI3KC2β) by PKA activation, which reduces the production of phosphatidylinositol 3-phosphate [PI(3)P], and the reduced membrane surface expression of KCa3.1 channel was recovered by increasing the intracellular levels of PI(3)P. Consequently, our findings that lyso-Gb3 inhibited both KCa3.1 channel synthesis and surface expression by increasing intracellular cAMP, and controlled surface expression through changes in PI3KC2β-mediated PI(3)P production, suggest that modulation of PKA and PI3KC2β activity to control of KCa3.1 channel expression can be an alternative important target to attenuate ascending thoracic aortic aneurysms in Fabry disease. - Highlights: • Lyso-Gb3 causes elevation of intracellular cAMP. • Lyso-Gb3 inhibits the ERK 1/2 phosphorylation through PKA, thereby reducing KCa3.1 channel synthesis. • Lyso-Gb3 reduces PI3KC2

  16. Elevated Striatal Dopamine Function in Immigrants and Their Children: A Risk Mechanism for Psychosis.

    PubMed

    Egerton, Alice; Howes, Oliver D; Houle, Sylvain; McKenzie, Kwame; Valmaggia, Lucia R; Bagby, Michael R; Tseng, Huai-Hsuan; Bloomfield, Michael A P; Kenk, Miran; Bhattacharyya, Sagnik; Suridjan, Ivonne; Chaddock, Chistopher A; Winton-Brown, Toby T; Allen, Paul; Rusjan, Pablo; Remington, Gary; Meyer-Lindenberg, Andreas; McGuire, Philip K; Mizrahi, Romina

    2017-03-01

    Migration is a major risk factor for schizophrenia but the neurochemical processes involved are unknown. One candidate mechanism is through elevations in striatal dopamine synthesis and release. The objective of this research was to determine whether striatal dopamine function is elevated in immigrants compared to nonimmigrants and the relationship with psychosis. Two complementary case-control studies of in vivo dopamine function (stress-induced dopamine release and dopamine synthesis capacity) in immigrants compared to nonimmigrants were performed in Canada and the United Kingdom. The Canadian dopamine release study included 25 immigrant and 31 nonmigrant Canadians. These groups included 23 clinical high risk (CHR) subjects, 9 antipsychotic naïve patients with schizophrenia, and 24 healthy volunteers. The UK dopamine synthesis study included 32 immigrants and 44 nonimmigrant British. These groups included 50 CHR subjects and 26 healthy volunteers. Both striatal stress-induced dopamine release and dopamine synthesis capacity were significantly elevated in immigrants compared to nonimmigrants, independent of clinical status. These data provide the first evidence that the effect of migration on the risk of developing psychosis may be mediated by an elevation in brain dopamine function. © The Author 2017. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center.

  17. Elevated Striatal Dopamine Function in Immigrants and Their Children: A Risk Mechanism for Psychosis

    PubMed Central

    Egerton, Alice; Howes, Oliver D.; Houle, Sylvain; McKenzie, Kwame; Valmaggia, Lucia R.; Bagby, Michael R.; Tseng, Huai-Hsuan; Bloomfield, Michael A. P.; Kenk, Miran; Bhattacharyya, Sagnik; Suridjan, Ivonne; Chaddock, Chistopher A.; Winton-Brown, Toby T.; Allen, Paul; Rusjan, Pablo; Remington, Gary; Meyer-Lindenberg, Andreas; McGuire, Philip K.

    2017-01-01

    Abstract Migration is a major risk factor for schizophrenia but the neurochemical processes involved are unknown. One candidate mechanism is through elevations in striatal dopamine synthesis and release. The objective of this research was to determine whether striatal dopamine function is elevated in immigrants compared to nonimmigrants and the relationship with psychosis. Two complementary case–control studies of in vivo dopamine function (stress-induced dopamine release and dopamine synthesis capacity) in immigrants compared to nonimmigrants were performed in Canada and the United Kingdom. The Canadian dopamine release study included 25 immigrant and 31 nonmigrant Canadians. These groups included 23 clinical high risk (CHR) subjects, 9 antipsychotic naïve patients with schizophrenia, and 24 healthy volunteers. The UK dopamine synthesis study included 32 immigrants and 44 nonimmigrant British. These groups included 50 CHR subjects and 26 healthy volunteers. Both striatal stress-induced dopamine release and dopamine synthesis capacity were significantly elevated in immigrants compared to nonimmigrants, independent of clinical status. These data provide the first evidence that the effect of migration on the risk of developing psychosis may be mediated by an elevation in brain dopamine function. PMID:28057720

  18. Targeting dopamine D3 and serotonin 5-HT1A and 5-HT2A receptors for developing effective antipsychotics: synthesis, biological characterization, and behavioral studies.

    PubMed

    Brindisi, Margherita; Butini, Stefania; Franceschini, Silvia; Brogi, Simone; Trotta, Francesco; Ros, Sindu; Cagnotto, Alfredo; Salmona, Mario; Casagni, Alice; Andreassi, Marco; Saponara, Simona; Gorelli, Beatrice; Weikop, Pia; Mikkelsen, Jens D; Scheel-Kruger, Jorgen; Sandager-Nielsen, Karin; Novellino, Ettore; Campiani, Giuseppe; Gemma, Sandra

    2014-11-26

    Combination of dopamine D3 antagonism, serotonin 5-HT1A partial agonism, and antagonism at 5-HT2A leads to a novel approach to potent atypical antipsychotics. Exploitation of the original structure-activity relationships resulted in the identification of safe and effective antipsychotics devoid of extrapyramidal symptoms liability, sedation, and catalepsy. The potential atypical antipsychotic 5bb was selected for further pharmacological investigation. The distribution of c-fos positive cells in the ventral striatum confirmed the atypical antipsychotic profile of 5bb in agreement with behavioral rodent studies. 5bb administered orally demonstrated a biphasic effect on the MK801-induced hyperactivity at dose levels not able to induce sedation, catalepsy, or learning impairment in passive avoidance. In microdialysis studies, 5bb increased the dopamine efflux in the medial prefrontal cortex. Thus, 5bb represents a valuable lead for the development of atypical antipsychotics endowed with a unique pharmacological profile for addressing negative symptoms and cognitive deficits in schizophrenia.

  19. Synthesis and pharmacological evaluation of dual acting ligands targeting the adenosine A2A and dopamine D2 receptors for the potential treatment of Parkinson's disease.

    PubMed

    Jörg, Manuela; May, Lauren T; Mak, Frankie S; Lee, Kiew Ching K; Miller, Neil D; Scammells, Peter J; Capuano, Ben

    2015-01-22

    A relatively new strategy in drug discovery is the development of dual acting ligands. These molecules are potentially able to interact at two orthosteric binding sites of a heterodimer simultaneously, possibly resulting in enhanced subtype selectivity, higher affinity, enhanced or modified physiological response, and reduced reliance on multiple drug administration regimens. In this study, we have successfully synthesized a series of classical heterobivalent ligands as well as a series of more integrated and "drug-like" dual acting molecules, incorporating ropinirole as a dopamine D2 receptor agonist and ZM 241385 as an adenosine A2A receptor antagonist. The best compounds of our series maintained the potency of the original pharmacophores at both receptors (adenosine A2A and dopamine D2). In addition, the integrated dual acting ligands also showed promising results in preliminary blood-brain barrier permeability tests, whereas the classical heterobivalent ligands are potentially more suited as pharmacological tools.

  20. Synthesis and Characterization of Selective Dopamine D2 Receptor Antagonists. 2. Azaindole, Benzofuran, and Benzothiophene Analogs of L-741,626

    PubMed Central

    Vangveravong, Suwanna; Taylor, Michelle; Xu, Jinbin; Cui, Jinquan; Calvin, Wesley; Babic, Sonja; Luedtke, Robert R.; Mach, Robert H.

    2010-01-01

    A series of indole, 7-azaindole, benzofuran, and benzothiophene compounds have been prepared and evaluated for affinity at D2-like dopamine receptors. These compounds share structural elements with the classical D2-like dopamine receptor antagonists haloperidol, N-methylspiperone and benperidol. Two new compounds, 4-(4-iodophenyl)-1-((4-methoxy-1H-indol-3-yl)methyl)piperidin-4-ol (6) and 4-(4-iodophenyl)-1-((5-methoxy-1H-indol-3-yl)methyl)piperidin-4-ol (7), were found to have high affinity to and selectivity for D2 versus D3 receptors. Changing the aromatic ring system from an indole to other heteroaromatic ring systems reduced the D2 binding affinity and the D2 versus D3 selectivity. PMID:20542439

  1. Synthesis and characterization of cellulose-functionalized 3,4-dihydroxyphenylalanine(dopamine)/silica-gold nanomaterials by sol-gel process.

    NASA Astrophysics Data System (ADS)

    Ramesh, Sivalingam; Kim, Joo-Hyung

    2012-10-01

    Cellulose-metal oxide nanomaterials were developed the technologies to manipulate self-assembly and multi-functionallity, of new technologies to the point where industry can produce advanced and cost-competitive cellulose and lignocellulose-based materials. The present investigation focused on cellulose-silica and cellulose functionalized 3,4-dihydroxy phenyl alanine(dopamine) silica/gold nanomaterials by in-situ sol-gel process. The tetraethoxysilane (TEOS) and gold precursors such as tetrachloroauricacid (HAuCl4) and γ- aminopropyltriethoxysilane (γ-APTES) as coupling agent were used for sol-gel crosslinking process. The chemical and morphological properties of cellulose/silica and cellulose /silica-gold nanomaterials via covalent crosslinking hybrids were investigated with FTIR, XRD, SEM and TEM analysis. The results show that cellulose/silica and cellulose functionalized dopamine-silica/gold hybrids form new macromolecular structures in the size of 20 nm.

  2. Dopamine-assisted one-pot synthesis of zinc ferrite-embedded porous carbon nanospheres for ultrafast and stable lithium ion batteries.

    PubMed

    Yao, Xiayin; Zhao, Chenyang; Kong, Junhua; Wu, Huiqing; Zhou, Dan; Lu, Xuehong

    2014-12-04

    Polydopamine-derived carbon (C-PDA) nanospheres embedded with zinc ferrite (ZnFe2O4) are synthesized by in situ polymerization of dopamine with zinc and iron species followed by carbonization. The composite nanospheres contain ZnFe2O4 nanoparticles ∼8 nm in size well dispersed in porous C-PDA. The unique structure and morphology endow the nanospheres with excellent rate capability and cycling stability for use as anodes in lithium-ion batteries.

  3. Transition-metal-ion-mediated polymerization of dopamine: mussel-inspired approach for the facile synthesis of robust transition-metal nanoparticle-graphene hybrids.

    PubMed

    Yang, Liping; Kong, Junhua; Zhou, Dan; Ang, Jia Ming; Phua, Si Lei; Yee, Wu Aik; Liu, Hai; Huang, Yizhong; Lu, Xuehong

    2014-06-16

    Inspired by the high transition-metal-ion content in mussel glues, and the cross-linking and mechanical reinforcement effects of some transition-metal ions in mussel threads, high concentrations of nickel(II), cobalt(II), and manganese(II) ions have been purposely introduced into the reaction system for dopamine polymerization. Kinetics studies were conducted for the Ni(2+)-dopamine system to investigate the polymerization mechanism. The results show that the Ni(2+) ions could accelerate the assembly of dopamine oligomers in the polymerization process. Spectroscopic and electron microscopic studies reveal that the Ni(2+) ions are chelated with polydopamine (PDA) units, forming homogeneous Ni(2+)-PDA complexes. This facile one-pot approach is utilized to construct transition-metal-ion-PDA complex thin coatings on graphene oxide, which can be carbonized to produce robust hybrid nanosheets with well-dispersed metallic nickel/metallic cobalt/manganese(II) oxide nanoparticles embedded in PDA-derived thin graphitic carbon layers. The nickel-graphene hybrid prepared by using this approach shows good catalytic properties and recyclability for the reduction of p-nitrophenol. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Recovery of hypothalamic tuberoinfundibular dopamine neurons from acute toxicant exposure is dependent upon protein synthesis and associated with an increase in parkin and ubiquitin carboxy-terminal hydrolase-L1 expression.

    PubMed

    Benskey, Matthew; Behrouz, Bahareh; Sunryd, Johan; Pappas, Samuel S; Baek, Seung-Hoon; Huebner, Marianne; Lookingland, Keith J; Goudreau, John L

    2012-06-01

    Hypothalamic tuberoinfundibular dopamine (TIDA) neurons remain unaffected in Parkinson disease (PD) while there is significant degeneration of midbrain nigrostriatal dopamine (NSDA) neurons. A similar pattern of susceptibility is observed in acute and chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse and rotenone rat models of degeneration. It is not known if the resistance of TIDA neurons is a constitutive or induced cell-autonomous phenotype for this unique subset of DA neurons. In the present study, treatment with a single injection of MPTP (20 mg/kg; s.c.) was employed to examine the response of TIDA versus NSDA neurons to acute injury. An acute single dose of MPTP caused an initial loss of DA from axon terminals of both TIDA and NSDA neurons, with recovery occurring solely in TIDA neurons by 16 h post-treatment. Initial loss of DA from axon terminals was dependent on a functional dopamine transporter (DAT) in NSDA neurons but DAT-independent in TIDA neurons. The active metabolite of MPTP, 1-methyl, 4-phenylpyradinium (MPP+), reached higher concentration and was eliminated slower in TIDA compared to NSDA neurons, which indicates that impaired toxicant bioactivation or distribution is an unlikely explanation for the observed resistance of TIDA neurons to MPTP exposure. Inhibition of protein synthesis prevented TIDA neuron recovery, suggesting that the ability to recover from injury was dependent on an induced, rather than a constitutive cellular mechanism. Further, there were no changes in total tyrosine hydroxylase (TH) expression following MPTP, indicating that up-regulation of the rate-limiting enzyme in DA synthesis does not account for TIDA neuronal recovery. Differential candidate gene expression analysis revealed a time-dependent increase in parkin and ubiquitin carboxyl-terminal hydrolase-L1 (UCH-L1) expression (mRNA and protein) in TIDA neurons during recovery from injury. Parkin expression was also found to increase with incremental

  5. Requirement for the eIF4E binding proteins for the synergistic down-regulation of protein synthesis by hypertonic conditions and mTOR inhibition.

    PubMed

    Clemens, Michael J; Elia, Androulla; Morley, Simon J

    2013-01-01

    The protein kinase mammalian target of rapamycin (mTOR) regulates the phosphorylation and activity of several proteins that have the potential to control translation, including p70S6 kinase and the eIF4E binding proteins 4E-BP1 and 4E-BP2. In spite of this, in exponentially growing cells overall protein synthesis is often resistant to mTOR inhibitors. We report here that sensitivity of wild-type mouse embryonic fibroblasts (MEFs) to mTOR inhibitors can be greatly increased when the cells are subjected to the physiological stress imposed by hypertonic conditions. In contrast, protein synthesis in MEFs with a double knockout of 4E-BP1 and 4E-BP2 remains resistant to mTOR inhibitors under these conditions. Phosphorylation of p70S6 kinase and protein kinase B (Akt) is blocked by the mTOR inhibitor Ku0063794 equally well in both wild-type and 4E-BP knockout cells, under both normal and hypertonic conditions. The response of protein synthesis to hypertonic stress itself does not require the 4E-BPs. These data suggest that under certain stress conditions: (i) translation has a greater requirement for mTOR activity and (ii) there is an absolute requirement for the 4E-BPs for regulation by mTOR. Importantly, dephosphorylation of p70S6 kinase and Akt is not sufficient to affect protein synthesis acutely.

  6. Down-regulation of bile acid synthesis and a metabolic co-activator under hypoxic conditions - implications in obstructive sleep apnea.

    PubMed

    Johnson, Paul R

    2008-10-01

    Obstructive sleep apnea is characterized by episodes of intermittent hypoxia that occur while the afflicted person sleeps, and is believed to affect and have a negative impact on many people worldwide. Both observational evidence in obstructive sleep apnea patients and direct studies in mice mimicking the disease strongly support an increased risk for atherosclerosis in these groups. Studies to date on atherosclerosis in obstructive sleep apnea have been focused on cholesterol synthesis. However, dysregulation of bile acid synthesis, which is an important means of cholesterol removal, has not been considered in any sleep disorder model to date. While the relationship between hypoxia and bile acid regulation has been explored in a variety of models, no unifying theory currently ties in the pathologic effect of intermittent hypoxia on bile acid regulation in humans or animals. The goal of this article is to propose the role intermittent hypoxia plays in disrupting bile acid synthesis in patients with obstructive sleep apnea, and its metabolic consequences. Reviewed and discussed are the complex interactions of several key molecular players known to be involved in metabolism with emphasis on the principle bile acid synthesis enzyme, cholesterol 7-alpha-hydroxylase, which is proposed to have reduced activity under hypoxic conditions. Furthermore, the metabolic consequences of reduced levels of active peroxisome proliferator-activated receptor-gamma co-activator-1alpha (PGC-1alpha) under hypoxia, and hypothetically in obstructive sleep apnea, are explored. A better molecular understanding of bile acid synthesis and metabolic dysregulation in this context will hopefully promote the study of new targets in human sleep apneas, and encourage clinical trials using existing therapeutic and dietary interventions in patients afflicted with these conditions.

  7. Restoration of the Dopamine Transporter through Cell Therapy Improves Dyskinesia in a Rat Model of Parkinson's Disease.

    PubMed

    Tomas, D; Stanic, D; Chua, H K; White, K; Boon, W C; Horne, M

    2016-01-01

    The dyskinesia of Parkinson's Disease is most likely due to excess levels of dopamine in the striatum. The mechanism may be due to aberrant synthesis but also, a deficiency or absence of the Dopamine Transporter. In this study we have examined the proposition that reinstating Dopamine Transporter expression in the striatum would reduce dyskinesia. We transplanted c17.2 cells that stably expressed the Dopamine Transporter into dyskinetic rats. There was a reduction in dyskinesia in rats that received grafts expressing the Dopamine Transporter. Strategies designed to increase Dopamine Transporter in the striatum may be useful in treating the dyskinesia associated with human Parkinson's Disease.

  8. The unfolded protein response is activated in skeletal muscle by high-fat feeding: potential role in the downregulation of protein synthesis.

    PubMed

    Deldicque, Louise; Cani, Patrice D; Philp, Andrew; Raymackers, Jean-Marc; Meakin, Paul J; Ashford, Michael L J; Delzenne, Nathalie M; Francaux, Marc; Baar, Keith

    2010-11-01

    High-fat diets are known to decrease muscle protein synthesis, the adaptation to overload, and insulin sensitivity. Conditions that disrupt endoplasmic reticulum (ER) homeostasis lead to the activation of the unfolded protein response (UPR) that is associated with decreases in protein synthesis, chronic inflammation, and insulin resistance. The purpose of the present study was to establish whether ER stress is induced by a high-fat diet in skeletal muscle and whether ER stress can decrease mTORC1 activity and protein synthesis in muscle cells. Two independent protocols of high-fat feeding activated the UPR in mice. In the first study, mice consuming a high-fat diet containing 70% fat and <1% carbohydrates for 6 wk showed higher markers of the UPR (BiP, IRE1α, and MBTPS2) in the soleus and in the tibialis anterior muscles and ATF4 in the tibialis anterior (P < 0.05). In the second study, a 20-wk high-fat diet containing 46% fat and 36% carbohydrates also increased BiP, IRE1α, and phospho-PERK protein and the expression of ATF4, CHOP, and both the spliced and unspliced forms of XBP1 in the plantar flexors (P < 0.05). In C(2)C(12) muscle cells, tunicamycin, thapsigargin, and palmitic acid all increased UPR markers and decreased phosphorylation of S6K1 (P < 0.05). Collectively, these data show that a high-fat diet activates the UPR in mouse skeletal muscle in vivo. In addition, in vitro studies indicate that palmitic acid, and other well-known ER stress inducers, triggered the UPR in myogenic cells and led to a decrease in protein synthesis and mTORC1 activity.

  9. Synthesis and characterization of a novel series of agonist compounds as potential radiopharmaceuticals for imaging dopamine D₂/₃ receptors in their high-affinity state.

    PubMed

    van Wieringen, Jan-Peter; Shalgunov, Vladimir; Janssen, Henk M; Fransen, P Michel; Janssen, Anton G M; Michel, Martin C; Booij, Jan; Elsinga, Philip H

    2014-01-23

    Imaging of dopamine D2/3 receptors (D2/3R) can shed light on the nature of several neuropsychiatric disorders in which dysregulation of D2/3R signaling is involved. Agonist D2/3 tracers for PET/SPECT imaging are considered to be superior to antagonists because they are more sensitive to dopamine concentrations and may selectively label the high-affinity receptor state. Carbon-11-labeled D2/3R agonists have been developed, but these short-lived tracers can be used only in centers with a cyclotron. Here, we report the development of a series of novel D2R agonist compounds based on the 2-aminomethylchromane (AMC) scaffold that provides ample opportunities for the introduction of longer-lived [(18)F] or [(123)I]. Binding experiments showed that several AMC compounds have a high affinity and selectivity for D2/3R and act as agonists. Two fluorine-containing compounds were [(18)F]-labeled, and both displayed specific binding to striatal D2/3R in rat brain slices in vitro. These findings encourage further in vivo evaluations.

  10. Gd-DTPA-Dopamine-Bisphytanyl Amphiphile: Synthesis, Characterisation and Relaxation Parameters of the Nanoassemblies and Their Potential as MRI Contrast Agents.

    PubMed

    Gupta, Abhishek; Willis, Scott A; Waddington, Lynne J; Stait-Gardner, Tim; de Campo, Liliana; Hwang, Dennis W; Kirby, Nigel; Price, William S; Moghaddam, Minoo J

    2015-09-28

    Here, a new amphiphilic magnetic resonance imaging (MRI) contrast agent, a Gd(III)-chelated diethylenetriaminepentaacetic acid conjugated to two branched alkyl chains via a dopamine spacer, Gd-DTPA-dopamine-bisphytanyl (Gd-DTPA-Dop-Phy), which is readily capable of self-assembling into liposomal nanoassemblies upon dispersion in an aqueous solution, is reported. In vitro relaxivities of the dispersions were found to be much higher than Magnevist, a commercially available contrast agent, at 0.47 T but comparable at 9.40 T. Analysis of variable temperature (17)O NMR transverse relaxation measurements revealed the water exchange of the nanoassemblies to be faster than that previously reported for paramagnetic liposomes. Molecular reorientation dynamics were probed by (1)H NMRD profiles using a classical inner and outer sphere relaxation model and a Lipari-Szabo "model-free" approach. High payloads of Gd(III) ions in the liposomal nanoassemblies made solely from the Gd-DTPA-Dop-Phy amphiphiles, in combination with slow molecular reorientation and fast water exchange makes this novel amphiphile a suitable candidate to be investigated as an advanced MRI contrast agent.

  11. Sport physiology, dopamine and nitric oxide - Some speculations and hypothesis generation.

    PubMed

    Landers, J G; Esch, Tobias

    2015-12-01

    Elite Spanish professional soccer players surprisingly showed a preponderance of an allele coding for nitric oxide synthase (NOS) that resulted in lower nitric oxide (NO) compared with Spanish endurance and power athletes and sedentary men. The present paper attempts a speculative explanation. Soccer is an "externally-paced" (EP) sport and team work dependent, requiring "executive function skills". We accept that time interval estimation skill is, in part, also an executive skill. Dopamine (DA) is prominent among the neurotransmitters with a role in such skills. Polymorphisms affecting dopamine (especially DRD2/ANKK1-Taq1a which leads to lower density of dopamine D2 receptors in the striatum, leading to increased striatal dopamine synthesis) and COMT val 158 met (which prolongs the action of dopamine in the cortex) feature both in the time interval estimation and the executive skills literatures. Our paper may be a pioneering attempt to stimulate empirical efforts to show how genotypes among soccer players may be connected via neurotransmitters to certain cognitive abilities that predict sporting success, perhaps also in some other externally-paced team sports. Graphing DA levels against time interval estimation accuracy and also against certain executive skills reveals an inverted-U relationship. A pathway from DA, via endogenous morphine and mu3 receptors on endothelia, to the generation of NO in tiny quantities has been demonstrated. Exercise up-regulates DA and this pathway. With somewhat excessive exercise, negative feedback from NO down-regulates DA, hypothetically keeping it near the peak of the inverted-U. Other research, not yet done on higher animals or humans, shows NO "fine-tuning" movement. We speculate that Caucasian men, playing soccer recreationally, would exemplify the above pattern and their nitric oxide synthase (NOS) would reflect the norm of their community, whereas professional players of soccer and perhaps other EP sports, with DA boosted by

  12. Nitric oxide down-regulation of carotenoid synthesis and PSII activity in relation to very high light-induced singlet oxygen production and oxidative stress in Chlamydomonas reinhardtii.

    PubMed

    Chang, Hsueh-Ling; Hsu, Yuan-Ting; Kang, Cheng-Yang; Lee, Tse-Min

    2013-08-01

    Nitric oxide (NO) was produced in Chlamydomonas reinhardtii cells 30 min after illumination at a very high light intensity of 3,000 µmol m⁻² s⁻¹ (VHL) followed by singlet oxygen (¹O₂) production, lipid peroxidation, expression of oxidative stress-related genes, irreversible PSII inactivation and cell death. Treatment with 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), an NO scavenger, effectively reduced ¹O₂ levels and VHL damage, while treatment with diphenylamine (DPA), an ¹O₂ scavenger, only slightly reduced NO levels, though VHL damage was still effectively reduced. In the presence of cPTIO, the decline in minimum (Fo, Ft) and maximum (Fm, Fm') fluorescence after 60 min of VHL illumination can be slowed, and after recovery to 50 µmol m⁻² s⁻¹ conditions, PSII activity (Fv/Fm, Fv'/Fm') and PSII donor-side and acceptor-side electron transfer were partially restored. This finding indicates that ¹O₂ production is induced by NO through inhibition of PSII electron transfer under VHL conditions. VHL illumination caused a decrease in carotenoid contents but a transient increase in the transcription of two enzymes involved in carotenoid synthesis, phytoene synthase (PSY) and phytoene desaturase (PDS), at 30 min followed by a decrease at 60 min. The VHL-induced decrease in PDS transcription can be inhibited in the presence of cPTIO. The results of the present study show that NO generated in C. reinhardtii cells under VHL conditions induces ¹O₂ accumulation due to a decrease in the ¹O₂-scavenging capacity caused by NO-mediated inhibition of carotenoid synthesis and PSII electron transport, which, in turn, leads to oxidative damage and cell death.

  13. Semisynthetic homoharringtonine induces apoptosis via inhibition of protein synthesis and triggers rapid myeloid cell leukemia-1 down-regulation in myeloid leukemia cells.

    PubMed

    Tang, Ruoping; Faussat, Anne-Marie; Majdak, Patricia; Marzac, Christophe; Dubrulle, Sabine; Marjanovic, Zora; Legrand, Ollivier; Marie, Jean-Pierre

    2006-03-01

    Semisynthetic homoharringtonine (ssHHT) is now being evaluated in phase II clinical trials for the treatment of chronic myelogenous leukemia and acute myelogenous leukemia patients. Here, we examined the mechanism of the apoptosis induced by ssHHT in myeloid leukemia cells. First, we have shown that ssHHT induces apoptosis in HL60 and HL60/MRP cell lines in a time- and dose-dependent manner, and independently of the expression of Bax. The decrease of mitochondrial membrane potential and the release of cytochrome c were observed in the apoptotic cells induced by ssHHT. To unveil the relationship between ssHHT and the mitochondrial disruption, we have shown that ssHHT decreased myeloid cell leukemia-1 (Mcl-1) expression and induced Bcl-2 cleavage in HL60 and HL60/MRP cell lines. The Bcl-2 cleavage could be inhibited by the Z-VAD.fmk caspase inhibitor. However, Mcl-1 turnover was very rapid and occurred before caspase activation. The Mcl-1 turnover was only induced by ssHHT and cycloheximide, but not by daunorubicin and cytosine arabinoside, and could be restored by proteasome inhibitors. Second, we confirmed that ssHHT rapidly induced massive apoptosis in acute myelogenous leukemia patient cells. We have also confirmed the release of cytochrome c and a rapid turnover of Mcl-1 in these patient cells, taking place only in apoptotic cells induced by ssHHT but not in cells undergoing spontaneous apoptosis. Finally, we have shown that ssHHT inhibits protein synthesis in both cell line and patient cells. We suggest that the inhibition of protein synthesis and resulting Mcl-1 turnover play a key role in the apoptosis induced by ssHHT. Our results encourage further clinical trials for the use of ssHHT in acute myelogenous leukemia.

  14. Down-regulation of collagen synthesis and matrix metalloproteinase expression in myofibroblasts from Dupuytren nodule using adenovirus-mediated relaxin gene therapy.

    PubMed

    Kang, Young-Mi; Choi, Yun-Rak; Yun, Chae-Ok; Park, Jin-Oh; Suk, Kyung-Soo; Kim, Hak-Sun; Park, Moon-Soo; Lee, Byung-Ho; Lee, Hwan-Mo; Moon, Seong-Hwan

    2014-04-01

    Dupuytren's disease is a fibroproliferative connective tissue disorder characterized by contracture of the palmer fascia of the hand. Relaxin (RLN) is a multifunctional factor which contributes to the remodeling of the pelvic ligament by inhibiting fibrosis and inflammatory activities. The aim of this study was to investigate the effect of the RLN gene on the inhibition of fibrosis in myofibroblastic cells. Myofibroblast cells with adenovirus LacZ (Ad-LacZ) as a marker gene or adenovirus relaxin (Ad-RLN) as therapeutic gene showed transgene expressions in beta-galactosidase assay and Western blot analysis. Myofibroblastic cells with Ad-RLN demonstrated a 22% and 48% reduction in collagen I and III mRNA expressions respectively, a 50% decrease in MMP-1, 70% decrease in MMP-2, 80% decrease in MMP-9, and a 15% reduction in MMP-13 protein expression compared with cultures with viral control and saline control. In addition, myofibroblastic cells with Ad-RLN showed a 40% decrease in TIMP 1 and a 15% increase in TIMP 3 protein expression at 48 h compared to cultures with viral control and saline control. Also, myofibroblastic cell with Ad-RLN demonstrated a 74% inhibition of fibronectin and a 52% decrease in total collagen synthesis at 48 h compared with cultures with viral control and saline control. In conclusion, the RLN gene render antifibrogenic effect on myofibroblastic cells from Dupuytren's nodule via direct inhibition of collagen synthesis not through collagenolytic pathway such as MMP-1, -13, TIMP 1, and 3. Therefore relaxin can be an alternative therapeutic strategy in initial stage of Dupuytren's disease by its antifibrogenic effect. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  15. Cytokine Effects on the Basal Ganglia and Dopamine Function: the Subcortical Source of Inflammatory Malaise

    PubMed Central

    Felger, Jennifer C.; Miller, Andrew H.

    2012-01-01

    Data suggest that cytokines released during the inflammatory response target subcortical structures including the basal ganglia as well as dopamine function to acutely induce behavioral changes that support fighting infection and wound healing. However, chronic inflammation and exposure to inflammatory cytokines appears to lead to persisting alterations in the basal ganglia and dopamine function reflected by anhedonia, fatigue, and psychomotor slowing. Moreover, reduced neural responses to hedonic reward, decreased dopamine metabolites in the cerebrospinal fluid and increased presynaptic dopamine uptake and decreased turnover have been described. This multiplicity of changes in the basal ganglia and dopamine function suggest fundamental effects of inflammatory cytokines on dopamine synthesis, packaging, release and/or reuptake, which may sabotage and circumvent the efficacy of current treatment approaches. Thus, examination of the mechanisms by which cytokines alter the basal ganglia and dopamine function will yield novel insights into the treatment of cytokine-induced behavioral changes and inflammatory malaise. PMID:23000204

  16. Cytokine effects on the basal ganglia and dopamine function: the subcortical source of inflammatory malaise.

    PubMed

    Felger, Jennifer C; Miller, Andrew H

    2012-08-01

    Data suggest that cytokines released during the inflammatory response target subcortical structures including the basal ganglia as well as dopamine function to acutely induce behavioral changes that support fighting infection and wound healing. However, chronic inflammation and exposure to inflammatory cytokines appears to lead to persisting alterations in the basal ganglia and dopamine function reflected by anhedonia, fatigue, and psychomotor slowing. Moreover, reduced neural responses to hedonic reward, decreased dopamine metabolites in the cerebrospinal fluid and increased presynaptic dopamine uptake and decreased turnover have been described. This multiplicity of changes in the basal ganglia and dopamine function suggest fundamental effects of inflammatory cytokines on dopamine synthesis, packaging, release and/or reuptake, which may sabotage and circumvent the efficacy of current treatment approaches. Thus, examination of the mechanisms by which cytokines alter the basal ganglia and dopamine function will yield novel insights into the treatment of cytokine-induced behavioral changes and inflammatory malaise. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Azido-iodo-N-benzyl derivatives of threo-methylphenidate (Ritalin, Concerta): Rational design, synthesis, pharmacological evaluation, and dopamine transporter photoaffinity labeling.

    PubMed

    Lapinsky, David J; Velagaleti, Ranganadh; Yarravarapu, Nageswari; Liu, Yi; Huang, Yurong; Surratt, Christopher K; Lever, John R; Foster, James D; Acharya, Rejwi; Vaughan, Roxanne A; Deutsch, Howard M

    2011-01-01

    In contrast to tropane-based compounds such as benztropine and cocaine, non-tropane-based photoaffinity ligands for the dopamine transporter (DAT) are relatively unexplored. Towards addressing this knowledge gap, ligands were synthesized in which the piperidine nitrogen of 3- and 4-iodomethylphenidate was substituted with a benzyl group bearing a photoreactive azide. Analog (±)-3a demonstrated modest DAT affinity and a radioiodinated version was shown to bind covalently to rat striatal DAT and hDAT expressed in cultured cells. Co-incubation of (±)-3a with nonradioactive d-(+)-methylphenidate or (-)-2-β-carbomethoxy-3-β-(4-fluorophenyl)tropane (β-CFT, WIN-35,428, a cocaine analog) blocked DAT labeling. Compound (±)-3a represents the first successful example of a DAT photoaffinity ligand based on the methylphenidate scaffold. Such ligands are expected to assist in mapping non-tropane ligand-binding pockets within plasma membrane monoamine transporters.

  18. Azido-Iodo-N-Benzyl Derivatives of threo-Methylphenidate (Ritalin, Concerta): Rational Design, Synthesis, Pharmacological Evaluation, and Dopamine Transporter Photoaffinity Labeling

    PubMed Central

    Lapinsky, David J.; Velagaleti, Ranganadh; Yarravarapu, Nageswari; Liu, Yi; Huang, Yurong; Surratt, Christopher K.; Lever, John R.; Foster, James D.; Acharya, Rejwi; Vaughan, Roxanne A.; Deutsch, Howard M.

    2010-01-01

    In contrast to tropane-based compounds such as benztropine and cocaine, non-tropane-based photoaffinity ligands for the dopamine transporter (DAT) are relatively unexplored. Towards addressing this knowledge gap, ligands were synthesized in which the piperidine nitrogen of 3- and 4-iodomethylphenidate was substituted with a benzyl group bearing a photoreactive azide. Analog (±)-3a demonstrated modest DAT affinity and a radioiodinated version was shown to bind covalently to rat striatal DAT and hDAT expressed in cultured cells. Co-incubation of (±)-3a with nonradioactive D-(+)-methylphenidate or (−)-2-β-carbomethoxy-3-β-(4-fluorophenyl)tropane (β-CFT, WIN-35,428, a cocaine analog) blocked DAT labeling. Compound (±)-3a represents the first successful example of a DAT photoaffinity ligand based on the methylphenidate scaffold. Such ligands are expected to assist in mapping non-tropane ligand-binding pockets within plasma membrane monoamine transporters. PMID:21129986

  19. Recovery of dopamine transporters with methamphetamine detoxification is not linked to changes in dopamine release

    SciTech Connect

    Volkow, Nora D.; Wang, Gene-Jack; Smith, Lisa; Fowler, Joanna S.; Telang, Frank; Logan, Jean; Tomasi, Dardo

    2015-07-21

    Metamphetamine’s widepread abuse and concerns that it may increase Parkinson’s disease led us to assess if the reported loss of dopamine transporters (DAT) in methamphetamine abusers (MA) reflected damage to dopamine neurons. Using PET with [11C]cocaine to measure DAT, and with [11C]raclopride to measure dopamine release (assessed as changes in specific binding of [11C]raclopride between placebo and methylphenidate), which was used as marker of dopamine neuronal function, we show that MA (n=16), tested during early detoxification, had lower DAT (20-30%) but overall normal DA release in striatum (except for a small decrease in left putamen), when compared to controls (n=15). In controls, DAT were positively correlated with DA release (higher DAT associated with larger DA increases), consistent with DAT serving as markers of DA terminals. In contrast, MA showed a trend for a negative correlation (p=0.07) (higher DAT associated with lower DA increases), consistent with reduced DA re-uptake following DAT downregulation. MA who remained abstinent nine-months later (n=9) showed significant increases in DAT (20%) but methylphenidate-induced dopamine increases did not change. In contrast, in controls, DAT did not change when retested 9 months later but methylphenidate-induced dopamine increases in ventral striatum were reduced (p=0.05). Baseline D2/D3 receptors in caudate were lower in MA than in controls and did not change with detoxification, nor did they change in the controls upon retest. The loss of DAT in the MA, which was not associated with a concomitant reduction in dopamine release as would have been expected if DAT loss reflected DA terminal degneration; as well as the recovery of DAT after protracted detoxification, which was not associated with increased dopamine release as would have been expected if DAT increases reflected terminal regeneration, indicate that the loss of DAT in these MA does not reflect degeneration of

  20. Recovery of dopamine transporters with methamphetamine detoxification is not linked to changes in dopamine release

    DOE PAGES

    Volkow, Nora D.; Wang, Gene-Jack; Smith, Lisa; ...

    2015-07-21

    Metamphetamine’s widepread abuse and concerns that it may increase Parkinson’s disease led us to assess if the reported loss of dopamine transporters (DAT) in methamphetamine abusers (MA) reflected damage to dopamine neurons. Using PET with [11C]cocaine to measure DAT, and with [11C]raclopride to measure dopamine release (assessed as changes in specific binding of [11C]raclopride between placebo and methylphenidate), which was used as marker of dopamine neuronal function, we show that MA (n=16), tested during early detoxification, had lower DAT (20-30%) but overall normal DA release in striatum (except for a small decrease in left putamen), when compared to controls (n=15).more » In controls, DAT were positively correlated with DA release (higher DAT associated with larger DA increases), consistent with DAT serving as markers of DA terminals. In contrast, MA showed a trend for a negative correlation (p=0.07) (higher DAT associated with lower DA increases), consistent with reduced DA re-uptake following DAT downregulation. MA who remained abstinent nine-months later (n=9) showed significant increases in DAT (20%) but methylphenidate-induced dopamine increases did not change. In contrast, in controls, DAT did not change when retested 9 months later but methylphenidate-induced dopamine increases in ventral striatum were reduced (p=0.05). Baseline D2/D3 receptors in caudate were lower in MA than in controls and did not change with detoxification, nor did they change in the controls upon retest. The loss of DAT in the MA, which was not associated with a concomitant reduction in dopamine release as would have been expected if DAT loss reflected DA terminal degneration; as well as the recovery of DAT after protracted detoxification, which was not associated with increased dopamine release as would have been expected if DAT increases reflected terminal regeneration, indicate that the loss of DAT in these MA does not reflect degeneration of dopamine terminals.« less

  1. Linoleic Acid-Induced Growth Inhibition of Human Gastric Epithelial Adenocarcinoma AGS Cells is Associated with Down-Regulation of Prostaglandin E2 Synthesis and Telomerase Activity

    PubMed Central

    Choi, Yung Hyun

    2014-01-01

    Background: Linoleic acid is the most abundant polyunsaturated fatty acid in human nutrition and found in most vegetable oils and certain food products. In the present study, we investigated the effects of linoleic acid on the growth of human epithelial adenocarcinoma AGS cells. Methods: MTT assay, flow cytometry, RT-PCR and Western-blot analyses were used to investigate the effects and underlying mechanisms of linoleic acid on AGS cells. The effects of this compound were also tested on prostaglandin E2 (PGE2) production and telomerase activity. Results: Our data indicated that growth inhibition of AGS cells by linoleic acid treatment was associated with induction of apoptosis. Linoleic acid treatment decreased the expression levels of the cyclooxygenase (COX)-2 mRNA and protein without causing significant changes in the COX-1 levels, which was correlated with the inhibition of PGE2 synthesis. Linoleic acid treatment also decreased the expression of human telomerase reverse transcriptase (hTERT), a main determinant of the telomerase enzymatic activity, and activity of telomerase, with inhibiting the expression of c-myc in a concentration-dependent manner. Conclusions: Taken together, our results indicate that linoleic acid inhibits the production of PGE2 and activity of telomerase by suppressing COX-2 and hTERT expression. PMID:25337570

  2. Resistin disrupts glycogen synthesis under high insulin and high glucose levels by down-regulating the hepatic levels of GSK3β

    PubMed Central

    Song, Rongjing; Wang, Xi; Mao, Yiqing; Li, Hui; Li, Zhixin; Xu, Wei; Wang, Rong; Guo, Tingting; Jin, Ling; Zhang, Xiaojing; Zhang, Yizhuang; Zhou, Na; Hu, Ruobi; Jia, Jianwei; Lei, Zhen; Irwin, David M.; Niu, Gang; Tan, Huanran

    2014-01-01

    The effect of mouse resistin on hepatic insulin resistance in vivo and in vitro, and its possible molecular mechanism were examined. Focusing on liver glycogen metabolism and gluconeogenesis, which are important parts of glucose metabolism, in primary cultures of rat hepatocytes we found that glycogen content was significantly lower (P<0.05) after treatment with recombinant murine resistin only in the presence of insulin plus glucose stimulation. Protein levels of factors in the insulin signaling pathway involved in glycogen synthesis were examined by Western blot analysis, with the only significant change observed being the level of phosphorylated (at Ser 9) glycogen synthase kinase-3β (GSK-3β) (P<0.001). No differences in the protein levels for the insulin receptor β (IRβ), insulin receptor substrates (IRS1 and IRS2), phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt) or their phosphorylated forms were observed between control and resistin treated primary rat hepatocytes. In a mouse model with high liver-specific expression of resistin, fasting blood glucose levels and liver glycogen content changed. Fasting blood glucose levels were significantly higher (P<0.001) in the model mice, compared to the control mice, while the glycogen content of the liver tissue was about 60% of that of the control mice (P<0.05). The gluconeogenic response was not altered between the experimental and control mice. The level of phosphorylated GSK-3β in the liver tissue was also decreased (P<0.05) in the model mice, consistent with the results from the primary rat hepatocytes. Our results suggests that resistin reduces the levels of GSK-3β phosphorylated at Ser 9 leading to impaired hepatic insulin action in primary rat hepatocytes and in a mouse model with high liver-specific expression of resistin. PMID:23860320

  3. Dopamine triggers Heterosynaptic Plasticity

    PubMed Central

    Ishikawa, Masago; Otaka, Mami; Huang, Yanhua; Neumann, Peter A.; Winters, Bradley D.; Grace, Anthony A.; Schlüter, Oliver M.; Dong, Yan

    2013-01-01

    As a classic neuromodulator, dopamine has long been thought to modulate, rather than trigger, synaptic plasticity. In contrast, our present results demonstrate that within the parallel projections of dopaminergic and GABAergic terminals from the ventral tegmental area (VTA) to nucleus accumbens core (NAcCo), action potential-activated release of dopamine heterosynaptically triggers LTD at GABAergic synapses, which is likely mediated by activating presynaptically-located dopamine D1 class receptors and expressed by inhibiting presynaptic release of GABA. Moreover, this dopamine-mediated heterosynaptic LTD is abolished after withdrawal from cocaine exposure. These results suggest that action potential-dependent dopamine release triggers very different cellular consequences from those induced by volume release or pharmacological manipulation. Activation of the VTA-to-NAcCo projections is essential for emotional and motivational responses. This dopamine-mediated LTD allows a flexible output of NAcCo neurons, whereas disruption of this LTD may contribute to the rigid emotional and motivational state observed in addicts during cocaine withdrawal. PMID:23595734

  4. Asymmetric total synthesis and identification of tetrahydroprotoberberine derivatives as new antipsychotic agents possessing a dopamine D(1), D(2) and serotonin 5-HT(1A) multi-action profile.

    PubMed

    Sun, Haifeng; Zhu, Liyuan; Yang, Huicui; Qian, Wangke; Guo, Lin; Zhou, Shengbin; Gao, Bo; Li, Zeng; Zhou, Yu; Jiang, Hualiang; Chen, Kaixian; Zhen, Xuechu; Liu, Hong

    2013-02-15

    An effective and rapid method for the microwave-assisted preparation of the key intermediate for the total synthesis of tetrahydroprotoberberines (THPBs) including l-stepholidine (l-SPD) was developed. Thirty-one THPB derivatives with diverse substituents on A and D ring were synthesized, and their binding affinity to dopamine D(1), D(2) and serotonin 5-HT(1A) and 5-HT(2A) receptors were determined. Compounds 18k and 18m were identified as partial agonists at the D(1) receptor with K(i) values of 50 and 6.3nM, while both compounds act as D(2) receptor antagonists (K(i)=305 and 145nM, respectively) and 5-HT(1A) receptor full agonists (K(i)=149 and 908nM, respectively). These two THPBs compounds exerted antipsychotic actions in animal models. Further electrophysiological studies employing single-unit recording in intact animals demonstrated that 18k-excited dopaminergic (DA) neurons are associated with its 5-HT(1A) receptor agonistic activity. These results suggest that these two compounds targeted to multiple neurotransmitter receptors may present novel lead drugs with new pharmacological profiles for the treatment of schizophrenia. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Dopamine D1 and D2 Receptor Immunoreactivities in the Arcuate-Median Eminence Complex and their Link to the Tubero-Infundibular Dopamine Neurons

    PubMed Central

    Romero-Fernandez, W.; Borroto-Escuela, D.O.; Vargas-Barroso, V.; Narváez, M.; Di Palma, M.; Agnati, L.F.; Sahd, J. Larriva

    2014-01-01

    modulate the activity and/or Dopamine synthesis of substantial numbers of tubero-infundibular dopamine neurons at the somatic and terminal level. The immunohistochemical work also gives support to the view that dopamine D1 receptors and/or dopamine D2 receptors in the lateral palisade zone by mediating dopamine volume transmission may contribute to the inhibition of luteinizing hormone releasing hormone release from nerve terminals in this region. PMID:25308843

  6. Design, synthesis, and characterization of a novel, 4-[2-(diphenylmethoxy)ethyl]-1-benzyl piperidine-based, dopamine transporter photoaffinity label.

    PubMed

    Dutta, A K; Fei, X S; Vaughan, R A; Gaffaney, J D; Wang, N; Lever, J R; Reith, M E

    2001-03-09

    The dopamine transporter (DAT) has been implicated strongly in cocaine's reinforcing effects. Many derivatives of piperidine analogs of GBR 12909 have been developed and were found to be quite potent and selective for the DAT. In this regard, most of these derivatives were found to be much more selective for the DAT than conventional GBR compounds e.g. GBR 12909 when their selectivity was compared with the serotonin transporter (SERT). A brief structure-activity relationship (SAR) study has been carried out in the development of a novel photoaffinity ligand which illustrated the effect of the presence of a sterically bulky iodine atom next to the azido group in activity and selectivity for the DAT. This SAR study also led to the development of the compound 4 which is one of the most potent and selective blockers for the DAT known today. The photoaffinity ligand [125I]AD-96-129 was incorporated into the DAT molecule as was demonstrated by immunoprecipitation with serum 16 which is specific for DAT. This photolabeling was antagonized by DAT-specific blockers and was unaffected by specific SERT and norepinephrine transporter (NET) blockers indicating interaction of this novel ligand with the DAT.

  7. Microwave-assisted synthesis of a core-shell MWCNT/GONR heterostructure for the electrochemical detection of ascorbic acid, dopamine, and uric acid.

