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Gill NB, Dowker-Key PD, Hedrick M, Bettaieb A. Unveiling the Role of Oxidative Stress in Cochlear Hair Cell Death: Prospective Phytochemical Therapeutics against Sensorineural Hearing Loss. Int J Mol Sci 2024; 25:4272. [PMID: 38673858 PMCID: PMC11050722 DOI: 10.3390/ijms25084272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/31/2024] [Accepted: 04/07/2024] [Indexed: 04/28/2024] Open
Abstract
Hearing loss represents a multifaceted and pervasive challenge that deeply impacts various aspects of an individual's life, spanning psychological, emotional, social, and economic realms. Understanding the molecular underpinnings that orchestrate hearing loss remains paramount in the quest for effective therapeutic strategies. This review aims to expound upon the physiological, biochemical, and molecular aspects of hearing loss, with a specific focus on its correlation with diabetes. Within this context, phytochemicals have surfaced as prospective contenders in the pursuit of potential adjuvant therapies. These compounds exhibit noteworthy antioxidant and anti-inflammatory properties, which hold the potential to counteract the detrimental effects induced by oxidative stress and inflammation-prominent contributors to hearing impairment. Furthermore, this review offers an up-to-date exploration of the diverse molecular pathways modulated by these compounds. However, the dynamic landscape of their efficacy warrants recognition as an ongoing investigative topic, inherently contingent upon specific experimental models. Ultimately, to ascertain the genuine potential of phytochemicals as agents in hearing loss treatment, a comprehensive grasp of the molecular mechanisms at play, coupled with rigorous clinical investigations, stands as an imperative quest.
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Affiliation(s)
- Nicholas B. Gill
- Department of Nutrition, University of Tennessee Knoxville, Knoxville, TN 37996-0840, USA
| | - Presley D. Dowker-Key
- Department of Nutrition, University of Tennessee Knoxville, Knoxville, TN 37996-0840, USA
| | - Mark Hedrick
- Department of Audiology & Speech Pathology, The University of Tennessee Health Science Center, Knoxville, TN 37996-0240, USA
| | - Ahmed Bettaieb
- Department of Nutrition, University of Tennessee Knoxville, Knoxville, TN 37996-0840, USA
- Graduate School of Genome Science and Technology, University of Tennessee Knoxville, Knoxville, TN 37996-0840, USA
- Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee Knoxville, Knoxville, TN 37996-0840, USA
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Wu Y, Zhang J, Liu Q, Miao Z, Chai R, Chen W. Development of Chinese herbal medicine for sensorineural hearing loss. Acta Pharm Sin B 2024; 14:455-467. [PMID: 38322328 PMCID: PMC10840432 DOI: 10.1016/j.apsb.2023.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 09/16/2023] [Accepted: 10/24/2023] [Indexed: 02/08/2024] Open
Abstract
According to the World Health Organization's world report on hearing, nearly 2.5 billion people worldwide will suffer from hearing loss by 2050, which may contribute to a severe impact on individual life quality and national economies. Sensorineural hearing loss (SNHL) occurs commonly as a result of noise exposure, aging, and ototoxic drugs, and is pathologically characterized by the impairment of mechanosensory hair cells of the inner ear, which is mainly triggered by reactive oxygen species accumulation, inflammation, and mitochondrial dysfunction. Though recent advances have been made in understanding the ability of cochlear repair and regeneration, there are still no effective therapeutic drugs for SNHL. Chinese herbal medicine which is widely distributed and easily accessible in China has demonstrated a unique curative effect against SNHL with higher safety and lower cost compared with Western medicine. Herein we present trends in research for Chinese herbal medicine for the treatment of SNHL, and elucidate their molecular mechanisms of action, to pave the way for further research and development of novel effective drugs in this field.
