Neuron-specific enolase in gerbil brain and serum after transient cerebral ischemia.

BACKGROUND AND
PURPOSE: The sensitivity and validity of serum neuron-specific enolase as a marker of brain injury were tested after global cerebral ischemia.
METHODS: Sixty-nine Mongolian gerbils were perfusion fixed after variable reperfusion after 5-minute (group 1) or 15-minute (group 2) bilateral carotid occlusion. Neuron-specific enolase was analyzed by an enzyme immunoassay in serum of control, sham-operated, and ischemic animals before euthanasia and in nonischemic gerbil brains. Brains were processed for histology, immunohistochemistry, and morphometric evaluation of ischemic neuronal damage.
RESULTS: After cerebral ischemia, loss of neuronal immunoreactivity was closely associated with increased neuron-specific enolase serum levels, which were significantly elevated by 24 hours (group 1) or by 4 hours (group 2) of reperfusion (P < .001). Response of serum levels depended on the duration of preceding ischemia, and maximum concentrations were approximately 3-fold (group 1) or 20-fold (group 2) those of nonischemic control. Morphological damage became apparent 48 hours (group 1) or 12 hours (group 2) after ischemia, as indicated by histological and morphometric data.
CONCLUSIONS: Significantly elevated neuron-specific enolase serum levels could be demonstrated as a consequence of ischemia-induced cytoplasmic loss of neuron-specific enolase in central nervous system neurons, corresponded quantitatively to the severity of cerebral ischemia, and were detectable before irreversible neuronal injury. Therefore, analysis of serum neuron-specific enolase is suggested to be both a valuable diagnostic tool in clinical management of the initial stages of global cerebral ischemia and a prognostic parameter during the postischemic course.