calpain and Craniocerebral-Trauma

Traumatic brain injury is putting an extreme burden on societies all over the world. While surgical and neuro-intensive treatment is traditionally aimed at space occupying or focal lesions, traumatic brain injury is frequently associated with diffuse axonal injury, which significantly contributes to its morbidity and mortality. Current taught appreciates that diffuse axonal injury is a progressive event gradually evolving from focal alterations in axolemmal permeability and the underlying axonal ultrastructure to axonal disconnection, a process amenable of therapeutic interventions. This review is primarily focusing on the clinical/neuroradiological manifestation and our contemporary knowledge of the pathobiology of traumatically evoked (diffuse-) axonal injury with particular emphasize on recent- to date, primarily experimental-therapeutic approaches that in the future might offer potential aid to the head injured.

Topics: Accidents, Traffic; Animals; Axons; Brain Injuries; Calpain; Caspases; Craniocerebral Trauma; Cyclosporine; Humans; Hypothermia, Induced; Magnetic Resonance Imaging; Tomography, X-Ray Computed

Calpain-mediated breakdown of the cytoskeleton has been proposed to contribute to brain damage resulting from head injury. We examined the corpus callosum from patients who died after a blunt head injury in order to determine if there was evidence of these pathophysiological events in a midline myelinated commissure that is susceptible to damage after human head injury. Western blotting revealed marked reductions in the levels of neurofilament triplet proteins 200 and 68kDa in the corpus callosum of head-injured patients compared with control subjects. Neurofilament 200kDa levels were significantly reduced as detected by either phosphorylation-dependent or -independent antibodies. In contrast, there were minimal changes in the levels of beta-tubulin or the microtubule-associated protein, tau, in the head-injured patients, although amyloid precursor protein immunostaining demonstrated axonal damage in 9 of the 10 patients. The inactive 800kDa and active 76kDa subunits of mu-calpain were present in control subjects and head-injured patients. However, there was a significant increase in the levels of calpain-mediated spectrin breakdown products in head-injured patients compared with the control subjects. The results demonstrate that following human blunt head injury, there is a significant degradation of neurofilament proteins and increased levels of calpain-mediated spectrin breakdown products within the corpus callosum. Therefore, our data support the hypothesis that calpain-mediated breakdown of the cytoskeleton may contribute to axonal damage after head injury.

Topics: Adult; Aged; Calpain; Corpus Callosum; Craniocerebral Trauma; Diffuse Axonal Injury; Female; Humans; Male; Middle Aged; Neurofilament Proteins