title: Neuroanatomical and neuropharmacological approaches to postictal antinociception-related prosencephalic neurons: the role of muscarinic and nicotinic cholinergic receptors.
abstract: Several studies have suggested the involvement of the hippocampus in the elaboration of epilepsy. There is evidence that suggests the hippocampus plays an important role in the affective and motivational components of nociceptive perception. However, the exact nature of this involvement remains unclear. Therefore, the aim of this study was to determine the role of muscarinic and nicotinic cholinergic receptors in the dorsal hippocampus (dH) in the organization of postictal analgesia. In a neuroanatomical study, afferent connections were found from the somatosensory cortex, the medial septal area, the lateral septal area, the diagonal band of Broca, and the dentate gyrus to the dH; all these areas have been suggested to modulate convulsive activity. Outputs to the dH were also identified from the linear raphe nucleus, the median raphe nucleus (MdRN), the dorsal raphe nucleus, and the locus coeruleus. All these structures comprise the endogenous pain modulatory system and may be involved either in postictal pronociception or antinociception that is commonly reported by epileptic patients. dH-pretreatment with cobalt chloride (1.0 mmol/L CoCl2/0.2 μL) to transiently inhibit local synapses decreased postictal analgesia 10 min after the end of seizures. Pretreatment of the dH with either atropine or mecamylamine (1.0 μg/0.2 μL) attenuated the postictal antinociception 30 min after seizures, while the higher dose (5.0 μg/0.2 μL) decreased postictal analgesia immediately after the end of seizures. These findings suggest that the dH exerts a critical role in the organization of postictal analgesia and that muscarinic and nicotinic cholinergic receptor-mediated mechanisms in the dH are involved in the elaboration of antinociceptive processes induced by generalized tonic-clonic seizures.
authors.affiliation: Laboratory of Neuroanatomy and Neuropsychobiology, Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo (USP) Av. dos Bandeirantes 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil ; Institute for Neuroscience and Behaviour, Campus Universitarius of Ribeirão Preto of the University of São Paulo (USP) Av. dos Bandeirantes 3900, Ribeirão Preto, São Paulo, 14049-901, Brazil.
authors.forename: Renato Leonardo
authors.initials: RL
authors.lastname: de Freitas
authors.forename: Luana Iacovelo
authors.initials: LI
authors.lastname: Bolognesi
authors.forename: André
authors.initials: A
authors.lastname: Twardowschy
authors.forename: Fernando Morgan Aguiar
authors.initials: FM
authors.lastname: Corrêa
authors.forename: Nicola R
authors.initials: NR
authors.lastname: Sibson
authors.forename: Norberto Cysne
authors.initials: NC
authors.lastname: Coimbra
keywords: GABAergic neurotransmission; cholinergic neurotransmission; dorsal hippocampus; postictal analgesia