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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.)

Effects of microinjections of apomorphine and haloperidol into the inferior colliculus on the latent inhibition of the conditioned emotional response

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Author(s):
Melo, Liana L. [1] ; Pereira, Ellen C. H. M. [1] ; Pagini, Cassia H. [1] ; Coimbra, Norberto C. [2] ; Brandao, Marcus L. [3] ; Ferrari, Elenice A. M. [4]
Total Authors: 6
Affiliation:
[1] Univ Sao Francisco, Lab Neuropsicofarmacol, BR-12916900 Braganca Paulista, SP - Brazil
[2] Univ Sao Paulo, Fac Med Ribeirao Preto, Dept Farmacol, Lab Neuroanat & Neuropsicobiol, BR-14049900 Ribeirao Preto, SP - Brazil
[3] Univ Sao Paulo, FFCLRP, Lab Psicobiol, BR-14049901 Ribeirao Preto, SP - Brazil
[4] Univ Estadual Campinas, Lab Sistemas Neurais & Comportamento IB, BR-13083970 Campinas, SP - Brazil
Total Affiliations: 4
Document type: Journal article
Source: Experimental Neurology; v. 216, n. 1, p. 16-21, MAR 2009.
Web of Science Citations: 6
Abstract

Electrical or chemical stimulation of the inferior colliculus (IC) induces fear-like behaviors. More recently, consistent evidence has shown that electrical stimulation of the central nucleus of the IC supports Pavlovian conditioning and latent inhibition (Li). LI is characterized by retardation in conditioning and also by an impaired ability to ignore irrelevant stimuli, after a non-reinforced pre-exposure to the conditioned stimulus. LI has been proposed as a behavioral model of cognitive abnormalities seen in schizophrenia. The aim of the present study was to determine whether dopaminergic mechanisms in the IC are involved in LI of the conditioned emotional response (CER). To induce LI, a group of rats was pre-exposed (PE) to six tones in two sessions, while rats that were not pre-exposed (NPE) had two sessions without tone presentations. The conditioning consisted of two tone presentations to the animal, followed immediately by a foot shock. PE and NPE rats received IC microinjections of physiological saline, the dopaminergic agonist apomorphine (9.0 mu g/0.5 mu L/side), or the dopaminergic antagonist haloperidol (0.5 mu g/0.5 mu L/side) before both pre-exposure and conditioning. During the test, the PE rats that received saline or haloperidol had a lower suppression of the licking response compared to NPE rats that received vehicle or haloperidol, indicating that latent inhibition was induced. There was no significant difference in the suppression ratio in rats that received apomorphine injections into the IC, indicating reduced latent inhibition. These results suggest that dopamine-mediated mechanisms of the IC are involved in the development of LI. (C) 2008 Elsevier Inc. All rights reserved. (AU)