M-3 muscarinic receptor in the ventral medial prefrontal cortex modulating the expression of contextual fear conditioning in rats

Author(s)

Fedoce, A. G. ^{[1, 2]} ; Ferreira-Junior, N. C. ^{[1, 2]} ; Reis, D. G. ^{[1, 2]} ; Correa, F. M. A. ^[1] ; Resstel, L. B. M. ^{[1, 2]}

Affiliation

^[1] Univ Sao Paulo, Ribeirao Preto Sch Med, Dept Pharmacol, BR-14049900 Ribeirao Preto, SP - Brazil

^[2] Univ Sao Paulo, Ctr Interdisciplinary Res Appl Neurosci, NAPNA, Sao Paulo - Brazil

• Document type: Journal article
• Source: Psychopharmacology; v. 233, n. 2, p. 267-280, JAN 2016.
• Web of Science Citations: 4

Abstract

Basal forebrain cholinergic neurons modulate the activation of cortical neurons by several stimuli such as fear and anxiety. However, the role of the muscarinic receptor in the medial prefrontal cortex (MPFC) in the modulation of the conditioned emotional response (CER) evoked in the model contextual conditioned fear remains unclear. The objective of this study is to test the hypothesis that inhibition of the muscarinic receptor in ventral MPFC modulates CER observed during animal's re-exposure to the aversive context. Rats implanted with cannulae aimed at the prelimbic (PL) or the infralimbic (IL) were submitted to a high-intensity contextual fear conditioning protocol. Before the test session, they received microinjections of the hemicholinium (choline reuptake blocker), atropine (muscarinic antagonist), J104129 fumarate (M-1-M-3 muscarinic antagonists), pirenzepine (M-1 muscarinic antagonist), neostigmine (inhibitor acetylcholinesterase enzyme), or the systemic administration of the FG7142 (inverse benzodiazepine agonist). Additional independent groups received the neostigmine or FG7142 before the ineffective doses of J104129 fumarate in the low-intensity protocol of contextual fear conditioning. In the high-intensity protocol, the administration of hemicholinium (1 nmol), atropine (0.06-6 nmol), J104129 fumarate (6 nmol), or pirenzepine (6 nmol) attenuated the expression of CER in rats. However, in the low-intensity protocol, only J10129 fumarate (0.06 nmol) reduced the expression of the CER. Finally, neostigmine (0.1-1 nmol) or FG7142 (8 mg/Kg) increased CER expression, an effect inhibited by the low dose of the J10129 fumarate. These results indicated that the blockade of M-3 muscarinic receptor in the vMPFC attenuates the CER expression. (AU)

• FAPESP's process: 12/17626-7 - Cellular and molecular mechanisms involved in the role of atypical neurotransmitters in neuropsychiatric disorders
• Grantee: Francisco Silveira Guimaraes
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 12/09300-4 - Bed nucleus of the stria terminalis noradrenergic system modulates contextual fear conditionig: possible interaction with CRF and glutamatergic and nitrergic neurotransmission
• Grantee: Leonardo Resstel Barbosa Moraes
• Support Opportunities: Regular Research Grants