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Affiliation(s)
- Yunhao Wu
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China
| | - Jingwen Zhang
- Department of Otolaryngology-Head and Neck, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510120, China
| | - Qiuping Liu
- Department of Otolaryngology-Head and Neck Surgery, Affiliated Hospital of Jiangnan University, Wuxi 214000, China
| | - Zhuang Miao
- Department of Otolaryngology-Head and Neck Surgery, Affiliated Hospital of Jiangnan University, Wuxi 214000, China
| | - Renjie Chai
- State Key Laboratory of Bioelectronics, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing 210096, China
- Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 610000, China
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Science, Beijing 100085, China
- Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China
| | - Wenyong Chen
- Department of Otolaryngology-Head and Neck, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou 510120, China
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Hu S, Sun Q, Xu F, Jiang N, Gao J. Age-related hearing loss and its potential drug candidates: a systematic review. Chin Med 2023; 18:121. [PMID: 37730634 PMCID: PMC10512576 DOI: 10.1186/s13020-023-00825-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 08/25/2023] [Indexed: 09/22/2023] Open
Abstract
BACKGROUND Age-related hearing loss (ARHL) is one of the main illnesses afflicting the aged population and has a significant negative impact on society, economy, and health. However, there is presently no appropriate therapeutic treatment of ARHL due to the absence of comprehensive trials. OBJECTIVES The goal of this review is to systematically evaluate and analyze recent statistics on the pathologic classifications, risk factors, treatment strategies, and drug candidates of ARHL, including that from traditional Chinese medicine (TCM), to provide potential new approaches for preventing and treating ARHL. METHODS Literature related to ARHL was conducted in databases such as PubMed, WOS, China National Knowledge Infrastructure (CNKI), and Wanfang from the establishment of the database to Jan, 2023. The pathology, causal factor, pathophysiological mechanism, treatment strategy, and the drug candidate of ARHL were extracted and pooled for synthesis. RESULTS Many hypotheses about the etiology of ARHL are based on genetic and environmental elements. Most of the current research on the pathology of ARHL focuses on oxidative damage, mitochondrial dysfunction, inflammation, cochlear blood flow, ion homeostasis, etc. In TCM, herbs belonging to the kidney, lung, and liver meridians exhibit good hearing protection. Seven herbs belonging to the kidney meridian, 9 belonging to the lung meridian, and 4 belonging to the liver meridian were ultimately retrieved in this review, such as Polygonum multiflorum Thunb., Panax ginseng C.A. Mey, and Pueraria lobata (Willd.) Ohwi. Their active compounds, 2,3,4',5-Tetrahydroxystilbene-2-O-D-glucoside, ginsenoside Rb1, and puerarin, may act as the molecular substance for their anti-ARHL efficacy, and show anti-oxidative, neuroprotective, anti-inflammatory, anti-apoptotic, or mitochondrial protective effects. CONCLUSION Anti-oxidants, modulators of mitochondrial function, anti-inflammation agents, vasodilators, K+ channel openers, Ca2+ channel blockers, JNK inhibitors, and nerve growth factors/neurotrophic factors all contribute to hearing protection, and herbs are an important source of potential anti-ARHL drugs.
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Affiliation(s)
- Shiyu Hu
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, 310053, Zhejiang, People's Republic of China
| | - Qingru Sun
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, 310053, Zhejiang, People's Republic of China
| | - Fei Xu
- School of Medical Technology and Information Engineering, Zhejiang Chinese Medical University, Hangzhou, 310053, Zhejiang, People's Republic of China
| | - Ninghua Jiang
- Department of Pharmacy, The Second Affiliated Hospital of Jiaxing University, Jiaxing, 314000, Zhejiang, People's Republic of China
| | - Jianli Gao
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, 310053, Zhejiang, People's Republic of China.
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Tureček R, Melichar A, Králíková M, Hrušková B. The role of GABA B receptors in the subcortical pathways of the mammalian auditory system. Front Endocrinol (Lausanne) 2023; 14:1195038. [PMID: 37635966 PMCID: PMC10456889 DOI: 10.3389/fendo.2023.1195038] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 07/24/2023] [Indexed: 08/29/2023] Open
Abstract
GABAB receptors are G-protein coupled receptors for the inhibitory neurotransmitter GABA. Functional GABAB receptors are formed as heteromers of GABAB1 and GABAB2 subunits, which further associate with various regulatory and signaling proteins to provide receptor complexes with distinct pharmacological and physiological properties. GABAB receptors are widely distributed in nervous tissue, where they are involved in a number of processes and in turn are subject to a number of regulatory mechanisms. In this review, we summarize current knowledge of the cellular distribution and function of the receptors in the inner ear and auditory pathway of the mammalian brainstem and midbrain. The findings suggest that in these regions, GABAB receptors are involved in processes essential for proper auditory function, such as cochlear amplifier modulation, regulation of spontaneous activity, binaural and temporal information processing, and predictive coding. Since impaired GABAergic inhibition has been found to be associated with various forms of hearing loss, GABAB dysfunction could also play a role in some pathologies of the auditory system.
