Enhanced cellular uptake and in vitro antitumor activity of short-chain fatty acid acylated daunorubicin-GnRH-III bioconjugates.

PubMed

Hegedüs, Rózsa; Manea, Marilena; Orbán, Erika; Szabó, Ildikó; Kiss, Eva; Sipos, Eva; Halmos, Gábor; Mező, Gábor

2012-10-01

Here we report on the synthesis and biochemical characterization (enzymatic stability, cellular uptake, in vitro antitumor activity, membrane interaction and GnRH-receptor binding affinity) of novel short-chain fatty acid (SCFA) acylated daunorubicin-GnRH-III bioconjugates, which may serve as drug delivery systems for targeted cancer chemotherapy. Ser in position 4 of GnRH-III was replaced by Lys, followed by the acylation of its ε-amino group with various fatty acids. SCFAs are potentially chemoprotective agents by suppressing the growth of cancer cells and therefore may enhance the antitumor activity of the bioconjugates. We found that all synthesized bioconjugates had high cytostatic effect in vitro, were stable in cell culture medium for 6 h and degraded in the presence of rat liver lysosomal homogenate leading to the formation of an oxime bond-linked daunorubicin-Lys as the smallest active metabolite. In the presence of α-chymotrypsin, all compounds were digested, the degradation rate strongly depending on the type of fatty acid. The bioconjugate containing Lys(nBu) in position 4 was taken up most efficiently by the cancer cells and exerted higher in vitro cytostatic effect than the previously developed GnRH-III((4)Lys(Ac), (8)Lys(Dau = Aoa)) or the parent GnRH-III(Dau = Aoa) bioconjugate. Our results could be explained by the increased binding affinity of the newly developed compound containing Lys(nBu) to the GnRH receptors. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Impact of Antibody Bioconjugation on Emission and Energy Band Profile of CdSeTe/ZnS Quantum Dots

NASA Astrophysics Data System (ADS)

Torchynska, T. V.; Gomez, J. A. Jaramillo; Polupan, G.; Macotela, L. G. Vega

2018-03-01

The variation of the photoluminescence (PL) and Raman scattering spectra of CdSeTe/ZnS quantum dots (QDs) on conjugation to an antibody has been investigated. Two types of CdSeTe/ZnS QD with different emission wavelength (705 nm and 800 nm) were studied comparatively before and after conjugation to anti-pseudorabies virus antibody (AB). Nonconjugated QDs were characterized by Gaussian-type PL bands. PL shifts to higher energy and asymmetric shape of PL bands was detected in PL spectra of bioconjugated QDs. The surface-enhanced Raman scattering effect was exhibited by the bioconjugated CdSeTe/ZnS QDs, indicating that the excitation light used in the Raman study generated electric dipoles in the AB molecules. The optical bandgap of the CdSeTe core was calculated numerically as a function of its radius based on an effective mass approximation model. The energy band diagrams for non- and bioconjugated CdSeTe/ZnS QDs were obtained, revealing a type II quantum well in the CdSeTe core. The calculations show that AB dipoles, excited in the bioconjugated QDs, stimulate a change in the energy band diagram of the QDs that alters the PL spectrum. These results could be useful for improving the sensitivity of QD biosensors.

Recyclable Cu(i)/melanin dots for cycloaddition, bioconjugation and cell labelling

DOE PAGES

Sun, Yao; Hong, Suhyun; Ma, Xiaowei; ...

2016-05-20

We successfully transferred melanin into a novel catalytic platform. Ligand-free, water-soluble, recyclable and biocompatible Cu(i)-loaded melanin dots [Cu(i)/M-dots] was easily prepared and demonstrate excellent properties for classic CuAAC, bioconjugation and cell labelling.

Recyclable Thermoresponsive Polymer-Cellulase Bioconjugates for Biomass Depolymerization

PubMed Central

Mackenzie, Katherine J.; Francis, Matthew B.

2013-01-01

Here we report the construction and characterization of a recoverable, thermoresponsive polymer-endoglucanase bioconjugate that matches the activity of unmodified enzymes on insoluble cellulose substrates. Two copolymers exhibiting a thermoresponsive lower critical solution temperature (LCST) were created through the copolymerization of an aminooxy-bearing methacrylamide with N-isopropylacrylamide (NIPAm) or N-isopropylmethacrylamide (NIPMa). The aminooxy group provided a handle through which the LCST was adjusted through small-molecule quenching. This allowed materials with LCSTs ranging from 20.9 °C to 60.5 °C to be readily obtained after polymerization. The thermostable endoglucanase EGPh from the hypothermophilic Pyrococcus horikoshii was transaminated with pyridoxal-5’-phosphate to produce a ketone-bearing protein, which was then site-selectively modified through oxime linkage with benzylalkoxyamine or 5 kDa-poly(ethylene glycol)-alkoxyamine. These modified proteins showed activity comparable to the controls when assayed on an insoluble cellulosic substrate. Two polymer bioconjugates were then constructed using transaminated EGPh and the aminooxy-bearing copolymers. After twelve hours, both bioconjugates produced an equivalent amount of free reducing sugars as the unmodified control using insoluble cellulose as a substrate. The recycling ability of the NIPAm copolymer-EGPh conjugate was determined through three rounds of activity, maintaining over 60% activity after two cycles of reuse and affording significantly more soluble carbohydrates than unmodified enzyme alone. When assayed on acid-pretreated Miscanthus, this bioconjugate increased the amount of reducing sugars by 2.8-fold over three rounds of activity. The synthetic strategy of this bioconjugate allows the LCST of the material to be changed readily from a common stock of copolymer and the method of attachment is applicable to a variety of proteins, enabling the same approach to be amenable to thermophile-derived cellulases or to the separation of multiple species using polymers with different recovery temperatures. PMID:23270527

Physical reasons of emission transformation in infrared CdSeTe/ZnS quantum dots at bioconjugation

NASA Astrophysics Data System (ADS)

Torchynska, T. V.

2015-04-01

The core/shell CdSeTe/ZnS quantum dots (QDs) with emission at 780-800 nm (1.55-1.60 eV) have been studied by means of photoluminescence (PL) and Raman scattering methods in the nonconjugated state and after conjugation to different antibodies (Ab): (i) mouse monoclonal [8C9] human papilloma virus Ab, anti-HPV 16-E7 Ab, (ii) mouse monoclonal [C1P5] human papilloma virus HPV16 E6+HPV18 E6 Ab, and (iii) pseudo rabies virus (PRV) Ab. The transformations of PL and Raman scattering spectra of QDs, stimulated by conjugated antibodies, have been revealed and discussed. The energy band diagram of core/shell CdSeTe/ZnS QDs has been designed that helps to analyze the PL spectra and their transformations at the bioconjugation. It is shown that the core in CdSeTe/ZnS QDs is complex and including the type II quantum well. The last fact permits to explain the nature of infrared (IR) optical transitions (1.55-1.60 eV) and the high energy PL band (1.88-1.94 eV) in the nonconjugated and bioconjugated QDs. A set of physical reasons has been analyzed with the aim to explain the transformation of PL spectra in bioconjugated QDs. Finally it is shown that two factors are responsible for the PL spectrum transformation at bioconjugation to charged antibodies: (i) the change of energy band profile in QDs and (ii) the shift of QD energy levels in the strong quantum confinement case. The effect of PL spectrum transformation is useful for the study of QD bioconjugation to specific antibodies and can be a powerful technique for early medical diagnostics.

In vitro degradation and antitumor activity of oxime bond-linked daunorubicin-GnRH-III bioconjugates and DNA-binding properties of daunorubicin-amino acid metabolites.

PubMed

Orbán, Erika; Mezo, Gábor; Schlage, Pascal; Csík, Gabriella; Kulić, Zarko; Ansorge, Philipp; Fellinger, Erzsébet; Möller, Heiko Michael; Manea, Marilena

2011-07-01

Bioconjugates with receptor-mediated tumor-targeting functions and carrying cytotoxic agents should enable the specific delivery of chemotherapeutics to malignant tissues, thus increasing their local efficacy while limiting the peripheral toxicity. In the present study, gonadotropin-releasing hormone III (GnRH-III; Glp-His-Trp-Ser-His-Asp-Trp-Lys-Pro-Gly-NH(2)) was employed as a targeting moiety to which daunorubicin was attached via oxime bond, either directly or by insertion of a GFLG or YRRL tetrapeptide spacer. The in vitro antitumor activity of the bioconjugates was determined on MCF-7 human breast and HT-29 human colon cancer cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Their degradation/stability (1) in human serum, (2) in the presence of cathepsin B and (3) in rat liver lysosomal homogenate was analyzed by liquid chromatography in combination with mass spectrometry. The results show that (1) all synthesized bioconjugates have in vitro antitumor effect, (2) they are stable in human serum at least for 24 h, except for the compound containing an YRRL spacer and (3) they are hydrolyzed by cathepsin B and in the lysosomal homogenate. To investigate the relationship between the in vitro antitumor activity and the structure of the bioconjugates, the smallest metabolites produced in the lysosomal homogenate were synthesized and their binding to DNA was assessed by fluorescence spectroscopy. Our data indicate that the incorporation of a peptide spacer in the structure of oxime bond-linked daunorubicin-GnRH-III bioconjugates is not required for their antitumor activity. Moreover, the antitumor activity is influenced by the structure of the metabolites (daunorubicin-amino acid derivatives) and their DNA-binding properties.

Dopamine and extinction: a convergence of theory with fear and reward circuitry.

PubMed

Abraham, Antony D; Neve, Kim A; Lattal, K Matthew

2014-02-01

Research on dopamine lies at the intersection of sophisticated theoretical and neurobiological approaches to learning and memory. Dopamine has been shown to be critical for many processes that drive learning and memory, including motivation, prediction error, incentive salience, memory consolidation, and response output. Theories of dopamine's function in these processes have, for the most part, been developed from behavioral approaches that examine learning mechanisms in reward-related tasks. A parallel and growing literature indicates that dopamine is involved in fear conditioning and extinction. These studies are consistent with long-standing ideas about appetitive-aversive interactions in learning theory and they speak to the general nature of cellular and molecular processes that underlie behavior. We review the behavioral and neurobiological literature showing a role for dopamine in fear conditioning and extinction. At a cellular level, we review dopamine signaling and receptor pharmacology, cellular and molecular events that follow dopamine receptor activation, and brain systems in which dopamine functions. At a behavioral level, we describe theories of learning and dopamine function that could describe the fundamental rules underlying how dopamine modulates different aspects of learning and memory processes. Copyright © 2013 Elsevier Inc. All rights reserved.

Bioconjugated nano-bactericidal complex for potent activity against human and phytopathogens with concern of global drug resistant crisis.

PubMed

Syed, Baker; Nagendra Prasad, M N; Mohan Kumar, K; Satish, S

2018-10-01

The present study emphasizes the need for novel antimicrobial agents to combat the global drug resistant crisis. The development of novel nanomaterials is reported to be of the alternative tool to combat drug resistant pathogens. In present investigation, bioconjugated nano-complex was developed from secondary metabolite secreted from endosymbiont. The endosymbiont capable of secreting antimicrobial metabolite was subjected to fermentation and the culture supernatant was assessed for purification of antimicrobial metabolite via bio-assay guided fraction techniques such as thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and column chromatography. The metabolite was characterized as 2,4-Diacetylphloroglucinol (2,4 DAPG) which was used to develop bioconjugated nano-complex by treating with 1 mM silver nitrate under optimized conditions. The purified metabolite 2,4 DAPG reduced silver nitrate to form bioconjugated nano-complex to form association with silver nanoparticles. The oxidized form of DAPG consists of four hard ligands that can conjugate on to the surface of silver nanoparticles cluster. The bioconjugation was confirmed with UV-visible spectroscopy which displayed the shift and shoulder peak in the absorbance spectra. This biomolecular interaction was further determined by the Fourier-transform spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analyses which displayed different signals ascertaining the molecular binding of 2,4,DAPG with silver nanoparticles. The transmission electron microscopy (TEM) analysis revealed the cluster formation due to bioconjugation. The XRD analysis revealed the crystalline nature of nano-complex with the characteristic peaks indexed to Bragg's reflection occurring at 2θ angle which indicated the (111), (200), (220) and (311) planes. The activity of bioconjugated nano-complex was tested against 12 significant human and phytopathogens. Among all the test pathogens, Shigella flexneri (MTCC 1457) was the most sensitive organisms with 38.33 ± 0.33 zone of inhibition. The results obtained in the present investigation attribute development of nano-complex as one of the effective tools against multi-drug resistant infections across the globe. Copyright © 2018 Elsevier B.V. All rights reserved.

A smart bioconjugate of alginate and pectinase with unusual biological activity toward chitosan.

PubMed

Sardar, Meryam; Roy, Ipsita; Gupta, Munishwar N

2003-01-01

The commercial preparation of pectinase (Pectinex Ultra SP-L) was conjugated to alginate by noncovalent interactions by employing 1% alginate during the conjugation protocol. The optimum "immobilization efficiency" was 0.76. The pH optimum and the thermal stability of the enzyme remained unchanged upon conjugation with alginate. The soluble bioconjugate showed a 3-fold increase in V(max)/K(m) as compared to the free enzyme when the smart biocatalyst was used for chitosan hydrolysis. Time course hydrolysis of chitosan thus showed higher conversion of chitosan into reducing oligosaccharides/sugars. The smart bioconjugate could be reused five times without any detectable loss of chitosanase activity.

Direct electrochemistry and electrocatalysis of a glucose oxidase-functionalized bioconjugate as a trace label for ultrasensitive detection of thrombin.

PubMed

Bai, Lijuan; Yuan, Ruo; Chai, Yaqin; Yuan, Yali; Wang, Yan; Xie, Shunbi

2012-11-18

For the first time, a glucose oxidase-functionalized bioconjugate was prepared and served as a new trace label through its direct electrochemistry and electrocatalysis in a sandwich-type electrochemical aptasensor for ultrasensitive detection of thrombin.

Dopamine and extinction: A convergence of theory with fear and reward circuitry

PubMed Central

Abraham, Antony D.; Neve, Kim A.; Lattal, K. Matthew

2014-01-01

Research on dopamine lies at the intersection of sophisticated theoretical and neurobiological approaches to learning and memory. Dopamine has been shown to be critical for many processes that drive learning and memory, including motivation, prediction error, incentive salience, memory consolidation, and response output. Theories of dopamine’s function in these processes have, for the most part, been developed from behavioral approaches that examine learning mechanisms in reward-related tasks. A parallel and growing literature indicates that dopamine is involved in fear conditioning and extinction. These studies are consistent with long-standing ideas about appetitive-aversive interactions in learning theory and they speak to the general nature of cellular and molecular processes that underlie behavior. We review the behavioral and neurobiological literature showing a role for dopamine in fear conditioning and extinction. At a cellular level, we review dopamine signaling and receptor pharmacology, cellular and molecular events that follow dopamine receptor activation, and brain systems in which dopamine functions. At a behavioral level, we describe theories of learning and dopamine function that could describe the fundamental rules underlying how dopamine modulates different aspects of learning and memory processes. PMID:24269353

Maize rayado fino virus-like particles expressed in tobacco plants: a new platform for cysteine selective bioconjugation peptide display

USDA-ARS?s Scientific Manuscript database

The ability of plant virus coat proteins to self-assemble into virus-like particles (VLPs), coupled with unique properties including three-dimensional structures, orthogonal reactivities, suitability for genetic manipulation and chemical bio-conjugation, provide potential utility in nanotechnology a...

Design, Synthesis, and Evaluation of N- and C-Terminal Protein Bioconjugates as G Protein-Coupled Receptor Agonists.

PubMed

Healey, Robert D; Wojciechowski, Jonathan P; Monserrat-Martinez, Ana; Tan, Susan L; Marquis, Christopher P; Sierecki, Emma; Gambin, Yann; Finch, Angela M; Thordarson, Pall

2018-02-21

A G protein-coupled receptor (GPCR) agonist protein, thaumatin, was site-specifically conjugated at the N- or C-terminus with a fluorophore for visualization of GPCR:agonist interactions. The N-terminus was specifically conjugated using a synthetic 2-pyridinecarboxyaldehyde reagent. The interaction profiles observed for N- and C-terminal conjugates were varied; N-terminal conjugates interacted very weakly with the GPCR of interest, whereas C-terminal conjugates bound to the receptor. These chemical biology tools allow interactions of therapeutic proteins:GPCR to be monitored and visualized. The methodology used for site-specific bioconjugation represents an advance in application of 2-pyridinecarboxyaldehydes for N-terminal specific bioconjugations.

Biological sensing and control of emission dynamics of quantum dot bioconjugates using arrays of long metallic nanorods.

PubMed

Sadeghi, Seyed M; Gutha, Rithvik R; Wing, Waylin J; Sharp, Christina; Capps, Lucas; Mao, Chuanbin

2017-01-01

We study biological sensing using plasmonic and photonic-plasmonic resonances of arrays of ultralong metallic nanorods and analyze the impact of these resonances on emission dynamics of quantum dot bioconjugates. We demonstrate that the LSPRs and plasmonic lattice modes of such array can be used to detect a single self-assembled monolayer of alkanethiol at the visible (550 nm) and near infrared (770 nm) range with well resolved shifts. We study adsorption of streptavidin-quantum dot conjugates to this monolayer, demonstrating that formation of nearly two dimensional arrays of quantum dots with limited emission blinking can lead to extra well-defined wavelength shifts in these modes. Using spectrally-resolved lifetime measurements we study the emission dynamics of such quantum dot bioconjugates within their monodispersed size distribution. We show that, despite their close vicinity to the nanorods, the rate of energy transfer from these quantum dots to nanorods is rather weak, while the plasmon field enhancement can be strong. Our results reveal that the nanorods present a strongly wavelength or size-dependent non-radiative decay channel to the quantum dot bioconjugates.

Semiconductor nanocrystal-aptamer bioconjugate probes for specific prostate carcinoma cell targeting

NASA Astrophysics Data System (ADS)

Shieh, Felice; Lavery, Laura; Chu, Chitai T.; Richards-Kortum, Rebecca; Ellington, Andrew D.; Korgel, Brian A.

2005-04-01

Cancer of the prostate affects approximately 1 in 11 men. Current early screening for prostate cancer utilizes digital rectal examinations to detect anomalies in the prostate gland and blood test screenings for upregulated levels of prostate specific antigen (PSA). Many of these tests are invasive and can often be inconclusive as PSA levels may be heightened due to benign factors. Prostate specific membrane antigen (PSMA), a well-characterized integral membrane protein, is expressed in virtually all prostate cancers and often correlates with cancer aggressiveness. Therefore, it may be used as an indicator of cancer growth and metastases. PSMA-specific antibodies have been identified and conjugated to fluorescent markers for cancer cell targeting; however, both the antibodies and markers possess significant limitations in their pharmaceutical and diagnostic value. Here we report the use of semiconductor nanocrystals bioconjugated to PSMA-specific aptamer recognition molecules for prostate carcinoma cell targeting. The nanocrystal/aptamer bioconjugates are small biocompatible probes with the potential for color-tunability for multicolor imaging. Ongoing in vitro and in vivo research seeks to introduce these nanoparticle bioconjugates into medical diagnostics.

Cytochrome P450 Bioconjugate as a Nanovehicle for Improved Chemotherapy Treatment.

PubMed

Quester, Katrin; Juarez-Moreno, Karla; Secundino, Isamel; Roseinstein, Yvonne; Alejo, Karla P; Huerta-Saquero, Alejandro; Vazquez-Duhalt, Rafael

2017-05-01

Cancer is still a growing public health problem, especially breast cancer that is one of the most important cancers in women. Chemotherapy, even though a successful treatment, is accompanied by severe side effects. Moreover, most of the drugs used for chemotherapy are administered as prodrugs and need to be transformed to the active form by cytochromes P450 (CYPs). In addition, increasing numbers of cancer tissues show lower CYP activity than the surrounding healthy tissues in which prodrugs are preferentially activated causing cytotoxicity. Here, the design of a functionalized cytochrome P450 bioconjugate is reported as nanovehicle for the enzyme direct delivery to the tumor tissue in order to improve the local drug activation. MCF-7 breast cancer cells are treated with CYP-polyethylene glycol bioconjugate functionalized folic acid, where it activates the prodrug tamoxifen and significantly reduces the dose of tamoxifen needed to kill the tumor cells. The CYP bioconjugate covered with polyethylene glycol shows no immunogenic activity. The advantages of increasing the site-specific CYP activity in tumor tissues are discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Site-Specifically Labeled Immunoconjugates for Molecular Imaging--Part 2: Peptide Tags and Unnatural Amino Acids.

PubMed

Adumeau, Pierre; Sharma, Sai Kiran; Brent, Colleen; Zeglis, Brian M

2016-04-01

Molecular imaging using radioisotope- or fluorophore-labeled antibodies is increasingly becoming a critical component of modern precision medicine. Yet despite this promise, the vast majority of these immunoconjugates are synthesized via the random coupling of amine-reactive bifunctional probes to lysines within the antibody, a process that can result in heterogeneous and poorly defined constructs with suboptimal pharmacological properties. In an effort to circumvent these issues, the last 5 years have played witness to a great deal of research focused on the creation of effective strategies for the site-specific attachment of payloads to antibodies. These chemoselective modification methods yield immunoconjugates that are more homogenous and better defined than constructs created using traditional synthetic approaches. Moreover, site-specifically labeled immunoconjugates have also been shown to exhibit superior in vivo behavior compared to their randomly modified cousins. The over-arching goal of this two-part review is to provide a broad yet detailed account of the various site-specific bioconjugation approaches that have been used to create immunoconjugates for positron emission tomography (PET), single photon emission computed tomography (SPECT), and fluorescence imaging. In Part 1, we covered site-specific bioconjugation techniques based on the modification of cysteine residues and the chemoenzymatic manipulation of glycans. In Part 2, we will detail two families of bioconjugation approaches that leverage biochemical tools to achieve site-specificity. First, we will discuss modification methods that employ peptide tags either as sites for enzyme-catalyzed ligations or as radiometal coordination architectures. And second, we will examine bioconjugation strategies predicated on the incorporation of unnatural or non-canonical amino acids into antibodies via genetic engineering. Finally, we will compare the advantages and disadvantages of the modification strategies covered in both parts of the review and offer a brief discussion of the overall direction of the field.

Patterning poly(maleic anhydride-co-3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5) undecane) copolymer bioconjugates for controlled release of drugs.

PubMed

Nita, Loredana E; Chiriac, Aurica P; Mititelu-Tartau, Liliana; Stoleru, Elena; Doroftei, Florica; Diaconu, Alina

2015-09-30

Owing to the special characteristics and abilities polymeric networks have received special interest for a range of biomedical applications especially for drug delivery systems. This study was devoted to preparation of new polymeric compounds based on maleic anhydride and 3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5) undecane copolymer (poly maleic anhydride-co-3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5) undecane) (PMAU) patterned as a network for bioconjugation and tested as drug carrier systems. The PMAU copolymer was improved in its functionality by opening the maleic anhydride ring with different amounts of erythritol, which is free of side effects in regular use and a multifunctional compound, and also confers antioxidant character for the new compounds. The new polymeric matrices were loaded with acetaminophen, codeine and their fixed dose combinations. The investigation demonstrated the capability of the new structures to be used as polymer networks for linking bioactive compounds and to perform controlled delivery. The physico-chemical investigations--Fourier transform infrared spectroscopy (FTIR) spectra, contact angle, zeta potential (ZP - z, PMAU and its derivatives samples loaded with medicines present decreased values of zeta potential attesting the bioconjugate formation and as well their stability), and hydrodynamic radius, near infrared chemical imaging evaluation (new specific bands being registered for bio-conjugate with acetaminophen around of 1150-1200 nm and 1700 nm, and also between 1150 and 1200 nm in case of the codeine bio-conjugate), scanning electron microscopy (SEM) studies, X-ray diffraction analysis--evidenced the formation of the bioconjugates in relation to the chemical composition of the polymer matrices, while in vitro release study and in vivo tests confirm the capacity for drug delivery of the prepared bioactive systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Multicomponent Reactions in Ligation and Bioconjugation Chemistry.

PubMed

Reguera, Leslie; Méndez, Yanira; Humpierre, Ana R; Valdés, Oscar; Rivera, Daniel G

2018-05-25

Multicomponent reactions (MCRs) encompass an exciting class of chemical transformations that have proven success in almost all fields of synthetic organic chemistry. These convergent procedures incorporate three or more reactants into a final product in one pot, thus combining high levels of complexity and diversity generation with low synthetic cost. Striking applications of these processes are found in heterocycle, peptidomimetic, and natural product syntheses. However, their potential in the preparation of large macro- and biomolecular constructs has been realized just recently. This Account describes the most relevant results of our group in the utilization of MCRs for ligation/conjugation of biomolecules along with significant contributions from other laboratories that validate the utility of this special class of bioconjugation process. Thus, MCRs have proven to be efficient in the ligation of lipids to peptides and oligosaccharides as well as the ligation of steroids, carbohydrates, and fluorescent and affinity tags to peptides and proteins. In the field of glycolipids, we highlight the power of isocyanide-based MCRs with the one-pot double lipidation of glycan fragments functionalized as either the carboxylic acid or amine. In peptide chemistry, the versatility of the multicomponent ligation strategy is demonstrated in both solution-phase lipidation protocols and solid-phase procedures enabling the simultaneous lipidation and biotinylation of peptides. In addition, we show that MCRs are powerful methods for synchronized lipidation/labeling and macrocyclization of peptides, thus accomplishing in one step what usually requires long sequences. In the realm of protein bioconjugation, MCRs have also proven to be effective in labeling, site-selective modification, immobilization, and glycoconjugation processes. For example, we illustrate a successful application of multicomponent polysaccharide-protein conjugation with the preparation of multivalent glycoconjugate vaccine candidates by the ligation of two antigenic capsular polysaccharides of a pathogenic bacterium to carrier proteins. By highlighting the ability to join several biomolecules in only one synthetic operation, we hope to encourage the biomolecular chemistry community to apply this powerful chemistry to novel biomedicinal challenges.

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

Improved in vivo antitumor effect of a daunorubicin - GnRH-III bioconjugate modified by apoptosis inducing agent butyric acid on colorectal carcinoma bearing mice.

PubMed

Kapuvári, Bence; Hegedüs, Rózsa; Schulcz, Ákos; Manea, Marilena; Tóvári, József; Gacs, Alexandra; Vincze, Borbála; Mező, Gábor

2016-08-01

Compared to classical chemotherapy, peptide-based drug targeting is a promising therapeutic approach for cancer, which can provide increased selectivity and decreased side effects to anticancer drugs. Among various homing devices, gonadotropin-releasing hormone-III (GnRH-III) peptide represents a suitable targeting moiety, in particular in the treatment of hormone independent tumors that highly express GnRH receptors (e.g. colon carcinoma). We have previously shown that GnRH-III[(4)Lys(Ac),(8)Lys(Dau = Aoa)] bioconjugate, in which daunorubicin was attached via oxime linkage to the (8)Lys of a GnRH-III derivative, exerted significant in vivo antitumor effect on subcutaneously developed HT-29 colon tumor. In contrast, results of the study reported here indicated that this compound was not active on an orthotopically developed tumor. However, if Lys in position 4 was acylated with butyric acid instead of acetic acid, the resulting bioconjugate GnRH-III[(4)Lys(Bu),(8)Lys(Dau = Aoa)] had significant tumor growth inhibitory effect. Furthermore, it prevented tumor neovascularization, without detectable side effects. Nevertheless, the development of metastases could not be inhibited by the bioconjugate; therefore, its application in combination with a metastasis preventive agent might be necessary in order to achieve complete tumor remission. In spite of this result, the treatment with GnRH-III[(4)Lys(Bu),(8)Lys(Dau = Aoa)] bioconjugate proved to have significant benefits over the administration of free daunorubicin, which was used at the maximum tolerated dose.

Dopamine dynamics during emotional cognitive processing: Implications of the specific actions of clozapine compared with haloperidol.

PubMed

Kawano, Masahiko; Oshibuchi, Hidehiro; Kawano, Takaaki; Muraoka, Hiroyuki; Tsutsumi, Takahiro; Yamada, Makiko; Inada, Ken; Ishigooka, Jun

2016-06-15

Clozapine has improved efficacy relative to typical antipsychotics in schizophrenia treatment, particularly regarding emotional symptoms. However, the mechanisms underlying its therapeutic benefits remain unclear. Using a methamphetamine-sensitised rat model, we measured changes in dopamine levels in the amygdalae in response to a fear-conditioned cue, serving as a biochemical marker of emotional cognitive processing disruption in psychosis, for analysing the biochemical mechanisms associated with the clinical benefits of clozapine. We also compared how clozapine and haloperidol affected basal dopamine levels and phasic dopamine release in response to the fear-conditioned cue. Extracellular dopamine was collected from the amygdalae of freely moving rats via microdialysis and was analysed by high-performance liquid chromatography. Clozapine or haloperidol was injected during microdialysis, followed by exposure to the fear-conditioned cue. We analysed the ratio of change in dopamine levels from baseline. Haloperidol treatment increased the baseline dopamine levels in both non-sensitised and sensitised rats. Conversely, clozapine only increased the basal dopamine levels in the non-sensitised rats, but not in the sensitised rats. Although both antipsychotics attenuated phasic dopamine release in both the non-sensitised and sensitised rats, the attenuation extent was greater for clozapine than for haloperidol under both dopaminergic conditions. Our findings indicate that stabilized dopamine release in the amygdalae is a common therapeutic mechanism of antipsychotic action during emotional processing. However, the specific dopaminergic state-dependent action of clozapine on both basal dopamine levels and stress-induced dopamine release may be the underlying mechanism for its superior clinical effect on emotional cognitive processing in patients with schizophrenia. Copyright © 2016 Elsevier B.V. All rights reserved.

Amine-selective bioconjugation using arene diazonium salts.

PubMed

Diethelm, Stefan; Schafroth, Michael A; Carreira, Erick M

2014-08-01

A novel bioconjugation strategy is presented that relies on the coupling of diazonium terephthalates with amines in proteins. The diazonium captures the amine while the vicinal ester locks it through cyclization, ensuring no reversibility. The reaction is highly efficient and proceeds under mild conditions and short reaction times. Densely functionalized, complex natural products were directly coupled to proteins using low concentrations of coupling partners.

Focus on quantum dots as potential fluorescent probes for monitoring food toxicants and foodborne pathogens.

PubMed

Vinayaka, A C; Thakur, M S

2010-06-01

Water-soluble quantum dots (QDs) are fluorescent semiconductor nanoparticles with narrow, very specific, stable emission spectra. Therefore, the bioconjugation of these QDs for biological fluorescent labeling may be of interest due to their unique physical and optical properties as compared to organic fluorescent dyes. These intrinsic properties of QDs have been used for the sensitive detection of target analytes. From the viewpoint of ensuring food safety, there is a need to develop rapid, sensitive and specific detection techniques to monitor food toxicants in food and environmental samples. Even trace levels of these toxicants can inadvertently enter the food chain, creating severe health hazards. The present review emphasizes the application of water-soluble bioconjugated QDs for the detection of food contaminants such as pesticides, pathogenic bacterial toxins such as botulinum toxin, enterotoxins produced by Staphylococcus aureus, Escherichia coli, and for the development of oligonucleotide-based microarrays. This review also emphasizes the application of a possible resonance energy transfer phenomenon resulting from nanobiomolecular interactions obtained through the bioconjugation of QDs with biomolecules. Furthermore, the utilization of significant changes in the spectral behavior of QDs (attributed to resonance energy transfer in the bioconjugate) in future nanobiosensor development is also emphasized.

Preparation and functionalization of graphene nanocomposites for biomedical applications

PubMed Central

Yang, Kai; Feng, Liangzhu; Hong, Hao; Cai, Weibo; Liu, Zhuang

2013-01-01

Functionalized nano-graphene– and graphene-based nanocomposites have gained tremendous attention in the area of biomedicine in recent years owing to their biocompatibility, the ease with which they can be functionalized and their properties such as thermal and electrical conductivity. potential applications for functionalized nanoparticles range from drug delivery and multimodal imaging to exploitation of the electrical properties of graphene toward the preparation of biosensing devices. this protocol covers the preparation, functionalization and bioconjugation of various graphene derivatives and nanocomposites. starting from graphite, the preparations of graphene oxide (GO), reduced GO (RGO) and magnetic GO–based nanocomposite, as well as how to functionalize them with biocompatible polymers such as polyethylene glycol (PEG), are described in detail. We also provide procedures for 125I radiolabeling of PEGylated GO and the preparation of GO-based gene carriers; other bioconjugation approaches including drug loading, antibody conjugation and fluorescent labeling are similar to those described previously and used for bioconjugation of PEGylated carbon nanotubes. We hope this article will help researchers in this field to fabricate graphene-based bioconjugates with high reproducibility for various applications in biomedicine. the sample preparation procedures take various times ranging from 1 to 2 d. PMID:24202553

Olfactory discrimination deficits in mice lacking the dopamine transporter or the D2 dopamine receptor.

PubMed

Tillerson, Jennifer L; Caudle, W Michael; Parent, Jack M; Gong, C; Schallert, Timothy; Miller, Gary W

2006-09-15

Previous pharmacological studies have implicated dopamine as a modulator of olfactory bulb processing. Several disorders characterized by altered dopamine homeostasis in olfaction-related brain regions display olfactory deficits. To further characterize the role of dopamine in olfactory processing, we subjected dopamine transporter knockout mice (DAT -/-) and dopamine receptor 2 knockout mice (D2 -/-) to a battery of olfactory tests. In addition to behavioral characterization, several neurochemical markers of olfactory bulb integrity and function were examined. DAT -/- mice displayed an olfactory discrimination deficit, but did not differ detectably from DAT wildtype (DAT +/+) mice in odor habituation, olfactory sensitivity, or odor recognition memory. Neurochemically, DAT -/- mice have decreased D2 receptor staining in the periglomerular layer of the olfactory bulb and increased tyrosine hydroxylase immunoreactivity compared to DAT +/+ controls. D2 -/- mice exhibited the same olfactory deficit as the DAT -/- mice, further supporting the role of dopamine at the D2 synapse in olfactory discrimination processing. The findings presented in this paper reinforce the functional significance of dopamine and more specifically the D2 receptor in olfactory discrimination and may help explain the behavioral phenotype in the DAT and D2 knockout mice.

Site-Specific Biomolecule Labeling with Gold Clusters

PubMed Central

Ackerson, Christopher J.; Powell, Richard D.; Hainfeld, James F.

2013-01-01

Site-specific labeling of biomolecules in vitro with gold clusters can enhance the information content of electron cryomicroscopy experiments. This chapter provides a practical overview of well-established techniques for forming biomolecule/gold cluster conjugates. Three bioconjugation chemistries are covered: Linker-mediated bioconjugation, direct gold–biomolecule bonding, and coordination-mediated bonding of nickel(II) nitrilotriacetic acid (NTA)-derivatized gold clusters to polyhistidine (His)-tagged proteins. PMID:20887859

Preparation of clinical-grade 89Zr-panitumumab as a positron emission tomography biomarker for evaluating epidermal growth factor receptor-targeted therapy

PubMed Central

Wei, Ling; Shi, Jianfeng; Afari, George; Bhattacharyya, Sibaprasad

2014-01-01

Panitumumab is a fully human monoclonal antibody approved for the treatment of epidermal growth factor receptor (EGFR) positive colorectal cancer. Recently, panitumumab has been radiolabeled with 89Zr and evaluated for its potential to be used as immuno-positron emission tomography (PET) probe for EGFR positive cancers. Interesting preclinical results published by several groups of researchers have prompted us to develop a robust procedure for producing clinical-grade 89Zr-panitumumab as an immuno-PET probe to evaluate EGFR-targeted therapy. In this process, clinical-grade panitumumab is bio-conjugated with desferrioxamine chelate and subsequently radiolabeled with 89Zr resulting in high radiochemical yield (>70%, n=3) and purity (>98%, n=3). All quality control (QC) tests were performed according to United States Pharmacopeia specifications. QC tests showed that 89Zr-panitumumab met all specifications for human injection. Herein, we describe a step-by-step method for the facile synthesis and QC tests of 89Zr-panitumumab for medical use. The entire process of bioconjugation, radiolabeling, and all QC tests will take about 5h. Because the synthesis is fully manual, two rapid, in-process QC tests have been introduced to make the procedure robust and error free. PMID:24448743

Glycosylation site-targeted PEGylation of glucose oxidase retains native enzymatic activity.

PubMed

Ritter, Dustin W; Roberts, Jason R; McShane, Michael J

2013-04-10

Targeted PEGylation of glucose oxidase at its glycosylation sites was investigated to determine the effect on enzymatic activity, as well as the bioconjugate's potential in an optical biosensing assay. Methoxy-poly(ethylene glycol)-hydrazide (4.5kDa) was covalently coupled to periodate-oxidized glycosylation sites of glucose oxidase from Aspergillus niger. The bioconjugate was characterized using gel electrophoresis, liquid chromatography, mass spectrometry, and dynamic light scattering. Gel electrophoresis data showed that the PEGylation protocol resulted in a drastic increase (ca. 100kDa) in the apparent molecular mass of the protein subunit, with complete conversion to the bioconjugate; liquid chromatography data corroborated this large increase in molecular size. Mass spectrometry data proved that the extent of PEGylation was six poly(ethylene glycol) chains per glucose oxidase dimer. Dynamic light scattering data indicated the absence of higher-order oligomers in the PEGylated GOx sample. To assess stability, enzymatic activity assays were performed in triplicate at multiple time points over the course of 29 days in the absence of glucose, as well as before and after exposure to 5% w/v glucose for 24h. At a confidence level of 95%, the bioconjugate's performance was statistically equivalent to native glucose oxidase in terms of activity retention over the 29 day time period, as well as following the 24h glucose exposure. Finally, the bioconjugate was entrapped within a poly(2-hydroxyethyl methacrylate) hydrogel containing an oxygen-sensitive phosphor, and the construct was shown to respond approximately linearly with a 220±73% signal change (n=4, 95% confidence interval) over the physiologically-relevant glucose range (i.e., 0-400mg/dL); to our knowledge, this represents the first demonstration of PEGylated glucose oxidase incorporated into an optical biosensing assay. Copyright © 2013 Elsevier Inc. All rights reserved.

Nanozeolite bioconjugates labeled with 223Ra for targeted alpha therapy.

PubMed

Piotrowska, Agata; Męczyńska-Wielgosz, Sylwia; Majkowska-Pilip, Agnieszka; Koźmiński, Przemysław; Wójciuk, Grzegorz; Cędrowska, Edyta; Bruchertseifer, Frank; Morgenstern, Alfred; Kruszewski, Marcin; Bilewicz, Aleksander

2017-04-01

Alpha particle emitting isotopes are of considerable interest for radionuclide therapy because of their high cytotoxicity and short path length. Among the many α emitters, 223 Ra exhibits very attractive nuclear properties for application in radionuclide therapy. The decay of this radioisotope and its daughters is accompanied by the emission of four α-particles, releasing 27.9MeV of cumulative energy. Unfortunately the lack of an appropriate bifunctional ligand for radium has so far been a main obstacle for the application of 223 Ra in receptor targeted therapy. In our studies we investigated the use of nanozeolite-Substance P bioconjugates as vehicles for 223 Ra radionuclides for targeted α therapy. The sodium form of an A-type of nanozeolite (NaA) was synthesized using the template method. Next, the nanozeolite particles were conjugated to the Substance P (5-11) peptide fragment, which targets NK-1 receptors on glioma cells. The obtained bioconjugate was characterized by transmission emission spectroscopy, thermogravimetric analysis and dynamic light scattering analysis. The NaA-silane-PEG-SP(5-11) bioconjugates were labeled with 223 Ra by exchange of the Na + cation and the stability, receptor affinity and cytotoxicity of the obtained radiobioconjugates were tested. The 223 Ra-labeled nanozeolite bioconjugate almost quantitatively retains 223 Ra in vitro after 6days, while the retention of decay products varies from 90 to 95%. The synthesized 223 RaA-silane-PEG-SP(5-11) showed high receptor affinity toward NK-1 receptor expressing glioma cells and exhibited a high cytotoxic effect in vitro. Substance P functionalized nanozeolite-A represents a viable solution for the use of the 223 Ra in vivo generator as a therapeutic construct for targeting glioma cells. Copyright © 2016 Elsevier Inc. All rights reserved.

The role of dopamine in human addiction: from reward to motivated attention.

PubMed

Franken, Ingmar H A; Booij, Jan; van den Brink, Wim

2005-12-05

There is general consensus among preclinical researchers that dopamine plays an important role in the development and persistence of addiction. However, the precise role of dopamine in addictive behaviors is far from clear and only a few clinical studies on the role of dopamine in human addiction have been conducted so far. The present paper reviews studies addressing the role of dopamine in humans. There is substantial and consistent evidence that dopamine is involved in the experience of drug reward in humans. Dopamine may also be involved in motivational processes such as drug craving. However, given the inconsistent findings of studies using dopamine receptor (ant)agonists, the role of dopamine in the experience of craving is far from resolved. Recent theories claiming that dopamine signals salience and makes the brain paying attention to biological relevant stimuli may provide an interesting framework for explaining addictive behaviors. There is accumulating evidence that patients with drug and alcohol addiction have an aberrant focus on drug-related stimuli. Although there is some preliminary support for the role of dopamine in these attention processes, more studies have to be carried out in order to test the validity of these theories in human subjects.

Molecule-specific darkfield and multiphoton imaging using gold nanocages

NASA Astrophysics Data System (ADS)

Powless, Amy J.; Jenkins, Samir V.; McKay, Mary Lee; Chen, Jingyi; Muldoon, Timothy J.

2015-03-01

Due to their robust optical properties, biological inertness, and readily adjustable surface chemistry, gold nanostructures have been demonstrated as contrast agents in a variety of biomedical imaging applications. One application is dynamic imaging of live cells using bioconjugated gold nanoparticles to monitor molecule trafficking mechanisms within cells; for instance, the regulatory pathway of epidermal growth factor receptor (EGFR) undergoing endocytosis. In this paper, we have demonstrated a method to track endocytosis of EGFR in MDA-MB-468 breast adenocarcinoma cells using bioconjugated gold nanocages (AuNCs) and multiphoton microscopy. Dynamic imaging was performed using a time series capture of 4 images every minute for one hour. Specific binding and internalization of the bioconjugated AuNCs was observed while the two control groups showed non-specific binding at fewer surface sites, leading to fewer bound AuNCs and no internalization.

In vivo molecular photoacoustic tomography of melanomas targeted by bioconjugated gold nanocages.

PubMed

Kim, Chulhong; Cho, Eun Chul; Chen, Jingyi; Song, Kwang Hyun; Au, Leslie; Favazza, Christopher; Zhang, Qiang; Cobley, Claire M; Gao, Feng; Xia, Younan; Wang, Lihong V

2010-08-24

Early diagnosis, accurate staging, and image-guided resection of melanomas remain crucial clinical objectives for improving patient survival and treatment outcomes. Conventional techniques cannot meet this demand because of the low sensitivity, low specificity, poor spatial resolution, shallow penetration, and/or ionizing radiation. Here we overcome such limitations by combining high-resolution photoacoustic tomography (PAT) with extraordinarily optical absorbing gold nanocages (AuNCs). When bioconjugated with [Nle(4),D-Phe(7)]-alpha-melanocyte-stimulating hormone, the AuNCs can serve as a novel contrast agent for in vivo molecular PAT of melanomas with both exquisite sensitivity and high specificity. The bioconjugated AuNCs enhanced contrast approximately 300% more than the control, PEGylated AuNCs. The in vivo PAT quantification of the amount of AuNCs accumulated in melanomas was further validated with inductively coupled plasma mass spectrometry (ICP-MS).

Improvement of the stability and activity of immobilized glucose oxidase on modified iron oxide magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Abbasi, Mahboube; Amiri, Razieh; Bordbar, Abdol-Kalegh; Ranjbakhsh, Elnaz; Khosropour, Ahmad-Reza

2016-02-01

Immobilized proteins and enzymes are widely investigated in the medical field as well as the food and environmental fields. In this study, glucose oxidase (GOX) was covalently immobilized on the surface of modified iron oxide magnetic nanoparticles (MIMNs) to produce a bioconjugate complex. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to the size, shape and structure characterization of the MIMNs. Binding of GOX to these MIMNs was confirmed by using FT-IR spectroscopy. The stability of the immobilized and free enzyme at different temperature and pH values was investigated by measuring the enzymatic activity. These studies reveal that the enzyme's stability is enhanced by immobilization. Further experiments showed that the storage stability of the enzyme is improved upon binding to the MIMNs. The results of kinetic measurements suggest that the effect of the immobilization process on substrate and product diffusion is small. Such bioconjugates can be considered as a catalytic nanodevice for accelerating the glucose oxidation reaction for biotechnological purposes.

A potential targeting gene vector based on biotinylated polyethyleneimine/avidin bioconjugates.

PubMed

Zeng, Xuan; Sun, Yun-Xia; Zhang, Xian-Zheng; Cheng, Si-Xue; Zhuo, Ren-Xi

2009-08-01

To improve the gene delivery efficiency and safety of non-viral vector in liver cells, avidin, which exhibited good biocompatibility and remarkable accumulation in liver, was bioconjugated with biotinylated polyethylenimine to obtain a novel gene vector. Biotinylated polyethyleneimine/avidin bioconjugate (ABP) was synthesized through grafting biotin to high molecular weight branched polyethylenimine (PEI, 25 kDa) and then bioconjugating with avidin by the biotin-avidin interaction. Physiochemical characteristics of ABP/pDNA complexes were analyzed, and in vitro cytotoxicity and transfection of ABP were also evaluated in HepG2, Hela and 293 T cells by using 25 kDa PEI as the control. It was found that ABP was able to condense pDNA efficiently at N/P ratio of 4. The particle sizes of ABP/pDNA complexes were less than 220 nm, and the average surface charges were around 27 mV at the N/P ratio ranging from 2 to 60. Among three different cell lines, ABP and its DNA complexes demonstrated much lower cytotoxicity and higher transfection efficacy in HepG2 cells as compared with 25 kDa PEI. ABP presented higher transfection efficacy and safety in HepG2 cells due to the biocompatibility of avidin and the specific interactions between avidin and HepG2 cells.

Mono-Amine Functionalized Phthalocyanines: Mwave-Assisted Solid-Phase Synthesis and Bioconjugation Strategies

PubMed Central

Erdem, S. Sibel; Nesterova, Irina V.; Soper, Steven A.; Hammer, Robert P.

2009-01-01

Phthalocyanines (Pcs) are excellent candidates for use as fluors for near-infrared (near-IR) fluorescent tagging of biomolecules for a wide variety of bioanalytical applications. Mono-functionalized Pcs, having two different types of peripheral substitutents; one for covalent conjugation of the Pc to biomolecules and others to improve the solubility of the macrocycle, ideally suit for the desired applications. To date, difficulties faced during the purification of the mono-functionalized Pcs limited their usage in various types of applications. Herein are reported a new synthetic method for rapid synthesis of the target Pcs and bioconjugation techniques for labeling of the oligonucleotides with the near-IR flours. A novel synthetic route was developed utilizing a hydrophilic, polyethylene glycol-based (PEG) support with an acid labile Rink Amide linker. The Pcs were functionalized with an amine group for covalent conjugation purposes and were decorated with short PEG chains, serving as solubilizing groups. Mwave-assisted solid-phase synthetic method was successfully applied to obtain pure asymmetrically-substituted mono-amine functionalized Pcs in a short period of time. Three different bioconjugation techniques, reductive amination, amidation and Huisgen cycloaddition, were employed for covalent conjugation of Pcs to oligonucleotides. The described μwave-assisted bioconjugation methods give an opportunity to synthesize and isolate the Pc-oligonucleotide conjugate in a few hours. PMID:19911767

Development of Efficient Chemistry to Generate Site-Specific Disulfide-Linked Protein- and Peptide-Payload Conjugates: Application to THIOMAB Antibody-Drug Conjugates.

PubMed

Sadowsky, Jack D; Pillow, Thomas H; Chen, Jinhua; Fan, Fang; He, Changrong; Wang, Yanli; Yan, Gang; Yao, Hui; Xu, Zijin; Martin, Shanique; Zhang, Donglu; Chu, Phillip; Dela Cruz-Chuh, Josefa; O'Donohue, Aimee; Li, Guangmin; Del Rosario, Geoffrey; He, Jintang; Liu, Luna; Ng, Carl; Su, Dian; Lewis Phillips, Gail D; Kozak, Katherine R; Yu, Shang-Fan; Xu, Keyang; Leipold, Douglas; Wai, John

2017-08-16

Conjugation of small molecule payloads to cysteine residues on proteins via a disulfide bond represents an attractive strategy to generate redox-sensitive bioconjugates, which have value as potential diagnostic reagents or therapeutics. Advancement of such "direct-disulfide" bioconjugates to the clinic necessitates chemical methods to form disulfide connections efficiently, without byproducts. The disulfide connection must also be resistant to premature cleavage by thiols prior to arrival at the targeted tissue. We show here that commonly employed methods to generate direct disulfide-linked bioconjugates are inadequate for addressing these challenges. We describe our efforts to optimize direct-disulfide conjugation chemistry, focusing on the generation of conjugates between cytotoxic payloads and cysteine-engineered antibodies (i.e., THIOMAB antibody-drug conjugates, or TDCs). This work culminates in the development of novel, high-yielding conjugation chemistry for creating direct payload disulfide connections to any of several Cys mutation sites in THIOMAB antibodies or to Cys sites in other biomolecules (e.g., human serum albumin and cell-penetrating peptides). We conclude by demonstrating that hindered direct disulfide TDCs with two methyl groups adjacent to the disulfide, which have heretofore not been described for any bioconjugate, are more stable and more efficacious in mouse tumor xenograft studies than less hindered analogs.

Chemical modifications and bioconjugate reactions of nanomaterials for sensing, imaging, drug delivery and therapy.

PubMed

Biju, Vasudevanpillai

2014-02-07

As prepared nanomaterials of metals, semiconductors, polymers and carbon often need surface modifications such as ligand exchange, and chemical and bioconjugate reactions for various biosensor, bioanalytical, bioimaging, drug delivery and therapeutic applications. Such surface modifications help us to control the physico-chemical, toxicological and pharmacological properties of nanomaterials. Furthermore, introduction of various reactive functional groups on the surface of nanomaterials allows us to conjugate a spectrum of contrast agents, antibodies, peptides, ligands, drugs and genes, and construct multifunctional and hybrid nanomaterials for the targeted imaging and treatment of cancers. This tutorial review is intended to provide an introduction to newcomers about how chemical and bioconjugate reactions transform the surface of nanomaterials such as silica nanoparticles, gold nanoparticles, gold quantum clusters, semiconductor quantum dots, carbon nanotubes, fullerene and graphene, and accordingly formulate them for applications such as biosensing, bioimaging, drug and gene delivery, chemotherapy, photodynamic therapy and photothermal therapy. Nonetheless, controversial reports and our growing concerns about toxicity and pharmacokinetics of nanomaterials suggest the need for not only rigorous in vivo experiments in animal models but also novel nanomaterials for practical applications in the clinical settings. Further reading of original and review articles cited herein is necessary to buildup in-depth knowledge about the chemistry, bioconjugate chemistry and biological applications of individual nanomaterials.

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

NASA Astrophysics Data System (ADS)

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

2015-04-01

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

Creative cognition and dopaminergic modulation of fronto-striatal networks: Integrative review and research agenda.

PubMed

Boot, Nathalie; Baas, Matthijs; van Gaal, Simon; Cools, Roshan; De Dreu, Carsten K W

2017-07-01

Creative cognition is key to human functioning yet the underlying neurobiological mechanisms are sparsely addressed and poorly understood. Here we address the possibility that creative cognition is a function of dopaminergic modulation in fronto-striatal brain circuitries. It is proposed that (i) creative cognition benefits from both flexible and persistent processing, (ii) striatal dopamine and the integrity of the nigrostriatal dopaminergic pathway is associated with flexible processing, while (iii) prefrontal dopamine and the integrity of the mesocortical dopaminergic pathway is associated with persistent processing. We examine this possibility in light of studies linking creative ideation, divergent thinking, and creative problem-solving to polymorphisms in dopamine receptor genes, indirect markers and manipulations of the dopaminergic system, and clinical populations with dysregulated dopaminergic activity. Combined, studies suggest a functional differentiation between striatal and prefrontal dopamine: moderate (but not low or high) levels of striatal dopamine benefit creative cognition by facilitating flexible processes, and moderate (but not low or high) levels of prefrontal dopamine enable persistence-driven creativity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Interfacial bioconjugation on emulsion droplet for biosensors.

PubMed

Zhang, Qifan; Scigliano, Anita; Biver, Tarita; Pucci, Andrea; Swager, Timothy M

2018-04-13

Interfacial bioconjugation methods are developed for intact liquid emulsion droplets. Complex emulsion droplets having internal hydrocarbon and fluorocarbon immiscible structured phases maintain a dynamic interface for controlled interfacial reactivity. The internal morphological change after binding to biomolecules is readily visualized and detected by light transmission, which provides a platform for the formation of inexpensive and portable bio-sensing assays for enzymes, antibodies, nucleic acids and carbohydrates. Copyright © 2018. Published by Elsevier Ltd.

Site-specific biomolecule labeling with gold clusters.

PubMed

Ackerson, Christopher J; Powell, Richard D; Hainfeld, James F

2010-01-01

Site-specific labeling of biomolecules in vitro with gold clusters can enhance the information content of electron cryomicroscopy experiments. This chapter provides a practical overview of well-established techniques for forming biomolecule/gold cluster conjugates. Three bioconjugation chemistries are covered: linker-mediated bioconjugation, direct gold-biomolecule bonding, and coordination-mediated bonding of nickel(II) nitrilotriacetic acid (NTA)-derivatized gold clusters to polyhistidine (His)-tagged proteins. Copyright © 2010 Elsevier Inc. All rights reserved.

Molecular characterization of multivalent bioconjugates by size-exclusion chromatography with multiangle laser light scattering.

PubMed

Pollock, Jacob F; Ashton, Randolph S; Rode, Nikhil A; Schaffer, David V; Healy, Kevin E

2012-09-19

The degree of substitution and valency of bioconjugate reaction products are often poorly judged or require multiple time- and product-consuming chemical characterization methods. These aspects become critical when analyzing and optimizing the potency of costly polyvalent bioactive conjugates. In this study, size-exclusion chromatography with multiangle laser light scattering was paired with refractive index detection and ultraviolet spectroscopy (SEC-MALS-RI-UV) to characterize the reaction efficiency, degree of substitution, and valency of the products of conjugation of either peptides or proteins to a biopolymer scaffold, i.e., hyaluronic acid (HyA). Molecular characterization was more complete compared to estimates from a protein quantification assay, and exploitation of this method led to more accurate deduction of the molecular structures of polymer bioconjugates. Information obtained using this technique can improve macromolecular engineering design principles and help to better understand multivalent macromolecular interactions in biological systems.

Decarboxylative alkylation for site-selective bioconjugation of native proteins via oxidation potentials.

PubMed

Bloom, Steven; Liu, Chun; Kölmel, Dominik K; Qiao, Jennifer X; Zhang, Yong; Poss, Michael A; Ewing, William R; MacMillan, David W C

2018-02-01

The advent of antibody-drug conjugates as pharmaceuticals has fuelled a need for reliable methods of site-selective protein modification that furnish homogeneous adducts. Although bioorthogonal methods that use engineered amino acids often provide an elegant solution to the question of selective functionalization, achieving homogeneity using native amino acids remains a challenge. Here, we explore visible-light-mediated single-electron transfer as a mechanism towards enabling site- and chemoselective bioconjugation. Specifically, we demonstrate the use of photoredox catalysis as a platform to selectivity wherein the discrepancy in oxidation potentials between internal versus C-terminal carboxylates can be exploited towards obtaining C-terminal functionalization exclusively. This oxidation potential-gated technology is amenable to endogenous peptides and has been successfully demonstrated on the protein insulin. As a fundamentally new approach to bioconjugation this methodology provides a blueprint toward the development of photoredox catalysis as a generic platform to target other redox-active side chains for native conjugation.

Decarboxylative alkylation for site-selective bioconjugation of native proteins via oxidation potentials

NASA Astrophysics Data System (ADS)

Bloom, Steven; Liu, Chun; Kölmel, Dominik K.; Qiao, Jennifer X.; Zhang, Yong; Poss, Michael A.; Ewing, William R.; MacMillan, David W. C.

2018-02-01

The advent of antibody-drug conjugates as pharmaceuticals has fuelled a need for reliable methods of site-selective protein modification that furnish homogeneous adducts. Although bioorthogonal methods that use engineered amino acids often provide an elegant solution to the question of selective functionalization, achieving homogeneity using native amino acids remains a challenge. Here, we explore visible-light-mediated single-electron transfer as a mechanism towards enabling site- and chemoselective bioconjugation. Specifically, we demonstrate the use of photoredox catalysis as a platform to selectivity wherein the discrepancy in oxidation potentials between internal versus C-terminal carboxylates can be exploited towards obtaining C-terminal functionalization exclusively. This oxidation potential-gated technology is amenable to endogenous peptides and has been successfully demonstrated on the protein insulin. As a fundamentally new approach to bioconjugation this methodology provides a blueprint toward the development of photoredox catalysis as a generic platform to target other redox-active side chains for native conjugation.

Molecular characterization of multivalent bioconjugates by size-exclusion chromatography (SEC) with multi-angle laser light scattering (MALS)

PubMed Central

Pollock, Jacob F.; Ashton, Randolph S.; Rode, Nikhil A.; Schaffer, David V.; Healy, Kevin E.

2013-01-01

The degree of substitution and valency of bioconjugate reaction products are often poorly judged or require multiple time- and product- consuming chemical characterization methods. These aspects become critical when analyzing and optimizing the potency of costly polyvalent bioactive conjugates. In this study, size-exclusion chromatography with multi-angle laser light scattering was paired with refractive index detection and ultraviolet spectroscopy (SEC-MALS-RI-UV) to characterize the reaction efficiency, degree of substitution, and valency of the products of conjugation of either peptides or proteins to a biopolymer scaffold, i.e., hyaluronic acid (HyA). Molecular characterization was more complete compared to estimates from a protein quantification assay, and exploitation of this method led to more accurate deduction of the molecular structures of polymer bioconjugates. Information obtained using this technique can improve macromolecular engineering design principles and better understand multivalent macromolecular interactions in biological systems. PMID:22794081

In vivo molecular photoacoustic tomography of melanomas targeted by bio-conjugated gold nanocages

PubMed Central

Kim, Chulhong; Cho, Eun Chul; Chen, Jingyi; Song, Kwang Hyun; Au, Leslie; Favazza, Christopher; Zhang, Qiang; Cobley, Claire M.; Gao, Feng; Xia, Younan; Wang, Lihong V.

2010-01-01

Early diagnosis, accurate staging, and image-guided resection of melanomas remain crucial clinical objectives for improving patient survival and treatment outcomes. Conventional techniques cannot meet this demand because of the low sensitivity, low specificity, poor spatial resolution, shallow penetration, and/or ionizing radiation. Here we overcome such limitations by combining high-resolution photoacoustic tomography (PAT) with extraordinarily optical absorbing gold nanocages (AuNCs). When bio-conjugated with [Nle4,D-Phe7]-α-melanocyte-stimulating hormone, the AuNCs can serve as a novel contrast agent for in vivo molecular PAT of melanomas with both exquisite sensitivity and high specificity. The bio-conjugated AuNCs enhanced contrast ~300% more than the control, PEGylated AuNCs. The in vivo PAT quantification of the amount of AuNCs accumulated in melanomas was further validated with inductively coupled plasma mass spectrometry (ICP-MS). PMID:20731439

Gallium-68-labelled NOTA-oligonucleotides: an optimized method for their preparation.

PubMed

Gijs, Marlies; Dammicco, Sylvestre; Warnier, Corentin; Aerts, An; Impens, Nathalie R E N; D'Huyvetter, Matthias; Léonard, Marc; Baatout, Sarah; Luxen, André

2016-02-01

One of the most essential aspects to the success of radiopharmaceuticals is an easy and reliable radiolabelling protocol to obtain pure and stable products. In this study, we optimized the bioconjugation and gallium-68 ((68) Ga) radiolabelling conditions for a single-stranded 40-mer DNA oligonucleotide, in order to obtain highly pure and stable radiolabelled oligonucleotides. Quantitative bioconjugation was obtained for a disulfide-functionalized oligonucleotide conjugated to the macrocylic bifunctional chelator MMA-NOTA (maleimido-mono-amide (1,4,7-triazanonane-1,4,7-triyl)triacetic acid). Next, this NOTA-oligonucleotide bioconjugate was radiolabelled at room temperature with purified and pre-concentrated (68) Ga with quantitative levels of radioactive incorporation and high radiochemical and chemical purity. In addition, high chelate stability was observed in physiological-like conditions (37 °C, PBS and serum), in the presence of a transchelator (EDTA) and transferrin. A specific activity of 51.1 MBq/nmol was reached using a 1470-fold molar excess bioconjugate over (68) Ga. This study presents a fast, straightforward and reliable protocol for the preparation of (68) Ga-radiolabelled DNA oligonucleotides under mild reaction conditions and without the use of organic solvents. The methodology herein developed will be applied to the preparation of oligonucleotidic sequences (aptamers) targeting the human epidermal growth factor receptor 2 (HER2) for cancer imaging. Copyright © 2015 John Wiley & Sons, Ltd.

Use of 5'-γ-ferrocenyl adenosine triphosphate (Fc-ATP) bioconjugates having poly(ethylene glycol) spacers in kinase-catalyzed phosphorylations.

PubMed

Martić, Sanela; Rains, Meghan K; Freeman, Daniel; Kraatz, Heinz-Bernhard

2011-08-17

The 5'-γ-ferrocenyl adenosine triphosphate (Fc-ATP) bioconjugates (3 and 4), containing the poly(ethylene glycol) spacers, were synthesized and compared to a hydrophobic analogue as co-substrates for the following protein kinases: sarcoma related kinase (Src), cyclin-dependent kinase (CDK), casein kinase II (CK2α), and protein kinase A (PKA). Electrochemical kinase assays indicate that the hydrophobic Fc-ATP analogue was an optimal co-substrate for which K(M) values were determined to be in the 30-200 μM range, depending on the particular protein kinase. The luminescence kinase assay demonstrated the kinase utility for all Fc-ATP conjugates, which is in line with the electrochemical data. Moreover, Fc-ATP bioconjugates exhibit competitive behavior with respect to ATP. Relatively poor performance of the polar Fc-ATP bioconjugates as co-substrates for protein kinases was presumably due to the additional H-bonding and electrostatic interactions of the poly(ethylene glycol) linkers of Fc-ATP with the kinase catalytic site and the target peptides. Phosphorylation of the full-length protein, His-tagged pro-caspase-3, was demonstrated through Fc-phosphoamide transfer to the Ser residues of the surface-bound protein by electrochemical means. These results suggest that electrochemical detection of the peptide and protein Fc-phosphorylation via tailored Fc-ATP co-substrates may be useful for probing protein-protein interactions.

Self-organization, interfacial interaction and photophysical properties of gold nanoparticle complexes derived from resilin-mimetic fluorescent protein rec1-resilin.

PubMed

Mayavan, Sundar; Dutta, Naba K; Choudhury, Namita R; Kim, Misook; Elvin, Christopher M; Hill, Anita J

2011-04-01

In this investigation we report the synthesis of optically coupled hybrid architectures based on a new biomimetic fluorescent protein rec1-resilin and nanometer-scale gold nanoparticles (AuNPs) in a one-step method using a non-covalent mode of binding protocol. The presence of uniformly distributed fluorophore sequences, -Ser(Thr)-Tyr-Gly- along the molecular structure of rec1-resilin provides significant opportunity to synthesize fluorophore-modified AuNPs bioconjugates with unique photophysical properties. The detailed analyses of the AuNP-bioconjugates, synthesized under different experimental conditions using spectroscopic, microscopic and scattering techniques demonstrate the organizational pathways and the electronic and photophysical properties of the developed AuNP-rec1-resilin bioconjugates. The calculation of the bimolecular quenching constant using the Stern-Volmer equation confirms that the dominant mechanism involved in quenching of fluorescence of rec1-resilin in the presence of AuNP is static. Photoacoustic infrared spectroscopy was employed to understand the nature of the interfacial interaction between the AuNP and rec1-resilin and its evolution with pH. In such bioconjugates the quenched emission of fluorescence by AuNP on the fluorophore moiety of rec1-resilin in the immediate vicinity of the AuNP has significant potential for fluorescence-based detection schemes, sensors and also can be incorporated into nanoparticle-based devices. Copyright © 2011 Elsevier Ltd. All rights reserved.

A Novel Perspective on Dopaminergic Processing of Human Addiction.

PubMed

Badgaiyan, Rajendra D

2013-01-01

Converging evidence from clinical, animal, and neuroimaging experiments suggests that the addictive behavior is associated with dysregulated dopamine neurotransmission. The precise role of dopamine in establishment and maintenance of addiction however is unclear. In this context animal studies on the brain reward system and the associative memory processing provide a novel insight. It was shown that both processing involve dopamine neurotransmission and both are disrupted in addiction. These findings indicate that dysregulated dopamine neurotransmission alters the brain processing of not only the reward system but also that of the memory of association between an addictive substance and reward. These alterations lead to maladaptive motivational behavior leading to chemical dependency. This concept however is based mostly on the data obtained in laboratory animals because of the paucity of human data. Due to lack of a reliable technique to study neurotransmission in the live human brain, it has been a problem to study the role of dopamine in human volunteers. A recently developed dynamic molecular imaging technique however, provides an opportunity to study these concepts in human volunteers because the technique allows detection, mapping and measurement of dopamine released in the live human brain during task performance.

Inverted-U shaped dopamine actions on human working memory and cognitive control

PubMed Central

Cools, R; D’Esposito, M

2011-01-01

Brain dopamine has long been implicated in cognitive control processes, including working memory. However, the precise role of dopamine in cognition is not well understood, partly because there is large variability in the response to dopaminergic drugs both across different behaviors and across different individuals. We review evidence from a series of studies with experimental animals, healthy humans and patients with Parkinson’s disease, which highlight two important factors that contribute to this large variability. First, the existence of an optimum dopamine level for cognitive function implicates the need to take into account baseline levels of dopamine when isolating dopamine’s effects. Second, cognitive control is a multi-factorial phenomenon, requiring a dynamic balance between cognitive stability and cognitive flexibility. These distinct components might implicate the prefrontal cortex and the striatum respectively. Manipulating dopamine will thus have paradoxical consequences for distinct cognitive control processes depending on distinct basal or optimal levels of dopamine in different brain regions. PMID:21531388

Noradrenergic innervation of the hypothalamus of rhesus monkeys: distribution of dopamine-beta-hydroxylase immunoreactive fibers and quantitative analysis of varicosities in the paraventricular nucleus.

PubMed

Ginsberg, S D; Hof, P R; Young, W G; Morrison, J H

1993-01-22

The distribution of noradrenergic processes within the hypothalamus of rhesus monkeys (Macaca mulatta) was examined by immunohistochemistry with an antibody against dopamine-beta-hydroxylase. The results revealed that the pattern of dopamine-beta-hydroxylase immunoreactivity varied systematically throughout the rhesus monkey hypothalamus. Extremely high densities of dopamine-beta-hydroxylase-immunoreactive processes were observed in the paraventricular and supraoptic nuclei, while relatively lower levels were found in the arcuate and dorsomedial nuclei and in the medial preoptic, perifornical, and suprachiasmatic areas. Moderate levels of dopamine-beta-hydroxylase immunoreactivity were found throughout the lateral hypothalamic area and in the internal lamina of the median eminence. Very few immunoreactive processes were found in the ventromedial nucleus or in the mammillary complex. Other midline diencephalic structures were found to have high densities of dopamine-beta-hydroxylase immunoreactivity, including the paraventricular nucleus of the thalamus and a discrete subregion of nucleus reuniens, the magnocellular subfascicular nucleus. A moderate density of dopamine-beta-hydroxylase immunoreactive processes were found in the rhomboid nucleus and zona incerta whereas little dopamine-beta-hydroxylase immunoreactivity was found in the fields of Forel, nucleus reuniens, or subthalamic nucleus. The differential distribution of dopamine-beta-hydroxylase-immunoreactive processes may reflect a potential role of norepinephrine as a regulator of a variety of functions associated with the nuclei that are most heavily innervated, e.g., neuroendocrine release from the paraventricular and supraoptic nuclei, and gonadotropin release from the medial preoptic area and mediobasal hypothalamus. Additionally, quantitative analysis of dopamine-beta-hydroxylase-immunoreactive varicosities was performed on a laser scanning microscope in both magnocellular and parvicellular regions of the paraventricular nucleus of the hypothalamus. The methodology employed in this study allowed for the high resolution of immunoreactive profiles through the volume of tissue being analyzed, and was more accurate than conventional light microscopy in terms of varicosity quantification. Quantitatively, a significant difference in the density of dopamine-beta-hydroxylase-immunoreactive varicosities was found between magnocellular and parvicellular regions, suggesting that parvicellular neurons received a denser noradrenergic input. These differential patterns may reflect an important functional role for norepinephrine in the regulation of anterior pituitary secretion through the hypothalamic-pituitary-adrenal stress axis.

Subsecond dopamine fluctuations in human striatum encode superposed error signals about actual and counterfactual reward

PubMed Central

Kishida, Kenneth T.; Saez, Ignacio; Lohrenz, Terry; Witcher, Mark R.; Laxton, Adrian W.; Tatter, Stephen B.; White, Jason P.; Ellis, Thomas L.; Phillips, Paul E. M.; Montague, P. Read

2016-01-01

In the mammalian brain, dopamine is a critical neuromodulator whose actions underlie learning, decision-making, and behavioral control. Degeneration of dopamine neurons causes Parkinson’s disease, whereas dysregulation of dopamine signaling is believed to contribute to psychiatric conditions such as schizophrenia, addiction, and depression. Experiments in animal models suggest the hypothesis that dopamine release in human striatum encodes reward prediction errors (RPEs) (the difference between actual and expected outcomes) during ongoing decision-making. Blood oxygen level-dependent (BOLD) imaging experiments in humans support the idea that RPEs are tracked in the striatum; however, BOLD measurements cannot be used to infer the action of any one specific neurotransmitter. We monitored dopamine levels with subsecond temporal resolution in humans (n = 17) with Parkinson’s disease while they executed a sequential decision-making task. Participants placed bets and experienced monetary gains or losses. Dopamine fluctuations in the striatum fail to encode RPEs, as anticipated by a large body of work in model organisms. Instead, subsecond dopamine fluctuations encode an integration of RPEs with counterfactual prediction errors, the latter defined by how much better or worse the experienced outcome could have been. How dopamine fluctuations combine the actual and counterfactual is unknown. One possibility is that this process is the normal behavior of reward processing dopamine neurons, which previously had not been tested by experiments in animal models. Alternatively, this superposition of error terms may result from an additional yet-to-be-identified subclass of dopamine neurons. PMID:26598677

Subsecond dopamine fluctuations in human striatum encode superposed error signals about actual and counterfactual reward.

PubMed

Kishida, Kenneth T; Saez, Ignacio; Lohrenz, Terry; Witcher, Mark R; Laxton, Adrian W; Tatter, Stephen B; White, Jason P; Ellis, Thomas L; Phillips, Paul E M; Montague, P Read

2016-01-05

In the mammalian brain, dopamine is a critical neuromodulator whose actions underlie learning, decision-making, and behavioral control. Degeneration of dopamine neurons causes Parkinson's disease, whereas dysregulation of dopamine signaling is believed to contribute to psychiatric conditions such as schizophrenia, addiction, and depression. Experiments in animal models suggest the hypothesis that dopamine release in human striatum encodes reward prediction errors (RPEs) (the difference between actual and expected outcomes) during ongoing decision-making. Blood oxygen level-dependent (BOLD) imaging experiments in humans support the idea that RPEs are tracked in the striatum; however, BOLD measurements cannot be used to infer the action of any one specific neurotransmitter. We monitored dopamine levels with subsecond temporal resolution in humans (n = 17) with Parkinson's disease while they executed a sequential decision-making task. Participants placed bets and experienced monetary gains or losses. Dopamine fluctuations in the striatum fail to encode RPEs, as anticipated by a large body of work in model organisms. Instead, subsecond dopamine fluctuations encode an integration of RPEs with counterfactual prediction errors, the latter defined by how much better or worse the experienced outcome could have been. How dopamine fluctuations combine the actual and counterfactual is unknown. One possibility is that this process is the normal behavior of reward processing dopamine neurons, which previously had not been tested by experiments in animal models. Alternatively, this superposition of error terms may result from an additional yet-to-be-identified subclass of dopamine neurons.

Bioconjugation of luminescent Eu-BDC-NH2 MOFs for highly efficient sensing of BSA

NASA Astrophysics Data System (ADS)

Kukkar, Preeti; Sammi, Heena; Rawat, Mohit; Singh, Pritpal; Basu, Soumen; Kukkar, Deepak

2018-05-01

Luminescent metal organic frameworks (MOFs) have emerged as an exciting prospect for molecular sensing applications owing to their tunable porosity and optical properties. In this study, we have reported the synthesis of luminescent Europium-amino terephthalic acid (Eu-BDC-NH2) MOFs through solvothermal approach subsequently followed by their bioconjugation with anti-Bovine serum albumin (BSA) antibody using standard carbodiimide linkage chemistry. Subsequently nanocomposite of the bioconjugate and Zeolotic Imidazole Frameworks -8(ZIF-8) nanoparticles was prepared by adding varying volumes of ZIF-8 NPs to check the variation in photoluminescence (PL) intensity. Finally, optimized nanocomposites with increased PL intensity were treated with different concentrations of BSA to show a turn on effect on the PL intensity. The prepared nanocomposites were able to screen 0.1 ppm concentration of the BSA thus showing their high efficiency as a molecular sensor. This fluorescent platform would be further utilized for sensitive detection of pesticides in solution.

High in Vivo Stability of 64Cu-Labeled Cross-Bridged Chelators Is a Crucial Factor in Improved Tumor Imaging of RGD Peptide Conjugates.

PubMed

Sarkar, Swarbhanu; Bhatt, Nikunj; Ha, Yeong Su; Huynh, Phuong Tu; Soni, Nisarg; Lee, Woonghee; Lee, Yong Jin; Kim, Jung Young; Pandya, Darpan N; An, Gwang Il; Lee, Kyo Chul; Chang, Yongmin; Yoo, Jeongsoo

2018-01-11

Although the importance of bifunctional chelators (BFCs) is well recognized, the chemophysical parameters of chelators that govern the biological behavior of the corresponding bioconjugates have not been clearly elucidated. Here, five BFCs closely related in structure were conjugated with a cyclic RGD peptide and radiolabeled with Cu-64 ions. Various biophysical and chemical properties of the Cu(II) complexes were analyzed with the aim of identifying correlations between individual factors and the biological behavior of the conjugates. Tumor uptake and body clearance of the 64 Cu-labeled bioconjugates were directly compared by animal PET imaging in animal models, which was further supported by biodistribution studies. Conjugates containing propylene cross-bridged chelators showed higher tumor uptake, while a closely related ethylene cross-bridged analogue exhibited rapid body clearance. High in vivo stability of the copper-chelator complex was strongly correlated with high tumor uptake, while the overall lipophilicity of the bioconjugate affected both tumor uptake and body clearance.

Engineering peptide ligase specificity by proteomic identification of ligation sites.

PubMed

Weeks, Amy M; Wells, James A

2018-01-01

Enzyme-catalyzed peptide ligation is a powerful tool for site-specific protein bioconjugation, but stringent enzyme-substrate specificity limits its utility. We developed an approach for comprehensively characterizing peptide ligase specificity for N termini using proteome-derived peptide libraries. We used this strategy to characterize the ligation efficiency for >25,000 enzyme-substrate pairs in the context of the engineered peptide ligase subtiligase and identified a family of 72 mutant subtiligases with activity toward N-terminal sequences that were previously recalcitrant to modification. We applied these mutants individually for site-specific bioconjugation of purified proteins, including antibodies, and in algorithmically selected combinations for sequencing of the cellular N terminome with reduced sequence bias. We also developed a web application to enable algorithmic selection of the most efficient subtiligase variant(s) for bioconjugation to user-defined sequences. Our methods provide a new toolbox of enzymes for site-specific protein modification and a general approach for rapidly defining and engineering peptide ligase specificity.

Functionalization of peptide nucleolipid bioconjugates and their structure anti-cancer activity relationship studies.

PubMed

Rana, Niki; Cultrara, Christopher; Phillips, Mariana; Sabatino, David

2017-09-01

In the search for more potent peptide-based anti-cancer conjugates the generation of new, functionally diverse nucleolipid derived D-(KLAKLAK) 2 -AK sequences has enabled a structure and anti-cancer activity relationship study. A reductive amination approach was key for the synthesis of alkylamine, diamine and polyamine derived nucleolipids as well as those incorporating heterocyclic functionality. The carboxy-derived nucleolipids were then coupled to the C-terminus of the D-(KLAKLAK) 2 -AK killer peptide sequence and produced with and without the FITC fluorophore for investigating biological activity in cancer cells. The amphiphilic, α-helical peptide-nucleolipid bioconjugates were found to exhibit variable effects on the viability of MM.1S cells, with the histamine derived nucleolipid peptide bioconjugate displaying the most significant anti-cancer effects. Thus, functionally diverse nucleolipids have been developed to fine-tune the structure and anti-cancer properties of killer peptide sequences, such as D-(KLAKLAK) 2 -AK. Copyright © 2017 Elsevier Ltd. All rights reserved.

Polymersomes prepared from thermoresponsive fluorescent protein-polymer bioconjugates: capture of and report on drug and protein payloads.

PubMed

Wong, Chin Ken; Laos, Alistair J; Soeriyadi, Alexander H; Wiedenmann, Jörg; Curmi, Paul M G; Gooding, J Justin; Marquis, Christopher P; Stenzel, Martina H; Thordarson, Pall

2015-04-27

Polymersomes provide a good platform for targeted drug delivery and the creation of complex (bio)catalytically active systems for research in synthetic biology. To realize these applications requires both spatial control over the encapsulation components in these polymersomes and a means to report where the components are in the polymersomes. To address these twin challenges, we synthesized the protein-polymer bioconjugate PNIPAM-b-amilFP497 composed of thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) and a green-fluorescent protein variant (amilFP497). Above 37 °C, this bioconjugate forms polymersomes that can (co-)encapsulate the fluorescent drug doxorubicin and the fluorescent light-harvesting protein phycoerythrin 545 (PE545). Using fluorescence lifetime imaging microscopy and Förster resonance energy transfer (FLIM-FRET), we can distinguish the co-encapsulated PE545 protein inside the polymersome membrane while doxorubicin is found both in the polymersome core and membrane. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Super-sensitive time-resolved fluoroimmunoassay for thyroid-stimulating hormone utilizing europium(III) nanoparticle labels achieved by protein corona stabilization, short binding time, and serum preprocessing.

PubMed

Näreoja, Tuomas; Rosenholm, Jessica M; Lamminmäki, Urpo; Hänninen, Pekka E

2017-05-01

Thyrotropin or thyroid-stimulating hormone (TSH) is used as a marker for thyroid function. More precise and more sensitive immunoassays are needed to facilitate continuous monitoring of thyroid dysfunctions and to assess the efficacy of the selected therapy and dosage of medication. Moreover, most thyroid diseases are autoimmune diseases making TSH assays very prone to immunoassay interferences due to autoantibodies in the sample matrix. We have developed a super-sensitive TSH immunoassay utilizing nanoparticle labels with a detection limit of 60 nU L -1 in preprocessed serum samples by reducing nonspecific binding. The developed preprocessing step by affinity purification removed interfering compounds and improved the recovery of spiked TSH from serum. The sensitivity enhancement was achieved by stabilization of the protein corona of the nanoparticle bioconjugates and a spot-coated configuration of the active solid-phase that reduced sedimentation of the nanoparticle bioconjugates and their contact time with antibody-coated solid phase, thus making use of the higher association rate of specific binding due to high avidity nanoparticle bioconjugates. Graphical Abstract We were able to decrease the lowest limit of detection and increase sensitivity of TSH immunoassay using Eu(III)-nanoparticles. The improvement was achieved by decreasing binding time of nanoparticle bioconjugates by small capture area and fast circular rotation. Also, we applied a step to stabilize protein corona of the nanoparticles and a serum-preprocessing step with a structurally related antibody.

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

Dopamine, reward learning, and active inference.

PubMed

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.

Levodopa administration modulates striatal processing of punishment-associated items in healthy participants.

PubMed

Wittmann, Bianca C; D'Esposito, Mark

2015-01-01

Appetitive and aversive processes share a number of features such as their relevance for action and learning. On a neural level, reward and its predictors are associated with increased firing of dopaminergic neurons, whereas punishment processing has been linked to the serotonergic system and to decreases in dopamine transmission. Recent data indicate, however, that the dopaminergic system also responds to aversive stimuli and associated actions. In this pharmacological functional magnetic resonance imaging study, we investigated the contribution of the dopaminergic system to reward and punishment processing in humans. Two groups of participants received either placebo or the dopamine precursor levodopa and were scanned during alternating reward and punishment anticipation blocks. Levodopa administration increased striatal activations for cues presented in punishment blocks. In an interaction with individual personality scores, levodopa also enhanced striatal activation for punishment-predictive compared with neutral cues in participants scoring higher on the novelty-seeking dimension. These data support recent indications that dopamine contributes to punishment processing and suggest that the novelty-seeking trait is a measure of susceptibility to drug effects on motivation. These findings are also consistent with the possibility of an inverted U-shaped response function of dopamine in the striatum, suggesting an optimal level of dopamine release for motivational processing.

Levodopa administration modulates striatal processing of punishment-associated items in healthy participants

PubMed Central

Wittmann, Bianca C.; D’Esposito, Mark

2014-01-01

Rationale Appetitive and aversive processes share a number of features such as their relevance for action and learning. On a neural level, reward and its predictors are associated with increased firing of dopaminergic neurons, whereas punishment processing has been linked to the serotonergic system and to decreases in dopamine transmission. Recent data indicate, however, that the dopaminergic system also responds to aversive stimuli and associated actions. Objectives In this pharmacological functional magnetic resonance imaging (fMRI) study, we investigated the contribution of the dopaminergic system to reward and punishment processing in humans. Methods Two groups of participants received either placebo or the dopamine precursor levodopa and were scanned during alternating reward and punishment anticipation blocks. Results Levodopa administration increased striatal activations for cues presented in punishment blocks. In an interaction with individual personality scores, levodopa also enhanced striatal activation for punishment-predictive compared to neutral cues in participants scoring higher on the novelty-seeking dimension. Conclusions These data support recent indications that dopamine contributes to punishment processing and suggest that the novelty-seeking trait is a measure of susceptibility to drug effects on motivation. These findings are also consistent with the possibility of an inverted U-shaped response function of dopamine in the striatum, suggesting an optimal level of dopamine release for motivational processing. PMID:24923987

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

Cocaine cues drive opposing context-dependent shifts in reward processing and emotional state.

