The Signal Transduction Of Cell Proliferation And Apoptosis In The Guinea Pig Vestibular Epithelinm Following Chronic Gentamicin Toxicity

The injury of vestibular hair cells is one of the important factor in the vestibular deseases. The key step in therapy of these deseases is to improve the regeneration ability of vestibular hair cells. To determine the mechanism of signal transduction involved in the apoptosis and regeneration of vestibular hair cells of mammals will provide reliable theoretical evidences for therapy of the vestibular deseases as well as cochlear deseases. Aim To study the process of the injury and regeneration of vestibular epithelium of guinea pig after the chronic toxicosis of gentamicin, and to explore the relationship between the vestibular hair cell apoptosis and proliferation, the changes of the expression of protein kinase A (C a and C P ),protein kinase C (P i , P II and Y )and the PKC activity of vestibular end organ were observed. Furthermore, the relationship between PKA IPKC and vestibular injury/repair was discussed. Method 1.The apoptosis of vestibular epithelium was detected by TUN7EL method and the cell proliferation by anti-Brdu inimunohistochemical method. 2.The expression and location of PKA(C a and C P )in vestibular organs was detected by ininiunohistochemistry. 3.The expression and location of PKC( P ,n and y) in vestibular organ was detected by iinmunohistochemistry and the PKC activity by 32p tracer method. Result I .There were no TUNEL or Brdu positive cells in control group. From ld to 3wk after gentamicin treatment the TUNEL positive cells were detected, a large number of positive cells were seen in ld group and then the positive cells were decreased. Positive cells still could be seen in 3wk group. The positive cells predominantly located in hair cell layer. Id after gentamicin treatment, the Brdu positive cells could be seen either in supporting cell layer or in hair cell layer. In 3d group the positive cells in supporting cell layer were increased. In lwk group some positive cells in hair cell layer were found. In 2wk group the Brdu lasted until 3wk after gentamicin treatment. 2. The positive expression of PKC isoforms P t,n and Y were detected in vestibular sensory epithelium . There was negative staining in connective tissue under epithelium. The stain of PKC iso forms P and i?was weaker than that of PKC P ~. The antigen distributions of different PKC isoforms were different. Comparied with control group, the expression of PKC P and y was decreased at Id after injection of gentamicin and then it was increased gradually. The expression was obviously higher than that of control group at lwk after injection and it hadn't recovered yet at 3wk after injection. There were no obvious differences in expressions of PKC P n among different groups. The change trend of PKC activity was similar with the expression change of PKC P nd as a whole. 3.The expression of PKA C a was detected in vestibular epithelium. Its expression was stronger in stereocilia bundle and in cuticular plate but weaker in cytoplasm. In 2wk and 3wk group, in utricle the expression of PKA ~ a in the stereocilia was weakened than that in control group, and the stereociliary bundles were much longer orderly than that in ld,3d and 1w groups. The expression of PKA C ~ was weaker in control group and it was increased in nucleus membrane in 2wk and 3wk after treatment. In each group the...