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Functional cage-amine complexes : polymerisable metallomonomers and multi-cage complexesLengkeek, Nigel Andrew January 2008 (has links)
[Truncated abstract] Chapter 1 provides an introduction to the 'sarcophagine' class of ligands and the field of metallopolymers. The synthesis, stereochemistry, physical properties and functionalisation of 'sarcophagines' and their metal complexes are discussed. A brief overview of the burgeoning field of metallopolymers is given with specific mention of the synthetic routes to pendant metallopolymers, and how these could be employed to prepared cage amine containing metallopolymers. Chapter 2 deals with the synthesis, characterisation and reactivity of cinnamylamino and styrylamido derivatives of the cage amines [Co((NH2)2sar)]3+, [Co((CH3)(NH2)sar)]3+ and [Cu((NH2)2sar)]2+. The cinnamylamino derivatives were prepared using reductive alkylation of the aforementioned amines with cinnamaldehyde. Procedures were developed to isolate the complexes without causing unwanted additions to the double bond. The cinnamylamino derivatives displayed unexpected reactivity towards a range of reducing agents, resulting in unexpected reduction of the double bond and cleavage of the cinnamyl group, but ultimately in the preparation of phenylpropylamino derivatives of [Co((NH2)2sar)]3+ and [Co((CH3)(NH2)sar)]3+. Attempts to rationalise the reactivity of the double bond have been explored based upon the physical properties and reactivity of the double bond. The styrylamido derivatives were prepared by treatment of the cage amines with 4-vinylbenzoyl chloride, and the complexes isolated in a similar manner to those of the cinnamylamino derivatives to ensure the amide linkage remained intact. Most of the complexes have been structurally characterised. ... Both the 2-thienyl and 3-thienyl derivatives of [Co((NH2)2sar)]3+ and [Co((CH3)(NH2)sar)]3+ have been prepared using reductive alkylation with the respective carboxaldehydes of thiophene. One of the optically pure isomers has been prepared. The complexes have been fully characterised including structural characterisation. Polymerisation of the thiophene-cage amine complexes was investigated under a range of chemical and electrochemical conditions, though polymerisation was never observed. Cleavage of the thienyl groups was observed when ceric ammonium nitrate in nitric acid was used as the oxidant. The attachment of oligothiophenes and mixed pyrrole-thiophene oligomers to cage amines were investigated using reductive alkylation and various pyrrole ring-forming reactions about the apical amino groups, though none of the desired complexes were isolated, reasons for the lack of reactivity were discussed. An efficient synthesis of N-(4-benzoic acid)- 2,5-di(2-thienyl)pyrrole was developed and was shown to the electropolymerisable, albeit the polymer films were non-conducting. Attempts to couple N-(4-benzoic acid)- 2,5-di(2-thienyl)pyrrole with a cage amine via its acid chloride were complicated by decomposition reactions, the nature of one of these products is discussed. Chapter 5 presents investigations into the preparation of simple complexes containing multiple cage amines using alkylation and acylation procedures with aromatic substrates. The complexes were found to exhibit some interesting electrochemical and chemical properties, demonstrating that even simple multiple cage amine species can display complicated and interesting behaviour.
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Caractérisation physico-chimique des <br />interphases époxyde-amine / oxyde <br />ou hydroxyde métallique, et de leurs constituantsAufray, Maëlenn 28 October 2005 (has links) (PDF)
Les caractéristiques des systèmes collés ou peints époxyde-amine/métal dépendent des caractéristiques de chacun des constituants mais aussi de leur "combinaison". En particulier, l'interphase possède des propriétés spécifiques. La chimisorption de l'amine sur le métal et la dissolution de la couche d'hydroxyde initialement présente à sa surface sont simultanées. Le complexe organométallique créé réagit avec le monomère époxyde pour former un réseau aux propriétés physico-chimiques spécifiques. Lorsque la configuration des complexes permet leur cristallisation, et que leur produit de solubilité est dépassé, les complexes précipitent pour donner naissance à des cristaux de facteur de forme très important. Quand un polymère est réalisé avec ces complexes, les cristaux jouent le rôle de charges, induisant de nouvelles propriétés mécaniques. La formation d'une interphase a été observée en appliquant plusieurs amines sur différents métaux. La variation des propriétés physico-chimiques et mécaniques a été évaluée.
