RESUMO
Sensorineural hearing loss is one of the most prevalent sensory deficits. Spiral ganglion neurons (SGNs) exhibit very limited regeneration capacity and their degeneration leads to profound hearing loss. Mesenchymal stem cell-derived small extracellular vesicles (MSC-sEV) have been demonstrated to repair tissue damage in various degenerative diseases. However, the effects of MSC-sEV on SGN degeneration remain unclear. In this study, we investigated the efficacy of MSC-sEV for protection against ouabain-induced SGN degeneration. MSC-sEV were derived from rat bone marrow and their components related to neuron growth were determined by proteomic analysis. In primary culture SGNs, MSC-sEV significantly promoted neurite growth and growth cone development. The RNA-Seq analysis of SGNs showed that enriched pathways include neuron development and axon regeneration, consistent with proteomics. In ouabain induced SGN degeneration rat model, MSC-sEV administration via intratympanic injection significantly enhanced SGN survival and mitigated hearing loss. Furthermore, after ouabain treatment, SGNs displayed evident signs of apoptosis, including nuclei condensation and fragmentation, with numerous cells exhibiting TUNEL-positive. However, administration of MSC-sEV effectively decreased the number of TUNEL-positive cells and reduced caspase-3 activation. In conclusion, our findings demonstrate the potential of MSC-sEV in preventing SGN degeneration and promoting neural growth, suggesting intratympanic injection of MSC-sEV is a specific and efficient strategy for neural hearing loss.
Assuntos
Vesículas Extracelulares , Injeção Intratimpânica , Células-Tronco Mesenquimais , Ouabaína , Ratos Sprague-Dawley , Gânglio Espiral da Cóclea , Animais , Gânglio Espiral da Cóclea/efeitos dos fármacos , Gânglio Espiral da Cóclea/patologia , Vesículas Extracelulares/metabolismo , Células-Tronco Mesenquimais/metabolismo , Células-Tronco Mesenquimais/efeitos dos fármacos , Ouabaína/farmacologia , Ratos , Masculino , Apoptose/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurônios/patologia , Neurônios/metabolismo , Degeneração Neural/patologia , Células Cultivadas , Modelos Animais de Doenças , Perda Auditiva Neurossensorial/patologiaRESUMO
Cisplatin is a chemotherapeutic agent widely used to treat solid tumors. However, it can also be highly ototoxic, resulting in high-frequency hearing loss. Cisplatin causes degeneration of hair cells (HCs) and spiral ganglion neurons (SGNs) in the inner ear, which are essential components of the hearing process and cannot be regenerated in mammals. As the affected cells primarily die by apoptosis, we tested several anti-apoptotic small molecules to protect these cells from drug-induced toxicity. We found that the general caspase inhibitor Emricasan could significantly counteract the toxic effects of cisplatin in House Ear Institute-Organ of Corti 1 (HEI-OC1) cells, phoenix auditory cells, and primary SGNs. Importantly, the anti-cytotoxic effect in neuronal cells was even more pronounced than the effect of sodium thiosulfate (STS), which is currently the only approved prevention option for cisplatin-induced ototoxicity. Finally, we tested the protective effect of Emricasan treatment in the context of another ototoxic drug, i.e., the aminoglycoside antibiotic neomycin, and again found a significant increase in cell viability when the cultures were co-treated with Emricasan. These results suggest a promising strategy to prevent ototoxicity in patients by temporarily blocking the apoptotic pathway when applying cisplatin or aminoglycoside antibiotics. KEY MESSAGES: Anti-apoptotic small molecules can reduce cisplatin-induced toxicity. Emricasan can effectively exert its anti-apoptotic effect on cochlear cells. Strong protection from cisplatin- and neomycin-induced cytotoxicity with Emricasan. Sodium thiosulfate and Emricasan provide similar protective effects to cisplatin-treated cells. Emricasan is more potent than sodium thiosulfate in reducing neomycin-induced cytotoxicity.