PubMed

Wheeler, Robert A; Aragona, Brandon J; Fuhrmann, Katherine A; Jones, Joshua L; Day, Jeremy J; Cacciapaglia, Fabio; Wightman, R Mark; Carelli, Regina M

2011-06-01

Prominent neurobiological theories of addiction posit a central role for aberrant mesolimbic dopamine release but disagree as to whether repeated drug experience blunts or enhances this system. Although drug withdrawal diminishes dopamine release, drug sensitization augments mesolimbic function, and both processes have been linked to drug seeking. One possibility is that the dopamine system can rapidly switch from dampened to enhanced release depending on the specific drug-predictive environment. To test this, we examined dopamine release when cues signaled delayed cocaine delivery versus imminent cocaine self-administration. Fast-scan cyclic voltammetry was used to examine real-time dopamine release while simultaneously monitoring behavioral indexes of aversion as rats experienced a sweet taste cue that predicted delayed cocaine availability and during self-administration. Furthermore, the impact of cues signaling delayed drug availability on intracranial self-stimulation, a broad measure of reward function, was assessed. We observed decreased mesolimbic dopamine concentrations, decreased reward sensitivity, and negative affect in response to the cocaine-predictive taste cue that signaled delayed cocaine availability. Importantly, dopamine concentration rapidly switched to elevated levels to cues signaling imminent cocaine delivery in the subsequent self-administration session. These findings show rapid, bivalent contextual control over brain reward processing, affect, and motivated behavior and have implications for mechanisms mediating substance abuse. Copyright © 2011 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Midbrain dopamine neurons associated with reward processing innervate the neurogenic subventricular zone.

PubMed

Lennington, Jessica B; Pope, Sara; Goodheart, Anna E; Drozdowicz, Linda; Daniels, Stephen B; Salamone, John D; Conover, Joanne C

2011-09-14

Coordinated regulation of the adult neurogenic subventricular zone (SVZ) is accomplished by a myriad of intrinsic and extrinsic factors. The neurotransmitter dopamine is one regulatory molecule implicated in SVZ function. Nigrostriatal and ventral tegmental area (VTA) midbrain dopamine neurons innervate regions adjacent to the SVZ, and dopamine synapses are found on SVZ cells. Cell division within the SVZ is decreased in humans with Parkinson's disease and in animal models of Parkinson's disease following exposure to toxins that selectively remove nigrostriatal neurons, suggesting that dopamine is critical for SVZ function and nigrostriatal neurons are the main suppliers of SVZ dopamine. However, when we examined the aphakia mouse, which is deficient in nigrostriatal neurons, we found no detrimental effect to SVZ proliferation or organization. Instead, dopamine innervation of the SVZ tracked to neurons at the ventrolateral boundary of the VTA. This same dopaminergic neuron population also innervated the SVZ of control mice. Characterization of these neurons revealed expression of proteins indicative of VTA neurons. Furthermore, exposure to the neurotoxin MPTP depleted neurons in the ventrolateral VTA and resulted in decreased SVZ proliferation. Together, these results reveal that dopamine signaling in the SVZ originates from a population of midbrain neurons more typically associated with motivational and reward processing.

Dopamine treatment and cognitive functioning in individuals with Parkinson's disease: the "cognitive flexibility" hypothesis seems to work.

PubMed

Costa, Alberto; Peppe, Antonella; Mazzù, Ilenia; Longarzo, Mariachiara; Caltagirone, Carlo; Carlesimo, Giovanni A

2014-01-01

Previous data suggest that (i) dopamine modulates the ability to implement nonroutine schemata and update operations (flexibility processes) and that (ii) dopamine-related improvement may be related to baseline dopamine levels in target pathways (inverted U-shaped hypothesis). To investigate above hypotheses in individuals with Parkinson's disease (PD). Twenty PD patients were administered tasks varying as to flexibility load in two treatment conditions: (i) "off" condition, about 18 hours after dopamine dose and (ii) "on" condition, after dopamine administration. PD patients were separated into two groups: low performers (i.e., performance on Digit Span Backward below the sample mean) and high performers (i.e., performance above the mean). Twenty healthy individuals performed the tasks in two sessions without taking drugs. Passing from the "off" to the "on" state, only low performer PD patients significantly improved their performance on high-flexibility measures (interference condition of the Stroop test; P < 0.05); no significant effect was found on low-flexibility tasks. These findings document that high-flexibility processes are sensitive to dopamine neuromodulation in the early phases of PD. This is in line with the hypothesis that striatal dopamine pathways, affected early by PD, are precociously implicated in the expression of cognitive disorders in these individuals.

Endocannabinoid Signaling in Motivation, Reward, and Addiction: Influences on Mesocorticolimbic Dopamine Function.

PubMed

Sagheddu, Claudia; Muntoni, Anna Lisa; Pistis, Marco; Melis, Miriam

2015-01-01

Evidence suggests that the endocannabinoid system has been conserved in the animal kingdom for 500 million years, and this system influences many critical behavioral processes including associative learning, reward signaling, goal-directed behavior, motor skill learning, and action-habit transformation. Additionally, the neurotransmitter dopamine has long been recognized to play a critical role in the processing of natural rewards, as well as of motivation that regulates approach and avoidance behavior. This motivational role of dopamine neurons is also based upon the evidence provided by several studies investigating disorders of dopamine pathways such as drug addiction and Parkinson's disease. From an evolutionary point of view, individuals engage in behaviors aimed at maximizing and minimizing positive and aversive consequences, respectively. Accordingly, those with the greatest fitness have a better potential to survival. Hence, deviations from fitness can be viewed as a part of the evolutionary process by means of natural selection. Given the long evolutionary history of both the endocannabinoid and dopaminergic systems, it is plausible that they must serve as fundamental and basic modulators of physiological functions and needs. Notably, endocannabinoids regulate dopamine neuronal activity and its influence on behavioral output. The goal of this chapter is to examine the endocannabinoid influence on dopamine signaling specifically related to (i) those behavioral processes that allow us to successfully adapt to ever-changing environments (i.e., reward signaling and motivational processes) and (ii) derangements from behavioral flexibility that underpin drug addiction. © 2015 Elsevier Inc. All rights reserved.

Application of bioconjugation chemistry on biosensor fabrication for detection of TAR-DNA binding protein 43.

PubMed

Dai, Yifan; Wang, Chunlai; Chiu, Liang-Yuan; Abbasi, Kevin; Tolbert, Blanton S; Sauvé, Geneviève; Yen, Yun; Liu, Chung-Chiun

2018-06-01

A simple-prepare, single-use and cost-effective, in vitro biosensor for the detection of TAR DNA-binding protein 43 (TDP-43), a biomarker of neuro-degenerative disorders, was designed, manufactured and tested. This study reports the first biosensor application for the detection of TDP-43 using a novel biosensor fabrication methodology. Bioconjugation mechanism was applied by conjugating anti-TDP 43 with N-succinimidyl S-acetylthioacetate (SATA) producing a thiol-linked anti-TDP 43, which was used to directly link with gold electrode surface, minimizing the preparation steps for biosensor fabrication and simplifying the biosensor surface. The effectiveness of this bioconjugation mechanism was evaluated and confirmed by FqRRM12 protein, using nuclear magnetic resonance (NMR). The surface coverage of the electrode was analyzed by Time-of-Flight-Secondary Ion Mass Spectrometry (TOF-SIMS). Differential pulse voltammetry (DPV) was acted as the detection transduction mechanism with the use of [Fe(CN) 6 ] 3-/4- redox probe. Human TDP-43 peptide of 0.0005 µg/mL to 2 µg/mL in undiluted human serum was analyzed using this TDP-43 biosensor. Interference study of the TDP-43 biosensor using β-amyloid 42 protein and T-tau protein confirmed the specificity of this TDP-43 biosensor. This bioconjugation chemistry based approach for biosensor fabrication circumvents tedious gold surface modification and functionalization while enabling specific detection of TDP-43 in less than 1 h with a low fabrication cost of a single biosensor less than $3. Copyright © 2018 Elsevier B.V. All rights reserved.

PRESYNAPTIC DOPAMINE MODULATION BY STIMULANT SELF ADMINISTRATION

PubMed Central

España, Rodrigo A.; Jones, Sara R.

2013-01-01

The mesolimbic dopamine system is an essential participant in the initiation and modulation of various forms of goal-directed behavior, including drug reinforcement and addiction processes. Dopamine neurotransmission is increased by acute administration of all drugs of abuse, including the stimulants cocaine and amphetamine. Chronic exposure to these drugs via voluntary self-administration provides a model of stimulant abuse that is useful in evaluating potential behavioral and neurochemical adaptations that occur during addiction. This review describes commonly used methodologies to measure dopamine and baseline parameters of presynaptic dopamine regulation, including exocytotic release and reuptake through the dopamine transporter in the nucleus accumbens core, as well as dramatic adaptations in dopamine neurotransmission and drug sensitivity that occur with acute non-contingent and chronic, contingent self-administration of cocaine and amphetamine. PMID:23277050

Salt Effect Accelerates Site-Selective Cysteine Bioconjugation

PubMed Central

2016-01-01

Highly efficient and selective chemical reactions are desired. For small molecule chemistry, the reaction rate can be varied by changing the concentration, temperature, and solvent used. In contrast for large biomolecules, the reaction rate is difficult to modify by adjusting these variables because stringent biocompatible reaction conditions are required. Here we show that adding salts can change the rate constant over 4 orders of magnitude for an arylation bioconjugation reaction between a cysteine residue within a four-residue sequence (π-clamp) and a perfluoroaryl electrophile. Biocompatible ammonium sulfate significantly enhances the reaction rate without influencing the site-specificity of π-clamp mediated arylation, enabling the fast synthesis of two site-specific antibody–drug conjugates that selectively kill HER2-positive breast cancer cells. Computational and structure–reactivity studies indicate that salts may tune the reaction rate through modulating the interactions between the π-clamp hydrophobic side chains and the electrophile. On the basis of this understanding, the salt effect is extended to other bioconjugation chemistry, and a new regioselective alkylation reaction at π-clamp cysteine is developed. PMID:27725962

Targeting glioma stem cells enhances anti-tumor effect of boron neutron capture therapy

PubMed Central

Sun, Ting; Li, Yanyan; Huang, Yulun; Zhang, Zizhu; Yang, Weilian; Du, Ziwei; Zhou, Youxin

2016-01-01

The uptake of (10)boron by tumor cells plays an important role for cell damage in boron neutron capture therapy (BNCT). CD133 is frequently expressed in the membrane of glioma stem cells (GSCs), resistant to radiotherapy and chemotherapy, and represents a potential therapeutic target. To increase (10)boron uptake in GSCs, we created a polyamido amine dendrimer, conjugated CD133 monoclonal antibodies, encapsulating mercaptoundecahydrododecaborate (BSH) in void spaces, and monitored the uptake of the bioconjugate nanoparticles by GSCs in vitro and in vivo. Fluorescence microscopy showed the specific uptake of the bioconjugate nanoparticles by CD133-positive GSCs. Treatment with the biconjugate nanoparticles resulted in a significant lethal effect after neutron radiation due to efficient and CD133-independent cellular targeting and uptake in CD133-expressing GSCs. A significantly longer survival occurred in combination with the biconjugate nanoparticles and BSH compared with BSH alone in human intracranial GBM models employing CD133-positive GSCs xenografts. Our data demonstrated that this bioconjugate nanoparticle targets human CD133-positive GSCs and is a potential boron agent in BNCT. PMID:27191269

Targeting glioma stem cells enhances anti-tumor effect of boron neutron capture therapy.

PubMed

Sun, Ting; Li, Yanyan; Huang, Yulun; Zhang, Zizhu; Yang, Weilian; Du, Ziwei; Zhou, Youxin

2016-07-12

The uptake of (10)boron by tumor cells plays an important role for cell damage in boron neutron capture therapy (BNCT). CD133 is frequently expressed in the membrane of glioma stem cells (GSCs), resistant to radiotherapy and chemotherapy, and represents a potential therapeutic target. To increase (10)boron uptake in GSCs, we created a polyamido amine dendrimer, conjugated CD133 monoclonal antibodies, encapsulating mercaptoundecahydrododecaborate (BSH) in void spaces, and monitored the uptake of the bioconjugate nanoparticles by GSCs in vitro and in vivo. Fluorescence microscopy showed the specific uptake of the bioconjugate nanoparticles by CD133-positive GSCs. Treatment with the biconjugate nanoparticles resulted in a significant lethal effect after neutron radiation due to efficient and CD133-independent cellular targeting and uptake in CD133-expressing GSCs. A significantly longer survival occurred in combination with the biconjugate nanoparticles and BSH compared with BSH alone in human intracranial GBM models employing CD133-positive GSCs xenografts. Our data demonstrated that this bioconjugate nanoparticle targets human CD133-positive GSCs and is a potential boron agent in BNCT.

ortho-Methoxyphenols as Convenient Oxidative Bioconjugation Reagents with Application to Site-Selective Heterobifunctional Cross-Linkers.

PubMed

ElSohly, Adel M; MacDonald, James I; Hentzen, Nina B; Aanei, Ioana L; El Muslemany, Kareem M; Francis, Matthew B

2017-03-15

The synthesis of complex protein-based bioconjugates has been facilitated greatly by recent developments in chemoselective methods for biomolecular modification. The oxidative coupling of o-aminophenols or catechols with aniline functional groups is chemoselective, mild, and rapid; however, the oxidatively sensitive nature of the electron-rich aromatics and the paucity of commercial sources pose some obstacles to the general use of these reactive strategies. Herein, we identify o-methoxyphenols as air-stable, commercially available derivatives that undergo efficient oxidative couplings with anilines in the presence of periodate as oxidant. Mechanistic considerations informed the development of a preoxidation protocol that can greatly reduce the amount of periodate necessary for effective coupling. The stability and versatility of these reagents was demonstrated through the synthesis of complex protein-protein bioconjugates using a site-selective heterobifunctional cross-linker comprising both o-methoxyphenol and 2-pyridinecarboxaldehyde moieties. This compound was used to link epidermal growth factor to genome-free MS2 viral capsids, affording nanoscale delivery vectors that can target a variety of cancer cell types.

Efficient Bioconjugation of Protein Capture Agents to Biosensor Surfaces Using Aniline-Catalyzed Hydrazone Ligation

PubMed Central

Byeon, Ji-Yeon; Limpoco, F. T.; Bailey, Ryan C.

2010-01-01

Aniline-catalyzed hydrazone ligation between surface immobilized hydrazines and aldehyde-modified antibodies is shown to be an efficient method for attaching protein capture agents to model oxide-coated biosensor substrates. Silicon photonic microring resonators are used to directly evaluate the efficiency of this surface bioconjugate reaction at various pHs and in the presence or absence of aniline as a nucleophilic catalyst. It is found that aniline significantly increases the net antibody loading for surfaces functionalized over a pH range from 4.5 to 7.4, allowing derivatization of substrates with reduced incubation time and sample consumption. This increase in antibody loading directly results in more sensitive antigen detection when functionalized microrings are employed in a label-free immunoassay. Furthermore, these experiments also reveal an interesting pH dependent non-covalent binding trend that plays an important role in dictating the amount of antibody attached onto the substrate, highlighting the competing contributions of the bioconjugate reaction rate and the dynamic interactions that control opportunities for a solution-phase biomolecule to react with a substrate-bound reagent. PMID:20809595

Photoluminescence of double core/shell infrared (CdSeTe)/ZnS quantum dots conjugated to Pseudo rabies virus antibodies

NASA Astrophysics Data System (ADS)

Torchynska, T. V.; Casas Espinola, J. L.; Jaramillo Gómez, J. A.; Douda, J.; Gazarian, K.

2013-06-01

Double core CdSeTe/ZnS quantum dots (QDs) with emission at 800 nm (1.60 eV) have been studied by photoluminescence (PL) and Raman scattering methods in the non-conjugated state and after the conjugation to the Pseudo rabies virus (PRV) antibodies. The transformation of PL spectra, stimulated by the electric charge of antibodies, has been detected for the bioconjugated QDs. Raman scattering spectra are investigated with the aim to reveal the CdSeTe core compositions. The double core QD energy diagrams were designed that help to analyze the PL spectra and their transformation at the bioconjugation. It is revealed that the interface in double core QDs has the type II quantum well character that permits to explain the near IR optical transition (1.60 eV) in the double core QDs. It is shown that the essential transformation of PL spectra is useful for the study of QD bioconjugation with specific antibodies and can be a powerful technique in early medical diagnostics.

Assessment of the systemic distribution of a bioconjugated anti-Her2 magnetic nanoparticle in a breast cancer model by means of magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Huerta-Núñez, L. F. E.; Villanueva-Lopez, G. Cleva; Morales-Guadarrama, A.; Soto, S.; López, J.; Silva, J. G.; Perez-Vielma, N.; Sacristán, E.; Gudiño-Zayas, Marco E.; González, C. A.

2016-09-01

The aim of this study was to determine the systemic distribution of magnetic nanoparticles of 100 nm diameter (MNPs) coupled to a specific monoclonal antibody anti-Her2 in an experimental breast cancer (BC) model. The study was performed in two groups of Sprague-Dawley rats: control ( n = 6) and BC chemically induced ( n = 3). Bioconjugated "anti-Her2-MNPs" were intravenously administered, and magnetic resonance imaging (MRI) monitored its systemic distribution at seven times after administration. Non-heme iron presence associated with the location of the bioconjugated anti-Her2-MNPs in splenic, hepatic, cardiac and tumor tissues was detected by Perl's Prussian blue (PPB) stain. Optical density measurements were used to semiquantitatively determine the iron presence in tissues on the basis of a grayscale values integration of T1 and T2 MRI sequence images. The results indicated a delayed systemic distribution of MNPs in cancer compared to healthy conditions with a maximum concentration of MNPs in cancer tissue at 24 h post-infusion.

"Click" on PLGA-PEG and hyaluronic acid: Gaining access to anti-leishmanial pentamidine bioconjugates.

PubMed

Scala, Angela; Piperno, Anna; Micale, Nicola; Mineo, Placido G; Abbadessa, Antonio; Risoluti, Roberta; Castelli, Germano; Bruno, Federica; Vitale, Fabrizio; Cascio, Antonio; Grassi, Giovanni

2017-12-08

Pentamidine (Pent), an antiparasitic drug used for the treatment of visceral leishmaniasis, has been modified with terminal azide groups and conjugated to two different polymer backbones (PLGA-PEG [PP] copolymer and hyaluronic acid [HA]) armed with alkyne end-groups. The conjugation has been performed by Copper Catalyzed Azido Alkyne Cycloaddition (CuAAC) using CuSO 4 /sodium ascorbate as metal source. The novel PP-Pent and HA-Pent bioconjugates are proposed, respectively, as non-targeted and targeted drug delivery systems against Leishmania infections. Moreover, Pent has been encapsulated into PP nanoparticles by the oil-in-water emulsion method, with the aim to compare the biological activity of the bioconjugates with that of the classical drug-loaded delivery system that physically entraps the therapeutic agent. Biological assays against Leishmania infantum amastigote-infected macrophages and primary macrophages revealed that Pent, either covalently conjugated with polymers or loaded into polymeric nanoparticles, turned out to be more potent and less toxic than the free Pent. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

Imaging Pancreatic Cancer Using Bioconjugated InP Quantum Dots

PubMed Central

Yong, Ken-Tye; Ding, Hong; Roy, Indrajit; Law, Wing-Cheung; Bergey, Earl J.; Maitra, Anirban; Prasad, Paras N.

2009-01-01

In this paper, we report the successful use of non-cadmium based quantum dots (QDs) as highly efficient and non-toxic optical probes for imaging live pancreatic cancer cells. Indium phosphide (core)-zinc sulphide (shell), or InP/ZnS, QDs with high quality and bright luminescence were prepared by a hot colloidal synthesis method in non-aqueous media. The surfaces of these QDs were then functionalized with mercaptosuccinic acid to make them highly dispersible in aqueous media. Further bioconjugation with pancreatic cancer specific monoclonal antibodies, such as anti-claudin 4 and anti-prostate stem cell antigen (anti-PSCA), to the functionalized InP/ZnS QDs, allowed specific in vitro targeting of pancreatic cancer cell lines (both immortalized and low passage ones). The receptor mediated delivery of the bioconjugates was further confirmed by the observation of poor in vitro targeting in non-pancreatic cancer based cell lines which are negative for the claudin-4-receptor. These observations suggest the immense potential of InP/ZnS QDs as non-cadmium based safe and efficient optical imaging nanoprobes in diagnostic imaging, particularly for early detection of cancer. PMID:19243145

Imaging pancreatic cancer using bioconjugated InP quantum dots.

PubMed

Yong, Ken-Tye; Ding, Hong; Roy, Indrajit; Law, Wing-Cheung; Bergey, Earl J; Maitra, Anirban; Prasad, Paras N

2009-03-24

In this paper, we report the successful use of non-cadmium-based quantum dots (QDs) as highly efficient and nontoxic optical probes for imaging live pancreatic cancer cells. Indium phosphide (core)-zinc sulfide (shell), or InP/ZnS, QDs with high quality and bright luminescence were prepared by a hot colloidal synthesis method in nonaqueous media. The surfaces of these QDs were then functionalized with mercaptosuccinic acid to make them highly dispersible in aqueous media. Further bioconjugation with pancreatic cancer specific monoclonal antibodies, such as anticlaudin 4 and antiprostate stem cell antigen (anti-PSCA), to the functionalized InP/ZnS QDs, allowed specific in vitro targeting of pancreatic cancer cell lines (both immortalized and low passage ones). The receptor-mediated delivery of the bioconjugates was further confirmed by the observation of poor in vitro targeting in nonpancreatic cancer based cell lines which are negative for the claudin-4-receptor. These observations suggest the immense potential of InP/ZnS QDs as non-cadmium-based safe and efficient optical imaging nanoprobes in diagnostic imaging, particularly for early detection of cancer.

Modulation of memory fields by dopamine Dl receptors in prefrontal cortex

NASA Astrophysics Data System (ADS)

Williams, Graham V.; Goldman-Rakic, Patricia S.

1995-08-01

Dopamine has been implicated in the cognitive process of working memory but the cellular basis of its action has yet to be revealed. By combining iontophoretic analysis of dopamine receptors with single-cell recording during behaviour, we found that D1 antagonists can selectively potentiate the 'memory fields' of prefrontal neurons which subserve working memory. The precision shown for D1 receptor modulation of mnemonic processing indicates a direct gating of selective excitatory synaptic inputs to prefrontal neurons during cognition.

Dopamine controls the neural dynamics of memory signals and retrieval accuracy.

PubMed

Apitz, Thore; Bunzeck, Nico

2013-11-01

The human brain is capable of differentiating between new and already stored information rapidly to allow optimal behavior and decision-making. Although the neural mechanisms of novelty discrimination were often described as temporally constant (ie, with specific latencies), recent electrophysiological studies have demonstrated that the onset of neural novelty signals (ie, differences in event-related responses to new and old items) can be accelerated by reward motivation. While the precise physiological mechanisms underlying this acceleration remain unclear, the involvement of the neurotransmitter dopamine in both novelty and reward processing suggests that enhanced dopamine levels in the context of reward prospect may have a role. To investigate this hypothesis, we used magnetoencephalography (MEG) in combination with an old/new recognition memory task in which correct discrimination between old and new items was rewarded. Importantly, before the task, human subjects received either 150 mg of the dopamine precursor levodopa or placebo. For the placebo group, old/new signals peaked at ∼100 ms after stimulus onset over left temporal/occipital sensors. In contrast, after levodopa administration earliest old/new effects only emerged after ∼400 ms and retrieval accuracy was reduced as expressed in lower d' values. As such, our results point towards a previously unreported role of dopamine in controlling the chronometry of neural processes underlying the distinction between old and new information. They also suggest that this relationship follows a nonlinear function whereby slightly enhanced dopamine levels accelerate neural/cognitive processes and excessive dopamine levels impair them.

Discrete neurochemical coding of distinguishable motivational processes: insights from nucleus accumbens control of feeding.

PubMed

Baldo, Brian A; Kelley, Ann E

2007-04-01

The idea that nucleus accumbens (Acb) dopamine transmission contributes to the neural mediation of reward, at least in a general sense, has achieved wide acceptance. Nevertheless, debate remains over the precise nature of dopamine's role in reward and even over the nature of reward itself. In the present article, evidence is reviewed from studies of food intake, feeding microstructure, instrumental responding for food reinforcement, and dopamine efflux associated with feeding, which suggests that reward processing in the Acb is best understood as an interaction among distinct processes coded by discrete neurotransmitter systems. In agreement with several theories of Acb dopamine function, it is proposed here that allocation of motor effort in seeking food or food-associated conditioned stimuli can be dissociated from computations relevant to the hedonic evaluation of food during the consummatory act. The former appears to depend upon Acb dopamine transmission and the latter upon striatal opioid peptide release. Moreover, dopamine transmission may play a role in 'stamping in' associations between motor acts and goal attainment and perhaps also neural representations corresponding to rewarding outcomes. Finally, evidence is reviewed that amino acid transmission specifically in the Acb shell acts as a central 'circuit breaker' to flexibly enable or terminate the consummatory act, via descending connections to hypothalamic feeding control systems. The heuristic framework outlined above may help explain why dopamine-compromising manipulations that strongly diminish instrumental goal-seeking behaviors leave consummatory activity relatively unaffected.

Synthesis and use of 2-[ 18F]fluoromalondialdehyde, an accessible synthon for bioconjugation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hooker, Jacob M.

We proposed methods for the synthesis and purification of 2-[ 18F]fluoromalondialdehyde, which will be a readily accessible synthon for bioconjugation. Our achievements in these areas will specifically address a stated goal of the DOE providing a transformational technology for macromolecule radiolabeling. Accomplishment of our aims will serve both DOE mission-related research as well as nuclear medicine research supported by the NIH and industry. At the heart of our proposal is the aim to “improve synthetic methodology for rapidly and efficiently incorporating radionuclides into a wide range of organic compounds.”

Activation of D1/5 Dopamine Receptors: A Common Mechanism for Enhancing Extinction of Fear and Reward-Seeking Behaviors.

PubMed

Abraham, Antony D; Neve, Kim A; Lattal, K Matthew

2016-07-01

Dopamine is critical for many processes that drive learning and memory, including motivation, prediction error, incentive salience, memory consolidation, and response output. Theories of dopamine's function in these processes have, for the most part, been developed from behavioral approaches that examine learning mechanisms in appetitive tasks. A parallel and growing literature indicates that dopamine signaling is involved in consolidation of memories into stable representations in aversive tasks such as fear conditioning. Relatively little is known about how dopamine may modulate memories that form during extinction, when organisms learn that the relation between previously associated events is severed. We investigated whether fear and reward extinction share common mechanisms that could be enhanced with dopamine D1/5 receptor activation. Pharmacological activation of dopamine D1/5 receptors (with SKF 81297) enhanced extinction of both cued and contextual fear. These effects also occurred in the extinction of cocaine-induced conditioned place preference, suggesting that the observed effects on extinction were not specific to a particular type of procedure (aversive or appetitive). A cAMP/PKA biased D1 agonist (SKF 83959) did not affect fear extinction, whereas a broadly efficacious D1 agonist (SKF 83822) promoted fear extinction. Together, these findings show that dopamine D1/5 receptor activation is a target for the enhancement of fear or reward extinction.

The Michelin red guide of the brain: role of dopamine in goal-oriented navigation.

PubMed

Retailleau, Aude; Boraud, Thomas

2014-01-01

Spatial learning has been recognized over the years to be under the control of the hippocampus and related temporal lobe structures. Hippocampal damage often causes severe impairments in the ability to learn and remember a location in space defined by distal visual cues. Such cognitive disabilities are found in Parkinsonian patients. We recently investigated the role of dopamine in navigation in the 6-Hydroxy-dopamine (6-OHDA) rat, a model of Parkinson's disease (PD) commonly used to investigate the pathophysiology of dopamine depletion (Retailleau et al., 2013). We demonstrated that dopamine (DA) is essential to spatial learning as its depletion results in spatial impairments. Our results showed that the behavioral effect of DA depletion is correlated with modification of the neural encoding of spatial features and decision making processes in hippocampus. However, the origin of these alterations in the neural processing of the spatial information needs to be clarified. It could result from a local effect: dopamine depletion disturbs directly the processing of relevant spatial information at hippocampal level. Alternatively, it could result from a more distributed network effect: dopamine depletion elsewhere in the brain (entorhinal cortex, striatum, etc.) modifies the way hippocampus processes spatial information. Recent experimental evidence in rodents, demonstrated indeed, that other brain areas are involved in the acquisition of spatial information. Amongst these, the cortex-basal ganglia (BG) loop is known to be involved in reinforcement learning and has been identified as an important contributor to spatial learning. In particular, it has been shown that altered activity of the BG striatal complex can impair the ability to perform spatial learning tasks. The present review provides a glimpse of the findings obtained over the past decade that support a dialog between these two structures during spatial learning under DA control.

Visualization of Plasticity in Fear-Evoked Calcium Signals in Midbrain Dopamine Neurons

ERIC Educational Resources Information Center

Gore, Bryan B.; Soden, Marta E.; Zweifel, Larry S.

2014-01-01

Dopamine is broadly implicated in fear-related processes, yet we know very little about signaling dynamics in these neurons during active fear conditioning. We describe the direct imaging of calcium signals of dopamine neurons during Pavlovian fear conditioning using fiber-optic confocal microscopy coupled with the genetically encoded calcium…

Decoding the contribution of dopaminergic genes and pathways to autism spectrum disorder (ASD).

PubMed

Nguyen, Michael; Roth, Andrew; Kyzar, Evan J; Poudel, Manoj K; Wong, Keith; Stewart, Adam Michael; Kalueff, Allan V

2014-01-01

Autism spectrum disorder (ASD) is a debilitating brain illness causing social deficits, delayed development and repetitive behaviors. ASD is a heritable neurodevelopmental disorder with poorly understood and complex etiology. The central dopaminergic system is strongly implicated in ASD pathogenesis. Genes encoding various elements of this system (including dopamine receptors, the dopamine transporter or enzymes of synthesis and catabolism) have been linked to ASD. Here, we comprehensively evaluate known molecular interactors of dopaminergic genes, and identify their potential molecular partners within up/down-steam signaling pathways associated with dopamine. These in silico analyses allowed us to construct a map of molecular pathways, regulated by dopamine and involved in ASD. Clustering these pathways reveals groups of genes associated with dopamine metabolism, encoding proteins that control dopamine neurotransmission, cytoskeletal processes, synaptic release, Ca(2+) signaling, as well as the adenosine, glutamatergic and gamma-aminobutyric systems. Overall, our analyses emphasize the important role of the dopaminergic system in ASD, and implicate several cellular signaling processes in its pathogenesis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hydrophobization and bioconjugation for enhanced siRNA delivery and targeting

PubMed Central

De Paula, Daniel; Bentley, M. Vitória L.B.; Mahato, Ram I.

2007-01-01

RNA interference (RNAi) is an evolutionarily conserved process by which double-stranded small interfering RNA (siRNA) induces sequence-specific, post-transcriptional gene silencing. Unlike other mRNA targeting strategies, RNAi takes advantage of the physiological gene silencing machinery. The potential use of siRNA as therapeutic agents has attracted great attention as a novel approach for treating severe and chronic diseases. RNAi can be achieved by either delivery of chemically synthesized siRNAs or endogenous expression of small hairpin RNA, siRNA, and microRNA (miRNA). However, the relatively high dose of siRNA required for gene silencing limits its therapeutic applications. This review discusses several strategies to improve therapeutic efficacy as well as to abrogate off-target effects and immunostimulation caused by siRNAs. There is an in-depth discussion on various issues related to the (1) mechanisms of RNAi, (2) methods of siRNA production, (3) barriers to RNAi-based therapies, (4) biodistribution, (5) design of siRNA molecules, (6) chemical modification and bioconjugation, (7) complex formation with lipids and polymers, (8) encapsulation into lipid particles, and (9) target specificity for enhanced therapeutic effectiveness. PMID:17329355

Quantum dots in biomedical applications: advances and challenges

NASA Astrophysics Data System (ADS)

Cinteza, Ludmila Otilia

2010-09-01

In the past two decades, nanotechnology has made great progress in generating novel materials with superior properties. Quantum dots (QDs) are an example of such materials. With unique optical properties, they have proven to be useful in a wide range of applications in life sciences, especially as a better alternative to overcome the shortcomings of conventional fluorophores. Current progress in the synthesis of biocompatible QDs allows for the possibility of producing a large variety of semiconductor nanocrystals in terms of size, surface functionality, bioconjugation, and targeting facilities. Strategies to enhance the water-dispersibility and biocompatibility of these nanoparticles have been developed, involving various encapsulation techniques and surface functionalization. The major obstacle in the clinical use of QDs remains their toxicity, and the systematic investigation on harmful effects of QDs both to humans and to the environment has become critical. Many examples of the experimental use of QDs prove their far-reaching potential for the study of intracellular processes at the molecular level, high resolution cellular imaging, and in vivo observation of cell trafficking. Biosensing methods based on QD bioconjugates proved to be successful in rapid detection of pathogens, and significant improvements are expected in early cancer diagnostic, non-conventional therapy of cancer and neurodegenerative diseases.

Development of anti-HER2 conjugated ICG-loaded polymeric nanoparticles for targeted optical imaging of ovarian cancer

NASA Astrophysics Data System (ADS)

Bahmani, Baharak; Vullev, Valentine; Anvari, Bahman

2012-03-01

Targeted delivery of therapeutic and imaging agents using surface modified nanovectors has been explored immensely in recent years. The growing demand for site-specific and efficient delivery of nanovectors entails stable surface conjugation of targeting moieties. We have developed a polymeric nanocapsule doped with Indocyanine green (ICG) with potential for targeted and deep tissue optical imaging and phototherapy. Our ICG-loaded nanocapsules (ICG-NCs) have potential for covalent coupling of various targeting moieties and materials due to presence of amine groups on the surface. Here, we covalently bioconjugate polyethylene glycol(PEG)-coated ICG-NCs with monoclonal antibody against HER2 through reductive amination-mediated procedures. The irreversible and stable bonds are formed between anti- EGFR and aldehyde termini of PEG chains on the surface of ICG-NCs. We confirm the uptake of conjugated ICG-NCs by ovarian cancer cells over-expressing HER2 using fluorescent confocal microscopy. The proposed process for covalent attachment of anti-HER2 to PEGylated ICG-NCs can be used as a methodology for bioconjugation of various antibodies to such nano-constrcuts, and provides the capability to use these optically active nano-probes for targeted optical imaging of ovarian and other cancer types.

Amphetamine Paradoxically Augments Exocytotic Dopamine Release and Phasic Dopamine Signals

PubMed Central

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

2013-01-01

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

ILLICIT DOPAMINE TRANSIENTS: RECONCILING ACTIONS OF ABUSED DRUGS

PubMed Central

Covey, Dan P.; Roitman, Mitchell F.; Garris, Paul A.

2014-01-01

Phasic increases in brain dopamine are required for cue-directed reward seeking. While compelling within the framework of appetitive behavior, the view that illicit drugs hijack reward circuits by hyper-activating these dopamine transients is inconsistent with established psychostimulant pharmacology. However, recent work reclassifying amphetamine (AMPH), cocaine, and other addictive dopamine-transporter inhibitors (DAT-Is) supports transient hyper-activation as a unifying hypothesis of abused drugs. We argue here that reclassification also identifies generating burst firing by dopamine neurons as a keystone action. Unlike natural rewards, which are processed by sensory systems, drugs act directly on the brain. Consequently, to mimic natural reward and exploit reward circuits, dopamine transients must be elicited de novo. Of available drug targets, only burst firing achieves this essential outcome. PMID:24656971

Epistasis between dopamine regulating genes identifies a nonlinear response of the human hippocampus during memory tasks.

PubMed

Bertolino, Alessandro; Di Giorgio, Annabella; Blasi, Giuseppe; Sambataro, Fabio; Caforio, Grazia; Sinibaldi, Lorenzo; Latorre, Valeria; Rampino, Antonio; Taurisano, Paolo; Fazio, Leonardo; Romano, Raffaella; Douzgou, Sofia; Popolizio, Teresa; Kolachana, Bhaskar; Nardini, Marcello; Weinberger, Daniel R; Dallapiccola, Bruno

2008-08-01

Dopamine modulation of neuronal activity in prefrontal cortex maps to an inverted U-curve. Dopamine is also an important factor in regulation of hippocampal mediated memory processing. Here, we investigated the effect of genetic variation of dopamine inactivation via catechol-O-methyltransferase (COMT) and the dopamine transporter (DAT) on hippocampal activity in healthy humans during different memory conditions. Using blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in 82 subjects matched for a series of demographic and genetic variables, we studied the effect of the COMT valine (Val)(158)methionine (Met) and the DAT 3' variable number tandem repeat (VNTR) polymorphisms on function of the hippocampus during encoding of recognition memory and during working memory. Our results consistently demonstrated a double dissociation so that DAT 9-repeat carrier alleles modulated activity in the hippocampus in the exact opposite direction of DAT 10/10-repeat alleles based on COMT Val(158)Met genotype during different memory conditions. Similar results were evident in ventrolateral and dorsolateral prefrontal cortex. These findings suggest that genetically determined dopamine signaling during memory processing maps to a nonlinear relationship also in the hippocampus. Our data also demonstrate in human brain epistasis of two genes implicated in dopamine signaling on brain activity during different memory conditions.

Different patterns of nuclear and mitochondrial penetration by the G3 PAMAM dendrimer and its biotin–pyridoxal bioconjugate BC-PAMAM in normal and cancer cells in vitro

PubMed Central

Uram, Łukasz; Szuster, Magdalena; Filipowicz, Aleksandra; Gargasz, Krzysztof; Wołowiec, Stanisław; Wałajtys-Rode, Elżbieta

2015-01-01

The intracellular localization and colocalization of a fluorescently labeled G3 amine-terminated cationic polyamidoamine (PAMAM) dendrimer and its biotin–pyridoxal (BC-PAMAM) bioconjugate were investigated in a concentration-dependent manner in normal human fibroblast (BJ) and squamous epithelial carcinoma (SCC-15) cell lines. After 24 hours treatment, both cell lines revealed different patterns of intracellular dendrimer accumulation depending on their cytotoxic effects. Cancer cells exhibited much higher (20-fold) tolerance for native PAMAM treatment than fibroblasts, whereas BC-PAMAM was significantly toxic only for fibroblasts at 50 µM concentration. Fibroblasts accumulated the native and bioconjugated dendrimers in a concentration-dependent manner at nontoxic range of concentration, with significantly lower bioconjugate loading. After reaching the cytotoxicity level, fluorescein isothiocyanate-PAMAM accumulation remains at high, comparable level. In cancer cells, native PAMAM loading at higher, but not cytotoxic concentrations, was kept at constant level with a sharp increase at toxic concentration. Mander’s coefficient calculated for fibroblasts and cancer cells confirmed more efficient native PAMAM penetration as compared to BC-PAMAM. Significant differences in nuclear dendrimer penetration were observed for both cell lines. In cancer cells, PAMAM signals amounted to ~25%–35% of the total nuclei area at all investigated concentrations, with lower level (15%–25%) observed for BC-PAMAM. In fibroblasts, the dendrimer nuclear signal amounted to 15% at nontoxic and up to 70% at toxic concentrations, whereas BC-PAMAM remained at a lower concentration-dependent level (0.3%–20%). Mitochondrial localization of PAMAM and BC-PAMAM revealed similar patterns in both cell lines, depending on the extracellular dendrimer concentration, and presented significantly lower signals from BC-PAMAM, which correlated well with the cytotoxicity. PMID:26379435

Dopamine neurons in culture express VGLUT2 explaining their capacity to release glutamate at synapses in addition to dopamine.

PubMed

Dal Bo, Gregory; St-Gelais, Fannie; Danik, Marc; Williams, Sylvain; Cotton, Mathieu; Trudeau, Louis-Eric

2004-03-01

Dopamine neurons have been suggested to use glutamate as a cotransmitter. To identify the basis of such a phenotype, we have examined the expression of the three recently identified vesicular glutamate transporters (VGLUT1-3) in postnatal rat dopamine neurons in culture. We found that the majority of isolated dopamine neurons express VGLUT2, but not VGLUT1 or 3. In comparison, serotonin neurons express only VGLUT3. Single-cell RT-PCR experiments confirmed the presence of VGLUT2 mRNA in dopamine neurons. Arguing for phenotypic heterogeneity among axon terminals, we find that only a proportion of terminals established by dopamine neurons are VGLUT2-positive. Taken together, our results provide a basis for the ability of dopamine neurons to release glutamate as a cotransmitter. A detailed analysis of the conditions under which DA neurons gain or loose a glutamatergic phenotype may provide novel insight into pathophysiological processes that underlie diseases such as schizophrenia, Parkinson's disease and drug dependence.

Neuronal Depolarization Drives Increased Dopamine Synaptic Vesicle Loading via VGLUT.

PubMed

Aguilar, Jenny I; Dunn, Matthew; Mingote, Susana; Karam, Caline S; Farino, Zachary J; Sonders, Mark S; Choi, Se Joon; Grygoruk, Anna; Zhang, Yuchao; Cela, Carolina; Choi, Ben Jiwon; Flores, Jorge; Freyberg, Robin J; McCabe, Brian D; Mosharov, Eugene V; Krantz, David E; Javitch, Jonathan A; Sulzer, David; Sames, Dalibor; Rayport, Stephen; Freyberg, Zachary

2017-08-30

The ability of presynaptic dopamine terminals to tune neurotransmitter release to meet the demands of neuronal activity is critical to neurotransmission. Although vesicle content has been assumed to be static, in vitro data increasingly suggest that cell activity modulates vesicle content. Here, we use a coordinated genetic, pharmacological, and imaging approach in Drosophila to study the presynaptic machinery responsible for these vesicular processes in vivo. We show that cell depolarization increases synaptic vesicle dopamine content prior to release via vesicular hyperacidification. This depolarization-induced hyperacidification is mediated by the vesicular glutamate transporter (VGLUT). Remarkably, both depolarization-induced dopamine vesicle hyperacidification and its dependence on VGLUT2 are seen in ventral midbrain dopamine neurons in the mouse. Together, these data suggest that in response to depolarization, dopamine vesicles utilize a cascade of vesicular transporters to dynamically increase the vesicular pH gradient, thereby increasing dopamine vesicle content. Copyright © 2017 Elsevier Inc. All rights reserved.

Neuronal Depolarization Drives Increased Dopamine Synaptic Vesicle Loading via VGLUT

PubMed Central

Aguilar, Jenny I.; Dunn, Matthew; Mingote, Susana; Karam, Caline S.; Farino, Zachary J.; Sonders, Mark S.; Choi, Se Joon; Grygoruk, Anna; Zhang, Yuchao; Cela, Carolina; Choi, Ben Jiwon; Flores, Jorge; Freyberg, Robin J.; McCabe, Brian D.; Mosharov, Eugene V.; Krantz, David E.; Javitch, Jonathan A.; Sulzer, David; Sames, Dalibor; Rayport, Stephen; Freyberg, Zachary

2017-01-01

SUMMARY The ability of presynaptic dopamine terminals to tune neurotransmitter release to meet the demands of neuronal activity is critical to neurotransmission. Although vesicle content has been assumed to be static, in vitro data increasingly suggest that cell activity modulates vesicle content. Here, we use a coordinated genetic, pharmacological, and imaging approach in Drosophila to study the presynaptic machinery responsible for these vesicular processes in vivo. We show that cell depolarization increases synaptic vesicle dopamine content prior to release via vesicular hyperacidification. This depolarization-induced hyperacidification is mediated by the vesicular glutamate transporter (VGLUT). Remarkably, both depolarization-induced dopamine vesicle hyperacidification and its dependence on VGLUT2 are seen in ventral midbrain dopamine neurons in the mouse. Together, these data suggest that in response to depolarization, dopamine vesicles utilize a cascade of vesicular transporters to dynamically increase the vesicular pH gradient, thereby increasing dopamine vesicle content. PMID:28823729

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

PubMed

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

2017-03-01

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

Aberrant mesolimbic dopamine-opiate interaction in obesity.

PubMed

Tuominen, Lauri; Tuulari, Jetro; Karlsson, Henry; Hirvonen, Jussi; Helin, Semi; Salminen, Paulina; Parkkola, Riitta; Hietala, Jarmo; Nuutila, Pirjo; Nummenmaa, Lauri

2015-11-15

Dopamine and opioid neurotransmitter systems share many functions such as regulation of reward and pleasure. μ-Opioid receptors (MOR) modulate the mesolimbic dopamine system in ventral tegmental area and striatum, key areas implicated in reward. We hypothesized that dopamine and opioid receptor availabilities correlate in vivo and that this correlation is altered in obesity, a disease with altered reward processing. Twenty lean females (mean BMI 22) and 25 non-binge eating morbidly obese females (mean BMI 41) underwent two positron emission tomography scans with [(11)C]carfentanil and [(11)C]raclopride to measure the MOR and dopamine D2 receptor (DRD2) availability, respectively. In lean subjects, the MOR and DRD2 availabilities were positively associated in the ventral striatum (r=0.62, p=0.003) and dorsal caudate nucleus (r=0.62, p=0.004). Moreover, DRD2 availability in the ventral striatum was associated with MOR availability in other regions of the reward circuitry, particularly in the ventral tegmental area. In morbidly obese subjects, this receptor interaction was significantly weaker in ventral striatum but unaltered in the caudate nucleus. Finally, the association between DRD2 availability in the ventral striatum and MOR availability in the ventral tegmental area was abolished in the morbidly obese. The study demonstrates a link between DRD2 and MOR availabilities in living human brain. This interaction is selectively disrupted in mesolimbic dopamine system in morbid obesity. We propose that interaction between the dopamine and opioid systems is a prerequisite for normal reward processing and that disrupted cross-talk may underlie altered reward processing in obesity. Copyright © 2015 Elsevier Inc. All rights reserved.

Interactions of iron, dopamine and neuromelanin pathways in brain aging and Parkinson's disease.

PubMed

Zucca, Fabio A; Segura-Aguilar, Juan; Ferrari, Emanuele; Muñoz, Patricia; Paris, Irmgard; Sulzer, David; Sarna, Tadeusz; Casella, Luigi; Zecca, Luigi

2017-08-01

There are several interrelated mechanisms involving iron, dopamine, and neuromelanin in neurons. Neuromelanin accumulates during aging and is the catecholamine-derived pigment of the dopamine neurons of the substantia nigra and norepinephrine neurons of the locus coeruleus, the two neuronal populations most targeted in Parkinson's disease. Many cellular redox reactions rely on iron, however an altered distribution of reactive iron is cytotoxic. In fact, increased levels of iron in the brain of Parkinson's disease patients are present. Dopamine accumulation can induce neuronal death; however, excess dopamine can be removed by converting it into a stable compound like neuromelanin, and this process rescues the cell. Interestingly, the main iron compound in dopamine and norepinephrine neurons is the neuromelanin-iron complex, since neuromelanin is an effective metal chelator. Neuromelanin serves to trap iron and provide neuronal protection from oxidative stress. This equilibrium between iron, dopamine, and neuromelanin is crucial for cell homeostasis and in some cellular circumstances can be disrupted. Indeed, when neuromelanin-containing organelles accumulate high load of toxins and iron during aging a neurodegenerative process can be triggered. In addition, neuromelanin released by degenerating neurons activates microglia and the latter cause neurons death with further release of neuromelanin, then starting a self-propelling mechanism of neuroinflammation and neurodegeneration. Considering the above issues, age-related accumulation of neuromelanin in dopamine neurons shows an interesting link between aging and neurodegeneration. Copyright © 2015 Elsevier Ltd. All rights reserved.

Illicit dopamine transients: reconciling actions of abused drugs.

PubMed

Covey, Dan P; Roitman, Mitchell F; Garris, Paul A

2014-04-01

Phasic increases in brain dopamine are required for cue-directed reward seeking. Although compelling within the framework of appetitive behavior, the view that illicit drugs hijack reward circuits by hyperactivating these dopamine transients is inconsistent with established psychostimulant pharmacology. However, recent work reclassifying amphetamine (AMPH), cocaine, and other addictive dopamine-transporter inhibitors (DAT-Is) supports transient hyperactivation as a unifying hypothesis of abused drugs. We argue here that reclassification also identifies generating burst firing by dopamine neurons as a keystone action. Unlike natural rewards, which are processed by sensory systems, drugs act directly on the brain. Consequently, to mimic natural rewards and exploit reward circuits, dopamine transients must be elicited de novo. Of available drug targets, only burst firing achieves this essential outcome. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of dopaminergic modulation on electrophysiological brain response to affective stimuli.

PubMed

Franken, Ingmar H A; Nijs, Ilse; Pepplinkhuizen, Lolke

2008-01-01

Several theoretical accounts of the role of dopamine suggest that dopamine has an influence on the processing of affective stimuli. There is some indirect evidence for this from studies showing an association between the treatment with dopaminergic agents and self-reported affect. We addressed this issue directly by examining the electrophysiological correlates of affective picture processing during a single-dose treatment with a dopamine D2 agonist (bromocriptine), a dopamine D2 antagonist (haloperidol), and a placebo. We compared early and late event-related brain potentials (ERPs) that have been associated with affective processing in the three medication treatment conditions in a randomized double-blind crossover design amongst healthy males. In each treatment condition, subjects attentively watched neutral, pleasant, and unpleasant pictures while ERPs were recorded. Results indicate that neither bromocriptine nor haloperidol has a selective effect on electrophysiological indices of affective processing. In concordance with this, no effects of dopaminergic modulation on self-reported positive or negative affect was observed. In contrast, bromocriptine decreased overall processing of all stimulus categories regardless of their affective content. The results indicate that dopaminergic D2 receptors do not seem to play a crucial role in the selective processing of affective visual stimuli.

Dopamine modulates reward system activity during subconscious processing of sexual stimuli.

PubMed

Oei, Nicole Y L; Rombouts, Serge Arb; Soeter, Roelof P; van Gerven, Joop M; Both, Stephanie

2012-06-01

Dopaminergic medication influences conscious processing of rewarding stimuli, and is associated with impulsive-compulsive behaviors, such as hypersexuality. Previous studies have shown that subconscious subliminal presentation of sexual stimuli activates brain areas known to be part of the 'reward system'. In this study, it was hypothesized that dopamine modulates activation in key areas of the reward system, such as the nucleus accumbens, during subconscious processing of sexual stimuli. Young healthy males (n=53) were randomly assigned to two experimental groups or a control group, and were administered a dopamine antagonist (haloperidol), a dopamine agonist (levodopa), or placebo. Brain activation was assessed during a backward-masking task with subliminally presented sexual stimuli. Results showed that levodopa significantly enhanced the activation in the nucleus accumbens and dorsal anterior cingulate when subliminal sexual stimuli were shown, whereas haloperidol decreased activations in those areas. Dopamine thus enhances activations in regions thought to regulate 'wanting' in response to potentially rewarding sexual stimuli that are not consciously perceived. This running start of the reward system might explain the pull of rewards in individuals with compulsive reward-seeking behaviors such as hypersexuality and patients who receive dopaminergic medication.

PSMA-targeted bispecific Fab conjugates that engage T cells.

PubMed

Patterson, James T; Isaacson, Jason; Kerwin, Lisa; Atassi, Ghazi; Duggal, Rohit; Bresson, Damien; Zhu, Tong; Zhou, Heyue; Fu, Yanwen; Kaufmann, Gunnar F

2017-12-15

Bioconjugate formats provide alternative strategies for antigen targeting with bispecific antibodies. Here, PSMA-targeted Fab conjugates were generated using different bispecific formats. Interchain disulfide bridging of an αCD3 Fab enabled installation of either the PSMA-targeting small molecule DUPA (SynFab) or the attachment of an αPSMA Fab (BisFab) by covalent linkage. Optimization of the reducing conditions was critical for selective interchain disulfide reduction and good bioconjugate yield. Activity of αPSMA/CD3 Fab conjugates was tested by in vitro cytotoxicity assays using prostate cancer cell lines. Both bispecific formats demonstrated excellent potency and antigen selectivity. Copyright © 2017. Published by Elsevier Ltd.

Noncharged and Charged Monodendronised Perylene Bisimides as Highly Fluorescent Labels and their Bioconjugates.

PubMed

Huth, Katharina; Heek, Timm; Achazi, Katharina; Kühne, Christian; Urner, Leonhard H; Pagel, Kevin; Dernedde, Jens; Haag, Rainer

2017-04-06

A series of water-soluble, hydroxylated and sulphated, polyglycerol (PG) dendronised, monofunctional perylene bisimides (PBIs) were synthesised in three generations. Their photophysical properties were determined by absorption and emission spectroscopy and their suitability as potential biolabels examined by biological in vitro studies after bioconjugation. It could be shown that the photophysical properties of the PBI labels can be improved by increasing the sterical demand and ionic charge of the attached dendron. Thereby, charged labels show superior suppression of aggregation over charge neutral labels owing to electrostatic repulsion forces on the PG-dendron. The ionic charges also enabled a reduction in dendron generation while retaining the labels' outstanding fluorescence quantum yields (FQYs) up to 100 %. These core-unsubstituted perylene derivatives were successfully applied as fluorescent labels upon bioconjugation to the therapeutic antibody cetuximab. The dye-antibody conjugates showed a strongly enhanced aggregation tendency compared to the corresponding free dyes. Biological evaluation by receptor-binding, cellular uptake, and cytotoxicity studies revealed that labelling did not affect the antibody's function, which renders the noncharged and charged dendronised PBIs suitable candidates as fluorescent labels in biological imaging. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ligand Assisted Stabilization of Fluorescence Nanoparticles; an Insight on the Fluorescence Characteristics, Dispersion Stability and DNA Loading Efficiency of Nanoparticles.

PubMed

Rhouati, Amina; Hayat, Akhtar; Mishra, Rupesh K; Bueno, Diana; Shahid, Shakir Ahmad; Muñoz, Roberto; Marty, Jean Louis

2016-07-01

This work reports on the ligand assisted stabilization of Fluospheres® carboxylate modified nanoparticles (FCMNPs), and subsequently investigation on the DNA loading capacity and fluorescence response of the modified particles. The designed fluorescence bioconjugate was characterized with enhanced fluorescence characteristics, good stability and large surface area with high DNA loading efficiency. For comparison purpose, bovine serum albumin (BSA) and polyethylene glycol (PEG) with three different length strands were used as cross linkers to modify the particles, and their DNA loading capacity and fluorescence characteristics were investigated. By comparing the performance of the particles, we found that the most improved fluorescence characteristics, enhanced DNA loading and high dispersion stability were obtained, when employing PEG of long spacer arm length. The designed fluorescence bioconjugate was observed to maintain all its characteristics under varying pH over an extended period of time. These types of bioconjugates are in great demand for fluorescence imaging and in vivo fluorescence biomedical application, especially when most of the as synthesized fluorescence particles cannot withstand to varying in vivo physiological conditions with decreases in fluorescence response and DNA loading efficiency.

Covalent protein-oligonucleotide conjugates by copper-free click reaction

PubMed Central

Khatwani, Santoshkumar L.; Mullen, Daniel G.; Hast, Michael A.; Beese, Lorena S.; Distefano, Mark D.; Taton, T. Andrew

2013-01-01

Covalent protein-oligodeoxynucleotide (protein-ODN) conjugates are useful in a number of biological applications, but synthesizing discrete conjugates—where the connection between the two components is at a defined location in both the protein and the ODN—under mild conditions with significant yield can be a challenge. In this article, we demonstrate a strategy for synthesizing discrete protein-ODN conjugates using strain-promoted azide-alkyne [3+2] cycloaddition (SPAAC, a copper-free “click” reaction). Azide-functionalized proteins, prepared by enzymatic prenylation of C-terminal CVIA tags with synthetic azidoprenyl diphosphates, were “clicked” to ODNs that had been modified with a strained dibenzocyclooctyne (DIBO-ODN). The resulting protein-ODN conjugates were purified and characterized by size-exclusion chromatography and gel electrophoresis. We find that the yields and reaction times of the SPAAC bioconjugation reactions are comparable to those previously reported for copper-catalyzed azide-alkyne [3+2] cycloaddition (CuAAC) bioconjugation, but require no catalyst. The same SPAAC chemistry was used to immobilize azide-modified proteins onto surfaces, using surface-bound DIBO-ODN as a heterobifunctional linker. Cu-free click bioconjugation of proteins to ODNs is a simple and versatile alternative to Cu-catalyzed click methods. PMID:22682299

Optimising the synthesis, polymer membrane encapsulation and photoreduction performance of Ru(II)- and Ir(III)-bis(terpyridine) cytochrome c bioconjugates.

PubMed

Hvasanov, David; Mason, Alexander F; Goldstein, Daniel C; Bhadbhade, Mohan; Thordarson, Pall

2013-07-28

Ruthenium(II) and iridium(III) bis(terpyridine) complexes were prepared with maleimide functionalities in order to site-specifically modify yeast iso-1 cytochrome c possessing a single cysteine residue available for modification (CYS102). Single X-ray crystal structures were solved for aniline and maleimide Ru(II) 3 and Ru(II) 4, respectively, providing detailed structural detail of the complexes. Light-activated bioconjugates prepared from Ru(II) 4 in the presence of tris(2-carboxyethyl)-phosphine (TCEP) significantly improved yields from 6% to 27%. Photoinduced electron transfer studies of Ru(II)-cyt c in bulk solution and polymer membrane encapsulated specimens were performed using EDTA as a sacrificial electron donor. It was found that membrane encapsulation of Ru(II)-cyt c in PS140-b-PAA48 resulted in a quantum efficiency of 1.1 ± 0.3 × 10(-3), which was a two-fold increase relative to the bulk. Moreover, Ir(III)-cyt c bioconjugates showed a quantum efficiency of 3.8 ± 1.9 × 10(-1), equivalent to a ∼640-fold increase relative to bulk Ru(II)-cyt c.

The Neurobiology of Opiate Motivation

PubMed Central

Ting-A-Kee, Ryan; van der Kooy, Derek

2012-01-01

Opiates are a highly addictive class of drugs that have been reported to possess both dopamine-dependent and dopamine-independent rewarding properties. The search for how, if at all, these distinct mechanisms of motivation are related is of great interest in drug addiction research. Recent electrophysiological, molecular, and behavioral work has greatly improved our understanding of this process. In particular, the signaling properties of GABAA receptors located on GABA neurons in the ventral tegmental area (VTA) appear to be crucial to understanding the interplay between dopamine-dependent and dopamine-independent mechanisms of opiate motivation. PMID:23028134

Mutation of Drosophila dopamine receptor DopR leads to male-male courtship behavior.

PubMed

Chen, Bin; Liu, He; Ren, Jing; Guo, Aike

2012-07-06

In Drosophila, dopamine plays important roles in many biological processes as a neuromodulator. Previous studies showed that dopamine level could affect fly courtship behaviors. Disturbed dopamine level leads to abnormal courtship behavior in two different ways. Dopamine up-regulation induces male-male courtship behavior, while down-regulation of dopamine level results in increased sexual attractiveness of males towards other male flies. Until now, the identity of the dopamine receptor involved in this abnormal male-male courtship behavior remains unknown. Here we used genetic approaches to investigate the role of dopamine receptors in fly courtship behavior. We found that a dopamine D1-like receptor, DopR, was involved in fly courtship behavior. DopR mutant male flies display male-male courtship behavior. This behavior is mainly due to the male's increased propensity to court other males. Expression of functional DopR successfully rescued this mutant phenotype. Knock-down of D2-like receptor D2R and another D1-like receptor, DAMB, did not induce male-male courtship behavior, indicating the receptor-type specificity of this phenomenon. Our findings provide insight into a possible link between dopamine level disturbance and the induced male-male courtship behavior. Copyright © 2012 Elsevier Inc. All rights reserved.

Orbitofrontal Dopamine Depletion Upregulates Caudate Dopamine and Alters Behavior via Changes in Reinforcement Sensitivity

PubMed Central

Cardinal, R. N.; Rygula, R.; Hong, Y. T.; Fryer, T. D.; Sawiak, S. J.; Ferrari, V.; Cockcroft, G.; Aigbirhio, F. I.; Robbins, T. W.; Roberts, A. C.

2014-01-01

Schizophrenia is associated with upregulation of dopamine (DA) release in the caudate nucleus. The caudate has dense connections with the orbitofrontal cortex (OFC) via the frontostriatal loops, and both areas exhibit pathophysiological change in schizophrenia. Despite evidence that abnormalities in dopaminergic neurotransmission and prefrontal cortex function co-occur in schizophrenia, the influence of OFC DA on caudate DA and reinforcement processing is poorly understood. To test the hypothesis that OFC dopaminergic dysfunction disrupts caudate dopamine function, we selectively depleted dopamine from the OFC of marmoset monkeys and measured striatal extracellular dopamine levels (using microdialysis) and dopamine D2/D3 receptor binding (using positron emission tomography), while modeling reinforcement-related behavior in a discrimination learning paradigm. OFC dopamine depletion caused an increase in tonic dopamine levels in the caudate nucleus and a corresponding reduction in D2/D3 receptor binding. Computational modeling of behavior showed that the lesion increased response exploration, reducing the tendency to persist with a recently chosen response side. This effect is akin to increased response switching previously seen in schizophrenia and was correlated with striatal but not OFC D2/D3 receptor binding. These results demonstrate that OFC dopamine depletion is sufficient to induce striatal hyperdopaminergia and changes in reinforcement learning relevant to schizophrenia. PMID:24872570

Label-Free SERS Selective Detection of Dopamine and Serotonin Using Graphene-Au Nanopyramid Heterostructure.

PubMed

Wang, Pu; Xia, Ming; Liang, Owen; Sun, Ke; Cipriano, Aaron F; Schroeder, Thomas; Liu, Huinan; Xie, Ya-Hong

2015-10-20

Ultrasensitive detection and spatially resolved mapping of neurotransmitters, dopamine and serotonin, are critical to facilitate understanding brain functions and investigate the information processing in neural networks. In this work, we demonstrated single molecule detection of dopamine and serotonin using a graphene-Au nanopyramid heterostructure platform. The quasi-periodic Au structure boosts high-density and high-homogeneity hotspots resulting in ultrahigh sensitivity with a surface enhanced Raman spectroscopic (SERS) enhancement factor ∼10(10). A single layer graphene superimposed on a Au structure not only can locate SERS hot spots but also modify the surface chemistry to realize selective enhancement Raman yield. Dopamine and serotonin could be detected and distinguished from each other at 10(-10) M level in 1 s data acquisition time without any pretreatment and labeling process. Moreover, the heterostructure realized nanomolar detection of neurotransmitters in the presence of simulated body fluids. These findings represent a step forward in enabling in-depth studies of neurological processes including those closely related to brain activity mapping (BAM).

Circuit Analysis of a Drosophila Dopamine Type 2 Receptor That Supports Anesthesia-Resistant Memory.

PubMed

Scholz-Kornehl, Sabrina; Schwärzel, Martin

2016-07-27

Dopamine is central to reinforcement processing and exerts this function in species ranging from humans to fruit flies. It can do so via two different types of receptors (i.e., D1 or D2) that mediate either augmentation or abatement of cellular cAMP levels. Whereas D1 receptors are known to contribute to Drosophila aversive odor learning per se, we here show that D2 receptors are specific for support of a consolidated form of odor memory known as anesthesia-resistant memory. By means of genetic mosaicism, we localize this function to Kenyon cells, the mushroom body intrinsic neurons, as well as GABAergic APL neurons and local interneurons of the antennal lobes, suggesting that consolidated anesthesia-resistant memory requires widespread dopaminergic modulation within the olfactory circuit. Additionally, dopaminergic neurons themselves require D2R, suggesting a critical role in dopamine release via its recognized autoreceptor function. Considering the dual role of dopamine in balancing memory acquisition (proactive function of dopamine) and its "forgetting" (retroactive function of dopamine), our analysis suggests D2R as central player of either process. Dopamine provides different information; while it mediates reinforcement during the learning act (proactive function), it balances memory performance between two antithetic processes thereafter (retroactive function) (i.e., forgetting and augmentation). Such bidirectional design can also be found at level of dopamine receptors, where augmenting D1 and abating D2 receptors are engaged to balance cellular cAMP levels. Here, we report that consolidated anesthesia-resistant memory (ARM), but not other concomitant memory phases, are sensitive to bidirectional dopaminergic signals. By means of genetic mosaicism, we identified widespread dopaminergic modulation within the olfactory circuit that suggests nonredundant and reiterating functions of D2R in support of ARM. Our results oppose ARM to its concomitant memory phases that localize to mushroom bodies and propose a decentralized organization of consolidated ARM. Copyright © 2016 the authors 0270-6474/16/367936-10$15.00/0.

The Effects of Acute Dopamine Precursor Depletion on the Cognitive Control Functions of Performance Monitoring and Conflict Processing: An Event-Related Potential (ERP) Study.

PubMed

Larson, Michael J; Clayson, Peter E; Primosch, Mark; Leyton, Marco; Steffensen, Scott C

2015-01-01

Studies using medications and psychiatric populations implicate dopamine in cognitive control and performance monitoring processes. However, side effects associated with medication or studying psychiatric groups may confound the relationship between dopamine and cognitive control. To circumvent such possibilities, we utilized a randomized, double-blind, placebo-controlled, within-subjects design wherein participants were administered a nutritionally-balanced amino acid mixture (BAL) and an amino acid mixture deficient in the dopamine precursors tyrosine (TYR) and phenylalanine (PHE) on two separate occasions. Order of sessions was randomly assigned. Cognitive control and performance monitoring were assessed using response times (RT), error rates, the N450, an event-related potential (ERP) index of conflict monitoring, the conflict slow potential (conflict SP), an ERP index of conflict resolution, and the error-related negativity (ERN) and error positivity (Pe), ERPs associated with performance monitoring. Participants were twelve males who completed a Stroop color-word task while ERPs were collected four hours following acute PHE and TYR depletion (APTD) or balanced (BAL) mixture ingestion in two separate sessions. N450 and conflict SP ERP amplitudes significantly differentiated congruent from incongruent trials, but did not differ as a function of APTD or BAL mixture ingestion. Similarly, ERN and Pe amplitudes showed significant differences between error and correct trials that were not different between APTD and BAL conditions. Findings indicate that acute dopamine precursor depletion does not significantly alter cognitive control and performance monitoring ERPs. Current results do not preclude the role of dopamine in these processes, but suggest that multiple methods for dopamine-related hypothesis testing are needed.

The "Creative Right Brain" Revisited: Individual Creativity and Associative Priming in the Right Hemisphere Relate to Hemispheric Asymmetries in Reward Brain Function.

PubMed

Aberg, Kristoffer Carl; Doell, Kimberly C; Schwartz, Sophie

2017-10-01

The idea that creativity resides in the right cerebral hemisphere is persistent in popular science, but has been widely frowned upon by the scientific community due to little empirical support. Yet, creativity is believed to rely on the ability to combine remote concepts into novel and useful ideas, an ability which would depend on associative processing in the right hemisphere. Moreover, associative processing is modulated by dopamine, and asymmetries in dopamine functionality between hemispheres may imbalance the expression of their implemented cognitive functions. Here, by uniting these largely disconnected concepts, we hypothesize that relatively less dopamine function in the right hemisphere boosts creativity by releasing constraining effects of dopamine on remote associations. Indeed, participants with reduced neural responses in the dopaminergic system of the right hemisphere (estimated by functional MRI in a reward task with positive and negative feedback), displayed higher creativity (estimated by convergent and divergent tasks), and increased associative processing in the right hemisphere (estimated by a lateralized lexical decision task). Our findings offer unprecedented empirical support for a crucial and specific contribution of the right hemisphere to creativity. More importantly our study provides a comprehensive view on potential determinants of human creativity, namely dopamine-related activity and associative processing. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Presence and function of dopamine transporter (DAT) in stallion sperm: dopamine modulates sperm motility and acrosomal integrity.

PubMed

Urra, Javier A; Villaroel-Espíndola, Franz; 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.

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

Ventral tegmental area dopamine revisited: effects of acute and repeated stress

PubMed Central

Holly, Elizabeth N.; Miczek, Klaus A.

2015-01-01

Aversive events rapidly and potently excite certain dopamine neurons in the ventral tegmental area (VTA), promoting phasic increases in the medial prefrontal cortex and nucleus accumbens. This is in apparent contradiction to a wealth of literature demonstrating that most VTA dopamine neurons are strongly activated by reward and reward-predictive cues while inhibited by aversive stimuli. How can these divergent processes both be mediated by VTA dopamine neurons? The answer may lie within the functional and anatomical heterogeneity of the VTA. We focus on VTA heterogeneity in anatomy, neurochemistry, electrophysiology, and afferent/efferent connectivity. Second, recent evidence for a critical role of VTA dopamine neurons in response to both acute and repeated stress will be discussed. Understanding which dopamine neurons are activated by stress, the neural mechanisms driving the activation, and where these neurons project will provide valuable insight into how stress can promote psychiatric disorders associated with the dopamine system, such as addiction and depression. PMID:26676983

Surface functionalization of polyamide fiber via dopamine polymerization

NASA Astrophysics Data System (ADS)

Kuang, Xiao-Hui; Guan, Jin-Ping; Tang, Ren-Cheng; Chen, Guo-Qiang

2017-09-01

The oxidative polymerization of dopamine for the functional surface modification of textile fibers has drawn great attention. In this work, the functionalization of polyamide fiber via dopamine polymerization was studied with the aim of the fabrication of hydrophilic and antistatic surface. The conditions of dopamine application were first discussed in the absence of specific oxidants in terms of the apparent color depth of polyamide fiber. Dopamine concentration, pH and time were found to exert great impact on color depth. The highest color depth was achieved at pH 8.5. In the process of modification, polydopamine was deposited onto the surface of polyamide fiber. The modified polyamide fiber displayed a yellowish brown color with excellent wash and light color fastness, and exhibited good hydrophilic, UV protection and antistatic effects. A disadvantage of the present approach was the slow rate of dopamine polymerization and functionalization.

Dopamine and the Management of Attentional Resources: Genetic Markers of Striatal D2 Dopamine Predict Individual Differences in the Attentional Blink

ERIC Educational Resources Information Center

Colzato, Lorenza S.; Slagter, Heleen A.; de Rover, Mischa; Hommel, Bernhard

2011-01-01

The attentional blink (AB)--a deficit in reporting the second of two target stimuli presented in close succession in a rapid sequence of distracters--has been related to processing limitations in working memory. Given that dopamine (DA) plays a crucial role working memory, the present study tested whether individual differences in the size of the…

fMRI Activation during Response Inhibition and Error Processing: The Role of the DAT1 Gene in Typically Developing Adolescents and Those Diagnosed with ADHD

ERIC Educational Resources Information Center

Braet, Wouter; Johnson, Katherine A.; Tobin, Claire T.; Acheson, Ruth; McDonnell, Caroline; Hawi, Ziarah; Barry, Edwina; Mulligan, Aisling; Gill, Michael; Bellgrove, Mark A.; Robertson, Ian H.; Garavan, Hugh

2011-01-01

The DAT1 gene codes for the dopamine transporter, which clears dopamine from the synaptic cleft, and a variant of this gene has previously been associated with compromised response inhibition in both healthy and clinical populations. This variant has also been associated with ADHD, a disorder that is characterised by disturbed dopamine function as…

A transient dopamine signal encodes subjective value and causally influences demand in an economic context

PubMed Central

Schelp, Scott A.; Pultorak, Katherine J.; Rakowski, Dylan R.; Gomez, Devan M.; Krzystyniak, Gregory; Das, Raibatak; Oleson, Erik B.

2017-01-01

The mesolimbic dopamine system is strongly implicated in motivational processes. Currently accepted theories suggest that transient mesolimbic dopamine release events energize reward seeking and encode reward value. During the pursuit of reward, critical associations are formed between the reward and cues that predict its availability. Conditioned by these experiences, dopamine neurons begin to fire upon the earliest presentation of a cue, and again at the receipt of reward. The resulting dopamine concentration scales proportionally to the value of the reward. In this study, we used a behavioral economics approach to quantify how transient dopamine release events scale with price and causally alter price sensitivity. We presented sucrose to rats across a range of prices and modeled the resulting demand curves to estimate price sensitivity. Using fast-scan cyclic voltammetry, we determined that the concentration of accumbal dopamine time-locked to cue presentation decreased with price. These data confirm and extend the notion that dopamine release events originating in the ventral tegmental area encode subjective value. Using optogenetics to augment dopamine concentration, we found that enhancing dopamine release at cue made demand more sensitive to price and decreased dopamine concentration at reward delivery. From these observations, we infer that value is decreased because of a negative reward prediction error (i.e., the animal receives less than expected). Conversely, enhancing dopamine at reward made demand less sensitive to price. We attribute this finding to a positive reward prediction error, whereby the animal perceives they received a better value than anticipated. PMID:29109253

Qualitative changes in ultrasonic vocalization in rats after unilateral dopamine depletion or haloperidol: A preliminary study

PubMed Central

Ciucci, Michelle; Ma, Teh-Sheng; Fox, Cynthia; Kane, Jacqueline; Ramig, Lorraine; Schallert, Timothy

2007-01-01

The sensorimotor speech/voice deficits associated with Parkinson Disease have been well-documented in humans. They are largely resistant to pharmacological and surgical treatment, but respond to intensive speech treatment. The mechanisms underlying this phenomenon are not well understood and are difficult to systematically test in humans. Thus we turn to the rat as a model. The purpose of this study is to compare the ultrasonic vocalization (USV) of rats in three conditions: control, haloperidol-induced transient dopamine depletion, and unilateral 6-hydroxydopamine (6-OHDA) induced moderately-severe degeneration of dopamine neurons. It was hypothesized that both dopamine-altered conditions would lead to a change in the features of the USV acoustic signal. Results demonstrated that bandwidth decreased in the dopamine-altered rats. This is the first study to document a degradation of the acoustic signal of frequency-modulated 50-kHz calls as a result of interfering with dopamine synaptic transmission in rats. The data suggest that mild transient dopamine depletion with haloperidol or even unilateral degeneration of dopamine neurons is associated with changes in the USV acoustic signal. Thus, dopaminergic dysfunction appears to influence USV production. This study provides a foundation to examine the role of dopamine in sensorimotor processes underlying USV production and potentially to explore treatments for dopamine deficiency-related impaired vocal outcome. PMID:17397940

Impaired contextual fear-conditioning in MAM rodent model of schizophrenia.

PubMed

Gill, Kathryn M; Miller, Sarah A; Grace, Anthony A

2018-05-01

The methylazoxymethanol acetate (MAM) rodent neurodevelopmental model of schizophrenia exhibits aberrant dopamine system activation attributed to hippocampal dysfunction. Context discrimination is a component of numerous behavioral and cognitive functions and relies on intact hippocampal processing. The present study explored context processing behaviors, along with dopamine system activation, during fear learning in the MAM model. Male offspring of dams treated with MAM (20mg/kg, i.p.) or saline on gestational day 17 were used for electrophysiological and behavioral experiments. Animals were tested on the immediate shock fear conditioning paradigm, with either different pre-conditioning contexts or varying amounts of context pre-exposure (0-10 sessions). Amphetamine-induced locomotor activity and dopamine neural activity was measured 1-week after fear conditioning. Saline, but not MAM animals, demonstrated enhanced fear responses following a single context pre-exposure in the conditioning context. One week following fear learning, saline rats with 2 or 7min of context pre-exposure prior to fear conditioning also demonstrated enhanced amphetamine-induced locomotor response relative to MAM animals. Dopamine neuron recordings showed fear learning-induced reductions in spontaneous dopamine neural activity in MAM rats that was further reduced by amphetamine. Apomorphine administration confirmed that reductions in dopamine neuron activity in MAM animals resulted from over excitation, or depolarization block. These data show a behavioral insensitivity to contextual stimuli in MAM rats that coincide with a less dynamic dopamine response after fear learning. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of Sulpiride on True and False Memories of Thematically Related Pictures and Associated Words in Healthy Volunteers

PubMed Central

Guarnieri, Regina V.; Ribeiro, Rafaela L.; de Souza, Altay A. Lino; Galduróz, José Carlos F.; Covolan, Luciene; Bueno, Orlando F. A.

2016-01-01

Episodic memory, working memory, emotional memory, and attention are subject to dopaminergic modulation. However, the potential role of dopamine on the generation of false memories is unknown. This study defined the role of the dopamine D2 receptor on true and false recognition memories. Twenty-four young, healthy volunteers ingested a single dose of placebo or 400 mg oral sulpiride, a dopamine D2-receptor antagonist, just before starting the recognition memory task in a randomized, double-blind, and placebo-controlled trial. The sulpiride group presented more false recognitions during visual and verbal processing than the placebo group, although both groups had the same indices of true memory. These findings demonstrate that dopamine D2 receptors blockade in healthy volunteers can specifically increase the rate of false recognitions. The findings fit well the two-process view of causes of false memories, the activation/monitoring failures model. PMID:27047394

Synthesis of sericin-based conjugates by click chemistry: enhancement of sunitinib bioavailability and cell membrane permeation.

PubMed

Scrivano, Luca; Iacopetta, Domenico; Sinicropi, Maria Stefania; Saturnino, Carmela; Longo, Pasquale; Parisi, Ortensia Ilaria; Puoci, Francesco

2017-11-01

Sericin is a natural protein that has been used in biomedical and pharmaceutical fields as raw material for polypeptide-based drug delivery systems (DDSs). In this paper, it has been employed as pharmaceutical biopolymer for the production of sunitinib-polypeptide conjugate. The synthesis has been carried out by simple click reaction in water, using the redox couple l-ascorbic acid/hydrogen peroxide as a free radical grafting initiator. The bioconjugate molecular weight (50 kDa < Mw < 75 kDa) was obtained by SDS-PAGE, while the spectroscopic characteristics have been studied in order to reveal the presence of grafted sunitinib. In both FT-IR and UV/Vis spectra, signals corresponding to sunitinib functional groups have been identified. Since sunitinib is an anticancer drug characterized by low bioavailability and low permeability, the bioconjugation aimed at their enhancement. In vitro studies demonstrated that bioavailability has been increased to almost 74%, compared with commercial formulation. Also cell membrane permeability has been augmented in in vitro tests, in which membrane models have been used to determine the lipid membrane/physiological fluid partition coefficient (Kp). The log(Kp) value of the bioconjugate was increased to over 4. This effect resulted in a three-fold decrease of IC 50 value against MCF-7 cells.

Flipped Phenyl Ring Orientations of Dopamine Binding with Human and Drosophila Dopamine Transporters: Remarkable Role of Three Nonconserved Residues.

PubMed

Yuan, Yaxia; Zhu, Jun; Zhan, Chang-Guo

2018-03-09

Molecular modeling and molecular dynamics simulations were performed in the present study to examine the modes of dopamine binding with human and Drosophila dopamine transporters (hDAT and dDAT). The computational data revealed flipped binding orientations of dopamine in hDAT and dDAT due to the major differences in three key residues (S149, G153, and A423 of hDAT vs A117, D121, and S422 of dDAT) in the binding pocket. These three residues dictate the binding orientation of dopamine in the binding pocket, as the aromatic ring of dopamine tends to take an orientation with both the para- and meta-hydroxyl groups being close to polar residues and away from nonpolar residues of the protein. The flipped binding orientations of dopamine in hDAT and dDAT clearly demonstrate a generally valuable insight concerning how the species difference could drastically affect the protein-ligand binding modes, demonstrating that the species difference, which is a factor rarely considered in early drug design stage, must be accounted for throughout the ligand/drug design and discovery processes in general.

Basal Ganglia, Dopamine and Temporal Processing: Performance on Three Timing Tasks on and off Medication in Parkinson's Disease

ERIC Educational Resources Information Center

Jones, Catherine R. G.; Malone, Tim J. L.; Dirnberger, Georg; Edwards, Mark; Jahanshahi, Marjan

2008-01-01

A pervasive hypothesis in the timing literature is that temporal processing in the milliseconds and seconds range engages the basal ganglia and is modulated by dopamine. This hypothesis was investigated by testing 12 patients with Parkinson's disease (PD), both "on" and "off" dopaminergic medication, and 20 healthy controls on three timing tasks.…

Dopamine Inactivation Efficacy Related to Functional DAT1 and COMT Variants Influences Motor Response Evaluation

PubMed Central

Bender, Stephan; Rellum, Thomas; Freitag, Christine; Resch, Franz; Rietschel, Marcella; Treutlein, Jens; Jennen-Steinmetz, Christine; Brandeis, Daniel; Banaschewski, Tobias; Laucht, Manfred

2012-01-01

Background Dopamine plays an important role in orienting, response anticipation and movement evaluation. Thus, we examined the influence of functional variants related to dopamine inactivation in the dopamine transporter (DAT1) and catechol-O-methyltransferase genes (COMT) on the time-course of motor processing in a contingent negative variation (CNV) task. Methods 64-channel EEG recordings were obtained from 195 healthy adolescents of a community-based sample during a continuous performance task (A-X version). Early and late CNV as well as motor postimperative negative variation were assessed. Adolescents were genotyped for the COMT Val158Met and two DAT1 polymorphisms (variable number tandem repeats in the 3′-untranslated region and in intron 8). Results The results revealed a significant interaction between COMT and DAT1, indicating that COMT exerted stronger effects on lateralized motor post-processing (centro-parietal motor postimperative negative variation) in homozygous carriers of a DAT1 haplotype increasing DAT1 expression. Source analysis showed that the time interval 500–1000 ms after the motor response was specifically affected in contrast to preceding movement anticipation and programming stages, which were not altered. Conclusions Motor slow negative waves allow the genomic imaging of dopamine inactivation effects on cortical motor post-processing during response evaluation. This is the first report to point towards epistatic effects in the motor system during response evaluation, i.e. during the post-processing of an already executed movement rather than during movement programming. PMID:22649558

Synthesis and in vitro biochemical evaluation of oxime bond-linked daunorubicin–GnRH-III conjugates developed for targeted drug delivery

PubMed Central

Schuster, Sabine; Biri-Kovács, Beáta; Szeder, Bálint; Farkas, Viktor; Buday, László; Szabó, Zsuzsanna; Halmos, Gábor

2018-01-01

Gonadotropin releasing hormone-III (GnRH-III), a native isoform of the human GnRH isolated from sea lamprey, specifically binds to GnRH receptors on cancer cells enabling its application as targeting moieties for anticancer drugs. Recently, we reported on the identification of a novel daunorubicin–GnRH-III conjugate (GnRH-III–[4Lys(Bu), 8Lys(Dau=Aoa)] with efficient in vitro and in vivo antitumor activity. To get a deeper insight into the mechanism of action of our lead compound, the cellular uptake was followed by confocal laser scanning microscopy. Hereby, the drug daunorubicin could be visualized in different subcellular compartments by following the localization of the drug in a time-dependent manner. Colocalization studies were carried out to prove the presence of the drug in lysosomes (early stage) and on its site of action (nuclei after 10 min). Additional flow cytometry studies demonstrated that the cellular uptake of the bioconjugate was inhibited in the presence of the competitive ligand triptorelin indicating a receptor-mediated pathway. For comparative purpose, six novel daunorubicin–GnRH-III bioconjugates have been synthesized and biochemically characterized in which 6Asp was replaced by D-Asp, D-Glu and D-Trp. In addition to the analysis of the in vitro cytostatic effect and cellular uptake, receptor binding studies with 125I-triptorelin as radiotracer and degradation of the GnRH-III conjugates in the presence of rat liver lysosomal homogenate have been performed. All derivatives showed high binding affinities to GnRH receptors and displayed in vitro cytostatic effects on HT-29 and MCF-7 cancer cells with IC50 values in a low micromolar range. Moreover, we found that the release of the active drug metabolite and the cellular uptake of the bioconjugates were strongly affected by the amino acid exchange which in turn had an impact on the antitumor activity of the bioconjugates. PMID:29719573

An Anatomical Basis for Opponent Process Mechanisms of Opiate Withdrawal

PubMed Central

Radke, Anna K.; Rothwell, Patrick E.; Gewirtz, Jonathan C.