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Résines époxy/amine pour le rotomoulage réactif : étude de la rhéocinétique et simulation numérique de l'écoulementMounif, Eskandar 14 March 2008 (has links) (PDF)
Cette thèse porte sur l'étude rhéocinétique de deux systèmes époxy/amine, DGEBA/DETDA et DGEBA/IPD pour le rotomoulage réactif. Les paramètres cinétiques du mécanisme auto-catalytique et non catalytique de la réticulation isotherme ont été identifiés par une méthode inverse à l'aide des résultats du suivi cinétique par spectroscopie proche infra rouge (PIR). La différence du comportement rhéocinétique entre les deux systèmes est attribuée à la différence de réactivité intrinsèque des groupes amines mis en jeu et l'importance de l'effet de substitution (réactivité des amines primaires par rapport aux amines secondaire) des deux durcisseurs. Une nouvelle méthode de détermination de l'effet de substitution a été établie, en utilisant les taux de conversion de l'époxy et de l'amine primaire mesurées par PIR. L'analyse des phénomènes de vitrification et gélification des deux systèmes a permis d'établir le diagramme Temps-Température-Transformation (TTT). La comparaison de la rotomoulabilité des deux systèmes a été effectuée par l'ajout des courbes d'iso-viscosité sur le diagramme TTT. L'écoulement au cours du rotomoulage a été modélisé par un écoulement à surface libre sous gravité d'un fluide réactif à l'intérieure d'un cylindre horizontal en rotation autour de son axe principal. Dans le cas des fluides de viscosité faible, la méthode lagrangienne de Smoothed Particle Hydrodynamics SPH, a été appliquée en utilisant une expression adaptée de la viscosité.
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Semicarbazide-sensitive Amine Oxidase (SSAO) – Regulation and Involvement in Blood Vessel Damage with Special Regard to Diabetes : A Study on Mice Overexpressing Human SSAOGöktürk, Camilla January 2004 (has links)
<p>Semicarbazide-sensitive amine oxidase (SSAO, EC 1.4.3.6) belongs to a family of copper-containing amine oxidases. SSAO exists as a membrane bound protein in endothelial-, smooth muscle-, and adipose cells as well as soluble in plasma. SSAO catalyses oxidative deamination of primary monoamines, which results in the production of corresponding aldehydes, hydrogen peroxide and ammonia. These compounds are very reactive and potentially cytotoxic, and are able to induce vascular damage if produced in high levels. Patients with diabetes mellitus, and with diabetic complications in particular, have a higher SSAO activity in plasma compared to healthy controls. It has therefore been speculated that high SSAO activity is involved in the development of vascular complications associated with diabetes. The aim of this thesis is to investigate the importance of SSAO in the development of disorders of a vascular origin. We have studied the transcriptional regulation of the SSAO gene, by inducing diabetes in NMRI and in transgenic mice, overexpressing the human form of SSAO in smooth muscle cells. We found that the increase in SSAO activity in diabetes is accompanied by reduced mRNA levels of the endogenous mouse gene, suggesting a negative feedback on the transcription of the SSAO gene. In addition, the transgenic mice exhibited an abnormal phenotype in the elastic tissue of aorta and renal artery. These mice have a lower mean artery pressure and an elevated pulse pressure. These results indicate that high SSAO activity in smooth muscle cells is associated with a change in the morphology of large arteries. This is likely contributing to the development of vascular complications in diabetes.</p>
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Self-Structuring of functionalized micro- and mesoporous organosilicas using boron-silane-precursorsIde, Andreas Hans Peter January 2008 (has links)
The structuring of porous silica materials at the nanometer scale and their surface functionalization are important issues of current materials research. Many innovations in chromatography, catalysis and electronic devices benefit from this knowledge.
The work at hand is dedicated to the targeted design of functional organosilica materials. In this context a new precursor concept based on boron-silanes is presented. These precursors combine the properties of a structure directing group and a silica source by covalent borane linkage. Formation of the precursor is easily realized by a sequential two-step hydroboration, firstly on bis(triethoxysilyl)ethene, and secondly on an unsaturated structure directing moiety such as alkenes or polymers. The so prepared precursors self-organize when hydrolysis of their inorganic moiety takes place via an aggregation of their organic side chains into hydrophobic domains. In this way, the additional use of a surfactant as a template is not necessary. Chemical cleavage of these moieties (e.g. by ammonolysis or oxidative saponification) yields an organosilica where all functionalities are exclusively located at the pore wall and therefore accessible. The accessibility of the functionalities is a vital point for applications and is not necessarily granted for common silica functionalization approaches. Further advantages of the boron-silane concept are the possibility to introduce a variety of surface functionalities by heterolytic cleavage of the boron linker and the control of the pore morphology. For that purpose the covalent linkage of different alkyl groups and polymers was studied. Another aspect is the access to chiral boron silane precursors yielding functionalized mesoporous organosilica with chiral functionalities exclusively located at the pore walls after condensation and removal of the structure directing moiety. These materials possess great potential for applications documented by preliminary investigations on chiral resolution of a racemic mixture by HPLC and asymmetric catalysis.
