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Braz J Otorhinolaryngol. 2017 Mar - Apr;83(2):155-161. doi: 10.1016/j.bjorl.2016.02.011. Epub 2016 Apr 25.

Specific immediate early gene expression induced by high doses of salicylate in the cochlear nucleus and inferior colliculus of the rat.

Author information

1
Universidade de São Paulo (USP), Faculdade de Medicina Ribeirão Preto (FMRP), Departamento de Oftalmologia e Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Ribeirão Preto, SP, Brazil; Universidade de São Paulo (USP), Faculdade de Medicina Ribeirão Preto (FMRP), Departamento de Fisiologia, Ribeirão Preto, SP, Brazil.
2
Universidade de São Paulo (USP), Faculdade de Medicina Ribeirão Preto (FMRP), Departamento de Oftalmologia e Otorrinolaringologia e Cirurgia de Cabeça e Pescoço, Ribeirão Preto, SP, Brazil.
3
Universidade de São Paulo (USP), Faculdade de Medicina Ribeirão Preto (FMRP), Departamento de Fisiologia, Ribeirão Preto, SP, Brazil. Electronic address: leaor@fmrp.usp.br.

Abstract

INTRODUCTION:

Salicylate at high doses induces tinnitus in humans and experimental animals. However, the mechanisms and loci of action of salicylate in inducing tinnitus are still not well known. The expression of Immediate Early Genes (IEG) is traditionally associated with long-term neuronal modifications but it is still not clear how and where IEGs are activated in animal models of tinnitus.

OBJECTIVES:

Here we investigated the expression of c-fos and Egr-1, two IEGs, in the Dorsal Cochlear Nucleus (DCN), the Inferior Colliculus (IC), and the Posterior Ventral Cochlear Nucleus (pVCN) of rats.

METHODS:

Rats were treated with doses known to induce tinnitus in rats (300mg/kg i.p. daily, for 3 days), and c-fos and Egr-1 protein expressions were analyzed using western blot and immunocytochemistry.

RESULTS:

After administration of salicylate, c-fos protein expression increased significantly in the DCN, pVCN and IC when assayed by western blot. Immunohistochemistry staining showed a more intense labeling of c-fos in the DCN, pVCN and IC and a significant increase in c-fos positive nuclei in the pVCN and IC. We did not detect increased Egr-1 expression in any of these areas.

CONCLUSION:

Our data show that a high dose of salicylate activates neurons in the DCN, pVCN and IC. The expression of these genes by high doses of salicylate strongly suggests that plastic changes in these areas are involved in the genesis of tinnitus.

KEYWORDS:

Cochlear nucleus; Colículo inferior; Inferior colliculus; Núcleo coclear; Salicilato; Salicylate; Tinnitus; Zumbido

PMID:
27174774
DOI:
10.1016/j.bjorl.2016.02.011
[Indexed for MEDLINE]
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