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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

MEDIAL PREFRONTAL CORTEX SEROTONERGIC AND GABAERGIC MECHANISMS MODULATE THE EXPRESSION OF CONTEXTUAL FEAR: INTRATELENCEPHALIC PATHWAYS AND DIFFERENTIAL INVOLVEMENT OF CORTICAL SUBREGIONS

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Author(s):
Almada, R. C. [1, 2] ; Coimbra, N. C. [1, 3, 2] ; Brandao, M. L. [1, 3, 4]
Total Authors: 3
Affiliation:
[1] Inst Neurosci & Behav INeC, BR-14050220 Sao Paulo - Brazil
[2] Univ Sao Paulo FMRP USP, Ribeirao Preto Med Sch, Dept Pharmacol, Lab Neuroanat & Neuropsychobiol, Sao Paulo - Brazil
[3] Univ Sao Paulo, Ribeirao Preto Med Sch, NAP USP Neurobiol Emot Res Ctr NuPNE, Sao Paulo - Brazil
[4] Univ Sao Paulo, Dept Psychol, Sch Philosophy Sci & Literature, Lab Neuropsychopharmacol, Sao Paulo - Brazil
Total Affiliations: 4
Document type: Journal article
Source: Neuroscience; v. 284, p. 988-997, JAN 22 2015.
Web of Science Citations: 23
Abstract

Several lines of evidence indicate that the dorsal hippocampus (dH) and medial prefrontal cortex (mPFC) regulate contextual fear conditioning. The prelimbic (PrL), infralimbic (IL) and the anterior cingulate cortex (ACC) subregions of the mPFC likely play distinct roles in the expression of fear. Moreover, studies have highlighted the role of serotonin (5-hydroxytryptamine, 5-HT)- and gamma-aminobutyric acid (GABA)- mediated mechanisms in the modulation of innate fear in the mPFC. The present study characterized dH-mPFC pathways and investigated the role of serotonergic and GABAergic mechanisms of the PrL, IL and ACC-area 1 (Cg1) in the elaboration of contextual fear conditioning using fear-potentiated startle (FPS) and freezing behavior in Rattus norvegicus. The results of neurotracing with microinjections of biotinylated dextran amine into the dH revealed a neural link of the dH with the PrL and ACC. Intra-PrL injections of the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) and the GABA(A) receptor-selective agonist muscimol reduced contextual FPS and freezing responses. Intra-Cg1 injections of muscimol but not 8-OH-DPAT decreased FPS and freezing responses. However, neither intra-IL injections of a 5-HT1A agonist nor of a GABA(A) agonist affected these defensive responses. Labeled neuronal fibers from the dH reached the superficial layers of the PrL cortex and spread to the inner layers of PrL and Cg1 cortices, supporting the pharmacological findings. The present results confirmed the involvement of PrL and Cg1 in the expression of FPS and freezing responses to aversive conditions. In addition, PrL serotoninergic mechanisms play a key role in contextual fear conditioning. This study suggests that PrL, IL and Cg1 distinctively contribute to the modulation of contextual fear conditioning. (C) 2014 IBRO. Published by Elsevier Ltd. All rights reserved. (AU)

FAPESP's process: 12/22681-7 - Involvement of Opioid and Endocanabinoid Receptors of the Substantia Nigra, Pars Reticulata, in the Modulation of the Activity of Nigro-Tectal GABAergic Pathways during the Organization of Defensive Behaviour of Mice Confronted with Venomous Snakes
Grantee:Rafael Carvalho Almada
Support Opportunities: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 11/00041-3 - Neurobiology of stress: the sensorimotor gating
Grantee:Marcus Lira Brandão
Support Opportunities: Research Projects - Thematic Grants