In the course of this work valuable insights into the targeted structuring and surface functionalization of organosilicas were gained. A promising outlook for further investigations is the extension of this concept by altering the structure directing moieties of the precursor. That way the morphology of the final organosilica might be controlled by for example mesogens. Furthermore, the use of the boron linker enables the introduction of multiple functionalities into organosilicas, making the obtained material unique in its performance. / Die Nanostrukturierung von funktionalisierten porösen Materialien auf Silikatbasis steht im Brennpunkt der aktuellen Forschung. Anwendungen wie Chromatographie, Katalyse oder die Herstellung elektronischer Bauteile profitieren von den Erkenntnissen, die auf diesem Gebiet gewonnen werden.
Die vorliegende Arbeit soll einen Beitrag zur gezielten Herstellung dieser Funktions-materialien leisten. Hierfür wurde ein neues Precursor-Konzept auf der Basis von Borsilanen vorgestellt. Diese Precursoren werden über eine sequentielle zweistufige Hydroborierung an Bis(triethoxysilyl)ethene und ein Alken oder ein ungesättigtes Polymer erhalten. Über den zweiten Schritt wird hierbei die so genannte strukturgebende Gruppe eingeführt und damit das Template kovalent gebunden. Dadurch entfällt im Vergleich zum bekannten Nanocasting-Mechanismus zum einen die Verwendung des herkömmlichen Templates für die Bildung der Porenstruktur und zusätzlich führt die Mikrophasenseparation während der Kondensation zu einer Anordnung der strukturgebenden Gruppen des Precursors an der Silikatphasengrenze. Nach der chemischen Abspaltung dieser Gruppen, die gleichzeitig zur Einführung funktioneller Gruppen führt, werden somit hochporöse Organosilikate erhalten, in denen sich die funktionellen Gruppen ausschließlich an der Porenoberfläche befinden. Ein Vorteil der Verwendung der Hydroborieung wird in der Vielfalt der funktionellen Gruppen deutlich, die eingeführt werden können. Die Zugänglichkeit der funktionellen Gruppen ist entscheidend für potentielle Anwendungen und bei herkömmlichen Organosilikaten nicht zwangsläufig gegeben. Ein herausragender Aspekt dieses Konzepts besteht in der Möglichkeit, sehr einfach chirale Precursoren und damit Organosilikate mit hoch funktionalisierten, chiralen Oberflächen herzustellen. Es konnte gezeigt werden, dass sich diese Materialien sowohl für die chromatographische Trennung von Racematen mittels HPLC als auch für die asymmetrische Katalyse eignen.
Durch die in dieser Arbeit erhaltenen Ergebnisse konnten wertvolle Erkenntnisse zur Ober-flächenfunktionalisierung und Strukturierung von mesoporösen Silikaten gewonnen werden. Die Möglichkeit, das vorgestellte Konzept auf andere strukturgebende Gruppen wie zum Beispiel Mesogene zu übertragen und damit die Porenmorphologie gezielt zu steuern, eröffnet viele weitere interessante Materialeigenschaften.
