engleski

INTRAGANGLIONIC INJECTION OF BOTULINUM TOXIN TYPE A REDUCES OROFACIAL PAIN IN RATS

Aim. In the present study we investigated possible antinociceptive effect of botulinum toxin type A (BTX-A), injected into the trigeminal ganglion in orofacial pain in rats. Methods. Male Wistar rats were injected in right trigeminal ganglion with BTX-A 0.5 and 1 U/kg. Control rats were injected with saline. After 2-3 days, experimental orofacial pain was induced by one of the two inflammatory substances (1) formalin (2.5%) or (2) capsaicin (0.01%) which were injected into the right upper lip of rats. In both tests, the number of seconds that the animals spent rubbing/grooming the injected area was recorded. Statistical analysis was performed with Mann-Whitney U test. Results. BTX-A 1 U/kg, injected into the trigeminal ganglion 3 days before the induction of pain, significantly decreased the time that the rats spent rubbing the area injected with 0.01% capsaicin (rubbing time during 30 min for control: 219, 3&#61617; 24, 2 s vs. 132, 4&#61617; 17, 2 s for BTX-A-treatd animals, p<0.01). Intraganglionic injection of BTX-A in a dose 0.5 U/kg significantly reduced pain induced with formalin injection, too. The rubbing time was significantly decreased only in the second phase of the test (12-45 min following formalin injection). Rubbing time was 591, 9&#61617; 26, 1 s for control group vs. 444, 3&#61617; 31, 3 s for BTX-A-treated group (p<0.01). Conclusion. The present study demonstrates, for the first time, that low doses of BTX-A, applied in vivo into the trigeminal ganglion, reduce orofacial pain in rats.

botulinum toxin; orofacial pain; trigeminal ganglia

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