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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.)

ENDOCANNABINOID SIGNALING MECHANISMS IN THE SUBSTANTIA NIGRA PARS RETICULATA MODULATE GABAergic NIGROTECTAL PATHWAYS IN MICE THREATENED BY URUTU-CRUZEIRO VENOMOUS PIT VIPER

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Author(s):
Almada, R. C. [1, 2] ; Roncon, C. M. [2] ; Elias-Filho, D. H. [1, 2] ; Coimbra, N. C. [1, 2, 3]
Total Authors: 4
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, BR-14049900 Sao Paulo - Brazil
[3] Univ Sao Paulo, Ribeirao Preto Med Sch, NAP USP Neurobiol Emot Res Ctr NuPNE, Sao Paulo - Brazil
Total Affiliations: 3
Document type: Journal article
Source: Neuroscience; v. 303, p. 503-514, SEP 10 2015.
Web of Science Citations: 19
Abstract

The substantia nigra pars reticulata (SNpr) is rich in gamma-aminobutyric acid (GABA)-ergic neurons and connected to the mesencephalic tectum (MT) structures, such as the superior colliculus and dorsal periaqueductal gray matter. The SNpr presents a high density of cannabinoid receptors (CBRs), suggesting a possible regulatory role that is played by endocannabinoids (eCBs) in the ventral mesencephalon. The present study investigated the involvement of SNpr eCB mechanisms in nigrotectal pathways in the expression of defensive behavior associated with instinctive fear and panic reactions in mice that are confronted with the venomous Viperidae snake Bothrops alternatus. The localization of CB1 receptors (CB1RS) and synaptophysin glycoprotein in the SNpr was also evaluated. Administration of the GABA(A) receptor antagonist bicuculline in the MT increased defensive responses to the snake that are related to panic, such as freezing and no escape reactions, sometimes toward the snake itself. Mice that were pretreated with anandamide (5 or 50 pmol) in the SNpr, followed by an injection of physiological saline or bicuculline in the MT, exhibited significant decreases in the expression of alertness, freezing, and escape responses. Immunofluorescence showed the presence of fibers that were rich in CB1RS and synaptophysin in the SNpr, indicating that these receptors appear to be located mainly in presynaptic terminals in the striatonigral pathway. These findings suggest that eCB mechanisms in the SNpr facilitate the activity of nigrotectal GABAergic pathways, modulating the activity of striatonigral links during the elaboration and organization of innate fear and panic-like responses in threatening situations. (C) 2015 IBRO. Published by Elsevier Ltd. All rights reserved. (AU)

FAPESP's process: 12/23238-0 - Evaluation of cooperative mechanisms between opioidergic and serotonergic systems in the dorsal periaqueductal grey matter in the antidepressants effects
Grantee:Camila Marroni Roncon
Support Opportunities: Scholarships in Brazil - Post-Doctoral
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-Doctoral
FAPESP's process: 12/03798-0 - Involvement of opioid and endocanabinoid receptors of the substantia nigra on the activity of Nigro-Tectal GABAergic pathways during defensive behaviour elicited by rodents confronted with venomous snakes
Grantee:Norberto Cysne Coimbra
Support Opportunities: Regular Research Grants