| Objective:To investigate the protective effect of lidocaine carbonate on noise-induced hearing threshold injury in guinea pigs with noise-induced deafness at different time before and after noise exposure.Method :Thirty-two adult male SPF white guinea pigs with red eyes were randomly divided into four groups:normal group,simple noise exposure group(Abbreviated as simple group,the following is the same as),treatment group and prevention group.Noise-induced deafness animal model was established.No noise exposure was observed in the normal group,and 120 db SPL white noise exposure was given to the simple group for 4 hours a day for 4 consecutive days.The treatment group was treated with lidocaine carbonate 5 mg / kg immediately after exposure to the same noise,followed by 5mg/kg/ injection 3 times a day for 7 days.In the prevention group,lidocaine carbonate 5 mg / kg was given 1 h before the same noise exposure,and then 5mg/kg/ was given 3 times a day for 7 days.All the above administration routes were injected through jugular catheter.The induced rate of binoacoustic emission(Distortion product otoacoustic emission,DPOAE)of guinea pigs before noise exposure,immediately after noise exposure and 3 and 7 days after noise exposure was measured and compared.The protective effects of lidocaine carbonate on noise-induced hearing threshold injury were analyzed in guinea pigs before and 7 days after noise exposure,and the activity of superoxide dismutase(Superoxide dismutase,SOD)in serum and cochlea SOD activity in guinea pigs after noise exposure.Results:1.Except for the control group,the induced rate of DPOAE at every frequency in the other groups decreased immediately after noise exposure,and the difference was statistically significant(P < 0.008).The induced rate of DPOAE in the prevention group was higher than that in the control group and the treatment group(P < 0.008),but there was no significant difference between the simple group and the treatment group in each frequency of DPOAE(P > 0.008).The noise-induced deafness can be induced by this noise condition,and lidocaine carbonate has protective effect on noise-induced hearing loss.However,immediately after noise exposure,lidocaine carbonate was not effective in the treatment of noise-induced hearing impairment.2.On the 3rd day after noise exposure,the induced rates of DPOAE in the control group,simple group and treatment group were in the order from large to small: control group > treatment group > simple group,the difference was statistically significant(P < 0.008).There was a significant difference between the prevention group and the control group in the induced rate of 2.0kHz DPOAE,but there was no significant difference in the rate of DPOAE induced by the rest frequency between the two groups(P > 0.008).The induction rate of DPOAE in prevention group was higher than that in simple group(P < 0.008).The induction rate of DPOAE on 4kHz in the prevention group was higher than that in the treatment group(P < 0.008),but there was no significant difference in the rest frequency between the prevention group and the treatment group(P > 0.008).Three days after noise exposure,the effect of lidocaine carbonate in the treatment of noise-induced hearing impairment was improved,but the induced rate of DPOAE at 4kHz frequency was not as good as that of preventive administration of lidocaine carbonate before noise exposure.3.On the 7th day after noise exposure,the induced rate of DPOAE in the simple group was lower than that in the other three groups(P < 0.008).There was no significant difference between the control group,the treatment group and the prevention group in the induced rate of DPOAE at each frequency(P > 0.008).On the 7th day after noise exposure,the hearing of guinea pigs treated with lidocaine carbonate could be restored to normal level,and the hearing of noise-induced deaf guinea pigs without treatment did not recover autonomously.4.The induced rate of DPOAE at all frequencies in the simple group was lower than that before noise exposure(P < 0.008),and there was a significant difference between the two groups(P < 0.05).In the treatment group,the induced rate of DPOAE at every frequency decreased immediately after noise exposure(P < 0.008),and decreased to 1.0 kHz on the 3rd day after noise exposure(P < 0.05).The induced rate of 2.0kHz DPOAE was significantly higher than that of immediately after exposure(P > 0.008),and the rate of residual frequency of DPOAE was significantly higher than that of immediately after noise exposure(P < 0.008).On the 7th day after noise exposure,the induced rate of DPOAE recovered to the level before noise exposure,and there was no significant difference between the two groups(P > 0.008).In the prevention group,the induced rate of 1.0kHz DPOAE was not significantly decreased immediately after noise exposure(P > 0.008),but the rate of DPOAE induced by other frequencies was decreased immediately after noise exposure(P < 0.008),and there was no significant difference between the two groups(P < 0.05).However,on the 3rd day after noise exposure,there was significant difference in the induced rate of 0.5kHz DPOAE(P < 0.008),but there was no significant difference between the other frequencies of DPOAE and that before noise exposure(P > 0.008),but there was no significant difference between the two groups on the 3rd day after noise exposure(P < 0.05).On the 7th day after noise exposure,the induced rate of DPOAE recovered to the level before noise exposure.There was no significant difference between the two groups(P > 0.008).It can be concluded that the hearing of guinea pigs exposed to noise is damaged,and lidocaine carbonate has a better therapeutic effect on hearing impairment when it is used for 3 days after noise exposure.Prophylactic administration of lidocaine carbonate has protective effect on noise-induced hearing damage.7 days after treatment,noise-induced hearing damage is expected to return to the pre-exposure level.5.On the 7th day after noise exposure,the activities of SOD in serum and SOD in cochlea of guinea pigs in simple group decreased significantly,which were significantly lower than those in the other three groups(P < 0.05).The serum SOD activity and cochlea SOD activity of guinea pigs in control group,treatment group and prevention group were close to normal(P > 0.05).It can be concluded that lidocaine carbonate has the effect of scavenging oxygen free radicals and anti-oxidative stress,and can be used to treat noise-induced deafness.Conclusion:1.Under this condition(the head of the 120 dB SPL,animal was placed in front of the 2cm of the sound source,exposed continuously for 4 hours at the same time every day for 4 days),noise exposure could damage the hearing of guinea pigs,and could not recover autonomously in a short period of time.Lidocaine carbonate plays an important role in the prevention and treatment of noise-induced hearing damage.After the treatment of lidocaine carbonate,the hearing can be restored to the level before noise exposure.2.Lidocaine carbonate has the effects of scavenging oxygen free radicals and anti-oxidative stress,which can be used to treat noise-induced deafness. |
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