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Stabile Expression von Sulfotransferasen - allein oder in Kombination mit Cytochrom P450 - in Zelllinien für MutagenitätsuntersuchungenPabel, Ulrike January 2003 (has links)
<P align=justify>Aromatische Amine und Amide (aAA) sind aufgrund ihrer starken Verbreitung in der menschlichen Umwelt und ihres kanzerogenen Potenzials von großer toxikologischer Bedeutung. Die Kanzerogenität der aAA wird durch die Mutagenität hochreaktiver Stoffwechselprodukte vermittelt, die in zwei sequenziellen katalytischen Reaktionen entstehen. Die erste ist meistens eine <I>N</I>-Hydroxylierung, die oft durch Cytochrom P450 1A2 (CYP1A2) katalysiert wird. Daran schließt sich eine <I>O</I>-Konjugation durch Sulfotransferasen (SULT) oder <I>N</I>-Acetyltransferasen (NAT) an. Die Bioaktivierung ist ein kritischer Parameter für die Übertragbarkeit von Ergebnissen aus Tiermodellen auf den Menschen. </P><P align=justify>Rekombinante <I>in vitro</I> Systeme, die fremdstoffmetabolisierende Enzyme verschiedener Spezies exprimieren, ermöglichen die vergleichende Untersuchung der Bioaktivierung im Menschen und in Versuchstieren. Ziel des Projektes war die Aufklärung der Bioaktivierung der aAA durch humane Enzyme. Im Vordergrund stand die Untersuchung der Rolle humaner SULT in diesem Prozess. Es wurden rekombinante <I>in vitro</I> Systeme, konstruiert, die CYP1A2 und SULT des Menschen koexprimieren. SULT-cDNAs wurden in den Säugerzell Expressionsvektor pMPSV kloniert und in Standardindikatorzellen für Mutagenitätsuntersuchungen (V79 Zellen aus dem Chinesischen Hamster) transfiziert. Das Expressionsniveau von CYP1A2 und SULT wurde mittels Immunblotanalyse und radiometrischen Aktivitätsmessungen charakterisiert. In den rekombinanten Zellen wurden vier aAA als Modellsubstanzen (2-Acetylaminofluoren, 2-Aminoanthracen, 3′-Methyl-4-dimethylaminoazobenzol, 2,4-Diaminotoluol) auf ihre Mutagenität am <I>hprt</I>-Locus hin untersucht.</P><P align=justify>Die aAA waren in Zellen, die keine rekombinanten Enzyme oder lediglich CYP1A2 exprimierten, nicht mutagen. In Zellen, die CYP1A2 und SULT der Subfamilie 1A koexprimierten, erzeugten sie bereits in geringen Konzentrationen klare mutagene Effekte (0,3 µM für 2-Acetylaminofluoren <br />
und 3′-Methyl-4-dimethylaminoazobenzol; 0,1 µM für 2-Aminoanthracen; 10 µM für 2,4-Diaminotoluol). Die stärkste Aktivierung von 2-Acetylaminofluoren und 3′-Methyl-4-dimethylaminoazobenzol erfolgte in der Zelllinie, die CYP1A2 und SULT1A2 koexprimierte; die stärkste Aktivierung von 2,4-Diaminotoluol und 2-Aminoanthracen erfolgte in der Zelllinie, die CYP1A2 und SULT1A1 koexprimierte. </P><P align=justify>Sowohl SULT1A1 als auch SULT1A2 sind im Menschen genetisch polymorph. Ein unterschiedlich starkes Aktivierungspotenzial der Alloenzyme könnte eine individuell unterschiedliche Suszeptibilität für die durch aAA ausgelöste Kanzerogenese bedingen. In HPRT-Mutationsuntersuchungen mit rekombinanten Zellen zeigten die allelischen Varianten der SULT1A2 starke Unterschiede in ihrem Aktivierungpotenzial. Nur in der Zelllinie, die das Alloenzym SULT1A2*1 mit CYP1A2 koexprimierte, wurde 2-Acetylaminofluoren zum Mutagen aktiviert. Zur Aktivierung von 3′-Methyl-4-dimethylaminoazobenzol waren jedoch sowohl das Alloenzym SULT1A2*1 als auch das Alloenzym SULT1A2*2 in der Lage. Die Alloenzyme der SULT1A1 zeigten ein ähnlich gutes Aktivierungspotenzial für aAA. </P><P align=justify>In früheren Studien wurde gezeigt, dass die SULT1C1 der Ratte eine wichtige Rolle bei der Aktivierung der aAA in dieser Spezies spielt. Dahingegen war die humane SULT1C1 nicht in der Lage die untersuchten aAA zu aktivieren. Die Kenntnis solcher Spezieunterschiede könnte wichtig sein um unterschiedliche Organotropismen aAA in Menschen und Tiermodellen zu erklären, da SULT mit starker Gewebespezifität exprimiert werden und das Expressionsmuster für die einzelnen SULT-Formen in Menschen und Ratten sich stark unterscheidet.