Efficacy of L-N-Acetyl Cysteine in the Prevention of Gentamicin Vestibulotoxicity in Rats

Abstract

Objectives:

Determine the effect of L-N-acetylcysteine (LNAC) on gentamicin (GM) initiated vestibulotoxicity.

Methods:

Wistar rats were divided into 4 groups: Group A (n = 7) had intratympanic (IT) GM (20 mg in 40 µL); group B (n = 6) had IT GM and intraperitoneal (IP) LNAC (350 mg/kg) at 24 hours and 1 hour before GM administration; group C (n = 6) had IT GM and IT LNAC (5 mg in 40 µL); and group D (n = 6) had only IT saline (40 µL). Rats were tested by ABR and cervical vestibular evoked myogenic potentials (VEMP) pretreatment, and at 1 week and 1 month posttreatment. Morphological analysis of the inner ears was performed at 1 month. Main outcome measures were the mean change in VEMP P1 latency at sound stimulation from 80 to 110 dB SPL, and hair cell count in the saccule.

Results:

Rats treated with IT LNAC exhibited the least change in mean VEMP latencies, although the intergroup differences were not statistically significant except for 80 dB stimulation at 1 week posttreatment. IP and IT LNAC resulted in preservation of the VEMP response in all rats, whereas 42% of rats not receiving LNAC had absent responses. Morphological analysis of the saccule revealed lower mean hair cell counts in rats not receiving LNAC.

Conclusions:

Systemic and IT administration of LNAC of rats treated with GM resulted in minimal variations in VEMP latencies and greater preservation of vestibular hair cells. The protective effect of LNAC in GM-initiated vestibulotoxicity is promising and warrants further research.