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Possible involvement of the endocannabinoid system in the bed nucleus of stria terminalis on the contextual fear conditioning responses in rats

Grant number: 17/16913-6
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): March 01, 2018
Effective date (End): February 29, 2020
Field of knowledge:Biological Sciences - Pharmacology
Principal Investigator:Leonardo Resstel Barbosa Moraes
Grantee:Anna Bárbara Borges de Assis
Home Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

The present study aims to evaluate the role of the endocannabinoid system, via cannabinoid receptors CB1 and CB2, located in the Bed Nucleus of the Stria Terminalis (BNST), which is a limbic structure responsible for of autonomic, neuroendocrine and behavioral integration during aversive situations, such as contextual fear conditioning. For this investigation, male Wistar rats will be submitted to stereotaxic surgery for bilateral guide cannula implantation directed to the BNST, for drug administration. After five days for recovery, animals will be submitted to a 3-days contextual fear conditioning protocol. On the first day, during Habituation session, animals will be exposure to the chamber for 10 min, without any shock presentation. Next, animals will be re-exposed to the same environment for additional 10 min for conditioning session, with shock presentation varying with chosen protocol (high or low intensity). On the second day, a catheter will be implanted into the femoral artery for blood pressure and heart rate recording. The test session will be held on the third day, 48h after fear conditioning. This session consists of a 10 min re-exposure to the same footshock chamber without shock delivery. Freezing behavior and autonomic responses (mean arterial pressure, heart rate and tail cutaneous temperature) evoked by the aversive context will be recorded for 10 min. Animals will be received intra-BNST drug infusion 10 min before the Test session begins. Our hypothesis is that cannabinoid CB2 receptors, in addition to CB1 receptors, expressed on BNST modulate behavioral and autonomic responses to aversive situations, and this effects depends on glutamatergic system and nitric oxide. (AU)