Acoustic trauma triggers upregulation of serotonin receptor genes

Abstract

Hearing loss induces plasticity in excitatory and inhibitory neurotransmitter systems in auditory brain regions. Excitatory-inhibitory balance is also influenced by a range of neuromodulatory regulatory systems, but less is known about the effects of auditory damage on these networks. In this work, we studied the effects of acoustic trauma on neuromodulatory plasticity in the auditory midbrain of CBA/J mice. Quantitative PCR was used to measure the expression of serotonergic and GABAergic receptor genes in the inferior colliculus (IC) of mice that were unmanipulated, sham controls with no hearing loss, and experimental individuals with hearing loss induced by exposure to a 116 dB, 10 kHz pure tone for 3 hours. Acoustic trauma induced substantial hearing loss that was accompanied by selective upregulation of two serotonin receptor genes in the IC. The Htr1B receptor gene was upregulated tenfold following trauma relative to shams, while the Htr1A gene was upregulated threefold. In contrast, no plasticity in serotonin receptor gene expression was found in the hippocampus, a region also innervated by serotonergic projections. Analyses in the IC demonstrated that acoustic trauma also changed the coexpression of genes in relation to each other, leading to an overexpression of Htr1B compared to other genes.. These data suggest that acoustic trauma induces serotonergic plasticity in the auditory system, and that this plasticity may involve comodulation of functionally-linked receptor genes.

Increased risk of depression in patients with acquired sensory hearing loss

“…[ 23 ] Acoustic trauma in an animal model induced substantial hearing loss and caused selective upregulation of serotonin receptor genes in the inferior colliculus. [ 24 ] These 3 studies have demonstrated that hearing loss may induce plasticity in the excitatory and inhibitory neurotransmitter systems in the central auditory brain regions. However, information on networks and etiologic mechanisms between auditory damage and depression via the serotonin pathway is scant.…”

Auditory midbrain coding of statistical learning that results from discontinuous sensory stimulation

“…Gene expression relative to the housekeeping gene (Rpl13a) was calculated with the method used by [ 93 ], in which corrections for different efficiencies between target gene and housekeeping gene are made: in which RE is the relative expression, Ekhg is the efficiency of the housekeeping gene, CThkg is the Ct value of the housekeeping gene, Etg is the efficiency of the target gene, and CTtg is the Ct value of the target gene.…”

Putting it in Context: Linking Auditory Processing with Social Behavior Circuits in the Vertebrate Brain

“…Moreover, activating serotonergic pathways in the IC strongly influences responses of IC neurons to playbacks of squeaks. Activating the 5-HT1A receptor, a type which is strongly expressed within the IC (Thompson et al 1994;Peruzzi and Dut 2004;Smith et al 2014), greatly decreases the responses of IC neurons to squeaks (Hurley and Nigam 2014). 5-HT1A activation also consolidates squeak-evoked action potentials in time, so that information on the temporally varying acoustic structure of squeaks is also reduced.…”