engleski

Botulinum toxin type A reduces migraine symptoms in rats: bilateral allodynia and dural extravasation after infraorbital nerve constriction injury

Control studies in humans indicate that botulinum toxin type A (BoNT/A) alleviates symptoms of migraine. However, this problem was never investigated in experimental animals. Infraorbital nerve constriction injury is a model used both in trigeminal neuropatic pain and in migraine. We have assessed mechanical allodynia and dural extravasation in this model after single unilateral injection of BoNT/A (3.5 U/ kg). Neuropathic behavior in rats was induced by a chronic constriction injury of the infraorbital nerve, and BoNT/A was administered into whisker pad either ipsilaterally or contralaterally to the side of nerve injury. The effects of BoNT/A on bilateral pain were assessed for a period of a month by measuring mechanical allodynia with Von Frey filaments. Animals which developed mechanical allodynia were administered with Evans blue intravenously and dural extravasation of Evans blue - plasma protein complexes was assessed. Both mechanical allodynia and dural extravasation were reduced by a single unilateral BoNT/A (3.5 U/kg) injection on the side of the toxin injection, and on the opposite side, as well. Both migraine signs: pain and dural extravasation were reduced after BoNT/A injection. For the first time we show presence of dural extravasation after infraorbital nerve constriction injury. Bilateral antinociceptive effect and even more reduction of dural extravasation suggests a central mechanism of BoNT/A actions.

botulinum toxine type A; migraine; neurogenic inflammation

DOI: 10.1111/j.1742-7843.2010.00608.x