The Effect of Erythropoietin on S100 Protein Expression in Cochlea After Acoustic Overstimulation: An Experimental Study

Aim: To investigate the effect of Erythropoietin on acoustically overstimulated rat spiral ganglion neurons (SGNs) using S100 protein immunostaining.Material and Method: Twenty-two Wistar albino rats were divided into three groups: healthy control group (n=7), Saline solution (n=7) and Erythropoietin injection groups (n=8). Saline solution and Erythropoietin injection groups received white noise (100 dB SPL) for 3 hours. Cochlear sections were stained by silver staining technique and immunostained by S100 antibody. Results: Histochemical analysis of silver staining sections revealed normal structure and a weak staining in SGNs of healthy control group. However, dark-black cytoplasmic staining, cellular shrinkage and degeneration were detected in saline injection group. On the other hand, a few weakly stained neurons were observed in erythropoietin injection group. S100 staining demonstrated strong reaction in Schwann cells and myelin sheaths of SGNs in healthy control group (p<0.05). In saline solution injection group, Schwann cells showed moderate S100 reaction and other regions of SGNs showed weak reaction (p<0.05). In erythropoietin injection group, strong S100 expression almost similar to the healthy control group was determined, although there was an occasional decrease. Discussion: Erythropoetin may prevent noise induced SGN degeneration via protecting the Schwann cells in rat cochlea