Limited regenerative response occurs in mammalian vestibular epithelia, although vestibular hair cell regeneration in mammals has been demonstrated under a variety of experimental conditions. Beta-catenin is known to play an important role in both cell-cell adhesion and signal transduction associated with cell proliferation. This study evaluated cell proliferation activity in mammalian vestibular epithelia in organotypic culture and examined the involvement of β-catenin in cell proliferation in vestibular epithelia. After 72 h of culture, utricles with or without induction of cell proliferation were examined. Cell proliferation was induced by brief exposure to forskolin and supplementation with fetal bovine serum. Cell proliferation activity was assessed by bromodeoxyuridine (BrdU) labeling. Immunohistochemistry was employed for analysis of cellular distribution of β-catenin. In utricles cultured without induction of cell proliferation, BrdU labeling was not found in vestibular epithelia. Expression of β-catenin was found in the area corresponding to the distribution of adherens junctions in vestibular epithelia. However, BrdU labeling was identified in sensory epithelia of utricles following induction of cell proliferation, although the number of BrdU-positive cells in sensory epithelia was very limited. Accumulation of β-catenin was occasionally found in proliferating cells in sensory epithelia
however, it was not always found in BrdU-positive cells. The present findings suggest that β-catenin may play a role in the induction of cell proliferation in mammal vestibular epithelia.