Evaluation of the effect of phenolic compounds on auditory evoked potentials with oxidative damage in experimental diabetic neuropathy

Diabetes is a systemic disease that can affect tissues and physiological functions at the molecular and biochemical levels. Although many clinical trials have found an association between diabetes and its effects on hearing loss and bone structure, the pathophysiological mechanisms of this effect are controversial. Diabetic neuropathy was evaluated by looking at GHbA1c levels and blood glucose and weight measurement of the STZ+NA T2 DM rats. Function of the hearing related of diabetes was assessed by ABR test. The effect of diabetes on bone structure was analyzed by means of Micro CT. At the level of oxidative stress in blood, the antioxidant effect of eugenol and quercetin was determined by MDA, SOD and GSH ELISA kits. In the ABR, when the tone burst stimulus (at 8, 16, 24 and 32 kHz frequencies) were evaluated together with the hearing thresholds of the control and experimental groups in all frequencies, the thresholds increased in the diabetic group compared to the control group and this increase was statistically significant (p<0.001). In the eugenol and quercetin groups, there was a significant decrease in the threshold values obtained with high frequency stimulus (24 and 32 kHz) compared to the diabetic group (p<0.05). When the femur Tb.Th, Tb.BV/Tb.Tv and SMI values were compared, the control, quercetin and eugenol groups showed a statistically significant difference compared to the diabetic group (p<0.05). Serum GHbA1c, MDA, GSH and SOD levels were significantly different from the control group (p<0.05). MDA, SOD and GSH levels of eugenol and quercetin groups were statistically significant compared to diabetic groups (p<0.05). In our study, the experimental STZ+NA T2 DM model showed that eugenol and quercetin had antioxidant and antidiabetic effects on the loss of hearing and bone structure due to oxidative stress related complications of diabetes. Key Words: Diabetes, oxidative stress, antioxidant, hearing loss, bone