Assuntos
Inibidores de Caspase , Cisplatino , Neomicina , Cisplatino/efeitos adversos , Cisplatino/toxicidade , Cisplatino/farmacologia , Animais , Neomicina/farmacologia , Neomicina/toxicidade , Inibidores de Caspase/farmacologia , Camundongos , Apoptose/efeitos dos fármacos , Cóclea/efeitos dos fármacos , Cóclea/citologia , Sobrevivência Celular/efeitos dos fármacos , Células Ciliadas Auditivas/efeitos dos fármacos , Gânglio Espiral da Cóclea/efeitos dos fármacos , Ototoxicidade/etiologia , Ototoxicidade/prevenção & controle , Antineoplásicos/farmacologia , Antineoplásicos/toxicidade , Linhagem Celular , Células CultivadasRESUMO
Neural response properties that typify primary sensory afferents are critical to fully appreciate because they establish and, ultimately represent, the fundamental coding design used for higher-level processing. Studies illuminating the center-surround receptive fields of retinal ganglion cells, for example, were ground-breaking because they determined the foundation of visual form detection. For the auditory system, a basic organizing principle of the spiral ganglion afferents is their extensive electrophysiological heterogeneity establishing diverse intrinsic firing properties in neurons throughout the spiral ganglion. Moreover, these neurons display an impressively large array of neurotransmitter receptor types that are responsive to efferent feedback. Thus, electrophysiological diversity and its neuromodulation are a fundamental encoding mechanism contributed by the primary afferents in the auditory system. To place these features into context, we evaluated the effects of hyperpolarization and cAMP on threshold level as indicators of overall afferent responsiveness in CBA/CaJ mice of either sex. Hyperpolarization modified threshold gradients such that distinct voltage protocols could shift the relationship between sensitivity and stimulus input to reshape resolution. This resulted in an "accordion effect" that appeared to stretch, compress, or maintain responsivity across the gradient of afferent thresholds. cAMP targeted threshold and kinetic shifts to rapidly adapting neurons, thus revealing multiple cochleotopic properties that could potentially be independently regulated. These examples of dynamic heterogeneity in primary auditory afferents not only have the capacity to shift the range, sensitivity, and resolution, but to do so in a coordinated manner that appears to orchestrate changes with a seemingly unlimited repertoire.SIGNIFICANCE STATEMENT How do we discriminate the more nuanced qualities of the sound around us? Beyond the basics of pitch and loudness, aspects, such as pattern, distance, velocity, and location, are all attributes that must be used to encode acoustic sensations effectively. While higher-level processing is required for perception, it would not be unexpected if the primary auditory afferents optimized receptor input to expedite neural encoding. The findings reported herein are consistent with this design. Neuromodulation compressed, expanded, shifted, or realigned intrinsic electrophysiological heterogeneity to alter neuronal responses selectively and dynamically. This suggests that diverse spiral ganglion phenotypes provide a rich substrate to support an almost limitless array of coding strategies within the first neural element of the auditory pathway.
Assuntos
Potenciais de Ação/fisiologia , Gânglio Espiral da Cóclea/fisiologia , Potenciais de Ação/efeitos dos fármacos , Animais , AMP Cíclico/farmacologia , Feminino , Masculino , Camundongos , Camundongos Endogâmicos CBA , Técnicas de Cultura de Órgãos , Gânglio Espiral da Cóclea/citologia , Gânglio Espiral da Cóclea/efeitos dos fármacosRESUMO
In the cochlea, non-sensory supporting cells are directly connected to adjacent supporting cells via gap junctions that allow the exchange of small molecules. We have previously shown that the pharmacological regulation of gap junctions alleviates cisplatin (CDDP)-induced ototoxicity in animal models. In this study, we aimed to identify specific small molecules that pass through gap junctions in the process of CDDP-induced auditory cell death and suggest new mechanisms to prevent hearing loss. We found that the cyclic adenosine monophosphate (cAMP) inducer forskolin (FSK) significantly attenuated CDDP-induced auditory cell death in vitro and ex vivo. The activation of cAMP/PKA/CREB signaling was observed in organ of Corti primary cells treated with FSK, especially in supporting cells. Co-treatment with gap junction enhancers such as all-trans retinoic acid (ATRA) and quinoline showed potentiating effects with FSK on cell survival via activation of cAMP/PKA/CREB. In vivo, the combination of FSK and ATRA was more effective for preventing ototoxicity compared to either single treatment. Our study provides the new insight that gap junction-mediated intercellular communication of cAMP may prevent CDDP-induced ototoxicity.
Assuntos
Comunicação Celular , Cisplatino/efeitos adversos , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , AMP Cíclico/metabolismo , Junções Comunicantes/metabolismo , Ototoxicidade/metabolismo , Transdução de Sinais , Células A549 , Animais , Comunicação Celular/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Colforsina/farmacologia , Colforsina/uso terapêutico , Conexina 26/metabolismo , Junções Comunicantes/efeitos dos fármacos , Células Ciliadas Auditivas/metabolismo , Células HeLa , Perda Auditiva/induzido quimicamente , Perda Auditiva/tratamento farmacológico , Perda Auditiva/prevenção & controle , Humanos , Camundongos , Substâncias Protetoras/farmacologia , Ratos Sprague-Dawley , Transdução de Sinais/efeitos dos fármacos , ATPase Trocadora de Sódio-Potássio/metabolismo , Gânglio Espiral da Cóclea/efeitos dos fármacos , Gânglio Espiral da Cóclea/patologia , Tretinoína/farmacologia , Tretinoína/uso terapêuticoRESUMO
OBJECTIVES: The aim of this study was to assess whether nivolumab is ototoxic in rats and whether this ototoxicity is dose-dependent. MATERIALS AND METHODS: Twelve rats were divided into two groups: Group 1 (control group, 6 rats, 12 ears) received intraperitoneal saline for 14 days. Group 2 (study group, 6 rats, 12 ears) and received two doses of 3 mg/kg intraperitoneal nivolumab within 14 days. Auditory brainstem responses (ABRs) were performed preoperatively and 4 and 8 weeks postoperatively. We compared between the groups, morphologic appearance of spiral ganglion cells and organ of Corti and density of spiral ganglion cells (measured with conventional light microscope connected to a personal computer). RESULTS: In our control group, both spiral ganglion and organ of corti had a normal morphological appearance. In our study group, spiral ganglion cells had a normal morphological appearance. However, some sections showed possibly mild degenerative changes in the organ of corti. Of 12 samples in the study group, four had a significant loss of density of spiral ganglion cells compared to the control group. The baseline ABR thresholds did not significantly differ between the groups (p=0.713). There was no statistically significant difference between the groups regarding ABR thresholds at week 4 (p=0.347). However, a statistically significant difference was observed in the ABR thresholds at week 8 (p=0.045). CONCLUSION: The results of our study showed that nivolumab treatment has ototoxic effects. Based on our results, we recommend monitoring the changes in the hearing ability of chemotherapy patients.
