Experimental Study On The Prevention And Treatment Effects Of TianGu Granule On Noise-Induced Hearing Loss

Objective To observe the prevention and treatment effects of TianGu granule on noise-induced hearing loss in guinea pigs and discuss its mechanisms.Methods The guinea pigs were divided into four groups: normal control group ( group A ), model control group ( group B ), group prevented with TianGu granule ( group C ), and group treated with TianGu granule ( group D ). The guinea pigs except group A were simultaneously exposed to 4 KHz steady white noise at 110 dB SPL for 6 days continuously ( 6h/d ). Group C were given TianGu granule ( 15ml/kg/d, calculated in accordance with 30g/kg/d of the crude drug ) for 13 days beginning from the 7th day before noise exposure and group D beginning from the day after noise exposure. Group B were given the same volume of physiological saline in the same time with group C. ABR ( Auditory Brainstem Response ) was used to assess the variation of the auditory function in each group of guinea pigs. The microstructure of hair cells on the basilar membrane and the blood filling state of stria vascularis in the cochlea spiral ligament were observed under the light microscope and the loss rate of the outer hair cells were counted. The stereocilium ultra structural changes were examined with scanning electron microscope.Result Compared with group B and D, group C showed significantly lower ABR threshold (P<0.05), shorter latency (P<0.01), less loss rate of outer hair cells (P<0.01) as well as slighter morphological lesion of cochlear hair cells and ischemia state of stria vascularis . Compared with group B , group D showed significantly lower ABR threshold (P<0.05), shorter latency (P<0.01) and slighter ischemia state of stria vascularis, but there was no significant difference about the loss rate of outer hair cells between them (P>0.05), and the morphological lesion of cochlear hair cells were also similar.Conclusion TianGu granule has obvious prevention effect on noise-induced hearing loss. It also has certain treatment effect on improving auditory function. The prevention effect is much better than the treatment effect. One of the important mechanisms of prevention and treatment effect of TianGu granule on noise-induced hearing loss is improving the microcirculation of cochlear.