Role of cyclooxygenase-2 in lipopolysaccharide-induced hyperalgesia in formalin test.
Indian J Exp Biol
;
2005 Jan; 43(1): 53-60
Artigo
em Inglês
| IMSEAR
| ID: sea-62474
ABSTRACT
Lipopolysaccharide (LPS)-induced hyperalgesia and the role of cyclooxygenase (COX) isoforms in acute and chronic nociceptive assays have been well established. However, the role of COX isoforms in LPS-induced hyperalgesia in the formalin test is not clear. Thus, the present study was undertaken to characterize the time course of formalin-induced nociceptive response in LPS-pretreated mice and to investigate possible effects of COX inhibitors to address the potential role of COX isoforms in LPS-induced hyperalgesia in the formalin test. All the animals showed typical biphasic response to formalin challenge. At 0 hr (immediately) and 4 hr after LPS pretreatment, animals did not show any alteration in formalin-induced tonic pain. However, 12 and 16 hr after LPS pretreatment, there was a significant increase in the late phase of formalin-induced nocifensive response as compared to control mice. Treatment with intravenously administered ketorolac (a nonselective COX inhibitor) significantly and dose-dependently inhibited the late phase of formalin-induced nociceptive behaviour in saline and LPS-pretreated mice. In contrast, parecoxib (prodrug of valdecoxib, a selective COX-2 inhibitor) or dexamethasone (COX-2 transcription inhibitor), when administered intravenously or intraperitoneally, respectively, did not show antinociceptive effect in the formalin test in saline-pretreated mice. However, both the agents significantly and dose-dependently decreased the late phase nociceptive behaviour of the formalin test in LPS-pretreated mice to the level of the animals that received saline pretreatment. These results suggest that induction of COX-2 by proinflammatory mediators and subsequent release of prostaglandins could be responsible for LPS enhancement of formalin-induced nocifensive behaviour and supports an important role of COX-2 in LPS-induced hyperalgesia in the formalin test.
Texto completo:
DisponíveL
Índice:
IMSEAR (Sudeste Asiático)
Assunto principal:
Salmonella typhimurium
/
Medição da Dor
/
Feminino
/
Masculino
/
Dexametasona
/
Lipopolissacarídeos
/
Inibidores de Ciclo-Oxigenase
/
Prostaglandina-Endoperóxido Sintases
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Cetorolaco
/
Modelos Animais de Doenças
Idioma:
Inglês
Revista:
Indian J Exp Biol
Ano de publicação:
2005
Tipo de documento:
Artigo
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