Objective:To explore the metabolic characteristics and the changes with lapse of time in superacute cerebral infarction in order to provide pathophysiological evidences for thrombolytic therapy and the use of neuroprotective drugs in superacute stage.Methods:12 healthy rabbits were randomly divided into two groups:sham operative group (5 rabbits)and occlusion of middle cerebral artery (MCAO) group (7 rabbits).The rabbits with MCAO were scanned with 1.5T MRI unit.The infarct regions and their mirror image regions were analyzed by probe 2000 software package of multi-voxel ~1 H magnetic resonance spectroscopy (~1H-MRS) at 0.5

1

2

3

4 and 6 hours respectively after MCAO.Results:(1)sham operative group:bilateral metabolites were symmetrically distributed

and N-acetylaspartate (NAA)/choline containing compounds (Cho)

phosphocreatine and creatine(Pcr+cr)/Oho showed no significant difference(P<0.05).(2)MCAO group:Lactate(Lac) was detected in the infarct region at 0.5 hours after ischemia

which kept increasing during first 6 hours.NAA and Pcr+Cr showed no obvious changes from O.5 to 1 hours while began to decrease after 2 hours

as compared with the mirror image regions(P<0.05 or 0.01).Cho was relatively stable within 3 hours and showed a reduction at 4 and 6 hours(P<0.05).Conclusion:The brain tissue in the infarct regions carried on anaerobic glycolysis continuously under local hypoxic conditions in the superacute stage after ischemia.The neuronal damage and the obstacle of energy metabolism begins at 2 hours and the breakdown of nerve cell membrane and myelin sheath at 4 hours.Above results suggest that the earlier the thrombolysis and the use of neuroprotective drugs for cerebral infarction begins

the better the effect of treatment may be.