The evaluation of the effects of Betahistine Dihydrocloride, Ginkgo Biloba and L-Carnitine on the cochlea of rats that has been applied acoustic trauma with otoacoustic emmision

It has been long suggested that oxidative stress due to hypoxia is the main pathological feature in cochlear damage that occur in noise-induced hearing loss (NIHL). Several pharmacological agents for NIHL prophylaxis or treatment have been studied in different trials however these agents can not be used in clinical practise, currently. In the present study, we aimed to investigate prophylactic effects of Betahistine Dihydrocloride, Ginkgo Biloba and Asetyl L-Carnitine separately on acoustic trauma in an animal model. In our study, a total of 40 Sprague-Dawley mature female rats were used. The animals were divided into four groups. While first group was given Betahistine Dihydrocloride; second, third, and fourth group was given Ginkgo Biloba, L-Carnitine and saline solution respectively for a period of 21 days, which was followed by administration of acoustic trauma to all subjects. DPOAE (distortion product otoacoustic emission) measurements were performed three times to all subjects, before and after administration of pharmacological agents, just after administration of acoustic trauma. Results were evaluated statistically and each group in itself was compared for SNR variables, no statistically significant difference was found in Betahistine group in terms of all frequencies (P>0,05) whereas a statistical significant decrease was detected in Ginkgo Biloba group in terms of SNR2000 and SNR6000 at 1. and 3. assesment (P<0,05) and a statistical significant decrease was detected in Carnitine group in terms of SNR3000 at 1. and 3. assesment; a statistical significant decrease was detected in terms of SNR1000 and SNR4000 at 2. and 3. assesment and in terms of SNR2000 and SNR3000 at 1. and 3. assesment in the control group (P<0,05). When the groups were compared in terms of SNR variables, statistically significant difference was detected in SNR1000 that obtained from AAE test at 3. assesment (P<0,05); the difference was observed between Betahistin group and the control group; Carnitine group and the control group. When each group was compared in itself for DP variables, statistically significant difference was observed in a few frequencies in pharmacological agent groups (P<0,05) whereas no statistically significant difference was detected in all frequencies in the control group (P>0,05). When the groups were compared to each other in DP variables, it was found that all frequencies displayed no statistical difference (P<0,05). Given these findings, although a significant decrease was detected in some frequencies in pharmacological agent administered group when compared to the control group according to in-group evaluations for DP variables, we suggest that all pharmacological agents used in our study particularly Betahistine Dihydrocloride and L-Carnitine, can be effective in acustic trauma prophylaxis, considering the fact that SNR parameters are more valuable than DP parameters.Key Words: Betahistine Dihydrocloride, Gingko Biloba, L-Carnitine, Acoustic Trauma, Otoacoustic Emission