Assuntos
Antineoplásicos Imunológicos/toxicidade , Nivolumabe/toxicidade , Ototoxicidade/etiologia , Animais , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Órgão Espiral/efeitos dos fármacos , Ototoxicidade/patologia , Ratos , Gânglio Espiral da Cóclea/efeitos dos fármacosRESUMO
Actinomycin-D (Act-D) is a highly effective chemotherapeutic agent that induces apoptosis in systemic tissues. Act-D combined with other chemotherapeutic agents exhibits ototoxic effects and causes hearing impairment. To investigate the potential toxic effects of Act-D in the inner ear, we treated cochlear organotypic cultures with varying concentrations of Act-D for different durations. For the first time, we found that Act-D specifically induced HC loss and apoptosis in a dose- and time-dependent manner but not neuronal degeneration. Co-treatment with benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (z-VAD-FMK), a pan cysteine protease inhibitor, significantly reduced HC loss and apoptosis induced by Act-D, indicating increased cell survival. Taken together, Act-D exposure has ototoxic effects on the auditory system, while z-VAD-FMK prevents Act-D-induced hair cell damage.
Assuntos
Clorometilcetonas de Aminoácidos/farmacologia , Dactinomicina/toxicidade , Células Ciliadas Auditivas/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Caspase 3/metabolismo , Inibidores de Caspase , Sobrevivência Celular/efeitos dos fármacos , Nervo Coclear/efeitos dos fármacos , Cultura , Inibidores de Cisteína Proteinase/farmacologia , Humanos , Recém-Nascido , Órgão Espiral/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio , Gânglio Espiral da Cóclea/efeitos dos fármacosRESUMO
INTRODUCTION: In recent years, the preservation of residual hearing has become a major factor in patients undergoing cochlear implantation (CI). In studies attempting to pharmaceutically improve hearing preservation rates, glucocorticoids (GCs) applied perioperatively in many institutions have emerged as a promising treatment regimen. Although dexamethasone is most commonly used and has been applied successfully by various research groups, recently pharmacological properties have been reported to be relatively unsuitable for topical delivery to the inner ear. Consequently other glucocorticoids merit further evaluation. The aim of this study was therefore to evaluate the otoprotective effects of the topical application of a sustained-release triamcinolone acetonide (TAAC) hydrogel in CI with hearing preservation. METHODS: Normal-hearing pigmented guinea pigs were randomized into a group receiving a single dose of a 6% TAAC poloxamer 407 hydrogel, a group receiving a 30% TAAC hydrogel and a control group. All hydrogel applications were performed 1 day prior to CI. After a cochleostomy was drilled, a specifically designed silicone electrode was inserted into the scala tympani for 5 mm. Frequency-specific compound action potentials of the auditory nerve (0.5-32 kHz) were measured pre- and directly postoperatively as well as on days 3, 7, 14, 21, and 28. Finally, temporal bones were harvested for histological evaluation. RESULTS: Application of the TAAC hydrogels resulted in significantly reduced hearing threshold shifts in low, middle and high frequencies and improved spiral ganglion cell survival in the second turn of the cochlea. Outer hair cell numbers in the basal and second turn of the cochlea were slightly reduced after TAAC application. CONCLUSION: In summary, we were able to demonstrate functional benefits of a single preoperative application of a TAAC hydrogel in a guinea pig model for CI, which persisted until the end of the observational period, that is, 28 days after surgery.
Assuntos
Implante Coclear/efeitos adversos , Implantes Cocleares , Perda Auditiva/prevenção & controle , Audição/efeitos dos fármacos , Hidrogéis/administração & dosagem , Triancinolona Acetonida/administração & dosagem , Potenciais de Ação/efeitos dos fármacos , Animais , Sobrevivência Celular/efeitos dos fármacos , Cóclea/efeitos dos fármacos , Cóclea/cirurgia , Preparações de Ação Retardada/administração & dosagem , Cobaias , Perda Auditiva/etiologia , Testes Auditivos , Gânglio Espiral da Cóclea/efeitos dos fármacosRESUMO
Cisplatin is one of the most widely used chemotherapeutic drugs for the treatment of cancer. Unfortunately, one of its major side effects is permanent hearing loss. Here, we show that glutathione transferase α4 (GSTA4), a member of the Phase II detoxifying enzyme superfamily, mediates reduction of cisplatin ototoxicity by removing 4-hydroxynonenal (4-HNE) in the inner ears of female mice. Under cisplatin treatment, loss of Gsta4 results in more profound hearing loss in female mice compared to male mice. Cisplatin stimulates GSTA4 activity in the inner ear of female wild-type, but not male wild-type mice. In female Gsta4-/- mice, cisplatin treatment results in increased levels of 4-HNE in cochlear neurons compared to male Gsta4-/- mice. In CBA/CaJ mice, ovariectomy decreases mRNA expression of Gsta4, and the levels of GSTA4 protein in the inner ears. Thus, our findings suggest that GSTA4-dependent detoxification may play a role in estrogen-mediated neuroprotection.
