Investigation of Astaxanthin Effect on Cisplatin Ototoxicity in Rats by Using Otoacoustic Emission, Total Antioxidant Capacity, and Histopathological Methods.

BACKGROUND: Cisplatin-induced ototoxicity is related to oxidative stress. Astaxanthin is one of the most powerful antioxidants in nature. AIMS/OBJECTIVES: To investigate the protective effect of astaxanthin on cisplatin-induced ototoxicity. MATERIALS AND METHODS: Thirty-five Sprague Dawley female rats were divided into 5 groups: control, cisplatin, and cisplatin with 10, 20, and 40 mg/kg astaxanthin groups. Cisplatin group received a single intraperitoneal injection of 14 mg/kg cisplatin. While saline was administered in the control group, in the other 3 groups, 10, 20, and 40 mg/kg daily doses of astaxanthin were administered through orogastric cannula before administration of cisplatin. Baseline and 10th day otoacoustic emission tests were administered. An intracardiac blood sample was taken to measure total antioxidant capacity (TAC), and the cochleas of the animals were investigated histopathologically. RESULTS: Hearing level of astaxanthin 40 mg/kg + cisplatin group was higher at 24 kHz and 32 kHz frequencies compared to the cisplatin group. The TAC value of the cisplatin group was lower than both the control and astaxanthin + cisplatin groups (P < .05). On histopathological examination, the other groups were deformed compared to the control group, but no statistically significant difference was observed between the astaxanthin + cisplatin and cisplatin groups. CONCLUSIONS AND SIGNIFICANCE: Astaxanthin showed protective effect at high frequencies when it was administered at high dose. Thus, astaxanthin may have protective effect against cisplatin-induced ototoxicity.

The effects of lipoic acid and methylprednisolone on nerve healing in rats with facial paralysis.

OBJECTIVE: To investigate the effects of lipoic acid and methylprednisolone on nerve healing in rats with traumatic facial paralysis. MATERIALS AND METHODS: The rats were randomly divided into four groups, with six rats in the control group and eight each in the remaining three groups. The buccal branch of the facial nerve in all groups except the control group was traumatized by a vascular clamp for 40 minutes. Group 1 was given lipoic acid (LA), Group 2 was given methylprednisolone (MP), and Group 3 was given lipoic acid and methylprednisolone (LA + MP) for one week. Nerve stimulus thresholds were measured before trauma, after trauma and at the end of the one week treatment period. RESULTS: When the groups were compared with each other, post-treatment threshold levels of LA + MP were significantly lower than LA. Although post-treatment threshold levels of LA and MP were still higher than the control group, there was no significant difference between LA + MP and control values (p > .05). CONCLUSION: Lipoic acid has a positive effect on nerve healing and can enhance the effect of methylprednisolone treatment. It is a good alternative in cases where methylprednisolone cannot be used.