Dopaminergic mechanisms underlying catalepsy, fear and anxiety: Do they interact?

Author(s)

Colombo, Ana Caroline ^{[1, 2]} ; de Oliveira, Amanda Ribeiro ^{[1, 2]} ; Reimer, Adriano Edgar ^{[1, 2]} ; Brandao, Marcus Lira ^{[1, 2]}

Affiliation

^[1] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Lab Psicobiol, BR-14090901 Ribeirao Preto, SP - Brazil

^[2] Inst Neurociencias & Comportamento INeC, Ribeirao Preto, SP - Brazil

• Document type: Journal article
• Source: Behavioural Brain Research; v. 257, p. 201-207, NOV 15 2013.
• Web of Science Citations: 8

Abstract

Haloperidol is a dopamine D2 receptor antagonist that induces catalepsy when systemically administered to rodents. The haloperidol-induced catalepsy is a state of akinesia and rigidity very similar to that seen in Parkinson's disease. There exists great interest in knowing whether or not some degree of emotionality underlies catalepsy. If so, what kind of emotional distress would permeate such motor disturbance? This study is an attempt to shed some light on this issue through an analysis of ultrasound vocalizations (USVs) of 22 kHz, open-field test, and contextual conditioned fear in rats with some degree of catalepsy induced by haloperidol. Systemic administration of haloperidol caused catalepsy and decreased exploratory activity in the open-field. There was no difference in the emission of USVs between groups during the catalepsy or the exploratory behavior in the open-field test. In the contextual conditioned fear, when administered before training session, haloperidol did not change the emission of USVs or the freezing response. When administered before testing session, haloperidol enhanced the freezing response and decreased the emission of USVs on the test day. These findings suggest that the involvement of dopaminergic mechanisms in threatening situations depends on the nature of the aversive stimulus. Activation of D2 receptors occurs in the setting up of adaptive responses to conditioned fear stimuli so that these mechanisms seem to be important for the emission of 22 kHz USVs during the testing phase of the contextual conditioned fear, but not during the training session or the open-field test (unconditioned fear stimuli). Catalepsy, on the other hand, is the result of the blockage of D2 receptors in neural circuits associated to motor behavior that appears to be dissociated from those directly linked to dopamine-mediated neural mechanisms associated to fear. (C) 2013 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 12/06546-2 - Role of the dopaminergic receptors D1 and D2 in the inferior colliculus in the expression of inconditioned and conditioned fear responses
• Grantee: Ana Caroline Colombo
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 11/00041-3 - Neurobiology of stress: the sensorimotor gating
• Grantee: Marcus Lira Brandão
• Support Opportunities: Research Projects - Thematic Grants