| Texto completo | |
| Autor(es): Mostrar menos - |
Coimbra‚ NC
;
De Oliveira‚ R.
;
Freitas‚ RL
;
Ribeiro‚ SJ
;
Borelli‚ KG
;
Pacagnella‚ RC
;
Moreira‚ JE
;
Da Silva‚ LA
;
Melo‚ LL
;
Lunardi‚ LO
;
others
Número total de Autores: 11
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Experimental Neurology; v. 197, n. 1, p. 93-112, 2006. |
| Resumo | |
Deep layers of the superior colliculus, the dorsal periaqueductal gray matter and the interior colliculus are midbrain structures involved ill the generation of defensive behavior and fear-induced anti-nociception. Local injections of the GABA(A) antagonist bicuculline into these structures have been used to produce this defense reaction. Serotonin is thought to be the main neurotransmitter to modulate such defense reaction in mammals. This study is the first attempt to employ immunohistochemical techniques to locate serotonergic cells in the same midbrain sites from where defense reaction is evoked by chemical stimulation with bicuculline. The blockade of GABAA receptors in the neural substrates of the dorsal mesencephalon was followed by vigorous defensive reactions and increased nociceptive thresholds. Light microscopy immuocytochemistry with streptavidin method was used for the localization of the putative cells of defensive behavior with antibodies to serotonin in the rat's midbrain. Neurons positive to serotonin were found in the midbrain sites where defensive reactions were evoked by microinjection of bicuculline. Serotonin was localized to somata and pro injections of the neural networks of the mesencephalic tectum. Immunohistochemical studies showed that the sites in which neuronal perikarya positive to serotonin were identified in intermediate and deep layers of the superior colliculus, and in the dorsal and ventral columns of the periaqueductal gray matter are the same which were activated during the generation of defense behaviors, such as alertness, freezing, and escape reactions, induced by bicuculline. These findings support the contention that serotonin and GABAergic neurons may act in concert in the modulation of defense reaction in the midbrain tectum. Our neuroanatomical findings indicate a direct neural pathway connecting the dorsal midbrain and monoaminergic nuclei of the descending pain inhibitory system, with profuse synaptic terminals mainly in the pontine reticular formation, gigantocellularis nucleus, and nucleus raphe magnus. The midbrain tectum-gigantocellularis complex and midbrain tectum-nucleus raphe magnus neural pathways may provide all alternative output allowing the organization of the fear-induced anti-nociception by mesencephalic networks. (c) 2005 Elsevier Inc. All rights reserved. (AU) | |
| 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 |
| Processo FAPESP: | 96/06946-6 - Estudo da neuroquímica de processos aversivos e antinoceptivos em estruturas encefálicas, utilizando microeletrodos na determinação de neurotransmissores in vitro e in vivo através de voltametria cíclica e de pulso diferencial |
| Beneficiário: | Luis Antonio da Silva |
| Modalidade de apoio: | Bolsas no Brasil - Jovens Pesquisadores |
| Processo FAPESP: | 98/11187-2 - Neurobiologia do medo e da ansiedade |
| Beneficiário: | Marcus Lira Brandão |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |
| Processo FAPESP: | 03/02186-2 - Envolvimento da neurotransmissão dopaminérgica no colículo inferior de ratos submetidos ao teste de resposta emocional condicionada em um procedimento de inibição latente |
| Beneficiário: | Liana Melo-Thomas |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |
| Processo FAPESP: | 97/11097-0 - Aquisição de equipamentos e material de consumo para imuno-localização ultraestrutural de proteínas solúveis |
| Beneficiário: | Antonio Haddad |
| Modalidade de apoio: | Auxílio à Pesquisa - Programa Infraestrutura - Equipamentos |
| Processo FAPESP: | 02/03705-0 - Neurobiologia do medo e do stress |
| Beneficiário: | Marcus Lira Brandão |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |
| Processo FAPESP: | 04/11732-3 - Investigação do efeito ansiolítico de óleos essenciais avaliado pelo modelo do labirinto em T elevado |
| Beneficiário: | Liana Melo-Thomas |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |