Effect of Sympathetic Nervous System on Susceptibility to Acoustic Trauma

Abstract

The purpose of the present study is to investigate whether the sympathetic nervous system (SNS) exerts in protective or enhancing manner when the ear is exposed to intense sound (2kHz, 10min). Fifty-three albino guinea pigs were divided into three groups, ie SNS stimulating group, SNS eliminated group and untreated controls. Each animal group was further divided into three subgroups by the sound pressure level (110, 115 and 130dB SPL) of the exposed intense sound. The superior cervical ganglion was electrically stimulated during acoustic overstimulation in SNS stimulating group, and sympathectomy was performed before acoustic overstimulation in SNS eliminated group. The measurement of the threshold shift in compound action potential after acoustic overstimulation revealed no significant difference among three groups regardless of the intensity of overstimulation. These results, however, does not exclude the possibility of SNS contribution to the susceptibility to acoustic trauma. Further studies including systemic condition of SNS are necessary to elucidate the presence or absence of this possibility.