Temporomandibular disorder is a common clinical condition involving pain in the temporomandibular joint (TMJ) region. This study assessed the antinociceptive effects of a polysulfated fraction from the red seaweed Gracilaria cornea (Gc-FI) on the formalin-induced TMJ hypernociception in rats and...

Temporomandibular disorder is a common clinical condition involving pain in the temporomandibular joint (TMJ) region. This study assessed the antinociceptive effects of a polysulfated fraction from the red seaweed Gracilaria cornea (Gc-FI) on the formalin-induced TMJ hypernociception in rats and investigated the involvement of different mechanisms. Male Wistar rats were pretreated with injection (sc) of saline or Gc-Fl 1 h before intra-TMJ injection of formalin to evaluate the nociception. The results showed that pretreatment with Gc-Fl significantly reduced formalin-induced nociceptive behavior. Moreover, the antinociceptive effect of the Gc-Fl was blocked by naloxone (a non-selective opioid antagonist), suggesting the involvement of opioids selective receptors. Thus, the pretreatment with selective opioids receptors antagonists, reversed the antinociceptive effect of the Gc-FI in the TMJ. The Gc-FI antinociceptive effect depends on the nitric oxide/cyclic GMP/protein kinase G/ATP-sensitive potassium channel (NO/cGMP/PKG/(+)(ATP)) pathway because it was prevented by pretreatment with inhibitors of nitric oxide synthase, guanylate cyclase enzyme, PKG and a K-ATP(+) blocker. In addition, after inhibition with a specific heme oxygenase-1 (HO-1) inhibitor, the antinociceptive effect of the Gc-Fl was not observed. Collectively, these data suggest that the antinociceptive effect induced by Gc-Fl is mediated by mu/delta/kappa-opioid receptors and by activation NO/cGMP/PKG/K-ATP(+) channel pathway, besides of HO-1

CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ

COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES

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