    PubMed

    Sun, Chia-Liang; Chang, Ching-Tang; Lee, Hsin-Hsien; Zhou, Jigang; Wang, Jian; Sham, Tsun-Kong; Pong, Way-Faung

    2011-10-25

    In this study, graphene oxide nanoribbons (GONRs) were synthesized from the facile unzipping of multiwalled carbon nanotubes (MWCNTs) with the help of microwave energy. A core-shell MWCNT/GONR-modified glassy carbon (MWCNT/GONR/GC) electrode was used to electrochemically detect ascorbic acid (AA), dopamine (DA), and uric acid (UA). In cyclic voltammograms, the MWCNT/GONR/GC electrode was found to outperform the MWCNT- and graphene-modified GC electrodes in terms of peak current. For the simultaneous sensing of three analytes, well-separated voltammetric peaks were obtained using a MWCNT/GONR/GC electrode in differential pulse voltammetry measurements. The corresponding peak separations were 229.9 mV (AA to DA), 126.7 mV (DA to UA), and 356.6 mV (AA to UA). This excellent electrochemical performance can be attributed to the unique electronic structure of MWCNTs/GONRs: a high density of unoccupied electronic states above the Fermi level and enriched oxygen-based functionality at the edge of the graphene-like structures, as revealed by X-ray absorption near-edge structure spectroscopy, obtained using scanning transmission X-ray microscopy.

  8. Electrochemical Co-Reduction Synthesis of AuPt Bimetallic Nanoparticles-Graphene Nanocomposites for Selective Detection of Dopamine in the Presence of Ascorbic Acid and Uric Acid

    PubMed Central

    Zhao, Zongya; Zhang, Mingming; Chen, Xiang; Li, Youjun; Wang, Jue

    2015-01-01

    In this paper, AuPt bimetallic nanoparticles-graphene nanocomposites were obtained by electrochemical co-reduction of graphene oxide (GO), HAuCl4 and H2PtCl6. The as-prepared AuPt bimetallic nanoparticles-graphene nanocomposites were characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and other electrochemical methods. The morphology and composition of the nanocomposite could be easily controlled by adjusting the HAuCl4/H2PtCl6 concentration ratio. The electrochemical experiments showed that when the concentration ratio of HAuCl4/H2PtCl6 was 1:1, the obtained AuPt bimetallic nanoparticles-graphene nanocomposite (denoted as Au1Pt1NPs-GR) possessed the highest electrocatalytic activity toward dopamine (DA). As such, Au1Pt1NPs-GR nanocomposites were used to detect DA in the presence of ascorbic acid (AA) and uric acid (UA) using the differential pulse voltammetry (DPV) technique and on the modified electrode, there were three separate DPV oxidation peaks with the peak potential separations of 177 mV, 130 mV and 307 mV for DA and AA, DA and UA, AA and UA, respectively. The linear range of the constructed DA sensor was from 1.6 μM to 39.7 μM with a detection limit of 0.1 μM (S/N = 3). The obtained DA sensor with good stability, high reproducibility and excellent selectivity made it possible to detect DA in human urine samples. PMID:26184200

  9. In situ electrochemical synthesis of highly loaded zirconium nanoparticles decorated reduced graphene oxide for the selective determination of dopamine and paracetamol in presence of ascorbic acid.

    PubMed

    Ezhil Vilian, A T; Rajkumar, Muniyandi; Chen, Shen-Ming

    2014-03-01

    Highly loaded zirconium oxide (ZrO2) nanoparticles were supported on graphene oxide (ERGO/ZrO2) via an in situ, simple and clean strategy on the basis of the electrochemical redox reaction between zirconyl chloride and graphene oxide (ZrOCl2 and GO). The electrochemical measurements and surface morphology of the as prepared nanocomposite were studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and field emission scanning electron microscopy (FESEM). This ZrO2 decorated reduced graphene oxide nanocomposite modified GCE (ERGO/ZrO2) exhibits a prominent electrocatalytic activity toward the selective detection and determination of dopamine (DA) and paracetamol (PA) in presence of ascorbic acid (AA). The peaks of linear sweep voltammetry (LSV) for DA and PA oxidation at ERGO/ZrO2 modified electrode surface were clearly separated from each other when they co-existed in the physiological pH (pH 7.0) with a potential value of 140 mV (between AA and DA) and 330 mV (between AA and PA). It was, therefore, possible to simultaneously determine DA and PA in the samples at ERGO/ZrO2 nanocomposite modified GCE. Linear calibration curves were obtained for 9-237 μM of PA and DA. The ERGO/ZrO2 nanocomposite electrode has been satisfactorily used for the determination of DA and PA in the presence of AA at pharmaceutical formulations in human urine samples with a linear range of 3-174 μM. The proposed biosensor shows a wide linear range, low detection limit, good reproducibility and acceptable stability, providing a biocompatible platform for bio sensing and bio catalysis.

  10. Click Synthesis of Hydrophilic Maltose-Functionalized Iron Oxide Magnetic Nanoparticles Based on Dopamine Anchors for Highly Selective Enrichment of Glycopeptides.

    PubMed

    Bi, Changfen; Zhao, Yingran; Shen, Lijin; Zhang, Kai; He, Xiwen; Chen, Langxing; Zhang, Yukui

    2015-11-11

    The development of methods to isolate and enrich low-abundance glycopeptides from biological samples is crucial to glycoproteomics. Herein, we present an easy and one-step surface modification strategy to prepare hydrophilic maltose functionalized Fe3O4 nanoparticles (NPs). First, based on the chelation of the catechol ligand with iron atoms, azido-terminated dopamine (DA) derivative was assembled on the surface of magnetic Fe3O4 nanoparticles by sonication. Second, the hydrophilic maltose-functionalized Fe3O4 (Fe3O4-DA-Maltose) NPs were obtained via copper(I)-catalyzed azide-alkyne cycloaddition (click chemistry). The morphology, structure, and composition of Fe3O4-DA-Maltose NPs were investigated by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), X-ray photoelectron spectrometer (XPS), and vibrating sample magnetometer (VSM). Meanwhile, hydrophilicity of the obtained NPs was evaluated by water contact angle measurement. The hydrophilic Fe3O4-DA-Maltose NPs were applied in isolation and enrichment of glycopeptides from horseradish peroxidase (HRP), immunoglobulin (IgG) digests. The MALDI-TOF mass spectrometric analysis indicated that the novel NPs exhibited high detection sensitivity in enrichment from HRP digests at concentration as low as 0.05 ng μL(-1), a large binding capacity up to 43 mg g(-1), and good recovery for glycopeptides enrichment (85-110%). Moreover, the Fe3O4-DA-Maltose NPs were applied to enrich glycopeptides from human renal mesangial cells (HRMC) for identification of N-glycosylation sites. Finally, we identified 115 different N-linked glycopeptides, representing 93 gene products and 124 glycosylation sites in HRMC.

  11. Electrochemical Co-Reduction Synthesis of AuPt Bimetallic Nanoparticles-Graphene Nanocomposites for Selective Detection of Dopamine in the Presence of Ascorbic Acid and Uric Acid.

    PubMed

    Zhao, Zongya; Zhang, Mingming; Chen, Xiang; Li, Youjun; Wang, Jue

    2015-07-09

    In this paper, AuPt bimetallic nanoparticles-graphene nanocomposites were obtained by electrochemical co-reduction of graphene oxide (GO), HAuCl4 and H2PtCl6. The as-prepared AuPt bimetallic nanoparticles-graphene nanocomposites were characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and other electrochemical methods. The morphology and composition of the nanocomposite could be easily controlled by adjusting the HAuCl4/H2PtCl6 concentration ratio. The electrochemical experiments showed that when the concentration ratio of HAuCl4/H2PtCl6 was 1:1, the obtained AuPt bimetallic nanoparticles-graphene nanocomposite (denoted as Au1Pt1NPs-GR) possessed the highest electrocatalytic activity toward dopamine (DA). As such, Au1Pt1NPs-GR nanocomposites were used to detect DA in the presence of ascorbic acid (AA) and uric acid (UA) using the differential pulse voltammetry (DPV) technique and on the modified electrode, there were three separate DPV oxidation peaks with the peak potential separations of 177 mV, 130 mV and 307 mV for DA and AA, DA and UA, AA and UA, respectively. The linear range of the constructed DA sensor was from 1.6 μM to 39.7 μM with a detection limit of 0.1 μM (S/N = 3). The obtained DA sensor with good stability, high reproducibility and excellent selectivity made it possible to detect DA in human urine samples.

  12. Attenuation of PAMP-triggered immunity in maize requires down-regulation of the key β-1,6-glucan synthesis genes KRE5 and KRE6 in biotrophic hyphae of Colletotrichum graminicola.

    PubMed

    Oliveira-Garcia, Ely; Deising, Holger B

    2016-08-01

    In plants, pathogen defense is initiated by recognition of pathogen-associated molecular patterns (PAMPs) via plasma membrane-localized pattern-recognition receptors (PRRs). Fungal structural cell wall polymers such as branched β-glucans are essential for infection structure rigidity and pathogenicity, but at the same time represent PAMPs. Kre5 and Kre6 are key enzymes in β-1,6-glucan synthesis and formation of branch points of the β-glucan network. In spite of the importance of branched β-glucan for hyphal rigidity and plant-fungus interactions, neither the role of KRE5 and KRE6 in pathogenesis nor mechanisms allowing circumventing branched β-glucan-triggered immune responses are known. We functionally characterized KRE5 and KRE6 of the ascomycete Colletotrichum graminicola, a hemibiotroph that infects maize (Zea mays). After appressorial plant invasion, this fungus sequentially differentiates biotrophic and highly destructive necrotrophic hyphae. RNAi-mediated reduction of KRE5 and KRE6 transcript abundance caused appressoria to burst and swelling of necrotrophic hyphae, indicating that β-1,6-glucosidic bonds are essential in these cells. Live cell imaging employing KRE5:mCherry and KRE6:mCherry knock-in strains and probing of infection structures with a YFP-conjugated β-1,6-glucan-binding protein showed expression of these genes and exposure of β-1,6-glucan in conidia, appressoria and necrotrophic, but not in biotrophic hyphae. Overexpression of KRE5 and KRE6 in biotrophic hyphae led to activation of broad-spectrum plant defense responses, including papilla and H2 O2 formation, as well as transcriptional activation of several defense-related genes. Collectively, our results strongly suggest that down-regulation of synthesis and avoidance of exposure of branched β-1,3-β-1,6-glucan in biotrophic hyphae is required for attenuation of plant immune responses. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

  13. Putative presynaptic dopamine dysregulation in schizophrenia is supported by molecular evidence from post-mortem human midbrain

    PubMed Central

    Purves-Tyson, T D; Owens, S J; Rothmond, D A; Halliday, G M; Double, K L; Stevens, J; McCrossin, T; Shannon Weickert, C

    2017-01-01

    The dopamine hypothesis of schizophrenia posits that increased subcortical dopamine underpins psychosis. In vivo imaging studies indicate an increased presynaptic dopamine synthesis capacity in striatal terminals and cell bodies in the midbrain in schizophrenia; however, measures of the dopamine-synthesising enzyme, tyrosine hydroxylase (TH), have not identified consistent changes. We hypothesise that dopamine dysregulation in schizophrenia could result from changes in expression of dopamine synthesis enzymes, receptors, transporters or catabolic enzymes. Gene expression of 12 dopamine-related molecules was examined in post-mortem midbrain (28 antipsychotic-treated schizophrenia cases/29 controls) using quantitative PCR. TH and the synaptic dopamine transporter (DAT) proteins were examined in post-mortem midbrain (26 antipsychotic-treated schizophrenia cases per 27 controls) using immunoblotting. TH and aromatic acid decarboxylase (AADC) mRNA and TH protein were unchanged in the midbrain in schizophrenia compared with controls. Dopamine receptor D2 short, vesicular monoamine transporter (VMAT2) and DAT mRNAs were significantly decreased in schizophrenia, with no change in DRD3 mRNA, DRD3nf mRNA and DAT protein between diagnostic groups. However, DAT protein was significantly increased in putatively treatment-resistant cases of schizophrenia compared to putatively treatment-responsive cases. Midbrain monoamine oxidase A (MAOA) mRNA was increased, whereas MAOB and catechol-O-methyl transferase mRNAs were unchanged in schizophrenia. We conclude that, whereas some mRNA changes are consistent with increased dopamine action (decreased DAT mRNA), others suggest reduced dopamine action (increased MAOA mRNA) in the midbrain in schizophrenia. Here, we identify a molecular signature of dopamine dysregulation in the midbrain in schizophrenia that mainly includes gene expression changes of molecules involved in dopamine synthesis and in regulating the time course of dopamine

  14. Putative presynaptic dopamine dysregulation in schizophrenia is supported by molecular evidence from post-mortem human midbrain.

    PubMed

    Purves-Tyson, T D; Owens, S J; Rothmond, D A; Halliday, G M; Double, K L; Stevens, J; McCrossin, T; Shannon Weickert, C

    2017-01-17

    The dopamine hypothesis of schizophrenia posits that increased subcortical dopamine underpins psychosis. In vivo imaging studies indicate an increased presynaptic dopamine synthesis capacity in striatal terminals and cell bodies in the midbrain in schizophrenia; however, measures of the dopamine-synthesising enzyme, tyrosine hydroxylase (TH), have not identified consistent changes. We hypothesise that dopamine dysregulation in schizophrenia could result from changes in expression of dopamine synthesis enzymes, receptors, transporters or catabolic enzymes. Gene expression of 12 dopamine-related molecules was examined in post-mortem midbrain (28 antipsychotic-treated schizophrenia cases/29 controls) using quantitative PCR. TH and the synaptic dopamine transporter (DAT) proteins were examined in post-mortem midbrain (26 antipsychotic-treated schizophrenia cases per 27 controls) using immunoblotting. TH and aromatic acid decarboxylase (AADC) mRNA and TH protein were unchanged in the midbrain in schizophrenia compared with controls. Dopamine receptor D2 short, vesicular monoamine transporter (VMAT2) and DAT mRNAs were significantly decreased in schizophrenia, with no change in DRD3 mRNA, DRD3nf mRNA and DAT protein between diagnostic groups. However, DAT protein was significantly increased in putatively treatment-resistant cases of schizophrenia compared to putatively treatment-responsive cases. Midbrain monoamine oxidase A (MAOA) mRNA was increased, whereas MAOB and catechol-O-methyl transferase mRNAs were unchanged in schizophrenia. We conclude that, whereas some mRNA changes are consistent with increased dopamine action (decreased DAT mRNA), others suggest reduced dopamine action (increased MAOA mRNA) in the midbrain in schizophrenia. Here, we identify a molecular signature of dopamine dysregulation in the midbrain in schizophrenia that mainly includes gene expression changes of molecules involved in dopamine synthesis and in regulating the time course of dopamine

  15. Reciprocal Phosphorylation and Palmitoylation Control Dopamine Transporter Kinetics*

    PubMed Central

    Moritz, Amy E.; Rastedt, Danielle E.; Stanislowski, Daniel J.; Shetty, Madhur; Smith, Margaret A.; Vaughan, Roxanne A.; Foster, James D.

    2015-01-01

    The dopamine transporter is a neuronal protein that drives the presynaptic reuptake of dopamine (DA) and is the major determinant of transmitter availability in the brain. Dopamine transporter function is regulated by protein kinase C (PKC) and other signaling pathways through mechanisms that are complex and poorly understood. Here we investigate the role of Ser-7 phosphorylation and Cys-580 palmitoylation in mediating steady-state transport kinetics and PKC-stimulated transport down-regulation. Using both mutational and pharmacological approaches, we demonstrate that these post-translational modifications are reciprocally regulated, leading to transporter populations that display high phosphorylation-low palmitoylation or low phosphorylation-high palmitoylation. The balance between the modifications dictates transport capacity, as conditions that promote high phosphorylation or low palmitoylation reduce transport Vmax and enhance PKC-stimulated down-regulation, whereas conditions that promote low phosphorylation or high palmitoylation increase transport Vmax and suppress PKC-stimulated down-regulation. Transitions between these functional states occur when endocytosis is blocked or undetectable, indicating that the modifications kinetically regulate the velocity of surface transporters. These findings reveal a novel mechanism for control of DA reuptake that may represent a point of dysregulation in DA imbalance disorders. PMID:26424792

  16. Testosterone Induces Molecular Changes in Dopamine Signaling Pathway Molecules in the Adolescent Male Rat Nigrostriatal Pathway

    PubMed Central

    Purves-Tyson, Tertia D.; Owens, Samantha J.; Double, Kay L.; Desai, Reena; Handelsman, David J.; Weickert, Cynthia Shannon

    2014-01-01

    Adolescent males have an increased risk of developing schizophrenia, implicating testosterone in the precipitation of dopamine-related psychopathology. Evidence from adult rodent brain indicates that testosterone can modulate nigrostriatal dopamine. However, studies are required to understand the role testosterone plays in maturation of dopamine pathways during adolescence and to elucidate the molecular mechanism(s) by which testosterone exerts its effects. We hypothesized that molecular indices of dopamine neurotransmission [synthesis (tyrosine hydroxylase), breakdown (catechol-O-methyl transferase; monoamine oxygenase), transport [vesicular monoamine transporter (VMAT), dopamine transporter (DAT)] and receptors (DRD1-D5)] would be changed by testosterone or its metabolites, dihydrotestosterone and 17β-estradiol, in the nigrostriatal pathway of adolescent male rats. We found that testosterone and dihydrotestosterone increased DAT and VMAT mRNAs in the substantia nigra and that testosterone increased DAT protein at the region of the cell bodies, but not in target regions in the striatum. Dopamine receptor D2 mRNA was increased and D3 mRNA was decreased in substantia nigra and/or striatum by androgens. These data suggest that increased testosterone at adolescence may change dopamine responsivity of the nigrostriatal pathway by modulating, at a molecular level, the capacity of neurons to transport and respond to dopamine. Further, dopamine turnover was increased in the dorsal striatum following gonadectomy and this was prevented by testosterone replacement. Gene expression changes in the dopaminergic cell body region may serve to modulate both dendritic dopamine feedback inhibition and reuptake in the dopaminergic somatodendritic field as well as dopamine release and re-uptake dynamics at the presynaptic terminals in the striatum. These testosterone-induced changes of molecular indices of dopamine neurotransmission in males are primarily androgen receptor

  17. A dopamine-secreting pheochromocytoma.

    PubMed

    Yasunari, K; Kohno, M; Minami, M; Kano, H; Ohhira, M; Nakamura, K; Yoshikawa, J

    2000-01-01

    We describe a patient with pheochromocytoma, which secretes dopamine. He was admitted to hospital because of chronic diarrhea. After surgical resection of the tumor, dramatic cessation of the diarrhea and blood pressure elevation were observed. Decreased expression of dopamine beta-hydroxylase in the tumor was considered a possible mechanism of producing a pathophysiological concentration of dopamine. This case shows that excessive excretion of dopamine, a vasodilative hormone, may affect blood pressure.

  18. Possible involvement of dopamine and dopamine2 receptors in the inhibitions of gastric emptying by escin Ib in mice.

    PubMed

    Matsuda, H; Li, Y; Yoshikawa, M

    2000-11-03

    It was previously reported that escin Ib isolated from horse chestnut inhibited gastric emptying (GE) in mice, in which the capsaicin-sensitive sensory nerves (CPSN), the central nervous system and endogenous prostaglandins (PGs) were involved. In the present study, the possible involvement of dopamine and dopamine receptors in the inhibition of GE by escin Ib were investigated in mice. GE inhibition by escin Ib (25 mg/kg, p.o.) was attenuated after pretreatment with a single bolus of DL-alpha-methyl-p-tyrosine methyl ester (400 mg/kg, s.c., an inhibitor of tyrosine hydroxylase), reserpine (5 mg/kg, p.o., a catecholamine depletor), 6-hydroxydopamine (80 mg/kg, i.p., a dopamine depletor). Furthermore, pretreatment with spiperone (0.5-5 mg/kg, s.c., a dopamine2 receptor antagonist), haloperidol (0.5-10 mg/kg, s.c.) and metoclopramide (1-10 mg/kg, s.c.) (centrally acting dopamine2 receptor antagonists) attenuated the effect of escin Ib. Domperidone (0.1-5 mg/kg, s.c., a peripheral-acting dopamine2 antagonist) showed a weak attenuation, but SCH 23390 (1-5 mg/kg, s.c., a dopamine, receptor antagonist) did not. It is postulated that escin Ib inhibits GE, at least in part, mediated by CPSN, to stimulate the synthesis and/or release of dopamine, to act through central dopamine2 receptor, which in turn causes the release of PGs.

  19. An electrochemical sensor prepared by sonochemical one-pot synthesis of multi-walled carbon nanotube-supported cobalt nanoparticles for the simultaneous determination of paracetamol and dopamine.

    PubMed

    Kutluay, Aysegul; Aslanoglu, Mehmet

    2014-08-11

    Multi-walled carbon nanotubes (MWCNTs) functionalized by cobalt nanoparticles were obtained using a single step chemical deposition method in an ultrasonic bath. The composite material was characterized using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The electroactivity of the cobalt-functionalized MWCNTs was assessed in respect to the electrooxidation of paracetamol (PAR) and dopamine (DA). It was found that the carbon nanotube supported cobalt nanoparticles have significantly higher catalytic properties. The proposed electrode has been applied for the simultaneous determination of PAR and DA. The modified electrode could resolve the overlapped voltammetric waves of PAR and DA into two well-defined voltammetric peaks with peak to peak separation of about 203 mV. On the other hand, the presence of potential drug interfering compounds AA and UA did not affect the voltammetric responses of PAR and DA. The current of oxidation peaks showed a linear dependent on the concentrations of PAR and DA in the range of 5.2×10(-9)-4.5×10(-7) M (R(2)=0.9987) and 5.0×10(-8)-3.0×10(-6) M (R(2)=0.9999), respectively. The detection limits of 1.0×10(-9) M and 1.5×10(-8) M were obtained for PAR and DA, respectively. The proposed electrode showed good stability (peak current change: 4.9% with and RSD of 2.6% for PAR; 5.5% with and RSD of 3.0% for DA over 3 weeks), reproducibility (RSD 2.3% for PAR and RSD 1.5% for DA), repeatability (RSD 2.25% for PAR and RSD 2.50% for DA) and high recovery (99.7% with an RSD of 1.3% for PAR; 100.8% with an RSD of 1.8% for DA). The proposed method was successfully applied to the determination of PAR and DA in pharmaceuticals.

  20. Novel neuroprotective mechanisms of pramipexole, an anti-Parkinson drug, against endogenous dopamine-mediated excitotoxicity.

    PubMed

    Izumi, Yasuhiko; Sawada, Hideyuki; Yamamoto, Noriyuki; Kume, Toshiaki; Katsuki, Hiroshi; Shimohama, Shun; Akaike, Akinori

    2007-02-28

    Parkinson disease is characterized by selective degeneration of mesencephalic dopaminergic neurons, and endogenous dopamine may play a pivotal role in the degenerative processes. Using primary cultured mesencephalic neurons, we found that glutamate, an excitotoxin, caused selective dopaminergic neuronal death depending on endogenous dopamine content. Pramipexole, a dopamine D2/D3 receptor agonist used clinically in the treatment of Parkinson disease, did not affect glutamate-induced calcium influx but blocked dopaminergic neuronal death induced by glutamate. Pramipexole reduced dopamine content but did not change the levels of total or phosphorylated tyrosine hydroxylase, a rate-limiting enzyme in dopamine synthesis. The neuroprotective effect of pramipexole was independent of dopamine receptor stimulation because it was not abrogated by domperidone, a dopamine D2-type receptor antagonist. Moreover, both active S(-)- and inactive R(+)-enantiomers of pramipexole as a dopamine D2-like receptor agonist equally suppressed dopaminergic neuronal death. These results suggest that pramipexole protects dopaminergic neurons from glutamate neurotoxicity by the reduction of intracellular dopamine content, independently of dopamine D2-like receptor activation.

  1. Dopamine alleviates nutrient deficiency-induced stress in Malus hupehensis.

    PubMed

    Liang, Bowen; Li, Cuiying; Ma, Changqing; Wei, Zhiwei; Wang, Qian; Huang, Dong; Chen, Qi; Li, Chao; Ma, Fengwang

    2017-10-01

    Dopamine mediates many physiological processes in plants. We investigated its role in regulating growth, root system architecture, nutrient uptake, and responses to nutrient deficiencies in Malus hupehensis Rehd. Under a nutrient deficiency, plants showed significant reductions in growth, chlorophyll concentrations, and net photosynthesis, along with disruptions in nutrient uptake, transport, and distribution. However, pretreatment with 100 μM dopamine markedly alleviated such inhibitions. Supplementation with that compound enabled plants to maintain their photosynthetic capacity and development of the root system while promoting the uptake of N, P, K, Ca, Mg, Fe, Mn, Cu, Zn, and B, altering the way in which those nutrients were partitioned throughout the plant. The addition of dopamine up-regulated genes for antioxidant enzymes involved in the ascorbate-glutathione cycle (MdcAPX, MdcGR, MdMDHAR, MdDHAR-1, and MdDHAR-2) but down-regulated genes for senescence (SAG12, PAO, and MdHXK). These results indicate that exogenous dopamine has an important antioxidant and anti-senescence effect that might be helpful for improving nutrient uptake. Our findings demonstrate that dopamine offers new opportunities for its use in agriculture, especially when addressing the problem of nutrient deficiencies. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  2. Characterization of dopamine releasable and reserve pools in Drosophila larvae using ATP/P2X2-mediated stimulation

    PubMed Central

    Xiao, Ning; Venton, B. Jill

    2015-01-01

    Dopaminergic signaling pathways are conserved between mammals and Drosophila, but the factors important for maintaining the functional pool of synaptic dopamine are not fully understood in Drosophila. In this study, we characterized the releasable and reserve dopamine pools in Drosophila larvae using ATP/ P2X2-mediated stimulation. Dopamine release was stable with stimulations performed at least every 5 min but decayed with stimulations performed 2 min apart or less, indicating the replenishment of the releasable pool occurred on a time scale between 2 and 5 min. Dopamine synthesis or uptake were pharmacologically inhibited with 3-iodotyrosine and cocaine, respectively, to evaluate their contributions to maintaining the releasable dopamine pool. We found that both synthesis and uptake were needed to maintain the releasable dopamine pool, with synthesis playing a major part in long-term replenishment and uptake being more important for short-term replenishment. These effects of synthesis and uptake on different time scales in Drosophila are analogous to mammals. However, unlike in mammals, cocaine did not activate a reserve pool of dopamine in Drosophila when using P2X2 stimulations. Our study shows that both synthesis and uptake replenish the releasable pool, providing a better understanding of dopamine regulation in Drosophila. PMID:25951875

  3. Selective expression of Parkinson's disease-related Leucine-rich repeat kinase 2 G2019S missense mutation in midbrain dopaminergic neurons impairs dopamine release and dopaminergic gene expression.

    PubMed

    Liu, Guoxiang; Sgobio, Carmelo; Gu, Xinglong; Sun, Lixin; Lin, Xian; Yu, Jia; Parisiadou, Loukia; Xie, Chengsong; Sastry, Namratha; Ding, Jinhui; Lohr, Kelly M; Miller, Gary W; Mateo, Yolanda; Lovinger, David M; Cai, Huaibin

    2015-09-15

    Preferential dysfunction/degeneration of midbrain substantia nigra pars compacta (SNpc) dopaminergic (DA) neurons contributes to the main movement symptoms manifested in Parkinson's disease (PD). Although the Leucine-rich repeat kinase 2 (LRRK2) G2019S missense mutation (LRRK2 G2019S) is the most common causative genetic factor linked to PD, the effects of LRRK2 G2019S on the function and survival of SNpc DA neurons are poorly understood. Using a binary gene expression system, we generated transgenic mice expressing either wild-type human LRRK2 (WT mice) or the LRRK2 G2019S mutation (G2019S mice) selectively in the midbrain DA neurons. Here we show that overexpression of LRRK2 G2019S did not induce overt motor abnormalities or substantial SNpc DA neuron loss. However, the LRRK2 G2019S mutation impaired dopamine homeostasis and release in aged mice. This reduction in dopamine content/release coincided with the degeneration of DA axon terminals and decreased expression of DA neuron-enriched genes tyrosine hydroxylase (TH), vesicular monoamine transporter 2, dopamine transporter and aldehyde dehydrogenase 1. These factors are responsible for dopamine synthesis, transport and degradation, and their expression is regulated by transcription factor paired-like homeodomain 3 (PITX3). Levels of Pitx3 mRNA and protein were similarly decreased in the SNpc DA neurons of aged G2019S mice. Together, these findings suggest that PITX3-dependent transcription regulation could be one of the many potential mechanisms by which LRRK2 G2019S acts in SNpc DA neurons, resulting in downregulation of its downstream target genes critical for dopamine homeostasis and release.

  4. Amphetamine Paradoxically Augments Exocytotic Dopamine Release and Phasic Dopamine Signals

    PubMed Central

    Daberkow, DP; Brown, HD; Bunner, KD; Kraniotis, SA; Doellman, MA; Ragozzino, ME; Garris, PA; Roitman, MF

    2013-01-01

    Drugs of abuse hijack brain reward circuitry during the addiction process by augmenting action potential-dependent phasic dopamine release events associated with learning and goal-directed behavior. One prominent exception to this notion would appear to be amphetamine (AMPH) and related analogs, which are proposed instead to disrupt normal patterns of dopamine neurotransmission by depleting vesicular stores and promoting non-exocytotic dopamine efflux via reverse transport. This mechanism of AMPH action, though, is inconsistent with its therapeutic effects and addictive properties - which are thought to be reliant on phasic dopamine signaling. Here we used fast-scan cyclic voltammetry in freely moving rats to interrogate principal neurochemical responses to AMPH in the striatum and relate these changes to behavior. First, we showed that AMPH dose-dependently enhanced evoked dopamine responses to phasic-like current pulse trains for up to two hours. Modeling the data revealed that AMPH inhibited dopamine uptake but also unexpectedly potentiated vesicular dopamine release. Second, we found that AMPH increased the amplitude, duration and frequency of spontaneous dopamine transients, the naturally occurring, non-electrically evoked, phasic increases in extracellular dopamine. Finally, using an operant sucrose reward paradigm, we showed that low-dose AMPH augmented dopamine transients elicited by sucrose-predictive cues. However, operant behavior failed at high-dose AMPH, which was due to phasic dopamine hyperactivity and the decoupling of dopamine transients from the reward predictive cue. These findings identify up-regulation of exocytotic dopamine release as a key AMPH action in behaving animals and support a unified mechanism of abused drugs to activate phasic dopamine signaling. PMID:23303926

  5. Dopamine and fronto-striatal networks in cognitive aging

    PubMed Central

    Klostermann, Ellen C.; Braskie, Meredith N.; Landau, Susan M.; O’Neil, James P.; Jagust, William J.

    2011-01-01

    Recent studies have linked dopamine to differences in behavior and brain activity in normal individuals. We explored these relationships in older and younger adults by investigating how functional connectivity between the striatum and prefrontal cortex is related to caudate dopamine and verbal working memory task performance. We studied 12 young and 18 older participants with functional magnetic resonance imaging (fMRI) during this task, and used positron emission tomography with the tracer 6-[18F]-fluoro-L-m-tyrosine (FMT) to assess dopamine synthesis capacity. Younger adults had a greater extent of frontal-caudate functional connectivity during the load-dependent delay period of the working memory task than the older participants. Across all subjects, the extent of this functional connectivity was negatively correlated with dopamine synthesis capacity, such that participants with the greatest connectivity had the lowest caudate FMT signal. Additionally, the extent of functional connectivity was positively correlated with working memory performance. Overall these data suggest interdependencies exist between fronto-striatal functional connectivity, dopamine, and working memory performance and that this system is functioning suboptimally in normal aging. PMID:21511369

  6. Levodopa therapy: consequences of the nonphysiologic replacement of dopamine.

    PubMed

    Chase, T N

    1998-05-01

    Normal motor function is dependent on the highly regulated synthesis and release of the transmitter dopamine by neurons projecting from the substantia nigra to the corpus striatum. Parkinson's disease involves the progressive degeneration of these neurons. Its core symptoms are a direct consequence of a striatal insufficiency of intrasynaptic dopamine. Levodopa, the standard of care for the treatment of PD, acts after its conversion to dopamine by restoring striatal dopaminergic transmission. However, there are significant differences between the normally functioning dopamine system and the restoration of function provided by standard levodopa treatment. Increasing clinical and preclinical evidence suggests that the intermittent stimulation of dopamine receptors resulting from current therapeutic regimens contributes to the response complications that ultimately affect most parkinsonian patients. It now appears that chronic nonphysiologic stimulation of dopaminergic receptors on striatal GABAergic neurons activates characteristic signaling pathways, leading to a potentiation of the synaptic efficacy of adjacent glutamatergic receptors of the N-methyl-D-aspartate (NMDA) subtype. As a result, function of these GABAergic efferent neurons changes in ways that favor the appearance of motor complications. Conceivably, use of dopaminomimetic replacement strategies that provide more continuous dopamine receptor stimulation will act to prevent or alleviate these disabling complications. A number of promising approaches to achieving this goal are now under development.

  7. Dopamine and anorexia nervosa.

    PubMed

    Södersten, P; Bergh, C; Leon, M; Zandian, M

    2016-01-01

    We have suggested that reduced food intake increases the risk for anorexia nervosa by engaging mesolimbic dopamine neurons, thereby initially rewarding dieting. Recent fMRI studies have confirmed that dopamine neurons are activated in anorexia nervosa, but it is not clear whether this response is due to the disorder or to its resulting nutritional deficit. When the body senses the shortage of nutrients, it rapidly shifts behavior toward foraging for food as a normal physiological response and the mesolimbic dopamine neurons may be involved in that process. On the other hand, the altered dopamine status of anorexics has been suggested to result from a brain abnormality that underlies their complex emotional disorder. We suggest that the outcomes of the treatments that emerge from that perspective remain poor because they target the mental symptoms that are actually the consequences of the food deprivation that accompanies anorexia. On the other hand, a method that normalizes the disordered eating behavior of anorexics results in much better physiological, behavioral, and emotional outcomes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Knocking out the dopamine reuptake transporter (DAT) does not change the baseline brain arachidonic acid signal in the mouse

    PubMed Central

    Ramadan, Epolia; Chang, Lisa; Chen, Mei; Ma, Kaizong; Hall, F. Scott; Uhl, George R.; Rapoport, Stanley I.; Basselin, Mireille

    2012-01-01

    Background Dopamine transporter (DAT) homozygous knockout (DAT−/−) mice have a 10-fold higher extracellular DA concentration in the caudate-putamen and nucleus accumbens than do wildtype (DAT+/+) mice, but show reduced presynaptic DA synthesis and fewer postsynaptic D2 receptors. One aspect of neurotransmission involves DA binding to postsynaptic D2-like receptors coupled to cytosolic phospholipase A2 (cPLA2), releasing second messenger arachidonic acid (AA) from synaptic membrane phospholipid. We hypothesized that tonic overactivation of D2-like receptors in DAT−/− mice due to elevated DA would not increase brain AA signaling, because of compensatory downregulation of postsynaptic signaling mechanisms. Methods [1-14C]AA was infused intravenously for 3 min in unanesthetized DAT+/+, heterozygous (DAT+/−) and DAT−/− mice. AA incorporation coefficients k* and rates Jin, markers of AA metabolism and signaling, were imaged in 83 brain regions using quantitative autoradiography brain cPLA2-IV activity also was measured. Results Neither k* nor Jin for AA in any brain region, or in brain cPLA2-IV activity, differed significantly between DAT−/−, DAT+/− and DAT+/+ mice. Conclusions These results differ from reported increases in k* and Jin for AA, and brain cPLA2 expression, in serotonin reuptake transporter (5-HTT) knockout mice, and suggest that postsynaptic dopaminergic neurotransmission mechanisms involving AA are downregulated despite elevated DA in DAT−/− mice. PMID:22376027

  9. Dopamine and binge eating behaviors

    PubMed Central

    Bello, Nicholas T.; Hajnal, Andras

    2010-01-01

    Central dopaminergic mechanisms are involved in the motivational aspects of eating and food choices. This review focuses on human and animal data examining the importance of dopamine on binge eating behaviors. Early works examining dopamine metabolites in the cerebrospinal fluid and plasma of bulimic individuals suggested decreased dopamine turnover during the active phase of the illness. While neuroimaging studies of dopamine mechanisms in bulimia nervosa (BN) and binge eating disorder (BED) are limited, genetic studies in humans have implicated an increased frequency of dopamine transporter and associated D2 receptor polymorphisms with binge pathology. Recent examinations of rodent models of dietary-induced binge eating (DIBE) have investigated plausible dopamine mechanisms involved in sustaining binge eating behaviors. In DIBE models, highly palatable foods (fats, sugars and their combination), as well as restricted access conditions appear to promote ingestive responses and result in sustained dopamine stimulation within the nucleus accumbens. Taken together with studies examining the comorbidity of illicit drug use and eating disorders, the data reviewed here support a role for dopamine in perpetuating the compulsive feeding patterns of BN and BED. As such, we propose that sustained stimulation of the dopamine systems by bingeing promoted by preexisting conditions (e.g., genetic traits, dietary restraint, stress, etc.) results in progressive impairments of dopamine signaling. To disrupt this vicious cycle, novel research-based treatment options aiming at the neural substrates of compulsive eating patterns are necessary. PMID:20417658

  10. Growth of dopamine crystals

    SciTech Connect

    Patil, Vidya Patki, Mugdha

    2016-05-06

    Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution. Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.

  11. Growth of dopamine crystals

    NASA Astrophysics Data System (ADS)

    Patil, Vidya; Patki, Mugdha

    2016-05-01

    Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution. Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.

  12. Updating dopamine reward signals

    PubMed Central

    Schultz, Wolfram

    2013-01-01

    Recent work has advanced our knowledge of phasic dopamine reward prediction error signals. The error signal is bidirectional, reflects well the higher order prediction error described by temporal difference learning models, is compatible with model-free and model-based reinforcement learning, reports the subjective rather than physical reward value during temporal discounting and reflects subjective stimulus perception rather than physical stimulus aspects. Dopamine activations are primarily driven by reward, and to some extent risk, whereas punishment and salience have only limited activating effects when appropriate controls are respected. The signal is homogeneous in terms of time course but heterogeneous in many other aspects. It is essential for synaptic plasticity and a range of behavioural learning situations. PMID:23267662

  13. Vascular dopamine-I receptors.

    PubMed

    Yasunari, K; Kohno, M; Yokokawa, K; Horio, T; Kano, H; Takeda, T

    1995-06-01

    The modulation of dopamine DA1 receptors of cultured rat renal arterial smooth muscle cells by phorbol ester, glucocorticoid and sodium chloride was studied. The extent of [3H]Sch-23390 binding to phorbol ester-treated cell was increased without any change in the dissociation constant (Kd). At a concentration of 10 nmol/l, the synthetic glucocorticoid dexamethasone increased maximum receptor binding (Bmax) but had no effect on the Kd. 100 mmol/l sodium chloride did not change Bmax, but increased the Kd for DA1 receptor. The production of cAMP in response to DA1 receptor stimulation was enhanced without any change of the adenylate cyclase activity. The glucocorticoid effect on DA1 of arterial smooth muscle cells became apparent after hours of incubation in the presence of the steroid and was significantly inhibited by cycloheximide (10 micrograms/ml) and by the glucocorticoid receptor antagonist RU-38486, indicating that the effect required protein synthesis through glucocorticoid receptors. Treatment of cells with 1 mumol/l dexamethasone for 24 h increased basal and DA1-stimulated adenylate cyclase activity. Basal adenylate cyclase was decreased by sodium chloride in a dose-dependent manner. These results suggest differential control of DA1 receptors on vascular smooth muscle cells by protein kinase C, glucocorticoid or sodium chloride.

  14. Immunomodulatory Effects Mediated by Dopamine

    PubMed Central

    Alvarez-Herrera, Samantha; Pérez-Sánchez, Gilberto; Becerril-Villanueva, Enrique; Cruz-Fuentes, Carlos; Flores-Gutierrez, Enrique Octavio; Quintero-Fabián, Saray

    2016-01-01

    Dopamine (DA), a neurotransmitter in the central nervous system (CNS), has modulatory functions at the systemic level. The peripheral and central nervous systems have independent dopaminergic system (DAS) that share mechanisms and molecular machinery. In the past century, experimental evidence has accumulated on the proteins knowledge that is involved in the synthesis, reuptake, and transportation of DA in leukocytes and the differential expression of the D1-like (D1R and D5R) and D2-like receptors (D2R, D3R, and D4R). The expression of these components depends on the state of cellular activation and the concentration and time of exposure to DA. Receptors that are expressed in leukocytes are linked to signaling pathways that are mediated by changes in cAMP concentration, which in turn triggers changes in phenotype and cellular function. According to the leukocyte lineage, the effects of DA are associated with such processes as respiratory burst, cytokine and antibody secretion, chemotaxis, apoptosis, and cytotoxicity. In clinical conditions such as schizophrenia, Parkinson disease, Tourette syndrome, and multiple sclerosis (MS), there are evident alterations during immune responses in leukocytes, in which changes in DA receptor density have been observed. Several groups have proposed that these findings are useful in establishing clinical status and clinical markers. PMID:27795960

  15. Immunomodulatory Effects Mediated by Dopamine.

    PubMed

    Arreola, Rodrigo; Alvarez-Herrera, Samantha; Pérez-Sánchez, Gilberto; Becerril-Villanueva, Enrique; Cruz-Fuentes, Carlos; Flores-Gutierrez, Enrique Octavio; Garcés-Alvarez, María Eugenia; de la Cruz-Aguilera, Dora Luz; Medina-Rivero, Emilio; Hurtado-Alvarado, Gabriela; Quintero-Fabián, Saray; Pavón, Lenin

    2016-01-01

    Dopamine (DA), a neurotransmitter in the central nervous system (CNS), has modulatory functions at the systemic level. The peripheral and central nervous systems have independent dopaminergic system (DAS) that share mechanisms and molecular machinery. In the past century, experimental evidence has accumulated on the proteins knowledge that is involved in the synthesis, reuptake, and transportation of DA in leukocytes and the differential expression of the D1-like (D1R and D5R) and D2-like receptors (D2R, D3R, and D4R). The expression of these components depends on the state of cellular activation and the concentration and time of exposure to DA. Receptors that are expressed in leukocytes are linked to signaling pathways that are mediated by changes in cAMP concentration, which in turn triggers changes in phenotype and cellular function. According to the leukocyte lineage, the effects of DA are associated with such processes as respiratory burst, cytokine and antibody secretion, chemotaxis, apoptosis, and cytotoxicity. In clinical conditions such as schizophrenia, Parkinson disease, Tourette syndrome, and multiple sclerosis (MS), there are evident alterations during immune responses in leukocytes, in which changes in DA receptor density have been observed. Several groups have proposed that these findings are useful in establishing clinical status and clinical markers.

  16. Dorsal striatal dopamine, food preference and health perception in humans.

    PubMed

    Wallace, Deanna L; Aarts, Esther; Dang, Linh C; Greer, Stephanie M; Jagust, William J; D'Esposito, Mark

    2014-01-01

    To date, few studies have explored the neurochemical mechanisms supporting individual differences in food preference in humans. Here we investigate how dorsal striatal dopamine, as measured by the positron emission tomography (PET) tracer [(18)F]fluorometatyrosine (FMT), correlates with food-related decision-making, as well as body mass index (BMI) in 16 healthy-weight to moderately obese individuals. We find that lower PET FMT dopamine synthesis binding potential correlates with higher BMI, greater preference for perceived "healthy" foods, but also greater healthiness ratings for food items. These findings further substantiate the role of dorsal striatal dopamine in food-related behaviors and shed light on the complexity of individual differences in food preference.

  17. Dorsal Striatal Dopamine, Food Preference and Health Perception in Humans

    PubMed Central

    Wallace, Deanna L.; Aarts, Esther; Dang, Linh C.; Greer, Stephanie M.; Jagust, William J.; D′Esposito, Mark

    2014-01-01

    To date, few studies have explored the neurochemical mechanisms supporting individual differences in food preference in humans. Here we investigate how dorsal striatal dopamine, as measured by the positron emission tomography (PET) tracer [18F]fluorometatyrosine (FMT), correlates with food-related decision-making, as well as body mass index (BMI) in 16 healthy-weight to moderately obese individuals. We find that lower PET FMT dopamine synthesis binding potential correlates with higher BMI, greater preference for perceived “healthy” foods, but also greater healthiness ratings for food items. These findings further substantiate the role of dorsal striatal dopamine in food-related behaviors and shed light on the complexity of individual differences in food preference. PMID:24806534

  18. Morbillivirus downregulation of CD46.

    PubMed

    Galbraith, S E; Tiwari, A; Baron, M D; Lund, B T; Barrett, T; Cosby, S L

    1998-12-01

    There is evidence that CD46 (membrane cofactor protein) is a cellular receptor for vaccine and laboratory-passaged strains of measles virus (MV). Following infection with these MV strains, CD46 is downregulated from the cell surface, and consequent complement-mediated lysis has been shown to occur upon infection of a human monocytic cell line. The MV hemagglutinin (H) protein alone is capable of inducing this downregulation. Some wild-type strains of MV fail to downregulate CD46, despite infection being prevented by anti-CD46 antibodies. In this study we show that CD46 is also downregulated to the same extent by wild-type, vaccine, and laboratory-passaged strains of rinderpest virus (RPV), although CD46 did not appear to be the receptor for RPV. Expression of the RPV H protein by a nonreplicating adenovirus vector was also found to cause this downregulation. A vaccine strain of peste des petits ruminants virus caused slight downregulation of CD46 in infected Vero cells, while wild-type and vaccine strains of canine distemper virus and a wild-type strain of dolphin morbillivirus failed to downregulate CD46. Downregulation of CD46 can, therefore, be a function independent of the use of this protein as a virus receptor.

  19. Dopamine D-2 receptor imaging radiopharmaceuticals: synthesis, radiolabeling, and in vitro binding of (R)-(+)- and (S)-(-)-3-iodo-2-hydroxy-6-methoxy-N- ((1-ethyl-2-pyrrolidinyl)methyl)benzamide

    SciTech Connect

    Kung, H.F.; Kasliwal, R.; Pan, S.G.; Kung, M.P.; Mach, R.H.; Guo, Y.Z.

    1988-05-01

    In developing central nervous system (CNS) dopamine D-2 receptor imaging agents, enantiomers, R-(+) and S-(-) isomers, of 3-(/sup 125/I)iodo-2-hydroxy-6-methoxy-N-((1-ethyl-2- pyrrolidinyl)methyl)benzamide, (/sup 125/I)IBZM, were synthesized, and their in vitro binding characteristics were evaluated in rat striatum tissue preparation. The (S)-(-)-(/sup 125/I)IBZM showed high specific dopamine D-2 receptor binding (Kd = 0.43 nM, Bmax = 0.48 pmol/mg of protein). Competition data of various ligands for IBZM binding displayed the following rank order of potency: spiperone greater than (S)-(-)-IBZM greater than (+)-butaclamol much greater than (R)-(+)-IBZM greater than (S)-(-)-BZM greater than dopamine greater than ketanserin greater than SCH23390 much greater than propanolol. The results indicate that (/sup 125/I)IBZM binds specifically to the dopamine D-2-receptor with stereospecificity. The (/sup 125/I)IBZM is potentially useful as an imaging agent for the investigation of dopamine D-2 receptors in humans.

  20. Cocaine exposure modulates dopamine and adenosine signaling in the fetal brain

    PubMed Central

    Kubrusly, Regina C. C.; Bhide, Pradeep G.

    2009-01-01

    Exposure to cocaine during the fetal period can produce significant lasting changes in the structure and function of the brain. Cocaine exerts its effects on the developing brain by blocking monoamine transporters and impairing monoamine receptor signaling. Dopamine is a major central target of cocaine. In a mouse model, we show that cocaine exposure from embryonic day 8 (E8) to E14 produces significant reduction in dopamine transporter activity, attenuation of dopamine D1-receptor function and upregulation of dopamine D2-receptor function. Cocaine’s effects on the D1-receptor are at the level of protein expression as well as activity. The cocaine exposure also produces significant increases in basal cAMP levels in the striatum and cerebral cortex. The increase in the basal cAMP levels was independent of dopamine receptor activity. In contrast, blocking the adenosine A2a receptor downregulated of the basal cAMP levels in the cocaine-exposed brain to physiological levels, suggesting the involvement of adenosine receptors in mediating cocaine’s effects on the embryonic brain. In support of this suggestion, we found that the cocaine exposure downregulated adenosine transporter function. We also found that dopamine D2- and adenosine A2a-receptors antagonize each other’s function in the embryonic brain in a manner consistent with their interactions in the mature brain. Thus, our data show that prenatal cocaine exposure produces direct effects on both the dopamine and adenosine systems. Furthermore, the dopamine D2 and adenosine A2a receptor interactions in the embryonic brain discovered in this study unveil a novel substrate for cocaine’s effects on the developing brain. PMID:19765599

  1. Cocaine exposure modulates dopamine and adenosine signaling in the fetal brain.

    PubMed

    Kubrusly, Regina C C; Bhide, Pradeep G

    2010-02-01

    Exposure to cocaine during the fetal period can produce significant lasting changes in the structure and function of the brain. Cocaine exerts its effects on the developing brain by blocking monoamine transporters and impairing monoamine receptor signaling. Dopamine is a major central target of cocaine. In a mouse model, we show that cocaine exposure from embryonic day 8 (E8) to E14 produces significant reduction in dopamine transporter activity, attenuation of dopamine D1-receptor function and upregulation of dopamine D2-receptor function. Cocaine's effects on the D1-receptor are at the level of protein expression as well as activity. The cocaine exposure also produces significant increases in basal cAMP levels in the striatum and cerebral cortex. The increase in the basal cAMP levels was independent of dopamine receptor activity. In contrast, blocking the adenosine A2a receptor downregulated the basal cAMP levels in the cocaine-exposed brain to physiological levels, suggesting the involvement of adenosine receptors in mediating cocaine's effects on the embryonic brain. In support of this suggestion, we found that the cocaine exposure downregulated adenosine transporter function. We also found that dopamine D2- and adenosine A2a-receptors antagonize each other's function in the embryonic brain in a manner consistent with their interactions in the mature brain. Thus, our data show that prenatal cocaine exposure produces direct effects on both the dopamine and adenosine systems. Furthermore, the dopamine D2 and adenosine A2a receptor interactions in the embryonic brain discovered in this study unveil a novel substrate for cocaine's effects on the developing brain. 2009 Elsevier Ltd. All rights reserved.

