Research On The Protective Effect Of Ursolic Acid On Cisplatin-induced Ototoxicity In Mouse

To investigate the protective effect and mechanism of ursolic acid (UA) oncisplatin (CDDP)-induced ototoxicity in mouse, and to provide a new idea forprotecting against CDDP ototoxicity in clinic.Methods1.120healthy BALB/c mice were randomly divided into control group, UAgroup, CDDP group and CDDP plus UA group, each group was30mice. Micefrom each group were continuously given drugs by introperitoneal injectiononce daily for5days. Expression of transient receptor potential vanilloidreceptor1(TRPV1), calpain,4-hydroxynonenal (4-HNE) and caspase-3inmouse cochlea was detected by using immunohistochemistry andimmunofluorescent staining, microscope image analysis and western blottechnique. At the same time, change of auditory threshold was tested byauditory brainstem response (ABR) measurement.2. Human ovarian cancer cell line SKOV3was cultured in vitro. MTTassay was used to detect the inhibitory effect of CDDP alone or in combinationwith UA on SKOV3cells growth, in order to observe the effect of UA onantitumor activity of cisplatin.Results1. After continuous administration for5days, ABR threshold shifts inCDDP group were increased significantly at each stimulating frequency ascompared with control group (P<0.01). Although ABR threshold shifts in CDDP plus UA group were also increased after treatment, but were lower than thosein CDDP group (P<0.01). It was no significant difference of ABR thresholdshifts between UA group and control group.2. The results of immunohistochemistry and microscope image analysisshowed that the expressions of TRPV1、calpain1and calpain2were weak inouter hair cell (OHC), spiral ganglion (SG) and stria vascularis (SV) of cochleain control group, while the expressions of TRPV1、calpain1and calpain2inCDDP group were greater than those in control group (P<0.01). Theexpressions of TRPV1, calpain1and calpain2in CDDP plus UA group weresignificantly weakened as compared with CDDP group (P<0.05, P<0.01). Itwas no significant difference about the expressions of TRPV1、calpain1andcalpain2between UA group and control group.3. The results of immunofluorescent staining and microscope imaginganalysis showed that4-HNE was weak expression in OHC, SG and SV ofcochlea in control group, while the expression of4-HNE in CDDP group wasgreater than that in control group (P<0.05). The expression of4-HNE in CDDPplus UA group was lower significantly than that in CDDP group (P<0.05,P<0.01). It was no significant difference about the expressions of4-HNEbetween UA group and control group.4. The results of western blot and semi-quantitative analysis showed thatthe protein expression levels of TRPV1, calpain1, calpain2, caspase-3and4-HNE in cochleae were very low in control group and UA group, while theprotein expression levels of above in CDDP group were higher than those incontrol group(P<0.01). The protein expression levels of above in CDDP plusUA group were lower significantly than those in CDDP group (P<0.05, P<0.01).5. The results of MTT assay showed that CDDP significantly inhibitedSKOV3cells growth in vitro (P<0.01). When combined with UA, the SKOV3cells growth inhibition rate was higher than CDDP alone (P<0.01), and with theconcentration of UA increased, SKOV3cells growth inhibition rate wasincreased markedly (P<0.01). ConclusionsTRPV1/calpain signal pathway and lipid peroxidation mediated CDDP-induced ototoxic damage on BALB/c mouse. UA could effectively attenuateCDDP ototoxicity by inhibiting high expressions of TRPV1and calpain as wellas by preventing lipid peroxidation induced by CDDP. Moreover, UA couldenhance the antitumor effect of CDDP, suggesting that UA is expected to be anew drug for protecting against CDDP ototoxicity in clinic.