| Objective: To investigate the role of one autophgy/lysosomal pathway in neuronrecovery after traumatic brain injury.Methods: Traumatic brain injury (TBI) model was induced in rats by using freelydropping coup techniques. Autophagosome was detected in injured site and itsenvironmental region by using transmission electron microscope (TEM).Immunohistochemistry and western blot were employed to determine alternations incathepsin B, cathepsin D, LC3, Beclinl levels in injuried cortex and hippocampus afterTBI; Double label was used to detect alternations in the coexpression of positive cells ofcaspase-3 and cathepsin B, cathepsin D, LC3, or Beclinl by confocal laser scanningmicroscope (CLSM).Results: Autophagic structure was detected at 1 hour in injuried cortex after TBI, andits number was significantly increased at 4 to 8 day, and still could be found at 32 day afterTBI. Cathepsin B was activated at 1 hour after TBI while cathepsin D was not activateduntil 12 hour after TBI, and both of them got to their peak during 4 to 8 days, and kept ahigh level of activating 32 day after TBI. LC3 and Beclin1 were activated at 1 hour afterTBI. Both of them got to their peak during 4 to 8 days and kept a high level of activating32 day after TBI. Cathepsin B and D positive cells did not merge with caspase-3 until 6hour after TBI, in the mean while, LC3 and Beclin1 positive cells did not merge withcaspase-3 until 24 hour after TBI.Conclusions: 1. Autophagy was activated after TBI. 2. Lysomal enzyme wasactivated after TBI and lysomal function might be intensified. Cathepsin B and D mightinhibit apoptosis pathway during early stage, but activate it during late stage after TBI. 3.During the course of repair following TBI, especially in the initial stage, autophagy mightplay a continuous role in protecting some nerve cells; on the contrary, it might contribute to cell loss during intermediate and advanced stage. 4. Autophagy and apoptosis mightaccelerate activation of lysosomal enzyme and formation of secondary lysosome. 5.Cathepsin B, cathepsin D, LC3, and Beclin1 could be the diagnostic markers of TBI andestimate time course of TBI during later period. |