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Affiliation(s)
- Rostislav Tureček
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czechia
| | - Adolf Melichar
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czechia
- Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Michaela Králíková
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czechia
| | - Bohdana Hrušková
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czechia
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Ma X, Guo J, Fu Y, Shen C, Jiang P, Zhang Y, Zhang L, Yu Y, Fan J, Chai R. G protein-coupled receptors in cochlea: Potential therapeutic targets for hearing loss. Front Mol Neurosci 2022; 15:1028125. [PMID: 36311029 PMCID: PMC9596917 DOI: 10.3389/fnmol.2022.1028125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 09/21/2022] [Indexed: 11/29/2022] Open
Abstract
The prevalence of hearing loss-related diseases caused by different factors is increasing worldwide year by year. Currently, however, the patient’s hearing loss has not been effectively improved. Therefore, there is an urgent need to adopt new treatment measures and treatment techniques to help improve the therapeutic effect of hearing loss. G protein-coupled receptors (GPCRs), as crucial cell surface receptors, can widely participate in different physiological and pathological processes, particularly play an essential role in many disease occurrences and be served as promising therapeutic targets. However, no specific drugs on the market have been found to target the GPCRs of the cochlea. Interestingly, many recent studies have demonstrated that GPCRs can participate in various pathogenic process related to hearing loss in the cochlea including heredity, noise, ototoxic drugs, cochlear structure, and so on. In this review, we comprehensively summarize the functions of 53 GPCRs known in the cochlea and their relationships with hearing loss, and highlight the recent advances of new techniques used in cochlear study including cryo-EM, AI, GPCR drug screening, gene therapy vectors, and CRISPR editing technology, as well as discuss in depth the future direction of novel GPCR-based drug development and gene therapy for cochlear hearing loss. Collectively, this review is to facilitate basic and (pre-) clinical research in this area, and provide beneficial help for emerging GPCR-based cochlear therapies.
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Affiliation(s)
- Xiangyu Ma
- State Key Laboratory of Bioelectronics, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Southeast University, Nanjing, China
| | - Jiamin Guo
- State Key Laboratory of Bioelectronics, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Southeast University, Nanjing, China
| | - Yaoyang Fu
- Department of Psychiatry, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Cangsong Shen
- College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Pei Jiang
- State Key Laboratory of Bioelectronics, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Southeast University, Nanjing, China
| | - Yuan Zhang
- Jiangsu Provincial Key Medical Discipline (Laboratory), Department of Otolaryngology Head and Neck Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
- Research Institute of Otolaryngology, Nanjing, China
| | - Lei Zhang
- Department of Otorhinolaryngology, Head and Neck Surgery, The Second Hospital of Anhui Medical University, Hefei, China
| | - Yafeng Yu
- First Affiliated Hospital of Soochow University, Soochow, China
- *Correspondence: Yafeng Yu,
| | - Jiangang Fan
- Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Jiangang Fan,
| | - Renjie Chai
- State Key Laboratory of Bioelectronics, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, Advanced Institute for Life and Health, Southeast University, Nanjing, China
- Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
- Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing, China
- Renjie Chai,
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Medical Therapy of Hearing Impairment and Tinnitus with Chinese Medicine: An Overview. Chin J Integr Med 2022:10.1007/s11655-022-3678-5. [PMID: 35419727 DOI: 10.1007/s11655-022-3678-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Indexed: 11/03/2022]
Abstract
The current review gives a comprehensive overview of the recent development in Chinese medicine (CM) for treating several kinds of acquired nerve deafness and tinnitus, as well as links the traditional principle to well-established pharmacological mechanisms for future research. To date, about 24 herbal species and 40 related ingredients used in CM to treat hearing loss and tinnitus are reported for the treatment of endocochlear potential, endolymph growth, lowering toxic and provocative substance aggregation, inhibiting sensory cell death, and retaining sensory transfer. However, there are a few herbal species that can be used for medicinal purposes. Nevertheless, clinical studies have been hampered by a limited population sample, a deficiency of a suitable control research group, or contradictory results. Enhanced cochlear blood flow, antiinflammatory antioxidant, neuroprotective effects, and anti-apoptotic, as well as multi-target approach on different auditory sections of the inner ear, are all possible benefits of CM medications. There are numerous unknown natural products for aural ailment and tinnitus identified in CM that are expected to be examined in the future utilizing various aural ailment models and processes.
