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Sample records for dopamine uptake sites

  1. Reduced number of caudate nucleus dopamine uptake sites in vascular dementia.

    PubMed

    Allard, P; Englund, E; Marcusson, J

    1999-01-01

    The dopamine (DA) uptake sites in the caudate nucleus were studied in patients with vascular dementia (VAD) and in a control group using the presynaptic DA uptake site marker [3H][2beta-carbomethoxy-3beta-(4-fluorophenyl) tropane] as radioligand. There was a significant decrease in the number of DA uptake sites in the VAD group, while the binding affinity was unchanged. The present results indicate that in the patients investigated, the cerebrovascular disease process involves dopaminergic neuron terminals in the caudate nucleus. Our findings are discussed in relation to the reductions in number of DA uptake sites that have previously been revealed in Alzheimer's and Parkinson's diseases.

  2. Dopamine uptake sites in the striatum are distributed differentially in striosome and matrix compartments

    SciTech Connect

    Graybiel, A.M.; Moratalla, R. )

    1989-11-01

    A major mechanism of neurotransmitter inactivation at catecholaminergic synapses in reuptake of released transmitter at high-affinity uptake sites on presynaptic terminals. The authors have analyzed the anatomical distribution of site-selective ligand binding for dopamine uptake sites in the striatum of rat, cat, and monkey. The authors report here that desipramine-sensitive ({sup 3}H)mazindol binding sites have highly heterogeneous distributions in the dorsal and the ventral striatum. In the caudate nucleus of cat and monkey, ({sup 3}H)mazindol binding observes striosomal ordering, being reduced in striosomes and heightened in the extrastriosomal matrix. Some local heterogeneity appears in the ventral caudoputamen of the rat. Different subdivisions of the nucleus accumbens also have different binding levels. These findings suggest that some functional effects of psychoactive drugs, such as cocaine, and that bind to the dopamine-uptake complex could be related to the distribution of these specific uptake sites. The findings also raise the possibility that these distributions could result in selective neuronal vulnerability to neurotoxins, such as 1-methyl-4-phenylpyridine (MPP{sup +}), that depend on the dopamine-uptake complex for entry into neurons.

  3. Differential visualization of dopamine and norepinephrine uptake sites in rat brain using (/sup 3/H)mazindol autoradiography

    SciTech Connect

    Javitch, J.A.; Strittmatter, S.M.; Snyder, S.H.

    1985-06-01

    Mazindol is a potent inhibitor of neuronal dopamine (DA) and norepinephrine (NE) uptake. DA and NE uptake sites in rat brain have been differentially visualized using (/sup 3/H)mazindol autoradiography. At appropriate concentrations, desipramine (DMI) selectively inhibits (/sup 3/H)mazindol binding to NE uptake sites without significantly affecting binding to DA uptake sites. The localization of DMI-insensitive specific (/sup 3/H) mazindol binding, reflecting DA uptake sites, is densest in the caudate-putamen, the nucleus accumbens, the olfactory tubercle, the subthalamic nucleus, the ventral tegmental area, the substantia nigra (SN) pars compacta, and the anterior olfactory nuclei. In contrast, the localization of DMI-sensitive specific (/sup 3/H)mazindol binding, representing NE uptake sites, is densest in the locus coeruleus, the nucleus of the solitary tract, the bed nucleus of the stria terminalis, the paraventricular and periventricular nuclei of the hypothalamus, and the anteroventral thalamus. The distribution of DMI-insensitive specific (/sup 3/H)mazindol binding closely parallels that of dopaminergic terminal and somatodendritic regions, while the distribution of DMI-sensitive specific (/sup 3/H)mazindol binding correlates well with the regional localization of noradrenergic terminals and cell bodies. Injection of 6-hydroxydopamine, ibotenic acid, or colchicine into the SN decreases (/sup 3/H)mazindol binding to DA uptake sites in the ipsilateral caudate-putamen by 85%. In contrast, ibotenic acid lesions of the caudate-putamen do not reduce (/sup 3/H)mazindol binding to either the ipsilateral or contralateral caudate-putamen.

  4. Comparison of characteristics of dopamine uptake and mazindol binding in mouse striatum.

    PubMed

    Zimányi, I; Lajtha, A; Reith, M E

    1989-12-01

    Biochemical and pharmacological studies suggest that the binding of [3H]mazindol is functionally related to the dopamine uptake carrier complex in rodent striatum. In order to study further the relationship between the substrate recognition site for dopamine uptake and the high-affinity binding site for mazindol the uptake of [3H]dopamine and the binding of [3H]mazindol was studied in BALB/cBy mouse striatum in various buffers (Tris, HEPES, bicarbonate-phosphate). Kinetic analysis showed that the Kd of the binding of [3H]mazindol and the Km of the uptake of [3H]dopamine was changed by different sodium concentrations and/or by the presence of Tris, while the Bmax and the Vmax remained essentially the same. However, the shape of the Na+ dependency curves was not the same for mazindol binding and dopamine uptake in the various buffers. The inhibitory effect of other cations such as K+ and Tris was also different on binding and uptake under similar experimental circumstances. Dopamine did not slow down the dissociation of mazindol from its site and this effect was not sodium-sensitive. These complexities can be accommodated by a model that involves overlapping sites for mazindol and dopamine on the dopamine uptake carrier complex, and translocation-reorientation steps. PMID:2615854

  5. 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.

  6. 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

  7. 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. PMID:27635280

  8. Dopamine uptake dynamics are preserved under isoflurane anesthesia.

    PubMed

    Brodnik, Zachary D; España, Rodrigo A

    2015-10-01

    Fast scan cyclic voltammetry is commonly used for measuring the kinetics of dopamine release and uptake. For experiments using an anesthetized preparation, urethane is preferentially used because it does not alter dopamine uptake kinetics compared to freely moving animals. Unfortunately, urethane is highly toxic, can induce premature death during experiments, and cannot be used for recovery surgeries. Isoflurane is an alternative anesthetic that is less toxic than urethane, produces a stable level of anesthesia over extended periods, and is often used for recovery surgeries. Despite these benefits, the effects of isoflurane on dopamine release and uptake have not been directly characterized. In the present studies, we assessed the utility of isoflurane for voltammetry experiments by testing dopamine signaling parameters under baseline conditions, after treatment with the dopamine uptake inhibitor cocaine, and after exposure to increasing concentrations of isoflurane. Our results indicate that surgical levels of isoflurane do not significantly alter terminal mechanisms of dopamine release and uptake over prolonged periods of time. Consequently, we propose that isoflurane is an acceptable anesthetic for voltammetry experiments, which in turn permits the design of studies in which dopamine signaling is examined under anesthesia prior to recovery and subsequent experimentation in the same animals. PMID:26321152

  9. [C-11]{beta}CNT: A new monoamine uptake ligand for studying serotonin and dopamine transporter sites in the living brain with PET

    SciTech Connect

    Mulholland, G.K.; Zheng, Q.H.; Zhou, F.C.

    1996-05-01

    There is considerable interest in measuring serotonin (5HT) and dopamine (DA) function in the human brain. Altered levels of 5HT and DA are recognized in drug abuse, neurotoxicities, psychiatric disorders, and neurodegenerative conditions including Alzheimer`s and Parkinson`s disease. Several phenyltropane analogs of cocaine bind tightly to both DA and 5HT uptake proteins. We have made a new agent from this class called {beta}CNT, 2{beta}-carboxymethyl-3{beta}-(2-naphthyl)-tropane, the isosteric O-for-CH{sub 2} analog of a compound reported to have among the highest measured affinities for DA and 5HT transporters and studied its in vivo brain distributions in animals for the first time. Optically pure {beta}CNT was made from cocaine, and labeled at the O-methyl position by esterification of {beta}CNT-acid with [C-11]CH{sub 3}OTfl under conditions similar to Wilson`s. HPLC-purified (99+%) final products (15-50% eob yield from CO{sub 2}, 40 min synth) had specific activities 0.1-1.2 Ci/{mu}mol at the time of injection. Preliminary [C-11]{beta}{beta}CNT rodent distribution showed very high brain uptake (3% ID at 60 min) and localization (striat: fr cort: hypo: cer: blood, 11: 5: 4: 1: 06). {beta}CNT-PET studies in juvenile pigs (5-20 mCi, 20-35 kg) found rapid brain uptake, and prominent retention (85 min) in midbrain, anterior brainstem and striatum, followed by cortex and olfactory bulb. Paroxetine pretreatment (5HT uptake blocker, 2mg/kg), diminished retention in most brain areas; nomifensine (DA/NE uptake blocker, 6 mg/kg) reduced striatum selectively. Direct comparisons of [C-11]{beta}CNT with other PET transporter radioligands {beta}CFT, {beta}CIT, and {beta}CTT (RTI-32) in the same pig found {beta}CNT had highest overall brain uptake among the agents. These initial results suggest {beta}CNT has favorable properties for imaging both 5HT and DA transporters in vivo, and further evaluation of its potential as a human PET agent is warranted.

  10. Antihistamine effect on synaptosomal uptake of serotonin, norepinephrine and dopamine

    NASA Technical Reports Server (NTRS)

    Brown, P. A.; Vernikos, J.

    1980-01-01

    A study on the effects of five H1 and H2 antihistamines on the synaptosomal uptake of serotonin (5HT), norepinephrine (NE), and dopamine (DA) is presented. Brain homogenates from female rats were incubated in Krebs-Ringer phosphate buffer solution in the presence of one of three radioactive neurotransmitters, and one of the five antihistamines. Low concentrations of pyrilamine competitively inhibited 5HT uptake, had little effect on NE uptake, and no effect on DA uptake. Promethazine, diphenhydramine, metiamide, and cimetidine had no effect on 5HT or DA uptake at the same concentration. Diphenhydramine had a small inhibitory effect on NE uptake. It is concluded that pyrilamine is a selective and potent competitive inhibitor of 5HT uptake at concentrations between .05 and .5 micromolars.

  11. Selective MPP+ uptake into synaptic dopamine vesicles: possible involvement in MPTP neurotoxicity.

    PubMed Central

    Del Zompo, M.; Piccardi, M. P.; Ruiu, S.; Quartu, M.; Gessa, G. L.; Vaccari, A.

    1993-01-01

    1. In the present study we provide evidence for a saturable, Mg2+/ATP- and temperature-dependent, tetrabenazine-, dopamine-, and amphetamine-sensitive uptake of 1-methyl-4-phenylpyridinium ion (MPP+) in synaptic vesicles from mouse striatum. 2. Similarity in the properties of the vesicular uptake suggests that in the striatum dopamine and MPP+ share the vesicular carrier. 3. The presence of MPP+ vesicular uptake in dopamine-rich regions such as striatum, olfactory, tubercles and hypothalamus, as well as its absence in cerebellum, cortex and pons-medulla, suggest that monoamine vesicular carriers differ between highly and poorly dopamine-innervated regions. 4. The restriction of active MPP+ uptake to the dopaminergic regions, which reflects the previously shown distribution of [3H]-MPP+ binding sites in mouse brain membranes, indicates MPP+ as a marker of the vesicular carrier for dopamine in dopaminergic neurones. 5. A role in MPP+ neurotoxicity is suggested for this region-specific, vesicular storage of the toxin. Images Figure 1 PMID:8102929

  12. Atypical Dopamine Uptake Inhibitors that Provide Clues About Cocaine's Mechanism at the Dopamine Transporter

    NASA Astrophysics Data System (ADS)

    Hauck Newman, Amy; Katz, Jonathan L.

    The dopamine transporter (DAT) has been a primary target for cocaine abuse/addiction medication discovery. However predicted addiction liability and limited clinical evaluation has provided a formidable challenge for development of these agents for human use. The unique and atypical pharmacological profile of the benztropine (BZT) class of dopamine uptake inhibitors, in preclinical models of cocaine effects and abuse, has encouraged further development of these agents. Moreover, in vivo studies have challenged the original DAT hypothesis and demonstrated that DAT occupancy and subsequent increases in dopamine produced by BZT analogues are significantly delayed and long lasting, as compared to cocaine. These important and distinctive elements are critical to the lack of abuse liability among BZT analogues, and improve their potential for development as treatments for cocaine abuse and possibly other neuropsychiatric disorders.

  13. Role of Histidine 547 of Human Dopamine Transporter in Molecular Interaction with HIV-1 Tat and Dopamine Uptake

    PubMed Central

    Yuan, Yaxia; Quizon, Pamela M.; Sun, Wei-Lun; Yao, Jianzhuang; Zhu, Jun; Zhan, Chang-Guo

    2016-01-01

    HIV-1 Tat plays an important role in HIV-associated neurocognitive disorders (HAND) by disrupting neurotransmission including dopamine uptake by human dopamine transporter (hDAT). Previous studies have demonstrated that HIV-1 Tat directly binds to hDAT and some amino-acid mutations that attenuate the hDAT-Tat binding also significantly decreased dopamine uptake activity of hDAT. This combined computational-experimental study demonstrates that histidine-547 (H547) of hDAT plays a crucial role in the hDAT-Tat binding and dopamine uptake by hDAT, and that the H547A mutation can not only considerably attenuate Tat-induced inhibition of dopamine uptake, but also significantly increase the Vmax of hDAT for dopamine uptake. The finding of such an unusual hDAT mutant capable of both increasing the Vmax of hDAT for dopamine uptake and disrupting the hDAT-Tat binding may provide an exciting knowledge basis for development of novel concepts for therapeutic treatment of the HAND. PMID:27250920

  14. Striatal dopamine neurotransmission: regulation of release and uptake

    PubMed Central

    Sulzer, David; Cragg, Stephanie J.; Rice, Margaret E.

    2016-01-01

    Dopamine (DA) transmission is governed by processes that regulate release from axonal boutons in the forebrain and the somatodendritic compartment in midbrain, and by clearance by the DA transporter, diffusion, and extracellular metabolism. We review how axonal DA release is regulated by neuronal activity and by autoreceptors and heteroreceptors, and address how quantal release events are regulated in size and frequency. In brain regions densely innervated by DA axons, DA clearance is due predominantly to uptake by the DA transporter, whereas in cortex, midbrain, and other regions with relatively sparse DA inputs, the norepinephrine transporter and diffusion are involved. We discuss the role of DA uptake in restricting the sphere of influence of DA and in temporal accumulation of extracellular DA levels upon successive action potentials. The tonic discharge activity of DA neurons may be translated into a tonic extracellular DA level, whereas their bursting activity can generate discrete extracellular DA transients. PMID:27141430

  15. The binding sites for benztropines and dopamine in the dopamine transporter overlap.

    PubMed

    Bisgaard, Heidi; Larsen, M Andreas B; Mazier, Sonia; Beuming, Thijs; Newman, Amy Hauck; Weinstein, Harel; Shi, Lei; Loland, Claus J; Gether, Ulrik

    2011-01-01

    Analogs of benztropines (BZTs) are potent inhibitors of the dopamine transporter (DAT) but are less effective than cocaine as behavioral stimulants. As a result, there have been efforts to evaluate these compounds as leads for potential medication for cocaine addiction. Here we use computational modeling together with site-directed mutagenesis to characterize the binding site for BZTs in DAT. Docking into molecular models based on the structure of the bacterial homolog LeuT supported a BZT binding site that overlaps with the substrate-binding pocket. In agreement, mutations of residues within the pocket, including(2) Val152(3.46) to Ala or Ile, Ser422(8.60) to Ala and Asn157(3.51) to Cys or Ala, resulted in decreased affinity for BZT and the analog JHW007, as assessed in [(3)H]dopamine uptake inhibition assays and/or [(3)H]CFT competition binding assay. A putative polar interaction of one of the phenyl ring fluorine substituents in JHW007 with Asn157(3.51) was used as a criterion for determining likely binding poses and establish a structural context for the mutagenesis findings. The analysis positioned the other fluorine-substituted phenyl ring of JHW007 in close proximity to Ala479(10.51)/Ala480(10.52) in transmembrane segment (TM) 10. The lack of such an interaction for BZT led to a more tilted orientation, as compared to JHW007, bringing one of the phenyl rings even closer to Ala479(10.51)/Ala480(10.52). Mutation of Ala479(10.51) and Ala480(10.52) to valines supported these predictions with a larger decrease in the affinity for BZT than for JHW007. Summarized, our data suggest that BZTs display a classical competitive binding mode with binding sites overlapping those of cocaine and dopamine.

  16. The binding sites for benztropines and dopamine in the dopamine transporter overlap

    PubMed Central

    Bisgaard, Heidi; Larsen, M. Andreas B.; Mazier, Sonia; Beuming, Thijs; Newman, Amy Hauck; Weinstein, Harel; Shi, Lei; Loland, Claus J.; Gether, Ulrik

    2013-01-01

    Analogues of benztropines (BZTs) are potent inhibitors of the dopamine transporter (DAT) but are less effective than cocaine as behavioral stimulants. As a result, there have been efforts to evaluate these compounds as leads for potential medication for cocaine addiction. Here we use computational modeling together with site-directed mutagenesis to characterize the binding site for BZTs in DAT. Docking into molecular models based on the structure of the bacterial homologue LeuT supported a BZT binding site that overlaps with the substrate binding pocket. In agreement, mutations of residues within the pocket, including Val1523.46* to Ala or Ile, Ser4228.60 to Ala and Asn1573.51 to Cys or Ala, resulted in decreased affinity for BZT and the analog JHW007, as assessed in [3H]dopamine uptake inhibition assays and/or [3H]CFT competition binding assay. A putative polar interaction of one of the phenyl ring fluorine substituents in JHW007 with Asn1573.51 was used as a criterion for determining likely binding poses and establish a structural context for the mutagenesis findings. The analysis positioned the other fluorine substituted phenyl ring of JHW007 in close proximity to Ala47910.51/Ala48010.52 in transmembrane segment (TM) 10. The lack of such an interaction for BZT led to a more tilted orientation, as compared to JHW007, bringing one of the phenyl rings even closer to Ala47910.51/Ala48010.52. Mutation of Ala47910.51 and Ala48010.52 to valines supported these predictions with a larger decrease in the affinity for BZT than for JHW007. Summarized, our data suggest that BZTs display a classical competitive binding mode with binding sites overlapping those of cocaine and dopamine. PMID:20816875

  17. Prolonged treatment with pramipexole promotes physical interaction of striatal dopamine D3 autoreceptors with dopamine transporters to reduce dopamine uptake.

    PubMed

    Castro-Hernández, Javier; Afonso-Oramas, Domingo; Cruz-Muros, Ignacio; Salas-Hernández, Josmar; Barroso-Chinea, Pedro; Moratalla, Rosario; Millan, Mark J; González-Hernández, Tomás

    2015-02-01

    The dopamine (DA) transporter (DAT), a membrane glycoprotein expressed in dopaminergic neurons, clears DA from extracellular space and is regulated by diverse presynaptic proteins like protein kinases, α-synuclein, D2 and D3 autoreceptors. DAT dysfunction is implicated in Parkinson's disease and depression, which are therapeutically treated by dopaminergic D2/D3 receptor (D2/D3R) agonists. It is, then, important to improve our understanding of interactions between D3R and DAT. We show that prolonged administration of pramipexole (0.1mg/kg/day, 6 to 21 days), a preferential D3R agonist, leads to a decrease in DA uptake in mouse striatum that reflects a reduction in DAT affinity for DA in the absence of any change in DAT density or subcellular distribution. The effect of pramipexole was absent in mice with genetically-deleted D3R (D3R(-/-)), yet unaffected in mice genetically deprived of D2R (D2R(-/-)). Pramipexole treatment induced a physical interaction between D3R and DAT, as assessed by co-immunoprecipitation and in situ proximity ligation assay. Furthermore, it promoted the formation of DAT dimers and DAT association with both D2R and α-synuclein, effects that were abolished in D3R(-/-) mice, yet unaffected in D2R(-/-) mice, indicating dependence upon D3R. Collectively, these data suggest that prolonged treatment with dopaminergic D3 agonists provokes a reduction in DA reuptake by dopaminergic neurons related to a hitherto-unsuspected modification of the DAT interactome. These observations provide novel insights into the long-term antiparkinson, antidepressant and additional clinical actions of pramipexole and other D3R agonists. PMID:25511804

  18. Impaired Brain Dopamine and Serotonin Release and Uptake in Wistar Rats Following Treatment with Carboplatin.

    PubMed

    Kaplan, Sam V; Limbocker, Ryan A; Gehringer, Rachel C; Divis, Jenny L; Osterhaus, Gregory L; Newby, Maxwell D; Sofis, Michael J; Jarmolowicz, David P; Newman, Brooke D; Mathews, Tiffany A; Johnson, Michael A

    2016-06-15

    Chemotherapy-induced cognitive impairment, known also as "chemobrain", is a medical complication of cancer treatment that is characterized by a general decline in cognition affecting visual and verbal memory, attention, complex problem solving skills, and motor function. It is estimated that one-third of patients who undergo chemotherapy treatment will experience cognitive impairment. Alterations in the release and uptake of dopamine and serotonin, central nervous system neurotransmitters that play important roles in cognition, could potentially contribute to impaired intellectual performance in those impacted by chemobrain. To investigate how chemotherapy treatment affects these systems, fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes was used to measure dopamine and serotonin release and uptake in coronal brain slices containing the striatum and dorsal raphe nucleus, respectively. Measurements were taken from rats treated weekly with selected doses of carboplatin and from control rats treated with saline. Modeling the stimulated dopamine release plots revealed an impairment of dopamine release per stimulus pulse (80% of saline control at 5 mg/kg and 58% at 20 mg/kg) after 4 weeks of carboplatin treatment. Moreover, Vmax, the maximum uptake rate of dopamine, was also decreased (55% of saline control at 5 mg/kg and 57% at 20 mg/kg). Nevertheless, overall dopamine content, measured in striatal brain lysates by high performance liquid chromatography, and reserve pool dopamine, measured by FSCV after pharmacological manipulation, did not significantly change, suggesting that chemotherapy treatment selectively impairs the dopamine release and uptake processes. Similarly, serotonin release upon electrical stimulation was impaired (45% of saline control at 20 mg/kg). Measurements of spatial learning discrimination were taken throughout the treatment period and carboplatin was found to alter cognition. These studies support the need for additional

  19. Impaired Brain Dopamine and Serotonin Release and Uptake in Wistar Rats Following Treatment with Carboplatin

    PubMed Central

    2016-01-01

    Chemotherapy-induced cognitive impairment, known also as “chemobrain”, is a medical complication of cancer treatment that is characterized by a general decline in cognition affecting visual and verbal memory, attention, complex problem solving skills, and motor function. It is estimated that one-third of patients who undergo chemotherapy treatment will experience cognitive impairment. Alterations in the release and uptake of dopamine and serotonin, central nervous system neurotransmitters that play important roles in cognition, could potentially contribute to impaired intellectual performance in those impacted by chemobrain. To investigate how chemotherapy treatment affects these systems, fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes was used to measure dopamine and serotonin release and uptake in coronal brain slices containing the striatum and dorsal raphe nucleus, respectively. Measurements were taken from rats treated weekly with selected doses of carboplatin and from control rats treated with saline. Modeling the stimulated dopamine release plots revealed an impairment of dopamine release per stimulus pulse (80% of saline control at 5 mg/kg and 58% at 20 mg/kg) after 4 weeks of carboplatin treatment. Moreover, Vmax, the maximum uptake rate of dopamine, was also decreased (55% of saline control at 5 mg/kg and 57% at 20 mg/kg). Nevertheless, overall dopamine content, measured in striatal brain lysates by high performance liquid chromatography, and reserve pool dopamine, measured by FSCV after pharmacological manipulation, did not significantly change, suggesting that chemotherapy treatment selectively impairs the dopamine release and uptake processes. Similarly, serotonin release upon electrical stimulation was impaired (45% of saline control at 20 mg/kg). Measurements of spatial learning discrimination were taken throughout the treatment period and carboplatin was found to alter cognition. These studies support the need for additional

  20. Mice expressing markedly reduced striatal dopamine transporters exhibit increased locomotor activity, dopamine uptake turnover rate, and cocaine responsiveness.

    PubMed

    Rao, Anjali; Sorkin, Alexander; Zahniser, Nancy R

    2013-10-01

    Variations in the expression levels of the dopamine transporter (DAT) can influence responsiveness to psychostimulant drugs like cocaine. To better understand this relationship, we studied a new DAT-low expresser (DAT-LE) mouse model and performed behavioral and biochemical studies with it. Immunoblotting and [(3) H]WIN 35,428 binding analyses revealed that these mice express ∼35% of wildtype (WT) mouse striatal DAT levels. Compared to WT mice, DAT-LE mice were hyperactive in a novel open-field environment. Despite their higher basal locomotor activity, cocaine (10 or 20 mg/kg, i.p.) induced greater locomotor activation in DAT-LE mice than in WT mice. The maximal velocity (Vmax ) of DAT-mediated [(3) H]DA uptake into striatal synaptosomes was reduced by 46% in DAT-LE mice, as compared to WT. Overall, considering the reduced number of DAT binding sites (Bmax ) along with the reduced Vmax in DAT-LE mice, a 2-fold increase in DA uptake turnover rate (Vmax /Bmax ) was found, relative to WT mice. This suggests that neuroadaptive changes have occurred in the DAT-LE mice that would help to compensate for their low DAT numbers. Interestingly, these changes do not include a reduction in tyrosine hydroxylase levels, as was previously reported in DAT knockout homozygous and heterozygous animals. Further, these changes are not sufficient to prevent elevated novelty- and cocaine-induced locomotor activity. Hence, these mice represent a unique model for studying changes of in vivo DAT function and regulation that result from markedly reduced levels of DAT expression. PMID:23564231

  1. Mice expressing markedly reduced striatal dopamine transporters exhibit increased locomotor activity, dopamine uptake turnover rate, and cocaine responsiveness.

    PubMed

    Rao, Anjali; Sorkin, Alexander; Zahniser, Nancy R

    2013-10-01

    Variations in the expression levels of the dopamine transporter (DAT) can influence responsiveness to psychostimulant drugs like cocaine. To better understand this relationship, we studied a new DAT-low expresser (DAT-LE) mouse model and performed behavioral and biochemical studies with it. Immunoblotting and [(3) H]WIN 35,428 binding analyses revealed that these mice express ∼35% of wildtype (WT) mouse striatal DAT levels. Compared to WT mice, DAT-LE mice were hyperactive in a novel open-field environment. Despite their higher basal locomotor activity, cocaine (10 or 20 mg/kg, i.p.) induced greater locomotor activation in DAT-LE mice than in WT mice. The maximal velocity (Vmax ) of DAT-mediated [(3) H]DA uptake into striatal synaptosomes was reduced by 46% in DAT-LE mice, as compared to WT. Overall, considering the reduced number of DAT binding sites (Bmax ) along with the reduced Vmax in DAT-LE mice, a 2-fold increase in DA uptake turnover rate (Vmax /Bmax ) was found, relative to WT mice. This suggests that neuroadaptive changes have occurred in the DAT-LE mice that would help to compensate for their low DAT numbers. Interestingly, these changes do not include a reduction in tyrosine hydroxylase levels, as was previously reported in DAT knockout homozygous and heterozygous animals. Further, these changes are not sufficient to prevent elevated novelty- and cocaine-induced locomotor activity. Hence, these mice represent a unique model for studying changes of in vivo DAT function and regulation that result from markedly reduced levels of DAT expression.

  2. Interaction between diffusion and Michaelis-Menten uptake of dopamine after iontophoresis in striatum.

    PubMed Central

    Nicholson, C

    1995-01-01

    A quantitative description of the behavior of a neurotransmitter in the brain extracellular microenvironment requires an understanding of the relative importance of diffusion versus uptake processes. This paper models the behavior of dopamine released from a small iontophoresis electrode and its voltammetric detection by a carbon fiber sensor 100 microns away as a basis for developing a new paradigm for measuring dopamine kinetics in intact rat neostriatum. The diffusion equation incorporating uptake, characterized by a maximum velocity Vmax and a Michaelis-Menten constant Km, was transformed to an integral equation and solved numerically for the dopamine concentration, C. Analytical solutions were derived for limiting cases of a steady-state free-boundary problem when C >> Km and the linear time-dependent problem when C << Km. These solutions were compared with complete numerical solutions, both for normal uptake (Vmax = 0.2 or 0.8 microM s-1; Km = 0.15 microM), and in the presence of the uptake blocker nomifensine (Km = 6 microM). The results suggest that an experimental strategy for the quantitative analysis of dopamine, and other compounds, in living tissue is to fit a family of concentration versus time curves generated with different iontophoretic current strengths and recorded with a microsensor, to the numerical solution of the diffusion-uptake equation. PMID:7612814

  3. Vascular Effects of Diphenylmethoxypiperidine-derived Dopamine Uptake Inhibitors

    PubMed Central

    Pulgar, Victor M.; Harp, Jill Keith

    2014-01-01

    Vascular effects of 4-aryl methoxypiperidinol compounds previously shown to share with cocaine the ability to inhibit the dopamine transporter are described. All the compounds tested inhibit KCl-induced and noradrenaline-dependent contractions in mesenteric arteries ex vivo. Thus, diphenylpyraline and its analogs may have a role as therapeutic options for the treatment of some of the cardiotoxic effects of cocaine intoxications. PMID:24792462

  4. Dopamine transport sites selectively labeled by a novel photoaffinity probe: 125I-DEEP

    SciTech Connect

    Grigoriadis, D.E.; Wilson, A.A.; Lew, R.; Sharkey, J.S.; Kuhar, M.J. )

    1989-08-01

    The dopamine transporter was labeled using a photosensitive compound related to GBR-12909, {sup 125}I-1-(2-(diphenylmethoxy)ethyl)-4-(2- (4-azido-3-iodophenyl)ethyl)piperazine ({sup 125}I-DEEP). {sup 125}I-DEEP bound reversibly and with high affinity to the dopamine transport protein in the absence of light and could be covalently attached to the protein following exposure to UV light. In rat striatal homogenates, {sup 125}I-DEEP was found to incorporate covalently into a protein with apparent molecular weight of 58,000 Da. The properties of this binding protein were characteristic of the dopamine transporter since covalent attachment could be inhibited by dopamine-uptake blockers with the proper pharmacological rank order of potencies. Covalent binding was also inhibited in a stereospecific manner by (+) and (-) cocaine, as well as other cocaine analogs. The protein was not found in the cerebellum. The dopamine transporter appears to exist in a glycosylated form since photoaffinity-labeled transport sites could adsorb to wheat germ-agglutinin and could be specifically eluted from the column by beta-N-acetylglucosamine.

  5. Amperozide, a putative anti-psychotic drug: Uptake inhibition and release of dopamine in vitro in the rat brain

    SciTech Connect

    Eriksson, E. )

    1990-01-01

    The effects of amperozide (a diphenylbutylpiperazinecarboxamide derivative) on the uptake and release of {sup 3}H-dopamine in vitro were investigated. Amperozide inhibited the amphetamine-stimulated release of dopamine from perfused rat striatal tissue in a dose-dependent manner. With 1 and 10 {mu}m amperozide there was significant inhibition of the amphetamine-stimulated release of dopamine, to 44 and 36 % of control. In contrast, 10 {mu}M amperozide significantly strengthened the electrically stimulated release of dopamine from perfused striatal slices. Amperozide 1-10 {mu}M had no significant effect on the potassium-stimulated release of dopamine, 10 {mu}M amperozide also slightly increased the basal release of {sup 3}H-dopamine from perfused striatal tissue. These effects on various types of release are similar to those reported for uptake inhibitors. The uptake of dopamine in striatal tissue was inhibited by amperozide with IC{sub 50} values of 18 {mu}M for uptake in chopped tissue and 1.0 {mu}M for uptake in synaptosomes. Amperozide also inhibited the uptake of serotonin in synaptosomes from frontal cortex, IC{sub 50} = 0.32 {mu}M and the uptake of noradrenaline in cortical synaptosomes, IC{sub 50} = 0.78 {mu}M.

  6. Dopamine Release and Uptake Impairments and Behavioral Alterations Observed in Mice that Model Fragile X Mental Retardation Syndrome.

    PubMed

    Fulks, Jenny L; O'Bryhim, Bliss E; Wenzel, Sara K; Fowler, Stephen C; Vorontsova, Elena; Pinkston, Jonathan W; Ortiz, Andrea N; Johnson, Michael A

    2010-10-20

    In this study we evaluated the relationship between amphetamine-induced behavioral alterations and dopamine release and uptake characteristics in Fmr1 knockout (Fmr1 KO) mice, which model fragile X syndrome. The behavioral analyses, obtained at millisecond temporal resolution and 2 mm spatial resolution using a force-plate actometer, revealed that Fmr1 KO mice express a lower degree of focused stereotypy compared to wild type (WT) control mice after injection with 10 mg/kg (ip) amphetamine. To identify potentially related neurochemical mechanisms underlying this phenomenon, we measured electrically-evoked dopamine release and uptake using fast-scan cyclic voltammetry at carbon-fiber microelectrodes in striatal brain slices. At 10 weeks of age, dopamine release per pulse, which is dopamine release corrected for differences in uptake, was unchanged. However, at 15 (the age of behavioral testing) and 20 weeks of age, dopamine per pulse and the maximum rate of dopamine uptake was diminished in Fmr1 KO mice compared to WT mice. Dopamine uptake measurements, obtained at different amphetamine concentrations, indicated that dopamine transporters in both genotypes have equal affinities for amphetamine. Moreover, dopamine release measurements from slices treated with quinpirole, a D2-family receptor agonist, rule out enhanced D2 autoreceptor sensitivity as a mechanism of release inhibition. However, dopamine release, uncorrected for uptake and normalized against the corresponding pre-drug release peaks, increased in Fmr1 KO mice, but not in WT mice. Collectively, these data are consistent with a scenario in which a decrease in extracellular dopamine levels in the striatum result in diminished expression of focused stereotypy in Fmr1 KO mice.

  7. Dopamine Release and Uptake Impairments and Behavioral Alterations Observed in Mice that Model Fragile X Mental Retardation Syndrome

    PubMed Central

    2010-01-01

    In this study, we evaluated the relationship between amphetamine-induced behavioral alterations and dopamine release and uptake characteristics in Fmr1 knockout (Fmr1 KO) mice, which model fragile X syndrome. The behavioral analyses, obtained at millisecond temporal resolution and 2 mm spatial resolution using a force-plate actometer, revealed that Fmr1 KO mice express a lower degree of focused stereotypy compared with wild-type (WT) control mice after injection with 10 mg/kg (ip) amphetamine. To identify potentially related neurochemical mechanisms underlying this phenomenon, we measured electrically evoked dopamine release and uptake using fast-scan cyclic voltammetry at carbon-fiber microelectrodes in striatal brain slices. At 10 weeks of age, dopamine release per pulse, which is dopamine release corrected for differences in uptake, was unchanged. However, at 15 (the age of behavioral testing) and 20 weeks of age, dopamine per pulse and the maximum rate of dopamine uptake was diminished in Fmr1 KO mice compared with WT mice. Dopamine uptake measurements, obtained at different amphetamine concentrations, indicated that dopamine transporters in both genotypes have equal affinities for amphetamine. Moreover, dopamine release measurements from slices treated with quinpirole, a D2-family receptor agonist, rule out enhanced D2 autoreceptor sensitivity as a mechanism of release inhibition. However, dopamine release, uncorrected for uptake and normalized against the corresponding predrug release peaks, increased in Fmr1 KO mice, but not in WT mice. Collectively, these data are consistent with a scenario in which a decrease in extracellular dopamine levels in the striatum result in diminished expression of focused stereotypy in Fmr1 KO mice. PMID:21116467

  8. Correlation between (/sup 3/H)dopamine specific uptake and (/sup 3/H)GBR 12783 specific binding during the maturation of rat striatum

    SciTech Connect

    Bonnet, J.J.; Costentin, J.

    1989-01-01

    The development of the specific uptake of dopamine in the rat striatum during the early postnatal period is compared with the ontogenetic changes of the specific binding of (/sup 3/H)GBR 12783 to the site of uptake inhibition. During maturation, the increase in the specific binding of (/sup 3/H)GBR 12783 parallels the increase in the specific uptake of dopamine. (/sup 3/H)GBR 12783 specific binding sites increase in number from day 1 postpartum until 40 days, when they reach the adult level. In 40 day-old rats, the weight of the striatum represents 80% of adult values. The affinity of (/sup 3/H)GBR 12783 for the inhibition site is similar in membrane preparations obtained from 6 day-old pups and adults; this results in a same ability of the inhibitor to block the specific uptake of dopamine into synaptosomes obtained from pups or adult rats. These data support the hypothesis of the existence of a single molecular entity including both the inhibition site and the carrier itself.

  9. Impact of disruption of secondary binding site S2 on dopamine transporter function.

    PubMed

    Zhen, Juan; Reith, Maarten E A

    2016-09-01

    The structures of the leucine transporter, drosophila dopamine transporter, and human serotonin transporter show a secondary binding site (designated S2 ) for drugs and substrate in the extracellular vestibule toward the membrane exterior in relation to the primary substrate recognition site (S1 ). The present experiments are aimed at disrupting S2 by mutating Asp476 and Ile159 to Ala. Both mutants displayed a profound decrease in [(3) H]DA uptake compared with wild-type associated with a reduced turnover rate kcat . This was not caused by a conformational bias as the mutants responded to Zn(2+) (10 μM) similarly as WT. The dopamine transporters with either the D476A or I159A mutation both displayed a higher Ki for dopamine for the inhibition of [3H](-)-2-β-carbomethoxy-3-β-(4-fluorophenyl)tropane binding than did the WT transporter, in accordance with an allosteric interaction between the S1 and S2 sites. The results provide evidence in favor of a general applicability of the two-site allosteric model of the Javitch/Weinstein group from LeuT to dopamine transporter and possibly other monoamine transporters. X-ray structures of transporters closely related to the dopamine (DA) transporter show a secondary binding site S2 in the extracellular vestibule proximal to the primary binding site S1 which is closely linked to one of the Na(+) binding sites. This work examines the relationship between S2 and S1 sites. We found that S2 site impairment severely reduced DA transport and allosterically reduced S1 site affinity for the cocaine analog [(3) H]CFT. Our results are the first to lend direct support for the application of the two-site allosteric model, advanced for bacterial LeuT, to the human DA transporter. The model states that, after binding of the first DA molecule (DA1 ) to the primary S1 site (along with Na(+) ), binding of a second DA (DA2 ) to the S2 site triggers, through an allosteric interaction, the release of DA1 and Na(+) into the cytoplasm. PMID

  10. Elimination of extracellular dopamine in the medial prefrontal cortex of conscious mice analysed using selective enzyme and uptake inhibitors.

    PubMed

    Tammimaki, A; Aonurm-Helm, A; Kaenmaki, M; Mannisto, P T

    2016-04-01

    We have shown in a previous study that in the medial prefrontal cortex (mPFC) of Comt knockout animals, uptake1 followed by oxidation accounts for approximately 50% and uptake2 followed by O-methylation for the remaining 50% of dopamine clearance. However, compensatory mechanisms in genetically modified animals may have affected the result. Therefore, in the present study, we gave a high dose (30 mg/kg) of tolcapone in combination with pargyline and reboxetine to C57BL/6J mice to see whether the earlier findings could be confirmed. The three drugs were also given together. We used intracerebral microdialysis to determine the levels of extracellular dopamine and its metabolites in the mPFC. In addition, we analyzed dopamine, 3,4-dihydroxyphenyl acetic acid (DOPAC) and homovanillic acid (HVA) contents in cortical and striatal synaptosomes to estimate the amount of releasable dopamine and dopamine turnover. In the prefrontal cortex of male C57BL/6J mice, the combination of two drugs (pargyline + tolcapone or reboxetine + tolcapone) generally elevated extracellular dopamine levels more than any single drug. Similar responses, although much weaker, were observed in female mice. Unexpectedly, triple treatment with pargyline, reboxetine and tolcapone did not increase dopamine outflow in the mPFC in either sex, and the treatment actually diminished dopamine outflow in the dorsal striatum. This seems to indicate that such an extensive treatment induces a fast and effective shut-down of dopamine release both in the mPFC and striatum to protect the brain from excess dopaminergic stimulation. The observed decrease in extracellular dopamine levels was not due to the depletion of releasable dopamine because abundant amounts of dopamine were present in synaptosomes. These results imply that the relative proportion of COMT-induced dopamine clearance may be somewhat lower than earlier estimated. PMID:27226189

  11. 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.

  12. Inhibition of uptake of 1-methyl-4-phenylpyridinium ion and dopamine in striatal synaptosomes by tobacco smoke components.

    PubMed

    Carr, L A; Basham, J K; York, B K; Rowell, P P

    1992-05-14

    To determine whether the attenuation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity by tobacco smoke exposure is caused by inhibition of the neuronal uptake of 4-phenylpyridinium ion (MPP+), various tobacco components and a smoke extract were tested for inhibitory activity in striatal synaptosomes. A dimethylsulfoxide extract of tobacco smoke filtrate was found to inhibit the uptake of MPP+ and dopamine. These results suggest that inhibition of the neuronal dopamine uptake mechanism may account for the protective effects of smoke exposure on MPTP-induced neurotoxicity.

  13. Effects of the histamine H₁ receptor antagonist and benztropine analog diphenylpyraline on dopamine uptake, locomotion and reward.

    PubMed

    Oleson, Erik B; Ferris, Mark J; España, Rodrigo A; Harp, Jill; Jones, Sara R

    2012-05-15

    Diphenylpyraline hydrochloride (DPP) is an internationally available antihistamine that produces therapeutic antiallergic effects by binding to histamine H₁ receptors. The complete neuropharmacological and behavioral profile of DPP, however, remains uncharacterized. Here we describe studies that suggest DPP may fit the profile of a potential agonist replacement medication for cocaine addiction. Aside from producing the desired histamine reducing effects, many antihistamines can also elicit psychomotor activation and reward, both of which are associated with increased dopamine concentrations in the nucleus accumbens (NAc). The primary aim of this study was to investigate the potential ability of DPP to inhibit the dopamine transporter, thereby leading to elevated dopamine concentrations in the NAc in a manner similar to cocaine and other psychostimulants. The psychomotor activating and rewarding effects of DPP were also investigated. For comparative purposes cocaine, a known dopamine transporter inhibitor, psychostimulant and drug of abuse, was used as a positive control. As predicted, both cocaine (15 mg/kg) and an equimolar dose of DPP (14 mg/kg) significantly inhibited dopamine uptake in the NAc in vivo and produced locomotor activation, although the time-course of pharmacological effects of the two drugs was different. In comparison to cocaine, DPP showed a prolonged effect on dopamine uptake and locomotion. Furthermore, cocaine, but not DPP, produced significant conditioned place preference, a measure of drug reward. The finding that DPP functions as a potent dopamine uptake inhibitor without producing significant rewarding effects suggests that DPP merits further study as a potential candidate as an agonist pharmacotherapy for cocaine addiction.

  14. Dopamine uptake and cocaine binding mechanisms: the involvement of charged amino acids from the transmembrane domains of the human dopamine transporter.

    PubMed

    Dar, Dalit E; Metzger, Thomas G; Vandenbergh, David J; Uhl, George R

    2006-05-24

    The wild type human dopamine transporter (DAT) and five DAT mutants were transfected into COS-7 cells and their ability to uptake dopamine or to bind cocaine was examine three days later. In each mutant, a single charged amino acid, located in areas that initial hydrophobic analysis had indicated were DAT transmembrane domains was substituted by alanine. Mutants used in this study were lysines 257 and 525 (termed K257A and K525A), arginines 283 and 521 (termed R283A and R521A), and glutamate 491 (termed E491A). Dopamine affinity was significantly enhanced in the K257A and R283A mutants, and the IC(50) for displacement of the radioactive cocaine analog 2 beta-carbomethoxy-3 beta-(4-fluorophenyl)tropane (CFT) by cocaine was significantly elevated in the E491A mutant. All mutants displayed a reduction or complete loss of the maximal velocity (V(m)) of dopamine transport. PMID:16674939

  15. ( sup 3 H)Dopamine uptake by platelet storage granules in schizophrenia

    SciTech Connect

    Rabey, J.M.; Graff, E.; Oberman, Z. ); Lerner, A.; Sigal, M. )

    1992-01-01

    ({sup 3}H)Dopamine (DA) uptake by platelet storage granules was determined in 26 schizophrenic male patients, paranoid type (14 acute stage; 12 in remission) and 20 age-matched, normal controls. maximum velocity (Vmax) of DA uptake was significantly higher in acute patients, than patients in remission or controls (p>0.05). The apparent Michaelis constant (kM) of DA uptake in acute patients was also significantly different from chronic patients a substantial diminution of DA uptake, while haloperidol produced a substantial diminution of DA uptake, while haloperidol (10{sup {minus}4}, 10{sup {minus}5} M) did not affect the assay. Considering that a DA disequilibrium in schizophrenia may be expressed not only in the brain, but also in the periphery and that an increased amount of DA accumulated in the vesicles, implies that an increased quantity of catecholamine is available for release, our findings suggest additional evidence for the role of DA overactivity in the pathophysiology of this disorder.

  16. Single exposure to cocaine impairs aspartate uptake in the pre-frontal cortex via dopamine D1-receptor dependent mechanisms.

    PubMed

    Sathler, Matheus Figueiredo; Stutz, Bernardo; Martins, Robertta Silva; Dos Santos Pereira, Maurício; Pecinalli, Ney Roner; Santos, Luis E; Taveira-da-Silva, Rosilane; Lowe, Jennifer; de Freitas, Isis Grigorio; de Melo Reis, Ricardo Augusto; Manhães, Alex C; Kubrusly, Regina C C

    2016-08-01

    Dopamine and glutamate play critical roles in the reinforcing effects of cocaine. We demonstrated that a single intraperitoneal administration of cocaine induces a significant decrease in [(3)H]-d-aspartate uptake in the pre-frontal cortex (PFC). This decrease is associated with elevated dopamine levels, and requires dopamine D1-receptor signaling (D1R) and adenylyl cyclase activation. The effect was observed within 10min of cocaine administration and lasted for up to 30min. This rapid response is related to D1R-mediated cAMP-mediated activation of PKA and phosphorylation of the excitatory amino acid transporters EAAT1, EAAT2 and EAAT3. We also demonstrated that cocaine exposure increases extracellular d-aspartate, l-glutamate and d-serine in the PFC. Our data suggest that cocaine activates dopamine D1 receptor signaling and PKA pathway to regulate EAATs function and extracellular EAA level in the PFC.

  17. Single exposure to cocaine impairs aspartate uptake in the pre-frontal cortex via dopamine D1-receptor dependent mechanisms.

    PubMed

    Sathler, Matheus Figueiredo; Stutz, Bernardo; Martins, Robertta Silva; Dos Santos Pereira, Maurício; Pecinalli, Ney Roner; Santos, Luis E; Taveira-da-Silva, Rosilane; Lowe, Jennifer; de Freitas, Isis Grigorio; de Melo Reis, Ricardo Augusto; Manhães, Alex C; Kubrusly, Regina C C

    2016-08-01

    Dopamine and glutamate play critical roles in the reinforcing effects of cocaine. We demonstrated that a single intraperitoneal administration of cocaine induces a significant decrease in [(3)H]-d-aspartate uptake in the pre-frontal cortex (PFC). This decrease is associated with elevated dopamine levels, and requires dopamine D1-receptor signaling (D1R) and adenylyl cyclase activation. The effect was observed within 10min of cocaine administration and lasted for up to 30min. This rapid response is related to D1R-mediated cAMP-mediated activation of PKA and phosphorylation of the excitatory amino acid transporters EAAT1, EAAT2 and EAAT3. We also demonstrated that cocaine exposure increases extracellular d-aspartate, l-glutamate and d-serine in the PFC. Our data suggest that cocaine activates dopamine D1 receptor signaling and PKA pathway to regulate EAATs function and extracellular EAA level in the PFC. PMID:27208619

  18. Electrophysiological and amperometric evidence that modafinil blocks the dopamine uptake transporter to induce behavioral activation.

    PubMed

    Federici, M; Latagliata, E C; Rizzo, F R; Ledonne, A; Gu, H H; Romigi, A; Nisticò, R; Puglisi-Allegra, S; Mercuri, N B

    2013-11-12

    Although the wake-promoting drug modafinil has been shown to bind quite exclusively to the dopamine transporter (DAT), its action in the brain has been thought to be partially independent from the facilitation of the dopaminergic signals. Here we used electrophysiological and amperometric techniques to investigate the effects of modafinil on the dopaminergic neurons of the substantia nigra pars compacta (SNpc) and on the synaptic overflow of dopamine in the dorsal striatum from the sliced tissue of wild-type and cocaine-insensitive genetically modified mice (DAT-CI). Moreover, we examined the consequences of modafinil administration on the locomotor behavior of wild-type and DAT-CI mice. In in vitro experiments, modafinil inhibited the spontaneous firing discharge of the dopaminergic neurons. More consistently, it potentiated firing inhibition and the membrane responses caused by exogenously applied dopamine on these cells. Furthermore, it augmented the stimulus-evoked outflow of DA in the striatum. Noteworthy, modafinil caused locomotor activation in wild-type mice. On the other hand, neither the electrophysiological nor the behavioral effects of modafinil were detected in DAT-CI animals. These results demonstrate that modafinil potentiates brain dopaminergic signals via DAT inhibition by acting at the same binding site of cocaine. Therefore, this mechanism of action explains most of the pharmacological properties of this compound in the clinical setting. PMID:23933217

  19. Phenyl Ring-Substituted Lobelane Analogs: Inhibition of [3H]Dopamine Uptake at the Vesicular Monoamine Transporter-2

    PubMed Central

    Nickell, Justin R.; Zheng, Guangrong; Deaciuc, Agripina G.; Crooks, Peter A.

    2011-01-01

    Lobeline attenuates the behavioral effects of methamphetamine via inhibition of the vesicular monoamine transporter (VMAT2). To increase selectivity for VMAT2, chemically defunctionalized lobeline analogs, including lobelane, were designed to eliminate nicotinic acetylcholine receptor affinity. The current study evaluated the ability of lobelane analogs to inhibit [3H]dihydrotetrabenazine (DTBZ) binding to VMAT2 and [3H]dopamine (DA) uptake into isolated synaptic vesicles and determined the mechanism of inhibition. Introduction of aromatic substituents in lobelane maintained analog affinity for the [3H]DTBZ binding site on VMAT2 and inhibitory potency in the [3H]DA uptake assay assessing VMAT2 function. The most potent (Ki = 13–16 nM) analogs in the series included para-methoxyphenyl nor-lobelane (GZ-252B), para-methoxyphenyl lobelane (GZ-252C), and 2,4-dichlorphenyl lobelane (GZ-260C). Affinity of the analogs for the [3H]DTBZ binding site did not correlate with inhibitory potency in the [3H]DA uptake assay. It is noteworthy that the N-benzylindole-, biphenyl-, and indole-bearing meso-analogs 2,6-bis[2-(1-benzyl-1H-indole-3-yl)ethyl]-1-methylpiperidine hemifumarate (AV-1-292C), 2,6-bis(2-(biphenyl-4-yl)ethyl)piperidine hydrochloride (GZ-272B), and 2,6-bis[2-(1H-indole-3-yl)ethyl]-1-methylpiperidine monofumarate (AV-1-294), respectively] inhibited VMAT2 function (Ki = 73, 127, and 2130 nM, respectively), yet had little to no affinity for the [3H]DTBZ binding site. These results suggest that the analogs interact at an alternate site to DTBZ on VMAT2. Kinetic analyses of [3H]DA uptake revealed a competitive mechanism for 2,6-bis(2-(4-methoxyphenyl)ethyl)piperidine hydrochloride (GZ-252B), 2,6-bis(2-(4-methoxyphenyl)ethyl)-1-methylpiperidine hydrochloride (GZ-252C), 2,6-bis(2-(2,4-dichlorophenyl)ethyl)piperidine hydrochloride (GZ-260C), and GZ-272B. Similar to methamphetamine, these analogs released [3H]DA from the vesicles, but with higher potency. In contrast to

  20. Phenyl ring-substituted lobelane analogs: inhibition of [³H]dopamine uptake at the vesicular monoamine transporter-2.

    PubMed

    Nickell, Justin R; Zheng, Guangrong; Deaciuc, Agripina G; Crooks, Peter A; Dwoskin, Linda P

    2011-03-01

    Lobeline attenuates the behavioral effects of methamphetamine via inhibition of the vesicular monoamine transporter (VMAT2). To increase selectivity for VMAT2, chemically defunctionalized lobeline analogs, including lobelane, were designed to eliminate nicotinic acetylcholine receptor affinity. The current study evaluated the ability of lobelane analogs to inhibit [³H]dihydrotetrabenazine (DTBZ) binding to VMAT2 and [³H]dopamine (DA) uptake into isolated synaptic vesicles and determined the mechanism of inhibition. Introduction of aromatic substituents in lobelane maintained analog affinity for the [³H]DTBZ binding site on VMAT2 and inhibitory potency in the [³H]DA uptake assay assessing VMAT2 function. The most potent (K(i) = 13-16 nM) analogs in the series included para-methoxyphenyl nor-lobelane (GZ-252B), para-methoxyphenyl lobelane (GZ-252C), and 2,4-dichlorphenyl lobelane (GZ-260C). Affinity of the analogs for the [³H]DTBZ binding site did not correlate with inhibitory potency in the [³H]DA uptake assay. It is noteworthy that the N-benzylindole-, biphenyl-, and indole-bearing meso-analogs 2,6-bis[2-(1-benzyl-1H-indole-3-yl)ethyl]-1-methylpiperidine hemifumarate (AV-1-292C), 2,6-bis(2-(biphenyl-4-yl)ethyl)piperidine hydrochloride (GZ-272B), and 2,6-bis[2-(1H-indole-3-yl)ethyl]-1-methylpiperidine monofumarate (AV-1-294), respectively] inhibited VMAT2 function (K(i) = 73, 127, and 2130 nM, respectively), yet had little to no affinity for the [³H]DTBZ binding site. These results suggest that the analogs interact at an alternate site to DTBZ on VMAT2. Kinetic analyses of [³H]DA uptake revealed a competitive mechanism for 2,6-bis(2-(4-methoxyphenyl)ethyl)piperidine hydrochloride (GZ-252B), 2,6-bis(2-(4-methoxyphenyl)ethyl)-1-methylpiperidine hydrochloride (GZ-252C), 2,6-bis(2-(2,4-dichlorophenyl)ethyl)piperidine hydrochloride (GZ-260C), and GZ-272B. Similar to methamphetamine, these analogs released [³H]DA from the vesicles, but with higher potency. In

  1. Combinations of Cocaine with Other Dopamine Uptake Inhibitors: Assessment of Additivity

    PubMed Central

    Tanda, Gianluigi; Newman, Amy Hauck; Ebbs, Aaron L.; Tronci, Valeria; Green, Jennifer L.; Tallarida, Ronald J.; Katz, Jonathan L.

    2009-01-01

    Drugs that inhibit dopamine (DA) reuptake through actions at the dopamine transporter (DAT) have been proposed as candidates for development as pharmacotherapies for cocaine abuse. Accordingly, it is important to understand the potential pharmacological interactions of cocaine with other drugs acting at the DAT. Effects of combinations of cocaine with a cocaine analog, 2β-carbomethoxy-3β-(4-fluorophenyl)tropane (WIN 35,428), were compared quantitatively with the combinations of cocaine with the N-butyl,4′,4″-diF benztropine analog, 3-(bis(4-fluorophenyl)methoxy)-8-butyl-8-azabicyclo[3.2.1]octane (JHW 007), to determine whether their effects on DA levels in the shell of the nucleus accumbens (NAC) in mice differed. Each of the drugs alone produced dose-related elevations in NAC DA levels. In contrast to the other drugs, JHW 007 was less effective, producing maximal effects that approached 400% of control versus ∼700% with the other drugs. In addition, the JHW 007 dose-effect curve was not as steep as those for cocaine and WIN 35,428. Combinations of cocaine with its analog, WIN 35,428, were most often greater than those predicted based on dose additivity. In contrast, combinations of cocaine with JHW 007 were most often subadditive. This outcome is consistent with recent studies suggesting that structurally divergent DA uptake inhibitors bind to different domains of the DAT, which can result in different DAT conformations. The conformational changes occurring with JHW 007 binding may result in functional outcomes that alter its abuse liability and its effects in combination with cocaine. PMID:19483071

  2. Substituting a long-acting dopamine uptake inhibitor for cocaine prevents relapse to cocaine seeking.

    PubMed

    Velázquez-Sánchez, Clara; Ferragud, Antonio; Ramos-Miguel, Alfredo; García-Sevilla, Jesús A; Canales, Juan J

    2013-07-01

    The treatment of cocaine addiction remains a challenge. The dopamine replacement approach in cocaine addiction involves the use of a competing dopaminergic agonist that might suppress withdrawal and drug craving in abstinent individuals. Although it has long been postulated that such an approach may be therapeutically successful, preclinical or clinical evidence showing its effectiveness to prevent relapse is scant. We used in rats a procedure that involved substitution of the N-substituted benztropine analog 3α-[bis(4'-fluorophenyl)methoxy]-tropane (AHN-1055), a long-acting dopamine uptake inhibitor (DUI), for cocaine. Maintenance treatment was self-administered. After extinction, reinstatement of drug seeking was induced by cocaine priming. We measured the contents of brain-derived neurotrophic factor (BDNF), c-Fos and Fas-associated death domain (FADD) proteins in the medial prefrontal cortex (mPFC) following reinstatement. DUI, but not amphetamine, substitution led to extinction of active lever presses, as did saline substitution. DUI substitution significantly reduced cocaine-induced reinstatement of drug-seeking behavior, which was strongly elicited after saline substitution. Rats passively yoked to DUI also showed reduced cocaine-primed reinstatement. Reductions in drug seeking during reinstatement were matched by downward shifts in the contents of BDNF, c-Fos and FADD proteins in the mPFC, which were elevated in relapsing rats. These data indicate that DUI substitution not only leads to extinction of self-administration behavior but also prevents reinstatement of drug seeking induced by cocaine re-exposure. Thus, DUI substitution therapy using compounds with low abuse potential, even if received passively in the context previously paired with drug taking, may provide an effective treatment for stimulant addiction.

  3. Measuring the serotonin uptake site using (/sup 3/H)paroxetine--a new serotonin uptake inhibitor

    SciTech Connect

    Gleiter, C.H.; Nutt, D.J.

    1988-01-01

    Serotonin is an important neurotransmitter that may be involved in ethanol preference and dependence. It is possible to label the serotonin uptake site in brain using the tricyclic antidepressant imipramine, but this also binds to other sites. We have used the new high-affinity uptake blocker paroxetine to define binding to this site and report it to have advantages over imipramine as a ligand.

  4. Autoradiographic localization of /sup 3/H-paroxetine-labeled serotonin uptake sites in rat brain

    SciTech Connect

    De Souza, E.B.; Kuyatt, B.L.

    1987-01-01

    Paroxetine is a potent and selective inhibitor of serotonin uptake into neurons. Serotonin uptake sites have been identified, localized, and quantified in rat brain by autoradiography with 3H-paroxetine; 3H-paroxetine binding in slide-mounted sections of rat forebrain was of high affinity (KD = 10 pM) and the inhibition affinity constant (Ki) values of various drugs in competing 3H-paroxetine binding significantly correlated with their reported potencies in inhibiting synaptosomal serotonin uptake. Serotonin uptake sites labeled by 3H-paroxetine were highly concentrated in the dorsal and median raphe nuclei, central gray, superficial layer of the superior colliculus, lateral septal nucleus, paraventricular nucleus of the thalamus, and the islands of Calleja. High concentrations of 3H-paroxetine binding sites were found in brainstem areas containing dopamine (substantia nigra and ventral tegmental area) and norepinephrine (locus coeruleus) cell bodies. Moderate concentrations of 3H-paroxetine binding sites were present in laminae I and IV of the frontal parietal cortex, primary olfactory cortex, olfactory tubercle, regions of the basal ganglia, septum, amygdala, thalamus, hypothalamus, hippocampus, and some brainstem areas including the interpeduncular, trigeminal, and parabrachial nuclei. Lower densities of 3H-paroxetine binding sites were found in other regions of the neocortex and very low to nonsignificant levels of binding were present in white matter tracts and in the cerebellum. Lesioning of serotonin neurons with 3,4-methylenedioxyamphetamine caused large decreases in 3H-paroxetine binding. The autoradiographic distribution of 3H-paroxetine binding sites in rat brain corresponds extremely well to the distribution of serotonin terminals and cell bodies as well as with the pharmacological sites of action of serotonin.

  5. In vitro binding assays using (3)H nisoxetine and (3)H WIN 35,428 reveal selective effects of gonadectomy and hormone replacement in adult male rats on norepinephrine but not dopamine transporter sites in the cerebral cortex.

    PubMed

    Meyers, B; Kritzer, M F

    2009-03-01

    The prefrontal cortices mediate cognitive functions that critically depend on local dopamine levels. In male rats, many prefrontal tasks where performance is disrupted by changes in dopamine signaling are also impaired by gonadectomy, a manipulation that increases cortical dopamine concentration, prefrontal dopamine axon density and possibly extracellular prefrontal dopamine levels as well. Because these actions could be responsible for the impairing effects of gonadectomy on prefrontal function, the question of how they might arise comes to the fore. Accordingly, the present studies asked whether dopamine levels might be increased via a hormone sensitivity of transporter-mediated dopamine uptake. Specifically, (3)H WIN 35,428 and (3)H nisoxetine, ligands selective for the dopamine (DAT)- and norepinephrine transporter (NET) respectively, were used in in vitro binding assays to ask whether gonadectomy altered transporter affinity (Kd) and/or binding site number (Bmax) in prefrontal cortex, sensorimotor cortex and/or caudate. Assays performed on tissues dissected from sham-operated, gonadectomized and gonadectomized rats supplemented with testosterone propionate or estradiol for 4 or 28 days revealed no significant group differences or obvious trends in Kd or Bmax for DAT binding or in measures of Bmax for NET binding. However, affinity constants for (3)H nisoxetine were found to be significantly higher in sensorimotor and/or prefrontal cortex of rats gonadectomized and gonadectomized and supplemented with estradiol for 4 or 28 days but similar to control in gonadectomized rats given testosterone. Because the NET contributes substantially to extracellular prefrontal dopamine clearance, these androgen-mediated effects could influence prefrontal dopamine levels and might thus be relevant for observed effects of gonadectomy on dopamine-dependent prefrontal behaviors. A hormone sensitivity of the NET could also have bearing on the prefrontal dopamine dysfunction seen in

  6. Synthetic analgesics and other phenylpiperidines: effects on uptake and storage of dopamine and other monoamines mouse forebrain tissue.

    PubMed

    Baldessarini, R J; Kula, N S; Francoeur, D; Finklestein, S P; Murphy, F; Neumeyer, J L

    1986-11-10

    The neurotoxin N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) can induce degeneration of dopamine (DA) and other central monoamine neurons, leading to Parkinson's disease-like effects in man, monkey, and mouse. MPTP and other substituted phenylpiperidines related to synthetic analgesics including alphaprodine and meperidine were evaluated for potency vs. uptake of 0.1 microM tritiated DA, norepinephrine (NE), or serotonin (5HT) in synaptosomal preparations of mouse striatum or cerebral cortex. The most potent inhibitor of the uptake of 3H-DA was N-methyl-4-phenylpyridinium ion (MPP+; IC50 = 1 microM, Ki = 0.4 microM), a metabolite of MPTP; its effect was competitive and reversible. Other analogs of MPTP: the N-ethylindole AHR-1709, N,N-dimethyl-MPTP, and N-methyl-4-phenylpiperidine were all more potent than MPTP against 3H-DA uptake. N-dealkylation and N-propyl substitution, as well as pyridine ring substitution, decreased affinity for DA uptake while 3',4'-dihydroxyphenyl substitution increased potency and selectivity for catecholamine uptake, and quarternarization of the pyridine ring also increased potency against DA uptake. Active compounds showed higher potency against the uptake of NE than of DA. MPP+ was also more potent than MPTP in releasing endogenous DA from striatal synaptosomes (EC50 = 3 vs. 30 microM), but did not release the cytoplasmic markers tyrosine hydroxylase and lactate dehydrogenase (LDH). In contrast to MPTP, synthetic phenylpiperidine analgesics, their potential metabolites and the experimental neuroleptic agent AHR-1709 all failed to deplete striatal DA in vivo, even if active in vitro against DA uptake.

  7. Quinolyl analogues of norlobelane: novel potent inhibitors of [(3)H]dihydrotetrabenazine binding and [(3)H]dopamine uptake at the vesicular monoamine transporter-2.

    PubMed

    Ding, Derong; Nickell, Justin R; Dwoskin, Linda P; Crooks, Peter A

    2015-07-01

    We have previously shown that quinolyl moieties are attractive structural replacements for the phenyl groups in lobelane. These quinolyl analogues had improved water-solubility over lobelane and retained the potent vesicular monoamine transporter-2 (VMAT-2) inhibitory properties of the parent compound, with quinlobelane (4) exhibiting potent inhibition of uptake at VMAT-2 (Ki=51nM). However, the VMAT-2 inhibitory properties of quinolyl analogues of norlobelane, which is equipotent with lobeline as an inhibitor of [(3)H]dopamine (DA) uptake at VMAT-2, have not been reported. In the current communication, we describe the synthesis of some novel des-methyl quinolyl analogues of lobelane that exhibit greater affinity (Ki=178-647nM) for the dihydrotetrabenazine binding site located on VMAT-2 compared with lobelane (Ki=970nM), norlobelane (Ki=2310nM) and quinlobelane (Ki=2640nM). The most potent compounds, 14 and 15, also exhibited inhibition of [(3)H]DA uptake at VMAT-2 (Ki=42nM) which was comparable to both lobelane (Ki=45nM) and norlobelane (Ki=43nM). Results reveal that binding affinity at VMAT-2 serves as an accurate predictor of inhibition of the function of VMAT-2 for the majority of these analogues. These novel analogues are under consideration for further development as treatments for methamphetamine abuse.

  8. Structural probing of a microdomain in the dopamine transporter by engineering of artificial Zn2+ binding sites.

    PubMed

    Norregaard, L; Visiers, I; Loland, C J; Ballesteros, J; Weinstein, H; Gether, U

    2000-12-26

    Previously, we have identified three Zn(2+) binding residues in an endogenous Zn(2+) binding site in the human dopamine transporter (hDAT): (193)His in extracellular loop 2 (ECL 2), (375)His at the external end of transmembrane segment (TM) 7, and (396)Glu at the external end of TM 8. Here we have generated a series of artificial Zn(2+) binding sites in a domain situated around the external ends of TMs 7 and 8 by taking advantage of the well-defined structural constraints for binding of the zinc(II) ion. Initially, we found that the Zn(2+)-coordinating (193)His in ECL 2 could be substituted with a histidine inserted at the i - 4 position relative to (375)His in TM 7. In this mutant (H193K/M371H), Zn(2+) potently inhibited [(3)H]dopamine uptake with an IC(50) value of 7 microM as compared to a value of 300 microM for the control (H193K). These data are consistent with the presence of an alpha-helical configuration of TM 7. This inference was further corroborated by the observation that no increase in the apparent Zn(2+) affinity was observed following introduction of histidines at the i - 2, i - 3, and i - 5 positions. In contrast, introduction of histidines at positions i + 2, i + 3, and i + 4 all resulted in potent inhibition of [(3)H]dopamine uptake by Zn(2+) (IC(50) = 3-32 microM). These observations are inconsistent with continuation of the helix beyond position 375 and indicate an approximate boundary between the end of the helix and the succeeding loop. In summary, the data presented here provide new insight into the structure of a functionally important domain in the hDAT and illustrate how engineering of Zn(2+) binding sites can be a useful approach for probing both secondary and tertiary structure relationships in membrane proteins of unknown structure. PMID:11123909

  9. Distinct Effects of Nalmefene on Dopamine Uptake Rates and Kappa Opioid Receptor Activity in the Nucleus Accumbens Following Chronic Intermittent Ethanol Exposure.

    PubMed

    Rose, Jamie H; Karkhanis, Anushree N; Steiniger-Brach, Björn; Jones, Sara R

    2016-01-01

    The development of pharmacotherapeutics that reduce relapse to alcohol drinking in patients with alcohol dependence is of considerable research interest. Preclinical data support a role for nucleus accumbens (NAc) κ opioid receptors (KOR) in chronic intermittent ethanol (CIE) exposure-induced increases in ethanol intake. Nalmefene, a high-affinity KOR partial agonist, reduces drinking in at-risk patients and relapse drinking in rodents, potentially due to its effects on NAc KORs. However, the effects of nalmefene on accumbal dopamine transmission and KOR function are poorly understood. We investigated the effects of nalmefene on dopamine transmission and KORs using fast scan cyclic voltammetry in NAc brain slices from male C57BL/6J mice following five weeks of CIE or air exposure. Nalmefene concentration-dependently reduced dopamine release similarly in air and CIE groups, suggesting that dynorphin tone may not be present in brain slices. Further, nalmefene attenuated dopamine uptake rates to a greater extent in brain slices from CIE-exposed mice, suggesting that dopamine transporter-KOR interactions may be fundamentally altered following CIE. Additionally, nalmefene reversed the dopamine-decreasing effects of a maximal concentration of a KOR agonist selectively in brain slices of CIE-exposed mice. It is possible that nalmefene may attenuate withdrawal-induced increases in ethanol consumption by modulation of dopamine transmission through KORs. PMID:27472317

  10. Distinct Effects of Nalmefene on Dopamine Uptake Rates and Kappa Opioid Receptor Activity in the Nucleus Accumbens Following Chronic Intermittent Ethanol Exposure.

    PubMed

    Rose, Jamie H; Karkhanis, Anushree N; Steiniger-Brach, Björn; Jones, Sara R

    2016-07-27

    The development of pharmacotherapeutics that reduce relapse to alcohol drinking in patients with alcohol dependence is of considerable research interest. Preclinical data support a role for nucleus accumbens (NAc) κ opioid receptors (KOR) in chronic intermittent ethanol (CIE) exposure-induced increases in ethanol intake. Nalmefene, a high-affinity KOR partial agonist, reduces drinking in at-risk patients and relapse drinking in rodents, potentially due to its effects on NAc KORs. However, the effects of nalmefene on accumbal dopamine transmission and KOR function are poorly understood. We investigated the effects of nalmefene on dopamine transmission and KORs using fast scan cyclic voltammetry in NAc brain slices from male C57BL/6J mice following five weeks of CIE or air exposure. Nalmefene concentration-dependently reduced dopamine release similarly in air and CIE groups, suggesting that dynorphin tone may not be present in brain slices. Further, nalmefene attenuated dopamine uptake rates to a greater extent in brain slices from CIE-exposed mice, suggesting that dopamine transporter-KOR interactions may be fundamentally altered following CIE. Additionally, nalmefene reversed the dopamine-decreasing effects of a maximal concentration of a KOR agonist selectively in brain slices of CIE-exposed mice. It is possible that nalmefene may attenuate withdrawal-induced increases in ethanol consumption by modulation of dopamine transmission through KORs.

  11. Distinct Effects of Nalmefene on Dopamine Uptake Rates and Kappa Opioid Receptor Activity in the Nucleus Accumbens Following Chronic Intermittent Ethanol Exposure

    PubMed Central

    Rose, Jamie H.; Karkhanis, Anushree N.; Steiniger-Brach, Björn; Jones, Sara R.

    2016-01-01

    The development of pharmacotherapeutics that reduce relapse to alcohol drinking in patients with alcohol dependence is of considerable research interest. Preclinical data support a role for nucleus accumbens (NAc) κ opioid receptors (KOR) in chronic intermittent ethanol (CIE) exposure-induced increases in ethanol intake. Nalmefene, a high-affinity KOR partial agonist, reduces drinking in at-risk patients and relapse drinking in rodents, potentially due to its effects on NAc KORs. However, the effects of nalmefene on accumbal dopamine transmission and KOR function are poorly understood. We investigated the effects of nalmefene on dopamine transmission and KORs using fast scan cyclic voltammetry in NAc brain slices from male C57BL/6J mice following five weeks of CIE or air exposure. Nalmefene concentration-dependently reduced dopamine release similarly in air and CIE groups, suggesting that dynorphin tone may not be present in brain slices. Further, nalmefene attenuated dopamine uptake rates to a greater extent in brain slices from CIE-exposed mice, suggesting that dopamine transporter-KOR interactions may be fundamentally altered following CIE. Additionally, nalmefene reversed the dopamine-decreasing effects of a maximal concentration of a KOR agonist selectively in brain slices of CIE-exposed mice. It is possible that nalmefene may attenuate withdrawal-induced increases in ethanol consumption by modulation of dopamine transmission through KORs. PMID:27472317

  12. Inhibition of ( sup 3 H)dopamine uptake into rat striatal slices by quaternary N-methylated nicotine metabolites

    SciTech Connect

    Dwoskin, L.P.; Leibee, L.L.; Jewell, A.L.; Fang, Zhaoxia; Crooks, P.A. )

    1992-01-01

    The effects of quaternary N-methylated nicotine derivatives were examined on in vitro uptake of ({sup 3}H)dopamine (({sup 3}H)DA) in rat striatal slices. Striatal slices were incubated with a 10 {mu}M concentration of the following compounds: N-methylnicotinium, N-methylnornicotinium, N-methylcotininium, N,N{prime}-dimethylnicotinium and N{prime}-methylnicotinium salts. The results clearly indicated that significant inhibition of ({sup 3}H)DA uptake occurred with those compounds possessing a N-methylpyridinium group; whereas, compounds that were methylated at the N{prime}-pyrrolidinium position were less effective or exhibited no inhibition of ({sup 3}H)DA uptake. The results suggest that high concentrations of quaternary N-methylated nicotine metabolites which are structurally related to the neurotoxin MPP{sup +}, and which may be formed in the CNS, may protect against Parkinson's Disease and explain the inverse relationship between smoking and Parkinsonism reported in epidemiologic studies.