</P><br> / <P align=justify>Aromatic amines and amides (aAA) represent a group of chemicals with great toxicological importance due to their wide distribution in the environment and their carcinogenic potency. The carcinogenicity of aAA is mediated by the mutagenic action of highly reactive metabolites. They are frequently formed by <I>N</I>-hydroxylation of the exocyclic amino group, usually catalysed by cytochrome P450 1A2 (CYP1A2) and subsequent <I>O</I>-conjugation by phase-II enzymes e.g. sulfotransferases (SULT) or <I>N</I>-acetyltransferases. </P> <P align=justify>The bioactivation constitutes a critical parameter for the transfer of results from animal models on man. Recombinant <I>in vitro</I> systems expressing xenobiotic metabolizing enzymes of different species allow the comparative study of the bioactivation in humans and animal models. <BR>The aim of this project was to elucidate the bioactivation of aAA by human xenobiotic enzymes. The investigation focused on the role of SULT in this process. SULT-cDNAs were cloned into the mammalian expression vector pMPSV and transfected in V79 Chinese Hamster cells, which represent standard indicator cells for mutagenicity tests. Selected SULT-cDNAs were also co-expressed with human CYP1A2. These cells were able to catalyse internally both enzymatic reactions that are necessary for the bioactivation of aAA. The expression level of CYP1A2 and SULT in the co-expressing cell clones was characterised by immunoblot analysis and radiometric SULT-activity measurement. The mutagenicity of four aAA model compounds, 2-aminoanthracene, 2-acetylaminofluorene, 3'-methyl-4-dimethylaminoazobenzene and 2,4-diaminotoluene, at the <I>hprt</I> locus of the recombinant cell lines was investigated.</P><br />
<P align=justify>These aAA were not or only marginally mutagenic in wild type cells or in recombinant cells expressing CYP1A2 alone. If CYP1A2 was co-expressed with SULT forms of the 1A subfamily clear mutagenic effects occured in low concentrations of the aAA (0,3 µM for 2-acetylaminofluorene and 3′-methyl-4-dimethylaminoazobenzene; 0,1 µM for 2-aminoanthracene; 10 µM for 2,4-diaminotoluene). The strongest activation of 2-acetylaminofluorene and 3'-methyl-4-dimethylaminoazobenzene was mediated by SULTA2 and of 2-aminoanthracene and 2,4-diaminotoluene by SULT1A1. </P><br />
<P align=justify>SULT1A1 and SULT1A2 are expressed polymorphically in humans. Differences in the activation potency of distinct alloenzymes for aAA may cause divergent individual susceptibilities for cancer induced by aAA. Briefly, the allelic variants of SULT1A2 showed substantial differences regarding their activation potencies for the investigated aAA. Only alloenzyme SULT1A2*1 was able to activate 2-acetylaminofluorene to a mutagen whereas 3′-methyl-4-di-methylaminoazobenzene was activated by alloenzymes SULT1A2*1 and SULT1A2*2. The investigated alloenzymes of SULT1A1 showed equal activation potencies for aAA. </P><br />
<P align=justify>In previous studies it had been shown that the SULT1C1 plays an important role in the activation of aAA in rats. However, the human SULT1C1 was not able to activate the investigated aAA in the study presented here. Such species differences might be important for the elucidation of divergent organotropisms of aAA in humans and animal models, since SULT are expressed with strong tissue specificities and the pattern of expression in humans and rats is severely different.</P><br>
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Analysis of two D1-like dopamine receptors from the honey bee Apis mellifera reveals agonist-independent activityBlenau, Wolfgang, Mustard, Julie A., Hamilton, Ingrid S., Ward, Vernon K., Ebert, Paul R., Mercer, Alison R. January 2003 (has links)
Dopamine is found in many invertebrate organisms, including insects, however, the mechanisms through which this amine operates remain unclear. We have expressed two dopamine receptors cloned from honey bee (AmDOP1 and AmDOP2) in insect cells (Spodoptera frugiperda), and compared their pharmacology directly using production of cAMP as a functional assay. In each assay, AmDOP1 receptors required lower concentrations of dopamine and 6,7-ADTN for maximal activation than AmDOP2 receptors. Conversely, butaclamol and cis(Z)-flupentixol were more potent at blocking the cAMP response mediated through AmDOP2 than AmDOP1 receptors. Expression of AmDOP1, but not AmDOP2, receptors significantly increased levels of cAMP even in the absence of ligand. This constitutive activity was blocked by cis(Z)-flupentixol. This work provides the first evidence of a constitutively activated dopamine receptor in invertebrates and suggests that although AmDOP1 and AmDOP2 share much less homology than their vertebrate counterparts, they display a number of functional parallels with the mammalian D1-like dopamine receptors.