Assuntos
Cisplatino/efeitos adversos , Glutationa Transferase/metabolismo , Ototoxicidade/enzimologia , Animais , Limiar Auditivo/efeitos dos fármacos , Capilares/patologia , Cóclea/enzimologia , Cóclea/patologia , Cóclea/fisiopatologia , Cruzamentos Genéticos , Dano ao DNA/genética , Potenciais Evocados Auditivos do Tronco Encefálico/efeitos dos fármacos , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Glutationa Transferase/deficiência , Perda Auditiva/complicações , Perda Auditiva/enzimologia , Perda Auditiva/fisiopatologia , Masculino , Camundongos Endogâmicos CBA , Ototoxicidade/complicações , Ototoxicidade/patologia , Ototoxicidade/fisiopatologia , Estresse Oxidativo/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Gânglio Espiral da Cóclea/efeitos dos fármacos , Gânglio Espiral da Cóclea/patologiaRESUMO
Manganese (Mn) is an essential cofactor for many enzymes and thus plays an important role in normal growth and development. However, persistent exposure to high Mn concentrations can result in deleterious effects on not only the central nervous system but also peripheral nerves, including nerves associated with the auditory system. Our initial research on cochlear organotypic cultures in vitro showed that N-acetylcysteine (NAC) clearly decreases Mn-induced losses in hair cells (HCs), auditory nerve ï¬bers (ANFs) and spiral ganglion neurons (SGNs) in a concentration-dependent manner. Salidroside (SAL) (p-hydroxyphenethyl-b-d-glucoside; C14H20O7), which is extracted from Rhodiola rosea L, has many pharmacological actions and antioxidative, antiaging, neuroprotective and anticancer effects. We hypothesized that SAL could also protect HCs, ANFs and SGNs from Mn injury. Cochlear organotypic cultures were treated with 1 mM Mn alone or combined with SAL (1-1000 µM). The neurofilament staining results showed that HCs, ANFs and SGNs were seriously damaged at high concentrations (100-1000 µM) but less damaged at low concentrations (1-10 µM). SAL may protect against 1 mM Mn-induced HC loss and axonal degeneration, suggesting that SAL could be a promising drug for clinical applications.
Assuntos
Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Cloretos/toxicidade , Glucosídeos/farmacologia , Células Ciliadas Auditivas Internas/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Fenóis/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Gânglio Espiral da Cóclea/efeitos dos fármacos , Animais , Animais Recém-Nascidos , Proteínas Reguladoras de Apoptose/metabolismo , Citoproteção , Relação Dose-Resposta a Droga , Células Ciliadas Auditivas Internas/metabolismo , Células Ciliadas Auditivas Internas/patologia , Compostos de Manganês , Ratos Sprague-Dawley , Transdução de Sinais/efeitos dos fármacos , Gânglio Espiral da Cóclea/metabolismo , Gânglio Espiral da Cóclea/patologia , Técnicas de Cultura de TecidosRESUMO
The purpose of this study was to observe the regulatory effects of GABAA (γ-aminobutyric acid A) receptor on the N-methyl-D-aspartate (NMDA) receptor during excitotoxicity in spiral ganglion neurons in the rat cochlea induced by sodium salicylate (SS). Western blot illustrated SS decreased the expression of NMDA receptor 2B subunit (NR2B) surface protein through affecting GABAA receptor, but the total protein content did not significantly change. Y1472 and S1480 are important phosphorylation sites in NR2B, SS downregulated the Fyn-dependent phosphorylation of Y1472 in a manner not related to the CK2 (Casein Kinase 2) dependent phosphorylation of S1480, thus regulating the surface distribution and internalization of NMDA receptor through GABAA receptor. These results suggest that the modified pattern of dynamic balance between excitation and inhibition by coactivation of the GABAA receptor can attenuate the excitatory NMDA receptor under the action of SS, via inhibiting the Fyn-dependent phosphorylation of Y1472.
