Purinerge P2X3-Rezeptoren spielen eine bedeutende Rolle in der Vermittlung chronischer Schmerzen, welche ein führendes Problem des Gesundheitswesens mit vielen sozioökonomischen Konsequenzen darstellen. Die Tatsache, dass P2X3-Rezeptoren fast ausschließlich von nozizeptiven Neuronen exprimiert werden, macht sie trotz ihres besonderen Desensitisierungsverhaltens zu vielversprechenden Angriffspunkten zukünftiger Schmerztherapien, beispielsweise mithilfe kompetitiver Antagonisten an diesen Rezeptoren. Zur Analyse der Wechselwirkungen zwischen Agonist und kompetitivem Antagonist wird meist der Schild-Plot benutzt. Jedoch ist dieser im Falle der sehr schnell desensitisierenden P2X3-Rezeptoren ungeeignet, da die Vorbedingung eines stabilen Gleichgewichts zwischen Agonist und Antagonist aufgrund der Desensitisierung nicht erfüllt ist. Ziel der vorliegenden Arbeit war es, eine neue Methode zur Analyse der Interaktion kompetitiver Antagonisten mit ihrer Bindungsstelle am Beispiel des P2X3-Rezeptors zu entwickeln und so für die Antagonistenbindung bedeutende Aminosäuren der Bindungsstelle zu identifizieren. Mittels der Patch-Clamp-Technik wurden die Effekte der Antagonisten A-317491, TNP-ATP und PPADS auf die vom P2X1,3-Rezeptor-selektiven Agonisten α,β-MeATP induzierten Ströme am P2X3-Wildtyp-Rezeptor und an fünf Rezeptormutanten mit veränderter Ligandenbindungsstelle untersucht. Alle Rezeptoren wurden in HEK293-Zellen exprimiert. Anhand der gemessenen Daten wurde ein Hidden Markov Model (HMM) erstellt, welches die sequentiellen Übergänge des Rezeptors von geschlossen zu offen und desensitisiert in An- und Abwesenheit des Antagonisten miteinander kombiniert. Die am P2X3-Rezeptor induzierten Ströme konnten mithilfe dieses Modells korrekt gefittet und die für die Antagonistenbindung wichtigen Aminosäuren innerhalb der Bindungsstelle bestimmt werden. Als Resultat dieser Arbeit konnte außerdem gezeigt werden, dass das HMM eine geeignete Methode zur Analyse der Wirkung kompetitiver Antagonisten an schnell desensitisierenden Rezeptoren darstellt. Die untersuchten Antagonisten A-317491 und TNP-ATP haben einen kompetitiven Wirkmechanismus, während PPADS eine pseudoirreversible Blockade verursacht.

Uppsatsen har gjort i syfte att undersöka porträtteringen av kvinnliga antagonister samt protagonister i två Disneyfilmer för att se om porträtteringen skiljer sig filmerna emellan. De filmer som varit aktuella för undersökningen har varit Snövit och de sju dvärgarna (1937) samt Trassel (2010). Materialet har analyserats utifrån representationsteori med nedstamp i stereotyper, genus samt mise-en-scéne inom animation. De valda metoder för analysen är en narrativ samt semiotisk analys där karaktärernas handlingar samt utseende tolkats för att sedan jämföras. Antagonisterna och protagonisterna från båda filmerna porträtteras likadant och har liknande narrativa funktioner, där antagonisten är kontrasterande och binär gentemot protagonisten som ses som filmens normala. / The purpose of this essay has been to analyze the female antagonists and protagonists in two films from Disney to see if the portrayal of these characters differentiate. The films fitting for the analysis are Snow White and the Seven Dwarfs (1937) and Tangled (2010). The material has been analyzed through a perspective of representation theory as well as stereotypes, gender and mise-en-scéne in animation. The methods chosen for this essay are a narrative analysis and a semiotic analysis where the characters’ actions and appearance  are being interpreted and compared. The antagonists and protagonists from both films are portrayed in a similar way and have narrative functions that are similar, where the antagonists are contrasting and binary opposite the protagonists who are viewed as the normal.

