calpain and Blast-Injuries

37 degrees' warm water for 12 s; Burn group: 94 degrees' boiling water for 12 s; Blast group: 5 g cyclonite explode in 75 cm distance from left chest wall of rat; Burn-blast group: burn group and blast group combined modeling method. At 6, 24, 48, 72 h observation points after injury, abdominal aorta blood samples and myocardial specimen were collected. Left ventricular ejection fraction (EF), left ventricular fractional shortening index (FS) were measured through color Doppler ultrasound instrument; Myocardial tissue was stained with hematoxylin-eosin (HE); serum cardiac troponin I (CTnI) and creatine kinase isoenzyme (CK-MB) were detected; detection of cell apoptosis in myocardial tissue was performed by terminal deoxynucleotidyl transferase-mediated dUTP notch labeling technique (Tunel). Expression levels of calpain mRNA level and protein were detected with Real-time fluorescent quantitative polymerase chain reaction (RT-PCR) and Western imprinting method analysis; calpain activity was detected by fluorescence spectrophotometry.

Topics: Animals; Blast Injuries; Burns; Calpain; Male; Myocardium; Rats; Rats, Sprague-Dawley

Repeated blast exposures commonly induce traumatic brain injury (TBI) characterized by diffuse axonal injury (DAI). We hypothesized that degradation of cytoskeletal proteins in the brain can lead to DAI, and evaluated α-II spectrin degradation in the pathophysiology of blast-induced TBI using the tightly-coupled three repetitive blast exposure mice model with a 1-30 min window in between exposures. Degradation of α-II spectrin and the expression profiles of caspase-3 and calpain-2, the major enzymes involved in the degradation were analyzed in the frontal cortex and cerebellum using Western blotting with specific antibodies. DAI at different brain regions was evaluated by neuropathology with silver staining. Repeated blast exposures resulted in significant increases in the α-II spectrin degradation products in the frontal cortex and cerebellum compared to sham controls. Expression of active caspase-3, which degrades α-II spectrin, showed significant increase in the frontal cortex after blast exposure at all the time points studied, while cerebellum showed an acute increase which was normalized over time. The expression of another α-II spectrin degrading enzyme, calpain-2, showed a rapid increase in the frontal cortex after blast exposure and it was significantly higher in the cerebellum at later time points. Neuropathological analysis showed significant levels of DAI at the frontal cortex and cerebellum at multiple time points after repeated blast injury. In summary, repeated blast exposure results in specific degradation of α-II spectrin in the brain along with differential expression of caspase-3/calpain-2 suggesting cytoskeletal breakdown as a possible contributor of DAI after repeated blast exposure.

Topics: Animals; Axons; Blast Injuries; Brain; Brain Injuries; Calpain; Caspase 3; Cytoskeletal Proteins; Mice; Spectrin