ABSTRACT
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 (300 mg/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.
Resumo Introdução: Salicilato em doses elevadas induz zumbido nos seres humanos e em animais experimentais. No entanto, os mecanismos e loci de ação do salicilato na indução de zumbido ainda não são bem conhecidos. A expressão dos genes precoces imediatos (GPIs) está tradicionalmente associada a alterações neuronais em longo prazo, mas ainda não está claro como e onde os GPIs são ativados em modelos animais de zumbido. Objetivos: No presente estudo investigamos a expressão de c-fos e Egr-1, dois GPIs, no núcleo coclear dorsal (NCD), colículo inferior (CI) e núcleo coclear ventral posterior (NCVp) de ratos. Métodos: Os ratos foram tratados com doses que, conhecidamente, induzem zumbido em ratos (300 mg/kg IP/dia, por três dias) e as expressões das proteínas c-fos e Egr-1 foram analisadas por meio de Western blot e imunoistoquímica. Resultados: Após a administração de salicilato, a expressão da proteína c-fos aumentou significativamente no NCD, NCVp e CI, quando analisados por Western blot. A coloração imunoistoquímica mostrou uma marcação mais intensa de c-fos no NCD, NCVp e CI e um aumento significativo de núcleos positivos de c-fos no NCVp e CI. Não detectamos aumento da expressão de Egr-1 em qualquer dessas áreas. Conclusão: Nossos dados mostram que uma dose alta de salicilato ativa neurônios no NCD, NCVp e CI. A expressão desses genes por doses altas de salicilato sugere que as alterações plásticas nessas áreas estão envolvidas na gênese do zumbido.
Subject(s)
Animals , Male , Rats , Inferior Colliculi/drug effects , Salicylates/pharmacology , Gene Expression Regulation/drug effects , Genes, Immediate-Early/drug effects , Cochlear Nucleus/drug effects , Salicylates/administration & dosage , Blotting, Western , Genes, fos/drug effects , Rats, Wistar , Dose-Response Relationship, Drug , Early Growth Response Protein 1/drug effectsABSTRACT
PURPOSE: To investigate the effects of alpha-1 adrenergic receptor antagonists for the treatment of benign prostatic hyperplasia (BPH) regarding potential risks of complications in the setting of cataract surgery. AIM: To address recommendations, optimal control therapy, voiding symptoms and safety within the setting of cataract surgery. MATERIALS AND METHODS: A comprehensive literature review was performed using MEDLINE with MeSH terms and keywords "benign prostatic hyperplasia", "intraoperative floppy iris syndrome", "adrenergic alpha-antagonist" and "cataract surgery". In addition, reference lists from identified publications were reviewed to identify reports and studies of interest from 2001 to 2009. RESULTS: The first report of intraoperative floppy iris syndrome (IFIS) was observed during cataract surgery in patients taking systemic alpha-1 AR antagonists in 2005. It has been most commonly seen related to use of tamsulosin. Changes of medication and washout periods of up to 2 weeks have been attempted to reduce the risk of complications in the setting of cataract surgery. CONCLUSION: Patients under clinical treatment for BPH should be informed about potential risks of this drug class so that it can be discuss with their healthcare providers, in particular urologist and ophthalmologist, prior to cataract surgery.