Research in hearing science is accelerating, and a wealth of data concerning auditory brainstem responses (ABR) in various animal models is published in peer-reviewed journals every year. Recently, we reviewed studies using ABR measurements in tinnitus rat models. We found significant discrepancies in the outcomes of these studies, some due to different research approaches and others due to different methodologies. Thus, the present work aimed to collect comprehensive information on all factors influencing ABR recordings in rats and compile recommendations on ABR data reporting. A questionnaire with queries about animal husbandry, transfer, handling, and the exact test conditions before, during, and after ABR recordings was sent to 125 researchers who published the relevant studies between 2015 and 2021. Eighteen researchers provided detailed answers on factors related to ABR measurements. Based on the analysis of the returned questionnaires, we identified three domains reflecting animal-, equipment-, and experiment-dependent factors that might influence the ABR outcome, thus requiring reporting in published research. The analysis of survey results led to the compilation of recommendations for reporting ABR outcomes supported by a literature review. Following these recommendations should facilitate comparative and meta-analyses of ABR results provided by various research groups.

Tinnitus is a subjective phantom sound perceived only by the affected person and a symptom of various auditory and non-auditory conditions. The majority of methods used in clinical and basic research for tinnitus diagnosis are subjective. To better understand tinnitus-associated changes in the auditory system, an objective technique measuring auditory sensitivity—the auditory brainstem responses (ABR)—has been suggested. Therefore, the present review aimed to summarize ABR’s features in a rat model during experimentally induced tinnitus. PubMed, Web of Science, Science Direct, and Scopus databanks were searched using Medical Subject Heading (MeSH) terms: auditory brainstem response, tinnitus, rat. The search identified 344 articles, and 36 of them were selected for the full-text analyses. The experimental protocols and results were evaluated, and the gained knowledge was synthesized. A high level of heterogeneity between the studies was found regarding all assessed areas. The most consistent finding of all studies was a reduction in the ABR wave I amplitude following exposure to noise and salicylate. Simultaneously, animals with salicylate-induced but not noise-induced tinnitus had an increased amplitude of wave IV. Furthermore, the present study identified a need to develop a consensus experimental ABR protocol applied in future tinnitus studies using the rat model.

Translational audiology research aims to transfer basic research findings into practical clinical applications. While animal studies provide essential knowledge for translational research, there is an urgent need to improve the reproducibility of data derived from these studies. Sources of variability in animal research can be grouped into three areas: animal, equipment, and experimental. To increase standardization in animal research, we developed universal recommendations for designing and conducting studies using a standard audiological method: auditory brainstem response (ABR). The recommendations are domain-specific and are intended to guide the reader through the issues that are important when applying for ABR approval, preparing for, and conducting ABR experiments. Better experimental standardization, which is the goal of these guidelines, is expected to improve the understanding and interpretation of results, reduce the number of animals used in preclinical studies, and improve the translation of knowledge to the clinic.

Background: Histamine is a widely distributed biogenic amine with multiple biological functions mediated by specific receptors that determine the local effects of histamine. This review aims to summarize the published findings on the expression and functional roles of histamine receptors in the inner ear and to identify potential research hotspots and gaps. Methods: A search of the electronic databases PubMed, Web of Science, and OVID EMBASE was performed using the keywords histamine, cochlea*, and inner ear. Of the 181 studies identified, 18 eligible publications were included in the full-text analysis. Results: All four types of histamine receptors were identified in the mammalian inner ear. The functional studies of histamine in the inner ear were mainly in vitro. Clinical evidence suggests that histamine and its receptors may play a role in Ménière’s disease, but the exact mechanism is not fully understood. The effects of histamine on hearing development remain unclear. Conclusions: Existing studies have successfully determined the expression of all four histamine receptors in the mammalian inner ear. However, further functional studies are needed to explore the potential of histamine receptors as targets for the treatment of hearing and balance disorders.

Translational research is a process that focuses on advancing basic research-based clinical solutions and is characterized by a structured process accelerating the implementation of scientific discoveries in healthcare. Translational research originated in oncology but has spread to other disciplines in recent decades. A translational project may refer to pharmacological research, the development of non-pharmacological therapies, or to disease monitoring processes. Its stages are divided into basic research focused on the clinical problem (T0), testing the developed means in humans (T1), conducting trials with patients (T2), implementation and dissemination of successful approaches (T3), and improving community health (T4). Many audiological studies are translational in nature. Accordingly, this scoping review aimed to evaluate the use of the terms “translational audiology” and “translational research in audiology” in the literature and examine the goals of the identified studies. PubMed and Web of Science search identified only two publications meeting the search criteria. We conclude that identifying translational audiological studies in the literature may be hampered by the lack of use of the terms “translational audiology” or “translational research”. We suggest using these terms when describing translational work in audiology, with a view to facilitating the identification of this type of research and credit it appropriately.

Background: The ionotropic glutamate receptor AMPA (AMPAR) mediates fast excitatory synaptic transmission and regulates synaptic strength in various parts of the CNS. Emotional challenges can affect these processes by influencing AMPAR levels and localization via stress hormones, resulting, e.g., in behavioral changes. AMPARs are essential for auditory processing, but their response to stress hormones in the central or peripheral auditory system remains poorly understood. Therefore, this scoping review examines the effects of corticosterone (CORT), a primary stress hormone in rodents, on AMPA receptor levels and localization in the rodent nervous system and considers potential implications for the auditory system. Methods: We systematically searched PubMed, Web of Science, and OVID EMBASE using MeSH terms related to AMPA receptors and corticosterone. Studies were screened based on predefined inclusion criteria, including original research published in English that focused on AMPA receptor subunits (e.g., GluR1-4, GluA1-4, Gria1-4). Of 288 articles screened, 17 met the criteria for final analysis. Results: No reports were found regarding CORT action in the auditory system. Three main experimental models used in the included research were identified: neuronal cultures, isolated tissue cultures, and animal models. Generally, short-term CORT exposure increases AMPAR surface localization and mobility in neuronal cultures, especially in the hippocampus and prefrontal cortex. However, results from animal models were inconsistent due to variations in experimental design and other factors. The isolated tissue study did not provide sufficient data for clear conclusions. Conclusions: Variability in experimental models limits our ability to draw definitive conclusions about the effects of CORT on AMPARs across different regions of the nervous system. The differences in live animal studies highlight the need for standardized methods and reporting. Since AMPARs play a crucial role in auditory processing, CORT-induced changes in neuronal cultures may occur in the auditory system. Further research is needed to explore the specific responses of AMPAR subunits and how stress hormones may influence auditory disorders, which could help identify potential treatment strategies.