Abstract: Objective To study the expression of cathepsin-B and-D in different time point after traumatic brain injury. Methods Traumatic brain injury (TBI) model was established on rats, cathepsin-B and cathepsin-D immunofluorescence staining and confocal microscope analysis were performed. Positive cells were counted by confocal microscope and image analysis techniques were used to determine the morphological changes in each group. Results Immunofluorescence staining results showed that cathepsin-B was activated 1 hour after TBI while cathepsin-D was not activated until 12 hour after TBI. Both of them got to their peak during 4 to 8 days, and kept a high level of activating 32 days after TBI. Cathepsin-B and -D positive cells did not merge with caspase-3 positive cells until 6 h after TBI. Conclusion Cathepsin-B and-D could be the diagnostic markers of TBI and can estimating time course of latteral TBI. They blocked caspase-3 activation at the beginning period after TBI and started to promote cell death with caspase-3 6 h after TBI.

Key words: traumatic brain injury, lysosome, cathepsin-B, cathepsin-D, caspase-3