Assuntos
Anti-Inflamatórios não Esteroides/toxicidade , Receptores de GABA-A/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Salicilato de Sódio/toxicidade , Gânglio Espiral da Cóclea/efeitos dos fármacos , Animais , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Síndromes Neurotóxicas/etiologia , Síndromes Neurotóxicas/metabolismo , Fosforilação/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-fyn/metabolismo , Ratos , Ratos Sprague-Dawley , Gânglio Espiral da Cóclea/metabolismoRESUMO
Macroautophagy/autophagy dysfunction is associated with many neurodegenerative diseases. TFEB (transcription factor EB), an important molecule that regulates lysosomal and autophagy function, is regarded as a potential target for treating some neurodegenerative diseases. However, the relationship between autophagy dysfunction and spiral ganglion neuron (SGN) degeneration and the role of TFEB in SGN degeneration has not yet been established. Here, we showed that in degenerated SGNs, induced by sensory epithelial cell loss in the cochlea of mice following kanamycin and furosemide administration, the lipofuscin area and oxidative stress level were increased, the nuclear-to-cytoplasmic TFEB ratio was decreased, and the late stage of autophagic flux was impaired. After autophagy dysfunction was partially ameliorated with an MTOR inhibitor, which promoted TFEB translocation into the nucleus from the cytoplasm, we found that the lysosomal deficits were significantly relieved, the oxidative stress level was reduced, and the density of surviving SGNs and auditory nerve fibers was increased. The results in the present study reveal that autophagy dysfunction is an important component of SGN degeneration, and TFEB may be a potential target for attenuating SGN degeneration following sensory epithelial cell loss in the cochlea of mice. Abbreviations: 3-NT: 3-nitrotyrosine; 4-HNE: 4-hydroxynonenal; 8-OHdG: 8-hydroxy-2'-deoxyguanosine; ABR: auditory brainstem response; APP: amyloid beta (A4) precursor protein; CLEAR: coordinated lysosomal expression and regulation; CTSB: cathespin B; CTSD: cathespin D; SAMR1: senescence-accelerated mouse/resistance 1; SAMP8: senescence-accelerated mouse/prone 8; MAPK1/ERK2: mitogen-activated protein kinase 1; MTOR: mechanistic target of rapamycin kinase; SGN: spiral ganglion neuron; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscope; TFEB: transcription factor EB.
Assuntos
Autofagia/genética , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Lisossomos/metabolismo , Degeneração Neural/patologia , Gânglio Espiral da Cóclea/metabolismo , Serina-Treonina Quinases TOR/antagonistas & inibidores , Animais , Autofagia/efeitos dos fármacos , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Cóclea/citologia , Cóclea/efeitos dos fármacos , Cóclea/metabolismo , Cóclea/patologia , Células Epiteliais/citologia , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/patologia , Lisossomos/efeitos dos fármacos , Lisossomos/enzimologia , Lisossomos/ultraestrutura , Camundongos , Camundongos Endogâmicos C57BL , Degeneração Neural/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/genética , Transporte Proteico/efeitos dos fármacos , Transporte Proteico/genética , Proteína Sequestossoma-1/metabolismo , Gânglio Espiral da Cóclea/citologia , Gânglio Espiral da Cóclea/efeitos dos fármacos , Gânglio Espiral da Cóclea/patologia , Serina-Treonina Quinases TOR/genética , Serina-Treonina Quinases TOR/metabolismoRESUMO
In the context of acquired sensorineural hearing loss (SNHL), cochlear hair cells have long been thought to be among the most vulnerable elements in mammalian cochleae. However, recent studies have indicated that the synaptic connection between inner hair cells (IHC) and spiral ganglion neurons (SGN) can be an important target for the treatment of SNHL. Our previous studies in patients with sudden SNHL demonstrated delayed and gradual hearing recovery following topical application of insulin-like growth factor 1 (IGF-1), suggesting that not only protective but also regenerative mechanisms may account for hearing recovery after treatment with IGF-1. We then hypothesized that IGF-1 has the potential to drive the regeneration of IHC-SGN synapses. To test this hypothesis, we investigated the effects of IGF-1 on IHC-SGN synapses using cochlear explant cultures from postnatal day 2 mice that had been damaged by exposure to the excitatory amino acids N-methyl-d-aspartate and kainate. Cochlear explants that lost IHC-SGN synapses upon exposure to excitatory amino acids were cultured with exogenous IGF-1 for an additional 48â¯h. We observed increased numbers of IHC-SGN synapses after exogenous IGF-1 application. Pharmacological inhibition of the IGF-1 receptor attenuated the restoration of IHC-SGN synapses by exogenous IGF-1. These findings indicated that IGF-1 induces regeneration of IHC-SGN synapses in cochlear explant cultures from postnatal day 2 mice. Therefore, in a future study we will perform in vivo experiments using adult mice to ascertain the effects of IGF-1 on the regeneration of IHC-SGN synapses.
