The Effect Of Ligustrazine On Gentamicin-induced Expression Of Calmodulin And Prestin In Guinea Pig Cochlear

ObjectivesTo investigate the effect of ligustrazine(TMP)on gentamicin(GM)-induced expressional alterations of Calmodulin(CaM)and Prestin to explore the intervention mechanism of ligustrazine,providing a supplementary method to the treatment of ototoxic deafness.MethodsScreening with healthy white red-eye 80 guinea pigs,randomly divided them into four groups:GM group(GM 120mg·kg-1·d-1 intramuscular injection),GM+TMP group(GM 120mg·kg-1·d-1 intramuscular injection and TMP 20mg·kg-1·d-1 intraperitoneal injection respectively),TMP group(TMP 20mg·kg-1·d-1 intraperitoneal injection)and normal saline group(NS).NS group was given NS as the same amount as the GM group.Guinea pigs from each group were continuously given drugs for 12 days.To detect the hearing threshold of each group by ABR measurement.At the same time,cochleas were prepared to be formalin-fixed paraffin-embedded format,then cochlear slices and HE dye were done and the structure of Corti’s organ and outer hair cells were observed.Western blot methods was used to detect CaM and Prestin expression level.Results1.From the results of click ABR test,the hearing threshold of all guinea pigs from each group has no significant difference before they were given drugs(P>0.05);The ABR threshold of GM group was increased significantly after Ototoxic GM exposure compared with NS group(P<0.01);The threshold of GM+TMP group showed significant difference with GM group(P<0.01),but still higher than NS group(P<0.01).There was no significant difference between NS group and TMP group(P>0.05).2.From the observation of cochlear slices,the histomorphology of cochlea got from NS group and TMP group was normal;The Corti’s organ of GM group was severely deformative with OHC swelling,and there are lots of cells missing and cavitation in the spiral ganglion;The situation in the GM+TMP group was slightly changed,but better than GM group.3.From the western blot results,there was a significant difference in expression of CaM and Prestin between GM group and other groups(P<0.01),indicating that the CaM and Prestin expression increased significantly;GM+TMP group has a lower expression of CaM and Prestin than GM group(P<0.01);There was no significant difference between GM+TMP group,NS group and TMP group(P>0.05);4.From the correlation analysis,it can be seen that the expression level of CaM and Prestin have a linear correlation to the hearing threshold(P<0.05).Conclusion1.Ototoxic GM exposure causes the the over expression of CaM and Prestin in cochlear,which is correspondent to the hearing threshold shifts,indicating that CaM and Prestin might be involved in the pathological process of hearing loss caused by GM.2.TMP could effectively attenuate GM ototoxicity by inhibiting CaM and Prestin overexpression induced by GM,this might be one of the molecular mechanisms by which TMP could protect against GM ototoxicity.