Traumatic brain injury (TBI) is a leading cause of death and long-term disability worldwide, and survivors are often left with cognitive deficits and significant problems with day to day tasks. To date, therapeutic pharmacological treatments of TBI remain elusive despite numerous clinical trials. An improved understanding of the molecular and cellular response to injury may help guide future treatment strategies. One promising marker for brain injury is the translocator protein (TSPO), which is normally expressed at a low level, but is highly expressed following brain damage and is associated with neuroinflammation. The isoquinoline carboxamide PK11195 binds selectively to the TSPO in many species, and has therefore become the most-studied TSPO ligand. To characterize the time-course of TSPO expression in the controlled cortical injury (CCI) model of TBI we subjected Sprague-Dawley rats to CCI and euthanatized them after 30 minutes, 12 hours, 1, 2, 4, or 6 days. Autoradiography with radiolabelled PK11195 was used to assess the time-course of TSPO binding following CCI. Autoradiographs were compared to adjacent tissue slices stained with the microglia/macrophage marker ED-1, with which a moderate positive correlation was discovered. PK11195 autoradiography was used as a tool with which to assess neuroinflammation following CCI and the administration of an α7 nAChR antagonist, methyllycaconitine (MLA). We hypothesized that blocking the calcium permeable α7 nAChR after brain injury would have a neuroprotective effect by attenuating excitotoxicity in the shortterm. Our study revealed clear dose-dependent tissue sparing in rats administered MLA after trauma and a modest improvement in functional outcome. The relatively modest recovery of function with MLA, which could be due to prolonged α7 nAChR blockade or downregulation lead us to explore the potential of α7 nAChR partial agonists in treating TBI. The α7 nAChR partial agonists tropisetron, ondansetron, and DMXB-A produced a moderate attenuation of cognitive deficits, but did not have a neuroprotective effect on tissue sparing. These studies show that following TBI, α7 nAChR modulation can have neuroprotective effects and attenuate cognitive deficits. Whether this modulation is best achieved through partial agonist treatment alone or a combination antagonist/agonist treatment remains to be determined.

Ultra-low doses (ULD) of the opioid receptor antagonists, naloxone and naltrexone, augment the analgesic actions of morphine, block the induction of tolerance, and reverse established tolerance by an unknown mechanism. Preclinical studies demonstrate that chronic morphine administration induces spinal gliosis and that inhibition of gliosis prevents the development of analgesic tolerance to opioids. Thus, this thesis investigated the inhibition of spinal gliosis as a mechanism by which ULD antagonists attenuate analgesic tolerance and opioid-induced hyperalgesia. Immune cell activation is implicated in the etiology of morphine tolerance and intrathecal catheterization, a technique commonly used to study the spinal effects of drugs, causes profound gliosis. Thus, the first study investigated the effects of catheter-induced gliosis on acute and chronic morphine analgesic tolerance. Catheterization-induced gliosis did not alter antinociceptive responses to acute intrathecal morphine; however, tolerance to chronic morphine was exacerbated in catheterized rats compared to sham and surgery-naïve controls. The potentiation of analgesic tolerance to chronic morphine by spinal gliosis provided evidence that glia modulate opioid analgesia; therefore, inhibition of opioid-induced activation of glia was explored as a potential mechanism by which ULD antagonists prevent tolerance. The second series of experiments reported morphine-induced activation of spinal microglia and astrocytes was blocked by co-administering ULD naltrexone with morphine. These findings prompted us to elucidate the specific molecular target through which ULD antagonists attenuate opioid analgesia. Activation of glial Toll-like receptor 4 (TLR4) induces gliosis and may contribute to analgesic tolerance and/or morphine-induced hyperalgesia (MIH). Antagonism of TLR4 by the opioid