Antagonistas serotoninérgico e noradrenérgico por via subaracnoidea aumentam a resposta álgica em ratos

Oscar César Pires; Hazem Adel Ashmawi; Elton Constantino; Naira Correa Cusma Pelogia; Irimar de Paula Posso

doi:10.1590/S0034-70942011000200009

Scientific Article

Antagonistas serotoninérgico e noradrenérgico por via subaracnoidea aumentam a resposta álgica em ratos

Subarachnoid serotonergic and noradrenergic antagonists increase the pain response in rats

Oscar César Pires; Hazem Adel Ashmawi; Elton Constantino; Naira Correa Cusma Pelogia; Irimar de Paula Posso

http://dx.doi.org/10.1590/S0034-70942011000200009 Braz J Anesthesiol, vol.61, n2, p.206-210, 2011

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Resumo

JUSTIFICATIVA E OBJETIVOS: Há evidências de que a passagem de informações nociceptivas pelo corno posterior da medula espinhal (CPME) seguindo para níveis rostrais do sistema nervoso central sofre profundas influências excitatórias e inibitórias. A presente pesquisa teve como objetivo comparar os efeitos da metissergida, da fentolamina e da fentolamina associada à metissergida, administrados por via subaracnoidea, sobre as fases I, intermediária e II do teste da formalina modificado em ratos. MÉTODO: Foram utilizados 28 ratos Wistar machos, distribuídos aleatoriamente em quatro grupos (n = 7) para receber solução salina (GC), fentolamina (GF), metissergida (GM) ou fentolamina associada à metissergida (GFM) por via subaracnoidea. A dor foi induzida pela administração de formalina na região dorsal da pata posterior direita. O teste foi dividido em três fases; fase I, intermediária e fase II. A análise estatística dos resultados foi realizada utilizando o programa SPSS (Statistical Package for Social Sciences), adotando o nível de significância de 5%. RESULTADOS: Na fase intermediária, o número de elevações da pata foi significativamente maior nos grupos GF, GM e GFM quando comparados com o grupo GC. CONCLUSÕES: Os resultados sugerem a existência de efeito noradrenérgico e serotoninérgico no sistema inibitório descendente da dor aguda, com a possibilidade de emprego de agonistas serotoninérgicos e α1-adrenérgicos para controle da dor aguda.

Palavras-chave

ANATOMIA, Espaço subaracnoideo, ANIMAL, Rato, DOR, DOR, DROGAS, Vasodilatadores, DROGAS, Vasodilatadores

Abstract

BACKGROUND AND OBJECTIVES: There is evidence that the passage of nociceptive information through the posterior horn of the spinal cord (PHSC) on its way to rostral levels of the central nervous system undergoes profound excitatory and inhibitory influences. The objective of the present study was to compare the effects of the subarachnoid administration of methysergide, phentolamine, and phentolamine associated with methysergide on phases I, intermediate, and II of the modified phormaline test in rats. METHODS: Twenty-eight male Wistar rats distributed randomly in four groups (n = 7) to received subarachnoid saline solution (GC), phentolamine (GF), methysergide (GM), or phentolamine associated with methysergide (GFM). Pain was induced by the administration of phormaline in the dorsal region of the right hind paw. The test was divided in three phases: phase I, intermediate, and phase II. Statistical analysis of the results was performed using the software SPSS (Statistical Package for Social Sciences), adopting a level of significance of 5%. RESULTS: In the intermediate phase the number of paw elevations was significantly higher in GF, GM, and GFM groups when compared to the GC group. CONCLUSIONS: The results suggest the existence of a noradrenergic and serotonergic effect in the inhibitory descending system of acute pain, with the possibility of using serotonergic and α1-adrenergic antagonists to control acute pain.

Keywords

Pain measurement, Subarachnoid Space, Phentolamine, Methysergide, Rats

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Antagonistas serotoninérgico e noradrenérgico por via subaracnoidea aumentam a resposta álgica em ratos

Subarachnoid serotonergic and noradrenergic antagonists increase the pain response in rats

Oscar César Pires; Hazem Adel Ashmawi; Elton Constantino; Naira Correa Cusma Pelogia; Irimar de Paula Posso

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