2011-01-01

Opponent process theory predicts that the first step in the induction of drug withdrawal is the activation of reward-related circuitry. Using the acoustic startle reflex as a model of anxiety-like behavior in rats, we show the emergence of a negative affective state during withdrawal after direct infusion of morphine into the ventral tegmental area (VTA), the origin of the mesolimbic dopamine system. Potentiation of startle during withdrawal from systemic morphine exposure requires a decrease in opiate receptor stimulation in the VTA and can be relieved by administration of the dopamine receptor agonist apomorphine. Together, our results suggest that the emergence of anxiety during withdrawal from acute opiate exposure begins with activation of VTA mesolimbic dopamine circuitry, providing a mechanism for the opponent process view of withdrawal. PMID:21593338

A multifunctional hemin@metal-organic framework and its application to construct an electrochemical aptasensor for thrombin detection

NASA Astrophysics Data System (ADS)

Xie, Shunbi; Ye, Jiawei; Yuan, Yali; Chai, Yaqin; Yuan, Ruo

2015-10-01

A new type of multifunctional metal-organic framework (MOF) has been synthesized by encapsulating hemin into the nano-sized Fe-MIL-88 MOFs (hemin@MOFs) and first applied in an electrochemical aptasensor to detect thrombin (TB) with the aid of an enzyme for signal amplification. The gold nanoparticle functionalized hemin@MOFs (Au/hemin@MOFs) have not only simultaneously served as redox mediators and solid electrocatalysts, but have also been utilized as an ideal loading platform to immobilize a large number of biomolecules. In this aptasensor, Au/hemin@MOFs conjugated with glucose oxidase (GOD) and thrombin binding aptamer (TBA II) were used as the secondary aptamer bioconjugates (Au/hemin@MOF-TBA II-GOD bioconjugates), and TB was sandwiched between Au/hemin@MOF-TBA II-GOD bioconjugates and the amino-terminated TBA I which was self-assembled on the gold nanoparticle (AuNP) modified electrode. The GOD could oxidize glucose into gluconic acid accompanied by the generation of H2O2. The generated H2O2 on the electrode surface was further electrocatalyzed by hemin@MOFs to amplify the electrochemical signal of hemin contained in hemin@MOFs. Therefore, the synthesized hemin@MOFs represented a new paradigm for multifunctional materials since it combined three different functions including serving as catalysts, redox mediators and loading platforms within a single material. With such an ingenious design, a wide linear range of 0.0001 nM to 30 nM was acquired with a relatively low detection limit of 0.068 pM for TB detection.A new type of multifunctional metal-organic framework (MOF) has been synthesized by encapsulating hemin into the nano-sized Fe-MIL-88 MOFs (hemin@MOFs) and first applied in an electrochemical aptasensor to detect thrombin (TB) with the aid of an enzyme for signal amplification. The gold nanoparticle functionalized hemin@MOFs (Au/hemin@MOFs) have not only simultaneously served as redox mediators and solid electrocatalysts, but have also been utilized as an ideal loading platform to immobilize a large number of biomolecules. In this aptasensor, Au/hemin@MOFs conjugated with glucose oxidase (GOD) and thrombin binding aptamer (TBA II) were used as the secondary aptamer bioconjugates (Au/hemin@MOF-TBA II-GOD bioconjugates), and TB was sandwiched between Au/hemin@MOF-TBA II-GOD bioconjugates and the amino-terminated TBA I which was self-assembled on the gold nanoparticle (AuNP) modified electrode. The GOD could oxidize glucose into gluconic acid accompanied by the generation of H2O2. The generated H2O2 on the electrode surface was further electrocatalyzed by hemin@MOFs to amplify the electrochemical signal of hemin contained in hemin@MOFs. Therefore, the synthesized hemin@MOFs represented a new paradigm for multifunctional materials since it combined three different functions including serving as catalysts, redox mediators and loading platforms within a single material. With such an ingenious design, a wide linear range of 0.0001 nM to 30 nM was acquired with a relatively low detection limit of 0.068 pM for TB detection. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04532k

Breathing is affected by dopamine D2-like receptors in the basolateral amygdala.

PubMed

Sugita, Toshihisa; Kanamaru, Mitsuko; Iizuka, Makito; Sato, Kanako; Tsukada, Setsuro; Kawamura, Mitsuru; Homma, Ikuo; Izumizaki, Masahiko

2015-04-01

The precise mechanisms underlying how emotions change breathing patterns remain unclear, but dopamine is a candidate neurotransmitter in the process of emotion-associated breathing. We investigated whether basal dopamine release occurs in the basolateral amygdala (BLA), where sensory-related inputs are received and lead to fear or anxiety responses, and whether D1- and D2-like receptor antagonists affect breathing patterns and dopamine release in the BLA. Adult male mice (C57BL/6N) were perfused with artificial cerebrospinal fluid, a D1-like receptor antagonist (SCH 23390), or a D2-like receptor antagonist ((S)-(-)-sulpiride) through a microdialysis probe in the BLA. Respiratory variables were measured using a double-chamber plethysmograph. Dopamine release was measured by an HPLC. Perfusion of (S)-(-)-sulpiride in the BLA, not SCH 23390, specifically decreased respiratory rate without changes in local release of dopamine. These results suggest that basal dopamine release in the BLA, at least partially, increases respiratory rates only through post-synaptic D2-like receptors, not autoreceptors, which might be associated with emotional responses. Copyright © 2014 Elsevier B.V. All rights reserved.

Methamphetamine-induced alterations in monoamine transport: implications for neurotoxicity, neuroprotection and treatment.

PubMed

Volz, Trent J; Fleckenstein, Annette E; Hanson, Glen R

2007-04-01

To review studies delineating the neurotoxic effects of methamphetamine on monoamine transport in dopaminergic neurons of the striatum and nucleus accumbens. The scope of this review includes the English language dopamine transporter and vesicular monoamine transporter-2 primary literature to April 2006 identified by Pubmed, Science Citation Index and SciFinder Scholar literature searches. Changes in the function of the plasmalemmal dopamine transporter and the vesicular monoamine transporter-2 are key components of methamphetamine-induced persistent dopaminergic deficits. These deficits include persistent reductions in dopamine content, dopamine transporter density and tyrosine hydroxylase activity. The striatum is susceptible to these effects of methamphetamine while the nucleus accumbens is resistant. Differences in dopamine transporter density and activity, extracellular dopamine levels and antioxidant levels in these two brain regions may, in part, account for the resistance of the nucleus accumbens. These findings concerning the nature of methamphetamine-induced changes in plasmalemmal and vesicular dopamine transport have very important implications for drug targets and for understanding the etiology of dopaminergic neurodegenerative processes, such as those associated with methamphetamine addiction and Parkinson's disease.

The "highs and lows" of the human brain on dopaminergics: Evidence from neuropharmacology.

PubMed

Martins, Daniel; Mehta, Mitul A; Prata, Diana

2017-09-01

Rewards are appetitive events that elicit approach. Ground-breaking findings from neurophysiological experiments in animals, alongside neuropharmacology and neuroimaging research in human samples have identified dopamine as the main neurochemical messenger of global reward processing in the brain. However, dopamine's contribution to the different components of reward processing remains to be precisely defined. To facilitate the informed design and interpretation of reward studies in humans, we have systematically reviewed all existing human pharmacological studies investigating how drug manipulation of the dopamine system affects reward-related behaviour and its neural correlates. Pharmacological experiments in humans face methodological challenges in terms of the: 1) specificity and safety of the available drugs for administration in humans, 2) uncertainties about pre- or post-synaptic modes of action, and 3) possible interactions with inter-individual neuropsychological or genotypic variables. In order to circumvent some of these limitations, future research should rely on the combination of different levels of observation, in integrative pharmaco-genetics-neurobehavioral approaches, to more completely characterize dopamine's role in both general and modality-specific processing of reward. Copyright © 2017 Elsevier Ltd. All rights reserved.

Prefrontal Markers and Cognitive Performance Are Dissociated during Progressive Dopamine Lesion

PubMed Central

Wilson, Charles R. E.; Vezoli, Julien; Faraut, Maïlys C. M.; Leviel, Vincent; Knoblauch, Kenneth; Procyk, Emmanuel

2016-01-01

Dopamine is thought to directly influence the neurophysiological mechanisms of both performance monitoring and cognitive control—two processes that are critically linked in the production of adapted behaviour. Changing dopamine levels are also thought to induce cognitive changes in several neurological and psychiatric conditions. But the working model of this system as a whole remains untested. Specifically, although many researchers assume that changing dopamine levels modify neurophysiological mechanisms and their markers in frontal cortex, and that this in turn leads to cognitive changes, this causal chain needs to be verified. Using longitudinal recordings of frontal neurophysiological markers over many months during progressive dopaminergic lesion in non-human primates, we provide data that fail to support a simple interaction between dopamine, frontal function, and cognition. Feedback potentials, which are performance-monitoring signals sometimes thought to drive successful control, ceased to differentiate feedback valence at the end of the lesion, just before clinical motor threshold. In contrast, cognitive control performance and beta oscillatory markers of cognitive control were unimpaired by the lesion. The differing dynamics of these measures throughout a dopamine lesion suggests they are not all driven by dopamine in the same way. These dynamics also demonstrate that a complex non-linear set of mechanisms is engaged in the brain in response to a progressive dopamine lesion. These results question the direct causal chain from dopamine to frontal physiology and on to cognition. They imply that biomarkers of cognitive functions are not directly predictive of dopamine loss. PMID:27824858

Olfactory modulation by dopamine in the context of aversive learning

PubMed Central

Riffell, Jeffrey A.; Martin, Joshua P.; Gage, Stephanie L.; Nighorn, Alan J.

2012-01-01

The need to detect and process sensory cues varies in different behavioral contexts. Plasticity in sensory coding can be achieved by the context-specific release of neuromodulators in restricted brain areas. The context of aversion triggers the release of dopamine in the insect brain, yet the effects of dopamine on sensory coding are unknown. In this study, we characterize the morphology of dopaminergic neurons that innervate each of the antennal lobes (ALs; the first synaptic neuropils of the olfactory system) of the moth Manduca sexta and demonstrate with electrophysiology that dopamine enhances odor-evoked responses of the majority of AL neurons while reducing the responses of a small minority. Because dopamine release in higher brain areas mediates aversive learning we developed a naturalistic, ecologically inspired aversive learning paradigm in which an innately appetitive host plant floral odor is paired with a mimic of the aversive nectar of herbivorized host plants. This pairing resulted in a decrease in feeding behavior that was blocked when dopamine receptor antagonists were injected directly into the ALs. These results suggest that a transient dopaminergic enhancement of sensory output from the AL contributes to the formation of aversive memories. We propose a model of olfactory modulation in which specific contexts trigger the release of different neuromodulators in the AL to increase olfactory output to downstream areas of processing. PMID:22552185

Altered effect of dopamine transporter 3'UTR VNTR genotype on prefrontal and striatal function in schizophrenia.

PubMed

Prata, Diana P; Mechelli, Andrea; Picchioni, Marco M; Fu, Cynthia H Y; Toulopoulou, Timothea; Bramon, Elvira; Walshe, Muriel; Murray, Robin M; Collier, David A; McGuire, Philip

2009-11-01

The dopamine transporter plays a key role in the regulation of central dopaminergic transmission, which modulates cognitive processing. Disrupted dopamine function and impaired executive processing are robust features of schizophrenia. To examine the effect of a polymorphism in the dopamine transporter gene (the variable number of tandem repeats in the 3' untranslated region) on brain function during executive processing in healthy volunteers and patients with schizophrenia. We hypothesized that this variation would have a different effect on prefrontal and striatal activation in schizophrenia, reflecting altered dopamine function. Case-control study. Psychiatric research center. Eighty-five subjects, comprising 44 healthy volunteers (18 who were 9-repeat carriers and 26 who were 10-repeat homozygotes) and 41 patients with DSM-IV schizophrenia (18 who were 9-repeat carriers and 23 who were 10-repeat homozygotes). Regional brain activation during word generation relative to repetition in an overt verbal fluency task measured by functional magnetic resonance imaging. Main effects of genotype and diagnosis on activation and their interaction were estimated with analysis of variance in SPM5. Irrespective of diagnosis, the 10-repeat allele was associated with greater activation than the 9-repeat allele in the left anterior insula and right caudate nucleus. Trends for the same effect in the right insula and for greater deactivation in the rostral anterior cingulate cortex were also detected. There were diagnosis x genotype interactions in the left middle frontal gyrus and left nucleus accumbens, where the 9-repeat allele was associated with greater activation than the 10-repeat allele in patients but not controls. Insular, cingulate, and striatal function during an executive task is normally modulated by variation in the dopamine transporter gene. Its effect on activation in the dorsolateral prefrontal cortex and ventral striatum is altered in patients with schizophrenia. This may reflect altered dopamine function in these regions in schizophrenia.

Oscillatory subthalamic nucleus activity is modulated by dopamine during emotional processing in Parkinson's disease.

PubMed

Huebl, Julius; Spitzer, Bernhard; Brücke, Christof; Schönecker, Thomas; Kupsch, Andreas; Alesch, François; Schneider, Gerd-Helge; Kühn, Andrea A

2014-11-01

Dopaminergic denervation in Parkinson's disease (PD) leads to motor deficits but also depression, lack of motivation and apathy. These symptoms can be reversed by dopaminergic treatment, which may even lead to an increased hedonic tone in some patients with PD. Here, we tested the effects of dopamine on emotional processing as indexed by changes in local field potential (LFP) activity of the subthalamic nucleus (STN) in 28 PD patients undergoing deep brain stimulation. LFP activity from the STN was recorded after the administration of levodopa (ON group) or after overnight withdrawal of medication (OFF group) during presentation of an emotional picture-viewing task. Neutral and emotionally arousing pleasant and unpleasant stimuli were chosen from the International Affective Picture System. We found a double dissociation of the alpha band response depending on dopamine state and stimulus valence: dopamine enhanced the processing of pleasant stimuli, while activation during unpleasant stimuli was reduced, as indexed by the degree of desynchronization in the alpha frequency band. This pattern was reversed in the OFF state and more pronounced in the subgroup of non-depressed PD patients. Further, we found an early gamma band increase with unpleasant stimuli that occurred when ON but not OFF medication and was correlated with stimulus arousal. The late STN alpha band decrease is thought to represent active processing of sensory information. Our findings support the idea that dopamine enhances approach-related processes during late stimulus evaluation in PD. The early gamma band response may represent local encoding of increased attention, which varies as a function of stimulus arousal. Copyright © 2014 Elsevier Ltd. All rights reserved.

Environmental Enrichment, Performance, and Brain Injury in Male and Female Rats

DTIC Science & Technology

2004-01-01

neurodevelopmental disorders characterized by deficits in processing novel information (e.g., autism ). 141 Table 8. Summary of Major...stimulated locomotor activity, dopamine synthesis, and dopamine release. Neuropharmacology, 32, 885-893. Braff, D.L., Swerdlow, N.R., & Geyer, M.A

Dopamine reward prediction-error signalling: a two-component response

PubMed Central

Schultz, Wolfram

2017-01-01

Environmental stimuli and objects, including rewards, are often processed sequentially in the brain. Recent work suggests that the phasic dopamine reward prediction-error response follows a similar sequential pattern. An initial brief, unselective and highly sensitive increase in activity unspecifically detects a wide range of environmental stimuli, then quickly evolves into the main response component, which reflects subjective reward value and utility. This temporal evolution allows the dopamine reward prediction-error signal to optimally combine speed and accuracy. PMID:26865020

Enhanced peripheral dopamine impairs post-ischemic healing by suppressing angiotensin receptor type 1 expression in endothelial cells and inhibiting angiogenesis.

PubMed

Sarkar, Chandrani; Ganju, Ramesh K; Pompili, Vincent J; Chakroborty, Debanjan

2017-02-01

Increased circulating catecholamines have been linked with cardiovascular anomalies as well as with peripheral vascular diseases. Although the roles of epinephrine and norepinephrine have received considerable attention, the role of the other catecholamine, dopamine, has been less studied. Since dopamine is a potent endogenous inhibitor of angiogenesis and as angiogenesis is essential for ischemic healing, we therefore studied the role played by dopamine during ischemic healing using dopamine D 2 receptor knockout (KOD2) mice. Although concentration of dopamine and its rate-limiting enzyme, tyrosine hydroxylase, was considerably high in the muscle tissues of wild-type and KOD2 mice with unilateral hind limb ischemia (HLI), recovery was significantly faster in the KOD2 mice compared to the wild-type controls, thereby indicating that peripheral dopamine might have a role in this healing process. In addition, we observed significant differences in post-ischemic angiogenesis between these two groups. Our study further revealed that elevated dopamine independently suppressed activation of local tissue-based renin-angiotensin system (RAS), a critical growth factor system stimulating angiogenesis in ischemia. Angiotensin II (ATII) and its receptor, angiotensin receptor type 1 (AT1R), are the key players in RAS-mediated angiogenesis. Dopamine acting through its D 2 receptors in endothelial cells inhibited ATII-mediated angiogenesis by suppressing the expression of AT1R in these cells. This study thus for the first time demonstrates the role played by dopamine in prolonging post-ischemic recovery. Therefore, pharmacological intervention inhibiting the action of dopamine holds promise as future therapeutic strategy for the treatment of HLI and other peripheral arterial diseases.

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 formation and arousal, in insects. PMID:27494326

Viability preserved capture of microorganism by plasma functionalized carbon-encapsulated iron nanoparticles

NASA Astrophysics Data System (ADS)

Viswan, Anchu; Sugiura, Kuniaki; Nagatsu, Masaaki

2015-09-01

Carbon-encapsulated iron nanoparticles (Fe@C NPs) were synthesized by DC arc discharge method. Carbon encapsulation makes the particles hydrophobic, however for most of the biomedical applications they need to be hydrophilic. To attain this, the particles were amino functionalized by RF plasma. Effect of gas mixture ratio (Ar/NH3), pretreatment, post-treatment times and RF power were optimized. By varying the RF plasma conditions, the amino group population on the surface of Fe@C NPs were increased. With conventional chemical method the amino group population on particles, synthesized in different conditions was found to be ranging from 3-7 × 104 per particle. Bioconjugation efficiency of the nanoparticles was examined by biotin-avidin system, which can be simulated for antigen-antibody reactions. Results from the UV absorption and fluorescence spectroscopy shows increment in bioconjugation efficiency, with the increase of amino group population on the nanoparticles. After confirming the bioconjugation efficiency, the amino functionalized Fe@C NPs were modified with antibodies for targeting specific microorganisms. Our aim is to capture the microbes in viable and concentrated form even from less populated samples, with lesser time compared to the presently available methods. This work has been supported in part by Grant-in-Aid for Scientific Research (Nos. 21110010 and 25246029) from the Japan Society for the Promotion of Science (JSPS).

Quantum dot bioconjugates: uptake into cells and induction of changes in normal cellular transport

NASA Astrophysics Data System (ADS)

Iversen, Tore-Geir; Frerker, Nadine; Sandvig, Kirsten

2009-02-01

Can quantum dots (QDs) act as relevant intracellular probes to investigate routing of ligands in live cells? To answer this question we studied intracellular trafficking of QDs that were coupled to the plant toxin ricin, Shiga toxin or the ligand transferrin (Tf) by confocal fluorescence microscopy in three different cell lines. The Tf:QDs were internalized but instead of being recycled they accumulated within endosomes in all cell lines. However, for the HEp-2 and SW480 cells a higher fraction colocalized with a lysosomal marker as compared with HeLa cells. The Shiga:QD bioconjugate was internalized slowly and with poor efficiency in the HEp-2 and SW480 cells as compared with HeLa cells, and was not routed to the Golgi apparatus in any of the cell lines. The internalized ricin:QD bioconjugates localized to the same endosomes as ricin itself, but could in contrast to ricin not be visualized in the Golgi apparatus. Importantly, we find that the endosomal accumulation of either ricin:QDs or transferrin:QDs affects endosome-to-Golgi transport of both ricin and Shiga toxin: Transport of ricin was reduced whereas transport of Shiga toxin was increased. In conclusion, the data from different cells reveal that in general these ligand-coupled QD nanoparticles are arrested within endosomes, and somehow perturb the normal endosomal sorting in cells.

Anti-proliferative effects of gold nanoparticles functionalized with Semaphorin 3F

NASA Astrophysics Data System (ADS)

Tan, Gamze; Onur, Mehmet Ali

2017-08-01

The new vessel formations play a vital role in growth and spread of cancer. Current anti-angiogenic therapies, predominantly based on vascular endothelial growth factor (VEGF) inhibition, can inhibit vascular development; however, they are usually ineffective against the primary tumor occurrence. The aim of this study was to assess anti-angiogenic effects of gold nanoparticles (AuNPs) functionalized with Semaphorin (Sema) 3F protein. The polyethylene glycol (PEG)-coated AuNPs were covalently functionalized with Sema 3F and labeled with the TAMRA fluorescent dye. The effect of the NPs on human umbilical vein endothelial cells (HUVECs) is probed in the way of internalization and viability assays. AuNP-Sema 3F bioconjugates showed great endothelial cell uptake. AuNP-Sema 3F bioconjugates reduced VEGF165-induced endothelial cell proliferation more effectively than Sema 3F alone, suggesting that the therapeutic effects of Sema 3F can be improved by conjugation to AuNPs. Also, no significant toxicity effect was induced by bioconjugates. This is the first study that reports a covalent binding of full length Sema 3F to NPs. The exogenously administration of Sema 3F, which has both anti-angiogenic and anti-tumoral activity, to tumor vasculature via a carrying platform may not only lead to more effective anti-angiogenic treatment but also may make current approach more applicable in clinical use like drug delivery system. [Figure not available: see fulltext.

Potentiometric Urea Biosensor Based on an Immobilised Fullerene-Urease Bio-Conjugate

PubMed Central

Saeedfar, Kasra; Heng, Lee Yook; Ling, Tan Ling; Rezayi, Majid

2013-01-01

A novel method for the rapid modification of fullerene for subsequent enzyme attachment to create a potentiometric biosensor is presented. Urease was immobilized onto the modified fullerene nanomaterial. The modified fullerene-immobilized urease (C60-urease) bioconjugate has been confirmed to catalyze the hydrolysis of urea in solution. The biomaterial was then deposited on a screen-printed electrode containing a non-plasticized poly(n-butyl acrylate) (PnBA) membrane entrapped with a hydrogen ionophore. This pH-selective membrane is intended to function as a potentiometric urea biosensor with the deposition of C60-urease on the PnBA membrane. Various parameters for fullerene modification and urease immobilization were investigated. The optimal pH and concentration of the phosphate buffer for the urea biosensor were 7.0 and 0.5 mM, respectively. The linear response range of the biosensor was from 2.31 × 10−3 M to 8.28 × 10−5 M. The biosensor's sensitivity was 59.67 ± 0.91 mV/decade, which is close to the theoretical value. Common cations such as Na+, K+, Ca2+, Mg2+ and NH4+ showed no obvious interference with the urea biosensor's response. The use of a fullerene-urease bio-conjugate and an acrylic membrane with good adhesion prevented the leaching of urease enzyme and thus increased the stability of the urea biosensor for up to 140 days. PMID:24322561

Potentiometric urea biosensor based on an immobilised fullerene-urease bio-conjugate.

PubMed

Saeedfar, Kasra; Heng, Lee Yook; Ling, Tan Ling; Rezayi, Majid

2013-12-06

A novel method for the rapid modification of fullerene for subsequent enzyme attachment to create a potentiometric biosensor is presented. Urease was immobilized onto the modified fullerene nanomaterial. The modified fullerene-immobilized urease (C60-urease) bioconjugate has been confirmed to catalyze the hydrolysis of urea in solution. The biomaterial was then deposited on a screen-printed electrode containing a non-plasticized poly(n-butyl acrylate) (PnBA) membrane entrapped with a hydrogen ionophore. This pH-selective membrane is intended to function as a potentiometric urea biosensor with the deposition of C60-urease on the PnBA membrane. Various parameters for fullerene modification and urease immobilization were investigated. The optimal pH and concentration of the phosphate buffer for the urea biosensor were 7.0 and 0.5 mM, respectively. The linear response range of the biosensor was from 2.31 × 10-3 M to 8.28 × 10-5 M. The biosensor's sensitivity was 59.67 ± 0.91 mV/decade, which is close to the theoretical value. Common cations such as Na+, K+, Ca2+, Mg2+ and NH4+ showed no obvious interference with the urea biosensor's response. The use of a fullerene-urease bio-conjugate and an acrylic membrane with good adhesion prevented the leaching of urease enzyme and thus increased the stability of the urea biosensor for up to 140 days.

C-FSCV: Compressive Fast-Scan Cyclic Voltammetry for Brain Dopamine Recording.

PubMed

Zamani, Hossein; Bahrami, Hamid Reza; Chalwadi, Preeti; Garris, Paul A; Mohseni, Pedram

2018-01-01

This paper presents a novel compressive sensing framework for recording brain dopamine levels with fast-scan cyclic voltammetry (FSCV) at a carbon-fiber microelectrode. Termed compressive FSCV (C-FSCV), this approach compressively samples the measured total current in each FSCV scan and performs basic FSCV processing steps, e.g., background current averaging and subtraction, directly with compressed measurements. The resulting background-subtracted faradaic currents, which are shown to have a block-sparse representation in the discrete cosine transform domain, are next reconstructed from their compressively sampled counterparts with the block sparse Bayesian learning algorithm. Using a previously recorded dopamine dataset, consisting of electrically evoked signals recorded in the dorsal striatum of an anesthetized rat, the C-FSCV framework is shown to be efficacious in compressing and reconstructing brain dopamine dynamics and associated voltammograms with high fidelity (correlation coefficient, ), while achieving compression ratio, CR, values as high as ~ 5. Moreover, using another set of dopamine data recorded 5 minutes after administration of amphetamine (AMPH) to an ambulatory rat, C-FSCV once again compresses (CR = 5) and reconstructs the temporal pattern of dopamine release with high fidelity ( ), leading to a true-positive rate of 96.4% in detecting AMPH-induced dopamine transients.

Water-soluble triazabutadienes that release diazonium species upon protonation under physiologically relevant conditions.

PubMed

Kimani, Flora W; Jewett, John C

2015-03-23

Triazabutadienes are an understudied structural motif that have remarkable reactivity once rendered water-soluble. It is shown that these molecules readily release diazonium species in a pH-dependent manner in a series of buffer solutions with pH ranges similar to those found in cells. Upon further development, we expect that this process will be well suited to cargo-release strategies and organelle-specific bioconjugation reactions. These compounds offer one of the mildest ways of generating diazonium species in aqueous solutions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The influence of the COMT genotype in the underlying functional brain activity of context processing in schizophrenia and in relatives.

PubMed

Lopez-Garcia, Pilar; Cristobal-Huerta, Alexandra; Young Espinoza, Leslie; Molero, Patricio; Ortuño Sanchez-Pedreño, Felipe; Hernández-Tamames, Juan Antonio

2016-11-03

Context processing deficits have been shown to be present in chronic and first episode schizophrenia patients and in their relatives. This cognitive process is linked to frontal functioning and is highly dependent on dopamine levels in the prefrontal cortex (PFC). The catechol-O-methyltransferase (COMT) enzyme plays a prominent role in regulating dopamine levels in PFC. Genotypic variations in the functional polymorphism Val(158)Met COMT appear to have an impact in dopamine signaling in the PFC of healthy subjects and schizophrenia patients. We aimed to explore the effect of the Val(158)Met COMT polymorphism on brain activation during the performance of a context processing task in healthy subjects, schizophrenia spectrum patients and their healthy relatives. 56 participants performed the Dot Probe Expectancy task (DPX) during the fMRI session. Subjects were genotyped and only the Val and Met homozygotes participated in the study. Schizophrenia spectrum patients and their relatives showed worse performance on context processing measures than healthy control subjects. The Val allele was associated with more context processing errors in healthy controls and in relatives compared to patients. There was a greater recruitment of frontal areas (supplementary motor area/cingulate gyrus) during context processing in patients relative to healthy controls. Met homozygotes subjects activated more frontal areas than Val homozygotes subjects. The Val(158)Met COMT polymorphism influences context processing and on its underlying brain activation, showing less recruitment of frontal areas in the subjects with the genotype associated to lower dopamine availability in PFC. Copyright © 2016. Published by Elsevier Inc.

Mechanisms of Nicotine Addiction

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGehee, Daniel

Nicotine reinforces the use of tobacco products primarily through its interaction with specific receptor proteins within the brain’s reward centers. A critical step in the process of addiction for many drugs, including nicotine, is the release of the neurotransmitter dopamine. A single nicotine exposure will enhance dopamine levels for hours, however, nicotinic receptors undergo both activation and then desensitization in minutes, which presents an important problem. How does the time course of receptor activity lead to the prolonged release of dopamine? We have found that persistent modulation of both inhibitory and excitatory synaptic connections by nicotine underlies the sustained increasemore » in dopamine release. Because these inputs express different types of nicotinic receptors there is a coordinated shift in the balance of synaptic inputs toward excitation of the dopamine neurons. Excitatory inputs are turned on while inhibitory inputs are depressed, thereby boosting the brain’s reward system.« less

Near-Infrared Fluorescent Nanoprobes for Revealing the Role of Dopamine in Drug Addiction.

PubMed

Feng, Peijian; Chen, Yulei; Zhang, Lei; Qian, Cheng-Gen; Xiao, Xuanzhong; Han, Xu; Shen, Qun-Dong

2018-02-07

Brain imaging techniques enable visualizing the activity of central nervous system without invasive neurosurgery. Dopamine is an important neurotransmitter. Its fluctuation in brain leads to a wide range of diseases and disorders, like drug addiction, depression, and Parkinson's disease. We designed near-infrared fluorescence dopamine-responsive nanoprobes (DRNs) for brain activity imaging during drug abuse and addiction process. On the basis of light-induced electron transfer between DRNs and dopamine and molecular wire effect of the DRNs, we can track the dynamical change of the neurotransmitter level in the physiological environment and the releasing of the neurotransmitter in living dopaminergic neurons in response to nicotine stimulation. The functional near-infrared fluorescence imaging can dynamically track the dopamine level in the mice midbrain under normal or drug-activated condition and evaluate the long-term effect of addictive substances to the brain. This strategy has the potential for studying neural activity under physiological condition.

Probabilistic classification learning with corrective feedback is associated with in vivo striatal dopamine release in the ventral striatum, while learning without feedback is not

PubMed Central

Wilkinson, Leonora; Tai, Yen Foung; Lin, Chia Shu; Lagnado, David Albert; Brooks, David James; Piccini, Paola; Jahanshahi, Marjan

2014-01-01

The basal ganglia (BG) mediate certain types of procedural learning, such as probabilistic classification learning on the ‘weather prediction task’ (WPT). Patients with Parkinson's disease (PD), who have BG dysfunction, are impaired at WPT-learning, but it remains unclear what component of the WPT is important for learning to occur. We tested the hypothesis that learning through processing of corrective feedback is the essential component and is associated with release of striatal dopamine. We employed two WPT paradigms, either involving learning via processing of corrective feedback (FB) or in a paired associate manner (PA). To test the prediction that learning on the FB but not PA paradigm would be associated with dopamine release in the striatum, we used serial 11C-raclopride (RAC) positron emission tomography (PET), to investigate striatal dopamine release during FB and PA WPT-learning in healthy individuals. Two groups, FB, (n = 7) and PA (n = 8), underwent RAC PET twice, once while performing the WPT and once during a control task. Based on a region-of-interest approach, striatal RAC-binding potentials reduced by 13–17% in the right ventral striatum when performing the FB compared to control task, indicating release of synaptic dopamine. In contrast, right ventral striatal RAC binding non-significantly increased by 9% during the PA task. While differences between the FB and PA versions of the WPT in effort and decision-making is also relevant, we conclude striatal dopamine is released during FB-based WPT-learning, implicating the striatum and its dopamine connections in mediating learning with FB. PMID:24777947

The motivational drive to natural rewards is modulated by prenatal glucocorticoid exposure

PubMed Central

Soares-Cunha, C; Coimbra, B; Borges, S; Carvalho, M M; Rodrigues, A J; Sousa, N

2014-01-01

Exposure to elevated levels of glucocorticoids (GCs) during neurodevelopment has been identified as a triggering factor for the development of reward-associated disorders in adulthood. Disturbances in the neural networks responsible for the complex processes that assign value to rewards and associated stimuli are critical for disorders such as depression, obsessive–compulsive disorders, obesity and addiction. Essential in the understanding on how cues influence behavior is the Pavlovian–instrumental transfer (PIT), a phenomenon that refers to the capacity of a Pavlovian stimulus that predicts a reward to elicit instrumental responses for that same reward. Here, we demonstrate that in utero exposure to GCs (iuGC) impairs both general and selective versions of the PIT paradigm, suggestive of deficits in motivational drive. The iuGC animals presented impaired neuronal activation pattern upon PIT performance in cortical and limbic regions, as well as morphometric changes and reduced levels of dopamine in prefrontal and orbitofrontal cortices, key regions involved in the integration of Pavlovian and instrumental stimuli. Normalization of dopamine levels rescued this behavior, a process that relied on D2/D3, but not D1, dopamine receptor activation. In summary, iuGC exposure programs the mesocorticolimbic dopaminergic circuitry, leading to a reduction in the attribution of the incentive salience to cues, in a dopamine-D2/D3-dependent manner. Ultimately, these results are important to understand how GCs bias incentive processes, a fact that is particularly relevant for disorders where differential attribution of incentive salience is critical. PMID:25928947

Click chemistry in the Development of Contrast Agents for Magnetic Resonance Imaging

PubMed Central

Hapuarachchige, Sudath; Artemov, Dmitri

2016-01-01

Click chemistry provides fast, convenient, versatile and reliable chemical reactions that take place between pairs of functional groups of small molecules that can be purified without chromatographic methods. Due to the fast kinetics and low or no elimination of byproducts, click chemistry is a promising approach that is rapidly gaining acceptance in drug discovery, radiochemistry, bioconjugation, and nanoscience applications. Increasing use of click chemistry in synthetic procedures or as a bioconjugation technique in diagnostic imaging is occurring because click reactions are fast, provide a quantitative yield, and produce minimal amount of nontoxic byproducts. This review summarizes the recent application of click chemistry in magnetic resonance imaging and discusses the directions for applying novel click reactions and strategies for further improving MRI performance. PMID:27748712

Surface bioengineering of diatomite based nanovectors for efficient intracellular uptake and drug delivery

NASA Astrophysics Data System (ADS)

Terracciano, Monica; Shahbazi, Mohammad-Ali; Correia, Alexandra; Rea, Ilaria; Lamberti, Annalisa; de Stefano, Luca; Santos, Hélder A.

2015-11-01

Diatomite is a natural porous silica material of sedimentary origin. Due to its peculiar properties, it can be considered as a valid surrogate of synthetic porous silica for nano-based drug delivery. In this work, we exploit the potential of diatomite nanoparticles (DNPs) for drug delivery with the aim of developing a successful dual-biofunctionalization method by polyethylene glycol (PEG) coverage and cell-penetrating peptide (CPP) bioconjugation, to improve the physicochemical and biological properties of the particles, to enhance the intracellular uptake in cancer cells, and to increase the biocompatibility of 3-aminopropyltriethoxysilane (APT) modified-DNPs. DNPs-APT-PEG-CPP showed hemocompatibility for up to 200 μg mL-1 after 48 h of incubation with erythrocytes, with a hemolysis value of only 1.3%. The cytotoxicity of the modified-DNPs with a concentration up to 200 μg mL-1 and incubation with MCF-7 and MDA-MB-231 breast cancer cells for 24 h, demonstrated that PEGylation and CPP-bioconjugation can strongly reduce the cytotoxicity of DNPs-APT. The cellular uptake of the modified-DNPs was also evaluated using the above mentioned cancer cell lines, showing that the CPP-bioconjugation can considerably increase the DNP cellular uptake. Moreover, the dual surface modification of DNPs improved both the loading of a poorly water-soluble anticancer drug, sorafenib, with a loading degree up to 22 wt%, and also enhanced the drug release profiles in aqueous solutions. Overall, this work demonstrates that the biofunctionalization of DNPs is a promising platform for drug delivery applications in cancer therapy as a result of its enhanced stability, biocompatibility, cellular uptake, and drug release profiles.Diatomite is a natural porous silica material of sedimentary origin. Due to its peculiar properties, it can be considered as a valid surrogate of synthetic porous silica for nano-based drug delivery. In this work, we exploit the potential of diatomite nanoparticles (DNPs) for drug delivery with the aim of developing a successful dual-biofunctionalization method by polyethylene glycol (PEG) coverage and cell-penetrating peptide (CPP) bioconjugation, to improve the physicochemical and biological properties of the particles, to enhance the intracellular uptake in cancer cells, and to increase the biocompatibility of 3-aminopropyltriethoxysilane (APT) modified-DNPs. DNPs-APT-PEG-CPP showed hemocompatibility for up to 200 μg mL-1 after 48 h of incubation with erythrocytes, with a hemolysis value of only 1.3%. The cytotoxicity of the modified-DNPs with a concentration up to 200 μg mL-1 and incubation with MCF-7 and MDA-MB-231 breast cancer cells for 24 h, demonstrated that PEGylation and CPP-bioconjugation can strongly reduce the cytotoxicity of DNPs-APT. The cellular uptake of the modified-DNPs was also evaluated using the above mentioned cancer cell lines, showing that the CPP-bioconjugation can considerably increase the DNP cellular uptake. Moreover, the dual surface modification of DNPs improved both the loading of a poorly water-soluble anticancer drug, sorafenib, with a loading degree up to 22 wt%, and also enhanced the drug release profiles in aqueous solutions. Overall, this work demonstrates that the biofunctionalization of DNPs is a promising platform for drug delivery applications in cancer therapy as a result of its enhanced stability, biocompatibility, cellular uptake, and drug release profiles. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05173h

Aging Affects Dopaminergic Neural Mechanisms of Cognitive Flexibility

DOE PAGES

Berry, Anne S.; Shah, Vyoma D.; Baker, Suzanne L.; ...

2016-12-14

Aging is accompanied by profound changes in the brain’s dopamine system that affect cognitive function. Evidence of powerful individual differences in cognitive aging has sharpened focus on identifying biological factors underlying relative preservation versus vulnerability to decline. Dopamine represents a key target in these efforts. Alterations of dopamine receptors and dopamine synthesis are seen in aging, with receptors generally showing reduction and synthesis demonstrating increases. Using the PET tracer 6-[ 18F]fluoro-L- m-tyrosine, we found strong support for upregulated striatal dopamine synthesis capacity in healthy older adult humans free of amyloid pathology, relative to young people. We next used fMRI tomore » define the functional impact of elevated synthesis capacity on cognitive flexibility, a core component of executive function. We found clear evidence in young adults that low levels of synthesis capacity were suboptimal, associated with diminished cognitive flexibility and altered frontoparietal activation relative to young adults with highest synthesis values. Critically, these relationships between dopamine, performance, and activation were transformed in older adults with higher synthesis capacity. Variability in synthesis capacity was related to intrinsic frontoparietal functional connectivity across groups, suggesting that striatal dopamine synthesis influences the tuning of networks underlying cognitive flexibility. Altogether, these findings define striatal dopamine’s association with cognitive flexibility and its neural underpinnings in young adults, and reveal the alteration in dopamine-related neural processes in aging.« less

Aging Affects Dopaminergic Neural Mechanisms of Cognitive Flexibility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berry, Anne S.; Shah, Vyoma D.; Baker, Suzanne L.

Aging is accompanied by profound changes in the brain’s dopamine system that affect cognitive function. Evidence of powerful individual differences in cognitive aging has sharpened focus on identifying biological factors underlying relative preservation versus vulnerability to decline. Dopamine represents a key target in these efforts. Alterations of dopamine receptors and dopamine synthesis are seen in aging, with receptors generally showing reduction and synthesis demonstrating increases. Using the PET tracer 6-[ 18F]fluoro-L- m-tyrosine, we found strong support for upregulated striatal dopamine synthesis capacity in healthy older adult humans free of amyloid pathology, relative to young people. We next used fMRI tomore » define the functional impact of elevated synthesis capacity on cognitive flexibility, a core component of executive function. We found clear evidence in young adults that low levels of synthesis capacity were suboptimal, associated with diminished cognitive flexibility and altered frontoparietal activation relative to young adults with highest synthesis values. Critically, these relationships between dopamine, performance, and activation were transformed in older adults with higher synthesis capacity. Variability in synthesis capacity was related to intrinsic frontoparietal functional connectivity across groups, suggesting that striatal dopamine synthesis influences the tuning of networks underlying cognitive flexibility. Altogether, these findings define striatal dopamine’s association with cognitive flexibility and its neural underpinnings in young adults, and reveal the alteration in dopamine-related neural processes in aging.« less

Changes in dopamine levels and locomotor activity in response to selection on virgin lifespan in Drosophila melanogaster.

PubMed

Vermeulen, C J; Cremers, T I F H; Westerink, B H C; Van De Zande, L; Bijlsma, R

2006-07-01

Among various other mechanisms, genetic differences in the production of reactive oxygen species are thought to underlie genetic variation for longevity. Here we report on possible changes in ROS production related processes in response to selection for divergent virgin lifespan in Drosophila. The selection lines were observed to differ significantly in dopamine levels and melanin pigmentation, which is associated with dopamine levels at eclosion. These findings confirm that variation in dopamine levels is associated with genetic variation for longevity. Dopamine has previously been implied in ROS production and in the occurrence of age-related neurodegenerative diseases. In addition, we propose a possible proximate mechanism by which dopamine levels affect longevity in Drosophila: We tested if increased dopamine levels were associated with a "rate-of-living" syndrome of increased activity and respiration levels, thus aggravating the level of oxidative stress. Findings on locomotor activity and oxygen consumption of short-lived flies were in line with expectations. However, the relation is not straightforward, as flies of the long-lived lines did not show any consistent differences in pigmentation or dopamine levels with respect to the control lines. Moreover, long-lived flies also had increased locomotor activity, but showed no consistent differences in respiration rate. This strongly suggests that the response for increased and decreased lifespan may be obtained by different mechanisms.

Process development of a FGF21 protein-antibody conjugate.

PubMed

Dirksen, Anouk; Davis, Keith A; Collins, Joe T; Bhattacharya, Keshab; Finneman, Jari I; Pepin, Erin L; Ryczek, Jeffrey S; Brown, Paul W; Wellborn, William B; Mangalathillam, Ratish; Evans, Brad P; Pozzo, Mark J; Finn, Rory F

2017-09-26

A scalable, viable process was developed for the Fibroblast Growth Factor 21 (FGF21) protein-antibody conjugate, CVX-343, an extended half-life therapeutic for the treatment of metabolic disease. CVX-343 utilizes the CovX antibody scaffold technology platform that was specifically developed for peptide and protein half-life extension. CVX-343 is representative of a growing number of complex novel peptide- and protein-based bioconjugate molecules currently being explored as therapeutic candidates. The complexity of these bioconjugates, assembled using well-established chemistries, can lead to very difficult production schemes requiring multiple starting materials and a combination of diverse technologies. Key improvements had to be made to the original CVX-343 Phase 1 manufacturing process in preparation for Phase 3 and commercial manufacturing. A strategy of minimizing FGF21 A129C dimerization and stabilizing the FGF21 A129C Drug Substance Intermediate (DSI), linker, and activated FGF21 intermediate was pursued. The use of tris(2-carboxyethyl)phosphine (TCEP) to prevent FGF21 A129C dimerization through disulfide formation was eliminated. FGF21 A129C dimerization and linker hydrolysis were minimized by formulating and activating FGF21 A129C at acidic instead of neutral pH. An activation use test was utilized to guide FGF21 A129C pooling in order to minimize misfolds, dimers, and misfolded dimers in the FGF21 A129C DSI. After final optimization of reaction conditions, a process was established that reduced the consumption of FGF21 A129C by 36% (from 4.7 to 3.0 equivalents) and the consumption of linker by 55% (from 1.4 to 0.95 equivalents for a smaller required amount of FGF21 A129C ). The overall process time was reduced from ∼5 to ∼3 days. The product distribution improved from containing ∼60% to ∼75% desired bifunctionalized (+2 FGF21) FGF21-antibody conjugate in the crude conjugation mixture and from ∼80% to ∼85% in the final CVX-343 Drug Substance (DS), while maintaining the same overall process yield based on antibody scaffold input. © 2017 Wiley Periodicals, Inc.

The effects of DAT1 genotype on fMRI activation in an emotional go/no-go task.

PubMed

Brown, Brenna K; Murrell, Jill; Karne, Harish; Anand, Amit

2017-02-01

Dopaminergic brain circuits participate in emotional processing and impulsivity. The dopamine transporter (DAT) modulates dopamine reuptake. A variable number tandem repeat (VNTR) in the dopamine transporter gene (DAT1) affects DAT expression. The influence of DAT1 genotype on neural activation during emotional processing and impulse inhibition has not been examined. Forty-two healthy subjects were classified as 9DAT (n = 17) or 10DAT (n = 25) based on DAT1 genotype (9DAT = 9R/9R and 9R/10R; 10DAT = 10R/10R). Subjects underwent fMRI during non-emotional and emotional go/no-go tasks. Subjects were instructed to inhibit responses to letters, happy faces, or sad faces in separate blocks. Accuracy and reaction time did not differ between groups. Within group results showed activation in regions previously implicated in emotional processing and response inhibition. Between groups results showed increased activation in 9DAT individuals during inhibition. During letter inhibition, 9DAT individuals exhibited greater activation in right inferior parietal regions. During sad inhibition, 9DAT Individuals exhibited greater activation in frontal, posterior cingulate, precuneus, right cerebellar, left paracentral, and right occipital brain regions. The interaction between DAT genotype and response type in sad versus letter stimuli showed increased activation in 9DAT individuals during sad no-go responses in the anterior cingulate cortex, extending into frontal-orbital regions. 9DAT individuals have greater activation than 10DAT individuals during neutral and sad inhibition, showing that genotypic variation influencing basal dopamine levels can alter the neural basis of emotional processing and response inhibition. This may indicate that 9R carriers exert more effort to overcome increased basal dopamine activation when inhibiting responses in emotional contexts.

Presynaptic D2 dopamine receptors control long-term depression expression and memory processes in the temporal hippocampus.

PubMed

Rocchetti, Jill; Isingrini, Elsa; Dal Bo, Gregory; Sagheby, Sara; Menegaux, Aurore; Tronche, François; Levesque, Daniel; Moquin, Luc; Gratton, Alain; Wong, Tak Pan; Rubinstein, Marcelo; Giros, Bruno

2015-03-15

Dysfunctional mesocorticolimbic dopamine signaling has been linked to alterations in motor and reward-based functions associated with psychiatric disorders. Converging evidence from patients with psychiatric disorders and use of antipsychotics suggests that imbalance of dopamine signaling deeply alters hippocampal functions. However, given the lack of full characterization of a functional mesohippocampal pathway, the precise role of dopamine transmission in memory deficits associated with these disorders and their dedicated therapies is unknown. In particular, the positive outcome of antipsychotic treatments, commonly antagonizing D2 dopamine receptors (D2Rs), on cognitive deficits and memory impairments remains questionable. Following pharmacologic and genetic manipulation of dopamine transmission, we performed anatomic, neurochemical, electrophysiologic, and behavioral investigations to uncover the role of D2Rs in hippocampal-dependent plasticity and learning. Naïve mice (n = 4-21) were used in the different procedures. Dopamine modulated both long-term potentiation and long-term depression in the temporal hippocampus as well as spatial and recognition learning and memory in mice through D2Rs. Although genetic deletion or pharmacologic blockade of D2Rs led to the loss of long-term potentiation expression, the specific genetic removal of presynaptic D2Rs impaired long-term depression and performances on spatial memory tasks. Presynaptic D2Rs in dopamine fibers of the temporal hippocampus tightly modulate long-term depression expression and play a major role in the regulation of hippocampal learning and memory. This direct role of mesohippocampal dopamine input as uncovered here adds a new dimension to dopamine involvement in the physiology underlying deficits associated with neuropsychiatric disorders. Copyright © 2015 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Aging Affects Dopaminergic Neural Mechanisms of Cognitive Flexibility.

PubMed

Berry, Anne S; Shah, Vyoma D; Baker, Suzanne L; Vogel, Jacob W; O'Neil, James P; Janabi, Mustafa; Schwimmer, Henry D; Marks, Shawn M; Jagust, William J

2016-12-14

Aging is accompanied by profound changes in the brain's dopamine system that affect cognitive function. Evidence of powerful individual differences in cognitive aging has sharpened focus on identifying biological factors underlying relative preservation versus vulnerability to decline. Dopamine represents a key target in these efforts. Alterations of dopamine receptors and dopamine synthesis are seen in aging, with receptors generally showing reduction and synthesis demonstrating increases. Using the PET tracer 6-[ 18 F]fluoro-l-m-tyrosine, we found strong support for upregulated striatal dopamine synthesis capacity in healthy older adult humans free of amyloid pathology, relative to young people. We next used fMRI to define the functional impact of elevated synthesis capacity on cognitive flexibility, a core component of executive function. We found clear evidence in young adults that low levels of synthesis capacity were suboptimal, associated with diminished cognitive flexibility and altered frontoparietal activation relative to young adults with highest synthesis values. Critically, these relationships between dopamine, performance, and activation were transformed in older adults with higher synthesis capacity. Variability in synthesis capacity was related to intrinsic frontoparietal functional connectivity across groups, suggesting that striatal dopamine synthesis influences the tuning of networks underlying cognitive flexibility. Together, these findings define striatal dopamine's association with cognitive flexibility and its neural underpinnings in young adults, and reveal the alteration in dopamine-related neural processes in aging. Few studies have combined measurement of brain dopamine with examination of the neural basis of cognition in youth and aging to delineate the underlying mechanisms of these associations. Combining in vivo PET imaging of dopamine synthesis capacity, fMRI, and a sensitive measure of cognitive flexibility, we reveal three core findings. First, we find evidence supporting older adults' capacity to upregulate dopamine synthesis. Second, we define relationships between dopamine, cognition, and frontoparietal activity in young adults indicating high levels of synthesis capacity are optimal. Third, we demonstrate alteration of these relationships in older adults, suggesting neurochemical modulation of cognitive flexibility changes with age. Copyright © 2016 the authors 0270-6474/16/3612559-11$15.00/0.

Human Dopamine Receptors Interaction Network (DRIN): a systems biology perspective on topology, stability and functionality of the network.

PubMed

Podder, Avijit; Jatana, Nidhi; Latha, N

2014-09-21

Dopamine receptors (DR) are one of the major neurotransmitter receptors present in human brain. Malfunctioning of these receptors is well established to trigger many neurological and psychiatric disorders. Taking into consideration that proteins function collectively in a network for most of the biological processes, the present study is aimed to depict the interactions between all dopamine receptors following a systems biology approach. To capture comprehensive interactions of candidate proteins associated with human dopamine receptors, we performed a protein-protein interaction network (PPIN) analysis of all five receptors and their protein partners by mapping them into human interactome and constructed a human Dopamine Receptors Interaction Network (DRIN). We explored the topology of dopamine receptors as molecular network, revealing their characteristics and the role of central network elements. More to the point, a sub-network analysis was done to determine major functional clusters in human DRIN that govern key neurological pathways. Besides, interacting proteins in a pathway were characterized and prioritized based on their affinity for utmost drug molecules. The vulnerability of different networks to the dysfunction of diverse combination of components was estimated under random and direct attack scenarios. To the best of our knowledge, the current study is unique to put all five dopamine receptors together in a common interaction network and to understand the functionality of interacting proteins collectively. Our study pinpointed distinctive topological and functional properties of human dopamine receptors that have helped in identifying potential therapeutic drug targets in the dopamine interaction network. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dopamine modulation of GABAergic function enables network stability and input selectivity for sustaining working memory in a computational model of the prefrontal cortex.

PubMed

Lew, Sergio E; Tseng, Kuei Y

2014-12-01

Dopamine modulation of GABAergic transmission in the prefrontal cortex (PFC) is thought to be critical for sustaining cognitive processes such as working memory and decision-making. Here, we developed a neurocomputational model of the PFC that includes physiological features of the facilitatory action of dopamine on fast-spiking interneurons to assess how a GABAergic dysregulation impacts on the prefrontal network stability and working memory. We found that a particular non-linear relationship between dopamine transmission and GABA function is required to enable input selectivity in the PFC for the formation and retention of working memory. Either degradation of the dopamine signal or the GABAergic function is sufficient to elicit hyperexcitability in pyramidal neurons and working memory impairments. The simulations also revealed an inverted U-shape relationship between working memory and dopamine, a function that is maintained even at high levels of GABA degradation. In fact, the working memory deficits resulting from reduced GABAergic transmission can be rescued by increasing dopamine tone and vice versa. We also examined the role of this dopamine-GABA interaction for the termination of working memory and found that the extent of GABAergic excitation needed to reset the PFC network begins to occur when the activity of fast-spiking interneurons surpasses 40 Hz. Together, these results indicate that the capability of the PFC to sustain working memory and network stability depends on a robust interplay of compensatory mechanisms between dopamine tone and the activity of local GABAergic interneurons.

Nucleus Accumbens Shell Dopamine Preferentially Tracks Information Related to Outcome Value of Reward.

PubMed

Sackett, Deirdre A; Saddoris, Michael P; Carelli, Regina M

2017-01-01

Effective decision-making requires organisms to predict reward values and bias behavior toward the best available option. The mesolimbic dopamine system, including the nucleus accumbens (NAc) shell and core, is involved in this process. Although studies support a role of the shell and core in specific aspects of decision-making (e.g., risk, effort, delay), no studies have directly compared dopamine release dynamics in these subregions to cues exclusively signaling the availability of different reward magnitudes. Here, fast-scan cyclic voltammetry was used to compare rapid dopamine release dynamics in the NAc subregions during a magnitude-based decision-making task. Rats learned that distinct cues signaled the availability of either a small or large reward (one or two sugar pellets), and then were given an opportunity to choose their preferred option. We found that peak dopamine release tracked the more preferred (higher-magnitude) option in both core and shell subregions. Critically, however, overall (i.e., global) dopamine release was significantly higher and longer lasting in the shell and tracked the preferred magnitude during the entire cue period. Further, in the shell (not core), dopamine signaling significantly declined immediately at the lever press for reward but increased during the period of reward consumption. Collectively, the results indicate that although dopamine release in both the core and shell are activated by cues signaling the opportunity to respond for rewards of different magnitudes, dopamine release in the shell plays a differential and unique role in tracking information related to the outcome value of reward.

Dopamine-dependent periadolescent maturation of corticostriatal functional connectivity in mouse.

PubMed

Galiñanes, Gregorio L; Taravini, Irene R E; Murer, M Gustavo

2009-02-25

Altered corticostriatal information processing associated with early dopamine systems dysfunction may contribute to attention deficit/hyperactivity disorder (ADHD). Mice with neonatal dopamine-depleting lesions exhibit hyperactivity that wanes after puberty and is reduced by psychostimulants, reminiscent of some aspects of ADHD. To assess whether the maturation of corticostriatal functional connectivity is altered by early dopamine depletion, we examined preadolescent and postadolescent urethane-anesthetized mice with or without dopamine-depleting lesions. Specifically, we assessed (1) synchronization between striatal neuron discharges and oscillations in frontal cortex field potentials and (2) striatal neuron responses to frontal cortex stimulation. In adult control mice striatal neurons were less spontaneously active, less responsive to cortical stimulation, and more temporally tuned to cortical rhythms than in infants. Striatal neurons from hyperlocomotor mice required more current to respond to cortical input and were less phase locked to ongoing oscillations, resulting in fewer neurons responding to refined cortical commands. By adulthood some electrophysiological deficits waned together with hyperlocomotion, but striatal spontaneous activity remained substantially elevated. Moreover, dopamine-depleted animals showing normal locomotor scores exhibited normal corticostriatal synchronization, suggesting that the lesion allows, but is not sufficient, for the emergence of corticostriatal changes and hyperactivity. Although amphetamine normalized corticostriatal tuning in hyperlocomotor mice, it reduced horizontal activity in dopamine-depleted animals regardless of their locomotor phenotype, suggesting that amphetamine modified locomotion through a parallel mechanism, rather than that modified by dopamine depletion. In summary, functional maturation of striatal activity continues after infancy, and early dopamine depletion delays the maturation of core functional capacities of the corticostriatal system.

Dopamine-dependent periadolescent maturation of corticostriatal functional connectivity in mouse

PubMed Central

Galiñanes, Gregorio L.; Taravini, Irene R.E.; Murer, M. Gustavo

2009-01-01

Altered corticostriatal information processing associated with early dopamine systems dysfunction may contribute to attention deficit/hyperactivity disorder (ADHD). Mice with neonatal dopamine-depleting lesions exhibit hyperactivity that wanes after puberty and is reduced by psychostimulants, reminiscent of some aspects of ADHD. To assess whether the maturation of corticostriatal functional connectivity is altered by early dopamine depletion, we examined pre- and post-adolescent urethane-anesthetized mice with or without dopamine-depleting lesions. Specifically, we assessed (1) synchronization between striatal neuron discharges and oscillations in frontal cortex field potentials and (2) striatal neuron responses to frontal cortex stimulation. In adult control mice striatal neurons were less spontaneously active, less responsive to cortical stimulation and more temporally tuned to cortical rhythms than in infants. Striatal neurons from hyperlocomotor mice required more current to respond to cortical input and were less phase-locked to ongoing oscillations, resulting in fewer neurons responding to refined cortical commands. By adulthood some electrophysiological deficits waned together with hyperlocomotion, but striatal spontaneous activity remained substantially elevated. Moreover, dopamine-depleted animals showing normal locomotor scores exhibited normal corticostriatal synchronization, suggesting that the lesion allows, but is not sufficient, for the emergence of corticostriatal changes and hyperactivity. Although amphetamine normalized corticostriatal tuning in hyperlocomotor mice, it reduced horizontal activity in dopamine-depleted animals irrespective of their locomotor phenotype, suggesting that amphetamine modified locomotion through a parallel mechanism, rather than that modified by dopamine depletion. In summary, functional maturation of striatal activity continues after infancy, and early dopamine depletion delays the maturation of core functional capacities of the corticostriatal system. PMID:19244524

Protective actions of the vesicular monoamine transporter 2 (VMAT2) in monoaminergic neurons.

PubMed

Guillot, Thomas S; Miller, Gary W

2009-04-01

Vesicular monoamine transporters (VMATs) are responsible for the packaging of neurotransmitters such as dopamine, serotonin, norepinephrine, and epinephrine into synaptic vesicles. These proteins evolved from precursors in the major facilitator superfamily of transporters and are among the members of the toxin extruding antiporter family. While the primary function of VMATs is to sequester neurotransmitters within vesicles, they can also translocate toxicants away from cytosolic sites of action. In the case of dopamine, this dual role of VMAT2 is combined-dopamine is more readily oxidized in the cytosol where it can cause oxidative stress so packaging into vesicles serves two purposes: neurotransmission and neuroprotection. Furthermore, the deleterious effects of exogenous toxicants on dopamine neurons, such as MPTP, can be attenuated by VMAT2 activity. The active metabolite of MPTP can be kept within vesicles and prevented from disrupting mitochondrial function thereby sparing the dopamine neuron. The highly addictive drug methamphetamine is also neurotoxic to dopamine neurons by using dopamine itself to destroy the axon terminals. Methamphetamine interferes with vesicular sequestration and increases the production of dopamine, escalating the amount in the cytosol and leading to oxidative damage of terminal components. Vesicular transport seems to resist this process by sequestering much of the excess dopamine, which is illustrated by the enhanced methamphetamine neurotoxicity in VMAT2-deficient mice. It is increasingly evident that VMAT2 provides neuroprotection from both endogenous and exogenous toxicants and that while VMAT2 has been adapted by eukaryotes for synaptic transmission, it is derived from phylogenetically ancient proteins that originally evolved for the purpose of cellular protection.

Time-Resolved Influences of Functional DAT1 and COMT Variants on Visual Perception and Post-Processing

PubMed Central

Bender, Stephan; Rellum, Thomas; Freitag, Christine; Resch, Franz; Rietschel, Marcella; Treutlein, Jens; Jennen-Steinmetz, Christine; Brandeis, Daniel; Banaschewski, Tobias; Laucht, Manfred

2012-01-01

Background Dopamine plays an important role in orienting and the regulation of selective attention to relevant stimulus characteristics. Thus, we examined the influences of functional variants related to dopamine inactivation in the dopamine transporter (DAT1) and catechol-O-methyltransferase genes (COMT) on the time-course of visual processing in a contingent negative variation (CNV) task. Methods 64-channel EEG recordings were obtained from 195 healthy adolescents of a community-based sample during a continuous performance task (A-X version). Early and late CNV as well as preceding visual evoked potential components were assessed. Results Significant additive main effects of DAT1 and COMT on the occipito-temporal early CNV were observed. In addition, there was a trend towards an interaction between the two polymorphisms. Source analysis showed early CNV generators in the ventral visual stream and in frontal regions. There was a strong negative correlation between occipito-temporal visual post-processing and the frontal early CNV component. The early CNV time interval 500–1000 ms after the visual cue was specifically affected while the preceding visual perception stages were not influenced. Conclusions Late visual potentials allow the genomic imaging of dopamine inactivation effects on visual post-processing. The same specific time-interval has been found to be affected by DAT1 and COMT during motor post-processing but not motor preparation. We propose the hypothesis that similar dopaminergic mechanisms modulate working memory encoding in both the visual and motor and perhaps other systems. PMID:22844499

Time-resolved influences of functional DAT1 and COMT variants on visual perception and post-processing.

PubMed

Bender, Stephan; Rellum, Thomas; Freitag, Christine; Resch, Franz; Rietschel, Marcella; Treutlein, Jens; Jennen-Steinmetz, Christine; Brandeis, Daniel; Banaschewski, Tobias; Laucht, Manfred

2012-01-01

Dopamine plays an important role in orienting and the regulation of selective attention to relevant stimulus characteristics. Thus, we examined the influences of functional variants related to dopamine inactivation in the dopamine transporter (DAT1) and catechol-O-methyltransferase genes (COMT) on the time-course of visual processing in a contingent negative variation (CNV) task. 64-channel EEG recordings were obtained from 195 healthy adolescents of a community-based sample during a continuous performance task (A-X version). Early and late CNV as well as preceding visual evoked potential components were assessed. Significant additive main effects of DAT1 and COMT on the occipito-temporal early CNV were observed. In addition, there was a trend towards an interaction between the two polymorphisms. Source analysis showed early CNV generators in the ventral visual stream and in frontal regions. There was a strong negative correlation between occipito-temporal visual post-processing and the frontal early CNV component. The early CNV time interval 500-1000 ms after the visual cue was specifically affected while the preceding visual perception stages were not influenced. Late visual potentials allow the genomic imaging of dopamine inactivation effects on visual post-processing. The same specific time-interval has been found to be affected by DAT1 and COMT during motor post-processing but not motor preparation. We propose the hypothesis that similar dopaminergic mechanisms modulate working memory encoding in both the visual and motor and perhaps other systems.

Amphetamine sensitization alters reward processing in the human striatum and amygdala.

PubMed

O'Daly, Owen G; Joyce, Daniel; Tracy, Derek K; Azim, Adnan; Stephan, Klaas E; Murray, Robin M; Shergill, Sukhwinder S

2014-01-01

Dysregulation of mesolimbic dopamine transmission is implicated in a number of psychiatric illnesses characterised by disruption of reward processing and goal-directed behaviour, including schizophrenia, drug addiction and impulse control disorders associated with chronic use of dopamine agonists. Amphetamine sensitization (AS) has been proposed to model the development of this aberrant dopamine signalling and the subsequent dysregulation of incentive motivational processes. However, in humans the effects of AS on the dopamine-sensitive neural circuitry associated with reward processing remains unclear. Here we describe the effects of acute amphetamine administration, following a sensitising dosage regime, on blood oxygen level dependent (BOLD) signal in dopaminoceptive brain regions during a rewarded gambling task performed by healthy volunteers. Using a randomised, double-blind, parallel-groups design, we found clear evidence for sensitization to the subjective effects of the drug, while rewarded reaction times were unchanged. Repeated amphetamine exposure was associated with reduced dorsal striatal BOLD signal during decision making, but enhanced ventromedial caudate activity during reward anticipation. The amygdala BOLD response to reward outcomes was blunted following repeated amphetamine exposure. Positive correlations between subjective sensitization and changes in anticipation- and outcome-related BOLD signal were seen for the caudate nucleus and amygdala, respectively. These data show for the first time in humans that AS changes the functional impact of acute stimulant exposure on the processing of reward-related information within dopaminoceptive regions. Our findings accord with pathophysiological models which implicate aberrant dopaminergic modulation of striatal and amygdala activity in psychosis and drug-related compulsive disorders.

Spectroscopic and photoacoustic characterization of encapsulated iron oxide super-paramagnetic nanoparticles as a new multiplatform contrast agent

NASA Astrophysics Data System (ADS)

Armanetti, Paolo; Flori, Alessandra; Avigo, Cinzia; Conti, Luca; Valtancoli, Barbara; Petroni, Debora; Doumett, Saer; Cappiello, Laura; Ravagli, Costanza; Baldi, Giovanni; Bencini, Andrea; Menichetti, Luca

2018-06-01

Recently, a number of photoacoustic (PA) agents with increased tissue penetration and fine spatial resolution have been developed for molecular imaging and mapping of pathophysiological features at the molecular level. Here, we present bio-conjugated near-infrared light-absorbing magnetic nanoparticles as a new agent for PA imaging. These nanoparticles exhibit suitable absorption in the near-infrared region, with good photoacoustic signal generation efficiency and high photo-stability. Furthermore, these encapsulated iron oxide nanoparticles exhibit strong super-paramagnetic behavior and nuclear relaxivities that make them useful as magnetic resonance imaging (MRI) contrast media as well. Their simple bio-conjugation strategy, optical and chemical stability, and straightforward manipulation could enable the development of a PA probe with magnetic and spectroscopic properties suitable for in vitro and in vivo real-time imaging of relevant biological targets.

Design, Synthesis and Affinity Properties of Biologically Active Peptide and Protein Conjugates of Cotton Cellulose

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edwards, J. V.; Goheen, Steven C.

The formation of peptide and protein conjugates of cellulose on cotton fabrics provides promising leads for the development of wound healing, antibacterial, and decontaminating textiles. An approach to the design, synthesis, and analysis of bioconjugates containing cellulose peptide and protein conjugates includes: 1) computer graphic modeling for a rationally designed structure; 2) attachment of the peptide or protein to cotton cellulose through a linker amino acid, and 3) characterization of the resulting bioconjugate. Computer graphic simulation of protein and peptide cellulose conjugates gives a rationally designed biopolymer to target synthetic modifications to the cotton cellulose. Techniques for preparing these typesmore » of conjugates involve both sequential assembly of the peptide on the fabric and direct crosslinking of the peptide or protein as cellulose bound esters or carboxymethylcellulose amides.« less

Bioconjugated iron oxide nanocubes: synthesis, functionalization, and vectorization.

PubMed

Wortmann, Laura; Ilyas, Shaista; Niznansky, Daniel; Valldor, Martin; Arroub, Karim; Berger, Nadja; Rahme, Kamil; Holmes, Justin; Mathur, Sanjay

2014-10-08

A facile bottom-up approach for the synthesis of inorganic/organic bioconjugated nanoprobes based on iron oxide nanocubes as the core with a nanometric silica shell is demonstrated. Surface coating and functionalization protocols developed in this work offered good control over the shell thickness (8-40 nm) and enabled biovectorization of SiO2@Fe3O4 core-shell structures by covalent attachment of folic acid (FA) as a targeting unit for cellular uptake. The successful immobilization of folic acid was investigated both quantitatively (TGA, EA, XPS) and qualitatively (AT-IR, UV-vis, ζ-potential). Additionally, the magnetic behavior of the nanocomposites was monitored after each functionalization step. Cell viability studies confirmed low cytotoxicity of FA@SiO2@Fe3O4 conjugates, which makes them promising nanoprobes for targeted internalization by cells and their imaging.

Hybrid gels by conjugation of hyaluronic acid with poly(itaconic anhydride-co-3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5)undecane) copolymers.

PubMed

Chiriac, Aurica P; Nita, Loredana Elena; Diaconu, Alina; Bercea, Maria; Tudorachi, Nita; Pamfil, Daniela; Mititelu-Tartau, Liliana

2017-05-01

The approach of covalent conjugation for coupling synthetic polymers with biomolecules represents an appealing strategy to produce new compounds with distinctive properties for biomedical applications. In the present study we generated hybrid gels with tunable characteristics by using hyaluronic acid (HA) and four variants of poly(itaconic anhydride-co-3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5] undecane) (PITAU) copolymers, differing through the molar ratios between comonomers. The new bioconjugate compounds were realized by using a ″grafting to″ strategy, for further ensuring new ways for coupling of various bioactive compounds, taking into account that the grafted copolymers are dual sensitive to pH and temperature. The procedure of chemical crosslinking, by opening the anhydride cycle of the copolymer with the hydroxyl groups of hyaluronic acid, was used to prepare the bioconjugates. The chemical conjugation between HA and PITAU copolymers, as well as the structure of the new compounds, was confirmed by FTIR and NMR techniques. The physical properties of the new gels as thermal stability, swelling capacity, and rheological properties were investigated. The bioconjugate networks were also investigated as drug delivery carriers by using indomethacin as a model drug. In vitro and in vivo tests attested the homogeneity of the bioactive compounds as well as a good biochemical response, showing good biocompatibility for the new structures. Copyright © 2017 Elsevier B.V. All rights reserved.

Epithelial cell adhesion molecule aptamer functionalized PLGA-lecithin-curcumin-PEG nanoparticles for targeted drug delivery to human colorectal adenocarcinoma cells

PubMed Central

Li, Lei; Xiang, Dongxi; Shigdar, Sarah; Yang, Wenrong; Li, Qiong; Lin, Jia; Liu, Kexin; Duan, Wei

2014-01-01

To improve the efficacy of drug delivery, active targeted nanotechnology-based drug delivery systems are gaining considerable attention as they have the potential to reduce side effects, minimize toxicity, and improve efficacy of anticancer treatment. In this work CUR-NPs (curcumin-loaded lipid-polymer-lecithin hybrid nanoparticles) were synthesized and functionalized with ribonucleic acid (RNA) Aptamers (Apts) against epithelial cell adhesion molecule (EpCAM) for targeted delivery to colorectal adenocarcinoma cells. These CUR-encapsulated bioconjugates (Apt-CUR-NPs) were characterized for particle size, zeta potential, drug encapsulation, stability, and release. The in vitro specific cell binding, cellular uptake, and cytotoxicity of Apt-CUR-NPs were also studied. The Apt-CUR-NP bioconjugates exhibited increased binding to HT29 colon cancer cells and enhancement in cellular uptake when compared to CUR-NPs functionalized with a control Apt (P<0.01). Furthermore, a substantial improvement in cytotoxicity was achieved toward HT29 cells with Apt-CUR-NP bioconjugates. The encapsulation of CUR in Apt-CUR-NPs resulted in the increased bioavailability of delivered CUR over a period of 24 hours compared to that of free CUR in vivo. These results show that the EpCAM Apt-functionalized CUR-NPs enhance the targeting and drug delivery of CUR to colorectal cancer cells. Further development of CUR-encapsulated, nanosized carriers will lead to improved targeted delivery of novel chemotherapeutic agents to colorectal cancer cells. PMID:24591829

Epithelial cell adhesion molecule aptamer functionalized PLGA-lecithin-curcumin-PEG nanoparticles for targeted drug delivery to human colorectal adenocarcinoma cells.

PubMed

Li, Lei; Xiang, Dongxi; Shigdar, Sarah; Yang, Wenrong; Li, Qiong; Lin, Jia; Liu, Kexin; Duan, Wei

2014-01-01

To improve the efficacy of drug delivery, active targeted nanotechnology-based drug delivery systems are gaining considerable attention as they have the potential to reduce side effects, minimize toxicity, and improve efficacy of anticancer treatment. In this work CUR-NPs (curcumin-loaded lipid-polymer-lecithin hybrid nanoparticles) were synthesized and functionalized with ribonucleic acid (RNA) Aptamers (Apts) against epithelial cell adhesion molecule (EpCAM) for targeted delivery to colorectal adenocarcinoma cells. These CUR-encapsulated bioconjugates (Apt-CUR-NPs) were characterized for particle size, zeta potential, drug encapsulation, stability, and release. The in vitro specific cell binding, cellular uptake, and cytotoxicity of Apt-CUR-NPs were also studied. The Apt-CUR-NP bioconjugates exhibited increased binding to HT29 colon cancer cells and enhancement in cellular uptake when compared to CUR-NPs functionalized with a control Apt (P<0.01). Furthermore, a substantial improvement in cytotoxicity was achieved toward HT29 cells with Apt-CUR-NP bioconjugates. The encapsulation of CUR in Apt-CUR-NPs resulted in the increased bioavailability of delivered CUR over a period of 24 hours compared to that of free CUR in vivo. These results show that the EpCAM Apt-functionalized CUR-NPs enhance the targeting and drug delivery of CUR to colorectal cancer cells. Further development of CUR-encapsulated, nanosized carriers will lead to improved targeted delivery of novel chemotherapeutic agents to colorectal cancer cells.

Ultrasensitive dual probe immunosensor for the monitoring of nicotine induced-brain derived neurotrophic factor released from cancer cells.

PubMed

Akhtar, Mahmood H; Hussain, Khalil K; Gurudatt, N G; Chandra, Pranjal; Shim, Yoon-Bo

2018-09-30

Brain-derived neurotrophic factor (BDNF) was detected in the extracellular matrix of neuronal cells using a dual probe immunosensor (DPI), where one of them was used as a working and another bioconjugate loading probe. The working probe was fabricated by covalently immobilizing capture anti-BDNF (Cap Ab) on the gold nanoparticles (AuNPs)/conducting polymer composite layer. The bioconjugate probe was modified by drop casting a bioconjugate particles composed of conducting polymer self-assembled AuNPs, immobilized with detection anti-BDNF (Det Ab) and toluidine blue O (TBO). Each sensor layer was characterized using the surface analysis and electrochemical methods. Two modified probes were precisely faced each other to form a microfluidic channel structure and the gap between inside modified surfaces was about 19 µm. At optimized conditions, the DPI showed a linear dynamic range from 4.0 to 600.0 pg/ml with a detection limit of 1.5 ± 0.012 pg/ml. Interference effect of IgG, arginine, glutamine, serine, albumin, and fibrinogene were examined and stability of the developed biosensor was also investigated. The reliability of the DPI sensor was evaluated by monitoring the extracellular release of BDNF using exogenic activators (ethanol, K + , and nicotine) in neuronal and non-neuronal cells. In addition, the effect of nicotine onto neuroblastoma cancer cells (SH-SY5Y) was studied in detail. Copyright © 2018 Elsevier B.V. All rights reserved.

Catalase coupled gold nanoparticles: Comparison between carbodiimide and biotin-streptavidin methods

PubMed Central

Chirra, Hariharasudhan D.; Sexton, Travis; Biswal, Dipti; Hersh, Louis B.; Hilt, J. Zach

2011-01-01

The use of proteins for therapeutic applications requires the protein to maintain sufficient activity for the period of in vivo treatment. Many proteins exhibit a short half-life in vivo and, thus, require delivery systems for them to be applied as therapeutics. The relative biocompatibility and the ability to form functionalized bioconjugates via simple chemistry make gold nanoparticles excellent candidates as protein delivery systems. Herein, two protocols for coupling proteins to gold nanoparticles were compared. In the first, the strong biomolecular binding between biotin and streptavidin was used to couple catalase to the surface of gold nanoparticles. In the second protocol, the formation of an amide bond between carboxylic acid coated gold nanoparticles and free surface amines of catalase using carbodiimide chemistry was performed. The stability and kinetics of the different steps involved in these protocols were studied using UV-Visible spectroscopy, dynamic light scattering, and transmission electron microscopy. The addition of mercaptoundecanoic acid in conjugation with (N-(6-(biotinamido)hexyl)-3′-(2′-pyridyldithio)-propionamide increased the stability of biotinylated gold nanoparticles. Although the carbodiimide chemistry based bioconjugation approach exhibited a decrease in catalase activity, the carbodiimide chemistry based bioconjugation approach resulted in more active catalase per gold nanoparticle compared to that of mercaptoundecanoic acid stabilized biotinylated gold nanoparticles. Both coupling protocols resulted in gold nanoparticles loaded with active catalase. Thus, these gold nanoparticle systems and coupling protocols represent promising methods for the application of gold nanoparticles for protein delivery. PMID:21232642

Bioconjugated PLGA-4-arm-PEG branched polymeric nanoparticles as novel tumor targeting carriers

NASA Astrophysics Data System (ADS)

Ding, Hong; Yong, Ken-Tye; Roy, Indrajit; Hu, Rui; Wu, Fang; Zhao, Lingling; Law, Wing-Cheung; Zhao, Weiwei; Ji, Wei; Liu, Liwei; Bergey, Earl J.; Prasad, Paras N.

2011-04-01

In this study, we have developed a novel carrier, micelle-type bioconjugated PLGA-4-arm-PEG branched polymeric nanoparticles (NPs), for the detection and treatment of pancreatic cancer. These NPs contained 4-arm-PEG as corona, and PLGA as core, the particle surface was conjugated with cyclo(arginine-glycine-aspartate) (cRGD) as ligand for in vivo tumor targeting. The hydrodynamic size of the NPs was determined to be 150-180 nm and the critical micellar concentration (CMC) was estimated to be 10.5 mg l - 1. Our in vitro study shows that these NPs by themselves had negligible cytotoxicity to human pancreatic cancer (Panc-1) and human glioblastoma (U87) cell lines. Near infrared (NIR) microscopy and flow cytometry demonstrated that the cRGD conjugated PLGA-4-arm-PEG polymeric NPs were taken up more efficiently by U87MG glioma cells, over-expressing the αvβ3 integrin, when compared with the non-targeted NPs. Whole body imaging showed that the cRGD conjugated PLGA-4-arm-PEG branched polymeric NPs had the highest accumulation in the pancreatic tumor site of mice at 48 h post-injection. Physical, hematological, and pathological assays indicated low in vivo toxicity of this NP formulation. These studies on the ability of these bioconjugated PLGA-4-arm-PEG polymeric NPs suggest that the prepared polymeric NPs may serve as a promising platform for detection and targeted drug delivery for pancreatic cancer.

Fluorescent nanodiamonds and their use in biomedical research

NASA Astrophysics Data System (ADS)

Suarez-Kelly, Lorena P.; Rampersaud, Isaac V.; Moritz, Charles E.; Campbell, Amanda R.; Hu, Zhiwei; Alkahtani, Masfer H.; Alghannam, Fahad S.; Hemmer, Phillip; Carson, William E.; Rampersaud, Arfaan A.

2016-03-01

Nanodiamonds containing color-centers produce non-quenching fluorescence that is easily detected. This makes them useful for cellular, proteomic and genomic applications. However, fluorescent nanodiamonds have yet to become popular in the biomedical research community as labeling reagents. We discuss production of nanodiamonds with distinct color-centers and assess their biocompatibility and techniques for bioconjugation. Fluorescent diamonds were fabricated by electron irradiation of high-pressure, high-temperature micron-sized diamonds which generated diamonds with vacancy-related defects (V). These diamonds were annealed to create nitrogen vacancy (NV)-centers then following a milling step were fractionated into nanoparticle sizes of 30, 60, and 95 nm. Optical characterization of Vand NV-center diamonds demonstrated fluorescence in two distinct green and red channels, respectively. In vitro studies demonstrated that these nanodiamonds are biocompatible and readily taken up by murine macrophage cells. Quantification of NV-center nanodiamond uptake by flow cytometry, showed that uptake was independent of nanodiamond size. Confocal microscopy demonstrated that NV-center nanodiamonds accumulate within the cytoplasm of these cells. NV-center nanodiamonds were then conjugated with streptavidin using a short polyethylene chain as linker. Conjugation was confirmed via a catalytic assay employing biotinylated-horseradish peroxidase. We present a technique for large-scale production of biocompatible conjugated V- or NV-center nanodiamonds. Functional testing is essential for standardization of fluorescent nanodiamond bioconjugates and quality control. Large-scale production of bioconjugated fluorescent nanodiamonds is crucial to their development as novel tools for biological and medical applications.

Rab3A Inhibition of Ca2+ -Dependent Dopamine Release From PC12 Cells Involves Interaction With Synaptotagmin I.

PubMed

Dai, Zhipan; Tang, Xia; Chen, Jia; Tang, Xiaochao; Wang, Xianchun

2017-11-01

Rab3 and synaptotagmin have been suggested to play important roles in the regulation of neurotransmitter release and, however, the molecular mechanism has not been completely clear. Here, we studied the effects of Rab3A and synaptotagmin I (Syt I) on dopamine release using PC12 cells as a model system. Rab3A was demonstrated to have effects on both Ca 2+ -independent and Ca 2+ -dependent dopamine releases from the PC12 cells. Application of Rab3A (up to 2500 nM) gradually decreased the amount of Ca 2+ -dependently released dopamine, indicating that Rab3A is a negative modulator that was further supported by the increase in dopamine release caused by Rab3A knockdown. Syt I knockdown weakened the Ca 2+ -dependent dopamine release, suggesting that Syt I plays a positive regulatory role in the cellular process. Treatment of the Syt I-knocked down PC12 cells with Rab3A further decreased Ca 2+ -dependent dopamine release and, however, the decrease magnitude was significantly reduced compared with that before Syt I knockdown, thus for the first time demonstrating that the inhibitory effect of Rab3A on Ca 2+ -dependent dopamine release involves the interaction with Syt I. This work has shed new light on the molecular mechanism for Rab3 and synaptotamin regulation of neurotransmitter release. J. Cell. Biochem. 118: 3696-3705, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Dopamine and Pain Sensitivity: Neither Sulpiride nor Acute Phenylalanine and Tyrosine Depletion Have Effects on Thermal Pain Sensations in Healthy Volunteers

PubMed Central

Becker, Susanne; Ceko, Marta; Louis-Foster, Mytsumi; Elfassy, Nathaniel M.; Leyton, Marco; Shir, Yoram; Schweinhardt, Petra

2013-01-01

Based on animal studies and some indirect clinical evidence, dopamine has been suggested to have anti-nociceptive effects. Here, we investigated directly the effects of increased and decreased availability of extracellular dopamine on pain perception in healthy volunteers. In Study 1, participants ingested, in separate sessions, a placebo and a low dose of the centrally acting D2-receptor antagonist sulpiride, intended to increase synaptic dopamine via predominant pre-synaptic blockade. No effects were seen on thermal pain thresholds, tolerance, or temporal summation. Study 2 used the acute phenylalanine and tyrosine depletion (APTD) method to transiently decrease dopamine availability. In one session participants ingested a mixture that depletes the dopamine amino acid precursors, phenylalanine and tyrosine. In the other session they ingested a nutritionally balanced control mixture. APTD led to a small mood-lowering response following aversive thermal stimulation, but had no effects on the perception of cold, warm, or pain stimuli. In both studies the experimental manipulation of dopaminergic neurotransmission was successful as indicated by manipulation checks. The results contradict proposals that dopamine has direct anti-nociceptive effects in acute experimental pain. Based on dopamine’s well-known role in reward processing, we hypothesize that also in the context of pain, dopamine acts on stimulus salience and might play a role in the initiation of avoidance behavior rather than having direct antinociceptive effects in acute experimental pain. PMID:24236199

Highly selective determination of dopamine in the presence of ascorbic acid and serotonin at glassy carbon electrodes modified with carbon nanotubes dispersed in polyethylenimine.

