cytochrome-c-t and Hearing-Loss

Cisplatin is a broad-spectrum anticancer drug that is commonly used in the clinic. Ototoxicity is one of the major side effects of this drug, which caused irreversible sensorineural hearing loss. Allicin, the main biologically active compound derived from garlic, has been shown to exert various anti-apoptotic and anti-oxidative activities in vitro and in vivo studies. We took advantage of C57 mice intraperitoneally injected with cisplatin alone or with cisplatin and allicin combined, to investigate whether allicin plays a protective role in vivo against cisplatin ototoxicity. The result showed that C57 mice in cisplatin group exhibited increased shift in auditory brainstem response, whereas the auditory fuction of mice in allicin + cisplatin group was protected in most frequencies, which was accordance with observed damages of outer hair cells (OHCs) and spiral ganglion neurons (SGNs) in the cochlea. Allicin markedly protected SGN mitochondria from damage and releasing cytochrome c, and significantly reduced pro-apoptosis factor expressions activated by cisplatin, including Bax, cleaved-caspase-9, cleaved-caspase-3and p53. Furthermore, allicin reduced the level of Malondialdehyde (MDA), but increased the level of superoxide dismutase (SOD). All data suggested that allicin could prevent hearing loss induced by cisplatin effectively, of which allicin protected SGNs from apoptosis via mitochondrial pathway while protected OHCs and supporting cells (SCs) from apoptosis through p53 pathway.

Topics: Animals; Antineoplastic Agents; Antioxidants; Apoptosis; Cell Survival; Cisplatin; Cytochromes c; Disulfides; Evoked Potentials, Auditory, Brain Stem; Hair Cells, Auditory; Hearing Loss; Mice, Inbred C57BL; Mitochondria; Neuroprotective Agents; Oxidative Stress; Random Allocation; Spiral Ganglion; Sulfinic Acids; Tumor Suppressor Protein p53

Since Korean red ginseng (KRG) has been proven to protect against gentamicin-induced vestibular and hearing dysfunction, the effects of KRG on age-related inner ear disorder in C57BL/6 mice were investigated. While age-related hearing loss was detected at the age of 6months (32kHz) and 9months (16kHz) in the control group, it was significantly delayed (p<0.05) in the 150mg/kg KRG-treated group. Vestibular dysfunction was observed in the tail-hanging and swimming tests, with significantly different severity scores and swimming times detected between the control and 150mg/kg KRG-treated group at the age of 12months (p<0.05). Mice treated with 500mg/kg KRG exhibited irritability and aggravated inner ear dysfunction. Histological observation supported the findings of hearing and vestibular function defects. In conclusion, C57BL/6 mice showed early-onset hearing loss and progressive vestibular dysfunction with aging, which were delayed by treatment with 150mg/kg KRG. However, 500mg/kg KRG treatment may induce aggressive behavior.

Topics: Aging; Animals; bcl-X Protein; Cytochromes c; Drug Evaluation, Preclinical; Hair Cells, Auditory; Hearing Loss; Male; Medicine, Korean Traditional; Mice, Inbred C57BL; Panax; Phytotherapy; Plant Extracts; Random Allocation; Vestibular Diseases

The authors evaluated the protective effects of Korean red ginseng (KRG) against gentamicin (GM)-induced unilateral vestibular and hearing dysfunction and investigated its effective mechanism using in vitro cell cultures. Vestibular function was comprehensively evaluated by a scoring system that ranged from 0 (normal) to 3 (worst) points, using head tilt, tail hanging, and swimming tests. The GM group showed significantly more deteriorated vestibular function (0 point--5 rats, 1 point--1 rat, 2 points--3 rats, and 3 points--3 rats) than the KRG+GM group (0 point--9 rats and 1 point--1 rat) (p<0.01). The hearing thresholds were better in the KRG+GM group than in the GM group (p<0.05). Quantitative analysis of hair cell damage in the scanning electron microscopy was closely related with vestibular and hearing functional results. In vitro study showed that ginsenoside Rb1 (gRb1) attenuated reactive oxygen species production, suppressed JNK activation, up-regulated Bcl-xL and down-regulated Bax, cytochrome c, caspase 3, and cleaved poly (ADP-ribose) polymerase in GM-treated VOT-E36 cells. These findings suggest that KRG including gRb1 component protects against vestibular/hearing dysfunction by inhibiting apoptotic pathways when ototoxicity is induced by unilateral intratympanic injection with GM in rats.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Caspase 3; Cell Line; Cytochromes c; Down-Regulation; Female; Gentamicins; Ginsenosides; Hearing Loss; Panax; Plant Extracts; Postural Balance; Protective Agents; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Up-Regulation; Vestibular Diseases