receptor-inactive (+) stereoisomer of naloxone was identified as a potential mechanism by which ULD antagonists modulate opioid analgesia. Tolerance and MIH developed in mice expressing non-functional TLR4 and in wildtype controls. Analgesic tolerance was stereoselectively blocked by ULD (-)naloxone, whereas MIH was blocked by both naloxone enantiomers. Collectively, these studies demonstrate analgesic tolerance and MIH occur through distinct mechanisms. ULD naloxone attenuates analgesic tolerance likely via an opioid receptor-mediated mechanism that is TLR4-independent. ULD antagonists do not attenuate tolerance via inhibition of spinal gliosis as hypothesized. In contrast, ULD antagonists prevent MIH by inhibiting opioid-induced gliosis in an opioid receptor- and TLR4-independent manner. Immune cell activation is implicated in the etiology of morphine tolerance and intrathecal catheterization, a technique commonly used to study the spinal effects of drugs, causes profound gliosis. Thus, the first study investigated the effects of catheter-induced gliosis on acute and chronic morphine analgesic tolerance. Catheterization-induced gliosis did not alter antinociceptive responses to acute intrathecal morphine; however, tolerance to chronic morphine was exacerbated in catheterized rats compared to sham and surgery-naïve controls. The potentiation of analgesic tolerance to chronic morphine by spinal gliosis provided evidence that glia modulate opioid analgesia; therefore, inhibition of opioid-induced activation of glia was explored as a potential mechanism by which ULD antagonists prevent tolerance. The second series of experiments reported morphine-induced activation of spinal microglia and astrocytes was blocked by co-administering ULD naltrexone with morphine. These findings prompted us to elucidate the specific molecular target through which ULD antagonists attenuate opioid analgesia. Activation of glial Toll-like receptor 4 (TLR4) induces gliosis and may contribute to analgesic tolerance and/or morphine-induced hyperalgesia (MIH). Antagonism of TLR4 by the opioid receptor-inactive (+) stereoisomer of naloxone was identified as a potential mechanism by which ULD antagonists modulate opioid analgesia. Tolerance and MIH developed in mice expressing non-functional TLR4 and in wildtype controls. Analgesic tolerance was stereoselectively blocked by ULD (-)naloxone, whereas MIH was blocked by both naloxone enantiomers. Collectively, these studies demonstrate analgesic tolerance and MIH occur through distinct mechanisms. ULD naloxone attenuates analgesic tolerance likely via an opioid receptor-mediated mechanism that is TLR4-independent. ULD antagonists do not attenuate tolerance via inhibition of spinal gliosis as hypothesized. In contrast, ULD antagonists prevent MIH by inhibiting opioid-induced gliosis in an opioid receptor- and TLR4-independent manner. / Thesis (Ph.D, Pharmacology & Toxicology) -- Queen's University, 2013-04-25 15:06:50.731

Thesis (MScMedSc)--Stellenbosch University, 2010. / ENGLISH ABSTRACT: Radiolabelled compounds have been widely used as investigative tools for psychiatric disorders using positron emission tomography (PET) or single photon emission tomography (SPECT) of the brain. In particular 123I-5-IR91150, a serotonin (5-HT) 2a antagonist, has been used for imaging the serotonergic system. The current study developed optimal radiolabelling and purification methods in our laboratory with the objective that it can provide 123I- 5-I-R91150 in sufficient quantity and of acceptable pharmaceutical quality for human use. Unlabelled R91150 was obtained from Janssen Pharmaceutica (Beerse, Belgium). Carrier free [123I]Iodine was produced by iThemba LABS, South Africa, via the 127I(p,5n)123Xe-123I reaction, providing Na[123I] in 0.05 N sodium hydroxide with a specific activity of 4000-6000 MBq/ml. A direct electrophilic radioiodination method of labelling was used in this study for labelling 123-I-5-IR91150 in glacial acetic acid. After radiolabelling, the product was purified using two different methods, namely a high performance liquid chromatography (HPLC) purification method and a solid phase extraction (SPE) method. The analyses of the purified product for both methods were done