Rat exposure in mice with neuropathic pain induces fear and antinociception that is not reversed by 5-HT2C receptor activation in the dorsal periaqueductal gray

• Autor(a) principal: Furuya-da-Cunha, Elke Mayumi [UNESP]
• Data de Publicação: 2016
• Outros Autores: Souza, Rimenez Rodrigues de, Canto-de-Souza, Azair [UNESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1016/j.bbr.2016.04.007; http://hdl.handle.net/11449/168575
• topic: 5-HT2C; Antinociception; Anxiety; Chronic constriction injury; Periaqueductal gray; Rat exposure test

Previous studies have demonstrated that serotonin 5-HT2C receptors in the dorsal periaqueductal gray (dPAG) mediate both anxiety and antinociception in mice submitted to the elevated plus maze. The present study examined the effects of intra-dPAG infusion of the serotonin 5-HT2C receptor agonist (MK-212) in the defensive reactions and antinociception in mice with neurophatic pain confronted by a predator. Neuropathic pain was induced by chronic constriction injury (CCI) of the sciatic nerve, and predator confrontation was performed using the rat exposure test (RET). Our results demonstrated that both sham-operated and CCI mice exhibited intense defensive reactions when confronted by rats. However, rat-exposed CCI mice showed reduced pain reactivity in comparison to CCI mice exposed to a toy rat. Intra-dPAG infusion of MK-212 prior to predator exposure did not significantly alter defensive or antinociceptive responses. To our knowledge, our results represent the first evidence of RET-induced antinociception in mice. Moreover, the results of the present study suggest that 5-HT2C receptor activation in the dPAG is not critically involved in the control of predator-evoked fearful or antinociceptive responses.