Correlation between caspase regulatory gene expression and facial nerve injury in a facial nerve injury model / 中国组织工程研究

ABSTRACT

BACKGROUND:Caspase plays a crucial role in the cellapoptosis, but the influence of different facial nerve injury on caspase 1, caspase 8, cyto-c protein expression and their correlation stil remain unclear. OBJECTIVE:To construct facial nerve crush or distal transection injury models, observe the morphological changes of facial motoneurons, investigate death gene caspase 3, caspase 8, cyto-c expression, and analyze their correlation. METHODS:Facial nerve crush or distal transection injury model was established in the right facial nerve of rats, while the left facial nerve served as normal controls. We observed the morphology and the death of facial motoneurons with toluidine blue staining and transmission electron microscope. Expressions of caspase 3, caspase 8 and cyto-c proteins were studied by immunohistochemistry analysis fol owing facial nerve injury. RESULTS AND CONCLUSION:Both facial nerve distal transection and crush injury resulted in the death of facial motoneurons, and the death pattern was mainly apoptosis. Caspase 3, caspase 8 and cyto-c protein expressions were observed in the subnucleus of normal rat facial nucleus. cells of the distal transection group were stained more intensely than that of crush group. Expressions of these proteins began to increase at 3 days after the injuries. Caspase 3 and caspase 8 protein expression peaked at 14 days, whereas cyto-c protein expression peaked at 7 days after the injuries. Expressions of caspase 3, caspase 8 and cyto-c proteins were correlated with facial nerve injury type and injury time. Expressions of caspase 8 and cyto-c protein were correlated with expression of caspase 3 protein. The findings indicate that, caspase 8 and cyto-c contribute to activate caspase 3, and caspase cascade reaction plays an important role in the apoptosis of facial motoneurons.