5-Hydroxytryptamine(2A/2C) receptors of nucleus raphe magnus and gigantocellularis/paragigantocellularis pars alpha reticular nuclei modulate the unconditioned fear-induced antinociception evoked by electrical stimulation of deep layers of the superior colliculus and dorsal periaqueductal grey matter

Author(s)

de Oliveira, Ricardo ; de Oliveira, Rithiele Cristina ; Falconi-Sobrinho, Luiz Luciano ; Soares, Jr., Raimundo da Silva ; Coimbra, Norberto Cysne

• Document type: Journal article
• Source: Behavioural Brain Research; v. 316, p. 294-304, JAN 1 2017.
• Web of Science Citations: 9

Abstract

The electrical stimulation of the dorsolateral columns of the periaquedutal grey matter (dlPAG) or deep layers of the superior colliculus (dlSC) evokes defensive behaviours followed by an antinociceptive response. Monoaminergic brainstem reticular nuclei are suggested to comprise the endogenous pain modulatory system. The aim of the present work was to investigate the role played by 5-HT2 subfamily of serotonergic receptors of the nucleus raphe magnus (NRM) and the gigantocellularisi/paragigantocellularis pars alpha reticular nuclei (Gi/PGi alpha) in the elaboration of instinctive fear-induced antinociception elicited by electrical stimulation of dlPAG or of dlSC. The nociceptive thresholds were measured by the tail-flick test in Wistar rats. The 5-HT2A/2C-serotonergic receptors antagonist ritanserin was microinjected at different concentrations (0.05, 0.5 and 5.0 mu g/0.2 mu L) either in Gi/PGi alpha or in NRM. The blockade of 5- HT2 receptors in both Gi/PGia and NRM decreased the innate fear-induced antinociception elicited by electrical stimulation of the dlSC or the dlPAG. These findings indicate that serotonin is involved in the hypo-algesia induced by unconditioned fear-induced behavioural responses and the 5-HT2A/2C-serotonergic receptor subfamily in neurons situated in the Gi/PGi alpha complex and NRM are critically recruited in pain modulation during the panic-like emotional behaviour. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 11/09850-1 - study of serotoninergic pathways that connect the dorsal raphe nucleus to the Lateral Septal Area on the Modulation of Defensive Behavior Organized by periaqueductal gray performed by the prefrontal cortex
• Grantee: Ricardo de Oliveira
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 12/03798-0 - Involvement of opioid and endocanabinoid receptors of the substantia nigra on the activity of Nigro-Tectal GABAergic pathways during defensive behaviour elicited by rodents confronted with venomous snakes
• Grantee: Norberto Cysne Coimbra
• Support Opportunities: Regular Research Grants
• FAPESP's process: 07/01174-1 - Study of the Involvement of opioid-, serotonergic- and noradrenergic-mechanisms of the pain endogenous inhibitory system in antinociceptive processes induced by oriented escape reactions evoked by chemical stimulation of the merdial hypothalamus
• Grantee: Norberto Cysne Coimbra
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/10984-8 - Influence of the anterior cingulate cortex and involvement of hypothalamic NMDA and AMPA/kainite glutamatergic receptorsin the organization of the defensive behaviorand innate fear-induced antinociception elaborated by posterior hypothalamus
• Grantee: Luiz Luciano Falconi Sobrinho
• Support Opportunities: Scholarships in Brazil - Master