Keynote Lecture

Prof. Dr. Barbara Canlon
Department of Physiology and Pharmacology, Karolinska Institute, Sweden

Do you hear the clock ticking?

We have found, in the mouse, that the same noise exposure causes greater physiological and morphological consequences during nighttime compared to daytime exposures with a loss of synaptic ribbons, an essential entity of the auditory synapse in the coding of sounds, leading to a permanent loss of auditory function. Consequently, a robust molecular circadian clock machinery including the circadian genes Per1, Per2, Bmal1, and Rev-Erba, was identified in the cochlea and was found to regulate this differential sensitivity to day or night noise exposure. Using RNAseq we recently identified 7211 genes in the cochlea that have circadian expression and a large proportion of them regulate cell signaling and hormone secretion. Near ⅔ of these genes show maximal expression at nighttime, a finding which can only be captured when performing analyses around the clock. These findings provide unprecedented knowledge of the genetic regulation of cochlear function since it is not standard practice in the auditory field to collect samples at different time points throughout the day. As a consequence, a full understanding of the molecular regulation of cochlear function during the day and the night is lacking and this presentation will be addressing this challenge.