  13. Azepines and piperidines with dual norepinephrine dopamine uptake inhibition and antidepressant activity.

    PubMed

    Brown, Dean G; Bernstein, Peter R; Wu, Ye; Urbanek, Rebecca A; Becker, Christopher W; Throner, Scott R; Dembofsky, Bruce T; Steelman, Gary B; Lazor, Lois A; Scott, Clay W; Wood, Michael W; Wesolowski, Steven S; Nugiel, David A; Koch, Stephanie; Yu, Jian; Pivonka, Donald E; Li, Shuang; Thompson, Carol; Zacco, Anna; Elmore, Charles S; Schroeder, Patricia; Liu, JianWei; Hurley, Christopher A; Ward, Stuart; Hunt, Hazel J; Williams, Karen; McLaughlin, Joseph; Hoesch, Valerie; Sydserff, Simon; Maier, Donna; Aharony, David

    2013-01-10

    Herein, we describe the discovery of inhibitors of norepinephrine (NET) and dopamine (DAT) transporters with reduced activity relative to serotonin transporters (SERT). Two compounds, 8b and 21a, along with nomifensine were tested in a rodent receptor occupancy study and demonstrated dose-dependent displacement of radiolabeled NET and DAT ligands. These compounds were efficacious in a rat forced swim assay (model of depression) and also had activity in rat spontaneous locomotion assay. PMID:24900562

  14. The high affinity dopamine uptake inhibitor, JHW 007, blocks cocaine-induced reward, locomotor stimulation and sensitization.

    PubMed

    Velázquez-Sánchez, C; Ferragud, A; Murga, J; Cardá, M; Canales, J J

    2010-07-01

    The discovery and evaluation of high affinity dopamine transport inhibitors with low abuse liability is an important step toward the development of efficacious medications for cocaine addiction. We examined in mice the behavioural effects of (N-(n-butyl)-3alpha-[bis(4'-fluorophenyl)methoxy]-tropane) (JHW 007), a benztropine (BZT) analogue that blocks dopamine uptake, and assessed its potential to influence the actions of cocaine in clinically-relevant models of cocaine addiction. In the conditioned place preference (CPP) paradigm, JHW 007 exposure did not produce place conditioning within an ample dose range but effectively blocked the CPP induced by cocaine administration. Similarly, in the CPP apparatus JHW 007 treatment failed to stimulate locomotor activity at any dose but dose-dependently suppressed the hyperactivity evoked by cocaine treatment. In locomotor sensitization assays performed in the open field, JHW 007 did not produce sensitized locomotor behaviour when given alone, but it prevented the sensitized component of the locomotor response elicited by subchronic (8-day) cocaine exposure. In the elevated plus maze (EPM), acute treatment with JHW 007, cocaine and combinations of the BZT analogue and cocaine produced an anxiogenic-like profile. Re-test in the EPM following subchronic (8-day) exposure enhanced the anxiogenic-like effect of the same drug treatments. The present findings indicate that JHW 007 exposure counteracts some critical behavioural correlates of cocaine treatment, including conditioned reward, locomotor stimulation and sensitization, and lend support to the further development of BZT analogues as potential replacement medications in cocaine addiction.

  15. Effects of volatile and intravenous anesthetics on the uptake of GABA, glutamate and dopamine by their transporters heterologously expressed in COS cells and in rat brain synaptosomes.

    PubMed

    Sugimura, M; Kitayama, S; Morita, K; Irifune, M; Takarada, T; Kawahara, M; Dohi, T

    2001-08-01

    Although the neurotransmitter uptake system is considered a possible target for the presynaptic action of anesthetic agents, observations are inconsistent concerning effects on the transporter and their clinical relevance. The present study examined the effects of volatile and intravenous anesthetics on the uptake of GABA, glutamate and dopamine in COS cells heterologously expressing the transporters for these neurotransmitters and in the rat brain synaptosomes. Halothane and isoflurane, but not thiamylal or thiopental, significantly inhibited uptake by COS cell systems of GABA, dopamine and glutamic acid in a concentration-dependent manner within clinically relevant ranges for anesthesia induced by these agents. Similarly, in synaptosomes halothane and isoflurane but not thiopental significantly suppressed the uptake of GABA and glutamic acid, respectively. These results do not support the hypothesis that volatile and intravenous anesthetics exert their action via specific inhibition of GABA uptake to enhance inhibitory GABAergic neuronal activity. Rather, they suggest that presynaptic uptake systems for various neurotransmitters including GABA may be the molecular targets for volatile anesthetic agents.

  16. Therapeutic-like properties of a dopamine uptake inhibitor in animal models of amphetamine addiction.

    PubMed

    Velazquez-Sanchez, Clara; Ferragud, Antonio; Renau-Piqueras, Jaime; Canales, Juan J

    2011-06-01

    N-substituted benztropine (BZT) analogs are molecules that display high affinity for the dopamine transporter (DAT), therapeutic-like effects in animal models of cocaine abuse, and psychopharmacological characteristics consistent with those of a substitute medication for cocaine addiction. Since amphetamine (Amph) and cocaine share mechanisms of action at the DAT, we evaluated the effectiveness of a BZT analog in animal models of Amph addiction. We tested in mice and rats the effects of the BZT derivative, 3α-[bis(4-fluorophenyl)methoxy]-tropane (AHN-1055), on Amph-induced conditioned place preference (CPP), locomotor activity, sensitization, self-administration and ΔFosB accumulation in the nucleus accumbens (NAc). The results showed that AHN-1055 did not produce rewarding, stimulant, or sensitized locomotor effects in mice when administered alone but it readily blocked the rewarding, stimulant, and sensitizing effects of repeated Amph exposure. Furthermore, in mice undergoing conditioning in the CPP paradigm, the BZT analog prevented the accumulation of ΔFosB protein induced in the NAc shell region by Amph treatment. Notably, treatment with AHN-1055 dose-dependently reduced Amph self-administration in rats with a steady history of voluntary Amph intake. These results provide a straightforward demonstration that a BZT derivative with binding affinity for DAT exhibits high efficacy in animal models of Amph abuse, suggesting that the novel generation of BZT analogs could have wider therapeutic applications in stimulant-spectrum disorders than those previously recognized.

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

    PubMed Central

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

    2013-01-01

    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 [3H]dopamine (DA) uptake into isolated synaptic vesicles (Ki≤66 nM). The cis-4-methoxy analog 22b was the most potent inhibitor (Ki=24 nM), and was 2-fold more potent that either lobelane (2a, Ki=45 nM) or norlobelane (2b, Ki=43 nM). The trans-methylenedioxy analog, 15c (Ki=31 nM), 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. PMID:23993667

  18. 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.

  19. 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.

  20. Computational and biochemical docking of the irreversible cocaine analog RTI 82 directly demonstrates ligand positioning in the dopamine transporter central substrate-binding site.

    PubMed

    Dahal, Rejwi Acharya; Pramod, Akula Bala; Sharma, Babita; Krout, Danielle; Foster, James D; Cha, Joo Hwan; Cao, Jianjing; Newman, Amy Hauck; Lever, John R; Vaughan, Roxanne A; Henry, L Keith

    2014-10-24

    The dopamine transporter (DAT) functions as a key regulator of dopaminergic neurotransmission via re-uptake of synaptic dopamine (DA). Cocaine binding to DAT blocks this activity and elevates extracellular DA, leading to psychomotor stimulation and addiction, but the mechanisms by which cocaine interacts with DAT and inhibits transport remain incompletely understood. Here, we addressed these questions using computational and biochemical methodologies to localize the binding and adduction sites of the photoactivatable irreversible cocaine analog 3β-(p-chlorophenyl)tropane-2β-carboxylic acid, 4'-azido-3'-iodophenylethyl ester ([(125)I]RTI 82). Comparative modeling and small molecule docking indicated that the tropane pharmacophore of RTI 82 was positioned in the central DA active site with an orientation that juxtaposed the aryliodoazide group for cross-linking to rat DAT Phe-319. This prediction was verified by focused methionine substitution of residues flanking this site followed by cyanogen bromide mapping of the [(125)I]RTI 82-labeled mutants and by the substituted cysteine accessibility method protection analyses. These findings provide positive functional evidence linking tropane pharmacophore interaction with the core substrate-binding site and support a competitive mechanism for transport inhibition. This synergistic application of computational and biochemical methodologies overcomes many uncertainties inherent in other approaches and furnishes a schematic framework for elucidating the ligand-protein interactions of other classes of DA transport inhibitors. PMID:25179220

  1. Computational and Biochemical Docking of the Irreversible Cocaine Analog RTI 82 Directly Demonstrates Ligand Positioning in the Dopamine Transporter Central Substrate-binding Site*

    PubMed Central

    Dahal, Rejwi Acharya; Pramod, Akula Bala; Sharma, Babita; Krout, Danielle; Foster, James D.; Cha, Joo Hwan; Cao, Jianjing; Newman, Amy Hauck; Lever, John R.; Vaughan, Roxanne A.; Henry, L. Keith

    2014-01-01

    The dopamine transporter (DAT) functions as a key regulator of dopaminergic neurotransmission via re-uptake of synaptic dopamine (DA). Cocaine binding to DAT blocks this activity and elevates extracellular DA, leading to psychomotor stimulation and addiction, but the mechanisms by which cocaine interacts with DAT and inhibits transport remain incompletely understood. Here, we addressed these questions using computational and biochemical methodologies to localize the binding and adduction sites of the photoactivatable irreversible cocaine analog 3β-(p-chlorophenyl)tropane-2β-carboxylic acid, 4′-azido-3′-iodophenylethyl ester ([125I]RTI 82). Comparative modeling and small molecule docking indicated that the tropane pharmacophore of RTI 82 was positioned in the central DA active site with an orientation that juxtaposed the aryliodoazide group for cross-linking to rat DAT Phe-319. This prediction was verified by focused methionine substitution of residues flanking this site followed by cyanogen bromide mapping of the [125I]RTI 82-labeled mutants and by the substituted cysteine accessibility method protection analyses. These findings provide positive functional evidence linking tropane pharmacophore interaction with the core substrate-binding site and support a competitive mechanism for transport inhibition. This synergistic application of computational and biochemical methodologies overcomes many uncertainties inherent in other approaches and furnishes a schematic framework for elucidating the ligand-protein interactions of other classes of DA transport inhibitors. PMID:25179220

  2. Dopamine Release in the Nonhuman Primate Caudate and Putamen Depends upon Site of Stimulation in the Subthalamic Nucleus

    PubMed Central

    Min, Hoon-Ki; Ross, Erika K.; Jo, Hang Joon; Cho, Shinho; Settell, Megan L.; Jeong, Ju Ho; Duffy, Penelope S.; Chang, Su-Youne; Bennet, Kevin E.; Blaha, Charles D.

    2016-01-01

    Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for medically refractory Parkinson's disease. Although DBS has recognized clinical utility, its biologic mechanisms are not fully understood, and whether dopamine release is a potential factor in those mechanisms is in dispute. We tested the hypothesis that STN DBS-evoked dopamine release depends on the precise location of the stimulation site in the STN and the site of recording in the caudate and putamen. We conducted DBS with miniature, scaled-to-animal size, multicontact electrodes and used functional magnetic resonance imaging to identify the best dopamine recording site in the brains of nonhuman primates (rhesus macaques), which are highly representative of human brain anatomy and circuitry. Real-time stimulation-evoked dopamine release was monitored using in vivo fast-scan cyclic voltammetry. This study demonstrates that STN DBS-evoked dopamine release can be reduced or increased by redirecting STN stimulation to a slightly different site. SIGNIFICANCE STATEMENT Electrical stimulation of deep structures of the brain, or deep brain stimulation (DBS), is used to modulate pathological brain activity. However, technological limitations and incomplete understanding of the therapeutic mechanisms of DBS prevent personalization of this therapy and may contribute to less-than-optimal outcomes. We have demonstrated that DBS coincides with changes in dopamine neurotransmitter release in the basal ganglia. Here we mapped relationships between DBS and changes in neurochemical activity. Importantly, this study shows that DBS-evoked dopamine release can be reduced or increased by refocusing the DBS on a slightly different stimulation site. PMID:27251623

  3. Mutational Analysis of the High-Affinity Zinc Binding Site Validates a Refined Human Dopamine Transporter Homology Model

    PubMed Central

    Stockner, Thomas; Montgomery, Therese R.; Kudlacek, Oliver; Weissensteiner, Rene; Ecker, Gerhard F.; Freissmuth, Michael; Sitte, Harald H.

    2013-01-01

    The high-resolution crystal structure of the leucine transporter (LeuT) is frequently used as a template for homology models of the dopamine transporter (DAT). Although similar in structure, DAT differs considerably from LeuT in a number of ways: (i) when compared to LeuT, DAT has very long intracellular amino and carboxyl termini; (ii) LeuT and DAT share a rather low overall sequence identity (22%) and (iii) the extracellular loop 2 (EL2) of DAT is substantially longer than that of LeuT. Extracellular zinc binds to DAT and restricts the transporter‚s movement through the conformational cycle, thereby resulting in a decrease in substrate uptake. Residue H293 in EL2 praticipates in zinc binding and must be modelled correctly to allow for a full understanding of its effects. We exploited the high-affinity zinc binding site endogenously present in DAT to create a model of the complete transmemberane domain of DAT. The zinc binding site provided a DAT-specific molecular ruler for calibration of the model. Our DAT model places EL2 at the transporter lipid interface in the vicinity of the zinc binding site. Based on the model, D206 was predicted to represent a fourth co-ordinating residue, in addition to the three previously described zinc binding residues H193, H375 and E396. This prediction was confirmed by mutagenesis: substitution of D206 by lysine and cysteine affected the inhibitory potency of zinc and the maximum inhibition exerted by zinc, respectively. Conversely, the structural changes observed in the model allowed for rationalizing the zinc-dependent regulation of DAT: upon binding, zinc stabilizes the outward-facing state, because its first coordination shell can only be completed in this conformation. Thus, the model provides a validated solution to the long extracellular loop and may be useful to address other aspects of the transport cycle. PMID:23436987

  4. Short- and Long-Term Effects of Interleukin-2 Treatment on the Sensitivity of Periadolescent Female Mice to Interleukin-2 and Dopamine Uptake Inhibitor

    PubMed Central

    Rankin, James S.; Zalcman, Steven S.; Zhu, Youhua; Siegel, Allan

    2013-01-01

    Interleukin (IL)-2, a T-helper 1 (Th1) cell-derived cytokine, which potently modulates dopamine activity and neuronal excitability in mesolimbic structures, is linked with pathological outcomes (e.g., schizophrenia, depression, etc.) that at least partly reflect alterations in central dopaminergic processes. It has been suggested that dopamine neurons undergo pruning during adolescence and abnormalities in pruning predispose individuals to behavioral disorders. Since IL-2 is known as a neurodevelopmental factor affecting associated behavioral processes, the present study tested whether IL-2 can modulate stereotypic behaviors in both the periadolescent and adult periods. This study determined whether IL-2 treatment would produce long-lasting changes in sensitivity to a later challenge with IL-2 or GBR 12909, a highly selective dopamine uptake inhibitor. Four experiments were conducted. Firstly, a decrease in novelty-induced stereotypic behavior was observed in BALB/c periadolescent mice (38 days of age) following IL-2 administration (0.4 µg/2 ml) relative to vehicle control. In the second experiment, an initial dose of IL-2 was given in the periadolescent period, but did not affect rearing responses. A second dose of IL-2 given to the animals 30 days later as adults, resulted in a significant increase in rearing behaviors relative to control animals. In the third experiment, separate groups of experimental and control mice were administered GBR 12909, a highly selective dopamine reuptake inhibitor, 30 days following treatment with either IL-2 or vehicle. It was noted that this experimental group, which initially received IL-2, exhibited stereotypy, as evidenced by increased sniffing behavior. A fourth experiment revealed that IL-2 administered in periadolesecence and adulthood had no effect on other motor responses, indicating that IL-2 selectively modulates selective stereotypic behaviors. The results provide evidence, for the first time, that long-term changes in

  5. Lobelane analogues containing 4-hydroxy and 4-(2-fluoroethoxy) aromatic substituents: Potent and selective inhibitors of [(3)H]dopamine uptake at the vesicular monoamine transporter-2.

    PubMed

    Joolakanti, Shyamsunder R; Nickell, Justin R; Janganati, Venumadhav; Zheng, Guangrong; Dwoskin, Linda P; Crooks, Peter A

    2016-05-15

    A series of lobelane and GZ-793A analogues that incorporate aromatic 4-hydroxy and 4-(2-fluoroethoxy) substituents were synthesized and evaluated for inhibition of [(3)H]dopamine (DA) uptake at the vesicular monoamine transporter-2 (VMAT2) and the dopamine transporter (DAT), and [(3)H]serotonin uptake at the serotonin transporter (SERT). Most of these compounds exhibited potent inhibition of DA uptake at VMAT2 in the nanomolar range (Ki=30-70nM). The two most potent analogues, 7 and 14, both exhibited a Ki value of 31nM for inhibition of VMAT2. The lobelane analogue 14, incorporating 4-(2-fluoroethoxy) and 4-hydroxy aromatic substituents, exhibited 96- and 335-fold greater selectivity for VMAT2 versus DAT and SERT, respectively, in comparison to lobelane. Thus, lobelane analogues bearing hydroxyl and fluoroethoxy moieties retain the high affinity for VMAT2 of the parent compound, while enhancing selectivity for VMAT2 versus the plasmalemma transporters.

  6. Interactions of dopaminergic agonists and antagonists with dopaminergic D3 binding sites in rat striatum. Evidence that (/sup 3/H)dopamine can label a high affinity agonist-binding state of the D1 dopamine receptor

    SciTech Connect

    Leff, S.E.; Creese, I.

    1985-02-01

    The interactions of dopaminergic agonists and antagonists with /sup 3/H-agonist labeled D3 dopaminergic binding sites of rat striatum have been characterized by radioligand-binding techniques. When the binding of (/sup 3/H)dopamine and (/sup 3/H)apomorphine to D2 dopamine receptors is blocked by the inclusion of D2 selective concentrations of unlabeled spiroperidol or domperidone, these ligands appear to label selectively the previously termed D3 binding site. Antagonist/(/sup 3/H)dopamine competition curves are of uniformly steep slope (nH . 1.0), suggesting the presence of a single D3 binding site. The relative potencies of antagonists to inhibit D3 specific (/sup 3/H)dopamine binding are significantly correlated with their potencies to block D1 dopamine receptors as measured by the inhibition of both dopamine-stimulated adenylate cyclase and (/sup 3/H)flupentixol-binding activities. The affinities of agonists to inhibit D3 specific (/sup 3/H)dopamine binding are also correlated with estimates of these agonists affinities for the high affinity binding component of agonist/(/sup 3/H)flupentixol competition curves. Both D3 specific (/sup 3/H) dopamine binding and the high affinity agonist-binding component of dopamine/(/sup 3/H)flupentixol competition curves show a similar sensitivity to guanine nucleotides. Taken together, these data strongly suggest that the D3 binding site is related to a high affinity agonist-binding state of the D1 dopamine receptor.

  7. Radiolabeled2{beta}-carbo-2{prime}(S)-fluoroisopropoxy-3{beta}-(4-iodophenyl)-tropane (FIPIT): Synthesis, characterization and primate imaging of a radioligand for mapping dopamine transporter sites by both PET and SPECT

    SciTech Connect

    Keil, R.; Shi, B.; Hoffman, J.M.

    1996-05-01

    Highly potent and selective dopamine transporter ligands containing both iodine and fluorine are versatile probes for in vivo mapping of dopamine transporter sites in the striatum by PET and SPECT when labeled with fluorine-18 and iodine-123, respectively. Dual labeled biochemical probes are attractive agents since only one set of toxicity and pharmacokinetic analysis may be required for ligand validation for both imaging modalities. Recently, we reported that replacement of the methyl ester of 2{beta}-carbomethoxy-3{beta}-(4-chlorophenyl)tropane with a 2{prime}(R,S)-[F-18]fluoroisopropyl ester affords a highly potent and selective dopamine transporter ligand, 2{beta}-carbo-2{prime}(R,S)- fluoroisopropoxy-3{beta}-(4-chlorophenyl)tropane (FIPCT). FIPCT showed high uptake and retention in the striatum (S) resulting in good S/cerebellum = 3.5 at 125 min post injection in a rhesus monkey. These findings prompted us to synthesize and evaluate the 4-iodo analog, 2{beta}-carbo-2{prime}-(S)-fluoroisopropoxy-3{beta}-(4-iodophenyl)tropane (1) with 1-fluoropropan-2-ol (2) and POC13. These results suggest that [F-18]S-FIPIT is an excellent candidate for mapping of dopamine transporter sites.

  8. Insights from molecular dynamics: the binding site of cocaine in the dopamine transporter and permeation pathways of substrates in the leucine and dopamine transporters

    PubMed Central

    Merchant, Bonnie A.; Madura, Jeffry D.

    2012-01-01

    The dopamine transporter (DAT) facilitates the regulation of synaptic neurotransmitter levels. As a target for therapeutic and illicit psycho-stimulant drugs like antidepressants and cocaine, DAT has been studied intensively. Despite a wealth of mutational and physiological data regarding DAT, the structure remains unsolved and details of the transport mechanism, binding sites and conformational changes remain debated. A bacterial homologue of DAT, the leucine transporter (LeuTAa) has been used as a template and framework for modeling and understanding DAT. Free energy profiles obtained from Multi-Configuration Thermodynamic Integration allowed us to correctly identify the primary and secondary binding pockets of LeuTAa. A comparison of free energy profiles for dopamine and cocaine in DAT suggests that the binding site of cocaine is located in a secondary pocket, not the primary substrate site. Two recurring primary pathways for intracellular substrate release from the primary pocket are identified in both transporters using the Random Acceleration Molecular Dynamics method. One pathway appears to follow transmembranes (TMs) 1a and 6b while the other pathway follows along TMs 6b and 8. Interestingly, we observe that a single sodium ion is co-transported with leucine during both simulations types. PMID:23079638

  9. Genome-wide characterisation of Foxa1 binding sites reveals several mechanisms for regulating neuronal differentiation in midbrain dopamine cells.

    PubMed

    Metzakopian, Emmanouil; Bouhali, Kamal; Alvarez-Saavedra, Matías; Whitsett, Jeffrey A; Picketts, David J; Ang, Siew-Lan

    2015-04-01

    Midbrain dopamine neuronal progenitors develop into heterogeneous subgroups of neurons, such as substantia nigra pars compacta, ventral tegmental area and retrorubal field, that regulate motor control, motivated and addictive behaviours. The development of midbrain dopamine neurons has been extensively studied, and these studies indicate that complex cross-regulatory interactions between extrinsic and intrinsic molecules regulate a precise temporal and spatial programme of neurogenesis in midbrain dopamine progenitors. To elucidate direct molecular interactions between multiple regulatory factors during neuronal differentiation in mice, we characterised genome-wide binding sites of the forkhead/winged helix transcription factor Foxa1, which functions redundantly with Foxa2 to regulate the differentiation of mDA neurons. Interestingly, our studies identified a rostral brain floor plate Neurog2 enhancer that requires direct input from Otx2, Foxa1, Foxa2 and an E-box transcription factor for its transcriptional activity. Furthermore, the chromatin remodelling factor Smarca1 was shown to function downstream of Foxa1 and Foxa2 to regulate differentiation from immature to mature midbrain dopaminergic neurons. Our genome-wide Foxa1-bound cis-regulatory sequences from ChIP-Seq and Foxa1/2 candidate target genes from RNA-Seq analyses of embryonic midbrain dopamine cells also provide an excellent resource for probing mechanistic insights into gene regulatory networks involved in the differentiation of midbrain dopamine neurons.

  10. The predicted 3D structure of the human D2 dopamine receptor and the binding site and binding affinities for agonists and antagonists

    NASA Astrophysics Data System (ADS)

    Kalani, M. Yashar S.; Vaidehi, Nagarajan; Hall, Spencer E.; Trabanino, Rene J.; Freddolino, Peter L.; Kalani, Maziyar A.; Floriano, Wely B.; Tak Kam, Victor Wai; Goddard, William A., III

    2004-03-01

    Dopamine neurotransmitter and its receptors play a critical role in the cell signaling process responsible for information transfer in neurons functioning in the nervous system. Development of improved therapeutics for such disorders as Parkinson's disease and schizophrenia would be significantly enhanced with the availability of the 3D structure for the dopamine receptors and of the binding site for dopamine and other agonists and antagonists. We report here the 3D structure of the long isoform of the human D2 dopamine receptor, predicted from primary sequence using first-principles theoretical and computational techniques (i.e., we did not use bioinformatic or experimental 3D structural information in predicting structures). The predicted 3D structure is validated by comparison of the predicted binding site and the relative binding affinities of dopamine, three known dopamine agonists (antiparkinsonian), and seven known antagonists (antipsychotic) in the D2 receptor to experimentally determined values. These structures correctly predict the critical residues for binding dopamine and several antagonists, identified by mutation studies, and give relative binding affinities that correlate well with experiments. The predicted binding site for dopamine and agonists is located between transmembrane (TM) helices 3, 4, 5, and 6, whereas the best antagonists bind to a site involving TM helices 2, 3, 4, 6, and 7 with minimal contacts to TM helix 5. We identify characteristic differences between the binding sites of agonists and antagonists.

  11. [Methoxyflurane and ethanol do not inhibit the neuronal uptake of noradrenaline (uptake 1) at the desipramine binding site].

    PubMed

    Kress, H G; Schömig, E

    1990-07-01

    We recently demonstrated that the net accumulation of 3H-norepinephrine in the rat pheochromocytoma cell line PC12 was reduced by anesthetic concentrations of n-alkanols and the volatile anesthetics halothane, enflurane, isoflurane, and methoxyflurane. In PC12 cells, as in adrenergic neurons, norepinephrine is transported across the plasma membrane by a saturable, high-affinity, carrier-mediated mechanism (uptake1), which follows Michaelis-Menten kinetics, is energy- and sodium-dependent, and is inhibited by low concentrations of cocaine and the tricyclic antidepressant desipramine. Although uptake1 is the most important process for the removal of norepinephrine from the synaptic cleft, the net accumulation of norepinephrine within the neuron also depends on other factors including its vesicular uptake and storage within the granules, its metabolism by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT), and the efflux of its more lipophilic metabolites. In our previous report we could not exclude the contribution of any of these factors to the observed inhibitory effects of volatile substances. Therefore, the aim of the present study with ethanol and methoxyflurane was: (1) to elucidate further the exact mechanism responsible for the reduction of the norepinephrine accumulation; and (2) to investigate the anesthetics' interaction with the substrate recognition site, which is identical with the desipramine binding site on the norepinephrine carrier. METHODS. For 3H-norepinephrine uptake experiments, PC12 cells were cultured on dishes (60 mm, Nunc) coated with polyornithine. Reserpine (10 microM) was added to the culture 24 h before the experiment to deplete endogenous norepinephrine. The initial carrier-mediated transport rate (60 s) was measured as previously described. 3H-desipramine equilibrium binding was determined with isolated plasma membranes prepared from PC12 cells grown in suspension culture. The carrier-mediated uptake of 3H

  12. 3,4-Methylenedioxymethamphetamine and 3,4-methylenedioxyamphetamine destroy serotonin terminals in rat brain: quantification of neurodegeneration by measurement of (/sup 3/H)paroxetine-labeled serotonin uptake sites

    SciTech Connect

    Battaglia, G.; Yeh, S.Y.; O'Hearn, E.; Molliver, M.E.; Kuhar, M.J.; De Souza, E.B.

    1987-09-01

    This study examines the effects of repeated systemic administration (20 mg/kg s.c., twice daily for 4 days) of 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyamphetamine (MDA) on levels of brain monoamines, their metabolites and on the density of monoamine uptake sites in various regions of rat brain. Marked reductions (30-60%) in the concentration of 5-hydroxyindoleacetic acid were observed in cerebral cortex, hippocampus, striatum, hypothalamus and midbrain at 2 weeks after a 4-day treatment regimen of MDMA or MDA; less consistent reductions in serotonin (5-HT) content were observed in these brain regions. In addition, both MDMA and MDA caused comparable and substantial reductions (50-75%) in the density of (/sup 3/H)paroxetine-labeled 5-HT uptake sites in all brain regions examined. In contrast, neither MDMA nor MDA caused any widespread or long-term changes in the content of the catecholaminergic markers (i.e., norepinephrine, dopamine, 3,4 dihydroxyphenylacetic acid and homovanillic acid) or in the number of (/sup 3/H)mazindol-labeled norepinephrine or dopamine uptake sites in the brain regions examined. These data demonstrate that MDMA and MDA cause long-lasting neurotoxic effects with respect to both the functional and structural integrity of serotonergic neurons in brain. Furthermore, our measurement of reductions in the density of 5-HT uptake sites provides a means for quantification of the neurodegenerative effects of MDMA and MDA on presynaptic 5-HT terminals.

  13. Autoradiographic localization of adenosine uptake sites in rat brain using (/sup 3/H)nitrobenzylthioinosine

    SciTech Connect

    Bisserbe, J.C.; Patel, J.; Marangos, P.J.

    1985-02-01

    The adenosine uptake site has been localized in rat brain by an in vitro light microscopic autoradiographic method, using (/sup 3/H)nitrobenzylthioinosine ((/sup 3/H)NBI) as the probe. The binding characteristics of (/sup 3/H)NBI on slide-mounted sections are comparable to those seen in studies performed on brain homogenates. A very high density of uptake sites occurs in the nucleus tractus solitarius, in the superficial layer of the superior colliculus, in several thalamic nuclei, and also in geniculate body nuclei. A high density of sites are also observed in the nucleus accumbens, the caudate putamen, the dorsal tegmentum area, the substantia nigra, and the central gray. The localization of the adenosine uptake site in brain may provide information on the functional activity of the site and suggests the involvement of the adenosine system in the central regulation of cardiovascular function.

  14. Urinary Dopamine as a Potential Index of the Transport Activity of Multidrug and Toxin Extrusion in the Kidney

    PubMed Central

    Kajiwara, Moto; Ban, Tsuyoshi; Matsubara, Kazuo; Nakanishi, Yoichi; Masuda, Satohiro

    2016-01-01

    Dopamine is a cationic natriuretic catecholamine synthesized in proximal tubular cells (PTCs) of the kidney before secretion into the lumen, a key site of its action. However, the molecular mechanisms underlying dopamine secretion into the lumen remain unclear. Multidrug and toxin extrusion (MATE) is a H+/organic cation antiporter that is highly expressed in the brush border membrane of PTCs and mediates the efflux of organic cations, including metformin and cisplatin, from the epithelial cells into the urine. Therefore, we hypothesized that MATE mediates dopamine secretion, a cationic catecholamine, into the tubule lumen, thereby regulating natriuresis. Here, we show that [3H]dopamine uptake in human (h) MATE1-, hMATE-2K- and mouse (m) MATE-expressing cells exhibited saturable kinetics. Fluid retention and decreased urinary excretion of dopamine and Na+ were observed in Mate1-knockout mice compared to that in wild-type mice. Imatinib, a MATE inhibitor, inhibited [3H]dopamine uptake by hMATE1-, hMATE2-K- and mMATE1-expressing cells in a concentration-dependent manner. At clinically-relevant concentrations, imatinib inhibited [3H]dopamine uptake by hMATE1- and hMATE2-K-expressing cells. The urinary excretion of dopamine and Na+ decreased and fluid retention occurred in imatinib-treated mice. In conclusion, MATE transporters secrete renally-synthesized dopamine, and therefore, urinary dopamine has the potential to be an index of the MATE transporter activity. PMID:27483254

  15. The dopamine uptake inhibitor 3 alpha-[bis(4'-fluorophenyl)metoxy]-tropane reduces cocaine-induced early-gene expression, locomotor activity, and conditioned reward.

    PubMed

    Velázquez-Sánchez, Clara; Ferragud, Antonio; Hernández-Rabaza, Vicente; Nácher, Amparo; Merino, Virginia; Cardá, Miguel; Murga, Juan; Canales, Juan J

    2009-11-01

    Benztropine (BZT) analogs, a family of high-affinity dopamine transporter ligands, are molecules that exhibit pharmacological and behavioral characteristics predictive of significant therapeutic potential in cocaine addiction. Here, we examined in mice the effects of 3 alpha-[bis(4'-fluorophenyl)metoxy]-tropane (AHN-1055) on motor activity, conditioned place preference (CPP) and c-Fos expression in the striatum. AHN-1055 produced mild attenuation of spontaneous locomotor activity at a low dose (1 mg/kg) and weak stimulation at a higher dose (10 mg/kg). In parallel, the BZT analog significantly increased c-Fos expression in the dorsolateral caudoputamen at the high dose, whereas producing marginal decreases at low and moderate doses (1, 3 mg/kg) in both dorsal and ventral striatum. Interaction assays showed that cocaine's ability to stimulate locomotor activity was decreased by AHN-1055 treatment, but not by treatment with D-amphetamine. Such reduced ability did not result from an increase in stereotyped behavior. Another dopamine uptake inhibitor, nomifensine, decreased cocaine-induced locomotor activity but evoked by itself intense motor stereotypies. Remarkably, the BZT analog dose-dependently blocked cocaine-induced CPP without producing CPP when given alone, and blocked in conditioned mice cocaine-stimulated early-gene activation in the nucleus accumbens and dorsomedial striatum. These observations provide evidence that AHN-1055 does not behave as a classical psychomotor stimulant and that some of its properties, including attenuation of cocaine-induced striatal c-Fos expression, locomotor stimulation, and CPP, support its candidacy, and that of structurally related molecules, as possible pharmacotherapies in cocaine addiction.

  16. The dopamine uptake inhibitor 3 alpha-[bis(4'-fluorophenyl)metoxy]-tropane reduces cocaine-induced early-gene expression, locomotor activity, and conditioned reward.

    PubMed

    Velázquez-Sánchez, Clara; Ferragud, Antonio; Hernández-Rabaza, Vicente; Nácher, Amparo; Merino, Virginia; Cardá, Miguel; Murga, Juan; Canales, Juan J

    2009-11-01

    Benztropine (BZT) analogs, a family of high-affinity dopamine transporter ligands, are molecules that exhibit pharmacological and behavioral characteristics predictive of significant therapeutic potential in cocaine addiction. Here, we examined in mice the effects of 3 alpha-[bis(4'-fluorophenyl)metoxy]-tropane (AHN-1055) on motor activity, conditioned place preference (CPP) and c-Fos expression in the striatum. AHN-1055 produced mild attenuation of spontaneous locomotor activity at a low dose (1 mg/kg) and weak stimulation at a higher dose (10 mg/kg). In parallel, the BZT analog significantly increased c-Fos expression in the dorsolateral caudoputamen at the high dose, whereas producing marginal decreases at low and moderate doses (1, 3 mg/kg) in both dorsal and ventral striatum. Interaction assays showed that cocaine's ability to stimulate locomotor activity was decreased by AHN-1055 treatment, but not by treatment with D-amphetamine. Such reduced ability did not result from an increase in stereotyped behavior. Another dopamine uptake inhibitor, nomifensine, decreased cocaine-induced locomotor activity but evoked by itself intense motor stereotypies. Remarkably, the BZT analog dose-dependently blocked cocaine-induced CPP without producing CPP when given alone, and blocked in conditioned mice cocaine-stimulated early-gene activation in the nucleus accumbens and dorsomedial striatum. These observations provide evidence that AHN-1055 does not behave as a classical psychomotor stimulant and that some of its properties, including attenuation of cocaine-induced striatal c-Fos expression, locomotor stimulation, and CPP, support its candidacy, and that of structurally related molecules, as possible pharmacotherapies in cocaine addiction. PMID:19606084

  17. Effects of the triple monoamine uptake inhibitor amitifadine on pain-related depression of behavior and mesolimbic dopamine release in rats.

    PubMed

    Miller, Laurence L; Leitl, Michael D; Banks, Matthew L; Blough, Bruce E; Negus, S Stevens

    2015-01-01

    Pain-related depression of behavior and mood is a key therapeutic target in the treatment of pain. Clinical evidence suggests a role for decreased dopamine (DA) signaling in pain-related depression of behavior and mood. Similarly, in rats, intraperitoneal injection of dilute lactic acid (IP acid) serves as a chemical noxious stimulus to produce analgesic-reversible decreases in both (1) extracellular DA levels in nucleus accumbens (NAc) and (2) intracranial self-stimulation (ICSS), an operant behavior reliant on NAc DA. Intraperitonial acid-induced depression of ICSS is blocked by DA transporter (DAT) inhibitors, but clinical viability of selective DAT inhibitors as analgesics is limited by abuse potential. Drugs that produce combined inhibition of both DA and serotonin transporters may retain efficacy to block pain-related behavioral depression with reduced abuse liability. Amitifadine is a "triple uptake inhibitor" that inhibits DAT with approximately 5- to 10-fold weaker potency than it inhibits serotonin and norepinephrine transporters. This study compared amitifadine effects on IP acid-induced depression of NAc DA and ICSS and IP acid-stimulated stretching in male Sprague-Dawley rats. Amitifadine blocked IP acid-induced depression of both NAc DA and ICSS and IP acid-stimulated stretching. In the absence of the noxious stimulus, amitifadine increased NAc levels of both DA and serotonin, and behaviorally, amitifadine produced significant but weak abuse-related ICSS facilitation. Moreover, amitifadine was more potent to block IP acid-induced depression of ICSS than to facilitate control ICSS. These results support consideration of amitifadine and related monoamine uptake inhibitors as candidate analgesics for treatment of pain-related behavioral depression.

  18. An overview of muscle glucose uptake during exercise. Sites of regulation.

    PubMed

    Wasserman, D H; Halseth, A E

    1998-01-01

    The uptake of blood glucose by skeletal muscle is a complex process. In order to be metabolized, glucose must travel the path from blood to interstitium to intracellular space and then be phosphorylated to glucose 6-phosphate (G6P). Movement of glucose from blood to interstitium is determined by skeletal muscle blood flow, capillary recruitment and the endothelial permeability to glucose. The influx of glucose from the interstitium to intracellular space is determined by the number of glucose transporters in the sarcolemma and the glucose gradient across the sarcolemma. The capacity to phosphorylate glucose is determined by the amount of skeletal muscle hexokinase II, hexokinase II compartmentalization within the cell, and the concentration of the hexokinase II inhibitor G6P. Any change in glucose uptake occurs due to an alteration in one or more of these steps. Based on the low calculated intracellular glucose levels and the higher affinity of glucose for phosphorylation relative to transport, glucose transport is generally considered rate-determining for basal muscle glucose uptake. Exercise increases both the movement of glucose from blood to sarcolemma and the permeability of the sarcolemma to glucose. Whether the ability to phosphorylate glucose is increased in the working muscle remains to be clearly shown. It is possible that the accelerated glucose delivery and transport rates during exercise bias regulation so that muscle glucose phosphorylation exerts more control on muscle glucose uptake. Conditions that alter glucose uptake during exercise, such as increased NEFA concentrations, decreased oxygen availability and adrenergic stimulation, must work by altering one or more of the three steps involved in glucose uptake. This review describes the regulation of glucose uptake during exercise at each of these sites under a number of conditions, as well as describing muscle glucose uptake in the post-exercise state.

  19. Differences between high-affinity forskolin binding sites in dopamine-riche and other regions of rat brain

    SciTech Connect

    Poat, J.A.; Cripps, H.E.; Iversen, L.L.

    1988-05-01

    Forskolin labelled with (/sup 3/H) bound to high- and low-affinity sites in the rat brain. The high-affinity site was discretely located, with highest densities in the striatum, nucleus accumbens, olfactory tubercule, substantia nigra, hippocampus, and the molecular layers of the cerebellum. This site did not correlate well with the distribution of adenylate cyclase. The high-affinity striatal binding site may be associated with a stimulatory guanine nucleotide-binding protein. Thus, the number of sites was increased by the addition of Mg/sup 2 +/ and guanylyl imidodiphosphate. Cholera toxin stereotaxically injected into rat striatum increased the number of binding sites, and no further increase was noted following the subsequent addition of guanyl nucleotide. High-affinity forskolin binding sites in non-dopamine-rich brain areas (hippocampus and cerebullum) were modulated in a qualitatively different manner by guanyl nucleotides. In these areas the number of binding sites was significantly reduced by the addition of guanyl nucleotide. These results suggest that forskolin may have a potential role in identifying different functional/structural guanine nucleotide-binding proteins.

  20. Immunomodulatory N-acyl Dopamine Glycosides from the Icelandic Marine Sponge Myxilla incrustans Collected at a Hydrothermal Vent Site.

    PubMed

    Einarsdottir, Eydis; Liu, Hong-Bing; Freysdottir, Jona; Gotfredsen, Charlotte Held; Omarsdottir, Sesselja

    2016-06-01

    A chemical investigation of the sponge (Porifera) Myxilla incrustans collected from the unique submarine hydrothermal vent site Strytan, North of Iceland, revealed a novel family of closely related N-acyl dopamine glycosides. Three new compounds, myxillin A (1), B (2) and C (3), were isolated and structurally elucidated using several analytical techniques, such as HR-MS, 1D and 2D NMR spectroscopy. Myxillin A (1) and B (2)were shown to be structurally similar, composed of a dopamine moiety, but differ in the acyl chain length and saturation. The myxillin C (3) has a dehydrotyrosine moiety composing the same acyl chain and glycosylation as myxillin B (2). Myxillins A (1) and C (3) were tested for immunomodulating activity in an in vitro dendritic cell model. Dendritic cells matured and stimulated in the presence of myxillin A (1) secreted lower levels of IL-12p40, whilst dendritic cells matured and stimulated in the presence of myxillin C (3) secreted lower levels of IL-10 compared with dendritic cells matured and stimulated in the presence of the solvent alone. These opposing results indicate that the structural differences in the aromatic ring part of the molecules could have an impact on the immunological effects of dendritic cells. These molecules could, therefore, prove to be important in preventing inflammatory diseases on the one hand, and inducing a response to fight tumors and/or pathogens on the other hand. Further studies will be needed to confirm these potential uses. PMID:27135626

  1. HIV-1 Tat Protein-Induced Rapid and Reversible Decrease in [3H]Dopamine Uptake: Dissociation of [3H]Dopamine Uptake and [3H]2β-Carbomethoxy-3-β-(4-fluorophenyl)tropane (WIN 35,428) Binding in Rat Striatal Synaptosomes

    PubMed Central

    Zhu, Jun; Mactutus, Charles F.; Wallace, David R.; Booze, Rosemarie M.

    2009-01-01

    Human immunodeficiency virus (HIV)-1 Tat protein plays a key role in the pathogenesis of both HIV-1-associated cognitive-motor disorder and drug abuse. Dopamine (DA) transporter (DAT) function is strikingly altered in patients with HIV-1-associated dementia and a history of chronic drug abuse. This study is the first in vitro evaluation of potential mechanisms underlying the effects of Tat protein on DAT function. Rat striatal synaptosomes were incubated with recombinant Tat1–86 protein, and [3H]DA uptake and the binding of [3H]2β-carbomethoxy-3-β-(4-fluorophenyl)tropane (WIN 35,428) and [3H]1-[2-(diphenylmethoxy)ethyl]-4-(3-phenylpropyl)-piperazine (GBR 12935) were determined. Tat decreased [3H]DA uptake, [3H]WIN 35,428 binding, and [3H]GBR 12935 binding in a time-dependent manner. The potency of Tat for inhibiting [3H]DA uptake (Ki = 1.2 μM) was the same as that for inhibiting [3H]GBR 12935 binding but 3-fold less than that for inhibiting [3H]WIN 35,428 binding. Mutant Tat proteins did not alter [3H]DA uptake. Kinetic analysis of [3H]DA uptake revealed that Tat (1 or 10 μM) decreased the Vmax value and increased the Km value in a dose-dependent manner. The Vmax value, decreased by Tat (1 μM), returned to the control level after washout of Tat, indicating that the inhibitory effect of Tat on DA uptake was reversible. Saturation studies revealed that Tat decreased the Bmax value and increased the Kd value of [3H]WIN 35,428 binding, whereas Tat decreased the Bmax value of [3H]GBR 12935 binding, without a change in the Kd value. These findings provide new insight into understanding the pharmacological mechanisms of Tat-induced dysfunction of the DAT in the dopaminergic system in HIV-infected patients. PMID:19325033

  2. Native Plant Uptake Model for Radioactive Waste Disposal Areas at the Nevada Test Site

    SciTech Connect

    BROWN,THERESA J.; WIRTH,SHARON

    1999-09-01

    This report defines and defends the basic framework, methodology, and associated input parameters for modeling plant uptake of radionuclides for use in Performance Assessment (PA) activities of Radioactive Waste Management Sites (RWMS) at the Nevada Test Site (NTS). PAs are used to help determine whether waste disposal configurations meet applicable regulatory standards for the protection of human health, the environment, or both. Plants adapted to the arid climate of the NTS are able to rapidly capture infiltrating moisture. In addition to capturing soil moisture, plant roots absorb nutrients, minerals, and heavy metals, transporting them within the plant to the above-ground biomass. In this fashion, plant uptake affects the movement of radionuclides. The plant uptake model presented reflects rooting characteristics important to plant uptake, biomass turnover rates, and the ability of plants to uptake radionuclides from the soil. Parameters are provided for modeling plant uptake and estimating surface contaminant flux due to plant uptake under both current and potential future climate conditions with increased effective soil moisture. The term ''effective moisture'' is used throughout this report to indicate the soil moisture that is available to plants and is intended to be inclusive of all the variables that control soil moisture at a site (e.g., precipitation, temperature, soil texture, and soil chemistry). Effective moisture is a concept used to simplify a number of complex, interrelated soil processes for which there are too little data to model actual plant available moisture. The PA simulates both the flux of radionuclides across the land surface and the potential dose to humans from that flux. Surface flux is modeled here as the amount of soil contamination that is transferred from the soil by roots and incorporated into aboveground biomass. Movement of contaminants to the surface is the only transport mechanism evaluated with the model presented here

  3. Binding site residues control inhibitor selectivity in the human norepinephrine transporter but not in the human dopamine transporter

    PubMed Central

    Andersen, Jacob; Ringsted, Kristoffer B.; Bang-Andersen, Benny; Strømgaard, Kristian; Kristensen, Anders S.

    2015-01-01

    The transporters for norepinephrine and dopamine (NET and DAT, respectively) constitute the molecular targets for recreational drugs and therapeutics used in the treatment of psychiatric disorders. Despite a strikingly similar amino acid sequence and predicted topology between these transporters, some inhibitors display a high degree of selectivity between NET and DAT. Here, a systematic mutational analysis of non-conserved residues within the extracellular entry pathway and the high affinity binding site in NET and DAT was performed to examine their role for selective inhibitor recognition. Changing the six diverging residues in the central binding site of NET to the complementary residues in DAT transferred a DAT-like pharmacology to NET, showing that non-conserved binding site residues in NET are critical determinants for inhibitor selectivity. In contrast, changing the equivalent residues in the central site of DAT to the corresponding residues in NET had modest effects on the same inhibitors, suggesting that non-conserved binding site residues in DAT play a minor role for selective inhibitor recognition. Our data points towards distinct structural determinants governing inhibitor selectivity in NET and DAT, and provide important new insight into the molecular basis for NET/DAT selectivity of therapeutic and recreational drugs. PMID:26503701

  4. Distribution of 3H-GABA uptake sites in the nematode Ascaris

    SciTech Connect

    Guastella, J.; Stretton, A.O. )

    1991-05-22

    The distribution of uptake sites for the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the nematode Ascaris suum was examined by autoradiography of 3H-GABA uptake. Single neural processes in both the ventral and dorsal nerve cords were labeled with 3H-GABA. Serial section analysis identified the cells of origin of these processes as the RMEV-like and RMED-like neurons. These cells belong to a set of four neurons in the nerve ring, all of which are labeled by 3H-GABA. 3H-GABA labeling of at least two other sets of cephalic neurons was seen. One of these pairs consists of medium-sized lateral ganglia neurons, located at the level of the amphid commissure bundle. A second pair is located in the lateral ganglia at the level of the deirid commissure bundle. The position and size of these lateral ganglia cells suggest that they are the GABA-immunoreactive lateral ganglia cells frequently seen in whole-mount immunocytochemical preparations. Four neuronal cell bodies located in the retrovesicular ganglion were also labeled with 3H-GABA. These cells, which are probably cholinergic excitatory motor neurons, do not contain detectable GABA-like immunoreactivity. Heavy labeling of muscle cells was also observed. The ventral and dorsal nerve cord inhibitory motor neurons, which are known to contain GABA-like immunoreactivity, were not labeled above background with 3H-GABA. Together with the experiments reported previously, these results define three classes of GABA-associated neurons in Ascaris: (1) neurons that contain endogenous GABA and possess a GABA uptake system; (2) neurons that contain endogenous GABA, but that either lack a GABA uptake system or possess a GABA uptake system of low activity; (3) neurons that possess a GABA uptake system, but that lack endogenous GABA.

  5. Rates and tissue sites of non-insulin- and insulin-mediated glucose uptake in humans

    SciTech Connect

    Baron, A.D.; Brechtel, G.; Wallace, P.; Edelman, S.V.

    1988-12-01

    In vivo glucose uptake can occur via two mechanisms, namely, insulin-mediated glucose uptake (IMGU) and non-insulin-mediated glucose uptake (NIMGU). Although the principal tissue sites for IMGU are skeletal muscle, the tissue sites for NIMGU at a given serum glucose concentration are not known. To examine this issue, rates of whole body glucose uptake (Rd) were measured at basal and during glucose clamp studies performed at euglycemia (approximately 90 mg/dl) and hyperglycemia (approximately 220 mg/dl) in six lean healthy men. Studies were performed during hyperinsulinemia (approximately 70 microU/ml) and during somatostatin-induced insulinopenia to measure IMGU and NIMGU, respectively. During each study, leg glucose balance (arteriovenous catheter technique) was also measured. With this approach, rates of whole body skeletal muscle IMGU and NIMGU can be estimated, and the difference between overall Rd and skeletal muscle glucose uptake represents non-skeletal muscle Rd. The results indicate that approximately 20% of basal Rd is into skeletal muscle. During insulinopenia approximately 86% of body NIMGU occurs in non-skeletal muscle tissues at euglycemia. When hyperglycemia was created, whole body NIMGU increased from 128 +/- 6 to 213 +/- 18 mg/min (P less than 0.01); NIMGU into non-skeletal muscle tissues was 134 +/- 11 and 111 +/- 6 mg/min at hyperglycemia and euglycemia, respectively, P = NS. Therefore, virtually all the hyperglycemia induced increment in NIMGU occurred in skeletal muscle. During hyperinsulinemia, IMGU in skeletal muscle represented 75 and 95% of body Rd, at euglycemia and hyperglycemia, respectively.

  6. Amphetamine paradoxically augments exocytotic dopamine release and phasic dopamine signals.

    PubMed

    Daberkow, D P; Brown, H D; Bunner, K D; Kraniotis, S A; Doellman, M A; Ragozzino, M E; Garris, P A; Roitman, M F

    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 nonexocytotic 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 2 h. 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, nonelectrically evoked, phasic increases in extracellular dopamine. Finally, using an operant sugar reward paradigm, we showed that low-dose AMPH augmented dopamine transients elicited by sugar-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 upregulation 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

  7. Uptake of nitroaromatic compounds in plants : Implications for risk assessment of ammunition sites.

    PubMed

    Schneider, K; Oltmanns, J; Radenberg, T; Schneider, T; Pauly-Mundegar, D

    1996-09-01

    The uptake of nitroaromatic compounds by plants from the soil was studied at an ammunition site. After the development of analytical methods for 2,4,6-trinitrotoluene, aminodinitrotoluenes and dinitrotoluenes in plant material, we could show that these substances accumulated in the roots of plants and are found to a lesser extent inleaves and stems. We observed only moderate differences between various plant species. It is likely that a metabolic transformation in plants leads to the formation of dinitrotoluenes which are considered to be potent carcinogens. Results from soils with a wide range of explosive concentrations show a good correlation between the plant and soil concentrations. The relative accumulation in plant material is higher at lower soil concentrations. At low soil concentrations of about 1 mg trinitrotoluene/kg soil, an accumulation factor of about 0.5 can be derived. These data are an important input for the risk assessment of ammunition sites.

  8. Urinary Dopamine as a Potential Index of the Transport Activity of Multidrug and Toxin Extrusion in the Kidney.

    PubMed

    Kajiwara, Moto; Ban, Tsuyoshi; Matsubara, Kazuo; Nakanishi, Yoichi; Masuda, Satohiro

    2016-01-01

    Dopamine is a cationic natriuretic catecholamine synthesized in proximal tubular cells (PTCs) of the kidney before secretion into the lumen, a key site of its action. However, the molecular mechanisms underlying dopamine secretion into the lumen remain unclear. Multidrug and toxin extrusion (MATE) is a H⁺/organic cation antiporter that is highly expressed in the brush border membrane of PTCs and mediates the efflux of organic cations, including metformin and cisplatin, from the epithelial cells into the urine. Therefore, we hypothesized that MATE mediates dopamine secretion, a cationic catecholamine, into the tubule lumen, thereby regulating natriuresis. Here, we show that [³H]dopamine uptake in human (h) MATE1-, hMATE-2K- and mouse (m) MATE-expressing cells exhibited saturable kinetics. Fluid retention and decreased urinary excretion of dopamine and Na⁺ were observed in Mate1-knockout mice compared to that in wild-type mice. Imatinib, a MATE inhibitor, inhibited [³H]dopamine uptake by hMATE1-, hMATE2-K- and mMATE1-expressing cells in a concentration-dependent manner. At clinically-relevant concentrations, imatinib inhibited [³H]dopamine uptake by hMATE1- and hMATE2-K-expressing cells. The urinary excretion of dopamine and Na⁺ decreased and fluid retention occurred in imatinib-treated mice. In conclusion, MATE transporters secrete renally-synthesized dopamine, and therefore, urinary dopamine has the potential to be an index of the MATE transporter activity. PMID:27483254

  9. Effects of repeated oral doses of dexnorfenfluramine on 5-HT levels and 5-HT uptake sites in rat brain.

    PubMed

    Gobbi, M; Bergami, A; Caltavuturo, C; Valle, F D; Mennini, T; Caccia, S

    1996-11-15

    The effects of oral dexnorfenfluramine (DNF; 1-4 mg/kg, twice daily for 4 days), the active metabolite of dexfenfluramine, were examined on rat regional brain indole contents and [3H]citalopram binding. Two hours after the last dose, serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were dose-dependently lowered at doses above 1.5 mg/kg, with slight regional differences. Cortical 5-HT uptake sites were reduced only at the highest dose. Above 2 mg/kg DNF also caused a more lasting reduction (4 weeks) of regional indoles and cortical 5-HT uptake sites. At this longer time while the decrease in hippocampal 5-HT levels and cortical 5-HT uptake sites remained essentially constant, cortical and striatal 5-HT levels were lowered less than at 2 h, suggesting a return toward control values.

  10. Water uptake by two river red gum ( Eucalyptus camaldulensis) clones in a discharge site plantation in the Western Australian wheatbelt

    NASA Astrophysics Data System (ADS)

    Marshall, John K.; Morgan, Anne L.; Akilan, Kandia; Farrell, Richard C. C.; Bell, David T.

    1997-12-01

    The heat-pulse technique was used to estimate year-long water uptake in a discharge zone plantation of 9-year-old clonal Eucalyptus camaldulensis Dehnh. near Wubin, Western Australia. Water uptake matched rainfall closely during weter months but exceeded rainfall as the dry season progressed. Average annual water uptake (1148 mm) exceeded rainfall (432 mm) by about 2.7 fold and approached 56% of pan evaporation for the area. The data suggest that at least 37% (i.e. ( {1}/{2.7}) × 100 ) of the lower catchment discharge zone should be planted to prevent the rise of groundwater. Water uptake varied with soil environment, season and genotype. Upslope trees used more water than did downslope trees. Water uptake was higher in E. camaldulensis clone M80 than in clone M66 until late spring. The difference reversed as summer progressed. Both clones, however, have the potential to dry out the landscape when potential evapotranspiration exceeds rainfall. This variation in water uptake within the species indicates the potential for manipulating plantation uptake by matching tree characteristics to site characteristics. Controlled experiments on the heat-pulse technique indicated accuracy errors of approximately 10%. This, combined with the ability to obtain long-term, continuous data and the superior logistics of use of the heat-pulse technique, suggests that results obtained by it would be much more reliable than those achieved by the ventilated chamber technique.

  11. Missense dopamine transporter mutations associate with adult parkinsonism and ADHD

    PubMed Central

    Hansen, Freja H.; Skjørringe, Tina; Yasmeen, Saiqa; Arends, Natascha V.; Sahai, Michelle A.; Erreger, Kevin; Andreassen, Thorvald F.; Holy, Marion; Hamilton, Peter J.; Neergheen, Viruna; Karlsborg, Merete; Newman, Amy H.; Pope, Simon; Heales, Simon J.R.; Friberg, Lars; Law, Ian; Pinborg, Lars H.; Sitte, Harald H.; Loland, Claus; Shi, Lei; Weinstein, Harel; Galli, Aurelio; Hjermind, Lena E.; Møller, Lisbeth B.; Gether, Ulrik

    2014-01-01

    Parkinsonism and attention deficit hyperactivity disorder (ADHD) are widespread brain disorders that involve disturbances of dopaminergic signaling. The sodium-coupled dopamine transporter (DAT) controls dopamine homeostasis, but its contribution to disease remains poorly understood. Here, we analyzed a cohort of patients with atypical movement disorder and identified 2 DAT coding variants, DAT-Ile312Phe and a presumed de novo mutant DAT-Asp421Asn, in an adult male with early-onset parkinsonism and ADHD. According to DAT single-photon emission computed tomography (DAT-SPECT) scans and a fluoro-deoxy-glucose-PET/MRI (FDG-PET/MRI) scan, the patient suffered from progressive dopaminergic neurodegeneration. In heterologous cells, both DAT variants exhibited markedly reduced dopamine uptake capacity but preserved membrane targeting, consistent with impaired catalytic activity. Computational simulations and uptake experiments suggested that the disrupted function of the DAT-Asp421Asn mutant is the result of compromised sodium binding, in agreement with Asp421 coordinating sodium at the second sodium site. For DAT-Asp421Asn, substrate efflux experiments revealed a constitutive, anomalous efflux of dopamine, and electrophysiological analyses identified a large cation leak that might further perturb dopaminergic neurotransmission. Our results link specific DAT missense mutations to neurodegenerative early-onset parkinsonism. Moreover, the neuropsychiatric comorbidity provides additional support for the idea that DAT missense mutations are an ADHD risk factor and suggests that complex DAT genotype and phenotype correlations contribute to different dopaminergic pathologies. PMID:24911152

  12. Sites of calcium uptake of fish otoliths correspond with macular regions rich of carbonic anhydrase

    NASA Astrophysics Data System (ADS)

    Beier, M.; Anken, R.; Hilbig, R.

    2006-01-01

    Based on pharmacological data, it has been suggested that the enzyme carbonic anhydrase (CAH) plays a prominent role in the mineralization of fish otoliths. To directly test this proposal, the topographical distribution of CAH was histochemically analyzed in the utricular and saccular maculae of larval cichlid fish Oreochromis mossambicus. Further investigations were focussed on the sites of otolithic calcium uptake using the fluorescent calcium tracer alizarin-complexone (AC). Both in the utricle and the saccule, CAH-reactivity was prominent in regions on both sides of the sensory macula (centrifugal (cf) and centripetal (cp) areas), which reportedly contain ionocytes, specialized cells regulating the ionic composition of the endolymph. (The terms centrifugal and centripetal were chosen instead of lateral and medial, because the saccule is positioned perpendicular to the utricle; “lateral” and “medial” thus do not allow an unambiguous allocation of the respective regions.) In the saccule, the size of cf and cp did not differ from each other, whereas, in the utricle, cp was considerably larger as compared to cf (CAH-reactivity per μm2 was nearly identical in both areas of both endorgans). AC-incubation resulted in a fluorescent band on the proximal surface of the otoliths (this surface lies next to the sensory epithelium). In saccular otoliths (sagittae), the area of the band did not differ between centrifugal and centripetal otolith regions, whereas in the utricular otoliths (lapilli), the area of the centripetal AC-band was larger in size as compared to the centrifugal one (AC-fluorescence per μm2 did not differ between the areas analyzed in both types of otoliths). These results strongly suggest that calcium/carbonate uptake of otoliths takes place especially in those regions of their proximal face which are located adjacent to CAH-rich areas of the macular epithelium. It is thus concluded that CAH is directly involved in otolith calcification. The

  13. Blockade of uptake for dopamine, but not norepinephrine or 5-HT, increases selection of high effort instrumental activity: Implications for treatment of effort-related motivational symptoms in psychopathology.

    PubMed

    Yohn, Samantha E; Errante, Emily E; Rosenbloom-Snow, Aaron; Somerville, Matthew; Rowland, Margaret; Tokarski, Kristin; Zafar, Nadia; Correa, Merce; Salamone, John D

    2016-10-01

    Deficits in behavioral activation, exertion of effort, and other psychomotor/motivational symptoms are frequently seen in people with depression and other disorders. Depressed people show a decision bias towards selection of low effort activities, and animal tests of effort-related decision making are being used as models of motivational dysfunctions seen in psychopathology. The present studies investigated the ability of drugs that block dopamine transport (DAT), norepinephrine transport (NET), and serotonin transport (SERT) to modulate work output in rats responding on a test of effort-related decision making (i.e., a progressive ratio (PROG)/chow feeding choice task). With this task, rats choose between working for a preferred food (high carbohydrate pellets) by lever pressing on a PROG schedule vs. obtaining a less preferred lab chow that is freely available in the chamber. The present studies focused on the effects of the selective DAT inhibitor GBR12909, the selective SERT inhibitor fluoxetine, and the selective NET inhibitors desipramine and atomoxetine. Acute and repeated administration of GBR12909 shifted choice behavior, increasing measures of PROG lever pressing but decreasing chow intake. In contrast, fluoxetine, desipramine and atomoxetine failed to increase lever pressing output, and actually decreased it at higher doses. In the behaviorally effective dose range, GBR12909 elevated extracellular dopamine levels in accumbens core as measured by microdialysis, but fluoxetine, desipramine and atomoxetine decreased extracellular dopamine. Thus, blockade of DAT increases selection of the high effort instrumental activity, while inhibition of SERT or NET does not. These results have implications for the use of monoamine uptake inhibitors for the treatment of effort-related psychiatric symptoms in humans. PMID:27329556

  14. Blockade of uptake for dopamine, but not norepinephrine or 5-HT, increases selection of high effort instrumental activity: Implications for treatment of effort-related motivational symptoms in psychopathology.

    PubMed

    Yohn, Samantha E; Errante, Emily E; Rosenbloom-Snow, Aaron; Somerville, Matthew; Rowland, Margaret; Tokarski, Kristin; Zafar, Nadia; Correa, Merce; Salamone, John D

    2016-10-01

    Deficits in behavioral activation, exertion of effort, and other psychomotor/motivational symptoms are frequently seen in people with depression and other disorders. Depressed people show a decision bias towards selection of low effort activities, and animal tests of effort-related decision making are being used as models of motivational dysfunctions seen in psychopathology. The present studies investigated the ability of drugs that block dopamine transport (DAT), norepinephrine transport (NET), and serotonin transport (SERT) to modulate work output in rats responding on a test of effort-related decision making (i.e., a progressive ratio (PROG)/chow feeding choice task). With this task, rats choose between working for a preferred food (high carbohydrate pellets) by lever pressing on a PROG schedule vs. obtaining a less preferred lab chow that is freely available in the chamber. The present studies focused on the effects of the selective DAT inhibitor GBR12909, the selective SERT inhibitor fluoxetine, and the selective NET inhibitors desipramine and atomoxetine. Acute and repeated administration of GBR12909 shifted choice behavior, increasing measures of PROG lever pressing but decreasing chow intake. In contrast, fluoxetine, desipramine and atomoxetine failed to increase lever pressing output, and actually decreased it at higher doses. In the behaviorally effective dose range, GBR12909 elevated extracellular dopamine levels in accumbens core as measured by microdialysis, but fluoxetine, desipramine and atomoxetine decreased extracellular dopamine. Thus, blockade of DAT increases selection of the high effort instrumental activity, while inhibition of SERT or NET does not. These results have implications for the use of monoamine uptake inhibitors for the treatment of effort-related psychiatric symptoms in humans.

  15. Effects of high-dose fenfluramine treatment on monoamine uptake sites in rat brain: Assessment using quantitative autoradiography

    SciTech Connect

    Appel, N.M.; Mitchell, W.M.; Contrera, J.F.; De Souza, E.B. )

    1990-01-01

    Fenfluramine is an amphetamine derivative that in humans is used primarily as an anorectic agent in the treatment of obesity. In rats, subchronic high-dose d,l-fenfluramine treatment (24 mg/kg subcutaneously, twice daily for 4 days) causes long-lasting decreases in brain serotonin (5HT), its metabolite 5-hydroxyindoleacetic acid, and high-affinity 5HT uptake sites. Moreover, this high-dose treatment regimen causes both selective long-lasting decreases in fine-caliber 5HT-immunoreactive axons and appearance of other 5HT-immunoreactive axons with morphology characteristic of degenerating axons. Determination of the potential neurotoxic effects of fenfluramine treatment using immunohistochemistry is limited from the perspectives that staining is difficult to quantify and that it relies on presence of the antigen (in this case 5HT), and the 5HT-depleting effects of fenfluramine are well known. In the present study, we used quantitative in vitro autoradiography to assess, in detail, the density and regional distribution of (3H)paroxetine-labeled 5HT and (3H)mazindol-labeled catecholamine uptake sites in response to the high-dose fenfluramine treatment described above. Because monoamine uptake sites are concentrated on monoamine-containing nerve terminals, decreases in uptake site density would provide a quantitative assessment of potential neurotoxicity resulting from this fenfluramine treatment regimen. Marked decreases in densities of (3H)paroxetine-labeled 5HT uptake sites occurred in brain regions in which fenfluramine treatment decreased the density of 5HT-like immunostaining when compared to saline-treated control rats. These included cerebral cortex, caudate putamen, hippocampus, thalamus, and medial hypothalamus.

  16. Soil contamination and plant uptake of heavy metals at polluted sites in China.

    PubMed

    Wang, Qing-Ren; Cui, Yan-Shan; Liu, Xiu-Mei; Dong, Yi-Ting; Christie, Peter

    2003-05-01

    We investigated heavy metal contamination in soils and plants at polluted sites in China including some with heavy industries, metal mining, smelting and untreated wastewater irrigation areas. We report our main findings in this paper. The concentrations of heavy metals, including Cd and Zn, in the soils at the investigated sites were above the background levels, and generally exceeded the Government guidelines for metals in soil. The concentrations of metals in plants served to indicate the metal contamination status of the site, and also revealed the abilities of various plant species to take up and accumulate the metals from the soil. Substantial differences in the accumulation of heavy metals were observed among the plant species investigated. Polygonum hydropiper growing on contaminated soils in a sewage pond had accumulated 1061 mg kg(-1) of Zn in its shoots. Rumex acetosa L. growing near a smelter had accumulated more than 900 mg kg(-1) of Zn both in its shoots and roots. Therefore these species have potential for phytoremediation of metal-contaminated sites. Our results indicate the need to elucidate the dynamics of soil metal contamination of plants and the onward movement of metal contaminants into the food chain. Also our results indicate that the consumption of rice grown in paddy soils contaminated with Cd, Cr or Zn may pose a serious risk to human health, because from 24 to 22% of the total metal content in the rice biomass was concentrated in the rice grain. Platanus acerifolia growing on heavily contaminated soil accumulated only very low levels of heavy metals, and this mechanism for excluding metal uptake may have value in crop improvement. Sources of metal entering the environmental matrices studied included untreated wastewater, tailings or slurries and dust depositions from metal ore mining, and sewage sludge. Pb, Zn or Cd concentrations declined with the distance from metal smelter in accordance with a good exponential correlation (R2

  17. Similarity of nutrient uptake and root dimensions of Engelmann spruce and subalpine fir at two contrasting sites in Colorado

    SciTech Connect

    Yanai, R; McFarlane, K; Lucash, M; Kulpa, S; Wood, D

    2009-10-09

    Nutrient uptake capacity is an important parameter in modeling nutrient uptake by plants. Researchers commonly assume that uptake capacity measured for a species can be used across sites. We tested this assumption by measuring the nutrient uptake capacity of intact roots of Engelmann spruce (Picea engelmanni Parry) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) at Loch Vale Watershed and Fraser Experimental Forest in the Rocky Mountains of central Colorado. Roots still attached to the tree were exposed to one of three concentrations of nutrient solutions for time periods ranging from 1 to 96 hours, and solutions were analyzed for ammonium, nitrate, calcium, magnesium, and potassium. Surprisingly, the two species were indistinguishable in nutrient uptake within site for all nutrients (P > 0.25), but uptake rates differed by site. In general, nutrient uptake was higher at Fraser (P = 0.01, 0.15, 0.03, 0.18 for NH{sub 4}{sup +}, NO{sub 3}{sup -}, Ca{sup 2+}, and K{sup +}, respectively), which is west of the Continental Divide and has lower atmospheric deposition of N than Loch Vale. Mean uptake rates by site for ambient solution concentrations were 0.12 {micro}mol NH{sub 4}{sup +} g{sub fwt}{sup -1} h{sup -1}, 0.02 {micro}mol NO{sub 3}{sup -} g{sub fwt}{sup -1}, 0.21 {micro}mol Ca{sup 2+} g{sub fwt}{sup -1} h{sup -1}, and 0.01 {micro}mol Mg{sup 2+} g{sub fwt}{sup -1} h{sup -1} at Loch Vale, and 0.21 {micro}mol NH{sub 4}{sup +} f{sub fwt}{sup -1}h{sup -1}, 0.04 {micro}mol NO{sub 3}{sup -} g{sub fwt}{sup -1} h{sup -1}, 0.51 {micro}mol Ca{sup 2+}g{sub fwt}{sup -1}h{sup -1}, and 0.07 {micro}mol Mg{sup 2+} f{sub fwt}{sup -1}h{sup -1} at Fraser. The importance of site conditions in determining uptake capacity should not be overlooked when parameterizing nutrient uptake models. We also characterized the root morphology of these two species and compared them to other tree species we have measured at various sites in the northeastern USA. Engelman spruce and subalpine fir

  18. In vivo labeling of 5-hydroxytryptamine uptake sites in mouse brain with ( sup 3 H)-6-nitroquipazine

    SciTech Connect

    Hashimoto, K.; Goromaru, T. )

    1990-10-01

    6-Nitroquipazine (DU 24565; 6-nitro 2-piperazinylquinoline) is a very potent 5-hydroxytryptamine (5-HT; serotonin) uptake inhibitor. It has been demonstrated very recently that (3H)-6-nitroquipazine is a suitable radioligand for studying 5-HT uptake sites. The present study evaluates (3H)6-nitroquipazine as a radioligand for in vivo labeling of 5-HT uptake sites in mouse brain. Very high uptake of radioactivity in the brain after i.v. administration of (3H)-6-nitroquipazine was shown. Regional distribution of the radioactivity in mouse brain 3 hr after injection of (3H)-6-nitroquipazine was in the order (highest to lowest) hypothalamus greater than midbrain greater than striatum greater than hippocampus greater than cerebral cortex greater than medulla oblongata greater than cerebellum. The regional distribution of in vivo (3H)-6-nitroquipazine binding in mouse brain was highly correlated with that in rat brain obtained from previous in vitro binding studies. Coadministration of carrier 6-nitroquipazine (5 mg/kg) significantly decreased the radioactivity in the hypothalamus, whereas that in the cerebellum and cerebral cortex was increased. Because the cerebellum has very low density of (3H)-6-nitroquipazine binding sites, the radioactivity in the cerebellum could, therefore, reflect the amount on nonspecific binding and free ligand. Kinetic studies showed highest in vivo specific binding 1 hr after injection of (3H)-6-nitroquipazine and slow clearance of specific binding. Specific binding in the hypothalamus was inhibited in a stereoselective manner by the stereoisomers of norzimelidine. Furthermore, specific binding in the hypothalamus was reduced by several 5-HT uptake inhibitors, in a dose-dependent manner.

  19. Exemplifying whole-plant ozone uptake in adult forest trees of contrasting species and site conditions.

    PubMed

    Nunn, Angela J; Wieser, Gerhard; Metzger, Ursula; Löw, Markus; Wipfler, Philip; Häberle, Karl-Heinz; Matyssek, Rainer

    2007-04-01

    Whole-tree O3 uptake was exemplified for Picea abies, Fagus sylvatica and Larix decidua in stands at high and low altitude and contrasting water availability through sap flow measurement in tree trunks, intrinsically accounting for drought and boundary layer effects on O3 flux. O3 uptake of evergreen spruce per unit foliage area was enhanced by 100% at high relative to low elevation, whereas deciduous beech and larch showed similar uptake regardless of altitude. The responsiveness of the canopy conductance to water vapor and, as a consequence, O3 uptake to soil moisture and air humidity did not differ between species. Unifying findings at the whole-tree level will promote cause-effect based O3 risk assessment and modeling. PMID:16996178

  20. Exemplifying whole-plant ozone uptake in adult forest trees of contrasting species and site conditions.

    PubMed

    Nunn, Angela J; Wieser, Gerhard; Metzger, Ursula; Löw, Markus; Wipfler, Philip; Häberle, Karl-Heinz; Matyssek, Rainer

    2007-04-01

    Whole-tree O3 uptake was exemplified for Picea abies, Fagus sylvatica and Larix decidua in stands at high and low altitude and contrasting water availability through sap flow measurement in tree trunks, intrinsically accounting for drought and boundary layer effects on O3 flux. O3 uptake of evergreen spruce per unit foliage area was enhanced by 100% at high relative to low elevation, whereas deciduous beech and larch showed similar uptake regardless of altitude. The responsiveness of the canopy conductance to water vapor and, as a consequence, O3 uptake to soil moisture and air humidity did not differ between species. Unifying findings at the whole-tree level will promote cause-effect based O3 risk assessment and modeling.

  1. Simultaneous Detection of c-Fos Activation from Mesolimbic and Mesocortical Dopamine Reward Sites Following Naive Sugar and Fat Ingestion in Rats.

