OBJECTIVETo study the protective effect of Ligustrazine Injection (LI) against cisplatin-induced ototoxicity and to explore its mechanism.

METHODSThirty healthy adult guinea pigs were randomly divided into three groups, 10 in each group, i.e., the normal control group, the cisplatin group, and the LI group. Guinea pigs in the normal control group were intraperitoneally injected with normal saline at 3 mL/kg for 7 consecutive days. Those in the cisplatin group were intraperitoneally injected with cisplatin at 3 mg/kg for 7 consecutive days. Those in the LI group were intraperitoneally injected with LI at 140 mg/kg for 7 days, but cisplatin (3 mg/kg) was intraperitoneally injected from the opposite side starting from the 4th day. Brainstem auditory evoked potential (BAEP) was performed in all animals before and after injection. All animals were sacrificed after the final testing under anesthesia and their cochleas collected. Half the cochleas of each group were collected for silver nitrate staining of cochlear basilar membrane stretched. The other half the cochleas of each group made into paraffin sections to observe the apoptosis of cochlea cells by TUNEL method and the expression levels of c-Jun detected by immunohistochemistry.

RESULTSThere was no statistical difference in the difference of BAEP threshold among the 3 groups before injection (P > 0.05), but the BAEP threshold increased in the cisplatin group and the LI group (P < 0.05). Besides, it was higher in the cisplatin group (P < 0.05). In the cisplatin group, most hair cells were missing, spiral ganglion cells obviously decreased, more TUNEL positive cells occurred, and the expression of c-Jun was stronger. But the aforesaid impairment in the LI group was obviously lessened (P < 0.05).

CONCLUSIONSLI showed certain antagonist effect on cisplatin-induced ototoxicity. Its mechanism might be associated with scavenging oxygen radicals of the cochlea tissue, improving the microcirculation, and fighting against apoptosis.