Serum amino acid levels after permanent middle cerebral artery occlusion in the rat

Background and Purpose: High levels of glutamate in plasma and cerebrospina l fluid (CSF) have been demonstrated in patients with acute ischemic stroke . Whereas this glutamate increase in CSF is only evidenced during the first 6 h in stable ischemic stroke, it is sustained for 24 h in progressing str oke. The aim of this investigation was to study the evolution of serum glut amate levels after stroke in a rat model of permanent cerebral artery occlu sion. Methods: Glutamate, glycine, aspartate, taurine and tryptophan were m easured by high-performance liquid chromatography from serum samples taken before and at different times after permanent middle cerebral artery occlus ion (MCAO) and from sham-operated rats. Results:After MCAO, a 3-fold increa se in glutamate and a 2-fold increase in glycine and aspartate were observe d in rat serum. The onset of this amino acid increase began 4-6 h after isc hemic induction, reached peak values at 8-24 h and returned to preischemic values by 48-72 h. Serum concentrations of taurine and tryptophan were not modified after MCAO. Sham-operated rats did not exhibit changes of basal am ino acid concentrations in serum. Conclusions: The serum excitatory amino a cid profile in this experimental model confirms that the early detection of increased concentrations of glutamate and glycine at systemic circulation observed in patients with acute stroke is a consequence of the cerebral isc hemic process. Copyright (C) 2000 S. Karger AG. Basel.