• J P Martins, R B M Silva, R Coutinho-Silva, C M Takiya, A M O Battastini, F B Morrone, and M M Campos.
• Faculdade de Medicina, PUCRS, Porto Alegre, RS, Brazil.
• Br. J. Pharmacol. 2012 Jan 1;165(1):183-96.

Background And PurposeATP is released in response to cellular damage, and P2X7 receptors have an essential role in the onset and maintenance of pathological changes. Haemorrhagic cystitis (HC) is a well-known adverse effect of therapy with cyclophosphamide used for the treatment of many solid tumours and autoimmune conditions. Here we have evaluated the role of P2X7 receptors in a model of HC induced by cyclophosphamide.Experimental ApproachEffects of pharmacological antagonism or genetic deletion of P2X7 receptor on cyclophosphamide-induced HC in mice was assessed by nociceptive and inflammatory measures. In addition, the presence of immunoreactive P2X7 receptors was assessed by immunohistochemistry.Key ResultsPretreatment with the selective P2X7 receptor antagonist A-438079 or genetic ablation of P2X7 receptors reduced nociceptive behaviour scores in the HC model. The same strategies decreased both oedema and haemorrhage indices, on macroscopic or histological evaluation. Treatment with A-438079 decreased the staining for c-Fos in the lumbar spinal cord and brain cortical areas. Treatment with A-438079 also prevented the increase of urinary bladder myeloperoxidase activity and macrophage migration induced by cyclophosphamide and reduced the tissue levels of IL-1β and TNF-α. Finally, P2X7 receptors were markedly up-regulated in the bladders of mice with cyclophosphamide-induced HC.Conclusions And ImplicationsP2X7 receptors were significantly involved in a model of HC induced by cyclophosphamide. Pharmacological inhibition of these receptors might represent a new therapeutic option for this pathological condition.© 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

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