Disappearance of click-evoked potentials on the neck of the guinea pig by pharmacological and surgical destruction of the peripheral vestibular afferent system.
In order to establish an animal model of acoustically evoked vestibulo-collic reflex, the so-called vestibular evoked myogenic potential in humans, potentials evoked by loud clicks on the neck of the guinea pig were recorded using subjects whose peripheral vestibular endorgans or vestibular afferents had been damaged. Four normal control guinea pigs, four guinea pigs that received an intramuscular injection of gentamicin for 20 days (90 mg/kg/day) and five guinea pigs whose vestibular nerves were surgically sectioned were used in this study. Under general anesthesia with an intraperitoneal injection of pentobarbital sodium (40 mg/kg), auditory brainstem responses (ABRs) were recorded. Then, potentials evoked by loud clicks on the pre-vertebral muscle at the level of the third cervical vertebral bone were recorded using silver ball electrodes. As a result, a distinctive negative peak (NP) with a latency of 6-8 ms was recorded in all animals in the control group. NP was not observed in the gentamicin-administered group while ABR was preserved. After sectioning the vestibular nerve, NP was abolished while ABR was preserved. From these results, NP could be of vestibular origin. These results are in agreement with a previous report of NP using subjects whose cochlea had been damaged pharmacologically.
Matsuzaki
Masaki
M
Department of Otolaryngology, Tokyo Postal Services Agency Hospital, 2-14-23 Fujimi, Chiyoda-ku, Tokyo, Japan. yomiyama-tky@umin.ac.jp
Murofushi
Toshihisa
T
D000161:Acoustic Stimulation; D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D005072:Evoked Potentials, Auditory / Q000187:drug effects; D005839:Gentamicins / Q000008:administration & dosage / Q000494:pharmacology; D006168:Guinea Pigs; D007273:Injections, Intramuscular; D009333:Neck / Q000502:physiology*; D014725:Vestibular Nerve / Q000502:physiology*
D005839:Gentamicins