  2. Discovery of a new class of potential multifunctional atypical antipsychotic agents targeting dopamine D3 and serotonin 5-HT1A and 5-HT2A receptors: design, synthesis, and effects on behavior.

    PubMed

    Butini, Stefania; Gemma, Sandra; Campiani, Giuseppe; Franceschini, Silvia; Trotta, Francesco; Borriello, Marianna; Ceres, Nicoletta; Ros, Sindu; Coccone, Salvatore Sanna; Bernetti, Matteo; De Angelis, Meri; Brindisi, Margherita; Nacci, Vito; Fiorini, Isabella; Novellino, Ettore; Cagnotto, Alfredo; Mennini, Tiziana; Sandager-Nielsen, Karin; Andreasen, Jesper Tobias; Scheel-Kruger, Jorgen; Mikkelsen, Jens D; Fattorusso, Caterina

    2009-01-08

    Dopamine D(3) antagonism combined with serotonin 5-HT(1A) and 5-HT(2A) receptor occupancy may represent a novel paradigm for developing innovative antipsychotics. The unique pharmacological features of 5i are a high affinity for dopamine D(3), serotonin 5-HT(1A) and 5-HT(2A) receptors, together with a low affinity for dopamine D(2) receptors (to minimize extrapyramidal side effects), serotonin 5-HT(2C) receptors (to reduce the risk of obesity under chronic treatment), and for hERG channels (to reduce incidence of torsade des pointes). Pharmacological and biochemical data, including specific c-fos expression in mesocorticolimbic areas, confirmed an atypical antipsychotic profile of 5i in vivo, characterized by the absence of catalepsy at antipsychotic dose.

  3. Switch from excitatory to inhibitory actions of ethanol on dopamine levels after chronic exposure: Role of kappa opioid receptors.

    PubMed

    Karkhanis, Anushree N; Huggins, Kimberly N; Rose, Jamie H; Jones, Sara R

    2016-11-01

    Acute ethanol exposure is known to stimulate the dopamine system; however, chronic exposure has been shown to downregulate the dopamine system. In rodents, chronic intermittent exposure (CIE) to ethanol also increases negative affect during withdrawal, such as, increases in anxiety- and depressive-like behavior. Moreover, CIE exposure results in increased ethanol drinking and preference during withdrawal. Previous literature documents reductions in CIE-induced anxiety-, depressive-like behaviors and ethanol intake in response to kappa opioid receptor (KOR) blockade. KORs are located on presynaptic dopamine terminals in the nucleus accumbens (NAc) and inhibit release, an effect which has been linked to negative affective behaviors. Previous reports show an upregulation in KOR function following extended CIE exposure; however it is not clear whether there is a direct link between KOR upregulation and dopamine downregulation during withdrawal from CIE. This study aimed to examine the effects of KOR modulation on dopamine responses to ethanol of behaving mice exposed to air or ethanol vapor in a repeated intermittent pattern. First, we showed that KORs have a greater response to an agonist after moderate CIE compared to air exposed mice using ex vivo fast scan cyclic voltammetry. Second, using in vivo microdialysis, we showed that, in contrast to the expected increase in extracellular levels of dopamine following an acute ethanol challenge in air exposed mice, CIE exposed mice exhibited a robust decrease in dopamine levels. Third, we showed that blockade of KORs reversed the aberrant inhibitory dopamine response to ethanol in CIE exposed mice while not affecting the air exposed mice demonstrating that inhibition of KORs "rescued" dopamine responses in CIE exposed mice. Taken together, these findings indicate that augmentation of dynorphin/KOR system activity drives the reduction in stimulated (electrical and ethanol) dopamine release in the NAc. Thus, blockade of

  4. Quercetin-3-O-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranoside suppresses melanin synthesis by augmenting p38 MAPK and CREB signaling pathways and subsequent cAMP down-regulation in murine melanoma cells

    PubMed Central

    Jung, Hyun Gug; Kim, Han Hyuk; Paul, Souren; Jang, Jae Yoon; Cho, Yong Hun; Kim, Hyeon Jeong; Yu, Jae Myo; Lee, Eun Su; An, Bong Jeun; Kang, Sun Chul; Bang, Byung Ho

    2015-01-01

    In this study, the effect of purified quercetin-3-O-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosid (QCGG) on melanogenesis was investigated. QCGG was isolated from the calyx of a traditional Korean medicinal herb, Persimmon (Diospyros kaki). The hypopigmentation effects of QCGG were determined by examination of cellular melanin contents, tyrosinase activity assay, cAMP assay, and Western blotting of α-MSH-stimulated B16F10 mouse melanoma cells. Our results showed that QCGG inhibited both melanin synthesis and tyrosinase activity in a concentration-dependent manner as well as significantly reduced the expression of melanogenic proteins such as microphthalmia-associated transcription factor (MITF), tyrosinase-related protein-1, tyrosinase-related protein-2, and tyrosinase. Moreover, QCGG inhibited intracellular cAMP levels, cAMP response element-binding protein (CREB), and p38 MAPK expression in α-MSH-stimulated B16F10 cells. Taken together, the suppressive effects of QCGG on melanogenesis may involve down-regulation of MITF and its downstream signaling pathway via phosphorylation of p38 MAPK and CREB along with reduced cAMP levels. These results indicate that QCGG reduced melanin synthesis by reducing expression of tyrosine and tyrosine-related proteins via extracellular signal-related protein kinase (ERK) activation, followed by down-regulation of CREB, p38, and MITF. PMID:26586997

  5. A heterocyclic compound CE-103 inhibits dopamine reuptake and modulates dopamine transporter and dopamine D1-D3 containing receptor complexes.

    PubMed

    Sase, Ajinkya; Aher, Yogesh D; Saroja, Sivaprakasam R; Ganesan, Minu Karthika; Sase, Sunetra; Holy, Marion; Höger, Harald; Bakulev, Vasiliy; Ecker, Gerhard F; Langer, Thierry; Sitte, Harald H; Leban, Johann; Lubec, Gert

    2016-03-01

    A series of compounds have been reported to enhance memory via the DA system and herein a heterocyclic compound was tested for working memory (WM) enhancement. 2-((benzhydrylsulfinyl)methyl)thiazole (CE-103) was synthesized in a six-step synthesis. Binding of CE-103 to the dopamine (DAT), serotonin (SERT) and norepinephrine (NET) transporters and dopamine reuptake inhibition was tested as well as blood brain permeation and a screen for GPCR targets. 60 male Sprague Dawley rats were divided into six groups: CE-103 treated 1-10 mg/kg body weight, trained (TDI) and yoked (YDI) and vehicle treated, trained (TVI) and yoked (YVI) rats. Daily single intraperitoneal injections for a period of 10 days were administered and rats were tested in a radial arm maze (RAM). Hippocampi were taken 6 h following the last day of training and complexes containing the unphosphorylated or phosphorylated dopamine transporter (DAT) and complexes containing the D1-3 dopamine receptor subunits were determined. CE-103 was binding to the DAT but insignificantly to SERT or NET and dopamine reuptake was blocked specifically (IC50 = 14.73 μM). From day eight the compound was decreasing WM errors in the RAM significantly at both doses tested as compared to the vehicle controls. In the trained CE-103-treated group levels of the complex containing the phosphorylated dopamine transporter (pDAT) as well as D1R were decreased while levels of complexes containing D2R and D3R were significantly increased. CE-103 was shown to enhance spatial WM and DA reuptake inhibition with subsequent modulation of D1-3 receptors is proposed as a possible mechanism of action.

  6. Dopamine- and Tyrosine Hydroxylase-Immunoreactive Neurons in the Brain of the American Cockroach, Periplaneta americana.

    PubMed

    Hamanaka, Yoshitaka; Minoura, Run; Nishino, Hiroshi; Miura, Toru; Mizunami, Makoto

    2016-01-01

    The catecholamine dopamine plays several vital roles in the central nervous system of many species, but its neural mechanisms remain elusive. Detailed neuroanatomical characterization of dopamine neurons is a prerequisite for elucidating dopamine's actions in the brain. In the present study, we investigated the distribution of dopaminergic neurons in the brain of the American cockroach, Periplaneta americana, using two antisera: 1) an antiserum against dopamine, and 2) an antiserum against tyrosine hydroxylase (TH, an enzyme required for dopamine synthesis), and identified about 250 putatively dopaminergic neurons. The patterns of dopamine- and TH-immunoreactive neurons were strikingly similar, suggesting that both antisera recognize the same sets of "dopaminergic" neurons. The dopamine and TH antibodies intensively or moderately immunolabeled prominent brain neuropils, e.g. the mushroom body (memory center), antennal lobe (first-order olfactory center) and central complex (motor coordination center). All subdivisions of the mushroom body exhibit both dopamine and TH immunoreactivity. Comparison of immunolabeled neurons with those filled by dye injection revealed that a group of immunolabeled neurons with cell bodies near the calyx projects into a distal region of the vertical lobe, which is a plausible site for olfactory memory formation in insects. In the antennal lobe, ordinary glomeruli as well as macroglomeruli exhibit both dopamine and TH immunoreactivity. It is noteworthy that the dopamine antiserum labeled tiny granular structures inside the glomeruli whereas the TH antiserum labeled processes in the marginal regions of the glomeruli, suggesting a different origin. In the central complex, all subdivisions excluding part of the noduli and protocerebral bridge exhibit both dopamine and TH immunoreactivity. These anatomical findings will accelerate our understanding of dopaminergic systems, specifically in neural circuits underlying aversive memory formation

  7. Selective effects of buspirone and molindone on dopamine metabolism and function in the striatum and frontal cortex of the rat.

    PubMed

    McMillen, B A; McDonald, C C

    1983-03-01

    The hypothesis that the nerve endings of the dopamine projection of the frontal cortex lack autoreceptors for regulation of tyrosine hydroxylase was tested by using the preferential inhibitors of dopamine autoreceptors, molindole and buspirone. In contrast to haloperidol, which elevates dopamine metabolism in the striatum and frontal cortex, both molindone and buspirone elicited little change in dopamine metabolism in the frontal cortex at doses up to 3.0 mg/kg, which cause the same maximal response in the corpus striatum as does haloperidol. Thus, the lack of autoreceptors in the frontal cortex is of pharmacological importance. That preferential inhibition of striatal dopamine autoreceptors may reverse catalepsy by enhancing synthesis and release of dopamine was tested by first inducing catalepsy with different drugs and then administering molindone or buspirone. Only buspirone (1.0 mg/kg) reversed catalepsy. This effect does not require presynaptic dopamine as catalepsy was reversed by buspirone in the dopamine-depleted rat (with 2.0 mg/kg R04-1284) as well as after postsynaptic dopamine receptor blockade by haloperidol of cis-flupenthixol. Thus, the mechanism for the reversal of catalepsy appears to be located efferent from the dopamine neuron. Buspirone, a non-benzodiazepine anti-anxiety drug, may prove useful for treatment of extrapyramidal motor disorders of either iatrogenic or idiosyncratic origin.

  8. Hypersensitivity of dopamine transmission in the rat striatum after treatment with the NMDA receptor antagonist amantadine.

    PubMed

    Peeters, Magali; Page, Guylène; Maloteaux, Jean-Marie; Hermans, Emmanuel

    2002-09-13

    Amantadine, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist known to increase dopamine synthesis and release in the striatum, is frequently associated with L-DOPA in the treatment of Parkinson's disease. However, the biochemical mechanisms involved in the effect of amantadine and the consequences of its repetitive administration on the modulation of striatal dopamine transmission still need to be clarified. We have investigated the effects of short-term amantadine treatments on the expression of dopamine receptors and the functional coupling to G proteins in rat striatal membranes. Dopamine-induced stimulation of guanosine 5'-[gamma-35S]triphosphate ([35S]GTPgammaS) binding was significantly enhanced (40%) in striatum homogenates from rats treated for 4 days with amantadine (40 mg/kg, i.p.) compared to vehicle-treated animals. This effect was specific for dopamine receptors and was transient as no significant modifications were observed when animals were treated for either 2 or 7 days. Administration of amantadine did not directly affect the animal behaviour. However, treated animals exhibited hypersensitive dopamine transmission since rats treated for 4 days showed exacerbated responses to a single apomorphine administration (enhanced locomotor activity and reduced stereotypy). Since the effects of amantadine administration differ from those usually observed with direct dopamine receptor agonists or other NMDA receptor antagonists, we suggest that multiple biochemical mechanisms contribute to the modulation of dopamine transmission by amantadine.

  9. Complexity of dopamine metabolism

    PubMed Central

    2013-01-01

    Parkinson’s disease (PD) coincides with a dramatic loss of dopaminergic neurons within the substantia nigra. A key player in the loss of dopaminergic neurons is oxidative stress. Dopamine (DA) metabolism itself is strongly linked to oxidative stress as its degradation generates reactive oxygen species (ROS) and DA oxidation can lead to endogenous neurotoxins whereas some DA derivatives show antioxidative effects. Therefore, DA metabolism is of special importance for neuronal redox-homeostasis and viability. In this review we highlight different aspects of dopamine metabolism in the context of PD and neurodegeneration. Since most reviews focus only on single aspects of the DA system, we will give a broader overview by looking at DA biosynthesis, sequestration, degradation and oxidation chemistry at the metabolic level, as well as at the transcriptional, translational and posttranslational regulation of all enzymes involved. This is followed by a short overview of cellular models currently used in PD research. Finally, we will address the topic from a medical point of view which directly aims to encounter PD. PMID:23683503

  10. Does dopamine connect the dots in ADPKD?

    PubMed

    Chapman, Arlene B

    2015-02-01

    Healthy autosomal dominant polycystic kidney disease (ADPKD) patients with normal kidney function demonstrate reduced endothelial-dependent vasodilation that improves with increasing local dopamine levels. Dopamine regulates renal sodium excretion, and dopamine receptors are located on primary cilia in both vascular and renal tubular epithelial cells. The study by Lorthioir and colleagues links endothelial function and dopamine availability in ADPKD patients.

  11. Differences in Number of Midbrain Dopamine Neurons Associated with Summer and Winter Photoperiods in Humans.

    PubMed

    Aumann, Tim D; Raabus, Mai; Tomas, Doris; Prijanto, Agustinus; Churilov, Leonid; Spitzer, Nicholas C; Horne, Malcolm K

    2016-01-01

    Recent evidence indicates the number of dopaminergic neurons in the adult rodent hypothalamus and midbrain is regulated by environmental cues, including photoperiod, and that this occurs via up- or down-regulation of expression of genes and proteins that are important for dopamine (DA) synthesis in extant neurons ('DA neurotransmitter switching'). If the same occurs in humans, it may have implications for neurological symptoms associated with DA imbalances. Here we tested whether there are differences in the number of tyrosine hydroxylase (TH, the rate-limiting enzyme in DA synthesis) and DA transporter (DAT) immunoreactive neurons in the midbrain of people who died in summer (long-day photoperiod, n = 5) versus winter (short-day photoperiod, n = 5). TH and DAT immunoreactivity in neurons and their processes was qualitatively higher in summer compared with winter. The density of TH immunopositive (TH+) neurons was significantly (~6-fold) higher whereas the density of TH immunonegative (TH-) neurons was significantly (~2.5-fold) lower in summer compared with winter. The density of total neurons (TH+ and TH- combined) was not different. The density of DAT+ neurons was ~2-fold higher whereas the density of DAT- neurons was ~2-fold lower in summer compared with winter, although these differences were not statistically significant. In contrast, midbrain nuclear volume, the density of supposed glia (small TH- cells), and the amount of TUNEL staining were the same in summer compared with winter. This study provides the first evidence of an association between environmental stimuli (photoperiod) and the number of midbrain DA neurons in humans, and suggests DA neurotransmitter switching underlies this association.

  12. Differences in Number of Midbrain Dopamine Neurons Associated with Summer and Winter Photoperiods in Humans

    PubMed Central

    Aumann, Tim D.; Raabus, Mai; Tomas, Doris; Prijanto, Agustinus; Churilov, Leonid; Spitzer, Nicholas C.; Horne, Malcolm K.

    2016-01-01

    Recent evidence indicates the number of dopaminergic neurons in the adult rodent hypothalamus and midbrain is regulated by environmental cues, including photoperiod, and that this occurs via up- or down-regulation of expression of genes and proteins that are important for dopamine (DA) synthesis in extant neurons (‘DA neurotransmitter switching’). If the same occurs in humans, it may have implications for neurological symptoms associated with DA imbalances. Here we tested whether there are differences in the number of tyrosine hydroxylase (TH, the rate-limiting enzyme in DA synthesis) and DA transporter (DAT) immunoreactive neurons in the midbrain of people who died in summer (long-day photoperiod, n = 5) versus winter (short-day photoperiod, n = 5). TH and DAT immunoreactivity in neurons and their processes was qualitatively higher in summer compared with winter. The density of TH immunopositive (TH+) neurons was significantly (~6-fold) higher whereas the density of TH immunonegative (TH-) neurons was significantly (~2.5-fold) lower in summer compared with winter. The density of total neurons (TH+ and TH- combined) was not different. The density of DAT+ neurons was ~2-fold higher whereas the density of DAT- neurons was ~2-fold lower in summer compared with winter, although these differences were not statistically significant. In contrast, midbrain nuclear volume, the density of supposed glia (small TH- cells), and the amount of TUNEL staining were the same in summer compared with winter. This study provides the first evidence of an association between environmental stimuli (photoperiod) and the number of midbrain DA neurons in humans, and suggests DA neurotransmitter switching underlies this association. PMID:27428306

  13. The Role of Genes, Stress, and Dopamine in the Development of Schizophrenia.

    PubMed

    Howes, Oliver D; McCutcheon, Robert; Owen, Michael J; Murray, Robin M

    2017-01-01

    The dopamine hypothesis is the longest standing pathoetiologic theory of schizophrenia. Because it was initially based on indirect evidence and findings in patients with established schizophrenia, it was unclear what role dopamine played in the onset of the disorder. However, recent studies in people at risk of schizophrenia have found elevated striatal dopamine synthesis capacity and increased dopamine release to stress. Furthermore, striatal dopamine changes have been linked to altered cortical function during cognitive tasks, in line with preclinical evidence that a circuit involving cortical projections to the striatum and midbrain may underlie the striatal dopamine changes. Other studies have shown that a number of environmental risk factors for schizophrenia, such as social isolation and childhood trauma, also affect presynaptic dopaminergic function. Advances in preclinical work and genetics have begun to unravel the molecular architecture linking dopamine, psychosis, and psychosocial stress. Included among the many genes associated with risk of schizophrenia are the gene encoding the dopamine D2 receptor and those involved in the upstream regulation of dopaminergic synthesis, through glutamatergic and gamma-aminobutyric acidergic pathways. A number of these pathways are also linked to the stress response. We review these new lines of evidence and present a model of how genes and environmental factors may sensitize the dopamine system so that it is vulnerable to acute stress, leading to progressive dysregulation and the onset of psychosis. Finally, we consider the implications for rational drug development, in particular regionally selective dopaminergic modulation, and the potential of genetic factors to stratify patients. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  14. Effects of Smoking Cessation on Presynaptic Dopamine Function of Addicted Male Smokers.

    PubMed

    Rademacher, Lena; Prinz, Susanne; Winz, Oliver; Henkel, Karsten; Dietrich, Claudia A; Schmaljohann, Jörn; Mohammadkhani Shali, Siamak; Schabram, Ina; Stoppe, Christian; Cumming, Paul; Hilgers, Ralf-Dieter; Kumakura, Yoshitaka; Coburn, Mark; Mottaghy, Felix M; Gründer, Gerhard; Vernaleken, Ingo

    2016-08-01

    There is evidence of abnormal cerebral dopamine transmission in nicotine-dependent smokers, but it is unclear whether dopaminergic abnormalities are due to acute nicotine abuse or whether they persist with abstinence. We addressed this question by conducting longitudinal positron emission tomography (PET) examination of smokers before and after 3 months of abstinence. We obtained baseline 6-[(18)F]fluoro-L-DOPA (FDOPA)-PET scans in 15 nonsmokers and 30 nicotine-dependent smokers, who either smoked as per their usual habit or were in acute withdrawal. All smokers then underwent cessation treatment, and successful abstainers were re-examined by FDOPA-PET after 3 months of abstinence (n = 15). Uptake of FDOPA was analyzed using a steady-state model yielding estimates of the dopamine synthesis capacity (K); the turnover of tracer dopamine formed in living brain (kloss); and the tracer distribution volume (Vd), which is an index of dopamine storage capacity. Compared with nonsmokers, K was 15% to 20% lower in the caudate nuclei of consuming smokers. Intraindividual comparisons of consumption and long-term abstinence revealed significant increases in K in the right dorsal and left ventral caudate nuclei. Relative to acute withdrawal, Vd significantly decreased in the right ventral and dorsal caudate after prolonged abstinence. Severity of nicotine dependence significantly correlated with dopamine synthesis capacity and dopamine turnover in the bilateral ventral putamen of consuming smokers. The results suggest a lower dopamine synthesis capacity in nicotine-dependent smokers that appears to normalize with abstinence. Further investigations are needed to clarify the role of dopamine in nicotine addiction to help develop smoking prevention and cessation treatments. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  15. mRNA expression of dopamine receptors in peripheral blood lymphocytes of computer game addicts.

    PubMed

    Vousooghi, Nasim; Zarei, Seyed Zeinolabedin; Sadat-Shirazi, Mitra-Sadat; Eghbali, Fatemeh; Zarrindast, Mohammad Reza

    2015-10-01

    Excessive playing of computer games like some other behaviors could lead to addiction. Addictive behaviors may induce their reinforcing effects through stimulation of the brain dopaminergic mesolimbic pathway. The status of dopamine receptors in the brain may be parallel to their homologous receptors in peripheral blood lymphocytes (PBLs). Here, we have investigated the mRNA expression of dopamine D3, D4 and D5 receptors in PBLs of computer game addicts (n = 20) in comparison to normal subjects (n = 20), using a real-time PCR method. The results showed that the expression level of D3 and D4 dopamine receptors in computer game addicts were not statistically different from the control group. However, the expression of the mRNA of D5 dopamine receptor was significantly down-regulated in PBLs of computer game addicts and reached 0.42 the amount of the control group. It is concluded that unlike with drug addiction, the expression levels of the D3 and D4 dopamine receptors in computer game addicts are not altered compared to the control group. However, reduced level of the D5 dopamine receptor in computer game addicts may serve as a peripheral marker in studies where the confounding effects of abused drugs are unwanted.

  16. Dopamine- and Tyrosine Hydroxylase-Immunoreactive Neurons in the Brain of the American Cockroach, Periplaneta americana

    PubMed Central

    Hamanaka, Yoshitaka; Minoura, Run; Nishino, Hiroshi; Miura, Toru; Mizunami, Makoto

    2016-01-01

    The catecholamine dopamine plays several vital roles in the central nervous system of many species, but its neural mechanisms remain elusive. Detailed neuroanatomical characterization of dopamine neurons is a prerequisite for elucidating dopamine’s actions in the brain. In the present study, we investigated the distribution of dopaminergic neurons in the brain of the American cockroach, Periplaneta americana, using two antisera: 1) an antiserum against dopamine, and 2) an antiserum against tyrosine hydroxylase (TH, an enzyme required for dopamine synthesis), and identified about 250 putatively dopaminergic neurons. The patterns of dopamine- and TH-immunoreactive neurons were strikingly similar, suggesting that both antisera recognize the same sets of “dopaminergic” neurons. The dopamine and TH antibodies intensively or moderately immunolabeled prominent brain neuropils, e.g. the mushroom body (memory center), antennal lobe (first-order olfactory center) and central complex (motor coordination center). All subdivisions of the mushroom body exhibit both dopamine and TH immunoreactivity. Comparison of immunolabeled neurons with those filled by dye injection revealed that a group of immunolabeled neurons with cell bodies near the calyx projects into a distal region of the vertical lobe, which is a plausible site for olfactory memory formation in insects. In the antennal lobe, ordinary glomeruli as well as macroglomeruli exhibit both dopamine and TH immunoreactivity. It is noteworthy that the dopamine antiserum labeled tiny granular structures inside the glomeruli whereas the TH antiserum labeled processes in the marginal regions of the glomeruli, suggesting a different origin. In the central complex, all subdivisions excluding part of the noduli and protocerebral bridge exhibit both dopamine and TH immunoreactivity. These anatomical findings will accelerate our understanding of dopaminergic systems, specifically in neural circuits underlying aversive memory

  17. Dopamine reward prediction error coding

    PubMed Central

    Schultz, Wolfram

    2016-01-01

    Reward prediction errors consist of the differences between received and predicted rewards. They are crucial for basic forms of learning about rewards and make us strive for more rewards—an evolutionary beneficial trait. Most dopamine neurons in the midbrain of humans, monkeys, and rodents signal a reward prediction error; they are activated by more reward than predicted (positive prediction error), remain at baseline activity for fully predicted rewards, and show depressed activity with less reward than predicted (negative prediction error). The dopamine signal increases nonlinearly with reward value and codes formal economic utility. Drugs of addiction generate, hijack, and amplify the dopamine reward signal and induce exaggerated, uncontrolled dopamine effects on neuronal plasticity. The striatum, amygdala, and frontal cortex also show reward prediction error coding, but only in subpopulations of neurons. Thus, the important concept of reward prediction errors is implemented in neuronal hardware. PMID:27069377

  18. Dopamine reward prediction error coding.

    PubMed

    Schultz, Wolfram

    2016-03-01

    Reward prediction errors consist of the differences between received and predicted rewards. They are crucial for basic forms of learning about rewards and make us strive for more rewards-an evolutionary beneficial trait. Most dopamine neurons in the midbrain of humans, monkeys, and rodents signal a reward prediction error; they are activated by more reward than predicted (positive prediction error), remain at baseline activity for fully predicted rewards, and show depressed activity with less reward than predicted (negative prediction error). The dopamine signal increases nonlinearly with reward value and codes formal economic utility. Drugs of addiction generate, hijack, and amplify the dopamine reward signal and induce exaggerated, uncontrolled dopamine effects on neuronal plasticity. The striatum, amygdala, and frontal cortex also show reward prediction error coding, but only in subpopulations of neurons. Thus, the important concept of reward prediction errors is implemented in neuronal hardware.

  19. Modification of dopamine D2 receptor activity by pergolide in Parkinson's disease: an in vivo study by PET.

    PubMed

    Linazasoro, G; Obeso, J A; Gómez, J C; Martínez, M; Antonini, A; Leenders, K L

    1999-01-01

    It is well known that chronic administration of pergolide and other dopamine agonists may induce a downregulation of dopamine D2 receptors in the rat model of Parkinson's disease (PD). To our knowledge, this effect has not been demonstrated in vivo in patients with PD. At present, the status of striatal dopamine D2 receptors can be studied with use of positron emission tomographic (PET) technology. Five patients with PD chronically treated with levodopa were studied with use of PET and [11C]-raclopride before and after 6 months of pergolide treatment (dose range = 4.5-7.5 mg/d). We found a slight reduction in the specific striatal [11C]-raclopride uptake index (mean reduction 14% in putamen and 9% in caudate) after pergolide treatment. This reduction appears to be related to downregulation of the receptor, although competitive binding of pergolide at the D2 receptor cannot be excluded.

  20. Design, Synthesis, and Structure–Activity Relationship Studies of a Series of [4-(4-Carboxamidobutyl)]-1-arylpiperazines: Insights into Structural Features Contributing to Dopamine D3 versus D2 Receptor Subtype Selectivity

    PubMed Central

    2015-01-01

    Antagonist and partial agonist modulators of the dopamine D3 receptor (D3R) have emerged as promising therapeutics for the treatment of substance abuse and neuropsychiatric disorders. However, development of druglike lead compounds with selectivity for the D3 receptor has been challenging because of the high sequence homology between the D3R and the dopamine D2 receptor (D2R). In this effort, we synthesized a series of acylaminobutylpiperazines incorporating aza-aromatic units and evaluated their binding and functional activities at the D3 and D2 receptors. Docking studies and results from evaluations against a set of chimeric and mutant receptors suggest that interactions at the extracellular end of TM7 contribute to the D3R versus D2R selectivity of these ligands. Molecular insights from this study could potentially enable rational design of potent and selective D3R ligands. PMID:25126833

  1. Dopamine, Affordance and Active Inference

    PubMed Central

    Friston, Karl J.; Shiner, Tamara; FitzGerald, Thomas; Galea, Joseph M.; Adams, Rick; Brown, Harriet; Dolan, Raymond J.; Moran, Rosalyn; Stephan, Klaas Enno; Bestmann, Sven

    2012-01-01

    The role of dopamine in behaviour and decision-making is often cast in terms of reinforcement learning and optimal decision theory. Here, we present an alternative view that frames the physiology of dopamine in terms of Bayes-optimal behaviour. In this account, dopamine controls the precision or salience of (external or internal) cues that engender action. In other words, dopamine balances bottom-up sensory information and top-down prior beliefs when making hierarchical inferences (predictions) about cues that have affordance. In this paper, we focus on the consequences of changing tonic levels of dopamine firing using simulations of cued sequential movements. Crucially, the predictions driving movements are based upon a hierarchical generative model that infers the context in which movements are made. This means that we can confuse agents by changing the context (order) in which cues are presented. These simulations provide a (Bayes-optimal) model of contextual uncertainty and set switching that can be quantified in terms of behavioural and electrophysiological responses. Furthermore, one can simulate dopaminergic lesions (by changing the precision of prediction errors) to produce pathological behaviours that are reminiscent of those seen in neurological disorders such as Parkinson's disease. We use these simulations to demonstrate how a single functional role for dopamine at the synaptic level can manifest in different ways at the behavioural level. PMID:22241972

  2. Genetic variations in the dopamine system and facial expression recognition in healthy chinese college students.

    PubMed

    Zhu, Bi; Chen, Chuansheng; Moyzis, Robert K; Dong, Qi; Chen, Chunhui; He, Qinghua; Stern, Hal S; Li, He; Li, Jin; Li, Jun; Lessard, Jared; Lin, Chongde

    2012-01-01

    This study investigated the relation between genetic variations in the dopamine system and facial expression recognition. A sample of Chinese college students (n = 478) was given a facial expression recognition task. Subjects were genotyped for 98 loci [96 single-nucleotide polymorphisms (SNPs) and 2 variable number tandem repeats] in 16 genes involved in the dopamine neurotransmitter system, including its 4 subsystems: synthesis (TH, DDC, and DBH), degradation/transport (COMT,MAOA,MAOB, and SLC6A3), receptors (DRD1,DRD2,DRD3,DRD4, and DRD5), and modulation (NTS,NTSR1,NTSR2, and NLN). To quantify the total contributions of the dopamine system to emotion recognition, we used a series of multiple regression models. Permutation analyses were performed to assess the posterior probabilities of obtaining such results. Among the 78 loci that were included in the final analyses (after excluding 12 SNPs that were in high linkage disequilibrium and 8 that were not in Hardy-Weinberg equilibrium), 1 (for fear), 3 (for sadness), 5 (for anger), 13 (for surprise), and 15 (for disgust) loci exhibited main effects on the recognition of facial expressions. Genetic variations in the dopamine system accounted for 3% for fear, 6% for sadness, 7% for anger, 10% for surprise, and 18% for disgust, with the latter surviving a stringent permutation test. Genetic variations in the dopamine system (especially the dopamine synthesis and modulation subsystems) made significant contributions to individual differences in the recognition of disgust faces. Copyright © 2012 S. Karger AG, Basel.

  3. Dynamic Nigrostriatal Dopamine Biases Action Selection.

    PubMed

    Howard, Christopher D; Li, Hao; Geddes, Claire E; Jin, Xin

    2017-03-22

    Dopamine is thought to play a critical role in reinforcement learning and goal-directed behavior, but its function in action selection remains largely unknown. Here we demonstrate that nigrostriatal dopamine biases ongoing action selection. When mice were trained to dynamically switch the action selected at different time points, changes in firing rate of nigrostriatal dopamine neurons, as well as dopamine signaling in the dorsal striatum, were found to be associated with action selection. This dopamine profile is specific to behavioral choice, scalable with interval duration, and doesn't reflect reward prediction error, timing, or value as single factors alone. Genetic deletion of NMDA receptors on dopamine or striatal neurons or optogenetic manipulation of dopamine concentration alters dopamine signaling and biases action selection. These results unveil a crucial role of nigrostriatal dopamine in integrating diverse information for regulating upcoming actions, and they have important implications for neurological disorders, including Parkinson's disease and substance dependence. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Endogenous dopamine is involved in the herbicide paraquat-induced dopaminergic cell death.

    PubMed

    Izumi, Yasuhiko; Ezumi, Masayuki; Takada-Takatori, Yuki; Akaike, Akinori; Kume, Toshiaki

    2014-06-01

    The herbicide paraquat is an environmental factor that may be involved in the etiology of Parkinson's disease (PD). Systemic exposure of mice to paraquat causes a selective loss of dopaminergic neurons in the substantia nigra pars compacta, although paraquat is not selectively incorporated in dopaminergic neurons. Here, we report a contribution of endogenous dopamine to paraquat-induced dopaminergic cell death. Exposure of PC12 cells to paraquat (50μM) caused delayed toxicity from 36 h onward. A decline in intracellular dopamine content achieved by inhibiting tyrosine hydroxylase (TH), an enzyme for dopamine synthesis, conferred resistance to paraquat toxicity on dopaminergic cells. Paraquat increased the levels of cytosolic and vesicular dopamine, accompanied by transiently increased TH activity. Quinone derived from cytosolic dopamine conjugates with cysteine residues in functional proteins to form quinoproteins. Formation of quinoprotein was transiently increased early during exposure to paraquat. Furthermore, pretreatment with ascorbic acid, which suppressed the elevations of intracellular dopamine and quinoprotein, almost completely prevented paraquat toxicity. These results suggest that the elevation of cytosolic dopamine induced by paraquat participates in the vulnerability of dopaminergic cells to delayed toxicity through the formation of quinoproteins.

  5. Genetic variation in COMT activity impacts learning and dopamine release capacity in the striatum.

    PubMed

    Simpson, Eleanor H; Morud, Julia; Winiger, Vanessa; Biezonski, Dominik; Zhu, Judy P; Bach, Mary Elizabeth; Malleret, Gael; Polan, H Jonathan; Ng-Evans, Scott; Phillips, Paul E M; Kellendonk, Christoph; Kandel, Eric R

    2014-03-17

    A common genetic polymorphism that results in increased activity of the dopamine regulating enzyme COMT (the COMT Val(158) allele) has been found to associate with poorer cognitive performance and increased susceptibility to develop psychiatric disorders. It is generally assumed that this increase in COMT activity influences cognitive function and psychiatric disease risk by increasing dopamine turnover in cortical synapses, though this cannot be directly measured in humans. Here we explore a novel transgenic mouse model of increased COMT activity, equivalent to the relative increase in activity observed with the human COMT Val(158) allele. By performing an extensive battery of behavioral tests, we found that COMT overexpressing mice (COMT-OE mice) exhibit cognitive deficits selectively in the domains that are affected by the COMT Val(158) allele, stimulus-response learning and working memory, functionally validating our model of increased COMT activity. Although we detected no changes in the level of markers for dopamine synthesis and dopamine transport, we found that COMT-OE mice display an increase in dopamine release capacity in the striatum. This result suggests that increased COMT activity may not only affect dopamine signaling by enhancing synaptic clearance in the cortex, but may also cause changes in presynaptic dopamine function in the striatum. These changes may underlie the behavioral deficits observed in the mice and might also play a role in the cognitive deficits and increased psychiatric disease risk associated with genetic variation in COMT activity in humans.

  6. Genetic variation in COMT activity impacts learning and dopamine release capacity in the striatum

    PubMed Central

    Simpson, Eleanor H.; Morud, Julia; Winiger, Vanessa; Biezonski, Dominik; Zhu, Judy P.; Bach, Mary Elizabeth; Malleret, Gael; Polan, H. Jonathan; Ng-Evans, Scott; Phillips, Paul E.M.; Kellendonk, Christoph; Kandel, Eric R.

    2014-01-01

    A common genetic polymorphism that results in increased activity of the dopamine regulating enzyme COMT (the COMT Val158 allele) has been found to associate with poorer cognitive performance and increased susceptibility to develop psychiatric disorders. It is generally assumed that this increase in COMT activity influences cognitive function and psychiatric disease risk by increasing dopamine turnover in cortical synapses, though this cannot be directly measured in humans. Here we explore a novel transgenic mouse model of increased COMT activity, equivalent to the relative increase in activity observed with the human COMT Val158 allele. By performing an extensive battery of behavioral tests, we found that COMT overexpressing mice (COMT-OE mice) exhibit cognitive deficits selectively in the domains that are affected by the COMT Val158 allele, stimulus–response learning and working memory, functionally validating our model of increased COMT activity. Although we detected no changes in the level of markers for dopamine synthesis and dopamine transport, we found that COMT-OE mice display an increase in dopamine release capacity in the striatum. This result suggests that increased COMT activity may not only affect dopamine signaling by enhancing synaptic clearance in the cortex, but may also cause changes in presynaptic dopamine function in the striatum. These changes may underlie the behavioral deficits observed in the mice and might also play a role in the cognitive deficits and increased psychiatric disease risk associated with genetic variation in COMT activity in humans. PMID:24639487

  7. The Role of Dopamine in Inflammation-Associated Depression: Mechanisms and Therapeutic Implications.

    PubMed

    Felger, Jennifer C

    Studies investigating the impact of a variety of inflammatory stimuli on the brain and behavior have consistently reported evidence that inflammatory cytokines affect the basal ganglia and dopamine to mediate depressive symptoms related to motivation and motor activity. Findings have included inflammation-associated reductions in ventral striatal responses to hedonic reward, decreased dopamine and dopamine metabolites in cerebrospinal fluid, and decreased availability of striatal dopamine, all of which correlate with symptoms of anhedonia, fatigue, and psychomotor retardation. Similar relationships between alterations in dopamine-relevant corticostriatal reward circuitry and symptoms of anhedonia and psychomotor slowing have also been observed in patients with major depression who exhibit increased peripheral cytokines and other inflammatory markers, such as C-reactive protein. Of note, these inflammation-associated depressive symptoms are often difficult to treat in patients with medical illnesses or major depression. Furthermore, a wealth of literature suggests that inflammation can decrease dopamine synthesis, packaging, and release, thus sabotaging or circumventing the efficacy of standard antidepressant treatments. Herein, the mechanisms by which inflammation and cytokines affect dopamine neurotransmission are discussed, which may provide novel insights into treatment of inflammation-related behavioral symptoms that contribute to an inflammatory malaise.

  8. History of the discovery of the antipsychotic dopamine D2 receptor: a basis for the dopamine hypothesis of schizophrenia.

    PubMed

    Madras, Bertha K

    2013-01-01

    The 1975 publication of Seeman et al. (Proc Nat Acad Sci, USA), reporting the discovery of the antipsychotic receptor in the brain, is a classic example of translational medicine research. In searching for a pathophysiological mechanism of psychosis, the team sought to identify sites that bound the antipsychotic drug haloperidol. Their criterion was that haloperidol bound to the site at one to two nanomoles per liter, corresponding to haloperidol concentrations found in spinal fluid or plasma water in treated patients. They requested de novo synthesis of tritiated haloperidol, and it readily detected specific haloperidol binding sites in brain striatum. With dopamine binding the haloperidol-labeled sites with higher potency than other neurotransmitters, the sites were named antipsychotic/dopamine receptors (now designated dopamine D2 receptors). Most significantly, they found that all antipsychotics bound these sites at concentrations and with a rank order of potencies that were directly related to the mean daily antipsychotic dose taken by patients with schizophrenia. Their findings enabled screening for new antipsychotics, initiated D2 receptor measurements in brain of living patients, and determination of minimum occupancy (65%) of D2 receptors for antipsychotic benefit. The collective work is generally viewed as providing a fundamental basis for the dopamine hypothesis of schizophrenia.

  9. Dopamine Receptors and Neurodegeneration

    PubMed Central

    Rangel-Barajas, Claudia; Coronel, Israel; Florán, Benjamín

    2015-01-01

    Dopamine (DA) is one of the major neurotransmitters and participates in a number of functions such as motor coordination, emotions, memory, reward mechanism, neuroendocrine regulation etc. DA exerts its effects through five DA receptors that are subdivided in 2 families: D1-like DA receptors (D1 and D5) and the D2-like (D2, D3 and D4). All DA receptors are widely expressed in the central nervous system (CNS) and play an important role in not only in physiological conditions but also pathological scenarios. Abnormalities in the DAergic system and its receptors in the basal ganglia structures are the basis Parkinson’s disease (PD), however DA also participates in other neurodegenerative disorders such as Huntington disease (HD) and multiple sclerosis (MS). Under pathological conditions reorganization of DAergic system has been observed and most of the times, those changes occur as a mechanism of compensation, but in some cases contributes to worsening the alterations. Here we review the changes that occur on DA transmission and DA receptors (DARs) at both levels expression and signals transduction pathways as a result of neurotoxicity, inflammation and in neurodegenerative processes. The better understanding of the role of DA receptors in neuropathological conditions is crucial for development of novel therapeutic approaches to treat alterations related to neurodegenerative diseases. PMID:26425390

  10. The nature of dopamine dysfunction in schizophrenia and what this means for treatment

    PubMed Central

    Howes, Oliver D; Kambeitz, Joseph; Kim, Euitae; Stahl, Daniel; Slifstein, Mark; Abi-Dargham, Anissa; Kapur, Shitij

    2013-01-01

    Context Current drug treatments for schizophrenia are inadequate for many patients and, despite five decades of drug discovery, all use the same mechanism-dopamine D2 receptor blockade. Understanding the pathophysiology of the disorder is thus likely to be critical to the rational development of new treatments for schizophrenia. Objective To investigate the nature of the dopaminergic dysfunction in schizophrenia using meta-analysis of in vivo studies. Data sources The MEDLINE, EMBASE and PsychINFO databases were searched for studies from January 1, 1960, to July 1, 2011. Study selection Forty-four studies were identified that compared in vivo striatal dopaminergic function in 618 patients with schizophrenia with 606 controls using positron emission tomography or single photon emission computed tomography. Data extraction Demographic, clinical and imaging variables were extracted from each study and effect sizes determined for the measures of dopaminergic function. Studies were grouped into those of presynaptic function, and dopamine transporter and receptor availability. Sensitivity analyses were conducted to explore the consistency of effects and the effect of clinical and imaging variables. Data synthesis There was a highly significant elevation (p<0.0001) in presynaptic dopaminergic function in schizophrenia with a large effect size (Cohen’s d=0.79). There was no evidence of alterations in dopamine transporter availability. There was a small elevation in D2/3 receptor availability (Cohen’s d=0.26), but this was not evident in drug-naïve patients and was influenced by the imaging approach used. Conclusions The locus of the largest dopaminergic abnormality in schizophrenia is presynaptic-affecting dopamine synthesis capacity, baseline synaptic dopamine levels and dopamine release. Current drug treatments - which primarily act at D2/3 receptors - fail to target these abnormalities. Future drug development should focus on the control of presynaptic dopamine

  11. Dopamine modulates insulin release and is involved in the survival of rat pancreatic beta cells.

    PubMed

    Garcia Barrado, Maria Jose; Iglesias Osma, Maria Carmen; Blanco, Enrique J; Carretero Hernández, Marta; Sánchez Robledo, Virginia; Catalano Iniesta, Leonardo; Carrero, Sixto; Carretero, Jose

    2015-01-01

    The local synthesis of dopamine and its effects on insulin release have been described in isolated islets. Thus, it may be accepted that dopamine exerts an auto-paracrine regulation of insulin secretion from pancreatic beta cells. The aim of the present study is to analyze whether dopamine is a regulator of the proliferation and apoptosis of rat pancreatic beta cells after glucose-stimulated insulin secretion. Glucose stimulated pancreatic islets obtained from male Wistar rats were cultured with 1 or 10 μM dopamine from 1 to 12 h. Insulin secretion was analyzed by RIA. The cellular proliferation rate of pancreatic islets and beta cells was studied with immunocytochemical double labelling for both insulin and PCNA (proliferating cell nuclear antigen), and active caspase-3 was detected to evaluate apoptosis. The secretion of insulin from isolated islets was significantly inhibited (p<0.01), by treatment with 1 and 10 μM dopamine, with no differences between either dose as early as 1 h after treatment. The percentage of insulin-positive cells in the islets decreased significantly (p<0.01) after 1 h of treatment up to 12 h. The proliferation rate of insulin-positive cells in the islets decreased significantly (p<0.01) following treatment with dopamine. Apoptosis in pancreatic islets and beta cells was increased by treatment with 1 and 10 μM dopamine along 12 h. In conclusion, these results suggest that dopamine could modulate the proliferation and apoptosis of pancreatic beta cells and that dopamine may be involved in the maintenance of pancreatic islets.

  12. Dopamine Modulates Insulin Release and Is Involved in the Survival of Rat Pancreatic Beta Cells

    PubMed Central

    Iglesias Osma, Maria Carmen; Blanco, Enrique J.; Carretero Hernández, Marta; Sánchez Robledo, Virginia; Catalano Iniesta, Leonardo; Carrero, Sixto

    2015-01-01

    The local synthesis of dopamine and its effects on insulin release have been described in isolated islets. Thus, it may be accepted that dopamine exerts an auto-paracrine regulation of insulin secretion from pancreatic beta cells. The aim of the present study is to analyze whether dopamine is a regulator of the proliferation and apoptosis of rat pancreatic beta cells after glucose-stimulated insulin secretion. Glucose stimulated pancreatic islets obtained from male Wistar rats were cultured with 1 or 10 μM dopamine from 1 to 12 h. Insulin secretion was analyzed by RIA. The cellular proliferation rate of pancreatic islets and beta cells was studied with immunocytochemical double labelling for both insulin and PCNA (proliferating cell nuclear antigen), and active caspase-3 was detected to evaluate apoptosis. The secretion of insulin from isolated islets was significantly inhibited (p<0.01), by treatment with 1 and 10 μM dopamine, with no differences between either dose as early as 1 h after treatment. The percentage of insulin-positive cells in the islets decreased significantly (p<0.01) after 1 h of treatment up to 12 h. The proliferation rate of insulin-positive cells in the islets decreased significantly (p<0.01) following treatment with dopamine. Apoptosis in pancreatic islets and beta cells was increased by treatment with 1 and 10 μM dopamine along 12 h. In conclusion, these results suggest that dopamine could modulate the proliferation and apoptosis of pancreatic beta cells and that dopamine may be involved in the maintenance of pancreatic islets. PMID:25886074

  13. Dopamine, reward learning, and active inference

    PubMed Central

    FitzGerald, Thomas H. B.; Dolan, Raymond J.; Friston, Karl

    2015-01-01

    Temporal difference learning models propose phasic dopamine signaling encodes reward prediction errors that drive learning. This is supported by studies where optogenetic stimulation of dopamine neurons can stand in lieu of actual reward. Nevertheless, a large body of data also shows that dopamine is not necessary for learning, and that dopamine depletion primarily affects task performance. We offer a resolution to this paradox based on an hypothesis that dopamine encodes the precision of beliefs about alternative actions, and thus controls the outcome-sensitivity of behavior. We extend an active inference scheme for solving Markov decision processes to include learning, and show that simulated dopamine dynamics strongly resemble those actually observed during instrumental conditioning. Furthermore, simulated dopamine depletion impairs performance but spares learning, while simulated excitation of dopamine neurons drives reward learning, through aberrant inference about outcome states. Our formal approach provides a novel and parsimonious reconciliation of apparently divergent experimental findings. PMID:26581305

  14. Dopamine regulates body size in Caenorhabditis elegans.

    PubMed

    Nagashima, Takashi; Oami, Eitaro; Kutsuna, Natsumaro; Ishiura, Shoichi; Suo, Satoshi

    2016-04-01

    The nervous system plays a critical role in the regulation of animal body sizes. In Caenorhabditis elegans, an amine neurotransmitter, dopamine, is required for the tactile perception of food and food-dependent behavioral changes, while its role in development is unknown. In this study, we show that dopamine negatively regulates body size through a D2-like dopamine receptor, DOP-3, in C. elegans. Dopamine alters body size without affecting food intake or developmental rate. We also found that dopamine promotes egg-laying, although the regulation of body size by dopamine was not solely caused by this effect. Furthermore, dopamine negatively regulates body size through the suppression of signaling by octopamine and Gq-coupled octopamine receptors, SER-3 and SER-6. Our results demonstrate that dopamine and octopamine regulate the body size of C. elegans and suggest a potential role for perception in addition to ingestion of food for growth.

