N-Acetylcysteine and N-Nitroarginine Methyl Ester Attenuate Carboplatin-Induced Ototoxicity in Dissociated Spiral Ganglion Neuron Cultures

Abstract

ObjectivesCarboplatin, a platinum-containing anti-cancer drug used to treat a variety of cancers, induces ototoxicity. Since, reactive oxygen species (ROS) and nitric oxide (NO) seem to be responsible for this toxicity, the antioxidant, N-acetyl-L-cysteine (L-NAC), and NO synthetase inhibitor, N-nitro-L-arginine methyl ester (L-NAME) were predicted to have protective effects against carboplatin ototoxicity. The aim of this study was to test for the protective effects of L-NAC and L-NAME on cochlear hair cells and spiral ganglion neurons (SGNs).MethodsCochlear organotypic cultures and dissociated spiral ganglion neuron cultures, from mice postnatal day 5 cultures were used in this study. The cultures were treated with carboplatin alone or in combination with L-NAC or L-NAME, and carboplatin-induced damage was monitored.ResultsTreatment with carboplatin induced a significant loss of outer hair cells, while inner hair cells were preserved in the cochlear organotypic cultures. Addition of L-NAC or L-NAME reduced the amount of carboplatin-induced hair cell damage; the differences did not reach statistical significance. However, carboplatin significantly decreased the number of surviving SGNs in dissociated cultures. The toxic effects were significantly reduced by addition of L-NAC or L-NAME. In addition, carboplatin induced the loss of neurites from the SGN somata, and this was not blocked with L-NAC or L-NAME.ConclusionThe results of this study suggest that ROS and NO are involved in carboplatin-induced damage to hair cells and SGNs, and administration of L-NAC/L-NAME can be used to attenuate the toxicity.

Ototoxic effects of carboplatin in organotypic cultures in chinchillas and rats

“…In addition, outer hair cells were clearly damaged more than inner hair cells (Fig. 3), consistent with previous in vivo and in vitro studies in rats [31, 34, 76–78] .…”

“…The in vitro ototoxic effects of carboplatin have been studied in very few species using as cell lines and cochlear cultures [30, 76–78] . According to the very limited discoveries from previous studies in the rat cochlear culture system, carboplatin absolutely selectively destroys outer hair cells and spiral ganglion neurons in the postnatal day 3 rat cochlear explant [76–78] .…”

“…According to the very limited discoveries from previous studies in the rat cochlear culture system, carboplatin absolutely selectively destroys outer hair cells and spiral ganglion neurons in the postnatal day 3 rat cochlear explant [76–78] . In contrast, carboplatin selectively destroys inner hair cells and type I spiral ganglion neurons in chinchilla cochlear explants as it does in vivo, from our preliminary findings reported in an abstract at the Association for Research in Otolaryngology annual meeting [77] .…”

Endoplasmic Reticulum Stress Is Involved in the Response of Human Laryngeal Carcinoma Cells to Carboplatin but Is Absent in Carboplatin-Resistant Cells

“…In addition, it is reported that CBP-induced cardiotoxicity is related to ROS production in mice and could be prevented by using pravastatin, which protected against oxidative stress [32]. Production of ROS is involved in CBP-induced damage to murine cochlear hair cells and spiral ganglion neurons, and can be attenuated by the antioxidant NAC [49].…”

Design and synthesis of coumarin-based organoselenium as a new hit for myeloprotection and synergistic therapeutic efficacy in adjuvant therapy

“…We assumed that myelotoxicity of CBDCA may be caused by the free radicals mediated assault to DNA in murine bone marrow cells because (i) CBDCA induced free radicals are reported to be responsible for neurotoxicity, ototoxicity 29 and nephrotoxicity 3 , (ii) heavy metals are known to generate free radicals which can interact with DNA and produce lesions 30 and (iii) CBDCA can intercalate within DNA that resulted in the formation of the free radicals generated by platinum can damage DNA in spite of their short lifespan. We examined this hypothesis by measuring cellular oxidative and nitrosative stress.…”