CSF neuron-specific enolase as a quantitative marker of neuronal damage in a rat stroke model

A technique for chronic cisternal cerebrospinal fluid (CSF) sampling in conscious rats was used to obtain multiple 50 microliters samples before and up to 7 days after middle cerebral artery occlusion. Neuron-specific enolase (NSE) concentrations were measured by radioimmunoassay using a readily available kit. The volume of infarction was measured by integrating the area of damage on 9 evenly spaced histological sections of the forebrain. This correlated well (r = 0.97, P less than 0.001) with the concentration of CSF neuron-specific enolase integrated over the first 5 days post occlusion, in animals with pure cortical and mixed cortical and striatal lesions. The correlation was maintained in animals given the NMDA antagonist MK-801. There was also a good correlation between the CSF NSE concentration 3 days post-MCAO and the volume of infarction (r = 0.92, P less than 0.01). It is therefore possible that CSF neuron-specific enolase may be useful as a quantitative marker of ischaemic damage in humans and provide a useful adjunct in the assessment of neuroprotective drugs in stroke.