    PubMed

    Dela Cruz, Julie A D; Coke, Tricia; Bodnar, Richard J

    2016-01-01

    This study uses cellular c-fos activation to assess effects of novel ingestion of fat and sugar on brain dopamine (DA) pathways in rats. Intakes of sugars and fats are mediated by their innate attractions as well as learned preferences. Brain dopamine, especially meso-limbic and meso-cortical projections from the ventral tegmental area (VTA), has been implicated in both of these unlearned and learned responses. The concept of distributed brain networks, wherein several sites and transmitter/peptide systems interact, has been proposed to mediate palatable food intake, but there is limited evidence empirically demonstrating such actions. Thus, sugar intake elicits DA release and increases c-fos-like immunoreactivity (FLI) from individual VTA DA projection zones including the nucleus accumbens (NAC), amygdala (AMY) and medial prefrontal cortex (mPFC) as well as the dorsal striatum. Further, central administration of selective DA receptor antagonists into these sites differentially reduce acquisition and expression of conditioned flavor preferences elicited by sugars or fats. One approach by which to determine whether these sites interacted as a distributed brain network in response to sugar or fat intake would be to simultaneous evaluate whether the VTA and its major mesotelencephalic DA projection zones (prelimbic and infralimbic mPFC, core and shell of the NAc, basolateral and central-cortico-medial AMY) as well as the dorsal striatum would display coordinated and simultaneous FLI activation after oral, unconditioned intake of corn oil (3.5%), glucose (8%), fructose (8%) and saccharin (0.2%) solutions. This approach is a successful first step in identifying the feasibility of using cellular c-fos activation simultaneously across relevant brain sites to study reward-related learning in ingestion of palatable food in rodents. PMID:27583636

  2. High and Reversible Ammonia Uptake in Mesoporous Azolate Metal-Organic Frameworks with Open Mn, Co, and Ni Sites.

    PubMed

    Rieth, Adam J; Tulchinsky, Yuri; Dincă, Mircea

    2016-08-01

    A series of new mesoporous metal-organic frameworks (MOFs) made from extended bisbenzenetriazolate linkers exhibit coordinatively unsaturated metal sites that are responsible for high and reversible uptake of ammonia. Isostructural Mn, Co, and Ni materials adsorb 15.47, 12.00, and 12.02 mmol of NH3/g, respectively, at STP. Importantly, these near-record capacities are reversible for at least three cycles. These results demonstrate that azolate MOFs are sufficiently thermally and chemically stable to find uses in recyclable sorption, storage, and potentially separation of chemically challenging and/or corrosive gases, especially when designed to exhibit a high density of open metal sites.

  3. Different components of /sup 3/H-imipramine binding in rat brain membranes: relation to serotonin uptake sites

    SciTech Connect

    Gobbi, M.; Taddei, C.; Mennini, T.

    1988-01-01

    In the present paper, the authors confirm and extend previous studies showing heterogeneous /sup 3/H-imipramine (/sup 3/H-IMI) binding sites. Inhibition curves of various drugs (serotonin, imipramine, desmethyl-imipramine, d-fenfluramine, d-norfenfluramine and indalpine, a potent serotonin uptake inhibitor) obtained using 2 nM /sup 3/H-IMI and in presence of 120 mM NaCl, confirmed the presence of at least three /sup 3/H-IMI binding sites: two of these were serotonin-insensitive while the third one was selectively inhibited by serotonin and indalpine with nanomolar affinities. Moreover this last component was found to be selectively modulated by chronic imipramine treatment thus suggesting a close relation to serontonin uptake mechanism. These data indicate that the use of a more selective inhibitors of the serotonin-sensitive component (like indalpine or serotonin itself) to define non specific /sup 3/H-IMI, may be of help in understanding its relation with serotonin uptake system. 22 references, 2 figures, 2 tables.

  4. Knowledge, attitude, and uptake related to human papillomavirus vaccination among young women in Germany recruited via a social media site

    PubMed Central

    Remschmidt, Cornelius; Walter, Dietmar; Schmich, Patrick; Wetzstein, Matthias; Deleré, Yvonne; Wichmann, Ole

    2014-01-01

    Background: Many industrialized countries have introduced human papillomavirus (HPV) vaccination of young women, but vaccine uptake often remains suboptimal. This study aimed to investigate whether a social media site like Facebook is an appropriate tool to assess knowledge, attitude and uptake related to HPV vaccination in young women in Germany. Methods: Between December 2012 and January 2013 two different targeting strategies were implemented on Facebook, providing a link to an online questionnaire. Advertisements were displayed to female Facebook users aged 18–25 years living in Germany. During the simple targeting strategy, advertisements comprised health-related images along with various short titles and text messages. During the focused strategy, advertisements were targeted to users who in addition had certain fashion brands or pop stars listed on their profiles. The targeting strategies were compared with respect to participant characteristics. Univariate and multivariate analyses were used to identify factors associated with HPV vaccine uptake. Results: A total of 1161 women participated. The two targeting strategies resulted in significant differences regarding educational status and migrant background. Overall, awareness of HPV was high, but only 53% received at least one vaccine dose. In multivariate analysis, HPV vaccine uptake was independently associated with a physician's recommendation and trust in vaccine effectiveness. Concerns of adverse effects were negatively associated with vaccine uptake. Discussion: Social network recruitment permits fast and convenient access to young people. Sample characteristics can be manipulated by adjusting targeting strategies. There is further need for promoting knowledge of HPV vaccination among young women. Physicians have a major role in the vaccination decision-making process of young women. PMID:25483492

  5. Root water uptake model based on water potential gradient with water redistribution via roots: application to coniferous forest site

    NASA Astrophysics Data System (ADS)

    Votrubova, Jana; Vogel, Tomas; Dohnal, Michal; Dusek, Jaromir; Tesar, Miroslav

    2013-04-01

    A simple macroscopic vertically distributed plant root water uptake (RWU) model based on traditional water-potential-gradient formulation (Vogel et al., 2013), in which the uptake rates are directly proportional to the potential gradient and indirectly proportional to the local soil and root resistances to water flow, was tested. This RWU modeling approach was implemented in a one-dimensional dual-continuum model of soil water flow based on Richards' equation and used to simulate soil water distribution changes during a vegetation season at a forest site located in a temperate humid climate of central Europe. The main objectives were to test the ability of the presented RWU model to simulate the observed soil-plant-atmosphere interactions, and to examine the differences between empirical and more physically-based RWU modeling approaches (accommodated in the same soil water flow model). The tested RWU model was capable of simulating both the compensatory root water uptake, in situations when reduced uptake from dry layers was compensated for by increased uptake from wetter layers, and the root-mediated hydraulic redistribution of soil water, contributing to more natural soil moisture distribution throughout the root zone. Comparison of the model results with the sap flow observed reveals some limitations related to the quasi-steady-state assumption for the plant xylem and zero transpiration rates prescribed during nights and precipitation. This stated, the model seems to simulate adequately both the regular nightly hydraulic redistribution, due to reduced night transpiration, and the episodic daytime hydraulic redistribution during wet canopy events. The model results were compared to simulations produced using the semi-empirical RWU model of Feddes. Based on both an improved agreement between the observed and simulated soil water pressure responses to daily variations of transpiration, and a more realistic seasonal distribution of the transpiration rate reduction

  6. The selective dopamine uptake inhibitor, D-84, suppresses cocaine self-administration, but does not occasion cocaine-like levels of generalization.

    PubMed

    Batman, Angela M; Dutta, Aloke K; Reith, Maarten E A; Beardsley, Patrick M

    2010-12-01

    A successful replacement pharmacotherapy for treating cocaine dependency would likely reduce cocaine's abuse, support a low abuse liability, overlap cocaine's subjective effects, and have a long duration of action. Inhibitors with varying selectivity at the dopamine transporter (DAT) have approximated these properties. The objective of the present study was to characterize the behavioural effects of an extremely selective DAT inhibitor, (+) trans-4-(2-Benzhydryloxyethyl)-1-(4-fluorobenzyl) piperadin-3-ol (D-84), a 3-hydroxy substituted piperidine derivative of GBR-12935, for its cocaine-like discriminative stimulus effects, its effects on cocaine self-administration, and for its own self-administration. During cocaine discrimination tests, cocaine occasioned the 10 mg/kg cocaine training stimulus with an ED(50) value of 3.13 (1.54-6.34) mg/kg, and reduced response rates with an ED(50) value of 20.39 (7.24-57.44) mg/kg. D-84 incompletely generalized to the cocaine stimulus occasioning a maximal 76% cocaine-lever responding, while reducing response rates with lower potency than cocaine (ED(50)=30.94 (12.34-77.60) mg/kg). Pretreatment with D-84 (9.6-30.4 mg/kg) significantly (P<0.05) reduced cocaine intake at 17.1 mg/kg D-84 when cocaine was self-administered at 0.5 mg/kg/infusion, and at 30.4 mg/kg D-84 when cocaine was self-administered at 0.1, 0.5 .and 1.0 mg/kg/infusion. During self-administration tests with D-84 (0.1-1 mg/kg/infusion), numbers of infusions significantly exceeded vehicle levels at 0.3 mg/kg/infusion. These results show that D-84 pretreatment can decrease cocaine intake especially when high doses of cocaine are being self-administered. This observation, combined with its incomplete generalization to the cocaine discriminative stimulus and its reported long duration of action, provides a profile consistent with a potential replacement therapy for treating cocaine-abusing patients.

  7. Plant selective uptake of halogenated flame retardants at an e-waste recycling site in southern China.

    PubMed

    Wang, Shaorui; Wang, Yan; Luo, Chunling; Li, Jun; Yin, Hua; Zhang, Gan

    2016-07-01

    The concentrations and homolog patterns of halogenated flame retardants (HFRs) in vegetables grown at an e-waste contaminated site were investigated. Polybrominated diphenyl ethers (PBDEs) were the dominant HFRs in vegetable tissues, with concentrations ranging from 10.3 to 164 ng g(-1) and 1.16-107 ng g(-1) in shoots and roots, respectively, followed by novel brominated flame retardants (NBFRs) and dechlorane plus (DPs). This is an indication that PBDE contamination in vegetables grown around e-waste recycling sites may pose a risk to the local terrestrial ecosystem and residents. In addition, this is the first report on the concentrations and compositions of NBFRs in vegetables around e-waste recycling sites. The HFRs concentrations in vegetables varied greatly with the vegetable species, with the highest concentrations observed in Brassica oleracea var. capitata. Root concentration factors (RCF) decreased with increasing log Kow of HFRs, which indicated that the uptake of HFRs was controlled mainly by log Kow. Dissimilar HFRs profiles in shoots and roots suggested that the uptake and translocation of HFRs by plants were selective, with lower halogenated congeners prone to accumulation in vegetable tissues. Positive relationships between PBDEs and their substitutes were observed in vegetable tissues, suggesting that the replacement of PBDEs by NBFRs has not resulted in an obvious transition in plants within the study area. PMID:27149147

  8. Plant selective uptake of halogenated flame retardants at an e-waste recycling site in southern China.

    PubMed

    Wang, Shaorui; Wang, Yan; Luo, Chunling; Li, Jun; Yin, Hua; Zhang, Gan

    2016-07-01

    The concentrations and homolog patterns of halogenated flame retardants (HFRs) in vegetables grown at an e-waste contaminated site were investigated. Polybrominated diphenyl ethers (PBDEs) were the dominant HFRs in vegetable tissues, with concentrations ranging from 10.3 to 164 ng g(-1) and 1.16-107 ng g(-1) in shoots and roots, respectively, followed by novel brominated flame retardants (NBFRs) and dechlorane plus (DPs). This is an indication that PBDE contamination in vegetables grown around e-waste recycling sites may pose a risk to the local terrestrial ecosystem and residents. In addition, this is the first report on the concentrations and compositions of NBFRs in vegetables around e-waste recycling sites. The HFRs concentrations in vegetables varied greatly with the vegetable species, with the highest concentrations observed in Brassica oleracea var. capitata. Root concentration factors (RCF) decreased with increasing log Kow of HFRs, which indicated that the uptake of HFRs was controlled mainly by log Kow. Dissimilar HFRs profiles in shoots and roots suggested that the uptake and translocation of HFRs by plants were selective, with lower halogenated congeners prone to accumulation in vegetable tissues. Positive relationships between PBDEs and their substitutes were observed in vegetable tissues, suggesting that the replacement of PBDEs by NBFRs has not resulted in an obvious transition in plants within the study area.

  9. Contribution of vesicular and cytosolic dopamine to the increased striatal dopamine efflux elicited by intrastriatal injection of SKF38393.

    PubMed

    Saigusa, Tadashi; Aono, Yuri; Sekino, Reiko; Uchida, Takuya; Takada, Koji; Oi, Yoshiyuki; Koshikawa, Noriaki; Cools, Alexander R

    2009-12-10

    Like dexamphetamine, SKF38393 induces an increase in striatal dopamine efflux which is insensitive for tetrodotoxin, Ca(2+) independent and prevented by a dopamine transporter inhibitor. The dexamphetamine-induced striatal dopamine efflux originates from both the reserpine-sensitive vesicular dopamine pool and the alpha-methyl-para-tyrosine-sensitive cytosolic dopamine pool. Given the similarities between dexamphetamine and SKF38393, we hypothesized that both types of pool also contribute to the striatally applied SKF38393-induced dopamine efflux. Using in vivo microdialysis technique, we analysed the contribution of these pools to the SKF38393-induced striatal dopamine efflux in freely moving rats. The increase of dopamine efflux induced by 1.5 microg SKF38393 was largely prevented by either reserpine (5mg/kg i.p., given 24h earlier) or alpha-methyl-para-tyrosine (250 mg/kg i.p., given 2h earlier), showing that both the vesicular dopamine pool and the cytosolic dopamine pool contribute to the SKF38393-induced increase in striatal dopamine efflux. The sum of the amounts of dopamine that was sensitive to either reserpine or alpha-methyl-para-tyrosine, was greater than 100%, namely 137.6% of the basal dopamine level and 143.9% of the SKF38393-induced dopamine level, suggesting that striatally applied SKF38393 promotes the redistribution of dopamine from vesicles to the cytosol, and vice versa. The finding that the combined treatment of reserpine and alpha-methyl-para-tyrosine only inhibited the SKF38393-induced striatal dopamine efflux till 86.0% of the control, is ascribed to the notion that SKF38393 can also inhibit the re-uptake of dopamine. The latter conclusion has far-reaching consequences for studies in which the effects of SKF38393 are simply ascribed to its dopamine D1 receptor stimulation capacity.

  10. Cellular sites of estrogen and antiestrogen uptake, retention and action: comparative autoradiographic studies in the immature rat uterus

    SciTech Connect

    Ennis, B.W.

    1987-01-01

    This purpose of this study is to clarify the mechanism of action of antiestrogens: agents used for treating breast cancer and as probes for studying the mechanisms of action of estrogen. Nuclear uptake and retention of estrogen and antiestrogen were determined in the different cell types of the immature rat uterus, by quantitative autoradiography, after an injection of tritiated hydroxytamoxifen ((/sup 3/H)TAM(OH)) or tritiated estradiol ((/sup 3/H)E/sub 2/). The effect of TAM(OH) and E/sub 2/ on progesterone receptor content was assessed in the different cell types by determining nuclear uptake of the synthetic progestin (/sup 3/H)Org 2058. The results indicate that antiestrogen and estrogen localize to nuclei of the same uterine cell types, but that this nuclear uptake differs among the uterine tissue compartments, that antiestrogen is taken up considerably slower and retained longer than estrogen and that antiestrogen and estrogen differentially affect progesterone receptor content in the different cell types. The results further suggest that antiestrogen-specific binding sites exist in the cytoplasm of uterine luminal epithelium.

  11. Site-Specific Radioiodination of HER2-Targeting Affibody Molecules using 4-Iodophenethylmaleimide Decreases Renal Uptake of Radioactivity

    PubMed Central

    Strand, Joanna; Nordeman, Patrik; Honarvar, Hadis; Altai, Mohamed; Orlova, Anna; Larhed, Mats; Tolmachev, Vladimir

    2015-01-01

    Affibody molecules are small scaffold-based affinity proteins with promising properties as probes for radionuclide-based molecular imaging. However, a high reabsorption of radiolabeled Affibody molecules in kidneys is an issue. We have shown that the use of 125I-3-iodo-((4-hydroxyphenyl)ethyl)maleimide (IHPEM) for site-specific labeling of cysteine-containing Affibody molecules provides high tumor uptake but low radioactivity retention in kidneys. We hypothesized that the use of 4-iodophenethylmaleimide (IPEM) would further reduce renal retention of radioactivity because of higher lipophilicity of radiometabolites. An anti-human epidermal growth factor receptor type 2 (HER2) Affibody molecule (ZHER2:2395) was labeled using 125I-IPEM with an overall yield of 45±3 %. 125I-IPEM-ZHER2:2395 bound specifically to HER2-expressing human ovarian carcinoma cells (SKOV-3 cell line). In NMRI mice, the renal uptake of 125I-IPEM-ZHER2:2395 (24±2 and 5.7±0.3 % IA g−1at 1 and 4 h after injection, respectively) was significantly lower than uptake of 125I-IHPEM-ZHER2:2395 (50±8 and 12±2 % IA g−1at 1 and 4 h after injection, respectively). In conclusion, the use of a more lipophilic linker for the radioiodination of Affibody molecules reduces renal radioactivity. PMID:25969816

  12. Selective labeling of serotonin uptake sites in rat brain by (/sup 3/H)citalopram contrasted to labeling of multiple sites by (/sup 3/H)imipramine

    SciTech Connect

    D'Amato, R.J.; Largent, B.L.; Snowman, A.M.; Snyder, S.H.

    1987-07-01

    Citalopram is a potent and selective inhibitor of neuronal serotonin uptake. In rat brain membranes (/sup 3/H)citalopram demonstrates saturable and reversible binding with a KD of 0.8 nM and a maximal number of binding sites (Bmax) of 570 fmol/mg of protein. The drug specificity for (/sup 3/H)citalopram binding and synaptosomal serotonin uptake are closely correlated. Inhibition of (/sup 3/H)citalopram binding by both serotonin and imipramine is consistent with a competitive interaction in both equilibrium and kinetic analyses. The autoradiographic pattern of (/sup 3/H)citalopram binding sites closely resembles the distribution of serotonin. By contrast, detailed equilibrium-saturation analysis of (/sup 3/H)imipramine binding reveals two binding components, i.e., high affinity (KD = 9 nM, Bmax = 420 fmol/mg of protein) and low affinity (KD = 553 nM, Bmax = 8560 fmol/mg of protein) sites. Specific (/sup 3/H)imipramine binding, defined as the binding inhibited by 100 microM desipramine, is displaced only partially by serotonin. Various studies reveal that the serotonin-sensitive portion of binding corresponds to the high affinity sites of (/sup 3/H)imipramine binding whereas the serotonin-insensitive binding corresponds to the low affinity sites. Lesioning of serotonin neurons with p-chloroamphetamine causes a large decrease in (/sup 3/H)citalopram and serotonin-sensitive (/sup 3/H)imipramine binding with only a small effect on serotonin-insensitive (/sup 3/H)imipramine binding. The dissociation rate of (/sup 3/H)imipramine or (/sup 3/H)citalopram is not altered by citalopram, imipramine or serotonin up to concentrations of 10 microM. The regional distribution of serotonin sensitive (/sup 3/H)imipramine high affinity binding sites closely resembles that of (/sup 3/H)citalopram binding.

  13. Uptake of gamma-aminobutyric acid and L-glutamic acid by synaptosomes from postmortem human cerebral cortex: multiple sites, sodium dependence and effect of tissue preparation.

    PubMed

    Dodd, P R; Watson, W E; Morrison, M M; Johnston, G A; Bird, E D; Cowburn, R F; Hardy, J A

    1989-06-26

    The uptake of gamma-aminobutyric acid (GABA) and L-glutamic acid by synaptosomes prepared from frozen postmortem human brain was shown to be effected via distinct high and low affinity sites. At approximately 17 h postmortem delay, the kinetic parameters for GABA uptake were: high affinity site, Km 7.1 +/- 2.5 microM, Vmax 18.7 +/- 4.8 nmol.min-1 per 100 mg protein; low affinity site, Km 2 +/- 1 mM, Vmax 425 +/- 250 nmol.min-1 per 100 mg protein (means +/- S.E.M., n = 13). Kinetic parameters for L-glutamate uptake were: high affinity site, Km 7.5 +/- 1.0 microM, Vmax 85 +/- 8 nmol.min-1 per 100 mg protein; low affinity site, Km 1.8 +/- 1.2 mM. Vmax 780 +/- 175 nmol.min-1 per 100 mg protein (n = 11). A detailed kinetic analysis of high affinity GABA uptake was performed over a range of sodium ion concentrations. The results were consistent with a coupling ratio of one Na+ ion to one GABA molecule; a similar result was found with rat brain synaptosomes. However, rat and human synaptosomes differed in the degree to which the substrate affinity of the high affinity GABA uptake site varied with decreasing Na+ ion concentration. High affinity GABA uptake was markedly affected by the method used to freeze and divide the tissue, but did not vary greatly in different cortical regions. There was some decline of high affinity GABA uptake activity with postmortem delay, apparently due to a loss of sites rather than a change in site affinity.

  14. A comparison of 90Sr and 137Cs uptake in plants via three pathways at two Chernobyl-contaminated sites.

    PubMed

    Malek, M A; Hinton, T G; Webb, S B

    2002-01-01

    Foliar absorption of resuspended 90Sr, root uptake and contamination adhering to leaf surfaces (i.e. soil loading) were compared at two Chernobyl-contaminated sites, Chistogalovka and Polesskoye. Although foliar absorption of resuspended 90Sr was quantifiable, its contribution amounted to less than 10% of the plants' total, above-ground contamination. Root uptake was 200 times greater than foliar absorption at the near-field site of Chistogalovka and eight times greater at Polesskoye, where the fallout consisted of the more soluble condensation-type, rather than fuel particles. Strontium's bioavailability exceeded that of 137Cs (analyzed in the same plants) by orders of magnitude when compared using concentration ratios. Simplistic, cumulative effective dose calculations for humans ingesting 90Sr- and 137Cs-contaminated plants revealed that the dose at Chistogalovka was greater from 90Sr (185 mSv vs. 3 mSv from 137Cs), while at Polesskoye the dose from 137Cs (66 mSv) was 30 times greater than from 90Sr (2 mSv). PMID:11814162

  15. De novo mutation in the dopamine transporter gene associates dopamine dysfunction with autism spectrum disorder

    PubMed Central

    Hamilton, Peter J.; Campbell, Nicholas G.; Sharma, Shruti; Erreger, Kevin; Hansen, Freja Herborg; Saunders, Christine; Belovich, Andrea N.; Sahai, Michelle A.; Cook, Edwin H.; Gether, Ulrik; Mchaourab, Hassane S.; Matthies, Heinrich J.G.; Sutcliffe, James S.; Galli, Aurelio

    2014-01-01

    De novo genetic variation is an important class of risk factors for autism spectrum disorder (ASD). Recently, whole exome sequencing of ASD families has identified a novel de novo missense mutation in the human dopamine (DA) transporter (hDAT) gene, which results in a Thr to Met substitution at site 356 (hDAT T356M). The dopamine transporter (DAT) is a presynaptic membrane protein that regulates dopaminergic tone in the central nervous system by mediating the high-affinity re-uptake of synaptically released DA, making it a crucial regulator of DA homeostasis. Here, we report the first functional, structural, and behavioral characterization of an ASD-associated de novo mutation in the hDAT. We demonstrate that the hDAT T356M displays anomalous function, characterized as a persistent reverse transport of DA (substrate efflux). Importantly, in the bacterial homolog leucine transporter, substitution of A289 (the homologous site to T356) with a Met promotes an outward-facing conformation upon substrate binding. In the substrate-bound state, an outward-facing transporter conformation is a required for substrate efflux. In Drosophila melanogaster, expression of hDAT T356M in DA neurons lacking Drosophila DAT leads to hyperlocomotion, a trait associated with DA dysfunction and ASD. Taken together, our findings demonstrate that alterations in DA homeostasis, mediated by aberrant DAT function, may confer risk for ASD and related neuropsychiatric conditions. PMID:23979605

  16. Increased expression of the dopamine transporter leads to loss of dopamine neurons, oxidative stress and l-DOPA reversible motor deficits.

    PubMed

    Masoud, S T; Vecchio, L M; Bergeron, Y; Hossain, M M; Nguyen, L T; Bermejo, M K; Kile, B; Sotnikova, T D; Siesser, W B; Gainetdinov, R R; Wightman, R M; Caron, M G; Richardson, J R; Miller, G W; Ramsey, A J; Cyr, M; Salahpour, A

    2015-02-01

    The dopamine transporter is a key protein responsible for regulating dopamine homeostasis. Its function is to transport dopamine from the extracellular space into the presynaptic neuron. Studies have suggested that accumulation of dopamine in the cytosol can trigger oxidative stress and neurotoxicity. Previously, ectopic expression of the dopamine transporter was shown to cause damage in non-dopaminergic neurons due to their inability to handle cytosolic dopamine. However, it is unknown whether increasing dopamine transporter activity will be detrimental to dopamine neurons that are inherently capable of storing and degrading dopamine. To address this issue, we characterized transgenic mice that over-express the dopamine transporter selectively in dopamine neurons. We report that dopamine transporter over-expressing (DAT-tg) mice display spontaneous loss of midbrain dopamine neurons that is accompanied by increases in oxidative stress markers, 5-S-cysteinyl-dopamine and 5-S-cysteinyl-DOPAC. In addition, metabolite-to-dopamine ratios are increased and VMAT2 protein expression is decreased in the striatum of these animals. Furthermore, DAT-tg mice also show fine motor deficits on challenging beam traversal that are reversed with l-DOPA treatment. Collectively, our findings demonstrate that even in neurons that routinely handle dopamine, increased uptake of this neurotransmitter through the dopamine transporter results in oxidative damage, neuronal loss and l-DOPA reversible motor deficits. In addition, DAT over-expressing animals are highly sensitive to MPTP-induced neurotoxicity. The effects of increased dopamine uptake in these transgenic mice could shed light on the unique vulnerability of dopamine neurons in Parkinson's disease.

  17. Characterization of sulpipride-displaceable sup 3 H-YM-09151-2 binding sites in rat frontal cortex and the effects of subchronic treatment with haloperidol on cortical D-2 dopamine receptors

    SciTech Connect

    Kazawa, Tetsushi; Higuchi, Teruhiko National Institute of Neuroscience, Tokyo ); Mikuni, Masahiko; Takahshi, Kiyohisa ); Arai, Ichiro; Yamauchi, Toshio )

    1990-01-01

    We investigated the pharmacological properties of the sulpiride-displaceable binding sites labeled by {sup 3}H-YM-09151-2 in rat frontal cortex, compared to those in striatum. The IC{sub 50} value of ketanserin was 486 nM, which was apparently different from its affinity for the 5HT-2 receptor. Various dopamine antagonists showed almost the same inhibitory effects for binding site in frontal cortex and striatum. Sulpiride-displaceable {sup 3}H-YM-09151-2 binding sites were considered to be D-2 dopamine receptors. After subchronic treatment with haloperidol, the D-2 receptor density of frontal cortex increased to the same extent as striatum without significant change in apparent affinity.

  18. How does angiotensin II increase cardiac dopamine-beta-hydroxylation?

    PubMed

    Chevillard, C; Duchene, N; Alexandre, J M

    1975-03-01

    The potent accelerating effect of angiotensin II (Ang II) on caridac dopamine beta-hydroxylation was studied on slices of rat heart. Ang II did not affect the kinetics of beta-hydroxylation but it increased the axonal uptake of dopamine, and, concomitant with the acceleration of biosynthesis, it enhanced the accumulation of dopamine into tissue. Puromycin, in contrast to actinomycin D, antagonized the stimulation of dopamine beta-hydroxylation by Ang II, but did not suppress the rise in cardiac dopamine. Therefore, to promote the acceleration of dopamine beta-hydroxylation, (i) the rise in tissue dopamine available for conversion appeared to be insufficient, (ii) the formation of new proteins by activation of traduction seemed to constitute the basic mechanism of Ang II action.

  19. The cell pole: the site of cross talk between the DNA uptake and genetic recombination machinery.

    PubMed

    Kidane, Dawit; Ayora, Silvia; Sweasy, Joann B; Graumann, Peter L; Alonso, Juan C

    2012-01-01

    Natural transformation is a programmed mechanism characterized by binding of free double-stranded (ds) DNA from the environment to the cell pole in rod-shaped bacteria. In Bacillus subtilis some competence proteins, which process the dsDNA and translocate single-stranded (ss) DNA into the cytosol, recruit a set of recombination proteins mainly to one of the cell poles. A subset of single-stranded binding proteins, working as "guardians", protects ssDNA from degradation and limit the RecA recombinase loading. Then, the "mediators" overcome the inhibitory role of guardians, and recruit RecA onto ssDNA. A RecA·ssDNA filament searches for homology on the chromosome and, in a process that is controlled by "modulators", catalyzes strand invasion with the generation of a displacement loop (D-loop). A D-loop resolvase or "resolver" cleaves this intermediate, limited DNA replication restores missing information and a DNA ligase seals the DNA ends. However, if any step fails, the "rescuers" will repair the broken end to rescue chromosomal transformation. If the ssDNA does not share homology with resident DNA, but it contains information for autonomous replication, guardian and mediator proteins catalyze plasmid establishment after inhibition of RecA. DNA replication and ligation reconstitute the molecule (plasmid transformation). In this review, the interacting network that leads to a cross talk between proteins of the uptake and genetic recombination machinery will be placed into prospective.

  20. Beta-test Results for an HPV Information Web site: GoHealthyGirls.org – Increasing HPV Vaccine Uptake in the United States

    PubMed Central

    Nodulman, Jessica A.; Kong, Alberta S.; Wheeler, Cosette M.; Buller, David B.; Woodall, W. Gill

    2014-01-01

    A web site, GoHealthyGirls, was developed to educate and inform parents and their adolescent daughters about human papillomavirus (HPV) and HPV vaccines. This article provides an overview of web site development and content followed by the results of a beta-test of the web site. 63 New Mexican parents of adolescent girls tested the site. Results indicated that GoHealthyGirls was a functioning and appealing web site. During this brief educational intervention, findings suggest that the web site has the potential to increase HPV vaccine uptake. This research supports the Internet as a valuable channel to disseminate health education and information to diverse populations. PMID:25221442

  1. Improved techniques for examining rapid dopamine signaling with iontophoresis.

    PubMed

    Herr, Natalie Rios; Wightman, Robert Mark

    2013-01-01

    Dopamine is a neurotransmitter that is utilized in brain circuits associated with reward processing and motor activity. Advances in microelectrode techniques and cyclic voltammetry have enabled its extracellular concentration fluctuations to be examined on a subsecond time scale in the brain of anesthetized and freely moving animals. The microelectrodes can be attached to micropipettes that allow local drug delivery at the site of measurement. Drugs that inhibit dopamine uptake or its autoreceptors can be evaluated while only affecting the brain region directly adjacent to the electrode. The drugs are ejected by iontophoresis in which an electrical current forces the movement of molecules by a combination of electrical migration and electroosmosis. Using electroactive tracer molecules, the amount ejected can be measured with cyclic voltammetry. In this review we will give an introduction to the basic principles of iontophoresis, including a historical account on the development of iontophoresis. It will also include an overview of the use of iontophoresis to study neurotransmission of dopamine in the rat brain. It will close by summarizing the advantages of iontophoresis and how the development of quantitative iontophoresis will facilitate future studies.

  2. The cell pole: The site of cross talk between the DNA uptake and genetic recombination machinery

    PubMed Central

    Kidane, Dawit; Ayora, Silvia; Sweasy, Joann; Graumann, Peter L.; Alonso, Juan C.

    2012-01-01

    Natural transformation is a programmed mechanism characterized by binding of free double-stranded (ds) DNA from the environment to the cell pole in rod-shaped bacteria. In Bacillus subtilis some competence proteins, which process the dsDNA and translocate single-stranded (ss) DNA into the cytosol, recruit a set of recombination proteins mainly to one of the cell poles. A subset of single-stranded binding proteins, working as “guardians”, protect ssDNA from degradation and limit the RecA recombinase loading. Then, the “mediators” overcome the inhibitory role of guardians, and recruit RecA onto ssDNA. A RecA·ssDNA filament searches for homology on the chromosome and, in a process that is controlled by “modulators”, catalyzes strand invasion with the generation of a displacement loop (D-loop). A D-loop resolvase or “resolver” cleaves this intermediate, limited DNA replication restores missing information and a DNA ligase seals the DNA ends. However, if any step fails, the “rescuers” will repair the broken end to rescue chromosomal transformation. If the ssDNA does not share homology with resident DNA, but it contains information for autonomous replication, guardian and mediator proteins catalyze plasmid establishment after inhibition of RecA. DNA replication and ligation reconstitute the molecule (plasmid transformation). In this review, the interacting network that leads to a cross talk between proteins of the uptake and genetic recombination machinery will be placed into prospective. PMID:23046409

  3. Kinetic and e.p.r. studies of cyanide and azide binding to the copper sites of dopamine (3,4-dihydroxyphenethylamine) beta-mono-oxygenase.

    PubMed Central

    Blackburn, N J; Collison, D; Sutton, J; Mabbs, F E

    1984-01-01

    The kinetics of inhibition of dopamine (3,4-dihydroxyphenethylamine) beta-mono-oxygenase by cyanide (CN-) and azide (N3-) ions have been investigated by using steady-state methods. Both anions show complex non-competitive-inhibition patterns with respect to ascorbate, suggestive of anion binding at two different sites on the oxidized enzyme. To further investigate this finding, e.p.r. titrations of CN- and N3- binding to the 63Cu-reconstituted enzyme were carried out. Addition of approx. 2 equiv. of CN- to copper elicits a new signal with g = 2.217, g = 2.025, A = 17.0 mT characteristic of a copper (II)-cyano complex. Simulations show that this signal accounts for half the copper (II) in the enzyme. The remainder of the enzyme-bound copper is expressed by a signal close to, but not identical with, that of native enzyme. Further addition of CN- induces a simultaneous decrease in intensity of both of these signals so that their 1:1 ratio is maintained. Binding of N3-, on the other hand, changes the e.p.r. spectrum to a form different from either that of the native or CN- -treated enzyme, and integrates to 100% of the copper in the enzyme (g = 2.252, g = 2.050, A = 16.5 mT). Resolved superhyperfine structure is apparent in the g region. N3- binding is also accompanied by the appearance of a broad charge-transfer band centred at 387 nm. Neither 9 nor 35 GHz e.p.r. spectra show evidence for more than one (non-interacting) species of Cu(II) in native enzyme and N3- derivatives. The binding and reactivity of CN-, on the other hand, argues against independent copper sites in the enzyme. PMID:6331417

  4. 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.

  5. 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. PMID:27035941

  6. Uptake of Human Papillomavirus Vaccine Among Adolescent Males and Females: Immunization Information System Sentinel Sites, 2009–2012

    PubMed Central

    Cullen, Karen A.; Stokley, Shannon; Markowitz, Lauri E.

    2015-01-01

    Objective The Advisory Committee on Immunization Practices (ACIP) has recommended routine human papillomavirus (HPV) vaccination at age 11 or 12 years for girls since 2006 and for boys since 2011. We sought to describe adolescent HPV vaccination coverage, doses administered from 2009 to 2012, and age at first vaccination by sex. Methods Aggregate data were analyzed from 8 Immunization Information System sentinel sites on HPV vaccinations in children and adolescents aged 11 to 12 years, 13 to 15 years, and 16 to 18 years. Vaccination coverage by age group was reported for 2009 to 2012, and weekly doses administered were determined. Age at first HPV vaccination was calculated for girls in 2007 and 2011 and for boys in 2011. Results This analysis included data on 2.9 million adolescents aged 11 to 18 years. There were small increases in coverage for girls, with receipt of ≥1 dose of HPV vaccine reaching 27.1% of ages 11 to 12, 47.9% of ages 13 to 15, and 57.1% of ages 16 to 18 by December 31, 2012. Uptake of ≥1 dose in boys reached ~18% for all age groups. Doses administered showed seasonal variation, with highest uptake before back to school among girls and steady increases in boys after the 2009 ACIP recommendation for permissive use. Doses administered to boys surpassed those administered to girls by September 2012. Among vaccinated girls, more received vaccine at the recommended age of 11 to 12 years in 2011 (74.2%) compared to 2007 (9.9%). In 2011, 27.3% of vaccinated boys received their first dose at age 11 to 12 years. Conclusions HPV vaccination coverage increased among adolescents between 2009 and 2012. However, increases among girls were small, and coverage for boys and girls remained below target levels. PMID:24954170

  7. Presence and Function of Dopamine Transporter (DAT) in Stallion Sperm: Dopamine Modulates Sperm Motility and Acrosomal Integrity

    PubMed Central

    Covarrubias, Alejandra A.; Rodríguez-Gil, Joan Enric; Ramírez-Reveco, Alfredo; Concha, Ilona I.

    2014-01-01

    Dopamine is a catecholamine with multiple physiological functions, playing a key role in nervous system; however its participation in reproductive processes and sperm physiology is controversial. High dopamine concentrations have been reported in different portions of the feminine and masculine reproductive tract, although the role fulfilled by this catecholamine in reproductive physiology is as yet unknown. We have previously shown that dopamine type 2 receptor is functional in boar sperm, suggesting that dopamine acts as a physiological modulator of sperm viability, capacitation and motility. In the present study, using immunodetection methods, we revealed the presence of several proteins important for the dopamine uptake and signalling in mammalian sperm, specifically monoamine transporters as dopamine (DAT), serotonin (SERT) and norepinephrine (NET) transporters in equine sperm. We also demonstrated for the first time in equine sperm a functional dopamine transporter using 4-[4-(Dimethylamino)styryl]-N-methylpyridinium iodide (ASP+), as substrate. In addition, we also showed that dopamine (1 mM) treatment in vitro, does not affect sperm viability but decreases total and progressive sperm motility. This effect is reversed by blocking the dopamine transporter with the selective inhibitor vanoxerine (GBR12909) and non-selective inhibitors of dopamine reuptake such as nomifensine and bupropion. The effect of dopamine in sperm physiology was evaluated and we demonstrated that acrosome integrity and thyrosine phosphorylation in equine sperm is significantly reduced at high concentrations of this catecholamine. In summary, our results revealed the presence of monoamine transporter DAT, NET and SERT in equine sperm, and that the dopamine uptake by DAT can regulate sperm function, specifically acrosomal integrity and sperm motility. PMID:25402186

  8. Synaptic vesicles in electromotoneurones. I. Axonal transport, site of transmitter uptake and processing of a core proteoglycan during maturation.

    PubMed Central

    Kiene, M L; Stadler, H

    1987-01-01

    We were able by using an in vivo pulse-label technique to trace part of the life cycle of a secretory organelle, the acetylcholine-storing synaptic vesicle from electromotoneurones of Torpedo marmorata. This technique uses [35S]sulphate incorporation into the cell bodies of the electromotoneurones which results in radioactive labelling of a synaptic vesicle heparansulphate proteoglycan--a major core component. Vesicles are anterogradely transported in the axons at a fast rate as 'empty' organelles (VP0 population). In the nerve terminal, maturation of the granule to a population (VP1) fully charged with acetylcholine and ATP occurs. Finally after a longer time interval a change to a third population (VP2) is observed. This population is reduced in diameter as compared to VP0 and VP1 suggesting, in agreement with earlier reports, that it has undergone exo-endocytosis. The changes from VP0 to VP1 and VP2 are accompanied by a degradation of the core proteoglycan as measured by gel filtration of the 35S-labelled compound. The results show that vesicles are axonally transported as preformed organelles, exist in the neurone at least in three different populations and that the nerve terminal is the major site of transmitter uptake. Images Fig. 1. Fig. 4. Fig. 6. PMID:2444433

  9. AMPHETAMINE AUGMENTS VESICULAR DOPAMINE RELEASE IN THE DORSAL AND VENTRAL STRIATUM THROUGH DIFFERENT MECHANISMS

    PubMed Central

    Avelar, Alicia J.; Juliano, Steven A.; Garris, Paul A.

    2013-01-01

    Amphetamine has well-established actions on presynaptic dopamine signaling, such as inhibiting uptake and degradation, activating synthesis, depleting vesicular stores, and promoting dopamine-transporter reversal and non-exocytotic release. Recent in vivo studies have identified an additional mechanism: augmenting vesicular release. Here we investigated how amphetamine elicits this effect. Our hypothesis was that amphetamine enhances vesicular dopamine release in dorsal and ventral striata by differentially targeting dopamine synthesis and degradation. In urethane-anesthetized rats, we employed voltammetry to monitor dopamine, electrical stimulation to deplete stores or assess vesicular release and uptake, and pharmacology to isolate degradation and synthesis. While amphetamine increased electrically evoked dopamine levels, inhibited uptake, and up-regulated vesicular release in both striatal sub-regions in controls, this psychostimulant elicited region-specific effects on evoked levels and vesicular release but not uptake in drug treatments. Evoked levels better correlated with vesicular release compared to uptake, supporting enhanced vesicular release as an important amphetamine mechanism. Taken together, these results suggested that amphetamine enhances vesicular release in the dorsal striatum by activating dopamine synthesis and inhibiting dopamine degradation, but targeting an alternative mechanism in the ventral striatum. Region-distinct activation of vesicular dopamine release highlights complex cellular actions of amphetamine and may have implications for its behavioral effects. PMID:23406303

  10. Amphetamine augments vesicular dopamine release in the dorsal and ventral striatum through different mechanisms.

    PubMed

    Avelar, Alicia J; Juliano, Steven A; Garris, Paul A

    2013-05-01

    Amphetamine has well-established actions on pre-synaptic dopamine signaling, such as inhibiting uptake and degradation, activating synthesis, depleting vesicular stores, and promoting dopamine-transporter reversal and non-exocytotic release. Recent in vivo studies have identified an additional mechanism: augmenting vesicular release. In this study, we investigated how amphetamine elicits this effect. Our hypothesis was that amphetamine enhances vesicular dopamine release in dorsal and ventral striata by differentially targeting dopamine synthesis and degradation. In urethane-anesthetized rats, we employed voltammetry to monitor dopamine, electrical stimulation to deplete stores or assess vesicular release and uptake, and pharmacology to isolate degradation and synthesis. While amphetamine increased electrically evoked dopamine levels, inhibited uptake, and up-regulated vesicular release in both striatal sub-regions in controls, this psychostimulant elicited region-specific effects on evoked levels and vesicular release but not uptake in drug treatments. Evoked levels better correlated with vesicular release compared with uptake, supporting enhanced vesicular release as an important amphetamine mechanism. Taken together, these results suggested that amphetamine enhances vesicular release in the dorsal striatum by activating dopamine synthesis and inhibiting dopamine degradation, but targeting an alternative mechanism in the ventral striatum. Region-distinct activation of vesicular dopamine release highlights complex cellular actions of amphetamine and may have implications for its behavioral effects.

  11. Fluorescent false neurotransmitter reveals functionally silent dopamine vesicle clusters in the striatum

    PubMed Central

    Pereira, Daniela B.; Schmitz, Yvonne; Mészáros, József; Merchant, Paolomi; Hu, Gang; Li, Shu; Henke, Adam; Lizardi-Ortiz, José E.; Karpowicz, Richard J.; Morgenstern, Travis J.; Sonders, Mark S.; Kanter, Ellen; Rodriguez, Pamela C.; Mosharov, Eugene V.; Sames, Dalibor; Sulzer, David

    2016-01-01

    Neurotransmission at dopaminergic synapses has been studied with techniques that provide high temporal resolution but cannot resolve individual synapses. To elucidate the spatial dynamics and heterogeneity of individual dopamine boutons, we developed fluorescent false neurotransmitter 200 (FFN200), a vesicular monoamine transporter 2 (VMAT2) substrate that is the first probe to selectively trace monoamine exocytosis in both neuronal cell culture and brain tissue. By monitoring electrically-evoked Ca2+ transients with GCaMP3 and FFN200 release simultaneously, we find that only a small fraction of dopamine boutons that exhibit Ca2+ influx engage in exocytosis, a result confirmed with activity-dependent loading of the endocytic probe FM 1-43. Thus, only a low fraction of striatal dopamine axonal sites with uptake-competent VMAT2 vesicles are capable of transmitter release. This is consistent with the presence of functionally “silent” dopamine vesicle clusters and represents a first report suggestive of presynaptically silent neuromodulatory synapses. PMID:26900925

  12. Water structural changes at the proton uptake site (the Thr46-Asp96 domain) in the L intermediate of bacteriorhodopsin

    SciTech Connect

    Yamazaki, Yoichi; Hatanka, Minoru; Kandori, Hideki

    1995-05-30

    Fourier transform infrared spectra of the L intermediate of light-adapted bacteriorhodopsin were examined for recombinant proteins with amino acid substitutions at Thr46 and Asp96. Two O-H stretching vibrational bands of water, at 3607 and 3577 cm{sup -1}, change into stronger H-bonding states in L of the wild type. Thr46{r_arrow}Val substitution abolished these bands in spite of the fact that [3-{sup 18}O]threonine-labeling did not shift with them indicating that they correspond to coordination of the water with Thr46. The two water bands were restored, although with changed frequencies, by an additional Asp96{r_arrow}Asn substitution in Thr46{r_arrow}Val/Asp96{r_arrow}Asn. A single Asp96{r_arrow}Asn substitution abolished the 3607 cm{sup -1} band. Thus, Asp96 also takes part in structural changes in water. The perturbations of these water molecules in the L intermediate displayed a weak correlation with the ratio of intensity change in the two of vibrational bands of the Schiff base mode at 1312 and 1301 cm{sup -1} and the rate for the deprotonation of the Schiff base at the L-to-M reaction of the photocycle. We find, therefore, that the water molecule sin the cytoplasmic Asp96-Thr46 domain, which comprises the site of proton uptake after formation of the M intermediate, undergo structural changes in the L intermediate already. These changes are transmitted to the extracellular domain and the affect interaction of the Schiff base with Asp 85, that is far removed from this region. 32 refs., 7 figs.

  13. Metal uptake by homegrown vegetables – The relative importance in human health risk assessments at contaminated sites

    SciTech Connect

    Augustsson, Anna L.M.; Uddh-Söderberg, Terese E.; Hogmalm, K. Johan; Filipsson, Monika E.M.

    2015-04-15

    Risk assessments of contaminated land often involve the use of generic bioconcentration factors (BCFs), which express contaminant concentrations in edible plant parts as a function of the concentration in soil, in order to assess the risks associated with consumption of homegrown vegetables. This study aimed to quantify variability in BCFs and evaluate the implications of this variability for human exposure assessments, focusing on cadmium (Cd) and lead (Pb) in lettuce and potatoes sampled around 22 contaminated glassworks sites. In addition, risks associated with measured Cd and Pb concentrations in soil and vegetable samples were characterized and a probabilistic exposure assessment was conducted to estimate the likelihood of local residents exceeding tolerable daily intakes. The results show that concentrations in vegetables were only moderately elevated despite high concentrations in soil, and most samples complied with applicable foodstuff legislation. Still, the daily intake of Cd (but not Pb) was assessed to exceed toxicological thresholds for about a fifth of the study population. Bioconcentration factors were found to vary more than indicated by previous studies, but decreasing BCFs with increasing metal concentrations in the soil can explain why the calculated exposure is only moderately affected by the choice of BCF value when generic soil guideline values are exceeded and the risk may be unacceptable. - Highlights: • Uptake of Cd and Pb by lettuce and potatoes increased with soil contamination. • Consumption of homegrown vegetables may lead to a daily Cd intake above TDIs. • The variability in the calculated BCFs is high when compared to previous studies. • Exposure assessments are most sensitive to the choice of BCFs at low contamination.

  14. Glutamate neurons within the midbrain dopamine regions.

    PubMed

    Morales, M; Root, D H

    2014-12-12

    Midbrain dopamine systems play important roles in Parkinson's disease, schizophrenia, addiction, and depression. The participation of midbrain dopamine systems in diverse clinical contexts suggests these systems are highly complex. Midbrain dopamine regions contain at least three neuronal phenotypes: dopaminergic, GABAergic, and glutamatergic. Here, we review the locations, subtypes, and functions of glutamatergic neurons within midbrain dopamine regions. Vesicular glutamate transporter 2 (VGluT2) mRNA-expressing neurons are observed within each midbrain dopamine system. Within rat retrorubral field (RRF), large populations of VGluT2 neurons are observed throughout its anteroposterior extent. Within rat substantia nigra pars compacta (SNC), VGluT2 neurons are observed centrally and caudally, and are most dense within the laterodorsal subdivision. RRF and SNC rat VGluT2 neurons lack tyrosine hydroxylase (TH), making them an entirely distinct population of neurons from dopaminergic neurons. The rat ventral tegmental area (VTA) contains the most heterogeneous populations of VGluT2 neurons. VGluT2 neurons are found in each VTA subnucleus but are most dense within the anterior midline subnuclei. Some subpopulations of rat VGluT2 neurons co-express TH or glutamic acid decarboxylase (GAD), but most of the VGluT2 neurons lack TH or GAD. Different subsets of rat VGluT2-TH neurons exist based on the presence or absence of vesicular monoamine transporter 2, dopamine transporter, or D2 dopamine receptor. Thus, the capacity by which VGluT2-TH neurons may release dopamine will differ based on their capacity to accumulate vesicular dopamine, uptake extracellular dopamine, or be autoregulated by dopamine. Rat VTA VGluT2 neurons exhibit intrinsic VTA projections and extrinsic projections to the accumbens and to the prefrontal cortex. Mouse VTA VGluT2 neurons project to accumbens shell, prefrontal cortex, ventral pallidum, amygdala, and lateral habenula. Given their molecular

  15. Comparison of modelled and measured ozone concentrations and meteorology for a site in south-west Sweden: implications for ozone uptake calculations.

    PubMed

    Klingberg, Jenny; Danielsson, Helena; Simpson, David; Pleijel, Håkan

    2008-09-01

    Measurements of ground-level ozone concentrations and meteorology (temperature, vapour pressure deficit (VPD), solar radiation) at the monitoring site Ostad (south-west Sweden) were compared to data from the corresponding grid in the EMEP photo-oxidant model for 1997, 1999 and 2000. The influence of synoptic weather on the agreement between model and measurements was studied. Implications of differences between modelled and observed inputs for ozone flux calculations for wheat and potato were investigated. The EMEP model output of ozone, temperature and VPD correlated well with measurements during daytime. Deviations were larger during the night, especially in calm conditions, attributed to local climatological conditions at the monitoring site deviating from average conditions of the grid. These differences did not lead to significant differences in calculated ozone uptake, which was reproduced remarkably well. The uptake calculations were sensitive to errors in the ozone and temperature input data, especially when including a flux threshold.

  16. 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

  17. Dopamine alleviates salt-induced stress in Malus hupehensis.

    PubMed

    Li, Chao; Sun, Xiangkai; Chang, Cong; Jia, Dongfeng; Wei, Zhiwei; Li, Cuiying; Ma, Fengwang

    2015-04-01

    Dopamine mediates many physiological processes in plants. We investigated its role in regulating growth, ion homeostasis and the response to salinity in Malus hupehensis Rehd. Both hydroponics and field-pot experiments were conducted under saline conditions. Salt-stressed plants had reduced growth and a marked decline in their net photosynthetic rates, values for Fv /Fm and chlorophyll contents. However, pretreatment with 100 or 200 μM dopamine significantly alleviated this inhibition and enabled plants to maintain their photosynthetic capacity. In addition to changing stomatal behavior, supplementation with dopamine positively influenced the uptake of K, N, P, S, Cu and Mn ions but had an inhibitory effect on Na and Cl uptake, the balance of which is responsible for managing the response to salinity by Malus plants. Dopamine pretreatment also controlled the burst of hydrogen peroxide, possibly through direct scavenging and by enhancing the activities of antioxidative enzymes and the capacity of the ascorbate-glutathione cycle. We also investigated whether dopamine might regulate salt overly sensitive pathway genes under salinity. Here, MdHKT1, MdNHX1 and MdSOS1 were greatly upregulated in roots and leaves, which possibly contributed to the maintenance of ion homeostasis and, thus, improved salinity resistance in plants exposed earlier to exogenous dopamine. These results support our conclusion that dopamine alleviates salt-induced stress not only at the level of antioxidant defense but also by regulating other mechanisms of ion homeostasis.

  18. 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.

  19. Dopamine, depression and antidepressants.

    PubMed

    Dailly, Eric; Chenu, Franck; Renard, Caroline E; Bourin, Michel

    2004-12-01

    Abstract The relationship between depression and dopamine deficiency in the mesolimbic pathway has been hypothesized for many years. The experimental studies with animal models of depression and the human studies implicate the role of the dopamine system in depression. Not only do dopaminergic receptor agonists, but also antagonists such as olanzapine exhibit antidepressant effects associated with standard antidepressants in patients with treatment-resistant depression. This paradoxical result suggests that further investigations are necessary to understand the role played by dopamine in depression.

  20. Decoding dopamine signaling.

    PubMed

    Bibb, James A

    2005-07-29

    Dopamine is a key neurotransmitter that is important for many physiological functions including motor control, mood, and the reward pathway. In this issue of Cell, the laboratories of Marc Caron and Li-Huei Tsai identify two very different molecules--beta-arrestin 2 and Par-4, respectively--that unexpectedly are involved in dopamine signaling via the D2 receptor. These two new signaling pathways mediate the actions of dopamine on behavior and facilitate crosstalk between different signaling pathways that are activated by binding of dopamine to the D2 receptor.

  1. Biaryl analogues of conformationally constrained tricyclic tropanes as potent and selective norepinephrine reuptake inhibitors: synthesis and evaluation of their uptake inhibition at monoamine transporter sites.

    PubMed

    Zhou, Jia; Zhang, Ao; Kläss, Thomas; Johnson, Kenneth M; Wang, Cheng Z; Ye, Yan Ping; Kozikowski, Alan P

    2003-05-01

    A series of novel conformationally constrained tricyclic tropane derivatives containing a biaryl moiety, (Z)-9-(biarylylmethylene)-7-azatricyclo[4.3.1.0(3,7)]decanes, were synthesized and evaluated for their ability to inhibit reuptake of dopamine (DA), serotonin (5-HT), and norepinephrine (NE) by the DA, 5-HT, and NE transporters. Most of the compounds containing a methoxycarbonyl substituent at C-10 exhibit moderate to high inhibitory activity at the NET but lower activity at the DAT and SERT. Among these new compounds, some potent, NET-selective ligands were identified. The p-methoxy derivative 11a has a K(i) value of 39 nM for uptake inhibition at the NET and moderate to high selectivity over the SERT (100-fold) and the DAT (20-fold). Compound 11f exhibits a remarkable potency (K(i) = 9.7 nM) at the NET and a 25-fold selectivity over both the SERT and the DAT. Analogue 23 containing a thiophene ring as a bioisosteric replacement of the phenyl ring Ar(1) displays a high activity (K(i) = 10.3 nM) for the NET and similar selectivity over the SERT (50-fold) and the DAT (37-fold). The selectivity profile of biaryl analogues differs from that of the monoaryl series, as most members of that series display excellent potency at and selectivity for the SERT (J. Med. Chem. 2002, 45, 1930). This finding suggests that the different shape and size of the lipophilic recognition pocket that encompasses the aryl ring(s) of these tropanes are major determinants of a ligand's transporter activity at either the NET or the SERT. Some of the compounds in this series may also be valuable in sorting out the contribution of the individual transporters to cocaine's reinforcing properties.

  2. D-A and D-2 dopamine receptor function in the rabbit retina: a model for the central nervous system

    SciTech Connect

    Hensler, J.G.

    1987-01-01

    Studies were done investigating the effect of the synaptic concentration of the transmitter DA, modified by changes in the frequency of electrical field stimulation and by the DA uptake inhibitor nomifensine, on the modulation of /sup 3/H-DA release by D-2 DA autoreceptors and by melatonin receptor sites. At lower synaptic concentrations of the transmitter dopamine, D-2 DA receptor agonists were more potent, while antagonists were more potent when the synaptic concentration of transmitter was higher. The potency of melatonin to inhibit DA release was not altered by the frequency of field stimulation of by frequency-dependent changes in the synaptic concentration of the transmitter.

  3. Discovery of drugs to treat cocaine dependence: behavioral and neurochemical effects of atypical dopamine transport inhibitors.

    PubMed

    Tanda, Gianluigi; Newman, Amy H; Katz, Jonathan L

    2009-01-01

    Stimulant drugs acting at the dopamine transporter (DAT), like cocaine, are widely abused, yet effective medical treatments for this abuse have not been found. Analogs of benztropine (BZT) that, like cocaine, act at the DAT have effects that differ from cocaine and in some situations block the behavioral, neurochemical, and reinforcing actions of cocaine. Neurochemical studies of dopamine levels in brain and behavioral studies have demonstrated that BZT analogs have a relatively slow onset and reduced maximal effects compared to cocaine. Pharmacokinetic studies, however, indicated that the BZT analogs rapidly access the brain at concentrations above their in vitro binding affinities, while binding in vivo demonstrates apparent association rates for BZT analogs lower than that for cocaine. Additionally, the off-target effects of these compounds do not fully explain their differences from cocaine. Initial structure-activity studies indicated that BZT analogs bind to DAT differently from cocaine and these differences have been supported by site-directed mutagenesis studies of the DAT. In addition, BZT analog-mediated inhibition of uptake was more resistant to mutations producing inward conformational DAT changes than cocaine analogs. The BZT analogs have provided new insights into the relation between the molecular and behavioral actions of cocaine and the diversity of effects produced by dopamine transport inhibitors. Novel interactions of BZT analogs with the DAT suggest that these drugs may have a pharmacology that would be useful in their development as treatments for cocaine abuse.

  4. Contaminant Uptake and Demography of the Loggerhead Shrike (Lanius ludovicianus) at the Lawrence Livermore National Laboratory, Site 300

    SciTech Connect

    van Hattem, M G; Santolo, G

    2005-02-23

    Concentrations of eleven potential environmental contaminants (metals) in the blood and retrice feathers of fledged-Hatch Year and adult loggerhead shrikes (Lanius ludovicianus) were examined at Lawrence Livermore National Laboratory's Site 300 and a control site, in San Joaquin and Contra Costa Counties, California. The purpose of this pilot study was to determine, through non-lethal means, if loggerhead shrikes are exposed to metals at Site 300 and whether specific demographic variables (i.e., clutch size, fledgling success, etc.) are affected. Loggerhead shrikes at Site 300 had higher blood concentrations of metals, especially birds on the west side of the site, when compared to control site birds. Metal concentrations in the feathers of control site birds tended to be higher than Site 300 shrikes. Blood concentrations of metals in loggerhead shrikes from both Site 300 and the control site were well below the Most Tolerant Dietary Level (MTDL) for domestic birds for all metals except selenium. Clutch size was similar to other populations but one deformed embryo was discovered in a failed egg. The results of this pilot study suggest further work is needed to understand possible synergistic effects related to other contaminants of concern found at Site 300 and overall population variability.

  5. Dopamine and T cells: dopamine receptors and potent effects on T cells, dopamine production in T cells, and abnormalities in the dopaminergic system in T cells in autoimmune, neurological and psychiatric diseases.

    PubMed

    Levite, M

    2016-01-01

    Dopamine, a principal neurotransmitter, deserves upgrading to 'NeuroImmunotransmitter' thanks to its multiple, direct and powerful effects on most/all immune cells. Dopamine by itself is a potent activator of resting effector T cells (Teffs), via two independent ways: direct Teffs activation, and indirect Teffs activation by suppression of regulatory T cells (Tregs). The review covers the following findings: (i) T cells express functional dopamine receptors (DRs) D1R-D5R, but their level and function are dynamic and context-sensitive, (ii) DR membranal protein levels do not necessarily correlate with DR mRNA levels, (iii) different T cell types/subtypes have different DR levels and composition and different responses to dopamine, (iv) autoimmune and pro-inflammatory T cells and T cell leukaemia/lymphoma also express functional DRs, (v) dopamine (~10(-8) M) activates resting/naive Teffs (CD8(+) >CD4(+) ), (vi) dopamine affects Th1/Th2/Th17 differentiation, (vii) dopamine inhibits already activated Teffs (i.e. T cells that have been already activated by either antigen, mitogen, anti-CD3 antibodies cytokines or other molecules), (viii) dopamine inhibits activated Tregs in an autocrine/paracrine manner. Thus, dopamine 'suppresses the suppressors' and releases the inhibition they exert on Teffs, (ix) dopamine affects intracellular signalling molecules and cascades in T cells (e.g. ERK, Lck, Fyn, NF-κB, KLF2), (x) T cells produce dopamine (Tregs>Teffs), can release dopamine, mainly after activation (by antigen, mitogen, anti-CD3 antibodies, PKC activators or other), uptake extracellular dopamine, and most probably need dopamine, (xi) dopamine is important for antigen-specific interactions between T cells and dendritic cells, (xii) in few autoimmune diseases (e.g. multiple sclerosis/SLE/rheumatoid arthritis), and neurological/psychiatric diseases (e.g. Parkinson disease, Alzheimer's disease, Schizophrenia and Tourette), patient's T cells seem to have abnormal DRs

  6. Quantitative autoradiography of /sup 3/H-nomifensine binding sites in rat brain

    SciTech Connect

    Scatton, B.; Dubois, A.; Dubocovich, M.L.; Zahniser, N.R.; Fage, D.

    1985-03-04

    The distribution of /sup 3/H-nomifensine binding sites in the rat brain has been studied by quantitative autoradiography. The binding of /sup 3/H-nomifensine to caudate putamen sections was saturable, specific, of a highly affinity (Kd = 56 nM) and sodium-dependent. The dopamine uptake inhibitors benztropine, nomifensine, cocaine, bupropion and amfonelic acid were the most potent competitors of /sup 3/H-nomifensine binding to striatal sections. The highest levels of (benztropine-displaceable) /sup 3/H-nomifensine binding sites were found in the caudate-putamen, the olfactory tubercle and the nucleus accumbens. 6-Hydroxy-dopamine-induced lesion of the ascending dopaminergic bundle resulted in a marked decrease in the /sup 3/H-ligand binding in these areas. Moderately high concentrations of the /sup 3/H-ligand were observed in the bed nucleus of the stria terminalis, the anteroventral thalamic nucleus, the cingulate cortex, the lateral septum, the hippocampus, the amygdala, the zona incerta and some hypothalamic nuclei. There were low levels of binding sites in the habenula, the dorsolateral geniculate body, the substantia nigra, the ventral tegmental area and the periaqueductal gray matter. These autoradiographic data are consistent with the hypothesis that /sup 3/H-nomifensine binds primarily to the presynaptic uptake site for dopamine but also labels the norepinephrine uptake site. 33 references, 2 figures, 1 table.

  7. Tianeptine: 5-HT uptake sites and 5-HT(1-7) receptors modulate memory formation in an autoshaping Pavlovian/instrumental task.

    PubMed

    Meneses, Alfredo

    2002-05-01

    Recent studies using invertebrate and mammal species have revealed that, endogenous serotonin (5-hydroxytryptamine, 5-HT) modulates cognitive processes, particularly learning and memory, though, at present, it is unclear the manner, where, and how long 5-HT systems are involved. Hence in this work, an attempt was made to study the effects of 5-HT endogenous on memory formation, using a 5-HT uptake facilitator (tianeptine) and, selective 5-HT(1-7) receptor antagonists to determine whether 5-HT uptake sites and which 5-HT receptors are involved, respectively. Results showed that post-training tianeptine injection enhanced memory consolidation in an autoshaping Pavlovian/instrumental learning task, which has been useful to detect changes on memory formation elicited by drugs or aging. On interaction experiments, ketanserin (5-HT(1D/2A/2C) antagonist) slightly enhanced tianeptine effects, while WAY 100635 (5-HT(1A) antagonist), SB-224289 (5-HT(1B) inverse agonist), SB-200646 (5-HT(2B/2C) antagonist), ondansetron (5-HT(3) antagonist), GR 127487 (5-HT(4) antagonist), Ro 04-6790 (5-HT(6) antagonist), DR 4004 (5-HT(7) antagonist), or fluoxetine (an inhibitor of 5-HT reuptake) blocked the facilitatory tianeptine effect. Notably, together tianeptine and Ro 04-6790 impaired learning consolidation. Moreover, 5-HT depletion completely reversed the tianeptine effect. Tianeptine also normalized an impaired memory elicited by scopolamine (an antimuscarinic) or dizocilpine (non-competitive glutamatergic antagonist), while partially reversed that induced by TFMPP (5-HT(1B/1D/2A-2C/7) agonist/antagonist). Finally, tianeptine-fluoxetine coadministration had no effect on learning consolidation; nevertheless, administration of an acetylcholinesterase inhibitor, phenserine, potentiated subeffective tianeptine or fluoxetine doses. Collectively, these data confirmed that endogenously 5-HT modulates, via uptake sites and 5-HT(1-7) receptors, memory consolidation, and are consistent with the

  8. Siderophore-mediated iron uptake in fluorescent Pseudomonas: characterization of the pyoverdine-receptor binding site of three cross-reacting pyoverdines.

    PubMed

    Meyer, Jean-Marie; Geoffroy, Valérie A; Baysse, Christine; Cornelis, Pierre; Barelmann, Insa; Taraz, Kambiz; Budzikiewicz, Herbert

    2002-01-15

    Two Pseudomonas fluorescens and one Pseudomonas aeruginosa strains, although producing structurally different pyoverdines, demonstrated highly efficient cross-reactions when tested for pyoverdine-mediated iron uptake. A ferripyoverdine receptor-deficient mutant of the P. aeruginosa strain was unable to use any of the three pyoverdines. Moreover, the three strains presented each a specific outer membrane siderophore-receptor pattern. Thus, the capacity of using heterologous pyoverdines was related not to the presence of supplementary specific ferripyoverdine receptors but to the existence within the respective pyoverdine-peptide chains of a common dipeptide motif which should act as the receptor-binding site for the three pyoverdines. Other pyoverdines sharing the same motif but at another position within the peptide chain were not efficient in iron transport, demonstrating the importance of the spatial position of the binding site. PMID:11795869

  9. Pyrethroid pesticide-induced alterations in dopamine transporter function

    PubMed Central

    Elwan, Mohamed A.; Richardson, Jason R.; Guillot, Thomas S.; Caudle, W. Michael; Miller, Gary W.

    2016-01-01

    Parkinson’s disease (PD) is a progressive neurodegenerative disease affecting the nigrostriatal dopaminergic pathway. Several epidemiological studies have demonstrated an association between pesticide exposure and the incidence of PD. Studies from our laboratory and others have demonstrated that certain pesticides increase levels of the dopamine transporter (DAT), an integral component of dopaminergic neurotransmission and a gateway for dopaminergic neurotoxins. Here, we report that repeated exposure (3 injections over 2 weeks) of mice to two commonly used pyrethroid pesticides, deltamethrin (3 mg/kg) and permethrin (0.8 mg/kg), increases DAT-mediated dopamine uptake by 31 and 28%, respectively. Using cells stably expressing DAT, we determined that exposure (10 min) to deltamethrin and permethrin (1 nM–100 μM) had no effect on DAT-mediated dopamine uptake. Extending exposures to both pesticides for 30 min (10 μM) or 24 h (1, 5, and 10 μM) resulted in significant decrease in dopamine uptake. This reduction was not the result of competitive inhibition, loss of DAT protein, or cytotoxicity. However, there was an increase in DNA fragmentation, an index of apoptosis, in cells exhibiting reduced uptake at 30 min and 24 h. These data suggest that up-regulation of DAT by in vivo pyrethroid exposure is an indirect effect and that longer-term exposure of cells results in apoptosis. Since DAT can greatly affect the vulnerability of dopamine neurons to neurotoxicants, up-regulation of DAT by deltamethrin and permethrin may increase the susceptibility of dopamine neurons to toxic insult, which may provide insight into the association between pesticide exposure and PD. PMID:16005927

  10. Pyrethroid pesticide-induced alterations in dopamine transporter function

    SciTech Connect

    Elwan, Mohamed A.; Richardson, Jason R.; Guillot, Thomas S.; Caudle, W. Michael; Miller, Gary W. . E-mail: gary.miller@emory.edu

    2006-03-15

    Parkinson's disease (PD) is a progressive neurodegenerative disease affecting the nigrostriatal dopaminergic pathway. Several epidemiological studies have demonstrated an association between pesticide exposure and the incidence of PD. Studies from our laboratory and others have demonstrated that certain pesticides increase levels of the dopamine transporter (DAT), an integral component of dopaminergic neurotransmission and a gateway for dopaminergic neurotoxins. Here, we report that repeated exposure (3 injections over 2 weeks) of mice to two commonly used pyrethroid pesticides, deltamethrin (3 mg/kg) and permethrin (0.8 mg/kg), increases DAT-mediated dopamine uptake by 31 and 28%, respectively. Using cells stably expressing DAT, we determined that exposure (10 min) to deltamethrin and permethrin (1 nM-100 {mu}M) had no effect on DAT-mediated dopamine uptake. Extending exposures to both pesticides for 30 min (10 {mu}M) or 24 h (1, 5, and 10 {mu}M) resulted in significant decrease in dopamine uptake. This reduction was not the result of competitive inhibition, loss of DAT protein, or cytotoxicity. However, there was an increase in DNA fragmentation, an index of apoptosis, in cells exhibiting reduced uptake at 30 min and 24 h. These data suggest that up-regulation of DAT by in vivo pyrethroid exposure is an indirect effect and that longer-term exposure of cells results in apoptosis. Since DAT can greatly affect the vulnerability of dopamine neurons to neurotoxicants, up-regulation of DAT by deltamethrin and permethrin may increase the susceptibility of dopamine neurons to toxic insult, which may provide insight into the association between pesticide exposure and PD.

  11. Grass species influence on plant N uptake - Determination of atmospheric N deposition to a semi-natural peat bog site using a 15N labelling approach

    NASA Astrophysics Data System (ADS)

    Hurkuck, Miriam; Brümmer, Christian; Spott, Oliver; Flessa, Heinz; Kutsch, Werner L.

    2014-05-01

    Large areas of natural peat bogs in Northwestern Germany have been converted to arable land and were subjected to draining and peat cutting in the past. The few protected peatland areas remaining are affected by high nitrogen (N) deposition. Our study site - a moderately drained raised bog - is surrounded by highly fertilized agricultural land and livestock production. In this study, we used a 15N pool dilution technique called 'Integrated Total Nitrogen Input' (ITNI) to quantify annual deposition of atmospheric N into biomonitoring pots over a two-year period. Since it considers direct N uptake by plants, it was expected to result in higher N input than conventional methods for determination of N deposition (e.g. micrometeorological approaches, bulk N samplers). Using Lolium multiflorum and Eriophorum vaginatum as monitor plants and low, medium and high levels of fertilization, we aimed to simulate increasing N deposition to planted pots and to allocate airborne N after its uptake by the soil-plant system in aboveground biomass, roots and soil. Increasing N fertilization was positively correlated with biomass production of Eriophorum vaginatum, whereas atmospheric plant N uptake decreased and highest airborne N input of 899.8 ± 67.4 µg N d-1 pot-1 was found for low N fertilization. In contrast, Lolium multiflorum showed a clear dependency of N supply on plant N uptake and was highest (688.7 ± 41.4 µg N d-1 pot-1) for highly fertilized vegetation pots. Our results suggest that grass species respond differently to increasing N input. While crop grasses such as Lolium multiflorum take up N according to N availability, species adopted to nutrient-limited conditions like Eriophorum vaginatum show N saturation effects with increasing N supply. Total airborne N input ranged from about 24 to 66 kg N ha-1 yr-1 dependent on the used indicator plant and the amount of added fertilizer. Parallel determination of atmospheric N deposition using a micrometeorological approach

  12. Dopamine Transport Inhibitors Based on GBR12909 and Benztropine as Potential Medications to Treat Cocaine Addiction

    PubMed Central

    Rothman, Richard B.; Baumann, Michael; Prisinzano, Thomas E.; Newman, Amy Hauck

    2008-01-01

    The discovery and development of medications to treat addiction and notably, cocaine addiction, have been frustrated by both the complexity of the disorder and the lack of target validation in human subjects. The dopamine transporter has historically been a primary target for cocaine abuse medication development, but addictive liability and other confounds of such inhibitors of dopamine uptake have limited clinical evaluation and validation. Herein we describe efforts to develop analogues of the dopamine uptake inhibitors GBR 12909 and benztropine that show promising profiles in animal models of cocaine abuse that contrast to that of cocaine. Their unique pharmacological profiles have provided important insights into the reinforcing actions of cocaine and we propose that clinical investigation of novel dopamine uptake inhibitors will facilitate the discovery of cocaine-abuse medications. PMID:17897630

  13. Dopamine triggers heterosynaptic plasticity.

    PubMed

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

    2013-04-17

    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 to the 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 ventral tegmental area 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.

  14. Amphetamine elevates nucleus accumbens dopamine via an action potential-dependent mechanism that is modulated by endocannabinoids.

    PubMed

    Covey, Dan P; Bunner, Kendra D; Schuweiler, Douglas R; Cheer, Joseph F; Garris, Paul A

    2016-06-01

    The reinforcing effects of abused drugs are mediated by their ability to elevate nucleus accumbens dopamine. Amphetamine (AMPH) was historically thought to increase dopamine by an action potential-independent, non-exocytotic type of release called efflux, involving reversal of dopamine transporter function and driven by vesicular dopamine depletion. Growing evidence suggests that AMPH also acts by an action potential-dependent mechanism. Indeed, fast-scan cyclic voltammetry demonstrates that AMPH activates dopamine transients, reward-related phasic signals generated by burst firing of dopamine neurons and dependent on intact vesicular dopamine. Not established for AMPH but indicating a shared mechanism, endocannabinoids facilitate this activation of dopamine transients by broad classes of abused drugs. Here, using fast-scan cyclic voltammetry coupled to pharmacological manipulations in awake rats, we investigated the action potential and endocannabinoid dependence of AMPH-induced elevations in nucleus accumbens dopamine. AMPH increased the frequency, amplitude and duration of transients, which were observed riding on top of slower dopamine increases. Surprisingly, silencing dopamine neuron firing abolished all AMPH-induced dopamine elevations, identifying an action potential-dependent origin. Blocking cannabinoid type 1 receptors prevented AMPH from increasing transient frequency, similar to reported effects on other abused drugs, but not from increasing transient duration and inhibiting dopamine uptake. Thus, AMPH elevates nucleus accumbens dopamine by eliciting transients via cannabinoid type 1 receptors and promoting the summation of temporally coincident transients, made more numerous, larger and wider by AMPH. Collectively, these findings are inconsistent with AMPH eliciting action potential-independent dopamine efflux and vesicular dopamine depletion, and support endocannabinoids facilitating phasic dopamine signalling as a common action in drug reinforcement.

  15. BASAL GANGLIA PATHOLOGY IN SCHIZOPHRENIA: DOPAMINE CONNECTIONS and ANOMALIES

    PubMed Central

    Perez-Costas, Emma; Melendez-Ferro, Miguel; Roberts, Rosalinda C.

    2010-01-01

    Schizophrenia is a severe mental illness that affects 1% of the world population. The disease usually manifests itself in early adulthood with hallucinations, delusions, cognitive and emotional disturbances and disorganized thought and behavior. Dopamine was the first neurotransmitter to be implicated in the disease, and though no longer the only suspect in schizophrenia pathophysiology, it obviously plays an important role. The basal ganglia are the site of most of the dopamine neurons in the brain and the target of antipsychotic drugs. In this review we will start with an overview of basal ganglia anatomy emphasizing dopamine circuitry. Then, we will review the major deficits in dopamine function in schizophrenia, emphasizing the role of excessive dopamine in the basal ganglia and the link to psychosis. PMID:20089137

  16. Central actions of a novel and selective dopamine antagonist

    SciTech Connect

    Schulz, D.W.

