Role of muscarinic and nicotinic cholinergic receptors in an experimental model of epilepsy-induced analgesia

Autor(es)

Freitas, Renato Leonardo de ; Oliveira, Rithiele Cristina de ; Carvalho, Andressa Daiane de ; Felippotti, Tatiana Tocchini ; Bassi, Gabriel Shimizu ; Elias-Filho, Daoud Hibrahim ^[6] ; Coimbra, Norberto Cysne

• Tipo de documento: Artigo Científico
• Fonte: Pharmacology Biochemistry and Behavior; v. 79, n. 2, p. 367-376, Oct. 2004.
• Área do conhecimento: Ciências Biológicas - Farmacologia
• Assunto(s): Epilepsia Dor Receptores colinérgicos Aminoácidos GABA

Resumo

The blockade of GABA-mediated Cl− influx with pentylenetetrazol (PTZ) was used in the present work to induce seizures in animals. The neurotransmission in the postictal period has been the focus of many studies, and there is evidence suggesting antinociceptive mechanisms following tonic-clonic seizures in both animals and men. The aim of this work was to study the involvement of acetylcholine in the antinociception induced by convulsions elicited by peripheral administration of PTZ (64 mg/kg). Analgesia was measured by the tail-flick test in eight albino Wistar rats per group. Convulsions were followed by significant increases in tail-flick latencies (TFLs) at least for 120 min of the postictal period. Peripheral administration of atropine (0.25, 1 and 4 mg/kg) caused a significant dose-dependent decrease in the TFL in seizing animals, as compared to controls. These data were corroborated by peripheral administration of mecamylamine, a nicotinic cholinergic receptor blocker, at the same doses (0.25, 1 and 4 mg/kg) used for the muscarinic cholinergic receptor antagonist. The recruitment of the muscarinic receptor was made 10 min postconvulsions and in subsequent periods of postictal analgesia, whereas the involvement of the nicotinic cholinergic receptor was implicated only after 30 min postseizures. The cholinergic antagonists caused a minimal reduction in body temperature, but did not impair baseline TFL, spontaneous exploration or motor coordination in the rotarod test at the maximal dose of 4 mg/kg. These results indicate that acetylcholine may be involved as a neurotransmitter in postictal analgesia. (AU)

• Processo FAPESP: 96/08574-9 - Estudo de processos antinociceptivos pos-ictais em modelos experimentais de epilepsia.
• Beneficiário: Norberto Cysne Coimbra
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 02/01497-1 - Estudo do envolvimento do núcleo magno da rafe, do núcleo gigantocelular e núcleo pré-tectal anterior, e de receptores opiódes, kappa e delta serotoninérgicos 5HT2/1C, e noradrenérgicos alfa, beta, na analgesia pós-cital: um estudo neuroanatômico e neuropsicofisiológico em um modelo experimental de epilepsia
• Beneficiário: Daoud Hibrahim Elias Filho
• Modalidade de apoio: Bolsas no Brasil - Programa Capacitação - Treinamento Técnico
• Processo FAPESP: 02/01496-5 - Estudo do envolvimento do núcleo magno da rafe, do núcleo gigantocelular e núcleo pré-tectal anterior, e de receptores opióides, mu, kappa e delta serotininérgicos 5-HT2A/2C e noradrenérgicos alfa e beta na analgesia pós-ictal: um estudo neuroanatômico e neuropsicofisiológico em um modelo experimental de epilepsia
• Beneficiário: Norberto Cysne Coimbra
• Modalidade de apoio: Auxílio à Pesquisa - Regular