Assuntos
Cóclea/efeitos dos fármacos , Cóclea/inervação , Fator de Crescimento Insulin-Like I/administração & dosagem , Regeneração Nervosa/efeitos dos fármacos , Animais , Cóclea/fisiologia , Modelos Animais de Doenças , Células Ciliadas Auditivas Internas/efeitos dos fármacos , Células Ciliadas Auditivas Internas/patologia , Células Ciliadas Auditivas Internas/fisiologia , Perda Auditiva Neurossensorial/tratamento farmacológico , Perda Auditiva Neurossensorial/patologia , Perda Auditiva Neurossensorial/fisiopatologia , Humanos , Técnicas In Vitro , Fator de Crescimento Insulin-Like I/fisiologia , Ácido Caínico/toxicidade , Camundongos , Camundongos Endogâmicos ICR , N-Metilaspartato/toxicidade , Regeneração Nervosa/fisiologia , Ototoxicidade/tratamento farmacológico , Ototoxicidade/patologia , Ototoxicidade/fisiopatologia , Receptor IGF Tipo 1/antagonistas & inibidores , Receptor IGF Tipo 1/fisiologia , Gânglio Espiral da Cóclea/efeitos dos fármacos , Gânglio Espiral da Cóclea/patologia , Gânglio Espiral da Cóclea/fisiologia , Sinapses/efeitos dos fármacos , Sinapses/patologia , Sinapses/fisiologiaRESUMO
OBJECTIVE: To compare the benefits of a dexamethasone-eluting array for hearing preservation and cochlear histopathology in low trauma (soft-surgery) and high trauma models of cochlear implant surgery. METHODS: Adult guinea pigs were implanted with an intra-cochlear array using two different surgical procedures: either a soft-surgery approach or following generation of electrode insertion trauma (high trauma). Two methods of dexamethasone delivery were evaluated: elution from an electrode array alone, and elution from a cochlear implant electrode array in combination with a pre-operative systemic injection. All electrode arrays were implanted for a period of 4 weeks. Outcome measures at 4 weeks post-implantation included auditory brainstem response (ABR) thresholds, histological analysis of spiral ganglion neuron density, fibrotic tissue, new bone growth, and cochlear damage. RESULTS: Animals exposed to high surgical trauma showed greater hearing loss than those in the low trauma model, irrespective of the presence of dexamethasone. Whilst the area of intra-cochlear fibrotic tissue growth post-implantation was also independent of dexamethasone administration, new bone growth was significantly reduced in its presence. Our high trauma model effectively obliterated the organ of Corti and significantly reduced spiral ganglion neuron densities in the lower basal turn. This trauma-induced reduction in spiral ganglion neuron survival decreased with the inclusion of a dexamethasone-eluting array. A pre-operative systemic injection of dexamethasone did not significantly improve any outcome measures beyond those provided with a dexamethasone-eluting array alone. CONCLUSION: Dexamethasone-eluting intra-cochlear arrays may inhibit osteoneogenesis, and reduce spiral ganglion neuron loss following traumatic cochlear implantation.
Assuntos
Implante Coclear/efeitos adversos , Implantes Cocleares/efeitos adversos , Dexametasona/administração & dosagem , Glucocorticoides/administração & dosagem , Perda Auditiva/prevenção & controle , Complicações Pós-Operatórias/prevenção & controle , Animais , Cóclea/efeitos dos fármacos , Cóclea/cirurgia , Implante Coclear/métodos , Cobaias , Audição/efeitos dos fármacos , Perda Auditiva/etiologia , Gânglio Espiral da Cóclea/efeitos dos fármacos , Gânglio Espiral da Cóclea/cirurgiaRESUMO
BACKGROUND Kanamycin and subsequent furosemide administration was applied to the healthy guinea pigs to induce deafness. MATERIAL AND METHODS Of the deafened guinea pigs, 10 were further infused with anti-infection procedures (Group B) and the other 10 animals did not undergo anti-infection procedures (Group C). In Group B, the deafened animals were able to restore cochlear and middle ear functions following the anti-infection procedure. In Group C, all animals developed cochlear and middle ear infections. RESULTS Compared to the healthy guinea pigs, hair cells and spiral ganglion neurons (SGN) of deafened animals (in Group B and Group C) were severely damaged. SGN density of deafened animals was significantly lower than that of healthy control animals in all ear turns except the basal turn. There was no significant difference between Group B and Group C in SGN density. The average optical density value of neurofilaments of deafened animals was also significantly decreased after the ototoxic drug administration. Notably, the density of the neurons in the cochlear nucleus region (CNR) of the brainstem were not significantly different between the healthy control guinea pigs and deafened animals. CONCLUSIONS Mimic cochlear implant surgery-induced cochlear infection caused no significant damage to the auditory pathway in ototoxic drug-induced deafened guinea pigs.
