Bilateral superior cervical sympathectomy and noise-induced, permanent threshold shift in guinea pigs.
The rich sympathetic innervation to the cochlea suggests its potential control of cochlear blood flow and activity during noise exposure, as part of the general and local stress sympathetic reaction evoked by noise. In a previous study, superior cervical sympathectomy prior to sound exposure in guinea pigs in an awake state, resulted in reduced temporary threshold shift. The present study was conducted to explore whether this potential protection would also be manifested in conditions producing permanent threshold shift (PTS). Thirty-six guinea pigs, divided into four groups of nine guinea pigs each, were sound exposed for 2 h in an awake state. Eighteen guinea pigs underwent superior cervical sympathectomy prior to sound exposure. Auditory brainstem thresholds were recorded prior to sound exposure, and then at 24 h, 1 and 6 weeks post-exposure. Results indicated a reduced PTS at 122 dB sound pressure level (SPL) exposure, suggesting a protective effect of the sympathectomy. However, at 125 dB SPL exposure, the protective effect was reduced.
Hildesheimer
Minka
M
Speech and Hearing Center, The Chaim Sheba Medical Center, Tel Hashomer, Israel. hildeshe@post.tau.ac.il
Henkin
Yael
Y
Pye
Ade
A
Heled
Shirly
S
Sahartov
Emma
E
Shabtai
Esther L
EL
Muchnik
Chava
C
D000818:Animals; D001309:Auditory Threshold / Q000502:physiology*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005260:Female; D006168:Guinea Pigs; D009622:Noise; D017783:Superior Cervical Ganglion / Q000502:physiology*; D013562:Sympathectomy