title: Specific immediate early gene expression induced by high doses of salicylate in the cochlear nucleus and inferior colliculus of the rat.
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: 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.
authors.forename: Paula
authors.initials: P
authors.lastname: Santos
authors.affiliation: 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.
authors.forename: Lilian Eslaine Costa Mendes
authors.initials: LE
authors.lastname: da Silva
authors.affiliation: Universidade de São Paulo (USP), Faculdade de Medicina Ribeirão Preto (FMRP), Departamento de Fisiologia, Ribeirão Preto, SP, Brazil. Electronic address: leaor@fmrp.usp.br.
authors.forename: Ricardo Maurício
authors.initials: RM
authors.lastname: Leão
mesh_terms: D000818:Animals; D015153:Blotting, Western; D017626:Cochlear Nucleus / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D051766:Early Growth Response Protein 1 / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects*; D017781:Genes, Immediate-Early / Q000187:drug effects*; D016762:Genes, fos / Q000187:drug effects; D007245:Inferior Colliculi / Q000187:drug effects*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012459:Salicylates / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D012459:Salicylates
keywords: Cochlear nucleus; Colículo inferior; Inferior colliculus; Núcleo coclear; Salicilato; Salicylate; Tinnitus; Zumbido