To enhance their mechanical sensitivity and frequency selectivity, hair cells amplify the mechanical stimuli to which they respond. Although cell-body contractions of outer hair cells are thought to mediate the active process in the mammalian cochlea, vertebrates without outer hair cells display highly sensitive, sharply tuned hearing and spontaneous otoacoustic emissions. In these animals the ...

The intracellular membrane systems in intact, isolated outer hair cells were visualised using the fluorescent membrane probe 3,3'-dihexyloxacarbocyanine iodide (DiOC6) and by freeze-fracture, and f-actin distribution was examined with rhodamine-phalloidin. DiOC6 stained the sub-surface cisternal membranes in the lateral wall and revealed a membrane system running in the centre of the cell from ...

Aminoglycoside antibiotics such as gentamicin have long been known to destroy cochlear and vestibular hair cells in vivo. In the cochlea outer hair cells are preferentially affected. In contrast, gentamicin will not damage outer hair cells in vitro unless it has been enzymatically converted to a cytotoxic metabolite. Several potential inhibitors of this enzymatic reaction were tested in an in v...

The cochlea of the mammalian inner ear contains three rows of outer hair cells and a single row of inner hair cells. These hair cell receptors reside in the organ of Corti and function to transduce mechanical stimuli into electrical signals that mediate hearing. To date, the molecular mechanisms underlying the maintenance of these delicate sensory hair cells are unknown. We report that targeted...

Hair loss is a prevalent medical condition affecting both genders. In this study, we investigate the effects of specific class extracellular vesicles (EVs), namely human normal fibroblast-derived EVs (hFB-EVs), on dermal papilla (DP) and outer root sheath (ORS) cells examine molecular mechanisms responsible for hair growth in follicles (HFs). We find that Wnt3a, which maintains hair-generating ...

Cell death in outer hair cells of the mammalian inner ear induced by aminoglycoside antibiotics is mediated by reactive oxygen species (ROS) and can be prevented by antioxidants. The current study investigates the role of the nuclear factor (NF)-kappaB pathway in cell death or survival in adult CBA mice. Kanamycin (700 mg/kg subcutaneously, twice per day) progressively destroys hair cells but a...

Mechanosensory hair cells release glutamate at ribbon synapses to excite postsynaptic afferent neurons, via AMPA-type ionotropic glutamate receptors (AMPARs). However, type II afferent neurons contacting outer hair cells in the mammalian cochlea were thought to differ in this respect, failing to show GluA immunolabeling and with many "ribbonless" afferent contacts. Here it is shown that antibod...

Hair cell loss is a major cause of sensorineural hearing loss. We have developed a method to examine metabolic events in hair cells in response to stimuli known to cause hair cell loss, such as acoustic trauma and aminoglycoside administration. The method employs two-photon excitation of the metabolic intermediate, reduced nicotinamide adenine dinucleotide (NADH), in hair cell mitochondria in a...

The hair cells in the mammalian cochlea are of two distinct types. Inner hair cells are responsible for transducing mechanical stimuli into electrical responses, which they forward to the brain through a copious afferent innervation. Outer hair cells, which are thought to mediate the active process that sensitizes and tunes the cochlea, possess a negligible afferent innervation. For every inner...