1,721,055 research outputs found
LOSS OF INTRINSIC STIATAL NEURONS AFTER METHYLAZOXYMETHANOL ACETATE TREATMENT IN PREGNANT RATS
No full textCloning, pharmacological characterisation and distribution of the rat G-protein-coupled P2Y(13) receptor
No full textThe human P2Y(13) receptor is a new receptor characterized by coupling to Gi, responsiveness to adenine di-phospho-nucleotides and blockade by the P2Y antagonist AR-C69931MX. The mouse P2Y(13) ortholog has also been reported. Here we report, for the first time, the cloning of rat P2Y(13) receptor, its pharmacological analysis and tissue distribution. Rat P2Y(13) is 79% and 87% identical to human and mouse P2Y(13) receptors, respectively. Expression of rP2Y(13) receptor in 1321N1 cells induced the appearance of responses to the typical P2Y(13) receptor agonists ADP and 2MeSADP, as detected by stimulation of [(35)S]GTPgammaS binding. Agonist activities were higher in cells transfected with rP2Y(13) receptor in the presence of the Galpha(16) subunit; in all cases agonist effects were abolished by pertussis toxin pre-treatment. At variance from both human and mouse receptors, ADP was more potent than 2MeSADP. Other nucleotides and sugar-nucleotides were ineffective. Both in the absence and presence of Galpha(16), activation of rP2Y(13) receptor by ADP and 2MeSADP was completely inhibited by nM concentrations of AR-C69931MX. In contrast, no inhibition of rP2Y(13) receptor was induced by the selective P2Y(1) receptor antagonist MRS2179. rP2Y(13) receptor showed highest expression levels in spleen, followed by liver and brain (with particularly high levels in cortex and striatum as reported in man), suggesting important roles in the nervous and immune systems. Expression levels comparable to those of the other cloned P2Y receptors were found in primary rat astrocytes, indicating a possible role in reactive astrogliosis. Hence, rat P2Y(13) receptor displays several similarities but also interesting differences with its human and mouse orthologs, that will have to be taken into account when characterizing the pathophysiological roles of this receptor in the rat animal models
Agonist-induced desensitisation/resensitisation of human GPR17: a functional cross talk between purinergic and cysteinyl-leukotriene ligands
No full text
Agonist-Induced Desensitization/Resensitization of Human G Protein-Coupled Receptor 17: A Functional Cross-Talk between Purinergic and Cysteinyl-Leukotriene Ligands
No full textG protein-coupled receptor (GPR) 17 is a P2Y-like receptor that responds to both uracil nucleotides (as UDP-glucose) and cysteinyl-leukotrienes (cysLTs, as LTD(4)). By bioinformatic analysis, two distinct binding sites have been hypothesized to be present on GPR17, but little is known on their putative cross-regulation and on GPR17 desensitization/resensitization upon agonist exposure. In this study, we investigated in GPR17-expressing 1321N1 cells the cross-regulation between purinergic- and cysLT-mediated responses and analyzed GPR17 regulation after prolonged agonist exposure. Because GPR17 receptors couple to G(i) proteins and adenylyl cyclase inhibition, both guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPγS) binding and the cAMP assay have been used to investigate receptor functional activity. UDP-glucose was found to enhance LTD(4) potency in mediating activation of G proteins and vice versa, possibly through an allosteric mechanism. Both UDP-glucose and LTD(4) induced a time- and concentration-dependent GPR17 loss of response (homologous desensitization) with similar kinetics. GPR17 homologous desensitization was accompanied by internalization of receptors inside cells, which occurred in a time-dependent manner with similar kinetics for both agonists. Upon agonist removal, receptor resensitization occurred with the typical kinetics of G protein-coupled receptors. Finally, activation of GPR17 by UDP-glucose (but not vice versa) induced a partial heterologous desensitization of LTD(4)-mediated responses, suggesting that nucleotides have a hierarchy in producing desensitizing signals. These findings suggest a functional cross-talk between purinergic and cysLT ligands at GPR17. Because of the recently suggested key role of GPR17 in brain oligodendrogliogenesis and myelination, this cross-talk may have profound implications in fine-tuning cell responses to demyelinating and inflammatory conditions when these ligands accumulate at lesion sites
Method of diagnosing and treating Huntington's disease
No full textThe present invention relates to the field of therapy for diseases of the central nervous system. In particular this invention concerns an “in vitro” method for early diagnosis of the onset of Huntington’s disease based on the assessment of abnormal adenylate cyclase activity and the binding to the adenosine A2A receptors and in the use of drugs that inhibit this activity for the prevention and/or treatment of this disease.