    1985-01-01

    Receptors for the neurotransmitter dopamine traditionally have been divided into two subgroups: the D/sub 1/ class, which is linked to the stimulation of adenylate cyclase-activity, and the D/sub 2/ class which is not. There is much evidence suggesting that it is the D/sub 2/ class which is not. There is much evidence suggesting that it is the D/sub 2/ dopamine receptor that mediates the physiological and behavioral actions of dopamine in the intact animal. However, the benzazepine SCH23390 is a dopamine antagonist which has potent behavioral actions while displaying apparent neurochemical selectivity for the D/sub 1/ class of dopamine receptors. The purpose of this dissertation was to (1) confirm and characterize this selectivity, and (2) test certain hypothesis related to possible modes of action of SCH233390. The inhibition of adenylate cyclase by SCH23390 occurred via an action at the dopamine receptor only. A radiolabeled analog of SCH23390 displayed the receptor binding properties of a specific high-affinity ligand, and regional receptor densities were highly correlated with dopamine levels. The subcellular distribution of (/sup 3/H)-SCH23390 binding did not correspond completely with that of dopamine-stimulated adenylate cyclase. The neurochemical potency of SCH23390 as a D/sub 1/ receptor antagonist was preserved following parental administration. A variety of dopamine agonists and antagonists displayed a high correlation between their abilities to compete for (/sup 3/H)-SCH23390 binding in vitro and to act at an adenylate cyclase-linked receptor. Finally, the relative affinities of dopamine and SCH23390 for both D/sub 1/ receptors and (/sup 3/H)-SCH23390 binding sites were comparable. It is concluded that the behavioral effects of SCH23390 are mediated by actions at D/sub 1/ dopamine receptors only, and that the physiological importance of this class of receptors should be reevaluated.

  17. Further studies on conformationally constrained tricyclic tropane analogues and their uptake inhibition at monoamine transporter sites: synthesis of (Z)-9-(substituted arylmethylene)-7-azatricyclo[4.3.1.0(3,7)]decanes as a novel class of serotonin transporter inhibitors.

    PubMed

    Zhang, Ao; Zhou, Guochun; Hoepping, Alexander; Mukhopadhyaya, Jayanta; Johnson, Kenneth M; Zhang, Mei; Kozikowski, Alan P

    2002-04-25

    A novel series of conformationally constrained tricyclic tropane analogues, (Z)-9-(substituted arylmethylene)-7-azatricyclo[4.3.1.0(3,7)]decanes, were prepared, and their abilities to inhibit high-affinity uptake of dopamine (DA), serotonin (5-HT), and norepinephrine (NE) into rat brain nerve endings (synaptosomes) were evaluated. First, a systematic screening of a variety of different substituents on the phenyl ring indicated that the substitution pattern plays an important role in the monoamine transporter activity. Most compounds in this series possessed a very low activity at the DA transporter (DAT) but a good to excellent affinity for the 5-HT transporter (SERT). In the case of para-substituted phenyl analogues, the electronic character of the substituent did not affect uptake inhibition as dramatically as observed in some benztropine analogues. Among these compounds, the 4-bromophenyl and 4-isopropylphenyl analogues 8d and 8j exhibited the highest potency at the SERT with a K(i) value of 10 nM. In the 3,4-disubstituted phenyl series, even more potent and highly selective compounds were discovered. Compound 8o has a K(i) value of 2.3 nM for uptake inhibition at the SERT, a DAT/SERT uptake ratio of 2360, and a NET/SERT uptake ratio of 200. Compound 8p exhibited a K(i) value of 1.8 nM for uptake inhibition at the SERT, a DAT/SERT uptake ratio of 1740, and a NET/SERT uptake ratio of 151. These compounds are 3-4-fold more potent than the antidepressant medication fluoxetine, and the selectivities for SERT over DAT and NET are also better than those of fluoxetine. Second, a variety of functional modifications on the ester moiety were investigated. Substitution by other esters or amides as well as alkenes did not increase potency, while most of the acetates or benzoates (16-21, 23, and 24) and the ketone 28 exhibited significantly improved activity. A good hydrogen-bonding ability of the substituent is believed to be required for high activity. The most potent and

  18. Increasing Healthy Start food and vitamin voucher uptake for low income pregnant women (Early Years Collaborative Leith Pioneer Site)

    PubMed Central

    Mackenzie, Graham; Dougall, Angela

    2016-01-01

    Poverty has a detrimental impact on health and wellbeing. Healthy Start food and vitamin vouchers provide support for low income families across the UK, but at least 25% of eligible women and children miss out. We set out to increase uptake, with an aim of 90% of eligible women and children (n~540 eligible, varying over time) receiving vouchers in the initial team's catchment area by December 2015. Starting with one midwife and one pregnant woman in March 2014 we used the model for improvement to identify ways to improve documentation, sign up, and referral. Weekly data on process measures and monthly data on voucher receipt were plotted on run charts. Comparing medians for January-June 2014 and March-August 2015 there was a 13.3% rise in voucher receipt in Lothian (increase from 313 to 355 women), versus an 8.4% decline for the rest of Scotland (fall from 1688 to 1546 women). Figures varied by team, influenced by staff, family, and area factors. The initial aim proved unrealistic, as signing up a woman for vouchers increases both the numerator and denominator. Accordingly, the percentage uptake has not increased at a regional level (remains at 75%), though the figure for the initiating team (“team 3” in graphs) has increased from 73.0% (January 2014) to 79.0% (November 2015). We have continued testing, achieving recent increases in the number of women referred for welfare rights advice on benefits, tax credits, employment rights, childcare, and debt, securing on average £4,500 per client during 2015/16 (£404k for 89 clients by mid September 2015). This improvement project, part of the Early Years Collaborative in Scotland, has had a measureable impact on pregnant women across Lothian. Success has relied on testing, an electronic maternity record, rapid dissemination of findings through direct engagement with clinical teams, and persistence. Our findings have relevance across the UK, particularly at a time of worsening finances for many families. PMID

  19. Increasing Healthy Start food and vitamin voucher uptake for low income pregnant women (Early Years Collaborative Leith Pioneer Site).

    PubMed

    Mackenzie, Graham; Dougall, Angela

    2016-01-01

    Poverty has a detrimental impact on health and wellbeing. Healthy Start food and vitamin vouchers provide support for low income families across the UK, but at least 25% of eligible women and children miss out. We set out to increase uptake, with an aim of 90% of eligible women and children (n~540 eligible, varying over time) receiving vouchers in the initial team's catchment area by December 2015. Starting with one midwife and one pregnant woman in March 2014 we used the model for improvement to identify ways to improve documentation, sign up, and referral. Weekly data on process measures and monthly data on voucher receipt were plotted on run charts. Comparing medians for January-June 2014 and March-August 2015 there was a 13.3% rise in voucher receipt in Lothian (increase from 313 to 355 women), versus an 8.4% decline for the rest of Scotland (fall from 1688 to 1546 women). Figures varied by team, influenced by staff, family, and area factors. The initial aim proved unrealistic, as signing up a woman for vouchers increases both the numerator and denominator. Accordingly, the percentage uptake has not increased at a regional level (remains at 75%), though the figure for the initiating team ("team 3" in graphs) has increased from 73.0% (January 2014) to 79.0% (November 2015). We have continued testing, achieving recent increases in the number of women referred for welfare rights advice on benefits, tax credits, employment rights, childcare, and debt, securing on average £4,500 per client during 2015/16 (£404k for 89 clients by mid September 2015). This improvement project, part of the Early Years Collaborative in Scotland, has had a measureable impact on pregnant women across Lothian. Success has relied on testing, an electronic maternity record, rapid dissemination of findings through direct engagement with clinical teams, and persistence. Our findings have relevance across the UK, particularly at a time of worsening finances for many families. PMID:27134747

  20. Site-specific conjugation of single domain antibodies to liposomes enhances photosensitizer uptake and photodynamic therapy efficacy

    NASA Astrophysics Data System (ADS)

    Broekgaarden, M.; van Vught, R.; Oliveira, S.; Roovers, R. C.; van Bergen En Henegouwen, P. M. P.; Pieters, R. J.; van Gulik, T. M.; Breukink, E.; Heger, M.

    2016-03-01

    Photodynamic therapy for therapy-resistant cancers will greatly benefit from targeted delivery of tumor photosensitizing agents. In this study, a strategy for the site-specific conjugation of single domain antibodies onto liposomes containing the photosensitizer zinc phthalocyanine was developed and tested.Photodynamic therapy for therapy-resistant cancers will greatly benefit from targeted delivery of tumor photosensitizing agents. In this study, a strategy for the site-specific conjugation of single domain antibodies onto liposomes containing the photosensitizer zinc phthalocyanine was developed and tested. Electronic supplementary information (ESI) available: Materials and methods. See DOI: 10.1039/c6nr00014b

  1. 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; 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).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

  2. 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

  3. Evidence for regional catecholamine uptake and storage sites in the transplanted human heart by positron emission tomography

    SciTech Connect

    Schwaiger, M.; Hutchins, G.D.; Kalff, V.; Rosenspire, K.; Haka, M.S.; Mallette, S.; Deeb, G.M.; Abrams, G.D.; Wieland, D. )

    1991-05-01

    Positron emission tomography in combination with the newly introduced catecholamine analogue ({sup 11}C)hydroxyephedrine (({sup 11}C)HED) enables the noninvasive delineation of sympathetic nerve terminals of the heart. To address the ongoing controversy over possible reinnervation of the human transplant, 5 healthy control subjects and 11 patients were studied after cardiac transplant by this imaging approach. Regional ({sup 11}C)HED retention was compared to regional blood flow as assessed by rubidium-82. Transplant patients were divided into two groups. Group I had recent (less than 1 yr, 4.4 +/- 2.3 mo) surgery, while group II patients underwent cardiac transplantation more than 2 yr before imaging (3.5 +/- 1.3 yr). ({sup 11}C)HED retention paralleled blood flow in normals, but was homogeneously reduced in group I. In contrast, group II patients revealed heterogeneous ({sup 11}C)HED retention, with increased uptake in the proximal anterior and septal wall. Quantitative evaluation of ({sup 11}C)HED retention revealed a 70% reduction in group I and 59% reduction in group II patients (P less than 0.001). In group II patients, ({sup 11}C)HED retention reached 60% of normal in the proximal anterior wall. These data suggest the presence of neuronal tissue in the transplanted human heart, which may reflect regional sympathetic reinnervation.

  4. Assessment of the in vitro binding of JHW 007, a dopamine transport inhibitor that blocks the effects of cocaine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Benztropine (BZT) and its analogues, like cocaine, bind to the dopamine transporter and block dopamine uptake. However, while BZT analogues bind the DAT with high affinity, they generally do not have cocaine-like behavioral effects. JHW 007 is a BZT analogue that displaces [3H]WIN 35,428 from the D...

  5. Cre recombinase-mediated restoration of nigrostriatal dopamine in dopamine-deficient mice reverses hypophagia and bradykinesia.

    PubMed

    Hnasko, Thomas S; Perez, Francisco A; Scouras, Alex D; Stoll, Elizabeth A; Gale, Samuel D; Luquet, Serge; Phillips, Paul E M; Kremer, Eric J; Palmiter, Richard D

    2006-06-01

    A line of dopamine-deficient (DD) mice was generated to allow selective restoration of normal dopamine signaling to specific brain regions. These DD floxed stop (DDfs) mice have a nonfunctional Tyrosine hydroxylase (Th) gene because of insertion of a NeoR gene flanked by lox P sites targeted to the first intron of the Th gene. DDfs mice have trace brain dopamine content, severe hypoactivity, and aphagia, and they die without intervention. However, they can be maintained by daily treatment with l-3,4-dihydroxyphenylalanine (L-dopa). Injection of a canine adenovirus (CAV-2) engineered to express Cre recombinase into the central caudate putamen restores normal Th gene expression to the midbrain dopamine neurons that project there because CAV-2 efficiently transduces axon terminals and is retrogradely transported to neuronal cell bodies. Bilateral injection of Cre recombinase into the central caudate putamen restores feeding and normalizes locomotion in DDfs mice. Analysis of feeding behavior by using lickometer cages revealed that virally rescued DDfs mice are hyperphagic and have modified meal structures compared with control mice. The virally rescued DDfs mice are also hyperactive at night, have reduced motor coordination, and are thigmotactic compared with controls. These results highlight the critical role for dopamine signaling in the dorsal striatum for most dopamine-dependent behaviors but suggest that dopamine signaling in other brain regions is important to fine-tune these behaviors. This approach offers numerous advantages compared with previous models aimed at examining dopamine signaling in discrete dopaminergic circuits.

  6. SITE SITE DISTURBANCE EFFECTS ON A CLAY SOIL UNDER PINUS RADIATA - ROOT BIOMASS, MYCORRHIZAL COLONISATION, 15AMMONIUM UPTAKE, AND FOLIAR NUTRIENT LEVELS

    EPA Science Inventory

    Timber harvesting can result in adverse physical, chemical and biological alterations to soil. The objective of this study was to examine the effects of site disturbance to determine the extent and duration of possible harvesting impacts on soil chemical and biological propertie...

  7. Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules

    PubMed Central

    Davidge, Kelly S; Singh, Sandip; Bowman, Lesley AH; Tinajero-Trejo, Mariana; Carballal, Sebastián; Radi, Rafael; Poole, Robert K; Dikshit, Kanak; Estrin, Dario A; Marti, Marcelo A; Boechi, Leonardo

    2015-01-01

    Mycobacterium tuberculosis, the causative agent of human tuberculosis, has two proteins belonging to the truncated hemoglobin (trHb) family. Mt-trHbN presents well-defined internal hydrophobic tunnels that allow O 2 and •NO to migrate easily from the solvent to the active site, whereas Mt-trHbO possesses tunnels that are partially blocked by a few bulky residues, particularly a tryptophan at position G8. Differential ligand migration rates allow Mt-trHbN to detoxify •NO, a crucial step for pathogen survival once under attack by the immune system, much more efficiently than Mt-trHbO. In order to investigate the differences between these proteins, we performed experimental kinetic measurements, •NO decomposition, as well as molecular dynamics simulations of the wild type Mt-trHbN and two mutants, VG8F and VG8W. These mutations introduce modifications in both tunnel topologies and affect the incoming ligand capacity to displace retained water molecules at the active site. We found that a single mutation allows Mt-trHbN to acquire ligand migration rates comparable to those observed for Mt-trHbO, confirming that ligand migration is regulated by the internal tunnel architecture as well as by water molecules stabilized in the active site. PMID:26478812

  8. Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules.

    PubMed

    Boron, Ignacio; Bustamante, Juan Pablo; Davidge, Kelly S; Singh, Sandip; Bowman, Lesley Ah; Tinajero-Trejo, Mariana; Carballal, Sebastián; Radi, Rafael; Poole, Robert K; Dikshit, Kanak; Estrin, Dario A; Marti, Marcelo A; Boechi, Leonardo

    2015-01-01

    Mycobacterium tuberculosis, the causative agent of human tuberculosis, has two proteins belonging to the truncated hemoglobin (trHb) family. Mt-trHbN presents well-defined internal hydrophobic tunnels that allow O 2 and (•)NO to migrate easily from the solvent to the active site, whereas Mt-trHbO possesses tunnels that are partially blocked by a few bulky residues, particularly a tryptophan at position G8. Differential ligand migration rates allow Mt-trHbN to detoxify (•)NO, a crucial step for pathogen survival once under attack by the immune system, much more efficiently than Mt-trHbO. In order to investigate the differences between these proteins, we performed experimental kinetic measurements, (•)NO decomposition, as well as molecular dynamics simulations of the wild type Mt-trHbN and two mutants, VG8F and VG8W. These mutations introduce modifications in both tunnel topologies and affect the incoming ligand capacity to displace retained water molecules at the active site. We found that a single mutation allows Mt-trHbN to acquire ligand migration rates comparable to those observed for Mt-trHbO, confirming that ligand migration is regulated by the internal tunnel architecture as well as by water molecules stabilized in the active site.

  9. Effects of chronic cocaine abuse on postsynaptic dopamine receptors

    SciTech Connect

    Volkow, N.D.; Fowler, J.S.; Wolf, A.P.; Schlyer, D.; Shiue, C.Y.; Alpert, R.; Dewey, S.L.; Logan, J.; Bendriem, B.; Christman, D. )

    1990-06-01

    To assess the effects of chronic cocaine intoxication on dopamine receptors in human subjects, the authors evaluated ({sup 18}F)N-methylspiroperidol binding using positron emission tomography in 10 cocaine abusers and 10 normal control subjects. Cocaine abusers who had been detoxified for 1 week or less showed significantly lower values for uptake of ({sup 18}F)N-methylspiroperidol in striatum than the normal subjects, whereas the cocaine abusers who had been detoxified for 1 month showed values comparable to those obtained from normal subjects. The authors conclude that postsynaptic dopamine receptor availability decreases with chronic cocaine abuse but may recover after a drug-free interval.

  10. Classic Studies on the Interaction of Cocaine and the Dopamine Transporter.

    PubMed

    Verma, Vivek

    2015-12-31

    The dopamine transporter is responsible for recycling dopamine after release. Inhibitors of the dopamine transporter, such as cocaine, will stop the reuptake of dopamine and allow it to stay extracellularly, causing prominent changes at the molecular, cellular, and behavioral levels. There is much left to be known about the mechanism and site(s) of binding, as well as the effect that cocaine administration does to dopamine transporter-cocaine binding sites and gene expression which also plays a strong role in cocaine abusers and their behavioral characteristics. Thus, if more light is shed on the dopamine transporter-cocaine interaction, treatments for addiction and even other diseases of the dopaminergic system may not be too far ahead. As today's ongoing research expands on the shoulders of classic research done in the 1990s and 2000s, the foundation of core research done in that time period will be reviewed, which forms the basis of today's work and tomorrow's therapies. PMID:26598579

  11. Did we choose the best one? A new site selection approach based on exposure and uptake potential for waste incineration.

    PubMed

    Demirarslan, K Onur; Korucu, M Kemal; Karademir, Aykan

    2016-08-01

    Ecological problems arising after the construction and operation of a waste incineration plant generally originate from incorrect decisions made during the selection of the location of the plant. The main objective of this study is to investigate how the selection method for the location of a new municipal waste incineration plant can be improved by using a dispersion modelling approach supported by geographical information systems and multi-criteria decision analysis. Considering this aim, the appropriateness of the current location of an existent plant was assessed by applying a pollution dispersion model. Using this procedure, the site ranking for a total of 90 candidate locations and the site of the existing incinerator were determined by a new location selection practice and the current place of the plant was evaluated by ANOVA and Tukey tests. This ranking, made without the use of modelling approaches, was re-evaluated based on the modelling of various variables, including the concentration of pollutants, population and population density, demography, temporality of meteorological data, pollutant type, risk formation type by CALPUFF and re-ranking the results. The findings clearly indicate the impropriety of the location of the current plant, as the pollution distribution model showed that its location was the fourth-worst choice among 91 possibilities. It was concluded that the location selection procedures for waste incinerators should benefit from the improvements obtained by the articulation of pollution dispersion studies combined with the population density data to obtain the most suitable location.

  12. Did we choose the best one? A new site selection approach based on exposure and uptake potential for waste incineration.

    PubMed

    Demirarslan, K Onur; Korucu, M Kemal; Karademir, Aykan

    2016-08-01

    Ecological problems arising after the construction and operation of a waste incineration plant generally originate from incorrect decisions made during the selection of the location of the plant. The main objective of this study is to investigate how the selection method for the location of a new municipal waste incineration plant can be improved by using a dispersion modelling approach supported by geographical information systems and multi-criteria decision analysis. Considering this aim, the appropriateness of the current location of an existent plant was assessed by applying a pollution dispersion model. Using this procedure, the site ranking for a total of 90 candidate locations and the site of the existing incinerator were determined by a new location selection practice and the current place of the plant was evaluated by ANOVA and Tukey tests. This ranking, made without the use of modelling approaches, was re-evaluated based on the modelling of various variables, including the concentration of pollutants, population and population density, demography, temporality of meteorological data, pollutant type, risk formation type by CALPUFF and re-ranking the results. The findings clearly indicate the impropriety of the location of the current plant, as the pollution distribution model showed that its location was the fourth-worst choice among 91 possibilities. It was concluded that the location selection procedures for waste incinerators should benefit from the improvements obtained by the articulation of pollution dispersion studies combined with the population density data to obtain the most suitable location. PMID:27354016

  13. Identification and characterization of two nuclear factor-kappaB sites in the regulatory region of the dopamine D2 receptor.

    PubMed

    Bontempi, Sandra; Fiorentini, Chiara; Busi, Chiara; Guerra, Nicoletta; Spano, PierFranco; Missale, Cristina

    2007-05-01

    Regulation of D2 receptor (D2R) expression is crucial in the function of dopaminergic systems. Because alterations of D2R expression may contribute to the development of different disorders, it is important to elucidate the mechanisms regulating D2R gene transcription. We report the characterization of two putative nuclear factor-kappaB (NF-kappaB) motifs, referred to as D2-kappaB sites, in the human D2R promoter, and demonstrate that they bind NF-kappaB subunits and stimulate D2R promoter activity. D2-kappaB sites show different degrees of conservation and specificity, when compared with canonical kB sites. The D2-kappaB1 site (from -407 to -398) is highly conserved and binds p50/p65 and p50/c-Rel complexes, whereas D2-kappaB2 (from -513 to -504) is more degenerated and only binds p50/p65 heterodimers. Activation of D2-kappaB sites in COS-7 cells expressing a luciferase reporter vector containing the D2R promoter resulted in increased transcriptional activity. Site-directed mutagenesis of each D2-kappaB site differentially modified D2R promoter activity. In particular, mutation of the D2-kappaB1 motif did not affect D2R promoter response to p50/c-Rel complexes, whereas inactivation of the D2-kappaB2 site decreased it. Mutations of either D2-kappaB1 or D2-kappaB2 sites attenuated the D2R promoter transcriptional efficiency induced by p50/p65 complexes. Thus, D2R transcription mediated by p50/c-Rel is supported mainly by the D2-kappaB2 site, whereas both sites are necessary to support the full transcriptional activity mediated by p50/p65 complexes. A correlation was found between NF-kappaB activity and D2R expression in the pituitary and pituitary-derived cells but not in the striatum, suggesting that NF-kappaB regulation of D2R expression could be a pituitary-specific mechanism.

  14. A novel heterocyclic compound targeting the dopamine transporter improves performance in the radial arm maze and modulates dopamine receptors D1-D3.

    PubMed

    Saroja, Sivaprakasam R; Aher, Yogesh D; Kalaba, Predrag; Aher, Nilima Y; Zehl, Martin; Korz, Volker; Subramaniyan, Saraswathi; Miklosi, Andras G; Zanon, Lisa; Neuhaus, Winfried; Höger, Harald; Langer, Thierry; Urban, Ernst; Leban, Johann; Lubec, Gert

    2016-10-01

    A series of compounds targeting the dopamine transporter (DAT) haS been shown to improve memory performance most probably by re-uptake inhibition. Although specific DAT inhibitors are available, there is limited information about specificity, mechanism and in particular the effect on dopamine receptors. It was therefore the aim of the study to test the DAT inhibitor 4-(diphenyl-methanesulfinylmethyl)-2-methyl-thiazole (code: CE-111), synthetized in our laboratory for the specificity to target DAT, for the effects upon spatial memory and for induced dopamine receptor modulation. Re-uptake inhibition was tested for DAT (IC50=3.2μM), serotonin transporter, SERT (IC50=272291μM) and noradrenaline transporter, NET (IC50=174μM). Spatial memory was studied in the radial arm maze (RAM) in male Sprague-Dawley rats that were intraperitoneally injected with CE-111 (1 or 10mg/kg body weight). Performance in the RAM was improved using 1 and 10mg/kg body weight of CE-111. Training and treatment effects on presynaptic, postsynaptic and extrasynaptic D1 and D2- receptors and dopamine receptor containing complexes as well as on activated DAT were observed. CE-111 was crossing the blood-brain barrier comparable to modafinil and was identified as effective to improve memory performance in the RAM. Dopamine re-uptake inhibition along with modulations in dopamine receptors are proposed as potential underlying mechanisms. PMID:27288589

  15. An evaluation of the regional acid deposition model surface module for ozone uptake at three sites in the San Joaquin Valley of California

    NASA Technical Reports Server (NTRS)

    Massman, W. J.; Pederson, J.; Delany, A.; Grantz, D.; Hertog, G. Den; Neumann, H. H.; Oncley, S. P.; Pearson, R., Jr.; Shaw, R. H.

    1994-01-01

    Plants and soils act as major sinks for the destruction of tropospheric ozone, especially during daylight hours when plant stomata open and are thought to provide the dominant pathway for the uptake of ozone. The present study, part of the California Ozone Deposition Experiment, compares predictions of the regional acid deposition model ozone surface conductance module with surface conductance data derived from eddy covariance measurements of ozone flux taken at a grape, a cotton, and a grassland site in the San Joaquin Valley of California during the summer of 1991. Results indicate that the model (which was developed to provide long-term large-area estimates for the eastern United States) significantly overpredicts the surface conductance at all times of the day for at least two important types of plant cover of the San Joaquin Valley and that it incorrectly partitions the ozone flux between transpiring and nontranspiring components of the surface at the third site. Consequently, the model either overpredicts or inaccurately represents the observed deposition velocities. Other results indicate that the presence of dew does not reduce the rate of ozone deposition, contradicting to model assumptions, and that model assumptions involving the dependency of stomata upon environmental temperature are unnecessary. The effects of measurement errors and biases, arising from the presence of the roughness sublayer and possible photochemical reactions, are also discussed. A simpler model for ozone surface deposition (at least for the San Joaquin Valley) is proposed and evaluated.

  16. (125)I-spectramide: A novel benzamide displaying potent and selective effects at the D sub 2 dopamine receptor

    SciTech Connect

    Sanchez-Roa, P.M.; Grigoriadis, D.E.; Wilson, A.A.; Sharkey, J.; Dannals, R.F.; Villemagne, Victor, L.; Wong, D.F.; Wagner, H.N. Jr.; Kuhar, M.J. )

    1989-01-01

    The new substituted benzamide Spectramide, (N-(2-(4-iodobenzyl-N-methylamino)-2-methoxy-4-ethyl)-5-chloro-methylamine benzamide) labelled with {sup 125}I was used as a potent and highly selective dopamine-D{sub 2} receptor antagonist in rat striatal homogenates for in vitro receptor binding. Kinetic experiments demonstrated the reversibility of the binding and the estimated Kd from saturation analysis was 25 pM, with a Bmax of 20 pmol/g of tissue. Competition studies showed that spectramide did not interact potently with the D{sub 1} or dopamine-uptake site. Drugs known to interact with other receptor system were weak competitors of the binding, while binding was potently inhibited by other D{sub 2} antagonists, such as spiperone and eticlopride. These data indicate that Spectramide binds selectively and with high affinity to the dopamine D{sub 2} receptors, and may prove to be a useful tool for the study of these receptors in vivo using PET or SPECT.

  17. Acute fasting increases somatodendritic dopamine release in the ventral tegmental area.

    PubMed

    Roseberry, Aaron G

    2015-08-01

    Fasting and food restriction alter the activity of the mesolimbic dopamine system to affect multiple reward-related behaviors. Food restriction decreases baseline dopamine levels in efferent target sites and enhances dopamine release in response to rewards such as food and drugs. In addition to releasing dopamine from axon terminals, dopamine neurons in the ventral tegmental area (VTA) also release dopamine from their soma and dendrites, and this somatodendritic dopamine release acts as an autoinhibitory signal to inhibit neighboring VTA dopamine neurons. It is unknown whether acute fasting also affects dopamine release, including the local inhibitory somatodendritic dopamine release in the VTA. In these studies, I have tested whether fasting affects the inhibitory somatodendritic dopamine release within the VTA by examining whether an acute 24-h fast affects the inhibitory postsynaptic current mediated by evoked somatodendritic dopamine release (D2R IPSC). Fasting increased the contribution of the first action potential to the overall D2R IPSC and increased the ratio of repeated D2R IPSCs evoked at short intervals. Fasting also reduced the effect of forskolin on the D2R IPSC and led to a significantly bigger decrease in the D2R IPSC in low extracellular calcium. Finally, fasting resulted in an increase in the D2R IPSCs when a more physiologically relevant train of D2R IPSCs was used. Taken together, these results indicate that fasting caused a change in the properties of somatodendritic dopamine release, possibly by increasing dopamine release, and that this increased release can be sustained under conditions where dopamine neurons are highly active.

  18. Comparison of dopamine kinetics in the larval Drosophila ventral nerve cord and protocerebrum with improved optogenetic stimulation.

    PubMed

    Privman, Eve; Venton, B Jill

    2015-11-01

    Dopamine release and uptake have been studied in the Drosophila larval ventral nerve cord (VNC) using optogenetics to stimulate endogenous release. However, other areas of the central nervous system remain uncharacterized. Here, we compare dopamine release in the VNC and protocerebrum of larval Drosophila. Stimulations were performed with CsChrimson, a new, improved, red light-activated channelrhodopsin. In both regions, dopamine release was observed after only a single, 4 ms duration light pulse. Michaelis-Menten modeling was used to understand release and uptake parameters for dopamine. The amount of dopamine released ([DA]p ) on the first stimulation pulse is higher than the average [DA]p released from subsequent pulses. The initial and average amount of dopamine released per stimulation pulse is smaller in the protocerebrum than in the VNC. The average Vmax of 0.08 μM/s in the protocerebrum was significantly higher than the Vmax of 0.05 μM/s in the VNC. The average Km of 0.11 μM in the protocerebrum was not significantly different from the Km of 0.10 μM in the VNC. When the competitive dopamine transporter (DAT) inhibitor nisoxetine was applied, the Km increased significantly in both regions while Vmax stayed the same. This work demonstrates regional differences in dopamine release and uptake kinetics, indicating important variation in the amount of dopamine available for neurotransmission and neuromodulation. We use a new optogenetic tool, red light activated CsChrimson, to stimulate the release of dopamine in the ventral nerve cord and medial protocerebrum of the larval Drosophila central nervous system. We monitored extracellular dopamine by fast scan cyclic voltammetry and used Michaelis-Menten modeling to probe the regulation of extracellular dopamine, discovering important similarities and differences in these two regions.

  19. Cadmium and zinc uptake by volunteer willow species and elder rooting in polluted dredged sediment disposal sites.

    PubMed

    Vandecasteele, Bart; De Vos, Bruno; Tack, Filip M G

    2002-11-01

    Salix species and Sambucus nigra L. (elder) naturally invade dredged sediment landfills and are commonly encountered on substrates contaminated with heavy metals. Foliar concentrations of Cd and Zn in four Salix species and elder were explored in the field. Metal contents in dredged sediment derived soils were elevated compared to baseline concentration levels reported for Flanders. To evaluate foliar concentrations, reference data were compiled from observations in nurseries, young plantations and unpolluted sites with volunteer willow vegetation. Willows grown on polluted dredged sediment landfills showed elevated foliar Cd and Zn concentrations (>6.6 mg Cd/kg DW and >700 mg Zn/kg DW). This was not the case for elder. For willow, a significant relation was found between soil total Zn or Cd and foliar Zn or Cd, regardless of age, species, or clone. Willows proved to be useful bioindicators. Results indicated a possible threat in long-term habitat development of willow brushwood from transfer of Cd and Zn to the food web.

  20. Dopamine dynamics and cocaine sensitivity differ between striosome and matrix compartments of the striatum.

    PubMed

    Salinas, Armando G; Davis, Margaret I; Lovinger, David M; Mateo, Yolanda

    2016-09-01

    The striatum is typically classified according to its major output pathways, which consist of dopamine D1 and D2 receptor-expressing neurons. The striatum is also divided into striosome and matrix compartments, based on the differential expression of a number of proteins, including the mu opioid receptor, dopamine transporter (DAT), and Nr4a1 (nuclear receptor subfamily 4, group A, member 1). Numerous functional differences between the striosome and matrix compartments are implicated in dopamine-related neurological disorders including Parkinson's disease and addiction. Using Nr4a1-eGFP mice, we provide evidence that electrically evoked dopamine release differs between the striosome and matrix compartments in a regionally-distinct manner. We further demonstrate that this difference is not due to differences in inhibition of dopamine release by dopamine autoreceptors or nicotinic acetylcholine receptors. Furthermore, cocaine enhanced extracellular dopamine in striosomes to a greater degree than in the matrix and concomitantly inhibited dopamine uptake in the matrix to a greater degree than in striosomes. Importantly, these compartment differences in cocaine sensitivity were limited to the dorsal striatum. These findings demonstrate a level of exquisite microanatomical regulation of dopamine by the DAT in striosomes relative to the matrix. PMID:27036891

  1. Random and site-specific mutagenesis of the Helicobacter pylori ferric uptake regulator provides insight into Fur structure-function relationships.

    PubMed

    Gilbreath, Jeremy J; Pich, Oscar Q; Benoit, Stéphane L; Besold, Angelique N; Cha, Jeong-Heon; Maier, Robert J; Michel, Sarah L J; Maynard, Ernest L; Merrell, D Scott

    2013-07-01

    The ferric uptake regulator (Fur) of Helicobacter pylori is a global regulator that is important for colonization and survival within the gastric mucosa. H. pylori Fur is unique in its ability to activate and repress gene expression in both the iron-bound (Fe-Fur) and apo forms (apo-Fur). In the current study we combined random and site-specific mutagenesis to identify amino acid residues important for both Fe-Fur and apo-Fur function. We identified 25 mutations that affected Fe-Fur repression and 23 mutations that affected apo-Fur repression, as determined by transcriptional analyses of the Fe-Fur target gene amiE, and the apo-Fur target gene, pfr. In addition, eight of these mutations also significantly affected levels of Fur in the cell. Based on regulatory phenotypes, we selected several representative mutations to characterize further. Of those selected, we purified the wild-type (HpFurWT) and three mutant Fur proteins (HpFurE5A, HpFurA92T and HpFurH134Y), which represent mutations in the N-terminal extension, the regulatory metal binding site (S2) and the structural metal binding site (S3) respectively. Purified proteins were evaluated for secondary structure by circular dichroism spectroscopy, iron-binding by atomic absorption spectrophotometry, oligomerization in manganese-substituted and apo conditions by in vitro cross-linking assays, and DNA binding to Fe-Fur and apo-Fur target sequences by fluorescence anisotropy. The results showed that the N-terminal, S2 and S3 regions play distinct roles in terms of Fur structure-function relationships. Overall, these studies provide novel information regarding the role of these residues in Fur function, and provide mechanistic insight into how H. pylori Fur regulates gene expression in both the iron-bound and apo forms of the protein.

  2. Random and site-specific mutagenesis of the Helicobacter pylori ferric uptake regulator provides insight into Fur structure-function relationships.

    PubMed

    Gilbreath, Jeremy J; Pich, Oscar Q; Benoit, Stéphane L; Besold, Angelique N; Cha, Jeong-Heon; Maier, Robert J; Michel, Sarah L J; Maynard, Ernest L; Merrell, D Scott

    2013-07-01

    The ferric uptake regulator (Fur) of Helicobacter pylori is a global regulator that is important for colonization and survival within the gastric mucosa. H. pylori Fur is unique in its ability to activate and repress gene expression in both the iron-bound (Fe-Fur) and apo forms (apo-Fur). In the current study we combined random and site-specific mutagenesis to identify amino acid residues important for both Fe-Fur and apo-Fur function. We identified 25 mutations that affected Fe-Fur repression and 23 mutations that affected apo-Fur repression, as determined by transcriptional analyses of the Fe-Fur target gene amiE, and the apo-Fur target gene, pfr. In addition, eight of these mutations also significantly affected levels of Fur in the cell. Based on regulatory phenotypes, we selected several representative mutations to characterize further. Of those selected, we purified the wild-type (HpFurWT) and three mutant Fur proteins (HpFurE5A, HpFurA92T and HpFurH134Y), which represent mutations in the N-terminal extension, the regulatory metal binding site (S2) and the structural metal binding site (S3) respectively. Purified proteins were evaluated for secondary structure by circular dichroism spectroscopy, iron-binding by atomic absorption spectrophotometry, oligomerization in manganese-substituted and apo conditions by in vitro cross-linking assays, and DNA binding to Fe-Fur and apo-Fur target sequences by fluorescence anisotropy. The results showed that the N-terminal, S2 and S3 regions play distinct roles in terms of Fur structure-function relationships. Overall, these studies provide novel information regarding the role of these residues in Fur function, and provide mechanistic insight into how H. pylori Fur regulates gene expression in both the iron-bound and apo forms of the protein. PMID:23710935

  3. Random and Site-Specific Mutagenesis of the Helicobacter pylori Ferric Uptake Regulator Provides Insight into Fur Structure-Function Relationships

    PubMed Central

    Gilbreath, Jeremy J.; Pich, Oscar Q.; Benoit, Stéphane L.; Besold, Angelique N.; Cha, Jeong-Heon; Maier, Robert J.; Michel, Sarah L.J.; Maynard, Ernest L.; Merrell, D. Scott

    2013-01-01

    Summary The ferric uptake regulator (Fur) of Helicobacter pylori is a global regulator that is important for colonization and survival within the gastric mucosa. H. pylori Fur is unique in its ability to activate and repress gene expression in both the iron-bound (Fe-Fur) and apo forms (apo-Fur). In the current study we combined random and site-specific mutagenesis to identify amino acid residues important for both Fe-Fur and apo-Fur function. We identified 25 mutations that affected Fe-Fur repression and 23 mutations that affected apo-Fur repression, as determined by transcriptional analyses of the Fe-Fur target gene amiE, and the apo-Fur target gene, pfr. In addition, eight of these mutations also significantly affected levels of Fur in the cell. Based on regulatory phenotypes, we selected several representative mutations to characterize further. Of those selected, we purified the wildtype (HpFurWT) and three mutant Fur proteins (HpFurE5A, HpFurA92T, and HpFurH134Y), which represent mutations in the N-terminal extension, the regulatory metal binding site (S2) and the structural metal binding site (S3), respectively. Purified proteins were evaluated for secondary structure by circular dichroism spectroscopy, iron-binding by atomic absorption spectrophotometry, oligomerization in iron-substituted and apo conditions by in vitro cross-linking assays, and DNA binding to Fe-Fur and apo-Fur target sequences by fluorescence anisotropy. The results showed that the N-terminal, S2, and S3 regions play distinct roles in terms of Fur structure-function relationships. Overall, these studies provide novel information regarding the role of these residues in Fur function, and provide mechanistic insight into how H. pylori Fur regulates gene expression in both the iron-bound and apo forms of the protein. PMID:23710935

  4. 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.

  5. Preparation and characterization of half-apo dopamine-[beta]-hydroxylase by selective removal of Cu[sub A]. Identification of a sulfur ligand at the dioxygen binding site by EXAFS and FTIR spectroscopy

    SciTech Connect

    Reedy, B.J.; Blackburn, N.J. )

    1994-03-09

    Progress has been made in determining the individual coordination of each of the copper sites (Cu[sub A] and Cu[sub B]) which comprise the active center in dopamine-[beta]-hydroxylase. Previous studies have determined the average ligand environment per copper in the fully metalated enzyme as two to three histidines and one to two O/N donors in the Cu(II) form changing to 2-3 histidines and 0.5 sulfur donors upon reduction to the Cu(I) form. Derivatives of the Cu(I) form of DBH have been made in which Cu[sub A] has been selectively removed, allowing Cu[sub B], the O[sub 2] binding center to be studied by EXAFS and FTIR. Cu[sub B] has been found to be coordinated to two histidines (Cu-N = 1.99 [+-] 0.03 [angstrom]), a S-donor ligand (Cu-S = 2.25 [+-] 0.03 [angstrom]), and a fourth, as yet unidentified ligand X (Cu-X = 2.53 [+-] 0.03 [angstrom]). The FTIR spectrum of the carbonyl derivative of Cu[sub B] indicates that V[sub CO] (2089 cm[sup [minus]1]) is identical to that found for the fully metalated enzyme, providing strong evidence that the Cu[sub B] site is not perturbed by Cu[sub A] removal. EXAFS results on Cu[sub B]-CO indicate that CO binding does not displace the S ligand but appears to displace the weakly bound ligand X. 44 refs., 4 figs., 3 tabs.

  6. Structural studies of dopamine. beta. -hydroxylase

    SciTech Connect

    Papadopoulos, N.J.

    1985-01-01

    Dopamine ..beta..-hydroxylase catalyzes the conversion of dopamine to norepinephrine, a ..beta..-hydroxylation reaction, utilizing ascorbic acid as reducing agent and molecular oxygen as cosubstrate. Modifications of the previously published purification procedure for D..beta..H have produced findings which show that (1) enzyme is inactivated by ascorbate autooxidation during the isolation procedure, (2) active as well as inactive D..beta..H co-purify throughout the entire purification procedure and (3) beef liver catalase totally protects against this time dependent inactivation. The stoichiometry of copper binding to the active sites of D..beta..H has been investigated using /sup 19/F-NMR and radioactive binding experiments. The data unequivocally show that homogeneous D..beta..H (isolated in the presence of catalase) specifically binds up to approx.8 copper atoms per enzyme tetramer. Distance determinations done using NMR relaxation rate theory show that anion activators of the catalytic reaction are bound at a fairly far distance from the Cu/sup 2 +/ centers. Spin-echo electron paramagnetic resonance spectroscopy indicates that at least one, possibly two, histidines are bound as equatorial ligands to each Cu/sup 2 +/ ion. The combined data indicate that highly purified dopamine ..beta..-hydroxylase contains a 2 copper atom active site, composed of magnetically non-interacting metal centers. Active site components are distant from the Cu/sup 2 +/ centers, suggesting a possible movement of active site residues or components after reduction of enzyme bound copper in order to achieve the insertion of 1 atom of oxygen into the benzylic C-H bond of dopamine.

  7. Dopamine D3 autoreceptor inhibition enhances cocaine potency at the dopamine transporter.

    PubMed

    McGinnis, Molly M; Siciliano, Cody A; Jones, Sara R

    2016-09-01

    Cocaine is a commonly abused central nervous system stimulant that enhances dopamine (DA) neurotransmission through its ability to block dopamine transporters (DATs). Recent evidence suggests there may be an interaction between DATs and D2/D3 autoreceptors that modulates cocaine's effects. The purpose of this study was to explore how D2/D3 autoreceptors modulate the ability of cocaine to inhibit DA uptake through DATs on pre-synaptic DA terminals. Using fast-scan cyclic voltammetry in brain slices containing the nucleus accumbens core from male and female C57BL/6J mice, we first sought to examine the effects of global autoreceptor blockade using the non-selective D2/D3 autoreceptor antagonist, raclopride. We found that the ability of cocaine to inhibit DA uptake was increased by raclopride and that this effect was consistent across sexes. Furthermore, using D2 (L-741,626) or D3 (SB-277011-A) autoreceptor selective antagonists, we discovered that blockade of D3, but not D2, autoreceptors was responsible for the increased cocaine potency. Alterations in cocaine potency were attributable to alterations in uptake inhibition, rather than cocaine effects on vesicular DA release, suggesting that these results may be a product of a functional D3/DAT interaction apart from the canonical inhibitory actions of D3 autoreceptors on DA release. In addition, application of D2 (sumanirole) and D3 (PD 128907) autoreceptor-specific agonists had inverse effects, whereby D2 autoreceptor activation decreased cocaine potency and D3 autoreceptor activation had no effect. Together, these data show that DA autoreceptors dynamically regulate cocaine potency at the DAT, which is important for understanding cocaine's rewarding and addictive properties. We propose a model whereby presynaptic dopamine autoreceptors dynamically modulate cocaine potency through two separate mechanisms. We demonstrate that D2 agonists decrease cocaine potency, whereas D3 antagonists increase cocaine potency

  8. Site-specific conjugation of monodispersed DOTA-PEGn to a thiolated diabody reveals the effect of increasing peg size on kidney clearance and tumor uptake with improved 64-copper PET imaging.

    PubMed

    Li, Lin; Crow, Desiree; Turatti, Fabio; Bading, James R; Anderson, Anne-Line; Poku, Erasmus; Yazaki, Paul J; Carmichael, Jenny; Leong, David; Wheatcroft, David; Wheatcroft, Michael P; Raubitschek, Andrew A; Hudson, Peter J; Colcher, David; Shively, John E

    2011-04-20

    Optimal PET imaging of tumors with radiolabeled engineered antibodies requires, among other parameters, matching blood clearance and tumor uptake with the half-life of the engineered antibody. Although diabodies have favorable molecular sizes (50 kDa) for rapid blood clearance (t(1/2) = 30-60 min) and are bivalent, thereby increasing tumor uptake, they exhibit substantial kidney uptake as their major route of clearance, which is especially evident when they are labeled with the PET isotope (64)Cu (t(1/2) = 12 h). To overcome this drawback, diabodies may be conjugated to PEG, a modification that increases the apparent molecular size of the diabody and reduces kidney uptake without adversely affecting tumor uptake or the tumor to blood ratio. We show here that site-specific attachment of monodispersed PEGn of increasing molecular size (n = 12, 24, and 48) can uniformly increase the apparent molecular size of the PEG-diabody conjugate, decrease kidney uptake, and increase tumor uptake, the latter due to the increased residence time of the conjugate in the blood. Since the monodispersed PEGs were preconjugated to the chelator DOTA, the conjugates were able to bind radiometals such as (111)In and (64)Cu that can be used for SPECT and PET imaging, respectively. To allow conjugation of the DOTA-PEG to the diabody, the DOTA-PEG incorporated a terminal cysteine conjugated to a vinyl sulfone moiety. In order to control the conjugation chemistry, we have engineered a surface thiolated diabody that incorporates two cysteines per monomer (four per diabody). The thiolated diabody was expressed and purified from bacterial fermentation and only needs to be reduced prior to conjugation to the DOTA-PEGn-Cys-VS. This novel imaging agent (a diabody with DOTA-PEG48-Cys-VS attached to introduced thiols) gave up to 80%ID/g of tumor uptake with a tumor to blood ratio (T/B) of 8 at 24 h when radiolabeled with (111)In and 37.9% ID/g of tumor uptake (T/B = 8) at 44 h when radiolabeled with

  9. Measurements, in vivo, of parameters of the dopamine system

    SciTech Connect

    Friedman, A.M.; DeJesus, O.T.; Dinerstein, R.; Revenaugh, J.

    1983-01-01

    This paper discusses methods of measuring important parameters of the dopamine system in the living animal by use of PET techniques. One primary concern is the density and binding affinity of post-synaptic neuroreceptors. A second concern is the activity of neurons. In vivo, this is generally related to the turnover of neurotransmitter and can also be related to the uptake of precursor compounds by the neurons. If the transmitter and neuroleptic compound compete for the same binding sites (on the receptor molecule) these two effects are interwoven and are not easily isolated. It appears that the movement of neuroleptic drugs from the brain is slow enough to allow equilibrium to be maintained between ligand and receptor, especially after some time for the initial washout and translocation in the brain. To test the consequences of equilibrium binding and the possible use of the model for measurement of receptor densities by emission tomography we have modified Clark's equilibrium model of ligand binding. In this note we will describe the solutions of the equations and some comparisons of the predictions of the model with data, as well as its application to tomographic measurements.

  10. Uptake of strontium by chamisa (Chrysothamnus nauseosus) shrub plants growing over a former liquid waste disposal site at Los Alamos National Laboratory

    SciTech Connect

    Fresquez, P.R.; Foxx, T.S.; Naranjo, L. Jr.

    1996-06-01

    A major concern of managers at low-level waste burial site facilities is that plant roots may translocate contaminants up to the soil surface. This study investigates the uptake of strontium ({sup 90}Sr), a biologically mobile element, by chamisa (Chrysothamnus nauseosus), a deep-rooted shrub plant, growing in a former liquid waste disposal site (Solid Waste Management Unit [SWMU] 10-003[c]) at Los Alamos National Laboratory (LANL), Los Alamos, New Mexico. Surface soil samples were also collected from below (understory) and between (interspace) shrub canopies. Both chamisa plants growing over SWMU 10-003(c) contained significantly higher concentrations of {sup 90}Sr than a control plant--one plant, in particular, contained 3.35 x 10{sup 6} Bq kg{sup {minus}1} ash (9.05 x 10{sup 4} pCi g{sup {minus}1} ash) in top-growth material. Similarly, soil surface samples collected underneath and between plants contained {sup 90}Sr concentrations above background and LANL screening action levels (> 218 Bq kg{sup {minus}1} dry [5.90 pCi g{sup {minus}1} dry]); this probably occurred as a result of chamisa plant leaf fall contaminating the soil understory area followed by water and/or winds moving {sup 90}Sr to the soil interspace areas. Although some soil surface migration of {sup 90}Sr from SWMU 10-003(c) has occurred, the level of {sup 90}Sr in sediments collected downstream of SWMU 10-003(c) at the LANL boundary was still within regional (background) concentrations.

  11. Dopamine receptors in pituitary adenomas: PET visualization with 11C-N-methylspiperone

    SciTech Connect

    Muhr, C.; Bergstroem, M.L.; Lundberg, P.O.; Bergstroem, K.H.; Hartvig, P.; Lundqvist, H.; Antoni, G.; Langstroem B2

    1986-03-01

    Two patients with pituitary tumors were examined with positron emission tomography (PET) after intravenous administration of 11C-N-methylspiperone. In repeat studies the patients were given 1 mg of intravenous haloperidol prior to the administration of the radioligand to block the dopamine receptors. High uptakes of the radiolabeled ligand were seen in one of the tumors. With haloperidol pretreatment the uptake was lower, probably mainly showing the remaining unspecific binding. The most marked uptake and the largest effect of haloperidol pretreatment was seen in a patient with a hormonally active prolactinoma. Dopamine receptor binding in pituitary tumors can be demonstrated in vivo with PET, and quantification of this binding is possible using a compartmental model. This technique may be useful in improving our understanding of the variable response to medical treatment of prolactinomas with dopamine agonists as well as in the prediction of the effect of such treatment.

  12. Does human presynaptic striatal dopamine function predict social conformity?

    PubMed

    Stokes, Paul R A; Benecke, Aaf; Puraite, Julita; Bloomfield, Michael A P; Shotbolt, Paul; Reeves, Suzanne J; Lingford-Hughes, Anne R; Howes, Oliver; Egerton, Alice

    2014-03-01

    Socially desirable responding (SDR) is a personality trait which reflects either a tendency to present oneself in an overly positive manner to others, consistent with social conformity (impression management (IM)), or the tendency to view one's own behaviour in an overly positive light (self-deceptive enhancement (SDE)). Neurochemical imaging studies report an inverse relationship between SDR and dorsal striatal dopamine D₂/₃ receptor availability. This may reflect an association between SDR and D₂/₃ receptor expression, synaptic dopamine levels or a combination of the two. In this study, we used a [¹⁸F]-DOPA positron emission tomography (PET) image database to investigate whether SDR is associated with presynaptic dopamine function. Striatal [¹⁸F]-DOPA uptake, (k(i)(cer), min⁻¹), was determined in two independent healthy participant cohorts (n=27 and 19), by Patlak analysis using a cerebellar reference region. SDR was assessed using the revised Eysenck Personality Questionnaire (EPQ-R) Lie scale, and IM and SDE were measured using the Paulhus Deception Scales. No significant associations were detected between Lie, SDE or IM scores and striatal [¹⁸F]-DOPA k(i)(cer). These results indicate that presynaptic striatal dopamine function is not associated with social conformity and suggests that social conformity may be associated with striatal D₂/₃ receptor expression rather than with synaptic dopamine levels.

  13. Optogenetic Control of Serotonin and Dopamine Release in Drosophila Larvae

    PubMed Central

    2014-01-01

    Optogenetic control of neurotransmitter release is an elegant method to investigate neurobiological mechanisms with millisecond precision and cell type-specific resolution. Channelrhodopsin-2 (ChR2) can be expressed in specific neurons, and blue light used to activate those neurons. Previously, in Drosophila, neurotransmitter release and uptake have been studied after continuous optical illumination. In this study, we investigated the effects of pulsed optical stimulation trains on serotonin or dopamine release in larval ventral nerve cords. In larvae with ChR2 expressed in serotonergic neurons, low-frequency stimulations produced a distinct, steady-state response while high-frequency patterns were peak shaped. Evoked serotonin release increased with increasing stimulation frequency and then plateaued. The steady-state response and the frequency dependence disappeared after administering the uptake inhibitor fluoxetine, indicating that uptake plays a significant role in regulating the extracellular serotonin concentration. Pulsed stimulations were also used to evoke dopamine release in flies expressing ChR2 in dopaminergic neurons and similar frequency dependence was observed. Release due to pulsed optical stimulations was modeled to determine the uptake kinetics. For serotonin, Vmax was 0.54 ± 0.07 μM/s and Km was 0.61 ± 0.04 μM; and for dopamine, Vmax was 0.12 ± 0.03 μM/s and Km was 0.45 ± 0.13 μM. The amount of serotonin released per stimulation pulse was 4.4 ± 1.0 nM, and the amount of dopamine was 1.6 ± 0.3 nM. Thus, pulsed optical stimulations can be used to mimic neuronal firing patterns and will allow Drosophila to be used as a model system for studying mechanisms underlying neurotransmission. PMID:24849718

  14. Optogenetic control of serotonin and dopamine release in Drosophila larvae.

    PubMed

    Xiao, Ning; Privman, Eve; Venton, B Jill

    2014-08-20

    Optogenetic control of neurotransmitter release is an elegant method to investigate neurobiological mechanisms with millisecond precision and cell type-specific resolution. Channelrhodopsin-2 (ChR2) can be expressed in specific neurons, and blue light used to activate those neurons. Previously, in Drosophila, neurotransmitter release and uptake have been studied after continuous optical illumination. In this study, we investigated the effects of pulsed optical stimulation trains on serotonin or dopamine release in larval ventral nerve cords. In larvae with ChR2 expressed in serotonergic neurons, low-frequency stimulations produced a distinct, steady-state response while high-frequency patterns were peak shaped. Evoked serotonin release increased with increasing stimulation frequency and then plateaued. The steady-state response and the frequency dependence disappeared after administering the uptake inhibitor fluoxetine, indicating that uptake plays a significant role in regulating the extracellular serotonin concentration. Pulsed stimulations were also used to evoke dopamine release in flies expressing ChR2 in dopaminergic neurons and similar frequency dependence was observed. Release due to pulsed optical stimulations was modeled to determine the uptake kinetics. For serotonin, Vmax was 0.54 ± 0.07 μM/s and Km was 0.61 ± 0.04 μM; and for dopamine, Vmax was 0.12 ± 0.03 μM/s and Km was 0.45 ± 0.13 μM. The amount of serotonin released per stimulation pulse was 4.4 ± 1.0 nM, and the amount of dopamine was 1.6 ± 0.3 nM. Thus, pulsed optical stimulations can be used to mimic neuronal firing patterns and will allow Drosophila to be used as a model system for studying mechanisms underlying neurotransmission.

  15. Updating dopamine reward signals.

    PubMed

    Schultz, Wolfram

    2013-04-01

    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.

  16. 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.

  17. Enhanced Dopamine Release by Dopamine Transport Inhibitors Described by a Restricted Diffusion Model and Fast-Scan Cyclic Voltammetry.

    PubMed

    Hoffman, Alexander F; Spivak, Charles E; Lupica, Carl R

    2016-06-15

    Fast-scan cyclic voltammetry (FSCV) using carbon fiber electrodes is widely used to rapidly monitor changes in dopamine (DA) levels in vitro and in vivo. Current analytical approaches utilize parameters such as peak oxidation current amplitude and decay times to estimate release and uptake processes, respectively. However, peak amplitude changes are often observed with uptake inhibitors, thereby confounding the interpretation of these parameters. To overcome this limitation, we demonstrate that a simple five-parameter, two-compartment model mathematically describes DA signals as a balance of release (r/ke) and uptake (ku), summed with adsorption (kads and kdes) of DA to the carbon electrode surface. Using nonlinear regression, we demonstrate that our model precisely describes measured DA signals obtained in brain slice recordings. The parameters extracted from these curves were then validated using pharmacological manipulations that selectively alter vesicular release or DA transporter (DAT)-mediated uptake. Manipulation of DA release through altering the Ca(2+)/Mg(2+) ratio or adding tetrodotoxin reduced the release parameter with no effect on the uptake parameter. DAT inhibitors methylenedioxypyrovalerone, cocaine, and nomifensine significantly reduced uptake and increased vesicular DA release. In contrast, a low concentration of amphetamine reduced uptake but had no effect on DA release. Finally, the kappa opioid receptor agonist U50,488 significantly reduced vesicular DA release but had no effect on uptake. Together, these data demonstrate a novel analytical approach to distinguish the effects of manipulations on DA release or uptake that can be used to interpret FSCV data. PMID:27018734

  18. Dual Action of Zn2+ on the Transport Cycle of the Dopamine Transporter.

    PubMed

    Li, Yang; Hasenhuetl, Peter S; Schicker, Klaus; Sitte, Harald H; Freissmuth, Michael; Sandtner, Walter

    2015-12-25

    The dopamine transporter shapes dopaminergic neurotransmission by clearing extracellular dopamine and by replenishing vesicular stores. The dopamine transporter carries an endogenous binding site for Zn(2+), but the nature of the Zn(2+)-dependent modulation has remained elusive: both, inhibition and stimulation of DAT have been reported. Here, we exploited the high time resolution of patch-clamp recordings to examine the effects of Zn(2+) on the transport cycle of DAT: we recorded peak currents associated with substrate translocation and steady-state currents reflecting the forward transport mode of DAT. Zn(2+) depressed the peak current but enhanced the steady-state current through DAT. The parsimonious explanation is preferential binding of Zn(2+) to the outward facing conformation of DAT, which allows for an allosteric activation of DAT, in both, the forward transport mode and substrate exchange mode. We directly confirmed that Zn(2+) dissociated more rapidly from the inward- than from the outward-facing state of DAT. Finally, we formulated a kinetic model for the action of Zn(2+) on DAT that emulated all current experimental observations and accounted for all previous (in part contradictory) findings. Importantly, the model predicts that the intracellular Na(+) concentration determines whether substrate uptake by DAT is stimulated or inhibited by Zn(2+). This prediction was directly verified. The mechanistic framework provided by the current model is of relevance for the rational design of allosteric activators of DAT. These are of interest for treating de novo loss-of-function mutations of DAT associated with neuropsychiatric disorders such as attention deficit hyperactivity disorder (ADHD).

  19. Dual Action of Zn2+ on the Transport Cycle of the Dopamine Transporter.

    PubMed

    Li, Yang; Hasenhuetl, Peter S; Schicker, Klaus; Sitte, Harald H; Freissmuth, Michael; Sandtner, Walter

    2015-12-25

    The dopamine transporter shapes dopaminergic neurotransmission by clearing extracellular dopamine and by replenishing vesicular stores. The dopamine transporter carries an endogenous binding site for Zn(2+), but the nature of the Zn(2+)-dependent modulation has remained elusive: both, inhibition and stimulation of DAT have been reported. Here, we exploited the high time resolution of patch-clamp recordings to examine the effects of Zn(2+) on the transport cycle of DAT: we recorded peak currents associated with substrate translocation and steady-state currents reflecting the forward transport mode of DAT. Zn(2+) depressed the peak current but enhanced the steady-state current through DAT. The parsimonious explanation is preferential binding of Zn(2+) to the outward facing conformation of DAT, which allows for an allosteric activation of DAT, in both, the forward transport mode and substrate exchange mode. We directly confirmed that Zn(2+) dissociated more rapidly from the inward- than from the outward-facing state of DAT. Finally, we formulated a kinetic model for the action of Zn(2+) on DAT that emulated all current experimental observations and accounted for all previous (in part contradictory) findings. Importantly, the model predicts that the intracellular Na(+) concentration determines whether substrate uptake by DAT is stimulated or inhibited by Zn(2+). This prediction was directly verified. The mechanistic framework provided by the current model is of relevance for the rational design of allosteric activators of DAT. These are of interest for treating de novo loss-of-function mutations of DAT associated with neuropsychiatric disorders such as attention deficit hyperactivity disorder (ADHD). PMID:26504078

  20. Dopamine blockade and clinical response: Evidence for two biological subgroups of schizophrenia

    SciTech Connect

    Wolkin, A.; Barouche, F.; Wolf, A.P.; Rotrosen, J.; Fowler, J.S.; Shiue, C.Y.; Cooper, T.B.; Brodie, J.D. )

    1989-07-01

    Because CNS neuroleptic concentration cannot be directly measured in patients, the relation between clinical response and extent of dopamine receptor blockade is unknown. This relationship is critical in ascertaining whether nonresponse to neuroleptics is the result merely of inadequate CNS drug levels or of more basic biological differences in pathophysiology. Using ({sup 18}F)N-methylspiroperidol and positron emission tomography, the authors assessed dopamine receptor occupancy in 10 schizophrenic patients before and after treatment with haloperidol. Responders and nonresponders had virtually identical indices of ({sup 18}F)N-methylspiroperidol uptake after treatment, indicating that failure to respond clinically was not a function of neuroleptic uptake or binding in the CNS.

  1. Roles of uptake, biotransformation, and target site sensitivity in determining the differential toxicity of chlorpyrifos to second to fourth instar Chironomous riparius (Meigen)

    USGS Publications Warehouse

    Buchwalter, D.B.; Sandahl, J.F.; Jenkins, J.J.; Curtis, L.R.

    2004-01-01

    Early life stages of aquatic organisms tend to be more sensitive to various chemical contaminants than later life stages. This research attempted to identify the key biological factors that determined sensitivity differences among life stages of the aquatic insect Chironomous riparius. Specifically, second to fourth instar larvae were exposed in vivo to both low and high waterborne concentrations of chlorpyrifos to examine differences in accumulation rates, chlorpyrifos biotransformation, and overall sensitivity among instars. In vitro acetylcholinesterase (AChE) assays were performed with chlorpyrifos and the metabolite, chlorpyrifos-oxon, to investigate potential target site sensitivity differences among instars. Earlier instars accumulated chlorpyrifos more rapidly than later instars. There were no major differences among instars in the biotransformation rates of chlorpyrifos to the more polar metabolites, chlorpyrifos-oxon, and chlorpyridinol (TCP). Homogenate AChE activities from second to fourth instar larvae were refractory to chlorpyrifos, even at high concentrations. In contrast, homogenate AChE activities were responsive in a dose-dependent manner to chlorpyrifos-oxon. In general, it appeared that chlorpyrifos sensitivity differences among second to fourth instar C. riparius were largely determined by differences in uptake rates. In terms of AChE depression, fourth instar homogenates were more sensitive to chlorpyrifos and chlorpyrifos-oxon than earlier instars. However, basal AChE activity in fourth instar larvae was significantly higher than basal AChE activity in second to third instar larvae, which could potentially offset the apparent increased sensitivity to the oxon. ?? 2003 Elsevier B.V. All rights reserved.

  2. Temporal Pattern of Cocaine Intake Determines Tolerance vs Sensitization of Cocaine Effects at the Dopamine Transporter

    PubMed Central

    Calipari, Erin S; Ferris, Mark J; Zimmer, Benjamin A; Roberts, David CS; Jones, Sara R

    2013-01-01

    The dopamine transporter (DAT) is responsible for terminating dopamine (DA) signaling and is the primary site of cocaine's reinforcing actions. Cocaine self-administration has been shown previously to result in changes in cocaine potency at the DAT. To determine whether the DAT changes associated with self-administration are due to differences in intake levels or temporal patterns of cocaine-induced DAT inhibition, we manipulated cocaine access to produce either continuous or intermittent elevations in cocaine brain levels. Long-access (LgA, 6 h) and short-access (ShA, 2 h) continuous self-administration produced similar temporal profiles of cocaine intake that were sustained throughout the session; however, LgA had greater intake. ShA and intermittent-access (IntA, 6 h) produced the same intake, but different temporal profiles, with ‘spiking' brain levels in IntA compared with constant levels in ShA. IntA consisted of 5-min access periods alternating with 25-min timeouts, which resulted in bursts of high responding followed by periods of no responding. DA release and uptake, as well as the potency of cocaine for DAT inhibition, were assessed by voltammetry in the nucleus accumbens slices following control, IntA, ShA, and LgA self-administration. Continuous-access protocols (LgA and ShA) did not change DA parameters, but the ‘spiking' protocol (IntA) increased both release and uptake of DA. In addition, high continuous intake (LgA) produced tolerance to cocaine, while ‘spiking' (IntA) produced sensitization, relative to ShA and naive controls. Thus, intake and pattern can both influence cocaine potency, and tolerance seems to be produced by high intake, while sensitization is produced by intermittent temporal patterns of intake. PMID:23719505

  3. Extrasynaptic release of GABA and dopamine by retinal dopaminergic neurons

    PubMed Central

    Hirasawa, Hajime; Contini, Massimo; Raviola, Elio

    2015-01-01

    In the mouse retina, dopaminergic amacrine (DA) cells synthesize both dopamine and GABA. Both transmitters are released extrasynaptically and act on neighbouring and distant retinal neurons by volume transmission. In simultaneous recordings of dopamine and GABA release from isolated perikarya of DA cells, a proportion of the events of dopamine and GABA exocytosis were simultaneous, suggesting co-release. In addition, DA cells establish GABAergic synapses onto AII amacrine cells, the neurons that transfer rod bipolar signals to cone bipolars. GABAA but not dopamine receptors are clustered in the postsynaptic membrane. Therefore, dopamine, irrespective of its site of release—synaptic or extrasynaptic—exclusively acts by volume transmission. Dopamine is released upon illumination and sets the gain of retinal neurons for vision in bright light. The GABA released at DA cells' synapses probably prevents signals from the saturated rods from entering the cone pathway when the dark-adapted retina is exposed to bright illumination. The GABA released extrasynaptically by DA and other amacrine cells may set a ‘GABAergic tone’ in the inner plexiform layer and thus counteract the effects of a spillover of glutamate released at the bipolar cell synapses of adjacent OFF and ON strata, thus preserving segregation of signals between ON and OFF pathways. PMID:26009765

  4. Neuronal uptake and metabolism of 2- and 6-fluorodopamine: false neurotransmitters for positron emission tomographic imaging of sympathetically innervated tissues

    SciTech Connect

    Eisenhofer, G.; Hovevey-Sion, D.; Kopin, I.J.; Miletich, R.; Kirk, K.L.; Finn, R.; Goldstein, D.S.

    1989-01-01

    The neuronal uptake and metabolism of 2-fluorodopamine (2F-dopamine), 6-fluorodopamine (6F-dopamine) and tritium-labeled dopamine were compared in heart, submaxillary gland and spleen of rats to assess the utility of 18F-labeled 2F- or 6F-dopamine for positron emission tomographic imaging of sympathetically innervated tissues. Tritiated dopamine with and without 2F- or 6F-dopamine, or tritiated 2F-dopamine alone, were injected i.v. into rats that were or were not pretreated with desipramine to block catecholamine neuronal uptake or with reserpine to block vesicular translocation of catecholamines. Tissue and plasma samples were obtained at intervals up to 1 hr after injections. At 1 hr after injection of tritiated dopamine, tritium-labeled norepinephrine, dopamine, dihydroxyphenylacetic acid and dihydroxyphenylglucol accounted for less than 2% of the tritium in plasma but up to 92% of that in tissues; tritiated norepinephrine accounted for 70% or more of the tritium in tissues. In contrast, at 1 hr after injection of tritiated 2F-dopamine, tritiated 2F-norepinephrine accounted for 30 to 46% of the tritium in tissues. Desipramine and reserpine pretreatment blocked the tissue accumulation of tritiated and fluorinated dopamine as well as their dihydroxy-metabolites, indicating that accumulation of exogenous norepinephrine and dopamine analogs was within sympathetic storage vesicles. Relative to the doses of dopamine precursors, less 2F- and 6F-norepinephrine accumulated in tissues than tritiated norepinephrine, due largely to inefficient beta-hydroxylation of fluorinated dopamine.

  5. Synthesis and dopamine transporter imaging in rhesus monkeys with fluorine-18 labeled FECT

    SciTech Connect

    Keil, R.; Hoffman, J.M.; Eschima, D.

    1996-05-01

    Parkinson`s patients have been shown to suffer a 60-80% loss of dopamine transporters in the substantia nigra and striatum. Dopamine transporter ligands labeled with fluorine-18 (t {1/2}=110 min) are attractive probes for measuring the density of dopamine transporter sites n the striatum for the diagnosis and evaluation of Parkinson`s patients by PET. We have synthesized (Ki = 32 nM vs RTI-55), fluorine-18 labeled 2{beta}-carbomethoxy-3{beta}(4-chlorophenyl)-8-(3-fluoropropyl)nortropane (FECT), with favorable kinetics as a potential dopamine transporter PET imaging agent. Treatment of 2{beta}-carbomethoxy-3{beta}-(4-chlorophenyl)nortropane (1) with 1-bromo-2-fluoroethane (2) in CH3CN at 80{degrees}C gave FECT (3). [F-18]FECT (3) was prepared by treating 1,2-ditosyloxyethane (4) with NCA K[F-18]/K222 (365 mCi) for 5 min in CH3CN at 85{degrees}C to give [F-18] 1-fluoro-2-tosyloxyethane (5) (175 mCi)in 59% E.O.B. yield. Coupling of [F-18] 5 with 1 in DMF at 135 {degrees}C for 45 min gave [F-18]FECT (41 mCi) in 25% yield E.O.B. following HPLC purification in a total synthesis time of 122 min. [F-18] 5 was >99% radiochemically pure with a specific activity of 5 Ci/{mu}mole. Following intravenous administration to a rhesus monkey [F-18]FECT (8.13 mCi) showed a peak uptake at 30 min in the striatum (S) followed by a slow clearance and a rapid washout from the cerebellum to afford a high S/C ratio = 11.0 at 125 min. Radio-HPLC analysis of the ether extracts form plasma samples for radioactive metabolites detected only the presence of [F-18]FECT. These results suggest that FECT is an Research supported by DOE.

  6. High affinity dopamine D2 receptor radioligands. 1. Regional rat brain distribution of iodinated benzamides

    SciTech Connect

    Kessler, R.M.; Ansari, M.S.; de Paulis, T.; Schmidt, D.E.; Clanton, J.A.; Smith, H.E.; Manning, R.G.; Gillespie, D.; Ebert, M.H. )

    1991-08-01

    Five 125I-labeled substituted benzamides, which are close structural analogues of (S)-sulpiride, eticlopride, and isoremoxipride, were evaluated for their selective in vivo uptake into dopamine D2 receptor rich tissue of the rat brain. Iodopride (KD 0.88 nM), an iodine substituted benzamide structurally related to sulpiride, displayed a maximal striatum: cerebellar uptake ratio of 7.6. Demonstration of saturation of the receptor with (125I)iodopride in striatum required uptake in frontal cortex to be used, rather than cerebellar uptake, to define nonspecific binding. Two other ligands structurally related to eticlopride, iclopride (KD 0.23 nM) and itopride (KD 0.16 nM), displayed maximal striatal: cerebellar uptake ratios of 9.8 and 3.3, respectively. The most potent ligands, epidepride (KD 0.057 nM) and ioxipride (KD 0.070 nM) showed striatal:cerebellar uptake ratios of 234 and 65, respectively. The observed uptake ratios correlated poorly with the affinity constants for the dopamine D2 receptor alone, but were highly correlated (r = 0.92) with the product of the receptor dissociation constant (KD) and the apparent lipophilicity (kw), as determined by reverse-phase HPLC at pH 7.5. Total striatal uptake also appeared dependent on lipophilicity, with maximal uptake occurring for ligands having log kw 2.4-2.8.

  7. Selective Enhancement of Dopamine Release in the Ventral Pallidum of Methamphetamine-Sensitized Mice

    PubMed Central

    2016-01-01

    Drugs of abuse induce sensitization, which is defined as enhanced response to additional drug following a period of withdrawal. Sensitization occurs in both humans and animal models of drug reinforcement and contributes substantially to the addictive nature of drugs of abuse, because it is thought to represent enhanced motivational wanting for drug. The ventral pallidum, a key member of the reward pathway, contributes to behaviors associated with reward, such as sensitization. Dopamine inputs to the ventral pallidum have not been directly characterized. Here we provide anatomical, neurochemical, and behavioral evidence demonstrating that dopamine terminals in the ventral pallidum contribute to reward in mice. We report subregional differences in dopamine release, measured by ex vivo fast-scan cyclic voltammetry: rostral ventral pallidum exhibits increased dopamine release and uptake compared with caudal ventral pallidum, which is correlated with tissue expression of dopaminergic proteins. We then subjected mice to a methamphetamine-sensitization protocol to investigate the contribution of dopaminergic projections to the region in reward related behavior. Methamphetamine-sensitized animals displayed a 508% and 307% increase in baseline dopamine release in the rostral and caudal ventral pallidum, respectively. Augmented dopamine release in the rostral ventral pallidum was significantly correlated with sensitized locomotor activity. Moreover, this presynaptic dopaminergic plasticity occurred only in the ventral pallidum and not in the ventral or dorsal striatum, suggesting that dopamine release in the ventral pallidum may be integrally important to drug-induced sensitization. PMID:27501345

  8. X-ray structure of dopamine transporter elucidates antidepressant mechanism.

    PubMed

    Penmatsa, Aravind; Wang, Kevin H; Gouaux, Eric

    2013-11-01

    Antidepressants targeting Na(+)/Cl(-)-coupled neurotransmitter uptake define a key therapeutic strategy to treat clinical depression and neuropathic pain. However, identifying the molecular interactions that underlie the pharmacological activity of these transport inhibitors, and thus the mechanism by which the inhibitors lead to increased synaptic neurotransmitter levels, has proven elusive. Here we present the crystal structure of the Drosophila melanogaster dopamine transporter at 3.0 Å resolution bound to the tricyclic antidepressant nortriptyline. The transporter is locked in an outward-open conformation with nortriptyline wedged between transmembrane helices 1, 3, 6 and 8, blocking the transporter from binding substrate and from isomerizing to an inward-facing conformation. Although the overall structure of the dopamine transporter is similar to that of its prokaryotic relative LeuT, there are multiple distinctions, including a kink in transmembrane helix 12 halfway across the membrane bilayer, a latch-like carboxy-terminal helix that caps the cytoplasmic gate, and a cholesterol molecule wedged within a groove formed by transmembrane helices 1a, 5 and 7. Taken together, the dopamine transporter structure reveals the molecular basis for antidepressant action on sodium-coupled neurotransmitter symporters and elucidates critical elements of eukaryotic transporter structure and modulation by lipids, thus expanding our understanding of the mechanism and regulation of neurotransmitter uptake at chemical synapses.

