Master's Dissertation
DOI
https://doi.org/10.11606/D.17.2014.tde-21032014-173659
Document
Author
Full name
Tayllon dos Anjos Garcia
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Ribeirão Preto, 2014
Supervisor
Committee
Coimbra, Norberto Cysne (President)
Guimarães, Francisco Silveira
Rocha, Maria Jose Alves da
Title in Portuguese
Envolvimento de vias mediadas por endocanabinoides na modulação do comportamento de defesa induzido pelo bloqueio de receptores GABAA na divisão dorso-medial do hipotálamo ventro-medial: papel do receptor CB1
Keywords in Portuguese
Comportamento de defesa
Endocanabinoides
Hipotálamo ventro-medial
Receptor GABAA
Abstract in Portuguese
Os efeitos dos canabinoides em algumas áreas encefálicas que expressam receptores endocanabinoides, como é o caso dos núcleos hipotalâmicos, não são ainda muito bem definidos. Vários estudos têm demonstrado o papel de alguns núcleos hipotalâmicos na organização das reações induzidas pelo medo inato e pelo pânico. As respostas de defesa induzidas pelo medo instintivo caracterizam-se por serem mais elaboradas e dirigidas para algum abrigo ou rota de fuga. O estado de pânico pode ser provocado experimentalmente em animais de laboratório através da diminuição da atividade do sistema GABAérgico. O objetivo deste trabalho foi estudar os padrões comportamentais de fuga elaborada induzidos pelo bloqueio de receptores GABAérgicos do tipo A, com microinjeções intra-hipotalâmicas de bicuculina (BIC), especificamente na divisão dorso-medial do hipotálamo ventro-medial (VMHDM), assim como estabelecer o envolvimento endocanabinoides e o papel do receptor canabinoide do tipo 1 (CB1) na modulação das respostas defensivas organizadas pelo hipotálamo medial. Os resultados mostraram que a administração prévia de doses intermediárias (5pmol) de anandamida (AEA) atenuaram as respostas defensivas induzidas pela microinjeção intra-VMHDM de bicuculina (40ng), efeito este prevenido pelo pré-tratamento intra-hipotalâmica com antagonista de receptores CB1. Os resultados indicam que a AEA pode modular os efeitos pró-aversivos da bicuculina no VMHDM por meio do recrutamento de receptores CB1.
Title in English
Involvement of endocannabinoid-mediated pathways in the modulation of defensive behaviour induced by the GABAA receptor blockade in dorsomedial division of ventromedial hypothalamus: role of CB1 receptor
Keywords in English
Defensive behaviour
Endocannabinoid
GABAA receptor
Ventromedial hypothalamus
Abstract in English
The effects of cannabinoids in some brain areas that express endocannabinoid receptors, such as some hypothalamic nuclei, are not yet well known. Several studies have demonstrated a role of hypothalamic nuclei in the organisation of behavioural responses induced by innate fear and panic attacks. The defensive responses induced by instinctive fear are more elaborated and oriented toward a burrow or alternative route of escape. Panic-prone states are able to be experimentally induced in laboratory animals decreasing the GABAergic system activity. The aim of this work was to study panic-like elaborated defensive behaviour evoked by GABAA receptor blockade with bicuculline (BIC) in the dorsomedial division of the ventromedial hypothalamus (VMHDM), we also aimed to establish the involvement of endocannabinoids and the role of CB1 cannabinoid receptor in the modulation of elaborated defense behavioural responses organised by medial hypothalamus. The results showed that intra-hypothalamic administration of anandamide (AEA) at the intermediate dose (5pmol) attenuated defensive responses induced by intra-VMHDM microinjection of bicuculline (40ng). This effect, however, was prevented by the pre-treatment of VMHDM with the CB1 receptor antagonist AM251. These results indicate that AEA can modulate the pro-aversive effects of bicuculline into the VMHDM, recruiting CB1 receptors.
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Publishing Date
2015-05-28