抄録
In avian, there are good evidences for hair cells to regenerate after damages. It is recently demonstrated morphologically that some mammalian vestibular hair cells regenerate. However, it is not clear any details of functional regeneration. Here we report physiological evidences of functional regeneration in vestibular hair cells after damage by gentamicin in cultured rat maculaes. The mechano-electrical transduction (MET) was monitored as Ca2+ responses by loading fura-2 and by applying mechanical stimulation to the hair bundle. In the control, the percentage of functioning samples was decreased gradually with the day of culture and no MET was found after 2 weeks. Paradoxically, in the sample after damage, MET was found even after 2 weeks. This means that MET re-appeared in 2 weeks indicating functional regeneration of hair cells. To facilitate regeneration, we applied steroid hormones, then the percentage of functioning samples was increased. Hair bundles' loss and regeneration were confirmed morphologically, by Nomarsky optics and by scanning electron microscopy from the same sample. Phalloidin stained samples were also investigated. In the control, number of hair bundles was gradually decreased during culture. However, the number gradually increased in 2 weeks after acute hair bundle loss by gentamicin. In the area hair bundles were completely lost, some short hair bundle like structures emerged 2-3 weeks later. This may indicate that mammalian vestibular hair cells regenerate morphologically and functionally. [Jpn J Physiol 54 Suppl:S168 (2004)]