using HPLC. Methods were tested to reduce the volume of the purified product using C8 or C18 solid phase extraction cartridges. The average labelling efficiencies for SPE and HPLC purification methods were 76% ± 13.6% and 52% ± 11.2% respectively. The yields of 123I-5-I-R91150 were about 80%. Sep-Pak C8 and C18 were both unable to concentrate the HPLC purified product. Products from both purification methods were sterile and pyrogen free. Both SPE and HPLC purification methods have been shown to provide products meeting most criteria set for this study. However, both methods have advantages and disadvantages. The SPE purification method provided higher labelling efficiency and a much lower product volume. The stability of this product is however of concern as some free iodide was detected. If this purification method is used, the product should therefore be administered as soon as possible after completion of analysis. After HPLC purification, the undiluted product remained stable up to 4.15 hours after production but the product volume was relatively high, and purification time-consuming. In order to obtain a useful patient dose, labelling would have to start with at least 740 MBq 123I and the labelled product should be collected in fractions of 5 ml or less in order to obtain a fraction of sufficiently high specific activity. It was concluded that radiolabeling R91150 is possible at our institution, but that an improved HPLC system would be of value for routine production of a pure and safe product. / AFRIKAANSE OPSOMMING: Radioaktief gemerkte verbindings word baie gebruik as ondersoekmiddel vir psigiatriese afwykings met behulp van positron emissive tomografie (PET) of enkelfoton emissie tomografie (SPECT) van die brein. Die verbinding 123I-5-IR91150, ‘n serotonien (5-HT) 2a antagonis, is beskryf vir beelding van die serotonerge sisteem. Die huidige studie het ondersoek ingestel na optimale metodes vir radioaktiewe merking en suiwering vir ons laboratorium met die doel om 123I-5-I-R91150 in genoegsame hoeveelhed en van aanvaarbare farmaseutiese gehalte geskik vir menslike gebruik te verskaf. R91150 is van Janssen Pharmaceutica (Beerse, België) verkry. Draervry [123I]jodium is deur iThemba LABS, Suid-Afrika, via die 127I(p,5n)123Xe-123I reaksie geproduseer, om Na[123I] in 0.05 N natriumhidroksied met spesifieke aktiwiteit van 4000-6000 MBq/ml te lewer. ‘n Direkte elektrofiliese radioiodineringsmetode is in hierdie studie gebruik om 123-I-5-I-R91150 in ysasynsuur te merk. Na radioaktiewe merking is die radioaktiewe produk deur twee verskillende metodes gesuiwer, naamlik ‘n HPLC metode en ‘n soliede fase ekstraksie (SPE) metode. Vir beide metodes is die produk deur middel van HPLC analiseer. Metodes is getoets om die volume van die gemerkte produk met C8 of C18 SPE kolommetjies te verminder. Die gemiddelde bindingsdoeltreffendheid vir die SPE en HPLC suiweringsmetodes was 76% ± 13.6% en 52% ± 11.2% onderskeidelik. Die opbrengs van 123I-5-I-R91150 was ongeveer 80%. Sep-Pak C8 en C18 kon beide nie gebruik word om die HPLC gesuiwerde produk te konsentreer nie. Produkte van beide suiweringsmetodes was steriel en pirogeenvry. Daar is getoon dat beide suiweringsmetodes produkte lewer wat aan die meeste kriteria wat in hierdie studie gestel is, voldoen. Beide metodes het egter voor- en nadele. Die SPE suiweringsmetdode het tot hoër bindingsdoeltreffendheid gelei, asook ‘n baie laer produkvolume. Daar is egter ‘n mate van kommer oor die stabiliteit van die produk aangesien vry radiojodied waargeneem is. Indien hierdie suiweringsmetode gebruik word, moet die produk dus so gou as moontlik na voltooiing van analise toegedien word. Na HPLC suiwering was die onverdunde produk tot 4.15 uur na produksie stabiel maar die produkvolume was relatief hoog en suiwering tydrowend. Om ‘n bruikbare pasiëntdosis te verkry moet merking met ten minste 740 MBq 123I begin en die gemerkte produk moet na suiwering in fraksies van 5 ml of minder versamel word om ‘n fraksie met geskikte spesifieke aktiwiteit te verkry. Die gevolgtrekking is gemaak dat radioaktiewe merking van R91150 by ons instelling moontlik is, maar dat ‘n verbeterde HPLC sisteem vir roetineproduksie van ‘n suiwer en veilige produk van waarde sou wees.

