D-Methionine attenuates inner hair cell loss in carboplatin-treated chinchillas

Carboplatin, a second-generation platinum-based antineoplastic drug, preferentially destroys inner hair cells (IHCs) in the chinchilla while sparing outer hair cells (OHCs). D-Methionine (D-Met), a sulfur-containing amino acid, has been shown to protect hair cells from cisplatin damage in rats, but its ability to protect IHCs from carboplatin damage has not yet been evaluated in the chinchilla. We tested whether D-Met would protect the hair cells in the chinchilla from carboplatin. Animals were divided into two groups: a control group that only received carboplatin (100 mg/kg, i.p.) and an experimental group that received 300 mg/kg D-Met (i.p.) 30 min before carboplatin treatment. Ototoxicity was assessed by measuring the amount of IHC and OHC loss. Average IHC loss in the group treated with D-Met was 62% compared with 84% in the untreated control group. Thus, D-Met causes a statistically significant reduction in IHC loss induced by carboplatin.