The protective effect of cortexin on the cisplatin ototoxicity

The aim of this study is to evaluate whether Cortexin has a protective effect against the ototoxicity, one of the major side effects of the cisplatin which is used as a potent antineoplastic. The study was performed on 30 healthy adult Wistar Albino rats whose weights are ranging from 200 to 240 g. The subjects were divided randomly into three equal groups of ten each. Group I (Control Group) was applied 1 ml/day dose of intraperitoneally (i.p.) saline solution while Group II (Cisplatin Group) was a total of 20 mg/kg of i.p. Cisplatin in 10 mg/kg doses for two days and Group III (Cisplatin + Cortexin Group) was applied i.p. Cisplatin a total of 20 mg/kg of i.p. Cisplatin in 10 mg/kg doses for two days in addition to 2 mg/day of i.p Cortexin for seven days. Before study, all subjects underwent ABR and DPOAE testing. In the 4th day of the study, the ABR and DPOAE tests were repeated on all of the subjects and then, half of the subjects in each group were decapitated and their cochleas were removed for histopathological evaluation. In the 8th day of the study, the ABR and DPOAE tests were repeated on the remaining subjects and subsequently, these subjects were also decapitated and their cochleas were histopathologically evaluated. In conclusion of the ABR test performed, the average hearing threshold of all groupswere found to be similar on the 0th day. In the ABR test performed on the 4th and 8th day of the study, a statistically significant increase was observed in the average hearing thresholds of the Groups II and III compared to Group I (p <0.05), however, no statistically significant difference was observed between the Groups II and III on the 4th day of the study. On the 8th day of the study, a statistically significant decrease was observed in the average hearing thresholds of Group III compared to Group II (p<0.05). On the 4th and 8th days of the study, a loss was found in the emission values of Group II and Group III compared to the pre-study period, as a result of the DPOAE test. When Group II and Group III were compared with each other, it was found that the emission loss was higher in Group II in both periods, with a higher rate on the 8th day of the study. The histopathological findings also showed a higher apoptosis in Group II in a way to support the electrophysiological data. According to the histopathological findings and electrophysiological tests conducted within our study, it was seen that there were ototoxic effects in Group II and Group III compared to the pre-study period, however, such effects were fewer in Group III. These findings show that Cortexin has protective effects against the cisplatin ototoxicity and suggest that Cortexin may be an alternative for protecting from ototoxicity in ototoxic drug applications. Key Words: Ototoxicity, Cisplatin, Cortexin