Medial prefrontal cortex Transient Receptor Potential Vanilloid Type 1 (TRPV1) in the expression of contextual fear conditioning in Wistar rats

Author(s)

Terzian, Ana Luisa B. ^{[1, 2]} ; dos Reis, Daniel Gustavo ^[3] ; Guimares, Francisco S. ^{[3, 4]} ; Correa, Fernando M. A. ^[3] ; Resstel, Leonardo B. M. ^{[3, 4]}

Affiliation

^[1] Max Planck Inst Psychiat, D-80804 Munich - Germany

^[2] Univ Munich, Grad Sch Syst Neurosci, Munich - Germany

^[3] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Pharmacol, BR-14049900 Sao Paulo - Brazil

^[4] Univ Sao Paulo, Ctr Interdisciplinary Res Appl Neurosci NAPNA, BR-14049900 Sao Paulo - Brazil

• Document type: Journal article
• Source: Psychopharmacology; v. 231, n. 1, p. 149-157, JAN 2014.
• Web of Science Citations: 14

Abstract

Contextual fear is evoked by re-exposing an animal to an environment that has been previously paired with an aversive or unpleasant stimulus. It can be assessed by freezing and cardiovascular changes such as increase in mean arterial pressure and heart rate. A marked increase in neuronal activity is associated with contextual fear conditioning, especially in limbic structures involved with defense reactions, such as the ventral portion of medial prefrontal cortex. Given the fact that transient receptor potential vanilloid type 1 (TRPV1) receptors could be involved in the expression of defensive behavior, the present work tested the hypothesis that TRPV1 manipulation in the ventromedial prefrontal cortex (vMPFC) modulates the expression of contextual conditioned fear. Male Wistar rats received bilateral microinjections into the vMPFC of the TRPV1 receptor antagonists capsazepine (1, 10, and 60 nmol/200 nL) or 6-iodonordihydrocapsaicin (3 nmol/200 nL), and the TRPV1 agonist capsaicin (1 nmol/200 nL) preceded by vehicle or 6-iodonordihydrocapsaicin before re-exposure to the experimental chamber for 10 min, 48 h after conditioning in two different protocols distinct by their aversiveness. Both antagonists reduced the freezing and cardiovascular responses in the high aversive protocol. Capsaicin caused an increase in fear-associated responses that could be blocked by 6-iodonordihydrocapsaicin. Our results indicate that TRPV1 receptors located in the vMPFC have a tonic involvement in the modulation of the expression of contextual fear conditioning. (AU)

• FAPESP's process: 11/07332-3 - Possible role of dorsal hippocampus on behaviour and autonomic responses during defensive responses: involvement of NMDA receptor/nitric oxide and endocanabinoid
• Grantee: Leonardo Resstel Barbosa Moraes
• Support Opportunities: Regular Research Grants