Avaliação do envolvimento da enzima monoamina oxidase B em modelos de dor pós-operatória e neuropática em camundongos

Abstract

Monoamines appear to play an important modulatory role on pain descending pathways and are involved in the antinociceptive mechanism of several drugs commonly used for the management of pain. In this study, we assessed the involvement of monoamine oxidase B (MAO-B), a key enzyme implicated in monoamine metabolism, on models of postsurgical and neuropathic pain in mice. For this purpose, we evaluated the effects of the selective and irreversible MAO-B inhibitor selegiline on mechanical sensitivity and ex vivo MAO-B activity in different central nervous system regions in mice submitted to incisional and partial sciatic nerve ligation (PSNL) pain models. Mice subjected to plantar incision showed a significant decrease in mechanical threshold when compared with sham-operated mice, characterizing the development of mechanical allodynia. Selegiline, at a dose sufficient to inhibit selectively the MAO-B activity (10 mg/kg), showed an anti-allodynic effect from 0.5 until 6 h after incision. The MAO-B activity was not altered in incision submitted mice when compared with sham-operated animals in any analyzed structure. Likewise, PSNL submitted mice also developed mechanical allodynia, which was reversed by selegiline (10 mg/kg) from 2 until 6 h after treatment. In addition, a significant increase on striatal MAO-B activity was observed in mice subjected to PSNL when compared with sham-operated animals, which was reversed by selegiline treatment. Taken together, our results showed that selegiline presented an antinociceptive effect on mice models of both acute and chronic pain, suggesting a potential involvement of MAO-B on pain mechanisms.