Protective And Treatmen Effect Of D-methionine On Noise Induced Hearing Loss

Part One Study on noise induced hearing loss and drugs for preventionand treatment of animalObjective: Noise seriously affects people's hearing,and the proportion of noise induced hearing loss in all deafness is high,but the protection and treatment methods in clinical can not achieve satisfactory effects until now.Methionine,as one of the 8 essential amino acids in human body,has an important role in maintaining a healthy state.The methyl contained in the methionine molecule,plays as a methyl donor in the process of metabolism and synthesis.The methionine and its metabolites also play as a antioxidant to protect DNA and protein.Human tissue exist loss of gap junction,and connexin26(Cx26)and connexin30(Cx30)are the crucial component of gap junction in the inner ear.Cx26 and Cx30 play an important role in development and function of the cochlear.In this paper,we will to study the effects of noise on cochlear tissue and the protective effect and therapeutic effects of methionine on noise induced hearing loss and the changes of Cx26 and Cx30 during the process.Methods:40 female Kunming mice were divided into 4 groups randomly:(1)Control group(n=10)(2)Noise group(n=10)(3)D-methionine + noise group(n=10)(4)Noise+ D-methionine group(n=10).The mice of control group were injected saline once a day,for 3 days;the mice of noise group were exposed to white noise.The duration of sound exposure was 10h/d,107-110 dB SPL,for 3 days,after noise exposure,saline was injected to the mice of noise group,once a day,for 3 days;the mice in D-methionine + noise group were injected 600mg/kg of D-methionine,once a day,for 3 days before noise exposure,and the noise exposure was same with noise group;in the noise+ D-methionine group,mice were expoued to noise first for 3 days,and then injected with D-methionine.All of the 4 groups were tested with auditory brainstem response(ABR)before and after the noise exposure to assess the hearing function.After the last ABR test,the cochlea tissue samples were quickly collected by microdissection.And the samples were made into slice or operated to get the basilar membrane.We used anti-myosin-VI staining to see the living of hair cells in the inner ear;and the exchange of Cx26 and Cx30 expression were assessed by immunohistochemistry.With all above methods,we can observe the protective and cure effects of methionine on noise induced hearing loss.Statistical analysis was performed using SPSS22 software,the results were indicated with mean ± standard deviation and statistical significance was determined with P< 0.05.Results:1 General observations: The mice in control group were growing normally,lively,and sensitive to noise.The pure noise group was slightly depressed,thin,and lags in response.The mice in the other two groups were slightly agitated,and responsed to noise normally.2 The result of ABR test: All the four groups of mice's hearing threshold showed no significant difference before noise exposure.And the ABR threshold of each group after noise were respectively as below: control group,15.50±4.38 dB SPL;noise group,40±14.14 dB SPL;D-methionine + noise group,28.06 ± 9.57dBSPL;Noise+ D-methionine group,22.81 ± 4.82 dB SPL.Compared between the four groups,the D-methionine + noise group and the Noise+D-methionine group showed no significant difference(P> 0.05),the rest were statistically different(P< 0.05).The control group's ABR threshold was not statistically different before and after the noise exposure(P >0.05),so that we can exclude factors of age related hearing loss.3 The results of anti·-myosinVI staining: After anti-myosin VI staining,the samples were observed under confocal microsrope,the outer hair cells(OHCs)and inner hair cells(IHCs)were arranged regularly,no cell degeneration;in the noise group,we can see obviously degeneration of OHC,as well as malalignment,blurring,but no IHC damaged.There was no damage to IHCs of D-methionine+noise group and Noise+D-methionine group,the OHCs were scattered,a few mount of degeneration and the structure was clear.To calculate the survival rate of OHCs,the survival rate was statistically different(P < 0.05)between every two groups.4 The results of Cx26 and Cx30 immnofluorescence staining: In the control group,there were rich of Connexin26 and Connexin30 expressed in basilar membrane,stria vascularis and spiral ligament.Cx26 and Cx30 in noise group were significantly decreased in the there location.In Dmethionine+noise group and Noise+D-methionine group,there were also different degrees decreased expression of Cx26 and Cx30,but is relatively slight than the degree of noise group.Part Two Study on hearing impairment caused by strong noise on thehuman ear and drug prevention and treatmentObjective: Noise seriously affects people's quality of life,long-term exposure to high intensity noise or transient explosive noise will lead to hearing loss(Noise Induced Hearing Loss,NIHL),the protection and the treatment of NIHL measures are still in the exploratory stage.The purpose of this study is to explore the effective methods for the treatment of NIHL by analyzing the diagnosis and treatment process and the characteristics of hearing loss of people who were diagnosed with Explosive Deafness in the past ten years.Methods:In our study,we collected 75 patients(106 ears altogether)from the army who were admitted to Bethune International Peace Hospital from the year of2007 to 2016,to analysis the prognosis and the factors related to the prognosis of Explosive Deafness by collecting the basic information of patients,the results of hearing tests and treatment progresses.Results:1 After 7-15 days of treatment,16 ears were cured,33 ears were improved,and there are no effect on the other 57 ears.The total effective ratewas 46.23%.The accompanying symptoms such as tinnitus,aural fullness and otalgia were alleviated after the treatment.2 The relationship between the prognosis and the course of disease: the later to see a doctor,the worse of the result and the lower of the total effective rate.Conclusions:1 Noise can induce hearing loss,which can be reflected from morphology,and methionine has protection and treatment effect on noise induced hearing loss;2 Connexin26 and Connexin30 were involved in the pathogenesis of NIHL,and can be reflected from the staining of immunofluorescence histochemistry;3 Methionine may provide protective and therapeutic effects on noise induced deccreaed expression of Cx26 and Cx30.4 The prognosis of ED is closely related to the time of asking for medicine treatment,the more timely,the more likely to achieve good results.5 At present,it is effective for the treatment of explosive deafness,but it still need to be advanced.