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Xu B, Li J, Chen X, Kou M. Puerarin attenuates cisplatin-induced apoptosis of hair cells through the mitochondrial apoptotic pathway. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2022; 1869:119208. [PMID: 35032475 DOI: 10.1016/j.bbamcr.2021.119208] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 12/14/2021] [Accepted: 12/28/2021] [Indexed: 06/14/2023]
Abstract
Puerarin, one of the main components of Pueraria lobata, has been reported to possess a wide range of pharmacological activities, including anti-inflammatory, antioxidative and anti-apoptotic effects. However, the role of puerarin in ototoxic drug-induced hair cell injury has not been well characterized. This study explored whether puerarin protects against cisplatin-induced hair cell damage and its potential mechanisms. The viability of puerarin-treated HEI-OC1 cells was assessed by CCK8 assay. Reactive oxygen species (ROS) was estimated with flow cytometric analysis using Cellrox Green fluorescent probe. Apoptosis-related protein levels were detected by western blot analysis. Immunostaining of the organ of Corti was performed to determine mice cochlear hair cell survival. Our results showed that puerarin improved cell viability and suppressed apoptosis in the cisplatin-damaged HEI-OC1 cells and cochlear hair cells. Mechanistic studies revealed that puerarin attenuated mitochondrial apoptosis pathway by regulating apoptotic related proteins, such as Bax and cleaved caspase-3, and attenuated ROS accumulation after cisplatin damage. Moreover, puerarin was involved in regulating the Akt pathway in HEI-OC1 cells in response to cisplatin. Our results demonstrated that puerarin administration decreased the sensitivity to apoptosis dependent on the mitochondrial apoptotic pathway by reducing ROS generation, which could be used as a new protective agent against cisplatin-induced ototoxicity.
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Affiliation(s)
- Bingqiang Xu
- Department of Radiology, Shaanxi Provincial People's Hospital, No.256, You Yi West Street, Xi'an 710068, PR China
| | - Juedan Li
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an 710004, PR China; Department of General Dentistry and Emergency Room, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an 710004, PR China
| | - Xiaolong Chen
- Department of Radiology, Shaanxi Provincial People's Hospital, No.256, You Yi West Street, Xi'an 710068, PR China
| | - Mingqing Kou
- Department of Radiology, Shaanxi Provincial People's Hospital, No.256, You Yi West Street, Xi'an 710068, PR China.
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Gittleman SN, Le Prell CG, Hammill TL. Octave band noise exposure: Laboratory models and otoprotection efforts. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2019; 146:3800. [PMID: 31795706 PMCID: PMC7195864 DOI: 10.1121/1.5133393] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 05/21/2019] [Indexed: 05/05/2023]
Abstract
With advances in the understanding of mechanisms of noise injury, the past 30 years have brought numerous efforts to identify drugs that prevent noise-induced hearing loss (NIHL). The diverse protocols used across investigations have made comparisons across drugs difficult. A systematic review of the literature by Hammill [(2017). Doctoral thesis, The University of Texas at Austin] identified original reports of chemical interventions to prevent or treat hearing loss caused by noise exposure. An initial search returned 3492 articles. After excluding duplicate articles and articles that did not meet the systematic review inclusion criteria, a total of 213 studies published between 1977 and 2016 remained. Reference information, noise exposure parameters, species, sex, method of NIHL assessment, and pharmaceutical intervention details for these 213 studies were entered into a database. Frequency-specific threshold shifts in control animals (i.e., in the absence of pharmaceutical intervention) are reported here. Specific patterns of hearing loss as a function of species and noise exposure parameters are provided to facilitate the selection of appropriate pre-clinical models. The emphasis of this report is octave band noise exposure, as this is one of the most common exposure protocols across pharmacological otoprotection studies.
