Expression of Antioxidant Genes in the Mouse Cochlea and Brain in Salicylate-Induced Tinnitus and Effect of Treatment with Spirulina platensis Water Extract

C-Phycocyanin Attenuates Noise-Induced Cochlear Synaptopathy via the Inhibition of Oxidative Stress and Intercellular Adhesion Molecule-1 in the Cochlea

The synapses between inner hair cells (IHCs) and spiral ganglion neurons (SGNs) are the most vulnerable structures in the noise-exposed cochlea. Cochlear synaptopathy results from the disruption of these synapses following noise exposure and is considered the main cause of poor speech understanding in noisy environments, even when audiogram results are normal. Cochlear synaptopathy leads to the degeneration of SGNs if damaged IHC-SGN synapses are not promptly recovered. Oxidative stress plays a central role in the pathogenesis of cochlear synaptopathy. C-Phycocyanin (C-PC) has antioxidant and anti-inflammatory activities and is widely utilized in the food and drug industry. However, the effect of the C-PC on noise-induced cochlear damage is unknown. We first investigated the therapeutic effect of C-PC on noise-induced cochlear synaptopathy. In vitro experiments revealed that C-PC reduced the H2O2-induced generation of reactive oxygen species in HEI-OC1 auditory cells. H2O2-induced cytotoxicity in HEI-OC1 cells was reduced with C-PC treatment. After white noise exposure for 3 h at a sound pressure of 118 dB, the guinea pigs intratympanically administered 5 μg/mL C-PC exhibited greater wave I amplitudes in the auditory brainstem response, more IHC synaptic ribbons and more IHC-SGN synapses according to microscopic analysis than the saline-treated guinea pigs. Furthermore, the group treated with C-PC had less intense 4-hydroxynonenal and intercellular adhesion molecule-1 staining in the cochlea compared with the saline group. Our results suggest that C-PC improves cochlear synaptopathy by inhibiting noise-induced oxidative stress and the inflammatory response in the cochlea.

Analysis of Studies in Tinnitus-Related Gene Research

Objective

Summarize and analyze the current research results of tinnitus-related genes, explore the potential links between the results of each study, and provide reference for subsequent studies.

Methods

Collect and sort out the research literature related to tinnitus genes included in PubMed, Web of Science, China National Knowledge Infrastructure, and Wanfang Data Knowledge Service Platform before December 31, 2019. Then the relevant contents of the literature were sorted out and summarized.

Results

Fifty-one articles were finally selected for analysis: 31 articles (60.8%) were classified as researches on animal models of tinnitus, and 20 (39.2%) as researches on tinnitus patients. Existing studies have shown that genes related to oxidative stress, inflammatory response, nerve excitation/inhibition, and nerve growth are differentially expressed in tinnitus patients or animal models, and have presented the potential links between genes or proteins in the occurrence and development of tinnitus.

Conclusion

The research on tinnitus-related genes is still in the exploratory stage, and further high-quality research evidence is needed.

Association of sleep terror, walking or talking and tinnitus

BACKGROUND/PURPOSE

Sleep disturbances are associated with chronic tinnitus in humans. However, whether parasomnias are associated with chronic tinnitus is unclear. This study aims to investigate this issue.

METHODS

Clinical data for 2907 subjects who had visited the Sleep Center of a community hospital in Taiwan during November 2011 to June 2017 were collected retrospectively. The association of chronic tinnitus with sleep terror, sleep walking, and sleep talking was analyzed using Pearson's Chi-Square test and multivariate logistic regression.

RESULTS

The cohort age ranged from 7 to 91 years old, with a mean age of 49.8 years (standard deviation, 14.3 years). The cohort included 1937 patients without and 970 patients with chronic tinnitus. The percentage of patients who experienced sleep terror was significantly higher among those with tinnitus than those without (p < 0.001). The percentage of patients reporting sleep walking was slightly higher in subjects with tinnitus than in those without, with borderline significance (p = 0.063). The percentage of patients experiencing sleep talking did not differ significantly between the groups. Multivariate logistic regression also showed that sleep terror but not sleep walking was significantly associated with tinnitus after adjusting for age, sex, hearing loss, and insomnia. After adjusting for other factors, subgroup analysis by age showed that sleep terror was significantly positively associated with chronic tinnitus in patients aged 20-44 years but not in those aged 7-19 or >45 years.

CONCLUSION

Sleep terror is positively associated with chronic tinnitus, especially in young adults.