  15. Functional Fast Scan Cyclic Voltammetry Assay to Characterize Dopamine D2 and D3 Autoreceptors in the Mouse Striatum

    PubMed Central

    2010-01-01

    Dopamine D2 and D3 autoreceptors are located on presynaptic terminals and are known to control the release and synthesis of dopamine. Dopamine D3 receptors have a fairly restricted pattern of expression in the mammalian brain. Their localization in the nucleus accumbens core and shell is of particular interest because of their association with the rewarding properties of drugs of abuse. Using background subtracted fast scan cyclic voltammetry, we investigated the effects of dopamine D2 and D3 agonists on electrically stimulated dopamine release and uptake rates in the mouse caudate putamen and nucleus accumbens core and shell. The dopamine D2 agonists (−)-quinpirole hydrochloride and 5,6,7,8-tetrahydro-6-(2-propen-1-yl)-4H-thiazolo[4,5-d]azepin-2-amine dihydrochloride (B-HT 920) had the same dopamine release inhibition effects on caudate putamen and nucleus accumbens (core and shell) on the basis of their EC50 values and efficacies. This suggests that the dopamine D2 autoreceptor functionality is comparable in all three striatal regions investigated. The dopamine D3 agonists (4aR,10bR)-3,4a,4,10b-tetrahydro-4-propyl-2H,5H-[1]benzopyrano-[4,3-b]-1,4-oxazin-9-ol hydrochloride ((+)-PD 128907) and (±)-7-Hydroxy-2-dipropylaminotetralin hydrobromide (7-OH-DPAT) had a significantly greater effect on dopamine release inhibition in the nucleus accumbens shell than in the caudate putamen. This study confirms that, the dopamine D3 autoreceptor functionality is greater in the nucleus accumbens shell followed by the nucleus accumbens core, with the caudate putamen having the least. Neither dopamine D2 nor D3 agonists affected the uptake rates in nucleus accumbens but concentrations greater than 0.1 μM lowered the uptake rate in caudate putamen. To validate our method of evaluating dopamine D2 and D3 autoreceptors, sulpiride (D2 antagonist) and nafadotride (D3 antagonist) were used to reverse the effects of the dopamine agonists to approximately 100% of the preagonist

  16. Dopamine controls neurogenesis in the adult salamander midbrain in homeostasis and during regeneration of dopamine neurons.

    PubMed

    Berg, Daniel A; Kirkham, Matthew; Wang, Heng; Frisén, Jonas; Simon, András

    2011-04-08

    Appropriate termination of regenerative processes is critical for producing the correct number of cells in tissues. Here we provide evidence for an end-product inhibition of dopamine neuron regeneration that is mediated by dopamine. Ablation of midbrain dopamine neurons leads to complete regeneration in salamanders. Regeneration involves extensive neurogenesis and requires activation of quiescent ependymoglia cells, which express dopamine receptors. Pharmacological compensation for dopamine loss by L-dopa inhibits ependymoglia proliferation and regeneration in a dopamine receptor-signaling-dependent manner, specifically after ablation of dopamine neurons. Systemic administration of the dopamine receptor antagonist haloperidol alone causes ependymoglia proliferation and the appearance of excessive number of neurons. Our data show that stem cell quiescence is under dopamine control and provide a model for termination once normal homeostasis is restored. The findings establish a role for dopamine in the reversible suppression of neurogenesis in the midbrain and have implications for regenerative strategies in Parkinson's disease.

  17. Intrahippocampal Infusions of Anisomycin Produce Amnesia: Contribution of Increased Release of Norepinephrine, Dopamine, and Acetylcholine

    ERIC Educational Resources Information Center

    Qi, Zhenghan; Gold, Paul E.

    2009-01-01

    Intra-amygdala injections of anisomycin produce large increases in the release of norepinephrine (NE), dopamine (DA), and serotonin in the amygdala. Pretreatment with intra-amygdala injections of the beta-adrenergic receptor antagonist propranolol attenuates anisomycin-induced amnesia without reversing the inhibition of protein synthesis, and…

  18. Pharmacologic inhibition of L-tyrosine degradation ameliorates cerebral dopamine deficiency in murine phenylketonuria (PKU)

    PubMed Central

    Harding, Cary O.; Winn, Shelley R.; Gibson, K. Michael; Arning, Erland; Bottiglieri, Teodoro; Grompe, Markus

    2014-01-01

    Summary Monoamine neurotransmitter deficiency has been implicated in the etiology of neuropsychiatric symptoms associated with chronic hyperphenylalaninemia in phenylketonuria (PKU). Two proposed explanations for neurotransmitter deficiency in PKU include first, that chronically elevated blood L-phenylalanine (Phe) inhibits the transport of L-tyrosine (Tyr) and L-tryptophan (Trp), the substrates for dopamine and serotonin synthesis respectively, into brain. In the second hypothesis, elevated Phe competitively inhibits brain tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH) activities, the rate limiting steps in dopamine and serotonin synthesis. Dietary supplementation with large neutral amino acids (LNAA) including Tyr and Trp has been recommended for individuals with chronically elevated blood Phe in an attempt to restore amino acid and monoamine homeostasis in brain. As a potential alternative treatment approach, we demonstrate that pharmacologic inhibition of Tyr degradation through oral administration of nitisinone (NTBC) yielded sustained increases in blood and brain Tyr, decreased blood and brain Phe, and consequently increased dopamine synthesis in a murine model of PKU. Our results suggest that Phe-mediated inhibition of TH activity is the likely mechanism of impaired dopamine synthesis in PKU. Pharmacologic inhibition of Tyr degradation may be a promising adjunct therapy for CNS monoamine neurotransmitter deficiency in hyperphenylalaninemic individuals with PKU. PMID:24487571

  19. Pharmacologic inhibition of L-tyrosine degradation ameliorates cerebral dopamine deficiency in murine phenylketonuria (PKU).

    PubMed

    Harding, Cary O; Winn, Shelley R; Gibson, K Michael; Arning, Erland; Bottiglieri, Teodoro; Grompe, Markus

    2014-09-01

    Monoamine neurotransmitter deficiency has been implicated in the etiology of neuropsychiatric symptoms associated with chronic hyperphenylalaninemia in phenylketonuria (PKU). Two proposed explanations for neurotransmitter deficiency in PKU include first, that chronically elevated blood L-phenylalanine (Phe) inhibits the transport of L-tyrosine (Tyr) and L-tryptophan (Trp), the substrates for dopamine and serotonin synthesis respectively, into brain. In the second hypothesis, elevated Phe competitively inhibits brain tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH) activities, the rate limiting steps in dopamine and serotonin synthesis. Dietary supplementation with large neutral amino acids (LNAA) including Tyr and Trp has been recommended for individuals with chronically elevated blood Phe in an attempt to restore amino acid and monoamine homeostasis in brain. As a potential alternative treatment approach, we demonstrate that pharmacologic inhibition of Tyr degradation through oral administration of nitisinone (NTBC) yielded sustained increases in blood and brain Tyr, decreased blood and brain Phe, and consequently increased dopamine synthesis in a murine model of PKU. Our results suggest that Phe-mediated inhibition of TH activity is the likely mechanism of impaired dopamine synthesis in PKU. Pharmacologic inhibition of Tyr degradation may be a promising adjunct therapy for CNS monoamine neurotransmitter deficiency in hyperphenylalaninemic individuals with PKU.

  20. Intrahippocampal Infusions of Anisomycin Produce Amnesia: Contribution of Increased Release of Norepinephrine, Dopamine, and Acetylcholine

    ERIC Educational Resources Information Center

    Qi, Zhenghan; Gold, Paul E.

    2009-01-01

    Intra-amygdala injections of anisomycin produce large increases in the release of norepinephrine (NE), dopamine (DA), and serotonin in the amygdala. Pretreatment with intra-amygdala injections of the beta-adrenergic receptor antagonist propranolol attenuates anisomycin-induced amnesia without reversing the inhibition of protein synthesis, and…

  1. Chaotic behavior in dopamine neurodynamics.

    PubMed Central

    King, R; Barchas, J D; Huberman, B A

    1984-01-01

    We report the results of the dynamics of a model of the central dopaminergic neuronal system. In particular, for certain values of a parameter k, which monitors the efficacy of dopamine at the postsynaptic receptor, chaotic solutions of the dynamical equations appear--a prediction that correlates with the observed increased variability in behavior among schizophrenics, the rapid fluctuations in motor activity among Parkinsonian patients treated chronically with L-dopa, and the lability of mood in some patients with an affective disorder. Moreover our hypothesis offers specific results concerning the appearance or disappearance of erratic solutions as a function of k and the external input to the dopamine neuronal system. PMID:6583705

  2. Chaotic behavior in dopamine neurodynamics.

    PubMed

    King, R; Barchas, J D; Huberman, B A

    1984-02-01

    We report the results of the dynamics of a model of the central dopaminergic neuronal system. In particular, for certain values of a parameter k, which monitors the efficacy of dopamine at the postsynaptic receptor, chaotic solutions of the dynamical equations appear--a prediction that correlates with the observed increased variability in behavior among schizophrenics, the rapid fluctuations in motor activity among Parkinsonian patients treated chronically with L-dopa, and the lability of mood in some patients with an affective disorder. Moreover our hypothesis offers specific results concerning the appearance or disappearance of erratic solutions as a function of k and the external input to the dopamine neuronal system.

  3. Longevity manipulations differentially affect serotonin/dopamine level and behavioral deterioration in aging Caenorhabditis elegans.

    PubMed

    Yin, Jiang-An; Liu, Xi-Juan; Yuan, Jie; Jiang, Jing; Cai, Shi-Qing

    2014-03-12

    Aging is accompanied with behavioral and cognitive decline. Changes in the neurotransmitter level are associated with the age-related behavioral deterioration, but whether well-known longevity manipulations affect the function of neurotransmitter system in aging animals is largely unclear. Here we report that serotonin (5-HT) and dopamine (DA) level decrease with age in C. elegans. The reduction results in downregulation of the activity of neurons controlled by 5-HT/DA signaling, and deterioration of some important behaviors, including pharyngeal pumping, food-induced slowing responses, and male mating. Longevity manipulations differentially affect the age-related decline in neuronal level of 5-HT/DA. The reduction and resultant behavioral deterioration occur in long-lived worms with defective insulin signaling [daf-2(e1370), age-1(hx546)] or mitochondria function [isp-1(qm150), tpk-1(qm162)], but not in long-lived worms with dietary restriction eat-2(ad1116). A reduced expression level of dopa decarboxylase BAS-1, the shared enzyme for 5-HT/DA synthesis, is responsible for the decline in 5-HT/DA levels. RNAi assay revealed that the sustained 5-HT/DA level in neurons of aged eat-2(ad1116) worms requires PHA-4 and its effectors superoxide dismutases and catalases, suggesting the involvement of reactive oxygen species in the 5-HT/DA decline. Furthermore, we found that elevating 5-HT/DA ameliorates age-related deterioration of pharyngeal pumping, food-induced slowing responses, and male mating in both wild-type and daf-2(e1370) worms. Together, dietary restriction preserves healthy behaviors in aged worms at least partially by sustaining a high 5-HT/DA level, and elevating the 5-HT/DA level in wild-type and daf-2(e1370) worms improves their behaviors during aging.

  4. Protein Kinase C Beta Regulates the D2-Like Dopamine Autoreceptor

    PubMed Central

    Luderman, Kathryn D.; Chen, Rong; Ferris, Mark J.; Jones, Sara R.; Gnegy, Margaret E.

    2014-01-01

    The focus of this study was the regulation of the D2-like dopamine autoreceptor (D2 autoreceptor) by protein kinase Cβ, a member of the protein kinase C (PKC) family. Together with the dopamine transporter, the D2 autoreceptor regulates the level of extracellular dopamine and thus dopaminergic signaling. PKC regulates neuronal signaling via several mechanisms, including desensitizing autoreceptors to increase the release of several different neurotransmitters. Here, using both PKCβ−/− mice and specific PKCβ inhibitors, we demonstrated that a lack of PKCβ activity enhanced the D2 autoreceptor-stimulated decrease in dopamine release following both chemical and electrical stimulations. Inhibition of PKCβ increased surface localization of D2R in mouse striatal synaptosomes, which could underlie the greater sensitivity to quinpirole following inhibition of PKCβ. PKCβ−/− mice displayed greater sensitivity to the quinpirole-induced suppression of locomotor activity, demonstrating that the regulation of the D2 autoreceptor by PKCβ is physiologically significant. Overall, we have found that PKCβ downregulates the D2 autoreceptor, providing an additional layer of regulation for dopaminergic signaling. We propose that in the absence of PKCβ activity, surface D2 autoreceptor localization and thus D2 autoreceptor signaling is increased, leading to less dopamine in the extracellular space and attenuated dopaminergic signaling. PMID:25446677

  5. Early direct and transneuronal effects in mice with targeted expression of a toxin gene to D1 dopamine receptor neurons.

    PubMed

    Padungchaichot, P; Wong, J Y; Natoli, A L; Massalas, J S; Finkelstein, D I; Lawrence, A L; Drago, J

    2000-01-01

    The neurochemical profile was examined at postnatal day 3-4 in mutant mice generated by in vivo Cre mediated activation of an attenuated diphtheria toxin gene inserted into the D1 dopamine receptor gene locus. An earlier study of this model had shown that D1 dopamine receptor, substance P and dynorphin were not expressed in the striatum. Quantitative in situ hybridization analysis showed an increase in D2 dopamine receptor and enkephalin messenger RNA expression. The nigrostriatal pathway in the mutant pups was intact with a normal number of dopaminergic neurons in the substantia nigra and the ventral tegmental area in addition to a normal pattern of striatal dopamine transporter and tyrosine hydroxylase immunoreactivity. Quantitative analysis of striatal dopamine transporter density using [3H]mazindol showed a reduction of 26% suggesting a degree of transneuronal down-regulation. There was also a 49% reduction of striatal GABA receptor binding and a 36% reduction of striatal muscarinic receptor binding in mutant pups. The number of healthy striatal neuropeptide Y-containing interneurons was also substantially down-regulated in the mutant striatum. In contrast, there was an increase in the number of striatal cholinergic interneurons. Down-regulated cortical GABA receptor and muscarinic receptor binding was also observed in addition to subtle morphological changes in the neuropeptide Y-expressing population of cortical neurons. The changes reflect the early cascade of events which follows the ablation of D1 dopamine receptor-positive cells. Although extensive changes in a number of striatal and cortical neurons were demonstrated, only subtle transneuronal effects were seen in the nigrostriatal pathway.

  6. Interactions between glutamate, dopamine, and the neuronal signature of response inhibition in the human striatum.

    PubMed

    Lorenz, Robert C; Gleich, Tobias; Buchert, Ralph; Schlagenhauf, Florian; Kühn, Simone; Gallinat, Jürgen

    2015-10-01

    Response inhibition is a basic mechanism in cognitive control and dysfunctional in major psychiatric disorders. The neuronal mechanisms are in part driven by dopamine in the striatum. Animal data suggest a regulatory role of glutamate on the level of the striatum. We used a trimodal imaging procedure of the human striatum including F18-DOPA positron emission tomography, proton magnetic resonance spectroscopy, and functional magnetic resonance imaging of a stop signal task. We investigated dopamine synthesis capacity and glutamate concentration in vivo and their relation to functional properties of response inhibition. A mediation analysis revealed a significant positive association between dopamine synthesis capacity and inhibition-related neural activity in the caudate nucleus. This relationship was significantly mediated by striatal glutamate concentration. Furthermore, stop signal reaction time was inversely related to striatal activity during inhibition. The data show, for the first time in humans, an interaction between dopamine, glutamate, and the neural signature of response inhibition in the striatum. This finding stresses the importance of the dopamine-glutamate interaction for behavior and may facilitate the understanding of psychiatric disorders characterized by impaired response inhibition.

  7. Regulation of dopamine quantal size in midbrain and hippocampal neurons.

    PubMed

    Pothos, Emmanuel N

    2002-03-10

    Since the pioneering work of Bernard Katz and his colleagues decades ago, neurotransmitter quantal size (defined as the number of neurotransmitter molecules released by a single synaptic vesicle during exocytosis) is often modeled as invariant. This assumption had tremendous implications for basic research on synaptic plasticity. For instance, it focused attention on the postsynaptic rather than the presynaptic component in studies of learning and memory (the field of long-term potentiation comes to mind as the best example). Furthermore, this assumption somehow 'spilled over' onto studies of monoamine neurotransmitters, which apparently use diffusion and slow action to exert their modulatory effects, in contrast to the fast acting neurotransmitters studied by Katz. Consequently, research on dopamine-related diseases (e.g. psychotic and movement disorders) did not pay as much attention to presynaptic mechanisms that regulate dopamine release, as to postsynaptic receptor action. Part of the problem, of course, has been the lack of technology to directly measure quanta from presynaptic sites and the obligatory reliance on measurements of miniature postsynaptic potentials (minis) for reaching conclusions about presynaptic quantal events. Due to the introduction of the carbon fiber amperometric microelectrode in tissue electrophysiology, initially by Francois Gonon (University of Bordeaux) and then by Mark Wightman (University of North Carolina), we were able to directly measure dopamine quanta from neurites of cultured midbrain dopamine neurons by amperometry. This was the first approach to provide direct measurement of the number of molecules and kinetics of presynaptic quantal release from CNS neuronal terminals. The interventions altering dopamine quantal size are so far the following. (1) Alteration of neurotransmitter synthesis--an increase of cytosolic dopamine availability (e.g. by exposure to L-DOPA) increases quantal size and a decrease of cytosolic dopamine

  8. Psychostimulants affect dopamine transmission through both dopamine transporter-dependent and independent mechanisms.

    PubMed

    dela Peña, Ike; Gevorkiana, Ruzanna; Shi, Wei-Xing

    2015-10-05

    The precise mechanisms by which cocaine and amphetamine-like psychostimulants exert their reinforcing effects are not yet fully defined. It is widely believed, however, that these drugs produce their effects by enhancing dopamine neurotransmission in the brain, especially in limbic areas such as the nucleus accumbens, by inducing dopamine transporter-mediated reverse transport and/or blocking dopamine reuptake though the dopamine transporter. Here, we present the evidence that aside from dopamine transporter, non-dopamine transporter-mediated mechanisms also participate in psychostimulant-induced dopamine release and contribute to the behavioral effects of these drugs, such as locomotor activation and reward. Accordingly, psychostimulants could increase norepinephrine release in the prefrontal cortex, the latter then alters the firing pattern of dopamine neurons resulting in changes in action potential-dependent dopamine release. These alterations would further affect the temporal pattern of dopamine release in the nucleus accumbens, thereby modifying information processing in that area. Hence, a synaptic input to a nucleus accumbens neuron may be enhanced or inhibited by dopamine depending on its temporal relationship to dopamine release. Specific temporal patterns of dopamine release may also be required for certain forms of synaptic plasticity in the nucleus accumbens. Together, these effects induced by psychostimulants, mediated through a non-dopamine transporter-mediated mechanism involving norepinephrine and the prefrontal cortex, may also contribute importantly to the reinforcing properties of these drugs.

  9. Psychostimulants affect dopamine transmission through both dopamine transporter-dependent and independent mechanisms

    PubMed Central

    dela Peña, Ike; Gevorkiana, Ruzanna; Shi, Wei-Xing

    2015-01-01

    The precise mechanisms by which cocaine and amphetamine-like psychostimulants exert their reinforcing effects are not yet fully defined. It is widely believed, however, that these drugs produce their effects by enhancing dopamine neurotransmission in the brain, especially in limbic areas such as the nucleus accumbens, by inducing dopamine transporter-mediated reverse transport and/or blocking dopamine reuptake though the dopamine transporter. Here, we present the evidence that aside from dopamine transporter, non-dopamine transporter-mediated mechanisms also participate in psychostimulant-induced dopamine release and contribute to the behavioral effects of these drugs, such as locomotor activation and reward. Accordingly, psychostimulants could increase norepinephrine release in the prefrontal cortex, the latter then alters the firing pattern of dopamine neurons resulting in changes in action potential-dependent dopamine release. These alterations would further affect the temporal pattern of dopamine release in the nucleus accumbens, thereby modifying information processing in that area. Hence, a synaptic input to a nucleus accumbens neuron may be enhanced or inhibited by dopamine depending on its temporal relationship to dopamine release. Specific temporal patterns of dopamine release may also be required for certain forms of synaptic plasticity in the nucleus accumbens. Together, these effects induced by psychostimulants, mediated through a non-dopamine transporter-mediated mechanism involving norepinephrine and the prefrontal cortex, may also contribute importantly to the reinforcing properties of these drugs. PMID:26209364

  10. Chronic Nicotine Mitigates Aberrant Inhibitory Motor Learning Induced by Motor Experience under Dopamine Deficiency.

    PubMed

    Koranda, Jessica L; Krok, Anne C; Xu, Jian; Contractor, Anis; McGehee, Daniel S; Beeler, Jeff A; Zhuang, Xiaoxi

    2016-05-11

    Although dopamine receptor antagonism has long been associated with impairments in motor performance, more recent studies have shown that dopamine D2 receptor (D2R) antagonism, paired with a motor task, not only impairs motor performance concomitant with the pharmacodynamics of the drug, but also impairs future motor performance once antagonism has been relieved. We have termed this phenomenon "aberrant motor learning" and have suggested that it may contribute to motor symptoms in movement disorders such as Parkinson's disease (PD). Here, we show that chronic nicotine (cNIC), but not acute nicotine, treatment mitigates the acquisition of D2R-antagonist-induced aberrant motor learning in mice. Although cNIC mitigates D2R-mediated aberrant motor learning, cNIC has no effect on D1R-mediated motor learning. β2-containing nicotinic receptors in dopamine neurons likely mediate the protective effect of cNIC against aberrant motor learning, because selective deletion of β2 nicotinic subunits in dopamine neurons reduced D2R-mediated aberrant motor learning. Finally, both cNIC treatment and β2 subunit deletion blunted postsynaptic responses to D2R antagonism. These results suggest that a chronic decrease in function or a downregulation of β2-containing nicotinic receptors protects the striatal network against aberrant plasticity and aberrant motor learning induced by motor experience under dopamine deficiency. Increasingly, aberrant plasticity and aberrant learning are recognized as contributing to the development and progression of movement disorders. Here, we show that chronic nicotine (cNIC) treatment or specific deletion of β2 nicotinic receptor subunits in dopamine neurons mitigates aberrant motor learning induced by dopamine D2 receptor (D2R) blockade in mice. Moreover, both manipulations also reduced striatal dopamine release and blunt postsynaptic responses to D2R antagonists. These results suggest that chronic downregulation of function and/or receptor

  11. Acute and sustained effects of methylphenidate on cognition and presynaptic dopamine metabolism: an [18F]FDOPA PET study.

    PubMed

    Schabram, Ina; Henkel, Karsten; Mohammadkhani Shali, Siamak; Dietrich, Claudia; Schmaljohann, Jörn; Winz, Oliver; Prinz, Susanne; Rademacher, Lena; Neumaier, Bernd; Felzen, Marc; Kumakura, Yoshitaka; Cumming, Paul; Mottaghy, Felix M; Gründer, Gerhard; Vernaleken, Ingo

    2014-10-29

    Methylphenidate (MPH) inhibits the reuptake of dopamine and noradrenaline. PET studies with MPH challenge show increased competition at postsynaptic D2/3-receptors, thus indirectly revealing presynaptic dopamine release. We used [(18)F]fluorodopamine ([(18)F]FDOPA)-PET in conjunction with the inlet-outlet model (IOM) of Kumakura et al. (2007) to investigate acute and long-term changes in dopamine synthesis capacity and turnover in nigrostriatal fibers of healthy subjects with MPH challenge. Twenty healthy human females underwent two dynamic [(18)F]FDOPA PET scans (124 min; slow bolus-injection; arterial blood sampling), with one scan in untreated baseline condition and the other after MPH administration (0.5 mg/kg, p.o.), in randomized order. Subjects underwent cognitive testing at each PET session. Time activity curves were obtained for ventral putamen and caudate and were analyzed according to the IOM to obtain the regional net-uptake of [(18)F]FDOPA (K; dopamine synthesis capacity) as well as the [(18)F]fluorodopamine washout rate (kloss, index of dopamine turnover). MPH substantially decreased kloss in putamen (-22%; p = 0.003). In the reversed treatment order group (MPH/no drug), K was increased by 18% at no drug follow-up. The magnitude of K at the no drug baseline correlated with cognitive parameters. Furthermore, individual kloss changes correlated with altered cognitive performance under MPH. [(18)F]FDOPA PET in combination with the IOM detects an MPH-evoked decrease in striatal dopamine turnover, in accordance with the known acute pharmacodynamics of MPH. Furthermore, the scan-ordering effect on K suggested that a single MPH challenge persistently increased striatal dopamine synthesis capacity. Attenuation of dopamine turnover by MPH is linked to enhanced cognitive performance in healthy females.

  12. Dopamine supports coupling of attention-related networks.

    PubMed

    Dang, Linh C; O'Neil, James P; Jagust, William J

    2012-07-11

    Attentional processing has been associated with the dorsal attention, default mode, and frontoparietal control networks. The dorsal attention network is involved in externally focused attention whereas the default mode network is involved in internally directed attention. The frontoparietal control network has been proposed to mediate the transition between external and internal attention by coupling its activity to either the dorsal attention network or the default mode network, depending on the attentional demand. Dopamine is hypothesized to modulate attention and has been linked to the integrity of these three attention-related networks. We used PET with 6-[(18)F]fluoro-L-m-tyrosine to quantify dopamine synthesis capacity in vivo and fMRI to acquire stimulus-independent brain activity in cognitively healthy human subjects. We found that in the resting state where internal cognition dominates, dopamine enhances the coupling between the frontoparietal control network and the default mode network while reducing the coupling between the frontoparietal control network and the dorsal attention network. These results add a neurochemical perspective to the role of network interaction in modulating attention.

  13. Discovery of cariprazine (RGH-188): a novel antipsychotic acting on dopamine D3/D2 receptors.

    PubMed

    Agai-Csongor, Eva; Domány, György; Nógrádi, Katalin; Galambos, János; Vágó, István; Keserű, György Miklós; Greiner, István; Laszlovszky, István; Gere, Anikó; Schmidt, Eva; Kiss, Béla; Vastag, Mónika; Tihanyi, Károly; Sághy, Katalin; Laszy, Judit; Gyertyán, István; Zájer-Balázs, Mária; Gémesi, Larisza; Kapás, Margit; Szombathelyi, Zsolt

    2012-05-15

    Medicinal chemistry optimization of an impurity isolated during the scale-up synthesis of a pyridylsulfonamide type dopamine D(3)/D(2) compound (1) led to a series of new piperazine derivatives having affinity to both dopamine D(3) and D(2) receptors. Several members of this group showed excellent pharmacokinetic and pharmacodynamic properties as demonstrated by outstanding activities in different antipsychotic tests. The most promising representative, 2m (cariprazine) had good absorption, excellent brain penetration and advantageous safety profile. Based on its successful clinical development we are looking forward to the NDA filing of cariprazine in 2012. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Increased brain dopamine and dopamine receptors in schizophrenia

    SciTech Connect

    Mackay, A.V.; Iversen, L.L.; Rossor, M.; Spokes, E.; Bird, E.; Arregui, A.; Creese, I.; Synder, S.H.

    1982-09-01

    In postmortem samples of caudate nucleus and nucleus accumbens from 48 schizophrenic patients, there were significant increases in both the maximum number of binding sites (Bmax) and the apparent dissociation constant (KD) for tritiated spiperone. The increase in apparent KD probably reflects the presence of residual neuroleptic drugs, but changes in Bmax for tritiated spiperone reflect genuine changes in receptor numbers. The increases in receptors were seen only in patients in whom neuroleptic medication had been maintained until the time of death, indicating that they may be entirely iatrogenic. Dopamine measurements for a larger series of schizophrenic and control cases (n greater than 60) show significantly increased concentrations in both the nucleus accumbens and caudate nucleus. The changes in dopamine were not obviously related to neuroleptic medication and, unlike the receptor changes, were most severe in younger patients.

  15. Rapid determination of dopamine in human plasma using a gold nanoparticle-based dual-mode sensing system.

    PubMed

    Zhang, Yali; Qi, Suijian; Liu, Zhonggang; Shi, Yupeng; Yue, Wanqing; Yi, Changqing

    2016-04-01

    Dopamine plays a very important role in biological systems and has a direct relationship with the ability of learning and cognition, human desires, feelings and mental state, as well as motor functions. Traditional methods for the detection of dopamine are complicated and time-consuming, therefore it is necessary to explore rapid and accurate detection of dopamine with high sensitivity and specificity. Herein we report a dual-mode system of colorimetric and fluorometric analyses based on gold nanoparticles (AuNPs) and aptamers specifically targeting dopamine. Aptamers modified with the fluorophore were used as dopamine specific recognition probe and the sensing mechanism is based on the color change of AuNPs and the fluorescence recovery of fluorophore conjugated on the aptamers in the presence of dopamine. The addition of aptamers into AuNPs colloid solution would prevent the AuNPs from aggregation in the high-salt solution. The close distance between AuNPs and fluorophore conjugated on the aptamers would lead to the quenching of fluorescence signal. In the presence of dopamine, the conformation of the aptamers and the inter-particle distance would be changed, leading to the aggregation of AuNPs, which subsequently results in color change from red to blue and fluorescence signal recovery. The dual-mode sensing system demonstrated high specificity towards dopamine with the detection limit as low as 78.7 nM. The sensing system reflects on its simplicity as no surface functionalization is required for the nanoparticles, leading to less laborious and more cost-effective synthesis. The reaction time is only 6 min, demonstrating a simple approach for rapid analysis of dopamine. More importantly, the sensing system allows the detection of dopamine in both aqueous solution and complicated biological sample with sensitive response, illustrating the feasibility and reliability for the potential applications in clinical and biomedical analysis in the future.

  16. Antiferroptotic activity of non-oxidative dopamine.

    PubMed

    Wang, Ding; Peng, Yingpeng; Xie, Yangchun; Zhou, Borong; Sun, Xiaofang; Kang, Rui; Tang, Daolin

    2016-11-25

    Dopamine is a neurotransmitter that has many functions in the nervous and immune systems. Ferroptosis is a non-apoptotic form of regulated cell death that is involved in cancer and neurodegenerative diseases. However, the role of dopamine in ferroptosis remains unidentified. Here, we show that the non-oxidative form of dopamine is a strong inhibitor of ferroptotic cell death. Dopamine dose-dependently blocked ferroptosis in cancer (PANC1 and HEY) and non-cancer (MEF and HEK293) cells following treatment with erastin, a small molecule ferroptosis inducer. Notably, dopamine reduced erastin-induced ferrous iron accumulation, glutathione depletion, and malondialdehyde production. Mechanically, dopamine increased the protein stability of glutathione peroxidase 4, a phospholipid hydroperoxidase that protects cells against membrane lipid peroxidation. Moreover, dopamine suppressed dopamine receptor D4 protein degradation and promoted dopamine receptor D5 gene expression. Thus, our findings uncover a novel function of dopamine in cell death and provide new insight into the regulation of iron metabolism and lipid peroxidation by neurotransmitters.

  17. Dopamine agonists for cocaine dependence.

    PubMed

    Soares, B G; Lima, M S; Reisser, A A; Farrell, M

    2001-01-01

    Cocaine is a major drug of abuse. Cocaine dependence is a common and serious condition, which has become nowadays a substantial public health problem. There is a wide and well documented range of consequences associated to chronic use of this drug, such as medical, psychological and social problems, including the spread of infectious diseases (e.g. AIDS, hepatitis and tuberculosis), crime, violence and neonatal drug exposure. Therapeutic management of the cocaine addicts includes an initial period of abstinence from the drug. During this phase the subjects may experience, besides the intense craving for cocaine, symptoms such as depression, fatigue, irritability, anorexia, and sleep disturbances. It was demonstrated that the acute use of cocaine may enhance dopamine transmission and chronically it decreases dopamine concentrations in the brain. Pharmacological treatment that affects dopamine could theoretically reduce these symptoms and contribute to a more successful therapeutic approach. To evaluate the efficacy and acceptability of dopamine agonists for treating cocaine dependence. We searched: The Cochrane Controlled Trials Register (Cochrane Library, issue 4, 2000), MEDLINE (from 1966 - 2000), EMBASE (from 1980 - 2000), LILACS (from 1982 - 2000), PsycLIT (from 1974 - 2000), Biological Abstracts (1982 to 2000). Reference searching; personal communication; conference abstracts; unpublished trials from pharmaceutical industry; book chapters on treatment of cocaine dependence. The inclusion criteria for all randomised controlled trials were that they should focus on the use of dopamine agonists on the treatment of cocaine dependence. Trials including patients with additional diagnosis such as opiate dependence were also eligible. The reviewers extracted the data independently and Relative Risks, weighted mean difference and number needed to treat were estimated. The reviewers assumed that people who died or dropped out had no improvement and tested the sensitivity

  18. Dopamine agonists for cocaine dependence.

    PubMed

    Soares, B G O; Lima, M S; Reisser, A A P; Farrell, M

    2003-01-01

    Cocaine dependence is a common and serious condition, which has become nowadays a substantial public health problem. There is a wide and well documented range of consequences associated to chronic use of this drug, such as medical, psychological and social problems, including the spread of infectious diseases (e.g. AIDS, hepatitis and tuberculosis), crime, violence and neonatal drug exposure. Therapeutic management of the cocaine addicts includes an initial period of abstinence from the drug. During this phase the subjects may experience, besides the intense craving for cocaine, symptoms such as depression, fatigue, irritability, anorexia, and sleep disturbances. It was demonstrated that the acute use of cocaine may enhance dopamine transmission and chronically it decreases dopamine concentrations in the brain. Pharmacological treatment that affects dopamine could theoretically reduce these symptoms and contribute to a more successful therapeutic approach. To evaluate the efficacy and acceptability of dopamine agonists for treating cocaine dependence. Electronic searches of Cochrane Library, EMBASE, MEDLINE, PsycLIT, Biological Abstracts and LILACS; reference searching; personal communication; conference abstracts; unpublished trials from pharmaceutical industry; book chapters on treatment of cocaine dependence, was performed for the primary version of this review in 2001. Another search of the electronic databases was done in December of 2002 for this update. The specialised register of trials of the Cochrane Group on Drugs and Alcohol was searched until February 2003. The inclusion criteria for all randomised controlled trials were that they should focus on the use of dopamine agonists on the treatment of cocaine dependence. The reviewers extracted the data independently and Relative Risks, weighted mean difference and number needed to treat were estimated. The reviewers assumed that people who died or dropped out had no improvement and tested the sensitivity of

  19. The biosynthesis of N-arachidonoyl dopamine (NADA), a putative endocannabinoid and endovanilloid, via conjugation of arachidonic acid with dopamine

    PubMed Central

    Hu, Sherry Shu-Jung; Bradshaw, Heather B.; Benton, Valery M.; Chen, Jay Shih-Chieh; Huang, Susan M.; Minassi, Alberto; Bisogno, Tiziana; Masuda, Kim; Tan, Bo; Roskoski, Robert; Cravatt, Benjamin F.; Di Marzo, Vincenzo

    2009-01-01

    Summary N-arachidonoyl dopamine (NADA) is an endogenous ligand that activates the cannabinoid type 1 receptor and the transient receptor potential vanilloid type 1 channel. Two potential biosynthetic pathways for NADA have been proposed, though no conclusive evidence exists for either. The first is the direct conjugation of arachidonic acid with dopamine; the other is via metabolism of a putative N-arachidonoyl tyrosine (NA-tyrosine). In the present study we investigated these biosynthetic mechanisms and report that NADA synthesis requires TH in dopaminergic terminals, however, NA-tyrosine, which we identify here as an endogenous lipid, is not an intermediate. We show that NADA biosynthesis primarily occurs through an enzyme-mediated conjugation of arachidonic acid with dopamine. While this conjugation likely involves a complex of enzymes, our data suggest a direct involvement of fatty acid amide hydrolase in NADA biosynthesis as either a rate-limiting enzyme that liberates arachidonic acid from AEA, as a conjugation enzyme, or both. PMID:19570666

  20. The biosynthesis of N-arachidonoyl dopamine (NADA), a putative endocannabinoid and endovanilloid, via conjugation of arachidonic acid with dopamine.

    PubMed

    Hu, Sherry Shu-Jung; Bradshaw, Heather B; Benton, Valery M; Chen, Jay Shih-Chieh; Huang, Susan M; Minassi, Alberto; Bisogno, Tiziana; Masuda, Kim; Tan, Bo; Roskoski, Robert; Cravatt, Benjamin F; Di Marzo, Vincenzo; Walker, J Michael

    2009-10-01

    N-arachidonoyl dopamine (NADA) is an endogenous ligand that activates the cannabinoid type 1 receptor and the transient receptor potential vanilloid type 1 channel. Two potential biosynthetic pathways for NADA have been proposed, though no conclusive evidence exists for either. The first is the direct conjugation of arachidonic acid with dopamine and the other is via metabolism of a putative N-arachidonoyl tyrosine (NA-tyrosine). In the present study we investigated these biosynthetic mechanisms and report that NADA synthesis requires TH in dopaminergic terminals; however, NA-tyrosine, which we identify here as an endogenous lipid, is not an intermediate. We show that NADA biosynthesis primarily occurs through an enzyme-mediated conjugation of arachidonic acid with dopamine. While this conjugation likely involves a complex of enzymes, our data suggest a direct involvement of fatty acid amide hydrolase in NADA biosynthesis either as a rate-limiting enzyme that liberates arachidonic acid from AEA, or as a conjugation enzyme, or both.

  1. L-DOPA inhibits depolarization-induced [3H]GABA release in the dopamine-denervated globus pallidus of the rat: the effect is dopamine independent and mediated by D2-like receptors.

    PubMed

    Silva, I; Cortes, H; Escartín, E; Rangel, C; Florán, L; Erlij, D; Aceves, J; Florán, B

    2006-12-01

    The effect of L-DOPA on [(3)H]GABA release in slices of globus pallidus from 6-OHDA-lesioned rats was studied. Release was evoked by high (15 mM) K(+). The lesion reduced dopamine content and dopamine synthesized from L-DOPA. The inhibition of DOPA decarboxylase blocked dopamine synthesis. Endogenous dopamine released by high K(+) inhibited [(3)H]GABA release in normal but not in lesioned slices. L-DOPA inhibited (IC(50) = 0.44 microM) evoked [(3)H]GABA release. The inhibition was via D2-like receptors but not mediated by dopamine. The turning behavior induced by L-DOPA methyl ester (25 mg/kg, i.p.) was not abolished by the DOPA decarboxylase inhibitor 3-hydroxybenzylhydrazine but in this condition it was abolished by sulpiride. Results suggest that L-DOPA acting as D2-like agonist inhibits GABA release in the rat globus pallidus and induces turning behavior in rats with unilateral lesions of the dopamine innervation. L-DOPA could control Parkinson's disease symptoms acting not only as dopamine precursor but also by itself.

  2. Dopamine modulation of transient receptor potential vanilloid type 1 (TRPV1) receptor in dorsal root ganglia neurons

    PubMed Central

    Chakraborty, Saikat; Rebecchi, Mario; Kaczocha, Martin

    2016-01-01

    Key points Transient receptor potential vanilloid type 1 (TRPV1) receptors transduce noxious thermal stimuli and are responsible for the thermal hyperalgesia associated with inflammatory pain.A large population of dorsal root ganglia (DRG) neurons, including the C low threshold mechanoreceptors (C‐LTMRs), express tyrosine hydroxylase, and probably release dopamine.We found that dopamine and SKF 81297 (an agonist at D1/D5 receptors), but not quinpirole (an agonist at D2 receptors), downregulate the activity of TRPV1 channels in DRG neurons.The inhibitory effect of SKF 81297 on TRPV1 channels was strongly dependent on external calcium and preferentially linked to calcium–calmodulin‐dependent protein kinase II (CaMKII).We suggest that modulation of TRPV1 channels by dopamine in nociceptive neurons may represent a way for dopamine to modulate incoming noxious stimuli. Abstract The transient receptor potential vanilloid type 1 (TRPV1) receptor plays a key role in the modulation of nociceptor excitability. To address whether dopamine can modulate the activity of TRPV1 channels in nociceptive neurons, the effects of dopamine and dopamine receptor agonists were tested on the capsaicin‐activated current recorded from acutely dissociated small diameter (<27 μm) dorsal root ganglia (DRG) neurons. Dopamine or SKF 81297 (an agonist at D1/D5 receptors), caused inhibition of both inward and outward currents by ∼60% and ∼48%, respectively. The effect of SKF 81297 was reversed by SCH 23390 (an antagonist at D1/D5 receptors), confirming that it was mediated by activation of D1/D5 dopamine receptors. In contrast, quinpirole (an agonist at D2 receptors) had no significant effect on the capsaicin‐activated current. Inhibition of the capsaicin‐activated current by SKF 81297 was mediated by G protein coupled receptors (GPCRs), and highly dependent on external calcium. The inhibitory effect of SKF 81297 on the capsaicin‐activated current was not affected when

  3. PRESYNAPTIC DOPAMINE MODULATION BY STIMULANT SELF ADMINISTRATION

    PubMed Central

    España, Rodrigo A.; Jones, Sara R.

    2013-01-01

    The mesolimbic dopamine system is an essential participant in the initiation and modulation of various forms of goal-directed behavior, including drug reinforcement and addiction processes. Dopamine neurotransmission is increased by acute administration of all drugs of abuse, including the stimulants cocaine and amphetamine. Chronic exposure to these drugs via voluntary self-administration provides a model of stimulant abuse that is useful in evaluating potential behavioral and neurochemical adaptations that occur during addiction. This review describes commonly used methodologies to measure dopamine and baseline parameters of presynaptic dopamine regulation, including exocytotic release and reuptake through the dopamine transporter in the nucleus accumbens core, as well as dramatic adaptations in dopamine neurotransmission and drug sensitivity that occur with acute non-contingent and chronic, contingent self-administration of cocaine and amphetamine. PMID:23277050

  4. Pathway-Specific Dopamine Abnormalities in Schizophrenia.

    PubMed

    Weinstein, Jodi J; Chohan, Muhammad O; Slifstein, Mark; Kegeles, Lawrence S; Moore, Holly; Abi-Dargham, Anissa

    2017-01-01

    In light of the clinical evidence implicating dopamine in schizophrenia and the prominent hypotheses put forth regarding alterations in dopaminergic transmission in this disease, molecular imaging has been used to examine multiple aspects of the dopaminergic system. We review the imaging methods used and compare the findings across the different molecular targets. Findings have converged to suggest early dysregulation in the striatum, especially in the rostral caudate, manifesting as excess synthesis and release. Recent data showed deficit extending to most cortical regions and even to other extrastriatal subcortical regions not previously considered to be "hypodopaminergic" in schizophrenia. These findings yield a new topography for the dopaminergic dysregulation in schizophrenia. We discuss the dopaminergic innervation within the individual projection fields to provide a topographical map of this dual dysregulation and explore potential cellular and circuit-based mechanisms for brain region-dependent alterations in dopaminergic parameters. This refined knowledge is essential to better guide translational studies and efforts in early drug development. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  5. Identification of an intronic cis-acting element in the human dopamine transporter gene

    PubMed Central

    Zhao, Ying; Zhou, Yanhong; Lin, Zhicheng

    2017-01-01

    The human dopamine transporter gene (hDAT) encodes the dopamine transporter in dopamine (DA) neurons to regulate DA transmission. hDAT expression varies significantly from neuron to neuron, and from individual to individual so that dysregulation of hDAT is related to many neuropsychiatric disorders. It is critical to identify hDAT-specific cis-acting elements that regulate the hDAT expression. Previous studies showed that hDAT Intron 1 displayed inhibitory activity for reporter gene expression. Here we report that the hDAT Intron 1 contains a 121-bp fragment that down-regulated both SV40 and hDAT promoter activities by 80% in vitro. Subfragments of 121-bp still down-regulated the SV40 promoter but not the hDAT promoter, as supported by nuclear protein-binding activities. Collectively, 121-bp is a silencer in vitro that might coordinate with transcriptional activities both inside and outside 121-bp in regulation of hDAT. PMID:22160470

  6. Synthesis and characterization of dopamine substitue tripodal trinuclear [(salen/salophen/salpropen)M] (Mdbnd Cr(III), Mn(III), Fe(III) ions) capped s-triazine complexes: Investigation of their thermal and magnetic properties

    NASA Astrophysics Data System (ADS)

    Uysal, Şaban; Koç, Ziya Erdem

    2016-04-01

    In this work, we aimed to synthesize and characterize a novel tridirectional ligand including three catechol groups and its novel tridirectional-trinuclear triazine core complexes. For this purpose, we used melamine (2,4,6-triamino-1,3,5-triazine) (MA) as starting material. 2,4,6-tris(4-carboxybenzimino)-1,3,5-triazine (II) was synthesized by the reaction of an equivalent melamine (I) and three equivalent 4-carboxybenzaldehyde. 4,4‧,4″-((1E,1‧E,1″E)-((1,3,5-triazine-2,4,6-triyl)tris(azanylylidene))tris(methanylylidene))tris(N-(3,4-dihydroxyphenethyl)benzamide) L (IV) was synthesized by the reaction of one equivalent (II) and three equivalent dopamine (3,4-dihydroxyphenethylamine) (DA) by using two different methods. (II, III, IV) and nine novel trinuclear Cr(III), Mn(III) and Fe(III) complexes of (IV) were characterized by means of elemental analyses, 1H NMR, FT-IR spectrometry, LC-MS (ESI+) and thermal analyses. The metal ratios of the prepared complexes were performed using Atomic Absorption Spectrophotometry (AAS). We also synthesized novel tridirectional-trinuclear systems and investigated their effects on magnetic behaviors of [salen, salophen, salpropen Cr(III)/Mn(III)/Fe(III)] capped complexes. The complexes were determined to be low-spin distorted octahedral Mn(III) and Fe(III), and distorted octahedral Cr(III) all bridged by catechol group.

  7. Lipopolysaccharide mitagates methamphetamine-induced striatal dopamine depletion via modulating local TNF-alpha and dopamine transporter expression.

    PubMed

    Lai, Yu-Ting; Tsai, Yen-Ping N; Cherng, Chianfang G; Ke, Jing-Jer; Ho, Ming-Che; Tsai, Chia-Wen; Yu, Lung

    2009-04-01

    Systemic lipopolysaccharide (LPS) treatment may affect methamphetamine (MA)-induced nigrostriatal dopamine (DA) depletion. This study was undertaken to determine the critical time window for the protective effects of LPS treatment and the underlying mechanisms. An LPS injection (1 mg/kg) 72 h before or 2 h after MA treatment [three consecutive, subcutaneous injections of MA (10 mg/kg each) at 2-h intervals] diminished the MA-induced DA depletion in mouse striatum. Such an LPS-associated effect was independent of MA-produced hyperthermia. TNF-alpha, IL-1beta, IL-6 expressions were all elevated in striatal tissues following a systemic injection with LPS, indicating that peripheral LPS treatment affected striatal pro-inflammatory cytokine expression. Striatal TNF-alpha expression was dramatically increased at 72 and 96 h after the MA treatment, while such TNF-alpha elevation was abolished by the LPS pretreatment protocol. Moreover, MA-produced activation of nuclear NFkappaB, a transcription factor following TNF-alpha activation, in striatum was abolished by the LPS (1 mg/kg) pretreatment. Furthermore, thalidomide, a TNF-alpha antagonist, treatment abolished the LPS pretreatment-associated protective effects. Pretreatment with mouse recombinant TNF-alpha in striatum diminished the MA-produced DA depletion. Finally, single LPS treatment caused a rapid down-regulation of dopamine transporter (DAT) in striatum. Taken together, we conclude that peripheral LPS treatment protects nigrostriatal DA neurons against MA-induced toxicity, in part, by reversing elevated TNF-alpha expression and subsequent signaling cascade and causing a rapid DAT down-regulation in striatum.