  9. X-ray structure of dopamine transporter elucidates antidepressant mechanism.

    PubMed

    Penmatsa, Aravind; Wang, Kevin H; Gouaux, Eric

    2013-11-01

    Antidepressants targeting Na(+)/Cl(-)-coupled neurotransmitter uptake define a key therapeutic strategy to treat clinical depression and neuropathic pain. However, identifying the molecular interactions that underlie the pharmacological activity of these transport inhibitors, and thus the mechanism by which the inhibitors lead to increased synaptic neurotransmitter levels, has proven elusive. Here we present the crystal structure of the Drosophila melanogaster dopamine transporter at 3.0 Å resolution bound to the tricyclic antidepressant nortriptyline. The transporter is locked in an outward-open conformation with nortriptyline wedged between transmembrane helices 1, 3, 6 and 8, blocking the transporter from binding substrate and from isomerizing to an inward-facing conformation. Although the overall structure of the dopamine transporter is similar to that of its prokaryotic relative LeuT, there are multiple distinctions, including a kink in transmembrane helix 12 halfway across the membrane bilayer, a latch-like carboxy-terminal helix that caps the cytoplasmic gate, and a cholesterol molecule wedged within a groove formed by transmembrane helices 1a, 5 and 7. Taken together, the dopamine transporter structure reveals the molecular basis for antidepressant action on sodium-coupled neurotransmitter symporters and elucidates critical elements of eukaryotic transporter structure and modulation by lipids, thus expanding our understanding of the mechanism and regulation of neurotransmitter uptake at chemical synapses. PMID:24037379

  10. Phase I Report: Technetium Radiotracers for the Dopamine Transporter. [September 1998 - March 1999

    SciTech Connect

    Baldwin, R.N.

    1999-03-17

    This project (a) demonstrated specific dopamine transporter (DAT) uptake in vivo and metabolic stability of a radiolabelled cycloplentadieny rhenium compound in rats and baboons, (b) showed that cyclopentadieny tricarbonyl rhenium and technetium compounds conjugated tropanel could be made by metal transfer with ferrocenes; and (c) explored new methods of synthesizing these compounds under mild conditions.

  11. Diet-induced obesity: dopamine transporter function, impulsivity and motivation

    PubMed Central

    Narayanaswami, V; Thompson, AC; Cassis, LA; Bardo, MT; Dwoskin, LP

    2013-01-01

    OBJECTIVE A rat model of diet-induced obesity (DIO) was used to determine dopamine transporter (DAT) function, impulsivity and motivation as neurobehavioral outcomes and predictors of obesity. DESIGN To evaluate neurobehavioral alterations following the development of DIO induced by an 8-week high-fat diet (HF) exposure, striatal D2-receptor density, DAT function and expression, extracellular dopamine concentrations, impulsivity, and motivation for high- and low-fat reinforcers were determined. To determine predictors of DIO, neurobehavioral antecedents including impulsivity, motivation for high-fat reinforcers, DAT function and extracellular dopamine were evaluated before the 8-week HF exposure. METHODS Striatal D2-receptor density was determined by in vitro kinetic analysis of [3H]raclopride binding. DAT function was determined using in vitro kinetic analysis of [3H]dopamine uptake, methamphetamine-evoked [3H]dopamine overflow and no-net flux in vivo microdialysis. DAT cell-surface expression was determined using biotinylation and western blotting. Impulsivity and food-motivated behavior were determined using a delay discounting task and progressive ratio schedule, respectively. RESULTS Relative to obesity-resistant (OR) rats, obesity-prone (OP) rats exhibited 18% greater body weight following an 8-week HF-diet exposure, 42% lower striatal D2-receptor density, 30% lower total DAT expression, 40% lower in vitro and in vivo DAT function, 45% greater extracellular dopamine and twofold greater methamphetamine-evoked [3H]dopamine overflow. OP rats exhibited higher motivation for food, and surprisingly, were less impulsive relative to OR rats. Impulsivity, in vivo DAT function and extracellular dopamine concentration did not predict DIO. Importantly, motivation for high-fat reinforcers predicted the development of DIO. CONCLUSION Human studies are limited by their ability to determine if impulsivity, motivation and DAT function are causes or consequences of DIO. The

  12. Characterization of the effects of serotonin on the release of (/sup 3/H)dopamine from rat nucleus accumbens and striatal slices

    SciTech Connect

    Nurse, B.; Russell, V.A.; Taljaard, J.J.

    1988-05-01

    The effect of serotonin agonists on the depolarization (K+)-induced, calcium-dependent, release of (/sup 3/H)dopamine (DA) from rat nucleus accumbens and striatal slices was investigated. Serotonin enhanced basal /sup 3/H overflow and reduced K+-induced release of (/sup 3/H)DA from nucleus accumbens slices. The effect of serotonin on basal /sup 3/H overflow was not altered by the serotonin antagonist, methysergide, or the serotonin re-uptake blocker, chlorimipramine, but was reversed by the DA re-uptake carrier inhibitors nomifensine and benztropine. With the effect on basal overflow blocked, serotonin did not modulate K+-induced release of (/sup 3/H)DA in the nucleus accumbens or striatum. The serotonin agonists, quipazine (in the presence of nomifensine) and 5-methoxytryptamine, did not significantly affect K+-induced release of (/sup 3/H)DA in the nucleus accumbens. This study does not support suggestions that serotonin receptors inhibit the depolarization-induced release of dopamine in the nucleus accumbens or striatum of the rat brain. The present results do not preclude the possibility that serotonin may affect the mesolimbic reward system at a site which is post-synaptic to dopaminergic terminals in the nucleus accumbens.

  13. Brominated and radioiodinated derivatives of methylphenidate (MP): Potential imaging agents for the dopamine (DA) transporter

    SciTech Connect

    Pan, D.; Gatley, S.J.; Dewey, S.L.

    1994-05-01

    MP (Ritalin) is a psychomotor stimulant used in the treatment of attention-deficit hyperactivity disorder. The therapeutic properties of MP are thought to be mediated by its binding to a site on the DA transporter, resulting in inhibition of DA reuptake and enhanced levels of synaptic dopamine. MP also inhibits reuptake of norepinephrine (NE) in vitro. MP has two chiral centers, but its pharmacological activity is believed due solely to the d-threo isomer. We have found that d,l-threo-C-11 MP has favorable properties for PET studies, and therefore examined the effects of incorporating halogen atoms into the phenyl ring of MP, with a view to preparing C-11 and I-123 MP analogs as potential PET/SPECT tracers. We synthesized the 2-, 3- and 4-bromo MP analogs from the corresponding bromophenylacetonitriles by modification of the original synthesis of MP. In in vitro binding assays all three d,l-threo bromo compounds had higher affinities than MP for DA transporter sites labeled with tritiated WIN 35,428 (3->4-, 2->MP). They also showed high activity with NE reuptake sites labeled with tritiated nisoxetine. They were active in vivo as demonstrated by inhibition of heart uptake of tritiated NE in the mouse, and elevation of striatal extracellular DA (microdialysis) and stimulation of locomotor activity in the rat.

  14. 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.

  15. 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

  16. Dopamine, affordance and active inference.

    PubMed

    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.

  17. Mesolimbic dopamine signals the value of work.

    PubMed

    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

    2016-01-01

    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, whereas 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 found that minute-by-minute dopamine levels covaried with reward rate and motivational vigor. Second-by-second dopamine release encoded an estimate of temporally discounted future reward (a value function). Changing dopamine immediately altered willingness to work and reinforced 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, which is employed for both learning and motivational functions.

  18. Dopamine Release Dynamics Change during Adolescence and after Voluntary Alcohol Intake

    PubMed Central

    Palm, Sara; Nylander, Ingrid

    2014-01-01

    Adolescence is associated with high impulsivity and risk taking, making adolescent individuals more inclined to use drugs. Early drug use is correlated to increased risk for substance use disorders later in life but the neurobiological basis is unclear. The brain undergoes extensive development during adolescence and disturbances at this time are hypothesized to contribute to increased vulnerability. The transition from controlled to compulsive drug use and addiction involve long-lasting changes in neural networks including a shift from the nucleus accumbens, mediating acute reinforcing effects, to recruitment of the dorsal striatum and habit formation. This study aimed to test the hypothesis of increased dopamine release after a pharmacological challenge in adolescent rats. Potassium-evoked dopamine release and uptake was investigated using chronoamperometric dopamine recordings in combination with a challenge by amphetamine in early and late adolescent rats and in adult rats. In addition, the consequences of voluntary alcohol intake during adolescence on these effects were investigated. The data show a gradual increase of evoked dopamine release with age, supporting previous studies suggesting that the pool of releasable dopamine increases with age. In contrast, a gradual decrease in evoked release with age was seen in response to amphetamine, supporting a proportionally larger storage pool of dopamine in younger animals. Dopamine measures after voluntary alcohol intake resulted in lower release amplitudes in response to potassium-chloride, indicating that alcohol affects the releasable pool of dopamine and this may have implications for vulnerability to addiction and other psychiatric diagnoses involving dopamine in the dorsal striatum. PMID:24788731

  19. 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

  20. Binding of [(3)H]lysergic acid diethylamide to serotonin 5-HT(2A) receptors and of [(3)H]paroxetine to serotonin uptake sites in platelets from healthy children, adolescents and adults.

    PubMed

    Sigurdh, J; Spigset, O; Allard, P; Mjörndal, T; Hägglöf, B

    1999-11-01

    Possible age effects on binding of [(3)H]lysergic acid diethylamide ([(3)H]LSD) to serotonin 5-HT(2A) receptors and of [(3)H]paroxetine to serotonin uptake sites were studied in platelets from healthy children (11-12 years of age), adolescents (16-17 years of age) and adults. Significant overall age effects were found both for the number of binding sites (B(max)) for [(3)H]LSD binding (p < 0.001), the affinity constant (K(d)) for [(3)H]LSD binding (p < 0.001), B(max) for [(3)H]paroxetine binding (p < 0.001) and K(d) for [(3)H] paroxetine binding (p = 0.006). In general, there was a decrease in B(max) with increasing age, which predominantly occurred between the ages 11-12 years and 16-17 years for the 5-HT(2A) receptor, and after 16-17 years of age for the serotonin uptake site. These developmental changes might have an impact on the effect of treatment with serotonergic drugs in children and adolescents. When the platelet serotonin variables investigated are employed in studies in children or adolescents, age matching or, alternatively, introduction of age control in the statistical analysis should be performed.

  1. 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

  2. Atrial Natriuretic Peptide Stimulates Dopamine Tubular Transport by Organic Cation Transporters: A Novel Mechanism to Enhance Renal Sodium Excretion

    PubMed Central

    Kouyoumdzian, Nicolás M.; Rukavina Mikusic, Natalia L.; Kravetz, María C.; Lee, Brenda M.; Carranza, Andrea; Del Mauro, Julieta S.; Pandolfo, Marcela; Gironacci, Mariela M.; Gorzalczany, Susana; Toblli, Jorge E.; Fernández, Belisario E.

    2016-01-01

    The aim of this study was to demonstrate the effects of atrial natriuretic peptide (ANP) on organic cation transporters (OCTs) expression and activity, and its consequences on dopamine urinary levels, Na+, K+-ATPase activity and renal function. Male Sprague Dawley rats were infused with isotonic saline solution during 120 minutes and randomized in nine different groups: control, pargyline plus tolcapone (P+T), ANP, dopamine (DA), D-22, DA+D-22, ANP+D-22, ANP+DA and ANP+DA+D-22. Renal functional parameters were determined and urinary dopamine concentration was quantified by HPLC. Expression of OCTs and D1-receptor in membrane preparations from renal cortex tissues were determined by western blot and Na+, K+-ATPase activity was determined using in vitro enzyme assay. 3H-DA renal uptake was determined in vitro. Compared to P+T group, ANP and dopamine infusion increased diuresis, urinary sodium and dopamine excretion significantly. These effects were more pronounced in ANP+DA group and reversed by OCTs blockade by D-22, demonstrating that OCTs are implied in ANP stimulated-DA uptake and transport in renal tissues. The activity of Na+, K+-ATPase exhibited a similar fashion when it was measured in the same experimental groups. Although OCTs and D1-receptor protein expression were not modified by ANP, OCTs-dependent-dopamine tubular uptake was increased by ANP through activation of NPR-A receptor and protein kinase G as signaling pathway. This effect was reflected by an increase in urinary dopamine excretion, natriuresis, diuresis and decreased Na+, K+-ATPase activity. OCTs represent a novel target that links the activity of ANP and dopamine together in a common mechanism to enhance their natriuretic and diuretic effects. PMID:27392042

  3. CNS Dopamine Transmission Mediated by Noradrenergic Innervation

    PubMed Central

    Smith, Caroline C.; Greene, Robert W.

    2012-01-01

    The pre-synaptic source of dopamine in the CA1 field of dorsal hippocampus is uncertain due to an anatomical mismatch between dopaminergic terminals and receptors. We show, in an in vitro slice preparation from C57BL6 male mice, that a dopamine (DA) D1 receptor (D1R) mediated enhancement in glutamate synaptic transmission occurs following release of endogenous DA with amphetamine exposure. It is assumed DA is released from terminals innervating from the ventral tegmental area (VTA) even though DA transporter (DAT) positive fibers are absent in hippocampus, a region with abundant D1Rs. It has been suggested this results from a lack of DAT expression on VTA terminals rather than a lack of these terminals per se. Neither a knockdown of tyrosine hydroxylase (TH) expression in the VTA by THsiRNA, delivered locally, by adeno-associated viral vector, nor localized pharmacological blockade of DAT to prevent amphetamine uptake into DA terminals, has any effect on the D1R synaptic, enhancement response to amphetamine. However, either a decrease in TH expression in the locus coeruleus (LC) or a blockade of the norepinephrine (NE) transporter prevents the DA mediated response, indicating LC terminals can release both NE and DA. These findings suggest noradrenergic fibers may be the primary source of DA release in hippocampus and corresponding DA mediated increase in synaptic transmission. Accordingly, these data imply the LC may have a role in DA transmission in the CNS in response to drugs of abuse, and potentially, under physiological conditions. PMID:22553014

  4. 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. PMID:26921458

  5. 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

  6. 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.

  7. Significant enhancement of gas uptake capacity and selectivity via the judicious increase of open metal sites and Lewis basic sites within two polyhedron-based metal-organic frameworks.

    PubMed

    Liu, Bing; Yao, Shuo; Shi, Chao; Li, Guanghua; Huo, Qisheng; Liu, Yunling

    2016-02-21

    Two new isomorphous polyhedron-based MOFs ( and ), with dual functionalities of OMSs and LBSs, have been synthesized by using the SBB strategy. By judiciously avoiding the DABCO axial ligand, possesses more OMSs than , and exhibits a significant enhancement of CO2 uptake capacity 210 versus 162 cm(3) g(-1) for at 273 K under 1 bar.

  8. Dopamine-dependent responses to morphine depend on glucocorticoid receptors

    PubMed Central

    Marinelli, Michela; Aouizerate, Bruno; Barrot, Michel; Le Moal, Michel; Piazza, Pier Vincenzo

    1998-01-01

    Previous work has shown that glucocorticoid hormones facilitate the behavioral and dopaminergic effects of morphine. In this study we examined the possible role in these effects of the two central corticosteroid receptor types: mineralocorticoid receptor (MR), and glucocorticoid receptor (GR). To accomplish this, specific antagonists of these receptors were infused intracerebroventricularly and 2 hr later we measured: (i) locomotor activity induced by a systemic injection of morphine (2 mg/kg); (ii) locomotor activity induced by an infusion of morphine (1 μg per side) into the ventral tegmental area, which is a dopamine-dependent behavioral response to morphine; (iii) morphine-induced dopamine release in the nucleus accumbens, a dopaminergic projection site mediating the locomotor and reinforcing effects of drugs of abuse. Blockade of MRs by spironolactone had no significant effects on locomotion induced by systemic morphine. In contrast, blockade of GRs by either RU38486 or RU39305, which is devoid of antiprogesterone effects, reduced the locomotor response to morphine, and this effect was dose dependent. GR antagonists also reduced the locomotor response to intraventral tegmental area morphine as well as the basal and morphine-induced increase in accumbens dopamine, as measured by microdialysis in freely moving rats. In contrast, spironolactone did not modify dopamine release. In conclusion, glucocorticoids, via GRs, facilitate the dopamine-dependent behavioral effects of morphine, probably by facilitating dopamine release. The possibility of decreasing the behavioral and dopaminergic effects of opioids by an acute administration of GR antagonists may open new therapeutic strategies for treatment of drug addiction. PMID:9636221

  9. Dopamine denervation does not alter in vivo /sup 3/H-spiperone binding in rat striatum: implications for external imaging of dopamine receptors in Parkinson's disease

    SciTech Connect

    Bennett, J.P. Jr.; Wooten, G.F.

    1986-04-01

    Striatal particulate preparations, both from rats with lesion-induced striatal dopamine (DA) loss and from some striatal dopamine (DA) loss and from some patients with Parkinson's disease, exhibit increased /sup 3/H-neuroleptic binding, which is interpreted to be the mechanism of denervation-induced behavioral supersensitivity to dopaminergic compounds. After intravenous /sup 3/H-spiperone (/sup 3/H-SP) administration to rats with unilateral nigral lesions, we found no differences in accumulation of total or particulate-bound /sup 3/H-SP in dopamine-denervated compared with intact striata. /sup 3/H-SP in vivo binds to less than 10% of striatal sites labeled by /sup 3/H-SP incubated with striatal particulate preparations in vitro. Quantitative autoradiography of /sup 3/H-SP binding to striatal sections in vitro also failed to reveal any effects of dopamine denervation. /sup 3/H-SP bound to striatal sites in vivo dissociates more slowly than that bound to striatal particulate preparations labeled in vitro. Striatal binding properties of /sup 3/H-SP administered in vivo are quite different from the same kinetic binding parameters estimated in vitro using crude membrane preparations of striatum. In addition, striatal binding of in vivo-administered 3H-SP is not affected by prior lesion of the substantia nigra, which results in profound ipsilateral striatal dopamine depletion. Thus, behavioral supersensitivity to dopaminergic compounds may not be associated with altered striatal binding properties for dopamine receptor ligands in vivo.

  10. 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

  11. Pharmacological and biochemical characterization of the D-1 dopamine receptor mediating acetylcholine release in rabbit retina

    SciTech Connect

    Hensler, J.G.; Cotterell, D.J.; Dubocovich, M.L.

    1987-12-01

    Superfusion with dopamine (0.1 microM-10 mM) evokes calcium-dependent (/sup 3/H)acetylcholine release from rabbit retina labeled in vitro with (/sup 3/H)choline. This effect is antagonized by the D-1 dopamine receptor antagonist SCH 23390. Activation or blockade of D-2 dopamine, alpha-2 or beta receptors did not stimulate or attenuate the release of (/sup 3/H)acetylcholine from rabbit retina. Dopamine receptor agonists evoke the release of (/sup 3/H)acetylcholine with the following order of potency: apomorphine less than or equal to SKF(R)82526 < SKF 85174 < SKF(R)38393 less than or equal to pergolide less than or equal to dopamine (EC50 = 4.5 microM) < SKF(S)82526 less than or equal to SKF(S)38393. Dopamine receptor antagonists inhibited the dopamine-evoked release of (/sup 3/H)acetylcholine: SCH 23390 (IC50 = 1 nM) < (+)-butaclamol less than or equal to cis-flupenthixol < fluphenazine < perphenazine < trans-flupenthixol < R-sulpiride. The potencies of dopamine receptor agonists and antagonists at the dopamine receptor mediating (/sup 3/H)acetylcholine release is characteristic of the D-1 dopamine receptor. These potencies were correlated with the potencies of dopamine receptor agonists and antagonists at the D-1 dopamine receptor in rabbit retina as labeled by (/sup 3/H)SCH 23390, or as determined by adenylate cyclase activity. (/sup 3/H)SCH 23390 binding in rabbit retinal membranes was stable, saturable and reversible. Scatchard analysis of (/sup 3/H)SCH 23390 saturation data revealed a single high affinity binding site (Kd = 0.175 +/- 0.002 nM) with a maximum binding of 482 +/- 12 fmol/mg of protein. The potencies of dopamine receptor agonists to stimulate (/sup 3/H)acetylcholine release were correlated with their potencies to stimulate adenylate cyclase (r = 0.784, P less than .05, n = 7) and with their affinities at (/sup 3/H)SCH 23390 binding sites (r = 0.755, P < .05, n = 8).

  12. Catecholamine stimulation, substrate competition, and myocardial glucose uptake in conscious dogs assessed with positron emission tomography.

    PubMed

    Merhige, M E; Ekas, R; Mossberg, K; Taegtmeyer, H; Gould, K L

    1987-11-01

    Uptake of radiolabelled deoxyglucose out of proportion to reduced coronary flow demonstrated by positron emission tomography has been used to identify reversibly ischemic, viable myocardium. For this concept to be applied reliably in the clinical setting, factors that may depress glucose availability independent of tissue viability, such as adrenergic stimulation and substrate competition, must be examined. Accordingly, we studied the effect of catecholamine stimulation by dopamine on myocardial glucose uptake in vivo using chronically instrumented, intact dogs and positron emission tomography. We measured myocardial activity of [2-18F]-2-deoxyglucose (FDG) and 82Rb in glucose-loaded animals randomly studied during dopamine infusion, during insulin infusion, and then during their combined infusion. Myocardial FDG uptake was significantly decreased when animals were treated with dopamine, compared with treatment in the same animals with insulin. When insulin was added to the dopamine infusion, myocardial FDG uptake was restored. In contrast, myocardial activity of 82Rb, which is taken up in proportion to coronary flow, was similar under all three experimental conditions. Plasma glucose, free fatty acid, and lactate concentrations were determined before and during each infusion. The depression of myocardial FDG activity seen during dopamine infusion and its reversal with addition of insulin can be explained on the basis of effects of these hormones on substrate availability and competition.

  13. New selenium-75 labeled radiopharmaceuticals: selenonium analogues of dopamine

    SciTech Connect

    Sadek, S.A.; Basmadjian, G.P.; Hsu, P.M.; Rieger, J.A.

    1983-07-01

    Selenium-75 labeled selenonium analogues of dopamine, (2-(3,4-dimethoxyphenyl)ethyl)dimethylselenonium iodide and its dihydroxy analogue, were prepared by reducing (/sup 75/Se)selenious acid with sodium borohydride at pH 6.0 and reacting the NaSeH produced with 1-(3,4-dimethoxyphenyl)-2-(p-toluenesulfonyloxy)ethane. Tissue distribution studies in rats given the /sup 75/Se-labeled selenonium agents intravenously demonstrated high initial heart uptake. Prolonged adrenal retention and high adrenal to blood ratio of compound 4 were observed. The high uptake and adrenal to blood ratio suggest the potential use of compound 4 as a radiopharmaceutical for the adrenal gland.

  14. Classic Studies on the Interaction of Cocaine and the Dopamine Transporter

    PubMed Central

    Verma, Vivek

    2015-01-01

    The dopamine transporter is responsible for recycling dopamine after release. Inhibitors of the dopamine transporter, such as cocaine, will stop the reuptake of dopamine and allow it to stay extracellularly, causing prominent changes at the molecular, cellular, and behavioral levels. There is much left to be known about the mechanism and site(s) of binding, as well as the effect that cocaine administration does to dopamine transporter-cocaine binding sites and gene expression which also plays a strong role in cocaine abusers and their behavioral characteristics. Thus, if more light is shed on the dopamine transporter-cocaine interaction, treatments for addiction and even other diseases of the dopaminergic system may not be too far ahead. As today’s ongoing research expands on the shoulders of classic research done in the 1990s and 2000s, the foundation of core research done in that time period will be reviewed, which forms the basis of today’s work and tomorrow’s therapies. PMID:26598579

  15. Amphetamine and methamphetamine reduce striatal dopamine transporter function without concurrent dopamine transporter relocalization.

    PubMed

    German, Christopher L; Hanson, Glen R; Fleckenstein, Annette E

    2012-10-01

    Amphetamine (AMPH) and methamphetamine (METH) alter dopamine transporter (DAT) function. In vitro heterologous cell line and synaptosome studies demonstrate AMPH-induced DAT internalization, implicating relocalization in reduced DAT uptake following drug exposure. However, few studies have evaluated DAT localization following in vivo AMPH/METH administration. To determine DAT subcellular localization following drug administration, a centrifugation technique was developed to isolate striatal synaptosomal membrane and vesicle fractions. DAT was distributed between the synaptosomal membrane (60%) and endosomal vesicles (40%), and in vitro application of the protein kinase C activator phorbol 12-myristate 13-acetate to striatal synaptosomes caused DAT internalization into the vesicle fractions. In contrast, neither single nor repeated in vivo AMPH and/or METH administrations altered DAT localization 5, 15, 30, or 60 min post-treatment, despite reduced DAT uptake. Importantly, repeated METH injections uniformly decreased total DAT immunoreactivity within all fractions 7 days post-treatment. These findings suggest that factors other than internalization can contribute to the observed acute and persistent DAT dysfunction and dopaminergic deficits following in vivo AMPH or METH administration.

  16. Spiperone: evidence for uptake into secretory granules.

    PubMed Central

    Dannies, P S; Rudnick, M S; Fishkes, H; Rudnick, G

    1984-01-01

    Spiperone, a dopamine antagonist widely used as a specific ligand for dopamine and serotonin receptors, is actively accumulated into the F4C1 strain of rat pituitary tumor cells. The accumulation of 10 nM [3H]spiperone was linear for 3 min and reached a steady state after 10 min. Spiperone accumulation was reduced 50% by preincubation with 5 microM reserpine, an inhibitor of biogenic amine transport into secretory granules, and was also blocked by monensin and ammonium chloride, both of which increase the pH of intracellular storage organelles. Uptake was not affected by replacing sodium in the buffer with lithium at equimolar concentrations. Spiperone at 1 microM inhibited by over 50% serotonin transport into membrane vesicles isolated from platelet dense granules; this concentration inhibited the Na+-dependent plasma membrane transport system less than 10%. The data indicate spiperone specifically interacts with the secretory granule amine transport system and suggest that this transport system is found in the F4C1 pituitary cell strain as well as in platelets and neurons. The data also suggest that experiments utilizing spiperone to measure dopamine and serotonin receptors be interpreted with caution. PMID:6584920

  17. 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

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

    PubMed

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

    2015-10-01

    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

  19. Neurotransmitter and psychostimulant recognition by the dopamine transporter.

    PubMed

    Wang, Kevin H; Penmatsa, Aravind; Gouaux, Eric

    2015-05-21

    Na(+)/Cl(-)-coupled biogenic amine transporters are the primary targets of therapeutic and abused drugs, ranging from antidepressants to the psychostimulants cocaine and amphetamines, and to their cognate substrates. Here we determine X-ray crystal structures of the Drosophila melanogaster dopamine transporter (dDAT) bound to its substrate dopamine, a substrate analogue 3,4-dichlorophenethylamine, the psychostimulants d-amphetamine and methamphetamine, or to cocaine and cocaine analogues. All ligands bind to the central binding site, located approximately halfway across the membrane bilayer, in close proximity to bound sodium and chloride ions. The central binding site recognizes three chemically distinct classes of ligands via conformational changes that accommodate varying sizes and shapes, thus illustrating molecular principles that distinguish substrates from inhibitors in biogenic amine transporters.

  20. Neurotransmitter and psychostimulant recognition by the dopamine transporter

    PubMed Central

    Wang, Kevin H.; Penmatsa, Aravind; Gouaux, Eric

    2015-01-01

    Na+/Cl−-coupled biogenic amine transporters are the primary targets of therapeutic and abused drugs, ranging from antidepressants to the psychostimulants cocaine and amphetamines, and to their cognate substrates. Here we determine x-ray crystal structures of the Drosophila melanogaster dopamine transporter (dDAT) bound to its substrate dopamine (DA), a substrate analogue 3,4-dichlorophenethylamine, the psychostimulants D-amphetamine, methamphetamine, or to cocaine and cocaine analogues. All ligands bind to the central binding site, located approximately halfway across the membrane bilayer, in close proximity to bound sodium and chloride ions. The central binding site recognizes three chemically distinct classes of ligands via conformational changes that accommodate varying sizes and shapes, thus illustrating molecular principles that distinguish substrates from inhibitors in biogenic amine transporters. PMID:25970245

  1. Effect of high potassium on dopamine receptor activity in bovine retina

    SciTech Connect

    Ackerman, J.M.

    1989-01-01

    In the present study, the hypothesis that dopamine released by light caused a subsensitivity of the dopamine receptor was investigated. Bovine eyes were obtained from a slaughterhouse, and retinas were dissected in a dark room. Filter binding assays were developed to measure agonist and antagonist binding to the dopamine receptor using ({sup 3}H)dopamine and ({sup 3}H)SCH 23390, respectively, in a retinal membrane fraction. Adenylate cyclase activation was measured by the production of ({sup 32}P)cyclic AMP from {sup 32}ATP. In desensitization experiments, bovine retinas were incubated for fifteen minutes with 56 mM potassium, which also causes a release of dopamine in retinas were washed, and membranes were prepared. The stimulation of adenylate cyclase evoked by dopamine and radiolabeled agonist and antagonist binding were measured. In the receptor binding characterization studies, the dissociation constant and the maximum number of binding sites were obtained for ({sup 3}H)dopamine and ({sup 3}H)SCH 23390 binding.

  2. Dual role of medial A10 dopamine neurons in affective encoding.

    PubMed

    Liu, Zhong-Hua; Shin, Rick; Ikemoto, Satoshi

    2008-11-01

    Increasing evidence suggests that the activation of medial A10 neurons mediates positive affective encoding. However, little is known about the functions of the inhibition of midbrain dopamine neurons. Here we show evidence suggesting that the inhibition of medial A10 neurons mediates a negative affective state, leading to negative affective encoding, whereas blunting the activation of medial A10 neurons disrupts positive affective encoding involving food reward. We used a microinjection procedure, in which the D(2) dopamine receptor agonist quinpirole was administered into the cell body region of the dopamine neurons, a procedure that reduces dopamine cell firing. Microinjections of quinpirole into the posteromedial ventral tegmental area, but not its more lateral counterparts, led to conditioned place aversion. Quinpirole administration to this site also decreased food intake and basal dopamine concentration in the ventromedial striatum, a major projection area of medial A10 neurons. In addition, moderate quinpirole doses that did not lead to conditioned place aversion or disrupt food intake abolished food-conditioned place preference, suggesting that blunting dopamine impulse activity in response to food reward disrupts positive affective encoding in associated external stimuli. Our data support the hypothesis that activation of medial A10 dopamine neurons mediates a positive affective state, leading to positive affective encoding, while their inhibition mediates a negative affective state, leading to negative affective encoding. Together with previous findings, we propose that medial A10 neurons are an important component of the mechanism via which animals learn to avoid negative incentive stimuli. PMID:18256592

  3. N-allyl epiderpride: An extremely potent SPECT radioligand for the dopamine D2 receptor

    SciTech Connect

    Kessler, R.M.; Mason, N.S.; Ansari, M.S.

    1994-05-01

    We have previously reported that epidepride is a potent (K{sub D} 24pM) and specific SPECT radioligand for the dopamine D2 receptor which can be used to study striatal and extrastriatal dopamine D2 receptors in man. We have synthesized and evaluated the N-allyl analogue of epiderpride (APID) as a potential SPECT radioligand for the dopamine D2 receptor. In comparison to epidepride it is even more potent at the dopamine D2 receptor, the K{sub D} for APID being 11 frontal cortical homogenate. The lipophilicity, evaluated using the log kw pH 7.5, was 2.9 versus 2.05 for epidepride. Competitive binding studies using rat striatal, hippocampal and frontal cortical homogenates showed high affinity for only dopamine D2 like cerebellar ratio of 275:1 at 320 minutes post injection-similar to that seen with epidepride, but with nearly four times higher brain uptake. Of interest was the off-rate from the dopamine D2 receptor; it was 0.0046 min{sup -1} in vitro at 25{degrees}C-corresponding to an t 1/2 of 150 minutes. Studies in rhesus monkeys show an in vivo off rate (following 2.5 mg/kg raclopride IV) of about 0.0082 min{sup -1} seen that with epidepride. SPECT studies in rhesus monkeys reveal APID is a promising SPECT radioligand that appears to be similar to epidepride, but with higher brain uptake due to its more optimal lipophilicity for entry into brain.

  4. Corticosterone Acts in the Nucleus Accumbens to Enhance Dopamine Signaling and Potentiate Reinstatement of Cocaine Seeking

    PubMed Central

    Graf, Evan N.; Wheeler, Robert A.; Baker, David A.; Ebben, Amanda L.; Hill, Jonathan E.; McReynolds, Jayme R.; Robble, Mykel A.; Vranjkovic, Oliver; Wheeler, Daniel S.; Mantsch, John R.

    2013-01-01

    Stressful life events are important contributors to relapse in recovering cocaine addicts, but the mechanisms by which they influence motivational systems are poorly understood. Studies suggest that stress may “set the stage” for relapse by increasing the sensitivity of brain reward circuits to drug-associated stimuli. We examined the effects of stress and corticosterone on behavioral and neurochemical responses of rats to a cocaine prime after cocaine self-administration and extinction. Exposure of rats to acute electric footshock stress did not by itself reinstate drug-seeking behavior but potentiated reinstatement in response to a subthreshold dose of cocaine. This effect of stress was not observed in adrenalectomized animals, and was reproduced in nonstressed animals by administration of corticosterone at a dose that reproduced stress-induced plasma levels. Pretreatment with the glucocorticoid receptor antagonist RU38486 did not block the corticosterone effect. Corticosterone potentiated cocaine-induced increases in extracellular dopamine in the nucleus accumbens (NAc), and pharmacological blockade of NAc dopamine receptors blocked corticosterone-induced potentiation of reinstatement. Intra-accumbens administration of corticosterone reproduced the behavioral effects of stress and systemic corticosterone. Corticosterone treatment acutely decreased NAc dopamine clearance measured by fast-scan cyclic voltammetry, suggesting that inhibition of uptake2-mediated dopamine clearance may underlie corticosterone effects. Consistent with this hypothesis, intra-accumbens administration of the uptake2 inhibitor normetanephrine potentiated cocaine-induced reinstatement. Expression of organic cation transporter 3, a corticosterone-sensitive uptake2 transporter, was detected on NAc neurons. These findings reveal a novel mechanism by which stress hormones can rapidly regulate dopamine signaling and contribute to the impact of stress on drug intake. PMID:23864669

  5. Multiple Fragment Docking and Linking in Primary and Secondary Pockets of Dopamine Receptors

    PubMed Central

    2014-01-01

    A sequential docking methodology was applied to computationally predict starting points for fragment linking using the human dopamine D3 receptor crystal structure and a human dopamine D2 receptor homology model. Two focused fragment libraries were docked in the primary and secondary binding sites, and best fragment combinations were enumerated. Similar top scoring fragments were found for the primary site, while secondary site fragments were predicted to convey selectivity. Three linked compounds were synthesized that had 9-, 39-, and 55-fold selectivity in favor of D3 and the subtype selectivity of the compounds was assessed on a structural basis. PMID:25221658

  6. Mesocortical Dopamine Phenotypes in Mice Lacking the Sonic Hedgehog Receptor Cdon.

    PubMed

    Verwey, Michael; Grant, Alanna; Meti, Nicholas; Adye-White, Lauren; Torres-Berrío, Angelica; Rioux, Veronique; Lévesque, Martin; Charron, Frederic; Flores, Cecilia

    2016-01-01

    Motivated behaviors and many psychopathologies typically involve changes in dopamine release from the projections of the ventral tegmental area (VTA) and/or the substantia nigra pars compacta (SNc). The morphogen Sonic Hedgehog (Shh) specifies fates of midbrain dopamine neurons, but VTA-specific effects of Shh signaling are also being uncovered. In this study, we assessed the role of the Shh receptor Cdon in the development of VTA and SNc dopamine neurons. We find that Cdon is expressed in the proliferating progenitor zone of the embryonic ventral midbrain and that the number of proliferating cells in this region is increased in mouse Cdon(-/-) embryos. Consistent with a role of Shh in the regulation of neuronal proliferation in this region, we find that the number of tyrosine hydroxylase (TH)-positive neurons is increased in the VTA of Cdon(-/-) mice at birth and that this effect endures into adulthood. In contrast, the number of TH-positive neurons in the SNc is not altered in Cdon(-/-) mice at either age. Moreover, adult Cdon(-/-) mice have a greater number of medial prefrontal cortex (mPFC) dopamine presynaptic sites, and increased baseline concentrations of dopamine and dopamine metabolites selectively in this region. Finally, consistent with increased dopamine function in the mPFC, we find that adult Cdon(-/-) mice fail to exhibit behavioral plasticity upon repeated amphetamine treatment. Based on these data, we suggest that Cdon plays an important role encoding the diversity of dopamine neurons in the midbrain, influencing both the development of the mesocortical dopamine pathway and behavioral outputs that involve this neural circuitry. PMID:27419218

  7. Mesocortical Dopamine Phenotypes in Mice Lacking the Sonic Hedgehog Receptor Cdon

    PubMed Central

    Grant, Alanna; Meti, Nicholas; Adye-White, Lauren; Rioux, Veronique

    2016-01-01

    Abstract Motivated behaviors and many psychopathologies typically involve changes in dopamine release from the projections of the ventral tegmental area (VTA) and/or the substantia nigra pars compacta (SNc). The morphogen Sonic Hedgehog (Shh) specifies fates of midbrain dopamine neurons, but VTA-specific effects of Shh signaling are also being uncovered. In this study, we assessed the role of the Shh receptor Cdon in the development of VTA and SNc dopamine neurons. We find that Cdon is expressed in the proliferating progenitor zone of the embryonic ventral midbrain and that the number of proliferating cells in this region is increased in mouse Cdon−/− embryos. Consistent with a role of Shh in the regulation of neuronal proliferation in this region, we find that the number of tyrosine hydroxylase (TH)-positive neurons is increased in the VTA of Cdon−/− mice at birth and that this effect endures into adulthood. In contrast, the number of TH-positive neurons in the SNc is not altered in Cdon−/− mice at either age. Moreover, adult Cdon−/− mice have a greater number of medial prefrontal cortex (mPFC) dopamine presynaptic sites, and increased baseline concentrations of dopamine and dopamine metabolites selectively in this region. Finally, consistent with increased dopamine function in the mPFC, we find that adult Cdon−/− mice fail to exhibit behavioral plasticity upon repeated amphetamine treatment. Based on these data, we suggest that Cdon plays an important role encoding the diversity of dopamine neurons in the midbrain, influencing both the development of the mesocortical dopamine pathway and behavioral outputs that involve this neural circuitry. PMID:27419218

  8. Chronic intrastriatal dopamine infusions in rats with unilateral lesions of the substantia nigra

    SciTech Connect

    Hargraves, R.; Freed, W.J.

    1987-03-09

    This study examined the effects of continuously supplied dopamine delivered directly into the dopamine-deficient striatum. Rats received unilateral lesions of the substantia nigra by stereotaxic administration of 6-hydroxydopamine and were tested for apomorphine-induced rotational behavior and general activity. Osmotic mini-pumps were filled with dopamine in various concentrations, implanted subcutaneously and connected to a cannula implanted directly into the striatum. The system delivered solution at a rate of .5 ..mu..l/hr for two weeks. Dopamine in a dosage of 0.5 ..mu..g/per hour reduced apomorphine-induced rotational behavior by a mean of 52 +/- 5.8% (mean +/- SEM n=20) with a maximal individual decrease of 99%. There was no change in general activity or increase in stereotype behavior. Infusions of vehicle solutions did not decrease rotational behavior. Spread of the infused dopamine and its metabolites was estimated by adding /sup 3/H-dopamine to the pumps in tracer quantities. Radioactivity was highly concentrated at the infusion site and decreased rapidly within a few mm from the infusion site. Continuous infusion methods may eventually prove to be effective in the treatment of nigro-striatal degenerative disease. 12 references, 4 figures.

  9. An uptake of cationized ferritin by alveolar type I cells in airway-instilled goat lung: distribution of anionic sites on the epithelial surface.

    PubMed

    Atwal, O S; Viel, L; Minhas, K J

    1990-07-01

    The present study has investigated ultrastructural localization of anionic sites on the luminal surface of the alveolar epithelium of goat lung by direct airway instillation of cationized ferritin (CF) in the cranial lobe of the right lung through a bronchoscope. The cationic probe decorated preferentially the luminal plasmalemmal vesicles and plasmalemma proper of alveolar type I cell. This indicated the presence of highly charged anionic microdomains at these binding sites. The ligand was internalized in the free plasmalemmal vesicles of alveolar type I cell within 2 min. Heavy decoration of vesicles at 5 min of perfusion indicated that the amount of CF internalization increased with its concentration in the alveoli. It is suggested that exposure of alveolar surface to several gases of ruminal-origin induces changes in the surface charge of luminal plasmalemma of alveolar type I cells. The significance of these anionic plasmalemmal sites is discussed in relation to the adjustment of osmotic pressure gradient across the alveolar-capillary membrane of the ruminant lung.

  10. An uptake of cationized ferritin by alveolar type I cells in airway-instilled goat lung: distribution of anionic sites on the epithelial surface.

    PubMed

    Atwal, O S; Viel, L; Minhas, K J

    1990-07-01

    The present study has investigated ultrastructural localization of anionic sites on the luminal surface of the alveolar epithelium of goat lung by direct airway instillation of cationized ferritin (CF) in the cranial lobe of the right lung through a bronchoscope. The cationic probe decorated preferentially the luminal plasmalemmal vesicles and plasmalemma proper of alveolar type I cell. This indicated the presence of highly charged anionic microdomains at these binding sites. The ligand was internalized in the free plasmalemmal vesicles of alveolar type I cell within 2 min. Heavy decoration of vesicles at 5 min of perfusion indicated that the amount of CF internalization increased with its concentration in the alveoli. It is suggested that exposure of alveolar surface to several gases of ruminal-origin induces changes in the surface charge of luminal plasmalemma of alveolar type I cells. The significance of these anionic plasmalemmal sites is discussed in relation to the adjustment of osmotic pressure gradient across the alveolar-capillary membrane of the ruminant lung. PMID:2390765

  11. Substance P Weights Striatal Dopamine Transmission Differently within the Striosome-Matrix Axis

    PubMed Central

    Brimblecombe, Katherine R.

    2015-01-01

    The mammalian striatum has a topographical organization of input–output connectivity, but a complex internal, nonlaminar neuronal architecture comprising projection neurons of two types interspersed among multiple interneuron types and potential local neuromodulators. From this cellular melange arises a biochemical compartmentalization of areas termed striosomes and extrastriosomal matrix. The functions of these compartments are poorly understood but might confer distinct features to striatal signal processing and be discretely governed. Dopamine transmission occurs throughout striosomes and matrix, and is reported to be modulated by the striosomally enriched neuromodulator substance P. However, reported effects are conflicting, ranging from facilitation to inhibition. We addressed whether dopamine transmission is modulated differently in striosome-matrix compartments by substance P. We paired detection of evoked dopamine release at carbon-fiber microelectrodes in mouse striatal slices with subsequent identification of the location of recording sites with respect to μ-opioid receptor-rich striosomes. Substance P had bidirectional effects on dopamine release that varied between recording sites and were prevented by inhibition of neurokinin-1 receptors. The direction of modulation was determined by location within the striosomal-matrix axis: dopamine release was boosted in striosome centers, diminished in striosomal-matrix border regions, and unaffected in the matrix. In turn, this different weighting of dopamine transmission by substance P modified the apparent center-surround contrast of striosomal dopamine signals. These data reveal that dopamine transmission can be differentially modulated within the striosomal-matrix axis, and furthermore, indicate a functionally distinct zone at the striosome-matrix interface, which may have key impacts on striatal integration. PMID:26085627

  12. Brain dopamine metabolism in patients with Parkinson's disease measured with positron emission tomography.

    PubMed Central

    Leenders, K L; Palmer, A J; Quinn, N; Clark, J C; Firnau, G; Garnett, E S; Nahmias, C; Jones, T; Marsden, C D

    1986-01-01

    L-[18F] fluorodopa was administered in trace amounts intravenously to healthy control subjects and to patients with Parkinson's disease. Striatal uptake of radioactivity was measured using positron emission tomography. The capacity of the striatum to retain tracer was severely impaired in patients compared to controls. This may reflect a reduction of striatal dopamine storage in Parkinson's disease. Patients showing the "on/off" phenomenon had an even greater decrease of striatal storage capacity. Images PMID:3091770

  13. Dopamine and aging: intersecting facets.

    PubMed

    Rollo, C David

    2009-04-01

    Aging encompasses life itself so understanding requires frameworks that forge unity amidst complexity. The free radical theory of aging is one example. The original focus on damage was augmented recently by appreciation that reactive oxygen and nitrogen species are essential to normal signaling and cell function. This paradigm is currently undergoing an explosive expansion fueled by the discovery that regulatory organization is a merry-go-round of redox cycling seamlessly fused to endogenous clocks. This might best be described as an "Electroplasmic Cycle." This is certainly applicable to dopaminergic neurons with their exceptional metabolic, electrical and rhythmic properties. Here I review normal aging of dopamine systems to highlight them as a valuable model. I then examine the possible integration of free radical and ion channel theories of aging. Finally, I incorporate clocks and explore the multifaceted implications of electroplasmic cycles with special emphasis on dopamine.

  14. Dopamine, uncertainty and TD learning

    PubMed Central

    Niv, Yael; Duff, Michael O; Dayan, Peter

    2005-01-01

    Substantial evidence suggests that the phasic activities of dopaminergic neurons in the primate midbrain represent a temporal difference (TD) error in predictions of future reward, with increases above and decreases below baseline consequent on positive and negative prediction errors, respectively. However, dopamine cells have very low baseline activity, which implies that the representation of these two sorts of error is asymmetric. We explore the implications of this seemingly innocuous asymmetry for the interpretation of dopaminergic firing patterns in experiments with probabilistic rewards which bring about persistent prediction errors. In particular, we show that when averaging the non-stationary prediction errors across trials, a ramping in the activity of the dopamine neurons should be apparent, whose magnitude is dependent on the learning rate. This exact phenomenon was observed in a recent experiment, though being interpreted there in antipodal terms as a within-trial encoding of uncertainty. PMID:15953384

  15. Alterations in binding site density of dopamine transporter in the striatum, orbitofrontal cortex, and amygdala in early Parkinson's disease: compartment analysis for beta-CFT binding with positron emission tomography.

    PubMed

    Ouchi, Y; Yoshikawa, E; Okada, H; Futatsubashi, M; Sekine, Y; Iyo, M; Sakamoto, M

    1999-05-01

    We investigated changes in the kinetics in the binding of the dopamine transporter probe 2-beta-carbomethoxy-3beta-(4-[11C]fluorophenyl)tropane (beta-CFT) in living brain by compartmental analysis, using positron emission tomography in unmedicated patients with Parkinson's disease (PD) (Hoehn and Yahr stages I-II). With dynamic positron emission tomographic data from 90-minute acquisitions and metabolite-corrected arterial input functions, binding potentials (k3/k4) were calculated by using estimated rate constants (K1 - k4). In this analysis, the magnitude of the distribution volume (K1/k2) measured in the cerebellum, in which specific binding is negligible, was used as a constrained value for fitting in binding regions. Statistics showed that k3/k4 values in the striatum, the orbitofrontal cortex, and the amygdala were significantly lower in PD patients than in normal controls, whereas there were no differences in K1/k2 ratios and structural volumes between the groups. Correlation analysis showed that the putaminal and orbitofrontal binding levels were correlated positively with motor and mentation scores, respectively, of the Unified Parkinson's Disease Rating Scale. These results indicated that not only the striatal but also the orbitofrontal and amygdalar presynaptic dopaminergic functions were altered in early PD. The reductions in these mesocortical/mesolimbic functions might contribute to the mental and behavioral impairment observed in PD.

  16. Rates and Determinants of Uptake and Use of an Internet Physical Activity and Weight Management Program in Office and Manufacturing Work Sites in England: Cohort Study

    PubMed Central

    Hurling, Robert; Bataveljic, Ogi; Fairley, Bruce W; Hurst, Tina L; Murray, Peter; Rennie, Kirsten L; Tomkins, Chris E; Finn, Anne; Cobain, Mark R; Pearson, Dympna A; Foreyt, John P

    2008-01-01

    Background Internet-based physical activity (PA) and weight management programs have the potential to improve employees’ health in large occupational health settings. To be successful, the program must engage a wide range of employees, especially those at risk of weight gain or ill health. Objective The aim of the study was to assess the use and nonuse (user attrition) of a Web-based and monitoring device–based PA and weight management program in a range of employees and to determine if engagement with the program was related to the employees’ baseline characteristics or measured outcomes. Methods Longitudinal observational study of a cohort of employees having access to the MiLife Web-based automated behavior change system. Employees were recruited from manufacturing and office sites in the North West and the South of England. Baseline health data were collected, and participants were given devices to monitor their weight and PA via data upload to the website. Website use, PA, and weight data were collected throughout the 12-week program. Results Overall, 12% of employees at the four sites (265/2302) agreed to participate in the program, with 130 men (49%) and 135 women (51%), and of these, 233 went on to start the program. During the program, the dropout rate was 5% (11/233). Of the remaining 222 Web program users, 173 (78%) were using the program at the end of the 12 weeks, with 69% (153/222) continuing after this period. Engagement with the program varied by site but was not significantly different between the office and factory sites. During the first 2 weeks, participants used the website, on average, 6 times per week, suggesting an initial learning period after which the frequency of website log-in was typically 2 visits per week and 7 minutes per visit. Employees who uploaded weight data had a significant reduction in weight (−2.6 kg, SD 3.2, P< .001). The reduction in weight was largest for employees using the program’s weight loss mode (−3

  17. Application of ground bone and sheep manure on soils from two contaminated sites and influence on oat growth, uranium and radium uptake and translocation

    NASA Astrophysics Data System (ADS)

    Abreu, M. M.; Pacheco, A.; Santos, E.; Magalhães, M. C. F.

    2012-04-01

    Past radium and uranium exploitation and processing in Urgeiriça mine and radium processing in Barracão (centre-north of Portugal) led to soils and waters contamination. Most of the soils, located in rural areas, are cultivated for vegetables, fruit trees, and/or pasturage, and the waters used for soils irrigation. The objective of this work was to evaluate the capacity of organic amendments and hydroxiapatite to reduce the soil available fraction of Utotal and 226Ra in soils of two areas after four months of incubation. Influence on oat growth, uranium and radium uptake and translocation was also studied. Pot experiments, under controlled conditions, were undertaken during four months of incubation at 70% of the soil water-holding capacity. Urgeiriça (Urg) and Barracão (Brc) soils containing large concentrations of Utotal (635 and 189 mg/kg, respectively), and 226Ra (2310 and 1770 Bq/kg, respectively) were used. The available fraction of these elements, extracted with ammonium acetate, corresponds to: 90 and 20% of total concentration of uranium and radium, respectively, for Urgeiriça soil, and 19 and 43% of total concentration of uranium and radium, respectively, for Barracão soil. Fine ground bone (FB), sheep manure (OM), and vermicompost (V) single or mixtures were used as amendments. Control (soil) and treatments were made in triplicate: (T1) soil+96 g FB/kg of soil; (T2) soil+168 g OM/kg of soil; (T3) soil+168 g OM/kg of soil+96 g FB/kg of soil; (T4) soil+168 g V/kg of soil. After incubation, soil subsamples were analysed for pH, electric conductivity (EC), and available fractions of Utotal and 226Ra. The remaining soils were used for oat (Avena sativa L.) cultivation. Soils had pH 5.15 (Urg) and 6.04 (Brc), and EC 57.3 µS/cm (Urg) and 36.3 µS/cm (Brc). After incubation soil pH increased to a maximum of 6.82 (Urg) and 7.10 (Brc) in amended samples, and EC showed a large increase (15-19 times) when compared to the control. A decrease of the available

  18. 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

  19. 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

  20. Greater Ethanol-Induced Locomotor Activation in DBA/2J versus C57BL/6J Mice Is Not Predicted by Presynaptic Striatal Dopamine Dynamics

    PubMed Central

    Rose, Jamie H.; Calipari, Erin S.; Mathews, Tiffany A.; Jones, Sara R.

    2013-01-01

    A large body of research has aimed to determine the neurochemical factors driving differential sensitivity to ethanol between individuals in an attempt to find predictors of ethanol abuse vulnerability. Here we find that the locomotor activating effects of ethanol are markedly greater in DBA/2J compared to C57BL/6J mice, although it is unclear as to what neurochemical differences between strains mediate this behavior. Dopamine elevations in the nucleus accumbens and caudate-putamen regulate locomotor behavior for most drugs, including ethanol; thus, we aimed to determine if differences in these regions predict strain differences in ethanol-induced locomotor activity. Previous studies suggest that ethanol interacts with the dopamine transporter, potentially mediating its locomotor activating effects; however, we found that ethanol had no effects on dopamine uptake in either strain. Ex vivo voltammetry allows for the determination of ethanol effects on presynaptic dopamine terminals, independent of drug-induced changes in firing rates of afferent inputs from either dopamine neurons or other neurotransmitter systems. However, differences in striatal dopamine dynamics did not predict the locomotor-activating effects of ethanol, since the inhibitory effects of ethanol on dopamine release were similar between strains. There were differences in presynaptic dopamine function between strains, with faster dopamine clearance in the caudate-putamen of DBA/2J mice; however, it is unclear how this difference relates to locomotor behavior. Because of the role of the dopamine system in reinforcement and reward learning, differences in dopamine signaling between the strains could have implications for addiction-related behaviors that extend beyond ethanol effects in the striatum. PMID:24349553

  1. Binding of [3H]paroxetine to serotonin uptake sites and of [3H]lysergic acid diethylamide to 5-HT2A receptors in platelets from women with premenstrual dysphoric disorder during gonadotropin releasing hormone treatment.

    PubMed

    Bixo, M; Allard, P; Bäckström, T; Mjörndal, T; Nyberg, S; Spigset, O; Sundström-Poromaa, I

    2001-08-01

    Changes in serotonergic parameters have been reported in psychiatric conditions such as depression but also in the premenstrual dysphoric disorder (PMDD). In addition, hormonal effects on serotonergic activity have been established. In the present study, binding of [3H]paroxetine to platelet serotonin uptake sites and binding of [3H]lysergic acid diethylamide ([3H]LSD) to platelet serotonin (5-HT)2A receptors were studied in patients with PMDD treated with a low dose of a gonadotropin releasing hormone (GnRH) agonist (buserelin) or placebo and compared to controls. The PMDD patients were relieved of premenstrual symptoms like depression and irritability during buserelin treatment. The number of [3H]paroxetine binding sites (Bmax) were significantly higher in the follicular phase in untreated PMDD patients compared to controls. When treated with buserelin the difference disappeared. No differences in [3H]LSD binding between the three groups were shown. The present study demonstrated altered platelet [3H]paroxetine binding characteristics in women with PMDD compared to controls. Furthermore, [3H]paroxetine binding was affected by PMDD treatment with a low dose of buserelin. The results are consistent with the hypothesis that changes in serotonergic transmission could be a trait in the premenstrual dysphoric disorder.

  2. Potential Moderating Effects of Selenium on Mercury Uptake and Selenium:Mercury Molar Ratios in Fish From Oak Ridge and Savannah River Site - 12086

    SciTech Connect

    Burger, Joanna; Gochfeld, Michael; Donio, Mark; Jeitner, Christian; Pittfield, Taryn

    2012-07-01

    Mercury contamination is an important remediation issue at the U.S. Department of Energy's (DOE) Oak Ridge Reservation and to a lesser extent at other DOE sites because of the hazard it presents, potential consequences to humans and eco-receptors, and completed pathways, to offsite receptors. Recent work has emphasized that selenium might ameliorate the toxicity of mercury, and we examine the selenium:mercury (Se:Hg) molar ratios in fish from Oak Ridge, and compare them to Se:Hg molar ratios in fish from the Savannah River. Selenium/mercury molar ratios varied considerably among and within fish species. There was considerable variation in the molar ratios for individual fish (as opposed to mean ratios by species) for freshwater fish from both sites. The inter-individual variation in molar ratios indicates that such that the molar ratios of mean Se and Hg concentrations may not be representative. Even for fish species with relatively low mercury levels, some individual fish have molar ratios less than unity, the value sometime thought to be protective. Selenium levels varied narrowly regardless of fish size, consistent with homeostatic regulation of this essential trace element. The data indicate that considerable attention will need to be directed toward variations and variances, as well as the mechanisms of the interaction of selenium and mercury, before risk assessment and risk management policies can use this information to manage mercury pollution and risk. Even so, if there are high levels of selenium in the fish from Poplar Creek on Oak Ridge, then the potential exists for some amelioration of adverse health effects, on the fish themselves, predators that eat them, and people who consume them. This work will aid DOE because it will allow managers and scientists to understand another aspect that affects fate and transport of mercury, as well as the potential effects of methylmercury in fish for human and ecological receptors. The variability within fish

  3. Differential influence of dopamine transport rate on the potencies of cocaine, amphetamine, and methylphenidate.

    PubMed

    Calipari, Erin S; Ferris, Mark J; Siciliano, Cody A; Jones, Sara R

    2015-01-21

    Dopamine transporter (DAT) levels vary across brain regions and individuals, and are altered by drug history and disease states; however, the impact of altered DAT expression on psychostimulant effects in brain has not been systematically explored. Using fast scan cyclic voltammetry, we measured the effects of elevated DAT levels on presynaptic dopamine parameters as well as the uptake inhibition potency of the blockers cocaine and methylphenidate (MPH) and the releaser amphetamine (AMPH) in the nucleus accumbens core. Here we found that increases in DAT levels, resulting from either genetic overexpression or MPH self-administration, caused markedly increased maximal rates of uptake (Vmax) that were positively correlated with the uptake inhibition potency of AMPH and MPH, but not cocaine. AMPH and MPH were particularly sensitive to DAT changes, with a 100% increase in Vmax resulting in a 200% increase in potency. The relationship between Vmax and MPH potency was the same as that for AMPH, but was different from that for cocaine, indicating that MPH more closely resembles a releaser with regard to uptake inhibition. Conversely, the effects of MPH on stimulated dopamine release were similar to those of cocaine, with inverted U-shaped increases in release over a concentration-response curve. This was strikingly different from the release profile of AMPH, which showed only reductions at high concentrations, indicating that MPH is not a pure releaser. These data indicate that although MPH is a DAT blocker, its uptake-inhibitory actions are affected by DAT changes in a similar manner to releasers. Together, these data show that fluctuations in DAT levels alter the potency of releasers and MPH but not blockers and suggest an integral role of the DAT in the addictive potential of AMPH and related compounds. PMID:25474655

  4. Differential Influence of Dopamine Transport Rate on the Potencies of Cocaine, Amphetamine, and Methylphenidate

    PubMed Central

    2015-01-01

    Dopamine transporter (DAT) levels vary across brain regions and individuals, and are altered by drug history and disease states; however, the impact of altered DAT expression on psychostimulant effects in brain has not been systematically explored. Using fast scan cyclic voltammetry, we measured the effects of elevated DAT levels on presynaptic dopamine parameters as well as the uptake inhibition potency of the blockers cocaine and methylphenidate (MPH) and the releaser amphetamine (AMPH) in the nucleus accumbens core. Here we found that increases in DAT levels, resulting from either genetic overexpression or MPH self-administration, caused markedly increased maximal rates of uptake (Vmax) that were positively correlated with the uptake inhibition potency of AMPH and MPH, but not cocaine. AMPH and MPH were particularly sensitive to DAT changes, with a 100% increase in Vmax resulting in a 200% increase in potency. The relationship between Vmax and MPH potency was the same as that for AMPH, but was different from that for cocaine, indicating that MPH more closely resembles a releaser with regard to uptake inhibition. Conversely, the effects of MPH on stimulated dopamine release were similar to those of cocaine, with inverted U-shaped increases in release over a concentration–response curve. This was strikingly different from the release profile of AMPH, which showed only reductions at high concentrations, indicating that MPH is not a pure releaser. These data indicate that although MPH is a DAT blocker, its uptake-inhibitory actions are affected by DAT changes in a similar manner to releasers. Together, these data show that fluctuations in DAT levels alter the potency of releasers and MPH but not blockers and suggest an integral role of the DAT in the addictive potential of AMPH and related compounds. PMID:25474655

  5. Dopamine: burning the candle at both ends.

    PubMed

    Pearson, John M; Platt, Michael L

    2013-09-01

    Dopamine neurons are well known for signaling reward-prediction errors. In this issue, Matsumoto and Takada (2013) show that some dopamine neurons also signal salient events during progression through a visual search task requiring working memory and sustained attention. PMID:24011998

  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. PMID:20660258

  7. Molecular Mechanism of Dopamine Transport by Human Dopamine Transporter.

    PubMed

    Cheng, Mary Hongying; Bahar, Ivet

    2015-11-01

    Dopamine transporters (DATs) control neurotransmitter dopamine (DA) homeostasis by reuptake of excess DA, assisted by sodium and chloride ions. The recent resolution of DAT structure (dDAT) from Drosophila permits us for the first time to directly view the sequence of events involved in DA reuptake in human DAT (hDAT) using homology modeling and full-atomic microseconds accelerated simulations. Major observations are spontaneous closure of extracellular gates prompted by DA binding; stabilization of a holo-occluded intermediate; disruption of N82-N353 hydrogen bond and exposure to intracellular (IC) water triggered by Na2 dislocation; redistribution of a network of salt bridges at the IC surface in the inward-facing state; concerted tilting of IC-exposed helices to enable the release of Na(+) and Cl(-) ions; and DA release after protonation of D79. The observed time-resolved interactions confirm the conserved dynamics of LeuT-fold family, while providing insights into the mechanistic role of specific residues in hDAT.

  8. 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

  9. 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.

  10. Dopamine modulates excitability of basolateral amygdala neurons in vitro.

    PubMed

    Kröner, Sven; Rosenkranz, J Amiel; Grace, Anthony A; Barrionuevo, German

    2005-03-01

    The amygdala plays a role in affective behaviors, which are modulated by the dopamine (DA) innervation of the basolateral amygdala complex (BLA). Although in vivo studies indicate that activation of DA receptors alters BLA neuronal activity, it is unclear whether DA exerts direct effects on BLA neurons or whether it acts via indirect effects on BLA afferents. Using whole cell patch-clamp recordings in rat brain slices, we investigated the site and mechanisms through which DA regulates the excitability of BLA neurons. Dopamine enhanced the excitability of BLA projection neurons in response to somatic current injections via a postsynaptic effect. Dopamine D1 receptor activation increased excitability and evoked firing, whereas D2 receptor activation increased input resistance. Current- and voltage-clamp experiments in projection neurons showed that D1 receptor activation enhanced excitability by modulating a 4-aminopyridine- and alpha-dendrotoxin-sensitive, slowly inactivating K+ current. Furthermore, DA and D1 receptor activation increased evoked firing in fast-spiking BLA interneurons. Consistent with a postsynaptic modulation of interneuron excitability, DA also increased the frequency of spontaneous inhibitory postsynaptic currents recorded in projection neurons without changing release of GABA. These data demonstrate that DA exerts direct effects on BLA projection neurons and indirect actions via modulation of interneurons that may work in concert to enhance the neuronal response to large, suprathreshold inputs, while suppressing weaker inputs. PMID:15537813

  11. Redox interactions of nitric oxide with dopamine and its derivatives.

    PubMed

    Antunes, Fernando; Nunes, Carla; Laranjinha, João; Cadenas, Enrique

    2005-03-15

    Nitric oxide (*NO) is a ubiquitous diffusible messenger in the central nervous system. *NO and derived nitrogen species may interact with catecholamines, thus, modifying not only its regulatory actions but also producing oxidants and free radicals that are likely to trigger toxic pathways in the nervous system. Oxidative pathways and chain oxidation reactions triggered by catecholamines may be broken by ascorbate and glutathione, of which there is ample supply in the brain. At the subcellular level, mitochondria and cytosolic dopamine storage vesicles are likely to provide site-specific settings for *NO and catecholamines interactions. Thus, a complex picture emerges in which the steady- state levels of the individual reactants, the rate constants of the reactions involved, the oxygen tension, and the compartmentalization of reactions determine the biological significance of the redox interactions between *NO and dopamine metabolism in the brain. The physiological relevance of *NO-driven chemical modifications of dopamine and its derivatives and the ensuing free radical production are discussed in connection with the neurodegeneration inherent in Parkinson's disease.

  12. The crystal structure of human dopamine β-hydroxylase at 2.9 Å resolution

    PubMed Central

    Vendelboe, Trine V.; Harris, Pernille; Zhao, Yuguang; Walter, Thomas S.; Harlos, Karl; El Omari, Kamel; Christensen, Hans E. M.

    2016-01-01

    The norepinephrine pathway is believed to modulate behavioral and physiological processes, such as mood, overall arousal, and attention. Furthermore, abnormalities in the pathway have been linked to numerous diseases, for example hypertension, depression, anxiety, Parkinson’s disease, schizophrenia, Alzheimer’s disease, attention deficit hyperactivity disorder, and cocaine dependence. We report the crystal structure of human dopamine β-hydroxylase, which is the enzyme converting dopamine to norepinephrine. The structure of the DOMON (dopamine β-monooxygenase N-terminal) domain, also found in >1600 other proteins, reveals a possible metal-binding site and a ligand-binding pocket. The catalytic core structure shows two different conformations: an open active site, as also seen in another member of this enzyme family [the peptidylglycine α-hydroxylating (and α-amidating) monooxygenase], and a closed active site structure, in which the two copper-binding sites are only 4 to 5 Å apart, in what might be a coupled binuclear copper site. The dimerization domain adopts a conformation that bears no resemblance to any other known protein structure. The structure provides new molecular insights into the numerous devastating disorders of both physiological and neurological origins associated with the dopamine system. PMID:27152332

  13. The crystal structure of human dopamine β-hydroxylase at 2.9 Å resolution.

    PubMed

    Vendelboe, Trine V; Harris, Pernille; Zhao, Yuguang; Walter, Thomas S; Harlos, Karl; El Omari, Kamel; Christensen, Hans E M

    2016-04-01

    The norepinephrine pathway is believed to modulate behavioral and physiological processes, such as mood, overall arousal, and attention. Furthermore, abnormalities in the pathway have been linked to numerous diseases, for example hypertension, depression, anxiety, Parkinson's disease, schizophrenia, Alzheimer's disease, attention deficit hyperactivity disorder, and cocaine dependence. We report the crystal structure of human dopamine β-hydroxylase, which is the enzyme converting dopamine to norepinephrine. The structure of the DOMON (dopamine β-monooxygenase N-terminal) domain, also found in >1600 other proteins, reveals a possible metal-binding site and a ligand-binding pocket. The catalytic core structure shows two different conformations: an open active site, as also seen in another member of this enzyme family [the peptidylglycine α-hydroxylating (and α-amidating) monooxygenase], and a closed active site structure, in which the two copper-binding sites are only 4 to 5 Å apart, in what might be a coupled binuclear copper site. The dimerization domain adopts a conformation that bears no resemblance to any other known protein structure. The structure provides new molecular insights into the numerous devastating disorders of both physiological and neurological origins associated with the dopamine system. PMID:27152332

  14. Polypharmacology of dopamine receptor ligands.

    PubMed

    Butini, S; Nikolic, K; Kassel, S; Brückmann, H; Filipic, S; Agbaba, D; Gemma, S; Brogi, S; Brindisi, M; Campiani, G; Stark, H

    2016-07-01

    Most neurological diseases have a multifactorial nature and the number of molecular mechanisms discovered as underpinning these diseases is continuously evolving. The old concept of developing selective agents for a single target does not fit with the medical need of most neurological diseases. The development of designed multiple ligands holds great promises and appears as the next step in drug development for the treatment of these multifactorial diseases. Dopamine and its five receptor subtypes are intimately involved in numerous neurological disorders. Dopamine receptor ligands display a high degree of cross interactions with many other targets including G-protein coupled receptors, transporters, enzymes and ion channels. For brain disorders like Parkinsońs disease, schizophrenia and depression the dopaminergic system, being intertwined with many other signaling systems, plays a key role in pathogenesis and therapy. The concept of designed multiple ligands and polypharmacology, which perfectly meets the therapeutic needs for these brain disorders, is herein discussed as a general ligand-based concept while focusing on dopaminergic agents and receptor subtypes in particular. PMID:27234980

  15. Dopamine transporter inhibitory and antiparkinsonian effect of common flowering quince extract.

    PubMed

    Zhao, Gang; Jiang, Zhi-Hua; Zheng, Xiang-Wei; Zang, Shao-Yun; Guo, Li-He

    2008-09-01

    Common flowering quince (FQ) is the fruit of Chaenomeles speciosa (Sweet) Nakai. FQ-containing cocktails have been applied to the treatment of neuralgia, migraine, and depression in traditional Chinese medicine. The present study assessed whether FQ is effective in dopamine transporter (DAT) regulation and antiparkinsonism by utilizing in vitro and in vivo assays, respectively. FQ at concentrations of 1-1000 microg/ml concentration-dependently inhibited dopamine uptake by Chinese hamster ovary (CHO) cells stably expressing DAT (D8 cells) and by synaptosomes. FQ had a slight inhibitory action on norepinephrine uptake by CHO cells expressing the norepinephrine transporter and no inhibitory effect on gamma-aminobutyric acid (GABA) uptake by CHO cells expressing GABA transporter-1 or serotonin uptake by the serotonin transporter. A viability assay showed that FQ mitigated 1-methyl-4-phenylpyridinium-induced toxicity in D8 cells. Furthermore, in behavioral studies, FQ alleviated rotational behavior in 6-hydroxydopamine-treated rats and improved deficits in endurance performance in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice. Furthermore, immunohistochemistry revealed that FQ markedly reduced the loss of tyrosine hydroxylase-positive neurons in the substantia nigra in MPTP-treated mice. In summary, FQ is a selective, potent DAT inhibitor and has antiparkinsonian-like effects that are mediated possibly by DAT suppression. FQ has the potential to be further developed for Parkinson's disease treatment.

  16. Cystathionine γ lyase-hydrogen sulfide increases peroxisome proliferator-activated receptor γ activity by sulfhydration at C139 site thereby promoting glucose uptake and lipid storage in adipocytes.

    PubMed

    Cai, Junyan; Shi, Xiaoqin; Wang, Huamin; Fan, Jinghui; Feng, Yongliang; Lin, Xianjuan; Yang, Jichun; Cui, Qinghua; Tang, Chaoshu; Xu, Guoheng; Geng, Bin

    2016-05-01

    Adipocytes express the cystathionine γ lyase (CSE)-hydrogen sulfide (H2S) system. CSE-H2S promotes adipogenesis but ameliorates adipocyte insulin resistance. We investigated the mechanism of how CSE-H2S induces these paradoxical effects. First, we confirmed that an H2S donor or CSE overexpression promoted adipocyte differentiation. Second, we found that H2S donor inhibited but CSE inhibition increased phosphodiesterase (PDE) activity. H2S replacing isobutylmethylxanthine in the differentiation program induced adipocyte differentiation in part. Inhibiting PDE activity by H2S induced peroxisome proliferator activated receptor γ (PPARγ) protein and mRNA expression. Of note, H2S directly sulfhydrated PPARγ protein. Sulfhydrated PPARγ increased its nuclear accumulation, DNA binding activity and adipogenesis gene expression, thereby increasing glucose uptake and lipid storage, which were blocked by the desulfhydration reagent DTT. H2S induced PPARγ sulfhydration, which was blocked by mutation of the C139 site of PPARγ. In mice fed a high-fat diet (HFD) for 4 weeks, the CSE inhibitor decreased but H2S donor increased adipocyte numbers. In obese mice fed an HFD for 13 weeks, H2S treatment increased PPARγ sulfhydration in adipose tissues and attenuated insulin resistance but did not increase obesity. In conclusion, CSE-H2S increased PPARγ activity by direct sulfhydration at the C139 site, thereby changing glucose into triglyceride storage in adipocytes. CSE-H2S-mediated PPARγ activation might be a new therapeutic target for diabetes associated with obesity. PMID:26946260

  17. Cystathionine γ lyase-hydrogen sulfide increases peroxisome proliferator-activated receptor γ activity by sulfhydration at C139 site thereby promoting glucose uptake and lipid storage in adipocytes.

    PubMed

    Cai, Junyan; Shi, Xiaoqin; Wang, Huamin; Fan, Jinghui; Feng, Yongliang; Lin, Xianjuan; Yang, Jichun; Cui, Qinghua; Tang, Chaoshu; Xu, Guoheng; Geng, Bin

    2016-05-01

    Adipocytes express the cystathionine γ lyase (CSE)-hydrogen sulfide (H2S) system. CSE-H2S promotes adipogenesis but ameliorates adipocyte insulin resistance. We investigated the mechanism of how CSE-H2S induces these paradoxical effects. First, we confirmed that an H2S donor or CSE overexpression promoted adipocyte differentiation. Second, we found that H2S donor inhibited but CSE inhibition increased phosphodiesterase (PDE) activity. H2S replacing isobutylmethylxanthine in the differentiation program induced adipocyte differentiation in part. Inhibiting PDE activity by H2S induced peroxisome proliferator activated receptor γ (PPARγ) protein and mRNA expression. Of note, H2S directly sulfhydrated PPARγ protein. Sulfhydrated PPARγ increased its nuclear accumulation, DNA binding activity and adipogenesis gene expression, thereby increasing glucose uptake and lipid storage, which were blocked by the desulfhydration reagent DTT. H2S induced PPARγ sulfhydration, which was blocked by mutation of the C139 site of PPARγ. In mice fed a high-fat diet (HFD) for 4 weeks, the CSE inhibitor decreased but H2S donor increased adipocyte numbers. In obese mice fed an HFD for 13 weeks, H2S treatment increased PPARγ sulfhydration in adipose tissues and attenuated insulin resistance but did not increase obesity. In conclusion, CSE-H2S increased PPARγ activity by direct sulfhydration at the C139 site, thereby changing glucose into triglyceride storage in adipocytes. CSE-H2S-mediated PPARγ activation might be a new therapeutic target for diabetes associated with obesity.

