Differences in Stress-Induced Modulation of the Auditory System Between Wistar and Lewis Rats

Abstract

Many aspects of stress-induced physiological and psychological effects have been characterized in people and animals. However, stress effects on the auditory system are less explored and their mechanisms are not well-understood, in spite of its relevance for a variety of diseases, including tinnitus. To expedite further research of stress-induced changes in the auditory system, here we compare the reactions to stress among Wistar and Lewis rats. The animals were stressed for 24 h, and subsequently we tested the functionality of the outer hair cells (OHCs) using distortion product otoacoustic emissions (DPOAEs) and auditory neurons using evoked auditory brainstem responses (ABR). Lastly, using Western blot, we analyzed the levels of plasticity-related proteins in the inferior colliculus, confirming that the inferior colliculus is involved in the adaptive changes that occur in the auditory system upon stress exposure. Surprisingly, the two strains reacted to stress quite differently: Lewis rats displayed a lowering of their auditory threshold, whereas it was increased in Wistar rats. These functional differences were seen in OHCs of the apical region (low frequencies) and in the auditory neurons (across several frequencies) from day 1 until 2 weeks after the experimental stress ended. Wistar and Lewis rats may thus provide models for auditory threshold increase and decrease, respectively, which can both be observed in different patients in response to stress.

Preventive Effects of Ginkgo-Extract EGb 761® on Noise Trauma-Induced Cochlear Synaptopathy

“…Lastly, the animals came from a different breeder (Charles River vs. Janvier) which may have led to a different genetic and/or physiological background of the animals. The therapeutic effects of Ginkgo biloba extract EGb 761 ® on hearing loss described by other groups, e.g., in female rats [ 36 ], were comparable to our earlier study and may have been based on the oxidative stress-reducing and/or anti-inflammatory qualities of the extract [ 37 , 44 ], or due to the increase in cochlear blood flow optimizing oxygen perfusion of the tissues (e.g., [ 45 ]). Nevertheless, we did not see an overall effect of the extract on the number of surviving ribbon-synapses at the IHCs of therapeutically treated animals when compared to control animals ( Figure 6 B).…”

Cerebral Cortical Activity During Academic Stress Amongst Undergraduate Medical Students at Kampala International University (Uganda)

“…In addition, the reticular system, which is responsible for behavior patterns of attention and excitement, projects serotonergic fibers to all pathways of the auditory system, ranging from the cochlea to the auditory cortex (23). Stress effects on the auditory system are less explored, their mechanisms are not well-understood, and recent findings on the functionality of the outer hair cells using distortion product otoacoustic emissions and auditory neurons using evoked auditory brainstem responses showed differences in auditory sensation between different rat strains, i.e., increase and decrease thresholds as would be observed in humans during stress (25). This evidence shows that stress affects the visual, auditory, and tactile cortical areas of the cerebral cortex; however, information on reaction time (RT) in the cerebral cortex is scarce.…”

Expression Patterns of the Neuropeptide Urocortin 3 and Its Receptor CRFR2 in the Mouse Central Auditory System

“…Temporary changes in hearing during stressful situations or episodes of anxiety or sadness are commonly experienced by humans and animals ( Neuser and Knoop, 1986 ; Schmitt et al, 2000 ; Horner, 2003 ; Kadner et al, 2006 ; Mazurek et al, 2010 ; Pacheco-Unguetti and Parmentier, 2014 ; Lin et al, 2016 ; Szczepek et al, 2018 ). Such changes can range from decreased attention to sincere auditory hallucinations ( Hoskin et al, 2014 ).…”