Association of periodic limb movements during sleep and tinnitus in humans

Both of periodic limb movements during sleep (PLMS) and tinnitus were related with dopaminergic system dysfunction. However, it was still unclear whether PLMS, one kind of sleep disturbances, was associated with chronic tinnitus or not. Thus, we aimed to investigate this issue in humans. Clinical and overnight polysomnographic data of 2849 adults from a community hospital during Nov. 2011 to Jun 2017 in Taiwan was collected retrospectively. The association of PLMS and chronic tinnitus was analyzed by Student’s t-test, Pearson’s Chi-Square test, and multivariate logistic regression. The results showed that the mean age was 50.6 years old (standard deviation, SD = 13.3, range = 18~91) for all subjects. There were 1886 subjects without tinnitus and 963 subjects with tinnitus in this study. The PLMS was not significantly different between subjects without tinnitus (mean = 1.0/h, SD = 3.5/h) and subjects with tinnitus mean = 1.1/h, SD = 3.4/h) by Student’s t-test. The severity of PLMS was not significantly between non-tinnitus and tinnitus subjects by Pearson’s Chi-Square test. Multivariate logistic regression also showed that PLMS was not significantly associated with tinnitus after adjusting age, sex, subjective hearing loss, Parkinson’s disease, and insomnia. In conclusion, PLMS was not associated with chronic tinnitus in humans.

Outcomes of Triple-Combination Therapy for Chronic Tinnitus

BACKGROUND/AIM

Patients with tinnitus suffer not only from auditory dysfunction but also physical, mental, and social difficulties. Our aim was to investigate the outcomes of our triple-combination therapy for chronic tinnitus, which includes narrow-band noise masking, auricular acupuncture and cognitive behavioral therapy.

PATIENTS AND METHODS

The tinnitus handicap inventory (THI) scores of 78 adults with chronic tinnitus who received triple-combination therapy for 12 weeks were analyzed retrospectively.

RESULTS

There were 39 females and 39 males in this study. The mean age was 60.5 years [standard deviation (SD)=13.0, range=27-88 years] for all subjects. Mean pure tone average=39.5 decibel hearing level (SD=23.09). Pre-treatment mean THI score was 41.4 (SD=21.13), functional (F) subscore was 17.9 (SD=10.69), emotional (E) subscore was 10.6 (SD=6.87), and catastrophic (C) subscore was 12.9 (SD=4.85). Post-treatment THI total score was significantly lower compared to pre-treatment THI total score. Also, post-treatment subscores were significantly lower compared to pre-treatment subscores in F and C subsocres, but not in E subscore. In addition, multivariate logistic regression analysis showed that coffee and tea consumption was significantly positively associated with a reduction of THI total score.

CONCLUSION

Triple-combination therapy could be helpful for chronic tinnitus patients. It seemed that coffee and tea consumption may elicit increased improvement in conjunction with combined therapy for chronic tinnitus.

Association of periodic limb movements during sleep and Parkinson disease: A retrospective clinical study

Both of periodic limb movements during sleep (PLMS) and Parkinson disease (PD) were related with dopaminergic system dysfunction. We aimed to investigate the detailed association of PLMS severity and PD.Clinical and overnight polysomnographic data of 2230 adults older than 40 from a community hospital between November 2011 and June 2017 in Taiwan were collected retrospectively. The association of PLMS severity and PD was analyzed by Fisher exact test, univariate, and multivariate logistic regression.The mean age was 55.6 years old (standard deviation = 9.8, range = 40-91) for all subjects. There were 2205 subjects without PD and 25 subjects with PD in this study. The distribution of PLMS severity was not significantly different between subjects without PD and with PD (Fischer exact test, P = .215). Also, PLMS was not significantly associated with PD using univariate and multivariate logistic regression.The PLMS severity was not associated with PD.

Association of Tinnitus and Other Cochlear Disorders With a History of Migraines

Importance

A headache is a symptom of a migraine, but not all patients with migraine have headaches. It is still unclear whether a migraine might increase the risk of cochlear disorders, even though a migraine does not occur concurrently with cochlear disorders.

Objective

To investigate the risk of cochlear disorders for patients with a history of migraines.

Design, Setting, and Participants

This study used claims data from the Taiwan Longitudinal Health Insurance Database 2005 to identify 1056 patients with migraines diagnosed between January 1, 1996, and December 31, 2012. A total of 4224 controls were also identified from the same database based on propensity score matching. Statistical analysis was performed from January 23, 1996, to December 28, 2012.

Main Outcomes and Measures

The incidence rate of cochlear disorders (tinnitus, sensorineural hearing impairment, and/or sudden deafness) was compared between the cohorts by use of the Kaplan-Meier method. The Cox proportional hazards regression model was also used to examine the association of cochlear disorders with migraines.