  18. Orbitofrontal (18) F-DOPA Uptake and Movement Preparation in Parkinson's Disease.

    PubMed

    Marinelli, Lucio; Piccardo, Arnoldo; Mori, Laura; Morbelli, Silvia; Girtler, Nicola; Castaldi, Antonio; Picco, Agnese; Trompetto, Carlo; Ghilardi, Maria Felice; Abbruzzese, Giovanni; Nobili, Flavio

    2015-01-01

    In Parkinson's disease (PD) degeneration of mesocortical dopaminergic projections may determine cognitive and behavioral symptoms. Choice reaction time task is related to attention, working memory, and goal-directed behavior. Such paradigm involves frontal cortical circuits receiving mesocortical dopamine which are affected early in PD. The aim of this study is to characterize the role of dopamine on the cognitive processes that precede movement in a reaction time paradigm in PD. We enrolled 16 newly diagnosed and untreated patients with PD without cognitive impairment or depression and 10 control subjects with essential tremor. They performed multiple-choice reaction time task with the right upper limb and brain (18)F-DOPA PET/CT scan. A significant inverse correlation was highlighted between average reaction time and (18)F-DOPA uptake in the left lateral orbitofrontal cortex. No correlations were found between reaction time and PD disease severity or between reaction time and (18)F-DOPA uptake in controls. Our study shows that in PD, but not in controls, reaction time is inversely related to the levels of dopamine in the left lateral orbitofrontal cortex. This novel finding underlines the role of dopamine in the lateral orbitofrontal cortex in the early stages of PD, supporting a relation between the compensatory cortical dopamine and movement preparation. PMID:26171275

  19. Effects of the monoamine uptake inhibitors RTI-112 and RTI-113 on cocaine- and food-maintained responding in rhesus monkeys.

    PubMed

    Negus, S S; Mello, N K; Kimmel, H L; Howell, L L; Carroll, F I

    2009-01-01

    Cocaine blocks uptake of the monoamines dopamine, serotonin and norepinephrine, and monoamine uptake inhibitors constitute one class of drugs under consideration as candidate "agonist" medications for the treatment of cocaine abuse and dependence. The pharmacological selectivity of monoamine uptake inhibitors to block uptake of dopamine, serotonin and norepinephrine is one factor that may influence the efficacy and/or safety of these compounds as drug abuse treatment medications. To address this issue, the present study compared the effects of 7-day treatment with a non-selective monoamine uptake inhibitor (RTI-112) and a dopamine-selective uptake inhibitor (RTI-113) on cocaine- and food-maintained responding in rhesus monkeys. Monkeys (N=3) were trained to respond for cocaine injections (0.01 mg/kg/inj) and food pellets under a second-order schedule [FR2(VR16:S)] during alternating daily components of cocaine and food availability. Both RTI-112 (0.0032-0.01 mg/kg/hr) and RTI-113 (0.01-0.056 mg/kg/h) produced dose-dependent, sustained and nearly complete elimination of cocaine self-administration. However, for both drugs, the potency to reduce cocaine self-administration was similar to the potency to reduce food-maintained responding. These findings do not support the hypothesis that pharmacological selectivity to block dopamine uptake is associated with behavioral selectivity to decrease cocaine- vs. food-maintained responding in rhesus monkeys. PMID:18755212

  20. Does the dopamine hypothesis explain schizophrenia?

    PubMed

    Lau, Chi-Ieong; Wang, Han-Cheng; Hsu, Jung-Lung; Liu, Mu-En

    2013-01-01

    The dopamine hypothesis has been the cornerstone in the research and clinical practice of schizophrenia. With the initial emphasis on the role of excessive dopamine, the hypothesis has evolved to a concept of combining prefrontal hypodopaminergia and striatal hyperdopaminergia, and subsequently to the present aberrant salience hypothesis. This article provides a brief overview of the development and evidence of the dopamine hypothesis. It will argue that the current model of aberrant salience explains psychosis in schizophrenia and provides a plausible linkage between the pharmacological and cognitive aspects of the disease. Despite the privileged role of dopamine hypothesis in psychosis, its pathophysiological rather than etiological basis, its limitations in defining symptoms other than psychosis, as well as the evidence of other neurotransmitters such as glutamate and adenosine, prompt us to a wider perspective of the disease. Finally, dopamine does explain the pathophysiology of schizophrenia, but not necessarily the cause per se. Rather, dopamine acts as the common final pathway of a wide variety of predisposing factors, either environmental, genetic, or both, that lead to the disease. Other neurotransmitters, such as glutamate and adenosine, may also collaborate with dopamine to give rise to the entire picture of schizophrenia. PMID:23843581

  1. Dopamine receptor partial agonists and addiction.

    PubMed

    Moreira, Fabricio A; Dalley, Jeffrey W

    2015-04-01

    Many drugs abused by humans acutely facilitate, either directly or indirectly, dopamine neurotransmission in the mesolimbic pathway. As a consequence dopamine receptor agonists and antagonists have been widely investigated as putative pharmacological therapies for addiction. This general strategy, however, has had only limited success due in part to poor treatment adherence and efficacy and the significant adverse effects of dopaminergic medications. In this perspective, we discuss the potential therapeutic use of dopamine receptor partial agonists in addiction, developed initially as antipsychotic agents. Recent research indicates that the dopamine D2 receptor partial agonists, such as aripiprazole, also shows useful ancillary efficacy in several animal models of psychostimulant and opioid addiction. Notably, these findings suggest that unlike full dopamine receptor agonists and antagonists these compounds have low abuse liability and are generally well tolerated. Indeed, partial dopamine agonists attenuate the rewarding properties of opioids without interfering with their analgesic effects. Herein we discuss the utility and potential of dopamine receptor partial agonists as treatments for both stimulant and non-stimulant drug addiction.

  2. Mechanisms of amphetamine action illuminated through optical monitoring of dopamine synaptic vesicles in Drosophila brain.

    PubMed

    Freyberg, Zachary; Sonders, Mark S; Aguilar, Jenny I; Hiranita, Takato; Karam, Caline S; Flores, Jorge; Pizzo, Andrea B; Zhang, Yuchao; Farino, Zachary J; Chen, Audrey; Martin, Ciara A; Kopajtic, Theresa A; Fei, Hao; Hu, Gang; Lin, Yi-Ying; Mosharov, Eugene V; McCabe, Brian D; Freyberg, Robin; Wimalasena, Kandatege; Hsin, Ling-Wei; Sames, Dalibor; Krantz, David E; Katz, Jonathan L; Sulzer, David; Javitch, Jonathan A

    2016-02-16

    Amphetamines elevate extracellular dopamine, but the underlying mechanisms remain uncertain. Here we show in rodents that acute pharmacological inhibition of the vesicular monoamine transporter (VMAT) blocks amphetamine-induced locomotion and self-administration without impacting cocaine-induced behaviours. To study VMAT's role in mediating amphetamine action in dopamine neurons, we have used novel genetic, pharmacological and optical approaches in Drosophila melanogaster. In an ex vivo whole-brain preparation, fluorescent reporters of vesicular cargo and of vesicular pH reveal that amphetamine redistributes vesicle contents and diminishes the vesicle pH-gradient responsible for dopamine uptake and retention. This amphetamine-induced deacidification requires VMAT function and results from net H(+) antiport by VMAT out of the vesicle lumen coupled to inward amphetamine transport. Amphetamine-induced vesicle deacidification also requires functional dopamine transporter (DAT) at the plasma membrane. Thus, we find that at pharmacologically relevant concentrations, amphetamines must be actively transported by DAT and VMAT in tandem to produce psychostimulant effects.

  3. Mechanisms of amphetamine action illuminated through optical monitoring of dopamine synaptic vesicles in Drosophila brain

    PubMed Central

    Freyberg, Zachary; Sonders, Mark S.; Aguilar, Jenny I.; Hiranita, Takato; Karam, Caline S.; Flores, Jorge; Pizzo, Andrea B.; Zhang, Yuchao; Farino, Zachary J.; Chen, Audrey; Martin, Ciara A.; Kopajtic, Theresa A.; Fei, Hao; Hu, Gang; Lin, Yi-Ying; Mosharov, Eugene V.; McCabe, Brian D.; Freyberg, Robin; Wimalasena, Kandatege; Hsin, Ling-Wei; Sames, Dalibor; Krantz, David E.; Katz, Jonathan L.; Sulzer, David; Javitch, Jonathan A.

    2016-01-01

    Amphetamines elevate extracellular dopamine, but the underlying mechanisms remain uncertain. Here we show in rodents that acute pharmacological inhibition of the vesicular monoamine transporter (VMAT) blocks amphetamine-induced locomotion and self-administration without impacting cocaine-induced behaviours. To study VMAT's role in mediating amphetamine action in dopamine neurons, we have used novel genetic, pharmacological and optical approaches in Drosophila melanogaster. In an ex vivo whole-brain preparation, fluorescent reporters of vesicular cargo and of vesicular pH reveal that amphetamine redistributes vesicle contents and diminishes the vesicle pH-gradient responsible for dopamine uptake and retention. This amphetamine-induced deacidification requires VMAT function and results from net H+ antiport by VMAT out of the vesicle lumen coupled to inward amphetamine transport. Amphetamine-induced vesicle deacidification also requires functional dopamine transporter (DAT) at the plasma membrane. Thus, we find that at pharmacologically relevant concentrations, amphetamines must be actively transported by DAT and VMAT in tandem to produce psychostimulant effects. PMID:26879809

  4. Development of the dopamine transporter selective RTI-336 as a pharmacotherapy for cocaine abuse.

    PubMed

    Carroll, F Ivy; Howard, James L; Howell, Leonard L; Fox, Barbara S; Kuhar, Michael J

    2006-01-01

    The discovery and preclinical development of selective dopamine reuptake inhibitors as potential pharmacotherapies for treating cocaine addiction are presented. The studies are based on the hypothesis that a dopamine reuptake inhibitor is expected to partially substitute for cocaine, thus decreasing cocaine self-administration and minimizing the craving for cocaine. This type of indirect agonist therapy has been highly effective for treating smoking addiction (nicotine replacement therapy) and heroin addiction (methadone). To be an effective pharmacotherapy for cocaine addiction, the potential drug must be safe, long-acting, and have minimal abuse potential. We have developed several 3-phenyltropane analogs that are potent dopamine uptake inhibitors, and some are selective for the dopamine transporter relative to the serotonin and norepinephrine transporters. In animal studies, these compounds substitute for cocaine, reduce the intake of cocaine in rats and rhesus monkeys trained to self-administer cocaine, and have demonstrated a slow onset and long duration of action and lack of sensitization. The 3-phenyltropane analogs were also tested in a rhesus monkey self-administration model to define their abuse potential relative to cocaine. Based on these studies, 3beta-(4-chlorophenyl)-2beta-[3-(4'-methylphenyl)isoxazol-5-yl]tropane (RTI-336) has been selected for preclinical development. PMID:16584128

  5. Mechanisms of amphetamine action illuminated through optical monitoring of dopamine synaptic vesicles in Drosophila brain.

    PubMed

    Freyberg, Zachary; Sonders, Mark S; Aguilar, Jenny I; Hiranita, Takato; Karam, Caline S; Flores, Jorge; Pizzo, Andrea B; Zhang, Yuchao; Farino, Zachary J; Chen, Audrey; Martin, Ciara A; Kopajtic, Theresa A; Fei, Hao; Hu, Gang; Lin, Yi-Ying; Mosharov, Eugene V; McCabe, Brian D; Freyberg, Robin; Wimalasena, Kandatege; Hsin, Ling-Wei; Sames, Dalibor; Krantz, David E; Katz, Jonathan L; Sulzer, David; Javitch, Jonathan A

    2016-01-01

    Amphetamines elevate extracellular dopamine, but the underlying mechanisms remain uncertain. Here we show in rodents that acute pharmacological inhibition of the vesicular monoamine transporter (VMAT) blocks amphetamine-induced locomotion and self-administration without impacting cocaine-induced behaviours. To study VMAT's role in mediating amphetamine action in dopamine neurons, we have used novel genetic, pharmacological and optical approaches in Drosophila melanogaster. In an ex vivo whole-brain preparation, fluorescent reporters of vesicular cargo and of vesicular pH reveal that amphetamine redistributes vesicle contents and diminishes the vesicle pH-gradient responsible for dopamine uptake and retention. This amphetamine-induced deacidification requires VMAT function and results from net H(+) antiport by VMAT out of the vesicle lumen coupled to inward amphetamine transport. Amphetamine-induced vesicle deacidification also requires functional dopamine transporter (DAT) at the plasma membrane. Thus, we find that at pharmacologically relevant concentrations, amphetamines must be actively transported by DAT and VMAT in tandem to produce psychostimulant effects. PMID:26879809

  6. The role of dopamine in risk taking: a specific look at Parkinson’s disease and gambling

    PubMed Central

    Clark, Crystal A.; Dagher, Alain

    2014-01-01

    An influential model suggests that dopamine signals the difference between predicted and experienced reward. In this way, dopamine can act as a learning signal that can shape behaviors to maximize rewards and avoid punishments. Dopamine is also thought to invigorate reward seeking behavior. Loss of dopamine signaling is the major abnormality in Parkinson’s disease. Dopamine agonists have been implicated in the occurrence of impulse control disorders in Parkinson’s disease patients, the most common being pathological gambling, compulsive sexual behavior, and compulsive buying. Recently, a number of functional imaging studies investigating impulse control disorders in Parkinson’s disease have been published. Here we review this literature, and attempt to place it within a decision-making framework in which potential gains and losses are evaluated to arrive at optimum choices. We also provide a hypothetical but still incomplete model on the effect of dopamine agonist treatment on these value and risk assessments. Two of the main brain structures thought to be involved in computing aspects of reward and loss are the ventral striatum (VStr) and the insula, both dopamine projection sites. Both structures are consistently implicated in functional brain imaging studies of pathological gambling in Parkinson’s disease. PMID:24910600

  7. Contribution of dopamine to mitochondrial complex I inhibition and dopaminergic deficits caused by methylenedioxymethamphetamine in mice.

    PubMed

    Barros-Miñones, L; Goñi-Allo, B; Suquia, V; Beitia, G; Aguirre, N; Puerta, E

    2015-06-01

    Methylenedioxymethamphetamine (MDMA) causes a persistent loss of dopaminergic cell bodies in the substantia nigra of mice. Current evidence indicates that MDMA-induced neurotoxicity is mediated by oxidative stress probably due to the inhibition of mitochondrial complex I activity. In this study we investigated the contribution of dopamine (DA) to such effects. For this, we modulated the dopaminergic system of mice at the synthesis, uptake or metabolism levels. Striatal mitochondrial complex I activity was decreased 1 h after MDMA; an effect not observed in the striatum of DA depleted mice or in the hippocampus, a dopamine spare region. The DA precursor, L-dopa, caused a significant reduction of mitochondrial complex I activity by itself and exacerbated the dopaminergic deficits when combined with systemic MDMA. By contrast, no damage was observed when L-dopa was combined with intrastriatal injections of MDMA. On the other hand, dopamine uptake blockade using GBR 12909, inhibited both, the acute inhibition of complex I activity and the long-term dopaminergic toxicity caused by MDMA. Moreover, the inhibition of DA metabolism with the monoamine oxidase (MAO) inhibitor, pargyline, afforded a significant protection against MDMA-induced complex I inhibition and neurotoxicity. Taken together, these findings point to the formation of hydrogen peroxide subsequent to DA metabolism by MAO, rather than a direct DA-mediated mitochondrial complex I inhibition, and the contribution of a peripheral metabolite of MDMA, as the key steps in the chain of biochemical events leading to DA neurotoxicity caused by MDMA in mice.

  8. Predictive reward signal of dopamine neurons.

    PubMed

    Schultz, W

    1998-07-01

    The effects of lesions, receptor blocking, electrical self-stimulation, and drugs of abuse suggest that midbrain dopamine systems are involved in processing reward information and learning approach behavior. Most dopamine neurons show phasic activations after primary liquid and food rewards and conditioned, reward-predicting visual and auditory stimuli. They show biphasic, activation-depression responses after stimuli that resemble reward-predicting stimuli or are novel or particularly salient. However, only few phasic activations follow aversive stimuli. Thus dopamine neurons label environmental stimuli with appetitive value, predict and detect rewards and signal alerting and motivating events. By failing to discriminate between different rewards, dopamine neurons appear to emit an alerting message about the surprising presence or absence of rewards. All responses to rewards and reward-predicting stimuli depend on event predictability. Dopamine neurons are activated by rewarding events that are better than predicted, remain uninfluenced by events that are as good as predicted, and are depressed by events that are worse than predicted. By signaling rewards according to a prediction error, dopamine responses have the formal characteristics of a teaching signal postulated by reinforcement learning theories. Dopamine responses transfer during learning from primary rewards to reward-predicting stimuli. This may contribute to neuronal mechanisms underlying the retrograde action of rewards, one of the main puzzles in reinforcement learning. The impulse response releases a short pulse of dopamine onto many dendrites, thus broadcasting a rather global reinforcement signal to postsynaptic neurons. This signal may improve approach behavior by providing advance reward information before the behavior occurs, and may contribute to learning by modifying synaptic transmission. The dopamine reward signal is supplemented by activity in neurons in striatum, frontal cortex, and

  9. 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.

  10. Somatodendritic dopamine release: recent mechanistic insights

    PubMed Central

    Rice, Margaret E.; Patel, Jyoti C.

    2015-01-01

    Dopamine (DA) is a key transmitter in motor, reward and cogitative pathways, with DA dysfunction implicated in disorders including Parkinson's disease and addiction. Located in midbrain, DA neurons of the substantia nigra pars compacta project via the medial forebrain bundle to the dorsal striatum (caudate putamen), and DA neurons in the adjacent ventral tegmental area project to the ventral striatum (nucleus accumbens) and prefrontal cortex. In addition to classical vesicular release from axons, midbrain DA neurons exhibit DA release from their cell bodies and dendrites. Somatodendritic DA release leads to activation of D2 DA autoreceptors on DA neurons that inhibit their firing via G-protein-coupled inwardly rectifying K+ channels. This helps determine patterns of DA signalling at distant axonal release sites. Somatodendritically released DA also acts via volume transmission to extrasynaptic receptors that modulate local transmitter release and neuronal activity in the midbrain. Thus, somatodendritic release is a pivotal intrinsic feature of DA neurons that must be well defined in order to fully understand the physiology and pathophysiology of DA pathways. Here, we review recent mechanistic aspects of somatodendritic DA release, with particular emphasis on the Ca2+ dependence of release and the potential role of exocytotic proteins. PMID:26009764

  11. Beyond the dopamine receptor: novel therapeutic targets for treating schizophrenia

    PubMed Central

    Coyle, Joseph T.; Balu, Darrick; Benneyworth, Michael; Basu, Alo; Roseman, Alexander

    2010-01-01

    All current drugs approved to treat schizophrenia appear to exert their antipsychotic effects through blocking the dopamine D2 receptor. Recent meta-analyses and comparative efficacy studies indicate marginal differences in efficacy of newer atypical antipsychotics and the older drugs, and little effects on negative and cognitive symptoms. This review integrates findings from postmortem, imaging, and drug-challenge studies to elucidate a corticolimbic “pathologic circuit” in schizophrenia that may be particularly relevant to the negative symptoms and cognitive impairments of schizophrenia. Potential sites for pharmacologic intervention targeting glutatatergic, GABAergic, and cholinergic neurotransmission to treat these symptoms of schizophrenia are discussed. PMID:20954431

  12. Dopamine evoked inhibition of single cells of the feline putamen and basolateral amygdala.

    PubMed

    Ben-Ari, Y; Kelly, J S

    1976-03-01

    significant effect on the dopamine or GABA sensitivity of seventy cells in the putamen and basolateral amygdala. 7. Our results are in keeping with the view that dopamine has a predominantly inhibitory action in the mammalian forebrain. However the failure of I.V. neuroleptics to modify the sensitivity of the cells to dopamine suggests that the dramatic effects of neuroleptics on animal behaviour may not be explicable simply in terms of a generalized blockade of dopamine receptors at post-synaptic sites.

  13. A Single Amphetamine Infusion Reverses Deficits in Dopamine Nerve-Terminal Function Caused by a History of Cocaine Self-Administration

    PubMed Central

    Ferris, Mark J; Calipari, Erin S; Rose, Jamie H; Siciliano, Cody A; Sun, Haiguo; Chen, Rong; Jones, Sara R

    2015-01-01

    There are ∼1.6 million people who meet the criteria for cocaine addiction in the United States, and there are currently no FDA-approved pharmacotherapies. Amphetamine-based dopamine-releasing drugs have shown efficacy in reducing the motivation to self-administer cocaine and reducing intake in animals and humans. It is hypothesized that amphetamine acts as a replacement therapy for cocaine through elevation of extracellular dopamine levels. Using voltammetry in brain slices, we tested the ability of a single amphetamine infusion in vivo to modulate dopamine release, uptake kinetics, and cocaine potency in cocaine-naive animals and after a history of cocaine self-administration (1.5 mg/kg/infusion, fixed-ratio 1, 40 injections/day × 5 days). Dopamine kinetics were measured 1 and 24 h after amphetamine infusion (0.56 mg/kg, i.v.). Following cocaine self-administration, dopamine release, maximal rate of uptake (Vmax), and membrane-associated dopamine transporter (DAT) levels were reduced, and the DAT was less sensitive to cocaine. A single amphetamine infusion reduced Vmax and membrane DAT levels in cocaine-naive animals, but fully restored all aspects of dopamine terminal function in cocaine self-administering animals. Here, for the first time, we demonstrate pharmacologically induced, immediate rescue of deficits in dopamine nerve-terminal function in animals with a history of high-dose cocaine self-administration. This observation supports the notion that the DAT expression and function can be modulated on a rapid timescale and also suggests that the pharmacotherapeutic actions of amphetamine for cocaine addiction go beyond that of replacement therapy. PMID:25689882

  14. A Single Amphetamine Infusion Reverses Deficits in Dopamine Nerve-Terminal Function Caused by a History of Cocaine Self-Administration.

    PubMed

    Ferris, Mark J; Calipari, Erin S; Rose, Jamie H; Siciliano, Cody A; Sun, Haiguo; Chen, Rong; Jones, Sara R

    2015-07-01

    There are ∼ 1.6 million people who meet the criteria for cocaine addiction in the United States, and there are currently no FDA-approved pharmacotherapies. Amphetamine-based dopamine-releasing drugs have shown efficacy in reducing the motivation to self-administer cocaine and reducing intake in animals and humans. It is hypothesized that amphetamine acts as a replacement therapy for cocaine through elevation of extracellular dopamine levels. Using voltammetry in brain slices, we tested the ability of a single amphetamine infusion in vivo to modulate dopamine release, uptake kinetics, and cocaine potency in cocaine-naive animals and after a history of cocaine self-administration (1.5 mg/kg/infusion, fixed-ratio 1, 40 injections/day × 5 days). Dopamine kinetics were measured 1 and 24 h after amphetamine infusion (0.56 mg/kg, i.v.). Following cocaine self-administration, dopamine release, maximal rate of uptake (Vmax), and membrane-associated dopamine transporter (DAT) levels were reduced, and the DAT was less sensitive to cocaine. A single amphetamine infusion reduced Vmax and membrane DAT levels in cocaine-naive animals, but fully restored all aspects of dopamine terminal function in cocaine self-administering animals. Here, for the first time, we demonstrate pharmacologically induced, immediate rescue of deficits in dopamine nerve-terminal function in animals with a history of high-dose cocaine self-administration. This observation supports the notion that the DAT expression and function can be modulated on a rapid timescale and also suggests that the pharmacotherapeutic actions of amphetamine for cocaine addiction go beyond that of replacement therapy. PMID:25689882

  15. Postnatal manganese exposure alters dopamine transporter function in adult rats: Potential impact on nonassociative and associative processes.

    PubMed

    McDougall, S A; Reichel, C M; Farley, C M; Flesher, M M; Der-Ghazarian, T; Cortez, A M; Wacan, J J; Martinez, C E; Varela, F A; Butt, A E; Crawford, C A

    2008-06-23

    In the present study, we examined whether exposing rats to a high-dose regimen of manganese chloride (Mn) during the postnatal period would depress presynaptic dopamine functioning and alter nonassociative and associative behaviors. To this end, rats were given oral supplements of Mn (750 microg/day) on postnatal days (PD) 1-21. On PD 90, dopamine transporter (DAT) immunoreactivity and [3H]dopamine uptake were assayed in the striatum and nucleus accumbens, while in vivo microdialysis was used to measure dopamine efflux in the same brain regions. The effects of postnatal Mn exposure on nigrostriatal functioning were evaluated by assessing rotorod performance and amphetamine-induced stereotypy in adulthood. In terms of associative processes, both cocaine-induced conditioned place preference (CPP) and sucrose-reinforced operant responding were examined. Results showed that postnatal Mn exposure caused persistent declines in DAT protein expression and [3H]dopamine uptake in the striatum and nucleus accumbens, as well as long-term reductions in striatal dopamine efflux. Rotorod performance did not differ according to exposure condition, however Mn-exposed rats did exhibit substantially more amphetamine-induced stereotypy than vehicle controls. Mn exposure did not alter performance on any aspect of the CPP task (preference, extinction, or reinstatement testing), nor did Mn affect progressive ratio responding (a measure of motivation). Interestingly, acquisition of a fixed ratio task was impaired in Mn-exposed rats, suggesting a deficit in procedural learning. In sum, these results indicate that postnatal Mn exposure causes persistent declines in various indices of presynaptic dopaminergic functioning. Mn-induced alterations in striatal functioning may have long-term impact on associative and nonassociative behavior.

  16. Amphetamine in adolescence disrupts the development of medial prefrontal cortex dopamine connectivity in a DCC-dependent manner.

    PubMed

    Reynolds, Lauren M; Makowski, Carolina S; Yogendran, Sandra V; Kiessling, Silke; Cermakian, Nicolas; Flores, Cecilia

    2015-03-13

    Initiation of drug use during adolescence is a strong predictor of both the incidence and severity of addiction throughout the lifetime. Intriguingly, adolescence is a period of dynamic refinement in the organization of neuronal connectivity, in particular medial prefrontal cortex (mPFC) dopamine circuitry. The guidance cue receptor, DCC (deleted in colorectal cancer), is highly expressed by dopamine neurons and orchestrates their innervation to the mPFC during adolescence. Furthermore, we have shown that amphetamine in adolescence regulates DCC expression in dopamine neurons. Drugs in adolescence may therefore induce their enduring behavioral effects via DCC-mediated disruption in mPFC dopamine development. In this study, we investigated the impact of repeated exposure to amphetamine during adolescence on both the development of mPFC dopamine connectivity and on salience attribution to drug context in adulthood. We compare these effects to those induced by adult exposure to an identical amphetamine regimen. Finally, we determine whether DCC signaling within dopamine neurons is necessary for these events. Exposure to amphetamine in adolescence, but not in adulthood, leads to an increase in the span of dopamine innervation to the mPFC, but a reduction of presynaptic sites present on these axons. Amphetamine treatment in adolescence, but not in adulthood, also produces an increase in salience attribution to a previously drug-paired context in adulthood. Remarkably, DCC signaling within dopamine neurons is required for both of these effects. Drugs of abuse in adolescence may therefore induce their detrimental behavioral consequences by disrupting mesocortical dopamine development through alterations in the DCC signaling cascade.

  17. Amphetamine in adolescence disrupts the development of medial prefrontal cortex dopamine connectivity in a DCC-dependent manner.

    PubMed

    Reynolds, Lauren M; Makowski, Carolina S; Yogendran, Sandra V; Kiessling, Silke; Cermakian, Nicolas; Flores, Cecilia

    2015-04-01

    Initiation of drug use during adolescence is a strong predictor of both the incidence and severity of addiction throughout the lifetime. Intriguingly, adolescence is a period of dynamic refinement in the organization of neuronal connectivity, in particular medial prefrontal cortex (mPFC) dopamine circuitry. The guidance cue receptor, DCC (deleted in colorectal cancer), is highly expressed by dopamine neurons and orchestrates their innervation to the mPFC during adolescence. Furthermore, we have shown that amphetamine in adolescence regulates DCC expression in dopamine neurons. Drugs in adolescence may therefore induce their enduring behavioral effects via DCC-mediated disruption in mPFC dopamine development. In this study, we investigated the impact of repeated exposure to amphetamine during adolescence on both the development of mPFC dopamine connectivity and on salience attribution to drug context in adulthood. We compare these effects to those induced by adult exposure to an identical amphetamine regimen. Finally, we determine whether DCC signaling within dopamine neurons is necessary for these events. Exposure to amphetamine in adolescence, but not in adulthood, leads to an increase in the span of dopamine innervation to the mPFC, but a reduction of presynaptic sites present on these axons. Amphetamine treatment in adolescence, but not in adulthood, also produces an increase in salience attribution to a previously drug-paired context in adulthood. Remarkably, DCC signaling within dopamine neurons is required for both of these effects. Drugs of abuse in adolescence may therefore induce their detrimental behavioral consequences by disrupting mesocortical dopamine development through alterations in the DCC signaling cascade. PMID:25336209

  18. Distinct dopamine neurons mediate reward signals for short- and long-term memories.

    PubMed

    Yamagata, Nobuhiro; Ichinose, Toshiharu; Aso, Yoshinori; Plaçais, Pierre-Yves; Friedrich, Anja B; Sima, Richard J; Preat, Thomas; Rubin, Gerald M; Tanimoto, Hiromu

    2015-01-13

    Drosophila melanogaster can acquire a stable appetitive olfactory memory when the presentation of a sugar reward and an odor are paired. However, the neuronal mechanisms by which a single training induces long-term memory are poorly understood. Here we show that two distinct subsets of dopamine neurons in the fly brain signal reward for short-term (STM) and long-term memories (LTM). One subset induces memory that decays within several hours, whereas the other induces memory that gradually develops after training. They convey reward signals to spatially segregated synaptic domains of the mushroom body (MB), a potential site for convergence. Furthermore, we identified a single type of dopamine neuron that conveys the reward signal to restricted subdomains of the mushroom body lobes and induces long-term memory. Constant appetitive memory retention after a single training session thus comprises two memory components triggered by distinct dopamine neurons.

  19. Distinct dopamine neurons mediate reward signals for short- and long-term memories

    PubMed Central

    Yamagata, Nobuhiro; Ichinose, Toshiharu; Aso, Yoshinori; Plaçais, Pierre-Yves; Friedrich, Anja B.; Sima, Richard J.; Preat, Thomas; Rubin, Gerald M.; Tanimoto, Hiromu

    2015-01-01

    Drosophila melanogaster can acquire a stable appetitive olfactory memory when the presentation of a sugar reward and an odor are paired. However, the neuronal mechanisms by which a single training induces long-term memory are poorly understood. Here we show that two distinct subsets of dopamine neurons in the fly brain signal reward for short-term (STM) and long-term memories (LTM). One subset induces memory that decays within several hours, whereas the other induces memory that gradually develops after training. They convey reward signals to spatially segregated synaptic domains of the mushroom body (MB), a potential site for convergence. Furthermore, we identified a single type of dopamine neuron that conveys the reward signal to restricted subdomains of the mushroom body lobes and induces long-term memory. Constant appetitive memory retention after a single training session thus comprises two memory components triggered by distinct dopamine neurons. PMID:25548178

  20. Distinct dopamine neurons mediate reward signals for short- and long-term memories.

    PubMed

    Yamagata, Nobuhiro; Ichinose, Toshiharu; Aso, Yoshinori; Plaçais, Pierre-Yves; Friedrich, Anja B; Sima, Richard J; Preat, Thomas; Rubin, Gerald M; Tanimoto, Hiromu

    2015-01-13

    Drosophila melanogaster can acquire a stable appetitive olfactory memory when the presentation of a sugar reward and an odor are paired. However, the neuronal mechanisms by which a single training induces long-term memory are poorly understood. Here we show that two distinct subsets of dopamine neurons in the fly brain signal reward for short-term (STM) and long-term memories (LTM). One subset induces memory that decays within several hours, whereas the other induces memory that gradually develops after training. They convey reward signals to spatially segregated synaptic domains of the mushroom body (MB), a potential site for convergence. Furthermore, we identified a single type of dopamine neuron that conveys the reward signal to restricted subdomains of the mushroom body lobes and induces long-term memory. Constant appetitive memory retention after a single training session thus comprises two memory components triggered by distinct dopamine neurons. PMID:25548178

  1. Effect of cocaine on striatal dopamine clearance in a rat model of developmental stress and attention-deficit/hyperactivity disorder.

    PubMed

    Womersley, Jacqueline S; Kellaway, Lauriston A; Stein, Dan J; Gerhardt, Greg A; Russell, Vivienne A

    2016-01-01

    Attention-deficit/hyperactivity disorder (ADHD) and developmental stress are considered risk factors for the development of drug abuse. Though the physiological mechanisms underlying this risk are not yet clear, ADHD, developmental stress and drug abuse are known to share underlying disturbances in dopaminergic neurotransmission. Thus, we hypothesized that clearance of cocaine-induced elevations in striatal dopamine would be prolonged in a rat model of ADHD and that this would be further increased by exposure to developmental stress. In the current study, male spontaneously hypertensive rats (SHRs), a well-validated model of ADHD, and control Wistar-Kyoto (WKY) rats were exposed to either standard rearing (nMS) or a maternal separation (MS) paradigm involving removal of the pups from the dam for 180 min/day over 13 days. This produced a 2 × 2 factorial design (SHR/WKY × nMS/MS) with 5-6 rats/group. Striatal clearance of exogenously applied dopamine was measured via in vivo chronoamperometry, and the difference in dopamine uptake parameters before and after cocaine administration was compared between experimental groups. Cocaine, a potent dopamine transporter inhibitor, reliably increased the clearance time of dopamine though no difference in this parameter was found between SHR and WKY strains. However, developmental stress elevated the cocaine-induced increase in time to clear 50% of exogenously applied dopamine (T50) in SHR but had no effect in WKY rats. These findings suggest that a strain × environment interaction prolongs elevated levels of dopamine thereby potentially increasing the rewarding properties of this drug in SHR.

  2. Effect of cocaine on striatal dopamine clearance in a rat model of developmental stress and attention-deficit/hyperactivity disorder.

    PubMed

    Womersley, Jacqueline S; Kellaway, Lauriston A; Stein, Dan J; Gerhardt, Greg A; Russell, Vivienne A

    2016-01-01

    Attention-deficit/hyperactivity disorder (ADHD) and developmental stress are considered risk factors for the development of drug abuse. Though the physiological mechanisms underlying this risk are not yet clear, ADHD, developmental stress and drug abuse are known to share underlying disturbances in dopaminergic neurotransmission. Thus, we hypothesized that clearance of cocaine-induced elevations in striatal dopamine would be prolonged in a rat model of ADHD and that this would be further increased by exposure to developmental stress. In the current study, male spontaneously hypertensive rats (SHRs), a well-validated model of ADHD, and control Wistar-Kyoto (WKY) rats were exposed to either standard rearing (nMS) or a maternal separation (MS) paradigm involving removal of the pups from the dam for 180 min/day over 13 days. This produced a 2 × 2 factorial design (SHR/WKY × nMS/MS) with 5-6 rats/group. Striatal clearance of exogenously applied dopamine was measured via in vivo chronoamperometry, and the difference in dopamine uptake parameters before and after cocaine administration was compared between experimental groups. Cocaine, a potent dopamine transporter inhibitor, reliably increased the clearance time of dopamine though no difference in this parameter was found between SHR and WKY strains. However, developmental stress elevated the cocaine-induced increase in time to clear 50% of exogenously applied dopamine (T50) in SHR but had no effect in WKY rats. These findings suggest that a strain × environment interaction prolongs elevated levels of dopamine thereby potentially increasing the rewarding properties of this drug in SHR. PMID:26394534

  3. Allelic association of the D2 dopamine receptor gene with receptor-binding characteristics in alcoholism

    SciTech Connect

    Noble, E.P.; Blum, K.; Ritchie, T.; Montgomery, A.; Sheridan, P.J. )

    1991-07-01

    The allelic association of the human D2 dopamine receptor gene with the binding characteristics of the D2 dopamine receptor was determined in 66 brains of alcoholic and non-alcoholic subjects. In a blinded experiment, DNA from the cerebral cortex was treated with the restriction endonuclease Taql and probed with a 1.5-kilobase (kb) digest of a clone (lambda hD2G1) of the human D2 dopamine receptor gene. The binding characteristics (Kd (binding affinity) and Bmax (number of binding sites)) of the D2 dopamine receptor were determined in the caudate nuclei of these brains using tritiated spiperone as the ligand. The adjusted Kd was significantly lower in alcoholic than in nonalcoholic subjects. In subjects with the A1 allele, in whom a high association with alcoholism was found, the Bmax was significantly reduced compared with the Bmax of subjects with the A2 allele. Moreover, a progressively reduced Bmax was found in subjects with A2/A2, A1/A2, and A1/A1 alleles, with subjects with A2/A2 having the highest mean values, and subjects with A1/A1, the lowest. The polymorphic pattern of the D2 dopamine receptor gene and its differential expression of receptors suggests the involvement of the dopaminergic system in conferring susceptibility to at least one subtype of severe alcoholism.

  4. Dopamine transporter ligands: recent developments and therapeutic potential.

    PubMed

    Runyon, Scott P; Carroll, F Ivy

    2006-01-01

    The dopamine transporter (DAT) is a target for the development of pharmacotherapies for a number of central disorders including Parkinson's disease, Alzheimer's disease, schizophrenia, Tourette's syndrome, Lesch-Nyhan disease, attention deficit hyperactivity disorder (ADHD), obesity, depression, and stimulant abuse as well as normal aging. Considerable effort continues to be devoted to the development of new ligands for the DAT. In this review, we present some of the more interesting ligands developed during the last few years from the 3-phenytropane, 1,4-dialkylpiperazine, phenylpiperidine, and benztropine classes of DAT uptake inhibitors as well as a few less studied miscellaneous DAT uptake inhibitors. Studies related to the therapeutic potential of some of the more studied compounds are presented. A few of the compounds have been studied as pharmacotherapies for Parkinson's disease, ADHD, and obesity. However, most of the drug discovery studies have been directed toward pharmacotherapies for stimulant abuse (mainly cocaine). A number of the compounds showed decreased cocaine maintained responding in rhesus monkeys trained to self-administer cocaine. One compound, GBR 12,909, was evaluated in a Phase 1 clinical trial. PMID:17017960

  5. Dual Control of Dopamine Synthesis and Release by Presynaptic and Postsynaptic Dopamine D2 Receptors

    PubMed Central

    Anzalone, Andrea; Lizardi-Ortiz, José E.; Ramos, Maria; De Mei, Claudia; Hopf, F. Woodward; Iaccarino, Ciro; Halbout, Briac; Jacobsen, Jacob; Kinoshita, Chisato; Welter, Marc; Caron, Marc G.; Bonci, Antonello; Sulzer, David

    2012-01-01

    Dysfunctions of dopaminergic homeostasis leading to either low or high dopamine (DA) levels are causally linked to Parkinson's disease, schizophrenia, and addiction. Major sites of DA synthesis are the mesencephalic neurons originating in the substantia nigra and ventral tegmental area; these structures send major projections to the dorsal striatum (DSt) and nucleus accumbens (NAcc), respectively. DA finely tunes its own synthesis and release by activating DA D2 receptors (D2R). To date, this critical D2R-dependent function was thought to be solely due to activation of D2Rs on dopaminergic neurons (D2 autoreceptors); instead, using site-specific D2R knock-out mice, we uncover that D2 heteroreceptors located on non-DAergic medium spiny neurons participate in the control of DA levels. This D2 heteroreceptor-mediated mechanism is more efficient in the DSt than in NAcc, indicating that D2R signaling differentially regulates mesolimbic- versus nigrostriatal-mediated functions. This study reveals previously unappreciated control of DA signaling, shedding new light on region-specific regulation of DA-mediated effects. PMID:22745501

  6. A new dopamine-β-hydroxylase inhibitor

    PubMed Central

    Andén, N. -E.; Fuxe, K.

    1971-01-01

    1. The dopamine-β-hydroxylase inhibitor bis(4-methyl-1-homopiperazinyl-thiocarbonyl) disulphide (FLA-63; 25 mg/kg i.p.) caused within 4 h a 65% loss of noradrenaline throughout the intact rat spinal cord and also cranial to a transection of the cut spinal cord. Caudal to the lesion, there was only an insignificant depletion of 17% indicating the importance of nerve impulses for the disappearance of noradrenaline. 2. Dopamine accumulated in the spinal cord after treatment with FLA-63 although the amounts were not sufficient to replace the missing noradrenaline. Even after treatment with L-3,4-dihydroxyphenylalanine (L-DOPA), the catecholamine store was incompletely replenished by dopamine. 3. After a large depletion of the noradrenaline stores, induced by repeated doses of FLA-63 or by reserpine plus FLA-63, the L-DOPA-induced increase in flexor reflex activity of the hind limbs of spinal rats was inhibited much more than after pretreatment with α-methyl-tyrosine or reserpine. FLA-63 blocked the formation of noradrenaline but not of dopamine from L-DOPA. 4. The increase in flexor reflex activity induced by the noradrenaline receptor stimulating agent clonidine was not changed by FLA-63, indicating that the noradrenaline receptor sensitivity was not influenced. 5. After depletion of the noradrenaline stores, the small formation of noradrenaline from L-DOPA may be of greater functional significance for the noradrenaline receptor stimulation than the greater formation of dopamine, but the dopamine formed also has a slight action. With intact noradrenaline stores, displacement of endogenous noradrenaline by newly formed dopamine contributes, at least after monoamine oxidase inhibition, to the increase in the flexor reflex activity caused by L-DOPA. PMID:4339882

  7. High fat diet augments amphetamine sensitization in mice: Role of feeding pattern, obesity, and dopamine terminal changes.

    PubMed

    Fordahl, Steve C; Locke, Jason L; Jones, Sara R

    2016-10-01

    High fat (HF) diet-induced obesity has been shown to augment behavioral responses to psychostimulants that target the dopamine system. The purpose of this study was to characterize dopamine terminal changes induced by a HF diet that correspond with enhanced locomotor sensitization to amphetamine. C57BL/6J mice had limited (2hr 3 d/week) or extended (24 h 7 d/week) access to a HF diet or standard chow for six weeks. Mice were then repeatedly exposed to amphetamine (AMPH), and their locomotor responses to an amphetamine challenge were measured. Fast scan cyclic voltammetry was used to identify changes in dopamine terminal function after AMPH exposure. Exposure to a HF diet reduced dopamine uptake and increased locomotor responses to acute, high-dose AMPH administration compared to chow fed mice. Microdialysis showed elevated extracellular dopamine in the nucleus accumbens (NAc) coincided with enhanced locomotion after acute AMPH in HF-fed mice. All mice exhibited locomotor sensitization to amphetamine, but both extended and limited access to a HF diet augmented this response. Neither HF-fed group showed the robust amphetamine sensitization-induced increases in dopamine release, reuptake, and amphetamine potency observed in chow fed animals. However, the potency of amphetamine as an uptake inhibitor was significantly elevated after sensitization in mice with extended (but not limited) access to HF. Conversely, after amphetamine sensitization, mice with limited (but not extended) access to HF displayed reduced autoreceptor sensitivity to the D2/D3 agonist quinpirole. Additionally, we observed reduced membrane dopamine transporter (DAT) levels after HF, and a shift in DAT localization to the cytosol was detected with limited access to HF. This study showed that different patterns of HF exposure produced distinct dopamine terminal adaptations to repeated AMPH, which differed from chow fed mice, and enhanced sensitization to AMPH. Locomotor sensitization in chow fed

  8. Stereoselective effects of MDMA on inhibition of monoamine uptake

    SciTech Connect

    Steele, T.D.; Nichols, D.E.; Yim, G.K.W.

    1986-03-05

    The R(-)-isomers of hallucinogenic phenylisopropylamines are most active, whereas the S(+)-enantiomers of amphetamine (AMPH) and methylenedioxymethamphetamine (MDMA) are more potent centrally. To determine if MDMA exhibits stereoselective effects at the biochemical level that resemble either those of amphetamine or the potent hallucinogen 2,5-dimethoxy-4-methylamphetamine (DOM), the ability of the isomers of MDMA, AMPH and DOM to inhibit uptake of radiolabelled monoamines into synaptosomes was measured. AMPH was more potent than MDMA in inhibiting uptake of /sup 3/H-norepinephrine (NE) into hypothalamic synaptosomes and /sup 3/H-dopamine (DA) into striatal synaptosomes. The S(+)-isomer was more active in each case. MDMA was more potent than AMPH in inhibiting uptake of /sup 3/H-serotonin (5-HT) into hippocampal synaptosomes and exhibited a high degree of stereoselectivity, in favor of the S(+)-isomer. DOM showed only minimal activity in inhibiting uptake of any monoamine (IC/sub 50/ > 10/sup -5/M). These results suggest that MDMA exhibits stereoselective effects similar to those of amphetamine on monoamine uptake inhibition, a parameter that is unrelated to the mechanism of action of the hallucinogen DOM.

  9. 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

  10. 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. PMID:19826615

  11. 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.

  12. 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.

  13. 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

  14. Genetic disruption of dopamine production results in pituitary adenomas and severe prolactinemia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  15. Changes in dopamine transporter binding in nucleus accumbens following chronic self-administration cocaine: heroin combinations.

    PubMed

    Pattison, Lindsey P; McIntosh, Scot; Sexton, Tammy; Childers, Steven R; Hemby, Scott E

    2014-10-01

    Concurrent use of cocaine and heroin (speedball) has been shown to exert synergistic effects on dopamine neurotransmission in the nucleus accumbens (NAc), as observed by significant increases in extracellular dopamine levels and compensatory elevations in the maximal reuptake rate of dopamine. The present studies were undertaken to determine whether chronic self-administration of cocaine, heroin or a combination of cocaine:heroin led to compensatory changes in the abundance and/or affinity of high- and low-affinity DAT binding sites. Saturation binding of the cocaine analog [(125) I] 3β-(4-iodophenyl)tropan-2β-carboxylic acid methyl ester ([(125) I]RTI-55) in rat NAc membranes resulted in binding curves that were best fit to two-site binding models, allowing calculation of dissociation constant (Kd ) and binding density (Bmax ) values corresponding to high- and low-affinity DAT binding sites. Scatchard analysis of the saturation binding curves clearly demonstrate the presence of high- and low- affinity binding sites in the NAc, with low-affinity sites comprising 85 to 94% of the binding sites. DAT binding analyses revealed that self-administration of cocaine and a cocaine:heroin combination increased the affinity of the low-affinity site for the cocaine congener RTI-55 compared to saline. These results indicate that the alterations observed following chronic speedball self-administration are likely due to the cocaine component alone; thus further studies are necessary to elaborate upon the synergistic effect of cocaine:heroin combinations on the dopamine system in the NAc. PMID:24916769

  16. Fluorescence Intensity and Intermittency as Tools for Following Dopamine Bioconjugate Processing in Living Cells

    PubMed Central

    Khatchadourian, Rafael; Bachir, Alexia; Clarke, Samuel J.; Heyes, Colin D.; Wiseman, Paul W.; Nadeau, Jay L.

    2007-01-01

    CdSe/ZnS quantum dots (QDs) conjugated to biomolecules that quench their fluorescence, particularly dopamine, have particular spectral properties that allow determination of the number of conjugates per particle, namely, photoenhancement and photobleaching. In this work, we quantify these properties on a single-particle and ensemble basis in order to evaluate their usefulness as a tool for indicating QD uptake, breakdown, and processing in living cells. This creates a general framework for the use of fluorescence quenching and intermittency to better understand nanoparticle-cell interactions. PMID:18401443

  17. Intrarenal dopamine inhibits progression of diabetic nephropathy.

    PubMed

    Zhang, Ming-Zhi; Yao, Bing; Yang, Shilin; Yang, Haichun; Wang, Suwan; Fan, Xiaofeng; Yin, Huiyong; Fogo, Agnes B; Moeckel, Gilbert W; Harris, Raymond C

    2012-10-01

    The kidney has a local intrarenal dopaminergic system, and in the kidney, dopamine modulates renal hemodynamics, inhibits salt and fluid reabsorption, antagonizes the renin-angiotensin system, and inhibits oxidative stress. The current study examined the effects of alterations in the intrarenal dopaminergic system on kidney structure and function in models of type 1 diabetes. We studied catechol-O-methyl-transferase (COMT)(-/-) mice, which have increased renal dopamine production due to decreased dopamine metabolism, and renal transplantation was used to determine whether the effects seen with COMT deficiency were kidney-specific. To determine the effects of selective inhibition of intrarenal dopamine production, we used mice with proximal tubule deletion of aromatic amino acid decarboxylase (ptAADC(-/-)). Compared with wild-type diabetic mice, COMT(-/-) mice had decreased hyperfiltration, decreased macula densa cyclooxygenase-2 expression, decreased albuminuria, decreased glomerulopathy, and inhibition of expression of markers of inflammation, oxidative stress, and fibrosis. These differences were also seen in diabetic mice with a transplanted kidney from COMT(-/-) mice. In contrast, diabetic ptAADC(-/-) mice had increased nephropathy. Our study demonstrates an important role of the intrarenal dopaminergic system to modulate the development and progression of diabetic kidney injury and indicate that the decreased renal dopamine production may have important consequences in the underlying pathogenesis of diabetic nephropathy. PMID:22688335

  18. Neuroeconomics: a formal test of dopamine's role in reinforcement learning.

    PubMed

    DeWitt, Eric E J

    2014-04-14

    Over the last two decades, dopamine and reinforcement learning have been increasingly linked. Using a novel, axiomatic approach, a recent study shows that dopamine meets the necessary and sufficient conditions required by the theory to encode a reward prediction error.

  19. Genetics Home Reference: dopamine beta-hydroxylase deficiency

    MedlinePlus

    ... CONGENITAL Sources for This Page Cubells JF, Zabetian CP. Human genetics of plasma dopamine beta-hydroxylase activity: ... GeneReview: Dopamine Beta-Hydroxylase Deficiency Kim CH, Zabetian CP, Cubells JF, Cho S, Biaggioni I, Cohen BM, Robertson ...

  20. Brain May Compensate for Dopamine Neuron Loss Early in Parkinson's

    MedlinePlus

    ... More Science News Brain May Compensate for Dopamine Neuron Loss Early in Parkinson’s - May 09 2014 Scientists ... at least 25 percent of the brain’s dopamine neurons already have been lost. So why do symptoms ...

  1. Evidence that amphetamine and Na+ gradient reversal increase striatal synaptosomal dopamine synthesis through carrier-mediated efflux of dopamine.

    PubMed

    Connor, C E; Kuczenski, R

    1986-09-15

    Amphetamine (AMPH) releases dopamine (DA) from striatal synaptosomes and concomitantly increases DA synthesis. Since AMPH may release DA through carrier-mediated diffusion via reversal of the DA uptake system, the increase in DA synthesis might depend on a functioning uptake carrier. Consistent with such a mechanism, the uptake inhibitors nomifensine (NMF) and benztropine (BZT) completely prevented the AMPH-induced increase in DA synthesis at concentrations known to inhibit DA uptake. Changes in the Na+ gradient across the synaptosomal membrane also promote DA release, since DA and Na+ are cotransported by the neuronal uptake carrier. Incubation of synaptosomes in medium containing decreasing Na+ increased DA synthesis inversely proportional to Na+ over the range 128 to 20 mM. Similarly, incubations in the presence of 10(-4) M ouabain to inhibit Na+, K+-ATPase and allow intracellular accumulation of Na+ also increased DA synthesis. These changes in DA synthesis could also be prevented by BZT and were non-additive with the AMPH-induced increase in DA synthesis. However, a concentration of ouabain (10(-6) M) which by itself did not increase DA synthesis, and does not promote DA release, potentiated the AMPH-induced increase in DA synthesis. Further, the increased DA synthesis promoted by all three manipulations was only marginally dependent on the presence of Ca2+ in the incubation medium. However, at 5 and 10 mM Na+, a second component of increased DA synthesis was observed which was insensitive to BZT, but was prevented by Ca2+ removal. These results suggest that the increase in DA synthesis, and presumably DA release promoted by AMPH, lowered Na+, and ouabain, depend on the availability of the DA carrier at the internal face of the neuronal membrane and the intracellular content of Na+. The second component of increased DA synthesis which is evident at 5 and 10 mM Na+ is discussed in terms of a possible Ca2+-mediated change in DA synthesis which is independent of

  2. Iron-Responsive Olfactory Uptake of Manganese Improves Motor Function Deficits Associated with Iron Deficiency

    PubMed Central

    Kim, Jonghan; Li, Yuan; Buckett, Peter D.; Böhlke, Mark; Thompson, Khristy J.; Takahashi, Masaya; Maher, Timothy J.; Wessling-Resnick, Marianne

    2012-01-01

    Iron-responsive manganese uptake is increased in iron-deficient rats, suggesting that toxicity related to manganese exposure could be modified by iron status. To explore possible interactions, the distribution of intranasally-instilled manganese in control and iron-deficient rat brain was characterized by quantitative image analysis using T1-weighted magnetic resonance imaging (MRI). Manganese accumulation in the brain of iron-deficient rats was doubled after intranasal administration of MnCl2 for 1- or 3-week. Enhanced manganese level was observed in specific brain regions of iron-deficient rats, including the striatum, hippocampus, and prefrontal cortex. Iron-deficient rats spent reduced time on a standard accelerating rotarod bar before falling and with lower peak speed compared to controls; unexpectedly, these measures of motor function significantly improved in iron-deficient rats intranasally-instilled with MnCl2. Although tissue dopamine concentrations were similar in the striatum, dopamine transporter (DAT) and dopamine receptor D1 (D1R) levels were reduced and dopamine receptor D2 (D2R) levels were increased in manganese-instilled rats, suggesting that manganese-induced changes in post-synaptic dopaminergic signaling contribute to the compensatory effect. Enhanced olfactory manganese uptake during iron deficiency appears to be a programmed “rescue response” with beneficial influence on motor impairment due to low iron status. PMID:22479410

  3. Dopamine Gene Profiling to Predict Impulse Control and Effects of Dopamine Agonist Ropinirole.

    PubMed

    MacDonald, Hayley J; Stinear, Cathy M; Ren, April; Coxon, James P; Kao, Justin; Macdonald, Lorraine; Snow, Barry; Cramer, Steven C; Byblow, Winston D

    2016-07-01

    Dopamine agonists can impair inhibitory control and cause impulse control disorders for those with Parkinson disease (PD), although mechanistically this is not well understood. In this study, we hypothesized that the extent of such drug effects on impulse control is related to specific dopamine gene polymorphisms. This double-blind, placebo-controlled study aimed to examine the effect of single doses of 0.5 and 1.0 mg of the dopamine agonist ropinirole on impulse control in healthy adults of typical age for PD onset. Impulse control was measured by stop signal RT on a response inhibition task and by an index of impulsive decision-making on the Balloon Analogue Risk Task. A dopamine genetic risk score quantified basal dopamine neurotransmission from the influence of five genes: catechol-O-methyltransferase, dopamine transporter, and those encoding receptors D1, D2, and D3. With placebo, impulse control was better for the high versus low genetic risk score groups. Ropinirole modulated impulse control in a manner dependent on genetic risk score. For the lower score group, both doses improved response inhibition (decreased stop signal RT) whereas the lower dose reduced impulsiveness in decision-making. Conversely, the higher score group showed a trend for worsened response inhibition on the lower dose whereas both doses increased impulsiveness in decision-making. The implications of the present findings are that genotyping can be used to predict impulse control and whether it will improve or worsen with the administration of dopamine agonists. PMID:26942320

  4. Nature or nurture? Determining the heritability of human striatal dopamine function: an [18F]-DOPA PET study.

    PubMed

    Stokes, Paul R A; Shotbolt, Paul; Mehta, Mitul A; Turkheimer, Eric; Benecke, Aaf; Copeland, Caroline; Turkheimer, Federico E; Lingford-Hughes, Anne R; Howes, Oliver D

    2013-02-01

    Striatal dopamine function is important for normal personality, cognitive processes and behavior, and abnormalities are linked to a number of neuropsychiatric disorders. However, no studies have examined the relative influence of genetic inheritance and environmental factors in determining striatal dopamine function. Using [18F]-DOPA positron emission tomography (PET), we sought to determine the heritability of presynaptic striatal dopamine function by comparing variability in uptake values in same sex monozygotic (MZ) twins to dizygotic (DZ) twins. Nine MZ and 10 DZ twin pairs underwent high-resolution [18F]-DOPA PET to assess presynaptic striatal dopamine function. Uptake values for the overall striatum and functional striatal subdivisions were determined by a Patlak analysis using a cerebellar reference region. Heritability, shared environmental effects and non-shared individual-specific effects were estimated using a region of interest (ROI) analysis and a confirmatory parametric analysis. Overall striatal heritability estimates from the ROI and parametric analyses were 0.44 and 0.33, respectively. We found a distinction between striatal heritability in the functional subdivisions, with the greatest heritability estimates occurring in the sensorimotor striatum and the greatest effect of individual-specific environmental factors in the limbic striatum. Our results indicate that variation in overall presynaptic striatal dopamine function is determined by a combination of genetic factors and individual-specific environmental factors, with familial environmental effects having no effect. These findings underline the importance of individual-specific environmental factors for striatal dopaminergic function, particularly in the limbic striatum, with implications for understanding neuropsychiatric disorders such as schizophrenia and addictions.

  5. Differential dopamine function in fibromyalgia.

    PubMed

    Albrecht, Daniel S; MacKie, Palmer J; Kareken, David A; Hutchins, Gary D; Chumin, Evgeny J; Christian, Bradley T; Yoder, Karmen K

    2016-09-01

    Approximately 30 % of Americans suffer from chronic pain disorders, such as fibromyalgia (FM), which can cause debilitating pain. Many pain-killing drugs prescribed for chronic pain disorders are highly addictive, have limited clinical efficacy, and do not treat the cognitive symptoms reported by many patients. The neurobiological substrates of chronic pain are largely unknown, but evidence points to altered dopaminergic transmission in aberrant pain perception. We sought to characterize the dopamine (DA) system in individuals with FM. Positron emission tomography (PET) with [(18)F]fallypride (FAL) was used to assess changes in DA during a working memory challenge relative to a baseline task, and to test for associations between baseline D2/D3 availability and experimental pain measures. Twelve female subjects with FM and 11 female controls completed study procedures. Subjects received one FAL PET scan while performing a "2-back" task, and one while performing a "0-back" (attentional control, "baseline") task. FM subjects had lower baseline FAL binding potential (BP) in several cortical regions relative to controls, including anterior cingulate cortex. In FM subjects, self-reported spontaneous pain negatively correlated with FAL BP in the left orbitofrontal cortex and parahippocampal gyrus. Baseline BP was significantly negatively correlated with experimental pain sensitivity and tolerance in both FM and CON subjects, although spatial patterns of these associations differed between groups. The data suggest that abnormal DA function may be associated with differential processing of pain perception in FM. Further studies are needed to explore the functional significance of DA in nociception and cognitive processing in chronic pain.

  6. Plasma dopamine: regulation and significance.

    PubMed

    Van Loon, G R

    1983-10-01

    Dopamine (DA) normally circulates in plasma. The plasma concentration of the free form of DA is approximately equivalent to that of epinephrine (E) and 20% that of norepinephrine (NE). The free form constitutes less than 2% of total plasma DA, and the remainder exists predominantly as sulfate or glucuronide conjugates. DA is found in adrenal medulla and cortex, peripheral nerves, sympathetic ganglia, carotid body, and kidney, but quantitatively the origin of circulating DA remains poorly understood. Plasma concentrations of free DA increase in association with events that increase sympathetic tone, although to a much lesser degree than seen for NE or E. Thus, upright posture, bicycle exercise, a variety of emotional and physical stresses, and hypoglycemia may be associated with increases in plasma free DA. Plasma DA decreases during the course of dietary sodium depletion in humans, in contrast to the plasma NE response, and consistent with a physiological role for DA in the regulation of aldosterone secretion. Plasma DA increases after administration of its precursor L-dihydroxyphenylalanine, together with the decarboxylase inhibitor carbidopa. Plasma NE and (in some studies) plasma DA decrease after administration of the DA receptor agonist bromocriptine. In contrast, plasma DA and one of its major metabolites, homovanillic acid, increase after administration of the DA receptor antagonist haloperidol. Administration of the endogenous opioid peptide beta-endorphin into the brain increases central sympathetic outflow, thus increasing plasma DA concentration, although to a lesser extent than for NE or E. Disordered basal concentrations of DA in plasma or disordered responses of plasma DA have been reported in a number of disease states. Clear understanding of physiological roles of DA in plasma and of its pathophysiology awaits definition. PMID:6413258

  7. 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.

  8. 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.

  9. 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

  10. Phosphorylation of Dopamine Transporter Serine 7 Modulates Cocaine Analog Binding*

    PubMed Central

    Moritz, Amy E.; Foster, James D.; Gorentla, Balachandra K.; Mazei-Robison, Michelle S.; Yang, Jae-Won; Sitte, Harald H.; Blakely, Randy D.; Vaughan, Roxanne A.

    2013-01-01

    As an approach to elucidating dopamine transporter (DAT) phosphorylation characteristics, we examined in vitro phosphorylation of a recombinant rat DAT N-terminal peptide (NDAT) using purified protein kinases. We found that NDAT becomes phosphorylated at single distinct sites by protein kinase A (Ser-7) and calcium-calmodulin-dependent protein kinase II (Ser-13) and at multiple sites (Ser-4, Ser-7, and Ser-13) by protein kinase C (PKC), implicating these residues as potential sites of DAT phosphorylation by these kinases. Mapping of rat striatal DAT phosphopeptides by two-dimensional thin layer chromatography revealed basal and PKC-stimulated phosphorylation of the same peptide fragments and comigration of PKC-stimulated phosphopeptide fragments with NDAT Ser-7 phosphopeptide markers. We further confirmed by site-directed mutagenesis and mass spectrometry that Ser-7 is a site for PKC-stimulated phosphorylation in heterologously expressed rat and human DATs. Mutation of Ser-7 and nearby residues strongly reduced the affinity of rat DAT for the cocaine analog (−)-2β-carbomethoxy-3β-(4-fluorophenyl) tropane (CFT), whereas in rat striatal tissue, conditions that promote DAT phosphorylation caused increased CFT affinity. Ser-7 mutation also affected zinc modulation of CFT binding, with Ala and Asp substitutions inducing opposing effects. These results identify Ser-7 as a major site for basal and PKC-stimulated phosphorylation of native and expressed DAT and suggest that Ser-7 phosphorylation modulates transporter conformational equilibria, shifting the transporter between high and low affinity cocaine binding states. PMID:23161550

  11. Relations between Stimulation of Mesolimbic Dopamine and Place Conditioning in Rats Produced by Cocaine or Drugs that are Tolerant to Dopamine Transporter Conformational Change

    PubMed Central

    Tanda, Gianluigi; Li, Su Min; Mereu, Maddalena; Thomas, Alexandra M.; Ebbs, Aaron L.; Chun, Lauren E.; Tronci, Valeria; Green, Jennifer L.; Zou, Mu-Fa; Kopajtic, Theresa A.; Newman, Amy Hauck; Katz, Jonathan L.

    2013-01-01

    Rationale Dopamine transporter (DAT) conformation plays a role in the effectiveness of cocaine-like and other DAT-inhibitors. Cocaine-like stimulants are intolerant to DAT conformation changes having decreased potency in cells transfected with DAT constructs that face the cytosol compared to wild-type DAT. In contrast, analogs of benztropine (BZT) are among compounds that are less affected by DAT conformational change. Methods We compared the displacement of radioligand binding to various mammalian CNS sites, acute stimulation of accumbens shell dopamine levels, and place-conditioning in rats among cocaine and four BZT analogs with Cl-substitutions on the diphenyl-ether system including two with carboalkoxy substitutions at the 2-position of the tropane ring. Results Binding assays confirmed high-affinity and selectivity for the DAT with the BZT analogs which also produced significant stimulation of mesolimbic dopamine efflux. Because BZT analogs produced temporal patterns of extracellular dopamine levels different from those by cocaine (3-10 mg/kg, IP), the place conditioning produced by BZT analogs and cocaine was compared at doses and times at which both the increase in dopamine levels and rates of increase were similar to those produced by an effective dose of cocaine. Despite this equilibration, none of the BZT analogs tested produced significant place conditioning. Conclusions The present results extend previous findings suggesting that cocaine-like actions are dependent on a binding equilibrium that favors the outward conformational state of the DAT. In contrast BZT analogs with reduced dependence on DAT conformation have reduced cocaine-like behavioral effects and may prove useful in development of medications for stimulant abuse. PMID:23612854

  12. Gray-matter volume, midbrain dopamine D2/D3 receptors and drug craving in methamphetamine users.

    PubMed

    Morales, A M; Kohno, M; Robertson, C L; Dean, A C; Mandelkern, M A; London, E D

    2015-06-01

    Dysfunction of the mesocorticolimbic system has a critical role in clinical features of addiction. Despite evidence suggesting that midbrain dopamine receptors influence amphetamine-induced dopamine release and that dopamine is involved in methamphetamine-induced neurotoxicity, associations between dopamine receptors and gray-matter volume have been unexplored in methamphetamine users. Here we used magnetic resonance imaging and [(18)F]fallypride positron emission tomography, respectively, to measure gray-matter volume (in 58 methamphetamine users) and dopamine D2/D3 receptor availability (binding potential relative to nondisplaceable uptake of the radiotracer, BPnd) (in 31 methamphetamine users and 37 control participants). Relationships between these measures and self-reported drug craving were examined. Although no difference in midbrain D2/D3 BPnd was detected between methamphetamine and control groups, midbrain D2/D3 BPnd was positively correlated with gray-matter volume in the striatum, prefrontal cortex, insula, hippocampus and temporal cortex in methamphetamine users, but not in control participants (group-by-midbrain D2/D3 BPnd interaction, P<0.05 corrected for multiple comparisons). Craving for methamphetamine was negatively associated with gray-matter volume in the insula, prefrontal cortex, amygdala, temporal cortex, occipital cortex, cerebellum and thalamus (P<0.05 corrected for multiple comparisons). A relationship between midbrain D2/D3 BPnd and methamphetamine craving was not detected. Lower midbrain D2/D3 BPnd may increase vulnerability to deficits in gray-matter volume in mesocorticolimbic circuitry in methamphetamine users, possibly reflecting greater dopamine-induced toxicity. Identifying factors that influence prefrontal and limbic volume, such as midbrain BPnd, may be important for understanding the basis of drug craving, a key factor in the maintenance of substance-use disorders.

  13. Supersensitive Kappa Opioid Receptors Promotes Ethanol Withdrawal-Related Behaviors and Reduce Dopamine Signaling in the Nucleus Accumbens

    PubMed Central

    Rose, Jamie H.; Karkhanis, Anushree N.; Chen, Rong; Gioia, Dominic; Lopez, Marcelo F.; Becker, Howard C.; McCool, Brian A.

    2016-01-01

    Background: Chronic ethanol exposure reduces dopamine transmission in the nucleus accumbens, which may contribute to the negative affective symptoms associated with ethanol withdrawal. Kappa opioid receptors have been implicated in withdrawal-induced excessive drinking and anxiety-like behaviors and are known to inhibit dopamine release in the nucleus accumbens. The effects of chronic ethanol exposure on kappa opioid receptor-mediated changes in dopamine transmission at the level of the dopamine terminal and withdrawal-related behaviors were examined. Methods: Five weeks of chronic intermittent ethanol exposure in male C57BL/6 mice were used to examine the role of kappa opioid receptors in chronic ethanol-induced increases in ethanol intake and marble burying, a measure of anxiety/compulsive-like behavior. Drinking and marble burying were evaluated before and after chronic intermittent ethanol exposure, with and without kappa opioid receptor blockade by nor-binaltorphimine (10mg/kg i.p.). Functional alterations in kappa opioid receptors were assessed using fast scan cyclic voltammetry in brain slices containing the nucleus accumbens. Results: Chronic intermittent ethanol-exposed mice showed increased ethanol drinking and marble burying compared with controls, which was attenuated with kappa opioid receptor blockade. Chronic intermittent ethanol-induced increases in behavior were replicated with kappa opioid receptor activation in naïve mice. Fast scan cyclic voltammetry revealed that chronic intermittent ethanol reduced accumbal dopamine release and increased uptake rates, promoting a hypodopaminergic state of this region. Kappa opioid receptor activation with U50,488H concentration-dependently decreased dopamine release in both groups; however, this effect was greater in chronic intermittent ethanol-treated mice, indicating kappa opioid receptor supersensitivity in this group. Conclusions: These data suggest that the chronic intermittent ethanol-induced increase

  14. Methylphenidate Increases Glutamate Uptake in Bergmann Glial Cells.

    PubMed

    Guillem, Alain M; Martínez-Lozada, Zila; Hernández-Kelly, Luisa C; López-Bayghen, Esther; López-Bayghen, Bruno; Calleros, Oscar A; Campuzano, Marco R; Ortega, Arturo

    2015-11-01

    Glutamate, the main excitatory transmitter in the vertebrate brain, exerts its actions through the activation of specific membrane receptors present in neurons and glial cells. Over-stimulation of glutamate receptors results in neuronal death, phenomena known as excitotoxicity. A family of glutamate uptake systems, mainly expressed in glial cells, removes the amino acid from the synaptic cleft preventing an excessive glutamatergic stimulation and thus neuronal damage. Autism spectrum disorders comprise a group of syndromes characterized by impaired social interactions and anxiety. One or the most common drugs prescribed to treat these disorders is Methylphenidate, known to increase dopamine extracellular levels, although it is not clear if its sedative effects are related to a plausible regulation of the glutamatergic tone via the regulation of the glial glutamate uptake systems. To gain insight into this possibility, we used the well-established model system of cultured chick cerebellum Bergmann glia cells. A time and dose-dependent increase in the activity and protein levels of glutamate transporters was detected upon Methylphenidate exposure. Interestingly, this increase is the result of an augmentation of both the synthesis as well as the insertion of these protein complexes in the plasma membrane. These results favour the notion that glial cells are Methylphenidate targets, and that by these means could regulate dopamine turnover.

  15. Striatal dopamine release in a schizophrenia mouse model measured by electrochemical amperometry in vivo.

    PubMed

    Xu, Huadong; Zuo, Panli; Wang, Shirong; Zhou, Li; Sun, Xiaoxuan; Hu, Meiqin; Liu, Bin; Wu, Qihui; Dou, Haiqiang; Liu, Bing; Zhu, Feipeng; Teng, Sasa; Zhang, Xiaoyu; Wang, Li; Li, Qing; Jin, Mu; Kang, Xinjiang; Xiong, Wei; Wang, Changhe; Zhou, Zhuan

    2015-06-01

    Schizophrenia is a severely devastating mental disorder, the pathological process of which is proposed to be associated with the dysfunction of dopaminergic transmission. Our previous results have demonstrated slower kinetics of transmitter release (glutamate release in hippocampus and norepinephrine release in adrenal slice) in a schizophrenia model, dysbindin null-sandy mice. However, whether dopaminergic transmission in the nigrostriatal pathway contributes to the pathology of dysbindin-/- mice remains unknown. Here, we have provided a step-by-step protocol to be applied in the in vivo amperometric recording of dopamine (DA) release from the mouse striatum evoked by an action potential (AP) pattern. With this protocol, AP pattern-dependent DA release was recorded from dysbindin-/- mice striatum in vivo. On combining amperometric recording in slices and electrophysiology, we found that in dysbindin-/- mice, (1) presynaptically, AP-pattern dependent dopamine overflow and uptake were intact in vivo; (2) the recycling of the dopamine vesicle pool remained unchanged. (3) Postsynaptically, the excitability of medium spiny neuron (MSN) was also normal, as revealed by patch-clamp recordings in striatal slices. Taken together, in contrast to reduced norepinephrine release in adrenal chromaffin cells, the dopaminergic transmission remains unchanged in the nigrostriatal pathway in dysbindin-/- mice, providing a new insight into the functions of the schizophrenia susceptibility gene dysbindin.

  16. PSP-CBS with Dopamine Deficiency in a Female with a FMR1 Premutation.

    PubMed

    Paucar, Martin; Beniaminov, Stanislav; Paslawski, Wojciech; Svenningsson, Per

    2016-10-01

    Premutations in the fragile X mental retardation 1 (FMR1) gene cause fragile X-associated tremor/ataxia syndrome (FXTAS) and FMR1-related primary ovarian insufficiency (POI). Female FMR1 premutation carriers rarely develop motor features. Dual pathology is an emerging phenomenon among FMR1 premutation carriers. Here, we describe a family affected by FMR1-related disorders in which the female index case has developed a rapidly progressive and disabling syndrome of atypical parkinsonism. This syndrome consists of early onset postural instability, echolalia, dystonia, and varying types of apraxia like early onset orobuccal apraxia and oculomotor apraxia. She has also developed supranuclear gaze palsy, increased latency of saccade initiation, and slow saccades. These features are compatible with progressive supranuclear palsy (PSP) of a corticobasal syndrome (CBS) variant. Imaging displays a marked reduction of presynaptic dopaminergic uptake and cerebrospinal fluid analysis showed reduced dopamine metabolism; however, the patient is unresponsive to levodopa. Midbrain atrophy ("hummingbird sign") and mild cerebellar atrophy were found on brain MRI. Her father was affected by a typical FXTAS presentation but also displayed dopamine deficiency along with the hummingbird sign. The mechanisms by which FMR1 premutations predispose to atypical parkinsonism and dopamine deficiency await further elucidation. PMID:27230899

  17. Investigation of the enzymology and pharmacology of novel substrates and inhibitors of dopamine beta-monooxygenase

    SciTech Connect

    Roberts, S.F.

    1987-01-01

    Dopamine beta-monooxygenase (DBM) was shown to catalyze the selenoxidation of 2-(phenylseleno)ethylamines, selenium-containing analogues of dopamine, by the normal monooxygenase pathway. The compounds 2-(phenylseleno)-ethylamine (PAESe), 2-(4'-hydroxyphenylseleno)ethylamine (pOH PAESe), and 1-(phenylseleno)-2-propylamine (Me PAESe) were synthesized and fully characterized as DBM substrates. Two other classes of compounds were investigated as potential alternate substrates for DBM. The possibility of stereoselective sulfonylation of 2-(phenylsulfenyl)- ethylamine (PAESO) was considered. A unique class of compounds, 2-(phenylthio)ethanols were designed and synthesized as DBM substrates but were found to be a novel class of potent competitive inhibitors of DBM with respect to tyramine. Preliminary experiments were also performed in an effort to demonstrate that the potent antihypertensive and indirect-acting sympathomimetic activity of 2-(phenylthio)ethylamine (PAES) was a result of DBM-oxygenation of this compound in vivo. The specific reserpine-sensitive uptake of (/sup 3/H)-norepinephrine into rat brain synaptosomes was demonstrated as was the synaptosomal conversion of (/sup 3/H)-dopamine to (/sup 3/H)-norepinephrine.

