[Study on c-myc mRNA and its product expression during hair cell regeneration in the chick basilar papilla]

To study the effect of c-myc gene expression during hair cell (HC) regeneration in the chick basilar papilla (BP) following getamicin ototoxicity.

c-myc mRNA and its product (c-myc protein) expression in the damaged region was histologicolly analyzed by in situ hybridization and immunohistochemistry. Thirty-six animals received one subcutaneous injection of gentamicin sulfate (50 mg/kg) daily for ten days. The animals were allowed to survive 1, 3, 7, 14, 21 or 28 days (n = 6 in each group) before sacrifice and preparation for both in situ hybridization and immunohistochemistry. Twelve animals were sacrificed as control for each groups (n = 2).

The results showed that the supporting cells and cells in the lumenal nuclear layer within the damaged region were strongly labeled for c-myc transcripts and its protein. Seven days after last injection, the highest level of c-myc mRNA and c-myc protein expression was observed in the injured sensory epithelium. C-myc gene expression began to decline from fourteen days post injection. High level expression of c-myc gene was discussed in relation to the time and location of HC regeneration.

The results indicate that c-myc gene expression may be an important molecular event in HC regeneration and may play a role in regulating progenitor cells proliferation.