ascorbic-acid and Deafness

Topics: Ascorbic Acid; Citric Acid Cycle; Deafness; Ear, Inner; Humans; Pantothenic Acid; Vitamin A; Vitamin B Complex; Vitamin E; Vitamin K; Vitamins

Cochlear implant surgery is currently the therapy of choice for profoundly deaf patients. However, the functionality of cochlear implants depends on the integrity of the auditory spiral ganglion neurons. This study assesses the combined efficacy of two classes of agents found effective in preventing degeneration of the auditory nerve following deafness, neurotrophic factors, and antioxidants. Guinea pigs were deafened and treated for 4 weeks with either local administration of GDNF or a combination of GDNF and systemic injections of the antioxidants ascorbic acid and Trolox. The density of surviving spiral ganglion cells was significantly enhanced and the thresholds for eliciting an electrically evoked brain stem response were significantly reduced in GDNF treated animals compared to deafened-untreated. The addition of antioxidants significantly enhanced the evoked responsiveness over that observed with GDNF alone. The results suggest multiple sites of intervention in the rescue of these cells from deafferentation-induced cell death.

Topics: Acoustic Stimulation; Animals; Antioxidants; Ascorbic Acid; Auditory Threshold; Chromans; Deafness; Disease Models, Animal; Dose-Response Relationship, Radiation; Drug Administration Routes; Electric Stimulation; Evoked Potentials, Auditory, Brain Stem; Glial Cell Line-Derived Neurotrophic Factor; Guinea Pigs; Neurons; Spiral Ganglion; Statistics, Nonparametric

Based on in vitro studies, it is hypothesized that neurotrophic factor deprivation following deafferentation elicits an oxidative state change in the deafferented neuron and the formation of free radicals that then signal cell death pathways. This pathway to cell death was tested in vivo by assessing the efficacy of antioxidants (AOs) to prevent degeneration of deafferented CNVIII spiral ganglion cells (SGCs) in deafened guinea pigs. Following destruction of sensory cells, guinea pigs were treated immediately with Trolox (a water soluble vitamin E analogue)+ascorbic acid (vitamin C) administered either locally, directly in the inner ear, or systemically. Electrical auditory brainstem response (EABR) thresholds were recorded to assess nerve function and showed a large increase following deafness. In treated animals EABR thresholds decreased and surviving SGCs were increased significantly compared to untreated animals. These results indicate that a change in oxidative state following deafferentation plays a role in nerve cell death and antioxidant therapy may rescue SGCs from deafferentation-induced degeneration.

Topics: Animals; Antioxidants; Ascorbic Acid; Auditory Threshold; Cell Survival; Chromans; Cochlear Nerve; Deafness; Denervation; Evoked Potentials, Auditory, Brain Stem; Guinea Pigs; Hair Cells, Auditory; Hearing Loss, Sensorineural; Male; Neurons, Afferent; Neuroprotective Agents; Oxidative Stress; Spiral Ganglion; Treatment Outcome

Topics: Aged; Ascorbic Acid; Deafness; Humans; Magnesium; Sulfadiazine; Vitamin B Complex

Topics: Acute Disease; Ascorbic Acid; Atropine; Audiometry; Deafness; Diphenhydramine; Humans; Procaine; Scopolamine; Vascular Diseases; Vasodilator Agents

Topics: Adolescent; Alligators and Crocodiles; Animals; Ascorbic Acid; Cochlear Nerve; Deafness; Humans; Neuroma; Neuroma, Acoustic; Surgical Procedures, Operative; Tears; Vestibulocochlear Nerve

Topics: Ascorbic Acid; Audiometry; Deafness; Diphenhydramine; Drug Therapy; Hearing Disorders; Histamine; Humans; Hydrocortisone; Meprobamate; Niacin; Postoperative Complications; Procaine; Stapes Surgery

Topics: Ascorbic Acid; Choline; Deafness; Flavanones; Flavonoids; Glycosides; Inositol; Meniere Disease; Methionine; Niacin; Nicotinic Acids; Pantothenic Acid; Pyridoxine; Riboflavin; Thiamine; Vitamin B 12

Topics: Ascorbic Acid; Citrus; Deafness; Flavonoids; Folic Acid; Hearing Loss, Sensorineural; Meniere Disease; Vitamin B Complex; Vitamins

Topics: Ascorbic Acid; Deafness; Ear Diseases; Hearing Loss; Kanamycin