RESUMEN
Waltzing guinea pigs are an inbred guinea pig strain with a congenital and progressive balance and hearing disorder. A unique rod-shaped structure is found in the type I vestibular hair cells, that traverses the cell in an axial direction, extending towards the basement membrane. The present study estimates the total number of utricular hair cells and supporting cells in waltzing guinea pigs and age-matched control animals using the optical fractionator method. Animals were divided into four age groups (1, 7, 49 and 343 day-old). The number of type I hair cells decreased by 20% in the 343 day-old waltzing guinea pigs compared to age-matched controls and younger animals. Two-photon confocal laser scanning microscopy using antibodies against fimbrin and betaIII-tubulin showed that the rods were exclusive to type I hair cells. There was no significant change in the length of the filament rods with age. Taken together, our data show that despite rod formation in the type I hair cells and deformation of hair bundles being present at birth, the type I hair cell population is not affected quantitatively until a year after birth.
Asunto(s)
Células Ciliadas Vestibulares/patología , Animales , Recuento de Células , Cobayas , Células Ciliadas Vestibulares/clasificación , Células Ciliadas Vestibulares/fisiología , Pérdida Auditiva/genética , Pérdida Auditiva/patología , Pérdida Auditiva/fisiopatología , Glicoproteínas de Membrana/metabolismo , Proteínas de Microfilamentos/metabolismo , Microscopía Confocal , Equilibrio Postural/fisiología , Trastornos de la Sensación/genética , Trastornos de la Sensación/patología , Trastornos de la Sensación/fisiopatología , Tubulina (Proteína)/metabolismoRESUMEN
The aminoglycoside kanamycin is a commonly used antibiotic, but unfortunately it is oto- and nephrotoxic in large doses. The negative effects are thought to be due to the formation of free radicals which is why strong antioxidants and iron chelators like 2,3-dihydroxybenzoic acid (DHB) are of great interest. This study estimates cellular quantitative changes in the utricular macula of mice following systemic treatment with kanamycin alone or in combination with DHB. The animals were injected with either saline, kanamycin or kanamycin + DHB for 15 days and perfusion fixed three weeks after last injection. Total volume of the utricle, as well as total number of hair and supporting cells, were estimated on light microscopic sections. Total volume and mean volume of hair cell types I and II and supporting cells were estimated on digital transmission electron micrographs. Total volume of the utricular macula, hair cell type I and supporting cells decreased significantly in animals injected with kanamycin but not in animals co-treated with DHB. Hair and supporting cell numbers remained unchanged in all three groups. In conclusion, the kanamycin-induced volume reduction of type I hair cells was attenuated by DHB.