Results

Of the 1056 patients with migraines, 672 were women and 384 were men, and the mean (SD) age was 36.7 (15.3) years. Compared with the nonmigraine cohort, the crude hazard ratio for cochlear disorders in the migraine cohort was 2.83 (95% CI, 2.01-3.99), and the adjusted hazard ratio was 2.71 (95% CI, 1.86-3.93). The incidence rates of cochlear disorders were 81.4 (95% CI, 81.1-81.8) per 1 million person-years for the migraine cohort and 29.4 (95% CI, 29.2-29.7) per 1 million person-years for the nonmigraine cohort. The cumulative incidence of cochlear disorders in the migraine cohort (12.2%) was significantly higher than that in the matched nonmigraine cohort (5.5%). Subgroup analysis showed that, compared with the nonmigraine cohort, the adjusted hazard ratios in the migraine cohort were 3.30 (95% CI, 2.17-5.00) for tinnitus, 1.03 (95% CI, 0.17-6.41) for sensorineural hearing impairment, and 1.22 (95% CI, 0.53-2.83) for sudden deafness.

Conclusions and Relevance

In this population-based study, the risk of cochlear disorders, especially for tinnitus, was found to be significantly higher among patients with a history of migraines. This finding may support the presence and/or concept of "cochlear migraine."

Risks of tinnitus, sensorineural hearing impairment, and sudden deafness in patients with non-migraine headache

Tinnitus and hearing impairment are prevalent among headache patients. This study aims to investigate the risk of tinnitus, sensorineural hearing impairment, and sudden deafness in patients with non-migraine headache. Participants included 43 294 patients with non-migraine headache (non-migraine headache cohort) and 173 176 patients with no headache of any type (control cohort) frequency-matched with respect to 10-year age interval and sex from the Longitudinal Health Insurance Database 2005 of the Taiwan National Health Insurance Research Database. The mean age of the non-migraine headache cohort was 28.4 ± 14.9 years, and 58.5% of this cohort was male. The incidence rates of tinnitus, sensorineural hearing impairment, and sudden deafness were compared between cohorts using the Kaplan–Meier method with the log-rank test. A Cox proportional hazard model was used to examine the association of tinnitus, sensorineural hearing impairment, and sudden deafness with non-migraine headache, with adjustment for all covariates. The combined risk of either tinnitus, sensorineural hearing impairment, or sudden deafness was higher in the non-migraine headache cohort than in the control cohort (adjusted odds ratio [aHR], 2.73; 95% confidence interval [95% CI], 2.62–2.84; p < 0.0001). Subgroup analysis showed that patients in the non-migraine headache cohort were at significantly higher risk of developing tinnitus (aHR, 3.05; 95% CI, 2.91–3.19; p < 0.0001), sensorineural hearing impairment (aHR, 1.89; 95% CI, 1.74–2.05; p < 0.0001), and sudden deafness (aHR, 2.14; 95% CI, 1.77–2.59; p < 0.0001) than were controls. In this population-based study, the risks of tinnitus, sensorineural hearing impairment, and sudden deafness were found to be significantly higher in patients with non-migraine headache than in those without headache.

Tinnitus Is Associated with a Higher Risk of Benign Brain Tumors: A Nationwide, Population-Based Secondary Cohort Study of Young and Middle-Aged Adults

BACKGROUND

It remains unclear whether tinnitus is associated with a higher risk of benign or malignant brain tumors in humans. Therefore, the aim of this secondary study was to investigate the risk of brain tumors in adult with tinnitus using data from a nationwide health claims research database.

METHODS

Patients aged 20-50 years who were newly diagnosed with tinnitus were identified from the Taiwan's National Health Insurance Research Database and they served as the study cohort. A comparison cohort was formed by using patients without tinnitus from the same database with frequency matching (4: 1) by 10-year age interval and gender to the patients in the tinnitus cohort. Cox proportional hazards models were used to calculate the adjusted hazard ratios (AHR) for benign and malignant brain tumors in patients with tinnitus, adjusting for age, gender, and comorbidities.

RESULTS

There were 15,819 patients in the tinnitus cohort and 63,276 in the comparison cohort. A significantly higher proportion of patients with tinnitus had benign brain tumor (p = 0.003) and all 11 comorbid conditions (p < 0.001) compared to those without tinnitus. Cox proportional hazards regression analysis performed on the basis of age, gender, and the 11 comorbidities revealed that tinnitus was independently associated with a higher risk for benign brain tumor (AHR 1.65, 95% CI 1.24-2.20, p = 0.001) and but not with malignant brain tumors (AHR 1.66, 95% CI 0.93-2.94, p = 0.085).

CONCLUSIONS

Findings from this secondary cohort analysis indicated that tinnitus is associated with a higher risk of benign brain tumors.