L’adénosine est un nucléoside ubiquitaire qui exerce un contrôle puissant sur les systèmes nerveux,immunitaire et cardiovasculaire par l’intermédiaire de quatre récepteurs membranaires : A1R, A2AR, A2BR etA3R. L’étude des récepteurs de l’adénosine est nécessaire à la compréhension de physio‐pathologieshumaines non encore élucidées. Pour étudier l’expression des A2AR, nous avons, dans une première étude,produit un anticorps monoclonal, appelé Adonis, d’isotype IgM, . Adonis reconnait un épitope linéaire desept acides aminés sur la partie C‐terminale de la seconde boucle extra‐cellulaire de l’A2AR humain. Adonisrévèle, par Western blotting sur lysats cellulaires, une bande de 45 KDa, correspondant à l’A2AR. Adonis secomporte comme un « agonist‐like » en augmentant la production d’AMPc et en inhibant la proliférationcellulaire via la stimulation des A2AR. Dans une deuxième étude, nous avons utilisé Adonis pour montrerque l’expression des A2AR de cellules mononucléées, qui mime celle des tissus cardiaques, permet dedifférencier certains patients souffrant de syncope neurocardiogénique. Nous avons monté dans unetroisième étude, qu’Adonis induit une « down‐régulation » de l’expression des co‐récepteurs CXCR4 etCCR5 des cellules T via la stimulation des A2AR, et qu’à ce titre il pouvait être un outil thérapeutique dans lesinfections par HIV. Dans une quatrième étude, nous avons évalué les effets anti‐nociceptifs d’Adonis qui,administré par voie intra‐cérébro‐ventriculaire, augmente de manière dose‐dépendante les latencesobtenues avec le test du Hot‐plate et du Tail‐flick chez la souris. Ces effets sont renversés par deuxantagonistes des A2AR mais aussi par un antagoniste des récepteurs aux opioïdes. Ceci suggère que leseffets anti‐nociceptifs d’Adonis sont médiés par la libération d’opioïdes endogènes. En marge de sesétudes, nous avons également testé les propriétés biologiques de nouveaux ligands des A1R dans le cadred’une collaboration entre chimistes et biologistes. Ainsi, nous montrons, dans une cinquième étude, queparmi la trentaine de molécules synthétisées, quatre sont des antagonistes et deux autres des agonistesavec un EC50 de l’ordre du micromolaire pour la production d’AMPc. De tels agonistes des A1R pourraientêtre utiles dans le traitement des douleurs neuropathiques, tandis que les antagonistes le seraient dansl’insuffisance cardiaque ou utilisés comme diurétique. Enfin dans une sixième étude, nous avons testé unemolécule originale, puisque bivalente, possédant un pôle d’activité pour les récepteurs aux opioïdes μ et unautre pour les A1R. Cette molécule est un antagoniste pour les deux récepteurs. Elle pourrait avoir desapplications cliniques dans certaines pathologies comme le choc hypovolémique ou le sevrage aux opiacés. / Adenosine interacts on its cell surface receptors, namely A1R, A2AR, A2BR and A3R, to exertphysiological effects on target tissues. Modulation of these adenosine receptors appears to be a currenttopic of research which may bring more comprehensions on human pathophysiology yet to be elucidated.In order to study A2AR expression, we produced, in study 1, a monoclonal antibody anti‐human A2AR, calledAdonis being of IgM, isotype. Adonis recognized a linear epitope of seven amino acids on the C‐terminalpart of the A2AR second extra‐cellular loop. By Western blotting, Adonis reveals a 45 KDa band of A2AR incell lysates. Adonis behaves as an agonist‐like which increases the cAMP production and inhibits cellproliferation through A2AR stimulation. In study 2, we showed that using Adonis, to measure the A2ARexpression of peripheral blood mononuclear cells which mimic those of the cardiac tissue, was able todifferentiate some