  18. 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.

  19. Mitochondrial calcium uptake.

    PubMed

    Williams, George S B; Boyman, Liron; Chikando, Aristide C; Khairallah, Ramzi J; Lederer, W J

    2013-06-25

    Calcium (Ca(2+)) uptake into the mitochondrial matrix is critically important to cellular function. As a regulator of matrix Ca(2+) levels, this flux influences energy production and can initiate cell death. If large, this flux could potentially alter intracellular Ca(2+) ([Ca(2+)]i) signals. Despite years of study, fundamental disagreements on the extent and speed of mitochondrial Ca(2+) uptake still exist. Here, we review and quantitatively analyze mitochondrial Ca(2+) uptake fluxes from different tissues and interpret the results with respect to the recently proposed mitochondrial Ca(2+) uniporter (MCU) candidate. This quantitative analysis yields four clear results: (i) under physiological conditions, Ca(2+) influx into the mitochondria via the MCU is small relative to other cytosolic Ca(2+) extrusion pathways; (ii) single MCU conductance is ∼6-7 pS (105 mM [Ca(2+)]), and MCU flux appears to be modulated by [Ca(2+)]i, suggesting Ca(2+) regulation of MCU open probability (P(O)); (iii) in the heart, two features are clear: the number of MCU channels per mitochondrion can be calculated, and MCU probability is low under normal conditions; and (iv) in skeletal muscle and liver cells, uptake per mitochondrion varies in magnitude but total uptake per cell still appears to be modest. Based on our analysis of available quantitative data, we conclude that although Ca(2+) critically regulates mitochondrial function, the mitochondria do not act as a significant dynamic buffer of cytosolic Ca(2+) under physiological conditions. Nevertheless, with prolonged (superphysiological) elevations of [Ca(2+)]i, mitochondrial Ca(2+) uptake can increase 10- to 1,000-fold and begin to shape [Ca(2+)]i dynamics.

  20. Chromatographic analysis of dopamine metabolism in a Parkinsonian model.

    PubMed

    Baranyi, Mária; Milusheva, Elisaveta; Vizi, E Sylvester; Sperlágh, Beáta

    2006-07-01

    The present study examined the metabolism of released dopamine from rat striatum upon chronic rotenone exposure. The sample separation was carried out by two-dimensional, reversed-phase and ion pair reversed-phase chromatography using on-line solid phase extraction enrichment. Reduced dopamine content and decreased extracellular level of [(3)H] and endogenous dopamine evoked by electrical stimulation indicated the injury of dopaminergic pathway. Sensitivity of dopaminergic neurons were increased to oxidative stress with enhanced release of dopamine and formation of oxidized metabolite dopamine quinone (DAQ). Utilizing multidimensional detection, EC at -100 mV reduction potential, the method has been applied for identification of DAQ and aminochrome (DAC).

  1. 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

  2. Studies of the biogenic amine transporters. IV. Demonstration of a multiplicity of binding sites in rat caudate membranes for the cocaine analog [125I]RTI-55.

    PubMed

    Rothman, R B; Cadet, J L; Akunne, H C; Silverthorn, M L; Baumann, M H; Carroll, F I; Rice, K C; de Costa, B R; Partilla, J S; Wang, J B

    1994-07-01

    The drug 3 beta-[4'-iodophenyl]tropan-2 beta-carboxylic acid methyl ester (RTI-55) is a cocaine congener with high affinity for the dopamine transporter (Kd < 1 nM). The present study characterized [125I]RTI-55 binding to membranes prepared from rat, monkey and human caudates and COS cells transiently expressing the cloned rat dopamine (DA) transporter. Using the method of binding surface analysis, two binding sites were resolved in rat caudate: a high-capacity binding site (site 1, Bmax = 11,900 fmol/mg of protein) and a low-capacity site (site 2, Bmax = 846 fmol/mg of protein). The Kd (or Ki) values of selected drugs at the two sites were as follows: (Ki for high-capacity site and Ki for low-capacity site, respectively): RTI-55 (0.76 and 0.21 nM), 1-[2-diphenyl-methoxy)ethyl]-4-(3-phenylpropyl)piperazine (0.79 and 358 nM), mazindol (37.6 and 631 nM), 2 beta-carbomethoxy-3 beta-(4-fluorophenyl)tropane (45.0 and 540 nM) and cocaine (341 and 129 nM). Nisoxetine, a selective noradrenergic uptake blocker, had low affinity for both sites. Serotonergic uptake blockers had a high degree of selectivity and high affinity for the low-capacity binding site (Ki of citalopram = 0.38 nM; Ki of paroxetine = 0.033 nM). The i.c.v. administration of 5,7-dihydroxytryptamine to rats pretreated with nomifensine (to protect dopaminergic and noradrenergic nerve terminals) selectively decreased the Bmax of site 2, strongly supporting the idea that site 2 is a binding site on the serotonin (5-HT) transporter. This serotonergic lesion also increased the affinity of [125I]RTI-55 for the DA transporter by 10-fold. The ligand selectivity of the caudate 5-HT transporter was different from the [I125]RTI-55 binding site on the 5-HT transporter present in membranes prepared from whole rat brain minus caudate. The [125I]RTI-55 binding to the DA transporter was further resolved into two components, termed sites 1a and 1b, by using human and monkey (Macaca mulatta) caudate membranes but not the

  3. Dopamine-melanin nanofilms for biomimetic structural coloration.

    PubMed

    Wu, Tong-Fei; Hong, Jong-Dal

    2015-02-01

    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.

  4. The role of dopamine receptors in the neurotoxicity of methamphetamine.

    PubMed

    Ares-Santos, S; Granado, N; Moratalla, R

    2013-05-01

    Methamphetamine is a synthetic drug consumed by millions of users despite its neurotoxic effects in the brain, leading to loss of dopaminergic fibres and cell bodies. Moreover, clinical reports suggest that methamphetamine abusers are predisposed to Parkinson's disease. Therefore, it is important to elucidate the mechanisms involved in methamphetamine-induced neurotoxicity. Dopamine receptors may be a plausible target to prevent this neurotoxicity. Genetic inactivation of dopamine D1 or D2 receptors protects against the loss of dopaminergic fibres in the striatum and loss of dopaminergic neurons in the substantia nigra. Protection by D1 receptor inactivation is due to blockade of hypothermia, reduced dopamine content and turnover and increased stored vesicular dopamine in D1R(-/-) mice. However, the neuroprotective impact of D2 receptor inactivation is partially dependent on an effect on body temperature, as well as on the blockade of dopamine reuptake by decreased dopamine transporter activity, which results in reduced intracytosolic dopamine levels in D2R(-/-) mice.

  5. Oscillating from Neurosecretion to Multitasking Dopamine Neurons.

    PubMed

    Grattan, David R; Akopian, Armen N

    2016-04-26

    In this issue of Cell Reports, Stagkourakis et al. (2016) report that oscillating hypothalamic TIDA neurons, previously thought to be simple neurosecretory neurons controlling pituitary prolactin secretion, control dopamine output via autoregulatory mechanisms and thus could potentially regulate other physiologically important hypothalamic neuronal circuits.

  6. Oscillating from Neurosecretion to Multitasking Dopamine Neurons

    PubMed Central

    Grattan, David R.; Akopian, Armen N.

    2016-01-01

    In this issue of Cell Reports, Stagkourakis et al. (2016) report that oscillating hypothalamic TIDA neurons, previously thought to be simple neurosecretory neurons controlling pituitary prolactin secretion, control dopamine output via autoregulatory mechanisms and thus could potentially regulate other physiologically important hypothalamic neuronal circuits. PMID:27119847

  7. Impulsivity, Stimulant Abuse, and Dopamine Receptor Signaling.

    PubMed

    London, E D

    2016-01-01

    The nonmedical use of amphetamine-type stimulants is a worldwide problem, with substantial medical and social consequences. Nonetheless, the identification of a pharmacological treatment for amphetamine use disorder remains elusive. Stimulant users exhibit neurochemical evidence of dopamine-system dysfunction as well as impulsive behaviors that may interfere with the success of treatments for their addiction. This review focuses on the potential role of dopaminergic neurotransmission in impulsivity, both in healthy individuals and chronic stimulant users who meet criteria for methamphetamine dependence. Presented are findings related to the potential contributions of signaling through dopamine D1- and D2-type receptors to self-control impulsivity in methamphetamine- dependent users. The information available points to signaling through striatal D2-type dopamine receptors as a potential therapeutic target for stimulant use disorders, but medications that target D2-type dopamine receptors have not been successful in treating stimulant-use disorders, possibly because D2-type receptors are downregulated. Other means to augment D2-type receptor signaling are therefore under consideration, and one promising approach is the addition of exercise training as an adjunct to behavioral treatment for addiction. PMID:27288074

  8. Oscillating from Neurosecretion to Multitasking Dopamine Neurons.

    PubMed

    Grattan, David R; Akopian, Armen N

    2016-04-26

    In this issue of Cell Reports, Stagkourakis et al. (2016) report that oscillating hypothalamic TIDA neurons, previously thought to be simple neurosecretory neurons controlling pituitary prolactin secretion, control dopamine output via autoregulatory mechanisms and thus could potentially regulate other physiologically important hypothalamic neuronal circuits. PMID:27119847

  9. 'Dopamine-first' mechanism enables the rational engineering of the norcoclaurine synthase aldehyde activity profile.

    PubMed

    Lichman, Benjamin R; Gershater, Markus C; Lamming, Eleanor D; Pesnot, Thomas; Sula, Altin; Keep, Nicholas H; Hailes, Helen C; Ward, John M

    2015-03-01

    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

  10. Determination of dopamine in synthetic cerebrospinal fluid by SWV with a graphite-polyurethane composite electrode.

    PubMed

    de Toledo, R A; Santos, M C; Cavalheiro, E T G; Mazo, L H

    2005-03-01

    This work describes an electroanalytical investigation of dopamine using cyclic voltammetry (CV) and the graphite-polyurethane composite electrode (GPU). In CV studies, well-defined redox peaks characterize the oxidation process at the GPU electrode, which is indicative of electrocatalytic effects associated with active sites on the GPU electrode surface. A new analytical methodology was developed using the GPU electrode and square wave voltammetry (SWV) in BR buffer solution (0.1 mol L(-1); pH 7.4). Analytical curves were constructed under optimized conditions (f=60s(-1), DeltaE(a)=50 mV, DeltaE(I)=2 mV) and detection and quantification limits of 6.4x10(-8) mol L(-1) (12.1 microg L(-1)) and 5.2x10(-6) mol L(-1) (0.9 mg L(-1)), respectively, were achieved. The precision of the method was checked by performing ten successive measurements for a 9.9x10(-6) mol L(-1) dopamine solution. For intra-assay and inter-assay precisions, the relative standard deviations were 1.9 and 2.3%, respectively. In order to evaluate the developed methodology, the determination of dopamine was performed with good sensitivity and selectivity, without the interference of ascorbic acid in synthetic cerebrospinal fluid, which indicates that the new methodology enables reliable analysis of dopamine. PMID:15714300

  11. Parkin expression profile in dopamine d3 receptor knock-out mice brains.

    PubMed

    D'Agata, Velia; Tiralongo, Adriana; Castorina, Alessandro; Leggio, Gian Marco; Micale, Vincenzo; Carnazza, Maria Luisa; Drago, Filippo

    2009-02-01

    Patients affected by autosomic recessive juvenile parkinsonism (ARJP) exhibit parkin gene mutations with brain decrease in dopamine D2/D3 binding sites. To date, there are no data indicating whether the reduction in dopamine D3 receptors (DRD3) may be associated with the expression of specific parkin variants. In the present study we investigated parkin expression profile in DRD3 knock-out mice brains. RT-PCR analysis was performed to assess qualitative changes in parkin isoforms' distribution pattern and in exons' expression both in wild type controls and dopamine D3 receptor's knock-out mice. Real-time PCR was performed to quantify single exons mRNA. Results demonstrated that exons 1, 2, 4, 6, 7, 8, were more expressed in wild type compared to dopamine D3 receptor KO mice brains while some other (3, 9, 10) were lower expressed. The expression levels of exons 5, 11 and 12 did not change in both animal groups. Our analysis was confirmed by western blot, which showed that parkin protein levels were influenced by the absence of DRD3.

  12. Homology Modeling of Dopamine D2 and D3 Receptors: Molecular Dynamics Refinement and Docking Evaluation

    PubMed Central

    Platania, Chiara Bianca Maria; Salomone, Salvatore; Leggio, Gian Marco; Drago, Filippo; Bucolo, Claudio

    2012-01-01

    Dopamine (DA) receptors, a class of G-protein coupled receptors (GPCRs), have been targeted for drug development for the treatment of neurological, psychiatric and ocular disorders. The lack of structural information about GPCRs and their ligand complexes has prompted the development of homology models of these proteins aimed at structure-based drug design. Crystal structure of human dopamine D3 (hD3) receptor has been recently solved. Based on the hD3 receptor crystal structure we generated dopamine D2 and D3 receptor models and refined them with molecular dynamics (MD) protocol. Refined structures, obtained from the MD simulations in membrane environment, were subsequently used in molecular docking studies in order to investigate potential sites of interaction. The structure of hD3 and hD2L receptors was differentiated by means of MD simulations and D3 selective ligands were discriminated, in terms of binding energy, by docking calculation. Robust correlation of computed and experimental Ki was obtained for hD3 and hD2L receptor ligands. In conclusion, the present computational approach seems suitable to build and refine structure models of homologous dopamine receptors that may be of value for structure-based drug discovery of selective dopaminergic ligands. PMID:22970199

  13. 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

  14. Regulation of dopamine transporter trafficking by intracellular amphetamine.

    PubMed

    Kahlig, Kristopher M; Lute, Brandon J; Wei, Yuqiang; Loland, Claus J; Gether, Ulrik; Javitch, Jonathan A; Galli, Aurelio

    2006-08-01

    The dopamine (DA) transporter (DAT) mediates the removal of released DA. DAT is the major molecular target responsible for the rewarding properties and abuse potential of the psychostimulant amphetamine (AMPH). AMPH has been shown to reduce the number of DATs at the cell surface, and this AMPH-induced cell surface DAT redistribution may result in long-lasting changes in DA homeostasis. The molecular mechanism by which AMPH induces trafficking is not clear. Because AMPH is a substrate, we do not know whether extracellular AMPH stimulates trafficking through its interaction with DAT and subsequent alteration in DAT function, thereby triggering intracellular signaling or whether AMPH must be transported and then act intracellularly. In agreement with our previous studies, extracellular AMPH caused cytosolic redistribution of the wild-type human DAT (WT-hDAT). However, AMPH did not induce cytosolic redistribution in an uptake-impaired hDAT (Y335A-hDAT) that still binds AMPH. The divalent cation zinc (Zn(2+)) inhibits WT-hDAT activity, but it restores Y335A-hDAT uptake. Coadministration of Zn(2+) and AMPH consistently reduced WT-hDAT trafficking but stimulated cytosolic redistribution of Y335A-hDAT. Furthermore, direct intracellular application of AMPH, via a whole-cell patch pipette, stimulated the trafficking of Y335A-hDAT. Taken together, these data suggest that the DAT transport cycle is not required for AMPH-induced down-regulation and that an increase of intracellular AMPH is an essential component of DAT redistribution.

  15. Reduced dopamine transporter expression in the amygdala of subjects diagnosed with schizophrenia.

    PubMed

    Markota, Matej; Sin, Jessica; Pantazopoulos, Harry; Jonilionis, Rebecca; Berretta, Sabina

    2014-09-01

    A disruption of dopaminergic transmission in the amygdala of subjects with schizophrenia was proposed as a main contributor to pathophysiological and clinical manifestations of this disorder. We tested the hypothesis that the expression of the dopamine transporter (DAT) is decreased in the amygdala of subjects with schizophrenia. In normal control, schizophrenic subjects and bipolar disorder subjects, we measured numerical density of axon varicosities immunoreactive (IR) for DAT in the lateral (LN), basal, accessory basal (ABN), and cortical (CO) nuclei and intercalated cell masses (ITCM) of the amygdala. Tyrosine hydroxylase (TH)-IR and dopamine beta-hydroxylase (DBH)-IR varicosities were measured to test for potential loss of varicosities and serotonin transporter (5HTT)-IR for involvement of the serotoninergic system. Among several potential confounding variables tested, particular emphasis was placed on exposure to therapeutic drugs. In schizophrenic subjects, DAT-IR varicosities were decreased in LN (P = .0002), ABN (P = .013), and CO (P = .0001) in comparison with controls, and in comparison with bipolar disorder subjects in LN (P = .004) and CO (P = .002). DBH-IR varicosities were decreased in ABN (P = .008) and ITCM (P = .017), compared with controls. TH- and 5HTT-IR varicosities were not altered. No changes were detected in bipolar disorder. Taken together with TH and DBH findings, reductions of DAT-IR varicosities point to decreased DAT expression in dopaminergic terminals in the amygdala of subjects with schizophrenia. This DAT decrease may disrupt dopamine uptake, leading to increased dopaminergic synaptic transmission and spillage into the extracellular space with activation of extrasynaptic dopamine receptors. Concurrent decrease of noradrenaline in the ABN may disrupt memory consolidation.

  16. Methamphetamine Self-Administration in Mice Decreases GIRK Channel-Mediated Currents in Midbrain Dopamine Neurons

    PubMed Central

    Sharpe, Amanda L.; Varela, Erika; Bettinger, Lynne

    2015-01-01

    Background: Methamphetamine is a psychomotor stimulant with abuse liability and a substrate for catecholamine uptake transporters. Acute methamphetamine elevates extracellular dopamine, which in the midbrain can activate D2 autoreceptors to increase a G-protein gated inwardly rectifying potassium (GIRK) conductance that inhibits dopamine neuron firing. These studies examined the neurophysiological consequences of methamphetamine self-administration on GIRK channel-mediated currents in dopaminergic neurons in the substantia nigra and ventral tegmental area. Methods: Male DBA/2J mice were trained to self-administer intravenous methamphetamine. A dose response was conducted as well as extinction and cue-induced reinstatement. In a second study, after at least 2 weeks of stable self-administration of methamphetamine, electrophysiological brain slice recordings were conducted on dopamine neurons from self-administering and control mice. Results: In the first experiment, ad libitum-fed, nonfood-trained mice exhibited a significant increase in intake and locomotion following self-administration as the concentration of methamphetamine per infusion was increased (0.0015–0.15mg/kg/infusion). Mice exhibited extinction in responding and cue-induced reinstatement. In the second experiment, dopamine cells in both the substantia nigra and ventral tegmental area from adult mice with a history of methamphetamine self-administration exhibited significantly smaller D2 and GABAB receptor-mediated currents compared with control mice, regardless of whether their daily self-administration sessions had been 1 or 4 hours. Interestingly, the effects of methamphetamine self-administration were not present when intracellular calcium was chelated by including BAPTA in the recording pipette. Conclusions: Our results suggest that methamphetamine self-administration decreases GIRK channel-mediated currents in dopaminergic neurons and that this effect may be calcium dependent. PMID:25522412

  17. Inhibitive effects of Fructus Psoraleae extract on dopamine transporter and noradrenaline transporter.

    PubMed

    Zhao, Gang; Li, Sheng; Qin, Guo-Wei; Fei, Jian; Guo, Li-He

    2007-07-25

    A petroleum ether extract (FP) from Fructus Psoraleae, seeds of Psoralea corylifolia L. (Leguminosae), was found to strongly inhibit dopamine (DA) uptake by dopamine transporter (DAT) heterogeneously expressed cells (D8 cells) and noradrenaline (NE) uptake by noradrenaline transporter (NET) heterogeneously expressed cells, which, however, had no effect on gamma-aminobutyric acid transporter heterogeneously expressed cells and serotonin transporter heterogeneously expressed cells at the concentration up to 100 microg/ml. These inhibitory effects were also confirmed by experiments on SK-N-SH cell line and synaptosomes from rats' brains. In addition, FP showed a significantly mitigating effect on 1-methyl-4-pyridinium induced injury of D8 cells. Meanwhile, FP dose-dependently reduced the binding of tritium-labeled cocaine analog (-)-2beta-carbomethoxy-3beta-(4-fluorophenyl) tropane to DAT of D8 cells, which suggests that FP may inhibit DAT activity in the same way as cocaine does. Behavioral study showed FP had a long-lasting stimulant effects on the activity of intact mice and reserpinized mice. So FP is proposed as a kind of DAT and NET inhibitor and may be involved in the process of regulating the DA and NE system, and FP or its unknown bioactive compounds may be developed into new medicines for disorders such as Parkinson's disease, depression, Attention Deficit Hyperactivity Disorder (ADHD) or cocaine addiction.

  18. Modulating dopamine release by optogenetics in transgenic mice reveals terminal dopaminergic dynamics

    PubMed Central

    Lu, Yao; Driscoll, Nicolette; Ozden, Ilker; Yu, Zeyang; Nurmikko, Arto V.

    2015-01-01

    Abstract. Dopamine (DA) release and uptake dynamics in the nucleus accumbens (NAc) have important implications for neurological diseases and mammalian animal behaviors. We demonstrate here the use of cell-type-specific optogenetic targeting in conjunction with fast-scan cyclic voltammetry applied to brain slices prepared from specifically tailored transgenic mice, which conditionally express channelrhodopsin-2 (ChR2) through dopamine transporter (DAT)-Cre. Terminal dopaminergic dynamics and the direct manipulation of induced DA release level by controlling light intensity, pulse width, and the shape of stimulation waveforms were studied. Effective cell terminal-targeting optogenetic induction of DA release at physiological levels in NAc is demonstrated and discussed. It was found that delivering more light energy by increasing stimulation intensity and length is not the only way to control DA release; the temporal shape of the stimulus waveform at light onset is also critically related to induced DA concentrations. In addition, DA uptake dynamics as well as the recovery of the presynaptic releasable DA pool are studied and modeled. More broadly, our experimental findings provide important further evidence for effectively applying optogenetics to induce neurotransmitter release in the behaviorally relevant region of the brain in a highly cell-type selective context. PMID:26171413

  19. Modulating dopamine release by optogenetics in transgenic mice reveals terminal dopaminergic dynamics.

    PubMed

    Lu, Yao; Driscoll, Nicolette; Ozden, Ilker; Yu, Zeyang; Nurmikko, Arto V

    2015-07-01

    Dopamine (DA) release and uptake dynamics in the nucleus accumbens (NAc) have important implications for neurological diseases and mammalian animal behaviors. We demonstrate here the use of cell-type-specific optogenetic targeting in conjunction with fast-scan cyclic voltammetry applied to brain slices prepared from specifically tailored transgenic mice, which conditionally express channelrhodopsin-2 (ChR2) through dopamine transporter (DAT)-Cre. Terminal dopaminergic dynamics and the direct manipulation of induced DA release level by controlling light intensity, pulse width, and the shape of stimulation waveforms were studied. Effective cell terminal-targeting optogenetic induction of DA release at physiological levels in NAc is demonstrated and discussed. It was found that delivering more light energy by increasing stimulation intensity and length is not the only way to control DA release; the temporal shape of the stimulus waveform at light onset is also critically related to induced DA concentrations. In addition, DA uptake dynamics as well as the recovery of the presynaptic releasable DA pool are studied and modeled. More broadly, our experimental findings provide important further evidence for effectively applying optogenetics to induce neurotransmitter release in the behaviorally relevant region of the brain in a highly cell-type selective context.

  20. 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.

  1. X-ray structures of Drosophila dopamine transporter in complex with nisoxetine and reboxetine

    PubMed Central

    Gouaux, Eric

    2015-01-01

    Most antidepressants elicit their therapeutic benefits through selective blockade of Na+−Cl− - coupled neurotransmitters transporters. Here we report x-ray structures of the Drosophila melanogaster dopamine transporter in complexes with the polycyclic antidepressants nisoxetine or reboxetine. The inhibitors stabilize the transporter in an outward-open conformation by occupying the substrate binding site. These structures explain how interactions between the binding pocket and substituents on the aromatic rings of antidepressants modulate drug – transporter selectivity. PMID:25961798

  2. Characterization of [(3) H]LS-3-134, a novel arylamide phenylpiperazine D3 dopamine receptor selective radioligand.

    PubMed

    Rangel-Barajas, Claudia; Malik, Maninder; Taylor, Michelle; Neve, Kim A; Mach, Robert H; Luedtke, Robert R

    2014-11-01

    LS-3-134 is a substituted N-phenylpiperazine derivative that has been reported to exhibit: (i) high-affinity binding (Ki value 0.2 nM) at human D3 dopamine receptors, (ii) > 100-fold D3 versus D2 dopamine receptor subtype binding selectivity, and (iii) low-affinity binding (Ki  > 5000 nM) at sigma 1 and sigma 2 receptors. Based upon a forskolin-dependent activation of the adenylyl cyclase inhibition assay, LS-3-134 is a weak partial agonist at both D2 and D3 dopamine receptor subtypes (29% and 35% of full agonist activity, respectively). In this study, [(3) H]-labeled LS-3-134 was prepared and evaluated to further characterize its use as a D3 dopamine receptor selective radioligand. Kinetic and equilibrium radioligand binding studies were performed. This radioligand rapidly reaches equilibrium (10-15 min at 37°C) and binds with high affinity to both human (Kd  = 0.06 ± 0.01 nM) and rat (Kd  = 0.2 ± 0.02 nM) D3 receptors expressed in HEK293 cells. Direct and competitive radioligand binding studies using rat caudate and nucleus accumbens tissue indicate that [(3) H]LS-3-134 selectively binds a homogeneous population of binding sites with a dopamine D3 receptor pharmacological profile. Based upon these studies, we propose that [(3) H]LS-3-134 represents a novel D3 dopamine receptor selective radioligand that can be used for studying the expression and regulation of the D3 dopamine receptor subtype.

  3. Mu Opioid Receptor Modulation of Dopamine Neurons in the Periaqueductal Gray/Dorsal Raphe: A Role in Regulation of Pain.

    PubMed

    Li, Chia; Sugam, Jonathan A; Lowery-Gionta, Emily G; McElligott, Zoe A; McCall, Nora M; Lopez, Alberto J; McKlveen, Jessica M; Pleil, Kristen E; Kash, Thomas L

    2016-07-01

    The periaqueductal gray (PAG) is a brain region involved in nociception modulation, and an important relay center for the descending nociceptive pathway through the rostral ventral lateral medulla. Given the dense expression of mu opioid receptors and the role of dopamine in pain, the recently characterized dopamine neurons in the ventral PAG (vPAG)/dorsal raphe (DR) region are a potentially critical site for the antinociceptive actions of opioids. The objectives of this study were to (1) evaluate synaptic modulation of the vPAG/DR dopamine neurons by mu opioid receptors and to (2) dissect the anatomy and neurochemistry of these neurons, in order to assess the downstream loci and functions of their activation. Using a mouse line that expresses eGFP under control of the tyrosine hydroxylase (TH) promoter, we found that mu opioid receptor activation led to a decrease in inhibitory inputs onto the vPAG/DR dopamine neurons. Furthermore, combining immunohistochemistry, optogenetics, electrophysiology, and fast-scan cyclic voltammetry in a TH-cre mouse line, we demonstrated that these neurons also express the vesicular glutamate type 2 transporter and co-release dopamine and glutamate in a major downstream projection structure-the bed nucleus of the stria terminalis. Finally, activation of TH-positive neurons in the vPAG/DR using Gq designer receptors exclusively activated by designer drugs displayed a supraspinal, but not spinal, antinociceptive effect. These results indicate that vPAG/DR dopamine neurons likely play a key role in opiate antinociception, potentially via the activation of downstream structures through dopamine and glutamate release.

  4. Dopamine down-regulation of protein L-isoaspartyl methyltransferase is dependent on reactive oxygen species in SH-SY5Y cells.

    PubMed

    Ouazia, D; Levros, L-C; Rassart, E; Desrosiers, R R

    2014-05-16

    Parkinson's disease (PD) is a chronic and progressive neurological disorder that is characterized by the loss of dopaminergic neurons in the substantia nigra. Dopamine, via the oxidative stress that it generates in the cytosol, could contribute to the selective loss of neurons observed in PD. Protein L-isoaspartyl methyltransferase (PIMT) is an enzyme that repairs L-isoaspartyl-containing proteins and possesses anti-apoptotic properties. PIMT expression has been shown to decrease with age. Together, these observations prompted us to investigate whether dopamine can regulate PIMT expression in SH-SY5Y neuroblastoma cells. Here, we report that dopamine down-regulated PIMT at both gene and protein levels. The same inhibition of PIMT protein level was caused by the electron transport chain inhibitor, rotenone, which was accompanied, in both cases, by an increase in cell death and reactive oxygen species (ROS) production. In fact, pre-treatment with the antioxidant N-acetyl cysteine blocked PIMT dopamine-associated down-regulation. PCMT1 promoter mapping experiments allowed the identification of two regions that showed different sensitivity to DA action. A first region localized between 61 and 94bp upstream of transcription start site was very sensitive to dopamine inhibition while a second region between 41 and 61bp appeared more resistant to dopamine inhibitory effect. The inhibition of PCMT1 promoter activity was mediated by dopamine-induced ROS since it was prevented by the hydroxyl radical scavenger N,N'-dimethylthiourea. Conversely, H2O2 inhibited in a dose-dependent manner the transcriptional activity of PCMT1 promoter. Therefore, our findings identified new molecular mechanisms, cytosolic dopamine and its resulting ROS, as inhibitors of PIMT expression. This suggests that ROS generated from cytosolic dopamine could reduce both the PCMT1 gene promoter activity and the PIMT protein level thus decreasing its capacity to repair proteins involved in apoptosis and

  5. Heterogeneity of dopamine neuron activity across traits and states

    PubMed Central

    Marinelli, Michela; McCutcheon, James E.

    2014-01-01

    Midbrain dopamine neurons fire irregularly, with interspersed clusters of high-frequency spikes, commonly called ‘bursts’. In this review we examine such heterogeneity in activity, and provide insight into how it can participate in psychiatric conditions such as drug addiction. We first describe several techniques used to evaluate dopamine neuron activity, and comment on the different measures that each provides. We next describe the activity of dopamine neurons in ‘basal’ conditions. Specifically, we discuss how the use of anesthesia and reduced preparations may alter aspects of dopamine cell activity, and how there is heterogeneity across species and regions. We also describe how dopamine cell firing changes throughout the peri-adolescent period and how dopamine neuron activity differs across the population. In the final section, we discuss how dopamine neuron activity changes in response to life events. First, we focus attention on drugs of abuse. Drugs themselves change firing activity through a variety of mechanisms, with effects on firing while drug is present differing from those seen after drug discontinuation. We then review how stimuli that are rewarding, aversive, or salient can evoke changes in firing rate and discharge pattern of dopamine neurons, and provide behavioral relevance of dopamine signaling. Finally, we discuss how stress can modulate dopamine neuron firing and how this may contribute to the role that stressful experiences play in psychiatric disorders such as addiction and depression. PMID:25084048

  6. Optical suppression of drug-evoked phasic dopamine release.

    PubMed

    McCutcheon, James E; Cone, Jackson J; Sinon, Christopher G; Fortin, Samantha M; Kantak, Pranish A; Witten, Ilana B; Deisseroth, Karl; Stuber, Garret D; Roitman, Mitchell F

    2014-01-01

    Brief fluctuations in dopamine concentration (dopamine transients) play a key role in behavior towards rewards, including drugs of abuse. Drug-evoked dopamine transients may result from actions at both dopamine cell bodies and dopamine terminals. Inhibitory opsins can be targeted to dopamine neurons permitting their firing activity to be suppressed. However, as dopamine transients can become uncoupled from firing, it is unknown whether optogenetic hyperpolarization at the level of the soma is able to suppress dopamine transients. Here, we used in vivo fast-scan cyclic voltammetry to record transients evoked by cocaine and raclopride in nucleus accumbens (NAc) of urethane-anesthetized rats. We targeted halorhodopsin (NpHR) specifically to dopamine cells by injecting Cre-inducible virus into ventral tegmental area (VTA) of transgenic rats that expressed Cre recombinase under control of the tyrosine hydroxylase promoter (TH-Cre(+) rats). Consistent with previous work, co-administration of cocaine and raclopride led to the generation of dopamine transients in NAc shell. Illumination of VTA with laser strongly suppressed the frequency of transients in NpHR-expressing rats, but not in control rats. Laser did not have any effect on amplitude of transients. Thus, optogenetics can effectively reduce the occurrence of drug-evoked transients and is therefore a suitable approach for studying the functional role of such transients in drug-associated behavior.

  7. Syntaxin 1A interaction with the dopamine transporter promotes amphetamine-induced dopamine efflux.

    PubMed

    Binda, Francesca; Dipace, Concetta; Bowton, Erica; Robertson, Sabrina D; Lute, Brandon J; Fog, Jacob U; Zhang, Minjia; Sen, Namita; Colbran, Roger J; Gnegy, Margaret E; Gether, Ulrik; Javitch, Jonathan A; Erreger, Kevin; Galli, Aurelio

    2008-10-01

    The soluble N-ethylmaleimide-sensitive factor attachment protein receptor protein syntaxin 1A (SYN1A) interacts with and regulates the function of transmembrane proteins, including ion channels and neurotransmitter transporters. Here, we define the first 33 amino acids of the N terminus of the dopamine (DA) transporter (DAT) as the site of direct interaction with SYN1A. Amphetamine (AMPH) increases the association of SYN1A with human DAT (hDAT) in a heterologous expression system (hDAT cells) and with native DAT in murine striatal synaptosomes. Immunoprecipitation of DAT from the biotinylated fraction shows that the AMPH-induced increase in DAT/SYN1A association occurs at the plasma membrane. In a superfusion assay of DA efflux, cells overexpressing SYN1A exhibited significantly greater AMPH-induced DA release with respect to control cells. By combining the patch-clamp technique with amperometry, we measured DA release under voltage clamp. At -60 mV, a physiological resting potential, AMPH did not induce DA efflux in hDAT cells and DA neurons. In contrast, perfusion of exogenous SYN1A (3 microM) into the cell with the whole-cell pipette enabled AMPH-induced DA efflux at -60 mV in both hDAT cells and DA neurons. It has been shown recently that Ca2+/calmodulin-dependent protein kinase II (CaMKII) is activated by AMPH and regulates AMPH-induced DA efflux. Here, we show that AMPH-induced association between DAT and SYN1A requires CaMKII activity and that inhibition of CaMKII blocks the ability of exogenous SYN1A to promote DA efflux. These data suggest that AMPH activation of CaMKII supports DAT/SYN1A association, resulting in a mode of DAT capable of DA efflux.

  8. Structure of the Human Dopamine D3 Receptor in Complex with a D2/D3 Selective Antagonist

    SciTech Connect

    Chien, Ellen Y.T.; Liu, Wei; Zhao, Qiang; Katritch, Vsevolod; Han, Gye Won; Hanson, Michael A.; Shi, Lei; Newman, Amy Hauck; Javitch, Jonathan A.; Cherezov, Vadim; Stevens, Raymond C.

    2010-11-30

    Dopamine modulates movement, cognition, and emotion through activation of dopamine G protein-coupled receptors in the brain. The crystal structure of the human dopamine D3 receptor (D3R) in complex with the small molecule D2R/D3R-specific antagonist eticlopride reveals important features of the ligand binding pocket and extracellular loops. On the intracellular side of the receptor, a locked conformation of the ionic lock and two distinctly different conformations of intracellular loop 2 are observed. Docking of R-22, a D3R-selective antagonist, reveals an extracellular extension of the eticlopride binding site that comprises a second binding pocket for the aryl amide of R-22, which differs between the highly homologous D2R and D3R. This difference provides direction to the design of D3R-selective agents for treating drug abuse and other neuropsychiatric indications.

  9. Pharmacological profile of the abeorphine 201-678, a potent orally active and long lasting dopamine agonist

    SciTech Connect

    Jaton, A.L.; Giger, R.K.A.; Vigouret, J.M.; Enz, A.; Frick, W.; Closse, A.; Markstein, R.

    1986-01-13

    The central dopaminergic effects of an abeorphine derivative 201-678 were compared to those of apomorphine and bromocriptine in different model systems. After oral administration, this compound induced contralateral turning in rats with 6-hydroxydopamine induced nigral lesions and exhibited strong anti-akinetic properties in rats with 6-hydroxydopamine induced hypothalamic lesions. It decreased dopamine metabolism in striatum and cortex, but did not modify noradrenaline and serotonin metabolism in the rat brain. 201-678 counteracted the in vivo increase of tyrosine hydroxylase activity induced by ..gamma..-butyrolactone. In vitro it stimulated DA-sensitive adenylate cyclase and inhibited acetylcholine release from rat striatal slices. This compound had high affinity for /sup 3/H-dopamine and /sup 3/H-clonidine binding sites. These results indicate that 201-678 is a potent, orally active dopamine agonist with a long duration of action. Furthermore it appears more selective than other dopaminergic drugs. 29 references, 5 figures, 3 tables.

  10. 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

  11. 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

  12. Dopamine D1 receptor activation regulates the expression of the estrogen synthesis gene aromatase B in radial glial cells

    PubMed Central

    Xing, Lei; McDonald, Heather; Da Fonte, Dillon F.; Gutierrez-Villagomez, Juan M.; Trudeau, Vance L.

    2015-01-01

    Radial glial cells (RGCs) are abundant stem-like non-neuronal progenitors that are important for adult neurogenesis and brain repair, yet little is known about their regulation by neurotransmitters. Here we provide evidence for neuronal-glial interactions via a novel role for dopamine to stimulate RGC function. Goldfish were chosen as the model organism due to the abundance of RGCs and regenerative abilities of the adult central nervous system. A close anatomical relationship was observed between tyrosine hydroxylase-positive catecholaminergic cell bodies and axons and dopamine-D1 receptor expressing RGCs along the ventricular surface of telencephalon, a site of active neurogenesis. A primary cell culture model was established and immunofluorescence analysis indicates that in vitro RGCs from female goldfish retain their major characteristics in vivo, including expression of glial fibrillary acidic protein and brain lipid binding protein. The estrogen synthesis enzyme aromatase B is exclusively found in RGCs, but this is lost as cells differentiate to neurons and other glial types in adult teleost brain. Pharmacological experiments using the cultured RGCs established that specific activation of dopamine D1 receptors up-regulates aromatase B mRNA through a cyclic adenosine monophosphate-dependent molecular mechanism. These data indicate that dopamine enhances the steroidogenic function of this neuronal progenitor cell. PMID:26388722

  13. Dopamine in the Brain: Hypothesizing Surfeit or Deficit Links to Reward and Addiction

    PubMed Central

    Blum, Kenneth; Thanos, Peter K.; Oscar-Berman, Marlene; Febo, Marcelo; Baron, David; Badgaiyan, Rajendra D.; Gardner, Eliot; Demetrovics, Zsolt; Fahlke, Claudia; Haberstick, Brett C.; Dushaj, Kristina; Gold, Mark S.

    2016-01-01

    Recently there has been debate concerning the role of brain dopamine in reward and addiction. David Nutt and associates eloquently proposed that dopamine (DA) may be central to psycho stimulant dependence and some what important for alcohol, but not important for opiates, nicotine or even cannabis. Others have also argued that surfeit theories can explain for example cocaine seeking behavior as well as non-substance-related addictive behaviors. It seems prudent to distinguish between what constitutes “surfeit” compared to” deficit” in terms of short-term (acute) and long-term (chronic) brain reward circuitry responsivity. In an attempt to resolve controversy regarding the contributions of mesolimbic DA systems to reward, we review the three main competing explanatory categories: “liking”, “learning”, and “wanting”. They are (a) the hedonic impact -liking reward, (b) the ability to predict rewarding effects-learning and (c) the incentive salience of reward-related stimuli -wanting. In terms of acute effects, most of the evidence seems to favor the “surfeit theory”. Due to preferential dopamine release at mesolimbic-VTA-caudate-accumbens loci most drugs of abuse and Reward Deficiency Syndrome (RDS) behaviors have been linked to heightened feelings of well-being and hyperdopaminergic states.The “dopamine hypotheses” originally thought to be simple, is now believed to be quite complex and involves encoding the set point of hedonic tone, encoding attention, reward expectancy, and incentive motivation. Importantly, Willuhn et al. shows that in a self-administration paradigm, (chronic) excessive use of cocaine is caused by decreased phasic dopamine signaling in the striatum. In terms of chronic addictions, others have shown a blunted responsivity at brain reward sites with food, nicotine, and even gambling behavior. Finally, we are cognizant of the differences in dopaminergic function as addiction progresses and argue that relapse may be tied

  14. Is Parkinson's disease a vesicular dopamine storage disorder? Evidence from a study in isolated synaptic vesicles of human and nonhuman primate striatum.

    PubMed

    Pifl, Christian; Rajput, Alex; Reither, Harald; Blesa, Javier; Cavada, Carmen; Obeso, José A; Rajput, Ali H; Hornykiewicz, Oleh

    2014-06-11

    The cause of degeneration of nigrostriatal dopamine (DA) neurons in idiopathic Parkinson's disease (PD) is still unknown. Intraneuronally, DA is largely confined to synaptic vesicles where it is protected from metabolic breakdown. In the cytoplasm, however, free DA can give rise to formation of cytotoxic free radicals. Normally, the concentration of cytoplasmic DA is kept at a minimum by continuous pumping activity of the vesicular monoamine transporter (VMAT)2. Defects in handling of cytosolic DA by VMAT2 increase levels of DA-generated oxy radicals ultimately resulting in degeneration of DAergic neurons. Here, we isolated for the first time, DA storage vesicles from the striatum of six autopsied brains of PD patients and four controls and measured several indices of vesicular DA storage mechanisms. We found that (1) vesicular uptake of DA and binding of the VMAT2-selective label [(3)H]dihydrotetrabenazine were profoundly reduced in PD by 87-90% and 71-80%, respectively; (2) after correcting for DA nerve terminal loss, DA uptake per VMAT2 transport site was significantly reduced in PD caudate and putamen by 53 and 55%, respectively; (3) the VMAT2 transport defect appeared specific for PD as it was not present in Macaca fascicularis (7 MPTP and 8 controls) with similar degree of MPTP-induced nigrostriatal neurodegeneration; and (4) DA efflux studies and measurements of acidification in the vesicular preparations suggest that the DA storage impairment was localized at the VMAT2 protein itself. We propose that this VMAT2 defect may be an early abnormality promoting mechanisms leading to nigrostriatal DA neuron death in PD.

  15. Proton uptake associated with the reduction of the primary quinone Q(A) influences the binding site of the secondary quinone Q(B) in Rhodopseudomonas viridis photosynthetic reaction centers.

    PubMed

    Zachariae, U; Lancaster, C R

    2001-06-01

    Previously, two binding sites for the secondary quinone Q(B) in the photosynthetic reaction center (RC) from Rhodopseudomonas viridis were identified by X-ray crystallography, a 'proximal' binding site close to the non-heme iron, and a 'distal' site, displaced by 4.2 A along the path of the isoprenoid tail [C.R.D. Lancaster and H. Michel, Structure 5 (1997) 1339-1359]. The quinone ring planes in the two sites differ by roughly a 180 degrees rotation around the isoprenoid tail. Here we present molecular dynamics simulations, which support the theory of a spontaneous transfer of Q(B) between the distal site and the proximal site. In contrast to earlier computational studies on RCs, the molecular dynamics simulations of Q(B) migration resulted in a proximal Q(B) binding pattern identical to that of the crystallographic findings. Also, we demonstrate that the preference towards the proximal Q(B) location is not necessarily attributed to reduction of Q(B) to the semiquinone, but already to the preceding reduction of the primary quinone Q(A) and resulting protonation changes in the protein. Energy mapping of the Q(B) binding pocket indicates that the quinone ring rotation required for completion of the transfer between the two sites is improbable at the distal or proximal binding sites due to high potential barriers, but may be possible at a newly identified position near the distal binding site.

  16. Axiomatic methods, dopamine and reward prediction error.

    PubMed

    Caplin, Andrew; Dean, Mark

    2008-04-01

    The phasic firing rate of midbrain dopamine neurons has been shown to respond both to the receipt of rewarding stimuli, and the degree to which such stimuli are anticipated by the recipient. This has led to the hypothesis that these neurons encode reward prediction error (RPE)-the difference between how rewarding an event is, and how rewarding it was expected to be. However, the RPE model is one of a number of competing explanations for dopamine activity that have proved hard to disentangle, mainly because they are couched in terms of latent, or unobservable, variables. This article describes techniques for dealing with latent variables common in economics and decision theory, and reviews work that uses these techniques to provide simple, non-parametric tests of the RPE hypothesis, allowing clear differentiation between competing explanations.

  17. Dopamine neurons share common response function for reward prediction error

    PubMed Central

    Eshel, Neir; Tian, Ju; Bukwich, Michael; Uchida, Naoshige

    2016-01-01

    Dopamine neurons are thought to signal reward prediction error, or the difference between actual and predicted reward. How dopamine neurons jointly encode this information, however, remains unclear. One possibility is that different neurons specialize in different aspects of prediction error; another is that each neuron calculates prediction error in the same way. We recorded from optogenetically-identified dopamine neurons in the lateral ventral tegmental area (VTA) while mice performed classical conditioning tasks. Our tasks allowed us to determine the full prediction error functions of dopamine neurons and compare them to each other. We found striking homogeneity among individual dopamine neurons: their responses to both unexpected and expected rewards followed the same function, just scaled up or down. As a result, we could describe both individual and population responses using just two parameters. Such uniformity ensures robust information coding, allowing each dopamine neuron to contribute fully to the prediction error signal. PMID:26854803

  18. Dopamine in motivational control: rewarding, aversive, and alerting

    PubMed Central

    Bromberg-Martin, Ethan S.; Matsumoto, Masayuki; Hikosaka, Okihide

    2010-01-01

    SUMMARY Midbrain dopamine neurons are well known for their strong responses to rewards and their critical role in positive motivation. It has become increasingly clear, however, that dopamine neurons also transmit signals related to salient but non-rewarding experiences such as aversive and alerting events. Here we review recent advances in understanding the reward and non-reward functions of dopamine. Based on this data, we propose that dopamine neurons come in multiple types that are connected with distinct brain networks and have distinct roles in motivational control. Some dopamine neurons encode motivational value, supporting brain networks for seeking, evaluation, and value learning. Others encode motivational salience, supporting brain networks for orienting, cognition, and general motivation. Both types of dopamine neurons are augmented by an alerting signal involved in rapid detection of potentially important sensory cues. We hypothesize that these dopaminergic pathways for value, salience, and alerting cooperate to support adaptive behavior. PMID:21144997

  19. Dopamine neurons share common response function for reward prediction error.

    PubMed

    Eshel, Neir; Tian, Ju; Bukwich, Michael; Uchida, Naoshige

    2016-03-01

    Dopamine neurons are thought to signal reward prediction error, or the difference between actual and predicted reward. How dopamine neurons jointly encode this information, however, remains unclear. One possibility is that different neurons specialize in different aspects of prediction error; another is that each neuron calculates prediction error in the same way. We recorded from optogenetically identified dopamine neurons in the lateral ventral tegmental area (VTA) while mice performed classical conditioning tasks. Our tasks allowed us to determine the full prediction error functions of dopamine neurons and compare them to each other. We found marked homogeneity among individual dopamine neurons: their responses to both unexpected and expected rewards followed the same function, just scaled up or down. As a result, we were able to describe both individual and population responses using just two parameters. Such uniformity ensures robust information coding, allowing each dopamine neuron to contribute fully to the prediction error signal. PMID:26854803

  20. Redox reactivity of cerium oxide nanoparticles against dopamine.

    PubMed

    Hayat, Akhtar; Andreescu, Daniel; Bulbul, Gonca; Andreescu, Silvana

    2014-03-15

    The interaction between dopamine and the redox active cerium oxide nanoparticles, or nanoceria was studied using a suite of spectroscopic and surface characterization methods. Changes in the chemical reactivity and concentration of dopamine upon exposure to nanoceria was assessed in aqueous solutions and a human physiological fluid--human serum. The results indicate strong attachment of dopamine to the nanoparticle surface through oxidation followed by chemisorption of the oxidative product with formation of a charge transfer complex. Such oxidation/surface adsorption processes between nanoceria and dopamine lead to a reduction of the concentration of free dopamine in aqueous environments. These findings suggest that the redox reactivity of nanoceria may alter dopamine levels in biological systems exposed to these particles and indicate the need for a comprehensive assessment of the potential neurological consequences that might result from intended or unintended exposure to these particles. PMID:24461841

  1. Alcohol-induced alterations in dopamine modulation of prefrontal activity.

    PubMed

    Trantham-Davidson, Heather; Chandler, L Judson

    2015-12-01

    Long-term alcohol use leads to persistent cognitive deficits that may be associated with maladaptive changes in the neurocircuitry that mediates executive functions. Impairments caused by these changes can persist well into abstinence and have a negative impact on quality of life and job performance, and can increase the probability of relapse. Many of the changes that affect cognitive function appear to involve dysregulation of the mesocortical dopamine system. This includes changes in dopamine release and alterations in dopamine receptor expression and function in the medial prefrontal cortex (PFC). This review summarizes the cellular effects of acute and chronic ethanol exposure on dopamine release and dopamine receptor function in the PFC with the goal of providing greater understanding of the effects of alcohol-use disorders on the dopamine system and how this relates to deficits in the executive function of the PFC. PMID:26558348

  2. Dopamine neurons share common response function for reward prediction error.

    PubMed

    Eshel, Neir; Tian, Ju; Bukwich, Michael; Uchida, Naoshige

    2016-03-01

    Dopamine neurons are thought to signal reward prediction error, or the difference between actual and predicted reward. How dopamine neurons jointly encode this information, however, remains unclear. One possibility is that different neurons specialize in different aspects of prediction error; another is that each neuron calculates prediction error in the same way. We recorded from optogenetically identified dopamine neurons in the lateral ventral tegmental area (VTA) while mice performed classical conditioning tasks. Our tasks allowed us to determine the full prediction error functions of dopamine neurons and compare them to each other. We found marked homogeneity among individual dopamine neurons: their responses to both unexpected and expected rewards followed the same function, just scaled up or down. As a result, we were able to describe both individual and population responses using just two parameters. Such uniformity ensures robust information coding, allowing each dopamine neuron to contribute fully to the prediction error signal.

  3. Spectroscopic Signatures and Structural Motifs of Dopamine: a Computational Study

    NASA Astrophysics Data System (ADS)

    Srivastava, Santosh Kumar; Singh, Vipin Bahadur

    2016-06-01

    dopamine is significantly red shifted upon protonation at amino site. E. Dragicevic, J. Schiemann and B. Liss, Neuroscience, 2015, 284, 798. Y. T. Chien et al. Science, 2010, 330, 1091. Cabezas etal., J. Phys. Chem. Lett. 2013, 4, 486.

  4. DOPAMINE AND FOOD ADDICTION: LEXICON BADLY NEEDED

    PubMed Central

    Salamone, John D.; Correa, Mercè

    2012-01-01

    Over the last few years, the concept of food addiction has become a common feature in the scientific literature, as well as the popular press. Nevertheless, the use of the term “addiction” to describe pathological aspects of food intake in humans remains controversial, and even among those who affirm the validity of the concept, there is considerable disagreement about its utility for explaining the increasing prevalence of obesity throughout much of the world. An examination of the literature on food addiction indicates that mesolimbic and nigrostriatal dopamine systems often are cited as mechanisms that contribute to the establishment of food addiction. However, in reviewing this literature, it is important to have a detailed consideration of the complex nature of dopaminergic involvement in motivational processes. For example, although it is often stated that mesolimbic dopamine mediates “reward”, there is no standard or consistent technical meaning of this term. Moreover, there is a persistent tendency to link dopamine transmission with pleasure or hedonia, as opposed to other aspects of motivation or learning. The present paper provides a critical discussion of some aspects of the food addiction literature, viewed through the lens of recent findings and current theoretical views of dopaminergic involvement in food motivation. Furthermore, compulsive food intake and binge eating will be considered from an evolutionary perspective, in terms of the motivational subsystems that are involved in adaptive patterns of food consumption and seeking behaviors, and a consideration of how these could be altered in pathological conditions. PMID:23177385

  5. Linking unfounded beliefs to genetic dopamine availability

    PubMed Central

    Schmack, Katharina; Rössler, Hannes; Sekutowicz, Maria; Brandl, Eva J.; Müller, Daniel J.; Petrovic, Predrag; Sterzer, Philipp

    2015-01-01

    Unfounded convictions involving beliefs in the paranormal, grandiosity ideas or suspicious thoughts are endorsed at varying degrees among the general population. Here, we investigated the neurobiopsychological basis of the observed inter-individual variability in the propensity toward unfounded beliefs. One hundred two healthy individuals were genotyped for four polymorphisms in the COMT gene (rs6269, rs4633, rs4818, and rs4680, also known as val158met) that define common functional haplotypes with substantial impact on synaptic dopamine degradation, completed a questionnaire measuring unfounded beliefs, and took part in a behavioral experiment assessing perceptual inference. We found that greater dopamine availability was associated with a stronger propensity toward unfounded beliefs, and that this effect was statistically mediated by an enhanced influence of expectations on perceptual inference. Our results indicate that genetic differences in dopaminergic neurotransmission account for inter-individual differences in perceptual inference linked to the formation and maintenance of unfounded beliefs. Thus, dopamine might be critically involved in the processes underlying one's interpretation of the relationship between the self and the world. PMID:26483654

  6. Action Initiation Shapes Mesolimbic Dopamine Encoding of Future Rewards

    PubMed Central

    Syed, Emilie C.J.; Grima, Laura L.; Magill, Peter J.; Bogacz, Rafal; Brown, Peter; Walton, Mark E.

    2015-01-01

    It is widely held that dopamine signaling encodes predictions of future rewards and such predictions are regularly used to drive behavior, but the relationship between these two is poorly defined. Here, we demonstrate in rats that nucleus accumbens dopamine following a reward-predicting cue is attenuated unless movement is correctly initiated. These results demonstrate that dopamine release in this region is contingent upon correct action initiation and not just reward prediction. PMID:26642087

  7. Dopamine Does Double Duty in Motivating Cognitive Effort.

    PubMed

    Westbrook, Andrew; Braver, Todd S

    2016-02-17

    Cognitive control is subjectively costly, suggesting that engagement is modulated in relationship to incentive state. Dopamine appears to play key roles. In particular, dopamine may mediate cognitive effort by two broad classes of functions: (1) modulating the functional parameters of working memory circuits subserving effortful cognition, and (2) mediating value-learning and decision-making about effortful cognitive action. Here, we tie together these two lines of research, proposing how dopamine serves "double duty", translating incentive information into cognitive motivation. PMID:26889810

  8. The dopamine transporter: role in neurotoxicity and human disease

    SciTech Connect

    Bannon, Michael J. . E-mail: mbannon@med.wayne.edu

    2005-05-01

    The dopamine transporter (DAT) is a plasma membrane transport protein expressed exclusively within a small subset of CNS neurons. It plays a crucial role in controlling dopamine-mediated neurotransmission and a number of associated behaviors. This review focuses on recent data elucidating the role of the dopamine transporter in neurotoxicity and a number of CNS disorders, including Parkinson disease, drug abuse, and attention deficit hyperactivity disorder (ADHD)

  9. Putrescine uptake in saintpaulia petals.

    PubMed

    Bagni, N; Pistocchi, R

    1985-02-01

    Putrescine uptake and the kinetics of this uptake were studied in petals of Saintpaulia ionantha Wendl. Uptake experiments of [(3)H] or [(14)C] putrescine were done on single petals at room temperature at various pH values. The results show that putrescine uptake occurs against a concentration gradient at low external putrescine concentration (0.5-100 micromolar) and follows a concentration gradient at higher external putrescine concentrations (100 micromolar to 100 millimolar). 2,4-Dinitrophenol and carbonylcyanide-m-chlorophenylhydrazone, two uncouplers, had no effect on putrescine uptake. Uptake rates were constant for 2 hours, reaching a maximum after 3 to 4 hours. Putrescine uptake depended markedly on the external pH and two maxima were observed: at low external concentrations of putrescine, the optimum was at pH 5 to 5.5; at higher concentrations the optimum was at pH 8. PMID:16664065

  10. New copper(II) complexes with dopamine hydrochloride and vanillymandelic acid: Spectroscopic and thermal characterization

    NASA Astrophysics Data System (ADS)

    Mohamed, Gehad G.; Nour El-Dien, F. A.; El-Nahas, R. G.

    2011-10-01

    The dopamine derivatives participate in the regulation of wide variety of physiological functions in the human body and in medication life. Increase and/or decrease in the concentration of dopamine in human body reflect an indication for diseases such as Schizophrenia and/or Parkinson diseases. The Cu(II) chelates with coupled products of dopamine hydrochloride (DO.HCl) and vanillymandelic acid (VMA) with 4-aminoantipyrine (4-AAP) are prepared and characterized. Different physico-chemical techniques namely IR, magnetic and UV-vis spectra are used to investigate the structure of these chelates. Cu(II) forms 1:1 (Cu:DO) and 1:2 (Cu:VMA) chelates. DO behave as a uninegative tridentate ligand in binding to the Cu(II) ion while VMA behaves as a uninegative bidentate ligand. IR spectra show that the DO is coordinated to the Cu(II) ion in a tridentate manner with ONO donor sites of the phenolic- OH, -NH and carbonyl- O, while VMA is coordinated with OO donor sites of the phenolic- OH and -NH. Magnetic moment measurements reveal the presence of Cu(II) chelates in octahedral and square planar geometries with DO and VMA, respectively. The thermal decomposition of Cu(II) complexes is studied using thermogravimetric (TG) and differential thermal analysis (DTA) techniques. The activation thermodynamic parameters, such as, energy of activation, enthalpy, entropy and free energy change of the complexes are evaluated and the relative thermal stability of the complexes are discussed.

  11. Understanding the Role α7 Nicotinic Receptors Play in Dopamine Efflux in Nucleus Accumbens

    PubMed Central

    2015-01-01

    Neuronal nicotinic acetylcholine receptors (NNRs) of the α7 subtype have been shown to contribute to the release of dopamine in the nucleus accumbens. The site of action and the underlying mechanism, however, are unclear. Here we applied a circuit modeling approach, supported by electrochemical in vivo recordings, to clarify this issue. Modeling revealed two potential mechanisms for the drop in accumbal dopamine efflux evoked by the selective α7 partial agonist TC-7020. TC-7020 could desensitize α7 NNRs located predominantly on dopamine neurons or glutamatergic afferents to them or, alternatively, activate α7 NNRs located on the glutamatergic afferents to GABAergic interneurons in the ventral tegmental area. Only the model based on desensitization, however, was able to explain the neutralizing effect of coapplied PNU-120596, a positive allosteric modulator. According to our results, the most likely sites of action are the preterminal α7 NNRs controlling glutamate release from cortical afferents to the nucleus accumbens. These findings offer a rationale for the further investigation of α7 NNR agonists as therapy for diseases associated with enhanced mesolimbic dopaminergic tone, such as schizophrenia and addiction. PMID:25147933

  12. Dopamine release in rat striatum - Physiological coupling to tyrosine supply

    NASA Technical Reports Server (NTRS)

    During, Matthew J.; Acworth, Ian N.; Wurtman, Richard J.

    1989-01-01

    Intracerebral microdialysis was used to monitor dopamine release in rat striatal extracellular fluid following the intraperitoneal administration of dopamine's precursor amino acid, L-tyrosine. Dopamine concentrations in dialysates increased transiently after tyrosine (50-100 mg/kg) administration. Pretreatment with haloperidol or the partial lesioning of nigrostriatal neurons enhanced the effect of tyrosine on dopamine release, and haloperidol also prolonged this effect. These data suggest that nigrostriatal dopaminergic neurons are responsive to changes in precursor availability under basal conditions, but that receptor-mediated feedback mechanisms limit the magnitude and duration of this effect.

  13. Cloning of the cocaine-sensitive bovine dopamine transporter

    SciTech Connect

    Usdin, T.B.; Chen, C.; Brownstein, M.J.; Hoffman, B.J. ); Mezey, E. )

    1991-12-15

    A cDNA encoding the dopamine transporter from bovine brain substantia nigra was identified on the basis of its structural homology to other, recently cloned, neurotransmitter transporters. The sequence of the 693-amino acid protein is quite similar to those of the rat {gamma}-aminobutyric acid, human norepinephrine, and rat serotonin transporters. Dopamine transporter mRNA was detected by in situ hybridization in the substantia nigra but not in the locus coeruleus, raphe, caudate, or other brain areas. ({sup 3}H)Dopamine accumulation in tissue culture cells transfected with the cDNA was inhibited by amphetamine, cocaine, and specific inhibitors of dopamine transports, including GBR12909.

  14. Reinforcement signalling in Drosophila; dopamine does it all after all.

    PubMed

    Waddell, Scott

    2013-06-01

    Reinforcement systems are believed to drive synaptic plasticity within neural circuits that store memories. Recent evidence from the fruit fly suggests that anatomically distinct dopaminergic neurons ultimately provide the key instructive signals for both appetitive and aversive learning. This dual role for dopamine overturns the previous model that octopamine signalled reward and dopamine punishment. More importantly, this anatomically segregated double role for dopamine in reward and aversion mirrors that emerging in mammals. Therefore, an antagonistic organization of distinct reinforcing dopaminegic neurons is a conserved feature of brains. It now seems crucial to understand how the dopaminergic neurons are controlled and what the released dopamine does to the underlying circuits to convey opposite valence.

  15. Coupling nutrient uptake and energy flow in headwater streams

    SciTech Connect

    Mulholland, Patrick J; Fellows, Christine; Valett, H. Maurice; Dahm, Cliff; Thomas, Steve

    2006-08-01

    Nutrient cycling and energy flow in ecosystems are tightly linked through the metabolic processes of organisms. Greater uptake of inorganic nutrients is expected to be associated with higher rates of metabolism [gross primary production (GPP) and respiration (R)], due to assimilatory demand of both autotrophs and heterotrophs. However, relationships between uptake and metabolism should vary with the relative contribution of autochthonous and allochthonous sources of organic matter. To investigate the relationship between metabolism and nutrient uptake, we used whole-stream and benthic chamber methods to measure rates of nitrate-nitrogen (NO{sub 3}-N) uptake and metabolism in four headwater streams chosen to span a range of light availability and therefore differing rates of GPP and contributions of autochthonous carbon. We coupled whole-stream metabolism with measures of NO{sub 3}-N uptake conducted repeatedly over the same stream reach during both day and night, as well as incubating benthic sediments under both light and dark conditions. NO{sub 3}-N uptake was generally greater in daylight compared to dark conditions, and although day-night differences in whole-stream uptake were not significant, light-dark differences in benthic chambers were significant at three of the four sites. Estimates of N demand indicated that assimilation by photoautotrophs could account for the majority of NO{sub 3}-N uptake at the two sites with relatively open canopies. Contrary to expectations, photoautotrophs contributed substantially to NO{sub 3}-N uptake even at the two closed-canopy sites, which had low values of GPP/R and relied heavily on allochthonous carbon to fuel R.

  16. Effects of isomers of apomorphines on dopamine receptors in striatal and limbic tissue of rat brain

    SciTech Connect

    Kula, N.S.; Baldessarini, R.J.; Bromley, S.; Neumeyer, J.L.

    1985-09-16

    The optical isomers of apomorphine (APO) and N-propylnorapomorphine (NPA) were interacted with three biochemical indices of dopamine (Da) receptors in extrapyramidal and limbic preparations of rat brain tissues. There were consistent isomeric preferences for the R(-) configuration of both DA analogs in stimulation adenylate cyclase (D-1 sites) and in competing for high affinity binding of /sup 3/H-spiroperidol (D-2 sites) and of /sup 3/H-ADTN (DA agonist binding sites) in striatal tissue, with lesser isomeric differences in the limbic tissue. The S(+) apomorphines did not inhibit stimulation of adenylate cyclase by DA. The tendency for greater activity of higher apparent affinity of R(-) apomorphines in striatum may reflect the evidently greater abundance of receptor sites in that region. There were only small regional differences in interactions of the apomorphine isomers with all three receptor sites, except for a strong preference of (-)NPA for striatal D-2 sites. These results do not parallel our recent observations indicating potent and selective antidopaminergic actions of S(+) apomorphines in the rat limbic system. They suggest caution in assuming close parallels between current biochemical functional, especially behavioral, methods of evaluating dopamine receptors of mammalian brain.

  17. Linkage analysis of schizophrenia with five dopamine receptor genes in nine pedigrees

    SciTech Connect

    Coon, H.; Byerley, W.; Holik, J.; Hoff, M.; Myles-Worsley, M.; Plaetke, R. ); Lannfelt, L. ); Sokoloff, P.; Schwartz, J.C. ); Waldo, M.; Freedman, R. )

    1993-02-01

    Alterations in dopamine neurotransmission have been strongly implicated in the pathogenesis of schizophrenia for nearly 2 decades. Recently, the genes for five dopamine receptors have been cloned and characterized, and genetic and physical map information has become available. Using these five loci as candidate genes, the authors have tested for genetic linkage to schizophrenia in nine multigenerational families which include multiple affected individuals. In addition to testing conservative disease models, the have used a neurophysiological indicator variable, the P50 auditory evoked response. Deficits in gating of the P50 response have been shown to segregate with schizophrenia in this sample and may identify carriers of gene(s) predisposing for schizophrenia. Linkage results were consistently negative, indicating that a defect at any of the actual receptor sites is unlikely to be a major contributor to schizophrenia in the nine families studied. 47 refs., 1 fig., 4 tabs.

  18. A glutamatergic reward input from the dorsal raphe to ventral tegmental area dopamine neurons

    PubMed Central

    Qi, Jia; Zhang, Shiliang; Wang, Hui-Ling; Wang, Huikun; de Jesus Aceves Buendia, Jose; Hoffman, Alexander F.; Lupica, Carl R.; Seal, Rebecca P.; Morales, Marisela

    2014-01-01

    Electrical stimulation of the dorsal raphe (DR) and ventral tegmental area (VTA) activates the fibers of the same reward pathway but the phenotype of this pathway and the direction of the reward-relevant fibers have not been determined. Here we report rewarding effects following activation of a DR-originating pathway consisting of vesicular glutamate transporter 3 (VGluT3) containing neurons that form asymmetric synapses onto VTA dopamine neurons that project to nucleus accumbens. Optogenetic VTA activation of this projection elicits AMPA-mediated synaptic excitatory currents in VTA mesoaccumbens dopaminergic neurons and causes dopamine release innucleus accumbens. Activation also reinforces instrumental behavior and establishes conditioned place preferences. These findings indicate that the DR-VGluT3 pathway to VTA utilizes glutamate as a neurotransmitter and is a substrate linking the DR—one of the most sensitive reward sites in the brain—to VTA dopaminergic neurons. PMID:25388237

  19. Synthesis and binding profile of haloperidol-based bivalent ligands targeting dopamine D(2)-like receptors.

    PubMed

    Salama, Ismail; Löber, Stefan; Hübner, Harald; Gmeiner, Peter

    2014-08-15

    Homodimers of dopamine D2-like receptors are suggested to be of particular importance in the pathophysiology of schizophrenia and, thus, serve as promising targets for the discovery of atypical antipsychotics. This study describes the development of a series of novel bivalent molecules with a pharmacophore derived from the dopamine receptor antagonist haloperidol. These dimers were investigated in comparison to their monomeric analogues for their D2long, D2short, D3, and D4 receptor binding and the ability to bridge two neighboring receptor protomers. Radioligand binding studies provided diagnostic insights when Hill slopes close to two for the bivalent ligand 13 incorporating 22 spacer atoms and a comparative analysis with monovalent control ligands indicated a bivalent binding mode with a simultaneous occupancy of two neighboring binding sites. PMID:25047579

  20. A glutamatergic reward input from the dorsal raphe to ventral tegmental area dopamine neurons.

    PubMed

    Qi, Jia; Zhang, Shiliang; Wang, Hui-Ling; Wang, Huikun; de Jesus Aceves Buendia, Jose; Hoffman, Alexander F; Lupica, Carl R; Seal, Rebecca P; Morales, Marisela

    2014-11-12

    Electrical stimulation of the dorsal raphe (DR) and ventral tegmental area (VTA) activates the fibres of the same reward pathway but the phenotype of this pathway and the direction of the reward-relevant fibres have not been determined. Here we report rewarding effects following activation of a DR-originating pathway consisting of vesicular glutamate transporter 3 (VGluT3) containing neurons that form asymmetric synapses onto VTA dopamine neurons that project to nucleus accumbens. Optogenetic VTA activation of this projection elicits AMPA-mediated synaptic excitatory currents in VTA mesoaccumbens dopaminergic neurons and causes dopamine release in nucleus accumbens. Activation also reinforces instrumental behaviour and establishes conditioned place preferences. These findings indicate that the DR-VGluT3 pathway to VTA utilizes glutamate as a neurotransmitter and is a substrate linking the DR-one of the most sensitive reward sites in the brain--to VTA dopaminergic neurons.

  1. Endocytotic uptake of nutrients in carnivorous plants.

    PubMed

    Adlassnig, Wolfram; Koller-Peroutka, Marianne; Bauer, Sonja; Koshkin, Edith; Lendl, Thomas; Lichtscheidl, Irene K

    2012-07-01

    Carnivorous plants trap, digest and absorb animals in order to supplement their mineral nutrition. Nutrients absorbed by the plant include different nitrogen species, phosphate, potassium, trace elements and small organic compounds. Uptake is usually thought to be performed via specific channels, but this study provides evidence that endocytosis is involved as well. Traps of the carnivorous plants Nepenthes coccinea, Nepenthes ventrata, Cephalotus follicularis, Drosophyllum lusitanicum, Drosera capensis, Dionaea muscipula, Aldrovanda vesiculosa, Genlisea violacea × lobata, Sarracenia psittacina and Sarracenia purpurea were stained with methylene blue in order to identify possible sites of uptake. The permeable parts of the traps were incubated with fluorescein isothiocyanate labelled bovine serum albumin (FITC-BSA) and other fluorescent endocytosis markers, combined with the soluble protein BSA or respiratory inhibitors. Uptake was studied by confocal microscopy. In Nepenthes, small fluorescent vesicles became visible 1 h after incubation with FITC-BSA. These vesicles fused to larger compartments within 30 h. A similar behaviour was found in the related genera Drosera, Dionaea, Aldrovanda and Drosophyllum but also in Cephalotus with glands of different evolutionary origin. In Genlisea and Sarracenia, no evidence for endocytosis was found. We propose that in many carnivorous plants, nutrient uptake by carriers is supplemented by endocytosis, which enables absorption and intracellular digestion of whole proteins. The advantage for the plant of reducing secretion of enzymes for extracellular digestion is evident.

  2. Endocytotic uptake of nutrients in carnivorous plants.

    PubMed

    Adlassnig, Wolfram; Koller-Peroutka, Marianne; Bauer, Sonja; Koshkin, Edith; Lendl, Thomas; Lichtscheidl, Irene K

    2012-07-01

    Carnivorous plants trap, digest and absorb animals in order to supplement their mineral nutrition. Nutrients absorbed by the plant include different nitrogen species, phosphate, potassium, trace elements and small organic compounds. Uptake is usually thought to be performed via specific channels, but this study provides evidence that endocytosis is involved as well. Traps of the carnivorous plants Nepenthes coccinea, Nepenthes ventrata, Cephalotus follicularis, Drosophyllum lusitanicum, Drosera capensis, Dionaea muscipula, Aldrovanda vesiculosa, Genlisea violacea × lobata, Sarracenia psittacina and Sarracenia purpurea were stained with methylene blue in order to identify possible sites of uptake. The permeable parts of the traps were incubated with fluorescein isothiocyanate labelled bovine serum albumin (FITC-BSA) and other fluorescent endocytosis markers, combined with the soluble protein BSA or respiratory inhibitors. Uptake was studied by confocal microscopy. In Nepenthes, small fluorescent vesicles became visible 1 h after incubation with FITC-BSA. These vesicles fused to larger compartments within 30 h. A similar behaviour was found in the related genera Drosera, Dionaea, Aldrovanda and Drosophyllum but also in Cephalotus with glands of different evolutionary origin. In Genlisea and Sarracenia, no evidence for endocytosis was found. We propose that in many carnivorous plants, nutrient uptake by carriers is supplemented by endocytosis, which enables absorption and intracellular digestion of whole proteins. The advantage for the plant of reducing secretion of enzymes for extracellular digestion is evident. PMID:22417315

  3. Absence of NMDA receptors in dopamine neurons attenuates dopamine release but not conditioned approach during Pavlovian conditioning.

    PubMed

    Parker, Jones G; Zweifel, Larry S; Clark, Jeremy J; Evans, Scott B; Phillips, Paul E M; Palmiter, Richard D

    2010-07-27

    During Pavlovian conditioning, phasic dopamine (DA) responses emerge to reward-predictive stimuli as the subject learns to anticipate reward delivery. This observation has led to the hypothesis that phasic dopamine signaling is important for learning. To assess the ability of mice to develop anticipatory behavior and to characterize the contribution of dopamine, we used a food-reinforced Pavlovian conditioning paradigm. As mice learned the cue-reward association, they increased their head entries to the food receptacle in a pattern that was consistent with conditioned anticipatory behavior. D1-receptor knockout (D1R-KO) mice had impaired acquisition, and systemic administration of a D1R antagonist blocked both the acquisition and expression of conditioned approach in wild-type mice. To assess the specific contribution of phasic dopamine transmission, we tested mice lacking NMDA-type glutamate receptors (NMDARs) exclusively in dopamine neurons (NR1-KO mice). Surprisingly, NR1-KO mice learned at the same rate as their littermate controls. To evaluate the contribution of NMDARs to phasic dopamine release in this paradigm, we performed fast-scan cyclic voltammetry in the nucleus accumbens of awake mice. Despite having significantly attenuated phasic dopamine release following reward delivery, KO mice developed cue-evoked dopamine release at the same rate as controls. We conclude that NMDARs in dopamine neurons enhance but are not critical for phasic dopamine release to behaviorally relevant stimuli; furthermore, their contribution to phasic dopamine signaling is not necessary for the development of cue-evoked dopamine or anticipatory activity in a D1R-dependent Pavlovian conditioning paradigm.

