The Effects of Acute Stress-Induced Sleep Disturbance on Acoustic Trauma-Induced Tinnitus in Rats

Abstract EN

Chronic tinnitus is a debilitating condition and often accompanied by anxiety, depression, and sleep disturbance.

It has been suggested that sleep disturbance, such as insomnia, may be a risk factor/predictor for tinnitus-related distress and the two conditions may share common neurobiological mechanisms.

This study investigated whether acute stress-induced sleep disturbance could increase the susceptibility to acoustic trauma-induced tinnitus in rats.

The animals were exposed to unilateral acoustic trauma 24 h before sleep disturbance being induced using the cage exchange method.

Tinnitus perception was assessed behaviourally using a conditioned lick suppression paradigm 3 weeks after the acoustic trauma.

Changes in the orexin system in the hypothalamus, which plays an important role in maintaining long-lasting arousal, were also examined using immunohistochemistry.

Cage exchange resulted in a significant reduction in the number of sleep episodes and acoustic trauma-induced tinnitus with acoustic features similar to a 32 kHz tone at 100 dB.

However, sleep disturbance did not exacerbate the perception of tinnitus in rats.

Neither tinnitus alone nor tinnitus plus sleep disturbance altered the number of orexin-expressing neurons.

The results suggest that acute sleep disturbance does not cause long-term changes in the number of orexin neurons and does not change the perception of tinnitus induced by acoustic trauma in rats.