Molecular biology of the degenerative and regenerative mechanisms in the inner ear sensory cells

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The aim of this study is to investigate the degenerative and regenerative mechanisms of inner ear sensory cell in to develop the new treatments for the inner ear diseases.The effect of ototoxic drugs on the cytoskeletal organization of vestibular sensory cells was investgated. The cytoskeletons were noted to have degenerated following ototoxic drug intoxication. Such degeneration was not linked with primary mitochondrial damage, but closely releated to subsequent degeneration of membrane-bound organelles. These findings suggest that cytoskeletons work closely together to maintain the structural integrity of the membrane-bound organelles, which can be altered by ototoxic drugs before the degeneration of membrane-bound organells.In the inner ear, constitutive NOS has been identified. NO mediates neurotransmission and play an important role in regulating vascular tone, and in maintaining endolymph and ion homeostasis. In contrast, enhanced NO production by inducible NOS and subsequent for … More mation of peroxynitrite is likely to be an important factor responsible for pathological insult of the vestibuli and removal of NO and/or O_2 to prevent formation of peroxynitrite or removal of peroxynitrite itsel may be beneficial treatment for vestibular diseases.The otoconial dynamics have been investigated using scanning electron microscopy, x-ray microanalysis and several kinds of Ca tracers. Dynamic exchange and/or uptake of Ca ions may occur even in adult animals. The giant otoconia are suggested to be formed mainly by dissolution of normal otoconia due to the loss of environmental calcium, followed by recrystallization as giant crystals. These phenomena seemed to be closely related to the otoconial dynamics which may regulate calcium ion homeostasis of endolymph.These results were presented at meetings (Sendai Symposium 96 and 97,5th and 6th meetings of Otological Society of Japan, 55th and 56th meetings of Japan Society for equilibrium Research) and were presented by 21 papers. Less