Assuntos
Vias Auditivas/fisiologia , Limiar Auditivo/efeitos dos fármacos , Implante Coclear/efeitos adversos , Animais , Vias Auditivas/microbiologia , Limiar Auditivo/fisiologia , Infecções Bacterianas , China , Cóclea/efeitos dos fármacos , Implante Coclear/métodos , Surdez/induzido quimicamente , Surdez/cirurgia , Potenciais Evocados Auditivos do Tronco Encefálico/efeitos dos fármacos , Cobaias , Células Ciliadas Auditivas , Perda Auditiva Neurossensorial , Canamicina/farmacologia , Neurônios/efeitos dos fármacos , Otite/patologia , Gânglio Espiral da Cóclea/efeitos dos fármacosRESUMO
Cisplatin, a small platinum-containing molecule, is a widely used, highly effective anticancer drug. However, severe side effects have been found in cancer patients treated with cisplatin, including nephrotoxicity, neurotoxicity, and ototoxicity. These cisplatin-induced side effects can have a major impact on patient quality of life, including social development problems in pediatric patients that develop hearing loss. Previous studies have suggested that the major cause of cisplatin-induced ototoxicity is abnormal accumulation of reactive oxygen species (ROS) and oxidative stress. Alpha-lipoic acid (ALA), one of the most effective antioxidants, is known to be involved in the cellular antioxidant system and may have a protective effect on cisplatin-induced ototoxicity. However, the therapeutic effect of ALA on damaged hearing function and its detailed mechanism of action are not fully understood. This study focused on determining whether ALA has a potential as a protective and/or therapeutic agent for cisplatin-induced ototoxicity. Histological and physiological analyses were performed using cisplatin-treated mouse cochlea and HEI-OC1 culture cells in pre- and post-treatment with ALA in vitro and in vivo. We found that ALA contributes to protecting mitochondrial function by preventing ROS accumulation and inhibiting apoptotic cell death. Importantly, post-treatment with ALA consistently showed an almost equal restorative effect to pretreatment, in vitro and in vivo, supporting the possible use of ALA as a therapeutic agent for cisplatin-induced ototoxicity. This study is the first report on a strong therapeutic potential of ALA to rescue ototoxic hearing loss caused by cisplatin, and our data provide key evidence that ALA may act as a reducing agent for glutathione disulfide to increase glutathione levels on behalf of glutathione reductase. This result was consistent in both cultured cells and the mouse model, which improves the clinical value of ALA for therapy of cisplatin-induced ototoxicity.
Assuntos
Antineoplásicos/toxicidade , Cisplatino/toxicidade , Perda Auditiva/prevenção & controle , Substâncias Protetoras/uso terapêutico , Ácido Tióctico/uso terapêutico , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Orelha Interna/patologia , Feminino , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Células Ciliadas Auditivas/citologia , Células Ciliadas Auditivas/efeitos dos fármacos , Células Ciliadas Auditivas/metabolismo , Perda Auditiva/induzido quimicamente , Masculino , Camundongos , Substâncias Protetoras/farmacologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Gânglio Espiral da Cóclea/citologia , Gânglio Espiral da Cóclea/efeitos dos fármacos , Gânglio Espiral da Cóclea/metabolismo , Estria Vascular/efeitos dos fármacos , Estria Vascular/fisiologia , Ácido Tióctico/farmacologia , Proteína X Associada a bcl-2/metabolismoRESUMO
The inner ear is a complex sensory organ responsible for hearing and balance. Formation of the inner ear is dependent on tight regulation of spatial and temporal expression of genes that direct a series of developmental processes. Recently, epigenetic regulation has emerged as a crucial regulator of the development of various organs. However, what roles higher-order chromatin organization and its regulator molecules play in inner ear development are unclear. CCCTC-binding factor (CTCF) is a highly conserved 11-zinc finger protein that regulates the three-dimensional architecture of chromatin, and is involved in various gene regulation processes. To delineate the role of CTCF in inner ear development, the present study investigated inner ear-specific Ctcf knockout mouse embryos (Pax2-Cre; Ctcffl/fl ). The loss of Ctcf resulted in multiple defects of inner ear development and severely compromised otic neurogenesis, which was partly due to a loss of Neurog1 expression. Furthermore, reduced Neurog1 gene expression by CTCF knockdown was found to be associated with changes in histone modification at the gene's promoter, as well as its upstream enhancer. The results of the present study demonstrate that CTCF plays an essential role in otic neurogenesis by modulating histone modification in the Neurog1 locus.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fator de Ligação a CCCTC/metabolismo , Orelha Interna/inervação , Loci Gênicos , Histonas/metabolismo , Proteínas do Tecido Nervoso/genética , Neurogênese , Processamento de Proteína Pós-Traducional , Acetilação , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Orelha Interna/embriologia , Orelha Interna/patologia , Embrião de Mamíferos/metabolismo , Deleção de Genes , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Técnicas de Silenciamento de Genes , Lisina/metabolismo , Camundongos , Proteínas do Tecido Nervoso/metabolismo , Neurogênese/efeitos dos fármacos , Neurogênese/genética , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Gânglio Espiral da Cóclea/efeitos dos fármacos , Gânglio Espiral da Cóclea/metabolismo , Tretinoína/farmacologiaRESUMO
Transplantation of mesenchymal stromal cells (MSC) presents a promising approach not only for the replacement of lost or degenerated cells in diseased organs but also for local drug delivery. It can potentially be used to enhance the safety and efficacy of inner ear surgeries such as cochlear implantation. Options for enhancing the effects of MSC therapy include modulating cell behaviour with customized bio-matrixes or modulating their behaviour by ex vivo transfection of the cells with a variety of genes. In this study, we demonstrate that MSC delivered to the inner ear of guinea pigs or to decellularized cochleae preferentially bind to areas of high heparin concentration. This presents an opportunity for modulating cell behaviour ex vivo. We evaluated the effect of carboxymethylglucose sulfate (Cacicol®), a heparan sulfate analogue on spiral ganglion cells and MSC and demonstrated support of neuronal survival and support of stem cell proliferation.