  8. Methylphenidate elevates resting dopamine which lowers the impulse-triggered release of dopamine: a hypothesis.

    PubMed

    Seeman, Philip; Madras, Bertha

    2002-03-10

    How do 'stimulants' reduce hyperactivity in children and adults? How can drugs which raise extracellular dopamine result in psychomotor slowing of hyperactive children when dopamine is known to enhance motor activity, such as in Parkinson's disease? In summary, the hypothesis for the anti-hyperactivity effects of the stimulants is as follows: during normal nerve activity, extracellular dopamine levels transiently rise 60-fold. At low therapeutic doses (0.2-0.5 mg/kg) to treat attention-deficit hyperactivity disorder, stimulant drugs such as methylphenidate and dextroamphetamine reduce locomotion in both humans and animals. The drugs raise resting extracellular levels of dopamine several-fold, but reduce the extent to which dopamine is released with nerve impulses, compared to the impulse-associated release in the absence of the drug. This relatively reduced amplitude of impulse-associated dopamine would result in less activation of post-synaptic dopamine receptors which drive psychomotor activity. At higher doses, stimulants produce generalized stimulation of the nervous system, as a result of the very high concentrations of extracellular dopamine at rest, and the markedly increased release of dopamine with nerve impulses. These high levels of resting and pulsatile dopamine cause widespread stimulation of post-synaptic dopamine receptors, overcoming any concomitant presynaptic inhibition of dopamine release.

  9. Metabolism of /sup 3/H-dopamine by human chorioamnion in vitro

    SciTech Connect

    Phillippe, M.; Niloff, J.M.

    1982-08-01

    Previous investigation has demonstrated biologically significant concentrations of catecholamines in amniotic fluid, which increase with gestation. The half life, metabolic clearance rate, and metabolic fate of these hormones in the amniotic compartment are yet to be established. This study was undertaken to demonstrate the ability of human chorioamnion to metabolize dopamine in vitro. Incubation experiments demonstrated that /sup 3/H-dopamine is rapidly metabolized to dihydroxyphenylacetic acid, 3-methoxy, 4-hydroxyphenylacetic acid, and 3-methoxy, 4-hydroxyphenylethanol-all products of monoamine oxidase. No significant 3-methoxytyramine, a catechol-o-methyltransferase product, was observed. Incubation experiments with pargyline, a monoamine oxidase inhibitor, resulted in significant reduction in /sup 3/H-dopamine metabolism. Catecholamines and their interaction with prostaglandin synthesis have been theorized to be a fetal signal for the initiation of parturition. The ability of chorioamnion to metabolize catecholamine could, therefore, provide another control mechanism by which fetal catecholamines are modulated.

  10. Dopamine receptors – IUPHAR Review 13

    PubMed Central

    Beaulieu, Jean-Martin; Espinoza, Stefano; Gainetdinov, Raul R

    2015-01-01

    The variety of physiological functions controlled by dopamine in the brain and periphery is mediated by the D1, D2, D3, D4 and D5 dopamine GPCRs. Drugs acting on dopamine receptors are significant tools for the management of several neuropsychiatric disorders including schizophrenia, bipolar disorder, depression and Parkinson's disease. Recent investigations of dopamine receptor signalling have shown that dopamine receptors, apart from their canonical action on cAMP-mediated signalling, can regulate a myriad of cellular responses to fine-tune the expression of dopamine-associated behaviours and functions. Such signalling mechanisms may involve alternate G protein coupling or non-G protein mechanisms involving ion channels, receptor tyrosine kinases or proteins such as β-arrestins that are classically involved in GPCR desensitization. Another level of complexity is the growing appreciation of the physiological roles played by dopamine receptor heteromers. Applications of new in vivo techniques have significantly furthered the understanding of the physiological functions played by dopamine receptors. Here we provide an update of the current knowledge regarding the complex biology, signalling, physiology and pharmacology of dopamine receptors. PMID:25671228

  11. Grafted dopamine neurons: Morphology, neurochemistry, and electrophysiology.

    PubMed

    Strömberg, Ingrid; Bickford, Paula; Gerhardt, Greg A

    2010-02-09

    Grafting of dopamine-rich tissue to counteract the symptoms in Parkinson's disease became a promising tool for future treatment. This article discusses how to improve the functional outcome with respect to graft outgrowth and functions of dopamine release and electrophysiological responses to graft implantation in the host brain striatal target. It has been documented that a subpopulation of the dopamine neurons innervates the host brain in a target-specific manner, while some of the grafted dopamine neurons never project to the host striatum. Neurochemical studies have demonstrated that the graft-induced outgrowth synthesize, store, metabolize and release dopamine and possibly other neurotransmitters such as 5-HT. Furthermore, the released dopamine affects the dopamine-depleted brain in areas that are larger than the graft-derived nerve fibers reach. While stem cells will most likely be the future source of cells to be used in grafting, it is important to find the guiding cues for how to reinnervate the dopamine-depleted striatum in a proper way with respect to the dopamine subpopulations of A9 and A10 to efficiently treat the motor abnormalities seen in Parkinson's disease.

  12. Mesolimbic Dopamine Signals the Value of Work

    PubMed Central

    Hamid, Arif A.; Pettibone, Jeffrey R.; Mabrouk, Omar S.; Hetrick, Vaughn L.; Schmidt, Robert; Vander Weele, Caitlin M.; Kennedy, Robert T.; Aragona, Brandon J.; Berke, Joshua D.

    2015-01-01

    Dopamine cell firing can encode errors in reward prediction, providing a learning signal to guide future behavior. Yet dopamine is also a key modulator of motivation, invigorating current behavior. Existing theories propose that fast (“phasic”) dopamine fluctuations support learning, while much slower (“tonic”) dopamine changes are involved in motivation. We examined dopamine release in the nucleus accumbens across multiple time scales, using complementary microdialysis and voltammetric methods during adaptive decision-making. We first show that minute-by-minute dopamine levels covary with reward rate and motivational vigor. We then show that second-by-second dopamine release encodes an estimate of temporally-discounted future reward (a value function). We demonstrate that changing dopamine immediately alters willingness to work, and reinforces preceding action choices by encoding temporal-difference reward prediction errors. Our results indicate that dopamine conveys a single, rapidly-evolving decision variable, the available reward for investment of effort, that is employed for both learning and motivational functions. PMID:26595651

  13. Cytomegalovirus downregulates IRE1 to repress the unfolded protein response.

    PubMed

    Stahl, Sebastian; Burkhart, Julia M; Hinte, Florian; Tirosh, Boaz; Mohr, Hermine; Zahedi, René P; Sickmann, Albert; Ruzsics, Zsolt; Budt, Matthias; Brune, Wolfram

    2013-01-01

    During viral infection, a massive demand for viral glycoproteins can overwhelm the capacity of the protein folding and quality control machinery, leading to an accumulation of unfolded proteins in the endoplasmic reticulum (ER). To restore ER homeostasis, cells initiate the unfolded protein response (UPR) by activating three ER-to-nucleus signaling pathways, of which the inositol-requiring enzyme 1 (IRE1)-dependent pathway is the most conserved. To reduce ER stress, the UPR decreases protein synthesis, increases degradation of unfolded proteins, and upregulates chaperone expression to enhance protein folding. Cytomegaloviruses, as other viral pathogens, modulate the UPR to their own advantage. However, the molecular mechanisms and the viral proteins responsible for UPR modulation remained to be identified. In this study, we investigated the modulation of IRE1 signaling by murine cytomegalovirus (MCMV) and found that IRE1-mediated mRNA splicing and expression of the X-box binding protein 1 (XBP1) is repressed in infected cells. By affinity purification, we identified the viral M50 protein as an IRE1-interacting protein. M50 expression in transfected or MCMV-infected cells induced a substantial downregulation of IRE1 protein levels. The N-terminal conserved region of M50 was found to be required for interaction with and downregulation of IRE1. Moreover, UL50, the human cytomegalovirus (HCMV) homolog of M50, affected IRE1 in the same way. Thus we concluded that IRE1 downregulation represents a previously undescribed viral strategy to curb the UPR.

  14. Cytomegalovirus Downregulates IRE1 to Repress the Unfolded Protein Response

    PubMed Central

    Stahl, Sebastian; Burkhart, Julia M.; Hinte, Florian; Tirosh, Boaz; Mohr, Hermine; Zahedi, René P.; Sickmann, Albert; Ruzsics, Zsolt; Budt, Matthias; Brune, Wolfram

    2013-01-01

    During viral infection, a massive demand for viral glycoproteins can overwhelm the capacity of the protein folding and quality control machinery, leading to an accumulation of unfolded proteins in the endoplasmic reticulum (ER). To restore ER homeostasis, cells initiate the unfolded protein response (UPR) by activating three ER-to-nucleus signaling pathways, of which the inositol-requiring enzyme 1 (IRE1)-dependent pathway is the most conserved. To reduce ER stress, the UPR decreases protein synthesis, increases degradation of unfolded proteins, and upregulates chaperone expression to enhance protein folding. Cytomegaloviruses, as other viral pathogens, modulate the UPR to their own advantage. However, the molecular mechanisms and the viral proteins responsible for UPR modulation remained to be identified. In this study, we investigated the modulation of IRE1 signaling by murine cytomegalovirus (MCMV) and found that IRE1-mediated mRNA splicing and expression of the X-box binding protein 1 (XBP1) is repressed in infected cells. By affinity purification, we identified the viral M50 protein as an IRE1-interacting protein. M50 expression in transfected or MCMV-infected cells induced a substantial downregulation of IRE1 protein levels. The N-terminal conserved region of M50 was found to be required for interaction with and downregulation of IRE1. Moreover, UL50, the human cytomegalovirus (HCMV) homolog of M50, affected IRE1 in the same way. Thus we concluded that IRE1 downregulation represents a previously undescribed viral strategy to curb the UPR. PMID:23950715

  15. Facilitation of fear extinction by novelty depends on dopamine acting on D1-subtype dopamine receptors in hippocampus

    PubMed Central

    Menezes, Jefferson; Alves, Niége; Borges, Sidnei; Roehrs, Rafael; de Carvalho Myskiw, Jociane; Furini, Cristiane Regina Guerino; Izquierdo, Ivan; Mello-Carpes, Pâmela B.

    2015-01-01

    Extinction is the learned inhibition of retrieval. Recently it was shown that a brief exposure to a novel environment enhances the extinction of contextual fear in rats, an effect explainable by a synaptic tagging-and-capture process. Here we examine whether this also happens with the extinction of another fear-motivated task, inhibitory avoidance (IA), and whether it depends on dopamine acting on D1 or D5 receptors. Rats were trained first in IA and then in extinction of this task. The retention of extinction was measured 24 h later. A 5-min exposure to a novel environment 30 min before extinction training enhanced its retention. Right after exposure to the novelty, animals were given bilateral intrahippocampal infusions of vehicle (VEH), of the protein synthesis inhibitor anisomycin, of the D1/D5 dopaminergic antagonist SCH23390, of the PKA inhibitor Rp-cAMP or of the PKC inhibitor Gö6976, and of the PKA stimulator Sp-cAMP or of the PKC stimulator PMA. The novelty increased hippocampal dopamine levels and facilitated the extinction, which was inhibited by intrahippocampal protein synthesis inhibitor anisomysin, D1/D5 dopaminerdic antagonist SCH23390, or PKA inhibitor Rp-cAMP and unaffected by PKC inhibitor Gö6976; additionally, the hippocampal infusion of PKA stimulator Sp-cAMP reverts the effect of D1/D5 dopaminergic antagonist SCH 23390, but the infusion of PKC stimulator PMA does not. The results attest to the generality of the novelty effect on fear extinction, suggest that it relies on synaptic tagging and capture, and show that it depends on hippocampal dopamine D1 but not D5 receptors. PMID:25775606

  16. Facilitation of fear extinction by novelty depends on dopamine acting on D1-subtype dopamine receptors in hippocampus.

    PubMed

    Menezes, Jefferson; Alves, Niége; Borges, Sidnei; Roehrs, Rafael; de Carvalho Myskiw, Jociane; Furini, Cristiane Regina Guerino; Izquierdo, Ivan; Mello-Carpes, Pâmela B

    2015-03-31

    Extinction is the learned inhibition of retrieval. Recently it was shown that a brief exposure to a novel environment enhances the extinction of contextual fear in rats, an effect explainable by a synaptic tagging-and-capture process. Here we examine whether this also happens with the extinction of another fear-motivated task, inhibitory avoidance (IA), and whether it depends on dopamine acting on D1 or D5 receptors. Rats were trained first in IA and then in extinction of this task. The retention of extinction was measured 24 h later. A 5-min exposure to a novel environment 30 min before extinction training enhanced its retention. Right after exposure to the novelty, animals were given bilateral intrahippocampal infusions of vehicle (VEH), of the protein synthesis inhibitor anisomycin, of the D1/D5 dopaminergic antagonist SCH23390, of the PKA inhibitor Rp-cAMP or of the PKC inhibitor Gö6976, and of the PKA stimulator Sp-cAMP or of the PKC stimulator PMA. The novelty increased hippocampal dopamine levels and facilitated the extinction, which was inhibited by intrahippocampal protein synthesis inhibitor anisomysin, D1/D5 dopaminerdic antagonist SCH23390, or PKA inhibitor Rp-cAMP and unaffected by PKC inhibitor Gö6976; additionally, the hippocampal infusion of PKA stimulator Sp-cAMP reverts the effect of D1/D5 dopaminergic antagonist SCH 23390, but the infusion of PKC stimulator PMA does not. The results attest to the generality of the novelty effect on fear extinction, suggest that it relies on synaptic tagging and capture, and show that it depends on hippocampal dopamine D1 but not D5 receptors.

  17. Effects of chronic methamphetamine on psychomotor and cognitive functions and dopamine signaling in the brain.

    PubMed

    Thanos, Panayotis K; Kim, Ronald; Delis, Foteini; Rocco, Mark J; Cho, Jacob; Volkow, Nora D

    2017-03-01

    Methamphetamine (MA) studies in animals usually involve acute, binge, or short-term exposure to the drug. However, addicts take substantial amounts of MA for extended periods of time. Here we wished to study the effects of MA exposure on brain and behavior, using an animal model analogous to this pattern of MA intake. MA doses, 4 and 8mg/kg/day, were based on previously reported average daily freely available MA self-administration levels. We examined the effects of 16 week MA treatment on psychomotor and cognitive function in the rat using open field and novel object recognition tests and we studied the adaptations of the dopaminergic system, using in vitro and in vivo receptor imaging. We show that chronic MA treatment, at doses that correspond to the average daily freely available self-administration levels in the rat, disorganizes open field activity, impairs alert exploratory behavior and anxiety-like state, and downregulates dopamine transporter in the striatum. Under these treatment conditions, dopamine terminal functional integrity in the nucleus accumbens is also affected. In addition, lower dopamine D1 receptor binding density, and, to a smaller degree, lower dopamine D2 receptor binding density were observed. Potential mechanisms related to these alterations are discussed.

  18. The dopamine hypothesis of bipolar affective disorder: the state of the art and implications for treatment

    PubMed Central

    Ashok, A H; Marques, T R; Jauhar, S; Nour, M M; Goodwin, G M; Young, A H; Howes, O D

    2017-01-01

    Bipolar affective disorder is a common neuropsychiatric disorder. Although its neurobiological underpinnings are incompletely understood, the dopamine hypothesis has been a key theory of the pathophysiology of both manic and depressive phases of the illness for over four decades. The increased use of antidopaminergics in the treatment of this disorder and new in vivo neuroimaging and post-mortem studies makes it timely to review this theory. To do this, we conducted a systematic search for post-mortem, pharmacological, functional magnetic resonance and molecular imaging studies of dopamine function in bipolar disorder. Converging findings from pharmacological and imaging studies support the hypothesis that a state of hyperdopaminergia, specifically elevations in D2/3 receptor availability and a hyperactive reward processing network, underlies mania. In bipolar depression imaging studies show increased dopamine transporter levels, but changes in other aspects of dopaminergic function are inconsistent. Puzzlingly, pharmacological evidence shows that both dopamine agonists and antidopaminergics can improve bipolar depressive symptoms and perhaps actions at other receptors may reconcile these findings. Tentatively, this evidence suggests a model where an elevation in striatal D2/3 receptor availability would lead to increased dopaminergic neurotransmission and mania, whilst increased striatal dopamine transporter (DAT) levels would lead to reduced dopaminergic function and depression. Thus, it can be speculated that a failure of dopamine receptor and transporter homoeostasis might underlie the pathophysiology of this disorder. The limitations of this model include its reliance on pharmacological evidence, as these studies could potentially affect other monoamines, and the scarcity of imaging evidence on dopaminergic function. This model, if confirmed, has implications for developing new treatment strategies such as reducing the dopamine synthesis and/or release in

  19. The dopamine hypothesis of bipolar affective disorder: the state of the art and implications for treatment.

    PubMed

    Ashok, A H; Marques, T R; Jauhar, S; Nour, M M; Goodwin, G M; Young, A H; Howes, O D

    2017-05-01

    Bipolar affective disorder is a common neuropsychiatric disorder. Although its neurobiological underpinnings are incompletely understood, the dopamine hypothesis has been a key theory of the pathophysiology of both manic and depressive phases of the illness for over four decades. The increased use of antidopaminergics in the treatment of this disorder and new in vivo neuroimaging and post-mortem studies makes it timely to review this theory. To do this, we conducted a systematic search for post-mortem, pharmacological, functional magnetic resonance and molecular imaging studies of dopamine function in bipolar disorder. Converging findings from pharmacological and imaging studies support the hypothesis that a state of hyperdopaminergia, specifically elevations in D2/3 receptor availability and a hyperactive reward processing network, underlies mania. In bipolar depression imaging studies show increased dopamine transporter levels, but changes in other aspects of dopaminergic function are inconsistent. Puzzlingly, pharmacological evidence shows that both dopamine agonists and antidopaminergics can improve bipolar depressive symptoms and perhaps actions at other receptors may reconcile these findings. Tentatively, this evidence suggests a model where an elevation in striatal D2/3 receptor availability would lead to increased dopaminergic neurotransmission and mania, whilst increased striatal dopamine transporter (DAT) levels would lead to reduced dopaminergic function and depression. Thus, it can be speculated that a failure of dopamine receptor and transporter homoeostasis might underlie the pathophysiology of this disorder. The limitations of this model include its reliance on pharmacological evidence, as these studies could potentially affect other monoamines, and the scarcity of imaging evidence on dopaminergic function. This model, if confirmed, has implications for developing new treatment strategies such as reducing the dopamine synthesis and/or release in

  20. l-Theanine protects against excess dopamine-induced neurotoxicity in the presence of astrocytes

    PubMed Central

    Takeshima, Mika; Miyazaki, Ikuko; Murakami, Shinki; Kita, Taizo; Asanuma, Masato

    2016-01-01

    l-Theanine (γ-glutamylethylamide), a component of green tea, is considered to have regulatory and neuroprotective roles in the brain. The present study was designed to determine the effect of l-theanine on excess dopamine-induced neurotoxicity in both cell culture and animal experiments. The primary cultured mesencephalic neurons or co-cultures of mesencephalic neurons and striatal astrocytes were pretreated with l-theanine for 72 h, and then treated with excess dopamine for further 24 h. The cell viability of dopamine neurons and levels of glutathione were evaluated. Excess dopamine-induced neurotoxicity was significantly attenuated by 72 h preincubation with l-theanine in neuron-astrocyte co-cultures but not in neuron-rich cultures. Exposure to l-theanine increased the levels of glutathione in both astrocytes and glial conditioned medium. The glial conditioned medium from l-theanine-pretreated striatal astrocytes attenuated dopamine-induced neurotoxicity and quinoprotein formation in mesencephalic neurons. In addition, replacement of l-glutamate with l-theanine in an in vitro cell-free glutathione-synthesis system produced glutathione-like thiol compounds. Furthermore, l-theanine administration (4 mg/kg, p.o.) for 14 days significantly increased glutathione levels in the striatum of mice. The results suggest that l-theanine provides neuroprotection against oxidative stress-induced neuronal damage by humoral molecules released from astrocytes, probably including glutathione. PMID:27698535

  1. l-Theanine protects against excess dopamine-induced neurotoxicity in the presence of astrocytes.

    PubMed

    Takeshima, Mika; Miyazaki, Ikuko; Murakami, Shinki; Kita, Taizo; Asanuma, Masato

    2016-09-01

    l-Theanine (γ-glutamylethylamide), a component of green tea, is considered to have regulatory and neuroprotective roles in the brain. The present study was designed to determine the effect of l-theanine on excess dopamine-induced neurotoxicity in both cell culture and animal experiments. The primary cultured mesencephalic neurons or co-cultures of mesencephalic neurons and striatal astrocytes were pretreated with l-theanine for 72 h, and then treated with excess dopamine for further 24 h. The cell viability of dopamine neurons and levels of glutathione were evaluated. Excess dopamine-induced neurotoxicity was significantly attenuated by 72 h preincubation with l-theanine in neuron-astrocyte co-cultures but not in neuron-rich cultures. Exposure to l-theanine increased the levels of glutathione in both astrocytes and glial conditioned medium. The glial conditioned medium from l-theanine-pretreated striatal astrocytes attenuated dopamine-induced neurotoxicity and quinoprotein formation in mesencephalic neurons. In addition, replacement of l-glutamate with l-theanine in an in vitro cell-free glutathione-synthesis system produced glutathione-like thiol compounds. Furthermore, l-theanine administration (4 mg/kg, p.o.) for 14 days significantly increased glutathione levels in the striatum of mice. The results suggest that l-theanine provides neuroprotection against oxidative stress-induced neuronal damage by humoral molecules released from astrocytes, probably including glutathione.

  2. Prenatal stress, moderate fetal alcohol, and dopamine system function in rhesus monkeys.

    PubMed

    Roberts, A D; Moore, C F; DeJesus, O T; Barnhart, T E; Larson, J A; Mukherjee, J; Nickles, R J; Schueller, M J; Shelton, S E; Schneider, M L

    2004-01-01

    This study examined the striatal dopamine system integrity and associated behavior in 5- to 7-year-old rhesus monkeys born from mothers that experienced stress and/or consumed moderate levels of alcohol during pregnancy. Thirty-one young adult rhesus monkeys were derived from females randomly assigned to one of four groups: (1) control group that consumed isocaloric sucrose solution throughout gestation; (2) stress group that experienced prenatal stress (10-min removal from home cage and exposure to three random loud noise bursts, gestational days 90 through 145); (3) alcohol group that consumed alcohol (0.6 g/kg/day) throughout gestation; or (4) combined alcohol plus stress group that received both treatments. The subjects were assessed for striatal dopamine system function using positron emission tomography (PET), in which the dopamine (DA)-rich striatum was evaluated in separate scans for the trapping of [(18)F]-Fallypride (FAL) and 6-[(18)F]fluoro-m-tyrosine (FMT) to assess dopamine D2 receptor binding potential (BP) and DA synthesis via dopa decarboxylase activity, respectively. Subjects were previously assessed for non-matching-to-sample (NMS) task acquisition, with ratings of behavioral inhibition, stereotypies, and activity made after each NMS testing session. Subjects from prenatal stress conditions (Groups 2 and 4) showed an increase in the ratio of striatal dopamine D2 receptor BP and DA synthesis compared to controls (Group 1). An increase in the radiotracer distribution volume ratios (DVRs), which is used to evaluate the balance between striatal DA synthesis and receptor availability, respectively, was significantly correlated with less behavioral inhibition. The latter supports a hypothesis linking striatal function to behavioral inhibitory control.

  3. [Role of DopR in the molecular mechanism of the dopamine control of juvenile hormone metabolism in female Drosophila].

    PubMed

    Karpova, E K; Bogomolova, E V; Romonova, I V; Gruntenko, N E; Raushenbakh, I Iu

    2012-08-01

    The effect of a decreased availability of the D1-like dopamine receptor (DopR) in Drosophila (caused by DopR antagonist added into food) on the juvenile hormone (JH) synthesis rate in young female D. melanogaster has been studied. The JH degradation rate and the alkaline phosphatase (ALP) and tyrosine decarboxylase (TDC) activities were used as indicators of the JH synthesis rate. Treatment of the flies with butaclamol, a specific DopR antagonist, has been demonstrated to increase the JH degradation rate, and the stress reactivity of the system of JH metabolism and decrease the ALP activity and stress reactivity, and increase the TDC activity and stress reactivity. As shown earlier, all this indicates a decrease in the JH synthesis rate in young female drosophila with a decreased DopR availability. It is concluded that the activating effect of dopamine on JH synthesis in Drosophila is mediated by D1-like receptors.

  4. Viral-mediated temporally controlled dopamine production in a rat model of Parkinson disease.

    PubMed

    Li, Xiao-Gang; Okada, Takashi; Kodera, Mika; Nara, Yuko; Takino, Naomi; Muramatsu, Chieko; Ikeguchi, Kunihiko; Urano, Fumi; Ichinose, Hiroshi; Metzger, Daniel; Chambon, Pierre; Nakano, Imaharu; Ozawa, Keiya; Muramatsu, Shin-Ichi

    2006-01-01

    Regulation of gene expression is necessary to avoid possible adverse effects of gene therapy due to excess synthesis of transgene products. To reduce transgene expression, we developed a viral vector-mediated somatic regulation system using inducible Cre recombinase. A recombinant adeno-associated virus (AAV) vector expressing Cre recombinase fused to a mutated ligand-binding domain of the estrogen receptor alpha (CreER(T2)) was delivered along with AAV vectors expressing dopamine-synthesizing enzymes to rats of a Parkinson disease model. Treatment with 4-hydroxytamoxifen, a synthetic estrogen receptor modulator, activated Cre recombinase within the transduced neurons and induced selective excision of the tyrosine hydroxylase (TH) coding sequence flanked by loxP sites, leading to a reduction in transgene-mediated dopamine synthesis. Using this strategy, aromatic L-amino acid decarboxylase (AADC) activity was retained so that l-3,4-dihydroxyphenylalanine (L-dopa), a substrate for AADC, could be converted to dopamine in the striatum and the therapeutic effects of L-dopa preserved, even after reduction of TH expression in the case of dopamine overproduction. Our data demonstrate that viral vector-mediated inducible Cre recombinase can serve as an in vivo molecular switch, allowing spatial and temporal control of transgene expression, thereby potentially increasing the safety of gene therapy.

  5. Synapsins Differentially Control Dopamine and Serotonin Release

    PubMed Central

    Kile, Brian M.; Guillot, Thomas S.; Venton, B. Jill; Wetsel, William C.; Augustine, George J.; Wightman, R. Mark

    2010-01-01

    Synapsins are a family of synaptic vesicle proteins that are important for neurotransmitter release. Here we have used triple knockout (TKO) mice lacking all three synapsin genes to determine the roles of synapsins in the release of two monoamine neurotransmitters, dopamine and serotonin. Serotonin release evoked by electrical stimulation was identical in substantia nigra pars reticulata slices prepared from TKO and wild-type mice. In contrast, release of dopamine in response to electrical stimulation was approximately doubled in striatum of TKO mice, both in vivo and in striatal slices, in comparison to wild-type controls. This was due to loss of synapsin III, because deletion of synapsin III alone was sufficient to increase dopamine release. Deletion of synapsins also increased the sensitivity of dopamine release to extracellular calcium ions. Although cocaine did not affect the release of serotonin from nigral tissue, this drug did enhance dopamine release. Cocaine-induced facilitation of dopamine release was a function of external calcium, an effect that was reduced in TKO mice. We conclude that synapsins play different roles in the control of release of dopamine and serotonin, with release of dopamine being negatively regulated by synapsins, specifically synapsin III, while serotonin release appears to be relatively independent of synapsins. These results provide further support for the concept that synapsin function in presynaptic terminals varies according to the neurotransmitter being released. PMID:20660258

  6. Synapsins differentially control dopamine and serotonin release.

    PubMed

    Kile, Brian M; Guillot, Thomas S; Venton, B Jill; Wetsel, William C; Augustine, George J; Wightman, R Mark

    2010-07-21

    Synapsins are a family of synaptic vesicle proteins that are important for neurotransmitter release. Here we have used triple knock-out (TKO) mice lacking all three synapsin genes to determine the roles of synapsins in the release of two monoamine neurotransmitters, dopamine and serotonin. Serotonin release evoked by electrical stimulation was identical in substantia nigra pars reticulata slices prepared from TKO and wild-type mice. In contrast, release of dopamine in response to electrical stimulation was approximately doubled in striatum of TKO mice, both in vivo and in striatal slices, in comparison to wild-type controls. This was due to loss of synapsin III, because deletion of synapsin III alone was sufficient to increase dopamine release. Deletion of synapsins also increased the sensitivity of dopamine release to extracellular calcium ions. Although cocaine did not affect the release of serotonin from nigral tissue, this drug did enhance dopamine release. Cocaine-induced facilitation of dopamine release was a function of external calcium, an effect that was reduced in TKO mice. We conclude that synapsins play different roles in the control of release of dopamine and serotonin, with release of dopamine being negatively regulated by synapsins, specifically synapsin III, while serotonin release appears to be relatively independent of synapsins. These results provide further support for the concept that synapsin function in presynaptic terminals varies according to the neurotransmitter being released.

  7. Going for broke: dopamine influences risky choice.

    PubMed

    Moschak, Travis M; Carelli, Regina M

    2014-10-01

    Dopamine neurons track reward by increasing or decreasing their firing rate when a reward is present or absent. In this issue of Neuron, Stopper et al. (2014) demonstrate that artificially eliminating these dopamine bursts or dips can alter risky decision-making.

  8. Metabolism of dopamine by the nasal mucosa.

    PubMed

    Chemuturi, Nagendra V; Donovan, Maureen D

    2006-11-01

    The nasal route of administration offers several advantages over oral and intravenous administration, including the ability to avoid hepatic first pass metabolism. Dopamine deficiency has been associated with several neurological disorders; it has been shown to have good systemic bioavailability and significant uptake into the CNS following intranasal administration. The purpose of these studies was to investigate the limiting role of mucosal metabolism of dopamine during nasal absorption. In vitro transport and initial rate studies were carried out using nasal mucosal explants to study dopamine permeability and metabolism. Dihydroxyphenylacetic acid (DOPAC) was the only metabolite detected. Monoamine oxidase (MAO), the enzyme responsible for DOPAC formation, was localized to the submucosal region of the nasal explants. The amount of DOPAC formed during the transport studies was less than 0.5% of the initial amount of dopamine placed into the system. Iproniazid, an MAO inhibitor, blocked DOPAC formation but had no effect on dopamine transport. The limited extent of dopamine metabolism compared to its mucosal transport demonstrates that nasal dopamine transport is not significantly reduced by mucosal metabolism and suggests that the nasal route may be promising for the efficient delivery of dopamine to the CNS.

  9. Dopamine transporter mutant animals: a translational perspective

    PubMed Central

    Efimova, Evgenia V.; Gainetdinov, Raul R.; Budygin, Evgeny A.; Sotnikova, Tatiana D.

    2016-01-01

    The dopamine transporter (DAT) plays an important homeostatic role in the control of both the extracellular and intraneuronal concentrations of dopamine, thereby providing effective control over activity of dopaminergic transmission. Since brain dopamine is known to be involved in numerous neuropsychiatric disorders, investigations using mice with genetically altered DAT function and thus intensity of dopamine-mediated signaling have provided numerous insights into the pathology of these disorders and highlight novel pathological mechanisms that could be targeted to provide new therapeutic approaches for these disorders. In this brief overview we discuss recent investigations involving animals with genetically altered DAT function, particularly focusing on translational studies providing new insights into pathology and pharmacology of dopamine-related disorders. Perspective applications of these and newly developed models of DAT dysfunction are also discussed. PMID:27276191

  10. THE MYSTERIOUS MOTIVATIONAL FUNCTIONS OF MESOLIMBIC DOPAMINE

    PubMed Central

    Salamone, John D.; Correa, Mercè

    2012-01-01

    Summary Nucleus accumbens dopamine is known to play a role in motivational processes, and dysfunctions of mesolimbic dopamine may contribute to motivational symptoms of depression and other disorders, as well as features of substance abuse. Although it has become traditional to label dopamine neurons as “reward” neurons, this is an over-generalization, and it is important to distinguish between aspects of motivation that are differentially affected by dopaminergic manipulations. For example, accumbens dopamine does not mediate primary food motivation or appetite, but is involved in appetitive and aversive motivational processes including behavioral activation, exertion of effort, approach behavior, sustained task engagement, Pavlovian processes and instrumental learning. In this review, we discuss the complex roles of dopamine in behavioral functions related to motivation. PMID:23141060

  11. Metabolic hormones, dopamine circuits, and feeding

    PubMed Central

    Narayanan, Nandakumar S.; Guarnieri, Douglas J.; DiLeone, Ralph J.

    2009-01-01

    Recent evidence has emerged demonstrating that metabolic hormones such as ghrelin and leptin can act on ventral tegmental area (VTA) midbrain dopamine neurons to influence feeding. The VTA is the origin of mesolimbic dopamine neurons that project to the nucleus accumbens (NAc) to influence behavior. While blockade of dopamine via systemic antagonists or targeted gene delete can impair food intake, local NAc dopamine manipulations have little effect on food intake. Notably, non-dopaminergic manipulations in the VTA and NAc produce more consistent effects on feeding and food choice. More recent genetic evidence supports a role for the substantia nigra-striatal dopamine pathways in food intake, while the VTA-NAc circuit is more likely involved in higher-order aspects of food acquisition, such as motivation and cue associations. This rich and complex literature should be considered in models of how peripheral hormones influence feeding behavior via action on the midbrain circuits. PMID:19836414

  12. GABA, glutamate, dopamine and serotonin transporters expression on forgetting.

    PubMed

    Tellez, Ruth; Gómez-Viquez, Leticia; Liy-Salmeron, Gustavo; Meneses, Alfredo

    2012-07-01

    Notwithstanding several neurotransmission systems are frequently related to memory formation; forgetting process and neurotransmission systems or their transporters; the role of γ-aminobutyric acid (GAT1), glutamate (EACC1), dopamine (DAT) and serotonin (SERT) is poorly understood. Hence, in this paper western-blot analysis was used to evaluate expression of GAT1, EAAC1, DAT and SERT during forgetting in trained and untrained rats treated with the selective serotonin transporter inhibitor fluoxetine, the amnesic drug d-methamphetamine (METH) and fluoxetine plus METH. Transporters expression was determined in the hippocampus (HIP), prefrontal cortex (PFC) and striatum (STR). Results indicated that forgetting of Pavlovian/instrumental autoshaping was associated to up-regulation of GAT1 (PFC and HIP) and DAT (PFC) while SERT (HIP) was down-regulated; no-changes were observed in striatum. Methamphetamine administration did not affect forgetting at 216 h post-training but up-regulated hippocampal DAT and EACC, prefrontal cortex DAT and striatal GAT1 or EACC1. Fluoxetine alone prevented forgetting, which was associated to striatal GAT1 and hippocampal DAT up-regulation, but prefrontal cortex GAT1 down-regulation. Fluoxetine plus METH administration was also able to prevent forgetting, which was associated to hippocampal DAT, prefrontal cortex SERT and striatal GAT1, DAT or SERT up-regulation, but prefrontal cortex GAT1 down-regulation. Together these data show that forgetting provokes primarily hippocampal and prefrontal cortex transporters changes; forgetting represent a behavioral process hardly modifiable and its prevention could causes different transporters expression patterns.

  13. Loss of mitochondrial complex I activity potentiates dopamine neuron death induced by microtubule dysfunction in a Parkinson’s disease model

    PubMed Central

    Choi, Won-Seok; Palmiter, Richard D.

    2011-01-01

    Mitochondrial complex I dysfunction is regarded as underlying dopamine neuron death in Parkinson’s disease models. However, inactivation of the Ndufs4 gene, which compromises complex I activity, does not affect the survival of dopamine neurons in culture or in the substantia nigra pars compacta of 5-wk-old mice. Treatment with piericidin A, a complex I inhibitor, does not induce selective dopamine neuron death in either Ndufs4+/+ or Ndufs4−/− mesencephalic cultures. In contrast, rotenone, another complex I inhibitor, causes selective toxicity to dopamine neurons, and Ndufs4 inactivation potentiates this toxicity. We identify microtubule depolymerization and the accumulation of cytosolic dopamine and reactive oxygen species as alternative mechanisms underlying rotenone-induced dopamine neuron death. Enhanced rotenone toxicity to dopamine neurons from Ndufs4 knockout mice may involve enhanced dopamine synthesis caused by the accumulation of nicotinamide adenine dinucleotide reduced. Our results suggest that the combination of disrupting microtubule dynamics and inhibiting complex I, either by mutations or exposure to toxicants, may be a risk factor for Parkinson’s disease. PMID:21383081

  14. HIV, Tat and dopamine transmission.

    PubMed

    Gaskill, Peter J; Miller, Douglas R; Gamble-George, Joyonna; Yano, Hideaki; Khoshbouei, Habibeh

    2017-09-01

    Human Immunodeficiency Virus (HIV) is a progressive infection that targets the immune system, affecting more than 37 million people around the world. While combinatorial antiretroviral therapy (cART) has lowered mortality rates and improved quality of life in infected individuals, the prevalence of HIV associated neurocognitive disorders is increasing and HIV associated cognitive decline remains prevalent. Recent research has suggested that HIV accessory proteins may be involved in this decline, and several studies have indicated that the HIV protein transactivator of transcription (Tat) can disrupt normal neuronal and glial function. Specifically, data indicate that Tat may directly impact dopaminergic neurotransmission, by modulating the function of the dopamine transporter and specifically damaging dopamine-rich regions of the CNS. HIV infection of the CNS has long been associated with dopaminergic dysfunction, but the mechanisms remain undefined. The specific effect(s) of Tat on dopaminergic neurotransmission may be, at least partially, a mechanism by which HIV infection directly or indirectly induces dopaminergic dysfunction. Therefore, precisely defining the specific effects of Tat on the dopaminergic system will help to elucidate the mechanisms by which HIV infection of the CNS induces neuropsychiatric, neurocognitive and neurological disorders that involve dopaminergic neurotransmission. Further, this will provide a discussion of the experiments needed to further these investigations, and may help to identify or develop new therapeutic approaches for the prevention or treatment of these disorders in HIV-infected individuals. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Dopamine agonist therapy in hyperprolactinemia.

    PubMed

    Webster, J

    1999-12-01

    Introduction of the dopamine agonist bromocriptine heralded a major advance in the management of hyperprolactinemic disorders. Although its side effects of nausea, dizziness and headache and its short elimination half-life are limiting factors, its efficacy established it as a reference compound against the activity of which several dopamine agonists, like pergolide, lysuride, metergoline, terguride and dihydroergocristine, fell by the wayside. More recently, two new agents, cabergoline and quinagolide, have been introduced and appear to offer considerable advantages over bromocriptine. Cabergoline, an ergoline D2 agonist, has a long plasma half-life that enables once- or twice-weekly administration. Quinagolide, in contrast, is a nonergot D2 agonist with an elimination half-life intermediate between those of bromocriptine and cabergoline, allowing the drug to be administered once daily. Comparative studies indicate that cabergoline is clearly superior to bromocriptine in efficacy (prolactin suppression, restoration of gonadal function) and in tolerability. In similar studies, quinagolide appeared to have similar efficacy and superior tolerability to that of bromocriptine. Results of a small crossover study indicate that cabergoline is better tolerated, with a trend toward activity superior to that of quinagolide. In hyperprolactinemic men and in women not seeking to become pregnant, cabergoline may be regarded as the treatment of choice.

  16. Inhibition of tetrodotoxin-resistant sodium current in dorsal root ganglia neurons mediated by D1/D5 dopamine receptors

    PubMed Central

    2013-01-01

    Background Dopaminergic fibers originating from area A11 of the hypothalamus project to different levels of the spinal cord and represent the major source of dopamine. In addition, tyrosine hydroxylase, the rate-limiting enzyme for the synthesis of catecholamines, is expressed in 8-10% of dorsal root ganglia (DRG) neurons, suggesting that dopamine may be released in the dorsal root ganglia. Dopamine has been shown to modulate calcium current in DRG neurons, but the effects of dopamine on sodium current and on the firing properties of small DRG neurons are poorly understood. Results The effects of dopamine and dopamine receptor agonists were tested on the tetrodotoxin-resistant (TTX-R) sodium current recorded from acutely dissociated small (diameter ≤ 25 μm) DRG neurons. Dopamine (20 μM) and SKF 81297 (10 μM) caused inhibition of TTX-R sodium current in small DRG neurons by 23% and 37%, respectively. In contrast, quinpirole (20 μM) had no effects on the TTX-R sodium current. Inhibition by SKF 81297 of the TTX-R sodium current was not affected when the protein kinase A (PKA) activity was blocked with the PKA inhibitory peptide (6–22), but was greatly reduced when the protein kinase C (PKC) activity was blocked with the PKC inhibitory peptide (19–36), suggesting that activation of D1/D5 dopamine receptors is linked to PKC activity. Expression of D1and D5 dopamine receptors in small DRG neurons, but not D2 dopamine receptors, was confirmed by Western blotting and immunofluorescence analysis. In current clamp experiments, the number of action potentials elicited in small DRG neurons by current injection was reduced by ~ 30% by SKF 81297. Conclusions We conclude that activation of D1/D5 dopamine receptors inhibits TTX-R sodium current in unmyelinated nociceptive neurons and dampens their intrinsic excitability by reducing the number of action potentials in response to stimulus. Increasing or decreasing levels of dopamine in the dorsal root ganglia

  17. Sources and physiological significance of plasma dopamine sulfate.

    PubMed

    Goldstein, D S; Swoboda, K J; Miles, J M; Coppack, S W; Aneman, A; Holmes, C; Lamensdorf, I; Eisenhofer, G

    1999-07-01

    Dopamine in the circulation occurs mainly as dopamine sulfate, the sources and physiological significance of which have been obscure. In this study, plasma concentrations of dopamine sulfate were measured after a meal, after fasting for 4 days, and during i.v. L-DOPA, nitroprusside, or trimethaphan infusion in volunteers; after dopamine infusion in patients with L-aromatic-amino-acid decarboxylase deficiency; in arterial and portal venous plasma of gastrointestinal surgery patients; and in patients with sympathetic neurocirculatory failure. Meal ingestion increased plasma dopamine sulfate by more than 50-fold; however, prolonged fasting decreased plasma dopamine sulfate only slightly. L-DOPA infusion produced much larger increments in dopamine sulfate than in dopamine; the other drugs were without effect. Patients with L-aromatic amino acid decarboxylase deficiency had decreased dopamine sulfate levels, and patients with sympathetic neurocirculatory failure had normal levels. Decarboxylase-deficient patients undergoing dopamine infusion had a dopamine sulfate/dopamine ratio about 25 times less than that at baseline in volunteers. Surgery patients had large arterial-portal venous increments in plasma concentrations of dopamine sulfate, so that mesenteric dopamine sulfate production accounted for most of urinary dopamine sulfate excretion, a finding consistent with the localization of the dopamine sulfoconjugating enzyme to gastrointestinal tissues. The results indicate that plasma dopamine sulfate derives mainly from sulfoconjugation of dopamine synthesized from L-DOPA in the gastrointestinal tract. Both dietary and endogenous determinants affect plasma dopamine sulfate. The findings suggest an enzymatic gut-blood barrier for detoxifying exogenous dopamine and delimiting autocrine/paracrine effects of endogenous dopamine generated in a "third catecholamine system."

  18. Dopamine receptors in human gastrointestinal mucosa

    SciTech Connect

    Hernandez, D.E.; Mason, G.A.; Walker, C.H.; Valenzuela, J.E.

    1987-12-21

    Dopamine is a putative enteric neurotransmitter that has been implicated in exocrine secretory and motility functions of the gastrointestinal tract of several mammalian species including man. This study was designed to determine the presence of dopamine binding sites in human gastric and duodenal mucosa and to describe certain biochemical characteristics of these enteric receptor sites. The binding assay was performed in triplicate with tissue homogenates obtained from healthy volunteers of both sexes using /sup 3/H-dopamine as a ligand. The extent of nonspecific binding was determined in the presence of a 100-fold excess of unlabeled dopamine. Scatchard analysis performed with increasing concentrations of /sup 3/H-dopamine (20-500 nM) revealed a single class of saturable dopamine binding sites in gastric and duodenal mucosa. The results of this report demonstrate the presence of specific dopamine receptors in human gastric and duodenal mucosa. These biochemical data suggest that molecular abnormalities of these receptor sites may be operative in the pathogenesis of important gastrointestinal disorders. 33 references, 2 figures.

  19. Dopamine transporter: expression in Xenopus oocytes.

    PubMed

    Uhl, G R; O'Hara, B; Shimada, S; Zaczek, R; DiGiorgianni, J; Nishimori, T

    1991-01-01

    Xenopus oocytes can express biologically relevant transport activity after injection of mRNAs encoding several carrier molecules. mRNA from PC12 cells, as well as transcripts from a rat ventral midbrain library, can be expressed in these oocytes and allow them to display pharmacologically specific dopamine uptake. mRNA-injected oocytes incubated with tritiated dopamine contain tritiated dopamine and metabolites; lower amounts of radiolabeled dopamine and more radiolabeled metabolites are found in oocytes co-incubated with cocaine or in water-injected oocytes. Tritiated dopamine uptake into mRNA-injected oocytes is time, sodium, and temperature dependent. It is blocked by cocaine and mazindol, but not by haloperidol. It is not found after injection of mRNA from other brain regions. A size-selected rat midbrain library constructed in the plasma vector pCDM8 yields mRNA transcripts whose injection into oocytes causes cocaine-blockable [3H]dopamine uptake. These findings provide an assay for purification of the dopamine transporter cDNA by sib selection techniques.

  20. Insulin resistance impairs nigrostriatal dopamine function.

    PubMed

    Morris, J K; Bomhoff, G L; Gorres, B K; Davis, V A; Kim, J; Lee, P-P; Brooks, W M; Gerhardt, G A; Geiger, P C; Stanford, J A

    2011-09-01

    Clinical studies have indicated a link between Parkinson's disease (PD) and Type 2 Diabetes. Although preclinical studies have examined the effect of high-fat feeding on dopamine function in brain reward pathways, the effect of diet on neurotransmission in the nigrostriatal pathway, which is affected in PD and parkinsonism, is less clear. We hypothesized that a high-fat diet, which models early-stage Type 2 Diabetes, would disrupt nigrostriatal dopamine function in young adult Fischer 344 rats. Rats were fed a high fat diet (60% calories from fat) or a normal chow diet for 12 weeks. High fat-fed animals were insulin resistant compared to chow-fed controls. Potassium-evoked dopamine release and dopamine clearance were measured in the striatum using in vivo electrochemistry. Dopamine release was attenuated and dopamine clearance was diminished in the high-fat diet group compared to chow-fed rats. Magnetic resonance imaging indicated increased iron deposition in the substantia nigra of the high fat group. This finding was supported by alterations in the expression of several proteins involved in iron metabolism in the substantia nigra in this group compared to chow-fed animals. The diet-induced systemic and basal ganglia-specific changes may play a role in the observed impairment of nigrostriatal dopamine function. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. Decreased prefrontal cortical dopamine transmission in alcoholism.

    PubMed

    Narendran, Rajesh; Mason, Neale Scott; Paris, Jennifer; Himes, Michael L; Douaihy, Antoine B; Frankle, W Gordon

    2014-08-01

    Basic studies have demonstrated that optimal levels of prefrontal cortical dopamine are critical to various executive functions such as working memory, attention, inhibitory control, and risk/reward decisions, all of which are impaired in addictive disorders such as alcoholism. Based on this and imaging studies of alcoholism that have demonstrated less dopamine in the striatum, the authors hypothesized decreased dopamine transmission in the prefrontal cortex in persons with alcohol dependence. To test this hypothesis, amphetamine and [11C]FLB 457 positron emission tomography were used to measure cortical dopamine transmission in 21 recently abstinent persons with alcohol dependence and 21 matched healthy comparison subjects. [11C]FLB 457 binding potential, specific compared to nondisplaceable uptake (BPND), was measured in subjects with kinetic analysis using the arterial input function both before and after 0.5 mg kg-1 of d-amphetamine. Amphetamine-induced displacement of [11C]FLB 457 binding potential (ΔBPND) was significantly smaller in the cortical regions in the alcohol-dependent group compared with the healthy comparison group. Cortical regions that demonstrated lower dopamine transmission in the alcohol-dependent group included the dorsolateral prefrontal cortex, medial prefrontal cortex, orbital frontal cortex, temporal cortex, and medial temporal lobe. The results of this study, for the first time, unambiguously demonstrate decreased dopamine transmission in the cortex in alcoholism. Further research is necessary to understand the clinical relevance of decreased cortical dopamine as to whether it is related to impaired executive function, relapse, and outcome in alcoholism.

