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Radioligand Binding Studies (radioligand + binding_studies)
Selected AbstractsNovel Enantiopure Ferrugininoids Active as Nicotinic Agents: Synthesis and Radioligand Binding Studies.CHEMINFORM, Issue 39 2004S. Seifert Abstract For Abstract see ChemInform Abstract in Full Text. [source] Expression and regulation of interleukin-10 and interleukin-10 receptor in rat astroglial and microglial cellsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2002Annemarie Ledeboer Abstract Activated glial cells crucially contribute to brain inflammatory responses. Interleukin-10 (IL-10) is an important modulator of glial cell responses in the brain. In the present study we describe the expression of IL-10 and the IL-10 receptor (IL-10R1) in primary cocultures of rat microglial and astroglial cells. Using quantitative RT-PCR and ELISA, we show that IL-10 mRNA expression and subsequent IL-10 secretion is time-dependently induced by lipopolysaccharide (LPS). IL-10R1, however, is constitutively expressed in glial cell cocultures, as shown by RT-PCR and immunocytochemistry. Radioligand binding studies using 125I-IL-10 reveal that rat glial cells express a single binding site with an apparent affinity of approximately 600 pm for human IL-10. Observations in enriched cultures of either microglial or astroglial cells indicate that both cell types express IL-10 mRNA and are capable of secreting IL-10. Both cell types also express IL-10R1 mRNA and protein. However, in glial cell cocultures immunoreactive IL-10R1 protein is predominantly observed in astrocytes, suggesting that microglial expression of IL-10R1 in cocultures is suppressed by astrocytes. In addition, exogenous IL-10 is highly potent in down-regulating LPS-induced IL-1, and IL-10 mRNA, and, at a higher dose, IL-10R1 mRNA in untreated and LPS-treated cultures, suggesting that IL-10 autoregulates its expression and inhibits that of IL-1, at the transcriptional level. Together the findings support the concept that IL-10, produced by activated microglial and astroglial cells, modulates glia-mediated inflammatory responses through high-affinity IL-10 receptors via paracrine and autocrine interactions. [source] Desensitisation of mast cell ,2 -adrenoceptor-mediated responses by salmeterol and formoterolBRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2004Anne-Marie Scola The long-acting ,2 -adrenoceptor agonist formoterol (10,10,10,6M) inhibited the IgE-dependent release of histamine from human lung mast cells in a concentration-dependent manner. Formoterol was more potent and a full agonist relative to the nonselective , -adrenoceptor agonist isoprenaline. By contrast, the long-acting ,2 -adrenoceptor agonist salmeterol (10,10,10,6M) was about two-thirds less efficacious than either formoterol or isoprenaline as an inhibitor of histamine release. Isoprenaline, formoterol and salmeterol (all at 10,5M) increased total cell cAMP levels in mast cells over basal by 361±90 (P<0.05), 321±89 (P<0.05) and 64±24% (P>0.05), respectively. Long-term (24 h) incubation of mast cells with formoterol (10,6M) or salmeterol (10,6M) essentially abolished the subsequent ability of isoprenaline to inhibit histamine release. Both formoterol and salmeterol were more effective at inducing the functional desensitisation than isoprenaline (10,6M) or the short-acting ,2 -adrenoceptor agonist salbutamol (10,6M). The desensitisation induced by long-term treatments with salmeterol and formoterol was specific for ,2 -adrenoceptor-mediated inhibition of histamine release as the inhibitory effects of alternative cAMP-elevating compounds, prostaglandin E2, a receptor-mediated activator of adenylate cyclase, and forskolin, a direct activator of adenylate cyclase, were unaffected by desensitising treatments. Radioligand binding studies were performed to determine ,2 -adrenoceptor density in cell membranes after pretreatment (24 h) of cells with agonists. Isoprenaline, formoterol and salmeterol (all at 10,6M) reduced ,2 -adrenoceptor density by 13±5 (P>0.05), 49±13 (P<0.05) and 35±17% (P>0.05), respectively. These data indicate that long-term exposure of mast cells to both salmeterol and formoterol can cause substantial levels of desensitisation