Exposure to low-dose barium by drinking water causes hearing loss in mice
| Autor: | Kyoko Ohgami, Masashi Kato, Toyonori Tsuzuki, Nobutaka Ohgami, Haruka Tamura, Sohjiro Hori, Shoko Ohnuma |
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| Rok vydání: | 2012 |
| Předmět: |
Time Factors
Hearing loss Physiology chemistry.chemical_element Toxicology Kidney Mice Ototoxicity Microscopy Electron Transmission otorhinolaryngologic diseases medicine Evoked Potentials Auditory Brain Stem Animals Tissue Distribution Hearing Loss Lung Spiral ganglion Neurons Mice Inbred ICR Dose-Response Relationship Drug Cerebrum General Neuroscience Myocardium Spectrophotometry Atomic digestive oral and skin physiology Kidney metabolism Brain Barium Anatomy Acoustics medicine.disease Dose–response relationship Disease Models Animal medicine.anatomical_structure chemistry Acoustic Stimulation Female sense organs medicine.symptom Spiral Ganglion Perfusion Water Pollutants Chemical |
| Zdroj: | Neurotoxicology. 33(5) |
| ISSN: | 1872-9711 |
| Popis: | Purpose We continuously ingest barium as a general element by drinking water and foods in our daily life. Exposure to high-dose barium (>100 mg/kg/day) has been shown to cause physiological impairments. Direct administration of barium to inner ears by vascular perfusion has been shown to cause physiological impairments in inner ears. However, the toxic influence of oral exposure to low-dose barium on hearing levels has not been clarified in vivo. We analyzed the toxic influence of oral exposure to low-dose barium on hearing levels and inner ears in mice. Experimental design We orally administered barium at low doses of 0.14 and 1.4 mg/kg/day to wild-type ICR mice by drinking water. The doses are equivalent to and 10-fold higher than the limit level (0.7 mg/l) of WHO health-based guidelines for drinking water, respectively. After 2-week exposure, hearing levels were measured by auditory brain stem responses and inner ears were morphologically analyzed. After 2-month exposure, tissue distribution of barium was measured by inductively coupled plasma mass spectrometry. Results Low-dose barium in drinking water caused severe hearing loss in mice. Inner ears including inner and outer hair cells, stria vascularis and spiral ganglion neurons showed severe degeneration. The Barium-administered group showed significantly higher levels of barium in inner ears than those in the control group, while barium levels in bone did not show a significant difference between the two groups. Barium levels in other tissues including the cerebrum, cerebellum, heart, liver and kidney were undetectably low in both groups. Conclusions Our results demonstrate for the first time that low-dose barium administered by drinking water specifically distributes to inner ears resulting in severe ototoxicity with degeneration of inner ears in mice. |
| Databáze: | OpenAIRE |
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