  2. Stereoselectivity of presynaptic autoreceptors modulating dopamine release.

    PubMed

    Arbilla, S; Langer, S Z

    1981-12-17

    The effects of the (R)- and (S)-enantiomers of sulpiride and butaclamol were studied on the spontaneous and field stimulation-evoked release of total radioactivity from slices of rabbit caudate nucleus prelabelled with [3H]dopamine. (S)-Sulpiride in concentrations ranging from 0.01--1 microM enhanced the electrically evoked release of [3H]dopamine while (R)-sulpiride was 10 times less potent than (S)-sulpiride. Exposure to (S)-butaclamol (0.01--1 microM) but not to (R)-butaclamol (0.1--10 microM) enhanced the field-stimulated release of [3H]dopamine. The facilitatory effects of (S)- and (R)-sulpiride and (S)-butaclamol on the stimulated release of the labelled neurotransmitter were observed under conditions in which these drugs did not modify the spontaneous outflow of radioactivity. Only the active enantiomers of sulpiride and butaclamol antagonized the inhibition by apomorphine (1 microM) of the stimulated release of [3H]dopamine. Our results indicate that the presynaptic inhibitory dopamine autoreceptors modulating the stimulation-evoked release of [3H]dopamine in the caudate nucleus are, like the classical postsynaptic dopamine receptors, chemically stereoselective.

  3. Induction of dopamine D1 and D5 receptors in R28 cells by light exposures.

    PubMed

    Ke, Yan; Li, Wentao; Tan, Zhiqun; Yang, Zhikuan

    2017-05-06

    Dopamine is known to play an important role in the pathophysiological process of myopia development relevant to the ambient lighting, but it is still poorly understood about how lighting regulates dopamine and its interaction with dopamine receptors to mediate the pathogenic signal transduction leading to alterations of ocular globe and the pathogenesis of myopia. Many studies have highlighted changes of ocular dopamine amount in response to different lighting conditions, but little attention has been paid to the dopamine receptors during these processes. Here we examined the effects of different lighting exposures on the expression of dopamine receptors in rat R28 retinal precursor cells. R28 cells normally grown in dark were exposed to a low (10 lux) or high (500 lux) intensity of a source of LED white light (5000 K-6000 K) for 12 h and total RNA was isolated either immediately or after certain time continuous growing in dark. Both conventional and real-time RT-PCR were performed to determine the expression of all five different dopamine receptors in cells after treatments. While the transcripts of dopamine D2, D3, and D4 receptors were not detected in the total RNA preparations of all the cells, those of D1 and D5 receptors (DRD1 and DRD5) were induced by lighting in contrast to the dark control. Elevated levels of DRD1 and DRD5 mRNA returned back close to the original levels once the cells were maintained in dark after light exposures. Immunofluorescence microscopy using a specific antibody confirmed an increase in the immunoreactivity of DRD1 in the cells exposed to 500 lux lighting versus dark control. Notably, treatments of R28 cells with nanomolar dosages of dopamine (0-500 nM) directly downregulated expression of both DRD1 and DRD5, whereas haloperidol (0-50 nM), a DRD2 antagonist, significantly induced expression of DRD1. These results suggest that dopamine receptors in the retinal cells might actively respond to the environmental lighting to act as

  4. Prenatal Ethanol Exposure Persistently Alters Endocannabinoid Signaling and Endocannabinoid-Mediated Excitatory Synaptic Plasticity in Ventral Tegmental Area Dopamine Neurons.

    PubMed

    Hausknecht, Kathryn; Shen, Ying-Ling; Wang, Rui-Xiang; Haj-Dahmane, Samir; Shen, Roh-Yu

    2017-06-14

    Prenatal ethanol exposure (PE) leads to increased addiction risk which could be mediated by enhanced excitatory synaptic strength in ventral tegmental area (VTA) dopamine (DA) neurons. Previous studies have shown that PE enhances excitatory synaptic strength by facilitating an anti-Hebbian form of long-term potentiation (LTP). In this study, we investigated the effect of PE on endocannabinoid-mediated long-term depression (eCB-LTD) in VTA DA neurons. Rats were exposed to moderate (3 g/kg/d) or high (6 g/kg/d) levels of ethanol during gestation. Whole-cell recordings were conducted in male offspring between 4 and 10 weeks old.We found that PE led to increased amphetamine self-administration. Both moderate and high levels of PE persistently reduced low-frequency stimulation-induced eCB-LTD. Furthermore, action potential-independent glutamate release was regulated by tonic eCB signaling in PE animals. Mechanistic studies for impaired eCB-LTD revealed that PE downregulated CB1 receptor function. Interestingly, eCB-LTD in PE animals was rescued by metabotropic glutamate receptor I activation, suggesting that PE did not impair the synthesis/release of eCBs. In contrast, eCB-LTD in PE animals was not rescued by increasing presynaptic activity, which actually led to LTP in PE animals, whereas LTD was still observed in controls. This result shows that the regulation of excitatory synaptic plasticity is fundamentally altered in PE animals. Together, PE leads to impaired eCB-LTD at the excitatory synapses of VTA DA neurons primarily due to CB1 receptor downregulation. This effect could contribute to enhanced LTP and the maintenance of augmented excitatory synaptic strength in VTA DA neurons and increased addiction risk after PE.SIGNIFICANCE STATEMENT Prenatal ethanol exposure (PE) is among many adverse developmental factors known to increase drug addiction risk. Increased excitatory synaptic strength in VTA DA neurons is a critical cellular mechanism for addiction risk. Our

  5. Dopamine receptor-interacting proteins: the Ca(2+) connection in dopamine signaling.

    PubMed

    Bergson, Clare; Levenson, Robert; Goldman-Rakic, Patricia S; Lidow, Michael S

    2003-09-01

    Abnormal activity of the dopamine system has been implicated in several psychiatric and neurological illnesses; however, lack of knowledge about the precise sites of dopamine dysfunction has compromised our ability to improve the efficacy and safety of dopamine-related drugs used in treatment modalities. Recent work suggests that dopamine transmission is regulated via the concerted efforts of a cohort of cytoskeletal, adaptor and signaling proteins called dopamine receptor-interacting proteins (DRIPs). The discovery that two DRIPs, calcyon and neuronal Ca(2+) sensor 1 (NCS-1), are upregulated in schizophrenia highlights the possibility that altered protein interactions and defects in Ca(2+) homeostasis might contribute to abnormalities in the brain dopamine system in neuropsychiatric diseases.

  6. Human dopamine receptor and its uses

    DOEpatents

    Civelli, Olivier; Van Tol, Hubert Henri-Marie

    1999-01-01

    The present invention is directed toward the isolation, characterization and pharmacological use of the human D4 dopamine receptor. The nucleotide sequence of the gene corresponding to this receptor and alleleic variant thereof are provided by the invention. The invention also includes recombinant eukaryotic expression constructs capable of expressing the human D4 dopamine receptor in cultures of transformed eukaryotic cells. The invention provides cultures of transformed eukaryotic cells which synthesize the human D4 dopamine receptor, and methods for characterizing novel psychotropic compounds using such cultures.

  7. Stress in adolescence and drugs of abuse in rodent models: Role of dopamine, CRF, and HPA axis

    PubMed Central

    Burke, Andrew R.; Miczek, Klaus A.

    2014-01-01

    Rationale Research on adolescence and drug abuse increased substantially in the past decade. However, drug-addiction related behaviors following stressful experiences during adolescence are less studied. We focus on rodent models of adolescent stress cross-sensitization to drugs of abuse. Objectives Review the ontogeny of behavior, dopamine, corticotropin-releasing factor (CRF), and the hypothalamic pituitary adrenal (HPA) axis in adolescent rodents. We evaluate evidence that stressful experiences during adolescence engender hypersensitivity to drugs of abuse and offer potential neural mechanisms. Results and Conclusions Much evidence suggests that final maturation of behavior, dopamine systems, and HPA axis occurs during adolescence. Stress during adolescence increases amphetamine- and ethanol-stimulated locomotion, preference, and self-administration under many conditions. The influence of adolescent stress on subsequent cocaine- and nicotine-stimulated locomotion and preference is less clear. The type of adolescent stress, temporal interval between stress and testing, species, sex, and the drug tested are key methodological determinants for successful cross-sensitization procedures. The sensitization of the mesolimbic dopamine system is proposed to underlie stress cross-sensitization to drugs of abuse in both adolescents and adults through modulation by CRF. Reduced levels of mesocortical dopamine appear to be a unique consequence of social stress during adolescence. Adolescent stress may reduce the final maturation of cortical dopamine through D2 dopamine receptor regulation of dopamine synthesis or glucocorticoid-facilitated pruning of cortical dopamine fibers. Certain rodent models of adolescent adversity are useful for determining neural mechanisms underlying the cross-sensitization to drugs of abuse. PMID:24370534

  8. MAOA-VNTR polymorphism modulates context-dependent dopamine release and aggressive behavior in males.

    PubMed

    Schlüter, Thorben; Winz, Oliver; Henkel, Karsten; Eggermann, Thomas; Mohammadkhani-Shali, Siamak; Dietrich, Claudia; Heinzel, Alexander; Decker, Michel; Cumming, Paul; Zerres, Klaus; Piel, Markus; Mottaghy, Felix M; Vernaleken, Ingo

    2016-01-15

    A recent [(18)F]FDOPA-PET study reports negative correlations between dopamine synthesis rates and aggressive behavior. Since dopamine is among the substrates for monoamine oxidase A (MAOA), this investigation examines whether functional allelic variants of the MAOA tandem repeat (VNTR) promotor polymorphism, which is known to modulate aggressive behavior, influences dopamine release and aggression in response to violent visual stimuli. We selected from a genetic prescreening sample, strictly case-matched groups of 2×12 healthy male subjects with VNTRs predictive of high (MAOA-High) and low (MAOA-Low) MAOA expression. Subjects underwent pairs of PET sessions (dopamine D2/3 ligand [(18)F]DMFP) while viewing a movie of neutral content, versus violent content. Directly afterwards, aggressive behavior was assessed by the Point Subtraction Aggression Paradigm (PSAP). Finally, PET data of 23 participants and behavioral data of 22 participants were analyzed due to post hoc exclusion criteria. In the genetic prescreening sample MAOA-Low carriers had significantly increased scores on the Buss-Perry Aggression Questionnaire. In the PET-study-group, aggressive behavior under the emotional neutral condition was significantly higher in the MAOA-Low group. Interestingly, the two MAOA-groups showed inverse dopaminergic and behavioral reactions to the violent movie: The MAOA-High group showed higher dopamine release and increased aggression after the violent movie; MAOA-Low subjects showed decreases in aggressive behavior and no consistent dopamine release. These results indicate a possible impact of the MAOA-promotor polymorphism on the neurobiological modulation of aggressive behavior. However, the data do not support approaches stating that MAOA-Low fosters aggression by a simple pro-dopaminergic mechanism.

  9. Autoradiographic localization of benzodiazepine receptor downregulation

    SciTech Connect

    Tietz, E.I.; Rosenberg, H.C.; Chiu, T.H.

    1986-01-01

    Regional differences in downregulation of brain benzodiazepine receptors were studied using a quantitative autoradiographic method. Rats were given a 4-week flurazepam treatment known to cause tolerance and receptor downregulation. A second group of rats was given a similar treatment, but for only 1 week. A third group was given a single acute dose of diazepam to produce a brain benzodiazepine-like activity equivalent to that found after the chronic treatment. Areas studied included hippocampal formation, cerebral cortex, superior colliculus, substantia nigra, dorsal geniculate nucleus, lateral amygdala and lateral hypothalamus. There was a regional variation in the degree of downregulation after 1 week of flurazepam treatment, ranging from 12% to 25%. Extending the flurazepam treatment to 4 weeks caused little further downregulation in those areas studied, except for the pars reticulata of the substantia nigra, which showed a 13% reduction in (/sup 3/H)flunitrazepam binding after 1 week and a 40% reduction after 4 weeks of treatment. In a few areas, such as the lateral hypothalamus, no significant change in binding was found after 4 weeks. Acute diazepam treatment caused no change in binding. This latter finding as well as results obtained during the development of the methodology show that downregulation was not an artifact due to residual drug content of brain slices. The regional variations in degree and rate of downregulation suggest areas that may be most important for benzodiazepine tolerance and dependence and may be related to the varying time courses for tolerance to different benzodiazepine actions.

  10. Phasic dopamine release in appetitive behaviors and drug abuse

    PubMed Central

    Wanat, Matthew J.; Willuhn, Ingo; Clark, Jeremy J.; Phillips, Paul E. M.

    2010-01-01

    Short phasic bursts of neuronal activity in dopamine neurons produce rapid and transient increases in extracellular dopamine concentrations throughout the mesocorticolimbic system, which are associated with the initiation of goal-directed behaviors. It is well established that acute exposure to many addictive drugs produce increases in tonic dopamine levels that occur on the order of minutes. However, recent studies suggest that abused drugs similarly enhance phasic dopamine release events that occur on a subsecond time scale. Furthermore, drug experience modulates the synaptic and intrinsic properties of dopamine neurons, which could affect dopamine burst firing and phasic dopamine release. This review will provide a general introduction to the mesolimbic dopamine system, as well as the primary methods used to detect dopamine neurons and dopamine release. We present the role of phasic dopamine release in appetitive behaviors in the context of contemporary theories regarding the function of dopamine. Next we discuss the known drug-induced changes to dopamine neurons and phasic release in both in vitro and in vivo preparations. Finally, we offer a simple model that chronic drug experience attenuates tonic/basal dopamine levels but promotes phasic dopamine release, which may result in aberrant goal-directed behaviors contributing to the development of addiction. PMID:19630749

  11. Environment- and activity-dependent dopamine neurotransmitter plasticity in the adult substantia nigra.

    PubMed

    Aumann, Tim D

    2016-04-01

    The ability of neurons to change the amount or type of neurotransmitter they use, or 'neurotransmitter plasticity', is an emerging new form of adult brain plasticity. For example, it has recently been shown that neurons in the adult rat hypothalamus up- or down-regulate dopamine (DA) neurotransmission in response to the amount of light the animal receives (photoperiod), and that this in turn affects anxiety- and depressive-like behaviors (Dulcis et al., 2013). In this Chapter I consolidate recent evidence from my laboratory suggesting neurons in the adult mouse substantia nigra pars compacta (SNc) also undergo DA neurotransmitter plasticity in response to persistent changes in their electrical activity, including that driven by the mouse's environment or behavior. Specifically, we have shown that the amounts of tyrosine hydroxylase (TH, the rate-limiting enzyme in DA synthesis) gene promoter activity, TH mRNA and TH protein in SNc neurons increases or decreases after ∼20h of altered electrical activity. Also, infusion of ion-channel agonists or antagonists into the midbrain for 2 weeks results in ∼10% (∼500 neurons) more or fewer TH immunoreactive (TH+) SNc neurons, with no change in the total number of SNc neurons (TH+ and TH-). Targeting ion-channels mediating cell-autonomous pacemaker activity in, or synaptic input and afferent pathways to, SNc neurons are equally effective in this regard. In addition, exposing mice to different environments (sex pairing or environment enrichment) for 1-2 weeks induces ∼10% more or fewer TH+ SNc (and ventral tegmental area or VTA) neurons and this is abolished by concurrent blockade of synaptic transmission in midbrain. Although further research is required to establish SNc (and VTA) DA neurotransmitter plasticity, and to determine whether it alters brain function and behavior, it is an exciting prospect because: (1) It may play important roles in movement, motor learning, reward, motivation, memory and cognition; and (2

  12. Delusions, superstitious conditioning and chaotic dopamine neurodynamics.

    PubMed

    Shaner, A

    1999-02-01

    Excessive mesolimbic dopaminergic neurotransmission is closely related to the psychotic symptoms of schizophrenia. A mathematical model of dopamine neuron firing rates, developed by King and others, suggests a mechanism by which excessive dopaminergic transmission could produce psychotic symptoms, especially delusions. In this model, firing rates varied chaotically when the efficacy of dopaminergic transmission was enhanced. Such non-contingent changes in firing rates in mesolimbic reward pathways could produce delusions by distorting thinking in the same way that non-contingent reinforcement produces superstitious conditioning. Though difficult to test in humans, the hypothesis is testable as an explanation for a common animal model of psychosis--amphetamine stereotypy in rats. The hypothesis predicts that: (1) amphetamine will cause chaotic firing rates in mesolimbic dopamine neurons; (2) non-contingent brain stimulation reward will produce stereotypy; (3) non-contingent microdialysis of dopamine into reward areas will produce stereotypy; and (4) dopamine antagonists will block all three effects.

  13. Purification of brain D2 dopamine receptor.

    PubMed Central

    Williamson, R A; Worrall, S; Chazot, P L; Strange, P G

    1988-01-01

    D2 dopamine receptors have been extracted from bovine brain using the detergent cholate and purified approximately 20,000-fold by affinity chromatography on haloperidol-sepharose and wheat germ agglutinin-agarose columns. The purified preparation contains D2 dopamine receptors as judged by the pharmacological specificity of [3H]spiperone binding to the purified material. The sp. act. of [3H]spiperone binding in the purified preparation is 2.5 nmol/mg protein. The purified preparation shows a major diffuse band at Mr 95,000 upon SDS-polyacrylamide gel electrophoresis and there is evidence for microheterogeneity either at the protein or glycosylation level. Photoaffinity labelling of D2 dopamine receptors also shows a species of Mr 95,000. The D2 dopamine receptor therefore is a glycoprotein of Mr 95,000. Images PMID:3243275

  14. Detection of Dopamine Dynamics in the Brain.

    ERIC Educational Resources Information Center

    Wightman, R. Mark; And Others

    1988-01-01

    Explores neurochemical events in the extra cellular space of the brain by use of in vivo voltammetric microelectrodes. Reports dopamine concentrations and pathways, and discusses techniques used for analysis. Recognizes current problems and future directions for research. (ML)

  15. Dopamine-oxytocin interactions in penile erection.

    PubMed

    Baskerville, T A; Allard, J; Wayman, C; Douglas, A J

    2009-12-03

    Dopamine and oxytocin have established roles in the central regulation of penile erection in rats; however, the neural circuitries involved in a specific erectile context and the interaction between dopamine and oxytocin mechanisms remain to be elucidated. The medial preoptic area (MPOA), supraoptic nucleus (SON) and paraventricular nucleus (PVN) of the hypothalamus may serve as candidate sites because they contain oxytocin cells, receive dopaminergic inputs and have been implicated in mediating masculine sexual behavior. Double immunofluorescence revealed that substantial numbers of oxytocin cells in the MPOA, SON and PVN possess dopamine D(2), D(3) and D(4) receptors. In anaesthetized rats, using intracavernous pressure as a physiological indicator of erection, blockade of lumbosacral oxytocin receptors (UK, 427843) reduced erectile responses to a nonselective dopamine agonist (apomorphine), suggesting that dopamine recruits a paraventriculospinal oxytocin pathway. In conscious males in the absence of a female, penile erection elicited by a D(2)/D(3) (Quinelorane) but not D(4) (PD168077) agonist was associated with activation of medial parvocellular PVN oxytocin cells. In another experiment where males were given full access to a receptive female, a D(4) (L-745870) but not D(2) or D(3) antagonist (L-741626; nafadotride) inhibited penile erection (intromission), and this was correlated with SON magnocellular oxytocin neuron activation. Together, the data suggest dopamine's effects on hypothalamic oxytocin cells during penile erection are context-specific. Dopamine may act via different parvocellular and magnocellular oxytocin subpopulations to elicit erectile responses, depending upon whether intromission is performed. This study demonstrates the potential existence of interaction between central dopamine and oxytocin pathways during penile erection, with the SON and PVN serving as integrative sites.

  16. A model of dopamine modulated glutamatergic synapse.

    PubMed

    Di Maio, Vito; Ventriglia, Francesco; Santillo, Silvia

    2015-10-01

    The dopamine neurotransmitter regulates important neural pathways and its action in the brain is very complex. When dopaminergic neurons make synapses on spiny neurons of the striatum nucleus, they tune the responsiveness of glutamatergic synapses by means of the dopamine D1 and D2 receptors. We studied the effect of dopamine D1 receptors on glutamatergic synapse of GABAergic spiny neurons in striatum nucleus where they are located on the neck of the same spine. The action of dopamine consists essentially in promoting the phosphorylation of AMPA and NMDA receptors thus increasing the Excitatory Post Synaptic Current peak amplitude. The consequence is a cooperative effect of glutamatergic and dopaminergic synapses for the regulation of the GABAergic neuronal code. The mechanisms by which the phosphorylation induces the increase of the EPSC amplitude still remain unclear although the lack of this regulation can be involved in several pathologies as, for example, the Parkinson's disease. We tested, by computational experiments based on our model of glutamatergic synapse, three parameters of the synaptic function that could be involved in dopamine action: (a) time binding of glutamate to receptors; (b) open probability of the receptors; and (c) single receptor conductance. For different reasons, any of the three parameters could be responsible of the increased EPSC-dopamine-dependent. Our computational results were compared and discussed with experimental results found in literature. Although for our model both the open probability and the single receptor conductance can reproduce the phosphorylation effect of dopamine, we argue that the dopamine effect consists essentially in an increase of the single receptor conductance due to a 3D rearrangement of the phosphorylated receptors.

  17. Is schizophrenia a dopamine supersensitivity psychotic reaction?

    PubMed

    Seeman, Mary V; Seeman, Philip

    2014-01-03

    Adolf Meyer (1866-1950) did not see schizophrenia as a discrete disorder with a specific etiology but, rather, as a reaction to a wide variety of biopsychosocial factors. He may have been right. Today, we have evidence that gene mutations, brain injury, drug use (cocaine, amphetamine, marijuana, phencyclidine, and steroids), prenatal infection and malnutrition, social isolation and marginalization, can all result in the signs and symptoms of schizophrenia. This clinical picture is generally associated with supersensitivity to dopamine, and activates dopamine neurotransmission that is usually alleviated or blocked by drugs that block dopamine D2 receptors. While the dopamine neural pathway may be a final common route to many of the clinical symptoms, the components of this pathway, such as dopamine release and number of D2 receptors, are approximately normal in schizophrenia patients who are in remission. Postmortem findings, however, reveal more dimers of D1D2 and D2D2 receptors in both human schizophrenia brains and in animal models of schizophrenia. Another finding in animal models is an elevation of high-affinity state D2High receptors, but no radioactive ligand is yet available to selectively label D2High receptors in humans. It is suggested that synaptic dopamine supersensitivity in schizophrenia is an attempt at compensation for the original damage by heightening dopamine neurotransmission pathways (preparing the organism for fight or flight). The dopamine overactivity is experienced subjectively as overstimulation, which accounts for some of the clinical symptoms, with attempts at dampening down the stimulation leading to still other symptoms. Reaction and counter-reaction may explain the symptoms of schizophrenia. © 2013. Published by Elsevier Inc. All rights reserved.

  18. Effects of Modafinil on Dopamine and Dopamine Transporters in the Male Human Brain: Clinical Implications

    PubMed Central

    Volkow, Nora D.; Fowler, Joanna S.; Logan, Jean; Alexoff, David; Zhu, Wei; Telang, Frank; Wang, Gene-Jack; Jayne, Millard; Hooker, Jacob M.; Wong, Christopher; Hubbard, Barbara; Carter, Pauline; Warner, Donald; King, Payton; Shea, Colleen; Xu, Youwen; Muench, Lisa; Apelskog-Torres, Karen

    2009-01-01

    Context Modafinil, a wake-promoting drug used to treat narcolepsy, is increasingly being used as a cognitive enhancer. Although initially launched as distinct from stimulants that increase extracellular dopamine by targeting dopamine transporters, recent preclinical studies suggest otherwise. Objective To measure the acute effects of modafinil at doses used therapeutically (200 mg and 400 mg given orally) on extracellular dopamine and on dopamine transporters in the male human brain. Design, Setting, and Participants Positron emission tomography with [11C]raclopride (D2/D3 radioligand sensitive to changes in endogenous dopamine) and [11C]cocaine (dopamine transporter radioligand) was used to measure the effects of modafinil on extracellular dopamine and on dopamine transporters in 10 healthy male participants. The study took place over an 8-month period (2007–2008) at Brookhaven National Laboratory. Main Outcome Measures Primary outcomes were changes in dopamine D2/D3 receptor and dopamine transporter availability (measured by changes in binding potential) after modafinil when compared with after placebo. Results Modafinil decreased mean (SD) [11C]raclopride binding potential in caudate (6.1% [6.5%]; 95% confidence interval [CI], 1.5% to 10.8%; P=.02), putamen (6.7% [4.9%]; 95% CI, 3.2% to 10.3%; P=.002), and nucleus accumbens (19.4% [20%]; 95% CI, 5% to 35%; P=.02), reflecting increases in extracellular dopamine. Modafinil also decreased [11C]cocaine binding potential in caudate (53.8% [13.8%]; 95% CI, 43.9% to 63.6%; P<.001), putamen (47.2% [11.4%]; 95% CI, 39.1% to 55.4%; P<.001), and nucleus accumbens (39.3% [10%]; 95% CI, 30% to 49%; P=.001), reflecting occupancy of dopamine transporters. Conclusions In this pilot study, modafinil blocked dopamine transporters and increased dopamine in the human brain (including the nucleus accumbens). Because drugs that increase dopamine in the nucleus accumbens have the potential for abuse, and considering the increasing

  19. Long-term studies of dopamine agonists.

    PubMed

    Hubble, Jean P

    2002-02-26

    Dopamine agonists have long been used as adjunctive therapy for the treatment of Parkinson's disease (PD). In more recent years these drugs have also been proved safe and effective as initial therapy in lieu of levodopa in the treatment of PD. Long-term levodopa therapy is associated with motor complications, including fluctuating response patterns and dyskinesia. By initially introducing a dopamine agonist as symptomatic drug therapy, it may be possible to postpone the use of levodopa and delay or prevent the development of motor complications. Recently, four clinical trials have explored this hypothesis by comparing the long-term response and side effects of levodopa with dopamine agonist therapy. The drugs studied have included ropinirole, pramipexole, cabergoline, and pergolide. In each of these projects, the occurrence of motor complications, such as wearing off and dyskinesia, was significantly less in the subjects assigned to initiation of therapy with a dopamine agonist. The addition of levodopa could be postponed by many months or even several years. Therefore, these long-term studies of dopamine agonists support the initiation of a dopamine agonist instead of levodopa in an effort to postpone levodopa-related motor complications. This therapeutic approach may be particularly appropriate in PD patients with a long treatment horizon on the basis of age and general good health. The extension phase of the long-term study comparing pramipexole with levodopa is ongoing, and follow-up information may help to establish the value of this treatment strategy.

  20. Tonic Dopamine Modulates Exploitation of Reward Learning

    PubMed Central

    Beeler, Jeff A.; Daw, Nathaniel; Frazier, Cristianne R. M.; Zhuang, Xiaoxi

    2010-01-01

    The impact of dopamine on adaptive behavior in a naturalistic environment is largely unexamined. Experimental work suggests that phasic dopamine is central to reinforcement learning whereas tonic dopamine may modulate performance without altering learning per se; however, this idea has not been developed formally or integrated with computational models of dopamine function. We quantitatively evaluate the role of tonic dopamine in these functions by studying the behavior of hyperdopaminergic DAT knockdown mice in an instrumental task in a semi-naturalistic homecage environment. In this “closed economy” paradigm, subjects earn all of their food by pressing either of two levers, but the relative cost for food on each lever shifts frequently. Compared to wild-type mice, hyperdopaminergic mice allocate more lever presses on high-cost levers, thus working harder to earn a given amount of food and maintain their body weight. However, both groups show a similarly quick reaction to shifts in lever cost, suggesting that the hyperdominergic mice are not slower at detecting changes, as with a learning deficit. We fit the lever choice data using reinforcement learning models to assess the distinction between acquisition and expression the models formalize. In these analyses, hyperdopaminergic mice displayed normal learning from recent reward history but diminished capacity to exploit this learning: a reduced coupling between choice and reward history. These data suggest that dopamine modulates the degree to which prior learning biases action selection and consequently alters the expression of learned, motivated behavior. PMID:21120145

  1. Pharmacological characterization of renal vascular dopamine receptors.

    PubMed

    Schmidt, M; Imbs, J L

    1980-01-01

    We present an in vitro method for studying the renal effects of dopamine in the isolated rat kidney. The organ is perfused in an open circuit and can be maintained satisfactorily for up to 180 min. The responses to dopamine were studied in the presence of phenoxybenzamine (10(-5) M) and sotalol (10(-5) M) while stable renal vasoconstriction was maintained by perfusion with prostaglandine F2 alpha. Dopamine induced dose-dependent renal vasodilation with an ED50 of 2.53 X 10(-6) moles/liter, which was not modified by reserpine pretreatment. (+) Butaclamol but not (-) butaclamol shifted the dopamine dose-response curve to the right in a parallel fashion, indicating competitive antagonism. Haloperidol and sulpiride at concentrations without intrinsic effect on vascular resistance also acted as competitive inhibitors for dopamine. Calculation of empirical pA2 values yielded the following relative potencies for these antagonists: (+) butaclamol greater than haloperidol greater than sulpiride. The renal vascular dopamine receptors are tentatively classified as being of the D1 type.

  2. The Effects of Acute Dopamine Precursor Depletion on the Reinforcing Value of Exercise in Anorexia Nervosa.

    PubMed

    O'Hara, Caitlin B; Keyes, Alexandra; Renwick, Bethany; Leyton, Marco; Campbell, Iain C; Schmidt, Ulrike

    2016-01-01

    This study investigated whether dopaminergic systems are involved in the motivation to engage in behaviours associated with anorexia nervosa (AN), specifically, the drive to exercise. Women recovered from AN (AN REC, n = 17) and healthy controls (HC, n = 15) were recruited. The acute phenylalanine/tyrosine depletion (APTD) method was used to transiently decrease dopamine synthesis and transmission. The effect of dopamine precursor depletion on drive to exercise was measured using a progressive ratio (PR) exercise breakpoint task. Both groups worked for the opportunity to exercise, and, at baseline, PR breakpoint scores were higher in AN REC than HC. Compared to values on the experimental control session, APTD did not decrease PR breakpoint scores in AN REC, but significantly decreased scores in HC. These data show that women recovered from AN are more motivated to exercise than HC, although in both groups, activity is more reinforcing than inactivity. Importantly, decreasing dopamine does not reduce the motivation to exercise in people recovered from AN, but in contrast, does so in HC. It is proposed that in AN, drive to exercise develops into a behaviour that is largely independent of dopamine mediated reward processes and becomes dependent on cortico-striatal neurocircuitry that regulates automated, habit- or compulsive-like behaviours. These data strengthen the case for the involvement of reward, learning, habit, and dopaminergic systems in the aetiology of AN.

  3. The Effects of Acute Dopamine Precursor Depletion on the Reinforcing Value of Exercise in Anorexia Nervosa

    PubMed Central

    O’Hara, Caitlin B.; Keyes, Alexandra; Renwick, Bethany; Leyton, Marco; Campbell, Iain C.; Schmidt, Ulrike

    2016-01-01

    This study investigated whether dopaminergic systems are involved in the motivation to engage in behaviours associated with anorexia nervosa (AN), specifically, the drive to exercise. Women recovered from AN (AN REC, n = 17) and healthy controls (HC, n = 15) were recruited. The acute phenylalanine/tyrosine depletion (APTD) method was used to transiently decrease dopamine synthesis and transmission. The effect of dopamine precursor depletion on drive to exercise was measured using a progressive ratio (PR) exercise breakpoint task. Both groups worked for the opportunity to exercise, and, at baseline, PR breakpoint scores were higher in AN REC than HC. Compared to values on the experimental control session, APTD did not decrease PR breakpoint scores in AN REC, but significantly decreased scores in HC. These data show that women recovered from AN are more motivated to exercise than HC, although in both groups, activity is more reinforcing than inactivity. Importantly, decreasing dopamine does not reduce the motivation to exercise in people recovered from AN, but in contrast, does so in HC. It is proposed that in AN, drive to exercise develops into a behaviour that is largely independent of dopamine mediated reward processes and becomes dependent on cortico-striatal neurocircuitry that regulates automated, habit- or compulsive-like behaviours. These data strengthen the case for the involvement of reward, learning, habit, and dopaminergic systems in the aetiology of AN. PMID:26808920

  4. Physiological role of peroxisome proliferator-activated receptors type α on dopamine systems.

    PubMed

    Melis, Miriam; Carta, Gianfranca; Pistis, Marco; Banni, Sebastiano

    2013-02-01

    The discovery that N-acylethanolamines, such as oleoylethanolamide (OEA) and palmitoylethanolamide (PEA), acting as endogenous ligands of alpha-type peroxisome proliferator-activated receptors (PPARα), block nicotine-induced excitation of dopamine neurons revealed their role as important endogenous negative modulators of nicotinic receptors containing β2 subunits (denoted β2*-nAChRs) on dopamine neurons, which are key to the brain reward system. Using mass-spectrometry data analysis from rodent brain slices containing the midbrain, we characterized the effects induced by modulation of PPARα on PEA and OEA levels. PEA and OEA constitutive levels in the midbrain are higher than endocannabinoids (e.g. anandamide, 2-arachidonoylglycerol), and depend upon excessive input drive and the metabolic state of the cells. Accordingly, OEA and PEA synthesis is affected when adding low concentrations of fatty acids (endogenous PPARα ligands), most likely through activation of PPARα. Indeed, PPARα activation increases PEA and OEA levels, which may further sustain PPARα activity. Given this, it is likely that these molecules dynamically affect dopamine function and excitability, as well as their dependent behaviour. Consequently, N-acylethanolamines may confer less vulnerability towards disruption of dynamic balance of dopamine-acetylcholine systems through PPARα activation. Finally, using pharmacological and/or nutritional strategies which target PPARα might represent a promising therapeutic approach to prevent disorders often related to neuro-inflammation, stress and abnormal β2*-nAChR function.

  5. Dopamine-first’ mechanism enables the rational engineering of the norcoclaurine synthase aldehyde activity profile

    PubMed Central

    Lichman, Benjamin R; Gershater, Markus C; Lamming, Eleanor D; Pesnot, Thomas; Sula, Altin; Keep, Nicholas H; Hailes, Helen C; Ward, John M

    2015-01-01

    Norcoclaurine synthase (NCS) (EC 4.2.1.78) catalyzes the Pictet–Spengler condensation of dopamine and an aldehyde, forming a substituted (S)-tetrahydroisoquinoline, a pharmaceutically important moiety. This unique activity has led to NCS being used for both in vitro biocatalysis and in vivo recombinant metabolism. Future engineering of NCS activity to enable the synthesis of diverse tetrahydroisoquinolines is dependent on an understanding of the NCS mechanism and kinetics. We assess two proposed mechanisms for NCS activity: (a) one based on the holo X-ray crystal structure and (b) the ‘dopamine-first’ mechanism based on computational docking. Thalictrum flavum NCS variant activities support the dopamine-first mechanism. Suppression of the non-enzymatic background reaction reveals novel kinetic parameters for NCS, showing it to act with low catalytic efficiency. This kinetic behaviour can account for the ineffectiveness of recombinant NCS in in vivo systems, and also suggests NCS may have an in planta role as a metabolic gatekeeper. The amino acid substitution L76A, situated in the proposed aldehyde binding site, results in the alteration of the enzyme's aldehyde activity profile. This both verifies the dopamine-first mechanism and demonstrates the potential for the rational engineering of NCS activity. PMID:25620686

  6. Dual regulating effects of gastrodin on extracellular dopamine concentration in rats models of Tourette's syndrome.

    PubMed

    Zhang, Feng; Li, Anyuan

    2015-01-01

    Evaluate the dual regulating effects of gastrodin on striatal extracellular dopamine (DA) concentration in Tourette's syndrome (TS) rat models, and explore the underlying pharmacological mechanisms. Seventy Wistar rats were randomly divided into control group and TS model group. The former was intraperitoneally injected with saline (0.9%), while in the later, the rats were injected with Apomorphine (Apo) and 3,3'-iminodipropionitrile (IDPN) respectively to manipulate two kinds of TS rat models. Both Apo and IDPN induced rats were further assigned to three conditions, and the related rats were treated respectively by oral gavage with saline, gastrodin and Haloperidol (Hal). Data of stereotypy of the rats were collected. After 8 weeks, the extracellular content of DA and HVA in striatum were examined by intracerebral microdialysis and follow-up high-performance liquid chromatography (HPLC), and the expression of dopamine transporter (DAT) was probed by Western blot. Gastrodin improved the stereotyped behaviors in TS rats. Furthermore, it down-regulated the elevated striatal extracellular DA concentration in Apo-induced rats and up-regulated the decreased DA content in the rats exposed to IDPN. Meanwhile, a dramatic down-regulation was detected in DAT protein expression in Apo + GAS group, while an opposite profile was showed in the IDPN + GAS group. The dual regulating effects of gastrodin on extracellular DA level have been established, and the related mechanisms would be the dual regulating effects of gastrodin on the expression of DAT, a glycoprotein in the regulation of the extracellular DA concentration.

  7. [Study of extracellular concentration of dopamine and its metabolites in mice striatum by a microdialysis technique at intraperitoneal administration of MPTP].

    PubMed

    Averkin, R G; Korshunov, V A; Shchegolevskiĭ, N V; Mats, V N; Markevich, V A; Grigor'ian, G A; Bazian, A S

    2010-01-01

    In this paper a structure of a microdialytic cannula inserted into brain areas just before a microdialysis is described. The cannula used allowed to find out a correspondence of behavioral and biochemical changes in C57BL/6 mice at various time intervals after a single dose administration (20 mg/kg) of the neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, without any additional pharmacological actions enhancing an extracellular striatal dopamine concentration. Immediately after 1-methyl-4-phenyl-1.2,3.6-tetrahydropyridine administration an essential disturbance of mice behavior and a significant reduction of the extracellular concentration of dopamine and homovanillic acid were observed in striatum. A week after the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration neither behavior nor the extracellular dopamine and homovanillic acid striatal concentration substantially differed from those of controls. 30 days after the neurotoxin administration there was again an essential disturbance of behavior and the large reduction of dopamine and its metabolite concentration in striatum. There was suggested that a reduction of the dopamine concentration immediately after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine injection connected with abnormalities of dopamine synthesis and metabolism induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine whereas a reduction of the extracellular striatal dopamine concentration 30 days after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration related to damage of the nigrastriatal dopaminergic system.

  8. Fisetin inhibits liver cancer growth in a mouse model: Relation to dopamine receptor.

    PubMed

    Liu, Xiang-Feng; Long, Hai-Jiao; Miao, Xiong-Ying; Liu, Guo-Li; Yao, Hong-Liang

    2017-07-01

    Fisetin (3,3',4',7-tetrahydroxyflavone), a natural abundant flavonoid, is produced in different vegetables and fruits. Fisetin has been reported to relate to various positive biological effects, including anti-proliferative, anticancer, anti-oxidative and neuroprotective effects. Dopamine receptors (DRs) belonging to G protein‑coupled receptor family, are known as the target of ~50% of all modern medicinal drugs. DRs consist of various proteins, functioning as transduction of intracellular signals for extracellular stimuli. We found that fisetin performed as DR2 agonist to suppress liver cancer cells proliferation, migration and invasion. Caspase-3 signaling was activated to induce apoptosis for fisetin administration. Furthermore, TGF‑β1 was also inhibited in fisetin-treated liver cancer cells, reducing epithelial-mesenchymal transition (EMT). Additionally, fisetin downregulated VEGFR1, p-ERK1/2, p38 and pJNK, ameliorating liver cancer progression. In vivo, the orthotopically implanted tumors from mice were inhibited by fisetin adminisatration accompanied by prolonged survival rate and higher levels of dopamine. Together, the results indicated a novel therapeutic strategy to suppress liver cancer progression associated with DR2 regulation, indicating that dopamine might be of importance in liver cancer progression.

  9. Orbitofrontal Dopamine Depletion Upregulates Caudate Dopamine and Alters Behavior via Changes in Reinforcement Sensitivity

    PubMed Central

    Cardinal, R. N.; Rygula, R.; Hong, Y. T.; Fryer, T. D.; Sawiak, S. J.; Ferrari, V.; Cockcroft, G.; Aigbirhio, F. I.; Robbins, T. W.; Roberts, A. C.

    2014-01-01

    Schizophrenia is associated with upregulation of dopamine (DA) release in the caudate nucleus. The caudate has dense connections with the orbitofrontal cortex (OFC) via the frontostriatal loops, and both areas exhibit pathophysiological change in schizophrenia. Despite evidence that abnormalities in dopaminergic neurotransmission and prefrontal cortex function co-occur in schizophrenia, the influence of OFC DA on caudate DA and reinforcement processing is poorly understood. To test the hypothesis that OFC dopaminergic dysfunction disrupts caudate dopamine function, we selectively depleted dopamine from the OFC of marmoset monkeys and measured striatal extracellular dopamine levels (using microdialysis) and dopamine D2/D3 receptor binding (using positron emission tomography), while modeling reinforcement-related behavior in a discrimination learning paradigm. OFC dopamine depletion caused an increase in tonic dopamine levels in the caudate nucleus and a corresponding reduction in D2/D3 receptor binding. Computational modeling of behavior showed that the lesion increased response exploration, reducing the tendency to persist with a recently chosen response side. This effect is akin to increased response switching previously seen in schizophrenia and was correlated with striatal but not OFC D2/D3 receptor binding. These results demonstrate that OFC dopamine depletion is sufficient to induce striatal hyperdopaminergia and changes in reinforcement learning relevant to schizophrenia. PMID:24872570

  10. Strain differences of dopamine receptor levels and dopamine related behaviors in rats.

    PubMed

    Zamudio, Sergio; Fregoso, Tomás; Miranda, Abraham; De La Cruz, Fidel; Flores, Gonzalo

    2005-04-30

    Here we have investigated whether differences in levels of dopamine D1-like, D2-like receptors, dopamine D3 receptors, and dopamine transporter could be related to behaviors such as immobility response and locomotion between Wistar rats and Sprague-Dawley rats. The levels of the dopamine receptors and transporter were measured by autoradiographic study at the level of basal ganglia and the limbic subregion. The behavioral study was done by open-field and immobility response tests. The Wistar rats exhibited a higher level of D1 receptor binding in the basal ganglia subregions than Sprague-Dawley rats. The Wistar rats have higher levels of dopamine D2 receptor binding and dopamine transporter binding in the dorsolateral part of the caudate-putamen. In addition, the dopamine transporter binding were also higher in the Wistar rats than in Sprague-Dawley rats in the ventral part of the caudate-putamen and nucleus accumbens core. However, there were no differences in the level of D3 receptor binding in the limbic or basal ganglia subregions between these two strains. In Wistar rats, the duration of the immobility responses was longer and with less locomotor activity after these immobility responses compared with Sprague-Dawley rats. These data suggest that the differences in dopamine receptors in these two rat strains may in part relate to the behavioral differences reported in these two strains.

  11. Dopamine induces growth inhibition and vascular normalization through reprogramming M2-polarized macrophages in rat C6 glioma

    SciTech Connect

    Qin, Tian; Wang, Chenlong; Chen, Xuewei; Duan, Chenfan; Zhang, Xiaoyan; Zhang, Jing; Chai, Hongyan; Tang, Tian; Chen, Honglei; Yue, Jiang; Li, Ying; Yang, Jing

    2015-07-15

    Dopamine (DA), a monoamine catecholamine neurotransmitter with antiangiogenic activity, stabilizes tumor vessels in colon, prostate and ovarian cancers, thus increases chemotherapeutic efficacy. Here, in the rat C6 glioma models, we investigated the vascular normalization effects of DA and its mechanisms of action. DA (25, 50 mg/kg) inhibited tumor growth, while a precursor of DA (levodopa) prolonged the survival time of rats bearing orthotopic C6 glioma. DA improved tumor perfusion, with significant effects from day 3, and a higher level at days 5 to 7. In addition, DA decreased microvessel density and hypoxia-inducible factor-1α expression in tumor tissues, while increasing the coverage of pericyte. Conversely, an antagonist of dopamine receptor 2 (DR2) (eticlopride) but not DR1 (butaclamol) abrogated DA-induced tumor regression and vascular normalization. Furthermore, DA improved the delivery and efficacy of temozolomide therapy. Importantly, DA increased representative M1 markers (iNOS, CXCL9, etc.), while decreasing M2 markers (CD206, arginase-1, etc.). Depletion of macrophages by clodronate or zoledronic acid attenuated the effects of DA. Notably, DA treatment induced M2-to-M1 polarization in RAW264.7 cells and mouse peritoneal macrophages, and enhanced the migration of pericyte-like cells (10T1/2), which was reversed by eticlopride or DR2-siRNA. Such changes were accompanied by the downregulation of VEGF/VEGFR2 signaling. In summary, DA induces growth inhibition and vascular normalization through reprogramming M2-polarized macrophages. Thus, targeting the tumor microvasculature by DA represents a promising strategy for human glioma therapy. - Highlights: • Dopamine induces tumor growth inhibition and vascular normalization in rat C6 glioma. • Dopamine switches macrophage phenotype from M2 to M1. • Dopamine-induced vascular normalization is mediated by macrophage polarization. • Dopamine is a promising agent targeting the microvasculature in tumor

  12. Downregulation of the CCK-B receptor in pancreatic cancer cells blocks proliferation and promotes apoptosis

    PubMed Central

    Fino, Kristin K.; Matters, Gail L.; McGovern, Christopher O.; Gilius, Evan L.

    2012-01-01

    Gastrin stimulates the growth of pancreatic cancer cells through the activation of the cholecystokinin-B receptor (CCK-BR), which has been found to be overexpressed in pancreatic cancer. In this study, we proposed that the CCK-BR drives growth of pancreatic cancer; hence, interruption of CCK-BR activity could potentially be an ideal target for cancer therapeutics. The effect of CCK-BR downregulation in the human pancreatic adenocarcinoma cells was examined by utilizing specific CCK-BR-targeted RNA interference reagents. The CCK-BR receptor expression was both transiently and stably downregulated by transfection with selective CCK-BR small-interfering RNA or short-hairpin RNA, respectively, and the effects on cell growth and apoptosis were assessed. CCK-BR downregulation resulted in reduced cancer cell proliferation, decreased DNA synthesis, and cell cycle arrest as demonstrated by an inhibition of G1 to S phase progression. Furthermore, CCK-BR downregulation increased caspase-3 activity, TUNEL-positive cells, and decreased X-linked inhibitor of apoptosis protein expression, suggesting apoptotic activity. Pancreatic cancer cell mobility was decreased when the CCK-BR was downregulated, as assessed by a migration assay. These results show the importance of the CCK-BR in regulation of growth and apoptosis in pancreatic cancer. Strategies to decrease the CCK-BR expression and activity may be beneficial for the development of new methods to improve the treatment for patients with pancreatic cancer. PMID:22442157

  13. Addiction: Beyond dopamine reward circuitry

    SciTech Connect

    Volkow, N.D.; Wang, G.; Volkow, N.D.; Wang, G.-J.; Fowler, J.S.; Tomasi, D.; Telang, F.

    2011-09-13

    Dopamine (DA) is considered crucial for the rewarding effects of drugs of abuse, but its role in addiction is much less clear. This review focuses on studies that used PET to characterize the brain DA system in addicted subjects. These studies have corroborated in humans the relevance of drug-induced fast DA increases in striatum [including nucleus accumbens (NAc)] in their rewarding effects but have unexpectedly shown that in addicted subjects, drug-induced DA increases (as well as their subjective reinforcing effects) are markedly blunted compared with controls. In contrast, addicted subjects show significant DA increases in striatum in response to drug-conditioned cues that are associated with self-reports of drug craving and appear to be of a greater magnitude than the DA responses to the drug. We postulate that the discrepancy between the expectation for the drug effects (conditioned responses) and the blunted pharmacological effects maintains drug taking in an attempt to achieve the expected reward. Also, whether tested during early or protracted withdrawal, addicted subjects show lower levels of D2 receptors in striatum (including NAc), which are associated with decreases in baseline activity in frontal brain regions implicated in salience attribution (orbitofrontal cortex) and inhibitory control (anterior cingulate gyrus), whose disruption results in compulsivity and impulsivity. These results point to an imbalance between dopaminergic circuits that underlie reward and conditioning and those that underlie executive function (emotional control and decision making), which we postulate contributes to the compulsive drug use and loss of control in addiction.