  4. Effect of environmental enrichment on dopamine and serotonin transporters and glutamate neurotransmission in medial prefrontal and orbitofrontal cortex.

    PubMed

    Darna, Mahesh; Beckmann, Joshua S; Gipson, Cassandra D; Bardo, Michael T; Dwoskin, Linda P

    2015-03-01

    Recent studies have reported that rats raised in an enriched condition (EC) have decreased dopamine transporter (DAT) function and expression in medial prefrontal cortex (mPFC), as well as increased d-amphetamine-induced glutamate release in nucleus accumbens compared to rats raised in an isolated condition (IC). In these previous studies, DAT function and expression were evaluated using mPFC pooled from four rats for each condition to obtain kinetic parameters due to sparse DAT expression in mPFC. In contrast, accumbal glutamate release was determined using individual rats. The current study extends the previous work and reports on the optimization of DAT and serotonin transporter (SERT) functional assays, as well as cell surface expression assays using both mPFC and orbitofrontal cortex (OFC) from individual EC or IC rats. In addition, the effect of d-amphetamine on glutamate release in mPFC and OFC of EC and IC rats was determined using in vivo microdialysis. Results show that environmental enrichment decreased maximal transport velocity (Vmax) for [(3)H]dopamine uptake in mPFC, but increased Vmax for [(3)H]dopamine uptake in OFC. Corresponding changes in DAT cell surface expression were not found. In contrast, Vmax for [(3)H]serotonin uptake and cellular localization of SERT in mPFC and OFC were not different between EC and IC rats. Further, acute d-amphetamine (2mg/kg, s.c.) increased extracellular glutamate concentrations in mPFC of EC rats only and in OFC of IC rats only. Overall, these results suggest that enrichment produces long-lasting alterations in mPFC and OFC DAT function via a trafficking-independent mechanism, as well as differential glutamate release in mPFC and OFC. Rearing-induced modulation of DAT function and glutamate release in prefrontal cortical subregions may contribute to the known protective effects of enrichment on drug abuse vulnerability.

  5. Phospholipase A2 and 3H-hemicholinium-3 binding sites in rat brain: A potential second-messenger role for fatty acids in the regulation of high-affinity choline uptake

    SciTech Connect

    Saltarelli, M.D.; Yamada, K.; Coyle, J.T. )

    1990-01-01

    The involvement of phospholipase A2 (PLA2) and fatty acid release in the regulation of sodium-dependent high-affinity choline uptake in rat brain was assessed in vitro through the use of the specific binding of 3H-hemicholinium-3 (3H-HCh-3). Addition of arachidonic acid and other unsaturated fatty acids to rat striatal membranes in vitro resulted in a dose-dependent, temperature-independent activation of 3H-HCh-3 binding. Scatchard analysis revealed that these changes in binding result from a 2-fold increase in the affinity and capacity of 3H-HCh-3 binding. Saturated fatty acids, lysophospholipids, and phospholipids did not affect specific 3H-HCh-3 binding. Addition of defatted BSA to membranes, which had been treated previously with arachidonic acid, completely reversed the increase in specific 3H-HCh-3 binding. However, several inhibitors of fatty acid metabolism, including nordihydroguaiaretic acid, indomethacin, catalase, and superoxide dismutase, did not alter arachidonic acid-induced changes in 3H-HCh-3 binding, suggesting that unsaturated fatty acids, and not their metabolites, are directly responsible for the observed activation of specific 3H-HCh-3 binding. Additionally, unsaturated fatty acids dose-dependently inhibited high-affinity 3H-choline uptake in rat striatal synaptosomes, apparently due to the disruption of synaptosomal integrity. The phospholipase A2 inhibitors quinacrine hydrochloride, trifluoperazine, and 4-bromophenacylbromide dose-dependently inhibited potassium depolarization-induced activation of specific 3H-HCh-3 binding in slices of rat brain in vitro. Similarly, both quinacrine and trifluoperazine inhibited the metabolism of phospholipids and the release of fatty acids evoked by either elevated KCl or calcium ionophore A23187.

  6. 3- and 4-O-sulfoconjugated and methylated dopamine: highly reduced binding affinity to dopamine D2 receptors in rat striatal membranes.

    PubMed

    Werle, E; Lenz, T; Strobel, G; Weicker, H

    1988-07-01

    The binding properties of 3- and 4-O-sulfo-conjugated dopamine (DA-3-O-S, DA-4-O-S) as well as 3-O-methylated dopamine (MT) to rat striatal dopamine D2 receptors were investigated. 3H-spiperone was used as a radioligand in the binding studies. In saturation binding experiments (+)butaclamol, which has been reported to bind to dopaminergic D2 and serotoninergic 5HT2 receptors, was used in conjunction with ketanserin and sulpiride, which preferentially label 5HT2 and D2 receptors, respectively, in order to discriminate between 3H-spiperone binding to D2 and to 5HT2 receptors. Under our particular membrane preparation and assay conditions, 3H-spiperone binds to D2 and 5HT2 receptors with a maximal binding capacity (Bmax) of 340 fmol/mg protein in proportions of about 75%:25% with similar dissociation constants KD (35 pmol/l; 43 pmol/l). This result was verified by the biphasic competition curve of ketanserin, which revealed about 20% high (KD = 24 nmol/l) and 80% low (KD = 420 nmol/l) affinity binding sites corresponding to 5HT2 and D2 receptors, respectively. Therefore, all further competition experiments at a tracer concentration of 50 pmol/l were performed in the presence of 0.1 mumol/l ketanserin to mask the 5HT2 receptors. DA competition curves were best fitted assuming two binding sites, with high (KH = 0.12 mumol/l) and low (KL = 18 mumol/l) affinity, present in a ratio of 3:1. The high affinity binding sites were interconvertible by 100 mumol/l guanyl-5-yl imidodiphosphate [Gpp(NH)p], resulting in a homogenous affinity state of DA receptors (KD = 2.8 mumol/l).2+ off PMID:2853303

  7. 3- and 4-O-sulfoconjugated and methylated dopamine: highly reduced binding affinity to dopamine D2 receptors in rat striatal membranes.

    PubMed

    Werle, E; Lenz, T; Strobel, G; Weicker, H

    1988-07-01

    The binding properties of 3- and 4-O-sulfo-conjugated dopamine (DA-3-O-S, DA-4-O-S) as well as 3-O-methylated dopamine (MT) to rat striatal dopamine D2 receptors were investigated. 3H-spiperone was used as a radioligand in the binding studies. In saturation binding experiments (+)butaclamol, which has been reported to bind to dopaminergic D2 and serotoninergic 5HT2 receptors, was used in conjunction with ketanserin and sulpiride, which preferentially label 5HT2 and D2 receptors, respectively, in order to discriminate between 3H-spiperone binding to D2 and to 5HT2 receptors. Under our particular membrane preparation and assay conditions, 3H-spiperone binds to D2 and 5HT2 receptors with a maximal binding capacity (Bmax) of 340 fmol/mg protein in proportions of about 75%:25% with similar dissociation constants KD (35 pmol/l; 43 pmol/l). This result was verified by the biphasic competition curve of ketanserin, which revealed about 20% high (KD = 24 nmol/l) and 80% low (KD = 420 nmol/l) affinity binding sites corresponding to 5HT2 and D2 receptors, respectively. Therefore, all further competition experiments at a tracer concentration of 50 pmol/l were performed in the presence of 0.1 mumol/l ketanserin to mask the 5HT2 receptors. DA competition curves were best fitted assuming two binding sites, with high (KH = 0.12 mumol/l) and low (KL = 18 mumol/l) affinity, present in a ratio of 3:1. The high affinity binding sites were interconvertible by 100 mumol/l guanyl-5-yl imidodiphosphate [Gpp(NH)p], resulting in a homogenous affinity state of DA receptors (KD = 2.8 mumol/l).2+ off

  8. Changes in dopamine transporter binding in nucleus accumbens following chronic self-administration of cocaine:heroin combinations

    PubMed Central

    Pattison, Lindsey P.; McIntosh, Scot; Sexton, Tammy; Childers, Steven R.; Hemby, Scott E.

    2014-01-01

    Concurrent use of cocaine and heroin (speedball) has been shown to exert synergistic effects on dopamine neurotransmission in the nucleus accumbens (NAc), as observed by significant increases in extracellular dopamine levels and compensatory elevations in the maximal reuptake rate (Vmax) of dopamine. The present studies were undertaken to determine whether chronic self-administration of cocaine, heroin or a combination of cocaine:heroin led to compensatory changes in the abundance and/or affinity of high- and low-affinity DAT binding sites. Saturation binding of the cocaine analog [125I] 3β-(4-iodophenyl)tropan-2β-carboxylic acid methyl ester ([125I]RTI-55) in rat NAc membranes resulted in binding curves that were best fit to two-site binding models, allowing calculation of dissociation constant (Kd) and binding density (Bmax) values corresponding to high- and low-affinity DAT binding sites. Scatchard analysis of the saturation binding curves clearly demonstrate the presence of high- and low- affinity binding sites in the NAc, with low-affinity sites comprising 85 to 94% of the binding sites. DAT binding analyses revealed that self-administration of cocaine and a cocaine:heroin combination increased the affinity of the low-affinity site for the cocaine congener RTI-55 compared to saline. These results indicate that the alterations observed following chronic speedball self-administration are likely due to the cocaine component alone; thus further studies are necessary to elaborate upon the synergistic effect of cocaine:heroin combinations on the dopamine system in the NAc. PMID:24916769

  9. Responses of in vivo renal microvessels to dopamine.

    PubMed

    Steinhausen, M; Weis, S; Fleming, J; Dussel, R; Parekh, N

    1986-09-01

    The split hydronephrotic kidney preparation was used to directly observe the effects of locally applied dopamine on the in vivo diameters of renal vessels. Dopamine (1 X 10(-6) to 3 X 10(-5) M) produced a concentration-dependent dilation of the arcuate and interlobular arteries and afferent arterioles. Efferent arterioles near the glomeruli also dilated to dopamine but the dilation was less than that of the preglomerular vessels. Higher dopamine concentrations (3 X 10(-4) and 1 X 10(-3) M) produced more variable effects, with a tendency for the arcuate and interlobular arteries and the afferent and efferent arterioles away from the glomeruli to decrease in diameter. After pretreatment with haloperidol, dopamine (1 X 10(-6) to 1 X 10(-4) M) did not dilate any pre- or postglomerular vascular segment, but the tendency for pre- and postglomerular constrictions with higher dopamine concentrations were not abolished. Pretreatment with phentolamine and propranolol enhanced the dilator response of the pre- and postglomerular vessels (except the afferent arterioles near glomeruli and efferent arterioles near welling points) to dopamine (3 X 10(-5) and 1 X 10(-4) M), and abolished the reductions in diameter produced by the high dopamine levels. These data indicate that the dilator effect of dopamine is mediated by interactions with specific dopaminergic receptors, while alpha and beta adrenergic receptors appear to mediate a constrictor influence observed with high dopamine concentrations. The overall effect of dopamine on the renal vessel diameters thus appears to depend on the balance of dilator and constrictor stimuli mediated by multiple receptors.

  10. Studies of the biogenic amine transporters. VI. Characterization of a novel cocaine binding site, identified with [125I]RTI-55, in membranes prepared from whole rat brain minus caudate.

    PubMed

    Rothman, R B; Silverthorn, M L; Baumann, M H; Goodman, C B; Cadet, J L; Matecka, D; Rice, K C; Carroll, F I; Wang, J B; Uhl, G R

    1995-07-01

    Previous studies showed that the cocaine analog [125I]RTI-55 labels dopamine and serotonergic (5-HT) biogenic amine transporters (BATs) with high affinity. Here we characterized [125I]RTI-55 binding to membranes prepared from whole rat brain minus the caudate nuclei. Paroxetine (50 nM) was used to block [125I]RTI-55 binding to 5-HT transporter sites. Initial experiments identified drugs that displaced [125I]RTI-55 binding with moderately low slope factors. Binding surface analysis of the interaction of 3 beta-(4-chlorophenyl)tropan-2 beta-carboxylic acid phenyl ester hydrochloride (RTI-113) and 3 beta-(4-iodophenyl)tropan-2 beta-carboxylic acid phenyl ester hydrochloride (RTI-122) with [125I]RTI-55 binding sites readily resolved two binding sites for [125I]RTI-55 with Kd values of 0.44 nM and 17 nM and Bmax values of 31 and 245 fmol/mg protein. Potent 5-HT and noradrenergic uptake inhibitors had low affinity for both sites. Whereas cocaine, CFT and WIN35,065-2 were 6.0-, 25- and 14-fold selective for the first site, benztropine, PCP and the novel pyrrole, (+-)-(2RS,3aSR,8bRS)-1,2,3,3a,4,8b-hexahydro- 2-benzyl-1-methylindeno-[1,2-b]pyrrole resorcylate [(+-)-HBMP, formerly called (+-)-RTI-4793-14], were moderately selective for the second site. A single binding site with the characteristics of site 1 was resolved using COS cells transiently expressing the cloned rat dopamine transporter. Lesion studies with 6-hydroxydopamine and 5,7-dihydroxytryptamine were conducted to test the hypothesis that site 1 and site 2 are physically distinct. The data showed that these neurotoxins differentially decreased [125I]RTI-55 binding to sites 1 and 2. The differential distribution of sites 1 and 2 in rat brain provides further support for this hypothesis. Viewed collectively, these data show that [125I]RTI-55 labels a novel binding site in rat brain membranes, termed DATsite2, which is not associated with the classic dopamine, serotonin or norepinephrine transporters.

  11. Presence of dopamine D-2 receptors in human tumoral cell lines

    SciTech Connect

    Sokoloff, P.; Riou, J.F.; Martres, M.P.; Schwartz, J.C. )

    1989-07-31

    ({sup 125}I) Iodosulpride binding was examined on eight human cell lines derived from lung, breast and digestive tract carcinomas, neuroblastomas and leukemia. Specific binding was detected in five of these cell lines. In the richest cell line N417, derived from small cell lung carcinoma, ({sup 125}I) iodosulpride bound with a high affinity (Kd = 1.3 nM) to an apparently homogeneous population of binding site (Bmax = 1,606 sites per cell). These sites displayed a typical D-2 specificity, established with several dopaminergic agonists and antagonists selective of either D-1 or D-2 receptor subtypes. In addition, dopamine, apomorphine and RU 24926 distinguished high- and low-affinity sites, suggesting that the binding sites are associated with a G-protein. The biological significance and the possible diagnostic implication of the presence of D-2 receptors on these cell lines are discussed.

  12. Serotonin-S2 and dopamine-D2 receptors are the same size in membranes

    SciTech Connect

    Brann, M.R.

    1985-12-31

    Target size analysis was used to compare the sizes of serotonin-S2 and dopamine-D2 receptors in rat brain membranes. The sizes of these receptors were standardized by comparison with the muscarinic receptor, a receptor of known size. The number of serotonin-S2 receptors labeled with (3H)ketanserin or (3H)spiperone in frontal cortex decreased as an exponential function of radiation dose, and receptor affinity was not affected. The number of dopamine-D2 receptors labeled with (3H)spiperone in striatum also decreased as an exponential function of radiation dose, and D2 and S2 receptors were equally sensitive to radiation. In both striatum and frontal cortex, the number of muscarinic receptors labeled with (3H)QNB decreased as an exponential function of radiation dose, and were much less sensitive to radiation than S2 and D2 receptors. These data indicate that in rat brain membranes, S2 and D2 receptors are of similar size, and both molecules are much larger than the muscarinic receptor.

  13. CHRONIC INTERMITTENT ETHANOL EXPOSURE REDUCES PRESYNAPTIC DOPAMINE NEUROTRANSMISSION IN THE MOUSE NUCLEUS ACCUMBENS

    PubMed Central

    Karkhanis, Anushree N.; Rose, Jamie H.; Huggins, Kimberly N.; Konstantopoulos, Joanne K.; Jones, Sara R.

    2015-01-01

    BACKGROUND Increasing evidence suggests that chronic ethanol exposure decreases dopamine (DA) neurotransmission in the nucleus accumbens (NAc), contributing to a hypodopaminergic state during withdrawal. However, few studies have investigated adaptations in presynaptic DA terminals after chronic intermittent ethanol (CIE) exposure. In monkeys and rats, chronic ethanol exposure paradigms have been shown to increase DA uptake and D2 autoreceptor sensitivity. METHODS The current study examined the effects of ethanol on DA terminals in CIE exposed mice during two time-points after the cessation of CIE exposure. DA release and uptake were measured using fast scan cyclic voltammetry in NAc core slices from C57BL/6J mice, 0 and 72 hours following three weekly cycles (4 days of 16 hrs ethanol vapor/8 hrs room air/day + 3 days withdrawal) of CIE vapor exposure. RESULTS Current results showed that DA release was reduced, uptake rates were increased, and inhibitory D2-type autoreceptor activity was augmented following CIE exposure in mice. CONCLUSIONS Overall, these CIE-induced adaptations in the accumbal DA system reduce DA signaling and therefore reveal several potential mechanisms contributing to a functional hypodopaminergic state during alcohol withdrawal. PMID:25765483

  14. Opening the black box: dopamine, predictions, and learning

    PubMed Central

    Eshel, Neir; Tian, Ju; Uchida, Naoshige

    2013-01-01

    Dopamine neurons are thought to promote learning by signaling prediction errors, that is, the difference between actual and expected outcomes. Whether these signals are sufficient for associative learning, however, remains untested. A recent study used optogenetics in a classic behavioral paradigm to confirm the role of dopamine prediction errors in learning. PMID:23830895

  15. Time, Not Size, Matters for Striatal Reward Predictions to Dopamine.

    PubMed

    Burke, Christopher J; Tobler, Philippe N

    2016-07-01

    Midbrain dopamine neurons encode reward prediction errors. In this issue of Neuron, Takahashi et al. (2016) show that the ventral striatum provides dopamine neurons with prediction information specific to the timing, but not the quantity, of reward, suggesting a surprisingly nuanced neural implementation of reward prediction errors. PMID:27387646

  16. Decreased brain dopamine cell numbers in human cocaine users.

    PubMed

    Little, Karley Y; Ramssen, Eric; Welchko, Ryan; Volberg, Vitaly; Roland, Courtney J; Cassin, Bader

    2009-08-15

    Cocaine use diminishes striatal and midbrain dopamine neuronal components in both post-mortem and in vivo human experiments. The diffuse nature of these declines suggests the possibility that cocaine use might cause a loss of dopamine neurons in humans. Previous rodent studies have not detected cocaine-induced dopamine cell damage. The present experiment involved counting midbrain dopamine neurons utilizing both melanin and tyrosine hydroxylase immunoreactivity. Well-preserved blocks ranging from +38 mm obex to +45 mm obex were examined in 10 cocaine users and 9 controls. Sections were also examined for signs of acute pathological injury by counting activated macrophages and microglia. Melanized cells at six midbrain levels were significantly reduced in cocaine users by both drug exposures. The estimated total number of melanized dopamine cells in the anterior midbrain was significantly reduced in cocaine users by 16%. Results with tyrosine hydroxylase immunoreactivity were less conclusive because of variability in staining. Both activated macrophages and activated microglia were significantly increased among cocaine users. Cocaine exposure may have neurotoxic effects on dopamine neurons in humans. The infiltration of phagocytic cells suggests that the lower number of dopamine cells found in cocaine users was a relatively recent effect. The loss of dopamine cells could contribute to and intensify cocaine dependence, as well as anhedonic and depressive symptoms, in some cocaine users. Further efforts at clarifying the pathophysiological mechanisms involved may help explain treatment refractoriness, and identify targets for therapeutic intervention. PMID:19233481

  17. Imaging dopamine receptors in the human brain by position tomography

    SciTech Connect

    Wagner, H.N. Jr.; Burns, H.D.; Dannals, R.F.; Wong, D.F.; Langstrom, B.; Duelfer, T.; Frost, J.J.; Ravert, H.T.; Links, J.M.; Rosenbloom, S.B.

    1983-01-01

    Neurotransmitter receptors may be involved in a number of neuropsychiatric disease states. The ligand 3-N-(/sup 11/C)methylspiperone, which preferentially binds to dopamine receptors in vivo, was used to image the receptors by positron emission tomography scanning in baboons and in humans. This technique holds promise for noninvasive clinical studies of dopamine receptors in humans.

  18. Dopamine receptor genes: new tools for molecular psychiatry.

    PubMed Central

    Niznik, H B; Van Tol, H H

    1992-01-01

    For over a decade it has been generally assumed that all the pharmacological and biochemical actions of dopamine within the central nervous system and periphery were mediated by two distinct dopamine receptors. These receptors, termed D1 and D2, were defined as those coupled to the stimulation or inhibition of adenylate cyclase, respectively, and by their selectivity and avidity for various drugs and compounds. The concept that two dopamine receptors were sufficient to account for all the effects mediated by dopamine was an oversimplification. Recent molecular biological studies have identified five distinct genes which encode at least eight functional dopamine receptors. The members of the expanded dopamine receptor family, however, can still be codifed by way of the original D1 and D2 receptor dichotomy. These include two genes encoding dopamine D1-like receptors (D1 [D1A]/D5 [D1B]) and three genes encoding D2-like receptors (D2/D3/D4). We review here our recent work on the cloning and characterization of some of the members of the dopamine receptor gene family (D1, D2, D4, D5), their relationship to neuropsychiatric disorders and their potential role in antipsychotic drug action. Images Fig. 1 PMID:1450188

  19. Opening the black box: dopamine, predictions, and learning.

    PubMed

    Eshel, Neir; Tian, Ju; Uchida, Naoshige

    2013-09-01

    Dopamine neurons are thought to promote learning by signaling prediction errors, that is, the difference between actual and expected outcomes. Whether these signals are sufficient for associative learning, however, remains untested. A recent study used optogenetics in a classic behavioral paradigm to confirm the role of dopamine prediction errors in learning.

  20. Mesolimbic dopamine and its neuromodulators in obesity and binge eating.

    PubMed

    Naef, Lindsay; Pitman, Kimberley A; Borgland, Stephanie L

    2015-12-01

    Obesity has reached epidemic prevalence, and much research has focused on homeostatic and nonhomeostatic mechanisms underlying overconsumption of food. Mesocorticolimbic circuitry, including dopamine neurons of the ventral tegmental area (VTA), is a key substrate for nonhomeostatic feeding. The goal of the present review is to compare changes in mesolimbic dopamine function in human obesity with diet-induced obesity in rodents. Additionally, we will review the literature to determine if dopamine signaling is altered with binge eating disorder in humans or binge eating modeled in rodents. Finally, we assess modulation of dopamine neurons by neuropeptides and peripheral peptidergic signals that occur with obesity or binge eating. We find that while decreased dopamine concentration is observed with obesity, there is inconsistency outside the human literature on the relationship between striatal D2 receptor expression and obesity. Finally, few studies have explored how orexigenic or anorexigenic peptides modulate dopamine neuronal activity or striatal dopamine in obese models. However, ghrelin modulation of dopamine neurons may be an important factor for driving binge feeding in rodents.

  1. Dopamine modulates egalitarian behavior in humans.

    PubMed

    Sáez, Ignacio; Zhu, Lusha; Set, Eric; Kayser, Andrew; Hsu, Ming

    2015-03-30

    Egalitarian motives form a powerful force in promoting prosocial behavior and enabling large-scale cooperation in the human species [1]. At the neural level, there is substantial, albeit correlational, evidence suggesting a link between dopamine and such behavior [2, 3]. However, important questions remain about the specific role of dopamine in setting or modulating behavioral sensitivity to prosocial concerns. Here, using a combination of pharmacological tools and economic games, we provide critical evidence for a causal involvement of dopamine in human egalitarian tendencies. Specifically, using the brain penetrant catechol-O-methyl transferase (COMT) inhibitor tolcapone [4, 5], we investigated the causal relationship between dopaminergic mechanisms and two prosocial concerns at the core of a number of widely used economic games: (1) the extent to which individuals directly value the material payoffs of others, i.e., generosity, and (2) the extent to which they are averse to differences between their own payoffs and those of others, i.e., inequity. We found that dopaminergic augmentation via COMT inhibition increased egalitarian tendencies in participants who played an extended version of the dictator game [6]. Strikingly, computational modeling of choice behavior [7] revealed that tolcapone exerted selective effects on inequity aversion, and not on other computational components such as the extent to which individuals directly value the material payoffs of others. Together, these data shed light on the causal relationship between neurochemical systems and human prosocial behavior and have potential implications for our understanding of the complex array of social impairments accompanying neuropsychiatric disorders involving dopaminergic dysregulation. PMID:25802148

  2. Characterization of the striatal dopaminergic neurotransmission in MEN2B mice with elevated cerebral tissue dopamine.

    PubMed

    Mijatovic, Jelena; Patrikainen, Outi; Yavich, Leonid; Airavaara, Mikko; Ahtee, Liisa; Saarma, Mart; Piepponen, T Petteri

    2008-06-01

    The Ret receptor tyrosine kinase is the common signaling receptor for the glial cell line-derived neurotrophic factor (GDNF) family ligands. The Met918Thr mutation leads to constitutive activation of Ret and is responsible for dominantly inherited cancer syndrome MEN2B. Previously, we found that the mice carrying the mutation (MEN2B mice) have profoundly increased tissue dopamine (DA) concentrations in the striatum as well as increased striatal levels of tyrosine hydroxylase (TH) and dopamine transporter. The aim of this study was to characterize the striatal dopaminergic neurotransmission in MEN2B mice and to clarify the mechanisms by which they compensate their over-production of DA. We found that tyrosine hydroxylase activity and DA synthesis are increased in MEN2B mice. Augmented effects of alpha-methyl-para-tyrosine (alphaMT, an inhibitor of TH) and tetrabenazine (VMAT2 blocker) on DA levels suggest that also storage of DA is increased in MEN2B mice. There was no difference in the basal extracellular DA concentrations or potassium-evoked DA release between the genotypes. The effects of cocaine and haloperidol were also similar between the genotypes as assessed by in vivo microdialysis. However, with in vivo voltammetry we found increase in stimulated DA release in MEN2B mice and detailed analysis of DA overflow showed that uptake of DA was also enhanced in MEN2B mice. Thus, our data show that enhanced synthesis of DA leading to increased storage and releasable pools in pre-synaptic terminals in MEN2B mice apparently also leads to increased DA release, which in turn is compensated by higher dopamine transporter activity. PMID:18248620

  3. (18)F-FECNT: validation as PET dopamine transporter ligand in parkinsonism.

    PubMed

    Masilamoni, Gunasingh; Votaw, John; Howell, Leonard; Villalba, Rosa M; Goodman, Mark; Voll, Ronald J; Stehouwer, Jeffrey; Wichmann, Thomas; Smith, Yoland

    2010-12-01

    The positron emission tomography (PET) tracer 2β-carbomethoxy-3β-(4-chlorophenyl)-8-(2-[18F]-fluoroethyl)-nortropane ((18)F-FECNT) is a highly specific ligand for dopamine transporter (DAT) that yields higher peak striatum-to-cerebellum ratios and offers more favorable kinetics than most (18)F-radiolabeled DAT ligands currently available. The goal of this study is to validate the use of (18)F-FECNT as a PET radiotracer to assess the degree of striatal dopamine terminals denervation and midbrain dopaminergic cell loss in MPTP-treated parkinsonian monkeys. Three rhesus monkeys received weekly injections of MPTP (0.2-0.5 mg/kg) for 21 weeks, which resulted in the progressive development of a moderate level of parkinsonism. We carried out (18)F-FECNT PET at baseline (twice; 10 weeks apart) and at week 21 post-MPTP injections. Postmortem stereological cell counts of dopaminergic neurons in the ventral midbrain, and intensity measurements of DAT and tyrosine hydroxylase (TH) immunoreactivity in the striatum were performed and correlated with striatal and ventral midbrain PET data. Three additional monkeys were used as controls for midbrain dopaminergic cell counts, and striatal DAT or TH immunoreactivity measurements. The correlation and coefficient of variance between (18)F-FECNT test-retest specific uptake ratios were 0.99 (R²) and 2.65%, respectively. The (18)F-FECNT binding potential of the ventral midbrain and striatal regions was tightly correlated with postmortem stereological cell counts of nigral dopaminergic neurons (R²=0.91), and striatal DAT (R²=0.83) or TH (R²=0.88) immunoreactivity intensity measurements. These findings demonstrate that (18)F-FECNT is a highly sensitive PET imaging ligand to quantify both striatal dopamine denervation and midbrain dopaminergic cell loss associated with parkinsonism.

  4. Conformational changes in dopamine transporter intracellular regions upon cocaine binding and dopamine translocation

    PubMed Central

    Dehnes, Yvette; Shan, Jufang; Beuming, Thijs; Shi, Lei; Weinstein, Harel; Javitch, Jonathan A.

    2014-01-01

    The dopamine transporter (DAT), a member of the neurotransmitter:sodium symporter family, mediates the reuptake of dopamine at the synaptic cleft. DAT is the primary target for psychostimulants such as cocaine and amphetamine. We previously demonstrated that cocaine binding and dopamine transport alter the accessibility of Cys342 in the third intracellular loop (IL3). To study the conformational changes associated with the functional mechanism of the transporter, we made cysteine substitution mutants, one at a time, from Phe332 to Ser351 in IL3 of the background DAT construct, X7C, in which 7 endogenous cysteines were mutated. The accessibility of the 20 engineered cysteines to polar charged sulfhydryl reagents was studied in the absence and presence of cocaine or dopamine. Of the 11 positions that reacted with methanethiosulfonate ethyl ammonium, as evidenced by inhibition of ligand binding, 5 were protected against this inhibition by cocaine and dopamine (S333C, S334C, N336C, M342C and T349C), indicating that reagent accessibility is affected by conformational changes associated with inhibitor and substrate binding. In some of the cysteine mutants, transport activity is disrupted, but can be rescued by the presence of zinc, most likely because the distribution between inward- and outward-facing conformations is restored by zinc binding. The experimental data were interpreted in the context of molecular models of DAT in both the inward- and outward-facing conformations. Differences in the solvent accessible surface area for individual IL3 residues calculated for these states correlate well with the experimental accessibility data, and suggest that protection by ligand binding results from the stabilization of the outward-facing configuration. Changes in the residue interaction networks observed from the molecular dynamics simulations also revealed the critical roles of several positions during the conformational transitions. We conclude that the IL3 region of DAT

  5. Recombinant glucose uptake system

    DOEpatents

    Ingrahm, Lonnie O.; Snoep, Jacob L.; Arfman, Nico

    1997-01-01

    Recombinant organisms are disclosed that contain a pathway for glucose uptake other than the pathway normally utilized by the host cell. In particular, the host cell is one in which glucose transport into the cell normally is coupled to PEP production. This host cell is transformed so that it uses an alternative pathway for glucose transport that is not coupled to PEP production. In a preferred embodiment, the host cell is a bacterium other than Z. mobilis that has been transformed to contain the glf and glk genes of Z. mobilis. By uncoupling glucose transport into the cell from PEP utilization, more PEP is produced for synthesis of products of commercial importance from a given quantity of biomass supplied to the host cells.

  6. Dopamine and epistemic curiosity in music listening.

    PubMed

    Omigie, Diana

    2015-01-01

    Elucidating the cognitive, affective, and reward processes that take place during music listening is the aim of a growing number of researchers. Several authors have used the Bayesian brain framework and existing models of reward to interpret neural activity observed during musical listening. The claims from Friston and colleagues regarding the role of dopamine, as well as the demonstration that salience-seeking behavior naturally emerges from minimizing free energy, will be of potential interest to those seeking to understand the general principles underlying our motivation to hear music. PMID:26073880

  7. A descending dopamine pathway conserved from basal vertebrates to mammals

    PubMed Central

    Ryczko, Dimitri; Cone, Jackson J.; Alpert, Michael H.; Goetz, Laurent; Auclair, François; Dubé, Catherine; Parent, Martin; Roitman, Mitchell F.; Alford, Simon; Dubuc, Réjean

    2016-01-01

    Dopamine neurons are classically known to modulate locomotion indirectly through ascending projections to the basal ganglia that project down to brainstem locomotor networks. Their loss in Parkinson’s disease is devastating. In lampreys, we recently showed that brainstem networks also receive direct descending dopaminergic inputs that potentiate locomotor output. Here, we provide evidence that this descending dopaminergic pathway is conserved to higher vertebrates, including mammals. In salamanders, dopamine neurons projecting to the striatum or brainstem locomotor networks were partly intermingled. Stimulation of the dopaminergic region evoked dopamine release in brainstem locomotor networks and concurrent reticulospinal activity. In rats, some dopamine neurons projecting to the striatum also innervated the pedunculopontine nucleus, a known locomotor center, and stimulation of the dopaminergic region evoked pedunculopontine dopamine release in vivo. Finally, we found dopaminergic fibers in the human pedunculopontine nucleus. The conservation of a descending dopaminergic pathway across vertebrates warrants re-evaluating dopamine’s role in locomotion. PMID:27071118

  8. Dopamine encoding of Pavlovian incentive stimuli diminishes with extended training.

    PubMed

    Clark, Jeremy J; Collins, Anne L; Sanford, Christina Akers; Phillips, Paul E M

    2013-02-20

    Dopamine is highly implicated both as a teaching signal in reinforcement learning and in motivating actions to obtain rewards. However, theoretical disconnects remain between the temporal encoding properties of dopamine neurons and the behavioral consequences of its release. Here, we demonstrate in rats that dopamine evoked by Pavlovian cues increases during acquisition, but dissociates from stable conditioned appetitive behavior as this signal returns to preconditioning levels with extended training. Experimental manipulation of the statistical parameters of the behavioral paradigm revealed that this attenuation of cue-evoked dopamine release during the postasymptotic period was attributable to acquired knowledge of the temporal structure of the task. In parallel, conditioned behavior became less dopamine dependent after extended training. Thus, the current work demonstrates that as the presentation of reward-predictive stimuli becomes anticipated through the acquisition of task information, there is a shift in the neurobiological substrates that mediate the motivational properties of these incentive stimuli. PMID:23426680

  9. Arithmetic and local circuitry underlying dopamine prediction errors

    PubMed Central

    Eshel, Neir; Bukwich, Michael; Rao, Vinod; Hemmelder, Vivian; Tian, Ju; Uchida, Naoshige

    2015-01-01

    Dopamine neurons are thought to facilitate learning by comparing actual and expected reward1,2. Despite two decades of investigation, little is known about how this comparison is made. To determine how dopamine neurons calculate prediction error, we combined optogenetic manipulations with extracellular recordings in the ventral tegmental area (VTA) while mice engaged in classical conditioning. By manipulating the temporal expectation of reward, we demonstrate that dopamine neurons perform subtraction, a computation that is ideal for reinforcement learning but rarely observed in the brain. Furthermore, selectively exciting and inhibiting neighbouring GABA neurons in the VTA reveals that these neurons are a source of subtraction: they inhibit dopamine neurons when reward is expected, causally contributing to prediction error calculations. Finally, bilaterally stimulating VTA GABA neurons dramatically reduces anticipatory licking to conditioned odours, consistent with an important role for these neurons in reinforcement learning. Together, our results uncover the arithmetic and local circuitry underlying dopamine prediction errors. PMID:26322583

  10. Label-free dopamine imaging in live rat brain slices.

    PubMed

    Sarkar, Bidyut; Banerjee, Arkarup; Das, Anand Kant; Nag, Suman; Kaushalya, Sanjeev Kumar; Tripathy, Umakanta; Shameem, Mohammad; Shukla, Shubha; Maiti, Sudipta

    2014-05-21

    Dopaminergic neurotransmission has been investigated extensively, yet direct optical probing of dopamine has not been possible in live cells. Here we image intracellular dopamine with sub-micrometer three-dimensional resolution by harnessing its intrinsic mid-ultraviolet (UV) autofluorescence. Two-photon excitation with visible light (540 nm) in conjunction with a non-epifluorescent detection scheme is used to circumvent the UV toxicity and the UV transmission problems. The method is established by imaging dopamine in a dopaminergic cell line and in control cells (glia), and is validated by mass spectrometry. We further show that individual dopamine vesicles/vesicular clusters can be imaged in cultured rat brain slices, thereby providing a direct visualization of the intracellular events preceding dopamine release induced by depolarization or amphetamine exposure. Our technique opens up a previously inaccessible mid-ultraviolet spectral regime (excitation ~270 nm, emission < 320 nm) for label-free imaging of native molecules in live tissue.

  11. Label-Free Dopamine Imaging in Live Rat Brain Slices

    PubMed Central

    2014-01-01

    Dopaminergic neurotransmission has been investigated extensively, yet direct optical probing of dopamine has not been possible in live cells. Here we image intracellular dopamine with sub-micrometer three-dimensional resolution by harnessing its intrinsic mid-ultraviolet (UV) autofluorescence. Two-photon excitation with visible light (540 nm) in conjunction with a non-epifluorescent detection scheme is used to circumvent the UV toxicity and the UV transmission problems. The method is established by imaging dopamine in a dopaminergic cell line and in control cells (glia), and is validated by mass spectrometry. We further show that individual dopamine vesicles/vesicular clusters can be imaged in cultured rat brain slices, thereby providing a direct visualization of the intracellular events preceding dopamine release induced by depolarization or amphetamine exposure. Our technique opens up a previously inaccessible mid-ultraviolet spectral regime (excitation ∼ 270 nm, emission < 320 nm) for label-free imaging of native molecules in live tissue. PMID:24661118

  12. Arithmetic and local circuitry underlying dopamine prediction errors.

    PubMed

    Eshel, Neir; Bukwich, Michael; Rao, Vinod; Hemmelder, Vivian; Tian, Ju; Uchida, Naoshige

    2015-09-10

    Dopamine neurons are thought to facilitate learning by comparing actual and expected reward. Despite two decades of investigation, little is known about how this comparison is made. To determine how dopamine neurons calculate prediction error, we combined optogenetic manipulations with extracellular recordings in the ventral tegmental area while mice engaged in classical conditioning. Here we demonstrate, by manipulating the temporal expectation of reward, that dopamine neurons perform subtraction, a computation that is ideal for reinforcement learning but rarely observed in the brain. Furthermore, selectively exciting and inhibiting neighbouring GABA (γ-aminobutyric acid) neurons in the ventral tegmental area reveals that these neurons are a source of subtraction: they inhibit dopamine neurons when reward is expected, causally contributing to prediction-error calculations. Finally, bilaterally stimulating ventral tegmental area GABA neurons dramatically reduces anticipatory licking to conditioned odours, consistent with an important role for these neurons in reinforcement learning. Together, our results uncover the arithmetic and local circuitry underlying dopamine prediction errors.

  13. A causal link between prediction errors, dopamine neurons and learning.

    PubMed

    Steinberg, Elizabeth E; Keiflin, Ronald; Boivin, Josiah R; Witten, Ilana B; Deisseroth, Karl; Janak, Patricia H

    2013-07-01

    Situations in which rewards are unexpectedly obtained or withheld represent opportunities for new learning. Often, this learning includes identifying cues that predict reward availability. Unexpected rewards strongly activate midbrain dopamine neurons. This phasic signal is proposed to support learning about antecedent cues by signaling discrepancies between actual and expected outcomes, termed a reward prediction error. However, it is unknown whether dopamine neuron prediction error signaling and cue-reward learning are causally linked. To test this hypothesis, we manipulated dopamine neuron activity in rats in two behavioral procedures, associative blocking and extinction, that illustrate the essential function of prediction errors in learning. We observed that optogenetic activation of dopamine neurons concurrent with reward delivery, mimicking a prediction error, was sufficient to cause long-lasting increases in cue-elicited reward-seeking behavior. Our findings establish a causal role for temporally precise dopamine neuron signaling in cue-reward learning, bridging a critical gap between experimental evidence and influential theoretical frameworks.

  14. Dopamine and lipophilic derivates protect cardiomyocytes against cold preservation injury.

    PubMed

    Vettel, Christiane; Hottenrott, Maximilia C; Spindler, Rahel; Benck, Urs; Schnuelle, Peter; Tsagogiorgas, Charalambos; Krämer, Bernhard K; Hoeger, Simone; El-Armouche, Ali; Wieland, Thomas; Yard, Benito A

    2014-01-01

    Donor heart allografts are extremely susceptible to prolonged static cold storage. Because donor treatment with low-dose dopamine improves clinical outcome after heart transplantation, we tested the hypothesis that dopamine and its lipophilic derivate, N-octanoyl dopamine (NOD), protect cardiomyocytes from cold storage injury. Neonatal rat cardiomyocytes were treated with dopamine or NOD or left untreated and subsequently subjected to static cold storage (8-12 hours). Dopamine- and NOD-treated cardiomyocytes displayed a better viability compared with untreated cells after hypothermia. In untreated cardiomyocytes, cell damage was reflected by lactate dehydrogenase (LDH) release and a decrease in intracellular ATP. NOD was approximately 20-fold more potent than dopamine. Similarly to cardiomyocytes in vitro, rat hearts perfused with NOD before explantation showed significantly lower LDH release after static cold storage. ATP regeneration and spontaneous contractions after cold storage and rewarming only occurred in treated cardiomyocytes. Hypothermia severely attenuated isoprenaline-induced cAMP formation in control but not in dopamine- or NOD-treated cells. Esterified derivates of NOD with redox potential and lipophilic side chains reduced cell damage during cold storage similarly to NOD. In contrast to dopamine, neither NOD nor its derivates induced a significant β-adrenoceptor-mediated elevation of cellular cAMP levels. The β1-adrenoceptor antagonist atenolol and D1/D2 receptor antagonist fluphenazine had no impact on the protective effect of NOD or dopamine. We conclude that dopamine as well as NOD treatment mitigates cold preservation injury to cardiomyocytes. The beneficial effects are independent of β-adrenoceptor or dopaminergic receptor stimulation but correlate with redox potential and lipophilic properties.

  15. Reduced Presynaptic Dopamine Activity in Adolescent Dorsal Striatum

    PubMed Central

    Matthews, Marguerite; Bondi, Corina; Torres, Gonzalo; Moghaddam, Bita

    2013-01-01

    Adolescence coincides with symptomatic onset of several psychiatric illnesses including schizophrenia and addiction. Excess limbic dopamine activity has been implicated in these vulnerabilities. We combined molecular and dynamic indices of dopamine neurotransmission to assess dopamine function in adolescent rats in two functionally distinct striatal subregions: nucleus accumbens (NAc) and dorsal striatum (DS). In adolescents, we find an overall reduction in dopamine availability selective to the DS. Dopamine release in the DS, but not in the NAc, was less responsive to amphetamine in adolescents compared to adults. The dopamine transporter (DAT) inhibitor, nomifensine, similarly inhibited basal and amphetamine-induced dopamine release in either regions of both the age groups, suggesting that the reduced effectiveness of amphetamine is not due to differences in DAT function. Furthermore, DAT and vesicular monoamine transporter-2 expressions were similar in the DS and NAc of adolescent rats. In contrast, expression of tyrosine hydroxylase (TH) was reduced in the DS, but not in the NAc, of adolescents compared to adults. Behaviorally, adolescents were less sensitive to amphetamine but more sensitive to a TH inhibitor. These data indicate that, in contrast to the general notion that dopamine is hyperactive in adolescents, there is diminished presynaptic dopamine activity in adolescents that is selective to the DS and may result from attenuated TH activity. Given recent reports of altered dopamine activity in associative/dorsal striatum of individuals at a clinically high risk of psychosis, our data further support the idea that dorsal, as opposed to ventral, regions of the striatum are a locus of vulnerability for psychosis. PMID:23358239

  16. Reduced presynaptic dopamine activity in adolescent dorsal striatum.

    PubMed

    Matthews, Marguerite; Bondi, Corina; Torres, Gonzalo; Moghaddam, Bita

    2013-06-01

    Adolescence coincides with symptomatic onset of several psychiatric illnesses including schizophrenia and addiction. Excess limbic dopamine activity has been implicated in these vulnerabilities. We combined molecular and dynamic indices of dopamine neurotransmission to assess dopamine function in adolescent rats in two functionally distinct striatal subregions: nucleus accumbens (NAc) and dorsal striatum (DS). In adolescents, we find an overall reduction in dopamine availability selective to the DS. Dopamine release in the DS, but not in the NAc, was less responsive to amphetamine in adolescents compared to adults. The dopamine transporter (DAT) inhibitor, nomifensine, similarly inhibited basal and amphetamine-induced dopamine release in either regions of both the age groups, suggesting that the reduced effectiveness of amphetamine is not due to differences in DAT function. Furthermore, DAT and vesicular monoamine transporter-2 expressions were similar in the DS and NAc of adolescent rats. In contrast, expression of tyrosine hydroxylase (TH) was reduced in the DS, but not in the NAc, of adolescents compared to adults. Behaviorally, adolescents were less sensitive to amphetamine but more sensitive to a TH inhibitor. These data indicate that, in contrast to the general notion that dopamine is hyperactive in adolescents, there is diminished presynaptic dopamine activity in adolescents that is selective to the DS and may result from attenuated TH activity. Given recent reports of altered dopamine activity in associative/dorsal striatum of individuals at a clinically high risk of psychosis, our data further support the idea that dorsal, as opposed to ventral, regions of the striatum are a locus of vulnerability for psychosis.

  17. Dopamine-stimulated dephosphorylation of connexin 36 mediates AII amacrine cell uncoupling.

    PubMed

    Kothmann, W Wade; Massey, Stephen C; O'Brien, John

    2009-11-25

    Gap junction proteins form the substrate for electrical coupling between neurons. These electrical synapses are widespread in the CNS and serve a variety of important functions. In the retina, connexin 36 (Cx36) gap junctions couple AII amacrine cells and are a requisite component of the high-sensitivity rod photoreceptor pathway. AII amacrine cell coupling strength is dynamically regulated by background light intensity, and uncoupling is thought to be mediated by dopamine signaling via D(1)-like receptors. One proposed mechanism for this uncoupling involves dopamine-stimulated phosphorylation of Cx36 at regulatory sites, mediated by protein kinase A. Here we provide evidence against this hypothesis and demonstrate a direct relationship between Cx36 phosphorylation and AII amacrine cell coupling strength. Dopamine receptor-driven uncoupling of the AII network results from protein kinase A activation of protein phosphatase 2A and subsequent dephosphorylation of Cx36. Protein phosphatase 1 activity negatively regulates this pathway. We also find that Cx36 gap junctions can exist in widely different phosphorylation states within a single neuron, implying that coupling is controlled at the level of individual gap junctions by locally assembled signaling complexes. This kind of synapse-by-synapse plasticity allows for precise control of neuronal coupling, as well as cell-type-specific responses dependent on the identity of the signaling complexes assembled.

  18. Melanocortin 4 Receptor and Dopamine D2 Receptor Expression in Brain Areas Involved in Food Intake

    PubMed Central

    Yoon, Ye Ran

    2015-01-01

    Background The melanocortin 4 receptor (MC4R) is involved in the regulation of homeostatic energy balance by the hypothalamus. Recent reports showed that MC4R can also control the motivation for food in association with a brain reward system, such as dopamine. We investigated the expression levels of MC4R and the dopamine D2 receptor (D2R), which is known to be related to food rewards, in both the hypothalamus and brain regions involved in food rewards. Methods We examined the expression levels of D2R and MC4R by dual immunofluorescence histochemistry in hypothalamic regions and in the bed nucleus of the stria terminalis (BNST), the central amygdala, and the ventral tegmental area of transgenic mice expressing enhanced green fluorescent protein under the control of the D2R gene. Results In the hypothalamic area, significant coexpression of MC4R and D2R was observed in the arcuate nucleus. We observed a significant coexpression of D2R and MC4R in the BNST, which has been suggested to be an important site for food reward. Conclusion We suggest that MC4R and D2R function in the hypothalamus for control of energy homeostasis and that within the brain regions related with rewards, such as the BNST, the melanocortin system works synergistically with dopamine for the integration of food motivation in the control of feeding behaviors. PMID:26790386

  19. Synthesis and evaluation of novel tropane derivatives as potential PET imaging agents for the dopamine transporter

    PubMed Central

    Qiao, Hongwen; Zhu, Lin; Lieberman, Brian P.; Zha, Zhihao; Plössl, Karl; Kung, Hank F.

    2012-01-01

    A novel series of tropane derivatives containing a fluorinated tertiary amino or amide at the 2β position was synthesized, labeled with the positron-emitter fluorine-18 (T1/2 = 109.8 min), and tested as potential in vivo dopamine transporter (DAT) imaging agents. The corresponding chlorinated analogs were prepared and employed as precursors for radiolabeling leading to the fluorine-18-labeled derivatives via a one-step nucleophilic aliphatic substitution reaction. In vitro binding results showed that the 2β-amino compounds 6b, 6d and 7b displayed moderately high affinities to DAT (Ki < 10 nM). Biodistribution studies of [18F]6b and [18F]6d showed that the brain uptakes in rats were low. This is likely due to their low lipophilicities. Further structural modifications of these tropane derivatives will be needed to improve their in vivo properties as DAT imaging agents. PMID:22658558

  20. Numerical model for the uptake of groundwater contaminants by phreatophytes

    USGS Publications Warehouse

    Widdowson, M.A.; El-Sayed, A.; Landmeyer, J.E.

    2008-01-01

    Conventional solute transport models do not adequately account for the effects of phreatophytic plant systems on contaminant concentrations in shallow groundwater systems. A numerical model was developed and tested to simulate threedimensional reactive solute transport in a heterogeneous porous medium. Advective-dispersive transport is coupled to biodegradation, sorption, and plantbased attenuation processes including plant uptake and sorption by plant roots. The latter effects are a function of the physical-chemical properties of the individual solutes and plant species. Models for plant uptake were tested and evaluated using the experimental data collected at a field site comprised of hybrid poplar trees. A non-linear equilibrium isotherm model best represented site conditions.

  1. Neurotransmission in Parkinson's disease: beyond dopamine.

    PubMed

    Barone, P

    2010-03-01

    Parkinson's disease (PD) is most frequently associated with characteristic motor symptoms that are known to arise with degeneration of dopaminergic neurons. However, patients with this disease also experience a multitude of non-motor symptoms, such as sleep disturbances, fatigue, apathy, anxiety, depression, cognitive impairment, dementia, olfactory dysfunction, pain, sweating and constipation, some of which can be at least as debilitating as the movement disorders and have a major impact on patients' quality of life. Many of these non-motor symptoms may be evident prior to the onset of motor dysfunction. The neuropathology of PD has shown that complex, interconnected neuronal systems, regulated by a number of different neurotransmitters in addition to dopamine, are involved in the aetiology of motor and non-motor symptoms. This review focuses on the non-dopaminergic neurotransmission systems associated with PD with particular reference to the effect that their modulation and interaction with dopamine has on the non-motor symptoms of the disease. PD treatments that focus on the dopaminergic system alone are unable to alleviate both motor and non-motor symptoms, particularly those that develop at early stages of the disease. The development of agents that interact with several of the affected neurotransmission systems could prove invaluable for the treatment of this disease.

  2. [Scans without Evidence of Dopamine Deficit (SWEDDs)].

    PubMed

    Mukai, Yohei; Murata, Miho

    2016-01-01

    Dopamine transporter (DaT) single-photon emission computed tomography (SPECT) and [18F]fluoro-L-DOPA ([18F]DOPA) positron emission tomography (PET) facilitate the investigation of dopaminergic hypofunction in neurodegenerative diseases. DaT SPECT and [18F]DOPA PET have been adopted as survey tools in clinical trials. In a large study on Parkinson's disease, 4-15% of subjects clinically diagnosed with early-stage Parkinson's disease had normal dopaminergic functional imaging scans. These are called Scans without Evidence of Dopamine Deficit (SWEDDs), and are considered to represent a state different from Parkinson's disease. Neurological diseases that exhibit parkinsonism and have normal dopaminergic cells in the nigrostriatal system (e.g., essential tremor, psychogenic parkinsonism, DOPA-responsive dystonia, vascular parkinsonism, drug-induced parkinsonism, manganism, brain tumor, myoclonus-dystonia (DYT11), and fragile X syndrome) might be diagnosed with SWEDDs. True bradykinesia with fatigue or decrement may be useful for distinguishing between Parkinson's disease and SWEDDs. However, because SWEDDs encompass many diseases, their properties may not be uniform. In this review, we discuss DaT SPECT, the concept of SWEDDs, and differential diagnosis. PMID:26764301

  3. Lobelane inhibits methamphetamine-evoked dopamine release via inhibition of the vesicular monoamine transporter-2.

    PubMed

    Nickell, Justin R; Krishnamurthy, Sairam; Norrholm, Seth; Deaciuc, Gabriela; Siripurapu, Kiran B; Zheng, Guangrong; Crooks, Peter A; Dwoskin, Linda P

    2010-02-01

    Lobeline is currently being evaluated in clinical trials as a methamphetamine abuse treatment. Lobeline interacts with nicotinic receptor subtypes, dopamine transporters (DATs), and vesicular monoamine transporters (VMAT2s). Methamphetamine inhibits VMAT2 and promotes dopamine (DA) release from synaptic vesicles, resulting ultimately in increased extracellular DA. The present study generated structure-activity relationships by defunctionalizing the lobeline molecule and determining effects on [(3)H]dihydrotetrabenazine binding, inhibition of [(3)H]DA uptake into striatal synaptic vesicles and synaptosomes, the mechanism of VMAT2 inhibition, and inhibition of methamphetamine-evoked DA release. Compared with lobeline, the analogs exhibited greater potency inhibiting DA transporter (DAT) function. Saturated analogs, lobelane and nor-lobelane, exhibited high potency (K(i) = 45 nM) inhibiting vesicular [(3)H]DA uptake, and lobelane competitively inhibited VMAT2 function. Lobeline and lobelane exhibited 67- and 35-fold greater potency, respectively, in inhibiting VMAT2 function compared to DAT function. Lobelane potently decreased (IC(50) = 0.65 microM; I(max) = 73%) methamphetamine-evoked DA overflow, and with a greater maximal effect compared with lobeline (IC(50) = 0.42 microM, I(max) = 56.1%). These results provide support for VMAT2 as a target for inhibition of methamphetamine effects. Both trans-isomers and demethylated analogs of lobelane had reduced or unaltered potency inhibiting VMAT2 function and lower maximal inhibition of methamphetamine-evoked DA release compared with lobelane. Thus, defunctionalization, cis-stereochemistry of the side chains, and presence of the piperidino N-methyl are structural features that afford greatest inhibition of methamphetamine-evoked DA release and enhancement of selectivity for VMAT2. The current results reveal that lobelane, a selective VMAT2 inhibitor, inhibits methamphetamine-evoked DA release and is a promising lead for

  4. Lobelane Inhibits Methamphetamine-Evoked Dopamine Release via Inhibition of the Vesicular Monoamine Transporter-2S⃞

    PubMed Central

    Nickell, Justin R.; Krishnamurthy, Sairam; Norrholm, Seth; Deaciuc, Gabriela; Siripurapu, Kiran B.; Zheng, Guangrong; Crooks, Peter A.

    2010-01-01

    Lobeline is currently being evaluated in clinical trials as a methamphetamine abuse treatment. Lobeline interacts with nicotinic receptor subtypes, dopamine transporters (DATs), and vesicular monoamine transporters (VMAT2s). Methamphetamine inhibits VMAT2 and promotes dopamine (DA) release from synaptic vesicles, resulting ultimately in increased extracellular DA. The present study generated structure-activity relationships by defunctionalizing the lobeline molecule and determining effects on [3H]dihydrotetrabenazine binding, inhibition of [3H]DA uptake into striatal synaptic vesicles and synaptosomes, the mechanism of VMAT2 inhibition, and inhibition of methamphetamine-evoked DA release. Compared with lobeline, the analogs exhibited greater potency inhibiting DA transporter (DAT) function. Saturated analogs, lobelane and nor-lobelane, exhibited high potency (Ki = 45 nM) inhibiting vesicular [3H]DA uptake, and lobelane competitively inhibited VMAT2 function. Lobeline and lobelane exhibited 67- and 35-fold greater potency, respectively, in inhibiting VMAT2 function compared to DAT function. Lobelane potently decreased (IC50 = 0.65 μM; Imax = 73%) methamphetamine-evoked DA overflow, and with a greater maximal effect compared with lobeline (IC50 = 0.42 μM, Imax = 56.1%). These results provide support for VMAT2 as a target for inhibition of methamphetamine effects. Both trans-isomers and demethylated analogs of lobelane had reduced or unaltered potency inhibiting VMAT2 function and lower maximal inhibition of methamphetamine-evoked DA release compared with lobelane. Thus, defunctionalization, cis-stereochemistry of the side chains, and presence of the piperidino N-methyl are structural features that afford greatest inhibition of methamphetamine-evoked DA release and enhancement of selectivity for VMAT2. The current results reveal that lobelane, a selective VMAT2 inhibitor, inhibits methamphetamine-evoked DA release and is a promising lead for the development of a

  5. Low dopamine activity in Lesch Nyhan Disease. An 18-fluorodopa PET study

    SciTech Connect

    Ernst, M.; Zametkin, A.; Matochik, J.

    1996-05-01

    Lesch-Nyhan Disease (LND) is a rare devastating X-linked recessive disorder characterized by the virtual absence of hypoxanthine guanine phosphoribosyl transferase (HPRT), a major enzyme of the salvage pathway of purine metabolism. The clinical presentation includes hyperuricemia choreoathetosis, dystonia, aggression and self-injurious behavior. The genetic and biochemical abnormalities are fully identified. However, the neuropathophysiological process by which the lack of HPRT produces the neuropsychiatric syndrome of LND in unclear. Presynaptic uptake of 18-Fluorodopa (FD) in basal ganglia, substantia nigra, and frontal and occipital cortices was measured by PET in 12 patients with LND, 10 to 20 years old, and 15 health controls, 12 to 23 years old. Radioactive counts (mCi/cc), recorded between 90 and 130 minutes after tracer injection, were measured in regions of interest by a rater blind to subjects` identities. Results were expressed as ratios of FD uptake in specific to non-specific (occipital cortex) brain areas. Presynaptic dopamine activity was significantly lower by 69% in putamen (p<0.0001), 61% in caudate (p<0.0001), 56% in frontal cortex (p=0.003) and 43% in substantiat nigra (p<0.016) in LND patients than in control subjects. Absolute FD measures in occipital regions did not differ between the two groups. Activity of FD in the basal ganglia was stable over time in the LND group and tended to increase in the control group (r=0.50, n=15, p=0.060). In the LND group, aggressive behavior was worse as FD activity was higher (r=0.60, n=12, p=0.40). LND is associated with a striking reduction of presynaptic dopamine activity that is not region-specific. The temporal stability of FD measures and of the severity of LND symptomatology is consistent with a developmental rather than degenerative process.

  6. Behavioral, biological, and chemical perspectives on atypical agents targeting the dopamine transporterɸ

    PubMed Central

    Reith, Maarten E.A.; Blough, Bruce E.; Hong, Weimin C.; Jones, Kymry T.; Schmitt, Kyle C.; Baumann, Michael H.; Partilla, John S.; Rothman, Richard B.; Katz, Jonathan L.

    2014-01-01

    Background Treatment of Stimulant-Use Disorders remains a formidable challenge, and the dopamine transporter (DAT) remains a potential target for antagonist or agonist-like substitution therapies. Methods This review focuses on DAT ligands, such as benztropine, GBR 12909, modafinil, and DAT substrates derived from phenethylamine or cathinone that have atypical DAT-inhibitor effects, either in vitro or in vivo. The compounds are described from a molecular mechanistic, behavioral, and medicinal-chemical perspective. Results Possible mechanisms for atypicality at the molecular level can be deduced from the conformational cycle for substrate translocation. For each conformation, a crystal structure of a bacterial homolog is available, with a possible role of cholesterol, which is also present in the crystal of drosophila DAT. Although there is a direct relationship between behavioral potencies of most DAT inhibitors and their DAT affinities, a number of compounds bind to the DAT and inhibit dopamine uptake but do not share cocaine-like effects. Such atypical behavior, depending on the compound, may be related to slow DAT association, combined sigma-receptor actions, or bias for cytosol-facing DAT. Some structures are sterically small enough to serve as DAT substrates but large enough to also inhibit transport. Such compounds may display partial DA releasing effects, and may be combined with release or uptake inhibition at other monoamine transporters. Conclusions Mechanisms of atypical DAT inhibitors may serve as targets for the development of treatments for stimulant abuse. These mechanisms are novel and their further exploration may produce compounds with unique therapeutic potential as treatments for stimulant abuse. PMID:25548026

  7. Evidence that ibogaine releases dopamine from the cytoplasmic pool in isolated mouse striatum.

    PubMed

    Harsing, L G; Sershen, H; Lajtha, A

    1994-01-01

    We measured the effect of ibogaine on the tritium efflux from isolated mouse striatum preloaded with [3H]dopamine ([3H]DA). Ibogaine increased the basal tritium outflow in a concentration-dependent manner, but it was without effect on electrical stimulation-induced tritium overflow. Separation of the released radioactivity after ibogaine administration showed that this drug increased the release of [3H]DA and [3H]-dihydroxyphenylacetic acid ([3H]DOPAC), but the efflux of O-methylated-deaminated metabolites was not changed. The dopamine (DA)-releasing effect of ibogaine was reduced by the DA uptake inhibitors cocaine and nomifensine. The tritium efflux evoked by ibogaine was not altered by omission of Ca2+ from the perfusion buffer or by inhibition of the voltage-sensitive Na+ channels with tetrodotoxin. Ibogaine maintained its effect on release from superfused striatum prepared from reserpine-pretreated mice. The ibogaine-induced tritium release measured from mouse striatum that was preloaded with [3H]DA was not affected by the D-2 DA receptor ligands (-)-quinpirole and (+/-)-sulpiride, indicating that the ibogaine-induced release is not subject to presynaptic autoreceptor regulation. Ibogaine failed to affect [3H]DA uptake and retention in mouse striatum. These data indicate that at the nerve terminal level ibogaine releases DA, and the primary source for the release is probably the cytoplasmic pool. The DA-releasing effect of ibogaine may have importance in mediation of its hallucinogenic action, as seen in a frequent practice in African cults. PMID:7826572

  8. Calcium influx through L-type channels generates protein kinase M to induce burst firing of dopamine cells in the rat ventral tegmental area.

    PubMed

    Liu, Yudan; Dore, Jules; Chen, Xihua

    2007-03-23

    Enhanced activity of the dopaminergic system originating in the ventral tegmental area is implicated in addictive and psychiatric disorders. Burst firing increases dopamine levels at the synapse to signal novelty and salience. We have previously reported a calcium-dependent burst firing of dopamine cells mediated by L-type channels following cholinergic stimulation; this paper describes a cellular mechanism resulting in burst firing following L-type channel activation. Calcium influx through L-type channels following FPL 64176 or (S)-(-)-Bay K8644 induced burst firing independent of dopamine, glutamate, or calcium from the internal stores. Burst firing induced as such was completely blocked by the substrate site protein kinase C (PKC) inhibitor chelerythrine but not by the diacylglycerol site inhibitor calphostin C. Western blotting analysis showed that FPL 64176 and (S)-(-)-Bay K8644 increased the cleavage of PKC to generate protein kinase M (PKM) and the specific calpain inhibitor MDL28170 blocked this increase. Prevention of PKM production by inhibiting calpain or depleting PKC blocked burst firing induction whereas direct loading of purified PKM into cells induced burst firing. Activation of the N-methyl-D-aspartic acid type glutamate or cholinergic receptors known to induce burst firing increased PKM expression. These results indicate that calcium influx through L-type channels activates a calcium-dependent protease that cleaves PKC to generate constitutively active and labile PKM resulting in burst firing of dopamine cells, a pathway that is involved in glutamatergic or cholinergic modulation of the central dopamine system.

  9. Elevated dopamine concentration in light-adapted zebrafish retinas is correlated with increased dopamine synthesis and metabolism.

    PubMed

    Connaughton, Victoria P; Wetzell, Bradley; Arneson, Lynne S; DeLucia, Vittoria; Riley, Anthony L

    2015-10-01

    Probing zebrafish (Danio rerio) retinal cryostat sections, collected either 8 h into the light or dark cycle, with an antibody against tyrosine hydroxylase (TH) identified a single population of immunopositive cells in the inner retina. However, the observed labeling patterns were not identical in both sets of tissues - label intensity was brighter in light-adapted tissue. This difference was quantified by probing western blots of retinal homogenates with the same TH antibody, which showed that TH expression increased by 42% in light-adapted tissue. High-performance liquid chromatography with electrochemical detection revealed that the concentrations of both dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) are also elevated in light-adapted zebrafish retinal tissue. Dopamine levels increased by 14% and DOPAC levels increased by 25% when measured in retinal homogenates harvested during the light cycle. These results indicate that dopamine levels in zebrafish retina are significantly increased in light-adapted tissue. The increase in dopamine content is correlated with an increase in both TH and DOPAC, suggesting that changes in dopamine concentration are due to light-adaptive changes in the synthesis, release and metabolism of dopamine. Dopamine concentration is elevated in lighted-adapted zebrafish retinas. This increase is correlated with an increase in both tyrosine hydroxylase (TH) and DOPAC (3,4-dihydroxyphenylacetic acid), suggesting that changes in dopamine concentration are due to light-adaptive changes in the synthesis, release and metabolism of dopamine. This is applicable to studies examining retinal mutants, the role of dopamine in disease or visual system development.

  10. Uptake of VOC by sunflower

    NASA Astrophysics Data System (ADS)

    Folkers, A.; Miebach, M.; Kleist, E.; Wildt, J.

    2003-04-01

    To study potential VOC uptake by plants we exposed sunflower (Helianthus annuus) to different VOC in continuously stirred tank reactors. For many VOC like methanol, ethanol, acetone, methylvinylketone, isoprene or limonene no uptake was detectable within the accuracy of our analytic set up. Other VOC like hexanal, octanal, (E)-3-hexenol and nopinone were taken up by sunflower. The uptake was related to stomatal aperture. Obviously, these VOC enter the plants through stomata. In case of hexanal, octanal, and (E)-3-hexenol the uptake was only limited by stomatal aperture implying that these VOC are rapidly metabolised. For nopinone the uptake seems to be limited by a slow metabolization. Estimations of deposition velocities showed that dry deposition of these compounds cannot be neglected as sink if diffusion through stomata is the limiting step for dry deposition. In such cases the lifetime with respect to dry deposiotion is comparable to the lifetime with respect to oxidation by hydroxyl radicals.

  11. 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…

  12. Not All Antidepressants Are Created Equal: Differential Effects of Monoamine Uptake Inhibitors on Effort-Related Choice Behavior.

    PubMed

    Yohn, Samantha E; Collins, Samantha L; Contreras-Mora, Hector M; Errante, Emily L; Rowland, Margaret A; Correa, Merce; Salamone, John D

    2016-02-01

    Motivated behavior can be characterized by behavioral activation and high work output. Moreover, people with depression and other disorders show effort-related motivational symptoms, such as anergia, psychomotor retardation, and fatigue. Effort-based decision making is studied using tasks offering choices between high effort options leading to highly valued reinforcers vs low effort/low reward options, and such tasks could be useful as animal models of motivational symptoms. In the present studies the effort-related effects of the vesicular monoamine transport (VMAT-2) inhibitor tetrabenazine (TBZ) were investigated. TBZ blocks vesicular storage and also produces depressive symptoms in humans. Moreover, TBZ alters effort-based choice in rats, biasing animals toward low effort alternatives. The present studies investigated the ability of acute administration of various monoamine uptake inhibitors to reverse the effects of TBZ. Effort-related effects of TBZ were attenuated by the catecholamine uptake inhibitor and antidepressant bupropion, and this effect of bupropion was reversed by either D1 or D2 family antagonism. The effort-related effects of TBZ were also attenuated by the selective dopamine uptake blocker GBR12909. The 5-HT uptake inhibitor fluoxetine and the norepinephrine uptake inhibitor desipramine failed to reverse the effects of TBZ, and higher doses of these drugs, given alone or in combination with TBZ, led to further behavioral impairments. These results indicate that drugs acting on dopamine transmission are relatively effective at reversing the effort-related effects of TBZ, and are consistent with the hypothesis that drugs that enhance dopamine transmission may be effective at treating effort-related psychiatric symptoms in humans.

  13. Maternal Immune Activation Disrupts Dopamine System in the Offspring

    PubMed Central

    Luchicchi, Antonio; Lecca, Salvatore; Melis, Miriam; De Felice, Marta; Cadeddu, Francesca; Frau, Roberto; Muntoni, Anna Lisa; Fadda, Paola; Devoto, Paola

    2016-01-01

    Background: In utero exposure to maternal viral infections is associated with a higher incidence of psychiatric disorders with a supposed neurodevelopmental origin, including schizophrenia. Hence, immune response factors exert a negative impact on brain maturation that predisposes the offspring to the emergence of pathological phenotypes later in life. Although ventral tegmental area dopamine neurons and their target regions play essential roles in the pathophysiology of psychoses, it remains to be fully elucidated how dopamine activity and functionality are disrupted in maternal immune activation models of schizophrenia. Methods: Here, we used an immune-mediated neurodevelopmental disruption model based on prenatal administration of the polyriboinosinic-polyribocytidilic acid in rats, which mimics a viral infection and recapitulates behavioral abnormalities relevant to psychiatric disorders in the offspring. Extracellular dopamine levels were measured by brain microdialysis in both the nucleus accumbens shell and the medial prefrontal cortex, whereas dopamine neurons in ventral tegmental area were studied by in vivo electrophysiology. Results: Polyriboinosinic-polyribocytidilic acid-treated animals, at adulthood, displayed deficits in sensorimotor gating, memory, and social interaction and increased baseline extracellular dopamine levels in the nucleus accumbens, but not in the prefrontal cortex. In polyriboinosinic-polyribocytidilic acid rats, dopamine neurons showed reduced spontaneously firing rate and population activity. Conclusions: These results confirm that maternal immune activation severely impairs dopamine system and that the polyriboinosinic-polyribocytidilic acid model can be considered a proper animal model of a psychiatric condition that fulfills a multidimensional set of validity criteria predictive of a human pathology. PMID:26819283

  14. Dopamine modulates metabolic rate and temperature sensitivity in Drosophila melanogaster.

    PubMed

    Ueno, Taro; Tomita, Jun; Kume, Shoen; Kume, Kazuhiko

    2012-01-01

    Homeothermal animals, such as mammals, maintain their body temperature by heat generation and heat dissipation, while poikilothermal animals, such as insects, accomplish it by relocating to an environment of their favored temperature. Catecholamines are known to regulate thermogenesis and metabolic rate in mammals, but their roles in other animals are poorly understood. The fruit fly, Drosophila melanogaster, has been used as a model system for the genetic studies of temperature preference behavior. Here, we demonstrate that metabolic rate and temperature sensitivity of some temperature sensitive behaviors are regulated by dopamine in Drosophila. Temperature-sensitive molecules like dTrpA1 and shi(ts) induce temperature-dependent behavioral changes, and the temperature at which the changes are induced were lowered in the dopamine transporter-defective mutant, fumin. The mutant also displays a preference for lower temperatures. This thermophobic phenotype was rescued by the genetic recovery of the dopamine transporter in dopamine neurons. Flies fed with a dopamine biosynthesis inhibitor (3-iodo-L-tyrosine), which diminishes dopamine signaling, exhibited preference for a higher temperature. Furthermore, we found that the metabolic rate is up-regulated in the fumin mutant. Taken together, dopamine has functions in the temperature sensitivity of behavioral changes and metabolic rate regulation in Drosophila, as well as its previously reported functions in arousal/sleep regulation.

  15. Dopamine receptor signaling and current and future antipsychotic drugs

    PubMed Central

    Boyd, Kevin N.; Mailman, Richard B.

    2015-01-01

    All currently efficacious antipsychotic drugs have as part of their mechanism the ability to attenuate some or all of their signaling through the dopamine D2 receptor. More recently, the dopamine D1 receptor has been hypothesized to be a promising target for the treatment of negative and/or cognitive aspects of schizophrenia that are not improved by current antipsychotics. Although cAMP has been presumed to be the primary messenger for signaling through the dopamine receptors, the last decade has unveiled a complexity that has provided exciting avenues for the future discovery of antipsychotic drugs (APDs). We review the signaling mechanisms of currently approved APDs at dopamine D2 receptors, and note that aripiprazole is a compound that is clearly differentiated from other approved drugs. Although aripiprazole has been postulated to cause dopamine stabilization due to its partial D2 agonist properties, a body of literature suggests that an alternate mechanism, functional selectivity, is of primary importance. Finally, we review the signaling at dopamine D1 receptors, and the idea that drugs that activate D1 receptors may have use as APDs for improving negative and cognitive symptoms. We address the current state of drug discovery in the D1 area, and its relationship to novel signaling mechanisms. Our conclusion is that although the first APD targeting dopamine receptors was discovered more than a half-century ago, recent research advances offer the possibility that novel and/or improved drugs will emerge in the next decade. PMID:23129328

  16. Dopamine modulates novelty seeking behavior during decision making.

    PubMed

    Costa, Vincent D; Tran, Valery L; Turchi, Janita; Averbeck, Bruno B

    2014-10-01

    Novelty seeking refers to the tendency of humans and animals to explore novel and unfamiliar stimuli and environments. The idea that dopamine modulates novelty seeking is supported by evidence that novel stimuli excite dopamine neurons and activate brain regions receiving dopaminergic input. In addition, dopamine is shown to drive exploratory behavior in novel environments. It is not clear whether dopamine promotes novelty seeking when it is framed as the decision to explore novel options versus the exploitation of familiar options. To test this hypothesis, we administered systemic injections of saline or GBR-12909, a selective dopamine transporter (DAT) inhibitor, to monkeys and assessed their novelty seeking behavior during a probabilistic decision making task. The task involved pseudorandom introductions of novel choice options. This allowed monkeys the opportunity to explore novel options or to exploit familiar options that they had already sampled. We found that DAT blockade increased the monkeys' preference for novel options. A reinforcement learning (RL) model fit to the monkeys' choice data showed that increased novelty seeking after DAT blockade was driven by an increase in the initial value the monkeys assigned to novel options. However, blocking DAT did not modulate the rate at which the monkeys learned which cues were most predictive of reward or their tendency to exploit that knowledge. These data demonstrate that dopamine enhances novelty-driven value and imply that excessive novelty seeking-characteristic of impulsivity and behavioral addictions-might be caused by increases in dopamine, stemming from less reuptake.

  17. Prefrontal cortical dopamine transmission is decreased in alcoholism

    PubMed Central

    Narendran, Rajesh; Mason, Neale Scott; Paris, Jennifer; Himes, Michael L.; Douaihy, Antoine B.; Frankle, W. Gordon

    2014-01-01

    Objective Basic studies have demonstra