The association between tinnitus and the risk of ischemic cerebrovascular disease in young and middle-aged patients: A secondary case-control analysis of a nationwide, population-based health claims database

Background

Tinnitus and ischemic cerebrovascular disease (ICVD) may share common pathophysiologic mechanisms. Nevertheless, no studies have investigated whether tinnitus is associated with a higher risk of ICVD. The aim of this study was to evaluate the risk of ICVD among young and middle-aged patients with tinnitus.

Methods

Using the Taiwan’s National Health Insurance Research Database, we identified 3,474 patients 20–45 years old with incident ICVD diagnosed between January 1, 2000 and December 31, 2010 and 17,370 controls, frequency matched on age interval, sex, and year of the index date. Risk of ICVD associated with tinnitus was assessed using multiple logistic regression analyses.

Results

Tinnitus was significantly associated with a higher risk of incident ICVD among young and middle-aged patients (adjusted odds ratio [OR] 1.66, 95% confidence interval [CI] 1.34–2.04), adjusting for sex, age, and comorbidities. In addition, sex-stratified analysis showed that the associations were significant in both male (adjusted OR 1.55, 95% CI 1.16–2.07) and female patients (adjusted OR 1.77, 95% CI 1.30–2.41). Furthermore, tinnitus was significantly associated with a higher risk of ICVD in the 20.0–29.9 years (adjusted OR 4.11, 95% CI 1.98–8.52) and 30.0–39.9 years (adjusted OR 2.19, 95% CI 1.57–3.05) age groups, but not in the 40.0–45.0 years age group.

Conclusions

Tinnitus could be a novel risk factor or clinical indicator for young ischemic stroke, and further investigations are warranted.

Effects of Spirulina on the functions and redox status of auditory system in senescence-accelerated prone-8 mice

To our knowledge, the effects of Spirulina platensis water extract (SP) on hearing function have not yet been reported. This study investigated the effects of SP on the function and redox status of the auditory system. Auditory brainstem responses and redox status were compared between two groups of 3-month-old senescence-accelerated prone-8 (SAMP8) mice: the control group was fed a normal diet, and the experimental group was fed a normal diet with oral supplementation of SP for 6 weeks. Compared with the control group, the experimental group had significantly lower hearing thresholds according to auditory brainstem responses measured using click sounds and 8-kHz tone burst sound stimulation at the end of this study. The experimental group had a shorter I-III interval of auditory brainstem responses with 16-kHz tone burst stimulation than the control group that was of borderline significance. Additionally, the experimental group had significantly higher mRNA expression of the superoxide dismutase and catalase genes in the cochlea and brainstem and significantly higher mRNA expression of the glutathione peroxidase gene in the cochlea. Further, the experimental group had significantly lower malondialdehyde levels in the cochlea and brainstem than the control group. However, tumor necrosis factor-α mRNA expression was not significantly different between the control and experimental groups. SP could decrease hearing degeneration in senescence-accelerated prone-8 mice possibly by increasing superoxide dismutase, catalase, and glutathione peroxidase gene expression and decreasing damage from oxidative stress in the cochlea and brainstem.

Expressions of ion co-transporter genes in salicylate-induced tinnitus and treatment effects of spirulina

BACKGROUND

Although the activity of tinnitus-related ion co-transporter are known, their mRNA expressions has seldom been reported. We aimed to investigate the mRNA expressions of tinnitus-related ion co-transporter genes, and treatment effects of Spirulina.

METHODS

The mRNA expressions of K(+)-Cl(-) co-transporter (KCC2) and Na-K-2Cl co-transporter 1 (NKCC1) genes in the cochlea and brain of mice were evaluated after tinnitus was induced by intraperitoneal injection of salicylate. The effects of spirulina water extract on these gene expressions were investigated.

RESULTS

Compared to the control group, the tinnitus scores increased significantly, however, the salicylate-induced tinnitus could be reduced significantly by spirulina water extract. The tinnitus group had higher of borderline significance mRNA expression of KCC2 gene in the cochlear, significantly higher in the temporal lobes and in the frontal lobes. Meanwhile, compared to the tinnitus group, the spirulina group had significantly lower mRNA expression of KCC2 gene in the cochlear, temporal lobes, frontal lobes and parahippocampus/hippocampus. However, the NKCC1 mRNA expression was not significantly different between three groups in the cochlea and these brain areas.

CONCLUSION

Salicylate-induced tinnitus might be associated with increased mRNA expression of KCC2 gene, but not with mRNA expressions of NKCC1 gene in the cochlear and some tinnitus-related brain areas. Spirulina reduced the expression of KCC2 genes in salicylate-induced tinnitus.