  14. Dopamine, behavioral economics, and effort.

    PubMed

    Salamone, John D; Correa, Merce; Farrar, Andrew M; Nunes, Eric J; Pardo, Marta

    2009-01-01

    There are numerous problems with the hypothesis that brain dopamine (DA) systems, particularly in the nucleus accumbens, directly mediate the rewarding or primary motivational characteristics of natural stimuli such as food. Research and theory related to the functions of mesolimbic DA are undergoing a substantial conceptual restructuring, with the traditional emphasis on hedonia and primary reward yielding to other concepts and lines of inquiry. The present review is focused upon the involvement of nucleus accumbens DA in behavioral activation and effort-related processes. Viewed from the framework of behavioral economics, the effects of accumbens DA depletions and antagonism on food-reinforced behavior are highly dependent upon the work requirements of the instrumental task, and DA depleted rats are more sensitive to increases in response costs (i.e., ratio requirements). Moreover, interference with accumbens DA transmission exerts a powerful influence over effort-related choice behavior. Rats with accumbens DA depletions or antagonism reallocate their instrumental behavior away from food-reinforced tasks that have high response requirements, and instead these rats select a less-effortful type of food-seeking behavior. Nucleus accumbens DA and adenosine interact in the regulation of effort-related functions, and other brain structures (anterior cingulate cortex, amygdala, ventral pallidum) also are involved. Studies of the brain systems regulating effort-based processes may have implications for understanding drug abuse, as well as energy-related disorders such as psychomotor slowing, fatigue or anergia in depression and other neurological disorders.

  15. Dopamine, Behavioral Economics, and Effort

    PubMed Central

    Salamone, John D.; Correa, Merce; Farrar, Andrew M.; Nunes, Eric J.; Pardo, Marta

    2009-01-01

    There are numerous problems with the hypothesis that brain dopamine (DA) systems, particularly in the nucleus accumbens, directly mediate the rewarding or primary motivational characteristics of natural stimuli such as food. Research and theory related to the functions of mesolimbic DA are undergoing a substantial conceptual restructuring, with the traditional emphasis on hedonia and primary reward yielding to other concepts and lines of inquiry. The present review is focused upon the involvement of nucleus accumbens DA in behavioral activation and effort-related processes. Viewed from the framework of behavioral economics, the effects of accumbens DA depletions and antagonism on food-reinforced behavior are highly dependent upon the work requirements of the instrumental task, and DA depleted rats are more sensitive to increases in response costs (i.e., ratio requirements). Moreover, interference with accumbens DA transmission exerts a powerful influence over effort-related choice behavior. Rats with accumbens DA depletions or antagonism reallocate their instrumental behavior away from food-reinforced tasks that have high response requirements, and instead these rats select a less-effortful type of food-seeking behavior. Nucleus accumbens DA and adenosine interact in the regulation of effort-related functions, and other brain structures (anterior cingulate cortex, amygdala, ventral pallidum) also are involved. Studies of the brain systems regulating effort-based processes may have implications for understanding drug abuse, as well as energy-related disorders such as psychomotor slowing, fatigue or anergia in depression and other neurological disorders. PMID:19826615

  16. Control of extracellular dopamine at dendrite and axon terminals

    PubMed Central

    Ford, Christopher P.; Gantz, Stephanie C.; Phillips, Paul E. M.; Williams, John T.

    2010-01-01

    Midbrain dopamine neurons release dopamine from both axons and dendrites. The mechanism underlying release at these different sites has been proposed to differ. This study used electrochemical and electrophysiological methods to compare the time course and calcium-dependence of somatodendritc dopamine release in the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) to that of axonal dopamine release in the dorsal striatum. The amount of dopamine released in the striatum was ~20 fold greater than in cell body regions of the VTA or SNc. However the calcium dependence and time to peak of the dopamine transients were similar. These results illustrate an unexpected overall similarity in the mechanisms of dopamine release in the striatum and cell body regions. To examine how diffusion regulates the time course of dopamine following release, dextran was added to the extracellular solution to slow diffusion. In the VTA, dextran slowed the rate of rise and fall of the extracellular dopamine transient as measured by fast-scan cyclic voltammetry (FSCV) yet did not alter the kinetics of the dopamine dependent inhibitory post-synaptic current (IPSC). Dextran failed to significantly alter the time course of the rise and fall of the dopamine transient in the striatum suggesting a more influential role for reuptake in the striatum. The conclusion is that the time course of dopamine within the extracellular space of the VTA is dependent on both diffusion and reuptake, whereas the activation of D2-receptors on dopamine neurons is primarily limited by reuptake. PMID:20484639

  17. Genetic disruption of dopamine production results in pituitary adenomas and severe prolactinemia

    USDA-ARS?s Scientific Manuscript database

    Dopamine release from tuberoinfundibular dopamine neurons into the median eminence activates dopamine-D2 receptors in the pituitary gland where it inhibits lactotroph function. We have previously described genetic dopamine-deficient mouse models which lack the ability to synthesize dopamine. Because...

  18. The effects of administration of monoamine oxidase-B inhibitors on rat striatal neurone responses to dopamine.

    PubMed Central

    Berry, M D; Scarr, E; Zhu, M Y; Paterson, I A; Juorio, A V

    1994-01-01

    1. (-)-Deprenyl has been shown to potentiate rat striatal neurone responses to dopamine agonists at doses not altering dopamine metabolism. Since there are a number of effects of (-)-deprenyl which could result in this phenomenon, we have investigated the effects of MDL 72,145 and Ro 19-6327, whose only common effect with (-)-deprenyl is an inhibition of monoamine oxidase-B (MAO-B), on rat striatal neurone responses to dopamine and on striatal dopamine metabolism. 2. Using in vivo electrophysiology, i.p. injection of either MDL 72,145 or Ro 19-6327 was found to produce a dose-dependent potentiation of striatal neurone responses to dopamine but not gamma-aminobutyric acid. 3. Neurochemical investigations revealed that this occurred at doses (0.25-1 mg kg-1) which, while not affecting levels of dopamine or its metabolites, 3,4-dihydroxyphenylacetic acid or homovanillic acid, did cause a significant, dose-dependent, elevation in striatal levels of the putative neuromodulator, 2-phenylethylamine (PE). 4. Inhibition of PE synthesis by i.p. injection of the aromatic L-amino acid decarboxylase inhibitor, NSD 1015, produced a reversal of the effects of MDL 72,145 and Ro 19-6327. 5. Neurochemical analysis revealed this to occur at a dose of NSD 1015 (10 mg kg-1) selective for reduction of elevated PE levels. 6. These results suggest that PE can act as a neuromodulator of dopaminergic responses and that MAO-B inhibitors may potentiate neuronal responses to dopamine via the indirect mechanism of elevation of PE following MAO-B inhibition. PMID:7889269

  19. Selective Overexpression of Dopamine D3 Receptors in the Striatum Disrupts Motivation but not Cognition

    PubMed Central

    Simpson, Eleanor H.; Winiger, Vanessa; Biezonski, Dominik K.; Haq, Iram; Kandel, Eric R.; Kellendonk, Christoph

    2014-01-01

    Background Evidence indicating an increase in dopamine D2 receptor (D2R) density and occupancy in patients with schizophrenia comes from positron emission tomography studies using ligands that bind both D2Rs and dopamine D3 receptors (D3Rs), questioning the role of D3Rs in the pathophysiology of the disease. Dopamine D3 receptor positron emission tomography ligands have recently been developed and antagonists with preferential affinity for D3R versus D2R are undergoing clinical evaluation. To determine if an increase in D3Rs in the striatum could produce phenotypes relevant to schizophrenia, we generated a transgenic model of striatal D3R overexpression. Methods A bi-transgenic system was used to generate mice with increased D3Rs selectively in the striatum. Mice with overexpression of D3R were subjected to an extensive battery of behavioral tests, including several relevant to schizophrenia. Ligand binding and quantitative reverse transcription polymerase chain reaction methods were used to quantify the effect of D3R overexpression on dopamine D1 receptors (D1Rs) in the striatum. Results Mice with overexpression of D3R show no abnormalities in basic behavioral functions or cognitive tests but do display a deficit in incentive motivation. This was associated with a reduction in striatal D1R ligand binding, driven by a downregulation at the level of transcription. Both motivation and D1R expression were rescued by switching off the transgene in adulthood. Conclusions Overexpression of D3Rs in the striatum of mice does not elicit cognitive deficits but disrupts motivation, suggesting that changes in D3Rs may be involved in the negative symptoms of schizophrenia. These data imply that it will be important to evaluate the effects of D3R antagonists on motivational symptoms, which are not improved by currently available antipsychotic medications. PMID:24387821

  20. Biochemical effects of baclofen (beta-parachlorophenyl-GABA) on the dopamine and the noradrenaline in the rat brain.

    PubMed

    Andén, N E; Wachtel, H

    1977-02-01

    Baclofen (beta-parachlorophenyl-GABA) caused an increase in the concentration of dopamine in the rat brain with a maximum of about 170% of the control value after 1 hr and after doses of 50 mg/kg or more intraperitoneally. The alpha-methyltyrosine-induced disappearance of dopamine was inhibited to about the same extent in the corpus striatum and in the limbic system by baclofen. The accumulation of DOPA following decarboxylase inhibition was stimulated more in the corpus striatum than in the limbic system by baclofen, thus accounting for the fact that the concentration of dopamine was elevated about three times as much in the corpus striatum as in the limbic system. Amphetamine almost completely inhibited the rise in dopamine produced by baclofen. Baclofen did not cause any consistent changes in the concentration, the synthesis and the utilization of noradrenaline. These effects of baclofen are similar to those described following gammahydroxybutyric acid or axotomy. Hence, baclofen might also interrupt the nerve impulse flow in central dopamine neurones, perhaps by stimulating a central GABA mechanism.

  1. Fabrication of gold nanorods with tunable longitudinal surface plasmon resonance peaks by reductive dopamine.

    PubMed

    Su, Gaoxing; Yang, Chi; Zhu, Jun-Jie

    2015-01-20

    Hydroxyphenol compounds are often used as reductants in controlling the growth of nanoparticles. Herein, dopamine was used as an effective reductant in seed-mediated synthesis of gold nanorods (GNRs). The as-prepared GNRs (83 × 16 nm) were monodisperse and had a high degree of purity. The conversion ratio from gold ions to GNRs was around 80%. In addition, dopamine worked as an additive. At a very low concentration of hexadecyltrimethylammonium bromide (CTAB; 0.025 M), thinner and shorter GNRs (60 × 9 nm) were successfully prepared. By regulating the concentration of silver ions, CTAB, seeds, and reductant, GNRs with longitudinal surface plasmon resonance (LSPR) peaks ranging from 680 to 1030 nm were synthesized. The growth process was tracked using UV-vis-NIR spectroscopy, and it was found that a slow growth rate was beneficial to the formation of GNRs.

  2. Imbalance between nitric oxide and dopamine may underly aggression in acute neurological patients.

    PubMed

    Ramírez-Bermudez, J; Perez-Neri, I; Montes, S; Ramirez-Abascal, M; Nente, F; Abundes-Corona, A; Soto-Hernandez, J L; Rios, C

    2010-10-01

    The neurochemical basis of aggressive behavior in humans is not fully understood. In this study we explored the relationship between aggressiveness (as measured by the Overt Aggression Scale), cognitive performance (as measured by the Mini Mental State Examination), and biochemical markers of dopamine neurotransmission (homovanillic acid, HVA) and nitric oxide synthesis (nitrite plus nitrate, NO(x)) in cerebrospinal fluid from 70 patients with acute brain disorders, mainly brain infections. Aggressive behavior and cognitive performance showed an inverse correlation. NO(x)/HVA ratio was inversely correlated to aggressive behavior, and positively correlated to cognitive performance. A subanalysis with antipsychotic-naïve patients confirmed those results. The balance between nitric oxide and dopamine could be related to the cognitive control of aggressive impulse.

  3. Bromocryptine prevents the decline in tuberoinfundibular neuronal release of dopamine after removal of chronic estrogen treatment

    SciTech Connect

    Gottschall, P.E.; Meites, J.

    1987-11-01

    Prolonged exposure to estradiol 17-..beta.. (E/sub 2/) in rats has been shown to decrease dopamine (DA) synthesis in and release from tuberoinfundibular dopaminergic (TIDA) neurons in Fischer 344 rats. The objective of the present study was to determine whether inhibition of the E/sub 2/-induced increase in anterior pituitary (AP) weight and prolactin (PRL) secretion by concomitant administration of the dopaminergic agonist, bromocryptine, could prevent the decrease in TIDA neuronal function produced by chronic E/sub 2/ administration. TIDA neuronal function was evaluated by in vitro superfusion and electrical stimulation of median eminence (ME) tissue after allowing for accumulation of (/sup 3/H) dopamine (DA). The effect of chronic E/sub 2/ and/or bromocryptine treatment on catecholamine content in tuberohypophyseal neurons in the neurointermediate lobe was also measured to determine whether increased pituitary size possibly damaged the tuberohypophyseal neurons.

  4. Grafts of fetal dopamine neurons survive and improve motor function in Parkinson's disease

    SciTech Connect

    Lindvall, O.; Brundin, P.; Widner, H.; Rehncrona, S.; Gustavii, B.; Frackowiak, R.; Leenders, K.L.; Sawle, G.; Rothwell, J.C.; Marsden, C.D. )

    1990-02-02

    Neural transplantation can restore striatal dopaminergic neurotransmission in animal models of Parkinson's disease. It has now been shown that mesencephalic dopamine neurons, obtained from human fetuses of 8 to 9 weeks gestational age, can survive in the human brain and produce marked and sustained symptomatic relief in a patient severely affected with idiopathic Parkinson's disease. The grafts, which were implanted unilaterally into the putamen by stereotactic surgery, restored dopamine synthesis and storage in the grafted area, as assessed by positron emission tomography with 6-L-({sup 18}F)fluorodopa. This neurochemical change was accompanied by a therapeutically significant reduction in the patient's severe rigidity and bradykinesia and a marked diminuation of the fluctuations in the patient's condition during optimum medication (the on-off phenomenon). The clinical improvement was most marked on the side contralateral to the transplant.

  5. Dopamine transporter deficiency syndrome: phenotypic spectrum from infancy to adulthood

    PubMed Central

    Ng, Joanne; Zhen, Juan; Meyer, Esther; Erreger, Kevin; Li, Yan; Kakar, Naseebullah; Ahmad, Jamil; Thiele, Holger; Kubisch, Christian; Rider, Nicholas L.; Holmes Morton, D.; Strauss, Kevin A.; Puffenberger, Erik G.; D’Agnano, Daniela; Anikster, Yair; Carducci, Claudia; Hyland, Keith; Rotstein, Michael; Leuzzi, Vincenzo; Borck, Guntram; Reith, Maarten E. A.

    2014-01-01

    Dopamine transporter deficiency syndrome due to SLC6A3 mutations is the first inherited dopamine ‘transportopathy’ to be described, with a classical presentation of early infantile-onset progressive parkinsonism dystonia. In this study we have identified a new cohort of patients with dopamine transporter deficiency syndrome, including, most significantly, atypical presentation later in childhood with a milder disease course. We report the detailed clinical features, molecular genetic findings and in vitro functional investigations undertaken for adult and paediatric cases. Patients presenting with parkinsonism dystonia or a neurotransmitter profile characteristic of dopamine transporter deficiency syndrome were recruited for study. SLC6A3 mutational analysis was undertaken in all patients. The functional consequences of missense variants on the dopamine transporter were evaluated by determining the effect of mutant dopamine transporter on dopamine uptake, protein expression and amphetamine-mediated dopamine efflux using an in vitro cellular heterologous expression system. We identified eight new patients from five unrelated families with dopamine transporter deficiency syndrome. The median age at diagnosis was 13 years (range 1.5–34 years). Most significantly, the case series included three adolescent males with atypical dopamine transporter deficiency syndrome of juvenile onset (outside infancy) and progressive parkinsonism dystonia. The other five patients in the cohort presented with classical infantile-onset parkinsonism dystonia, with one surviving into adulthood (currently aged 34 years) and labelled as having ‘juvenile parkinsonism’. All eight patients harboured homozygous or compound heterozygous mutations in SLC6A3, of which the majority are previously unreported variants. In vitro studies of mutant dopamine transporter demonstrated multifaceted loss of dopamine transporter function. Impaired dopamine uptake was universally present, and more

  6. Melatonin and dopamine as biomarkers to optimize treatment in phenylketonuria: effects of tryptophan and tyrosine supplementation.

    PubMed

    Yano, Shoji; Moseley, Kathryn; Azen, Colleen

    2014-07-01

    To determine whether additional supplementation of tryptophan (Trp) and tyrosine (Tyr) improve serotonin and dopamine metabolism in individuals with phenylketonuria treated with large neutral amino acid (LNAA) tablets. Ten adult individuals with phenylketonuria participated in a randomized, double-blind, placebo-controlled cross-over study consisting of three 3-week phases: washout, treatment with LNAA tablets plus supplementation with either Trp and Tyr tablets or placebo, and LNAA tablets plus the alternate supplementation. An overnight protocol to measure blood melatonin, a serotonin metabolite in the pinealocytes, and urine 6-sulfatoxymelatonin and dopamine in first-void urine specimens was conducted after each phase. Serum melatonin and urine 6-sulfatoxymelatonin and dopamine levels were increased in the LNAA phase (LNAA plus placebo) compared with the washout phase. Serum melatonin and urine 6-sulfatoxymelatonin were not increased in the active phase (LNAA plus Trp + Tyr) compared with the LNAA phase, although plasma Trp:LNAA was increased compared with the LNAA phase. Among 7 subjects with a plasma Trp/LNAA >0.03, a negative correlation between urine 6-sulfatoxymelatonin and plasma phenylalanine levels was observed (r = -0.072). Urine dopamine levels and plasma Tyr:LNAA were increased in the active phase compared with the LNAA phase. Melatonin levels were not increased with the higher dose of Trp supplementation, but dopamine levels were increased with the higher dose of Tyr supplementation. Serotonin synthesis appears to be suppressed by high phenylalanine levels at the Trp hydroxylase level. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Carbon dots prepared by hydrothermal treatment of dopamine as an effective fluorescent sensing platform for the label-free detection of iron(III) ions and dopamine.

    PubMed

    Qu, Konggang; Wang, Jiasi; Ren, Jinsong; Qu, Xiaogang

    2013-05-27

    A facile, economic and green one-step hydrothermal synthesis route using dopamine as source towards photoluminescent carbon nanoparticles (CNPs) is proposed. The as-prepared CNPs have an average size about 3.8 nm. The emission spectra of the CNPs are broad, ranging from approximately 380 (purple) to approximately 525 nm (green), depending on the excitation wavelengths. Due to the favorable optical properties, the CNPs can readily enter into A549 cells and has been used for multicolor biolabeling and bioimaging. Most importantly, the as-prepared CNPs contain distinctive catechol groups on their surfaces. Due to the special response of catechol groups to Fe(3+) ions, we further demonstrate that such wholly new CNPs can serve as a very effective fluorescent sensing platform for label-free sensitive and selective detection of Fe(3+) ions and dopamine with a detection limit as low as 0.32 μM and 68 nM, respectively. The new "mix-and-detect" strategy is simple, green, and exhibits high sensitivity and selectivity. The present method was also applied to the determination of Fe(3+) ions in real water samples and dopamine in human urine and serum samples successfully. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Dopamine Uptake in the Somatic Cell Hybrid NX31

    DTIC Science & Technology

    1975-08-01

    AFRRI SR75-21 AUGUST 1975 AFRRI SCIENTIFIC REPORT CM CO DOPAMINE UPTAKE IN THE SOMATIC CELL HYBRID NX31 P. R. Myers W. G. Shaln, Jr...Sciences - National Research Council. AFRRI SR75-21 August 1975 DOPAMINE UPTAKE IN THE SOMATIC CELL HYBRID NX31 P. R. MYERS W. G. SHAIN...Introduction 1 II. Experimental Methods 2 Materials 2 Cell lines 2 Dopamine uptake experiments 3 Metabolism of accumulated dopamine 5

  9. The Effects of Dopamine and Estrogen upon Cortical Parvalbumin Expression

    DTIC Science & Technology

    2001-10-01

    parvalbumin expression in the deep cortical layers in the in vivo model. Dopamine D1 and D2 receptors are located on parvalbumin containing interneurons ...D2 dopamine receptors in the inhibition of the evoked release of [3H]GABA in the rat prefrontal cortex. Neuroscience 43:323-329. Sandhu S, Cook P and...Furthermore, estrogen treatment blocks dopamine D2 receptors (Paden et al, 1982) and altered dopamine mediated behaviors, such as locomotor activity

  10. Neuronal Source of Plasma Dopamine

    PubMed Central

    Goldstein, David S.; Holmes, Courtney

    2008-01-01

    BACKGROUND Determinants of plasma norepinephrine (NE) and epinephrine concentrations are well known; those of the third endogenous catecholamine, dopamine (DA), remain poorly understood. We tested in humans whether DA enters the plasma after corelease with NE during exocytosis from sympathetic noradrenergic nerves. METHODS We reviewed plasma catecholamine data from patients referred for autonomic testing and control subjects under the following experimental conditions: during supine rest and in response to orthostasis; intravenous yohimbine (YOH), isoproterenol (ISO), or glucagon (GLU), which augment exocytotic release of NE from sympathetic nerves; intravenous tri-methaphan (TRI) or pentolinium (PEN), which decrease exocytotic NE release; or intravenous tyramine (TYR), which releases NE by nonexocytotic means. We included groups of patients with pure autonomic failure (PAF), bilateral thoracic sympathectomies (SNS-x), or multiple system atrophy (MSA), since PAF and SNS-x are associated with noradrenergic denervation and MSA is not. RESULTS Orthostasis, YOH, ISO, and TYR increased and TRI/PEN decreased plasma DA concentrations. Individual values for changes in plasma DA concentrations correlated positively with changes in NE in response to orthostasis (r =0.72, P <0.0001), YOH (r = 0.75, P < 0.0001), ISO (r = 0.71, P < 0.0001), GLU (r = 0.47, P = 0.01), and TYR (r = 0.67, P < 0.0001). PAF and SNS-x patients had low plasma DA concentrations. We estimated that DA constitutes 2%– 4% of the catecholamine released by exocytosis from sympathetic nerves and that 50%–90% of plasma DA has a sympathoneural source. CONCLUSIONS Plasma DA is derived substantially from sympathetic noradrenergic nerves. PMID:18801936

  11. Thermal Stability of Dopamine Transporters.

    PubMed

    Kukk, Siim; Stepanov, Vladimir; Järv, Jaak

    2015-08-01

    The thermal stabilities of the rat and mouse dopamine transporter (DAT) proteins were studied within the temperature range of 0-37°C. The inactivation of the protein was followed by monitoring changes in radioligand-specific binding. We found that the process followed a rate equation with first-order kinetics and was characterized by having a single rate constant k inact. The activation energies (E a) that were calculated from the Arrhenius plots (ln k inact vs. 1/T) were 43 ± 5 and 45 ± 6 kJ/mol for the rat (rDAT) and mouse (mDAT) transporters, respectively, and 44 ± 7 kJ/mol for rDAT from PC-6.3 cell line. These E a values were similar to the E a values of thermal inactivation of the muscarinic receptor from rat brain cortex and to the thermal inactivation of other transmembrane proteins. However, all of these activation energy values were significantly lower than the E a values for soluble single-subunit proteins of similar size. These results therefore suggest that the thermal stability of transmembrane proteins may be governed to a significant extent by cell membrane properties and by interactions between the membrane components and the protein. In contrast, the stability of soluble proteins seems to be mostly governed by protein structure and size, which determine the sum of the stabilizing intramolecular interactions within the protein molecule. It is therefore not surprising that cell membrane properties and composition may have significant effects on the functional properties of transmembrane proteins.

  12. Imaging of Brain Dopamine Pathways

    PubMed Central

    Wang, Gene-Jack; Volkow, Nora D.; Thanos, Panayotis K.; Fowler, Joanna S.

    2011-01-01

    Obesity is typically associated with abnormal eating behaviors. Brain imaging studies in humans implicate the involvement of dopamine (DA)-modulated circuits in pathologic eating behavior(s). Food cues increase striatal extracellular DA, providing evidence for the involvement of DA in the nonhedonic motivational properties of food. Food cues also increase metabolism in the orbitofrontal cortex indicating the association of this region with the motivation for food consumption. Similar to drug-addicted subjects, striatal DA D2 receptor availability is reduced in obese subjects, which may predispose obese subjects to seek food as a means to temporarily compensate for understimulated reward circuits. Decreased DA D2 receptors in the obese subjects are also associated with decreased metabolism in prefrontal regions involved in inhibitory control, which may underlie their inability to control food intake. Gastric stimulation in obese subjects activates cortical and limbic regions involved with self-control, motivation, and memory. These brain regions are also activated during drug craving in drug-addicted subjects. Obese subjects have increased metabolism in the somatosensory cortex, which suggests an enhanced sensitivity to the sensory properties of food. The reduction in DA D2 receptors in obese subjects coupled with the enhanced sensitivity to food palatability could make food their most salient reinforcer putting them at risk for compulsive eating and obesity. The results from these studies suggest that multiple but similar brain circuits are disrupted in obesity and drug addiction and suggest that strategies aimed at improving DA function might be beneficial in the treatment and prevention of obesity. PMID:21603099

  13. Corticosterone regulates both naturally occurring and cocaine-induced dopamine signaling by selectively decreasing dopamine uptake.

    PubMed

    Wheeler, Daniel S; Ebben, Amanda L; Kurtoglu, Beliz; Lovell, Marissa E; Bohn, Austin T; Jasek, Isabella A; Baker, David A; Mantsch, John R; Gasser, Paul J; Wheeler, Robert A

    2017-10-01

    Stressful and aversive events promote maladaptive reward-seeking behaviors such as drug addiction by acting, in part, on the mesolimbic dopamine system. Using animal models, data from our lab and others show that stress and cocaine can interact to produce a synergistic effect on reward circuitry. This effect is also observed when the stress hormone corticosterone is administered directly into the nucleus accumbens (NAc), indicating that glucocorticoids act locally in dopamine terminal regions to enhance cocaine's effects on dopamine signaling. However, prior studies in behaving animals have not provided mechanistic insight. Using fast-scan cyclic voltammetry, we examined the effect of systemic corticosterone on spontaneous dopamine release events (transients) in the NAc core and shell in behaving rats. A physiologically relevant systemic injection of corticosterone (2 mg/kg i.p.) induced an increase in dopamine transient amplitude and duration (both voltammetric measures sensitive to decreases in dopamine clearance), but had no effect on the frequency of transient release events. This effect was compounded by cocaine (2.5 mg/kg i.p.). However, a second experiment indicated that the same injection of corticosterone had no detectable effect on the dopaminergic encoding of a palatable natural reward (saccharin). Taken together, these results suggest that corticosterone interferes with naturally-occurring dopamine uptake locally, and this effect is a critical determinant of dopamine concentration specifically in situations in which the dopamine transporter is pharmacologically blocked by cocaine. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  14. Dopamine, vesicular transporters, and dopamine receptor expression in rat major salivary glands.

    PubMed

    Tomassoni, Daniele; Traini, Enea; Mancini, Manuele; Bramanti, Vincenzo; Mahdi, Syed Sarosh; Amenta, Francesco

    2015-09-01

    The localization of dopamine stores and the expression and localization of dopamine (DAT) and vesicular monoamine transporters (VMAT) type-1 and -2 and of dopamine D1-like and D2-like receptor subtypes were investigated in rat submandibular, sublingual, and parotid salivary glands by HPLC with electrochemical detection, as well as immunochemical and immunohistochemical techniques. Male Wistar rats of 2 mo of age were used. The highest dopamine levels were measured in the parotid gland, followed by the submandibular and sublingual glands. Western blot analysis revealed DAT, VMAT-1, VMAT-2, and dopamine receptors immunoreactivity in membrane preparations obtained from the three glands investigated. Immunostaining for dopamine and transporters was developed within striated ducts. Salivary glands processed for dopamine receptors immunohistochemistry developed an immunoreaction primarily in striated and excretory ducts. In the submandibular gland, acinar cells displayed strong immunoreactivity for the D2 receptor, while cells of the convoluted granular tubules were negative for both D1-like and D2-like receptors. Parotid glands acinar cells displayed the highest immunoreactivity for both D1 and D2 receptors compared with other salivary glands. The above localization of dopamine and dopaminergic markers investigated did not correspond closely with neuron-specific enolase (NSE) localization. This indicates that at least in part, catecholamine stores and dopaminergic markers are independent from glandular innervation. These findings suggest that rat major salivary glands express a dopaminergic system probably involved in salivary secretion. The stronger immunoreactivity for dopamine transporters and receptors in striated duct cells suggests that the dopaminergic system could regulate not only quality, but also volume and ionic concentration of saliva. Copyright © 2015 the American Physiological Society.

  15. Detection of cell surface dopamine receptors.

    PubMed

    Xiao, Jiping; Bergson, Clare

    2013-01-01

    Dopamine receptors are a class of metabotropic G protein-coupled receptors. Plasma membrane expression is a key determinant of receptor signaling, and one that is regulated both by extra and intracellular cues. Abnormal dopamine receptor signaling is implicated in several neuropsychiatric disorders, including schizophrenia and attention deficit hyperactivity disorder, as well as drug abuse. Here, we describe in detail the application of two complementary applications of protein biotinylation and enzyme-linked immunoabsorbent assay (ELISA) for detecting and quantifying levels of dopamine receptors expressed on the cell surface. In the biotinylation method, cell surface receptors are labeled with Sulfo-NHS-biotin. The charge on the sulfonyl facilitates water solubility of the reactive biotin compound and prevents its diffusion across the plasma membrane. In the ELISA method, surface labeling is achieved with antibodies specific to extracellular epitopes on the receptors, and by fixing the cells without detergent such that the plasma membrane remains intact.

  16. Detection of Cell Surface Dopamine Receptors

    PubMed Central

    Xiao, Jiping; Bergson, Clare

    2014-01-01

    Dopamine receptors are a class of metabotropic G protein-coupled receptors. Plasma membrane expression is a key determinant of receptor signaling, and one that is regulated both by extra and intracellular cues. Abnormal dopamine receptor signaling is implicated in several neuropsychiatric disorders, including schizophrenia and attention deficit hyperactivity disorder, as well as drug abuse. Here, we describe in detail the application of two complementary applications of protein biotinylation and enzyme-linked immunoabsorbant assay (ELISA) for detecting and quantifying levels of dopamine receptors expressed on the cell surface. In the biotinylation method, cell surface receptors are labeled with Sulfo-NHS-biotin. The charge on the sulfonyl facilitates water solubility of the reactive biotin compound and prevents its diffusion across the plasma membrane. In the ELISA method, cells surface labeling is achieved with antibodies specific to extracellular epitopes on the receptors, and by fixing the cells without detergent such that the plasma membrane remains intact. PMID:23296774

  17. Theoretical determinations of ionization potentials of dopamine

    NASA Astrophysics Data System (ADS)

    Lu, J. F.; Yu, Z. Y.

    2013-04-01

    Adiabatic and vertical ionization potentials (IPs) of nine conformers of dopamine in the gas phase are determined using density functional theory (DFT) B3LYP, B3P86, B3PW91 methods and high level ab initio HF method with 6-311++G** basis set, respectively. And the nine stable cationic states have been found in the ionization process of dopamine. Vertical ionization potentials of nine conformers of dopamine are calculated using the older outer-valence Green's function (OVGF) calculations at 6-311++G** basis set. Vibrational frequencies and infrared spectrum intensities of G1b and G1b+ at B3LYP/6-311++G** level are discussed.

  18. Dopamine, T cells and multiple sclerosis (MS).

    PubMed

    Levite, Mia; Marino, Franca; Cosentino, Marco

    2017-03-10

    Dopamine is a key neurotransmitter that induces critical effects in the nervous system and in many peripheral organs, via 5 dopamine receptors (DRs): D1R-D5R. Dopamine also induces many direct and very potent effects on many DR-expressing immune cells, primarily T cells and dendritic cells. In this review, we focus only on dopamine receptors, effects and production in T cells. Dopamine by itself (at an optimal concentration of~0.1 nM) induces multiple function of resting normal human T cells, among them: T cell adhesion, chemotactic migration, homing, cytokine secretion and others. Interestingly, dopamine activates resting effector T cells (Teffs), but suppresses regulatory T cells (Tregs), and both effects lead eventually to Teff activation. Dopamine-induced effects on T cells are dynamic, context-sensitive and determined by the: T cell activation state, T cell type, DR type, and dopamine concentration. Dopamine itself, and also few dopaminergic molecules/ drugs that are in clinical use for cardiac, neurological and other non-immune indications, have direct effects on human T cells (summarized in this review). These dopaminergic drugs include: dopamine = intropin, L-DOPA, bromocriptine, pramipexole, pergolide, haloperidol, pimozide, and amantadine. Other dopaminergic drugs were not yet tested for their direct effects on T cells. Extensive evidence in multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) show dopaminergic dysregulations in T cells in these diseases: D1-like DRs are decreased in Teffs of MS patients, and dopamine does not affect these cells. In contrast, D1-like DRs are increased in Tregs of MS patients, possibly causing functional Treg impairment in MS. Treatment of MS patients with interferon β (IFN-β) increases D1-like DRs and decreases D2-like DRs in Teffs, decreases D1-like DRs in Tregs, and most important: restores responsiveness of patient's Teffs to dopamine. DR agonists and antagonists confer some benefits in

  19. How Addictive Drugs Disrupt Presynaptic Dopamine Neurotransmission

    PubMed Central

    Sulzer, David

    2011-01-01

    The fundamental principle that unites addictive drugs appears to be that each enhances synaptic dopamine by means that dissociate it from normal behavioral control, so that they act to reinforce their own acquisition. This occurs via the modulation of synaptic mechanisms involved in learning, including enhanced excitation or disinhibition of dopamine neuron activity, blockade of dopamine reuptake, and altering the state of the presynaptic terminal to enhance evoked over basal transmission. Amphetamines offer an exception to such modulation in that they combine multiple effects to produce non-exocytic stimulation-independent release of neurotransmitter via reverse transport independent from normal presynaptic function. Questions on the molecular actions of addictive drugs, prominently including the actions of alcohol and solvents, remain unresolved, but their ability to co-opt normal presynaptic functions helps to explain why treatment for addiction has been challenging. PMID:21338876

  20. Glucocorticoids and dopamine-1 receptors on vascular smooth muscle cells.

    PubMed

    Yasunari, K; Kohno, M; Balmforth, A; Murakawa, K; Yokokawa, K; Kurihara, N; Takeda, T

    1989-06-01

    The effect of glucocorticoids on the dopamine (DA)-mediated cyclic adenosine monophosphate (cAMP) by intact vascular smooth muscle cells (VSMC) was studied in rats. Cultured VSMC were obtained from renal arteries of 14-week-old Wistar-Kyoto rats by explant method. Micromolar concentrations of dexamethasone (DEX) pretreatment for 48 hours potentiated DA-mediated response without any change of affinity constant. However, micromolar concentrations of aldosterone pretreatment for 48 hours had almost no effect on DA-mediated response. The DEX-induced facilitation began at 6 hours and reached maximum at 24 hours after DEX administration in a dose-dependent manner. Inhibitors of protein and RNA synthesis blocked this glucocorticoid effect. The basal activity of adenylate cyclase in DEX-treated cells was twofold higher than that in control cells. Treatment of VSMC with DEX increased cholera toxin-stimulated and forskolin-stimulated adenylate cyclase activity. However, pertussis toxin treatment did not augment or reduce the effect of DEX treatment. These results suggest that glucocorticoids increase DA-mediated cAMP formation by VSMC through glucocorticoid type II receptors and the induction of protein synthesis and that the activation of the catalytic unit may play some role in this facilitation.

  1. Vascular dopamine receptors: Demonstration and characterization by in vitro studies.

    PubMed

    Brodde, O E

    1982-07-26

    Substantial evidence has accumulated that in certain vascular beds dopamine produces its relaxant effect through stimulation of specific dopamine receptors. The goal of this review is to describe several in vitro models (perfused mesenteric vessels of the dog; renal, mesenteric, splenic, coronary and cerebral arterial strips of rabbits, dogs and cats; perfused kidney of the rat) recently developed to demonstrate such specific relaxations induced by dopamine and dopaminomimetics. On these models studies on structure-activity relationship for activation of the dopamine receptor resulted in the following order of potency for agonists: SK&F 38393 (partial agonist) greater than epinine greater than A-6, 7-DTN greater than or equal to dopamine greater than N, N-di-n-propyl-dopamine (partial agonist) greater than apomorphine (partial agonist). The dopamine receptor antagonists (+)-butaclamol, cis-alpha-flupenthixol, metoclopramide, droperidol and bulbocapnine were found to competitively antagonize dopamine induced relaxation. In addition, in two isolated organ systems (rabbit mesenteric artery, rat perfused kidney) stereospecificity of the vascular dopamine receptor was demonstrated with the isomers of butaclamol. With the development of several in vitro models demonstrating a specific antagonism against dopamine induced relaxation an important requirement for definition of a specific dopamine receptor if fulfilled according to classical pharmacological criteria. Thus, there can be do doubt on the existence of post-synaptic dopamine receptors mediating vasodilation in certain vascular tissues.

  2. Modeling the kinetic diversity of dopamine in the dorsal striatum.

    PubMed

    Walters, Seth H; Robbins, Elaine M; Michael, Adrian C

    2015-08-19

    Dopamine is an important neurotransmitter that exhibits numerous functions in the healthy, injured, and diseased brain. Fast scan cyclic voltammetry paired with electrical stimulation of dopamine axons is a popular and powerful method for investigating the dynamics of dopamine in the extracellular space. Evidence now suggests that the heterogeneity of electrically evoked dopamine responses reflects the inherent kinetic diversity of dopamine systems, which might contribute to their diversity of physiological function. Dopamine measurements by fast scan cyclic voltammetry are affected by the adsorption of dopamine to carbon fiber electrodes. The temporal distortion caused by dopamine adsorption is correctable by a straightforward mathematical procedure. The corrected responses exhibit excellent agreement with a dopamine kinetic model cast to provide a generic description of restricted diffusion, short-term plasticity of dopamine release, and first-order dopamine clearance. The new DA kinetic model brings to light the rich kinetic information content of electrically evoked dopamine responses recorded via fast scan cyclic voltammetry in the rat dorsal striatum.

  3. Dopamine receptors in a songbird brain

    PubMed Central

    Kubikova, Lubica; Wada, Kazuhiro; Jarvis, Erich D

    2010-01-01

    Dopamine is a key neuromodulatory transmitter in the brain. It acts through dopamine receptors to affect changes in neural activity, gene expression, and behavior. In songbirds, dopamine is released into the striatal song nucleus Area X, and the levels depend on social contexts of undirected and directed singing. This differential release is associated with differential expression of activity-dependent genes, such as egr1 (avian zenk), which in mammalian brain are modulated by dopamine receptors. Here we cloned from zebra finch brain cDNAs of all avian dopamine receptors: the D1 (D1A, D1B, D1D) and D2 (D2, D3, D4) families. Comparative sequence analyses of predicted proteins revealed expected phylogenetic relationships, in which the D1 family exists as single exon and the D2 family exists as spliced exon genes. In both zebra finch and chicken, the D1A, D1B, and D2 receptors were highly expressed in the striatum, the D1D and D3 throughout the pallium and within the mesopallium, respectively, and the D4 mainly in the cerebellum. Furthermore, within the zebra finch, all receptors, except for D4, showed differential expression in song nuclei relative to the surrounding regions and developmentally regulated expression that decreased for most receptors during the sensory acquisition and sensorimotor phases of song learning. Within Area X, half of the cells expressed both D1A and D2 receptors, and a higher proportion of the D1A-only-containing neurons expressed egr1 during undirected but not during directed singing. Our findings are consistent with hypotheses that dopamine receptors may be involved in song development and social context-dependent behaviors. J. Comp. Neurol. 518:741–769, 2010. © 2009 Wiley-Liss, Inc. PMID:20058221

  4. Donor Preconditioning After the Onset of Brain Death With Dopamine Derivate n-Octanoyl Dopamine Improves Early Posttransplant Graft Function in the Rat.

    PubMed

    Li, S; Korkmaz-Icöz, S; Radovits, T; Ruppert, M; Spindler, R; Loganathan, S; Hegedűs, P; Brlecic, P; Theisinger, B; Theisinger, S; Höger, S; Brune, M; Lasitschka, F; Karck, M; Yard, B; Szabó, G

    2017-07-01

    Heart transplantation is the therapy of choice for end-stage heart failure. However, hemodynamic instability, which has been demonstrated in brain-dead donors (BDD), could also affect the posttransplant graft function. We tested the hypothesis that treatment of the BDD with the dopamine derivate n-octanoyl-dopamine (NOD) improves donor cardiac and graft function after transplantation. Donor rats were given a continuous intravenous infusion of either NOD (0.882 mg/kg/h, BDD+NOD, n = 6) or a physiological saline vehicle (BDD, n = 9) for 5 h after the induction of brain death by inflation of a subdural balloon catheter. Controls were sham-operated (n = 9). In BDD, decreased left-ventricular contractility (ejection fraction; maximum rate of rise of left-ventricular pressure; preload recruitable stroke work), relaxation (maximum rate of fall of left-ventricular pressure; Tau), and increased end-diastolic stiffness were significantly improved after the NOD treatment. Following the transplantation, the NOD-treatment of BDD improved impaired systolic function and ventricular relaxation. Additionally, after transplantation increased interleukin-6, tumor necrosis factor TNF-α, NF-kappaB-p65, and nuclear factor (NF)-kappaB-p105 gene expression, and increased caspase-3, TNF-α and NF-kappaB protein expression could be significantly downregulated by the NOD treatment compared to BDD. BDD postconditioning with NOD through downregulation of the pro-apoptotic factor caspase-3, pro-inflammatory cytokines, and NF-kappaB may protect the heart against the myocardial injuries associated with brain death and ischemia/reperfusion. © 2017 The American Society of Transplantation and the American Society of Transplant Surgeons.

  5. PET evaluation of the dopamine system of the human brain

    SciTech Connect

    Volkow, N.D.; Fowler, J.S.; Gatley, S. |

    1996-07-01

    Dopamine plays a pivotal role in the regulation and control of movement, motivation and cognition. It also is closely linked to reward, reinforcement and addiction. Abnormalities in brain dopamine are associated with many neurological and psychiatric disorders including Parkinson`s disease, schizophrenia and substance abuse. This close association between dopamine and neurological and psychiatric diseases and with substance abuse make it an important topic in research in the neurosciences and an important molecular target in drug development. PET enables the direct measurement of components of the dopamine system in the living human brain. It relies on radiotracers which label dopamine receptors, dopamine transporters, precursors of dopamine or compounds which have specificity for the enzymes which degrade dopamine. Additionally, by using tracers that provide information on regional brain metabolism or blood flow as well as neurochemically specific pharmacological interventions, PET can be used to assess the functional consequences of change in brain dopamine activity. PET dopamine measurements have been used to investigate the normal human brain and its involvement in psychiatric and neurological diseases. It has also been used in psychopharmacological research to investigate dopamine drugs used in the treatment of Parkinson`s disease and of schizophrenia as well as to investigate the effects of drugs of abuse on the dopamine system. Since various functional and neurochemical parameters can be studied in the same subject, PET enables investigation of the functional integrity of the dopamine system in the human brain and investigation of the interactions of dopamine with other neurotransmitters. This paper summarizes the different tracers and experimental strategies developed to evaluate the various elements of the dopamine system in the human brain with PET and their applications to clinical research. 254 refs., 7 figs., 3 tabs.

  6. Amphetamine Self-Administration Attenuates Dopamine D2 Autoreceptor Function

    PubMed Central

    Calipari, Erin S; Sun, Haiguo; Eldeeb, Khalil; Luessen, Deborah J; Feng, Xin; Howlett, Allyn C; Jones, Sara R; Chen, Rong

    2014-01-01

    Dopamine D2 autoreceptors located on the midbrain dopaminergic neurons modulate dopamine (DA) neuron firing, DA release, and DA synthesis through a negative-feedback mechanism. Dysfunctional D2 autoreceptors following repeated drug exposure could lead to aberrant DA activity in the ventral tegmental area (VTA) and projection areas such as nucleus accumbens (NAcc), promoting drug-seeking and -taking behavior. Therefore, it is important to understand molecular mechanisms underlying drug-induced changes in D2 autoreceptors. Here, we reported that 5 days of amphetamine (AMPH) self-administration reduced the ability of D2 autoreceptors to inhibit DA release in the NAcc as determined by voltammetry. Using the antibody-capture [35S]GTPγS scintillation proximity assay, we demonstrated for the first time that midbrain D2/D3 receptors were preferentially coupled to Gαi2, whereas striatal D2/D3 receptors were coupled equally to Gαi2 and Gαo for signaling. Importantly, AMPH abolished the interaction between Gαi2 and D2/D3 receptors in the midbrain while leaving striatal D2/D3 receptors unchanged. The disruption of the coupling between D2/D3 receptors and Gαi2 by AMPH is at least partially explained by the enhanced RGS2 (regulator of G-protein signaling 2) activity resulting from an increased RGS2 trafficking to the membrane. AMPH had no effects on the midbrain expression and trafficking of other RGS proteins such as RGS4 and RGS8. Our data suggest that midbrain D2/D3 receptors are more susceptible to AMPH-induced alterations. Reduced D2 autoreceptor function could lead to enhanced DA signaling and ultimately addiction-related behavior. RGS2 may be a potential non-dopaminergic target for pharmacological intervention of dysfunctional DA transmission and drug addiction. PMID:24513972

  7. Amphetamine self-administration attenuates dopamine D2 autoreceptor function.

    PubMed

    Calipari, Erin S; Sun, Haiguo; Eldeeb, Khalil; Luessen, Deborah J; Feng, Xin; Howlett, Allyn C; Jones, Sara R; Chen, Rong

    2014-07-01

    Dopamine D2 autoreceptors located on the midbrain dopaminergic neurons modulate dopamine (DA) neuron firing, DA release, and DA synthesis through a negative-feedback mechanism. Dysfunctional D2 autoreceptors following repeated drug exposure could lead to aberrant DA activity in the ventral tegmental area (VTA) and projection areas such as nucleus accumbens (NAcc), promoting drug-seeking and -taking behavior. Therefore, it is important to understand molecular mechanisms underlying drug-induced changes in D2 autoreceptors. Here, we reported that 5 days of amphetamine (AMPH) self-administration reduced the ability of D2 autoreceptors to inhibit DA release in the NAcc as determined by voltammetry. Using the antibody-capture [(35)S]GTPγS scintillation proximity assay, we demonstrated for the first time that midbrain D2/D3 receptors were preferentially coupled to Gαi2, whereas striatal D2/D3 receptors were coupled equally to Gαi2 and Gαo for signaling. Importantly, AMPH abolished the interaction between Gαi2 and D2/D3 receptors in the midbrain while leaving striatal D2/D3 receptors unchanged. The disruption of the coupling between D2/D3 receptors and Gαi2 by AMPH is at least partially explained by the enhanced RGS2 (regulator of G-protein signaling 2) activity resulting from an increased RGS2 trafficking to the membrane. AMPH had no effects on the midbrain expression and trafficking of other RGS proteins such as RGS4 and RGS8. Our data suggest that midbrain D2/D3 receptors are more susceptible to AMPH-induced alterations. Reduced D2 autoreceptor function could lead to enhanced DA signaling and ultimately addiction-related behavior. RGS2 may be a potential non-dopaminergic target for pharmacological intervention of dysfunctional DA transmission and drug addiction.

