The protective effect of astaxanthin on cisplatin-induced ototoxicity

Background. Promising studies have been conducted with many substances to reduce the ototoxic effects of cisplatin, but there is no treatment that completely eliminates the ototoxic effect. Objectives. To determine the effectiveness of astaxanthin (ASX) as a protective agent against cisplatin-induced ototoxicity. Materials and methods. Thirty-six rats were randomly divided into 6 groups. Group 1 received no drug injections except for anesthetics; group 2 received intraperitoneal (IP) olive oil only for 8 days; group 3 received only IP ASX 75 mg/kg dissolved in olive oil for 8 days; group 4 received a single dose of only IP 16 mg/kg cisplatin on the 5th day; group 5 received 25 mg/kg ASX IP daily for 8 days and a single 16 mg/kg dose of cisplatin on the 5th day; group 6 received 75 mg/kg ASX IP daily for 8 days and a single 16 mg/kg dose of cisplatin on the 5th day. The animals were tested for distortion product otoacoustic emissions (DPOAE) before and 3 days after cisplatin treatment. The animals in all groups were sacrificed under anesthesia on the 10th day. Before sacrifice, inferior vena cava blood samples were drawn into commercial tubes for biochemical analysis and their cochlea were prepared for histological analysis. Results. The ASX+cisplatin groups demonstrated significantly higher DPOAE thresholds when compared to the cisplatin-only group (p < 0.05). The ASX 25 mg/kg/day+cisplatin group showed a significant increase in total antioxidant capacity compared to the cisplatin-only group, whereas the ASX 75 mg/kg/day+cisplatin group had significantly lower total oxidative stress and oxidative stress index. Histologic results showed that the cortical organ was better preserved in the ASX+cisplatin groups compared to the cisplatin-only group, and the degeneration in the spiral ganglion and inner and outer hair cells was less visible in the ASX groups. Conclusions. Astaxanthin can protect hearing from cisplatin-induced ototoxicity, prevent cellular degeneration and significantly reduce oxidative stress