Peripheral and central auditory dysfunction induced by intermittent hypoxia via a novel recurrent airway obstruction device in rats.

OBJECTIVE

This study aimed to investigate the effects of intermittent hypoxia (IH) on auditory thresholds, auditory brainstem response (ABR) latency, and neuronal activity in the auditory cortex using a novel recurrent airway obstruction device.

METHODS

Twenty-four male Sprague-Dawley rats (300-350 g) were randomly assigned to experimental or control groups. A custom 3D-printed mask with one-way valves and a ventilation system was used to induce IH in the experimental group via periodic airflow cessation. The control group wore the same apparatus without hypoxic exposure. Blood oxygen saturation was continuously monitored using a pulse oximeter. A three-dimensional gas dynamics model was constructed to validate the oxygen and carbon dioxide dynamics within the mask. After 3 h of exposure, ABR and the spontaneous firing rate (SFR) of auditory cortical neurons were recorded.

RESULTS

The experimental group showed periodic desaturation, with minimum and maximum oxygen saturation values of 80.19 ± 0.34 % and 97.68 ± 0.31 %, respectively. ABR thresholds at 24 and 32 kHz significantly increased to 19.17 ± 1.54 dB and 25.00 ± 1.83 dB (P<0.05). ABR wave III-V latency at 32 kHz was significantly shortened from 2.79 ± 0.17 ms to 2.27 ± 0.16 ms (P<0.05). Additionally, the SFR of auditory cortical neurons increased to 2.67 ± 0.18 Hz in the experimental group versus 1.02 ± 0.11 Hz in controls (P<0.01).

CONCLUSION

Short-term IH induces high-frequency hearing loss, reduces ABR latency, and enhances cortical neuronal excitability, implicating both peripheral and central auditory pathways.