PubMed

Rodríguez, Marcela C; Rubianes, María D; Rivas, Gustavo A

2008-11-01

We report the highly selective and sensitive voltammetric dopamine quantification in the presence of ascorbic acid and serotonin by using glassy carbon electrodes modified with a dispersion of multi-wall carbon nanotubes (MWCNT) in polyethylenimine, PEI (GCE/MWCNT-PEI). The electrocatalytic activity of the MWCNT deposited on the glassy carbon electrode has allowed an important decrease in the overvoltages for the oxidation of ascorbic acid and dopamine, making possible a clear definition of dopamine, serotonin and ascorbic acid oxidation processes. The sensitivities for dopamine in the presence and absence of 1.0 mM ascorbic acid and serotonin were (2.18 +/- 0.03) x 10(5) microAM(-1) (r = 0.9998); and (2.10 +/- 0.07) x 10(5) miroAM(-1) (r=0.9985), respectively, demonstrating the excellent performance of the GCE/MWCNT-PEI. The detection limit for dopamine in the mixture was 9.2 x 10(-7) M. The R. S. D. for the determination of 50 microM dopamine using four different electrodes was 3.9% when modified with the same MWCNT/PEI dispersion, and 4.6% when using four different dispersions. The modified electrode has been successfully applied for recovery assays of dopamine in human blood serum. Therefore, the new sensor represents an interesting and promising alternative for the electrochemical quantification of neurotransmitters and other analytes of clinical interest.

Technical brief: a comparison of two methods of euthanasia on retinal dopamine levels.

PubMed

Hwang, Christopher K; Iuvone, P Michael

2013-01-01

Mice are commonly used in biomedical research, and euthanasia is an important part of mouse husbandry. Approved, humane methods of euthanasia are designed to minimize the potential for pain or discomfort, but may also influence the measurement of experimental variables. We compared the effects of two approved methods of mouse euthanasia on the levels of retinal dopamine. We examined the level of retinal dopamine, a commonly studied neuromodulator, following euthanasia by carbon dioxide (CO₂)-induced asphyxiation or by cervical dislocation. We found that the level of retinal dopamine in mice euthanized through CO₂ overdose substantially differed from that in mice euthanized through cervical dislocation. The use of CO₂ as a method of euthanasia could result in an experimental artifact that could compromise results when studying labile biologic processes.

Developmental origins of brain disorders: roles for dopamine

PubMed Central

Money, Kelli M.; Stanwood, Gregg D.

2013-01-01

Neurotransmitters and neuromodulators, such as dopamine, participate in a wide range of behavioral and cognitive functions in the adult brain, including movement, cognition, and reward. Dopamine-mediated signaling plays a fundamental neurodevelopmental role in forebrain differentiation and circuit formation. These developmental effects, such as modulation of neuronal migration and dendritic growth, occur before synaptogenesis and demonstrate novel roles for dopaminergic signaling beyond neuromodulation at the synapse. Pharmacologic and genetic disruptions demonstrate that these effects are brain region- and receptor subtype-specific. For example, the striatum and frontal cortex exhibit abnormal neuronal structure and function following prenatal disruption of dopamine receptor signaling. Alterations in these processes are implicated in the pathophysiology of neuropsychiatric disorders, and emerging studies of neurodevelopmental disruptions may shed light on the pathophysiology of abnormal neuronal circuitry in neuropsychiatric disorders. PMID:24391541

Dopamine modulates the neural representation of subjective value of food in hungry subjects.

PubMed

Medic, Nenad; Ziauddeen, Hisham; Vestergaard, Martin D; Henning, Elana; Schultz, Wolfram; Farooqi, I Sadaf; Fletcher, Paul C

2014-12-10

Although there is a rich literature on the role of dopamine in value learning, much less is known about its role in using established value estimations to shape decision-making. Here we investigated the effect of dopaminergic modulation on value-based decision-making for food items in fasted healthy human participants. The Becker-deGroot-Marschak auction, which assesses subjective value, was examined in conjunction with pharmacological fMRI using a dopaminergic agonist and an antagonist. We found that dopamine enhanced the neural response to value in the inferior parietal gyrus/intraparietal sulcus, and that this effect predominated toward the end of the valuation process when an action was needed to record the value. Our results suggest that dopamine is involved in acting upon the decision, providing additional insight to the mechanisms underlying impaired decision-making in healthy individuals and clinical populations with reduced dopamine levels. Copyright © 2014 the authors 0270-6474/14/3416856-09$15.00/0.

Dopamine and anorexia nervosa.

PubMed

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

2016-01-01

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

Molecular basis of the dopaminergic system in the cricket Gryllus bimaculatus.

PubMed

Watanabe, Takayuki; Sadamoto, Hisayo; Aonuma, Hitoshi

2013-12-01

In insects, dopamine modulates various aspects of behavior such as learning and memory, arousal and locomotion, and is also a precursor of melanin. To elucidate the molecular basis of the dopaminergic system in the field cricket Gryllus bimaculatus DeGeer, we identified genes involved in dopamine biosynthesis, signal transduction, and dopamine re-uptake in the cricket. Complementary DNA of two isoforms of tyrosine hydroxylase (TH), which convert tyrosine into L-3,4-dihydroxyphenylalanine, was isolated from the cricket brain cDNA library. In addition, four dopamine receptor genes (Dop1, Dop2, Dop3, and DopEcR) and a high-affinity dopamine transporter gene were identified. The two TH isoforms contained isoform-specific regions in the regulatory ACT domain and showed differential expression patterns in different tissues. In addition, the dopamine receptor genes had a receptor subtype-specific distribution: the Dop1, Dop2, and DopEcR genes were broadly expressed in various tissues at differential expression levels, and the Dop3 gene was restrictedly expressed in neuronal tissues and the testicles. Our findings provide a fundamental basis for understanding the dopaminergic regulation of diverse physiological processes in the cricket.

Dopamine alleviates nutrient deficiency-induced stress in Malus hupehensis.

PubMed

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

2017-10-01

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

Click Chemistry in Complex Mixtures: Bioorthogonal Bioconjugation

PubMed Central

McKay, Craig S.; Finn, M.G.

2014-01-01

The selective chemical modification of biological molecules drives a good portion of modern drug development and fundamental biological research. While a few early examples of reactions that engage amine and thiol groups on proteins helped establish the value of such processes, the development of reactions that avoid most biological molecules so as to achieve selectivity in desired bond-forming events has revolutionized the field. We provide an update on recent developments in bioorthogonal chemistry that highlights key advances in reaction rates, biocompatibility, and applications. While not exhaustive, we hope this summary allows the reader to appreciate the rich continuing development of good chemistry that operates in the biological setting. PMID:25237856

Extending the versatility of the Hemetsberger-Knittel indole synthesis through microwave and flow chemistry.

PubMed

Ranasinghe, Nadeesha; Jones, Graham B

2013-03-15

Microwave, flow and combination methodologies have been applied to the synthesis of a number of substituted indoles. Based on the Hemetsberger-Knittel (HK) process, modifications allow formation of products rapidly and in high yield. Adapting the methodology allows formation of 2-unsubstituted indoles and derivatives, and a route to analogs of the antitumor agent PLX-4032 is demonstrated. The utility of the HK substrates is further demonstrated through bioconjugation and subsequent ring closure and via Huisgen type [3+2] cycloaddition chemistry, allowing formation of peptide adducts which can be subsequently labeled with fluorine tags. Copyright © 2013 Elsevier Ltd. All rights reserved.

Stochastic Simulation of Dopamine Neuromodulation for Implementation of Fluorescent Neurochemical Probes in the Striatal Extracellular Space.

PubMed

Beyene, Abraham G; McFarlane, Ian R; Pinals, Rebecca L; Landry, Markita P

2017-10-18

Imaging the dynamic behavior of neuromodulatory neurotransmitters in the extracelluar space that arise from individual quantal release events would constitute a major advance in neurochemical imaging. Spatial and temporal resolution of these highly stochastic neuromodulatory events requires concurrent advances in the chemical development of optical nanosensors selective for neuromodulators in concert with advances in imaging methodologies to capture millisecond neurotransmitter release. Herein, we develop and implement a stochastic model to describe dopamine dynamics in the extracellular space (ECS) of the brain dorsal striatum to guide the design and implementation of fluorescent neurochemical probes that record neurotransmitter dynamics in the ECS. Our model is developed from first-principles and simulates release, diffusion, and reuptake of dopamine in a 3D simulation volume of striatal tissue. We find that in vivo imaging of neuromodulation requires simultaneous optimization of dopamine nanosensor reversibility and sensitivity: dopamine imaging in the striatum or nucleus accumbens requires nanosensors with an optimal dopamine dissociation constant (K d ) of 1 μM, whereas K d s above 10 μM are required for dopamine imaging in the prefrontal cortex. Furthermore, as a result of the probabilistic nature of dopamine terminal activity in the striatum, our model reveals that imaging frame rates of 20 Hz are optimal for recording temporally resolved dopamine release events. Our work provides a modeling platform to probe how complex neuromodulatory processes can be studied with fluorescent nanosensors and enables direct evaluation of nanosensor chemistry and imaging hardware parameters. Our stochastic model is generic for evaluating fluorescent neurotransmission probes, and is broadly applicable to the design of other neurotransmitter fluorophores and their optimization for implementation in vivo.

Opposite Actions of Dopamine on Aversive and Appetitive Memories in the Crab

ERIC Educational Resources Information Center

Klappenbach, Martin; Maldonado, Hector; Locatelli, Fernando; Kaczer, Laura

2012-01-01

The understanding of how the reinforcement is represented in the central nervous system during memory formation is a current issue in neurobiology. Several studies in insects provide evidence of the instructive role of biogenic amines during the learning and memory process. In insects it was widely accepted that dopamine (DA) mediates aversive…

Dopamine transporter availability in clinically normal aging is associated with individual differences in white matter integrity.

PubMed

Rieckmann, Anna; Hedden, Trey; Younger, Alayna P; Sperling, Reisa A; Johnson, Keith A; Buckner, Randy L

2016-02-01

Aging-related differences in white matter integrity, the presence of amyloid plaques, and density of biomarkers indicative of dopamine functions can be detected and quantified with in vivo human imaging. The primary aim of the present study was to investigate whether these imaging-based measures constitute independent imaging biomarkers in older adults, which would speak to the hypothesis that the aging brain is characterized by multiple independent neurobiological cascades. We assessed MRI-based markers of white matter integrity and PET-based marker of dopamine transporter density and amyloid deposition in the same set of 53 clinically normal individuals (age 65-87). A multiple regression analysis demonstrated that dopamine transporter availability is predicted by white matter integrity, which was detectable even after controlling for chronological age. Further post-hoc exploration revealed that dopamine transporter availability was further associated with systolic blood pressure, mirroring the established association between cardiovascular health and white matter integrity. Dopamine transporter availability was not associated with the presence of amyloid burden. Neurobiological correlates of dopamine transporter measures in aging are therefore likely unrelated to Alzheimer's disease but are aligned with white matter integrity and cardiovascular risk. More generally, these results suggest that two common imaging markers of the aging brain that are typically investigated separately do not reflect independent neurobiological processes. Hum Brain Mapp 37:621-631, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Differential dependence of Pavlovian incentive motivation and instrumental incentive learning processes on dopamine signaling

PubMed Central

Wassum, Kate M.; Ostlund, Sean B.; Balleine, Bernard W.; Maidment, Nigel T.

2011-01-01

Here we attempted to clarify the role of dopamine signaling in reward seeking. In Experiment 1, we assessed the effects of the dopamine D1/D2 receptor antagonist flupenthixol (0.5 mg/kg i.p.) on Pavlovian incentive motivation and found that flupenthixol blocked the ability of a conditioned stimulus to enhance both goal approach and instrumental performance (Pavlovian-to-instrumental transfer). In Experiment 2 we assessed the effects of flupenthixol on reward palatability during post-training noncontingent re-exposure to the sucrose reward in either a control 3-h or novel 23-h food-deprived state. Flupenthixol, although effective in blocking the Pavlovian goal approach, was without effect on palatability or the increase in reward palatability induced by the upshift in motivational state. This noncontingent re-exposure provided an opportunity for instrumental incentive learning, the process by which rats encode the value of a reward for use in updating reward-seeking actions. Flupenthixol administered prior to the instrumental incentive learning opportunity did not affect the increase in subsequent off-drug reward-seeking actions induced by that experience. These data suggest that although dopamine signaling is necessary for Pavlovian incentive motivation, it is not necessary for changes in reward experience, or for the instrumental incentive learning process that translates this experience into the incentive value used to drive reward-seeking actions, and provide further evidence that Pavlovian and instrumental incentive learning processes are dissociable. PMID:21693635

Primary structure and functional characterization of a Drosophila dopamine receptor with high homology to human D1/5 receptors.

PubMed

Gotzes, F; Balfanz, S; Baumann, A

1994-01-01

Members of the superfamily of G-protein coupled receptors share significant similarities in sequence and transmembrane architecture. We have isolated a Drosophila homologue of the mammalian dopamine receptor family using a low stringency hybridization approach. The deduced amino acid sequence is approximately 70% homologous to the human D1/D5 receptors. When expressed in HEK 293 cells, the Drosophila receptor stimulates cAMP production in response to dopamine application. This effect was mimicked by SKF 38393, a specific D1 receptor agonist, but inhibited by dopaminergic antagonists such as butaclamol and flupentixol. In situ hybridization revealed that the Drosophila dopamine receptor is highly expressed in the somata of the optic lobes. This suggests that the receptor might be involved in the processing of visual information and/or visual learning in invertebrates.

Curcumin Monoglucoside Shows Improved Bioavailability and Mitigates Rotenone Induced Neurotoxicity in Cell and Drosophila Models of Parkinson's Disease.

PubMed

Pandareesh, M D; Shrivash, M K; Naveen Kumar, H N; Misra, K; Srinivas Bharath, M M

2016-11-01

Curcumin (CUR), a dietary polyphenol has diverse pharmacologic effects, but is limited by poor bioavailability. This is probably due to decreased solubility, cellular uptake and stability. In order to enhance its solubility and bioavailability, we synthesized the CUR bioconjugate curcumin monoglucoside (CMG) and tested its bioavailability, neuroprotective and anti-apoptotic propensity against rotenone (ROT) induced toxicity in N27 dopaminergic neuronal cells and Drosophila models. Our results elucidate that CMG showed improved bioavailability than CUR in N27 cells. Pre-treatment with CMG protected against ROT neurotoxicity and exerted antioxidant effects by replenishing cellular glutathione levels and significantly decreasing reactive species. CMG pre-treatment also restored mitochondrial complex I and IV activities inhibited by ROT. ROT-induced nuclear damage was also restored by CMG as confirmed by comet assay. CMG induced anti-apoptotic effects was substantiated by decreased phosporylation of JNK3 and c-jun, which in turn decreased the cleavage of pro-caspase 3. Q-PCR analysis of redox genes showed up-regulation of NOS2 and down-regulation of NQO1 upon ROT exposure and this was attenuated by CMG pre-treatment. Studies in the Drosophila ROT model revealed that, CMG administration showed better survival rate and locomotor activity, improved antioxidant activity and dopamine content than ROT treated group and was comparable with the CUR group. Based on these data, we surmise that CMG has improved bioavailability and offered neuroprotection comparable with CUR, against ROT-induced toxicity both in dopaminergic neuronal cell line and Drosophila models, with therapeutic implications for PD.

Compromised NMDA/Glutamate Receptor Expression in Dopaminergic Neurons Impairs Instrumental Learning, But Not Pavlovian Goal Tracking or Sign Tracking

PubMed

James, Alex S; Pennington, Zachary T; Tran, Phu; Jentsch, James David

2015-01-01

Two theories regarding the role for dopamine neurons in learning include the concepts that their activity serves as a (1) mechanism that confers incentive salience onto rewards and associated cues and/or (2) contingency teaching signal reflecting reward prediction error. While both theories are provocative, the causal role for dopamine cell activity in either mechanism remains controversial. In this study mice that either fully or partially lacked NMDARs in dopamine neurons exclusively, as well as appropriate controls, were evaluated for reward-related learning; this experimental design allowed for a test of the premise that NMDA/glutamate receptor (NMDAR)-mediated mechanisms in dopamine neurons, including NMDA-dependent regulation of phasic discharge activity of these cells, modulate either the instrumental learning processes or the likelihood of pavlovian cues to become highly motivating incentive stimuli that directly attract behavior. Loss of NMDARs in dopamine neurons did not significantly affect baseline dopamine utilization in the striatum, novelty evoked locomotor behavior, or consumption of a freely available, palatable food solution. On the other hand, animals lacking NMDARs in dopamine cells exhibited a selective reduction in reinforced lever responses that emerged over the course of instrumental learning. Loss of receptor expression did not, however, influence the likelihood of an animal acquiring a pavlovian conditional response associated with attribution of incentive salience to reward-paired cues (sign tracking). These data support the view that reductions in NMDAR signaling in dopamine neurons affect instrumental reward-related learning but do not lend support to hypotheses that suggest that the behavioral significance of this signaling includes incentive salience attribution.

Motivational salience and genetic variability of dopamine D2 receptor expression interact in the modulation of interference processing

PubMed Central

Richter, Anni; Richter, Sylvia; Barman, Adriana; Soch, Joram; Klein, Marieke; Assmann, Anne; Libeau, Catherine; Behnisch, Gusalija; Wüstenberg, Torsten; Seidenbecher, Constanze I.; Schott, Björn H.

2013-01-01

Dopamine has been implicated in the fine-tuning of complex cognitive and motor function and also in the anticipation of future rewards. This dual function of dopamine suggests that dopamine might be involved in the generation of active motivated behavior. The DRD2 TaqIA polymorphism of the dopamine D2 receptor gene (rs1800497) has previously been suggested to affect striatal function with carriers of the less common A1 allele exhibiting reduced striatal D2 receptor density and increased risk for addiction. Here we aimed to investigate the influences of DRD2 TaqIA genotype on the modulation of interference processing by reward and punishment. Forty-six young, healthy volunteers participated in a behavioral experiment, and 32 underwent functional magnetic resonance imaging (fMRI). Participants performed a flanker task with a motivation manipulation (monetary reward, monetary loss, neither, or both). Reaction times (RTs) were shorter in motivated flanker trials, irrespective of congruency. In the fMRI experiment motivation was associated with reduced prefrontal activation during incongruent vs. congruent flanker trials, possibly reflecting increased processing efficiency. DRD2 TaqIA genotype did not affect overall RTs, but interacted with motivation on the congruency-related RT differences, with A1 carriers showing smaller interference effects to reward alone and A2 homozygotes exhibiting a specific interference reduction during combined reward (REW) and punishment trials (PUN). In fMRI, anterior cingulate activity showed a similar pattern of genotype-related modulation. Additionally, A1 carriers showed increased anterior insula activation relative to A2 homozygotes. Our results point to a role for genetic variations of the dopaminergic system in individual differences of cognition-motivation interaction. PMID:23760450

Dopaminergic Balance between Reward Maximization and Policy Complexity

PubMed Central

Parush, Naama; Tishby, Naftali; Bergman, Hagai

2011-01-01

Previous reinforcement-learning models of the basal ganglia network have highlighted the role of dopamine in encoding the mismatch between prediction and reality. Far less attention has been paid to the computational goals and algorithms of the main-axis (actor). Here, we construct a top-down model of the basal ganglia with emphasis on the role of dopamine as both a reinforcement learning signal and as a pseudo-temperature signal controlling the general level of basal ganglia excitability and motor vigilance of the acting agent. We argue that the basal ganglia endow the thalamic-cortical networks with the optimal dynamic tradeoff between two constraints: minimizing the policy complexity (cost) and maximizing the expected future reward (gain). We show that this multi-dimensional optimization processes results in an experience-modulated version of the softmax behavioral policy. Thus, as in classical softmax behavioral policies, probability of actions are selected according to their estimated values and the pseudo-temperature, but in addition also vary according to the frequency of previous choices of these actions. We conclude that the computational goal of the basal ganglia is not to maximize cumulative (positive and negative) reward. Rather, the basal ganglia aim at optimization of independent gain and cost functions. Unlike previously suggested single-variable maximization processes, this multi-dimensional optimization process leads naturally to a softmax-like behavioral policy. We suggest that beyond its role in the modulation of the efficacy of the cortico-striatal synapses, dopamine directly affects striatal excitability and thus provides a pseudo-temperature signal that modulates the tradeoff between gain and cost. The resulting experience and dopamine modulated softmax policy can then serve as a theoretical framework to account for the broad range of behaviors and clinical states governed by the basal ganglia and dopamine systems. PMID:21603228

Bis(dipyridophenazine)(2-(2'-pyridyl)pyrimidine-4-carboxylic acid)ruthenium(II) hexafluorophosphate: a lesson in stubbornness.

PubMed

Joshi, Tanmaya; Pierroz, Vanessa; Ferrari, Stefano; Gasser, Gilles

2014-07-01

Ruthenium complexes are currently considered to be among the most promising alternatives to platinum anticancer drugs. In this work, thirteen structural analogues and organelle/receptor-targeting peptide bioconjugates of a cytotoxic bis(dppz)-Ru(II) complex [Ru(dppz)2 (CppH)](PF6 )2 (1) were prepared, characterized, and assessed for their cytotoxicity and cellular localization (CppH=2-(2'-pyridyl)pyrimidine-4-carboxylic acid; dppz=dipyrido[3,2-a:2',3'-c]phenazine). It was observed that structural modifications (lipophilicity, charge, and size-based) result in the cytotoxic potency of 1 being compromised. Confocal microscopy studies revealed that unlike 1, the screened complexes/bioconjugates do not have a preferential accumulation in mitochondria. The results of this important structure-activity relationship strongly support our initial hypothesis that accumulation in mitochondria is crucial for 1 to exert its cytotoxic action. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

PRINT: A Protein Bioconjugation Method with Exquisite N-terminal Specificity

PubMed Central

Sur, Surojit; Qiao, Yuan; Fries, Anja; O’Meally, Robert N.; Cole, Robert N.; Kinzler, Kenneth W.; Vogelstein, Bert; Zhou, Shibin

2015-01-01

Chemical conjugation is commonly used to enhance the pharmacokinetics, biodistribution, and potency of protein therapeutics, but often leads to non-specific modification or loss of bioactivity. Here, we present a simple, versatile and widely applicable method that allows exquisite N-terminal specific modification of proteins. Combining reversible side-chain blocking and protease mediated cleavage of a commonly used HIS tag appended to a protein, we generate with high yield and purity exquisitely site specific and selective bio-conjugates of TNF-α by using amine reactive NHS ester chemistry. We confirm the N terminal selectivity and specificity using mass spectral analyses and show near complete retention of the biological activity of our model protein both in vitro and in vivo murine models. We believe that this methodology would be applicable to a variety of potentially therapeutic proteins and the specificity afforded by this technique would allow for rapid generation of novel biologics. PMID:26678960

Modular assembly of proteins on nanoparticles.

PubMed

Ma, Wenwei; Saccardo, Angela; Roccatano, Danilo; Aboagye-Mensah, Dorothy; Alkaseem, Mohammad; Jewkes, Matthew; Di Nezza, Francesca; Baron, Mark; Soloviev, Mikhail; Ferrari, Enrico

2018-04-16

Generally, the high diversity of protein properties necessitates the development of unique nanoparticle bio-conjugation methods, optimized for each different protein. Here we describe a universal bio-conjugation approach which makes use of a new recombinant fusion protein combining two distinct domains. The N-terminal part is Glutathione S-Transferase (GST) from Schistosoma japonicum, for which we identify and characterize the remarkable ability to bind gold nanoparticles (GNPs) by forming gold-sulfur bonds (Au-S). The C-terminal part of this multi-domain construct is the SpyCatcher from Streptococcus pyogenes, which provides the ability to capture recombinant proteins encoding a SpyTag. Here we show that SpyCatcher can be immobilized covalently on GNPs through GST without the loss of its full functionality. We then show that GST-SpyCatcher activated particles are able to covalently bind a SpyTag modified protein by simple mixing, through the spontaneous formation of an unusual isopeptide bond.

Spectroscopic and photoacoustic characterization of encapsulated iron oxide super-paramagnetic nanoparticles as a new multiplatform contrast agent.

PubMed

Armanetti, Paolo; Flori, Alessandra; Avigo, Cinzia; Conti, Luca; Valtancoli, Barbara; Petroni, Debora; Doumett, Saer; Cappiello, Laura; Ravagli, Costanza; Baldi, Giovanni; Bencini, Andrea; Menichetti, Luca

2018-06-15

Recently, a number of photoacoustic (PA) agents with increased tissue penetration and fine spatial resolution have been developed for molecular imaging and mapping of pathophysiological features at the molecular level. Here, we present bio-conjugated near-infrared light-absorbing magnetic nanoparticles as a new agent for PA imaging. These nanoparticles exhibit suitable absorption in the near-infrared region, with good photoacoustic signal generation efficiency and high photo-stability. Furthermore, these encapsulated iron oxide nanoparticles exhibit strong super-paramagnetic behavior and nuclear relaxivities that make them useful as magnetic resonance imaging (MRI) contrast media as well. Their simple bio-conjugation strategy, optical and chemical stability, and straightforward manipulation could enable the development of a PA probe with magnetic and spectroscopic properties suitable for in vitro and in vivo real-time imaging of relevant biological targets. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis of aldehyde-linked nucleotides and DNA and their bioconjugations with lysine and peptides through reductive amination.

PubMed

Raindlová, Veronika; Pohl, Radek; Hocek, Michal

2012-03-26

5-(5-Formylthienyl)-, 5-(4-formylphenyl)- and 5-(2-fluoro-5-formylphenyl)cytosine 2'-deoxyribonucleoside mono- (dC(R)MP) and triphosphates (dC(R)TP) were prepared by aqueous Suzuki-Miyaura cross-coupling of 5-iodocytosine nucleotides with the corresponding formylarylboronic acids. The dC(R)TPs were excellent substrates for DNA polymerases and were incorporated into DNA by primer extension or PCR. Reductive aminations of the model dC(R)MPs with lysine or lysine-containing tripeptide were studied and optimized. In aqueous phosphate buffer (pH 6.7) the yields of the reductive aminations with tripeptide III were up to 25 %. Bioconjugation of an aldehyde-containing DNA with a lysine-containing tripeptide was achieved through reductive amination in yields of up to 90 % in aqueous phosphate buffer. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reinforcement in an in Vitro Analog of Appetitive Classical Conditioning of Feeding Behavior in "Aplysia": Blockade by a Dopamine Antagonist

ERIC Educational Resources Information Center

Reyes, Fredy D.; Mozzachiodi, Riccardo; Baxter, Douglas A.; Byrne, John H.

2005-01-01

In a recently developed in vitro analog of appetitive classical conditioning of feeding in "Aplysia," the unconditioned stimulus (US) was electrical stimulation of the esophageal nerve (En). This nerve is rich in dopamine (DA)-containing processes, which suggests that DA mediates reinforcement during appetitive conditioning. To test this…

Individual Differences in Dopamine Efflux in Nucleus Accumbens Shell and Core during Instrumental Learning

ERIC Educational Resources Information Center

Cheng, Jingjun; Feenstra, Matthijs G. P.

2006-01-01

Combined activation of dopamine D1- and NMDA-glutamate receptors in the nucleus accumbens has been strongly implicated in instrumental learning, the process in which an individual learns that a specific action has a wanted outcome. To assess dopaminergic activity, we presented rats with two sessions (30 trials each) of a one-lever appetitive…

Use of monoclonal antibody-IRDye800CW bioconjugates in the resection of breast cancer

PubMed Central

Korb, Melissa L.; Hartman, Yolanda E.; Kovar, Joy; Zinn, Kurt R.; Bland, Kirby I.; Rosenthal, Eben L.

2015-01-01

Background Complete surgical resection of breast cancer is a powerful determinant of patient outcome, and failure to achieve negative margins results in reoperation in between 30% and 60% of patients. We hypothesize that repurposing Food and Drug Administration approved antibodies as tumor-targeting diagnostic molecules can function as optical contrast agents to identify the boundaries of malignant tissue intraoperatively. Materials and methods The monoclonal antibodies bevacizumab, cetuximab, panitumumab, trastuzumab, and tocilizumab were covalently linked to a near-infrared fluorescence probe (IRDye800CW) and in vitro binding assays were performed to confirm ligand-specific binding. Nude mice bearing human breast cancer flank tumors were intravenously injected with the antibody-IRDye800 bioconjugates and imaged over time. Tumor resections were performed using the SPY and Pearl Impulse systems, and the presence or absence of tumor was confirmed by conventional and fluorescence histology. Results Tumor was distinguishable from normal tissue using both SPY and Pearl systems, with both platforms being able to detect tumor as small as 0.5 mg. Serial surgical resections demonstrated that real-time fluorescence can differentiate subclinical segments of disease. Pathologic examination of samples by conventional and optical histology using the Odyssey scanner confirmed that the bioconjugates were specific for tumor cells and allowed accurate differentiation of malignant areas from normal tissue. Conclusions Human breast cancer tumors can be imaged in vivo with multiple optical imaging platforms using near-infrared fluorescently labeled antibodies. These data support additional preclinical investigations for improving the surgical resection of malignancies with the goal of eventual clinical translation. PMID:24360117

In Situ Generation and Consumption of H2O2 by Bienzyme-Quantum Dots Bioconjugates for Improved Chemiluminescence Resonance Energy Transfer.

PubMed

Xu, Shuxia; Li, Xianming; Li, Chaobi; Li, Jialin; Zhang, Xinfeng; Wu, Peng; Hou, Xiandeng

2016-06-21

Exploration of quantum dots (QDs) as energy acceptors revolutionizes the current chemiluminescence resonance energy transfer (CRET), since QDs possess large Stokes shifts and high luminescence efficiency. However, the strong and high concentration of oxidant (typically H2O2) needed for luminol chemiluminescence (CL) reaction could cause oxidative quenching to QDs, thereby decreasing the CRET performance. Here we proposed the use of bienzyme-QDs bioconjugate as the energy acceptor for improved CRET sensing. Two enzymes, one for H2O2 generation (oxidase) and another for H2O2 consumption (horseradish peroxidase, HRP), were bioconjugated onto the surface of QDs. The bienzyme allowed fast in situ cascaded H2O2 generation and consumption, thus alleviating fluorescence quenching of QDs. The nanosized QDs accommodate the two enzymes in a nanometric range, and the CL reaction was confined on the surface of QDs accordingly, thereby amplifying the CL reaction rate and improving CRET efficiency. As a result, CRET efficiency of 30-38% was obtained; the highest CRET efficiency by far was obtained using QDs as the energy acceptor. The proposed CRET system could be explored for ultrasensitive sensing of various oxidase substrates (here exemplified with cholesterol, glucose, and benzylamine), allowing for quantitative measurement of a spectrum of metabolites with high sensitivity and specificity. Limits of detection (LOD, 3σ) for cholesterol, glucose, and benzylamine were found to be 0.8, 3.4, and 10 nM, respectively. Furthermore, multiparametric blood analysis (glucose and cholesterol) is demonstrated.

Biosynthesis of insulin-silk fibroin nanoparticles conjugates and in vitro evaluation of a drug delivery system

NASA Astrophysics Data System (ADS)

Yan, Hai-Bo; Zhang, Yu-Qing; Ma, Yong-Lei; Zhou, Li-Xia

2009-11-01

Silk fibroin derived from Bombyx mori is a biomacromolecular protein with outstanding biocompatibility. When it was dissolved in highly concentrated CaCl2 solution and then the mixture of the protein and salt was subjected to desalting treatments for long time in flowing water, the resulting liquid silk was water-soluble polypeptides with different molecular masses, ranging from 8 to 70 kDa. When the liquid silk was introduced rapidly into acetone, silk protein nanoparticles with a range of 40-120 nm in diameter could be obtained. The crystalline silk nanoparticles could be conjugated covalently with insulin alone with cross-linking reagent glutaraldehyde. In vitro properties of the insulin-silk fibroin nanoparticles (Ins-SFN) bioconjugates were determined by Enzyme-Linked Immunosorbent Assay (ELISA). The optimal conditions for the biosynthesis of Ins-SFN bioconjugates were investigated. The Ins-SFN constructs obtained by 8 h of covalent cross-linking with 0.7% cross-linking reagent and the proportion of insulin and SFN being 30 IU: 15 mg showed much higher recoveries (90-115%). When insulin was coupled covalently with silk nanoparticles, the resistance of the modified insulin to trypsin digestion and in vitro stability in human serum were greatly enhanced as compared with insulin alone. The results in human serum indicated that the half-life in vitro of the biosynthesized Ins-SFN derivatives was about 2.5 times more than that of native insulin. Therefore, the silk protein nanoparticles have the potential values for being studied and developed as a new bioconjugate for enzyme/polypeptide drug delivery system.

A multifunctional hemin@metal-organic framework and its application to construct an electrochemical aptasensor for thrombin detection.

PubMed

Xie, Shunbi; Ye, Jiawei; Yuan, Yali; Chai, Yaqin; Yuan, Ruo

2015-11-21

A new type of multifunctional metal-organic framework (MOF) has been synthesized by encapsulating hemin into the nano-sized Fe-MIL-88 MOFs (hemin@MOFs) and first applied in an electrochemical aptasensor to detect thrombin (TB) with the aid of an enzyme for signal amplification. The gold nanoparticle functionalized hemin@MOFs (Au/hemin@MOFs) have not only simultaneously served as redox mediators and solid electrocatalysts, but have also been utilized as an ideal loading platform to immobilize a large number of biomolecules. In this aptasensor, Au/hemin@MOFs conjugated with glucose oxidase (GOD) and thrombin binding aptamer (TBA II) were used as the secondary aptamer bioconjugates (Au/hemin@MOF-TBA II-GOD bioconjugates), and TB was sandwiched between Au/hemin@MOF-TBA II-GOD bioconjugates and the amino-terminated TBA I which was self-assembled on the gold nanoparticle (AuNP) modified electrode. The GOD could oxidize glucose into gluconic acid accompanied by the generation of H2O2. The generated H2O2 on the electrode surface was further electrocatalyzed by hemin@MOFs to amplify the electrochemical signal of hemin contained in hemin@MOFs. Therefore, the synthesized hemin@MOFs represented a new paradigm for multifunctional materials since it combined three different functions including serving as catalysts, redox mediators and loading platforms within a single material. With such an ingenious design, a wide linear range of 0.0001 nM to 30 nM was acquired with a relatively low detection limit of 0.068 pM for TB detection.

GHSR-D2R heteromerization modulates dopamine signaling through an effect on G protein conformation.

PubMed

Damian, Marjorie; Pons, Véronique; Renault, Pedro; M'Kadmi, Céline; Delort, Bartholomé; Hartmann, Lucie; Kaya, Ali I; Louet, Maxime; Gagne, Didier; Ben Haj Salah, Khoubaib; Denoyelle, Séverine; Ferry, Gilles; Boutin, Jean A; Wagner, Renaud; Fehrentz, Jean-Alain; Martinez, Jean; Marie, Jacky; Floquet, Nicolas; Galès, Céline; Mary, Sophie; Hamm, Heidi E; Banères, Jean-Louis

2018-04-24

The growth hormone secretagogue receptor (GHSR) and dopamine receptor (D2R) have been shown to oligomerize in hypothalamic neurons with a significant effect on dopamine signaling, but the molecular processes underlying this effect are still obscure. We used here the purified GHSR and D2R to establish that these two receptors assemble in a lipid environment as a tetrameric complex composed of two each of the receptors. This complex further recruits G proteins to give rise to an assembly with only two G protein trimers bound to a receptor tetramer. We further demonstrate that receptor heteromerization directly impacts on dopamine-mediated Gi protein activation by modulating the conformation of its α-subunit. Indeed, association to the purified GHSR:D2R heteromer triggers a different active conformation of Gαi that is linked to a higher rate of GTP binding and a faster dissociation from the heteromeric receptor. This is an additional mechanism to expand the repertoire of GPCR signaling modulation that could have implications for the control of dopamine signaling in normal and physiopathological conditions.

Serotonergic mechanisms responsible for levodopa-induced dyskinesias in Parkinson’s disease patients

PubMed Central

Politis, Marios; Wu, Kit; Loane, Clare; Brooks, David J.; Kiferle, Lorenzo; Turkheimer, Federico E.; Bain, Peter; Molloy, Sophie; Piccini, Paola

2014-01-01

Levodopa-induced dyskinesias (LIDs) are the most common and disabling adverse motor effect of therapy in Parkinson’s disease (PD) patients. In this study, we investigated serotonergic mechanisms in LIDs development in PD patients using 11C-DASB PET to evaluate serotonin terminal function and 11C-raclopride PET to evaluate dopamine release. PD patients with LIDs showed relative preservation of serotonergic terminals throughout their disease. Identical levodopa doses induced markedly higher striatal synaptic dopamine concentrations in PD patients with LIDs compared with PD patients with stable responses to levodopa. Oral administration of the serotonin receptor type 1A agonist buspirone prior to levodopa reduced levodopa-evoked striatal synaptic dopamine increases and attenuated LIDs. PD patients with LIDs that exhibited greater decreases in synaptic dopamine after buspirone pretreatment had higher levels of serotonergic terminal functional integrity. Buspirone-associated modulation of dopamine levels was greater in PD patients with mild LIDs compared with those with more severe LIDs. These findings indicate that striatal serotonergic terminals contribute to LIDs pathophysiology via aberrant processing of exogenous levodopa and release of dopamine as false neurotransmitter in the denervated striatum of PD patients with LIDs. Our results also support the development of selective serotonin receptor type 1A agonists for use as antidyskinetic agents in PD. PMID:24531549

Interaction between effects of genes coding for dopamine and glutamate transmission on striatal and parahippocampal function.

PubMed

Pauli, Andreina; Prata, Diana P; Mechelli, Andrea; Picchioni, Marco; Fu, Cynthia H Y; Chaddock, Christopher A; Kane, Fergus; Kalidindi, Sridevi; McDonald, Colm; Kravariti, Eugenia; Toulopoulou, Timothea; Bramon, Elvira; Walshe, Muriel; Ehlert, Natascha; Georgiades, Anna; Murray, Robin; Collier, David A; McGuire, Philip

2013-09-01

The genes for the dopamine transporter (DAT) and the D-Amino acid oxidase activator (DAOA or G72) have been independently implicated in the risk for schizophrenia and in bipolar disorder and/or their related intermediate phenotypes. DAT and G72 respectively modulate central dopamine and glutamate transmission, the two systems most robustly implicated in these disorders. Contemporary studies have demonstrated that elevated dopamine function is associated with glutamatergic dysfunction in psychotic disorders. Using functional magnetic resonance imaging we examined whether there was an interaction between the effects of genes that influence dopamine and glutamate transmission (DAT and G72) on regional brain activation during verbal fluency, which is known to be abnormal in psychosis, in 80 healthy volunteers. Significant interactions between the effects of G72 and DAT polymorphisms on activation were evident in the striatum, parahippocampal gyrus, and supramarginal/angular gyri bilaterally, the right insula, in the right pre-/postcentral and the left posterior cingulate/retrosplenial gyri (P < 0.05, FDR-corrected across the whole brain). This provides evidence that interactions between the dopamine and the glutamate system, thought to be altered in psychosis, have an impact in executive processing which can be modulated by common genetic variation. Copyright © 2012 Wiley Periodicals, Inc., a Wiley company.

Dopamine Depletion Reduces Food-Related Reward Activity Independent of BMI

PubMed Central

Frank, Sabine; Veit, Ralf; Sauer, Helene; Enck, Paul; Friederich, Hans-Christoph; Unholzer, Theresa; Bauer, Ute-Maria; Linder, Katarzyna; Heni, Martin; Fritsche, Andreas; Preissl, Hubert

2016-01-01

Reward sensitivity and possible alterations in the dopaminergic-reward system are associated with obesity. We therefore aimed to investigate the influence of dopamine depletion on food-reward processing. We investigated 34 female subjects in a randomized placebo-controlled, within-subject design (body mass index (BMI)=27.0 kg/m2 ±4.79 SD; age=28 years ±4.97 SD) using an acute phenylalanine/tyrosine depletion drink representing dopamine depletion and a balanced amino acid drink as the control condition. Brain activity was measured with functional magnetic resonance imaging during a ‘wanting' and ‘liking' rating of food items. Eating behavior-related traits and states were assessed on the basis of questionnaires. Dopamine depletion resulted in reduced activation in the striatum and higher activation in the superior frontal gyrus independent of BMI. Brain activity during the wanting task activated a more distributed network than during the liking task. This network included gustatory, memory, visual, reward, and frontal regions. An interaction effect of dopamine depletion and the wanting/liking task was observed in the hippocampus. The interaction with the covariate BMI was significant in motor and control regions but not in the striatum. Our results support the notion of altered brain activity in the reward and prefrontal network with blunted dopaminergic action during food-reward processing. This effect is, however, independent of BMI, which contradicts the reward-deficiency hypothesis. This hints to the hypothesis suggesting a different or more complex mechanism underlying the dopaminergic reward function in obesity. PMID:26450814

The impact of binaural beats on creativity

PubMed Central

Reedijk, Susan A.; Bolders, Anne; Hommel, Bernhard

2013-01-01

Human creativity relies on a multitude of cognitive processes, some of which are influenced by the neurotransmitter dopamine. This suggests that creativity could be enhanced by interventions that either modulate the production or transmission of dopamine directly, or affect dopamine-driven processes. In the current study we hypothesized that creativity can be influenced by means of binaural beats, an auditory illusion that is considered a form of cognitive entrainment that operates through stimulating neuronal phase locking. We aimed to investigate whether binaural beats affect creative performance at all, whether they affect divergent thinking, convergent thinking, or both, and whether possible effects may be mediated by the individual striatal dopamine level. Binaural beats were presented at alpha and gamma frequency. Participants completed a divergent and a convergent thinking task to assess two important functions of creativity, and filled out the Positive And Negative Affect Scale—mood State questionnaire (PANAS-S) and an affect grid to measure current mood. Dopamine levels in the striatum were estimated using spontaneous eye blink rates (EBRs). Results showed that binaural beats, regardless of the presented frequency, can affect divergent but not convergent thinking. Individuals with low EBRs mostly benefitted from alpha binaural beat stimulation, while individuals with high EBRs were unaffected or even impaired by both alpha and gamma binaural beats. This suggests that binaural beats, and possibly other forms of cognitive entrainment, are not suited for a one-size-fits-all approach, and that individual cognitive-control systems need to be taken into account when studying cognitive enhancement methods. PMID:24294202

The impact of binaural beats on creativity.

PubMed

Reedijk, Susan A; Bolders, Anne; Hommel, Bernhard

2013-01-01

Human creativity relies on a multitude of cognitive processes, some of which are influenced by the neurotransmitter dopamine. This suggests that creativity could be enhanced by interventions that either modulate the production or transmission of dopamine directly, or affect dopamine-driven processes. In the current study we hypothesized that creativity can be influenced by means of binaural beats, an auditory illusion that is considered a form of cognitive entrainment that operates through stimulating neuronal phase locking. We aimed to investigate whether binaural beats affect creative performance at all, whether they affect divergent thinking, convergent thinking, or both, and whether possible effects may be mediated by the individual striatal dopamine level. Binaural beats were presented at alpha and gamma frequency. Participants completed a divergent and a convergent thinking task to assess two important functions of creativity, and filled out the Positive And Negative Affect Scale-mood State questionnaire (PANAS-S) and an affect grid to measure current mood. Dopamine levels in the striatum were estimated using spontaneous eye blink rates (EBRs). Results showed that binaural beats, regardless of the presented frequency, can affect divergent but not convergent thinking. Individuals with low EBRs mostly benefitted from alpha binaural beat stimulation, while individuals with high EBRs were unaffected or even impaired by both alpha and gamma binaural beats. This suggests that binaural beats, and possibly other forms of cognitive entrainment, are not suited for a one-size-fits-all approach, and that individual cognitive-control systems need to be taken into account when studying cognitive enhancement methods.

Targeted PEG-based bioconjugates enhance the cellular uptake and transport of a HIV-1 TAT nonapeptide.

PubMed

Ramanathan, S; Qiu, B; Pooyan, S; Zhang, G; Stein, S; Leibowitz, M J; Sinko, P J

2001-12-13

We previously described the enhanced cell uptake and transport of R.I-K(biotin)-Tat9, a large ( approximately 1500 Da) peptidic inhibitor of HIV-1 Tat protein, via SMVT, the intestinal biotin transporter. The aim of the present study was to investigate the feasibility of targeting biotinylated PEG-based conjugates to SMVT in order to enhance cell uptake and transport of Tat9. The 29 kDa peptide-loaded bioconjugate (PEG:(R.I-Cys-K(biotin)-Tat9)8) used in these studies contained eight copies of R.I-K(biotin)-Tat9 appended to PEG by means of a cysteine linkage. The absorptive transport of biotin-PEG-3400 (0.6-100 microM) and the bioconjugate (0.1-30 microM) was studied using Caco-2 cell monolayers. Inhibition of biotin-PEG-3400 by positive controls (biotin, biocytin, and desthiobiotin) was also determined. Uptake of these two compounds was also determined in CHO cells transfected with human SMVT (CHO/hSMVT) and control cells (CHO/pSPORT) over the concentration ranges of 0.05-12.5 microM and 0.003-30 microM, respectively. Nonbiotinylated forms of these two compounds, PEG-3350 and PEG:(R.I-Cys-K-Tat9)8, were used in the control studies. Biotin-PEG-3400 transport was found to be concentration-dependent and saturable in Caco-2 cells (K(m)=6.61 microM) and CHO/hSMVT cells (K(m)=1.26 microM). Transport/uptake was significantly inhibited by positive control substrates of SMVT. PEG:(R.I-Cys-K(biotin)Tat9)8 also showed saturable transport kinetics in Caco-2 cells (K(m)=6.13 microM) and CHO/hSMVT cells (K(m)=8.19 microM). Maximal uptake in molar equivalents of R.I-Cys-K(biotin)Tat9 was 5.7 times greater using the conjugate versus the biotinylated peptide alone. Transport of the nonbiotinylated forms was significantly lower (P<0.001) in all cases. The present results demonstrate that biotin-PEG-3400 and PEG:(R.I-Cys-K(biotin)Tat9)8 interact with human SMVT to enhance the cellular uptake and transport of these larger molecules and that targeted bioconjugates may have potential for enhancing the cellular uptake and transport of small peptide therapeutic agents.

Functional evidence for a direct excitatory projection from the lateral habenula to the ventral tegmental area in the rat

PubMed Central

Shepard, Paul D.

2016-01-01

The lateral habenula, a phylogenetically conserved epithalamic structure, is activated by aversive stimuli and reward omission. Excitatory efferents from the lateral habenula predominately inhibit midbrain dopamine neuronal firing through a disynaptic, feedforward inhibitory mechanism involving the rostromedial tegmental nucleus. However, the lateral habenula also directly targets dopamine neurons within the ventral tegmental area, suggesting that opposing actions may result from increased lateral habenula activity. In the present study, we tested the effect of habenular efferent stimulation on dopamine and nondopamine neurons in the ventral tegmental area of Sprague-Dawley rats using a parasagittal brain slice preparation. Single pulse stimulation of the fasciculus retroflexus excited 48% of dopamine neurons and 51% of nondopamine neurons in the ventral tegmental area of rat pups. These proportions were not altered by excision of the rostromedial tegmental nucleus and were evident in both cortical- and striatal-projecting dopamine neurons. Glutamate receptor antagonists blocked this excitation, and fasciculus retroflexus stimulation elicited evoked excitatory postsynaptic potentials with a nearly constant onset latency, indicative of a monosynaptic, glutamatergic connection. Comparison of responses in rat pups and young adults showed no significant difference in the proportion of neurons excited by fasciculus retroflexus stimulation. Our data indicate that the well-known, indirect inhibitory effect of lateral habenula activation on midbrain dopamine neurons is complemented by a significant, direct excitatory effect. This pathway may contribute to the role of midbrain dopamine neurons in processing aversive stimuli and salience. PMID:27358317

Functional evidence for a direct excitatory projection from the lateral habenula to the ventral tegmental area in the rat.

PubMed

Brown, P Leon; Shepard, Paul D

2016-09-01

The lateral habenula, a phylogenetically conserved epithalamic structure, is activated by aversive stimuli and reward omission. Excitatory efferents from the lateral habenula predominately inhibit midbrain dopamine neuronal firing through a disynaptic, feedforward inhibitory mechanism involving the rostromedial tegmental nucleus. However, the lateral habenula also directly targets dopamine neurons within the ventral tegmental area, suggesting that opposing actions may result from increased lateral habenula activity. In the present study, we tested the effect of habenular efferent stimulation on dopamine and nondopamine neurons in the ventral tegmental area of Sprague-Dawley rats using a parasagittal brain slice preparation. Single pulse stimulation of the fasciculus retroflexus excited 48% of dopamine neurons and 51% of nondopamine neurons in the ventral tegmental area of rat pups. These proportions were not altered by excision of the rostromedial tegmental nucleus and were evident in both cortical- and striatal-projecting dopamine neurons. Glutamate receptor antagonists blocked this excitation, and fasciculus retroflexus stimulation elicited evoked excitatory postsynaptic potentials with a nearly constant onset latency, indicative of a monosynaptic, glutamatergic connection. Comparison of responses in rat pups and young adults showed no significant difference in the proportion of neurons excited by fasciculus retroflexus stimulation. Our data indicate that the well-known, indirect inhibitory effect of lateral habenula activation on midbrain dopamine neurons is complemented by a significant, direct excitatory effect. This pathway may contribute to the role of midbrain dopamine neurons in processing aversive stimuli and salience. Copyright © 2016 the American Physiological Society.

No association between schizophrenia and polymorphisms within the genes for debrisoquine 4-hydroxylase (CYP2D6) and the dopamine transporter (DAT)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daniels, J.; Williams, J.; Asherson, P.

1995-02-27

It has been suggested that the cytochrome P450 mono-oxygenase, debrisoquine 4-hydroxylase, is involved in the catabolism and processing of neurotransmitters subsequent to their reuptake into target cells. It is also thought to be related to the dopamine transporter that acts to take released dopamine back up into presynaptic terminals. The present study used the association approach to test the hypothesis that mutations in the genes for debrisoquine 4-hydroxylase (CYP2D6) and the dopamine transporter (DAT) confer susceptibility to schizophrenia. There were no differences in allele or genotype frequencies between patients and controls in the mutations causing the poor metaboliser phenotype inmore » CYP2D6. In addition there was no association found between schizophrenia and a 48 bp repeat within the 3{prime} untranslated region of DAT. 18 refs., 2 tabs.« less

Visual Attention in Flies-Dopamine in the Mushroom Bodies Mediates the After-Effect of Cueing.

PubMed

Koenig, Sebastian; Wolf, Reinhard; Heisenberg, Martin

2016-01-01

Visual environments may simultaneously comprise stimuli of different significance. Often such stimuli require incompatible responses. Selective visual attention allows an animal to respond exclusively to the stimuli at a certain location in the visual field. In the process of establishing its focus of attention the animal can be influenced by external cues. Here we characterize the behavioral properties and neural mechanism of cueing in the fly Drosophila melanogaster. A cue can be attractive, repulsive or ineffective depending upon (e.g.) its visual properties and location in the visual field. Dopamine signaling in the brain is required to maintain the effect of cueing once the cue has disappeared. Raising or lowering dopamine at the synapse abolishes this after-effect. Specifically, dopamine is necessary and sufficient in the αβ-lobes of the mushroom bodies. Evidence is provided for an involvement of the αβposterior Kenyon cells.

Engineering the bio-nano interface using a multi-functional polymer coating

NASA Astrophysics Data System (ADS)

Wang, Wentao

Interfacing inorganic nanoparticles with biological systems to develop a variety of novel imaging, sensing and diagnostic tools has generated great interest and much activity over the past two decades. However, the effectiveness of this approach hinges on the ability to prepare water dispersible nanoparticles, with compact size and long term colloidal stability in biological environments, and the development of controlled conjugation to various biomolecules. The primary focus of this dissertation is the design and synthesis, characterization and use of a series of new multidentate and multifunctional coordinating polymers as ligands that render various inorganic nanocrystals water soluble, In Chapter 1 we introduce the basic physical properties of quantum dots (QDs), gold nanocrystals and magnetic nanocrystals along with brief description of their syntheses. We then provide an overview of surface functionalization strategies and recent progress in the ligand chemistry, followed by highlights of a few conjugation approaches applied to nanoparticles in biology. We then discuss modulation of the optical and spectroscopic properties of QDs via energy and charge transfer interactions. We conclude by presenting a few related examples on the incorporation of QD-conjugates into sensor design and intracellular imaging. In Chapter 2, we report the design of a series of multifunctional polymers as ligands for surface engineering of QDs and facilitating their use in bioconjugation. First, we introduce a novel PEGylated polymer that combines the synergies of metal-chelation promoted by lipoic acid and imidazole groups, as effective coating for the surface functionalization of QDs; one of the goals was to address the problems associated with thiol oxidation and weak imidazole affinity. Second, to minimize the hydrodynamic radius of the QDs without sacrificing aqueous solubility, a set of polymer ligands appended with zwitterion and imidazole motifs have been synthesized applied for the surface engineering of QDs. Third, modulation of the nanoparticle's interaction with biological systems requires access to an effective conjugation of these materials with bioactive targets in a controlled manner. To fulfill this goal, we have developed several zwitterion-based multifunctional ligands presenting tunable functional groups, including carboxyl, amine, azide and biotin. This has allowed conjugation of the QDs to biomolecules via bio-orthogonal coupling chemistries, including (1) amine-isothiocyanate reaction; (2) biotin-streptavidin self-assembly; (3) copper-free click chemistry. The resulted QD-bioconjugates have been tested in sensor design and for cell imaging. We also find that the efficiency of polyhistidine-mediated metal coordination is not only determined by the ligand lateral extension but also greatly influenced by the nature of metal coordination on the QDs. In Chapter 3, we have applied the various multi-coordinating and multi-reactive polymers, in particular, those presenting lipoic acid and PEG for the functionalization of gold nanoparticles and nanorods. Gold nanocrystals coated with this polymer exhibit excellent long-term colloidal stability over a broad range of conditions, and furthermore prevent the formation of protein corona. This was verified using dynamic light scattering measurements combined with agarose gel electrophoresis. The diffusion properties of polymer-coated nanocrystals were further characterized using dynamic light scattering; this has yielded valuable information on the nature of the interparticle interactions in biological media. In Chapter 4, an additional set of modular ligands were synthesized and applied for the surface modification of iron oxide nanoparticles. These ligands feature several dopamines for tight binding on iron oxide nanoparticle surface, a short PEG for water solubility and reactive groups (amine, carboxyl, azide and thiol) for bioconjugation. Nanoparticles functionalized with these polymers show extended stability in biologically relevant conditions and little to no cytotoxicity. We demonstrate that covalent attachment of dye enables producing luminescent probe for cell imaging. (Abstract shortened by ProQuest.).

Compromised NMDA/Glutamate Receptor Expression in Dopaminergic Neurons Impairs Instrumental Learning, But Not Pavlovian Goal Tracking or Sign Tracking1,2,3

PubMed Central

James, Alex S.; Pennington, Zachary T.; Tran, Phu

2015-01-01

Abstract Two theories regarding the role for dopamine neurons in learning include the concepts that their activity serves as a (1) mechanism that confers incentive salience onto rewards and associated cues and/or (2) contingency teaching signal reflecting reward prediction error. While both theories are provocative, the causal role for dopamine cell activity in either mechanism remains controversial. In this study mice that either fully or partially lacked NMDARs in dopamine neurons exclusively, as well as appropriate controls, were evaluated for reward-related learning; this experimental design allowed for a test of the premise that NMDA/glutamate receptor (NMDAR)-mediated mechanisms in dopamine neurons, including NMDA-dependent regulation of phasic discharge activity of these cells, modulate either the instrumental learning processes or the likelihood of pavlovian cues to become highly motivating incentive stimuli that directly attract behavior. Loss of NMDARs in dopamine neurons did not significantly affect baseline dopamine utilization in the striatum, novelty evoked locomotor behavior, or consumption of a freely available, palatable food solution. On the other hand, animals lacking NMDARs in dopamine cells exhibited a selective reduction in reinforced lever responses that emerged over the course of instrumental learning. Loss of receptor expression did not, however, influence the likelihood of an animal acquiring a pavlovian conditional response associated with attribution of incentive salience to reward-paired cues (sign tracking). These data support the view that reductions in NMDAR signaling in dopamine neurons affect instrumental reward-related learning but do not lend support to hypotheses that suggest that the behavioral significance of this signaling includes incentive salience attribution. PMID:26464985

The dopamine hypothesis of bipolar affective disorder: the state of the art and implications for treatment

PubMed Central

Ashok, A H; Marques, T R; Jauhar, S; Nour, M M; Goodwin, G M; Young, A H; Howes, O D

2017-01-01

Bipolar affective disorder is a common neuropsychiatric disorder. Although its neurobiological underpinnings are incompletely understood, the dopamine hypothesis has been a key theory of the pathophysiology of both manic and depressive phases of the illness for over four decades. The increased use of antidopaminergics in the treatment of this disorder and new in vivo neuroimaging and post-mortem studies makes it timely to review this theory. To do this, we conducted a systematic search for post-mortem, pharmacological, functional magnetic resonance and molecular imaging studies of dopamine function in bipolar disorder. Converging findings from pharmacological and imaging studies support the hypothesis that a state of hyperdopaminergia, specifically elevations in D2/3 receptor availability and a hyperactive reward processing network, underlies mania. In bipolar depression imaging studies show increased dopamine transporter levels, but changes in other aspects of dopaminergic function are inconsistent. Puzzlingly, pharmacological evidence shows that both dopamine agonists and antidopaminergics can improve bipolar depressive symptoms and perhaps actions at other receptors may reconcile these findings. Tentatively, this evidence suggests a model where an elevation in striatal D2/3 receptor availability would lead to increased dopaminergic neurotransmission and mania, whilst increased striatal dopamine transporter (DAT) levels would lead to reduced dopaminergic function and depression. Thus, it can be speculated that a failure of dopamine receptor and transporter homoeostasis might underlie the pathophysiology of this disorder. The limitations of this model include its reliance on pharmacological evidence, as these studies could potentially affect other monoamines, and the scarcity of imaging evidence on dopaminergic function. This model, if confirmed, has implications for developing new treatment strategies such as reducing the dopamine synthesis and/or release in mania and DAT blockade in bipolar depression. PMID:28289283

Glutamate Counteracts Dopamine/PKA Signaling via Dephosphorylation of DARPP-32 Ser-97 and Alteration of Its Cytonuclear Distribution.

PubMed

Nishi, Akinori; Matamales, Miriam; Musante, Veronica; Valjent, Emmanuel; Kuroiwa, Mahomi; Kitahara, Yosuke; Rebholz, Heike; Greengard, Paul; Girault, Jean-Antoine; Nairn, Angus C

2017-01-27

The interaction of glutamate and dopamine in the striatum is heavily dependent on signaling pathways that converge on the regulatory protein DARPP-32. The efficacy of dopamine/D1 receptor/PKA signaling is regulated by DARPP-32 phosphorylated at Thr-34 (the PKA site), a process that inhibits protein phosphatase 1 (PP1) and potentiates PKA action. Activation of dopamine/D1 receptor/PKA signaling also leads to dephosphorylation of DARPP-32 at Ser-97 (the CK2 site), leading to localization of phospho-Thr-34 DARPP-32 in the nucleus where it also inhibits PP1. In this study the role of glutamate in the regulation of DARPP-32 phosphorylation at four major sites was further investigated. Experiments using striatal slices revealed that glutamate decreased the phosphorylation states of DARPP-32 at Ser-97 as well as Thr-34, Thr-75, and Ser-130 by activating NMDA or AMPA receptors in both direct and indirect pathway striatal neurons. The effect of glutamate in decreasing Ser-97 phosphorylation was mediated by activation of PP2A. In vitro phosphatase assays indicated that the PP2A/PR72 heterotrimer complex was likely responsible for glutamate/Ca 2+ -regulated dephosphorylation of DARPP-32 at Ser-97. As a consequence of Ser-97 dephosphorylation, glutamate induced the nuclear localization in cultured striatal neurons of dephospho-Thr-34/dephospho-Ser-97 DARPP-32. It also reduced PKA-dependent DARPP-32 signaling in slices and in vivo Taken together, the results suggest that by inducing dephosphorylation of DARPP-32 at Ser-97 and altering its cytonuclear distribution, glutamate may counteract dopamine/D1 receptor/PKA signaling at multiple cellular levels. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Glutamate Counteracts Dopamine/PKA Signaling via Dephosphorylation of DARPP-32 Ser-97 and Alteration of Its Cytonuclear Distribution*

PubMed Central

Nishi, Akinori; Matamales, Miriam; Musante, Veronica; Valjent, Emmanuel; Kuroiwa, Mahomi; Kitahara, Yosuke; Rebholz, Heike; Greengard, Paul; Girault, Jean-Antoine; Nairn, Angus C.

2017-01-01

The interaction of glutamate and dopamine in the striatum is heavily dependent on signaling pathways that converge on the regulatory protein DARPP-32. The efficacy of dopamine/D1 receptor/PKA signaling is regulated by DARPP-32 phosphorylated at Thr-34 (the PKA site), a process that inhibits protein phosphatase 1 (PP1) and potentiates PKA action. Activation of dopamine/D1 receptor/PKA signaling also leads to dephosphorylation of DARPP-32 at Ser-97 (the CK2 site), leading to localization of phospho-Thr-34 DARPP-32 in the nucleus where it also inhibits PP1. In this study the role of glutamate in the regulation of DARPP-32 phosphorylation at four major sites was further investigated. Experiments using striatal slices revealed that glutamate decreased the phosphorylation states of DARPP-32 at Ser-97 as well as Thr-34, Thr-75, and Ser-130 by activating NMDA or AMPA receptors in both direct and indirect pathway striatal neurons. The effect of glutamate in decreasing Ser-97 phosphorylation was mediated by activation of PP2A. In vitro phosphatase assays indicated that the PP2A/PR72 heterotrimer complex was likely responsible for glutamate/Ca2+-regulated dephosphorylation of DARPP-32 at Ser-97. As a consequence of Ser-97 dephosphorylation, glutamate induced the nuclear localization in cultured striatal neurons of dephospho-Thr-34/dephospho-Ser-97 DARPP-32. It also reduced PKA-dependent DARPP-32 signaling in slices and in vivo. Taken together, the results suggest that by inducing dephosphorylation of DARPP-32 at Ser-97 and altering its cytonuclear distribution, glutamate may counteract dopamine/D1 receptor/PKA signaling at multiple cellular levels. PMID:27998980

Aberrant dopamine D2-like receptor function in a rodent model of schizophrenia.

PubMed

Perez, Stephanie M; Lodge, Daniel J

2012-11-01

Based on the observation that antipsychotic medications display antagonist properties at dopamine D2-like receptors, aberrant dopamine signaling has been proposed to underlie psychosis in patients with schizophrenia. Thus, it is not surprising that considerable research has been devoted to understanding the mechanisms involved in the antipsychotic action of these compounds. It is important to note that the majority of these studies have been performed in "normal" experimental animals. Given that these animals do not possess the aberrant neuronal information processing typically associated with schizophrenia, the aim of the current study was to examine the dopamine D2 receptor system in a rodent model of schizophrenia. Here, we demonstrate that methylazoxymethanol acetate (MAM)-treated rats display an enhanced effect of quinpirole on dopamine neuron activity and an aberrant locomotor response to D2-like receptor activation, suggesting changes in postsynaptic D2-like receptor function. To better understand the mechanisms underlying the enhanced response to D2-like ligands in MAM-treated rats, we examined the expression of D2, D3, and dopamine transporter mRNA in the nucleus accumbens and ventral tegmental area by quantitative reverse transcription-polymerase chain reaction. MAM-treated rats displayed a significant increase in dopamine D3 receptor mRNA expression in the nucleus accumbens with no significant changes in the expression of the D2 receptor. Taken together, these data demonstrate robust alterations in dopamine D2-like receptor function in a rodent model of schizophrenia and provide evidence that preclinical studies examining the mechanisms of antipsychotic drug action should be performed in animal models that mirror aspects of the abnormal neuronal transmission thought to underlie symptoms of schizophrenia.

Increased dopamine receptor expression and anti-depressant response following deep brain stimulation of the medial forebrain bundle.

PubMed

Dandekar, Manoj P; Luse, Dustin; Hoffmann, Carson; Cotton, Patrick; Peery, Travis; Ruiz, Christian; Hussey, Caroline; Giridharan, Vijayasree V; Soares, Jair C; Quevedo, Joao; Fenoy, Albert J

2017-08-01

Among several potential neuroanatomical targets pursued for deep brain stimulation (DBS) for treating those with treatment-resistant depression (TRD), the superolateral-branch of the medial forebrain bundle (MFB) is emerging as a privileged location. We investigated the antidepressant-like phenotypic and chemical changes associated with reward-processing dopaminergic systems in rat brains after MFB-DBS. Male Wistar rats were divided into three groups: sham-operated, DBS-Off, and DBS-On. For DBS, a concentric bipolar electrode was stereotactically implanted into the right MFB. Exploratory activity and depression-like behavior were evaluated using the open-field and forced-swimming test (FST), respectively. MFB-DBS effects on the dopaminergic system were evaluated using immunoblotting for tyrosine hydroxylase (TH), dopamine transporter (DAT), and dopamine receptors (D1-D5), and high-performance liquid chromatography for quantifying dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) in brain homogenates of prefrontal cortex (PFC), hippocampus, amygdala, and nucleus accumbens (NAc). Animals receiving MFB-DBS showed a significant increase in swimming time without alterations in locomotor activity, relative to the DBS-Off (p<0.039) and sham-operated groups (p<0.014), indicating an antidepressant-like response. MFB-DBS led to a striking increase in protein levels of dopamine D2 receptors and DAT in the PFC and hippocampus, respectively. However, we did not observe appreciable differences in the expression of other dopamine receptors, TH, or in the concentrations of dopamine, DOPAC, and HVA in PFC, hippocampus, amygdala, and NAc. This study was not performed on an animal model of TRD. MFB-DBS rescues the depression-like phenotypes and selectively activates expression of dopamine receptors in brain regions distant from the target area of stimulation. Copyright © 2017. Published by Elsevier B.V.

Zn(2+) site engineering at the oligomeric interface of the dopamine transporter.

PubMed

Norgaard-Nielsen, Kristine; Norregaard, Lene; Hastrup, Hanne; Javitch, Jonathan A; Gether, Ulrik

2002-07-31

Increasing evidence suggests that Na(+)/Cl(-)-dependent neurotransmitter transporters exist as homo-oligomeric proteins. However, the functional implication of this oligomerization remains unclear. Here we demonstrate the engineering of a Zn(2+) binding site at the predicted dimeric interface of the dopamine transporter (DAT) corresponding to the external end of transmembrane segment 6. Upon binding to this site, which involves a histidine inserted in position 310 (V310H) and the endogenous Cys306 within the same DAT molecule, Zn(2+) potently inhibits [(3)H]dopamine uptake. These data provide indirect evidence that conformational changes critical for the translocation process may occur at the interface between two transporter molecules in the oligomeric structure.

Protein tetrazinylation via diazonium coupling for covalent and catalyst-free bioconjugation.

PubMed

Zhang, Jie; Men, Yuwen; Lv, Shanshan; Yi, Long; Chen, Jian-Feng

2015-12-21

An efficient and bench-stable reagent was synthesized for direct and covalent introduction of tetrazines onto target protein or virus surfaces, which can be further modified based on tetrazine-ene ligation to achieve fluorescence labelling or PEGylation under mild conditions.

Nucleus Accumbens Dopamine D2-Receptor Expressing Neurons Control Behavioral Flexibility in a Place Discrimination Task in the IntelliCage

ERIC Educational Resources Information Center

Macpherson, Tom; Morita, Makiko; Wang, Yanyan; Sasaoka, Toshikuni; Sawa, Akira; Hikida, Takatoshi

2016-01-01

Considerable evidence has demonstrated a critical role for the nucleus accumbens (NAc) in the acquisition and flexibility of behavioral strategies. These processes are guided by the activity of two discrete neuron types, dopamine D1- or D2-receptor expressing medium spiny neurons (D1-/D2-MSNs). Here we used the IntelliCage, an automated…

AMPA/Kainate, NMDA, and Dopamine D1 Receptor Function in the Nucleus Accumbens Core: A Context-Limited Role in the Encoding and Consolidation of Instrumental Memory

ERIC Educational Resources Information Center

Hernandez, Pepe J.; Andrzejewski, Matthew E.; Sadeghian, Kenneth; Panksepp, Jules B.; Kelley, Ann E.

2005-01-01

Neural integration of glutamate- and dopamine-coded signals within the nucleus accumbens (NAc) is a fundamental process governing cellular plasticity underlying reward-related learning. Intra-NAc core blockade of NMDA or D1 receptors in rats impairs instrumental learning (lever-pressing for sugar pellets), but it is not known during which phase of…

Single or combined treatment with L-DOPA and quinpirole differentially modulate expression and phosphorylation of key regulatory kinases in neuroblastoma cells.

PubMed

Fuzzati-Armentero, Marie Therese; Ghezzi, Cristina; Nisticò, Robert; Oda, Adriano; Blandini, Fabio

2013-09-27

In the past decades, the clinical use of dopamine agonists has expanded from adjunct therapy in patients with a deteriorating response to L-3,4-dihydroxyphenylalanine (L-DOPA) to monotherapy for the treatment of early PD. Dopamine agonists provide their antiparkinsonian benefit through stimulation of brain postsynaptic type 2 dopamine receptors that exert their effect through classical cAMP-dependent mechanisms, as well as cAMP-independent cellular signaling cascades, including the Akt/glycogen synthase kinase 3 (GSK3) pathway. Alterations of Akt/GSK3 have been observed and may contribute to the neurodegenerative processes and the development of L-DOPA-induced dyskinesia. The effects L-DOPA and quinpirole, a dopamine agonist, on the two key regulatory kinases, Akt and GSK3, were evaluated in neuroblastoma cell line. L-DOPA and dopamine agonist dose-dependently and differentially modulated Akt and GSK3 expression and phosphorylation when added alone or combined. The combined treatment inverted or potentiated the modulatory properties of the single compound. The drug- and concentration-dependent balance of dopamine receptor stimulation over auto-oxidation may distinctively modulate GSK3 isoforms and Akt. Our results indicate that particular attention must be given to drug concentration and combination when multiple therapies are applied for the clinical treatment of PD patients. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Apoptotic natural cell death in developing primate dopamine midbrain neurons occurs during a restricted period in the second trimester of gestation

PubMed Central

Morrow, Bret A.; Roth, Robert H.; Redmond, D. Eugene; Sladek, John R.; Elsworth, John D.

2012-01-01

Natural cell death (NCD) by apoptosis is a normal developmental event in most neuronal populations, and is a determinant of the eventual size of a population. We decided to examine the timing and extent of NCD of the midbrain dopamine system in a primate species, as dopamine deficiency or excess has been implicated in several disorders. Genetic or environmental differences may alter the extent of NCD and predispose individuals to neurological or psychiatric diseases. In developing rats, NCD in the midbrain dopamine system has been observed to start at the end of gestation and peak in the postnatal period. In fetal monkey brains, apoptosis in midbrain DA neurons was identified histologically by chromatin clumping in tyrosine hydroxylase-positive cells, and confirmed by TUNEL and active caspase-3 staining. A distinct peak of NCD occurred at about E80, midway through gestation in this species. We estimate that at least 50% of the population may be lost in this process. In other brains we determined biochemically that the onset of apoptosis coincides with the time of greatest rate of increase of striatal DA concentration. Thus, marked apoptotic NCD occurs in the primate midbrain dopamine system half-way through gestation, and appears to be associated with the rapid developmental increase in striatal dopamine innervation. PMID:17313945

Regulation of dopamine D1 receptor dynamics within the postsynaptic density of hippocampal glutamate synapses.

PubMed

Ladepeche, Laurent; Yang, Luting; Bouchet, Delphine; Groc, Laurent

2013-01-01

Dopamine receptor potently modulates glutamate signalling, synaptic plasticity and neuronal network adaptations in various pathophysiological processes. Although key intracellular signalling cascades have been identified, the cellular mechanism by which dopamine and glutamate receptor-mediated signalling interplay at glutamate synapse remain poorly understood. Among the cellular mechanisms proposed to aggregate D1R in glutamate synapses, the direct interaction between D1R and the scaffold protein PSD95 or the direct interaction with the glutamate NMDA receptor (NMDAR) have been proposed. To tackle this question we here used high-resolution single nanoparticle imaging since it provides a powerful way to investigate at the sub-micron resolution the dynamic interaction between these partners in live synapses. We demonstrate in hippocampal neuronal networks that dopamine D1 receptors (D1R) laterally diffuse within glutamate synapses, in which their diffusion is reduced. Disrupting the interaction between D1R and PSD95, through genetical manipulation and competing peptide, did not affect D1R dynamics in glutamatergic synapses. However, preventing the physical interaction between D1R and the GluN1 subunit of NMDAR abolished the synaptic stabilization of diffusing D1R. Together, these data provide direct evidence that the interaction between D1R and NMDAR in synapses participate in the building of the dopamine-receptor-mediated signalling, and most likely to the glutamate-dopamine cross-talk.

Brain dopamine and kinematics of graphomotor functions.

PubMed

Lange, Klaus W; Mecklinger, Lara; Walitza, Susanne; Becker, Georg; Gerlach, Manfred; Naumann, Markus; Tucha, Oliver

2006-10-01

Three experiments were performed in an attempt to achieve a better understanding of the effect of dopamine on handwriting. In the first experiment, kinematic aspects of handwriting movements were compared between healthy participants and patients with Parkinson's disease (PD) on their usual dopaminergic treatment and following withdrawal of dopaminergic medication. In the second experiment, the writing performance of healthy participants with a hyperechogenicity of the substantia nigra as detected by transcranial sonography (TCS) was compared with the performance of healthy participants with low echogenicity of the substantia nigra. The third experiment examined the effect of central dopamine reduction on kinematic aspects of handwriting movements in healthy adults using acute phenylalanine and tyrosine depletion (APTD). A digitising tablet was used for the assessment of handwriting movements. Participants were asked to perform a simple writing task. Movement time, distance, velocity, acceleration and measures of fluency of handwriting movements were measured. The kinematic analysis of handwriting movements revealed that alterations of central dopaminergic neurotransmission adversely affect movement execution during handwriting. In comparison to the automatic processing of handwriting movements displayed by control participants, participants with an altered dopaminergic neurotransmission shifted from an automatic to a controlled processing of movement execution. Central dopamine appears to be of particular importance with regard to the automatic execution of well-learned movements.

Blocking serotonin but not dopamine reuptake alters neural processing during perceptual decision making.

PubMed

Costa, Vincent D; Kakalios, Laura C; Averbeck, Bruno B

2016-10-01

Dopamine and serotonin have opponent interactions on aspects of impulsivity. Therefore we wanted to test the hypothesis that dopamine and serotonin would have opposing effects on speed-accuracy trade offs in a perceptual decision making task. Unlike other behavioral measures of impulsivity, perceptual decision making allows us to determine whether decreasing premature responses, often interpreted as decreased impulsivity, corresponds to increased behavioral performance. We administered GBR-12909 (a dopamine transporter blocker), escitalopram (a serotonin transporter blocker), or saline in separate sessions to 3 rhesus macaques. We found that animals had slower reaction times (RTs) on escitalopram than on GBR-12909 or saline. However, they were also least accurate on escitalopram. Animals were faster, although nonsignificantly, on GBR than saline and had equivalent accuracy. Administration of GBR-12909 did cause animals to be faster in error trials than correct trials. Therefore, from the point of view of RTs the animals were less impulsive on escitalopram. However, the decreased accuracy of the monkeys shows that they were not able to make use of their slower response times to make more accurate decisions. Therefore, impulsivity was reduced on escitalopram, but at the expense of a slower information-processing rate in the perceptual inference task. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Amphetamine activates Rho GTPase signaling to mediate dopamine transporter internalization and acute behavioral effects of amphetamine

PubMed Central

Wheeler, David S.; Underhill, Suzanne M.; Stolz, Donna B.; Murdoch, Geoffrey H.; Thiels, Edda; Romero, Guillermo; Amara, Susan G.

2015-01-01

Acute amphetamine (AMPH) exposure elevates extracellular dopamine through a variety of mechanisms that include inhibition of dopamine reuptake, depletion of vesicular stores, and facilitation of dopamine efflux across the plasma membrane. Recent work has shown that the DAT substrate AMPH, unlike cocaine and other nontransported blockers, can also stimulate endocytosis of the plasma membrane dopamine transporter (DAT). Here, we show that when AMPH enters the cytoplasm it rapidly stimulates DAT internalization through a dynamin-dependent, clathrin-independent process. This effect, which can be observed in transfected cells, cultured dopamine neurons, and midbrain slices, is mediated by activation of the small GTPase RhoA. Inhibition of RhoA activity with C3 exotoxin or a dominant-negative RhoA blocks AMPH-induced DAT internalization. These actions depend on AMPH entry into the cell and are blocked by the DAT inhibitor cocaine. AMPH also stimulates cAMP accumulation and PKA-dependent inactivation of RhoA, thus providing a mechanism whereby PKA- and RhoA-dependent signaling pathways can interact to regulate the timing and robustness of AMPH’s effects on DAT internalization. Consistent with this model, the activation of D1/D5 receptors that couple to PKA in dopamine neurons antagonizes RhoA activation, DAT internalization, and hyperlocomotion observed in mice after AMPH treatment. These observations support the existence of an unanticipated intracellular target that mediates the effects of AMPH on RhoA and cAMP signaling and suggest new pathways to target to disrupt AMPH action. PMID:26553986

Dopaminergic control of motivation and reinforcement learning: a closed-circuit account for reward-oriented behavior.

PubMed

Morita, Kenji; Morishima, Mieko; Sakai, Katsuyuki; Kawaguchi, Yasuo

2013-05-15

Humans and animals take actions quickly when they expect that the actions lead to reward, reflecting their motivation. Injection of dopamine receptor antagonists into the striatum has been shown to slow such reward-seeking behavior, suggesting that dopamine is involved in the control of motivational processes. Meanwhile, neurophysiological studies have revealed that phasic response of dopamine neurons appears to represent reward prediction error, indicating that dopamine plays central roles in reinforcement learning. However, previous attempts to elucidate the mechanisms of these dopaminergic controls have not fully explained how the motivational and learning aspects are related and whether they can be understood by the way the activity of dopamine neurons itself is controlled by their upstream circuitries. To address this issue, we constructed a closed-circuit model of the corticobasal ganglia system based on recent findings regarding intracortical and corticostriatal circuit architectures. Simulations show that the model could reproduce the observed distinct motivational effects of D1- and D2-type dopamine receptor antagonists. Simultaneously, our model successfully explains the dopaminergic representation of reward prediction error as observed in behaving animals during learning tasks and could also explain distinct choice biases induced by optogenetic stimulation of the D1 and D2 receptor-expressing striatal neurons. These results indicate that the suggested roles of dopamine in motivational control and reinforcement learning can be understood in a unified manner through a notion that the indirect pathway of the basal ganglia represents the value of states/actions at a previous time point, an empirically driven key assumption of our model.

Rotenone and paraquat perturb dopamine metabolism: a computational analysis of pesticide toxicity

PubMed Central

Qi, Zhen; Miller, Gary W.; Voit, Eberhard O.

2014-01-01

Pesticides, such as rotenone and paraquat, are suspected in the pathogenesis of Parkinson’s disease (PD), whose hallmark is the progressive loss of dopaminergic neurons in the substantia nigra pars compacta. Thus, compounds expected to play a role in the pathogenesis of PD will likely impact the function of dopaminergic neurons. To explore the relationship between pesticide exposure and dopaminergic toxicity, we developed a custom-tailored mathematical model of dopamine metabolism and utilized it to infer potential mechanisms underlying the toxicity of rotenone and paraquat, asking how these pesticides perturb specific processes. We performed two types of analyses, which are conceptually different and complement each other. The first analysis, a purely algebraic reverse engineering approach, analytically and deterministically computes the altered profile of enzyme activities that characterize the effects of a pesticide. The second method consists of large-scale Monte Carlo simulations that statistically reveal possible mechanisms of pesticides. The results from the reverse engineering approach show that rotenone and paraquat exposures lead to distinctly different flux perturbations. Rotenone seems to affect all fluxes associated with dopamine compartmentalization, whereas paraquat exposure perturbs fluxes associated with dopamine and its breakdown metabolites. The statistical results of the Monte-Carlo analysis suggest several specific mechanisms. The findings are interesting, because no a priori assumptions are made regarding specific pesticide actions, and all parameters characterizing the processes in the dopamine model are treated in an unbiased manner. Our results show how approaches from computational systems biology can help identify mechanisms underlying the toxicity of pesticide exposure. PMID:24269752

Dopamine and serotonin: influences on male sexual behavior.

PubMed

Hull, Elaine M; Muschamp, John W; Sato, Satoru

2004-11-15

Steroid hormones regulate sexual behavior primarily by slow, genomically mediated effects. These effects are realized, in part, by enhancing the processing of relevant sensory stimuli, altering the synthesis, release, and/or receptors for neurotransmitters in integrative areas, and increasing the responsiveness of appropriate motor outputs. Dopamine has facilitative effects on sexual motivation, copulatory proficiency, and genital reflexes. Dopamine in the nigrostriatal tract influences motor activity; in the mesolimbic tract it activates numerous motivated behaviors, including copulation; in the medial preoptic area (MPOA) it controls genital reflexes, copulatory patterns, and specifically sexual motivation. Testosterone increases nitric oxide synthase in the MPOA; nitric oxide increases basal and female-stimulated dopamine release, which in turn facilitates copulation and genital reflexes. Serotonin (5-HT) is primarily inhibitory, although stimulation of 5-HT(2C) receptors increases erections and inhibits ejaculation, whereas stimulation of 5-HT(1A) receptors has the opposite effects: facilitation of ejaculation and, in some circumstances, inhibition of erection. 5-HT is released in the anterior lateral hypothalamus at the time of ejaculation. Microinjections of selective serotonin reuptake inhibitors there delay the onset of copulation and delay ejaculation after copulation begins. One means for this inhibition is a decrease in dopamine release in the mesolimbic tract.