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Molecular and functional characterization of an octopamine receptor from honeybee (Apis mellifera) brainBlenau, Wolfgang, Grohmann, Lore, Erber, Joachim, Ebert, Paul R., Strünker, Timo, Baumann, Arnd January 2003 (has links)
Biogenic amines and their receptors regulate and modulate many physiological and behavioural processes in animals. In vertebrates, octopamine is only found in trace amounts and its function as a true neurotransmitter is unclear. In protostomes, however, octopamine can act as neurotransmitter, neuromodulator and neurohormone. In the honeybee, octopamine acts as a neuromodulator and is involved in learning and memory formation. The identification of potential octopamine receptors is decisive for an understanding of the cellular pathways involved in mediating the effects of octopamine. Here we report the cloning and functional characterization of the first octopamine receptor from the honeybee, Apis mellifera . The gene was isolated from a brain-specific cDNA library. It encodes a protein most closely related to octopamine receptors from Drosophila melanogaster and Lymnea stagnalis . Signalling properties of the cloned receptor were studied in transiently transfected human embryonic kidney (HEK) 293 cells. Nanomolar to micromolar concentrations of octopamine induced oscillatory increases in the intracellular Ca2+ concentration. In contrast to octopamine, tyramine only elicited Ca2+ responses at micromolar concentrations. The gene is abundantly expressed in many somata of the honeybee brain, suggesting that this octopamine receptor is involved in the processing of sensory inputs, antennal motor outputs and higher-order brain functions.
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Pharmacology of serotonin-induced salivary secretion in Periplaneta americanaBlenau, Wolfgang, Troppmann, Britta, Walz, Bernd January 2007 (has links)
The acinar salivary gland of the cockroach, Periplaneta americana, is innervated by dopaminergic and serotonergic nerve fibers. Stimulation of the glands by serotonin (5-hydroxytryptamine, 5-HT) results in the production of a protein-rich saliva, whereas stimulation by dopamine results in saliva that is protein-free. Thus, dopamine acts selectively on ion-transporting peripheral cells within the acini, and 5-HT acts on protein-producing central cells. We have investigated the pharmacology of the 5-HT-induced secretory activity of isolated salivary glands of P. americana by testing several 5-HT receptor agonists and antagonists. The effects of 5-HT can be mimicked by the non-selective 5-HT receptor agonist 5-methoxytryptamine. All tested agonists that display at least some receptor subtype specificity in mammals, i.e., 5-carboxamidotryptamine, (+/-)-8-OH-DPAT, (+/-)-DOI, and AS 19, were ineffective in stimulating salivary secretion. 5-HT-induced secretion can be blocked by the vertebrate 5-HT receptor antagonists methiothepin, cyproheptadine, and mianserin. Our pharmacological data indicate that the pharmacology of arthropod 5-HT receptors is remarkably different from that of their vertebrate counterparts. (C) 2007 Elsevier Ltd. All rights reserved.
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Molecular characterization and localization of the first tyramine receptor of the American cockroach (Periplaneta americana)Blenau, Wolfgang, Rotte, Cathleen, Krach, Christian, Balfanz, Sabine, Baumann, Arnd, Walz, Bernd January 2009 (has links)
The phenolamines octopamine and tyramine control, regulate, and modulate many physiological and behavioral processes in invertebrates. Vertebrates possess only small amounts of both substances, and thus, octopamine and tyramine, together with other biogenic amines, are referred to as “trace amines.” Biogenic amines evoke cellular responses by activating G-protein-coupled receptors. We have isolated a complementary DNA (cDNA) that encodes a biogenic amine receptor from the American cockroach Periplaneta americana, viz., Peatyr1, which shares high sequence similarity to members of the invertebrate tyramine-receptor family. The PeaTYR1 receptor was stably expressed in human embryonic kidney (HEK) 293 cells, and its ligand response has been examined. Receptor activation with tyramine reduces adenylyl cyclase activity in a dose-dependent manner (EC50 350 nM). The inhibitory effect of tyramine is abolished by co-incubation with either yohimbine or chlorpromazine. Receptor expression has been investigated by reverse transcription polymerase chain reaction and immunocytochemistry. The mRNA is present in various tissues including brain, salivary glands, midgut, Malpighian tubules, and leg muscles. The effect of tyramine on salivary gland acinar cells has been investigated by intracellular recordings, which have revealed excitatory presynaptic actions of tyramine. This study marks the first comprehensive molecular, pharmacological, and functional characterization of a tyramine receptor in the cockroach.
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