This invention is based on the identification of an anomalous behaviour of the A2A adenosine receptor and its transduction system (adenylate cyclase enzyme) in cells genetically predisposed to develop Huntington’s disease and in circulating cells of affected patients as well as by overproduction of cyclic AMP following stimulation with A2A agonist compounds. This invention exploits this increase in the A2A receptors and overproduction of cyclic AMP as diagnostic markers in an vitro method for early detection of the onset of Huntington’s disease and to monitor its progression. The invention also described the use of compounds with A2A antagonist action that being capable of blocking this abnormal behaviour prevent pathological progression of the cell and thus form a class of drugs useful to the treatment and prevention of this disease. The present invention is based on studies performed by the applicants on an experimental genetic model of the disease and on platelets obtained from patients with Huntington’s disease. The experimental genetic model which reflects the genetic abnormality found in patients affected by Huntington’s disease is composed of neuronal cells, the genome of which contains the expansion of the CAG triplet. The cells thus modified express analogously to the in vivo pathological situation the mutant hungtintin protein. Working on this experimental model the applicants observed that the presence of mutant huntingtin in the neuronal cells affected by Huntington’s disease induces abnormal behaviour of the adenylate cyclase system responsabile for cyclic AMP synthesis and this behaviour is expressed as overproduction of cyclic AMP induced by stimulation with A2A agonist compounds. On the basis of these observations the present invention is aimed at a method for the diagnosis of Huntington’s disease that utilized as diagnostic marker an abnormal increase in the cellular production of cyclic AMP.
In summary, the present invention comprises a method for the diagnosis of neurodegenerative diseases caused by genetic mutations due by increased repetitions of the CAG triplet. This method is characterised by using as a diagnostic markers either the increase in cellular production of cyclic AMP following to treatment with A2A agonists, or the increase of receptor density of A2A receptors. The present invention also comprises the use of A2A antagonist compounds for the treatment and/or prevention of genetic mutations characterised by increased repetitions of the CAG triplet
METHYLAZOXYMETHANOL MICROENCEPHALY AS A MODEL FOR STUDYING NOOTROPIC DRUGS: NEUROCHEMICAL CHARACTERIZATION AND BEHAVIORAL STUDIES WITH OXIRACETAM
No full textModulatori del recettore GPR17 e loro impieghi terapeutici. news compounds with modulatory activity on GPR17
No full textIn silico identification of new ligands for GPR17: a promising therapeutic target for neurodegenerative diseases
No full textGPR17, a previously orphan receptor responding to both uracil nucleotides and cysteinyl-leukotrienes, has been proposed as a novel promising target for human neurodegenerative diseases. Here, in order to specifically identify novel potent ligands of GPR17, we first modeled in silico the receptor by using a multiple template approach, in which extracellular loops of the receptor, quite complex to treat, were modeled making reference to the most similar parts of all the class-A GPCRs crystallized so far. A high-throughput virtual screening exploration of GPR17 binding site with more than 130,000 lead-like compounds was then applied, followed by the wet functional and pharmacological validation of the top-scoring chemical structures. This approach revealed successful for the proposed aim, and allowed us to identify five agonists or partial agonists with very diverse chemical structure. None of these compounds could have been expected 'a priori' to act on a GPCR, and all of them behaved as much more potent ligands than GPR17 endogenous activators
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