patients with suspected neurally mediated syncope. We showed, in study 3, that A2ARstimulation by Adonis leads to a down‐regulation of CXCR4 and CCR5 expression on T‐cells, suggesting thatAdonis would be a potential drug to treat HIV infections. In study 4, we showed that intracereboventricularinjection of Adonis increased the Hot‐plate and Tail‐flick test latencies in mice in a dose‐dependent manner.Such increases were prevented by two A2AR antagonists and by an opiate receptor antagonist, suggestingthat the anti‐nociceptive effects of Adonis were mediated, at least in part, by endogenous opioid liberation.The last section focused on biological evaluation of new A1R ligands in collaborative studies betweenchemists and biologists. Indeed we showed, in study 5, that among thirty synthesized molecules, four act asA1R antagonists and two turn out to be A1R agonists with a micromolar EC50 on cAMP production. ThoseA1R agonists would be used in neuropathic pains, whereas other antagonists could be used in cardiacfailure or as diuretic. Finally, in study 6, we tested an original hybrid molecule which was revealed to be abivalent antagonist to μ opiate receptors and A1R. This hybrid compound may have applications in somepathologies such as hypovolemic shock and opiate addiction.

Today, more Americans die each year because of drug overdoses than are killed in motor vehicle accidents. In fact, in 2015, more than 33,000 individuals died due to an overdose of heroin or prescription opioids. Sadly, 40-60 % of patients on current opioid addiction treatment medications relapse. Studies have shown that the addiction/abuse liability of opioids are abolished in mu opioid receptor (MOR) knock-out mice; this indicates that the addiction and abuse liability of opioids are mainly mediated through MOR. Utilizing the “message-address concept”, the our laboratory reported a novel non-peptide, reversible MOR selective ligand 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6α (isoquinoline-3-carboxamido)morphinan (NAQ). Molecular modeling and mutagenesis studies revealed that the selectivity of NAQ for MOR is because of the π-π stacking of the isoquinoline ring of NAQ with W318. Therefore, other heterocyclic ring systems were explored to obtain a diverse library of compounds with similar or different molecular interactions and pharmacologic characteristics as NAQ. The newly designed compounds were indole analogs of 6α/β-naltrexamine. The compounds were synthesized and the affinity and selectivity for MOR determined using the radioligand binding assay while the functional activity at MOR was determined using the [35S]GTPγS binding assay. The indole analog of 6α-naltrexamine substituted at position 7 (compound 6) was found to be very potent and had the lowest efficacy in the [35S]GTPγS functional assay while the indole analog of 6β-naltrexamine substituted at position 2 (compound 10) was identified as a MOR agonist and had the greatest efficacy. In vivo studies were conducted using the warm-water immersion assay to find whether the synthesized compounds had antinociceptive effects and/or blocked the antinociceptive effects of morphine. Not surprisingly, compound 10 was identified as an opioid agonist while compound 6 almost completely blocked morphine’s antinociceptive effects. The opioid antagonist effect of compound 6 was found to be dose dependent with an AD50 of 2.39 mg/kg (0.46-12.47). An opioid withdrawal assay was conducted on compound 6 using morphine-pelleted mice. Compound 6 produced significantly less withdrawal symptoms at 50 mg/kg than naltrexone at 1 mg/kg. Therefore, compound 6 has the potential to be used in opioid addiction and withdrawal treatment.

