Proteins released from degenerating neurons are surrogate markers for acute brain damage

The experimental and clinical study of degenerative brain disorders would benefit from new surrogate markers for brain damage. To identify novel candidate markers for acute brain injury, we report that rat cortical neurons release over 60 cytoskeletal and other proteins, as well as their proteolytic fragments into the medium during neuronal death. The profiles of released proteins differ for necrosis and apoptosis, although a subset of proteins is released generally during neurodegeneration. The value of this approach was established by immunodetection of the released proteins 14-3-3ζ and 14-3-3β, as well as calpain and caspase derivatives of tau and α-spectrin in cerebrospinal fluid (CSF) following traumatic brain injury (TBI) or transient forebrain ischemia in the rat. These results indicate that proteins and their proteolytic fragments released from degenerating neurons are cerebrospinal fluid markers for acute brain damage and suggest that efflux of proteins from the injured brain may reflect underlying mechanisms for neurodegeneration.