Heat shock response in noise-induced hearing loss: effects of alanyl-glutamine dipeptide supplementation on heat shock proteins status()

INTRODUCTION: The 72 kDa heat shock protein, HSP72, located intracellularly provides cochlear cytoprotective and anti-inflammatory roles in the inner ear during stressful noise challenges. The expression of intracellular HSP72 (iHSP72) can be potentiated by alanyl-glutamine dipeptide supplementation...

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Detalles Bibliográficos
Autores principales: Soares, Marcos, Santos, Analu B. dos, Weich, Tainara M., Mânica, Gabriela Gomes, Homem de Bittencourt, Paulo Ivo, Ludwig, Mirna Stela, Heck, Thiago Gomes
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier 2019
Materias:
Original Article
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9422582/
https://www.ncbi.nlm.nih.gov/pubmed/31255578
http://dx.doi.org/10.1016/j.bjorl.2019.04.012
Descripción
Sumario:INTRODUCTION: The 72 kDa heat shock protein, HSP72, located intracellularly provides cochlear cytoprotective and anti-inflammatory roles in the inner ear during stressful noise challenges. The expression of intracellular HSP72 (iHSP72) can be potentiated by alanyl-glutamine dipeptide supplementation. Conversely, these proteins act as pro-inflammatory signals in the extracellular milieu (eHSP72). OBJECTIVE: We explore whether noise-induced hearing loss promotes both intracellular and extracellular HSP72 heat shock response alterations, and if alanyl-glutamine dipeptide supplementation could modify heat shock response and prevent hearing loss. METHODS: Female 90 day-old Wistar rats (n = 32) were randomly divided into four groups: control, noise-induced hearing loss, treated with alanyl-glutamine dipeptide and noise-induced hearing loss plus alanyl-glutamine dipeptide. Auditory brainstem responses were evaluated before noise exposure (124 dB SPL for 2 h) and 14 days after. Cochlea, nuclear cochlear complex and plasma samples were collected for the measurement of intracellular HSP72 and extracellular HSP72 by a high-sensitivity ELISA kit. RESULTS: We found an increase in both iHSP72 and eHSP72 levels in the noise-induced hearing loss group, which was alleviated by alanyl-glutamine dipeptide treatment. Furthermore, H-index of HSP72 (plasma/cochlea eHSP72/iHSP72 ratio) was increased in the noise-induced hearing loss group, but prevented by alanyl-glutamine dipeptide treatment, although alanyl-glutamine dipeptide had no effect on auditory threshold. CONCLUSIONS: Our data indicates that cochlear damage induced by noise exposure is accompanied by local and systemic heat shock response markers. Also, alanyl-glutamine reduced stress markers even though it had no effect on noise-induced hearing loss. Finally, plasma levels of 72 kDa heat shock proteins can be used as a biomarker of auditory stress after noise exposure.

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