ABSTRACT
Objective To inject PPTA into the cochlea of guinea pigs through scala tympani fenestration ,to study the protective effect of PPTA injection on the cochlear damage induced by gentamicin and mechanism of oxy-gen free radical .Methods Randomly divided were the guinea pigs with normal hearing into three groups :the con-trol group ,GM group and PPTA group .We injected the artificial perilymph 10μl /d into cochlea through scala tym-pani fenestration on control group for 3 days ,injected GM 160 mg · kg -1 · d-1 on GM group for 3 days ,injected the PPTA 10 μl /d into the cochlea through scala tympani fenestration and injected GM 160 mg · kg -1 · d-1 at the same time on PPTA group for 3 days .We tested ABR and analyzed the hearing changes .We tested the OFR level reacted by SOD and GSH of the cochlea tissue .SEM and TEM were performed to observe the change of cell mor-phology .Results For ABR ,the control group was 12 .75 ± 3 .796 ,GM group 28 .230 ± 4 .953 ,PPTA group23 .47 ±9 .211 dB SPL(P<0 .05) .For SOD ,the normal group was 50 .241 ± 9 .080 ,GM group 28 .230 ± 4 .953 ,PPTA group 43 .089 ± 4 .587 U/mgprot(P<0 .05) .For GSH ,the normal group was 3 .03 ± 0 .33 ,GM group 1 .51 ± 0 .13 ,PP-TA group 2 .50 ± 0 .16 Ggsh/L(P<0 .05) .The changes of hair cells of PPTA group were obviously less severe than that of GM group .For TEM ,the changes of spiral ganglion and stria vascularis of PPTA group were obviously less severe than that of GM group .Conclusion Injecting PPTA through scala tympani fenestration can protect cochlea by generating the excess of OFR when confronting against GM .