Investigating the Effect of Hypericum Perforatum L. on Hearing in Rats: An Experimental Study

Objectives: Hypericum perforatum L. (HP) is among the oldest used and most comprehensively studied medicinal herbs. Anti-inflammatory activities of different Hypericum extracts on external auditory canal and also in the prevention of tympanic membrane perforation and myringosclerosis were investigated experimentally in the animal model. This study was to investigate whether or not intratympanic injection of H. perforatum L. in the middle ear of the rats causes ototoxicity, via auditory brainstem response (ABR). Materials and Methods: Rats were assigned to three groups as Group C, S, and D. Excessive external auditory canal edema developed in the rats in Group D as of the 5th day and Group D was excluded from the study by considering that ABR records could be affected. Results: A statistically significant difference was observed mean latency values of the wave V and III at the baseline and on the 7th day in Group S (P < 0.05). A significant shortening was calculated in the interpeak mean latency values of the waves III-V at the baseline and on the 7th day in Group S (P < 0.05). A statistically significant difference was observed between the baseline III-V wave interpeak mean latency values in the between-group evaluation on the 7th day (P < 0.05). A statistically significant difference was detected in the mean values of the wave V/Va amplitude ratios at the baseline and on the 7th day in Group S (P < 0.05).In the between-group evaluation, a statistically significant difference was found in the mean values of the wave V/Va amplitude ratios on the 7th day (P < 0.05). Conclusion: The results of the study conducted in accordance with the hypothesis point out that the intratympanic injection of H. perforatum L. may have an ototoxic effect.