Millions of people in the US currently suffer from chronic pain but available therapeutics do not provide effective chronic pain treatment. Opiate therapy is still the gold standard for chronic pain management with detrimental side effects, such as tolerance, addiction, constipation, and respiratory depression that limit their therapeutic potential. Opiates exert their positive and negative effects by activating the μ opioid receptor (MOR). Conversely, the κ opioid receptor (KOR) has been shown to modulate the tolerance and addiction produced by MOR agonists and is also involved in mood modulation (anxiety and depression). Therefore, blocking KOR activation results in positive effects against opiate side effects and stress-related depression. Dynorphin A (Dyn A) is the endogenous opioid peptide for the KOR. Structure-activity relationship (SAR) studies were carried out to develop a KOR selective antagonist based on the Dyn A structure. A minimum Dyn A pharmacophore with improved stability, no cell toxicity, and antagonist activity was discovered. Peptidomimetic enkephalin analogues previously developed in our group as MOR and δ opioid receptor (DOR) agonists have shown multifunctional activity, with MOR/DOR agonist and KOR antagonist activities. To our knowledge, this finding is first of its class for the opioid receptors. Novel design and synthesis of KOR selective ligands based on our multifunctional enkephalin analogues was done. Successful peptide synthesis resulted in analogues with high stability in rat plasma and no cell toxicity.

This study was aimed at the development of novel CB1 cannabinoid receptor antago­nists that may have clinical applications for the treatment of cannabinoid and psychostimulant addiction. The rationale for the design for our target was to incorporate a bioisosteric 1,2,3-triazole ring into the vicinal diaryl group revealed in the prototypical antagonist/inverse agonist SR141716 (Rimonabant) that was pre­sumed to interact with a unique region in the CB1 receptors. Based on our prelimi­nary results we identified a novel series of 1,2,3-triazole ester and keto deriva­tives as lead compounds for biological evaluation. Here in the design rationale, syn­thesis and CB1 receptor affinity for a series of 4,5-diaryl-1-substituted-1,2,3-triazoles of ester and ketones is described. These derivatives were synthesized via a one-pot regiospecific click/acylation reaction sequence from 1-azido-2,4-dichlorobenzene and commercially available arylacetylenes. From the structure-activity studies the 5-(4-chlorophenyl) congeners exhibited the most potent CB1 receptor affinities relative to other 5-(substituted-phenyl) moieties. The 1-(2,4-dichlorophenyl)-5-(4-chlorophenyl)-4-propylcarbonyl-1,2,3-triazole (­31a) was found to be the most potent (Ki = 4.6 nM) CB1 receptor ligand of the series and exhibited high CB1 selectivity (CB2/CB1 = 417). The triazole ester 31a was further characterized as a cannabinoid antagonist in locomotor-activity studies by blocking the locomotor-reducing effects of cannabinoid agonist WIN55,212-2. In addition, unlike the prototypical cannabinoid antagonist SR141716A (Rimonabant), the triazole ester 31a did not exhibit increased activity in locomotor activ­ity studies, thus indicating the potential for a neutral antagonist profile.

Im Rahmen der vorliegenden Arbeit wurden neuartige siliciumhaltige Muscarinrezeptor-Antagonisten, Dopaminrezeptor-Antagonisten, Ca2+-Kanal-Blocker sowie alpha1-Rezeptor-Antagonisten synthetisiert, welche Sila-Analoga (C/Si-Austausch) bekannter organischer Pharmaka darstellen. Die C/Si-Analoga wurden pharmakologisch charakterisiert und damit Beiträge zur Thematik der C/Si-Bioisosterie geleistet. / In this work novel silicon-containing muscarinic antagonists, dopamine receptor antagonists, Ca2+ channel blockers, and alpha1-adrenoceptor antagonists – representing sila-analogues (C/Si replacement) of known organic drugs – were synthesized and pharmacologically characterized (studies on C/Si bioisosterism).