The role of dopamine in reward and pleasure behaviour--review of data from preclinical research.

PubMed

Bressan, R A; Crippa, J A

2005-01-01

The purpose of this article is to review some of the basic aspects of the dopaminergic system and its role in reward and pleasure behaviour. We also discuss the association between dopamine and unpleasant symptoms that are commonly found in neuropsychiatric disorders and may also be side-effects of neuroleptic drugs. A computer-based search of the literature, augmented by extensive bibliography-guided article reviews, were used to find basic information on the dopamine and the reward systems, and symptoms such as dysphoria, anhedonia and depression. Central dopaminergic neurotransmission is complex, having multiple actions at each level of the mesocorticolimbic reward pathway. The role of dopamine in the reward process was classically associated with the ability to experience pleasure; recent data suggest a more motivational role. Dysfunction of the dopamine transmission in the reward circuit is associated with symptoms such as anhedonia, apathy and dysphoria found in several neuropsychiatric disorders, including Parkinson's disease, depression, drug addiction, and neuroleptic-induced dysphoria. Viewing the dysfunctions of the reward pathways within a broader spectrum and exploring its complex relations with the dopaminergic transmission may help understand the pathophysiology of these neuropsychiatric disorders and lead to a rational development of novel treatments.

Dopamine dysregulation syndrome: implications for a dopamine hypothesis of bipolar disorder.

PubMed

Berk, M; Dodd, S; Kauer-Sant'anna, M; Malhi, G S; Bourin, M; Kapczinski, F; Norman, T

2007-01-01

Rational therapeutic development in bipolar is hampered by a lack of pathophysiological model. However, there is a wealth of converging data on the role of dopamine in bipolar disorder. This paper therefore examines the possibility of a dopamine hypothesis for bipolar disorder. A literature search was conducted using standard search engines Embase, PyschLIT, PubMed and MEDLINE. In addition, papers and book chapters known to the authors were retrieved and examined for further relevant articles. Collectively, in excess of 100 articles were reviewed from which approximately 75% were relevant to the focus of this paper. Pharmacological models suggest a role of increased dopaminergic drive in mania and the converse in depression. In Parkinson's disease, administration of high-dose dopamine precursors can produce a 'maniform' picture, which switches into a depressive analogue on withdrawal. It is possible that in bipolar disorder there is a cyclical process, where increased dopaminergic transmission in mania leads to a secondary down regulation of dopaminergic receptor sensitivity over time. This may lead to a period of decreased dopaminergic transmission, corresponding with the depressive phase, and the repetition of the cycle. This model, if verified, may have implications for rational drug development.

Functionalized TiO2 nanoparticles labelled with 225Ac for targeted alpha radionuclide therapy.

PubMed

Cędrowska, Edyta; Pruszynski, Marek; Majkowska-Pilip, Agnieszka; Męczyńska-Wielgosz, Sylwia; Bruchertseifer, Frank; Morgenstern, Alfred; Bilewicz, Aleksander

2018-01-01

The 225 Ac radioisotope exhibits very attractive nuclear properties for application in radionuclide therapy. Unfortunately, the major challenge for radioconjugates labelled with 225 Ac is that traditional chelating moieties are unable to sequester the radioactive daughters in the bioconjugate which is critical to minimize toxicity to healthy, non-targeted tissues. In the present work, we propose to apply TiO 2 nanoparticles (NPs) as carrier for 225 Ac and its decay products. The surface of TiO 2 nanoparticles with 25 nm diameter was modified with Substance P (5-11), a peptide fragment which targets NK1 receptors on the glioma cells, through the silan-PEG-NHS linker. Nanoparticles functionalized with Substance P (5-11) were synthesized with high yield in a two-step procedure, and the products were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and thermogravimetric analysis (TGA). The obtained results show that one TiO 2 -bioconjugate nanoparticle contains in average 80 peptide molecules on its surface. The synthesized TiO 2 -PEG-SP(5-11) conjugates were labelled with 225 Ac by ion-exchange reaction on hydroxyl (OH) functional groups on the TiO 2 surface. The labelled bioconjugates almost quantitatively retain 225 Ac in phosphate-buffered saline (PBS), physiological salt and cerebrospinal fluid (CSF) for up to 10 days. The leaching of 221 Fr, a first decay daughter of 225 Ac, in an amount of 30% was observed only in CSF after 10 days. The synthesized 225 Ac-TiO 2 -PEG-SP(5-11) has shown high cytotoxic effect in vitro in T98G glioma cells; therefore, it is a promising new radioconjugate for targeted radionuclide therapy of brain tumours.

Functionalized TiO2 nanoparticles labelled with 225Ac for targeted alpha radionuclide therapy

NASA Astrophysics Data System (ADS)

Cędrowska, Edyta; Pruszynski, Marek; Majkowska-Pilip, Agnieszka; Męczyńska-Wielgosz, Sylwia; Bruchertseifer, Frank; Morgenstern, Alfred; Bilewicz, Aleksander

2018-03-01

The 225Ac radioisotope exhibits very attractive nuclear properties for application in radionuclide therapy. Unfortunately, the major challenge for radioconjugates labelled with 225Ac is that traditional chelating moieties are unable to sequester the radioactive daughters in the bioconjugate which is critical to minimize toxicity to healthy, non-targeted tissues. In the present work, we propose to apply TiO2 nanoparticles (NPs) as carrier for 225Ac and its decay products. The surface of TiO2 nanoparticles with 25 nm diameter was modified with Substance P (5-11), a peptide fragment which targets NK1 receptors on the glioma cells, through the silan-PEG-NHS linker. Nanoparticles functionalized with Substance P (5-11) were synthesized with high yield in a two-step procedure, and the products were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and thermogravimetric analysis (TGA). The obtained results show that one TiO2-bioconjugate nanoparticle contains in average 80 peptide molecules on its surface. The synthesized TiO2-PEG-SP(5-11) conjugates were labelled with 225Ac by ion-exchange reaction on hydroxyl (OH) functional groups on the TiO2 surface. The labelled bioconjugates almost quantitatively retain 225Ac in phosphate-buffered saline (PBS), physiological salt and cerebrospinal fluid (CSF) for up to 10 days. The leaching of 221Fr, a first decay daughter of 225Ac, in an amount of 30% was observed only in CSF after 10 days. The synthesized 225Ac-TiO2-PEG-SP(5-11) has shown high cytotoxic effect in vitro in T98G glioma cells; therefore, it is a promising new radioconjugate for targeted radionuclide therapy of brain tumours.

Surface bioengineering of diatomite based nanovectors for efficient intracellular uptake and drug delivery.

PubMed

Terracciano, Monica; Shahbazi, Mohammad-Ali; Correia, Alexandra; Rea, Ilaria; Lamberti, Annalisa; De Stefano, Luca; Santos, Hélder A

2015-12-21

Diatomite is a natural porous silica material of sedimentary origin. Due to its peculiar properties, it can be considered as a valid surrogate of synthetic porous silica for nano-based drug delivery. In this work, we exploit the potential of diatomite nanoparticles (DNPs) for drug delivery with the aim of developing a successful dual-biofunctionalization method by polyethylene glycol (PEG) coverage and cell-penetrating peptide (CPP) bioconjugation, to improve the physicochemical and biological properties of the particles, to enhance the intracellular uptake in cancer cells, and to increase the biocompatibility of 3-aminopropyltriethoxysilane (APT) modified-DNPs. DNPs-APT-PEG-CPP showed hemocompatibility for up to 200 μg mL(-1) after 48 h of incubation with erythrocytes, with a hemolysis value of only 1.3%. The cytotoxicity of the modified-DNPs with a concentration up to 200 μg mL(-1) and incubation with MCF-7 and MDA-MB-231 breast cancer cells for 24 h, demonstrated that PEGylation and CPP-bioconjugation can strongly reduce the cytotoxicity of DNPs-APT. The cellular uptake of the modified-DNPs was also evaluated using the above mentioned cancer cell lines, showing that the CPP-bioconjugation can considerably increase the DNP cellular uptake. Moreover, the dual surface modification of DNPs improved both the loading of a poorly water-soluble anticancer drug, sorafenib, with a loading degree up to 22 wt%, and also enhanced the drug release profiles in aqueous solutions. Overall, this work demonstrates that the biofunctionalization of DNPs is a promising platform for drug delivery applications in cancer therapy as a result of its enhanced stability, biocompatibility, cellular uptake, and drug release profiles.

Growing Applications of “Click Chemistry” for Bioconjugation in Contemporary Biomedical Research

PubMed Central

Nwe, Kido

2009-01-01

Summation This update summarizes the growing application of “click” chemistry in diverse areas such as bioconjugation, drug discovery, materials science, and radiochemistry. This update also discusses click chemistry reactions that proceed rapidly with high selectivity, specificity, and yield. Two important characteristics make click chemistry so attractive for assembling compounds, reagents, and biomolecules for preclinical and clinical applications. First, click reactions are bio-orthogonal; neither the reactants nor their product's functional groups interact with functionalized biomolecules. Second, the reactions proceed with ease under mild nontoxic conditions, such as at room temperature and, usually, in water. The copper-catalyzed Huisgen cycloaddition, azide-alkyne [3 + 2] dipolar cycloaddition, Staudinger ligation, and azide-phosphine ligation each possess these unique qualities. These reactions can be used to modify one cellular component while leaving others unharmed or untouched. Click chemistry has found increasing applications in all aspects of drug discovery in medicinal chemistry, such as for generating lead compounds through combinatorial methods. Bioconjugation via click chemistry is rigorously employed in proteomics and nucleic research. In radiochemistry, selective radiolabeling of biomolecules in cells and living organisms for imaging and therapy has been realized by this technology. Bifunctional chelating agents for several radionuclides useful for positron emission tomography and single-photon emission computed tomography imaging have also been prepared by using click chemistry. This review concludes that click chemistry is not the perfect conjugation and assembly technology for all applications, but provides a powerful, attractive alternative to conventional chemistry. This chemistry has proven itself to be superior in satisfying many criteria (e.g., biocompatibility, selectivity, yield, stereospecificity, and so forth); thus, one can expect it will consequently become a more routine strategy in the near future for a wide range of applications. PMID:19538051

Surface Functionalization Methods to Enhance Bioconjugation in Metal-Labeled Polystyrene Particles

PubMed Central

Abdelrahman, Ahmed I.; Thickett, Stuart C.; Liang, Yi; Ornatsky, Olga; Baranov, Vladimir; Winnik, Mitchell A.

2011-01-01

Lanthanide-encoded polystyrene particles synthesized by dispersion polymerization are excellent candidates for mass cytometry based immunoassays, however they have previously lacked the ability to conjugate biomolecules to the particle surface. We present here three approaches to post-functionalize these particles, enabling the covalent attachment of proteins. Our first approach used partially hydrolyzed poly(N-vinylpyrrolidone) as a dispersion polymerization stabilizer to synthesize particles with high concentration of -COOH groups on the particle surface. In an alternative strategy to provide -COOH functionality to the lanthanide-encoded particles, we employed seeded emulsion polymerization to graft poly(methacrylic acid) (PMAA) chains onto the surface of these particles. However, these two approaches gave little to no improvement in the extent of bioconjugation. In our third approach, seeded emulsion polymerization was subsequently used as a method to grow a functional polymer shell (in this case, poly(glycidyl methacrylate) (PGMA)) onto the surface of these particles, which proved highly successful. The epoxide-rich PGMA shell permitted extensive surface bioconjugation of NeutrAvidin, as probed by an Lu-labeled biotin reporter (ca. 7 × 105 binding events per particle with a very low amount of non-specific binding) and analyzed by mass cytometry. It was shown that coupling agents such as EDC were not needed, such was the reactivity of the particle surface. These particles were stable and the addition of a polymeric shell was shown did not affect the narrow lanthanide ion distribution within the particle interior as analyzed by mass cytometry. These particles represent the most promising candidates for the development of a highly multiplexed bioassay based on lanthanide-labeled particles to date. PMID:21799543

In vivo production of a novel glycoconjugate vaccine against Shigella flexneri 2a in recombinant Escherichia coli: identification of stimulating factors for in vivo glycosylation.

PubMed

Kämpf, Michael M; Braun, Martin; Sirena, Dominique; Ihssen, Julian; Thöny-Meyer, Linda; Ren, Qun

2015-01-23

Glycoconjugated vaccines composed of polysaccharide antigens covalently linked to immunogenic carrier proteins have proved to belong to the most effective and safest vaccines for combating bacterial pathogens. The functional transfer of the N-glycosylation machinery from Campylobacter jejuni to the standard prokaryotic host Escherichia coli established a novel bioconjugation methodology termed bacterial glycoengineering. In this study, we report on the production of a new recombinant glycoconjugate vaccine against Shigella flexneri 2a representing the major serotype for global outbreaks of shigellosis. We demonstrate that S. flexneri 2a O-polysaccharides can be transferred to a detoxified variant of Pseudomonas aeruginosa carrier protein exotoxin A (EPA) by the C. jejuni oligosaccharyltransferase PglB, resulting in glycosylated EPA-2a. Moreover, we optimized the in vivo production of this novel vaccine by identification and quantitative analysis of critical process parameters for glycoprotein synthesis. It was found that sequential induction of oligosaccharyltransferase PglB and carrier protein EPA increased the specific productivity of EPA-2a by a factor of 1.6. Furthermore, by the addition of 10 g/L of the monosaccharide N-acetylglucosamine during induction, glycoconjugate vaccine yield was boosted up to 3.1-fold. The optimum concentration of Mg2+ ions for N-glycan transfer was determined to be 10 mM. Finally, optimized parameters were transferred to high cell density cultures with a 46-fold increase of overall yield of glycoconjugate compared to the one in initial shake flask production. The present study is the first attempt to identify stimulating parameters for improved productivity of S. flexneri 2a bioconjugates. Optimization of glycosylation efficiency will ultimately foster the transfer of lab-scale expression to a cost-effective in vivo production process for a glycoconjugate vaccine against S. flexneri 2a in E. coli. This study is an important step towards this goal and provides a starting point for further optimization studies.

A three-step model for protein-gold nanoparticle adsorption

USDA-ARS?s Scientific Manuscript database

Gold nanoparticles (AuNPs) are an attractive delivery vector in biomedicine because of their low toxicity and unique electronic and chemical properties. AuNP bioconjugates can be used in many applications, including nanomaterials, biosensing, and drug delivery. While the phenomenon of spontaneous pr...

Fluorescent nanocolloids for differential labeling of the endocytic pathway and drug delivery applications

NASA Astrophysics Data System (ADS)

Delehanty, James B.; Spillmann, Christopher M.; Naciri, Jawad; Algar, W. Russ; Ratna, Banahalli R.; Medintz, Igor L.

2013-02-01

The demonstration of fine control over nanomaterials within biological systems, particularly in live cells, is integral for the successful implementation of nanoparticles (NPs) in biomedical applications. Here, we show the ability to differentially label the endocytic pathway of mammalian cells in a spatiotemporal manner utilizing fluorescent nanocolloids (NCs) doped with a perylene-based dye. EDC-based conjugation of green- and red-emitting NCs to the iron transport protein transferrin resulted in stable bioconjugates that were efficiently endocytosed by HEK 293T/17 cells. The staggered delivery of the bioconjugates allowed for the time-resolved, differential labeling of distinct vesicular compartments along the endocytic pathway in a nontoxic manner. We further demonstrated the ability of the NCs to be impregnated with the anticancer therapeutic, doxorubicin. Delivery of the drug-doped nanoconjugates resulted in the intracellular release and nuclear accumulation of doxorubicin in a time- and dose-dependent manner. We discuss our results in the context of the utility of such materials for NP-mediated drug delivery applications.

Rapid Chemoselective Bioconjugation Through the Oxidative Coupling of Anilines and Aminophenols

PubMed Central

Behrens, Christopher R.; Hooker, Jacob M.; Obermeyer, Allie C.; Romanini, Dante W.; Katz, Elan M.; Francis, Matthew B.

2012-01-01

A highly efficient protein bioconjugation method is described involving the addition of anilines to o-aminophenols in the presence of sodium periodate. The reaction takes place in aqueous buffer at pH 6.5 and can reach high levels of completion in 2–5 min. The product of the reaction has been characterized using X-ray crystallography, which revealed that an unprecedented oxidative ring contraction occurs after the coupling step. The compatibility of the reaction with protein substrates has been demonstrated through the attachment of small molecules, polymer chains, and peptides to p-aminophenylalanine residues introduced into viral capsids through amber stop codon suppression. The coupling of anilines to o-aminophenol groups derived from tyrosine residues is also described. The compatibility of this method with thiol modification chemistry is shown through the attachment of a near-IR fluorescent chromophore to cysteine residues inside the viral capsid shells, followed by the attachment of integrin-targeting RGD peptides to anilines on the exterior surface. PMID:21919497

Enhanced Stability and Bioconjugation of Photo-cross-linked Polystyrene-Shell, Au-Core Nanoparticles

PubMed Central

Chen, Ying; Cho, Juhee; Young, Alexi; Taton, T. Andrew

2008-01-01

Encapsulating Au nanoparticles within a shell of photo-cross-linked block copolymer surfactant dramatically improves the physical and chemical stability of the nanoparticles, particularly when they are applied as bioconjugates. Photo-cross-linkable block copolymer amphiphiles [polystyrene-co-poly(4-vinyl benzophenone)]-block-poly(acrylic acid) [(PS-co-PVBP)-b-PAA] and [poly(styrene)-co-poly(4-vinyl benzophenone)]-block-poly(ethylene oxide) [(PS-co-PVBP)-b-PEO] were assembled around Au nanoparticles ranging from 12 nm to 108 nm in diameter. UV irradiation cross-linked the PVBP groups on the polymer to yield particles that withstood extremes of temperature, ionic strength, and chemical etching. Streptavidin was attached to [PS-co-PVBP]-b-PAA coated particles using the same noncovalent and covalent conjugation protocols used to bind biomolecules to divinylbenzene-crosslinked polystyrene microspheres. We expect that these particles will be useful as plasmonic, highly light-scattering and light-absorbing analogs to fluorescently labeled polystyrene nanospheres. PMID:17530871

In vitro and ex vivo evaluation of biomaterials' distinctive properties as a result of thiolation.

PubMed

Laffleur, Flavia; Wagner, Julian; Mahmood, Arshad

2015-01-01

Polysaccharide hyaluronic acid (HA) was chemically modified with cysteine ethyl ester (CYS). By immobilization of the thiol-bearing ligand on the polymeric backbone the thiolated bioconjugate HA-CYS was obtained. METHODOLOGY & RESULTS: Mucoadhesion, permeation enhancement effect and stability was tested. Furthermore mechanical, physicochemical properties as well as mucoadhesive strength, swelling index and residence time on the mucosa were investigated. The developed thiolated bioconjugate displayed 1.5-fold improved mucoadhesiveness on buccal mucosa as well as an enhanced permeation behavior and 2.5-fold higher polymer stability. The near neutral pH and 2.49±0.49% cytotoxicity over 12-h studies indicated their non-irritability and biocompatible nature with biological tissues. Further, the model drug sulforhodamine 101 was incorporated to determine its drug release profiles, which revealed a 2.8-fold controlled release of HA-CYS in comparison to unmodified HA. Thus, the promising results encourage further investigations and exploitation of this versatile polysaccharide.

Gold coated lanthanide phosphate nanoparticles for targeted alpha generator radiotherapy.

PubMed

McLaughlin, Mark F; Woodward, Jonathan; Boll, Rose A; Wall, Jonathan S; Rondinone, Adam J; Kennel, Stephen J; Mirzadeh, Saed; Robertson, J David

2013-01-01

Targeted radiotherapies maximize cytotoxicty to cancer cells. In vivo α-generator targeted radiotherapies can deliver multiple α particles to a receptor site dramatically amplifying the radiation dose delivered to the target. The major challenge with α-generator radiotherapies is that traditional chelating moieties are unable to sequester the radioactive daughters in the bioconjugate which is critical to minimize toxicity to healthy, non-target tissue. The recoil energy of the (225)Ac daughters following α decay will sever any metal-ligand bond used to form the bioconjugate. This work demonstrates that an engineered multilayered nanoparticle-antibody conjugate can deliver multiple α radiations and contain the decay daughters of (225)Ac while targeting biologically relevant receptors in a female BALB/c mouse model. These multi-shell nanoparticles combine the radiation resistance of lanthanide phosphate to contain (225)Ac and its radioactive decay daughters, the magnetic properties of gadolinium phosphate for easy separation, and established gold chemistry for attachment of targeting moieties.

Synthesis of surface-anchored DNA-polymer bioconjugates using reversible addition-fragmentation chain transfer polymerization.

PubMed

He, Peng; He, Lin

2009-07-13

We report here an approach to grafting DNA-polymer bioconjugates on a planar solid support using reversible addition-fragmentation chain transfer (RAFT) polymerization. In particular, a trithiocarbonate compound as the RAFT chain transfer agent (CTA) is attached to the distal point of a surface-immobilized oligonucleotide. Initiation of RAFT polymerization leads to controlled growth of polymers atop DNA molecules on the surface. Growth kinetics of poly(monomethoxy-capped oligo(ethylene glycol) methacrylate) atop DNA molecules is investigated by monitoring the change of polymer film thickness as a function of reaction time. The reaction conditions, including the polymerization temperature, the initiator concentration, the CTA surface density, and the selection of monomers, are varied to examine their impacts on the grafting efficiency of DNA-polymer conjugates. Comparing to polymer growth atop small molecules, the experimental results suggest that DNA molecules significantly accelerate polymer growth, which is speculated as a result of the presence of highly charged DNA backbones and purine/pyrimidine moieties surrounding the reaction sites.

Recyclable Thermoresponsive Polymer-β-Glucosidase Conjugate with Intact Hydrolysis Activity.

PubMed

Mukherjee, Ishita; Sinha, Sushant K; Datta, Supratim; De, Priyadarsi

2018-06-11

β-Glucosidase (BG) catalyzes the hydrolysis of cellobiose to glucose and is a rate-limiting enzyme in the conversion of lignocellulosic biomass to sugars toward biofuels. Since the cost of enzyme is a major contributor to biofuel economics, we report the bioconjugation of a temperature-responsive polymer with the highly active thermophilic β-glucosidase (B8CYA8) from Halothermothrix orenii toward improving enzyme recyclability. The bioconjugate, with a lower critical solution temperature (LCST) of 33 °C withstands high temperatures up to 70 °C. Though the secondary structure of the enzyme in the conjugate is slightly distorted with a higher percentage of β-sheet like structure, the stability and specific activity of B8CYA8 in the conjugate remains unaltered up to 30 °C and retains more than 70% specific activity of the unmodified enzyme at 70 °C. The conjugate can be reused for β-glucosidic bond cleavage of cellobiose for at least four cycles without any significant loss in specific activity.

Synthetic methodology for asymmetric ferrocene derived bio-conjugate systems via solid phase resin-based methodology.

PubMed

Scarborough, J Hunter; Gonzalez, Paulina; Rodich, Sean; Green, Kayla N

2015-03-12

Early detection is a key to successful treatment of most diseases, and is particularly imperative for the diagnosis and treatment of many types of cancer. The most common techniques utilized are imaging modalities such as Magnetic Resonance Imaging (MRI), Positron Emission Topography (PET), and Computed Topography (CT) and are optimal for understanding the physical structure of the disease but can only be performed once every four to six weeks due to the use of imaging agents and overall cost. With this in mind, the development of "point of care" techniques, such as biosensors, which evaluate the stage of disease and/or efficacy of treatment in the clinician's office and do so in a timely manner, would revolutionize treatment protocols.1 As a means to exploring ferrocene based biosensors for the detection of biologically relevant molecules2, methods were developed to produce ferrocene-biotin bio-conjugates described herein. This report will focus on a biotin-ferrocene-cysteine system that can be immobilized on a gold surface.

Overview of the main methods used to combine proteins with nanosystems: absorption, bioconjugation, and encapsulation

PubMed Central

Di Marco, Mariagrazia; Shamsuddin, Shaharum; Razak, Khairunisak Abdul; Aziz, Azlan Abdul; Devaux, Corinne; Borghi, Elsa; Levy, Laurent; Sadun, Claudia

2010-01-01

The latest development of protein engineering allows the production of proteins having desired properties and large potential markets, but the clinical advances of therapeutical proteins are still limited by their fragility. Nanotechnology could provide optimal vectors able to protect from degradation therapeutical biomolecules such as proteins, enzymes or specific polypeptides. On the other hand, some proteins can be also used as active ligands to help nanoparticles loaded with chemotherapeutic or other drugs to reach particular sites in the body. The aim of this review is to provide an overall picture of the general aspects of the most successful approaches used to combine proteins with nanosystems. This combination is mainly achieved by absorption, bioconjugation and encapsulation. Interactions of nanoparticles with biomolecules and caveats related to protein denaturation are also pointed out. A clear understanding of nanoparticle-protein interactions could make possible the design of precise and versatile hybrid nanosystems. This could further allow control of their pharmacokinetics as well as activity, and safety. PMID:20161986

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

DAT by perceived MC interaction on human prefrontal activity and connectivity during emotion processing.

PubMed

Taurisano, Paolo; Blasi, Giuseppe; Romano, Raffaella; Sambataro, Fabio; Fazio, Leonardo; Gelao, Barbara; Ursini, Gianluca; Lo Bianco, Luciana; Di Giorgio, Annabella; Ferrante, Francesca; Papazacharias, Apostolos; Porcelli, Annamaria; Sinibaldi, Lorenzo; Popolizio, Teresa; Bertolino, Alessandro

2013-12-01

Maternal care (MC) and dopamine modulate brain activity during emotion processing in inferior frontal gyrus (IFG), striatum and amygdala. Reuptake of dopamine from the synapse is performed by the dopamine transporter (DAT), whose abundance is predicted by variation in its gene (DAT 3'VNTR; 10 > 9-repeat alleles). Here, we investigated the interaction between perceived MC and DAT 3'VNTR genotype on brain activity during processing of aversive facial emotional stimuli. Sixty-one healthy subjects were genotyped for DAT 3'VNTR and categorized in low and high MC individuals. They underwent functional magnetic resonance imaging while performing a task requiring gender discrimination of facial stimuli with angry, fearful or neutral expressions. An interaction between facial expression, DAT genotype and MC was found in left IFG, such that low MC and homozygosity for the 10-repeat allele are associated with greater activity during processing of fearful faces. This greater activity was also inversely correlated with a measure of emotion control as scored with the Big Five Questionnaire. Moreover, MC and DAT genotype described a double dissociation on functional connectivity between IFG and amygdala. These findings suggest that perceived early parental bonding may interact with DAT 3'VNTR genotype in modulating brain activity during emotionally relevant inputs.

DAT by perceived MC interaction on human prefrontal activity and connectivity during emotion processing

PubMed Central

Taurisano, Paolo; Blasi, Giuseppe; Romano, Raffaella; Sambataro, Fabio; Fazio, Leonardo; Gelao, Barbara; Ursini, Gianluca; Lo Bianco, Luciana; Di Giorgio, Annabella; Ferrante, Francesca; Papazacharias, Apostolos; Porcelli, Annamaria; Sinibaldi, Lorenzo; Popolizio, Teresa

2013-01-01

Background: Maternal care (MC) and dopamine modulate brain activity during emotion processing in inferior frontal gyrus (IFG), striatum and amygdala. Reuptake of dopamine from the synapse is performed by the dopamine transporter (DAT), whose abundance is predicted by variation in its gene (DAT 3′VNTR; 10 > 9-repeat alleles). Here, we investigated the interaction between perceived MC and DAT 3′VNTR genotype on brain activity during processing of aversive facial emotional stimuli. Methods: Sixty-one healthy subjects were genotyped for DAT 3′VNTR and categorized in low and high MC individuals. They underwent functional magnetic resonance imaging while performing a task requiring gender discrimination of facial stimuli with angry, fearful or neutral expressions. Results: An interaction between facial expression, DAT genotype and MC was found in left IFG, such that low MC and homozygosity for the 10-repeat allele are associated with greater activity during processing of fearful faces. This greater activity was also inversely correlated with a measure of emotion control as scored with the Big Five Questionnaire. Moreover, MC and DAT genotype described a double dissociation on functional connectivity between IFG and amygdala. Conclusion: These findings suggest that perceived early parental bonding may interact with DAT 3′VNTR genotype in modulating brain activity during emotionally relevant inputs. PMID:22842906

Dynamic Connectivity between Brain Networks Supports Working Memory: Relationships to Dopamine Release and Schizophrenia.

PubMed

Cassidy, Clifford M; Van Snellenberg, Jared X; Benavides, Caridad; Slifstein, Mark; Wang, Zhishun; Moore, Holly; Abi-Dargham, Anissa; Horga, Guillermo

2016-04-13

Connectivity between brain networks may adapt flexibly to cognitive demand, a process that could underlie adaptive behaviors and cognitive deficits, such as those observed in neuropsychiatric conditions like schizophrenia. Dopamine signaling is critical for working memory but its influence on internetwork connectivity is relatively unknown. We addressed these questions in healthy humans using functional magnetic resonance imaging (during ann-back working-memory task) and positron emission tomography using the radiotracer [(11)C]FLB457 before and after amphetamine to measure the capacity for dopamine release in extrastriatal brain regions. Brain networks were defined by spatial independent component analysis (ICA) and working-memory-load-dependent connectivity between task-relevant pairs of networks was determined via a modified psychophysiological interaction analysis. For most pairs of task-relevant networks, connectivity significantly changed as a function of working-memory load. Moreover, load-dependent changes in connectivity between left and right frontoparietal networks (Δ connectivity lFPN-rFPN) predicted interindividual differences in task performance more accurately than other fMRI and PET imaging measures. Δ Connectivity lFPN-rFPN was not related to cortical dopamine release capacity. A second study in unmedicated patients with schizophrenia showed no abnormalities in load-dependent connectivity but showed a weaker relationship between Δ connectivity lFPN-rFPN and working memory performance in patients compared with matched healthy individuals. Poor working memory performance in patients was, in contrast, related to deficient cortical dopamine release. Our findings indicate that interactions between brain networks dynamically adapt to fluctuating environmental demands. These dynamic adaptations underlie successful working memory performance in healthy individuals and are not well predicted by amphetamine-induced dopamine release capacity. It is unclear how communication between brain networks responds to changing environmental demands during complex cognitive processes. Also, unknown in regard to these network dynamics is the role of neuromodulators, such as dopamine, and whether their dysregulation could underlie cognitive deficits in neuropsychiatric illness. We found that connectivity between brain networks changes with working-memory load and greater increases predict better working memory performance; however, it was not related to capacity for dopamine release in the cortex. Patients with schizophrenia did show dynamic internetwork connectivity; however, this was more weakly associated with successful performance in patients compared with healthy individuals. Our findings indicate that dynamic interactions between brain networks may support the type of flexible adaptations essential to goal-directed behavior. Copyright © 2016 the authors 0270-6474/16/364378-12$15.00/0.

Dynamic Connectivity between Brain Networks Supports Working Memory: Relationships to Dopamine Release and Schizophrenia

PubMed Central

Van Snellenberg, Jared X.; Benavides, Caridad; Slifstein, Mark; Wang, Zhishun; Moore, Holly; Abi-Dargham, Anissa

2016-01-01

Connectivity between brain networks may adapt flexibly to cognitive demand, a process that could underlie adaptive behaviors and cognitive deficits, such as those observed in neuropsychiatric conditions like schizophrenia. Dopamine signaling is critical for working memory but its influence on internetwork connectivity is relatively unknown. We addressed these questions in healthy humans using functional magnetic resonance imaging (during an n-back working-memory task) and positron emission tomography using the radiotracer [11C]FLB457 before and after amphetamine to measure the capacity for dopamine release in extrastriatal brain regions. Brain networks were defined by spatial independent component analysis (ICA) and working-memory-load-dependent connectivity between task-relevant pairs of networks was determined via a modified psychophysiological interaction analysis. For most pairs of task-relevant networks, connectivity significantly changed as a function of working-memory load. Moreover, load-dependent changes in connectivity between left and right frontoparietal networks (Δ connectivity lFPN-rFPN) predicted interindividual differences in task performance more accurately than other fMRI and PET imaging measures. Δ Connectivity lFPN-rFPN was not related to cortical dopamine release capacity. A second study in unmedicated patients with schizophrenia showed no abnormalities in load-dependent connectivity but showed a weaker relationship between Δ connectivity lFPN-rFPN and working memory performance in patients compared with matched healthy individuals. Poor working memory performance in patients was, in contrast, related to deficient cortical dopamine release. Our findings indicate that interactions between brain networks dynamically adapt to fluctuating environmental demands. These dynamic adaptations underlie successful working memory performance in healthy individuals and are not well predicted by amphetamine-induced dopamine release capacity. SIGNIFICANCE STATEMENT It is unclear how communication between brain networks responds to changing environmental demands during complex cognitive processes. Also, unknown in regard to these network dynamics is the role of neuromodulators, such as dopamine, and whether their dysregulation could underlie cognitive deficits in neuropsychiatric illness. We found that connectivity between brain networks changes with working-memory load and greater increases predict better working memory performance; however, it was not related to capacity for dopamine release in the cortex. Patients with schizophrenia did show dynamic internetwork connectivity; however, this was more weakly associated with successful performance in patients compared with healthy individuals. Our findings indicate that dynamic interactions between brain networks may support the type of flexible adaptations essential to goal-directed behavior. PMID:27076432

Differential involvement of dopamine receptors in conditioned suppression induced by cocaine.

PubMed

Grakalic, Ivana; Panlilio, Leigh V; Thorndike, Eric B; Schindler, Charles W

2007-11-14

Cocaine-paired stimuli can suppress food-reinforced operant behavior in rats, providing an animal model of conditioned drug effects. To study the neuropharmacological basis of this phenomenon, we examined the effects of various dopamine receptor antagonists on the acquisition and expression of cocaine-induced conditioned suppression in rats. Superimposed on an ongoing baseline of food-reinforced operant responding, a stimulus was paired with response-independent cocaine (3.0 mg/kg, i.v.) during each of 8 training sessions. To study acquisition, independent groups of rats were given saline, the dopamine D(1)-like receptor antagonist R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH 23390) (0.001-0.03 mg/kg, i.p.), or the dopamine D(2)-like receptor antagonist eticlopride (0.001-0.03 mg/kg, i.p.) prior to each training session. To study expression, independent groups of rats were trained first, then given saline, SCH 23390, eticlopride, or N-[4-(4-(2-methoxyphenyl)piperazinyl)butyl]-2-naphthamide (BP 897) (a dopamine D(3) partial receptor agonist; 0.1-1.0 mg/kg, i.p.) before test sessions in which the stimulus was presented without cocaine. Pre-treatment with either SCH 23390 or eticlopride during acquisition reduced the direct suppressant effects of cocaine, but conditioning was blocked only in rats that were treated with SCH 23390 during acquisition training. Expression of conditioning was attenuated only by eticlopride. Thus, dopamine at least partially mediates both the acquisition and expression of cocaine-induced conditioned suppression, with activation of dopamine D(1)- and D(2)-like receptors underlying these respective processes.

Low dopamine striatal D2 receptors are associated with prefrontal metabolism in obese subjects: Possible contributing factors

PubMed Central

Volkow, Nora D.; Wang, Gene-Jack; Telang, Frank; Fowler, Joanna S.; Thanos, Panayotis K.; Logan, Jean; Alexoff, David; Ding, Yu-Shin; Wong, Christopher; Ma, Yeming; Pradhan, Kith

2009-01-01

Dopamine's role in inhibitory control is well recognized and its disruption may contribute to behavioral disorders of discontrol such as obesity. However, the mechanism by which impaired dopamine neurotransmission interferes with inhibitory control is poorly understood. We had previously documented a reduction in dopamine D2 receptors in morbidly obese subjects. To assess if the reductions in dopamine D2 receptors were associated with activity in prefrontal brain regions implicated in inhibitory control we assessed the relationship between dopamine D2 receptor availability in striatum with brain glucose metabolism (marker of brain function) in ten morbidly obese subjects (BMI>40 kg/m2) and compared it to that in twelve non-obese controls. PET was used with [11C]raclopride to assess D2 receptors and with [18F] FDG to assess regional brain glucose metabolism. In obese subjects striatal D2 receptor availability was lower than controls and was positively correlated with metabolism in dorsolateral prefrontal, medial orbitofrontal, anterior cingulate gyrus and somatosensory cortices. In controls correlations with prefrontal metabolism were not significant but comparisons with those in obese subjects were not significant, which does not permit to ascribe the associations as unique to obesity. The associations between striatal D2 receptors and prefrontal metabolism in obese subjects suggest that decreases in striatal D2 receptors could contribute to overeating via their modulation of striatal prefrontal pathways, which participate in inhibitory control and salience attribution. The association between striatal D2 receptors and metabolism in somatosensory cortices (regions that process palatability) could underlie one of the mechanisms through which dopamine regulates the reinforcing properties of food. PMID:18598772

HIV-1 TAT protein enhances sensitization to methamphetamine by affecting dopaminergic function.

PubMed

Kesby, James P; Najera, Julia A; Romoli, Benedetto; Fang, Yiding; Basova, Liana; Birmingham, Amanda; Marcondes, Maria Cecilia G; Dulcis, Davide; Semenova, Svetlana

2017-10-01

Methamphetamine abuse is common among humans with immunodeficiency virus (HIV). The HIV-1 regulatory protein TAT induces dysfunction of mesolimbic dopaminergic systems which may result in impaired reward processes and contribute to methamphetamine abuse. These studies investigated the impact of TAT expression on methamphetamine-induced locomotor sensitization, underlying changes in dopamine function and adenosine receptors in mesolimbic brain areas and neuroinflammation (microgliosis). Transgenic mice with doxycycline-induced TAT protein expression in the brain were tested for locomotor activity in response to repeated methamphetamine injections and methamphetamine challenge after a 7-day abstinence period. Dopamine function in the nucleus accumbens (Acb) was determined using high performance liquid chromatography. Expression of dopamine and/or adenosine A receptors (ADORA) in the Acb and caudate putamen (CPu) was assessed using RT-PCR and immunohistochemistry analyses. Microarrays with pathway analyses assessed dopamine and adenosine signaling in the CPu. Activity-dependent neurotransmitter switching of a reserve pool of non-dopaminergic neurons to a dopaminergic phenotype in the ventral tegmental area (VTA) was determined by immunohistochemistry and quantified with stereology. TAT expression enhanced methamphetamine-induced sensitization. TAT expression alone decreased striatal dopamine (D1, D2, D4, D5) and ADORA1A receptor expression, while increasing ADORA2A receptors expression. Moreover, TAT expression combined with methamphetamine exposure was associated with increased adenosine A receptors (ADORA1A) expression and increased recruitment of dopamine neurons in the VTA. TAT expression and methamphetamine exposure induced microglia activation with the largest effect after combined exposure. Our findings suggest that dopamine-adenosine receptor interactions and reserve pool neuronal recruitment may represent potential targets to develop new treatments for methamphetamine abuse in individuals with HIV. Copyright © 2017 Elsevier Inc. All rights reserved.

Dysregulation of D2-Mediated Dopamine Transmission in Monkeys after Chronic Escalating Methamphetamine Exposure

PubMed Central

Groman, S.M.; Lee, B.; Seu, E.; James, A.S.; Feiler, K.; Mandelkern, M.A.; London, E.D.; Jentsch, J.D.

2012-01-01

Compulsive drug-seeking and drug-taking are important substance-abuse behaviors that have been linked to alterations in dopaminergic neurotransmission and to impaired inhibitory control. Evidence supports the notions that abnormal D2 receptor-mediated dopamine transmission and inhibitory control may be heritable risk factors for addictions, and that they also reflect drug-induced neuroadaptations. To provide a mechanistic explanation for the drug-induced emergence of inhibitory-control deficits, this study examined how a chronic, escalating-dose regimen of methamphetamine administration affected dopaminergic neurochemistry and cognition in monkeys. Dopamine D2-like receptor and dopamine transporter (DAT) availability and reversal-learning performance were measured before and after exposure to methamphetamine (or saline), and brain dopamine levels were assayed at the conclusion of the study. Exposure to methamphetamine reduced dopamine D2-like receptor and DAT availability, and produced transient, selective impairments in the reversal of a stimulus-outcome association. Furthermore, individual differences in the change in D2-like receptor availability in the striatum were related to the change in response to positive feedback. These data provide evidence that chronic, escalating-dose methamphetamine administration alters the dopamine system in a manner similar to that observed in methamphetamine-dependent humans. They also implicate alterations in positive-feedback sensitivity associated with D2-like receptor dysfunction as the mechanism by which inhibitory control deficits emerge in stimulant-dependent individuals. Finally, a significant degree of neurochemical and behavioral variation in response to methamphetamine was detected, indicating that individual differences affect the degree to which drugs of abuse alter these processes. Identification of these factors ultimately may assist in the development of individualized treatments for substance dependence. PMID:22539846

Dysregulation of D₂-mediated dopamine transmission in monkeys after chronic escalating methamphetamine exposure.

PubMed

Groman, Stephanie M; Lee, Buyean; Seu, Emanuele; James, Alex S; Feiler, Karen; Mandelkern, Mark A; London, Edythe D; Jentsch, J David

2012-04-25

Compulsive drug-seeking and drug-taking are important substance-abuse behaviors that have been linked to alterations in dopaminergic neurotransmission and to impaired inhibitory control. Evidence supports the notions that abnormal D₂ receptor-mediated dopamine transmission and inhibitory control may be heritable risk factors for addictions, and that they also reflect drug-induced neuroadaptations. To provide a mechanistic explanation for the drug-induced emergence of inhibitory-control deficits, this study examined how a chronic, escalating-dose regimen of methamphetamine administration affected dopaminergic neurochemistry and cognition in monkeys. Dopamine D₂-like receptor and dopamine transporter (DAT) availability and reversal-learning performance were measured before and after exposure to methamphetamine (or saline), and brain dopamine levels were assayed at the conclusion of the study. Exposure to methamphetamine reduced dopamine D₂-like receptor and DAT availability and produced transient, selective impairments in the reversal of a stimulus-outcome association. Furthermore, individual differences in the change in D₂-like receptor availability in the striatum were related to the change in response to positive feedback. These data provide evidence that chronic, escalating-dose methamphetamine administration alters the dopamine system in a manner similar to that observed in methamphetamine-dependent humans. They also implicate alterations in positive-feedback sensitivity associated with D₂-like receptor dysfunction as the mechanism by which inhibitory control deficits emerge in stimulant-dependent individuals. Finally, a significant degree of neurochemical and behavioral variation in response to methamphetamine was detected, indicating that individual differences affect the degree to which drugs of abuse alter these processes. Identification of these factors ultimately may assist in the development of individualized treatments for substance dependence.

Contrasting Roles of Dopamine and Noradrenaline in the Motivational Properties of Social Play Behavior in Rats.

PubMed

Achterberg, E J Marijke; van Kerkhof, Linda W M; Servadio, Michela; van Swieten, Maaike M H; Houwing, Danielle J; Aalderink, Mandy; Driel, Nina V; Trezza, Viviana; Vanderschuren, Louk J M J

2016-02-01

Social play behavior, abundant in the young of most mammalian species, is thought to be important for social and cognitive development. Social play is highly rewarding, and as such, the expression of social play depends on its pleasurable and motivational properties. Since the motivational properties of social play have only sporadically been investigated, we developed a setup in which rats responded for social play under a progressive ratio schedule of reinforcement. Dopaminergic neurotransmission plays a key role in incentive motivational processes, and both dopamine and noradrenaline have been implicated in the modulation of social play behavior. Therefore, we investigated the role of dopamine and noradrenaline in the motivation for social play. Treatment with the psychostimulant drugs methylphenidate and cocaine increased responding for social play, but suppressed its expression during reinforced play periods. The dopamine reuptake inhibitor GBR-12909 increased responding for social play, but did not affect its expression, whereas the noradrenaline reuptake inhibitor atomoxetine decreased responding for social play as well as its expression. The effects of methylphenidate and cocaine on responding for social play, but not their play-suppressant effects, were blocked by pretreatment with the dopamine receptor antagonist α-flupenthixol. In contrast, pretreatment with the α2-adrenoceptor antagonist RX821002 prevented the play-suppressant effect of methylphenidate, but left its effect on responding for social play unaltered. In sum, the present study introduces a novel method to study the incentive motivational properties of social play behavior in rats. Using this paradigm, we demonstrate dissociable roles for dopamine and noradrenaline in social play behavior: dopamine stimulates the motivation for social play, whereas noradrenaline negatively modulates the motivation for social play behavior and its expression.

A calcium-channel homologue required for adaptation to dopamine and serotonin in Caenorhabditis elegans.

PubMed

Schafer, W R; Kenyon, C J

1995-05-04

Processing and storage of information by the nervous system requires the ability to modulate the response of excitable cells to neurotransmitter. A simple process of this type, known as adaptation or desensitization, occurs when prolonged stimulation triggers processes that attenuate the response to neurotransmitter. Here we report that the Caenorhabditis elegans gene unc-2 is required for adaptation to two neurotransmitters, dopamine and serotonin. A loss-of-function mutation in unc-2 resulted in failure to adapt either to paralysis by dopamine or to stimulation of egg laying by serotonin. In addition, unc-2 mutants displayed behaviours similar to those induced by serotonin treatment. We found that unc-2 encodes a homologue of a voltage-sensitive calcium-channel alpha-1 subunit. Expression of unc-2 occurs in two types of neurons implicated in the control of egg laying, a behaviour regulated by serotonin. Unc-2 appears to be required in modulatory neurons to downregulate the response of the egg-laying muscles to serotonin. We propose that adaptation to serotonin occurs through activation of an Unc-2-dependent calcium influx, which modulates the postsynaptic response to serotonin, perhaps by inhibiting the release of a potentiating neuropeptide.

Modeling antigen-antibody nanoparticle bioconjugates and their polymorphs

NASA Astrophysics Data System (ADS)

Desgranges, Caroline; Delhommelle, Jerome

2018-03-01

The integration of nanomaterials with biomolecules has recently led to the development of new ways of designing biosensors, and through their assembly, to new hybrid structures for novel and exciting applications. In this work, we develop a coarse-grained model for nanoparticles grafted with antibody molecules and their binding with antigens. In particular, we isolate two possible states for antigen-antibody pairs during the binding process, termed as recognition and anchoring states. Using molecular simulation, we calculate the thermodynamic and structural features of three possible crystal structures or polymorphs, the body-centered cubic, simple cubic, and face-centered cubic phases, and of the melt. This leads us to determine the domain of stability of the three solid phases. In particular, the role played by the switching process between anchoring and recognition states during melting is identified, shedding light on the complex microscopic mechanisms in these systems.

Aging of the dopaminergic system and motor behavior in mice intoxicated with the parkinsonian toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.

PubMed

Schumm, Sophie; Sebban, Claude; Cohen-Salmon, Charles; Callebert, Jacques; Launay, Jean-Marie; Golmard, Jean-Louis; Boussicault, Lydie; Petropoulos, Isabelle; Hild, Audrey; Rousselet, Estelle; Prigent, Annick; Friguet, Bertrand; Mariani, Jean; Hirsch, Etienne C

2012-09-01

1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication of mice is a standard model of Parkinson's disease (PD). However, it does not reproduce functionally PD. Given the occurrence of PD during aging, symptoms might only be detected in MPTP-intoxicated mice after aging. To address this, mice injected with MPTP at 2.5 months were followed up to a maximum age of 21 months. There was no loss of dopamine cells with aging in control mice; moreover, the initial post-MPTP intoxication decrease in dopamine cell was no longer significant at 21 months. With aging, striatal dopamine level remained constant, but concentrations of the dopamine metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were markedly reduced in both groups. There was also a late impairment of fine motor skills. After MPTP intoxication, hyperactivity was immediately detected and it became greater than in control mice from 14 months of age; fine motor skills were also more impaired; both these symptoms were correlated with striatal dopamine, DOPAC and HVA concentrations. In bothgroups, neither motor symptoms nor dopamine changes worsened with age. These findings do not support the notion that PD develops with age in mice after MPTP intoxication and that the motor deficits seen are because of an aging process. © 2012 The Authors. Journal of Neurochemistry © 2012 International Society for Neurochemistry.

Bioinspired near-infrared-excited sensing platform for in vitro antioxidant capacity assay based on upconversion nanoparticles and a dopamine-melanin hybrid system.

PubMed

Wang, Dong; Chen, Chuan; Ke, Xuebin; Kang, Ning; Shen, Yuqing; Liu, Yongliang; Zhou, Xi; Wang, Hongjun; Chen, Changqing; Ren, Lei

2015-02-11

A novel core-shell structure based on upconversion fluorescent nanoparticles (UCNPs) and dopamine-melanin has been developed for evaluation of the antioxidant capacity of biological fluids. In this approach, dopamine-melanin nanoshells facilely formed on the surface of UCNPs act as ultraefficient quenchers for upconversion fluorescence, contributing to a photoinduced electron-transfer mechanism. This spontaneous oxidative polymerization of the dopamine-induced quenching effect could be effectively prevented by the presence of various antioxidants (typically biothiols, ascorbic acid (Vitamin C), and Trolox). The chemical response of the UCNPs@dopamine-melanin hybrid system exhibited great selectivity and sensitivity toward antioxidants relative to other compounds at 100-fold higher concentration. A satisfactory correlation was established between the ratio of the "anti-quenching" fluorescence intensity and the concentration of antioxidants. Besides the response of the upconversion fluorescence signal, a specific evaluation process for antioxidants could be visualized by the color change from colorless to dark gray accompanied by the spontaneous oxidation of dopamine. The near-infrared (NIR)-excited UCNP-based antioxidant capacity assay platform was further used to evaluate the antioxidant capacity of cell extracts and human plasma, and satisfactory sensitivity, repeatability, and recovery rate were obtained. This approach features easy preparation, fluorescence/visual dual mode detection, high specificity to antioxidants, and enhanced sensitivity with NIR excitation, showing great potential for screening and quantitative evaluation of antioxidants in biological systems.

Role of external and internal calcium on heterocarrier-mediated transmitter release.

PubMed

Fassio, A; Bonanno, G; Fontana, G; Usai, C; Marchi, M; Raiteri, M

1996-04-01

Release-regulating heterocarriers exist on brain nerve endings. We have investigated in this study the mechanisms involved in the neurotransmitter release evoked by GABA heterocarrier activation. GABA increased the basal release of [3H]acetylcholine and [3H]noradrenaline from rat hippocampal synaptosomes and of [3H]dopamine from striatal synaptosomes. These GABA effects, insensitive to GABA receptor antagonists, were prevented by inhibiting GABA uptake but not by blocking noradrenaline, choline, or dopamine transport. Lack of extracellular Ca2+ or addition of tetrodotoxin selectively abolished the GABA-evoked release of [3H]noradrenaline, leaving unaffected that of [3H]acetylcholine or [3H]dopamine. 1,2-Bis(2-aminophenoxyl)-ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM) or vesamicol attenuated the release of [3H]acetylcholine elicited by GABA. Reserpine, but not BAPTA-AM, prevented the effect of GABA on [3H] dopamine release. Autoreceptor activation inhibited the GABA-evoked release of [3H]noradrenaline but not that of [3H]acetylcholine or [3H]dopamine. It is concluded that (a) the release of [3H]noradrenaline consequent to activation of GABA heterocarriers sited on noradrenergic terminals meets the criteria of a conventional exocytotic process, (b) the extracellular [Ca2+]-independent releases of [3H]acetylcholine and [3H]dopamine appear to occur from vesicles possibly through involvement of intraterminal Ca2+, and (c) autoreceptor activation only affects heterocarrier-mediated vesicular release linked to entry of extracellular Ca2+.

Effects of pramipexole on the processing of rewarding and aversive taste stimuli.

PubMed

McCabe, Ciara; Harwood, James; Brouwer, Sietske; Harmer, Catherine J; Cowen, Philip J

2013-07-01

Pramipexole, a D2/D3 dopamine receptor agonist, has been implicated in the development of impulse control disorders in patients with Parkinson's disease. Investigation of single doses of pramipexole in healthy participants in reward-based learning tasks has shown inhibition of the neural processing of reward, presumptively through stimulation of dopamine autoreceptors. This study aims to examine the effects of pramipexole on the neural response to the passive receipt of rewarding and aversive sight and taste stimuli. We used functional magnetic resonance imaging to examine the neural responses to the sight and taste of pleasant (chocolate) and aversive (mouldy strawberry) stimuli in 16 healthy volunteers who received a single dose of pramipexole (0.25 mg) and placebo in a double-blind, within-subject, design. Relative to placebo, pramipexole treatment reduced blood oxygen level-dependent activation to the chocolate stimuli in the areas known to play a key role in reward, including the ventromedial prefrontal cortex, the orbitofrontal cortex, striatum, thalamus and dorsal anterior cingulate cortex. Pramipexole also reduced activation to the aversive condition in the dorsal anterior cingulate cortex. There were no effects of pramipexole on the subjective ratings of the stimuli. Our results are consistent with an ability of acute, low-dose pramipexole to diminish dopamine-mediated responses to both rewarding and aversive taste stimuli, perhaps through an inhibitory action of D2/3 autoreceptors on phasic burst activity of midbrain dopamine neurones. The ability of pramipexole to inhibit aversive processing might potentiate its adverse behavioural effects and could also play a role in its proposed efficacy in treatment-resistant depression.

Dopamine Modulates the Efficiency of Sensory Evidence Accumulation During Perceptual Decision Making.

PubMed

Beste, Christian; Adelhöfer, Nico; Gohil, Krutika; Passow, Susanne; Roessner, Veit; Li, Shu-Chen

2018-04-02

Perceptual decision making is the process through which available sensory information is gathered and processed to guide our choices. However, the neuropsychopharmacological basis of this important cognitive function is largely elusive. Yet, theoretical considerations suggest that the dopaminergic system may play an important role. In a double-blind, randomized, placebo-controlled study design, we examined the effect of methylphenidate in 2 dosages (0.25 mg/kg and 0.5 mg/kg body weight) in separate groups of healthy young adults. We used a moving dots task in which the coherency of the direction of moving dots stimuli was manipulated in 3 levels (5%, 15%, and 35%). Drift diffusion modelling was applied to behavioral data to capture subprocesses of perceptual decision making. The findings show that only the drift rate (v), reflecting the efficiency of sensory evidence accumulation, but not the decision criterion threshold (a) or the duration of nondecisional processes (Ter), is affected by methylphenidate vs placebo administration. Compared with placebo, administering 0.25 mg/kg methylphenidate increased v, but only in the 35% coherence condition. Administering 0.5 mg/kg methylphenidate did not induce modulations. The data suggest that dopamine selectively modulates the efficacy of evidence accumulation during perceptual decision making. This modulation depends on 2 factors: (1) the degree to which the dopaminergic system is modulated using methylphenidate (i.e., methylphenidate dosage) and (2) the signal-to-noise ratio of the visual information. Dopamine affects sensory evidence accumulation only when dopamine concentration is not shifted beyond an optimal level and the incoming information is less noisy.

Dopamine and response selection: an Acute Phenylalanine/Tyrosine Depletion study.

PubMed

Ramdani, Céline; Vidal, Franck; Dagher, Alain; Carbonnell, Laurence; Hasbroucq, Thierry

2018-04-01

The role of dopaminergic system in decision-making is well documented, and evidence suggests that it could play a significant role in response selection processes. The N-40 is a fronto-central event-related potential, generated by the supplementary motor areas (SMAs) and a physiological index of response selection processes. The aim of the present study was to determine whether infraclinical effects of dopamine depletion on response selection processes could be evidenced via alterations of the N-40. We obtained a dopamine depletion in healthy volunteers with the acute phenylalanine and tyrosine depletion (APTD) method which consists in decreasing the availability of dopamine precursors. Subjects realized a Simon task in the APTD condition and in the control condition. When the stimulus was presented on the same side as the required response, the stimulus-response association was congruent and when the stimulus was presented on the opposite side of the required response, the stimulus-response association was incongruent. The N-40 was smaller for congruent associations than for incongruent associations. Moreover, the N-40 was sensitive to the level of dopaminergic activity with a decrease in APTD condition compared to control condition. This modulation of the N-40 by dopaminergic level could not be explained by a global decrease of cerebral electrogenesis, since negativities and positivities indexing the recruitment of the primary motor cortex (anatomically adjacent to the SMA) were unaffected by APTD. The specific sensitivity of N-40 to ATPD supports the model of Keeler et al. (Neuroscience 282:156-175, 2014) according to which the dopaminergic system is involved in response selection.

Dopaminergic circuitry and risk/reward decision making: implications for schizophrenia.

PubMed

Stopper, Colin M; Floresco, Stan B

2015-01-01

Abnormal reinforcement learning and representations of reward value are present in schizophrenia, and these impairments can manifest as deficits in risk/reward decision making. These abnormalities may be due in part to dopaminergic dysfunction within cortico-limbic-striatal circuitry. Evidence from studies with laboratory animal have revealed that normal DA activity within different nodes of these circuits is critical for mediating dissociable processes that can refine decision biases. Moreover, both phasic and tonic dopamine transmission appear to play separate yet complementary roles in these processes. Tonic dopamine release within the prefrontal cortex and nucleus accumbens, serves as a "running rate-meter" of reward and reflects contextual information such as reward uncertainty and overt choice behavior. On the other hand, manipulations of outcome-related phasic dopamine bursts and dips suggest these signals provide rapid feedback to allow for quick adjustments in choice as reward contingencies change. The lateral habenula is a key input to the DA system that phasic signals is necessary for expressing subjective decision biases; as suppression of activity within this nucleus leads to catastrophic impairments in decision making and random patterns of choice behavior. As schizophrenia is characterized by impairments in using positive and negative feedback to appropriately guide decision making, these findings suggest that these deficits in these processes may be mediated, at least in part, by abnormalities in both tonic and phasic dopamine transmission. © The Author 2014. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Carbon nanotube multi-electrode array chips for noninvasive real-time measurement of dopamine, action potentials, and postsynaptic potentials.

PubMed

Suzuki, Ikuro; Fukuda, Mao; Shirakawa, Keiichi; Jiko, Hideyasu; Gotoh, Masao

2013-11-15

Multi-electrode arrays (MEAs) can be used for noninvasive, real-time, and long-term recording of electrophysiological activity and changes in the extracellular chemical microenvironment. Neural network organization, neuronal excitability, synaptic and phenotypic plasticity, and drug responses may be monitored by MEAs, but it is still difficult to measure presynaptic activity, such as neurotransmitter release, from the presynaptic bouton. In this study, we describe the development of planar carbon nanotube (CNT)-MEA chips that can measure both the release of the neurotransmitter dopamine as well as electrophysiological responses such as field postsynaptic potentials (fPSPs) and action potentials (APs). These CNT-MEA chips were fabricated by electroplating the indium-tin oxide (ITO) microelectrode surfaces. The CNT-plated ITO electrode exhibited electrochemical response, having much higher current density compared with the bare ITO electrode. Chronoamperometric measurements using these CNT-MEA chips detected dopamine at nanomolar concentrations. By placing mouse striatal brain slices on the CNT-MEA chip, we successfully measured synaptic dopamine release from spontaneous firings with a high S/N ratio of 62. Furthermore, APs and fPSPs were measured from cultured hippocampal neurons and slices with high temporal resolution and a 100-fold greater S/N ratio. Our CNT-MEA chips made it possible to measure neurotransmitter dopamine (presynaptic activities), postsynaptic potentials, and action potentials, which have a central role in information processing in the neuronal network. CNT-MEA chips could prove useful for in vitro studies of stem cell differentiation, drug screening and toxicity, synaptic plasticity, and pathogenic processes involved in epilepsy, stroke, and neurodegenerative diseases. Copyright © 2013 Elsevier B.V. All rights reserved.

Dopamine receptor blockade attenuates the general incentive motivational effects of noncontingently delivered rewards and reward-paired cues without affecting their ability to bias action selection.

PubMed

Ostlund, Sean B; Maidment, Nigel T

2012-01-01

Environmental cues affect our behavior in a variety of ways. Despite playing an invaluable role in guiding our daily activities, such cues also appear to trigger the harmful, compulsive behaviors that characterize addiction and other disorders of behavioral control. In instrumental conditioning, rewards and reward-paired cues bias action selection and invigorate reward-seeking behaviors, and appear to do so through distinct neurobehavioral processes. Although reward-paired cues are known to invigorate performance through a dopamine-dependent incentive motivational process, it is not known if dopamine also mediates the influence of rewards and reward-paired cues over action selection. The current study contrasted the effects of systemic administration of the nonspecific dopamine receptor antagonist flupentixol on response invigoration and action bias in Pavlovian-instrumental transfer, a test of cue-elicited responding, and in instrumental reinstatement, a test of noncontingent reward-elicited responding. Hungry rats were trained on two different stimulus-outcome relationships (eg, tone-grain pellets and noise-sucrose solution) and two different action-outcome relationships (eg, left press-grain and right press-sucrose). At test, we found that flupentixol pretreatment blocked the response invigoration generated by the cues but spared their ability to bias action selection to favor the action whose outcome was signaled by the cue being presented. The response-biasing influence of noncontingent reward deliveries was also unaffected by flupentixol. Interestingly, although flupentixol had a modest effect on the immediate response invigoration produced by those rewards, it was particularly potent in countering the lingering enhancement of responding produced by multiple reward deliveries. These findings indicate that dopamine mediates the general incentive motivational effects of noncontingent rewards and reward-paired cues but does not support their ability to bias action selection.

Dopamine D1/D5 receptors in the dorsal hippocampus are required for the acquisition and expression of a single trial cocaine-associated memory.

PubMed

Kramar, Cecilia P; Barbano, M Flavia; Medina, Jorge H

2014-12-01

The role of the hippocampus in memory supporting associative learning between contexts and unconditioned stimuli is well documented. Hippocampal dopamine neurotransmission modulates synaptic plasticity and memory processing of fear-motivated and spatial learning tasks. Much less is known about the involvement of the hippocampus and its D1/D5 dopamine receptors in the acquisition, consolidation and expression of memories for drug-associated experiences, more particularly, in the processing of single pairing cocaine conditioned place preference (CPP) training. To determine the temporal dynamics of cocaine CPP memory formation, we trained rats in a one-pairing CPP paradigm and tested them at different time intervals after conditioning. The cocaine-associated memory lasted 24 h but not 72 h. Then, we bilaterally infused the dorsal hippocampus with the GABA A receptor agonist muscimol or the D1/D5 dopamine receptor antagonist SCH 23390 at different stages to evaluate the mechanisms involved in the acquisition, consolidation or expression of cocaine CPP memory. Blockade of D1/D5 dopamine receptors at the moment of training impaired the acquisition of cocaine CPP memories, without having any effect when administered immediately or 12 h after training. The expression of cocaine CPP memory was also affected by the administration of SCH 23390 at the moment of the test. Conversely, muscimol impaired the consolidation of cocaine CPP memory only when administered 12 h post conditioning. These findings suggests that dopaminergic inputs to the dorsal hippocampus are required for the acquisition and expression of one trial cocaine-associated memory while neural activity of this structure is required for the late consolidation of these types of memories. Copyright © 2014 Elsevier Inc. All rights reserved.

Wide-Field Fluorescence Microscopy of Real-Time Bioconjugation Sensing

PubMed Central

Szalkowski, Marcin; Sulowska, Karolina; Grzelak, Justyna; Niedziółka-Jönsson, Joanna; Roźniecka, Ewa

2018-01-01

We apply wide-field fluorescence microscopy to measure real-time attachment of photosynthetic proteins to plasmonically active silver nanowires. The observation of this effect is enabled, on the one hand, by sensitive detection of fluorescence and, on the other hand, by plasmonic enhancement of protein fluorescence. We examined two sample configurations with substrates being a bare glass coverslip and a coverslip functionalized with a monolayer of streptavidin. The different preparation of the substrate changes the observed behavior as far as attachment of the protein is concerned as well as its subsequent photobleaching. For the latter substrate the conjugation process is measurably slower. The described method can be universally applied in studying protein-nanostructure interactions for real-time fluorescence-based sensing. PMID:29351211

Wide-Field Fluorescence Microscopy of Real-Time Bioconjugation Sensing.

PubMed

Szalkowski, Marcin; Sulowska, Karolina; Grzelak, Justyna; Niedziółka-Jönsson, Joanna; Roźniecka, Ewa; Kowalska, Dorota; Maćkowski, Sebastian

2018-01-19

We apply wide-field fluorescence microscopy to measure real-time attachment of photosynthetic proteins to plasmonically active silver nanowires. The observation of this effect is enabled, on the one hand, by sensitive detection of fluorescence and, on the other hand, by plasmonic enhancement of protein fluorescence. We examined two sample configurations with substrates being a bare glass coverslip and a coverslip functionalized with a monolayer of streptavidin. The different preparation of the substrate changes the observed behavior as far as attachment of the protein is concerned as well as its subsequent photobleaching. For the latter substrate the conjugation process is measurably slower. The described method can be universally applied in studying protein-nanostructure interactions for real-time fluorescence-based sensing.

Changes in artistic style and behaviour in Parkinson's disease: dopamine and creativity.

PubMed

Kulisevsky, Jaime; Pagonabarraga, Javier; Martinez-Corral, Mercè

2009-05-01

We present a PD patient in whom dopamine agonists awoke a hidden creativity that led to a gradual increase in painting productivity evolving to a disruptive impulsive behaviour that shared many features with punding. A dramatic change in painting style related to a more emotional experience during the process of creation developed after treatment onset. This case suggests that changes in creativity in PD seem to be related to dopaminergic imbalance in the limbic system.

Changes in Striatal Dopamine Release Associated with Human Motor-Skill Acquisition

PubMed Central

Kawashima, Shoji; Ueki, Yoshino; Kato, Takashi; Matsukawa, Noriyuki; Mima, Tatsuya; Hallett, Mark; Ito, Kengo; Ojika, Kosei

2012-01-01

The acquisition of new motor skills is essential throughout daily life and involves the processes of learning new motor sequence and encoding elementary aspects of new movement. Although previous animal studies have suggested a functional importance for striatal dopamine release in the learning of new motor sequence, its role in encoding elementary aspects of new movement has not yet been investigated. To elucidate this, we investigated changes in striatal dopamine levels during initial skill-training (Day 1) compared with acquired conditions (Day 2) using 11C-raclopride positron-emission tomography. Ten volunteers learned to perform brisk contractions using their non-dominant left thumbs with the aid of visual feedback. On Day 1, the mean acceleration of each session was improved through repeated training sessions until performance neared asymptotic levels, while improved motor performance was retained from the beginning on Day 2. The 11C-raclopride binding potential (BP) in the right putamen was reduced during initial skill-training compared with under acquired conditions. Moreover, voxel-wise analysis revealed that 11C-raclopride BP was particularly reduced in the right antero-dorsal to the lateral part of the putamen. Based on findings from previous fMRI studies that show a gradual shift of activation within the striatum during the initial processing of motor learning, striatal dopamine may play a role in the dynamic cortico-striatal activation during encoding of new motor memory in skill acquisition. PMID:22355391

Hybrid CMOS-Graphene Sensor Array for Subsecond Dopamine Detection.

PubMed

Nasri, Bayan; Wu, Ting; Alharbi, Abdullah; You, Kae-Dyi; Gupta, Mayank; Sebastian, Sunit P; Kiani, Roozbeh; Shahrjerdi, Davood

2017-12-01

We introduce a hybrid CMOS-graphene sensor array for subsecond measurement of dopamine via fast-scan cyclic voltammetry (FSCV). The prototype chip has four independent CMOS readout channels, fabricated in a 65-nm process. Using planar multilayer graphene as biologically compatible sensing material enables integration of miniaturized sensing electrodes directly above the readout channels. Taking advantage of the chemical specificity of FSCV, we introduce a region of interest technique, which subtracts a large portion of the background current using a programmable low-noise constant current at about the redox potentials. We demonstrate the utility of this feature for enhancing the sensitivity by measuring the sensor response to a known dopamine concentration in vitro at three different scan rates. This strategy further allows us to significantly reduce the dynamic range requirements of the analog-to-digital converter (ADC) without compromising the measurement accuracy. We show that an integrating dual-slope ADC is adequate for digitizing the background-subtracted current. The ADC operates at a sampling frequency of 5-10 kHz and has an effective resolution of about 60 pA, which corresponds to a theoretical dopamine detection limit of about 6 nM. Our hybrid sensing platform offers an effective solution for implementing next-generation FSCV devices that can enable precise recording of dopamine signaling in vivo on a large scale.

The dopamine D2 receptor antagonist sulpiride modulates striatal BOLD signal during the manipulation of information in working memory.

PubMed

Dodds, Chris M; Clark, Luke; Dove, Anja; Regenthal, Ralf; Baumann, Frank; Bullmore, Ed; Robbins, Trevor W; Müller, Ulrich

2009-11-01

Dopamine (DA) plays an important role in working memory. However, the precise functions supported by different DA receptor subtypes in different neural regions remain unclear. The present study used pharmacological, event-related fMRI to test the hypothesis that striatal dopamine is important for the manipulation of information in working memory. Twenty healthy human subjects were scanned twice, once after placebo and once after sulpiride 400 mg, a selective DA D2 receptor antagonist, while performing a verbal working memory task requiring different levels of manipulation. Whilst there was no overall effect of sulpiride on task-dependent activation, individual variation in sulpiride plasma levels predicted the effect of working memory manipulation on activation in the putamen, suggesting a dose-dependent effect of DA antagonism on a striatally based manipulation process. These effects occurred in the context of a drug-induced improvement in performance on trials requiring the manipulation of information in working memory but not on simple retrieval trials. No significant drug effects were observed in the prefrontal cortex. These results support models of dopamine function that posit a 'gating' function for dopamine D2 receptors in the striatum, which enables the flexible updating and manipulation of information in working memory.

Dopaminergic modulation of the human reward system: a placebo-controlled dopamine depletion fMRI study.

PubMed

da Silva Alves, Fabiana; Schmitz, Nicole; Figee, Martijn; Abeling, Nico; Hasler, Gregor; van der Meer, Johan; Nederveen, Aart; de Haan, Lieuwe; Linszen, Don; van Amelsvoort, Therese

2011-04-01

Reward related behaviour is linked to dopaminergic neurotransmission. Our aim was to gain insight into dopaminergic involvement in the human reward system. Combining functional magnetic resonance imaging with dopaminergic depletion by α-methylparatyrosine we measured dopamine-related brain activity in 10 healthy volunteers. In addition to blood-oxygen-level-dependent (BOLD) contrast we assessed the effect of dopaminergic depletion on prolactin response, peripheral markers for dopamine and norepinephrine. In the placebo condition we found increased activation in the left caudate and left cingulate gyrus during anticipation of reward. In the α-methylparatyrosine condition there was no significant brain activation during anticipation of reward or loss. In α-methylparatyrosine, anticipation of reward vs. loss increased activation in the right insula, left frontal, right parietal cortices and right cingulate gyrus. Comparing placebo versus α-methylparatyrosine showed increased activation in the left cingulate gyrus during anticipation of reward and the left medial frontal gyrus during anticipation of loss. α-methylparatyrosine reduced levels of dopamine in urine and homovanillic acid in plasma and increased prolactin. No significant effect of α-methylparatyrosine was found on norepinephrine markers. Our findings implicate distinct patterns of BOLD underlying reward processing following dopamine depletion, suggesting a role of dopaminergic neurotransmission for anticipation of monetary reward.

Size-controlled gold nanoparticles obtained from electrodeposited amidoferrocenylpoly(propyleneimine) dendrimer-templates for the electrochemical sensing of dopamine

NASA Astrophysics Data System (ADS)

Villena, Carlos; Bravo, Marta; Alonso, Beatriz; Casado, Carmen M.; Losada, José; García Armada, M. Pilar

2017-10-01

Nanometer-scale gold particles exhibit size-dependent electronic properties with important sensing and biosensing applications. In the same way, a lot of analytes show some type of surface-sensitive reaction and the electrode material has a strong influence on the catalytic activity. In this work we study the kinetics and electrochemistry of electrodes with size controlled gold nanoparticles, obtained by electrodeposited amidoferrocenylpoly(propyleneimine) dendrimers of two generations as templates, and the kinetics and the analytical response to the oxidation of dopamine. We demonstrate that the four-types of modified electrodes show good catalytic responses toward the oxidation of dopamine via different processes in relation with the absence or presence of gold nanoparticles and their size. The best response was obtained with the largest nanoparticles, obtained with the first generation dendrimer-template at 0.3 V vs. SCE, with three linear ranges (0-70, 70-600 and 600-1000 μM), with sensitivities 585.7; 466.0 and 314.3 μA/mM cm2, and limit of detection of 0.01 μM. The effect of interfering substances has been studied by differential pulse voltammetry and the developed sensor has been successfully used for the determination of dopamine in a commercial dopamine hydrochloride injection and in spiked Human urine.

Fluorescent microarray for multiplexed quantification of environmental contaminants in seawater samples

USDA-ARS?s Scientific Manuscript database

The development of a fluorescent multiplexed microarray platform able to detect and quantify a wide variety of pollutants in seawater is reported. The microarray platform has been manufactured by spotting 6 different bioconjugate competitors and it uses a cocktail of 6 monoclonal and polyclonal anti...

Manual Solid-Phase Peptide Synthesis of Metallocene-Peptide Bioconjugates

ERIC Educational Resources Information Center

Kirin, Srecko I.; Noor, Fozia; Metzler-Nolte, Nils; Mier, Walter

2007-01-01

A simple and relatively inexpensive procedure for preparing a biologically active peptide using solid phase peptide synthesis (SPPS) is described. Fourth-year undergraduate students have gained firsthand experience from the solid-phase synthesis techniques and they have become familiar with modern analytical techniques based on the particular…

Medial prefrontal cortex dopamine controls the persistent storage of aversive memories

PubMed Central

Gonzalez, María C.; Kramar, Cecilia P.; Tomaiuolo, Micol; Katche, Cynthia; Weisstaub, Noelia; Cammarota, Martín; Medina, Jorge H.

2014-01-01

Medial prefrontal cortex (mPFC) is essential for initial memory processing and expression but its involvement in persistent memory storage has seldom been studied. Using the hippocampus dependent inhibitory avoidance learning task and the hippocampus-independent conditioned taste aversion paradigm together with specific dopamine receptor agonists and antagonists we found that persistence but not formation of long-term aversive memories requires dopamine D1/D5 receptors activation in mPFC immediately after training and, depending on the task, between 6 and 12 h later. Our results indicate that besides its well-known participation in retrieval and early consolidation, mPFC also modulates the endurance of long-lasting aversive memories regardless of whether formation of the aversive mnemonic trace requires the participation of the hippocampus. PMID:25506318

Tautomeric and ionisation forms of dopamine and tyramine in the solid state

NASA Astrophysics Data System (ADS)

Cruickshank, Laura; Kennedy, Alan R.; Shankland, Norman

2013-11-01

Crystallisation of the phenylethylamine neurotransmitter dopamine from basic aqueous solution yielded the 3-phenoxide Zwitterionic tautomer, despite this being a minority form in the solution state. In the crystal structure, dopamine has a dimeric [OCCOH]2 hydrogen bonded catechol motif that expands through Nsbnd H⋯O interactions to give a 2-dimensional sheet of classical hydrogen bonds. These sheets are further interconnected by Nsbnd H⋯π interactions. The structurally related base tyramine crystallises under similar conditions as a hemihydrate with all four possible species of tyramine present (cationic, anionic, Zwitterionic and neutral) in the crystal structure. Single crystal X-ray diffraction studies at 121 and 293 K showed dynamic hydrogen atom disorder for the phenol/phenoxide group, suggesting that the tyramine speciation observed arises from a solid-state process.

Miniaturized and Wireless Optical Neurotransmitter Sensor for Real-Time Monitoring of Dopamine in the Brain

PubMed Central

Kim, Min H.; Yoon, Hargsoon; Choi, Sang H.; Zhao, Fei; Kim, Jongsung; Song, Kyo D.; Lee, Uhn

2016-01-01

Real-time monitoring of extracellular neurotransmitter concentration offers great benefits for diagnosis and treatment of neurological disorders and diseases. This paper presents the study design and results of a miniaturized and wireless optical neurotransmitter sensor (MWONS) for real-time monitoring of brain dopamine concentration. MWONS is based on fluorescent sensing principles and comprises a microspectrometer unit, a microcontroller for data acquisition, and a Bluetooth wireless network for real-time monitoring. MWONS has a custom-designed application software that controls the operation parameters for excitation light sources, data acquisition, and signal processing. MWONS successfully demonstrated a measurement capability with a limit of detection down to a 100 nanomole dopamine concentration, and high selectivity to ascorbic acid (90:1) and uric acid (36:1). PMID:27834927

Miniaturized and Wireless Optical Neurotransmitter Sensor for Real-Time Monitoring of Dopamine in the Brain.

PubMed

Kim, Min H; Yoon, Hargsoon; Choi, Sang H; Zhao, Fei; Kim, Jongsung; Song, Kyo D; Lee, Uhn

2016-11-10

Real-time monitoring of extracellular neurotransmitter concentration offers great benefits for diagnosis and treatment of neurological disorders and diseases. This paper presents the study design and results of a miniaturized and wireless optical neurotransmitter sensor (MWONS) for real-time monitoring of brain dopamine concentration. MWONS is based on fluorescent sensing principles and comprises a microspectrometer unit, a microcontroller for data acquisition, and a Bluetooth wireless network for real-time monitoring. MWONS has a custom-designed application software that controls the operation parameters for excitation light sources, data acquisition, and signal processing. MWONS successfully demonstrated a measurement capability with a limit of detection down to a 100 nanomole dopamine concentration, and high selectivity to ascorbic acid (90:1) and uric acid (36:1).

Distinctive striatal dopamine signaling after dieting and gastric bypass.

PubMed

Hankir, Mohammed K; Ashrafian, Hutan; Hesse, Swen; Horstmann, Annette; Fenske, Wiebke K

2015-05-01

Highly palatable and/or calorically dense foods, such as those rich in fat, engage the striatum to govern and set complex behaviors. Striatal dopamine signaling has been implicated in hedonic feeding and the development of obesity. Dieting and bariatric surgery have markedly different outcomes on weight loss, yet how these interventions affect central homeostatic and food reward processing remains poorly understood. Here, we propose that dieting and gastric bypass produce distinct changes in peripheral factors with known roles in regulating energy homeostasis, resulting in differential modulation of nigrostriatal and mesolimbic dopaminergic reward circuits. Enhancement of intestinal fat metabolism after gastric bypass may also modify striatal dopamine signaling contributing to its unique long-term effects on feeding behavior and body weight in obese individuals. Copyright © 2015 Elsevier Ltd. All rights reserved.

Amplified amperometric aptasensor for selective detection of protein using catalase-functional DNA-PtNPs dendrimer as a synergetic signal amplification label.

PubMed

Zhang, Juan; Yuan, Yali; biXie, Shun; Chai, Yaqin; Yuan, Ruo

2014-10-15

In this work, we present a new strategy to construct an electrochemical aptasensor for sensitive detection of platelet-derived growth factor BB (PDGF-BB) based on the synergetic amplification of a three-dimensional (3D) nanoscale catalase (CAT) enzyme-functional DNA-platinum nanoparticles (PtNPs) dendrimer through autonomous layer-by-layer assembly. Firstly, polyamidoaminedendrimer (PAMAM) with a hyper-branched and three-dimensional structure was served as nanocarriers to coimmobilize a large number of PDGF-BB binding aptamer (PBA II) and ssDNA 1 (S1) to form PBA II-PAMAM-S1 bioconjugate. In the presence of PDGF-BB, the bioconjugate was self-assembled on the electrode by sandwich assay. Following that, the carried S1 propagated a chain reaction of hybridization events between CAT-PtNPs-S1 and CAT-PtNPs-ssDNA 2 (S2) to form a 3D nanoscale CAT-functional PtNPs-DNA dendrimer, which successfully immobilized substantial CAT enzyme and PtNPs with superior catalysis activity. In this process, the formed negatively charged double-helix DNA could cause the intercalation of hexaammineruthenium(III) chloride (RuHex) into the groove via electrostatic interactions. Thus, numerous RuHex redox probes and CAT were decorated inside/outside of the dendrimer. In the presence of H2O2 in electrolytic cell, the synergistic reaction of CAT and PtNPs towards electrocatalysis could further amplify electrochemical signal. Under optimal condition, the CAT-PtNPs-DNA dendrimer-based sensing system presented a linear dependence between the reduction peak currents and logarithm of PDGF-BB concentrations in the range of 0.00005-35 nM with a relatively low detection limit of 0.02 pM. Copyright © 2014 Elsevier B.V. All rights reserved.

Gold and silver nanoparticles for biomolecule immobilization and enzymatic catalysis

PubMed Central

2012-01-01

In this work, a simple method for alcohol synthesis with high enantiomeric purity was proposed. For this, colloidal gold and silver surface modifications with 3-mercaptopropanoic acid and cysteamine were used to generate carboxyl and amine functionalized gold and silver nanoparticles of 15 and 45 nm, respectively. Alcohol dehydrogenase from Thermoanaerobium brockii (TbADH) and its cofactor (NADPH) were physical and covalent (through direct adsorption and using cross-linker) immobilized on nanoparticles' surface. In contrast to the physical and covalent immobilizations that led to a loss of 90% of the initial enzyme activity and 98% immobilization, the use of a cross-linker in immobilization process promoted a loss to 30% of the initial enzyme activity and >92% immobilization. The yield of NADPH immobilization was about 80%. The best results in terms of activity were obtained with Ag-citr nanoparticle functionalized with carboxyl groups (Ag-COOH), Au-COOH(CTAB), and Au-citr functionalized with amine groups and stabilized with CTAB (Au-NH2(CTAB)) nanoparticles treated with 0.7% and 1.0% glutaraldehyde. Enzyme conformation upon immobilization was studied using fluorescence and circular dichroism spectroscopies. Shift in ellipticity at 222 nm with about 4 to 7 nm and significant decreasing in fluorescence emission for all bioconjugates were observed by binding of TbADH to silver/gold nanoparticles. Emission redshifting of 5 nm only for Ag-COOH-TbADH bioconjugate demonstrated change in the microenvironment of TbADH. Enzyme immobilization on glutaraldehyde-treated Au-NH2(CTAB) nanoparticles promotes an additional stabilization preserving about 50% of enzyme activity after 15 days storage. Nanoparticles attached-TbADH-NADPH systems were used for enantioselective (ee > 99%) synthesis of (S)-7-hydroxy-2-tetralol. PMID:22655978

Gold and silver nanoparticles for biomolecule immobilization and enzymatic catalysis.

