Endogenous opioid peptide-mediated neurotransmission in central and pericentral nuclei of the inferior colliculus recruits mu(1)-opioid receptor to modulate post-ictal antinociception

Author(s)

Felippotti, Tatiana Tocchini ^{[1, 2, 3]} ; de Freitas, Renato Leonardo ^{[1, 2]} ; Coimbra, Norberto Cysne ^{[1, 2, 3]}

Affiliation

^[1] Inst Neurosci & Behav INeC, Ribeirao Preto, SP - Brazil

^[2] Univ Sao Paulo, Fac Med Ribeirao Preto, Dept Farmacol, Lab Neuroanat & Neuropsicobiol, BR-14049900 Ribeirao Preto, SP - Brazil

^[3] Univ Sao Paulo FMRP USP, Sch Med Ribeirao Preto, Dept Neurosci & Behav Sci, Div Neurol, Postgrad Program, BR-14049900 Ribeirao Preto, SP - Brazil

• Document type: Journal article
• Source: Neuropeptides; v. 46, n. 1, p. 39-47, FEB 2012.
• Web of Science Citations: 14

Abstract

Background: The aim of the present work was to investigate the involvement of the mu(1)-endogenous opioid peptide receptor-mediated system in post-ictal antinociception. Methods: Antinociceptive responses were determined by the tail-flick test after pre-treatment with the selective mu(1)-opioid receptor antagonist naloxonazine, peripherally or centrally administered at different doses. Results: Peripheral subchronic (24 h) pre-treatment with naloxonazine antagonised the antinociception elicited by tonic-clonic seizures. Acute (10 min) pre-treatment, however, did not have the same effect. In addition, microinjections of naloxonazine into the central, dorsal cortical and external cortical nuclei of the inferior colliculus antagonised tonic-clonic seizure-induced antinociception. Neither acute (10-min) peripheral pre-treatment with naloxonazine nor subchronic intramesencephalic blockade of mu(1)-opioid receptors resulted in consistent statistically significant differences in the severity of tonic-clonic seizures shown by Racine's index (1972), although the intracollicular specific antagonism of mu(1)-opioid receptor decreased the duration of seizures. Conclusion: mu(1)-Opioid receptors and the inferior colliculus have been implicated in several endogenous opioid peptide-mediated responses such as antinociception and convulsion. The present findings suggest the involvement of mu(1)-opiate receptors of central and pericentral nuclei of the inferior colliculus in the modulation of tonic-clonic seizures and in the organisation of post-ictal antinociception. (C) 2011 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 09/00668-6 - Study of the involvement of cholinergic pathways form tegmentar pedunculopontine nucleus to monoaminergic nuclei of the pain endogenous inhibitory system in the post-ictal antinociception
• Grantee: Norberto Cysne Coimbra
• Support Opportunities: Regular Research Grants
• FAPESP's process: 09/17258-5 - Study of the involvement of nitrergic system and of glutamatergic and cannabinoid-mediated neurotransmission from the medial prefrontal cortex in the analgesia induced by elaborated escape reactions evoked by GABAergic blockade in the medial hypothalamus
• Grantee: Renato Leonardo de Freitas
• Support Opportunities: Scholarships in Brazil - Post-Doctoral