to ,2 -adrenoceptor-mediated responses in mast cells. British Journal of Pharmacology (2004) 141, 163,171. doi:10.1038/sj.bjp.0705599 [source] A Drosophila melanogaster cell line (S2) facilitates post-genome functional analysis of receptors and ion channelsBIOESSAYS, Issue 11 2002Paula R. Towers The complete sequencing of the genome of the fruit fly Drosophila melanogaster offers the prospect of detailed functional analysis of the extensive gene families in this genetic model organism. Comprehensive functional analysis of family members is facilitated by access to a robust, stable and inducible expression system in a fly cell line. Here we show how the Schneider S2 cell line, derived from the Drosophila embryo, provides such an expression system, with the bonus that radioligand binding studies, second messenger assays, ion imaging, patch-clamp electrophysiology and gene silencing can readily be applied. Drosophila is also ideal for the study of new control strategies for insect pests since the receptors and ion channels that many new animal health drugs and crop protection chemicals target can be expressed in this cell line. In addition, many useful orthologues of human disease genes are emerging from the Drosophila genome and the study of their functions and interactions is another area for postgenome applications of S2 cell lines. BioEssays 24:1066,1073, 2002. © 2002 Wiley-Periodicals, Inc. [source] Cloning and pharmacological characterization of the dog P2X7 receptorBRITISH JOURNAL OF PHARMACOLOGY, Issue 6 2009S Roman Background and purpose:, Human and rodent P2X7 receptors exhibit differences in their sensitivity to antagonists. In this study we have cloned and characterized the dog P2X7 receptor to determine if its antagonist sensitivity more closely resembles the human or rodent orthologues. Experimental approach:, A cDNA encoding the dog P2X7 receptor was isolated from a dog heart cDNA library, expressed in U-2 OS cells using the BacMam viral expression system and characterized in electrophysiological, ethidium accumulation and radioligand binding studies. Native P2X7 receptors were examined by measuring ATP-stimulated interleukin-1, release in dog and human whole blood. Key results:, The dog P2X7 receptor was 595 amino acids long and exhibited high homology (>70%) to the human and rodent orthologues although it contained an additional threonine at position 284 and an amino acid deletion at position 538. ATP possessed low millimolar potency at dog P2X7 receptors. 2,-&3,-O-(4benzoylbenzoyl) ATP had slightly higher potency but was a partial agonist. Dog P2X7 receptors possessed relatively high affinity for a number of selective antagonists of the human P2X7 receptor although there were some differences in potency between the species. Compound affinities in human and dog blood exhibited a similar rank order of potency as observed in studies on the recombinant receptor although absolute potency was considerably lower. Conclusions and implications:, Dog recombinant and native P2X7 receptors display a number of pharmacological similarities to the human P2X7 receptor. Thus, dog may be a suitable species for assessing target-related toxicity of antagonists intended for evaluation in the clinic. [source] Indoloquinolizidine,Peptide Hybrids as Multiple Agonists for D1 and D2 Dopamine ReceptorsCHEMMEDCHEM, Issue 9 2009Marc Vendrell Abstract Multiple-specificity ligands are considered promising pharmacological tools that may show higher efficacy in the treatment of diseases for which the modulation of a single target is therapeutically inadequate. We prepared a set of novel ligands for D1 and D2 dopamine receptors by combining two indolo[2,3- a]quinolizidine scaffolds with various tripeptide moieties. The binding and functional properties of these molecules were determined by radioligand binding studies in brain striatum membranes and by intracellular cAMP production assays in cells expressing different dopamine receptor subtypes. Some indoloquinolizidine,peptide hybrids, mainly with the trans configuration, showed dual agonist activity at both D1 and D2 dopamine receptors and may therefore be useful for testing the therapeutic potential of multivalent drugs on these targets. [source] | |||||||||||||