To describe the clinical features, muscle pathological characteristics, and molecular studies of a patient with a mutation in the gene encoding the accessory subunit (p55) of polymerase gamma (POLG2) and a mutation in the OPA1 gene.. Clinical examination and morphological, biochemical, and molecular analyses.. Tertiary care university hospitals and molecular genetics and scientific computing laboratory.. A 42-year-old man experienced hearing loss, progressive external ophthalmoplegia (PEO), loss of central vision, macrocytic anemia, and hypogonadism. His family history was negative for neurological disease, and his serum lactate level was normal.. A muscle biopsy specimen showed scattered intensely succinate dehydrogenase-positive and cytochrome-c oxidase-negative fibers. Southern blot of muscle mitochondrial DNA showed multiple deletions. The results of screening for mutations in the nuclear genes associated with PEO and multiple mitochondrial DNA deletions, including those in POLG (polymerase gamma gene), ANT1 (gene encoding adenine nucleotide translocator 1), and PEO1, were negative, but sequencing of POLG2 revealed a G1247C mutation in exon 7, resulting in the substitution of a highly conserved glycine with an alanine at codon 416 (G416A). Because biochemical analysis of the mutant protein showed no alteration in chromatographic properties and normal ability to protect the catalytic subunit from N-ethylmaleimide, we also sequenced the OPA1 gene and identified a novel heterozygous mutation (Y582C).. Although we initially focused on the mutation in POLG2, the mutation in OPA1 is more likely to explain the late-onset PEO and multisystem disorder in this patient.

Topics: Adult; Anemia, Macrocytic; Ataxia; Biopsy; Blotting, Southern; Cytochromes c; DNA Polymerase gamma; DNA-Directed DNA Polymerase; DNA, Mitochondrial; Dynamins; GTP Phosphohydrolases; Hearing Loss; Humans; Hypogonadism; Immunohistochemistry; Lactic Acid; Male; Models, Molecular; Muscle Fibers, Skeletal; Muscle, Skeletal; Mutation, Missense; Oncogene Protein p55(v-myc); Ophthalmoplegia; Reverse Transcriptase Polymerase Chain Reaction; Succinate Dehydrogenase; Vision Disorders

Minocycline, a second-generation tetracycline antibiotic used against gram-negative and gram-positive bacteria, protects against a wide range of neurodegenerative disorders by inhibiting caspases, iNOS and the release of cytochrome c. Since aminoglycoside antibiotics damage sensory hair cells in the inner ear by activating caspase-mediated cell death pathways, we hypothesized that minocycline would protect against gentamicin (GM) ototoxicity. To test this hypothesis, postnatal day 3 (P3) rat, cochlear organotypic cultures were treated with GM alone or in combination with minocycline (10-500 microM). Treatment with GM induced a dose-dependent loss of outer hair cells (OHC) and inner hair cells (IHC). Addition of minocycline to the GM-treated cultures greatly reduced the amount of GM-induced hair cell damage in P3 cochlear cultures. The greatest protection was achieved with 100 microM of minocycline. Application of minocycline alone had no adverse effects on hair cell survival. The advantage of this combination therapy is that minocycline prevents GM-induced hair cell loss while helping to suppress the bacterial infection.

Topics: Analysis of Variance; Animals; Animals, Newborn; Anti-Bacterial Agents; Apoptosis; Caspase 9; Caspase Inhibitors; Caspases; Cochlea; Cytochromes c; Dose-Response Relationship, Drug; Gentamicins; Hair Cells, Auditory; Hearing Loss; Minocycline; Organ Culture Techniques; Rats

Cisplatin (CDDP) is a highly effective chemotherapeutic agent but with significant ototoxic side effects. Apoptosis is an important mechanism of cochlear hair cell loss following exposure to an ototoxic level of CDDP. This study examines intracellular pathways involved in hair cell death induced by CDDP exposure in vivo to develop effective therapeutic strategies to protect the auditory receptor from CDDP-initiated hearing loss. Guinea pigs were treated with systemic administration of CDDP. Cochlear hair cells from CDDP-treated animals exhibited classic apoptotic alterations in their morphology. Several important signaling events that regulate the death of CDDP-injured cochlear hair cells were identified. CDDP treatment induced the activation and redistribution of cytosolic Bax and the release of cytochrome c from injured mitochondria. Activation of caspase-9 and caspase-3, but not caspase-8, was detected after treatment with CDDP, and the cleavage of fodrin by activated caspase-3 was observed within damaged hair cells. Intracochlear perfusions with caspase-3 inhibitor (z-DEVD-fmk) and caspase-9 inhibitor (z-LEHD-fmk) prevent hearing loss and loss of sensory cells, but caspase-8 inhibitor (z-IETD-fmk) and cathepsin B inhibitor (z-FA-fmk) do not. Although the stress-activated protein kinase/c-Jun NH(2)-terminal kinase (JNK) signaling pathway is activated in response to CDDP toxicity, intracochlear perfusion of d-JNKI-1, a JNK inhibitor, did not protect against CDDP ototoxicity but instead potentiated the ototoxic effects of CDDP. The results of the present study show that blocking a critical step in apoptosis may be a useful strategy to prevent harmful side effects of CDDP ototoxicity in patients having to undergo chemotherapy.

Topics: Animals; Antineoplastic Agents; Apoptosis; bcl-2-Associated X Protein; Carrier Proteins; Caspase Inhibitors; Cisplatin; Cysteine Proteinase Inhibitors; Cytochromes c; Female; Guinea Pigs; Hair Cells, Auditory; Hearing Loss; Isoenzymes; JNK Mitogen-Activated Protein Kinases; MAP Kinase Signaling System; Microfilament Proteins; Mitochondria; Proto-Oncogene Proteins c-bcl-2