| Objective To investigate the effect of Ligustrazine(TMP)on gentamicin-induced expression of p38 mitogen-activated protein kinase(p38MAPK)in guinea pig cochlear,and explore the protective role and molecular mechanism of Ligustrazine(TMP)on gentamicin-induced ototoxicity from the perspective of traditional Chinese medicine.Finally,wish to provide a supplementary method to the treatment of ototoxic deafness.Methods 1.48 healthy and hearing responsive white red-eye guinea pigs were randomly divided them into four groups:normal saline group(NS),gentamicin(GM)group,ligustrazine(TMP)group and GM+TMP group respectively.Guinea pigs from each group were continuously given drugs by intramuscular injection twice daily for 13 days.Guinea pigs from the GM group were given gentamicin based on the amount of 120mg·kg-1·d-1;All guinea pigs from the ligustrazine(TMP)group were given TMP based on the amount of 30mg·kg-1·d-1;,all guinea pigs from the GM+TMP group were given TMP and GM based on the amount of 120mg·kg-1·d-1 and 30mg·kg-1·d-1 respectively;In the NS group,all guinea pigs were given NS as the same amount as the GM group.In the first day and the last day,auditory threshold was tested by auditory brainstem response(ABR)measurement from 80dBSPL to the threshold.After ABR measurement was finish,all guinea pigs-were killed as soon as possible and remove the cochlears.At the same time,cochlears were prepared to be formalin-fixed paraffin-embedded format.After that cochlear slices and HE dye were done to observed the structure of Corti's organ and inner cell in the spiral ganglion Expression of p38MAPK in guinea pigs cochlea was detected by the western blotResults 1.From the results of click ABR test,the hearing threshold(HT)of all guinea pigs from each group has no significant differences before they were given drugs.(P>0.05).After given drugs,compared with the HT of NS group,the HT got from the GM group and GM+TMP group increased significantly,with significant difference(P<0.05),but the HT got from GM+TMP group increased less;however,there was no significant difference between NS group and TMP group(P>0.05)2.From the results of click ABR test,the latency and amplifude of GM group showed significant differences compared with GM plus TMP group,the NS group and TMP group.however,there was no significant difference between NS group,TMP group and GM plus TMP group.3.From the western blot results,compared with those of GM group,Expression of p38MAPK in GM plus TMP group,the NS group and TMP group were both significantly declined(P<0.05).There was no significant difference between NS group,TMP group and GM plus TMP group.4.Expression of p38MAPK and ABR threshold shift in GM plus TMP group were both significantly declined as compared with those of GM group(P<0.05)Moreover,change of p38MAPK expression was in high correlation with that of ABR threshold shift and latency.However,there is no correlation between p38MAPK and amplifude.5.From the observation of cochlear slices,the histomorphology of cochlea got from NS group was normal;the Corti's organ of GM group was severely deformative with OHC swelling and deformation and lots of cells missing and cavitation in the spiral ganglion;however,the situation in the GM+TMP group was better than GM group;In the TMP group,the structure of Corti's organ and cells in the spiral ganglion were normal,but slightly changed.Conclusion 1.GM is ototoxic and results in the abnormal cochlear histomorphology,the increase of ABR threshold,the increase of ABR latency,abnormally expressed p38MAPK,there is correlation between p38MAPK and ABR.As a result,we can guess that p38MAPK could play an important role in the ototoxic mechanisms2.TMP could effectively attenuate GM ototoxicity by inhibiting p38MAPK high-expression induced by GM,this might be one of the molecular mechanisms by which TMP could protect against GM ototoxicity... |
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