PubMed

Petkova, Galina A; Záruba, Capital Ka Cyrillicamil; Zvátora, Pavel; Král, Vladimír

2012-06-01

In this work, a simple method for alcohol synthesis with high enantiomeric purity was proposed. For this, colloidal gold and silver surface modifications with 3-mercaptopropanoic acid and cysteamine were used to generate carboxyl and amine functionalized gold and silver nanoparticles of 15 and 45 nm, respectively. Alcohol dehydrogenase from Thermoanaerobium brockii (TbADH) and its cofactor (NADPH) were physical and covalent (through direct adsorption and using cross-linker) immobilized on nanoparticles' surface. In contrast to the physical and covalent immobilizations that led to a loss of 90% of the initial enzyme activity and 98% immobilization, the use of a cross-linker in immobilization process promoted a loss to 30% of the initial enzyme activity and >92% immobilization. The yield of NADPH immobilization was about 80%. The best results in terms of activity were obtained with Ag-citr nanoparticle functionalized with carboxyl groups (Ag-COOH), Au-COOH(CTAB), and Au-citr functionalized with amine groups and stabilized with CTAB (Au-NH2(CTAB)) nanoparticles treated with 0.7% and 1.0% glutaraldehyde. Enzyme conformation upon immobilization was studied using fluorescence and circular dichroism spectroscopies. Shift in ellipticity at 222 nm with about 4 to 7 nm and significant decreasing in fluorescence emission for all bioconjugates were observed by binding of TbADH to silver/gold nanoparticles. Emission redshifting of 5 nm only for Ag-COOH-TbADH bioconjugate demonstrated change in the microenvironment of TbADH. Enzyme immobilization on glutaraldehyde-treated Au-NH2(CTAB) nanoparticles promotes an additional stabilization preserving about 50% of enzyme activity after 15 days storage. Nanoparticles attached-TbADH-NADPH systems were used for enantioselective (ee > 99%) synthesis of (S)-7-hydroxy-2-tetralol.

Chemically-defined camelid antibody bioconjugate for the magnetic resonance imaging of Alzheimer's disease.

PubMed

Vandesquille, Matthias; Li, Tengfei; Po, Chrystelle; Ganneau, Christelle; Lenormand, Pascal; Dudeffant, Clémence; Czech, Christian; Grueninger, Fiona; Duyckaerts, Charles; Delatour, Benoît; Dhenain, Marc; Lafaye, Pierre; Bay, Sylvie

Today, molecular imaging of neurodegenerative diseases is mainly based on small molecule probes. Alternatively, antibodies are versatile tools that may be developed as new imaging agents. Indeed, they can be readily obtained to specifically target any antigen of interest and their scaffold can be functionalized. One of the critical issues involved in translating antibody-based probes to the clinic is the design and synthesis of perfectly-defined conjugates. Camelid single-domain antibody-fragments (VHHs) are very small and stable antibodies that are able to diffuse in tissues and potentially cross the blood brain barrier (BBB). Here, we selected a VHH (R3VQ) specifically targeting one of the main lesions of Alzheimer's disease (AD), namely the amyloid-beta (Aß) deposits. It was used as a scaffold for the design of imaging probes for magnetic resonance imaging (MRI) and labeled with the contrastophore gadolinium using either a random or site-specific approach. In contrast to the random strategy, the site-specific conjugation to a single reduced cysteine in the C-terminal part of the R3VQ generates a well-defined bioconjugate in a high yield process. This new imaging probe is able to cross the BBB and label Aß deposits after intravenous injection. Also, it displays improved r1 and r2 relaxivities, up to 30 times higher than a widely used clinical contrast agent, and it allows MRI detection of amyloid deposits in post mortem brain tissue of a mouse model of AD. The ability to produce chemically-defined VHH conjugates that cross the BBB opens the way for future development of tailored imaging probes targeting intracerebral antigens.

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

Dopamine dysregulation hypothesis: the common basis for motivational anhedonia in major depressive disorder and schizophrenia?

PubMed

Szczypiński, Jan Józef; Gola, Mateusz

2018-03-24

Abnormalities in reward processing are crucial symptoms of major depressive disorder (MDD) and schizophrenia (SCH). Recent neuroscientific findings regarding MDD have led to conclusions about two different symptoms related to reward processing: motivational and consummatory anhedonia, corresponding, respectively, to impaired motivation to obtain rewards ('wanting'), and diminished satisfaction from consuming them ('liking'). One can ask: which of these is common for MDD and SCH. In our review of the latest neuroscientific studies, we show that MDD and SCH do not share consummatory anhedonia, as SCH patients usually have unaltered liking. Therefore, we investigated whether motivational anhedonia is the common symptom across MDD and SCH. With regard to the similarities and differences between the neural mechanisms of MDD and SCH, here we expand the current knowledge of motivation deficits and present the common underlying mechanism of motivational anhedonia - the dopamine dysregulation hypothesis - stating that any prolonged dysregulation in tonic dopamine signaling that exceeds the given equilibrium can lead to striatal dysfunction and motivational anhedonia. The implications for further research and treatment of MDD and SCH are also discussed.

Basal ganglia and Dopamine Contributions to Probabilistic Category Learning

PubMed Central

Shohamy, D.; Myers, C.E.; Kalanithi, J.; Gluck, M.A.

2009-01-01

Studies of the medial temporal lobe and basal ganglia memory systems have recently been extended towards understanding the neural systems contributing to category learning. The basal ganglia, in particular, have been linked to probabilistic category learning in humans. A separate parallel literature in systems neuroscience has emerged, indicating a role for the basal ganglia and related dopamine inputs in reward prediction and feedback processing. Here, we review behavioral, neuropsychological, functional neuroimaging, and computational studies of basal ganglia and dopamine contributions to learning in humans. Collectively, these studies implicate the basal ganglia in incremental, feedback-based learning that involves integrating information across multiple experiences. The medial temporal lobes, by contrast, contribute to rapid encoding of relations between stimuli and support flexible generalization of learning to novel contexts and stimuli. By breaking down our understanding of the cognitive and neural mechanisms contributing to different aspects of learning, recent studies are providing insight into how, and when, these different processes support learning, how they may interact with each other, and the consequence of different forms of learning for the representation of knowledge. PMID:18061261

Dopamine Receptor-Specific Contributions to the Computation of Value.

PubMed

Burke, Christopher J; Soutschek, Alexander; Weber, Susanna; Raja Beharelle, Anjali; Fehr, Ernst; Haker, Helene; Tobler, Philippe N

2018-05-01

Dopamine is thought to play a crucial role in value-based decision making. However, the specific contributions of different dopamine receptor subtypes to the computation of subjective value remain unknown. Here we demonstrate how the balance between D1 and D2 dopamine receptor subtypes shapes subjective value computation during risky decision making. We administered the D2 receptor antagonist amisulpride or placebo before participants made choices between risky options. Compared with placebo, D2 receptor blockade resulted in more frequent choice of higher risk and higher expected value options. Using a novel model fitting procedure, we concurrently estimated the three parameters that define individual risk attitude according to an influential theoretical account of risky decision making (prospect theory). This analysis revealed that the observed reduction in risk aversion under amisulpride was driven by increased sensitivity to reward magnitude and decreased distortion of outcome probability, resulting in more linear value coding. Our data suggest that different components that govern individual risk attitude are under dopaminergic control, such that D2 receptor blockade facilitates risk taking and expected value processing.

Making sense: Dopamine activates conscious self‐monitoring through medial prefrontal cortex

PubMed Central

Joensson, Morten; Thomsen, Kristine Rømer; Andersen, Lau M.; Gross, Joachim; Mouridsen, Kim; Sandberg, Kristian; Østergaard, Leif

2015-01-01

Abstract When experiences become meaningful to the self, they are linked to synchronous activity in a paralimbic network of self‐awareness and dopaminergic activity. This network includes medial prefrontal and medial parietal/posterior cingulate cortices, where transcranial magnetic stimulation may transiently impair self‐awareness. Conversely, we hypothesize that dopaminergic stimulation may improve self‐awareness and metacognition (i.e., the ability of the brain to consciously monitor its own cognitive processes). Here, we demonstrate improved noetic (conscious) metacognition by oral administration of 100 mg dopamine in minimal self‐awareness. In a separate experiment with extended self‐awareness dopamine improved the retrieval accuracy of memories of self‐judgment (autonoetic, i.e., explicitly self‐conscious) metacognition. Concomitantly, magnetoencephalography (MEG) showed increased amplitudes of oscillations (power) preferentially in the medial prefrontal cortex. Given that electromagnetic activity in this region is instrumental in self‐awareness, this explains the specific effect of dopamine on explicit self‐awareness and autonoetic metacognition. Hum Brain Mapp 36:1866–1877, 2015. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.. PMID:25627861

Lack of association between alcohol-dependence and D3 dopamine receptor gene in three independent samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gorwood, P.; Feingold, J.; Ades, J.

1995-12-18

Numerous studies on the involvement of dopamine receptors in the genetics of alcoholism focused on associations between a polymorphism of the D2 dopamine receptor (DRD2) gene and alcohol dependence. However, the results of these studies are conflicting. Another receptor, the D3 dopamine receptor (DRD3), may be of additional interest since it is specifically located in the limbic area, and in particular in the nucleus accumbens which plays a significant role in the reward process of addiction behavior. We thus tested the association in three independent samples of alcoholic patients, with different origins and various inclusion criteria. No difference in themore » DRD3 gene polymorphism emerged between controls and alcoholic patients, regardless of their origin, inclusion criteria, or presence or absence of the DRD2 TaqI A1-allele. Despite the fact that more information could have been considered and that association studies provide limited information, there is good evidence that this DRD3 polymorphism does not play a major role in the genetic component of alcoholism. 17 refs., 2 tabs.« less

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

PubMed Central

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

2005-01-01

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

Dynorphin/Kappa Opioid Receptor Signaling in Preclinical Models of Alcohol, Drug, and Food Addiction.

PubMed

Karkhanis, Anushree; Holleran, Katherine M; Jones, Sara R

2017-01-01

The dynorphin/kappa opioid receptor (KOR) system is implicated in the "dark side" of addiction, in which stress exacerbates maladaptive responses to drug and alcohol exposure. For example, acute stress and acute ethanol exposure result in an elevation in dynorphin, the KOR endogenous ligand. Activation of KORs results in modulation of several neurotransmitters; however, this chapter will focus on its regulatory effects on dopamine in mesolimbic areas. Specifically, KOR activation has an inhibitory effect on dopamine release, thereby influencing reward processing. Repeated stimulation of KORs, for example, via chronic drug and/or stress exposure, results in increased function of the dynorphin/KOR system. This augmentation in KOR function shifts the homeostatic balance in favor of an overall reduction in dopamine signaling via either by reducing dopamine release or by increasing dopamine transporter function. This chapter examines the effects of chronic ethanol exposure on KOR function and the downstream effects on dopamine transmission. Additionally, the impact of chronic cocaine exposure and its effects on KOR function will be explored. Further, KORs may also be involved in driving excessive consumption of food, contributing to the risk of developing obesity. While some studies have shown that KOR agonists reduce drug intake, other studies have shown that antagonists reduce addiction-like behaviors, demonstrating therapeutic potential. For example, KOR inhibition reduces ethanol intake in dependent animals, motivation to self-administer cocaine in chronic stress-exposed animals, and food consumption in obese animals. This chapter will delve into the mechanisms by which modulation of the dynorphin/KOR system may be therapeutic. © 2017 Elsevier Inc. All rights reserved.

Genetically determined interaction between the dopamine transporter and the D2 receptor on prefronto-striatal activity and volume in humans.

PubMed

Bertolino, Alessandro; Fazio, Leonardo; Di Giorgio, Annabella; Blasi, Giuseppe; Romano, Raffaella; Taurisano, Paolo; Caforio, Grazia; Sinibaldi, Lorenzo; Ursini, Gianluca; Popolizio, Teresa; Tirotta, Emanuele; Papp, Audrey; Dallapiccola, Bruno; Borrelli, Emiliana; Sadee, Wolfgang

2009-01-28

Dopamine modulation of neuronal activity during memory tasks identifies a nonlinear inverted-U shaped function. Both the dopamine transporter (DAT) and dopamine D(2) receptors (encoded by DRD(2)) critically regulate dopamine signaling in the striatum and in prefrontal cortex during memory. Moreover, in vitro studies have demonstrated that DAT and D(2) proteins reciprocally regulate each other presynaptically. Therefore, we have evaluated the genetic interaction between a DRD(2) polymorphism (rs1076560) causing reduced presynaptic D(2) receptor expression and the DAT 3'-VNTR variant (affecting DAT expression) in a large sample of healthy subjects undergoing blood oxygenation level-dependent (BOLD)-functional magnetic resonance imaging (MRI) during memory tasks and structural MRI. Results indicated a significant DRD(2)/DAT interaction in prefrontal cortex and striatum BOLD activity during both working memory and encoding of recognition memory. The differential effect on BOLD activity of the DAT variant was mostly manifest in the context of the DRD(2) allele associated with lower presynaptic expression. Similar results were also evident for gray matter volume in caudate. These interactions describe a nonlinear relationship between compound genotypes and brain activity or gray matter volume. Complementary data from striatal protein extracts from wild-type and D(2) knock-out animals (D2R(-/-)) indicate that DAT and D(2) proteins interact in vivo. Together, our results demonstrate that the interaction between genetic variants in DRD(2) and DAT critically modulates the nonlinear relationship between dopamine and neuronal activity during memory processing.

Developmental imaging genetics: linking dopamine function to adolescent behavior.

PubMed

Padmanabhan, Aarthi; Luna, Beatriz

2014-08-01

Adolescence is a period of development characterized by numerous neurobiological changes that significantly influence behavior and brain function. Adolescence is of particular interest due to the alarming statistics indicating that mortality rates increase two to three-fold during this time compared to childhood, due largely to a peak in risk-taking behaviors resulting from increased impulsivity and sensation seeking. Furthermore, there exists large unexplained variability in these behaviors that are in part mediated by biological factors. Recent advances in molecular genetics and functional neuroimaging have provided a unique and exciting opportunity to non-invasively study the influence of genetic factors on brain function in humans. While genes do not code for specific behaviors, they do determine the structure and function of proteins that are essential to the neuronal processes that underlie behavior. Therefore, studying the interaction of genotype with measures of brain function over development could shed light on critical time points when biologically mediated individual differences in complex behaviors emerge. Here we review animal and human literature examining the neurobiological basis of adolescent development related to dopamine neurotransmission. Dopamine is of critical importance because of (1) its role in cognitive and affective behaviors, (2) its role in the pathogenesis of major psychopathology, and (3) the protracted development of dopamine signaling pathways over adolescence. We will then focus on current research examining the role of dopamine-related genes on brain function. We propose the use of imaging genetics to examine the influence of genetically mediated dopamine variability on brain function during adolescence, keeping in mind the limitations of this approach. Copyright © 2014 Elsevier Inc. All rights reserved.

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.

MicroRNA-133 Inhibits Behavioral Aggregation by Controlling Dopamine Synthesis in Locusts

PubMed Central

Wang, Yanli; Guo, Xiaojiao; He, Jing; Kang, Le

2014-01-01

Phenotypic plasticity is ubiquitous and primarily controlled by interactions between environmental and genetic factors. The migratory locust, a worldwide pest, exhibits pronounced phenotypic plasticity, which is a population density-dependent transition that occurs between the gregarious and solitary phases. Genes involved in dopamine synthesis have been shown to regulate the phase transition of locusts. However, the function of microRNAs in this process remains unknown. In this study, we report the participation of miR-133 in dopamine production and the behavioral transition by negatively regulating two critical genes, henna and pale, in the dopamine pathway. miR-133 participated in the post-transcriptional regulation of henna and pale by binding to their coding region and 3′ untranslated region, respectively. miR-133 displayed cellular co-localization with henna/pale in the protocerebrum, and its expression in the protocerebrum was negatively correlated with henna and pale expression. Moreover, miR-133 agomir delivery suppressed henna and pale expression, which consequently decreased dopamine production, thus resulting in the behavioral shift of the locusts from the gregarious phase to the solitary phase. Increasing the dopamine content could rescue the solitary phenotype, which was induced by miR-133 agomir delivery. Conversely, miR-133 inhibition increased the expression of henna and pale, resulting in the gregarious-like behavior of solitary locusts; this gregarious phenotype could be rescued by RNA interference of henna and pale. This study shows the novel function and modulation pattern of a miRNA in phenotypic plasticity and provides insight into the underlying molecular mechanisms of the phase transition of locusts. PMID:24586212

MicroRNA-133 inhibits behavioral aggregation by controlling dopamine synthesis in locusts.

PubMed

Yang, Meiling; Wei, Yuanyuan; Jiang, Feng; Wang, Yanli; Guo, Xiaojiao; He, Jing; Kang, Le

2014-02-01

Phenotypic plasticity is ubiquitous and primarily controlled by interactions between environmental and genetic factors. The migratory locust, a worldwide pest, exhibits pronounced phenotypic plasticity, which is a population density-dependent transition that occurs between the gregarious and solitary phases. Genes involved in dopamine synthesis have been shown to regulate the phase transition of locusts. However, the function of microRNAs in this process remains unknown. In this study, we report the participation of miR-133 in dopamine production and the behavioral transition by negatively regulating two critical genes, henna and pale, in the dopamine pathway. miR-133 participated in the post-transcriptional regulation of henna and pale by binding to their coding region and 3' untranslated region, respectively. miR-133 displayed cellular co-localization with henna/pale in the protocerebrum, and its expression in the protocerebrum was negatively correlated with henna and pale expression. Moreover, miR-133 agomir delivery suppressed henna and pale expression, which consequently decreased dopamine production, thus resulting in the behavioral shift of the locusts from the gregarious phase to the solitary phase. Increasing the dopamine content could rescue the solitary phenotype, which was induced by miR-133 agomir delivery. Conversely, miR-133 inhibition increased the expression of henna and pale, resulting in the gregarious-like behavior of solitary locusts; this gregarious phenotype could be rescued by RNA interference of henna and pale. This study shows the novel function and modulation pattern of a miRNA in phenotypic plasticity and provides insight into the underlying molecular mechanisms of the phase transition of locusts.

Histidine-decarboxylase knockout mice show deficient nonreinforced episodic object memory, improved negatively reinforced water-maze performance, and increased neo- and ventro-striatal dopamine turnover.

PubMed

Dere, Ekrem; De Souza-Silva, Maria A; Topic, Bianca; Spieler, Richard E; Haas, Helmut L; Huston, Joseph P

2003-01-01

The brain's histaminergic system has been implicated in hippocampal synaptic plasticity, learning, and memory, as well as brain reward and reinforcement. Our past pharmacological and lesion studies indicated that the brain's histamine system exerts inhibitory effects on the brain's reinforcement respective reward system reciprocal to mesolimbic dopamine systems, thereby modulating learning and memory performance. Given the close functional relationship between brain reinforcement and memory processes, the total disruption of brain histamine synthesis via genetic disruption of its synthesizing enzyme, histidine decarboxylase (HDC), in the mouse might have differential effects on learning dependent on the task-inherent reinforcement contingencies. Here, we investigated the effects of an HDC gene disruption in the mouse in a nonreinforced object exploration task and a negatively reinforced water-maze task as well as on neo- and ventro-striatal dopamine systems known to be involved in brain reward and reinforcement. Histidine decarboxylase knockout (HDC-KO) mice had higher dihydrophenylacetic acid concentrations and a higher dihydrophenylacetic acid/dopamine ratio in the neostriatum. In the ventral striatum, dihydrophenylacetic acid/dopamine and 3-methoxytyramine/dopamine ratios were higher in HDC-KO mice. Furthermore, the HDC-KO mice showed improved water-maze performance during both hidden and cued platform tasks, but deficient object discrimination based on temporal relationships. Our data imply that disruption of brain histamine synthesis can have both memory promoting and suppressive effects via distinct and independent mechanisms and further indicate that these opposed effects are related to the task-inherent reinforcement contingencies.

Nature or Nurture? Determining the Heritability of Human Striatal Dopamine Function: an [18F]-DOPA PET Study

PubMed Central

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

2013-01-01

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. PMID:23093224

Bioconjugates of luminescent CdSe-ZnS quantum dots with an engineered two-domain protein G for use in fluoroimmunoassays

NASA Astrophysics Data System (ADS)

Tran, Phan T.; Goldman, Ellen R.; Mattoussi, Hedi M.; Anderson, George P.; Mauro, J. Matthew

2001-06-01

Colloidal semiconductor quantum dots (QDs) seem suitable for labeling certain biomolecules for use in fluorescent tagging applications, such as fluoro-immunoassays. Compared to organic dye labels, Qds are resistant to photo-degradation, and these luminescent nanoparticles have size-dependent emission spectra spanning a wide range of wavelengths in the visible and near IR. We previously described an electrostatic self-assembly approach for conjugating highly luminescent colloidal CdSe-ZnS core-shell Qds with engineered two-domain recombinant proteins. Here we describe the application of this approach to prepare QD conjugates with the (Beta) 2 immunoglobin G (IgG) binding domain of streptococcal protein G (PG) appended with a basic lucine zipper attachment domain (PG-zb). We also demonstrate that the QD/PG conjugates retain their ability to bind IgG antibodies, and that a specific antibody coupled to QD via the PG functional domain efficiently binds its antigen. These preliminary results indicate that electrostatically self-assembled QD/PG-zb/IgG bioconjugates can be used in fluoro-immunoassays.

Photoactivated bioconjugation between ortho-azidophenols and anilines: a facile approach to biomolecular photopatterning.

PubMed

El Muslemany, Kareem M; Twite, Amy A; ElSohly, Adel M; Obermeyer, Allie C; Mathies, Richard A; Francis, Matthew B

2014-09-10

Methods for the surface patterning of small molecules and biomolecules can yield useful platforms for drug screening, synthetic biology applications, diagnostics, and the immobilization of live cells. However, new techniques are needed to achieve the ease, feature sizes, reliability, and patterning speed necessary for widespread adoption. Herein, we report an easily accessible and operationally simple photoinitiated reaction that can achieve patterned bioconjugation in a highly chemoselective manner. The reaction involves the photolysis of 2-azidophenols to generate iminoquinone intermediates that couple rapidly to aniline groups. We demonstrate the broad functional group compatibility of this reaction for the modification of proteins, polymers, oligonucleotides, peptides, and small molecules. As a specific application, the reaction was adapted for the photolithographic patterning of azidophenol DNA on aniline glass substrates. The presence of the DNA was confirmed by the ability of the surface to capture living cells bearing the sequence complement on their cell walls or cytoplasmic membranes. Compared to other light-based DNA patterning methods, this reaction offers higher speed and does not require the use of a photoresist or other blocking material.

Bioconjugation of laminin peptide YIGSR with poly(styrene co-maleic acid) increases its antimetastatic effect on lung metastasis of B16-BL6 melanoma cells.

PubMed

Mu, Y; Kamada, H; Kaneda, Y; Yamamoto, Y; Kodaira, H; Tsunoda, S; Tsutsumi, Y; Maeda, M; Kawasaki, K; Nomizu, M; Yamada, Y; Mayumi, T

1999-02-05

A comb-shaped polymeric modifier, SMA [poly(styrene comaleic anhydride)], which binds to plasma albumin in blood was used to modify the synthetic cell-adhesive laminin peptide YIGSR, and its inhibitory effect on experimental lung metastasis of B16-BL6 melanoma cells was examined. YIGSR was chemically conjugated with SMA via formation of an amide bond between the N-terminal amino group of YIGSR and the carboxyl anhydride of SMA. The antimetastatic effect of SMA-conjugated YIGSR was approximately 50-fold greater than that of native YIGSR. When injected intravenously, SMA-YIGSR showed a 10-fold longer plasma half-life than native YIGSR in vivo. In addition, SMA-YIGSR had the same binding affinity to plasma albumin as SMA, while native YIGSR did not bind to albumin. These findings suggested that the enhanced antimetastatic effect of SMA-YIGSR may be due to its prolonged plasma half-life by binding to plasma albumin, and that bioconjugation of in vivo unstable peptides with SMA may facilitate their therapeutic use. Copyright 1999 Academic Press.

Aptamer-functionalized nano-biosensors.

PubMed

Chiu, Tai-Chia; Huang, Chih-Ching

2009-01-01

Nanomaterials have become one of the most interesting sensing materials because of their unique size- and shape-dependent optical properties, high surface energy and surface-to-volume ratio, and tunable surface properties. Aptamers are oligonucleotides that can bind their target ligands with high affinity. The use of nanomaterials that are bioconjugated with aptamers for selective and sensitive detection of analytes such as small molecules, metal ions, proteins, and cells has been demonstrated. This review focuses on recent progress in the development of biosensors by integrating functional aptamers with different types of nanomaterials, including quantum dots, magnetic nanoparticles (NPs), metallic NPs, and carbon nanotubes. Colorimetry, fluorescence, electrochemistry, surface plasmon resonance, surface-enhanced Raman scattering, and magnetic resonance imaging are common detection modes for a broad range of analytes with high sensitivity and selectivity when using aptamer bioconjugated nanomaterials (Apt-NMs). We highlight the important roles that the size and concentration of nanomaterials, the secondary structure and density of aptamers, and the multivalent interactions play in determining the specificity and sensitivity of the nanosensors towards analytes. Advantages and disadvantages of the Apt-NMs for bioapplications are focused.

Quantum dots targeted to vascular endothelial growth factor receptor 2 as a contrast agent for the detection of colorectal cancer

NASA Astrophysics Data System (ADS)

Carbary-Ganz, Jordan L.; Barton, Jennifer K.; Utzinger, Urs

2014-08-01

We successfully labeled colorectal cancer in vivo using quantum dots targeted to vascular endothelial growth factor receptor 2 (VEGFR2). Quantum dots with emission centered at 655 nm were bioconjugated to anti-VEGFR2 antibodies through streptavidin/biotin linking. The resulting QD655-VEGFR2 contrast agent was applied in vivo to the colon of azoxymethane (AOM) treated mice via lavage and allowed to incubate. The colons were then excised, cut longitudinally, opened to expose the lumen, and imaged en face using a fluorescence stereoscope. The QD655-VEGFR2 contrast agent produced a significant increase in contrast between diseased and undiseased tissues, allowing for fluorescence-based visualization of the diseased areas of the colon. Specificity was assessed by observing insignificant contrast increase when labeling colons of AOM-treated mice with quantum dots bioconjugated to isotype control antibodies, and by labeling the colons of saline-treated control mice. This contrast agent has a great potential for in vivo imaging of the colon through endoscopy.

Controlled levels of protein modification through a chromatography-mediated bioconjugation

DOE PAGES

Kwant, Richard L.; Jaffe, Jake; Palmere, Peter J.; ...

2015-02-27

Synthetically modified proteins are increasingly finding applications as well-defined scaffolds for materials. In practice it remains difficult to construct bioconjugates with precise levels of modification because of the limited number of repeated functional groups on proteins. This article describes a method to control the level of protein modification in cases where there exist multiple potential modification sites. A protein is first tagged with a handle using any of a variety of modification chemistries. This handle is used to isolate proteins with a particular number of modifications via affinity chromatography, and then the handle is elaborated with a desired moiety usingmore » an oxidative coupling reaction. This method results in a sample of protein with a well-defined number of modifications, and we find it particularly applicable to systems like protein homomultimers in which there is no way to discern between chemically identical subunits. We demonstrate the use of this method in the construction of a protein-templated light-harvesting mimic, a type of system which has historically been difficult to make in a well-defined manner.« less

Novel aptamer-nanoparticle bioconjugates enhances delivery of anticancer drug to MUC1-positive cancer cells in vitro.

PubMed

Yu, Chenchen; Hu, Yan; Duan, Jinhong; Yuan, Wei; Wang, Chen; Xu, Haiyan; Yang, Xian-Da

2011-01-01

MUC1 protein is an attractive target for anticancer drug delivery owing to its overexpression in most adenocarcinomas. In this study, a reported MUC1 protein aptamer is exploited as the targeting agent of a nanoparticle-based drug delivery system. Paclitaxel (PTX) loaded poly (lactic-co-glycolic-acid) (PLGA) nanoparticles were formulated by an emulsion/evaporation method, and MUC1 aptamers (Apt) were conjugated to the particle surface through a DNA spacer. The aptamer conjugated nanoparticles (Apt-NPs) are about 225.3 nm in size with a stable in vitro drug release profile. Using MCF-7 breast cancer cell as a MUC1-overexpressing model, the MUC1 aptamer increased the uptake of nanoparticles into the target cells as measured by flow cytometry. Moreover, the PTX loaded Apt-NPs enhanced in vitro drug delivery and cytotoxicity to MUC1(+) cancer cells, as compared with non-targeted nanoparticles that lack the MUC1 aptamer (P<0.01). The behavior of this novel aptamer-nanoparticle bioconjugates suggests that MUC1 aptamers may have application potential in targeted drug delivery towards MUC1-overexpressing tumors.

Synthetic Methodology for Asymmetric Ferrocene Derived Bio-conjugate Systems via Solid Phase Resin-based Methodology

PubMed Central

Scarborough, J. Hunter; Gonzalez, Paulina; Rodich, Sean; Green, Kayla N.

2015-01-01

Early detection is a key to successful treatment of most diseases, and is particularly imperative for the diagnosis and treatment of many types of cancer. The most common techniques utilized are imaging modalities such as Magnetic Resonance Imaging (MRI), Positron Emission Topography (PET), and Computed Topography (CT) and are optimal for understanding the physical structure of the disease but can only be performed once every four to six weeks due to the use of imaging agents and overall cost. With this in mind, the development of “point of care” techniques, such as biosensors, which evaluate the stage of disease and/or efficacy of treatment in the clinician’s office and do so in a timely manner, would revolutionize treatment protocols.1 As a means to exploring ferrocene based biosensors for the detection of biologically relevant molecules2, methods were developed to produce ferrocene-biotin bio-conjugates described herein. This report will focus on a biotin-ferrocene-cysteine system that can be immobilized on a gold surface. PMID:25866986

Ultrasensitive Immunosensor for Cancer Biomarker Proteins using Gold Nanoparticle Film Electrodes and Multienzyme-Particle Amplification

PubMed Central

Mani, Vigneshwaran; Chikkaveeraiah, Bhaskara V.; Patel, Vyomesh; Gutkind, J. Silvio; Rusling, James F.

2009-01-01

A densely packed gold nanoparticle platform combined with a multiple-enzyme labeled detection antibody-magnetic bead bioconjugate was used as the basis for an ultrasensitive electrochemical immunosensor to detect cancer biomarkers in serum. Sensitivity was greatly amplified by synthesizing magnetic bioconjugates particles containing 7500 horseradish peroxidase (HRP) labels along with detection antibodies (Ab2) attached to activated carboxyl groups on 1 µm diameter magnetic beads. These sensors had sensitivity of 31.5 µA mL ng−1 and detection limit (DL) of 0.5 pg mL−1 for prostate specific antigen (PSA) in 10 µL of undiluted serum. This represents an ultralow mass DL of 5 fg PSA, eight fold better than a previously reported carbon nanotube (CNT) forest immunosensor featuring multiple labels on carbon nanotubes, and near or below the normal serum levels of most cancer biomarkers. Measurements of PSA in cell lysates and human serum of cancer patients gave excellent correlations with standard ELISA assays. These easily fabricated AuNP immunosensors show excellent promise for future fabrication of bioelectronic arrays. PMID:19216571

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

PubMed Central

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

2018-01-01

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. PMID:27038339

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. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Where attention falls: Increased risk of falls from the converging impact of cortical cholinergic and midbrain dopamine loss on striatal function.

PubMed

Sarter, Martin; Albin, Roger L; Kucinski, Aaron; Lustig, Cindy

2014-07-01

Falls are a major source of hospitalization, long-term institutionalization, and death in older adults and patients with Parkinson's disease (PD). Limited attentional resources are a major risk factor for falls. In this review, we specify cognitive-behavioral mechanisms that produce falls and map these mechanisms onto a model of multi-system degeneration. Results from PET studies in PD fallers and findings from a recently developed animal model support the hypothesis that falls result from interactions between loss of basal forebrain cholinergic projections to the cortex and striatal dopamine loss. Striatal dopamine loss produces inefficient, low-vigor gait, posture control, and movement. Cortical cholinergic deafferentation impairs a wide range of attentional processes, including monitoring of gait, posture and complex movements. Cholinergic cell loss reveals the full impact of striatal dopamine loss on motor performance, reflecting loss of compensatory attentional supervision of movement. Dysregulation of dorsomedial striatal circuitry is an essential, albeit not exclusive, mediator of falls in this dual-system model. Because cholinergic neuromodulatory activity influences cortical circuitry primarily via stimulation of α4β2* nicotinic acetylcholine receptors, and because agonists at these receptors are known to benefit attentional processes in animals and humans, treating PD fallers with such agonists, as an adjunct to dopaminergic treatment, is predicted to reduce falls. Falls are an informative behavioral endpoint to study attentional-motor integration by striatal circuitry. Copyright © 2014 Elsevier Inc. All rights reserved.

Where attention falls: Increased risk of falls from the converging impact of cortical cholinergic and midbrain dopamine loss on striatal function

PubMed Central

Sarter, Martin; Albin, Roger L.; Kucinski, Aaron; Lustig, Cindy

2015-01-01

Falls are a major source of hospitalization, long-term institutionalization, and death in older adults and patients with Parkinson’s disease (PD). Limited attentional resources are a major risk factor for falls. In this review, we specify cognitive–behavioral mechanisms that produce falls and map these mechanisms onto a model of multi-system degeneration. Results from PET studies in PD fallers and findings from a recently developed animal model support the hypothesis that falls result from interactions between loss of basal forebrain cholinergic projections to the cortex and striatal dopamine loss. Striatal dopamine loss produces inefficient, low-vigor gait, posture control, and movement. Cortical cholinergic deafferentation impairs a wide range of attentional processes, including monitoring of gait, posture and complex movements. Cholinergic cell loss reveals the full impact of striatal dopamine loss on motor performance, reflecting loss of compensatory attentional supervision of movement. Dysregulation of dorsomedial striatal circuitry is an essential, albeit not exclusive, mediator of falls in this dual-system model. Because cholinergic neuromodulatory activity influences cortical circuitry primarily via stimulation of α4β2* nicotinic acetylcholine receptors, and because agonists at these receptors are known to benefit attentional processes in animals and humans, treating PD fallers with such agonists, as an adjunct to dopaminergic treatment, is predicted to reduce falls. Falls are an informative behavioral endpoint to study attentional–motor integration by striatal circuitry. PMID:24805070

The Effects of Acute Dopamine Precursor Depletion on the Reinforcing Value of Exercise in Anorexia Nervosa.

PubMed

O'Hara, Caitlin B; Keyes, Alexandra; Renwick, Bethany; Leyton, Marco; Campbell, Iain C; Schmidt, Ulrike

2016-01-01

This study investigated whether dopaminergic systems are involved in the motivation to engage in behaviours associated with anorexia nervosa (AN), specifically, the drive to exercise. Women recovered from AN (AN REC, n = 17) and healthy controls (HC, n = 15) were recruited. The acute phenylalanine/tyrosine depletion (APTD) method was used to transiently decrease dopamine synthesis and transmission. The effect of dopamine precursor depletion on drive to exercise was measured using a progressive ratio (PR) exercise breakpoint task. Both groups worked for the opportunity to exercise, and, at baseline, PR breakpoint scores were higher in AN REC than HC. Compared to values on the experimental control session, APTD did not decrease PR breakpoint scores in AN REC, but significantly decreased scores in HC. These data show that women recovered from AN are more motivated to exercise than HC, although in both groups, activity is more reinforcing than inactivity. Importantly, decreasing dopamine does not reduce the motivation to exercise in people recovered from AN, but in contrast, does so in HC. It is proposed that in AN, drive to exercise develops into a behaviour that is largely independent of dopamine mediated reward processes and becomes dependent on cortico-striatal neurocircuitry that regulates automated, habit- or compulsive-like behaviours. These data strengthen the case for the involvement of reward, learning, habit, and dopaminergic systems in the aetiology of AN.

Reward modulation of cognitive function in adult attention-deficit/hyperactivity disorder: a pilot study on the role of striatal dopamine.

PubMed

Aarts, Esther; van Holstein, Mieke; Hoogman, Martine; Onnink, Marten; Kan, Cornelis; Franke, Barbara; Buitelaar, Jan; Cools, Roshan

2015-02-01

Attention-deficit/hyperactivity disorder (ADHD) is accompanied by impairments in cognitive control, such as task-switching deficits. We investigated whether such problems, and their remediation by medication, reflect abnormal reward motivation and associated striatal dopamine transmission in ADHD. We used functional genetic neuroimaging to assess the effects of dopaminergic medication and reward motivation on task-switching and striatal BOLD signal in 23 adults with ADHD, ON and OFF methylphenidate, and 26 healthy controls. Critically, we took into account interindividual variability in striatal dopamine by exploiting a common genetic polymorphism (3'-UTR VNTR) in the DAT1 gene coding for the dopamine transporter. The results showed a highly significant group by genotype interaction in the striatum. This was because a subgroup of patients with ADHD showed markedly exaggerated effects of reward on the striatal BOLD signal during task-switching when they were OFF their dopaminergic medication. Specifically, patients carrying the 9R allele showed a greater striatal signal than healthy controls carrying this allele, whereas no effect of diagnosis was observed in 10R homozygotes. Aberrant striatal responses were normalized when 9R-carrying patients with ADHD were ON medication. These pilot data indicate an important role for aberrant reward motivation, striatal dopamine and interindividual genetic differences in cognitive processes in adult ADHD.

Reward modulation of cognitive function in adult attention-deficit/hyperactivity disorder: a pilot study on the role of striatal dopamine

PubMed Central

Aarts, Esther; Hoogman, Martine; Onnink, Marten; Kan, Cornelis; Franke, Barbara; Buitelaar, Jan; Cools, Roshan

2015-01-01

Attention-deficit/hyperactivity disorder (ADHD) is accompanied by impairments in cognitive control, such as task-switching deficits. We investigated whether such problems, and their remediation by medication, reflect abnormal reward motivation and associated striatal dopamine transmission in ADHD. We used functional genetic neuroimaging to assess the effects of dopaminergic medication and reward motivation on task-switching and striatal BOLD signal in 23 adults with ADHD, ON and OFF methylphenidate, and 26 healthy controls. Critically, we took into account interindividual variability in striatal dopamine by exploiting a common genetic polymorphism (3′-UTR VNTR) in the DAT1 gene coding for the dopamine transporter. The results showed a highly significant group by genotype interaction in the striatum. This was because a subgroup of patients with ADHD showed markedly exaggerated effects of reward on the striatal BOLD signal during task-switching when they were OFF their dopaminergic medication. Specifically, patients carrying the 9R allele showed a greater striatal signal than healthy controls carrying this allele, whereas no effect of diagnosis was observed in 10R homozygotes. Aberrant striatal responses were normalized when 9R-carrying patients with ADHD were ON medication. These pilot data indicate an important role for aberrant reward motivation, striatal dopamine and interindividual genetic differences in cognitive processes in adult ADHD. PMID:25485641

The Effects of Acute Dopamine Precursor Depletion on the Reinforcing Value of Exercise in Anorexia Nervosa

PubMed Central

O’Hara, Caitlin B.; Keyes, Alexandra; Renwick, Bethany; Leyton, Marco; Campbell, Iain C.; Schmidt, Ulrike

2016-01-01

This study investigated whether dopaminergic systems are involved in the motivation to engage in behaviours associated with anorexia nervosa (AN), specifically, the drive to exercise. Women recovered from AN (AN REC, n = 17) and healthy controls (HC, n = 15) were recruited. The acute phenylalanine/tyrosine depletion (APTD) method was used to transiently decrease dopamine synthesis and transmission. The effect of dopamine precursor depletion on drive to exercise was measured using a progressive ratio (PR) exercise breakpoint task. Both groups worked for the opportunity to exercise, and, at baseline, PR breakpoint scores were higher in AN REC than HC. Compared to values on the experimental control session, APTD did not decrease PR breakpoint scores in AN REC, but significantly decreased scores in HC. These data show that women recovered from AN are more motivated to exercise than HC, although in both groups, activity is more reinforcing than inactivity. Importantly, decreasing dopamine does not reduce the motivation to exercise in people recovered from AN, but in contrast, does so in HC. It is proposed that in AN, drive to exercise develops into a behaviour that is largely independent of dopamine mediated reward processes and becomes dependent on cortico-striatal neurocircuitry that regulates automated, habit- or compulsive-like behaviours. These data strengthen the case for the involvement of reward, learning, habit, and dopaminergic systems in the aetiology of AN. PMID:26808920

Dynamic shaping of dopamine signals during probabilistic Pavlovian conditioning.

PubMed

Hart, Andrew S; Clark, Jeremy J; Phillips, Paul E M

2015-01-01

Cue- and reward-evoked phasic dopamine activity during Pavlovian and operant conditioning paradigms is well correlated with reward-prediction errors from formal reinforcement learning models, which feature teaching signals in the form of discrepancies between actual and expected reward outcomes. Additionally, in learning tasks where conditioned cues probabilistically predict rewards, dopamine neurons show sustained cue-evoked responses that are correlated with the variance of reward and are maximal to cues predicting rewards with a probability of 0.5. Therefore, it has been suggested that sustained dopamine activity after cue presentation encodes the uncertainty of impending reward delivery. In the current study we examined the acquisition and maintenance of these neural correlates using fast-scan cyclic voltammetry in rats implanted with carbon fiber electrodes in the nucleus accumbens core during probabilistic Pavlovian conditioning. The advantage of this technique is that we can sample from the same animal and recording location throughout learning with single trial resolution. We report that dopamine release in the nucleus accumbens core contains correlates of both expected value and variance. A quantitative analysis of these signals throughout learning, and during the ongoing updating process after learning in probabilistic conditions, demonstrates that these correlates are dynamically encoded during these phases. Peak CS-evoked responses are correlated with expected value and predominate during early learning while a variance-correlated sustained CS signal develops during the post-asymptotic updating phase. Copyright © 2014 Elsevier Inc. All rights reserved.

The potential role of dopamine D3 receptor neurotransmission in cognition

PubMed Central

Nakajima, Shinichiro; Gerretsen, Philip; Takeuchi, Hiroyoshi; Caravaggio, Fernando; Chow, Tiffany; Le Foll, Bernard; Mulsant, Benoit; Pollock, Bruce; Graff-Guerrero, Ariel

2013-01-01

Currently available treatments have limited pro-cognitive effects for neuropsychiatric disorders, such as schizophrenia, Parkinson’s disease and Alzheimer’s disease. The primary objective of this work is to review the literature on the role of dopamine D3 receptors in cognition, and propose dopamine D3 receptor antagonists as possible cognitive enhancers for neuropsychiatric disorders. A literature search was performed to identify animal and human studies on D3 receptors and cognition using PubMed, MEDLINE and EMBASE. The search terms included “dopamine D3 receptor” and “cognition”. The literature search identified 164 articles. The results revealed: (1) D3 receptors are associated with cognitive functioning in both healthy individuals and those with neuropsychiatric disorders; (2) D3 receptor blockade appears to enhance while D3 receptor agonism seems to impair cognitive function, including memory, attention, learning, processing speed, social recognition and executive function independent of age; and (3) D3 receptor antagonists may exert their pro-cognitive effect by enhancing the release of acetylcholine in the prefrontal cortex, disinhibiting the activity of dopamine neurons projecting to the nucleus accumbens or prefrontal cortex, or activating CREB signaling in the hippocampus. These findings suggest that D3 receptor blockade may enhance cognitive performance in healthy individuals and treat cognitive dysfunction in individuals with a neuropsychiatric disorder. Clinical trials are needed to confirm these effects. PMID:23791072

Key role of striatal cholinergic interneurons in processes leading to arrest of motor stereotypies.

PubMed

Aliane, Verena; Pérez, Sylvie; Bohren, Yohann; Deniau, Jean-Michel; Kemel, Marie-Louise

2011-01-01

Motor stereotypy is a key symptom of various disorders such as Tourette's syndrome and punding. Administration of nicotine or cholinesterase inhibitors is effective in treating some of these symptoms. However, the role of cholinergic transmission in motor stereotypy remains unknown. During strong cocaine-induced motor stereotypy, we showed earlier that increased dopamine release results in decreased acetylcholine release in the territory of the dorsal striatum related to the prefrontal cortex. Here, we investigated the role of striatal cholinergic transmission in the arrest of motor stereotypy. Analysis of N-methyl-d-aspartic acid-evoked release of dopamine and acetylcholine during declining intensity of motor stereotypy revealed a dissociation between dopamine and acetylcholine release. Whereas dopamine release remained increased, the inhibition of acetylcholine release decreased, mirroring the time course of motor stereotypy. Furthermore, pharmacological treatments restoring striatal acetylcholine release (raclopride, dopamine D2 antagonist; intraperitoneal or local injection in prefrontal territory of the dorsal striatum) rapidly stopped motor stereotypy. In contrast, pharmacological treatments that blocked the post-synaptic effects of acetylcholine (scopolamine, muscarinic antagonist; intraperitoneal or striatal local injection) or induced degeneration of cholinergic interneurons (AF64A, cholinergic toxin) in the prefrontal territory of the dorsal striatum robustly prolonged the duration of strong motor stereotypy. Thus, we propose that restoration of cholinergic transmission in the prefrontal territory of the dorsal striatum plays a key role in the arrest of motor stereotypy.

The pristine graphene produced by liquid exfoliation of graphite in mixed solvent and its application to determination of dopamine.

PubMed

Zhang, Juan; Xu, Liao; Zhou, Bo; Zhu, Yinyan; Jiang, Xiaoqing

2018-03-01

The pristine graphene can be easily prepared in isopropanol-water mixture with salts as assistant via liquid-phase exfoliation method. The concentration of graphene dispersion reaches as high as 0.565 mg/mL. The graphene film prepared by drop-casting method shows an excellent electrical conductivity (7.095 × 10 4  S/m). Furthermore, an electrochemical biosensor based on the pristine graphene shows high selectivity and sensitivity for the determination of dopamine. The linear detection range for dopamine is 2.5-1500 μM with detection limit of 1.5 μM. This method provides a potential process for preparing high-quality graphene ready-to-use in low-boiling point solvent. Copyright © 2017 Elsevier Inc. All rights reserved.

Phosphorylation mechanisms in dopamine transporter regulation.

PubMed

Foster, James D; Vaughan, Roxanne A

2017-10-01

The dopamine transporter (DAT) is a plasma membrane phosphoprotein that actively translocates extracellular dopamine (DA) into presynaptic neurons. The transporter is the primary mechanism for control of DA levels and subsequent neurotransmission, and is the target for abused and therapeutic drugs that exert their effects by suppressing reuptake. The transport capacity of DAT is acutely regulated by signaling systems and drug exposure, providing neurons the ability to fine-tune DA clearance in response to specific conditions. Kinase pathways play major roles in these mechanisms, and this review summarizes the current status of DAT phosphorylation characteristics and the evidence linking transporter phosphorylation to control of reuptake and other functions. Greater understanding of these processes may aid in elucidation of their possible contributions to DA disease states and suggest specific phosphorylation sites as targets for therapeutic manipulation of reuptake. Copyright © 2016. Published by Elsevier B.V.

Atomic force microscopy based nanoassay: a new method to study α-Synuclein-dopamine bioaffinity interactions

NASA Astrophysics Data System (ADS)

Corvaglia, Stefania; Sanavio, Barbara; Sorce, Barbara; Bosco, Alessandro; Sabella, Stefania; Pompa, Pierpaolo; Scoles, Giacinto; Casalis, Loredana

2015-03-01

Intrinsically Disordered Proteins (IDPs) are characterized by the lack of well-defined 3-D structure and show high conformational plasticity. For this reason, they are a strong challenge for the traditional characterization of structure, supramolecular assembly and biorecognition phenomena. We show here how the fine tuning of protein orientation on a surface turns useful in the reliable testing of biorecognition interactions of IDPs, in particular α-Synuclein. We exploited atomic force microscopy (AFM) for the selective, nanoscale confinement of α-Synuclein on gold to study the early stages of α-Synuclein aggregation and the effect of small molecules, like dopamine, on the aggregation process. Capitalizing on the high sensitivity of AFM topographic height measurements we determined, for the first time in the literature, the dissociation constant of dopamine- α-Synuclein adducts.

Atomic force microscopy based nanoassay: a new method to study α-Synuclein-dopamine bioaffinity interactions

NASA Astrophysics Data System (ADS)

Corvaglia, Stefania; Sanavio, Barbara; Hong Enriquez, Rolando P.; Sorce, Barbara; Bosco, Alessandro; Scaini, Denis; Sabella, Stefania; Pompa, Pier Paolo; Scoles, Giacinto; Casalis, Loredana

2014-06-01

Intrinsically Disordered Proteins (IDPs) are characterized by the lack of well-defined 3-D structure and show high conformational plasticity. For this reason, they are a strong challenge for the traditional characterization of structure, supramolecular assembly and biorecognition phenomena. We show here how the fine tuning of protein orientation on a surface turns useful in the reliable testing of biorecognition interactions of IDPs, in particular α-Synuclein. We exploited atomic force microscopy (AFM) for the selective, nanoscale confinement of α-Synuclein on gold to study the early stages of α-Synuclein aggregation and the effect of small molecules, like dopamine, on the aggregation process. Capitalizing on the high sensitivity of AFM topographic height measurements we determined, for the first time in the literature, the dissociation constant of dopamine-α-Synuclein adducts.

Sleep Deprivation During Early-Adult Development Results in Long-Lasting Learning Deficits in Adult Drosophila

PubMed Central

Seugnet, Laurent; Suzuki, Yasuko; Donlea, Jeff M.; Gottschalk, Laura; Shaw, Paul J.

2011-01-01

Study Objectives: Multiple lines of evidence indicate that sleep is important for the developing brain, although little is known about which cellular and molecular pathways are affected. Thus, the aim of this study was to determine whether the early adult life of Drosophila, which is associated with high amounts of sleep and critical periods of brain plasticity, could be used as a model to identify developmental processes that require sleep. Subjects: Wild type Canton-S Drosophila melanogaster. Design; Intervention: Flies were sleep deprived on their first full day of adult life and allowed to recover undisturbed for at least 3 days. The animals were then tested for short-term memory and response-inhibition using aversive phototaxis suppression (APS). Components of dopamine signaling were further evaluated using mRNA profiling, immunohistochemistry, and pharmacological treatments. Measurements and Results: Flies exposed to acute sleep deprivation on their first day of life showed impairments in short-term memory and response inhibition that persisted for at least 6 days. These impairments in adult performance were reversed by dopamine agonists, suggesting that the deficits were a consequence of reduced dopamine signaling. However, sleep deprivation did not impact dopaminergic neurons as measured by their number or by the levels of dopamine, pale (tyrosine hydroxylase), dopadecarboxylase, and the Dopamine transporter. However, dopamine pathways were impacted as measured by increased transcript levels of the dopamine receptors D2R and dDA1. Importantly, blocking signaling through the dDA1 receptor in animals that were sleep deprived during their critical developmental window prevented subsequent adult learning impairments. Conclusions: These data indicate that sleep plays an important and phylogenetically conserved role in the developing brain. Citation: Seugnet L; Suzuki Y; Donlea JM; Gottschalk L; Shaw PJ. Sleep deprivation during early-adult development results in long-lasting learning deficits in adult drosophila. SLEEP 2011;34(2):137-146. PMID:21286249

Biomimetic PDMS-hydroxyurethane terminated with catecholic moieties for chemical grafting on transition metal oxide-based surfaces

NASA Astrophysics Data System (ADS)

de Aguiar, Kelen R.; Rischka, Klaus; Gätjen, Linda; Noeske, Paul-Ludwig Michael; Cavalcanti, Welchy Leite; Rodrigues-Filho, Ubirajara P.

2018-01-01

The aim of this work was to synthesize a non-isocyanate poly(dimethylsiloxane) hydroxyurethane with biomimetic terminal catechol moieties, as a candidate for inorganic and metallic surface modification. Such surface modifier is capable to strongly attach onto metallic and inorganic substrates forming layers and, in addition, providing water-repellent surfaces. The non-isocyanate route is based on carbon dioxide cycloaddition into bis-epoxide, resulting in a precursor bis(cyclic carbonate)-polydimethylsiloxane (CCPDMS), thus fully replacing isocyanate in the manufacture process. A biomimetic approach was chosen with the molecular composition being inspired by terminal peptides present in adhesive proteins of mussels, like Mefp (Mytilus edulis foot protein), which bear catechol moieties and are strong adhesives even under natural and saline water. The catechol terminal groups were grafted by aminolysis reaction into a polydimethylsiloxane backbone. The product, PDMSUr-Dopamine, presented high affinity towards inhomogeneous alloy surfaces terminated by native oxide layers as demonstrated by quartz crystal microbalance (QCM-D), as well as stability against desorption by rinsing with ethanol. As revealed by QCM-D, X-ray photoelectron spectroscopy (XPS) and computational studies, the thickness and composition of the resulting nanolayers indicated an attachment of PDMSUr-Dopamine molecules to the substrate through both terminal catechol groups, with the adsorbate exposing the hydrophobic PDMS backbone. This hypothesis was investigated by classical molecular dynamic simulation (MD) of pure PDMSUr-Dopamine molecules on SiO2 surfaces. The computationally obtained PDMSUr-Dopamine assembly is in agreement with the conclusions from the experiments regarding the conformation of PDMSUr-Dopamine towards the surface. The tendency of the terminal catechol groups to approach the surface is in agreement with proposed model for the attachment PDMSUr-Dopamine. Remarkably, the versatile PDMSUr-Dopamine modifier facilitates such functionalization for various substrates such as titanium alloy, steel and ceramic surfaces.

Acute fasting increases somatodendritic dopamine release in the ventral tegmental area

PubMed Central

2015-01-01

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. PMID:26084913

Decoding the Dopamine Signal in Macaque Prefrontal Cortex: A Simulation Study Using the Cx3Dp Simulator

PubMed Central

Spühler, Isabelle Ayumi; Hauri, Andreas

2013-01-01

Dopamine transmission in the prefrontal cortex plays an important role in reward based learning, working memory and attention. Dopamine is thought to be released non-synaptically into the extracellular space and to reach distant receptors through diffusion. This simulation study examines how the dopamine signal might be decoded by the recipient neuron. The simulation was based on parameters from the literature and on our own quantified, structural data from macaque prefrontal area 10. The change in extracellular dopamine concentration was estimated at different distances from release sites and related to the affinity of the dopamine receptors. Due to the sparse and random distribution of release sites, a transient heterogeneous pattern of dopamine concentration emerges. Our simulation predicts, however, that at any point in the simulation volume there is sufficient dopamine to bind and activate high-affinity dopamine receptors. We propose that dopamine is broadcast to its distant receptors and any change from the local baseline concentration might be decoded by a transient change in the binding probability of dopamine receptors. Dopamine could thus provide a graduated ‘teaching’ signal to reinforce concurrently active synapses and cell assemblies. In conditions of highly reduced or highly elevated dopamine levels the simulations predict that relative changes in the dopamine signal can no longer be decoded, which might explain why cognitive deficits are observed in patients with Parkinson’s disease, or induced through drugs blocking dopamine reuptake. PMID:23951205

Glutamate and Opioid Antagonists Modulate Dopamine Levels Evoked by Innately Attractive Male Chemosignals in the Nucleus Accumbens of Female Rats

PubMed Central

Sánchez-Catalán, María-José; Orrico, Alejandro; Hipólito, Lucía; Zornoza, Teodoro; Polache, Ana; Lanuza, Enrique; Martínez-García, Fernando; Granero, Luis; Agustín-Pavón, Carmen

2017-01-01

Sexual chemosignals detected by vomeronasal and olfactory systems mediate intersexual attraction in rodents, and act as a natural reinforcer to them. The mesolimbic pathway processes natural rewards, and the nucleus accumbens receives olfactory information via glutamatergic projections from the amygdala. Thus, the aim of this study was to investigate the involvement of the mesolimbic pathway in the attraction toward sexual chemosignals. Our data show that female rats with no previous experience with males or their chemosignals display an innate preference for male-soiled bedding. Focal administration of the opioid antagonist β-funaltrexamine into the posterior ventral tegmental area does not affect preference for male chemosignals. Nevertheless, exposure to male-soiled bedding elicits an increase in dopamine efflux in the nucleus accumbens shell and core, measured by microdialysis. Infusion of the opioid antagonist naltrexone in the accumbens core does not significantly affect dopamine efflux during exposure to male chemosignals, although it enhances dopamine levels 40 min after withdrawal of the stimuli. By contrast, infusion of the glutamate antagonist kynurenic acid in the accumbens shell inhibits the release of dopamine and reduces the time that females spend investigating male-soiled bedding. These data are in agreement with previous reports in male rats showing that exposure to opposite-sex odors elicits dopamine release in the accumbens, and with data in female mice showing that the behavioral preference for male chemosignals is not affected by opioidergic antagonists. We hypothesize that glutamatergic projections from the amygdala into the accumbens might be important to modulate the neurochemical and behavioral responses elicited by sexual chemosignals in rats. PMID:28280461

Distinct Contributions of Dopamine in the Dorsolateral Striatum and Nucleus Accumbens Shell to the Reinforcing Properties of Cocaine

PubMed Central

Veeneman, Maartje M J; Broekhoven, Mark H; Damsteegt, Ruth; Vanderschuren, Louk J M J

2012-01-01

Dopaminergic neurotransmission in the dorsal and ventral striatum is thought to be involved in distinct aspects of cocaine addiction. Ventral striatal dopamine mediates the acute reinforcing properties of cocaine, whereas dopamine in the dorsolateral striatum (DLS) is thought to become involved in later stages of the addiction process to mediate well-established cue-controlled drug seeking. However, it is unclear whether the DLS also has a role in the reinforcing properties of cocaine itself. Therefore, we systematically investigated the involvement of dopamine in dorsal and ventral striatal regions in cocaine self-administration, using various schedules of reinforcement in animals with limited drug taking experience. Intra-DLS infusion of the dopamine receptor antagonist α-flupenthixol did not affect the acquisition of cocaine self-administration, increased cocaine self-administration under a fixed ratio-1 (FR-1) schedule of reinforcement, caused a rightward and downward shift of the dose–response curve of cocaine under an FR-1 schedule of reinforcement and decreased responding for cocaine under a progressive ratio (PR) schedule of reinforcement. Infusion of α-flupenthixol into the ventral nucleus accumbens (NAcc) shell inhibited the acquisition of cocaine self-administration, reduced responding for the drug under FR-1 and PR schedules of reinforcement, and caused a downward shift of the dose–response curve of cocaine self-administration under an FR-1 schedule of reinforcement. These data show that dopamine in both the DLS and NAcc shell is involved in cocaine reinforcement. We suggest that the DLS and the NAcc shell mediate somewhat distinct facets of the reinforcing properties of cocaine, related to its rewarding and motivational aspects, respectively. PMID:21918505

Wheel running alters patterns of uncontrollable stress-induced cfos mRNA expression in rat dorsal striatum direct and indirect pathways: a possible role for plasticity in adenosine receptors

PubMed Central

Clark, Peter J.; Ghasem, Parsa R.; Mika, Agnieszka; Day, Heidi E.; Herrera, Jonathan J.; Greenwood, Benjamin N.; Fleshner, Monika

2014-01-01

Emerging evidence indicates that adenosine is a major regulator of striatum activity, in part, through the antagonistic modulation of dopaminergic function. Exercise can influence adenosine and dopamine activity, which may subsequently promote plasticity in striatum adenosine and dopamine systems. Such changes could alter activity of medium spiny neurons and impact striatum function. The purpose of this study was two-fold. The first was to characterize the effect of long-term wheel running on adenosine 1 (A1R), adenosine 2A (A2AR), dopamine 1 (D1R), and dopamine 2 (D2R) receptor mRNA expression in adult rat dorsal and ventral striatum structures using in situ hybridization. The second was to determine if changes to adenosine and dopamine receptor mRNA from running are associated with altered cfos mRNA induction in dynorphin- (direct pathway) and enkephalin- (indirect pathway) expressing neurons of the dorsal striatum following stress exposure. We report that chronic running, as well as acute uncontrollable stress, reduced A1R and A2AR mRNA levels in the dorsal and ventral striatum. Running also modestly elevated D2R mRNA levels in striatum regions. Finally, stress-induced cfos was potentiated in dynorphin and attenuated in enkephalin expressing neurons of running rats. These data suggest striatum adenosine and dopamine systems are targets for neuroplasticity from exercise, which may contribute to changes in direct and indirect pathway activity. These findings may have implications for striatum mediated motor and cognitive processes, as well as exercise facilitated stress-resistance. PMID:25017571

Glutamate and Opioid Antagonists Modulate Dopamine Levels Evoked by Innately Attractive Male Chemosignals in the Nucleus Accumbens of Female Rats.

PubMed

Sánchez-Catalán, María-José; Orrico, Alejandro; Hipólito, Lucía; Zornoza, Teodoro; Polache, Ana; Lanuza, Enrique; Martínez-García, Fernando; Granero, Luis; Agustín-Pavón, Carmen

2017-01-01

Sexual chemosignals detected by vomeronasal and olfactory systems mediate intersexual attraction in rodents, and act as a natural reinforcer to them. The mesolimbic pathway processes natural rewards, and the nucleus accumbens receives olfactory information via glutamatergic projections from the amygdala. Thus, the aim of this study was to investigate the involvement of the mesolimbic pathway in the attraction toward sexual chemosignals. Our data show that female rats with no previous experience with males or their chemosignals display an innate preference for male-soiled bedding. Focal administration of the opioid antagonist β-funaltrexamine into the posterior ventral tegmental area does not affect preference for male chemosignals. Nevertheless, exposure to male-soiled bedding elicits an increase in dopamine efflux in the nucleus accumbens shell and core, measured by microdialysis. Infusion of the opioid antagonist naltrexone in the accumbens core does not significantly affect dopamine efflux during exposure to male chemosignals, although it enhances dopamine levels 40 min after withdrawal of the stimuli. By contrast, infusion of the glutamate antagonist kynurenic acid in the accumbens shell inhibits the release of dopamine and reduces the time that females spend investigating male-soiled bedding. These data are in agreement with previous reports in male rats showing that exposure to opposite-sex odors elicits dopamine release in the accumbens, and with data in female mice showing that the behavioral preference for male chemosignals is not affected by opioidergic antagonists. We hypothesize that glutamatergic projections from the amygdala into the accumbens might be important to modulate the neurochemical and behavioral responses elicited by sexual chemosignals in rats.

Dopamine D(1) receptor deletion strongly reduces neurotoxic effects of methamphetamine.

PubMed

Ares-Santos, S; Granado, N; Oliva, I; O'Shea, E; Martin, E D; Colado, M I; Moratalla, R

2012-02-01

Methamphetamine (METH) is a potent, highly addictive psychostimulant consumed worldwide. In humans and experimental animals, repeated exposure to this drug induces persistent neurodegenerative changes. Damage occurs primarily to dopaminergic neurons, accompanied by gliosis. The toxic effects of METH involve excessive dopamine (DA) release, thus DA receptors are highly likely to play a role in this process. To define the role of D(1) receptors in the neurotoxic effects of METH we used D(1) receptor knock-out mice (D(1)R(-/-)) and their WT littermates. Inactivation of D(1)R prevented METH-induced dopamine fibre loss and hyperthermia, and increases in gliosis and pro-inflammatory molecules such as iNOS in the striatum. In addition, D(1)R inactivation prevented METH-induced loss of dopaminergic neurons in the substantia nigra. To explore the relationship between hyperthermia and neurotoxicity, METH was given at high ambient temperature (29 °C). In this condition, D(1)R(-/-) mice developed hyperthermia following drug delivery and the neuroprotection provided by D(1)R inactivation at 23 °C was no longer observed. However, reserpine, which empties vesicular dopamine stores, blocked hyperthermia and strongly potentiated dopamine toxicity in D(1)R(-/-) mice, suggesting that the protection afforded by D(1)R inactivation is due to both hypothermia and higher stored vesicular dopamine. Moreover, electrical stimulation evoked higher DA overflow in D(1)R(-/-) mice as demonstrated by fast scan cyclic voltammetry despite their lower basal DA content, suggesting higher vesicular DA content in D(1)R(-/-) than in WT mice. Altogether, these results indicate that the D(1)R plays a significant role in METH-induced neurotoxicity by mediating drug-induced hyperthermia and increasing the releasable cytosolic DA pool. Copyright © 2011. Published by Elsevier Inc.

The roles of dopamine and serotonin in decision making: evidence from pharmacological experiments in humans.

PubMed

Rogers, Robert D

2011-01-01

Neurophysiological experiments in primates, alongside neuropsychological and functional magnetic resonance investigations in humans, have significantly enhanced our understanding of the neural architecture of decision making. In this review, I consider the more limited database of experiments that have investigated how dopamine and serotonin activity influences the choices of human adults. These include those experiments that have involved the administration of drugs to healthy controls, experiments that have tested genotypic influences upon dopamine and serotonin function, and, finally, some of those experiments that have examined the effects of drugs on the decision making of clinical samples. Pharmacological experiments in humans are few in number and face considerable methodological challenges in terms of drug specificity, uncertainties about pre- vs post-synaptic modes of action, and interactions with baseline cognitive performance. However, the available data are broadly consistent with current computational models of dopamine function in decision making and highlight the dissociable roles of dopamine receptor systems in the learning about outcomes that underpins value-based decision making. Moreover, genotypic influences on (interacting) prefrontal and striatal dopamine activity are associated with changes in choice behavior that might be relevant to understanding exploratory behaviors and vulnerability to addictive disorders. Manipulations of serotonin in laboratory tests of decision making in human participants have provided less consistent results, but the information gathered to date indicates a role for serotonin in learning about bad decision outcomes, non-normative aspects of risk-seeking behavior, and social choices involving affiliation and notions of fairness. Finally, I suggest that the role played by serotonin in the regulation of cognitive biases, and representation of context in learning, point toward a role in the cortically mediated cognitive appraisal of reinforcers when selecting between actions, potentially accounting for its influence upon the processing salient aversive outcomes and social choice.

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

PubMed Central

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

2014-01-01

Dopamine D1 and D2 receptor immunohistochemistry and Golgi techniques were used to study the structure of the adult rat arcuate-median eminence complex, and determine the distribution of the dopamine D1 and D2 receptor immunoreactivities therein, particularly in relation to the tubero-infundibular dopamine neurons. Punctate dopamine D1 and D2 receptor immunoreactivities, likely located on nerve terminals, were enriched in the lateral palisade zone built up of nerve terminals, while the densities were low to modest in the medial palisade zone. A codistribution of dopamine D1 receptor or dopamine D2 receptor immunoreactive puncta with tyrosine hydroxylase immunoreactive nerve terminals was demonstrated in the external layer. Dopamine D1 receptor but not dopamine D2 receptor immnunoreactivites nerve cell bodies were found in the ventromedial part of the arcuate nucleus and in the lateral part of the internal layer of the median eminence forming a continuous cell mass presumably representing neuropeptide Y immunoreactive nerve cell bodies. The major arcuate dopamine/ tyrosine hydroxylase nerve cell group was found in the dorsomedial part. A large number of tyrosine hydroxylase immunoreactive nerve cell bodies in this region demonstrated punctate dopamine D1 receptor immunoreactivity but only a few presented dopamine D2 receptor immunoreactivity which were mainly found in a substantial number of tyrosine hydroxylase cell bodies of the ventral periventricular hypothalamic nucleus, also belonging to the tuberoinfundibular dopamine neurons. Structural evidence for projections of the arcuate nerve cells into the median eminence was also obtained. Distal axons formed horizontal axons in the internal layer issuing a variable number of collaterals classified into single or multiple strands located in the external layer increasing our understanding of the dopamine nerve terminal networks in this region. Dopamine D1 and D2 receptors may therefore directly and differentially modulate the activity and/or Dopamine synthesis of substantial numbers of tubero-infundibular dopamine neurons at the somatic and terminal level. The immunohistochemical work also gives support to the view that dopamine D1 receptors and/or dopamine D2 receptors in the lateral palisade zone by mediating dopamine volume transmission may contribute to the inhibition of luteinizing hormone releasing hormone release from nerve terminals in this region. PMID:25308843

Dopamine D1 and D2 receptor immunoreactivities in the arcuate-median eminence complex and their link to the tubero-infundibular dopamine neurons.

PubMed

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

2014-07-18

Dopamine D1 and D2 receptor immunohistochemistry and Golgi techniques were used to study the structure of the adult rat arcuate-median eminence complex, and determine the distribution of the dopamine D1 and D2 receptor immunoreactivities therein, particularly in relation to the tubero-infundibular dopamine neurons. Punctate dopamine D1 and D2 receptor immunoreactivities, likely located on nerve terminals, were enriched in the lateral palisade zone built up of nerve terminals, while the densities were low to modest in the medial palisade zone. A codistribution of dopamine D1 receptor or dopamine D2 receptor immunoreactive puncta with tyrosine hydroxylase immunoreactive nerve terminals was demonstrated in the external layer. Dopamine D1 receptor but not dopamine D2 receptor immnunoreactivites nerve cell bodies were found in the ventromedial part of the arcuate nucleus and in the lateral part of the internal layer of the median eminence forming a continuous cell mass presumably representing neuropeptide Y immunoreactive nerve cell bodies. The major arcuate dopamine/ tyrosine hydroxylase nerve cell group was found in the dorsomedial part. A large number of tyrosine hydroxylase immunoreactive nerve cell bodies in this region demonstrated punctate dopamine D1 receptor immunoreactivity but only a few presented dopamine D2 receptor immunoreactivity which were mainly found in a substantial number of tyrosine hydroxylase cell bodies of the ventral periventricular hypothalamic nucleus, also belonging to the tubero-infundibular dopamine neurons. Structural evidence for projections of the arcuate nerve cells into the median eminence was also obtained. Distal axons formed horizontal axons in the internal layer issuing a variable number of collaterals classified into single or multiple strands located in the external layer increasing our understanding of the dopamine nerve terminal networks in this region.  Dopamine D1 and D2 receptors may therefore directly and differentially modulate the activity and /or Dopamine synthesis of substantial numbers of tubero-infundibular dopamine neurons at the somatic and terminal level. The immunohistochemical work also gives support to the view that dopamine D1 receptors and/or dopamine D2 receptors in the lateral palisade zone by mediating dopamine volume transmission may contribute to the inhibition of luteinizing hormone releasing hormone release from nerve terminals in this region.

Cholinergic Interneurons Underlie Spontaneous Dopamine Release in Nucleus Accumbens

PubMed Central

2017-01-01

The release of dopamine from terminals in the NAc is regulated by a number of factors, including voltage-gated ion channels, D2-autoreceptors, and nAChRs. Cholinergic interneurons (CINs) drive dopamine release through activation of nAChRs on dopamine terminals. Using cyclic voltammetry in mouse brain slices, nAChR-dependent spontaneous dopamine transients and the mechanisms underlying the origin were examined in the NAc. Spontaneous events were infrequent (0.3 per minute), but the rate and amplitude were increased after blocking Kv channels with 4-aminopyridine. Although the firing frequency of CINs was increased by blocking glutamate reuptake with TBOA and the Sk blocker apamin, only 4-aminopyridine increased the frequency of dopamine transients. In contrast, inhibition of CIN firing with the μ/δ selective opioid [Met5]enkephalin (1 μm) decreased spontaneous dopamine transients. Cocaine increased the rate and amplitude of dopamine transients, suggesting that the activity of the dopamine transporter limits the detection of these events. In the presence of cocaine, the rate of spontaneous dopamine transients was further increased after blocking D2-autoreceptors. Blockade of muscarinic receptors had no effect on evoked dopamine release, suggesting that feedback inhibition of acetylcholine release was not involved. Thus, although spontaneous dopamine transients are reliant on nAChRs, the frequency was not strictly governed by the activity of CINs. The increase in frequency of spontaneous dopamine transients induced by cocaine was not due to an increase in cholinergic tone and is likely a product of an increase in detection resulting from decreased dopamine reuptake. SIGNIFICANCE STATEMENT The actions of dopamine in the NAc are thought to be responsible for endogenous reward and the reinforcing properties of drugs of abuse, such as psychostimulants. The present work examines the mechanisms underlying nAChR-induced spontaneous dopamine release. This study demonstrates that spontaneous dopamine release is (1) dependent of the activation of nicotinic receptors, (2) independent on the spontaneous activity of cholinergic interneurons, and (3) that cocaine increased the detection of dopamine transients by prolonging the presence and increasing the diffusion of dopamine in the extracellular space. The release of acetylcholine is therefore responsible for spontaneous dopamine transients, and cocaine augments dopamine tone without altering activity of cholinergic interneurons. PMID:28115487

Nuclear medicine and imaging research (quantitative studies in radiopharmaceutical science)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooper, M.; Beck, R.N.

1992-06-01

This report describes three studies aimed at using radiolabeled pharmaceuticals to explore brain function and anatomy. The first section describes the chemical preparation of (F18)fluorinated benzamides (dopamine D-2 receptor tracers), (F18)fluorinated benzazepines (dopamine D-1 receptor tracers), and tissue distribution of (F18)-fluoxetine (serotonin reuptake site tracer). The second section relates pharmacological and behavioral studies of amphetamines. The third section reports on progress made with processing of brain images from CT, MRI and PET/SPECT with regards to brain metabolism of glucose during mental tasks.

Opposite initialization to novel cues in dopamine signaling in ventral and posterior striatum in mice

PubMed Central

Menegas, William; Babayan, Benedicte M; Uchida, Naoshige; Watabe-Uchida, Mitsuko

2017-01-01

Dopamine neurons are thought to encode novelty in addition to reward prediction error (the discrepancy between actual and predicted values). In this study, we compared dopamine activity across the striatum using fiber fluorometry in mice. During classical conditioning, we observed opposite dynamics in dopamine axon signals in the ventral striatum (‘VS dopamine’) and the posterior tail of the striatum (‘TS dopamine’). TS dopamine showed strong excitation to novel cues, whereas VS dopamine showed no responses to novel cues until they had been paired with a reward. TS dopamine cue responses decreased over time, depending on what the cue predicted. Additionally, TS dopamine showed excitation to several types of stimuli including rewarding, aversive, and neutral stimuli whereas VS dopamine showed excitation only to reward or reward-predicting cues. Together, these results demonstrate that dopamine novelty signals are localized in TS along with general salience signals, while VS dopamine reliably encodes reward prediction error. DOI: http://dx.doi.org/10.7554/eLife.21886.001 PMID:28054919

Serotoninergic and dopaminergic modulation of cortico-striatal circuit in executive and attention deficits induced by NMDA receptor hypofunction in the 5-choice serial reaction time task

PubMed Central

Carli, Mirjana; Invernizzi, Roberto W.

2014-01-01

Executive functions are an emerging propriety of neuronal processing in circuits encompassing frontal cortex and other cortical and subcortical brain regions such as basal ganglia and thalamus. Glutamate serves as the major neurotrasmitter in these circuits where glutamate receptors of NMDA type play key role. Serotonin and dopamine afferents are in position to modulate intrinsic glutamate neurotransmission along these circuits and in turn to optimize circuit performance for specific aspects of executive control over behavior. In this review, we focus on the 5-choice serial reaction time task which is able to provide various measures of attention and executive control over performance in rodents and the ability of prefrontocortical and striatal serotonin 5-HT1A, 5-HT2A, and 5-HT2C as well as dopamine D1- and D2-like receptors to modulate different aspects of executive and attention disturbances induced by NMDA receptor hypofunction in the prefrontal cortex. These behavioral studies are integrated with findings from microdialysis studies. These studies illustrate the control of attention selectivity by serotonin 5-HT1A, 5-HT2A, 5-HT2C, and dopamine D1- but not D2-like receptors and a distinct contribution of these cortical and striatal serotonin and dopamine receptors to the control of different aspects of executive control over performance such as impulsivity and compulsivity. An association between NMDA antagonist-induced increase in glutamate release in the prefrontal cortex and attention is suggested. Collectively, this review highlights the functional interaction of serotonin and dopamine with NMDA dependent glutamate neurotransmission in the cortico-striatal circuitry for specific cognitive demands and may shed some light on how dysregulation of neuronal processing in these circuits may be implicated in specific neuropsychiatric disorders. PMID:24966814

D1- and D2-like dopamine receptors in the CA1 region of the hippocampus are involved in the acquisition and reinstatement of morphine-induced conditioned place preference.

PubMed

Assar, Nasim; Mahmoudi, Dorna; Farhoudian, Ali; Farhadi, Mohammad Hasan; Fatahi, Zahra; Haghparast, Abbas

2016-10-01

The hippocampus plays a vital role in processing contextual memories and reward related learning tasks, such as conditioned place preference (CPP). Among the neurotransmitters in the hippocampus, dopamine is deeply involved in reward-related processes. This study assessed the role of D1- and D2-like dopamine receptors within the CA1 region of the hippocampus in the acquisition and reinstatement of morphine-CPP. To investigate the role of D1 and D2 receptors in morphine acquisition, the animals received different doses of D1- and/or D2-like dopamine receptor antagonists (SCH23390 and sulpiride, respectively) into the CA1, 5min before the administration of morphine (5mg/kg, subcutaneously) during a 3-days conditioning phase. To evaluate the involvement of these receptors in morphine reinstatement, the animals received different doses of SCH23390 or sulpiride (after extinction period) 5min before the administration of a low dose of morphine (1mg/kg) in order to reinstate the extinguished morphine-CPP. Conditioning scores were recorded by Ethovision software. The results of this study showed that the administration of SCH23390 or sulpiride, significantly decreased the acquisition of morphine-CPP. Besides, the injection of these antagonists before the administration of a priming dose of morphine, following the extinction period, decreased the reinstatement of morphine-CPP in sacrificed rats. However, the effect of sulpiride on the acquisition and reinstatement of morphine-CPP was more significant than that of SCH23390. These findings suggested that D1- and D2-like dopamine receptors in the CA1 are involved in the acquisition and reinstatement of morphine-CPP, and antagonism of these receptors can reduce the rewarding properties of morphine. Copyright © 2016 Elsevier B.V. All rights reserved.

Chemical synthesis and characterization of hollow dopamine coated, pentagonal and flower shaped magnetic iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Riasat, Rabia; Kaynat, Sumbal

2018-04-01

Iron oxide nanoparticles have gained attention recently in the field of nanoscience and technology due to their unique physicochemical properties. We hereby chemically synthesized novel pentagonal flower shaped iron oxide nanoparticles by thermal decomposition of iron penta-carbonyl in a two way annealing process. Controlled oxidation by acid etching was performed for these nanoparticles. At first 13 nm core shell nanoparticles of iron oxide (Fe/Fe3O4) were synthesized at 120°C annealing temperature that act as template material. The core shell nanoparticles then converted into porous hollow core shell nanoparticles (PH Fe/ Fe3O4) in a two way annealing process of heating, first at 100°C then at 250°C and heating rate of 5°C was kept constant throughout the reaction time. X-Ray diffraction (XRD) was done for the phase confirmation of as synthesized nanoparticles. Transmission electron microscopy (TEM) and higher resolution transmission electron microscopy (HRTEM) clearly shows the flower like nanoparticles that are approx. 16 nm-18 nm in size having the 4-5 nm core of Fe and 1-2 nm of the pores in the shell while the cavity between the shell and core is about 2 nm and the shell is 4-5 nm in diameter according to the TEM micrographs. The as prepared nanoparticles were then surface functionalized by dopamine polymer to make them water dispersible. Fourier transform Infrared spectroscopy confirmed the dopamine coating on the nanoparticles and the magnetic saturation of 38 emu/g of nanoparticles was analyzed by vibrating sample magnetometer (VSM). Magnetic saturation persists in the dopamine coated nanoparticles. These nanoparticles were surface functionalized with dopamine and show dispersity in the aqueous media and can further be exploited in many nano-biotechnological applications including target specific therapeutic applications for several diseases.

Imbalanced decision hierarchy in addicts emerging from drug-hijacked dopamine spiraling circuit.

PubMed

Keramati, Mehdi; Gutkin, Boris

2013-01-01

Despite explicitly wanting to quit, long-term addicts find themselves powerless to resist drugs, despite knowing that drug-taking may be a harmful course of action. Such inconsistency between the explicit knowledge of negative consequences and the compulsive behavioral patterns represents a cognitive/behavioral conflict that is a central characteristic of addiction. Neurobiologically, differential cue-induced activity in distinct striatal subregions, as well as the dopamine connectivity spiraling from ventral striatal regions to the dorsal regions, play critical roles in compulsive drug seeking. However, the functional mechanism that integrates these neuropharmacological observations with the above-mentioned cognitive/behavioral conflict is unknown. Here we provide a formal computational explanation for the drug-induced cognitive inconsistency that is apparent in the addicts' "self-described mistake". We show that addictive drugs gradually produce a motivational bias toward drug-seeking at low-level habitual decision processes, despite the low abstract cognitive valuation of this behavior. This pathology emerges within the hierarchical reinforcement learning framework when chronic exposure to the drug pharmacologically produces pathologicaly persistent phasic dopamine signals. Thereby the drug hijacks the dopaminergic spirals that cascade the reinforcement signals down the ventro-dorsal cortico-striatal hierarchy. Neurobiologically, our theory accounts for rapid development of drug cue-elicited dopamine efflux in the ventral striatum and a delayed response in the dorsal striatum. Our theory also shows how this response pattern depends critically on the dopamine spiraling circuitry. Behaviorally, our framework explains gradual insensitivity of drug-seeking to drug-associated punishments, the blocking phenomenon for drug outcomes, and the persistent preference for drugs over natural rewards by addicts. The model suggests testable predictions and beyond that, sets the stage for a view of addiction as a pathology of hierarchical decision-making processes. This view is complementary to the traditional interpretation of addiction as interaction between habitual and goal-directed decision systems.

Ventral tegmental ionotropic glutamate receptor stimulation of nucleus accumbens tonic dopamine efflux blunts hindbrain-evoked phasic neurotransmission: implications for dopamine dysregulation disorders.

PubMed

Tye, S J; Miller, A D; Blaha, C D

2013-11-12

Activation of glutamate receptors within the ventral tegmental area (VTA) stimulates extrasynaptic (basal) dopamine release in terminal regions, including the nucleus accumbens (NAc). Hindbrain inputs from the laterodorsal tegmental nucleus (LDT) are critical for elicitation of phasic VTA dopamine cell activity and consequent transient dopamine release. This study investigated the role of VTA ionotropic glutamate receptor (iGluR) stimulation on both basal and LDT electrical stimulation-evoked dopamine efflux in the NAc using in vivo chronoamperometry and fixed potential amperometry in combination with stearate-graphite paste and carbon fiber electrodes, respectively. Intra-VTA infusion of the iGluR agonists (±)-α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA; 1 μg/μl) or N-methyl-d-aspartic acid (NMDA; 2 μg/μl) enhanced basal NAc dopamine efflux. This iGluR-mediated potentiation of basal dopamine efflux was paralleled by an attenuation of LDT-evoked transient NAc dopamine efflux, suggesting that excitation of basal activity effectively inhibited the capacity of hindbrain afferents to elicit transient dopamine efflux. In line with this, post-NMDA infusion of the dopamine D2 autoreceptor (D2R) agonist quinpirole (1 μg/μl; intra-VTA) partially recovered NMDA-mediated attenuation of LDT-evoked NAc dopamine, while concurrently attenuating NMDA-mediated potentiation of basal dopamine efflux. Post-NMDA infusion of quinpirole (1 μg/μl) alone attenuated basal and LDT-evoked dopamine efflux. Taken together, these data reveal that hyperstimulation of basal dopamine transmission can stunt hindbrain burst-like stimulation-evoked dopamine efflux. Inhibitory autoreceptor mechanisms within the VTA help to partially recover the magnitude of phasic dopamine efflux, highlighting the importance of both iGluRs and D2 autoreceptors in maintaining the functional balance of tonic and phasic dopamine neurotransmission. Dysregulation of this balance may have important implications for disorders of dopamine dysregulation such as attention deficit hyperactivity disorder. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

Lack of dopamine supersensitivity in rats after chronic administration of blonanserin: Comparison with haloperidol.