Assuntos
Orelha Interna/cirurgia , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/fisiologia , Gânglio Espiral da Cóclea/cirurgia , Nicho de Células-Tronco , Animais , Adesão Celular , Movimento Celular , Proliferação de Células , Sobrevivência Celular , Células Cultivadas , Orelha Interna/efeitos dos fármacos , Orelha Interna/metabolismo , Feminino , Glicosaminoglicanos/metabolismo , Glicosaminoglicanos/farmacologia , Cobaias , Humanos , Masculino , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/metabolismo , Camundongos Endogâmicos C57BL , Ratos Sprague-Dawley , Gânglio Espiral da Cóclea/efeitos dos fármacos , Gânglio Espiral da Cóclea/metabolismo , Técnicas de Cultura de TecidosRESUMO
Phosphatase and tensin homologue (PTEN)-induced putative kinase 1 (PINK1) gene encodes a serine/threonine kinase, which acts as a molecular sensor of mitochondrial health necessary for mitochondrial quality control. The present study was designed to examine whether PINK1 expressed in C57BL/6 murine cochlea and HEI-OC1 cells and, if so, to investigate the possible mechanisms underlying the action of PINK1 in cisplatin-induced death of sensory hair cells (HCs) and spiral ganglion neurons (SGNs) in vitro. The expression pattern of PINK1, formation of parkin particles, and autophagy were determined by immunofluorescent staining. The expressions of PINK1, LC3B, cleaved-caspase 3 and p-JNK were measured by Western blotting. The levels of reactive oxygen species (ROS) were evaluated by DCFH-DA and Mito-Sox Red staining. The mitochondrial membrane potential was detected by Tetramethylrhodamine methyl ester perchlorate (TMRM) and Rhodamine 123. Cell viability and apoptosis were examined by CCK8 assay, TUNEL staining and Annexin V Apoptosis Detection Kit, respectively. We found that PINK1 was widely expressed in the cytoplasm in HCs, SGNs, stria vascularis of C57BL/6 cochlea and HEI-OC1 cells and, notably, the expression level in cochlear HCs and SGNs of postnatal day 4 (P4) mice was higher than that in adult mice. Moreover, treatment with 30⯵M cisplatin elicited the formation of ROS, which, in turn, led to PINK1 activation, parkin recruitment, autophagy formation and JNK pathway relevant to apoptosis in HEI-OC1 cells, HCs, and SGNs. Meanwhile, co-treatment with ROS scavenger N-acetyl-L-cysteine (NAC) or H2O2 consumer catalase-polyethylene glycol (PEG-catalase) inhibited parkin recruitment, alleviated autophagy formation, and mitigated JNK pathway related apoptosis. In addition, PINK1 silencing resulted in a lower level of autophagy, but, a higher mortality in HEI-OC1 cells treated with cisplatin. Taken together, data from this work reveal that PINK1 possesses the protective effect via induction of autophagy and resistance of apoptosis under cisplatin stimulus in sensory HCs and SGNs, implying that PINK1 might serve as an important regulator of cisplatin-elicited ototoxicity.
Assuntos
Antineoplásicos/toxicidade , Cisplatino/toxicidade , Células Ciliadas Auditivas/efeitos dos fármacos , Neuroproteção/fisiologia , Proteínas Quinases/metabolismo , Gânglio Espiral da Cóclea/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Células Ciliadas Auditivas/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Gânglio Espiral da Cóclea/metabolismoRESUMO
OBJECTIVE: The purpose of this study was to examine the anti-ototoxic impact of Ginkgo biloba extract and lycopene on the model of cisplatin-induced ototoxicity in rats. MATERIALS AND METHODS: Thirty-two Wistar albino rats were examined with the distortion product otoacoustic emission (DPOAE) test (MADSEN Capella2 ; GN Otometrics, ICS Medical, Chicago USA), and they were randomly divided into four groups. Group 1 (n=8) was defined as the healthy control group. Cisplatin was given intraperitoneally as single dose of 12 mg/kg to group 2 (n=8), group 3 (n=8), and group 4 (n=8). Group 2 was determined as ototoxic control group. G. biloba extract (100 mg/kg) was given to group 3, and 20 mg/kg lycopene was given to group 4 with orogastric feeding tube daily for 10 days. DPOAE test was repeated on day 10 on all the groups. Finally, histopathological examination was performed. The study has been lead in agreement with the principles by the Institutional Animal Care and Use Committee Review Board at Kocaeli University Medical Center (KOÜ HADYEK- 1/9-14). The animals were treated in accordance with protocols approved by this committee. RESULTS: When DPOAE tests were compared, there was no significant difference in the four groups before the application (p > 0.05). At the end of day 10, in groups 2 to 4, statistically significant changes were observed (p < 0.05). According to the cisplatin group, a significant increase in the DP-grams on G. biloba and lycopene groups was observed (p < 00.5). Corti organ and spiral ganglion neurons of groups 1, 3, and 4 were observed to have weak expression. Strong reactions were determined in organum spirale and some spiral ganglions of the cisplatin group. The striae vascularis damage on group 2 was found to be more significant more compared with groups 3 and 4. CONCLUSION: There is a protective effect of G. biloba and lycopene on cisplatin-dependent ototoxic rat model.