Botulinum toxin type A reduces inflammatory hypernociception induced by arthritis in the temporomadibular joint of rats.

OBJECTIVE

This study aimed to investigate the antinociceptive effects of Botulinum toxin type A (BoNT-A) on persistent inflammatory hypernociception induced by arthritis in the temporomandibular joint (TMJ) of rats.

MATERIAL AND METHODS

Wistar rats were induced to persistent inflammatory hypernociception in the left TMJ. Then, animals were treated with intra-TMJ injections of BoNT-A, using doses of 3.5, 7 and 14 U/kg. Saline was used as control group. Behavioral tests were applied to evaluated the effect of BoNT-A in the inflammatory hypernociception. After that, animals were euthanized and samples from peri-articular tissues and trigeminal ganglia were obtained for further analyses.

RESULTS

BoNT-A reduced the persistent inflammatory hypernociception induced by arthritis in the TMJ of rats. BoNT-A significantly reduced the peripheral release of the neurotransmitters Substance P and Calcitonin gene related peptide; and the pro-inflammatory cytokine IL-1β. Otherwise, BoNT-A had no effect in the peripheral release of glutamate and the cytokine TNF-α.

CONCLUSION

These results demonstrate that intra-articular injection of BoNT-A reduces the albumin-induced arthritis persistent hypernociception in TMJ of rats by peripheral inhibition of neuropeptides release.