  8. Downregulating the sucrose transporter VpSUT1 in Verbascum phoeniceum does not inhibit phloem loading

    PubMed Central

    Zhang, Cankui; Turgeon, Robert

    2009-01-01

    Sucrose is loaded into the phloem in the minor veins of leaves before export. Two active, species-specific loading mechanisms have been proposed. One involves transporter-mediated sucrose transfer from the apoplast into the sieve element-companion cell complex, so-called apoplastic loading. In the putative second mechanism, sucrose follows an entirely symplastic pathway, and the solute concentration is elevated by the synthesis of raffinose and stachyose in the phloem, not by transporter activity. Several sucrose-transporting plants have been shown to be apoplastic loaders by downregulating sucrose transporter 1 (SUT1), leading to accumulation of sugars and leaf chlorosis. In this study we compared the effect of downregulating SUT1 in Nicotiana tabacum, a sucrose transporter, and Verbascum phoeniceum, a species that transports raffinose and stachyose. To test the effectiveness of RNAi downregulation, we measured SUT1 mRNA levels and sucrose-H+ symport in leaf discs. Mild NtSUT1 downregulation in N. tabacum resulted in the pronounced phenotype associated with loading inhibition. In contrast, no such phenotype developed when VpSUT1 was downregulated in V. phoeniceum, leaving minimal sucrose transport activity. Only those plants with the most severe VpSUT1 downregulation accumulated more carbohydrate than usual and these plants were normal by other criteria: growth rate, photosynthesis, and ability to clear starch during the night. The results provide direct evidence that the mechanism of phloem loading in V. phoeniceum does not require active sucrose uptake from the apoplast and strongly supports the conclusion that the loading pathway is symplastic in this species. PMID:19846784

  9. Dopamine enhances the response of sunitinib in the treatment of drug-resistant breast cancer: Involvement of eradicating cancer stem-like cells.

    PubMed

    Wang, Siyuan; Mou, Zhenzhen; Ma, Yuanheng; Li, Jian; Li, Jingyun; Ji, Xiwei; Wu, Kehua; Li, Liang; Lu, Wei; Zhou, Tianyan

    2015-05-15

    Growing evidence suggests that the efficacy of sunitinib in breast cancer may be limited by increasing the population of cancer stem-like cells (CSCs). Hence the concurrent use of CSCs-targeting agents is required. Previous results indicated that dopamine receptor (DR) may serve as a potential therapeutic target of anti-CSCs therapies. This study focused on evaluating the effect of dopamine (an agonist of DR) on the enhancement of sunitinib's efficacy in the treatment of drug-resistant breast cancer, investigating the involved activation type of DR pathway and exploring the underlying anti-CSCs mechanisms. MCF-7 cells, MCF-7/Adr cells and breast cancer stem-like cells (BCSCs) were used for in vitro study. Moreover, MCF-7/Adr cells and BCSCs were selected as drug-resistant cell lines and further used for in vivo development of the xenograft animal models. Our results showed that dopamine greatly synergized the inhibitory effect of sunitinib in the drug-resistant cells and strikingly enhanced the response of sunitinib in both xenograft models. It was found that dopamine significantly down-regulated the expression of BCSCs markers (CD44(+)/CD24(-)) in vitro and in vivo. In addition, dopamine remarkably induced the apoptosis of BCSCs, markedly inhibited the Wnt signaling pathway and activated the apoptotic associated signals. The activation of dopamine receptor D1 (D1DR) pathway may be involved in the underlying mechanism as D1DR's antagonist SCH23390 completely reversed the combined effects. In conclusion, dopamine may eradicate CSCs and it significantly enhances the response of sunitinib in the treatment of drug-resistant breast cancer.

  10. Presynaptic Dopamine Capacity in Patients with Treatment-Resistant Schizophrenia Taking Clozapine: An [(18)F]DOPA PET Study.

    PubMed

    Kim, Euitae; Howes, Oliver D; Veronese, Mattia; Beck, Katherine; Seo, Seongho; Park, Jin Woo; Lee, Jae Sung; Lee, Yun-Sang; Kwon, Jun Soo

    2017-03-01

    Some patients with schizophrenia show poor response to first-line antipsychotic treatments and this is termed treatment-resistant schizophrenia. The differential response to first-line antipsychotic drugs may reflect a different underlying neurobiology. Indeed, a previous study found dopamine synthesis capacity was significantly lower in patients with treatment-resistant schizophrenia. However, in this study, the treatment-resistant patients were highly symptomatic, whereas the responsive patients showed no or minimal symptoms. The study could not distinguish whether this was a trait effect or reflected the difference in symptom levels. Thus, we aimed to test whether dopaminergic function is altered in patients with a history of treatment resistance to first-line drugs relative to treatment responders when both groups are matched for symptom severity levels by recruiting treatment-resistant patients currently showed low symptom severity with the clozapine treatment. Healthy controls (n=12), patients treated with clozapine (n=12) who had not responded to first-line antipsychotics, and patients who had responded to first-line antipsychotics (n=12) were recruited. Participants were matched for age and sex and symptomatic severity level in patient groups. Participants' dopamine synthesis capacity was measured by using [(18)F]DOPA PET. We found that patients treated with clozapine show lower dopamine synthesis capacity than patients who have responded to first-line treatment (Cohen's d=0.9191 (whole striatum), 0.7781 (associative striatum), 1.0344 (limbic striatum), and 1.0189 (sensorimotor striatum) in line with the hypothesis that the dopaminergic function is linked to treatment response. This suggests that a different neurobiology may underlie treatment-resistant schizophrenia and that dopamine synthesis capacity may be a useful biomarker to predict treatment responsiveness.

  11. Midbrain dopamine function in schizophrenia and depression: a post-mortem and positron emission tomographic imaging study.

    PubMed

    Howes, Oliver D; Williams, Matthew; Ibrahim, Kemal; Leung, Garret; Egerton, Alice; McGuire, Philip K; Turkheimer, Federico

    2013-11-01

    Elevated in vivo markers of presynaptic striatal dopamine activity have been a consistent finding in schizophrenia, and include a large effect size elevation in dopamine synthesis capacity. However, it is not known if the dopaminergic dysfunction is limited to the striatal terminals of dopamine neurons, or is also evident in the dopamine neuron cell bodies, which mostly originate in the substantia nigra. The aim of our studies was therefore to determine whether dopamine synthesis capacity is altered in the substantia nigra of people with schizophrenia, and how this relates to symptoms. In a post-mortem study, a semi-quantitative analysis of tyrosine hydroxylase staining was conducted in nigral dopaminergic cells from post-mortem tissue from patients with schizophrenia (n = 12), major depressive disorder (n = 13) and matched control subjects (n = 13). In an in vivo imaging study, nigral and striatal dopaminergic function was measured in patients with schizophrenia (n = 29) and matched healthy control subjects (n = 29) using (18)F-dihydroxyphenyl-L-alanine ((18)F-DOPA) positron emission tomography. In the post-mortem study we found that tyrosine hydroxylase staining was significantly increased in nigral dopaminergic neurons in schizophrenia compared with both control subjects (P < 0.001) and major depressive disorder (P < 0.001). There was no significant difference in tyrosine hydroxylase staining between control subjects and patients with major depressive disorder, indicating that the elevation in schizophrenia is not a non-specific indicator of psychiatric illness. In the in vivo imaging study we found that (18)F-dihydroxyphenyl-L-alanine uptake was elevated in both the substantia nigra and in the striatum of patients with schizophrenia (effect sizes = 0.85, P = 0.003 and 1.14, P < 0.0001, respectively) and, in the voxel-based analysis, was elevated in the right nigra (P < 0.05 corrected for family wise-error). Furthermore, nigral (18)F

  12. Unraveling neuronal dopamine transporter mechanisms with rotating disk electrode voltammetry.

    PubMed

    Schenk, James O; Wright, Cortney; Bjorklund, Nicole

    2005-04-15

    Herein we describe how the rotating disk electrode voltammetric technique can be used to examine the mechanism(s) of the inward transport of dopamine by the neuronal transporter for dopamine (DAT). The usefulness of making measurements kinetically resolving dopamine transport, interpretations of changes in Km and Vmax, approaches to defining pre-steady-state binding of dopamine to DAT, interactions between competing inhibitors, chemical modification of functional groups within DAT, and a presentation of a hypothetical multi-state model of dopamine transport are presented and discussed.

  13. Quadruplex Integrated DNA (QuID) Nanosensors for Monitoring Dopamine

    PubMed Central

    Morales, Jennifer M.; Skipwith, Christopher G.; Clark, Heather A.

    2015-01-01

    Dopamine is widely innervated throughout the brain and critical for many cognitive and motor functions. Imbalances or loss in dopamine transmission underlie various psychiatric disorders and degenerative diseases. Research involving cellular studies and disease states would benefit from a tool for measuring dopamine transmission. Here we show a Quadruplex Integrated DNA (QuID) nanosensor platform for selective and dynamic detection of dopamine. This nanosensor exploits DNA technology and enzyme recognition systems to optically image dopamine levels. The DNA quadruplex architecture is designed to be compatible in physically constrained environments (110 nm) with high flexibility, homogeneity, and a lower detection limit of 110 µM. PMID:26287196

  14. Cholinergic Interneurons Underlie Spontaneous Dopamine Release in Nucleus Accumbens.

    PubMed

    Yorgason, Jordan T; Zeppenfeld, Douglas M; Williams, John T

    2017-02-22

    The release of dopamine from terminals in the NAc is regulated by a number of factors, including voltage-gated ion channels, D2-autoreceptors, and nAChRs. Cholinergic interneurons (CINs) drive dopamine release through activation of nAChRs on dopamine terminals. Using cyclic voltammetry in mouse brain slices, nAChR-dependent spontaneous dopamine transients and the mechanisms underlying the origin were examined in the NAc. Spontaneous events were infrequent (0.3 per minute), but the rate and amplitude were increased after blocking Kv channels with 4-aminopyridine. Although the firing frequency of CINs was increased by blocking glutamate reuptake with TBOA and the Sk blocker apamin, only 4-aminopyridine increased the frequency of dopamine transients. In contrast, inhibition of CIN firing with the μ/δ selective opioid [Met(5)]enkephalin (1 μm) decreased spontaneous dopamine transients. Cocaine increased the rate and amplitude of dopamine transients, suggesting that the activity of the dopamine transporter limits the detection of these events. In the presence of cocaine, the rate of spontaneous dopamine transients was further increased after blocking D2-autoreceptors. Blockade of muscarinic receptors had no effect on evoked dopamine release, suggesting that feedback inhibition of acetylcholine release was not involved. Thus, although spontaneous dopamine transients are reliant on nAChRs, the frequency was not strictly governed by the activity of CINs. The increase in frequency of spontaneous dopamine transients induced by cocaine was not due to an increase in cholinergic tone and is likely a product of an increase in detection resulting from decreased dopamine reuptake.SIGNIFICANCE STATEMENT The actions of dopamine in the NAc are thought to be responsible for endogenous reward and the reinforcing properties of drugs of abuse, such as psychostimulants. The present work examines the mechanisms underlying nAChR-induced spontaneous dopamine release. This study

  15. Dopamine Transporters, D2 Receptors, and Dopamine Release in Generalized Social Anxiety Disorder

    PubMed Central

    Schneier, Franklin R.; Abi-Dargham, Anissa; Martinez, Diana; Slifstein, Mark; Hwang, Dah-Ren; Liebowitz, Michael R.; Laruelle, Marc

    2009-01-01

    Background Dopamine D2 receptor and dopamine transporter availability in the striatum have each been reported abnormal in generalized social anxiety disorder (GSAD) in studies using single photon computerized tomography (SPECT). D2 receptors and dopamine transporters have not previously been studied within the same GSAD subjects, however, and prior GSAD studies have not assessed dopamine release or subdivided striatum into functional subregions. Methods Unmedicated adults with GSAD (N=17) and matched healthy comparison subjects (HC, N=13) participated in this study. Of these, 15 GSAD and 13 HC subjects completed baseline assessment of D2 receptor availability using positron emission tomography (PET) with the radiotracer [11C] raclopride. Twelve GSAD and 13 HC subjects completed a repeat scan after intravenous administration of D-amphetamine, to study dopamine release. Twelve of the GSAD subjects and 10 of the HC subjects also completed SPECT with the radiotracer [123I] methyl 3ß-(4-iodophenyl) tropane-2ß-carboxylate ([123I] ß-CIT) to assess dopamine transporter availability. Results GSAD and HC groups did not differ significantly in striatal dopamine transporter availability, overall striatal or striatal subregion D2 receptor availability at baseline, or change in D2 receptor availability after D-amphetamine. Receptor availability and change after D-amphetamine were not significantly associated with severity of social anxiety or trait detachment. Conclusions These findings do not replicate previous findings of altered striatal dopamine transporter and D2 receptor availability in GSAD subjects assessed with SPECT. The differences from results of prior studies may be due to differences in imaging methods or characteristics of samples. PMID:19180583

  16. Experimental Investigations on Dopamine Transmission Can Provide Clues on the Mechanism of the Therapeutic Effect of Amphetamine and Methylphenidate in ADHD

    PubMed Central

    Carboni, Ezio; Silvagni, Alessandra

    2004-01-01

    The aim of this review is to compare the experimental evidence obtained from in vitro studies on the effect of amphetamine and methylphenidate on dopamine transmission with the results obtained in animal models of attention deficit hyperactivity disorder (ADHD). This comparison can extend the knowledge on the mechanism of action of the drugs used in the therapy of ADHD and provide insight into the etiology of ADHD. In particular, we considered the results obtained from in vitro methods, such as synaptosomes, cells in culture, and slices and from in vivo animal models of ADHD, such as spontaneous hypertensive rats (SHR) and the Naples high-excitability (NHE) rat lines. The different experimental approaches produce consonant results and suggest that in SHR rats, in contrast to Wistar Kyoto rats (WKY), amphetamine and depolarization by high K+ might release different pools of dopamine-containing vesicles. The pool depleted by amphetamine might represent dopamine that is stored in large dense core vesicles, whereas dopamine released by high K+ might be contained in small synaptic vesicles (SSV). The sustained dopamine transmission observed in the nucleus accumbens of SHR but not WKY rats can be supported by an elevated synthesis and release, which also might explain the stronger effect of methylphenidate on dopamine release in SHR but not in WKY rats. This hypothesis might enlighten the common therapeutic effect of these drugs, although their action takes place at different levels in catecholaminergic transmission. PMID:15303307

  17. Invariance of the density of dopamine uptake sites and dopamine metabolism in the rat brain after a chronic treatment with the dopamine uptake inhibitor GBR 12783.

    PubMed

    Boulay, D; Leroux-Nicollet, I; Duterte-Boucher, D; Naudon, L; Costentin, J

    1994-01-01

    A chronic treatment (10 mg/kg, twice daily during 9 days) with the dopamine uptake inhibitor GBR 12783 was performed in rats at a dose increasing their locomotor activity. Forty-eight hours after the last administration, animals were sacrificed and 3H mazindol binding was performed on brain slices. Autoradiographic analysis revealed no change in this binding relatively to control animals in regions with high dopamine contents: striatum, nucleus accumbens, olfactory tubercle, substantia nigra and ventral tegmentum area. The treatment did not either modify the levels of dopamine (DA) and metabolites (HVA, DOPAC) both in the striatum and the nucleus accumbens. Thus, early after the end of the treatment, the chronic blockade of the dopamine uptake complex regulates neither the dopamine uptake complex nor the dopamine metabolism.

  18. Dopamine-melanin nanofilms for biomimetic structural coloration.

    PubMed

    Wu, Tong-Fei; Hong, Jong-Dal

    2015-02-09

    This article describes the formation of dopamine-melanin thin films (50-200 nm thick) at an air/dopamine solution interface under static conditions. Beneath these films, spherical melanin granules formed in bulk liquid phase. The thickness of dopamine-melanin films at the interface relied mainly on the concentration of dopamine solution and the reaction time. A plausible mechanism underlining dopamine-melanin thin film formation was proposed based on the hydrophobicity of dopamine-melanin aggregates and the mass transport of the aggregates to the air/solution interface as a result of convective flow. The thickness of the interfacial films increased linearly with the dopamine concentration and the reaction time. The dopamine-melanin thin film and granules (formed in bulk liquid phase) with a double-layered structure were transferred onto a solid substrate to mimic the (keratin layer)/(melanin granules) structure present in bird plumage, thereby preparing full dopamine-melanin thin-film reflectors. The reflected color of the thin-film reflectors depended on the film thickness, which could be adjusted according to the dopamine concentration. The reflectance of the resulted reflectors exhibited a maximal reflectance value of 8-11%, comparable to that of bird plumage (∼11%). This study provides a useful, simple, and low-cost approach to the fabrication of biomimetic thin-film reflectors using full dopamine-melanin materials.

  19. Regulation of Dopamine Uptake by Vasoactive Peptides in the Kidney

    PubMed Central

    Gironacci, M. M.

    2016-01-01

    Considering the key role of renal dopamine in tubular sodium handling, we hypothesized that c-type natriuretic peptide (CNP) and Ang-(1-7) may regulate renal dopamine availability in tubular cells, contributing to Na+, K+-ATPase inhibition. Present results show that CNP did not affect either 3H-dopamine uptake in renal tissue or Na+, K+-ATPase activity; meanwhile, Ang-(1-7) was able to increase 3H-dopamine uptake and decreased Na+, K+-ATPase activity in renal cortex. Ang-(1-7) and dopamine together decreased further Na+, K+-ATPase activity showing an additive effect on the sodium pump. In addition, hydrocortisone reversed Ang-(1-7)-dopamine overinhibition on the enzyme, suggesting that this inhibition is closely related to Ang-(1-7) stimulation on renal dopamine uptake. Both anantin and cANP (4-23-amide) did not modify CNP effects on 3H-dopamine uptake by tubular cells. The Mas receptor antagonist, A-779, blocked the increase elicited by Ang-(1-7) on 3H-dopamine uptake. The stimulatory uptake induced by Ang-(1-7) was even more pronounced in the presence of losartan, suggesting an inhibitory effect of Ang-(1-7) on AT1 receptors on 3H-dopamine uptake. By increasing dopamine bioavailability in tubular cells, Ang-(1-7) enhances Na+, K+-ATPase activity inhibition, contributing to its natriuretic and diuretic effects. PMID:27635280

  20. Regulation of Dopamine Uptake by Vasoactive Peptides in the Kidney.

    PubMed

    Rukavina Mikusic, N L; Kouyoumdzian, N M; Rouvier, E; Gironacci, M M; Toblli, J E; Fernández, B E; Choi, M R

    2016-01-01

    Considering the key role of renal dopamine in tubular sodium handling, we hypothesized that c-type natriuretic peptide (CNP) and Ang-(1-7) may regulate renal dopamine availability in tubular cells, contributing to Na(+), K(+)-ATPase inhibition. Present results show that CNP did not affect either (3)H-dopamine uptake in renal tissue or Na(+), K(+)-ATPase activity; meanwhile, Ang-(1-7) was able to increase (3)H-dopamine uptake and decreased Na(+), K(+)-ATPase activity in renal cortex. Ang-(1-7) and dopamine together decreased further Na(+), K(+)-ATPase activity showing an additive effect on the sodium pump. In addition, hydrocortisone reversed Ang-(1-7)-dopamine overinhibition on the enzyme, suggesting that this inhibition is closely related to Ang-(1-7) stimulation on renal dopamine uptake. Both anantin and cANP (4-23-amide) did not modify CNP effects on (3)H-dopamine uptake by tubular cells. The Mas receptor antagonist, A-779, blocked the increase elicited by Ang-(1-7) on (3)H-dopamine uptake. The stimulatory uptake induced by Ang-(1-7) was even more pronounced in the presence of losartan, suggesting an inhibitory effect of Ang-(1-7) on AT1 receptors on (3)H-dopamine uptake. By increasing dopamine bioavailability in tubular cells, Ang-(1-7) enhances Na(+), K(+)-ATPase activity inhibition, contributing to its natriuretic and diuretic effects.

  1. Molecular model of the neural dopamine transporter

    NASA Astrophysics Data System (ADS)

    Ravna, Aina Westrheim; Sylte, Ingebrigt; Dahl, Svein G.

    2003-05-01

    The dopamine transporter (DAT) regulates the action of dopamine by reuptake of the neurotransmitter into presynaptic neurons, and is the main molecular target of amphetamines and cocaine. DAT and the Na+/H+ antiporter (NhaA) are secondary transporter proteins that carry small molecules across a cell membrane against a concentration gradient, using ion gradients as energy source. A 3-dimensional projection map of the E. coli NhaA has confirmed a topology of 12 membrane spanning domains, and was previously used to construct a 3-dimensional NhaA model with 12 trans-membrane α-helices (TMHs). The NhaA model, and site directed mutagenesis data on DAT, were used to construct a detailed 3-dimensional DAT model using interactive molecular graphics and empiric force field calculations. The model proposes a dopamine transport mechanism involving TMHs 1, 3, 4, 5, 7 and 11. Asp79, Tyr252 and Tyr274 were the primary cocaine binding residues. Binding of cocaine or its analogue, (-)-2β-carbomethoxy-3β-(4-fluorophenyl)tropane (CFT), seemed to lock the transporter in an inactive state, and thus inhibit dopamine transport. The present model may be used to design further experimental studies of the molecular structure and mechanisms of DAT and other secondary transporter proteins.

  2. [Dopamine dysregulation syndrome in Parkinson's disease].

    PubMed

    Borg, M; Bayreuther, C

    2008-04-01

    Dopamine replacement therapy in Parkinson's disease ameliorates motor symptoms. However, it has recently been recognized that a small subgroup of patients suffer motor and behavioral disturbances attributable to taking quantities of medication well beyond the dose required to treat their motor disabilities. Dopamine dysregulation syndrome can be regarded as a pattern of compulsive medication use leading to disabling motor and behavioral features. The major theories of psychostimulant addiction may help explain some of the phenomena seen in the dopamine dysregulation syndrome. In contrast to the predictable pattern of severe degeneration of ventrolateral nigral dopaminergic cells, there is a smaller and more variable loss of dopamine neurons within the ventral tegmental areas. Sensitization of ventral striatal networks to antiparkinsonian therapy and appetitive behaviors may be analogous to the neuroplastic changes in the dorsal striatum thought to contribute to the motor complications of treatment such as dyskinesias. This syndrome greatly affects patients, their families and society. Treatment is difficult; deep brain stimulation of the subthalamic nucleus may therefore prove useful in some cases.

  3. Extracellular dopamine and alterations on dopamine transporter are related to reserpine toxicity in Caenorhabditis elegans.

    PubMed

    Reckziegel, Patrícia; Chen, Pan; Caito, Sam; Gubert, Priscila; Soares, Félix Alexandre Antunes; Fachinetto, Roselei; Aschner, Michael

    2016-03-01

    Reserpine is used as an animal model of parkinsonism. We hypothesized that the involuntary movements induced by reserpine in rodents are induced by dopaminergic toxicity caused by extracellular dopamine accumulation. The present study tested the effects of reserpine on the dopaminergic system in Caenorhabditis elegans. Reserpine was toxic to worms (decreased the survival, food intake, development and changed egg laying and defecation cycles). In addition, reserpine increased the worms' locomotor rate on food and decreased dopamine levels. Morphological evaluations of dopaminergic CEP neurons confirmed neurodegeneration characterized by decreased fluorescence intensity and the number of worms with intact CEP neurons, and increased number of shrunken somas per worm. These effects were unrelated to reserpine's effect on decreased expression of the dopamine transporter, dat-1. Interestingly, the locomotor rate on food and the neurodegenerative parameters fully recovered to basal conditions upon reserpine withdrawal. Furthermore, reserpine decreased survival in vesicular monoamine transporter and dat-1 loss-of-function mutant worms. In addition, worms pre-exposed to dopamine followed by exposure to reserpine had decreased survival. Reserpine activated gst-4, which controls a phase II detoxification enzymes downstream of nuclear factor (erythroid-derived-2)-like 2. Our findings establish that the dopamine transporter, dat-1, plays an important role in reserpine toxicity, likely by increasing extracellular dopamine concentrations.

  4. Impulse control disorders and dopamine dysregulation syndrome associated with dopamine agonist therapy in Parkinson's disease.

    PubMed

    Fenu, Sandro; Wardas, Jadwiga; Morelli, Micaela

    2009-09-01

    Over the last decade, evidence has emerged linking disorders in the impulsive-compulsive spectrum in Parkinson's disease to dopamine receptor agonist treatment. These disorders include hypersexuality, gambling and, to a minor extent, compulsive shopping and eating, as well as dopamine dysregulation syndrome, characterized by an addictive pattern toward dopamine replacement therapy and stereotyped behaviors, such as punding. These syndromes, which have only recently been recognized and are still underdiagnosed, have deleterious social consequences that warrant interventions at the clinical level and promotion of research at the preclinical level. In this review, we first provide a summary of features of Parkinson's disease and current pharmacological therapies associated with the development of dopamine dysregulation syndrome and impulsive-compulsive disorders. We also examine the dopamine receptors and brain areas important in reward and compulsive behaviors. We then critically examine the neuroadaptations in dopaminergic circuitries and the literature concerning gambling, hypersexuality, and other addictive behaviors in parkinsonian patients. Finally, we focus on suggestions pointing to a role for dopamine D(3) receptors and sensitization phenomena as the main factors which may be the origin of these disorders.

  5. Dopamine receptor in anterior byssus retractor muscle of Mytilus edulis.

    PubMed

    Takayanagi, I; Murakami, H; Iwayama, Y; Yoshida, Y; Miki, S

    1981-04-01

    Effects of dopamine, N-methyl-, ethyl- and propyl-derivatives of dopamine, and alpha- and beta-adrenoceptor stimulants on catch contraction of anterior byssus retractor muscle of Mytilus edulis were tested. The test drugs except the beta-adrenoceptor stimulants relaxed catch contraction. Dopamine was most active and substitution of amino group in dopamine with ethyl and propyl decreased activity considerably. The concentration-curves of dopamine, its derivatives and norepinephrine shifted in parallel with application of haloperidol but were not influenced by the alpha- and beta-adrenoceptor antagonists. These results suggest that relaxation of catch contraction by catecholamines is mediated through a dopamine receptor. This muscle is considered to be suitable for a study of the dopamine receptor.

  6. The impact of FOXO on dopamine and octopamine metabolism in Drosophila under normal and heat stress conditions

    PubMed Central

    Adonyeva, Natalya V.; Burdina, Elena V.; Karpova, Evgenia K.; Andreenkova, Olga V.; Gladkikh, Daniil V.; Ilinsky, Yury Y.; Rauschenbach, Inga Yu

    2016-01-01

    ABSTRACT The forkhead boxO transcription factor (FOXO) is a component of the insulin signalling pathway and plays a role in responding to adverse conditions, such as oxidative stress and starvation. In stressful conditions, FOXO moves from the cytosol to the nucleus where it activates gene expression programmes. Here, we show that FOXO in Drosophila melanogaster responds to heat stress as it does to other stressors. The catecholamine signalling pathway is another component of the stress response. In Drosophila, dopamine and octopamine levels rise steeply under heat, nutrition and mechanical stresses, which are followed by a decrease in the activity of synthesis enzymes. We demonstrate that the nearly twofold decline of FOXO expression in foxoBG01018 mutants results in dramatic changes in the metabolism of dopamine and octopamine and the overall response to stress. The absence of FOXO increases tyrosine decarboxylase activity, the first enzyme in octopamine synthesis, and decreases the enzymatic activity of enzymes in dopamine synthesis, alkaline phosphatase and tyrosine hydroxylase, in young Drosophila females. We identified the juvenile hormone as a mediator of FOXO regulation of catecholamine metabolism. Our findings suggest that FOXO is a possible trigger for endocrinological stress reactions. PMID:27754851

  7. Comparison of Monoamine Oxidase Inhibitors in Decreasing Production of the Autotoxic Dopamine Metabolite 3,4-Dihydroxyphenylacetaldehyde in PC12 Cells.

    PubMed

    Goldstein, David S; Jinsmaa, Yunden; Sullivan, Patti; Holmes, Courtney; Kopin, Irwin J; Sharabi, Yehonatan

    2016-02-01

    According to the catecholaldehyde hypothesis, the toxic dopamine metabolite 3,4-dihydroxyphenylacetaldehyde (DOPAL) contributes to the loss of nigrostriatal dopaminergic neurons in Parkinson's disease. Monoamine oxidase-A (MAO-A) catalyzes the conversion of intraneuronal dopamine to DOPAL and may serve as a therapeutic target. The "cheese effect"-paroxysmal hypertension evoked by tyramine-containing foodstuffs-limits clinical use of irreversible MAO-A inhibitors. Combined MAO-A/B inhibition decreases DOPAL production in rat pheochromocytoma PC12 cells, but whether reversible MAO-A inhibitors or MAO-B inhibitors decrease endogenous DOPAL production is unknown. We compared the potencies of MAO inhibitors in attenuating DOPAL production and examined possible secondary effects on dopamine storage, constitutive release, synthesis, and auto-oxidation. Catechol concentrations were measured in cells and medium after incubation with the irreversible MAO-A inhibitor clorgyline, three reversible MAO-A inhibitors, or the MAO-B inhibitors selegiline or rasagiline for 180 minutes. Reversible MAO-A inhibitors were generally ineffective, whereas clorgyline (1 nM), rasagiline (500 nM), and selegiline (500 nM) decreased DOPAL levels in the cells and medium. All three drugs also increased dopamine and norepinephrine, decreased 3,4-dihydroxyphenylalanine, and increased cysteinyl-dopamine concentrations in the medium, suggesting increased vesicular uptake and constitutive release, decreased dopamine synthesis, and increased dopamine spontaneous oxidation. In conclusion, clorgyline, rasagiline, and selegiline decrease production of endogenous DOPAL. At relatively high concentrations, the latter drugs probably lose their selectivity for MAO-B. Possibly offsetting increased formation of potentially toxic oxidation products and decreased formation of DOPAL might account for the failure of large clinical trials of MAO-B inhibitors to demonstrate slowing of neurodegeneration in Parkinson

  8. Comparison of Monoamine Oxidase Inhibitors in Decreasing Production of the Autotoxic Dopamine Metabolite 3,4-Dihydroxyphenylacetaldehyde in PC12 Cells

    PubMed Central

    Jinsmaa, Yunden; Sullivan, Patti; Holmes, Courtney; Kopin, Irwin J.; Sharabi, Yehonatan

    2016-01-01

    According to the catecholaldehyde hypothesis, the toxic dopamine metabolite 3,4-dihydroxyphenylacetaldehyde (DOPAL) contributes to the loss of nigrostriatal dopaminergic neurons in Parkinson’s disease. Monoamine oxidase-A (MAO-A) catalyzes the conversion of intraneuronal dopamine to DOPAL and may serve as a therapeutic target. The “cheese effect”—paroxysmal hypertension evoked by tyramine-containing foodstuffs—limits clinical use of irreversible MAO-A inhibitors. Combined MAO-A/B inhibition decreases DOPAL production in rat pheochromocytoma PC12 cells, but whether reversible MAO-A inhibitors or MAO-B inhibitors decrease endogenous DOPAL production is unknown. We compared the potencies of MAO inhibitors in attenuating DOPAL production and examined possible secondary effects on dopamine storage, constitutive release, synthesis, and auto-oxidation. Catechol concentrations were measured in cells and medium after incubation with the irreversible MAO-A inhibitor clorgyline, three reversible MAO-A inhibitors, or the MAO-B inhibitors selegiline or rasagiline for 180 minutes. Reversible MAO-A inhibitors were generally ineffective, whereas clorgyline (1 nM), rasagiline (500 nM), and selegiline (500 nM) decreased DOPAL levels in the cells and medium. All three drugs also increased dopamine and norepinephrine, decreased 3,4-dihydroxyphenylalanine, and increased cysteinyl-dopamine concentrations in the medium, suggesting increased vesicular uptake and constitutive release, decreased dopamine synthesis, and increased dopamine spontaneous oxidation. In conclusion, clorgyline, rasagiline, and selegiline decrease production of endogenous DOPAL. At relatively high concentrations, the latter drugs probably lose their selectivity for MAO-B. Possibly offsetting increased formation of potentially toxic oxidation products and decreased formation of DOPAL might account for the failure of large clinical trials of MAO-B inhibitors to demonstrate slowing of neurodegeneration in

  9. Mitochondrial reactive oxygen species mediate hypoxic down-regulation of hERG channel protein.

    PubMed

    Nanduri, Jayasri; Wang, Ning; Bergson, Pamela; Yuan, Guoxiang; Ficker, Eckhard; Prabhakar, Nanduri R

    2008-08-22

    Previous studies suggest that reactive oxygen species (ROS) play an important role in physiological responses to hypoxia. In the present study, we examined the effects of hypoxia on human ether-a-go-go related gene (hERG) channel protein expression and assessed the role of ROS. Hypoxia, in a stimulus- and time-dependent manner, decreased hERG protein with marked reduction in hERG K+ conductance in human embryonic kidney cells stably expressing the hERG alpha subunit. Down-regulation of hERG by hypoxia was not due to increased proteasomal degradation or decreased transcription but due to decreased synthesis of the protein. Hypoxia increased ROS in a time-dependent manner. Antioxidants prevented hypoxia-evoked down-regulation of hERG protein and exogenous oxidants mimicked the effects of hypoxia. Hypoxia-evoked down-regulation of hERG protein and elevation in ROS were absent in p(O) cells, which are devoid of mitochondrial DNA. Inhibitors of NADPH oxidase failed to prevent the effects of hypoxia. These results demonstrate that hypoxia enhances the production of ROS in the mitochondria, resulting in down-regulation of hERG translation and decreased hERG-mediated K+ conductance.

  10. N-Nicotinoyl dopamine inhibits skin pigmentation by suppressing of melanosome transfer.

    PubMed

    Kim, Bora; Hwang, Jae Sung; Kim, Hyun-Soo

    2015-12-15

    We investigated the inhibitory effects of a niacinamide derivative, N-Nicotinoyl dopamine (NND) on melanogenesis. NND inhibits melanosome transfer in a normal human melanocyte-keratinocyte co-culture system and through phagocytic ability without affecting viability of cells while it did not show inhibitory effects of tyrosinase and melanin synthesis in B16F10 mouse melanoma cells. In addition, safety of NND was verified through performing neural stem cell morphology assay. Our findings indicate that NND may potentially be used for cosmetic industry for improvement of skin whitening and therapies related with several skin disorders, and the effect of NND may be acquired via reduction of melanosome transfer.

  11. PNA-Based Multivalent Scaffolds Activate the Dopamine D2 Receptor

    PubMed Central

    2015-01-01

    Peptide nucleic acid scaffolds represent a promising tool to interrogate the multivalent effects of ligand binding to a membrane receptor. Dopamine D2 receptors (D2R) are a class of G-protein coupled receptors (GPCRs), and the formation of higher-ordered structures of these receptors has been associated with the progression of several neurological diseases. In this Letter, we describe the synthesis of a library of ligand-modified PNAs bearing a known D2R agonist, (±)-PPHT. The D2R activity for each construct was assessed, and the multivalent effects were evaluated. PMID:25893044

  12. Pharmacological characterization of the dopamine-sensitive adenylate cyclase in cockroach brain: evidence for a distinct dopamine receptor

    SciTech Connect

    Orr, G.L.; Gole, J.W.D.; Notman, H.J.; Downer, R.G.H.

    1987-12-21

    Dopamine increases cyclic AMP production in crude membrane preparations of cockroach brain with plateaus in cyclic AMP production occurring between 1-10 ..mu..M and 10 mM. Maximal production of cyclic AMP is 2.25 fold greater than that of control values. Octopamine also increases cyclic AMP production with a Ka of 1.4 ..mu..M and maximal production 3.5 fold greater than that of control. 5-Hydroxytryptamine does not increase cyclic AMP production. The effects of octopamine and dopamine are fully additive. The vertebrate dopamine agonists ADTN and epinine stimulate the dopamine-sensitive adenylate cyclase (AC) with Ka values of 4.5 and 0.6 ..mu..M respectively and with maximal effectiveness 1.7 fold greater than that of control. The selective D/sub 2/-dopamine agonist LY-171555 stimulates cyclic AMP production to a similar extent with a Ka of 50 ..mu..M. Other dopamine agonists have no stimulatory effects. With the exception of mianserin, /sup 3/H-piflutixol is displaced from brain membranes by dopamine antagonists with an order of potency similar to that observed for the inhibition of dopamine-sensitive AC. The results indicate that the octopamine- and dopamine-sensitive AC in cockroach brain can be distinguished pharmacologically and the dopamine receptors coupled to AC have pharmacological characteristics distinct from vertebrate D/sup 1/- and D/sup 2/-dopamine receptors. 33 references, 3 figures, 2 tables.

  13. Methamphetamine produces bidirectional, concentration-dependent effects on dopamine neuron excitability and dopamine-mediated synaptic currents

    PubMed Central

    Branch, Sarah Y.

    2012-01-01

    Amphetamine-like compounds are commonly used to enhance cognition and to treat attention deficit/hyperactivity disorder, but they also function as positive reinforcers and are self-administered at doses far exceeding clinical relevance. Many of these compounds (including methamphetamine) are substrates for dopamine reuptake transporters, elevating extracellular dopamine by inhibiting uptake and promoting reverse transport. This produces an increase in extracellular dopamine that inhibits dopamine neuron firing through autoreceptor activation and consequently blunts phasic dopamine neurotransmission, an important learning signal. However, these mechanisms do not explain the beneficial behavioral effects observed at clinically useful concentrations. In the present study, we have used patch-clamp electrophysiology in slices of mouse midbrain to show that, surprisingly, low concentrations of methamphetamine actually enhance dopamine neurotransmission and increase dopamine neuron firing through a dopamine transporter-mediated excitatory conductance. Both of these effects are reversed by higher concentrations of methamphetamine, which inhibit firing through dopamine D2 autoreceptor activation and decrease the peak amplitude of dopamine-mediated synaptic currents. These competing, concentration-dependent effects of methamphetamine suggest a mechanistic interplay by which lower concentrations of methamphetamine can overcome autoreceptor-mediated inhibition at the soma to increase phasic dopamine transmission. PMID:22592307

  14. Effects of indomethacin on plasma homovanillic acid concentration in normal subjects: a study of prostaglandin-dopamine interactions.

    PubMed

    Kahn, R S; Davidson, M; Kanof, P; McQueeney, R T; Singh, R R; Davis, K L

    1991-01-01

    In laboratory animals, prostaglandins have been shown to act as endogenous neuromodulators of central dopamine (DA) activity. To examine the interaction between prostaglandins and DA in man, the effect of a prostaglandin synthesis inhibitor, indomethacin, was studied on plasma concentrations of the DA metabolite, homovanillic acid (pHVA). Indomethacin (150 mg PO) as compared to placebo significantly elevated mean pHVA concentrations in eight normal subjects. Results of this study support the hypothesis that, as in animals, inhibition of prostaglandin synthesis increases central DA turnover in man.

  15. Sensorimotor impairment and elevated levels of dopamine metabolites in the neostriatum occur rapidly after intranigral injection of 6-hydroxydopamine or gamma-hydroxybutyrate in awake rats.

    PubMed

    Altar, C A; O'Neil, S; Marshall, J F

    1984-03-01

    The unilateral injection of 6-hydroxydopamine (8 micrograms) into the ventral tegmental area of awake rats produced a rapidly developing and irreversible sensory neglect to contralateral tactile stimuli. This neglect developed in a caudal to rostral direction on the affected body surface and coincided with significant elevation in the concentrations of dopamine and two of its metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the ipsilateral neostriatum. The unilateral injection of procaine or gamma-hydroxybutyric acid (GHB) into the substantia nigra of awake animals also produced a contralateral neglect that developed in a caudal to rostral direction, but the behavioral effect of these drugs diminished within 1 hr. Concentrations of dopamine, dihydroxyphenylacetic acid and homovanillic acid in the neostriatum were markedly elevated during continuous infusions of procaine or gamma-hydroxybutyric acid. The extent of sensory neglect and changes in dopamine metabolism in the neostriatum varied according to the amount of gamma-hydroxybutyric acid injected into the nigra and according to the proximity of injections of gamma-hydroxybutyric acid to the pars compacta. The rapid onset of sensory neglect following microinjections of 6-hydroxydopamine, procaine or gamma-hydroxybutyric acid is consistent with the ability of each of these drugs to block the conduction of impulses in mesostriatal neurons and suggests that concomitant increases in levels of dopamine, dihydroxyphenylacetic acid and homovanillic acid in the neostriatum resulted from decreases in the release of dopamine coupled with increased synthesis of dopamine. These findings also indicate that the catabolism of dopamine to dihydroxyphenylacetic acid or homovanillic acid may originate intraneuronally, without prior release of dopamine and its recapture by mesostriatal terminals, if the flow of impulses in this pathway has been blocked.

  16. Comparison of the Binding and Functional Properties of Two Structurally Different D2 Dopamine Receptor Subtype Selective Compounds

    PubMed Central

    2012-01-01

    We previously reported on the synthesis of substituted phenyl-4-hydroxy-1-piperidyl indole analogues with nanomolar affinity at D2 dopamine receptors, ranging from 10- to 100-fold selective for D2 compared to the D3 dopamine receptor subtype. More recently, we evaluated a panel of aripiprazole analogues, identifying several analogues that also exhibit D2 vs D3 dopamine receptor binding selectivity. These studies further characterize the intrinsic efficacy of the compound with the greatest binding selectivity from each chemical class, 1-((5-methoxy-1H-indol-3-yl)methyl)-4-(4-(methylthio)phenyl)piperidin-4-ol (SV 293) and 7-(4-(4-(2-methoxyphenyl)piperazin-1-yl)butoxy)-3,4-dihydroquinolin-2(1H)-one (SV-III-130s), using an adenylyl cyclase inhibition assay, a G-protein-coupled inward-rectifying potassium (GIRK) channel activation assay, and a cell based phospho-MAPK (pERK1/2) assay. SV 293 was found to be a neutral antagonist at D2 dopamine receptors using all three assays. SV-III-130s is a partial agonist using an adenylyl cyclase inhibition assay but an antagonist in the GIRK and phospho ERK1/2 assays. To define the molecular basis for the binding selectivity, the affinity of these two compounds was evaluated using (a) wild type human D2 and D3 receptors and (b) a panel of chimeric D2/D3 dopamine receptors. Computer-assisted modeling techniques were used to dock these compounds to the human D2 and D3 dopamine receptor subtypes. It is hoped that these studies on D2 receptor selective ligands will be useful in the future design of (a) receptor selective ligands used to define the function of D2-like receptor subtypes, (b) novel pharmacotherapeutic agents, and/or (c) in vitro and in vivo imaging agents. PMID:23259040

  17. Aggregated Single-Walled Carbon Nanotubes Absorb and Deform Dopamine-Related Proteins Based on Molecular Dynamics Simulations.

    PubMed

    Yu, Yi; Sun, Huiyong; Gilmore, Keith; Hou, Tingjun; Wang, Suidong; Li, Youyong

    2017-09-12

    Single-walled carbon nanotubes (SWCNTs) have attracted considerable attention owing to their applications in various fields such as biotechnology and biomedicine. Recently, aggregated SWCNTs have shown more significant effects on the treatment of methamphetamine addiction (Nat. Nanotech. 2016, 11, 613). However, the mechanisms underlying these actions are unclear. By using all-atom molecular dynamics simulations, we investigate the effects of single and aggregated SWCNTs (single-(10,10)CNT, aggregated-7-(10,10)CNTs, and single-(35,35)CNT with the same diameter as that of the aggregated one) on the activity of dopamine-related proteins [tyrosine hydroxylase (TyrOH) and dopamine transporter (DAT), which are related to the synthesis and transport of dopamine, respectively]. We find that both TyrOH and DAT can adsorb onto these SWCNTs. For TyrOH, the aggregated-7-(10,10)CNTs mainly affect the conformation of the active site of the protein, and hence, they are more effective in inhibiting the expression of TyrOH. For DAT, our results suggest that the aggregated-7-(10,10)CNTs allow DAT to maintain an outward-facing conformation and hence are favorable to the reuptake of dopamine. The binding of a dopamine reuptake inhibitor, [(3)H]-WIN35,428, to DAT is significantly disrupted by aggregated-7-(10,10)CNTs and hence improve the ability to transport dopamine. Our results provide the dynamic interactions of proteins with single/aggregated SWCNTs, which illustrate the mechanism of aggregated SWCNTs for the treatment of drug addiction.

  18. [Peripheral secretion and inactivation of catecholamines (adrenaline, noradrenaline, dopamine)].

    PubMed

    Peyrin, L; Dalmaz, Y

    1975-01-01

    In spite of the biochemical relationship between catecholamines (E,NE,DA), the unity of the adrenergic system is only apparent; catecholamines are present in numerous pools, which exhibit different anatomical and cellular localizations, secretory patterns, control of release, physiological functions, inactivation schemes and metabolic behaviour. The main sources of catecholamines in the periphery are the orthosympathetic nervous system, which is permanently active in maintaining homoeostasy, and the adrenal medulla, an essential element in the struggle against stress. In addition to these large pools, catecholamines are found also in extra adrenal chromaffin tissue and in sympathetic ganglions; the latter represents a potential store of amines, whilst ganglionic dopamine-rich interneurones are important links in the regulation of orthosympathetic activity. Rather than by a topographic distinction, it seems more satisfactory to classify the catecholamines spread in adrenergic fields into a small number of pools possessing their own physiological functions and inactivation patterns. Two main pools of catecholamines in the periphery may be described: The functional pool, represented by those catecholamines already released, or able to be released; in this pool are found plasma and adrenal medullary catecholamines and NE from sympathetic nerve endings. The tissue pool, consisting of the synthesis and storage compartments, which are poorly penetrated by plasma pool with respect to their high possibilities for synthesis and storage. Catecholamines from cellular bodies and axons of sympathetic neurons and a part of the adrenal medullary amines may be related to it. Two other pools of catecholamines have to be reported: a potential extrachromaffin pool, which is apparently negligible in the physiological state, but able to exhibit its synthetic and secretory capacities in particularly critical situations; an intraganglionic dopamine pool, which plays a modulator role in

  19. Clavulanic acid increases dopamine release in neuronal cells through a mechanism involving enhanced vesicle trafficking.

    PubMed

    Kost, Gina Chun; Selvaraj, Senthil; Lee, Young Bok; Kim, Deog Joong; Ahn, Chang-Ho; Singh, Brij B

    2011-10-24

    Clavulanic acid is a CNS-modulating compound with exceptional blood-brain barrier permeability and safety profile. Clavulanic acid has been proposed to have anti-depressant activity and is currently entering Phase IIb clinical trials for the treatment of Major Depressive Disorder (MDD). Studies have also shown that clavulanic acid suppresses anxiety and enhances sexual functions in rodent and primate models by a mechanism involving central nervous system (CNS) modulation, although its detailed mechanism of action has yet to be elucidated. To further examine its potential as a CNS modulating agent as well as its mechanism of action, we investigated the effects of clavulanic acid in neuronal cells. Our results indicate that clavulanic acid enhances dopamine release in PC12 and SH-SY5Y cells without affecting dopamine synthesis. Furthermore, using affinity chromatography we were able to identify two proteins, Munc18-1 and Rab4 that potentially bind to clavulanic acid and play a critical role in neurosecretion and the vesicle trafficking process. Consistent with this result, an increase in the translocation of Munc18-1 and Rab4 from the cytoplasm to the plasma membrane was observed in clavulanic acid treated cells. Overall, these data suggest that clavulanic acid enhances dopamine release in a mechanism involving Munc18-1 and Rab4 modulation and warrants further investigation of its therapeutic use in CNS disorders, such as depression. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  20. Dopamine D2 receptor mRNA measured in serial sections of the rat anterior pituitary.

    PubMed

    Piano, J Z; Pogacnik, A

    2001-01-01

    Dopamine D2 receptors (D2-Rs) on lactotrophs in the pituitary gland are targets for dopamine to inhibit prolactin synthesis and release. The aim of our study was to examine if subpopulations of cells in the anterior pituitary that respond differently to dopamine show different pattern of D2-R mRNA expression. Therefore, we have used quantitative in situ hybridization technique to study the localisation of D2-R mRNA in the rat adenohypophysis. Pituitary tissue was obtained from mature and 18 days old rats. Riboprobe was transcribed from rat pituitary cDNA clone encoding D2-R and hybridized in situ with the serial sections of the pituitaries. Our results show that, although the anterior lobe of the pituitary gland contains a variety of cell types distributed in clusters, D2-R mRNA is relatively evenly distributed through the adenohypophysis. Level of expression of D2-R mRNA in the pituitary is slightly higher in mature than in young rats.

  1. Presynaptic recording of quanta from midbrain dopamine neurons and modulation of the quantal size.

    PubMed

    Pothos, E N; Davila, V; Sulzer, D

    1998-06-01

    The observation of quantal release from central catecholamine neurons has proven elusive because of the absence of evoked rapid postsynaptic currents. We adapted amperometric methods to observe quantal release directly from axonal varicosities of midbrain dopamine neurons that predominantly contain small synaptic vesicles. Quantal events were elicited by high K+ or alpha-latrotoxin, required extracellular Ca2+, and were abolished by reserpine. The events indicated the release of 3000 molecules over 200 microsec, much smaller and faster events than quanta associated with large dense-core vesicles previously recorded in vertebrate preparations.