PubMed

Hashimoto, Takashi; Baba, Satoko; Ikeda, Hiroko; Oda, Yasunori; Hashimoto, Kenji; Shimizu, Isao

2018-07-05

Long-term treatment with antipsychotic drugs in patients with schizophrenia can lead to dopamine supersensitivity psychosis. It is reported that repeated administration of haloperidol caused dopamine supersensitivity in rats. Blonanserin is an atypical antipsychotic drug with high affinity for dopamine D 2 , D 3 and serotonin 2A receptors. In this study, we investigated whether chronic administration of blonanserin leads to dopamine supersensitivity. Following oral treatment with blonanserin (0.78 mg/kg) or haloperidol (1.1 mg/kg) twice daily for 28 days, the dopamine D 2 agonist quinpirole-induced hyperlocomotion test and a dopamine D 2 receptor binding assay were conducted. We found that haloperidol significantly enhanced both quinpirole-induced hyperlocomotion and striatal dopamine D 2 receptor density in rats. On the other hand, repeated administration of blonanserin had no effect on either locomotor activity or striatal dopamine D 2 receptor density. Further, our results show that mRNA levels of dopamine D 2 and D 3 receptors in several brain regions were unaffected by repeated administration of both agents. In addition, we examined the effect of the dopamine D 3 receptor antagonist PG-01037 on development of dopamine supersensitivity induced by chronic haloperidol treatment and showed that PG-01037 prevents the development of supersensitivity to quinpirole in chronic haloperidol-treated rats. Given the higher affinity of blonanserin at dopamine D 3 receptors than haloperidol, antagonism of blonanserin at dopamine D 3 receptors may play a role in lack of dopamine supersensitivity after chronic administration. The present findings suggest long-term treatment with antipsychotic dose of blonanserin may be unlikely to lead to dopamine supersensitivity. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

PET evaluation of the dopamine system of the human brain

DOE Office of Scientific and Technical Information (OSTI.GOV)

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,more » 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.« less

Adenosine transiently modulates stimulated dopamine release in the caudate putamen via A1 receptors

PubMed Central

Ross, Ashley E.; Venton, B. Jill

2014-01-01

Adenosine modulates dopamine in the brain via A1 and A2A receptors, but that modulation has only been characterized on a slow time scale. Recent studies have characterized a rapid signaling mode of adenosine that suggests a possible rapid modulatory role. Here, fast-scan cyclic voltammetry was used to characterize the extent to which transient adenosine changes modulate stimulated dopamine release (5 pulses at 60 Hz) in rat caudate putamen brain slices. Exogenous adenosine was applied and dopamine concentration monitored. Adenosine only modulated dopamine when it was applied 2 or 5 s before stimulation. Longer time intervals and bath application of 5 µM adenosine did not decrease dopamine release. Mechanical stimulation of endogenous adenosine 2s before dopamine stimulation also decreased stimulated dopamine release by 41 ± 7 %, similar to the 54 ± 6 % decrease in dopamine after exogenous adenosine application. Dopamine inhibition by transient adenosine was recovered within 10 minutes. The A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) blocked the dopamine modulation, whereas dopamine modulation was unaffected by the A2A receptor antagonist SCH 442416. Thus, transient adenosine changes can transiently modulate phasic dopamine release via A1 receptors. These data demonstrate that adenosine has a rapid, but transient, modulatory role in the brain. PMID:25219576

The Role of D2-Autoreceptors in Regulating Dopamine Neuron Activity and Transmission

PubMed Central

Ford, Christopher P

2014-01-01

Dopamine D2-autoreceptors play a key role in regulating the activity of dopamine neurons and control the synthesis, release and uptake of dopamine. These Gi/o-coupled inhibitory receptors play a major part in shaping dopamine transmission. Found at both somatodendritic and axonal sites, autoreceptors regulate the firing patterns of dopamine neurons and control the timing and amount of dopamine released from their terminals in target regions. Alterations in the expression and activity of autoreceptors are thought to contribute to Parkinson’s disease as well as schizophrenia, drug addiction and attention deficit hyperactivity disorder (ADHD), which emphasizes the importance of D2-autoreceptors in regulating the dopamine system. This review will summarize the cellular actions of dopamine autoreceptors and discuss recent advances that have furthered our understanding of the mechanisms by which D2-receptors control dopamine transmission. PMID:24463000

Dynamic nigrostriatal dopamine biases action selection

PubMed Central

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

2017-01-01

Summary Dopamine is thought to play a critical role in reinforcement learning and goal-directed behavior, but its function in action selection remains largely unknown. Here, we demonstrate that nigrostriatal dopamine biases ongoing action selection. When mice were trained to dynamically switch the action selected at different time points, changes in firing rate of nigrostriatal dopamine neurons, as well as dopamine signaling in the dorsal striatum, were found to be associated with action selection. This dopamine profile is specific to behavioral choice, scalable with interval duration, and doesn’t reflect reward prediction error, timing, or value as single factors alone. Genetic deletion of NMDA receptors on dopamine or striatal neurons, or optogenetic manipulation of dopamine concentration, alters dopamine signaling and biases action selection. These results unveil a crucial role of nigrostriatal dopamine in integrating diverse information for regulating upcoming actions and have important implications for neurological disorders including Parkinson’s disease and substance dependence. PMID:28285820

Dynamic Nigrostriatal Dopamine Biases Action Selection.

PubMed

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

2017-03-22

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

Bioconjugated gold nanoparticles accelerate the growth of new blood vessels through redox signaling.

PubMed

Nethi, Susheel Kumar; Mukherjee, Sudip; Veeriah, Vimal; Barui, Ayan Kumar; Chatterjee, Suvro; Patra, Chitta Ranjan

2014-11-28

We have designed and developed novel pro-angiogenic bio-synthesized gold nanoconjugates (b-Au-HP) that make new blood vessels, as observed by several in vitro and in vivo assays, suggesting their future potential applications in alternative treatment strategies for wound healing, cardiovascular diseases (CVD) and ischemic diseases using a nanomedicine approach.

Modification of quantum dots with nucleic acids

NASA Astrophysics Data System (ADS)

Kocherginskaya, P. B.; Romanova, A. V.; Prokhorenko, I. A.; Itkis, Daniil M.; Korshun, V. A.; Goodilin, Eugene A.; Tretyakov, Yuri D.

2011-12-01

The key principles and modern approaches to targeted modification of semiconductor colloidal nanoparticles, quantum dots, which exhibit unique photophysical properties and are a promising class of luminescent markers, are discussed. Attention is given to the preparation of their bioconjugates with nucleic acids, promising tools for biological microchips and resonance energy transfer sensors. The bibliography includes 80 references.

Assembly of catalase-based bioconjugates for enhanced anticancer efficiency of photodynamic therapy in vitro.

PubMed

Zhao, Jie; Fei, Jinbo; Du, Cuiling; Cui, Wei; Ma, Hongchao; Li, Junbai

2013-11-25

An oxygen generation core-shell structure uploading rose bengal has been fabricated by covalent assembly of catalase and alginate dialdehyde via Schiff's base. The composite can catalyze the decomposition of intracellular H2O2 to increase the concentration of O2, which effectively enhances the anticancer efficiency of photodynamic therapy in vitro.

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

PubMed

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

2014-06-16

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

Dopamine D1 receptor activation leads to object recognition memory in a coral reef fish.

PubMed

Hamilton, Trevor J; Tresguerres, Martin; Kline, David I

2017-07-01

Object recognition memory is the ability to identify previously seen objects and is an adaptive mechanism that increases survival for many species throughout the animal kingdom. Previously believed to be possessed by only the highest order mammals, it is now becoming clear that fish are also capable of this type of memory formation. Similar to the mammalian hippocampus, the dorsolateral pallium regulates distinct memory processes and is modulated by neurotransmitters such as dopamine. Caribbean bicolour damselfish ( Stegastes partitus ) live in complex environments dominated by coral reef structures and thus likely possess many types of complex memory abilities including object recognition. This study used a novel object recognition test in which fish were first presented two identical objects, then after a retention interval of 10 min with no objects, the fish were presented with a novel object and one of the objects they had previously encountered in the first trial. We demonstrate that the dopamine D 1 -receptor agonist (SKF 38393) induces the formation of object recognition memories in these fish. Thus, our results suggest that dopamine-receptor mediated enhancement of spatial memory formation in fish represents an evolutionarily conserved mechanism in vertebrates. © 2017 The Author(s).

Multiple cone pathways are involved in photic regulation of retinal dopamine.

PubMed

Qiao, Sheng-Nan; Zhang, Zhijing; Ribelayga, Christophe P; Zhong, Yong-Mei; Zhang, Dao-Qi

2016-06-30

Dopamine is a key neurotransmitter in the retina and plays a central role in the light adaptive processes of the visual system. The sole source of retinal dopamine is dopaminergic amacrine cells (DACs). We and others have previously demonstrated that DACs are activated by rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs) upon illumination. However, it is still not clear how each class of photosensitive cells generates light responses in DACs. We genetically isolated cone function in mice to specifically examine the cone-mediated responses of DACs and their neural pathways. In addition to the reported excitatory input to DACs from light-increment (ON) bipolar cells, we found that cones alternatively signal to DACs via a retrograde signalling pathway from ipRGCs. Cones also produce ON and light-decrement (OFF) inhibitory responses in DACs, which are mediated by other amacrine cells, likely driven by type 1 and type 2/3a OFF bipolar cells, respectively. Dye injections indicated that DACs had similar morphological profiles with or without ON/OFF inhibition. Our data demonstrate that cones utilize specific parallel excitatory and inhibitory circuits to modulate DAC activity and efficiently regulate dopamine release and the light-adaptive state of the retina.

Gold nanoparticles coated polystyrene/reduced graphite oxide microspheres with improved dispersibility and electrical conductivity for dopamine detection.

PubMed

Qian, Tao; Yu, Chenfei; Wu, Shishan; Shen, Jian

2013-12-01

Gold nanoparticles coated polystyrene/reduced graphite oxide (AuNPs@PS/RGO) microspheres have been successfully prepared via a facile process, and the decorative gold nanoparticles could prevent the aggregation of RGO by electrostatic repulsive interaction, and lead to high dispersibility of the composite. The prepared composite has a highly increased conductivity of 129Sm(-1) due to the unique electrical properties of citrate reduced gold nanoparticles. Being employed as an electrochemical sensor for detection of dopamine, the modified electrode exhibits remarkable sensitivity (3.44μA/μM) and lower detection limit (5nM), with linear response in a range of 0.05-20μM. Moreover, valid response to dopamine obtained in present work also indicates the prospective performances of AuNPs@PS/RGO microspheres to other biological molecules, such as nucleic acids, proteins and enzymes. Copyright © 2013 Elsevier B.V. All rights reserved.

PSD-95 expression controls l-DOPA dyskinesia through dopamine D1 receptor trafficking

PubMed Central

Porras, Gregory; Berthet, Amandine; Dehay, Benjamin; Li, Qin; Ladepeche, Laurent; Normand, Elisabeth; Dovero, Sandra; Martinez, Audrey; Doudnikoff, Evelyne; Martin-Négrier, Marie-Laure; Chuan, Qin; Bloch, Bertrand; Choquet, Daniel; Boué-Grabot, Eric; Groc, Laurent; Bezard, Erwan

2012-01-01

l-DOPA–induced dyskinesia (LID), a detrimental consequence of dopamine replacement therapy for Parkinson’s disease, is associated with an alteration in dopamine D1 receptor (D1R) and glutamate receptor interactions. We hypothesized that the synaptic scaffolding protein PSD-95 plays a pivotal role in this process, as it interacts with D1R, regulates its trafficking and function, and is overexpressed in LID. Here, we demonstrate in rat and macaque models that disrupting the interaction between D1R and PSD-95 in the striatum reduces LID development and severity. Single quantum dot imaging revealed that this benefit was achieved primarily by destabilizing D1R localization, via increased lateral diffusion followed by increased internalization and diminished surface expression. These findings indicate that altering D1R trafficking via synapse-associated scaffolding proteins may be useful in the treatment of dyskinesia in Parkinson’s patients. PMID:23041629

Putting desire on a budget: dopamine and energy expenditure, reconciling reward and resources

PubMed Central

Beeler, Jeff A.; Frazier, Cristianne R. M.; Zhuang, Xiaoxi

2012-01-01

Accumulating evidence indicates integration of dopamine function with metabolic signals, highlighting a potential role for dopamine in energy balance, frequently construed as modulating reward in response to homeostatic state. Though its precise role remains controversial, the reward perspective of dopamine has dominated investigation of motivational disorders, including obesity. In the hypothesis outlined here, we suggest instead that the primary role of dopamine in behavior is to modulate activity to adapt behavioral energy expenditure to the prevailing environmental energy conditions, with the role of dopamine in reward and motivated behaviors derived from its primary role in energy balance. Dopamine has long been known to modulate activity, exemplified by psychostimulants that act via dopamine. More recently, there has been nascent investigation into the role of dopamine in modulating voluntary activity, with some investigators suggesting that dopamine may serve as a final common pathway that couples energy sensing to regulated voluntary energy expenditure. We suggest that interposed between input from both the internal and external world, dopamine modulates behavioral energy expenditure along two axes: a conserve-expend axis that regulates generalized activity and an explore-exploit axes that regulates the degree to which reward value biases the distribution of activity. In this view, increased dopamine does not promote consumption of tasty food. Instead increased dopamine promotes energy expenditure and exploration while decreased dopamine favors energy conservation and exploitation. This hypothesis provides a mechanistic interpretation to an apparent paradox: the well-established role of dopamine in food seeking and the findings that low dopaminergic functions are associated with obesity. Our hypothesis provides an alternative perspective on the role of dopamine in obesity and reinterprets the “reward deficiency hypothesis” as a perceived energy deficit. We propose that dopamine, by facilitating energy expenditure, should be protective against obesity. We suggest the apparent failure of this protective mechanism in Western societies with high prevalence of obesity arises as a consequence of sedentary lifestyles that thwart energy expenditure. PMID:22833718

Processing of emotional information in the human subthalamic nucleus.

PubMed

Buot, Anne; Welter, Marie-Laure; Karachi, Carine; Pochon, Jean-Baptiste; Bardinet, Eric; Yelnik, Jérôme; Mallet, Luc

2013-12-01

The subthalamic nucleus (STN) is an efficient target for treating patients with Parkinson's disease as well as patients with obsessive-compulsive disorder (OCD) using high frequency stimulation (HFS). In both Parkinson's disease and OCD patients, STN-HFS can trigger abnormal behaviours, such as hypomania and impulsivity. To investigate if this structure processes emotional information, and whether it depends on motor demands, we recorded subthalamic local field potentials in 16 patients with Parkinson's disease using deep brain stimulation electrodes. Recordings were made with and without dopaminergic treatment while patients performed an emotional categorisation paradigm in which the response varied according to stimulus valence (pleasant, unpleasant and neutral) and to the instruction given (motor, non-motor and passive). Pleasant, unpleasant and neutral stimuli evoked an event related potential (ERP). Without dopamine medication, ERP amplitudes were significantly larger for unpleasant compared with neutral pictures, whatever the response triggered by the stimuli; and the magnitude of this effect was maximal in the ventral part of the STN. No significant difference in ERP amplitude was observed for pleasant pictures. With dopamine medication, ERP amplitudes were significantly increased for pleasant compared with neutral pictures whatever the response triggered by the stimuli, while ERP amplitudes to unpleasant pictures were not modified. These results demonstrate that the ventral part of the STN processes the emotional valence of stimuli independently of the motor context and that dopamine enhances processing of pleasant information. These findings confirm the specific involvement of the STN in emotional processes in human, which may underlie the behavioural changes observed in patients with deep brain stimulation.

Brain catechol-o-methyltransferase (COMT) inhibition by tolcapone counteracts recognition memory deficits in normal and chronic phencyclidine-treated rats and in COMT-Val transgenic mice

PubMed Central

Detrait, E.R.; Carr, G.V.; Ferraille, S.; Weinberger, D.R.; Lamberty, Y.

2015-01-01

The critical involvement of dopamine in cognitive processes has been well established, suggesting therapies targeting dopamine metabolism may alleviate cognitive dysfunction. COMT is a catecholamine-degrading enzyme, the substrates of which include dopamine, epinephrine, and norepinephrine. The present work illustrates the potential therapeutic efficacy of COMT inhibition for alleviating cognitive impairment. A brain penetrant COMT inhibitor, tolcapone, was tested in normal and phencyclidine (PCP)-treated rats and COMT–Val transgenic mice. In a Novel Object Recognition (NOR) procedure, tolcapone counteracted a 24h-dependent forgetting of a familiar object and counteracted PCP-induced recognition deficits in the rats at doses ranging from 7.5 to 30 mg/kg. In contrast, entacapone, a COMT inhibitor which does not readily cross the blood-brain barrier failed to show efficacy at doses up to 30mg/kg. Tolcapone at a dose of 30 mg/kg also improved NOR performance in the transgenic mice, which showed clear recognition deficits. Complementing earlier studies, our results indicate that central inhibition of COMT positively impacts recognition memory processes and might constitute an appealing treatment for cognitive dysfunction related to neuropsychiatric disorders. PMID:26919286

Control of extracellular dopamine at dendrite and axon terminals

PubMed Central

Ford, Christopher P.; Gantz, Stephanie C.; Phillips, Paul E. M.; Williams, John T.

2010-01-01

Midbrain dopamine neurons release dopamine from both axons and dendrites. The mechanism underlying release at these different sites has been proposed to differ. This study used electrochemical and electrophysiological methods to compare the time course and calcium-dependence of somatodendritc dopamine release in the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) to that of axonal dopamine release in the dorsal striatum. The amount of dopamine released in the striatum was ~20 fold greater than in cell body regions of the VTA or SNc. However the calcium dependence and time to peak of the dopamine transients were similar. These results illustrate an unexpected overall similarity in the mechanisms of dopamine release in the striatum and cell body regions. To examine how diffusion regulates the time course of dopamine following release, dextran was added to the extracellular solution to slow diffusion. In the VTA, dextran slowed the rate of rise and fall of the extracellular dopamine transient as measured by fast-scan cyclic voltammetry (FSCV) yet did not alter the kinetics of the dopamine dependent inhibitory post-synaptic current (IPSC). Dextran failed to significantly alter the time course of the rise and fall of the dopamine transient in the striatum suggesting a more influential role for reuptake in the striatum. The conclusion is that the time course of dopamine within the extracellular space of the VTA is dependent on both diffusion and reuptake, whereas the activation of D2-receptors on dopamine neurons is primarily limited by reuptake. PMID:20484639

Initial elevations in glutamate and dopamine neurotransmission decline with age, as does exploratory behavior, in LRRK2 G2019S knock-in mice

PubMed Central

Kuhlmann, Naila; Kadgien, Chelsie A; Tatarnikov, Igor; Fox, Jesse; Khinda, Jaskaran; Mitchell, Emma; Bergeron, Sabrina; Melrose, Heather

2017-01-01

LRRK2 mutations produce end-stage Parkinson’s disease (PD) with reduced nigrostriatal dopamine, whereas, asymptomatic carriers have increased dopamine turnover and altered brain connectivity. LRRK2 pathophysiology remains unclear, but reduced dopamine and mitochondrial abnormalities occur in aged G2019S mutant knock-in (GKI) mice. Conversely, cultured GKI neurons exhibit increased synaptic transmission. We assessed behavior and synaptic glutamate and dopamine function across a range of ages. Young GKI mice exhibit more vertical exploration, elevated glutamate and dopamine transmission, and aberrant D2-receptor responses. These phenomena decline with age, but are stable in littermates. In young GKI mice, dopamine transients are slower, independent of dopamine transporter (DAT), increasing the lifetime of extracellular dopamine. Slowing of dopamine transients is observed with age in littermates, suggesting premature ageing of dopamine synapses in GKI mice. Thus, GKI mice exhibit early, but declining, synaptic and behavioral phenotypes, making them amenable to investigation of early pathophysiological, and later parkinsonian-like, alterations. This model will prove valuable in efforts to develop neuroprotection for PD. PMID:28930069

The impact of a parkinsonian lesion on dynamic striatal dopamine transmission depends on nicotinic receptor activation

PubMed Central

Jennings, Katie A.; Platt, Nicola J.; Cragg, Stephanie J.

2015-01-01

Dopamine function is disturbed in Parkinson's disease (PD), but whether and how release of dopamine from surviving neurons is altered has long been debated. Nicotinic acetylcholine receptors (nAChRs) on dopamine axons powerfully govern dopamine release and could be critical contributing factors. We revisited whether fundamental properties of dopamine transmission are changed in a parkinsonian brain and tested the potentially profound masking effects of nAChRs. Using real-time detection of dopamine in mouse striatum after a partial 6-hydroxydopamine lesion and under nAChR inhibition, we reveal that dopamine signals show diminished sensitivity to presynaptic activity. This effect manifested as diminished contrast between DA release evoked by the lowest versus highest frequencies. This reduced activity-dependence was underpinned by loss of short-term facilitation of dopamine release, consistent with an increase in release probability (Pr). With nAChRs active, the reduced activity-dependence of dopamine release after a parkinsonian lesion was masked. Consequently, moment-by-moment variation in activity of nAChRs may lead to dynamic co-variation in dopamine signal impairments in PD. PMID:26117304

Initial elevations in glutamate and dopamine neurotransmission decline with age, as does exploratory behavior, in LRRK2 G2019S knock-in mice.

PubMed

Volta, Mattia; Beccano-Kelly, Dayne A; Paschall, Sarah A; Cataldi, Stefano; MacIsaac, Sarah E; Kuhlmann, Naila; Kadgien, Chelsie A; Tatarnikov, Igor; Fox, Jesse; Khinda, Jaskaran; Mitchell, Emma; Bergeron, Sabrina; Melrose, Heather; Farrer, Matthew J; Milnerwood, Austen J

2017-09-20

LRRK2 mutations produce end-stage Parkinson's disease (PD) with reduced nigrostriatal dopamine, whereas, asymptomatic carriers have increased dopamine turnover and altered brain connectivity. LRRK2 pathophysiology remains unclear, but reduced dopamine and mitochondrial abnormalities occur in aged G2019S mutant knock-in (GKI) mice. Conversely, cultured GKI neurons exhibit increased synaptic transmission. We assessed behavior and synaptic glutamate and dopamine function across a range of ages. Young GKI mice exhibit more vertical exploration, elevated glutamate and dopamine transmission, and aberrant D2-receptor responses. These phenomena decline with age, but are stable in littermates. In young GKI mice, dopamine transients are slower, independent of dopamine transporter (DAT), increasing the lifetime of extracellular dopamine. Slowing of dopamine transients is observed with age in littermates, suggesting premature ageing of dopamine synapses in GKI mice. Thus, GKI mice exhibit early, but declining, synaptic and behavioral phenotypes, making them amenable to investigation of early pathophysiological, and later parkinsonian-like, alterations. This model will prove valuable in efforts to develop neuroprotection for PD.

In vitro and in vivo evaluation of poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate)/dopamine-coated electrodes for dopamine delivery.

PubMed

Sui, L; Song, X J; Ren, J; Cai, W J; Ju, L H; Wang, Y; Wang, L Y; Chen, M

2014-06-01

Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrene sulfonate) (PSS) has a variety of chemical and biomedical applications. The application of PEDOT/PSS polymers in drug delivery has attracted attention. However, whether conducting polymers of PEDOT/PSS could be used for dopamine delivery has not clear. In the present study, the PEDOT/PSS coatings incorporated with dopamine were fabricated on 0.5 mm diameter platinum electrodes, electrochemical properties, and dopamine delivery capacities of these electrodes were evaluated in vitro and in vivo through implanting these electrodes into brain striatum area. The findings demonstrated that the PEDOT/PSS/dopamine coatings on platinum electrodes could reduce electrodes impedances, increase charge storage capacities, and release significant levels of dopamine upon electrical stimulation of these electrodes. These results indicated that polymers of PEDOT/PSS/dopamine could be used for dopamine delivery, implicating potential application of PEDOT/PSS/dopamine-coated implantable electrodes in the treatment of some diseases associated with dopamine deficits, such as, electrodes for the treatment of Parkinson's disease during deep brain stimulation. Copyright © 2013 Wiley Periodicals, Inc.

The Role of Dopamine in Anticipatory Pursuit Eye Movements: Insights from Genetic Polymorphisms in Healthy Adults

PubMed Central

Hennig, Jürgen

2016-01-01

Abstract There is a long history of eye movement research in patients with psychiatric diseases for which dysfunctions of neurotransmission are considered to be the major pathologic mechanism. However, neuromodulation of oculomotor control is still hardly understood. We aimed to investigate in particular the impact of dopamine on smooth pursuit eye movements. Systematic variability in dopaminergic transmission due to genetic polymorphisms in healthy subjects offers a noninvasive opportunity to determine functional associations. We measured smooth pursuit in 110 healthy subjects genotyped for two well-documented polymorphisms, the COMT Val158Met polymorphism and the SLC6A3 3′-UTR-VNTR polymorphism. Pursuit paradigms were chosen to particularly assess the ability of the pursuit system to initiate tracking when target motion onset is blanked, reflecting the impact of extraretinal signals. In contrast, when following a fully visible target sensory, retinal signals are available. Our results highlight the crucial functional role of dopamine for anticipatory, but not for sensory-driven, pursuit processes. We found the COMT Val158Met polymorphism specifically associated with anticipatory pursuit parameters, emphasizing the dominant impact of prefrontal dopamine activity on complex oculomotor control. In contrast, modulation of striatal dopamine activity by the SLC6A3 3′-UTR-VNTR polymorphism had no significant functional effect. Though often neglected so far, individual differences in healthy subjects provide a promising approach to uncovering functional mechanisms and can be used as a bridge to understanding deficits in patients. PMID:28101524

The Role of Dopamine in Anticipatory Pursuit Eye Movements: Insights from Genetic Polymorphisms in Healthy Adults.

PubMed

Billino, Jutta; Hennig, Jürgen; Gegenfurtner, Karl R

2016-01-01

There is a long history of eye movement research in patients with psychiatric diseases for which dysfunctions of neurotransmission are considered to be the major pathologic mechanism. However, neuromodulation of oculomotor control is still hardly understood. We aimed to investigate in particular the impact of dopamine on smooth pursuit eye movements. Systematic variability in dopaminergic transmission due to genetic polymorphisms in healthy subjects offers a noninvasive opportunity to determine functional associations. We measured smooth pursuit in 110 healthy subjects genotyped for two well-documented polymorphisms, the COMT Val 158 Met polymorphism and the SLC6A3 3'-UTR-VNTR polymorphism. Pursuit paradigms were chosen to particularly assess the ability of the pursuit system to initiate tracking when target motion onset is blanked, reflecting the impact of extraretinal signals. In contrast, when following a fully visible target sensory, retinal signals are available. Our results highlight the crucial functional role of dopamine for anticipatory, but not for sensory-driven, pursuit processes. We found the COMT Val 158 Met polymorphism specifically associated with anticipatory pursuit parameters, emphasizing the dominant impact of prefrontal dopamine activity on complex oculomotor control. In contrast, modulation of striatal dopamine activity by the SLC6A3 3'-UTR-VNTR polymorphism had no significant functional effect. Though often neglected so far, individual differences in healthy subjects provide a promising approach to uncovering functional mechanisms and can be used as a bridge to understanding deficits in patients.

Magnetically assisted surface-enhanced raman scattering selective determination of dopamine in an artificial cerebrospinal fluid and a mouse striatum using Fe(3)O(4)/Ag nanocomposite.

PubMed

Ranc, Vaclav; Markova, Zdenka; Hajduch, Marian; Prucek, Robert; Kvitek, Libor; Kaslik, Josef; Safarova, Klara; Zboril, Radek

2014-03-18

The dopaminergic neural system is a crucial part of the brain responsible for many of its functions including mood, arousal, and other roles. Dopamine is the key neurotransmitter of this system, and a determination of its level presents a demanding task needed for a deeper understanding of the processes, even pathological, involving this brain part. In this work, we present a method for a fast analysis of dopamine levels in samples of cerebrospinal fluid and mouse striatum. The method is based on a nanocomposite composed of magnetite and silver nanoparticles, whose surface is modified with iron nitriloacetic acid (Fe-NTA)-a dopamine-selective compound. The magnetic properties of this nanocomposite enable simple separation of targeted molecules from a complex matrix while the silver acts as a platform for surface-enhanced Raman scattering (SERS). Silver and magnetite nanoparticles are joined by carboxymethyl chitosan, useful in biological environments and enhancing the sensitivity due to the presence of carboxyl groups. This system reveals a good stability and reproducibility. Moreover, rapid and simple quantitative experiments show an improvement in the detection of dopamine levels in biological assays at low femtomolar concentrations. The comparative data performed with clinical samples of mouse striatum show that the developed magnetic SERS is a strong alternative to conventional high-performance liquid chromatography-mass spectrometry (HPLC-MS) with even several superior aspects including faster and cheaper analysis and no necessity of sample preconcentration or derivatization.

Reversal of inhibition of putative dopaminergic neurons of the ventral tegmental area: Interaction of GABAB and D2 receptors

PubMed Central

Nimitvilai, Sudarat; Arora, Devinder S.; McElvain, Maureen A.; Brodie, Mark S.

2012-01-01

Neurons of the ventral tegmental area (VTA) are critical in the rewarding and reinforcing properties of drugs of abuse. Desensitization of VTA neurons to moderate extracellular concentrations of dopamine (DA) is dependent on protein kinase C (PKC) and intracellular calcium levels. This desensitization is called DA inhibition reversal (DIR), as it requires concurrent activation of D2 and D1-like receptors; activation of D2 receptors alone does not result in desensitization. Activation of other G-protein linked receptors can substitute for D1 activation. Like D2 receptors, GABAB receptors in the VTA are coupled to G-protein-linked potassium channels. In the present study, we examined interactions between a GABAB agonist, baclofen, and dopamine agonists, dopamine and quinpirole, to determine whether there was some interaction in the processes of desensitization of GABAB and D2 responses. Long-duration administration of baclofen alone produced reversal of the baclofen-induced inhibition indicative of desensitization, and this desensitization persisted for at least 60 min after baclofen washout. Desensitization to baclofen was dependent on protein kinase C. Dopamine inhibition was reduced for 30 min after baclofen-induced desensitization and conversely, the magnitude of baclofen inhibition was reduced for 30 min by long-duration application of dopamine, but not quinpirole. These results indicate that D2 and GABAB receptors share some protein kinase C-dependent mechanisms of receptor desensitization. PMID:22986166

Reward system and addiction: what dopamine does and doesn't do.

PubMed

Di Chiara, Gaetano; Bassareo, Valentina

2007-02-01

Addictive drugs share with palatable food the property of increasing extracellular dopamine (DA), preferentially in the nucleus accumbens shell rather than in the core. However, by acting directly on the brain, drugs bypass the adaptive mechanisms (habituation) that constrain the responsiveness of accumbens shell DA to food reward, abnormally facilitating Pavlovian incentive learning and promoting the acquisition of abnormal DA-releasing properties by drug conditioned stimuli. Thus, whereas Pavlovian food conditioned stimuli release core but not shell DA, drug conditioned stimuli do the opposite, releasing shell but not core DA. This process, which results in the acquisition of excessive incentive-motivational properties by drug conditioned stimuli, initiates the drug addiction process. Neuroadaptive processes related to the chronic influence of drugs on subcortical DA might secondarily impair the function of prefronto-striatal loops, resulting in impairments in impulse control and decision making that form the basis for the compulsive feature of drug seeking and its relapsing character.

Trans-blood brain barrier delivery of dopamine-loaded nanoparticles reverses functional deficits in parkinsonian rats.

PubMed

Pahuja, Richa; Seth, Kavita; Shukla, Anshi; Shukla, Rajendra Kumar; Bhatnagar, Priyanka; Chauhan, Lalit Kumar Singh; Saxena, Prem Narain; Arun, Jharna; Chaudhari, Bhushan Pradosh; Patel, Devendra Kumar; Singh, Sheelendra Pratap; Shukla, Rakesh; Khanna, Vinay Kumar; Kumar, Pradeep; Chaturvedi, Rajnish Kumar; Gupta, Kailash Chand

2015-05-26

Sustained and safe delivery of dopamine across the blood brain barrier (BBB) is a major hurdle for successful therapy in Parkinson's disease (PD), a neurodegenerative disorder. Therefore, in the present study we designed neurotransmitter dopamine-loaded PLGA nanoparticles (DA NPs) to deliver dopamine to the brain. These nanoparticles slowly and constantly released dopamine, showed reduced clearance of dopamine in plasma, reduced quinone adduct formation, and decreased dopamine autoxidation. DA NPs were internalized in dopaminergic SH-SY5Y cells and dopaminergic neurons in the substantia nigra and striatum, regions affected in PD. Treatment with DA NPs did not cause reduction in cell viability and morphological deterioration in SH-SY5Y, as compared to bulk dopamine-treated cells, which showed reduced viability. Herein, we report that these NPs were able to cross the BBB and capillary endothelium in the striatum and substantia nigra in a 6-hydroxydopamine (6-OHDA)-induced rat model of PD. Systemic intravenous administration of DA NPs caused significantly increased levels of dopamine and its metabolites and reduced dopamine-D2 receptor supersensitivity in the striatum of parkinsonian rats. Further, DA NPs significantly recovered neurobehavioral abnormalities in 6-OHDA-induced parkinsonian rats. Dopamine delivered through NPs did not cause additional generation of ROS, dopaminergic neuron degeneration, and ultrastructural changes in the striatum and substantia nigra as compared to 6-OHDA-lesioned rats. Interestingly, dopamine delivery through nanoformulation neither caused alterations in the heart rate and blood pressure nor showed any abrupt pathological change in the brain and other peripheral organs. These results suggest that NPs delivered dopamine into the brain, reduced dopamine autoxidation-mediated toxicity, and ultimately reversed neurochemical and neurobehavioral deficits in parkinsonian rats.

Effect of beta-phenylethylamine on extracellular concentrations of dopamine in the nucleus accumbens and prefrontal cortex.

PubMed

Murata, Mikio; Katagiri, Nobuyuki; Ishida, Kota; Abe, Kenji; Ishikawa, Masago; Utsunomiya, Iku; Hoshi, Keiko; Miyamoto, Ken-ichi; Taguchi, Kyoji

2009-05-07

It is known that psychostimulants stimulate dopamine transmission in the nucleus accumbens. In the present study, we examined the effects of systemically administered beta-phenylethylamine (beta-PEA), a psychomotor-stimulating trace amine, on dopamine concentrations in the nucleus accumbens and prefrontal cortex in freely moving rats, using an in vivo microdialysis technique. Intraperitoneal administration of beta-PEA (12.5 and 25 mg/kg) significantly increased extracellular dopamine levels in the nucleus accumbens shell. The observed increase in the dopamine concentration in nucleus accumbens shell dialysate after intraperitoneal administration of 25 mg/kg beta-PEA was inhibited by pre-treatment with a dopamine uptake inhibitor, GBR12909 (10 mg/kg, i.p.). In contrast, beta-PEA (25 mg/kg, i.p.) did not affect dopamine release in the nucleus accumbens core. Although a high dose of beta-PEA (50 mg/kg) significantly increased dopamine levels in the nucleus accumbens core, the dopamine increasing effect of beta-PEA was more potent in the nucleus accumbens shell. Systemic administration of 12.5 and 25 mg/kg beta-PEA also increased extracellular dopamine levels in the prefrontal cortex of rats. However, systemic 25 mg/kg beta-PEA-induced increases in extracellular dopamine levels were not blocked by GBR12909 within the prefrontal cortex. These results suggest that beta-PEA has a greater effect in the shell than in the core and low-dose beta-PEA stimulates dopamine release in the nucleus accumbens shell through uptake by a dopamine transporter. Similarly, beta-PEA increased extracellular dopamine levels in the prefrontal cortex. Thus, beta-PEA may increase extracellular dopamine concentrations in the mesocorticolimbic pathway.

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

PubMed Central

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

2017-01-01

The dopamine hypothesis of schizophrenia posits that increased subcortical dopamine underpins psychosis. In vivo imaging studies indicate an increased presynaptic dopamine synthesis capacity in striatal terminals and cell bodies in the midbrain in schizophrenia; however, measures of the dopamine-synthesising enzyme, tyrosine hydroxylase (TH), have not identified consistent changes. We hypothesise that dopamine dysregulation in schizophrenia could result from changes in expression of dopamine synthesis enzymes, receptors, transporters or catabolic enzymes. Gene expression of 12 dopamine-related molecules was examined in post-mortem midbrain (28 antipsychotic-treated schizophrenia cases/29 controls) using quantitative PCR. TH and the synaptic dopamine transporter (DAT) proteins were examined in post-mortem midbrain (26 antipsychotic-treated schizophrenia cases per 27 controls) using immunoblotting. TH and aromatic acid decarboxylase (AADC) mRNA and TH protein were unchanged in the midbrain in schizophrenia compared with controls. Dopamine receptor D2 short, vesicular monoamine transporter (VMAT2) and DAT mRNAs were significantly decreased in schizophrenia, with no change in DRD3 mRNA, DRD3nf mRNA and DAT protein between diagnostic groups. However, DAT protein was significantly increased in putatively treatment-resistant cases of schizophrenia compared to putatively treatment-responsive cases. Midbrain monoamine oxidase A (MAOA) mRNA was increased, whereas MAOB and catechol-O-methyl transferase mRNAs were unchanged in schizophrenia. We conclude that, whereas some mRNA changes are consistent with increased dopamine action (decreased DAT mRNA), others suggest reduced dopamine action (increased MAOA mRNA) in the midbrain in schizophrenia. Here, we identify a molecular signature of dopamine dysregulation in the midbrain in schizophrenia that mainly includes gene expression changes of molecules involved in dopamine synthesis and in regulating the time course of dopamine action. PMID:28094812

Treatment of Parkinson’s disease: nanostructured sol–gel silica–dopamine reservoirs for controlled drug release in the central nervous system

PubMed Central

López, Tessy; Bata-García, José L; Esquivel, Dulce; Ortiz-Islas, Emma; Gonzalez, Richard; Ascencio, Jorge; Quintana, Patricia; Oskam, Gerko; Álvarez-Cervera, Fernando J; Heredia-López, Francisco J; Góngora-Alfaro, José L

2011-01-01

Introduction We have evaluated the use of silica–dopamine reservoirs synthesized by the sol–gel approach with the aim of using them in the treatment of Parkinson’s disease, specifically as a device for the controlled release of dopamine in the striatum. Theoretical calculations illustrate that dopamine is expected to assume a planar structure and exhibit weak interactions with the silica surface. Methods Several samples were prepared by varying the wt% of dopamine added during the hydrolysis of tetraethyl orthosilicate. The silica–dopamine reservoirs were characterized by N2 adsorption, scanning and transmission electron microscopy, and Fourier transform infrared spectroscopy. The in vitro release profiles were determined using ultraviolet visible absorbance spectroscopy. The textural analyses showed a maximum value for the surface area of 620 m2/g nanostructured silica materials. The stability of dopamine in the silica network was confirmed by infrared and 13C-nuclear magnetic resonance spectroscopy. The reservoirs were evaluated by means of apomorphine-induced rotation behavior in hemiparkisonian rats. Results The in vitro dopamine delivery profiles indicate two regimes of release, a fast and sustained dopamine delivery was observed up to 24 hours, and after this time the rate of delivery became constant. Histologic analysis of formalin-fixed brains performed 24–32 weeks after reservoir implantation revealed that silica–dopamine implants had a reddish-brown color, suggesting the presence of oxidized dopamine, likely caused by the fixation procedure, while implants without dopamine were always translucent. Conclusion The major finding of the study was that intrastriatal silica–dopamine implants reversed the rotational asymmetry induced by apomorphine, a dopamine agonist, in hemiparkinsonian rats. No dyskinesias or other motor abnormalities were observed in animals implanted with silica or silica–dopamine. PMID:21289978

Interaction between catechol-O-methyltransferase (COMT) Val158Met genotype and genetic vulnerability to schizophrenia during explicit processing of aversive facial stimuli.

PubMed

Lo Bianco, L; Blasi, G; Taurisano, P; Di Giorgio, A; Ferrante, F; Ursini, G; Fazio, L; Gelao, B; Romano, R; Papazacharias, A; Caforio, G; Sinibaldi, L; Popolizio, T; Bellantuono, C; Bertolino, A

2013-02-01

Emotion dysregulation is a key feature of schizophrenia, a brain disorder strongly associated with genetic risk and aberrant dopamine signalling. Dopamine is inactivated by catechol-O-methyltransferase (COMT), whose gene contains a functional polymorphism (COMT Val158Met) associated with differential activity of the enzyme and with brain physiology of emotion processing. The aim of the present study was to investigate whether genetic risk for schizophrenia and COMT Val158Met genotype interact on brain activity during implicit and explicit emotion processing. A total of 25 patients with schizophrenia, 23 healthy siblings of patients and 24 comparison subjects genotyped for COMT Val158Met underwent functional magnetic resonance imaging during implicit and explicit processing of facial stimuli with negative emotional valence. We found a main effect of diagnosis in the right amygdala, with decreased activity in patients and siblings compared with control subjects. Furthermore, a genotype × diagnosis interaction was found in the left middle frontal gyrus, such that the effect of genetic risk for schizophrenia was evident in the context of the Val/Val genotype only, i.e. the phenotype of reduced activity was present especially in Val/Val patients and siblings. Finally, a complete inversion of the COMT effect between patients and healthy subjects was found in the left striatum during explicit processing. Overall, these results suggest complex interactions between genetically determined dopamine signalling and risk for schizophrenia on brain activity in the prefrontal cortex during emotion processing. On the other hand, the effects in the striatum may represent state-related epiphenomena of the disorder itself.

Midbrain dopamine neurons signal aversion in a reward-context-dependent manner

PubMed Central

Matsumoto, Hideyuki; Tian, Ju; Uchida, Naoshige; Watabe-Uchida, Mitsuko

2016-01-01

Dopamine is thought to regulate learning from appetitive and aversive events. Here we examined how optogenetically-identified dopamine neurons in the lateral ventral tegmental area of mice respond to aversive events in different conditions. In low reward contexts, most dopamine neurons were exclusively inhibited by aversive events, and expectation reduced dopamine neurons’ responses to reward and punishment. When a single odor predicted both reward and punishment, dopamine neurons’ responses to that odor reflected the integrated value of both outcomes. Thus, in low reward contexts, dopamine neurons signal value prediction errors (VPEs) integrating information about both reward and aversion in a common currency. In contrast, in high reward contexts, dopamine neurons acquired a short-latency excitation to aversive events that masked their VPE signaling. Our results demonstrate the importance of considering the contexts to examine the representation in dopamine neurons and uncover different modes of dopamine signaling, each of which may be adaptive for different environments. DOI: http://dx.doi.org/10.7554/eLife.17328.001 PMID:27760002

Cross-hemispheric dopamine projections have functional significance

PubMed Central

Fox, Megan E.; Mikhailova, Maria A.; Bass, Caroline E.; Takmakov, Pavel; Gainetdinov, Raul R.; Budygin, Evgeny A.; Wightman, R. Mark

2016-01-01

Dopamine signaling occurs on a subsecond timescale, and its dysregulation is implicated in pathologies ranging from drug addiction to Parkinson’s disease. Anatomic evidence suggests that some dopamine neurons have cross-hemispheric projections, but the significance of these projections is unknown. Here we report unprecedented interhemispheric communication in the midbrain dopamine system of awake and anesthetized rats. In the anesthetized rats, optogenetic and electrical stimulation of dopamine cells elicited physiologically relevant dopamine release in the contralateral striatum. Contralateral release differed between the dorsal and ventral striatum owing to differential regulation by D2-like receptors. In the freely moving animals, simultaneous bilateral measurements revealed that dopamine release synchronizes between hemispheres and intact, contralateral projections can release dopamine in the midbrain of 6-hydroxydopamine–lesioned rats. These experiments are the first, to our knowledge, to show cross-hemispheric synchronicity in dopamine signaling and support a functional role for contralateral projections. In addition, our data reveal that psychostimulants, such as amphetamine, promote the coupling of dopamine transients between hemispheres. PMID:27298371

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

A peptide disrupting the D2R-DAT interaction protects against dopamine neurotoxicity.

PubMed

Su, Ping; Liu, Fang

2017-09-01

Dopamine reuptake from extracellular space to cytosol leads to accumulation of dopamine, which triggers neurotoxicity in dopaminergic neurons. Previous studies have shown that both dopamine D2 receptor (D2R) and dopamine transporter (DAT) are involved in dopamine neurotoxicity. However, blockade of either D2R or DAT causes side effects due to antagonism of other physiological functions of these two proteins. We previously found that DAT can form a protein complex with D2R and its cell surface expression is facilitated via D2R-DAT interaction, which regulates dopamine reuptake and intracellular dopamine levels. Here we found that an interfering peptide (DAT-S1) disrupting the D2R-DAT interaction protects neurons against dopamine neurotoxicity, and this effect is mediated by inhibiting DAT cell surface expression and inhibiting both caspase-3 and PARP-1 cleavage. This study demonstrates the role of the D2R-DAT complex in dopamine neurotoxicity and investigated the potential mechanisms, which might help better understand the mechanisms of dopamine neurotoxicity. The peptide may provide some insights to improve treatments for dopamine neurotoxicity and related diseases, such as Parkinson's disease, as well as methamphetamine- and 3,4-methsylenedioxy methamphetamine-induced neurotoxicity. Copyright © 2017. Published by Elsevier Inc.

Adding Dopamine to Proxymetacaine or Oxybuprocaine Solutions Potentiates and Prolongs the Cutaneous Antinociception in Rats.

PubMed

Chen, Yu-Wen; Chiu, Chong-Chi; Lin, Heng-Teng; Wang, Jhi-Joung; Hung, Ching-Hsia

2018-05-01

We evaluated the interaction of dopamine-proxymetacaine and dopamine- oxybuprocaine antinociception using isobolograms. This experiment uses subcutaneous drug (proxymetacaine, oxybuprocaine, and dopamine) injections under the skin of the rat's back, thus simulating infiltration blocks. The dose-related antinociceptive curves of proxymetacaine and oxybuprocaine alone and in combination with dopamine were constructed, and then the antinociceptive interactions between the local anesthetic and dopamine were analyzed using isobolograms. Subcutaneous proxymetacaine, oxybuprocaine, and dopamine produced a sensory block to local skin pinpricks in a dose-dependent fashion. The rank order of potency was proxymetacaine (0.57 [0.52-0.63] μmol/kg) > oxybuprocaine (1.05 [0.96-1.15] μmol/kg) > dopamine (165 [154-177] μmol/kg; P < .01 for each comparison) based on the 50% effective dose values. On the equianesthetic basis (25% effective dose, 50% effective dose, and 75% effective dose), the nociceptive block duration of proxymetacaine or oxybuprocaine was shorter than that of dopamine (P < .01). Oxybuprocaine or proxymetacaine coinjected with dopamine elicited a synergistic antinociceptive effect and extended the duration of action. Oxybuprocaine and proxymetacaine had a higher potency and provoked a shorter duration of sensory block compared with dopamine. The use of dopamine increased the quality and duration of skin antinociception caused by oxybuprocaine and proxymetacaine.

Use of fast-scan cyclic voltammetry to assess phasic dopamine release in rat models of early postpartum maternal behavior and neglect.

PubMed

Shnitko, Tatiana A; Mace, Kyla D; Sullivan, Kaitlin M; Martin, W Kyle; Andersen, Elizabeth H; Williams Avram, Sarah K; Johns, Josephine M; Robinson, Donita L

2017-12-01

Maternal behavior (MB) is a complex response to infant cues, orchestrated by postpartum neurophysiology. Although mesolimbic dopamine contributes toward MB, little is known about real-time dopamine fluctuations during the postpartum period. Thus, we used fast-scan cyclic voltammetry to measure individual dopamine transients in the nucleus accumbens of early postpartum rats and compared them with dopamine transients in virgins and in postpartum females exposed to cocaine during pregnancy, which is known to disrupt MB. We hypothesized that dopamine transients are normally enhanced postpartum and support MB. In anesthetized rats, electrically evoked dopamine release was larger and clearance was faster in postpartum females than in virgins and gestational cocaine exposure blocked the change in clearance. In awake rats, control mothers showed more dopamine transients than cocaine-exposed mothers during MB. Salient pup-produced stimuli may contribute toward differences in maternal phasic dopamine by evoking dopamine transients; supporting the feasibility of this hypothesis, urine composition (glucose, ketones, and leukocytes) differed between unexposed and cocaine-exposed infants. These data, resulting from the novel application of fast-scan cyclic voltammetry to models of MB, support the hypothesis that phasic dopamine signaling is enhanced postpartum. Future studies with additional controls can delineate which aspects of gestational cocaine reduce dopamine clearance and transient frequency.

Acute phenylalanine/tyrosine depletion of phasic dopamine in the rat brain.

PubMed

Shnitko, Tatiana A; Taylor, Sarah C; Stringfield, Sierra J; Zandy, Shannon L; Cofresí, Roberto U; Doherty, James M; Lynch, William B; Boettiger, Charlotte A; Gonzales, Rueben A; Robinson, Donita L

2016-06-01

Dopamine plays a critical role in striatal and cortical function, and depletion of the dopamine precursors phenylalanine and tyrosine is used in humans to temporarily reduce dopamine and probe the role of dopamine in behavior. This method has been shown to alter addiction-related behaviors and cognitive functioning presumably by reducing dopamine transmission, but it is unclear what specific aspects of dopamine transmission are altered. We performed this study to confirm that administration of an amino acid mixture omitting phenylalanine and tyrosine (Phe/Tyr[-]) reduces tyrosine tissue content in the prefrontal cortex (PFC) and nucleus accumbens (NAc), and to test the hypothesis that Phe/Tyr[-] administration reduces phasic dopamine release in the NAc. Rats were injected with a Phe/Tyr[-] amino acid mixture, a control amino acid mixture, or saline. High-performance liquid chromatography was used to determine the concentration of tyrosine, dopamine, or norepinephrine in tissue punches from the PFC and ventral striatum. In a separate group of rats, phasic dopamine release was measured with fast-scan cyclic voltammetry in the NAc core after injection with either the Phe/Tyr[-] mixture or the control amino acid solution. Phe/Tyr[-] reduced tyrosine content in the PFC and NAc, but dopamine and norepinephrine tissue content were not reduced. Moreover, Phe/Tyr[-] decreased the frequency of dopamine transients, but not their amplitude, in freely moving rats. These results indicate that depletion of tyrosine via Phe/Tyr[-] decreases phasic dopamine transmission, providing insight into the mechanism by which this method modifies dopamine-dependent behaviors in human imaging studies.

Systemic effects of low-dose dopamine during administration of cytarabine.

PubMed

Connelly, James; Benani, Dina J; Newman, Matthew; Burton, Bradley; Crow, Jessica; Levis, Mark

2017-09-01

Purpose Low-dose dopamine has been utilized to improve renal blood flow, urine output, and reduce drug-induced nephrotoxicity. The purpose of this study was to assess changes in renal function, cardiovascular adverse events, and neurologic toxicity in patients receiving cytarabine with or without low-dose dopamine. Methods A retrospective, single-center, cohort study of patients receiving cytarabine at 667 mg/m 2 /dose or greater, with or without dopamine at ≤5 mcg/kg/min. Cohorts were based upon initiation or absence of low-dose dopamine; cytarabine only, cytarabine + pre- and day of low-dose dopamine, and cytarabine + post-low-dose dopamine. Renal outcomes (urine output, serum creatinine, and creatinine clearance) were compared with baseline and between cohorts. Safety endpoints (arrhythmias, tachycardia, and neurotoxicity) were compared between cohorts based on low-dose dopamine exposure. Results There was no difference in urine output from baseline in all cohorts. Comparing cytarabine only and pre- and day of low-dose dopamine cohorts, there was no difference in urine output. In those receiving low-dose dopamine, there was no difference in serum creatinine and creatinine clearance from baseline. No arrhythmias were documented during the study period, and there was no difference in the incidence of tachycardia between groups (P = 0.66). Neurotoxicity was reported in three patients who were on low-dose dopamine. Conclusion Though variation existed in individual patients administered low-dose dopamine, the use of low-dose dopamine did not significantly impact renal function in this small sample at a single institution. In addition, low-dose dopamine did not negatively impact cardiovascular function.

Brain dopamine neurone 'damage': methamphetamine users vs. Parkinson's disease - a critical assessment of the evidence.

PubMed

Kish, Stephen J; Boileau, Isabelle; Callaghan, Russell C; Tong, Junchao

2017-01-01

The objective of this review is to evaluate the evidence that recreational methamphetamine exposure might damage dopamine neurones in human brain, as predicted by experimental animal findings. Brain dopamine marker data in methamphetamine users can now be compared with those in Parkinson's disease, for which the Oleh Hornykiewicz discovery in Vienna of a brain dopamine deficiency is established. Whereas all examined striatal (caudate and putamen) dopamine neuronal markers are decreased in Parkinson's disease, levels of only some (dopamine, dopamine transporter) but not others (dopamine metabolites, synthetic enzymes, vesicular monoamine transporter 2) are below normal in methamphetamine users. This suggests that loss of dopamine neurones might not be characteristic of methamphetamine exposure in at least some human drug users. In methamphetamine users, dopamine loss was more marked in caudate than in putamen, whereas in Parkinson's disease, the putamen is distinctly more affected. Substantia nigra loss of dopamine-containing cell bodies is characteristic of Parkinson's disease, but similar neuropathological studies have yet to be conducted in methamphetamine users. Similarly, it is uncertain whether brain gliosis, a common feature of brain damage, occurs after methamphetamine exposure in humans. Preliminary epidemiological findings suggest that methamphetamine use might increase risk of subsequent development of Parkinson's disease. We conclude that the available literature is insufficient to indicate that recreational methamphetamine exposure likely causes loss of dopamine neurones in humans but does suggest presence of a striatal dopamine deficiency that, in principle, could be corrected by dopamine substitution medication if safety and subject selection considerations can be resolved. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

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

PubMed

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

2015-07-01

Theoretical and animal work has proposed that prefrontal cortex (PFC) glutamate inhibits dopaminergic inputs to the ventral striatum (VS) indirectly, whereas direct VS glutamatergic afferents have been suggested to enhance dopaminergic inputs to the VS. In the present study, we aimed to investigate relationships of glutamate and dopamine measures in prefrontostriatal circuitries of healthy humans. We hypothesized that PFC and VS glutamate, as well as their balance, are differently associated with VS dopamine. Glutamate concentrations in the left lateral PFC and left striatum were assessed using 3-Tesla proton magnetic resonance spectroscopy. Striatal presynaptic dopamine synthesis capacity was measured by fluorine-18-l-dihydroxyphenylalanine (F-18-FDOPA) positron emission tomography. First, a negative relationship was observed between glutamate concentrations in lateral PFC and VS dopamine synthesis capacity (n = 28). Second, a positive relationship was revealed between striatal glutamate and VS dopamine synthesis capacity (n = 26). Additionally, the intraindividual difference between PFC and striatal glutamate concentrations correlated negatively with VS dopamine synthesis capacity (n = 24). The present results indicate an involvement of a balance in PFC and striatal glutamate in the regulation of VS dopamine synthesis capacity. This notion points toward a potential mechanism how VS presynaptic dopamine levels are kept in a fine-tuned range. A disruption of this mechanism may account for alterations in striatal dopamine turnover as observed in mental diseases (e.g., in schizophrenia). The present work demonstrates complementary relationships between prefrontal and striatal glutamate and ventral striatal presynaptic dopamine using human imaging measures: a negative correlation between prefrontal glutamate and presynaptic dopamine and a positive relationship between striatal glutamate and presynaptic dopamine are revealed. The results may reflect a regulatory role of prefrontal and striatal glutamate for ventral striatal presynaptic dopamine levels. Such glutamate-dopamine relationships improve our understanding of neurochemical interactions in prefrontostriatal circuits and have implications for the neurobiology of mental disease. Copyright © 2015 the authors 0270-6474/15/359615-07$15.00/0.

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…

Time Processing in Children with Tourette's Syndrome

ERIC Educational Resources Information Center

Vicario, Carmelo Mario; Martino, Davide; Spata, Felice; Defazio, Giovanni; Giacche, Roberta; Martino, Vito; Rappo, Gaetano; Pepi, Anna Maria; Silvestri, Paola Rosaria; Cardona, Francesco

2010-01-01

Background: Tourette syndrome (TS) is characterized by dysfunctional connectivity between prefrontal cortex and sub-cortical structures, and altered meso-cortical and/or meso-striatal dopamine release. Since time processing is also regulated by fronto-striatal circuits and modulated by dopaminergic transmission, we hypothesized that time…

The roles of cannabinoid and dopamine receptor systems in neural emotional learning circuits: implications for schizophrenia and addiction.

PubMed

Laviolette, S R; Grace, A A

2006-07-01

Cannabinoids represent one of the most widely used hallucinogenic drugs and induce profound alterations in sensory perception and emotional processing. Similarly, the dopamine (DA) neurotransmitter system is critical for the central processing of emotion and motivation. Functional disturbances in either of these neurotransmitter systems are well-established correlates of the psychopathological symptoms and behavioral manifestations observed in addiction and schizophrenia. Increasing evidence from the anatomical, pharmacological and behavioral neuroscience fields points to complex functional interactions between these receptor systems at the anatomical, pharmacological and neural systems levels. An important question relates to whether these systems act in an orchestrated manner to produce the emotional processing and sensory perception deficits underlying addiction and schizophrenia. This review describes evidence for functional neural interactions between cannabinoid and DA receptor systems and how disturbances in this neural circuitry may underlie the aberrant emotional learning and processing observed in disorders such as addiction and schizophrenia.

A review of reward processing and motivational impairment in schizophrenia.

PubMed

Strauss, Gregory P; Waltz, James A; Gold, James M

2014-03-01

This article reviews and synthesizes research on reward processing in schizophrenia, which has begun to provide important insights into the cognitive and neural mechanisms associated with motivational impairments. Aberrant cortical-striatal interactions may be involved with multiple reward processing abnormalities, including: (1) dopamine-mediated basal ganglia systems that support reinforcement learning and the ability to predict cues that lead to rewarding outcomes; (2) orbitofrontal cortex-driven deficits in generating, updating, and maintaining value representations; (3) aberrant effort-value computations, which may be mediated by disrupted anterior cingulate cortex and midbrain dopamine functioning; and (4) altered activation of the prefrontal cortex, which is important for generating exploratory behaviors in environments where reward outcomes are uncertain. It will be important for psychosocial interventions targeting negative symptoms to account for abnormalities in each of these reward processes, which may also have important interactions; suggestions for novel behavioral intervention strategies that make use of external cues, reinforcers, and mobile technology are discussed.

Dopamine Modulates the Functional Organization of the Orbitofrontal Cortex.

PubMed

Kahnt, Thorsten; Tobler, Philippe N

2017-02-08

Neuromodulators such as dopamine can alter the intrinsic firing properties of neurons and may thereby change the configuration of larger functional circuits. The primate orbitofrontal cortex (OFC) receives dopaminergic input from midbrain nuclei, but the role of dopamine in the OFC is still unclear. Here we tested the idea that dopaminergic activity changes the pattern of connectivity between the OFC and the rest of the brain and thereby reconfigures functional networks in the OFC. To this end, we combined double-blind, placebo-controlled pharmacology [D 2 receptor (D2R) antagonist amisulpride] in humans with resting-state functional magnetic resonance imaging and clustering methods. In the placebo group, we replicated previously observed parcellations of the OFC into two and six subregions based on connectivity patterns with the rest of the brain. Most importantly, while the twofold clustering did not differ significantly between groups, blocking D2Rs significantly changed the composition of the sixfold parcellation, suggesting a dopamine-dependent reconfiguration of functional OFC subregions. Moreover, multivariate decoding analyses revealed that amisulpride changed the whole-brain connectivity patterns of individual OFC subregions. In particular, D2R blockade shifted the balance of OFC connectivity from associative areas in the temporal and parietal lobe toward functional connectivity with the frontal cortex. In summary, our results suggest that dopamine alters the composition of functional OFC circuits, possibly indicating a broader role for neuromodulators in the dynamic reconfiguration of functional brain networks. SIGNIFICANCE STATEMENT A key role of any neuromodulator may be the reconfiguration of functional brain circuits. Here we test this idea with regard to dopamine and the organization of functional networks in the orbitofrontal cortex (OFC). We show that blockade of dopamine D 2 receptors has profound effects on the functional connectivity patterns of the OFC, yielding altered connectivity-based subdivisions of this region. Our results suggest that dopamine changes the connectional configuration of the OFC, possibly leading to transitions between different operating modes that favor either sensory input or recurrent processing in the prefrontal cortex. More generally, our findings support a broader role for neuromodulators in the dynamic reconfiguration of functional brain networks and may have clinical implications for understanding the actions of antipsychotic agents. Copyright © 2017 the authors 0270-6474/17/371493-12$15.00/0.

[Effects of dopamine and adenosine on regulation of water-electrolyte exchange in Amoeba proteus].

PubMed

Bagrov, Ia Iu; Manusova, N B

2014-01-01

Dopamine and adenosine both regulate transport of sodium chloride in the renal tubules in mammals. We have studied the effect of dopamine and adenosine on spontaneous activity of contractile vacuole of Amoeba proteous. Both substances stimulated contractile vacuole. The effect of dopamine was suppressed by D2 receptor antagonist, haloperidol, but not by D1 antagonist, SCH 39166. Adenylate cyclase inhibitor, 2.5-dideoxyadenosine, suppressed the effect of dopamine, but not of adenosine. Inhibitor of protein kinase C, staurosporine, in contrast, blocked the effect of adenosine, but not dopamine. Notably, dopamine opposed effect of adenosine and vice versa. These results suggest that similar effects of dopamine and adenosine could be mediated by different intracellulare mechanisms.

The Aversive Agent Lithium Chloride Suppresses Phasic Dopamine Release Through Central GLP-1 Receptors.

PubMed

Fortin, Samantha M; Chartoff, Elena H; Roitman, Mitchell F

2016-02-01

Unconditioned rewarding stimuli evoke phasic increases in dopamine concentration in the nucleus accumbens (NAc) while discrete aversive stimuli elicit pauses in dopamine neuron firing and reductions in NAc dopamine concentration. The unconditioned effects of more prolonged aversive states on dopamine release dynamics are not well understood and are investigated here using the malaise-inducing agent lithium chloride (LiCl). We used fast-scan cyclic voltammetry to measure phasic increases in NAc dopamine resulting from electrical stimulation of dopamine cell bodies in the ventral tegmental area (VTA). Systemic LiCl injection reduced electrically evoked dopamine release in the NAc of both anesthetized and awake rats. As some behavioral effects of LiCl appear to be mediated through glucagon-like peptide-1 receptor (GLP-1R) activation, we hypothesized that the suppression of phasic dopamine by LiCl is GLP-1R dependent. Indeed, peripheral pretreatment with the GLP-1R antagonist exendin-9 (Ex-9) potently attenuated the LiCl-induced suppression of dopamine. Pretreatment with Ex-9 did not, however, affect the suppression of phasic dopamine release by the kappa-opioid receptor agonist, salvinorin A, supporting a selective effect of GLP-1R stimulation in LiCl-induced dopamine suppression. By delivering Ex-9 to either the lateral or fourth ventricle, we highlight a population of central GLP-1 receptors rostral to the hindbrain that are involved in the LiCl-mediated suppression of NAc dopamine release.

Frequency-Dependent Modulation of Dopamine Release by Nicotine and Dopamine D1 Receptor Ligands: An In Vitro Fast Cyclic Voltammetry Study in Rat Striatum.

PubMed

Goutier, W; Lowry, J P; McCreary, A C; O'Connor, J J

2016-05-01

Nicotine is a highly addictive drug and exerts this effect partially through the modulation of dopamine release and increasing extracellular dopamine in regions such as the brain reward systems. Nicotine acts in these regions on nicotinic acetylcholine receptors. The effect of nicotine on the frequency dependent modulation of dopamine release is well established and the purpose of this study was to investigate whether dopamine D1 receptor (D1R) ligands have an influence on this. Using fast cyclic voltammetry and rat corticostriatal slices, we show that D1R ligands are able to modulate the effect of nicotine on dopamine release. Nicotine (500 nM) induced a decrease in dopamine efflux at low frequency (single pulse or five pulses at 10 Hz) and an increase at high frequency (100 Hz) electrical field stimulation. The D1R agonist SKF-38393, whilst having no effect on dopamine release on its own or on the effect of nicotine upon multiple pulse evoked dopamine release, did significantly prevent and reverse the effect of nicotine on single pulse dopamine release. Interestingly similar results were obtained with the D1R antagonist SCH-23390. In this study we have demonstrated that the modulation of dopamine release by nicotine can be altered by D1R ligands, but only when evoked by single pulse stimulation, and are likely working via cholinergic interneuron driven dopamine release.

Greater Ethanol Inhibition of Presynaptic Dopamine Release in C57BL/6J than DBA/2J Mice: Role of Nicotinic Acetylcholine Receptors

PubMed Central

Yorgason, Jordan T.; Rose, Jamie H.; McIntosh, J. Michael; Ferris, Mark J.; Jones, Sara R.

2014-01-01

The mesolimbic dopamine system, originating in the ventral tegmental area (VTA) and projecting to the nucleus accumbens (NAc), has been heavily implicated in the reinforcing effects of ethanol. Recent slice voltammetry studies have shown that ethanol inhibits dopamine release selectively during highfrequency activity that elicits phasic dopamine release shown to be important for learning and reinforcement. Presently, we examined ethanol inhibition of electrically evoked NAc dopamine in two mouse strains with divergent dopamine responses to ethanol, C57BL/6 (C57) and DBA/2J (DBA) mice. Previous electrophysiology and microdialysis studies have demonstrated greater ethanol induced VTA dopaminergic firing and NAc dopamine elevations in DBA compared to C57 mice. Additionally, DBA mice have greater ethanol responses in dopamine-related behaviors, including hyperlocomotion and conditioned place preference. Currently, we demonstrate greater sensitivity of ethanol inhibition of NAc dopamine signaling in C57 compared to DBA mice. The reduced sensitivity to ethanol inhibition in DBA mice may contribute to the overall greater ethanol-induced dopamine signaling and related behaviors observed in this strain. NAc cholinergic activity is known to potently modulate terminal dopamine release. Additionally, ethanol is known to interact with multiple aspects of nicotinic acetylcholine receptor activity. Therefore, we examined ethanol-mediated inhibition of dopamine release at two ethanol concentrations (80 and 160mM) during bath application of the non-selective nicotinic receptor antagonist mecamylamine, as well as compounds selective for the β2- (DhβE) and α6- (α-conotoxin MII [H9A; L15A]) subunit-containing receptors. Mecamylamine and DhβE decreased dopamine release and reduced ethanol's inhibitory effects on dopamine in both DBA and C57 mice. Further, α-conotoxin also reduced the dopamine release and the dopamine-inhibiting effects of ethanol at the 80mM, but not 160mM, concentration. These data suggest that ethanol is acting in part through nicotinic acetylcholine receptors, or downstream effectors, to reduce dopamine release during high-frequency activity. PMID:25451295

Effects of Modafinil on Dopamine and Dopamine Transporters in the Male Human Brain: Clinical Implications

PubMed Central

Volkow, Nora D.; Fowler, Joanna S.; Logan, Jean; Alexoff, David; Zhu, Wei; Telang, Frank; Wang, Gene-Jack; Jayne, Millard; Hooker, Jacob M.; Wong, Christopher; Hubbard, Barbara; Carter, Pauline; Warner, Donald; King, Payton; Shea, Colleen; Xu, Youwen; Muench, Lisa; Apelskog-Torres, Karen

2009-01-01

Context Modafinil, a wake-promoting drug used to treat narcolepsy, is increasingly being used as a cognitive enhancer. Although initially launched as distinct from stimulants that increase extracellular dopamine by targeting dopamine transporters, recent preclinical studies suggest otherwise. Objective To measure the acute effects of modafinil at doses used therapeutically (200 mg and 400 mg given orally) on extracellular dopamine and on dopamine transporters in the male human brain. Design, Setting, and Participants Positron emission tomography with [11C]raclopride (D2/D3 radioligand sensitive to changes in endogenous dopamine) and [11C]cocaine (dopamine transporter radioligand) was used to measure the effects of modafinil on extracellular dopamine and on dopamine transporters in 10 healthy male participants. The study took place over an 8-month period (2007–2008) at Brookhaven National Laboratory. Main Outcome Measures Primary outcomes were changes in dopamine D2/D3 receptor and dopamine transporter availability (measured by changes in binding potential) after modafinil when compared with after placebo. Results Modafinil decreased mean (SD) [11C]raclopride binding potential in caudate (6.1% [6.5%]; 95% confidence interval [CI], 1.5% to 10.8%; P=.02), putamen (6.7% [4.9%]; 95% CI, 3.2% to 10.3%; P=.002), and nucleus accumbens (19.4% [20%]; 95% CI, 5% to 35%; P=.02), reflecting increases in extracellular dopamine. Modafinil also decreased [11C]cocaine binding potential in caudate (53.8% [13.8%]; 95% CI, 43.9% to 63.6%; P<.001), putamen (47.2% [11.4%]; 95% CI, 39.1% to 55.4%; P<.001), and nucleus accumbens (39.3% [10%]; 95% CI, 30% to 49%; P=.001), reflecting occupancy of dopamine transporters. Conclusions In this pilot study, modafinil blocked dopamine transporters and increased dopamine in the human brain (including the nucleus accumbens). Because drugs that increase dopamine in the nucleus accumbens have the potential for abuse, and considering the increasing use of modafinil, these results highlight the need for heightened awareness for potential abuse of and dependence on modafinil in vulnerable populations. PMID:19293415

Remembering the time: a continuous clock.

PubMed

Lewis, Penelope A; Miall, R Chris

2006-09-01

The neural mechanisms for time measurement are currently a subject of much debate. This article argues that our brains can measure time using the same dorsolateral prefrontal cells that are known to be involved in working memory. Evidence for this is: (1) the dorsolateral prefrontal cortex is integral to both cognitive timing and working memory; (2) both behavioural processes are modulated by dopamine and disrupted by manipulation of dopaminergic projections to the dorsolateral prefrontal cortex; (3) the neurons in question ramp their activity in a temporally predictable way during both types of processing; and (4) this ramping activity is modulated by dopamine. The dual involvement of these prefrontal neurons in working memory and cognitive timing supports a view of the prefrontal cortex as a multipurpose processor recruited by a wide variety of tasks.

Breast Cancer-Targeted Nuclear Drug Delivery Overcoming Drug Resistance for Breast Cancer Chemotherapy

DTIC Science & Technology

2012-09-01

A. A.; Menger, F. M. Adv. Colloid Interfac. 2008, 142, (1-2), 43-52. 9. Obata, Y.; Suzuki, D.; Takeoka , S. Bioconjugate Chem. 2008, 19, (5), 1055...4434-4447. 113. Takeoka , S.; Mori, K.; Ohkawa, H.; Sou, K.; Tsuchida, E. J. Am. Chem. Soc. 2000, 122, (33), 7927-7935. 114. Pati, D.; Kalva, N.; Das, S

A Partnership Training Program in Breast Cancer Research Using Molecular Imaging Techniques

DTIC Science & Technology

2007-07-01

polyethylenimine /DNA complexes for systemic tumor-targeted gene transfer. Bioconjugate Chem 2003;14:222–31. 22. Simoes S, Pires P, Duzgunes N, Pedroso de Lima M...determination of intracellular NO release. Culture and drug treatment(s) of cells were carried out at 37°C in an atmosphere of 5% CO2 and 95% air

Modification of aniline containing proteins using an oxidative coupling strategy.

PubMed

Hooker, Jacob M; Esser-Kahn, Aaron P; Francis, Matthew B

2006-12-13

A new bioconjugation reaction has been developed based on the chemoselective modification of anilines through an oxidative coupling pathway. Aryl amines were installed on the surface of protein substrates through lysine acylation reactions or through the use of native chemical ligation techniques. Upon exposure to NaIO4 in aqueous buffer, the anilines coupled rapidly to the aromatic rings of N,N-dialkyl-N'-acyl-p-phenylenediamines. The identities of the reaction products were confirmed using ESI-MS and through comparison to small molecule analogs. Control experiments indicated that none of the native amino acids participated in the reaction. The resulting bioconjugates were found to be stable toward hydrolysis from pH 4 to pH 11 and in the presence of many commonly used oxidants, reductants, and nucleophiles. A fluorescent phenylenediamine reagent was synthesized for the selective detection of aniline labeled proteins in mixtures, and the reaction was used to append the C-terminus of the green fluorescent protein with a single PEG chain. When combined with techniques for the incorporation of unnatural amino acids into proteins, this bioorthogonal coupling method should prove useful for a number of applications requiring a high degree of labeling specificity.

Bioconjugate functionalization of thermally carbonized porous silicon using a radical coupling reaction†

PubMed Central

Sciacca, Beniamino; Alvarez, Sara D.; Geobaldo, Francesco; Sailor, Michael J.

2011-01-01

The high stability of Salonen’s thermally carbonized porous silicon (TCPSi) has attracted attention for environmental and biochemical sensing applications, where corrosion-induced zero point drift of porous silicon-based sensor elements has historically been a significant problem. Prepared by the high temperature reaction of porous silicon with acetylene gas, the stability of this silicon carbide-like material also poses a challenge—many sensor applications require a functionalized surface, and the low reactivity of TCPSi has limited the ability to chemically modify its surface. This work presents a simple reaction to modify the surface of TCPSi with an alkyl carboxylate. The method involves radical coupling of a dicarboxylic acid (sebacic acid) to the TCPSi surface using a benzoyl peroxide initiator. The grafted carboxylic acid species provides a route for bioconjugate chemical modification, demonstrated in this work by coupling propylamine to the surface carboxylic acid group through the intermediacy of pentafluorophenol and 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC). The stability of the carbonized porous Si surface, both before and after chemical modification, is tested in phosphate buffered saline solution and found to be superior to either hydrosilylated (with undecylenic acid) or thermally oxidized porous Si surfaces. PMID:20967329

Bioconjugated fluorescent silica nanoparticles for the rapid detection of Entamoeba histolytica.

PubMed

Hemadi, Ahmad; Ekrami, Alireza; Oormazdi, Hormozd; Meamar, Ahmad Reza; Akhlaghi, Lame; Samarbaf-Zadeh, Ali Reza; Razmjou, Elham

2015-05-01

Rapid detection of Entamoeba histolytica based on fluorescent silica nanoparticle (FSNP) indirect immunofluorescence microscopy was evaluated. Silica nanoparticles were synthesized using Stöber's method, with their surface activated to covalently bind to, and immobilize, protein A. For biolabeling, FSNP was added to conjugated E. histolytica trophozoites with monoclonal anti-E. histolytica IgG1 for microscopic observation of fluorescence. Fluorescent silica nanoparticle sensitivity was determined with axenically cultured E. histolytica serially diluted to seven concentrations. Specificity was evaluated using other intestinal protozoa. Fluorescent silica nanoparticles detected E. histolytica at the lowest tested concentration with no cross-reaction with Entamoeba dispar, Entamoeba moshkovskii, Blastocystis sp., or Giardia lamblia. Visualization of E. histolytica trophozoites with anti-E. histolytica antibody labeled with fluorescein isothiocyanate (FITC) was compared with that using anti-E. histolytica antibody bioconjugated FSNP. Although FITC and FSNP produced similar results, the amount of specific antibody required for FITC to induce fluorescence of similar intensity was fivefold that for FSNP. Fluorescent silica nanoparticles delivered a rapid, simple, cost-effective, and highly sensitive and specific method of detecting E. histolytica. Further study is needed before introducing FSNP for laboratory diagnosis of amoebiasis. Copyright © 2015 Elsevier B.V. All rights reserved.

Solid-Binding Peptides in Biomedicine.

PubMed

Care, Andrew; Bergquist, Peter L; Sunna, Anwar

2017-01-01

Some peptides are able to bind to inorganic materials such as silica and gold. Over the past decade, Solid-binding peptides (SBPs) have been used increasingly as molecular building blocks in nanobiotechnology. These peptides show selectivity and bind with high affinity to a diverse range of inorganic surfaces e.g. metals, metal oxides, metal compounds, magnetic materials, semiconductors, carbon materials, polymers and minerals. They can be used in applications such as protein purification and synthesis, assembly and the functionalization of nanomaterials. They offer simple and versatile bioconjugation methods that can increase biocompatibility and also direct the immobilization and orientation of nanoscale entities onto solid supports without impeding their functionality. SBPs have been employed in numerous nanobiotechnological applications such as the controlled synthesis of nanomaterials and nanostructures, formation of hybrid biomaterials, immobilization of functional proteins and improved nanomaterial biocompatibility. With advances in nanotechnology, a multitude of novel nanomaterials have been designed and synthesized for diagnostic and therapeutic applications. New approaches have been developed recently to exert a greater control over bioconjugation and eventually, over the optimal and functional display of biomolecules on the surfaces of many types of solid materials. In this chapter we describe SBPs and highlight some selected examples of their potential applications in biomedicine.

Cetuximab-conjugated nanodiamonds drug delivery system for enhanced targeting therapy and 3D Raman imaging.

PubMed

Li, Dandan; Chen, Xin; Wang, Hong; Liu, Jie; Zheng, Meiling; Fu, Yang; Yu, Yuan; Zhi, Jinfang

2017-12-01

In this study, a multicomponent nanodiamonds (NDs)-based targeting drug delivery system, cetuximab-NDs-cisplatin bioconjugate, combining both specific targeting and enhanced therapeutic efficacy capabilities, is developed and characterized. The specific targeting ability of cetuximab-NDs-cisplatin system on human liver hepatocellular carcinoma (HepG2) cells is evaluated through epidermal growth factor receptor (EGFR) blocking experiments, since EGFR is over-expressed on HepG2 cell membrane. Besides, cytotoxic evaluation confirms that cetuximab-NDs-cisplatin system could significantly inhibit the growth of HepG2 cells, and the therapeutic activity of this system is proven to be better than that of both nonspecific NDs-cisplatin conjugate and specific EGF-NDs-cisplatin conjugate. Furthermore, a 3-dimensional (3D) Raman imaging technique is utilized to visualize the targeting efficacy and enhanced internalization of cetuximab-NDs-cisplatin system in HepG2 cells, using the NDs existing in the bioconjugate as Raman probes, based on the characteristic Raman signal of NDs at 1332 cm -1 . These advantageous properties of cetuximab-NDs-cisplatin system propose a prospective imaging and treatment tool for further diagnostic and therapeutic purposes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced dopamine D2 autoreceptor function in the adult prefrontal cortex contributes to dopamine hypoactivity following adolescent social stress.

PubMed

Weber, Matthew A; Graack, Eric T; Scholl, Jamie L; Renner, Kenneth J; Forster, Gina L; Watt, Michael J

2018-06-14

Adult psychiatric disorders characterized by cognitive deficits reliant on prefrontal cortex (PFC) dopamine are promoted by teenage bullying. Similarly, male Sprague-Dawley rats exposed to social defeat in mid-adolescence (P35-39) show impaired working memory in adulthood (P56-70), along with decreased medial PFC (mPFC) dopamine activity that results in part from increased dopamine transporter-mediated clearance. Here, we determined if dopamine synthesis and D2 autoreceptor-mediated inhibition of dopamine release in the adult mPFC are also enhanced by adolescent defeat to contribute to later dopamine hypofunction. Control and previously defeated rats did not differ in either DOPA accumulation following amino acid decarboxylase inhibition (NSD-1015 100 mg/kg ip.) or total/phosphorylated tyrosine hydroxylase protein expression, suggesting dopamine synthesis in the adult mPFC is not altered by adolescent defeat. However, exposure to adolescent defeat caused greater decreases in extracellular dopamine release (measured using in vivo chronoamperometry) in the adult mPFC upon local infusion of the D2 receptor agonist quinpirole (3 nM), implying greater D2 autoreceptor function. Equally enhanced D2 autoreceptor-mediated inhibition of dopamine release is seen in the adolescent (P40 or P49) mPFC, which declines in control rats by adulthood. However, this developmental decrease in autoreceptor function is absent following adolescent defeat, suggesting retention of an adolescent-like phenotype into adulthood. Current and previous findings indicate adolescent defeat decreases extracellular dopamine availability in the adult mPFC via both enhanced inhibition of dopamine release and increased dopamine clearance, which may be viable targets for improving treatment of cognitive deficits seen in neuropsychiatric disorders promoted by adolescent stress. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Blockade of dopamine D1-family receptors attenuates the mania-like hyperactive, risk-preferring, and high motivation behavioral profile of mice with low dopamine transporter levels.

PubMed

Milienne-Petiot, Morgane; Groenink, Lucianne; Minassian, Arpi; Young, Jared W

2017-10-01

Patients with bipolar disorder mania exhibit poor cognition, impulsivity, risk-taking, and goal-directed activity that negatively impact their quality of life. To date, existing treatments for bipolar disorder do not adequately remediate cognitive dysfunction. Reducing dopamine transporter expression recreates many bipolar disorder mania-relevant behaviors (i.e. hyperactivity and risk-taking). The current study investigated whether dopamine D 1 -family receptor blockade would attenuate the risk-taking, hypermotivation, and hyperactivity of dopamine transporter knockdown mice. Dopamine transporter knockdown and wild-type littermate mice were tested in mouse versions of the Iowa Gambling Task (risk-taking), Progressive Ratio Breakpoint Test (effortful motivation), and Behavioral Pattern Monitor (activity). Prior to testing, the mice were treated with the dopamine D 1 -family receptor antagonist SCH 23390 hydrochloride (0.03, 0.1, or 0.3 mg/kg), or vehicle. Dopamine transporter knockdown mice exhibited hyperactivity and hyperexploration, hypermotivation, and risk-taking preference compared with wild-type littermates. SCH 23390 hydrochloride treatment decreased premature responding in dopamine transporter knockdown mice and attenuated their hypermotivation. SCH 23390 hydrochloride flattened the safe/risk preference, while reducing activity and exploratory levels of both genotypes similarly. Dopamine transporter knockdown mice exhibited mania-relevant behavior compared to wild-type mice. Systemic dopamine D 1 -family receptor antagonism attenuated these behaviors in dopamine transporter knockdown, but not all effects were specific to only the knockdown mice. The normalization of behavior via blockade of dopamine D 1 -family receptors supports the hypothesis that D 1 and/or D 5 receptors could contribute to the mania-relevant behaviors of dopamine transporter knockdown mice.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Qing; Shao, Mingwang, E-mail: mwshao@suda.edu.cn; Chen, Tao

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

Nuclear medicine and imaging research (quantitative studies in radiopharmaceutical science). Progress report, January 1, 1992--December 31, 1992

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooper, M.; Beck, R.N.

