Protective effect of astaxanthin in experimental myringosclerosis model

Myringosclerosis is the most common type of tympanosclerosis and its main feature is hyaline degeneration and calcification of the collagen structure in the lamina propria of the tympanic membrane. Large sclerotic plaques that cause hearing loss can be seen in myringosclerosis, which is usually asymptomatic. The aim of this study was to evaluate the effectiveness of astaxanthin on the development of experimentally induced myringosclerosis. 49 Sprague Dawley rats included in the study were divided into seven groups, each consisting of seven randomly selected subjects. No procedure was performed after myringotomy was performed on 14 tympanic membranes (TM) of seven rats in group A. In groups B1, B2, B3, which are topical application groups, myringotomy was performed on 14 TMs of seven rats in each group. Then, a gelfoam piece soaked with 0.2 ml olive oil, 15 mg/kg astaxanthin dissolved in 0.2 ml olive oil, and 30 mg/kg astaxanthin dissolved in 0.2 ml olive oil was placed on the TM from the external auditory canal (DKY). Then, 0.2 ml olive oil, 15 mg/kg astaxanthin dissolved in 0.2 ml olive oil, and 30 mg/kg astaxanthin dissolved in 0.2 ml olive oil were dripped into the external auditory canal once a day, completing the treatment period of seven days, respectively. In the oral application groups C1, C2, C3, myringotomy was performed on 14 TMs of seven rats in each group. Then, 0.5 ml olive oil, 15 mg/kg astaxanthin dissolved in 0.5 ml olive oil and 30 mg/kg astaxanthin dissolved in 0.5 ml olive oil were administered to the groups via oral gavage, respectively. These applications were repeated once a day at the same time every day for seven days. Two tympanic membranes were not included in the study due to the death of one rat in group B1 during the study period. Myringosclerosis assessment was performed 14 days after myringotomy. Then, the temporal bone bullae of the decapitated rats were removed and examined histopathologically and immunohistochemically in terms of inflammation, collagen-IV accumulation, TM thickness and sclerosis score. When the results were evaluated, a statistically significant decrease was detected in TM thickness increase, inflammation score increase and sclerosis score increase in groups C2 and C3. This shows that astaxanthin, when administered orally at 15 mg/kg/day and 30 mg/kg/day for seven days, effectively prevents the formation of myringosclerosis. Although there was a decrease in the mentioned parameters in the groups that received topical astaxanthin, no statistically significant difference was detected. As a result, astaxanthin, which is a strong antioxidant, is very effective in preventing the formation of myringosclerosis. Astaxanthin will become an agent that takes its place in routine clinical practices with additional studies to be conducted in different doses and application methods and different experimental groups. Keywords: Myringotomy, astaxanthin, myringosclerosis