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Affiliation(s)
- Sarah N Gittleman
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, Texas 75080, USA
| | - Colleen G Le Prell
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, Texas 75080, USA
| | - Tanisha L Hammill
- Department of Defense, Defense Health Agency, Falls Church, Virginia 22042, USA
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Castañeda R, Natarajan S, Jeong SY, Hong BN, Kang TH. Traditional oriental medicine for sensorineural hearing loss: Can ethnopharmacology contribute to potential drug discovery? JOURNAL OF ETHNOPHARMACOLOGY 2019; 231:409-428. [PMID: 30439402 DOI: 10.1016/j.jep.2018.11.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 11/06/2018] [Accepted: 11/06/2018] [Indexed: 06/09/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE In Traditional Oriental Medicine (TOM), the development of hearing pathologies is related to an inadequate nourishment of the ears by the kidney and other organs involved in regulation of bodily fluids and nutrients. Several herbal species have historically been prescribed for promoting the production of bodily fluids or as antiaging agents to treat deficiencies in hearing. AIM OF REVIEW The prevalence of hearing loss has been increasing in the last decade and is projected to grow considerably in the coming years. Recently, several herbal-derived products prescribed in TOM have demonstrated a therapeutic potential for acquired sensorineural hearing loss and tinnitus. Therefore, the aims of this review are to provide a comprehensive overview of the current known efficacy of the herbs used in TOM for preventing different forms of acquired sensorineural hearing loss and tinnitus, and associate the traditional principle with the demonstrated pharmacological mechanisms to establish a solid foundation for directing future research. METHODS The present review collected the literature related to herbs used in TOM or related compounds on hearing from Chinese, Korean, and Japanese herbal classics; library catalogs; and scientific databases (PubMed, Scopus, Google Scholar; and Science Direct). RESULTS This review shows that approximately 25 herbal species and 40 active compounds prescribed in TOM for hearing loss and tinnitus have shown in vitro or in vivo beneficial effects for acquired sensorineural hearing loss produced by noise, aging, ototoxic drugs or diabetes. The inner ear is highly vulnerable to ischemia and oxidative damage, where several TOM agents have revealed a direct effect on the auditory system by normalizing the blood supply to the cochlea and increasing the antioxidant defense in sensory hair cells. These strategies have shown a positive impact on maintaining the inner ear potential, sustaining the production of endolymph, reducing the accumulation of toxic and inflammatory substances, preventing sensory cell death and preserving sensory transmission. There are still several herbal species with demonstrated therapeutic efficacy whose mechanisms have not been deeply studied and others that have been traditionally used in hearing loss but have not been tested experimentally. In clinical studies, Ginkgo biloba, Panax ginseng, and Astragalus propinquus have demonstrated to improve hearing thresholds in patients with sensorineural hearing loss and alleviated the symptoms of tinnitus. However, some of these clinical studies have been limited by small sample sizes, lack of an adequate control group or contradictory results. CONCLUSIONS Current therapeutic strategies have proven that the goal of the traditional oriental medicine principle of increasing bodily fluids is a relevant approach for reducing the development of hearing loss by improving microcirculation in the blood-labyrinth barrier and increasing cochlear blood flow. The potential benefits of TOM agents expand to a multi-target approach on different auditory structures of the inner ear related to increased cochlear blood flow, antioxidant, anti-inflammatory, anti-apoptotic and neuroprotective activities. However, more research is required, given the evidence is very limited in terms of the mechanism of action at the preclinical in vivo level and the scarce number of clinical studies published.
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Affiliation(s)
- Rodrigo Castañeda
- Graduate School of Biotechnology, Kyung Hee University, Republic of Korea; Department of Oriental Medicine Biotechnology, College of Life Sciences, Kyung Hee University, Global Campus, Gyeonggi, Republic of Korea.
| | - Sathishkumar Natarajan
- Graduate School of Biotechnology, Kyung Hee University, Republic of Korea; Department of Oriental Medicine Biotechnology, College of Life Sciences, Kyung Hee University, Global Campus, Gyeonggi, Republic of Korea.
| | - Seo Yule Jeong
- Graduate School of Biotechnology, Kyung Hee University, Republic of Korea; Department of Oriental Medicine Biotechnology, College of Life Sciences, Kyung Hee University, Global Campus, Gyeonggi, Republic of Korea.
| | - Bin Na Hong
- Graduate School of Biotechnology, Kyung Hee University, Republic of Korea.
| | - Tong Ho Kang
- Graduate School of Biotechnology, Kyung Hee University, Republic of Korea; Department of Oriental Medicine Biotechnology, College of Life Sciences, Kyung Hee University, Global Campus, Gyeonggi, Republic of Korea.
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