1992-06-01

This report describes three studies aimed at using radiolabeled pharmaceuticals to explore brain function and anatomy. The first section describes the chemical preparation of [F18]fluorinated benzamides (dopamine D-2 receptor tracers), [F18]fluorinated benzazepines (dopamine D-1 receptor tracers), and tissue distribution of [F18]-fluoxetine (serotonin reuptake site tracer). The second section relates pharmacological and behavioral studies of amphetamines. The third section reports on progress made with processing of brain images from CT, MRI and PET/SPECT with regards to brain metabolism of glucose during mental tasks.

Parkinson's disease-associated melanin steal.

PubMed

Hinz, Marty; Stein, Alvin; Cole, Ted

2014-01-01

Urinary dopamine fluctuations in the competitive inhibition state were first documented in 2009. At that time, it was noted that progressively higher daily dosing values of L-tyrosine decreased the magnitude of these fluctuations. While extensive statistical analysis has been performed by the authors since 2004, it was not until 2012 that a plausible explanation was formulated. In the process, correlations with L-tyrosine administration and the on/off effect of Parkinson's disease were defined. This paper documents the current knowledge with regard to the management of retrograde phase 1 dopamine fluctuations and investigates the hypothesis that they are caused by a melanin steal phenomenon.

Enhanced Striatal Dopamine Release During Food Stimulation in Binge Eating Disorder

PubMed Central

Wang, Gene-Jack; Geliebter, Allan; Volkow, Nora D.; Telang, Frank W.; Logan, Jean; Jayne, Millard C.; Galanti, Kochavi; Selig, Peter A.; Han, Hao; Zhu, Wei; Wong, Christopher T.; Fowler, Joanna S.

2011-01-01

Subjects with binge eating disorder (BED) regularly consume large amounts of food in short time periods. The neurobiology of BED is poorly understood. Brain dopamine, which regulates motivation for food intake, is likely to be involved. We assessed the involvement of brain dopamine in the motivation for food consumption in binge eaters. Positron emission tomography (PET) scans with [11C]raclopride were done in 10 obese BED and 8 obese subjects without BED. Changes in extracellular dopamine in the striatum in response to food stimulation in food-deprived subjects were evaluated after placebo and after oral methylphenidate (MPH), a drug that blocks the dopamine reuptake transporter and thus amplifies dopamine signals. Neither the neutral stimuli (with or without MPH) nor the food stimuli when given with placebo increased extracellular dopamine. The food stimuli when given with MPH significantly increased dopamine in the caudate and putamen in the binge eaters but not in the nonbinge eaters. Dopamine increases in the caudate were significantly correlated with the binge eating scores but not with BMI. These results identify dopamine neurotransmission in the caudate as being of relevance to the neurobiology of BED. The lack of correlation between BMI and dopamine changes suggests that dopamine release per se does not predict BMI within a group of obese individuals but that it predicts binge eating. PMID:21350434

Microencapsulation of dopamine neurons derived from human induced pluripotent stem cells.

PubMed

Konagaya, Shuhei; Iwata, Hiroo

2015-01-01

Dopamine neurons derived from induced pluripotent stem cells have been widely studied for the treatment of Parkinson's disease. However, various difficulties remain to be overcome, such as tumor formation, fragility of dopamine neurons, difficulty in handling large numbers of dopamine neurons, and immune reactions. In this study, human induced pluripotent stem cell-derived precursors of dopamine neurons were encapsulated in agarose microbeads. Dopamine neurons in microbeads could be handled without specific protocols, because the microbeads protected the fragile dopamine neurons from mechanical stress. hiPS cells were seeded on a Matrigel-coated dish and cultured to induce differentiation into a dopamine neuronal linage. On day 18 of culture, cells were collected from the culture dishes and seeded into U-bottom 96-well plates to induce cell aggregate formation. After 5 days, cell aggregates were collected from the plates and microencapsulated in agarose microbeads. The microencapsulated aggregates were cultured for an additional 45 days to induce maturation of dopamine neurons. Approximately 60% of all cells differentiated into tyrosine hydroxylase-positive neurons in agarose microbeads. The cells released dopamine for more than 40 days. In addition, microbeads containing cells could be cryopreserved. hiPS cells were successfully differentiated into dopamine neurons in agarose microbeads. Agarose microencapsulation provides a good supporting environment for the preparation and storage of dopamine neurons. Copyright © 2014 Elsevier B.V. All rights reserved.

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

Renal dopamine containing nerves. What is their functional significance?

PubMed

DiBona, G F

1990-06-01

Biochemical and morphological studies indicate that there are nerves within the kidney that contain dopamine and that various structures within the kidney contain dopamine receptors. However, the functional significance of these renal dopamine containing nerves in relation to renal dopamine receptors is unknown. The functional significance could be defined by demonstrating that an alteration in one or more renal functions occurring in response to reflex or electrical activation of efferent renal nerves is dependent on release of dopamine as the neurotransmitter from the renal nerve terminals acting on renal dopamine receptors. Thus, the hypothesis becomes: reflex or electrical activation of efferent renal nerves causes alterations in renal function (eg, renal blood flow, water and solute handling) that are inhibited by specific and selective dopamine receptor antagonists. As reviewed herein, the published experimental data do not support the hypothesis. Therefore, the view that alterations in one or more renal functions occurring in response to reflex or electrical activation of efferent renal nerves are dependent on release of dopamine as the neurotransmitter from the renal nerve terminals acting on renal dopamine receptors remains unproven.

Monoamines stimulate sex reversal in the saddleback wrasse.

PubMed

Larson, Earl T; Norris, David O; Gordon Grau, E; Summers, Cliff H

2003-02-15

Monoamine neurotransmitters (norepinephrine, dopamine, and serotonin) play an important role in reproduction and sexual behavior throughout the vertebrates. They are the first endogenous chemical signals in the regulation of the hypothalamo-pituitary-gonadal (HPG) axis. In teleosts with behavioral sex determination, much is known about behavioral cues that induce sex reversal. The cues are social, processed via the visual system and depend on the ratio of females to males in the population. The mechanisms by which these external behavioral cues are converted to an internal chemical regulatory process are largely unknown. The protogynous Hawaiian saddleback wrasse, Thalassoma duperrey, was used to investigate the biological pathway mediating the conversion of a social cue into neuroendocrine events regulating sex reversal. Because monoamines play an important role in the regulation of the HPG axis, they were selected as likely candidates for such a conversion. To determine if monoamines could affect sex reversal, drugs affecting monoamines were used in an attempt to either induce sex reversal under non-permissive conditions, or prevent sex reversal under permissive conditions. Increasing norepinephrine or blocking dopamine or serotonin lead to sex reversal in experimental animals under non-permissive conditions. Increasing serotonin blocked sex reversal under permissive conditions, while blocking dopamine or norepinephrine retarded the process. The results presented here demonstrate that monoamines contribute significantly to the control sex reversal. Norepinephrine stimulates initiation and completion of gonadal sex of reversal as well as color change perhaps directly via its effects on the HPG axis. Dopamine exercises inhibitory action on the initiation of sex reversal while 5-HT inhibits both initiation and completion of sex reversal. The serotonergic system appears to be an integral part of the pathway mediating the conversion of a social cue into a neuroendocrine event. The complex organization of neurochemical events controlling the psychosocial, physiological, and anatomical events that constitute reversal of sexual identity includes monoamine neurotransmitters. Copyright 2003 Elsevier Science (USA)

Dopamine-Induced Apoptosis of Lactotropes Is Mediated by the Short Isoform of D2 Receptor

PubMed Central

Radl, Daniela Betiana; Ferraris, Jimena; Boti, Valeria; Seilicovich, Adriana; Sarkar, Dipak Kumar; Pisera, Daniel

2011-01-01

Dopamine, through D2 receptor (D2R), is the major regulator of lactotrope function in the anterior pituitary gland. Both D2R isoforms, long (D2L) and short (D2S), are expressed in lactotropes. Although both isoforms can transduce dopamine signal, they differ in the mechanism that leads to cell response. The administration of D2R agonists, such as cabergoline, is the main pharmacological treatment for prolactinomas, but resistance to these drugs exists, which has been associated with alterations in D2R expression. We previously reported that dopamine and cabergoline induce apoptosis of lactotropes in primary culture in an estrogen-dependent manner. In this study we used an in vivo model to confirm the permissive action of estradiol in the apoptosis of anterior pituitary cells induced by D2R agonists. Administration of cabergoline to female rats induced apoptosis, measured by Annexin-V staining, in anterior pituitary gland from estradiol-treated rats but not from ovariectomized rats. To evaluate the participation of D2R isoforms in the apoptosis induced by dopamine we used lactotrope-derived PR1 cells stably transfected with expression vectors encoding D2L or D2S receptors. In the presence of estradiol, dopamine induced apoptosis, determined by ELISA and TUNEL assay, only in PR1-D2S cells. To study the role of p38 MAPK in apoptosis induced by D2R activation, anterior pituitary cells from primary culture or PR1-D2S were incubated with an inhibitor of the p38 MAPK pathway (SB203850). SB203580 blocked the apoptotic effect of D2R activation in lactotropes from primary cultures and PR1-D2S cells. Dopamine also induced p38 MAPK phosphorylation, determined by western blot, in PR1-D2S cells and estradiol enhanced this effect. These data suggest that, in the presence of estradiol, D2R agonists induce apoptosis of lactotropes by their interaction with D2S receptors and that p38 MAPK is involved in this process. PMID:21464994

Dopamine-induced apoptosis of lactotropes is mediated by the short isoform of D2 receptor.

PubMed

Radl, Daniela Betiana; Ferraris, Jimena; Boti, Valeria; Seilicovich, Adriana; Sarkar, Dipak Kumar; Pisera, Daniel

2011-03-25

Dopamine, through D2 receptor (D2R), is the major regulator of lactotrope function in the anterior pituitary gland. Both D2R isoforms, long (D2L) and short (D2S), are expressed in lactotropes. Although both isoforms can transduce dopamine signal, they differ in the mechanism that leads to cell response. The administration of D2R agonists, such as cabergoline, is the main pharmacological treatment for prolactinomas, but resistance to these drugs exists, which has been associated with alterations in D2R expression. We previously reported that dopamine and cabergoline induce apoptosis of lactotropes in primary culture in an estrogen-dependent manner. In this study we used an in vivo model to confirm the permissive action of estradiol in the apoptosis of anterior pituitary cells induced by D2R agonists. Administration of cabergoline to female rats induced apoptosis, measured by Annexin-V staining, in anterior pituitary gland from estradiol-treated rats but not from ovariectomized rats. To evaluate the participation of D2R isoforms in the apoptosis induced by dopamine we used lactotrope-derived PR1 cells stably transfected with expression vectors encoding D2L or D2S receptors. In the presence of estradiol, dopamine induced apoptosis, determined by ELISA and TUNEL assay, only in PR1-D2S cells. To study the role of p38 MAPK in apoptosis induced by D2R activation, anterior pituitary cells from primary culture or PR1-D2S were incubated with an inhibitor of the p38 MAPK pathway (SB203850). SB203580 blocked the apoptotic effect of D2R activation in lactotropes from primary cultures and PR1-D2S cells. Dopamine also induced p38 MAPK phosphorylation, determined by western blot, in PR1-D2S cells and estradiol enhanced this effect. These data suggest that, in the presence of estradiol, D2R agonists induce apoptosis of lactotropes by their interaction with D2S receptors and that p38 MAPK is involved in this process.

Sub-second changes in accumbal dopamine during sexual behavior in male rats.

PubMed

Robinson, D L; Phillips, P E; Budygin, E A; Trafton, B J; Garris, P A; Wightman, R M

2001-08-08

Transient (200--900 ms), high concentrations (200--500 nM) of dopamine, measured using fast-scan cyclic voltammetry, occurred in the nucleus accumbens core of male rats at the presentation of a receptive female. Additional dopamine signals were observed during subsequent approach behavior. Background-subtracted cyclic voltammograms of the naturally-evoked signals matched those of electrically-evoked dopamine measured at the same recording sites. Administration of nomifensine amplified natural and evoked dopamine release, and increased the frequency of detectable signals. While gradual changes in dopamine concentration during sexual behavior have been well established, these findings dramatically improve the time resolution. The observed dopamine transients, probably resulting from neuronal burst firing, represent the first direct correlation of dopamine with sexual behavior on a sub-second time scale.

Distribution of messenger RNAs for D1 dopamine receptors and DARPP-32 in striatum and cerebral cortex of the cynomolgus monkey: relationship to D1 dopamine receptors.

PubMed

Brené, S; Hall, H; Lindefors, N; Karlsson, P; Halldin, C; Sedvall, G

1995-07-01

Messenger RNAs for the D1 dopamine receptor and dopamine- and cyclic AMP-regulated phosphoprotein of relative mass 32,000 (DARPP-32) were examined by in situ hybridization in the cynomolgus monkey brain. The messenger RNA distribution was compared to the distribution of D1 dopamine receptors using [3H]SCH 23390 autoradiography. In the caudate nucleus and putamen, D1 dopamine receptor messenger RNA-positive cells were unevenly distributed. Clusters of cells with an approximately three-fold higher intensity of labeling, as compared to surrounding regions, were found. Some of these D1 dopamine receptor messenger RNA intensive cell clusters in the caudate nucleus appeared to some extent to be matched to regions of higher intensity of [3H]SCH 23390 binding. The distribution of cells expressing DARPP-32 messenger RNA in the caudate nucleus and putamen was found to be non-clustered. In neocortical regions, cells of different sizes expressing D1 dopamine receptor messenger RNA were present in layers II-VI. D1 dopamine receptor messenger RNA-positive cells were most abundant in layer V. Unexpectedly, no DARPP-32 messenger RNA signal was detected in neocortex. Chronic SCH 23390 administration did not change the relative levels of messenger RNAs for the D1 dopamine receptor and DARPP-32 or [3H]SCH 23390 binding as measured by quantitative image analysis. The clustered distribution of D1 dopamine receptor messenger RNA is in contrast to that of DARPP-32 messenger RNA. This suggests that D1 dopamine receptors may play a more significant role in regulating DARPP-32 function in patch regions as compared to matrix regions. D1 dopamine receptor messenger RNA-expressing cells could also be visualized in several layers of the primate neocortex, implying that dopamine acts through D1 dopamine receptors within functionally different neuronal circuits of the neocortex.

Consequences of peripheral chemoreflex inhibition with low-dose dopamine in humans

PubMed Central

Niewinski, Piotr; Tubek, Stanislaw; Banasiak, Waldemar; Paton, Julian F R; Ponikowski, Piotr

2014-01-01

Low-dose dopamine inhibits peripheral chemoreceptors and attenuates the hypoxic ventilatory response (HVR) in humans. However, it is unknown: (1) whether it also modulates the haemodynamic reactions to acute hypoxia, (2) whether it also modulates cardiac baroreflex sensitivity (BRS) and (3) if there is any effect of dopamine withdrawal. We performed a double-blind, placebo-controlled study on 11 healthy male volunteers. At sea level over 2 days every subject was administered low-dose dopamine (2 μg kg–1 min–1) or saline infusion, during which we assessed both ventilatory and haemodynamic responses to acute hypoxia. Separately, we evaluated effects of initiation and withdrawal of each infusion and BRS. The initiation of dopamine infusion did not affect minute ventilation (MV) or mean blood pressure (MAP), but increased both heart rate (HR) and cardiac output. Concomitantly, it decreased systemic vascular resistance. Dopamine blunted the ventilatory, MAP and HR reactions (hypertension, tachycardia) to acute hypoxia. Dopamine attenuated cardiac BRS to falling blood pressure. Dopamine withdrawal evoked an increase in MV. The magnitude of the increment in MV due to dopamine withdrawal correlated with the size of the HVR and depended on the duration of dopamine administration. The ventilatory reaction to dopamine withdrawal constitutes a novel index of peripheral chemoreceptor function. PMID:24396060

Excessive D1 Dopamine Receptor Activation in the Dorsal Striatum Promotes Autistic-Like Behaviors.

PubMed

Lee, Yunjin; Kim, Hannah; Kim, Ji-Eun; Park, Jin-Young; Choi, Juli; Lee, Jung-Eun; Lee, Eun-Hwa; Han, Pyung-Lim

2018-07-01

The dopamine system has been characterized in motor function, goal-directed behaviors, and rewards. Recent studies recognize various dopamine system genes as being associated with autism spectrum disorder (ASD). However, how dopamine system dysfunction induces ASD pathophysiology remains unknown. In the present study, we demonstrated that mice with increased dopamine functions in the dorsal striatum via the suppression of dopamine transporter expression in substantia nigra neurons or the optogenetic stimulation of the nigro-striatal circuitry exhibited sociability deficits and repetitive behaviors relevant to ASD pathology in animal models, while these behavioral changes were blocked by a D1 receptor antagonist. Pharmacological activation of D1 dopamine receptors in normal mice or the genetic knockout (KO) of D2 dopamine receptors also produced typical autistic-like behaviors. Moreover, the siRNA-mediated inhibition of D2 dopamine receptors in the dorsal striatum was sufficient to replicate autistic-like phenotypes in D2 KO mice. Intervention of D1 dopamine receptor functions or the signaling pathways-related D1 receptors in D2 KO mice produced anti-autistic effects. Together, our results indicate that increased dopamine function in the dorsal striatum promotes autistic-like behaviors and that the dorsal striatum is the neural correlate of ASD core symptoms.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, g.j.; Wang, G.-J.; Geliebter, A.

Subjects with binge eating disorder (BED) regularly consume large amounts of food in short time periods. The neurobiology of BED is poorly understood. Brain dopamine, which regulates motivation for food intake, is likely to be involved. We assessed the involvement of brain dopamine in the motivation for food consumption in binge eaters. Positron emission tomography (PET) scans with [{sup 11}C]raclopride were done in 10 obese BED and 8 obese subjects without BED. Changes in extracellular dopamine in the striatum in response to food stimulation in food-deprived subjects were evaluated after placebo and after oral methylphenidate (MPH), a drug that blocksmore » the dopamine reuptake transporter and thus amplifies dopamine signals. Neither the neutral stimuli (with or without MPH) nor the food stimuli when given with placebo increased extracellular dopamine. The food stimuli when given with MPH significantly increased dopamine in the caudate and putamen in the binge eaters but not in the nonbinge eaters. Dopamine increases in the caudate were significantly correlated with the binge eating scores but not with BMI. These results identify dopamine neurotransmission in the caudate as being of relevance to the neurobiology of BED. The lack of correlation between BMI and dopamine changes suggests that dopamine release per se does not predict BMI within a group of obese individuals but that it predicts binge eating.« less

Functional Connectome Analysis of Dopamine Neuron Glutamatergic Connections in Forebrain Regions.

PubMed

Mingote, Susana; Chuhma, Nao; Kusnoor, Sheila V; Field, Bianca; Deutch, Ariel Y; Rayport, Stephen

2015-12-09

In the ventral tegmental area (VTA), a subpopulation of dopamine neurons express vesicular glutamate transporter 2 and make glutamatergic connections to nucleus accumbens (NAc) and olfactory tubercle (OT) neurons. However, their glutamatergic connections across the forebrain have not been explored systematically. To visualize dopamine neuron forebrain projections and to enable photostimulation of their axons independent of transmitter status, we virally transfected VTA neurons with channelrhodopsin-2 fused to enhanced yellow fluorescent protein (ChR2-EYFP) and used DAT(IREScre) mice to restrict expression to dopamine neurons. ChR2-EYFP-expressing neurons almost invariably stained for tyrosine hydroxylase, identifying them as dopaminergic. Dopamine neuron axons visualized by ChR2-EYFP fluorescence projected most densely to the striatum, moderately to the amygdala and entorhinal cortex (ERC), sparsely to prefrontal and cingulate cortices, and rarely to the hippocampus. Guided by ChR2-EYFP fluorescence, we recorded systematically from putative principal neurons in target areas and determined the incidence and strength of glutamatergic connections by activating all dopamine neuron terminals impinging on recorded neurons with wide-field photostimulation. This revealed strong glutamatergic connections in the NAc, OT, and ERC; moderate strength connections in the central amygdala; and weak connections in the cingulate cortex. No glutamatergic connections were found in the dorsal striatum, hippocampus, basolateral amygdala, or prefrontal cortex. These results indicate that VTA dopamine neurons elicit widespread, but regionally distinct, glutamatergic signals in the forebrain and begin to define the dopamine neuron excitatory functional connectome. Dopamine neurons are important for the control of motivated behavior and are involved in the pathophysiology of several major neuropsychiatric disorders. Recent studies have shown that some ventral midbrain dopamine neurons are capable of glutamate cotransmission. With conditional expression of channelrhodopsin in dopamine neurons, we systematically explored dopamine neuron connections in the forebrain and identified regionally specific dopamine neuron excitatory connections. Establishing that only a subset of forebrain regions receive excitatory connections from dopamine neurons will help to determine the function of dopamine neuron glutamate cotransmission, which likely involves transmission of precise temporal signals and enhancement of the dynamic range of dopamine neuron signals. Copyright © 2015 the authors 0270-6474/15/3516259-13$15.00/0.

Dopamine-dependent effects on basal and glutamate stimulated network dynamics in cultured hippocampal neurons.

PubMed

Li, Yan; Chen, Xin; Dzakpasu, Rhonda; Conant, Katherine

2017-02-01

Oscillatory activity occurs in cortical and hippocampal networks with specific frequency ranges thought to be critical to working memory, attention, differentiation of neuronal precursors, and memory trace replay. Synchronized activity within relatively large neuronal populations is influenced by firing and bursting frequency within individual cells, and the latter is modulated by changes in intrinsic membrane excitability and synaptic transmission. Published work suggests that dopamine, a potent modulator of learning and memory, acts on dopamine receptor 1-like dopamine receptors to influence the phosphorylation and trafficking of glutamate receptor subunits, along with long-term potentiation of excitatory synaptic transmission in striatum and prefrontal cortex. Prior studies also suggest that dopamine can influence voltage gated ion channel function and membrane excitability in these regions. Fewer studies have examined dopamine's effect on related endpoints in hippocampus, or potential consequences in terms of network burst dynamics. In this study, we record action potential activity using a microelectrode array system to examine the ability of dopamine to modulate baseline and glutamate-stimulated bursting activity in an in vitro network of cultured murine hippocampal neurons. We show that dopamine stimulates a dopamine type-1 receptor-dependent increase in number of overall bursts within minutes of its application. Notably, however, at the concentration used herein, dopamine did not increase the overall synchrony of bursts between electrodes. Although the number of bursts normalizes by 40 min, bursting in response to a subsequent glutamate challenge is enhanced by dopamine pretreatment. Dopamine-dependent potentiation of glutamate-stimulated bursting was not observed when the two modulators were administered concurrently. In parallel, pretreatment of murine hippocampal cultures with dopamine stimulated lasting increases in the phosphorylation of the glutamate receptor subunit GluA1 at serine 845. This effect is consistent with the possibility that enhanced membrane insertion of GluAs may contribute to a more slowly evolving dopamine-dependent potentiation of glutamate-stimulated bursting. Together, these results are consistent with the possibility that dopamine can influence hippocampal bursting by at least two temporally distinct mechanisms, contributing to an emerging appreciation of dopamine-dependent effects on network activity in the hippocampus. © 2016 International Society for Neurochemistry.

The Transfection of BDNF to Dopamine Neurons Potentiates the Effect of Dopamine D3 Receptor Agonist Recovering the Striatal Innervation, Dendritic Spines and Motor Behavior in an Aged Rat Model of Parkinson’s Disease

PubMed Central

Razgado-Hernandez, Luis F.; Espadas-Alvarez, Armando J.; Reyna-Velazquez, Patricia; Sierra-Sanchez, Arturo; Anaya-Martinez, Veronica; Jimenez-Estrada, Ismael; Bannon, Michael J.; Martinez-Fong, Daniel; Aceves-Ruiz, Jorge

2015-01-01

The progressive degeneration of the dopamine neurons of the pars compacta of substantia nigra and the consequent loss of the dopamine innervation of the striatum leads to the impairment of motor behavior in Parkinson’s disease. Accordingly, an efficient therapy of the disease should protect and regenerate the dopamine neurons of the substantia nigra and the dopamine innervation of the striatum. Nigral neurons express Brain Derived Neurotropic Factor (BDNF) and dopamine D3 receptors, both of which protect the dopamine neurons. The chronic activation of dopamine D3 receptors by their agonists, in addition, restores, in part, the dopamine innervation of the striatum. Here we explored whether the over-expression of BDNF by dopamine neurons potentiates the effect of the activation of D3 receptors restoring nigrostriatal innervation. Twelve-month old Wistar rats were unilaterally injected with 6-hydroxydopamine into the striatum. Five months later, rats were treated with the D3 agonist 7-hydroxy-N,N-di-n-propy1-2-aminotetralin (7-OH-DPAT) administered i.p. during 4½ months via osmotic pumps and the BDNF gene transfection into nigral cells using the neurotensin-polyplex nanovector (a non-viral transfection) that selectively transfect the dopamine neurons via the high-affinity neurotensin receptor expressed by these neurons. Two months after the withdrawal of 7-OH-DPAT when rats were aged (24 months old), immunohistochemistry assays were made. The over-expression of BDNF in rats receiving the D3 agonist normalized gait and motor coordination; in addition, it eliminated the muscle rigidity produced by the loss of dopamine. The recovery of motor behavior was associated with the recovery of the nigral neurons, the dopamine innervation of the striatum and of the number of dendritic spines of the striatal neurons. Thus, the over-expression of BDNF in dopamine neurons associated with the chronic activation of the D3 receptors appears to be a promising strategy for restoring dopamine neurons in Parkinson’s disease. PMID:25693197

A Preliminary Study of DBH (Encoding Dopamine Beta-Hydroxylase) Genetic Variation and Neural Correlates of Emotional and Motivational Processing in Individuals With and Without Pathological Gambling.

PubMed

Yang, Bao-Zhu; Balodis, Iris M; Lacadie, Cheryl M; Xu, Jiansong; Potenza, Marc N

2016-06-01

Background and aims Corticostriatal-limbic neurocircuitry, emotional and motivational processing, dopaminergic and noradrenergic systems and genetic factors have all been implicated in pathological gambling (PG). However, allelic variants of genes influencing dopaminergic and noradrenergic neurotransmitters have not been investigated with respect to the neural correlates of emotional and motivational states in PG. Dopamine beta-hydroxylase (DBH) converts dopamine to norepinephrine; the T allele of a functional single-nucleotide polymorphism rs1611115 (C-1021T) in the DBH gene is associated with less DBH activity and has been linked to emotional processes and addiction. Here, we investigate the influence of rs1611115 on the neural correlates of emotional and motivational processing in PG and healthy comparison (HC) participants. Methods While undergoing functional magnetic resonance imaging, 18 PG and 25 HC participants, all European Americans, viewed gambling-, sad-, and cocaine-related videotapes. Analyses focused on brain activation differences related to DBH genotype (CC/T-carrier [i.e., CT and TT]) and condition (sad/gambling/cocaine). Results CC participants demonstrated greater recruitment of corticostriatal-limbic regions, relative to T-carriers. DBH variants were also associated with altered corticostriatal-limbic activations across the different videotape conditions, and this association appeared to be driven by greater activation in CC participants relative to T-carriers during the sad condition. CC relative to T-carrier subjects also reported greater subjective sadness to the sad videotapes. Conclusions Individual differences in genetic composition linked to aminergic function contribute significantly to emotional regulation across diagnostic groups and warrant further investigation in PG.

Phasic dopamine release drives rapid activation of striatal D2-receptors

PubMed Central

Marcott, Pamela F; Mamaligas, Aphroditi A; Ford, Christopher P

2014-01-01

Summary Striatal dopamine transmission underlies numerous goal-directed behaviors. Medium spiny neurons (MSNs) are a major target of dopamine in the striatum. However, as dopamine does not directly evoke a synaptic event in MSNs, the time course of dopamine signaling in these cells remains unclear. To examine how dopamine release activates D2-receptors on MSNs, G-protein activated inwardly rectifying potassium (GIRK2; Kir 3.2) channels were virally overexpressed in the striatum and the resulting outward currents were used as a sensor of D2-receptor activation. Electrical and optogenetic stimulation of dopamine terminals evoked robust D2-receptor inhibitory post-synaptic currents (IPSCs) in GIRK2-expressing MSNs that occurred in under a second. Evoked D2-IPSCs could be driven by repetitive stimulation and were not occluded by background dopamine tone. Together, the results indicate that D2-receptors on MSNs exhibit functional low affinity and suggest that striatal D2-receptors can encode both tonic and phasic dopamine signals. PMID:25242218

Methamphetamine Regulation of Firing Activity of Dopamine Neurons

PubMed Central

Lin, Min; Sambo, Danielle

2016-01-01

Methamphetamine (METH) is a substrate for the dopamine transporter that increases extracellular dopamine levels by competing with dopamine uptake and increasing reverse transport of dopamine via the transporter. METH has also been shown to alter the excitability of dopamine neurons. The mechanism of METH regulation of the intrinsic firing behaviors of dopamine neurons is less understood. Here we identified an unexpected and unique property of METH on the regulation of firing activity of mouse dopamine neurons. METH produced a transient augmentation of spontaneous spike activity of midbrain dopamine neurons that was followed by a progressive reduction of spontaneous spike activity. Inspection of action potential morphology revealed that METH increased the half-width and produced larger coefficients of variation of the interspike interval, suggesting that METH exposure affected the activity of voltage-dependent potassium channels in these neurons. Since METH has been shown to affect Ca2+ homeostasis, the unexpected findings that METH broadened the action potential and decreased the amplitude of afterhyperpolarization led us to ask whether METH alters the activity of Ca2+-activated potassium (BK) channels. First, we identified BK channels in dopamine neurons by their voltage dependence and their response to a BK channel blocker or opener. While METH suppressed the amplitude of BK channel-mediated unitary currents, the BK channel opener NS1619 attenuated the effects of METH on action potential broadening, afterhyperpolarization repression, and spontaneous spike activity reduction. Live-cell total internal reflection fluorescence microscopy, electrophysiology, and biochemical analysis suggest METH exposure decreased the activity of BK channels by decreasing BK-α subunit levels at the plasma membrane. SIGNIFICANCE STATEMENT Methamphetamine (METH) competes with dopamine uptake, increases dopamine efflux via the dopamine transporter, and affects the excitability of dopamine neurons. Here, we identified an unexpected property of METH on dopamine neuron firing activity. METH transiently increased the spontaneous spike activity of dopamine neurons followed by a progressive reduction of the spontaneous spike activity. METH broadened the action potentials, increased coefficients of variation of the interspike interval, and decreased the amplitude of afterhyperpolarization, which are consistent with changes in the activity of Ca2+-activated potassium (BK) channels. We found that METH decreased the activity of BK channels by stimulating BK-α subunit trafficking. Thus, METH modulation of dopamine neurotransmission and resulting behavioral responses is, in part, due to METH regulation of BK channel activity. PMID:27707972

Differential degradation of motor deficits during gradual dopamine depletion with 6-hydroxydopamine in mice

PubMed Central

Willard, Amanda M.; Bouchard, Rachel S.; Gittis, Aryn H.

2015-01-01

Parkinson’s disease (PD) is a movement disorder whose cardinal motor symptoms arise due to the progressive loss of dopamine. Although this dopamine loss typically progresses slowly over time, currently there are very few animal models that enable incremental dopamine depletion over time within the same animal. This type of gradual dopamine depletion model would be useful in studies aimed at the prodromal phase of PD, when dopamine levels are pathologically low but motor symptoms have not yet presented. Utilizing the highly characterized neurotoxin 6-hydroxydopamine (6-OHDA), we have developed a paradigm to gradually deplete dopamine levels in the striatum over a user-defined time course – spanning weeks to months – in C57BL/6 mice. Dopamine depletions were achieved by administration of five low dose injections (0.75 µg) of 6-OHDA through an implanted intracranial bilateral cannula targeting the medial forebrain bundle. Levels of dopamine within the striatum declined linearly with successive injections, quantified using tyrosine hydroxylase immunostaining and high-performance liquid chromatography. Behavioral testing was carried out at each time point to study the onset and progression of motor impairments as a function of dopamine loss over time. We found that spontaneous locomotion, measured in an open field, was robust to loss of dopamine until ~70% of striatal dopamine was lost. Beyond this point, additional dopamine loss caused a sharp decline in motor performance, reaching a final level comparable to that of acutely depleted mice. Similarly, although rearing behavior was more sensitive to dopamine loss and declined linearly as a function of dopamine levels, it eventually declined to levels similar to that seen in acutely depleted mice. In contrast, motor coordination, measured on a vertical pole task, was only moderately impaired in gradually depleted mice, despite severe impairments observed in acutely depleted mice. These results demonstrate the importance of the temporal profile of dopamine loss on the magnitude and progression of behavioral impairments. Our gradual depletion model thus establishes a new paradigm with which to study how circuits respond and adapt to dopamine loss over time, information which could uncover important cellular events during the prodromal phase of PD that ultimately impact the presentation or treatability of behavioral symptoms. PMID:26067595

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

PubMed Central

2010-01-01

Dopamine D2 and D3 autoreceptors are located on presynaptic terminals and are known to control the release and synthesis of dopamine. Dopamine D3 receptors have a fairly restricted pattern of expression in the mammalian brain. Their localization in the nucleus accumbens core and shell is of particular interest because of their association with the rewarding properties of drugs of abuse. Using background subtracted fast scan cyclic voltammetry, we investigated the effects of dopamine D2 and D3 agonists on electrically stimulated dopamine release and uptake rates in the mouse caudate putamen and nucleus accumbens core and shell. The dopamine D2 agonists (−)-quinpirole hydrochloride and 5,6,7,8-tetrahydro-6-(2-propen-1-yl)-4H-thiazolo[4,5-d]azepin-2-amine dihydrochloride (B-HT 920) had the same dopamine release inhibition effects on caudate putamen and nucleus accumbens (core and shell) on the basis of their EC50 values and efficacies. This suggests that the dopamine D2 autoreceptor functionality is comparable in all three striatal regions investigated. The dopamine D3 agonists (4aR,10bR)-3,4a,4,10b-tetrahydro-4-propyl-2H,5H-[1]benzopyrano-[4,3-b]-1,4-oxazin-9-ol hydrochloride ((+)-PD 128907) and (±)-7-Hydroxy-2-dipropylaminotetralin hydrobromide (7-OH-DPAT) had a significantly greater effect on dopamine release inhibition in the nucleus accumbens shell than in the caudate putamen. This study confirms that, the dopamine D3 autoreceptor functionality is greater in the nucleus accumbens shell followed by the nucleus accumbens core, with the caudate putamen having the least. Neither dopamine D2 nor D3 agonists affected the uptake rates in nucleus accumbens but concentrations greater than 0.1 μM lowered the uptake rate in caudate putamen. To validate our method of evaluating dopamine D2 and D3 autoreceptors, sulpiride (D2 antagonist) and nafadotride (D3 antagonist) were used to reverse the effects of the dopamine agonists to approximately 100% of the preagonist dopamine release concentration. Finally, these results demonstrate a functional voltammetric assay that characterizes dopamine D2-like agonists as either D2- or D3-preferring agonists by taking advantage of the unique receptor density within the striatum. PMID:20567609

Rational assembly of a biointerfaced core@shell nanocomplex towards selective and highly efficient synergistic photothermal/photodynamic therapy

NASA Astrophysics Data System (ADS)

Qin, Chenchen; Fei, Jinbo; Wang, Anhe; Yang, Yang; Li, Junbai

2015-11-01

To optimize synergistic cancer therapy, we rationally assemble an inorganic-organic nanocomplex using a folate-modified lipid bilayer spread on photosensitizer-entrapped mesoporous silica nanoparticle (MSN) coated gold nanorods (AuNRs). In this hybrid bioconjugate, the large specific surface area and pore size of AuNR@MSN guarantee a high loading capacity of small photosensitive molecules. The modification with selective mixed liposomes on the surface of AuNR@MSN enables faster cellular internalization and enhancement of endocytosis. Under one-time NIR two-photon illumination, AuNR-mediated hyperthermia can kill cancer cells directly. Meanwhile, the loaded photosensitizer, hypocrellin B, generates two kinds of reactive oxygen species (ROS) to induce cell apoptosis. Remarkably, hyperthermia can improve the yield of ROS. After intravenous injection of this bioconjugate into female BALB/c nude mice followed by laser irradiation (808 nm, 1.3 W cm-2, 6 min), the tumor growth is suppressed completely. The tumors are not recurrent within the observation time (19 days), and the normal or main organs are not obviously pathological. Thus, such a simplified and selective cancer treatment, combining photothermal and photodynamic therapy in a synergistic manner, provides outstanding efficiency in vivo. This nanocomplex with well-defined core@shell nanostructures integrated with a two-photon technique holds great promise to improve cancer phototherapy with a high efficiency in the clinic.To optimize synergistic cancer therapy, we rationally assemble an inorganic-organic nanocomplex using a folate-modified lipid bilayer spread on photosensitizer-entrapped mesoporous silica nanoparticle (MSN) coated gold nanorods (AuNRs). In this hybrid bioconjugate, the large specific surface area and pore size of AuNR@MSN guarantee a high loading capacity of small photosensitive molecules. The modification with selective mixed liposomes on the surface of AuNR@MSN enables faster cellular internalization and enhancement of endocytosis. Under one-time NIR two-photon illumination, AuNR-mediated hyperthermia can kill cancer cells directly. Meanwhile, the loaded photosensitizer, hypocrellin B, generates two kinds of reactive oxygen species (ROS) to induce cell apoptosis. Remarkably, hyperthermia can improve the yield of ROS. After intravenous injection of this bioconjugate into female BALB/c nude mice followed by laser irradiation (808 nm, 1.3 W cm-2, 6 min), the tumor growth is suppressed completely. The tumors are not recurrent within the observation time (19 days), and the normal or main organs are not obviously pathological. Thus, such a simplified and selective cancer treatment, combining photothermal and photodynamic therapy in a synergistic manner, provides outstanding efficiency in vivo. This nanocomplex with well-defined core@shell nanostructures integrated with a two-photon technique holds great promise to improve cancer phototherapy with a high efficiency in the clinic. Electronic supplementary information (ESI) available: The relevant TEM, DLS, UV spectra, photographs and chemical structures. See DOI: 10.1039/c5nr06501a

Delivery of Chemically Glycosylated Cytochrome c Immobilized in Mesoporous Silica Nanoparticles Induces Apoptosis in HeLa Cancer Cells

PubMed Central

Méndez, Jessica; Cruz, Moraima Morales; Reyes, Yamixa Delgado; Figueroa, Cindy M.; Orellano, Elsie A.; Morales, Myraida; Monteagudo, Alina; Griebenow, Kai

2014-01-01

Cytochrome c (Cyt c) is a small mitochondrial heme protein involved in the intrinsic apoptotic pathway. Once Cyt c is released into the cytosol, the caspase mediated apoptosis cascade is activated resulting in programmed cell death. Herein, we explore the covalent immobilization of Cyt c into mesoporous silica nanoparticles (MSN) to generate a smart delivery system for intracellular drug delivery to cancer cells aiming at affording subsequent cell death. Cyt c was modified with sulfosuccinimidyl-6-[3′-(2-pyridyldithio)-propionamido] hexanoate (SPDP) and incorporated into SH-functionalized MSN by thiol-disulfide interchange. Unfortunately, delivery of Cyt c from the MSN was not efficient in inducing apoptosis in human cervical cancer HeLa cells. We tested whether chemical Cyt c glycosylation could be useful in overcoming the efficacy problems by potentially improving Cyt c thermodynamic stability and reducing proteolytic degradation. Cyt c lysine residues were modified with lactose at a lactose-to-protein molar ratio of 3.7±0.9 using mono-(lactosylamido)-mono-(succinimidyl) suberate linker chemistry. Circular dichroism (CD) spectra demonstrated that part of the activity loss of Cyt c was due to conformational changes upon its modification with the SPDP linker. These conformational changes were prevented in the glycoconjugate. In agreement with the unfolding of Cyt c by the linker, a proteolytic assay demonstrated that the Cyt c-SPDP conjugate was more susceptible to proteolysis than Cyt c. Attachment of the four lactose molecules reversed this increased susceptibility and protected Cyt c from proteolytic degradation. Furthermore, a cell-free caspase-3 assay revealed 47% and 87% of relative caspase activation by Cyt c-SPDP and the Cyt c-lactose bioconjugate, respectively, when compared to Cyt c. This again demonstrates the efficiency of the glycosylation to improve maintaining Cyt c structure and thus function. To test for cytotoxicity, HeLa cells were incubated with Cyt c loaded MSN at different Cyt c concentrations (12.5, 25.0, and 37.5 μg/mL) for 24 to 72 h and cellular metabolic activity determined by a cell proliferation assay. While MSN-SPDP-Cyt c did not induced cell death, the Cyt c-lactose bioconjugate induced significant cell death after 72 h, reducing HeLa cell viability to 67% and 45% at the 25 μg/mL and 37.5 μg/mL concentrations, respectively. Confocal microscopy confirmed that the MSN immobilized Cyt c-lactose bioconjugate was internalized by HeLa cells and that the bioconjugate was capable of endosomal escape. The results clearly demonstrate that chemical glycosylation stabilized Cyt c upon formulation of a smart drug delivery system and upon delivery into cancer cells and highlight the general potential of chemical protein glycosylation to improve the stability of protein drugs. PMID:24294910

Organization of monosynaptic inputs to the serotonin and dopamine neuromodulatorysystems

PubMed Central

Ogawa, Sachie K.; Cohen, Jeremiah Y.; Hwang, Dabin; Uchida, Naoshige; Watabe-Uchida, Mitsuko

2014-01-01

SUMMARY Serotonin and dopamine are major neuromodulators. Here we used a modified rabies virus to identify monosynaptic inputs to serotonin neurons in the dorsal and median raphe (DR and MR). We found that inputs to DR and MR serotonin neurons are spatially shiftedin the forebrain, with MRserotonin neurons receiving inputs from more medial structures. We then compared these data with inputs to dopamine neurons in the ventral tegmental area (VTA) and substantianigra pars compacta (SNc). We found that DR serotonin neurons receive inputs from a remarkably similar set of areas as VTA dopamine neurons, apart from the striatum, which preferentially targets dopamine neurons. Ourresults suggest three majorinput streams: amedial stream regulates MR serotonin neurons, anintermediate stream regulatesDR serotonin and VTA dopamine neurons, and alateral stream regulatesSNc dopamine neurons. These results providefundamental organizational principlesofafferent control forserotonin and dopamine. PMID:25108805

The dopamine theory of addiction: 40 years of highs and lows.

PubMed

Nutt, David J; Lingford-Hughes, Anne; Erritzoe, David; Stokes, Paul R A

2015-05-01

For several decades, addiction has come to be viewed as a disorder of the dopamine neurotransmitter system; however, this view has not led to new treatments. In this Opinion article, we review the origins of the dopamine theory of addiction and discuss the ability of addictive drugs to elicit the release of dopamine in the human striatum. There is robust evidence that stimulants increase striatal dopamine levels and some evidence that alcohol may have such an effect, but little evidence, if any, that cannabis and opiates increase dopamine levels. Moreover, there is good evidence that striatal dopamine receptor availability and dopamine release are diminished in individuals with stimulant or alcohol dependence but not in individuals with opiate, nicotine or cannabis dependence. These observations have implications for understanding reward and treatment responses in various addictions.

Selective detection of dopamine in the presence of ascorbic acid via fluorescence quenching of InP/ZnS quantum dots.

PubMed

Ankireddy, Seshadri Reddy; Kim, Jongsung

2015-01-01

Dopamine is a neurotransmitter of the catecholamine family and has many important roles, especially in human brain. Several diseases of the nervous system, such as Parkinson's disease, attention deficit hyperactivity disorder, restless legs syndrome, are believed to be related to deficiency of dopamine. Several studies have been performed to detect dopamine by using electrochemical analysis. In this study, quantum dots (QDs) were used as sensing media for the detection of dopamine. The surface of the QDs was modified with l-cysteine by coupling reaction to increase the selectivity of dopamine. The fluorescence of cysteine-capped indium phosphide/zinc sulfide QDs was quenched by dopamine with various concentrations in the presence of ascorbic acid. This method shows good selectivity for dopamine detection, and the detection limit was 5 nM.

Dopamine dependency for acquisition and performance of Pavlovian conditioned response

PubMed Central

Darvas, Martin; Wunsch, Amanda M.; Gibbs, Jeffrey T.; Palmiter, Richard D.

2014-01-01

During Pavlovian conditioning, pairing of a neutral conditioned stimulus (CS) with a reward leads to conditioned reward-approach responses (CRs) that are elicited by presentation of the CS. CR behaviors can be sign tracking, in which animals engage the CS, or goal tracking, in which animals go to the reward location. We investigated CR behaviors in mice with only ∼5% of normal dopamine in the striatum using a Pavlovian conditioning paradigm. These mice had severely impaired acquisition of the CR, which was ameliorated by pharmacological restoration of dopamine synthesis with l-dopa. Surprisingly, after they had learned the CR, its expression decayed only gradually in following sessions that were conducted without l-dopa treatment. To assess specific contributions of dopamine signaling in the dorsal or ventral striatum, we performed virus-mediated restoration of dopamine synthesis in completely dopamine-deficient (DD) mice. Mice with dopamine signaling only in the dorsal striatum did not acquire a CR, whereas mice with dopamine signaling only in in the ventral striatum acquired a CR. The CR in mice with dopamine signaling only in the dorsal striatum was restored by subjecting the mice to instrumental training in which they had to interact with the CS to obtain rewards. We conclude that dopamine is essential for learning and performance of CR behavior that is predominantly goal tracking. Furthermore, although dopamine signaling in the ventral striatum is sufficient to support a CR, dopamine signaling only in the dorsal striatum can also support a CR under certain circumstances. PMID:24550305

Involvement of Infralimbic Prefrontal Cortex but not Lateral Habenula in Dopamine Attenuation After Chronic Mild Stress.

PubMed

Moreines, Jared L; Owrutsky, Zoe L; Grace, Anthony A

2017-03-01

Emerging evidence supports a role for dopamine in major depressive disorder (MDD). We recently reported fewer spontaneously active ventral tegmental area (VTA) dopamine neurons (ie, reduced dopamine neuron population activity) in the chronic mild stress (CMS) rodent model of MDD. In this study, we examined the role of two brain regions that have been implicated in MDD in humans, the infralimbic prefrontal cortex (ILPFC)-that is, rodent homolog of Brodmann area 25 (BA25), and the lateral habenula (LHb) in the CMS-induced attenuation of dopamine neuron activity. The impact of activating the ILPFC or LHb was evaluated using single-unit extracellular recordings of identified VTA dopamine neurons. The involvement of each region in dopamine neuron attenuation following 5-7 weeks of CMS was then evaluated by selective inactivation. Activation of either ILPFC or LHb in normal rats potently suppressed dopamine neuron population activity, but in unique patterns. ILPFC activation selectively inhibited dopamine neurons in medial VTA, which were most impacted by CMS. Conversely, LHb activation selectively inhibited dopamine neurons in lateral VTA, which were unaffected by CMS. Moreover, only ILPFC inactivation restored dopamine neuron population activity to normal levels following CMS; LHb inactivation had no restorative effect. These data suggest that, in the CMS model of MDD, the ILPFC is the primary driver of diminished dopamine neuron responses. These findings support a neural substrate for ILPFC/BA25 linking affective and motivational circuitry dysfunction in MDD.

Optical Control of Dopamine Receptors Using a Photoswitchable Tethered Inverse Agonist.

PubMed

Donthamsetti, Prashant C; Winter, Nils; Schönberger, Matthias; Levitz, Joshua; Stanley, Cherise; Javitch, Jonathan A; Isacoff, Ehud Y; Trauner, Dirk

2017-12-27

Family A G protein-coupled receptors (GPCRs) control diverse biological processes and are of great clinical relevance. Their archetype rhodopsin becomes naturally light sensitive by binding covalently to the photoswitchable tethered ligand (PTL) retinal. Other GPCRs, however, neither bind covalently to ligands nor are light sensitive. We sought to impart the logic of rhodopsin to light-insensitive Family A GPCRs in order to enable their remote control in a receptor-specific, cell-type-specific, and spatiotemporally precise manner. Dopamine receptors (DARs) are of particular interest for their roles in motor coordination, appetitive, and aversive behavior, as well as neuropsychiatric disorders such as Parkinson's disease, schizophrenia, mood disorders, and addiction. Using an azobenzene derivative of the well-known DAR ligand 2-(N-phenethyl-N-propyl)amino-5-hydroxytetralin (PPHT), we were able to rapidly, reversibly, and selectively block dopamine D1 and D2 receptors (D1R and D2R) when the PTL was conjugated to an engineered cysteine near the dopamine binding site. Depending on the site of tethering, the ligand behaved as either a photoswitchable tethered neutral antagonist or inverse agonist. Our results indicate that DARs can be chemically engineered for selective remote control by light and provide a template for precision control of Family A GPCRs.

Dopaminergic tone does not influence pain levels during placebo interventions in patients with chronic neuropathic pain.

PubMed

Skyt, Ina; Moslemi, Kurosh; Baastrup, Cathrine; Grosen, Kasper; Benedetti, Fabrizio; Petersen, Gitte L; Price, Donald D; Hall, Kathryn T; Kaptchuk, Ted J; Svensson, Peter; Jensen, Troels S; Vase, Lene

2017-10-23

Placebo effects have been reported in patients with chronic neuropathic pain. Expected pain levels and positive emotions are involved in the observed pain relief, but the underlying neurobiology is largely unknown. Patients with neuropathic pain are highly motivated for pain relief, and as motivational factors such as expectations of reward, as well as pain processing in itself, are related to the dopaminergic system, it can be speculated that dopamine release contributes to placebo effects in neuropathic pain. Nineteen patients with neuropathic pain after thoracic surgery were tested during a placebo intervention consisting of open and hidden applications of the pain-relieving agent lidocaine (2 mL) and no treatment. The dopamine antagonist haloperidol (2 mg) and the agonist levodopa/carbidopa (100/25 mg) were administered to test the involvement of dopamine. Expected pain levels, desire for pain relief, and ongoing and evoked pain were assessed on mechanical visual analog scales (0-10). Significant placebo effects on ongoing (P ≤ 0.003) and evoked (P ≤ 0.002) pain were observed. Expectancy and desire accounted for up to 41.2% and 71.5% of the variance in ongoing and evoked pain, respectively, after the open application of lidocaine. We found no evidence for an effect of haloperidol and levodopa/carbidopa on neuropathic pain levels (P = 0.071-0.963). Dopamine seemed to influence the levels of expectancy and desire, yet there was no evidence for indirect or interaction effects on the placebo effect. This is the first study to suggest that dopamine does not contribute to placebo effects in chronic neuropathic pain.

Dopamine selectively remediates ‘model-based’ reward learning: a computational approach

PubMed Central

Sharp, Madeleine E.; Foerde, Karin; Daw, Nathaniel D.

2016-01-01

Patients with loss of dopamine due to Parkinson’s disease are impaired at learning from reward. However, it remains unknown precisely which aspect of learning is impaired. In particular, learning from reward, or reinforcement learning, can be driven by two distinct computational processes. One involves habitual stamping-in of stimulus-response associations, hypothesized to arise computationally from ‘model-free’ learning. The other, ‘model-based’ learning, involves learning a model of the world that is believed to support goal-directed behaviour. Much work has pointed to a role for dopamine in model-free learning. But recent work suggests model-based learning may also involve dopamine modulation, raising the possibility that model-based learning may contribute to the learning impairment in Parkinson’s disease. To directly test this, we used a two-step reward-learning task which dissociates model-free versus model-based learning. We evaluated learning in patients with Parkinson’s disease tested ON versus OFF their dopamine replacement medication and in healthy controls. Surprisingly, we found no effect of disease or medication on model-free learning. Instead, we found that patients tested OFF medication showed a marked impairment in model-based learning, and that this impairment was remediated by dopaminergic medication. Moreover, model-based learning was positively correlated with a separate measure of working memory performance, raising the possibility of common neural substrates. Our results suggest that some learning deficits in Parkinson’s disease may be related to an inability to pursue reward based on complete representations of the environment. PMID:26685155

Individual differences in the propensity to approach signals vs goals promote different adaptations in the dopamine system of rats.

PubMed

Flagel, Shelly B; Watson, Stanley J; Robinson, Terry E; Akil, Huda

2007-04-01

The way an individual responds to cues associated with rewards may be a key determinant of vulnerability to compulsive behavioral disorders. We studied individual differences in Pavlovian conditioned approach behavior and examined the expression of neurobiological markers associated with the dopaminergic system, the same neural system implicated in incentive motivational processes. Pavlovian autoshaping procedures consisted of the brief presentation of an illuminated retractable lever (conditioned stimulus) followed by the response-independent delivery of a food pellet (unconditioned stimulus), which lead to a Pavlovian conditioned response. In situ hybridization was performed on brains obtained either following the first or last (fifth) day of training. Two phenotypes emerged. Sign-trackers (ST) exhibited behavior that seemed to be largely controlled by the cue that signaled impending reward delivery; whereas goal-trackers (GT) preferentially approached the location where the reward was delivered. Following a single training session, ST showed greater expression of dopamine D1 receptor mRNA relative to GT. After 5 days of training, GT exhibited greater expression levels of tyrosine hydroxylase, dopamine transporter, and dopamine D2 receptor mRNA relative to ST. These findings suggest that the development of approach behavior towards signals vs goal leads to distinct adaptations in the dopamine system. The sign-tracker vs goal-tracker phenotype may prove to be a valuable animal model to investigate individual differences in the way incentive salience is attributed to environmental stimuli, which may contribute to the development of addiction and other compulsive behavioral disorders.

Activation of Pedunculopontine Glutamate Neurons Is Reinforcing

PubMed Central

Yoo, Ji Hoon; Zell, Vivien; Wu, Johnathan; Punta, Cindy; Ramajayam, Nivedita; Shen, Xinyi; Faget, Lauren; Lilascharoen, Varoth; Lim, Byung Kook

2017-01-01

Dopamine transmission from midbrain ventral tegmental area (VTA) neurons underlies behavioral processes related to motivation and drug addiction. The pedunculopontine tegmental nucleus (PPTg) is a brainstem nucleus containing glutamate-, acetylcholine-, and GABA-releasing neurons with connections to basal ganglia and limbic brain regions. Here we investigated the role of PPTg glutamate neurons in reinforcement, with an emphasis on their projections to VTA dopamine neurons. We used cell-type-specific anterograde tracing and optogenetic methods to selectively label and manipulate glutamate projections from PPTg neurons in mice. We used anatomical, electrophysiological, and behavioral assays to determine their patterns of connectivity and ascribe functional roles in reinforcement. We found that photoactivation of PPTg glutamate cell bodies could serve as a direct positive reinforcer on intracranial self-photostimulation assays. Further, PPTg glutamate neurons directly innervate VTA; photostimulation of this pathway preferentially excites VTA dopamine neurons and is sufficient to induce behavioral reinforcement. These results demonstrate that ascending PPTg glutamate projections can drive motivated behavior, and PPTg to VTA synapses may represent an important target relevant to drug addiction and other mental health disorders. SIGNIFICANCE STATEMENT Uncovering brain circuits underlying reward-seeking is an important step toward understanding the circuit bases of drug addiction and other psychiatric disorders. The dopaminergic system emanating from the ventral tegmental area (VTA) plays a key role in regulating reward-seeking behaviors. We used optogenetics to demonstrate that the pedunculopontine tegmental nucleus sends glutamatergic projections to VTA dopamine neurons, and that stimulation of this circuit promotes behavioral reinforcement. The findings support a critical role for pedunculopontine tegmental nucleus glutamate neurotransmission in modulating VTA dopamine neuron activity and behavioral reinforcement. PMID:28053028

Species differences in the relative densities of D1- and D2-like dopamine receptor subtypes in the Japanese quail and rats: an in vitro quantitative receptor autoradiography study.

PubMed

Kleitz, Hayley K; Cornil, Charlotte A; Balthazart, Jacques; Ball, Gregory F

2009-01-01

Evidence has accumulated that the regulation of male sexual behavior by dopamine might not be the same in Japanese quail (and perhaps all birds) as it is in mammals. For example, the non-selective dopamine receptor agonist, apomorphine (APO), facilitates male sexual behavior in rats but inhibits it in quail. Although the general organization of the dopamine system is similar in birds and mammals, it is possible that the relative distribution and/or density of binding sites are different. We therefore compared the relative densities of D1-like and D2-like receptor subtypes in Japanese quail and rats, with the use of in vitro quantitative receptor autoradiography. Brain sections from 8 male rats and 8 male quail were labeled with [(3)H]SCH-23390 and [(3)H]Spiperone. In general we found a systematic species difference in the relative density of D1- vs. D2-like receptors such that the D2/D1 ratio is higher in quail than in rats in areas, known to be important target sites for dopamine action such as striatal regions or the preoptic area, which is also associated with activation of sexual behavior. This difference might explain the variation in the behavioral effectiveness of APO in rats as compared to quail; with a higher relative density of D2-like receptors in quail, a similar dose of APO would be more likely to activate inhibitory processes in quail than in rats. (c) 2009 S. Karger AG, Basel.

Emotion dysregulation and amygdala dopamine D2-type receptor availability in methamphetamine users.

PubMed

Okita, Kyoji; Ghahremani, Dara G; Payer, Doris E; Robertson, Chelsea L; Dean, Andy C; Mandelkern, Mark A; London, Edythe D

2016-04-01

Individuals who use methamphetamine chronically exhibit emotional and dopaminergic neurochemical deficits. Although the amygdala has an important role in emotion processing and receives dopaminergic innervation, little is known about how dopamine transmission in this region contributes to emotion regulation. This investigation aimed to evaluate emotion regulation in subjects who met DSM-IV criteria for methamphetamine dependence, and to test for a relationship between self-reports of difficulty in emotion regulation and D2-type dopamine receptor availability in the amygdala. Ninety-four methamphetamine-using and 102 healthy-control subjects completed the Difficulties in Emotion Regulation Scale (DERS); 33 of those who used methamphetamine completed the Addiction Severity Index (ASI). A subset of 27 methamphetamine-group and 20 control-group subjects completed positron emission tomography with [(18)F]fallypride to assay amygdala D2-type dopamine receptor availability, measured as binding potential (BPND). The methamphetamine group scored higher than the control group on the DERS total score (p<0.001), with DERS total score positively correlated with the Drug Composite Score on the ASI (p=0.02) in the methamphetamine group. The DERS total score was positively correlated with amygdala BPND in both groups and the combined group of participants (combined: r=0.331, p=0.02), and the groups did not differ in this relationship. These findings highlight problems with emotion regulation linked to methamphetamine use, possibly contributing to personal and interpersonal behavioral problems. They also suggest that D2-type dopamine receptors in the amygdala contribute to emotion regulation in both healthy and methamphetamine-using subjects. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Emotion Dysregulation and Amygdala Dopamine D2-type Receptor Availability in Methamphetamine Users

PubMed Central

Okita, Kyoji; Ghahremani, Dara G.; Payer, Doris E.; Robertson, Chelsea L.; Dean, Andy C.; Mandelkern, Mark A.; London, Edythe D.

2016-01-01

Background Individuals who use methamphetamine chronically exhibit emotional and dopaminergic neurochemical deficits. Although the amygdala has an important role in emotion processing and receives dopaminergic innervation, little is known about how dopamine transmission in this region contributes to emotion regulation. This investigation aimed to evaluate emotion regulation in subjects who met DSM-IV criteria for methamphetamine dependence, and to test for a relationship between self-reports of difficulty in emotion regulation and D2-type dopamine receptor availability in the amygdala. Method Ninety-four methamphetamine-using and 102 healthy-control subjects completed the Difficulties in Emotion Regulation Scale (DERS); 33 of those who used methamphetamine completed the Addiction Severity Index (ASI). A subset of 27 methamphetamine-group and 20 control-group subjects completed positron emission tomography with [18F]fallypride to assay amygdala D2-type dopamine receptor availability, measured as binding potential (BPND). Results The methamphetamine group scored higher than the control group on the DERS total score (p < 0.001), with DERS total score positively correlated with the Drug Composite Score on the ASI (p = 0.02) in the methamphetamine group. The DERS total score was positively correlated with amygdala BPND in both groups and the combined group of participants (combined: r = 0.331, p = 0.02), and the groups did not differ in this relationship. Conclusion These findings highlight problems with emotion regulation linked to methamphetamine use, possibly contributing to personal and interpersonal behavioral problems. They also suggest that D2-type dopamine receptors in the amygdala contribute to emotion regulation in both healthy and methamphetamine-using subjects. PMID:26880595

Cocaine Drives Aversive Conditioning via Delayed Activation of Dopamine-Responsive Habenular and Midbrain Pathways

PubMed Central

Good, Cameron H.; Rowley, Courtney S.; Xu, Sheng-ping; Wang, Huikun; Burnham, Nathan W.; Hoffman, Alexander F.; Lupica, Carl R.; Ikemoto, Satoshi

2013-01-01

Many strong rewards, including abused drugs, also produce aversive effects that are poorly understood. For example, cocaine can produce aversive conditioning after its rewarding effects have dissipated, consistent with opponent process theory, but the neural mechanisms involved are not well known. Using electrophysiological recordings in awake rats, we found that some neurons in the lateral habenula (LHb), where activation produces aversive conditioning, exhibited biphasic responses to single doses of intravenous cocaine, with an initial inhibition followed by delayed excitation paralleling cocaine's shift from rewarding to aversive. Recordings in LHb slice preparations revealed similar cocaine-induced biphasic responses and further demonstrated that biphasic responses were mimicked by dopamine, that the inhibitory phase depended on dopamine D2-like receptors, and that the delayed excitation persisted after drug washout for prolonged durations consistent with findings in vivo. c-Fos experiments further showed that cocaine-activated LHb neurons preferentially projected to and activated neurons in the rostromedial tegmental nucleus (RMTg), a recently identified target of LHb axons that is activated by negative motivational stimuli and inhibits dopamine neurons. Finally, pharmacological excitation of the RMTg produced conditioned place aversion, whereas cocaine-induced avoidance behaviors in a runway operant paradigm were abolished by lesions of LHb efferents, lesions of the RMTg, or by optogenetic inactivation of the RMTg selectively during the period when LHb neurons are activated by cocaine. Together, these results indicate that LHb/RMTg pathways contribute critically to cocaine-induced avoidance behaviors, while also participating in reciprocally inhibitory interactions with dopamine neurons. PMID:23616555

Sensing small neurotransmitter-enzyme interaction with nanoporous gated ion-sensitive field effect transistors.

PubMed

Kisner, Alexandre; Stockmann, Regina; Jansen, Michael; Yegin, Ugur; Offenhäusser, Andreas; Kubota, Lauro Tatsuo; Mourzina, Yulia

2012-01-15

Ion-sensitive field effect transistors with gates having a high density of nanopores were fabricated and employed to sense the neurotransmitter dopamine with high selectivity and detectability at micromolar range. The nanoporous structure of the gates was produced by applying a relatively simple anodizing process, which yielded a porous alumina layer with pores exhibiting a mean diameter ranging from 20 to 35 nm. Gate-source voltages of the transistors demonstrated a pH-dependence that was linear over a wide range and could be understood as changes in surface charges during protonation and deprotonation. The large surface area provided by the pores allowed the physical immobilization of tyrosinase, which is an enzyme that oxidizes dopamine, on the gates of the transistors, and thus, changes the acid-base behavior on their surfaces. Concentration-dependent dopamine interacting with immobilized tyrosinase showed a linear dependence into a physiological range of interest for dopamine concentration in the changes of gate-source voltages. In comparison with previous approaches, a response time relatively fast for detecting dopamine was obtained. Additionally, selectivity assays for other neurotransmitters that are abundantly found in the brain were examined. These results demonstrate that the nanoporous structure of ion-sensitive field effect transistors can easily be used to immobilize specific enzyme that can readily and selectively detect small neurotransmitter molecule based on its acid-base interaction with the receptor. Therefore, it could serve as a technology platform for molecular studies of neurotransmitter-enzyme binding and drugs screening. Copyright © 2011 Elsevier B.V. All rights reserved.

Pre- and post-synaptic dopamine imaging and its relation with frontostriatal cognitive function in Parkinson disease: PET studies with [11C]NNC 112 and [18F]FDOPA.

PubMed

Cropley, Vanessa L; Fujita, Masahiro; Bara-Jimenez, William; Brown, Amira K; Zhang, Xiang-Yang; Sangare, Janet; Herscovitch, Peter; Pike, Victor W; Hallett, Mark; Nathan, Pradeep J; Innis, Robert B

2008-07-15

Frontostriatal cognitive dysfunction is common in Parkinson disease (PD), but the explanation for its heterogeneous expressions remains unclear. This study examined the dopamine system within the frontostriatal circuitry with positron emission tomography (PET) to investigate pre- and post-synaptic dopamine function in relation to the executive processes in PD. Fifteen non-demented PD patients and 14 healthy controls underwent [(18)F]FDOPA (for dopamine synthesis) and [(11)C]NNC 112 (for D(1) receptors) PET scans and cognitive testing. Parametric images of [(18)F]FDOPA uptake (K(i)) and [(11)C]NNC 112 binding potential (BP(ND)) were calculated using reference tissue models. Group differences in K(i) and BP(ND) were assessed with both volume of interest and statistical parametric mapping, and were correlated with cognitive tests. Measurement of [(18)F]FDOPA uptake in cerebral cortex was questionable because of higher K(i) values in white than adjacent gray matter. These paradoxical results were likely to be caused by violations of the reference tissue model assumption rendering interpretation of cortical [(18)F]FDOPA uptake in PD difficult. We found no regional differences in D(1) receptor density between controls and PD, and no overall differences in frontostriatal performance. Although D(1) receptor density did not relate to frontostriatal cognition, K(i) decreases in the putamen predicted performance on the Wisconsin Card Sorting Test in PD only. These results suggest that striatal dopamine denervation may contribute to some frontostriatal cognitive impairment in moderate stage PD.

The dopamine D1 receptor is expressed and facilitates relaxation in airway smooth muscle.

PubMed

Mizuta, Kentaro; Zhang, Yi; Xu, Dingbang; Mizuta, Fumiko; D'Ovidio, Frank; Masaki, Eiji; Emala, Charles W

2013-09-02

Dopamine signaling is mediated by Gs protein-coupled "D1-like" receptors (D1 and D5) and Gi-coupled "D2-like" receptors (D2-4). In asthmatic patients, inhaled dopamine induces bronchodilation. Although the Gi-coupled dopamine D2 receptor is expressed and sensitizes adenylyl cyclase activity in airway smooth muscle (ASM) cells, the Gs-coupled dopamine D1-like receptor subtypes have never been identified on these cells. Activation of Gs-coupled receptors stimulates cyclic AMP (cAMP) production through the stimulation of adenylyl cyclase, which promotes ASM relaxation. We questioned whether the dopamine D1-like receptor is expressed on ASM, and modulates its function through Gs-coupling. The mRNA and protein expression of dopamine D1-like receptor subtypes in both native human and guinea pig ASM tissue and cultured human ASM (HASM) cells was measured. To characterize the stimulation of cAMP through the dopamine D1 receptor, HASM cells were treated with dopamine or the dopamine D1-like receptor agonists (A68930 or SKF38393) before cAMP measurements. To evaluate whether the activation of dopamine D1 receptor induces ASM relaxation, guinea pig tracheal rings suspended under isometric tension in organ baths were treated with cumulatively increasing concentrations of dopamine or A68930, following an acetylcholine-induced contraction with or without the cAMP-dependent protein kinase (PKA) inhibitor Rp-cAMPS, the large-conductance calcium-activated potassium (BKCa) channel blocker iberiotoxin, or the exchange proteins directly activated by cAMP (Epac) antagonist NSC45576. Messenger RNA encoding the dopamine D1 and D5 receptors were detected in native human ASM tissue and cultured HASM cells. Immunoblots confirmed the protein expression of the dopamine D1 receptor in both native human and guinea pig ASM tissue and cultured HASM cells. The dopamine D1 receptor was also immunohistochemically localized to both human and guinea pig ASM. The dopamine D1-like receptor agonists stimulated cAMP production in HASM cells, which was reversed by the selective dopamine D1-like receptor antagonists SCH23390 or SCH39166. A68930 relaxed acetylcholine-contracted guinea pig tracheal rings, which was attenuated by Rp-cAMPS but not by iberiotoxin or NSC45576. These results demonstrate that the dopamine D1 receptors are expressed on ASM and regulate smooth muscle force via cAMP activation of PKA, and offer a novel target for therapeutic relaxation of ASM.

The dopamine D1 receptor is expressed and facilitates relaxation in airway smooth muscle

PubMed Central

2013-01-01

Background Dopamine signaling is mediated by Gs protein-coupled “D1-like” receptors (D1 and D5) and Gi-coupled “D2-like” receptors (D2-4). In asthmatic patients, inhaled dopamine induces bronchodilation. Although the Gi-coupled dopamine D2 receptor is expressed and sensitizes adenylyl cyclase activity in airway smooth muscle (ASM) cells, the Gs-coupled dopamine D1-like receptor subtypes have never been identified on these cells. Activation of Gs-coupled receptors stimulates cyclic AMP (cAMP) production through the stimulation of adenylyl cyclase, which promotes ASM relaxation. We questioned whether the dopamine D1-like receptor is expressed on ASM, and modulates its function through Gs-coupling. Methods The mRNA and protein expression of dopamine D1-like receptor subtypes in both native human and guinea pig ASM tissue and cultured human ASM (HASM) cells was measured. To characterize the stimulation of cAMP through the dopamine D1 receptor, HASM cells were treated with dopamine or the dopamine D1-like receptor agonists (A68930 or SKF38393) before cAMP measurements. To evaluate whether the activation of dopamine D1 receptor induces ASM relaxation, guinea pig tracheal rings suspended under isometric tension in organ baths were treated with cumulatively increasing concentrations of dopamine or A68930, following an acetylcholine-induced contraction with or without the cAMP-dependent protein kinase (PKA) inhibitor Rp-cAMPS, the large-conductance calcium-activated potassium (BKCa) channel blocker iberiotoxin, or the exchange proteins directly activated by cAMP (Epac) antagonist NSC45576. Results Messenger RNA encoding the dopamine D1 and D5 receptors were detected in native human ASM tissue and cultured HASM cells. Immunoblots confirmed the protein expression of the dopamine D1 receptor in both native human and guinea pig ASM tissue and cultured HASM cells. The dopamine D1 receptor was also immunohistochemically localized to both human and guinea pig ASM. The dopamine D1-like receptor agonists stimulated cAMP production in HASM cells, which was reversed by the selective dopamine D1-like receptor antagonists SCH23390 or SCH39166. A68930 relaxed acetylcholine-contracted guinea pig tracheal rings, which was attenuated by Rp-cAMPS but not by iberiotoxin or NSC45576. Conclusions These results demonstrate that the dopamine D1 receptors are expressed on ASM and regulate smooth muscle force via cAMP activation of PKA, and offer a novel target for therapeutic relaxation of ASM. PMID:24004608

Striatal Sensitivity during Reward Processing in Attention-Deficit/Hyperactivity Disorder

ERIC Educational Resources Information Center

Paloyelis, Yannis; Mehta, Mitul A.; Faraone, Stephen V.; Asherson, Philip; Kuntsi, Jonna

2012-01-01

Objective: Attention-deficit/hyperactivity disorder (ADHD) has been linked to deficits in the dopaminergic reward-processing circuitry; yet, existing evidence is limited, and the influence of genetic variation affecting dopamine signaling remains unknown. We investigated striatal responsivity to rewards in ADHD combined type (ADHD-CT) using…

Dopamine release from the locus coeruleus to the dorsal hippocampus promotes spatial learning and memory

PubMed Central

Kempadoo, Kimberly A.; Mosharov, Eugene V.; Choi, Se Joon; Sulzer, David; Kandel, Eric R.

2016-01-01

Dopamine neurotransmission in the dorsal hippocampus is critical for a range of functions from spatial learning and synaptic plasticity to the deficits underlying psychiatric disorders such as attention-deficit hyperactivity disorder. The ventral tegmental area (VTA) is the presumed source of dopamine in the dorsal hippocampus. However, there is a surprising scarcity of VTA dopamine axons in the dorsal hippocampus despite the dense network of dopamine receptors. We have explored this apparent paradox using optogenetic, biochemical, and behavioral approaches and found that dopaminergic axons and subsequent dopamine release in the dorsal hippocampus originate from neurons of the locus coeruleus (LC). Photostimulation of LC axons produced an increase in dopamine release in the dorsal hippocampus as revealed by high-performance liquid chromatography. Furthermore, optogenetically induced release of dopamine from the LC into the dorsal hippocampus enhanced selective attention and spatial object recognition via the dopamine D1/D5 receptor. These results suggest that spatial learning and memory are energized by the release of dopamine in the dorsal hippocampus from noradrenergic neurons of the LC. The present findings are critical for identifying the neural circuits that enable proper attention selection and successful learning and memory. PMID:27930324

Dopamine release from the locus coeruleus to the dorsal hippocampus promotes spatial learning and memory.

PubMed

Kempadoo, Kimberly A; Mosharov, Eugene V; Choi, Se Joon; Sulzer, David; Kandel, Eric R

2016-12-20

Dopamine neurotransmission in the dorsal hippocampus is critical for a range of functions from spatial learning and synaptic plasticity to the deficits underlying psychiatric disorders such as attention-deficit hyperactivity disorder. The ventral tegmental area (VTA) is the presumed source of dopamine in the dorsal hippocampus. However, there is a surprising scarcity of VTA dopamine axons in the dorsal hippocampus despite the dense network of dopamine receptors. We have explored this apparent paradox using optogenetic, biochemical, and behavioral approaches and found that dopaminergic axons and subsequent dopamine release in the dorsal hippocampus originate from neurons of the locus coeruleus (LC). Photostimulation of LC axons produced an increase in dopamine release in the dorsal hippocampus as revealed by high-performance liquid chromatography. Furthermore, optogenetically induced release of dopamine from the LC into the dorsal hippocampus enhanced selective attention and spatial object recognition via the dopamine D1/D5 receptor. These results suggest that spatial learning and memory are energized by the release of dopamine in the dorsal hippocampus from noradrenergic neurons of the LC. The present findings are critical for identifying the neural circuits that enable proper attention selection and successful learning and memory.

Cutaneous synergistic analgesia of bupivacaine in combination with dopamine in rats.

PubMed

Tzeng, Jann-Inn; Wang, Jieh-Neng; Wang, Jhi-Joung; Chen, Yu-Wen; Hung, Ching-Hsia

2016-05-04

The main goal of the study was to investigate the interaction between bupivacaine and dopamine on local analgesia. After the blockade of the cutaneous trunci muscle reflex (CTMR) responses, which occurred following the drugs were subcutaneously injected in rats, the cutaneous analgesic effect of dopamine in a dosage-dependent fashion was compared to that of bupivacaine. Drug-drug interactions were evaluated by isobolographic methods. We showed the dose-dependent effects of dopamine on infiltrative cutaneous analgesia. On the 50% effective dose (ED50) basis, the rank of drug potency was bupivacaine (1.99 [1.92-2.09] μmol/kg) greater than dopamine (190 [181-203] μmol/kg) (P<0.01). At the equianalgesic doses (ED25, ED50, and ED75), dopamine elicited a similar duration of cutaneous analgesia compared with bupivacaine. The addition of dopamine to the bupivacaine solution exhibited a synergistic effect. Our pre-clinical data showed that dopamine produced a dose-dependent effect in producing cutaneous analgesia. When compared with bupivacaine, dopamine produced a lesser potency with a similar duration of cutaneous analgesia. Dopamine added to the bupivacaine preparation resulted in a synergistic analgesic effect. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

An electrochemical dopamine sensor based on the ZnO/CuO nanohybrid structures.

PubMed

Khun, K; Ibupoto, Z H; Liu, X; Mansor, N A; Turner, A P F; Beni, V; Willander, M

2014-09-01

The selective detection of dopamine (DA) is of great importance in the modern medicine because dopamine is one of the main regulators in human behaviour. In this study, ZnO/CuO nanohybrid structures, grown on the gold coated glass substrate, have been investigated as a novel electrode material for the electrochemical detection of dopamine. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques were used for the material characterization and the obtained results are in good agreement. The selective determination of dopamine was demonstrated by cyclic voltammetry (CV) and amperometric experiments. The amperometric response was linear for dopamine concentrations between 1.0 x 10(-3) and 8.0 mM with a sensitivity of 90.9 μA mM(-1) cm(-2). The proposed dopamine biosensor is very stable, selective over common interferents as glucose, uric acid and ascorbic acid, and also good reproducibility was observed for seven electrodes. Moreover, the dopamine sensor exhibited a fast response time of less than 10 s. The wide range and acceptable sensitivity of the presented dopamine sensor provide the possible application in analysing the dopamine from the real samples.

Salience attribution and its relationship to cannabis-induced psychotic symptoms.

PubMed

Bloomfield, M A P; Mouchlianitis, E; Morgan, C J A; Freeman, T P; Curran, H V; Roiser, J P; Howes, O D

2016-12-01

Cannabis is a widely used drug associated with increased risk for psychosis. The dopamine hypothesis of psychosis postulates that altered salience processing leads to psychosis. We therefore tested the hypothesis that cannabis users exhibit aberrant salience and explored the relationship between aberrant salience and dopamine synthesis capacity. We tested 17 cannabis users and 17 age- and sex-matched non-user controls using the Salience Attribution Test, a probabilistic reward-learning task. Within users, cannabis-induced psychotic symptoms were measured with the Psychotomimetic States Inventory. Dopamine synthesis capacity, indexed as the influx rate constant K i cer , was measured in 10 users and six controls with 3,4-dihydroxy-6-[18F]fluoro-l-phenylalanine positron emission tomography. There was no significant difference in aberrant salience between the groups [F 1,32 = 1.12, p = 0.30 (implicit); F 1,32 = 1.09, p = 0.30 (explicit)]. Within users there was a significant positive relationship between cannabis-induced psychotic symptom severity and explicit aberrant salience scores (r = 0.61, p = 0.04) and there was a significant association between cannabis dependency/abuse status and high implicit aberrant salience scores (F 1,15 = 5.8, p = 0.03). Within controls, implicit aberrant salience was inversely correlated with whole striatal dopamine synthesis capacity (r = -0.91, p = 0.01), whereas this relationship was non-significant within users (difference between correlations: Z = -2.05, p = 0.04). Aberrant salience is positively associated with cannabis-induced psychotic symptom severity, but is not seen in cannabis users overall. This is consistent with the hypothesis that the link between cannabis use and psychosis involves alterations in salience processing. Longitudinal studies are needed to determine whether these cognitive abnormalities are pre-existing or caused by long-term cannabis use.

Attenuating GABAA Receptor Signaling in Dopamine Neurons Selectively Enhances Reward Learning and Alters Risk Preference in Mice

PubMed Central

Parker, Jones G.; Wanat, Matthew J.; Soden, Marta E.; Ahmad, Kinza; Zweifel, Larry S.; Bamford, Nigel S.; Palmiter, Richard D.

2011-01-01

Phasic dopamine transmission encodes the value of reward-predictive stimuli and influences both learning and decision-making. Altered dopamine signaling is associated with psychiatric conditions characterized by risky choices such as pathological gambling. These observations highlight the importance of understanding how dopamine neuron activity is modulated. While excitatory drive onto dopamine neurons is critical for generating phasic dopamine responses, emerging evidence suggests that inhibitory signaling also modulates these responses. To address the functional importance of inhibitory signaling in dopamine neurons, we generated mice lacking the β3 subunit of the GABAA receptor specifically in dopamine neurons (β3-KO mice) and examined their behavior in tasks that assessed appetitive learning, aversive learning, and risk preference. Dopamine neurons in midbrain slices from β3-KO mice exhibited attenuated GABA-evoked inhibitory post-synaptic currents. Furthermore, electrical stimulation of excitatory afferents to dopamine neurons elicited more dopamine release in the nucleus accumbens of β3-KO mice as measured by fast-scan cyclic voltammetry. β3-KO mice were more active than controls when given morphine, which correlated with potential compensatory upregulation of GABAergic tone onto dopamine neurons. β3-KO mice learned faster in two food-reinforced learning paradigms, but extinguished their learned behavior normally. Enhanced learning was specific for appetitive tasks, as aversive learning was unaffected in β3-KO mice. Finally, we found that β3-KO mice had enhanced risk preference in a probabilistic selection task that required mice to choose between a small certain reward and a larger uncertain reward. Collectively, these findings identify a selective role for GABAA signaling in dopamine neurons in appetitive learning and decision-making. PMID:22114279

Interaction of childhood urbanicity and variation in dopamine genes alters adult prefrontal function as measured by functional magnetic resonance imaging (fMRI).

PubMed

Reed, Jessica L; D'Ambrosio, Enrico; Marenco, Stefano; Ursini, Gianluca; Zheutlin, Amanda B; Blasi, Giuseppe; Spencer, Barbara E; Romano, Raffaella; Hochheiser, Jesse; Reifman, Ann; Sturm, Justin; Berman, Karen F; Bertolino, Alessandro; Weinberger, Daniel R; Callicott, Joseph H

2018-01-01

Brain phenotypes showing environmental influence may help clarify unexplained associations between urban exposure and psychiatric risk. Heritable prefrontal fMRI activation during working memory (WM) is such a phenotype. We hypothesized that urban upbringing (childhood urbanicity) would alter this phenotype and interact with dopamine genes that regulate prefrontal function during WM. Further, dopamine has been hypothesized to mediate urban-associated factors like social stress. WM-related prefrontal function was tested for main effects of urbanicity, main effects of three dopamine genes-catechol-O-methyltransferase (COMT), dopamine receptor D1 (DRD1), and dopamine receptor D2 (DRD2)-and, importantly, dopamine gene-by-urbanicity interactions. For COMT, three independent human samples were recruited (total n = 487). We also studied 253 subjects genotyped for DRD1 and DRD2. 3T fMRI activation during the N-back WM task was the dependent variable, while childhood urbanicity, dopamine genotype, and urbanicity-dopamine interactions were independent variables. Main effects of dopamine genes and of urbanicity were found. Individuals raised in an urban environment showed altered prefrontal activation relative to those raised in rural or town settings. For each gene, dopamine genotype-by-urbanicity interactions were shown in prefrontal cortex-COMT replicated twice in two independent samples. An urban childhood upbringing altered prefrontal function and interacted with each gene to alter genotype-phenotype relationships. Gene-environment interactions between multiple dopamine genes and urban upbringing suggest that neural effects of developmental environmental exposure could mediate, at least partially, increased risk for psychiatric illness in urban environments via dopamine genes expressed into adulthood.