Objective:To study the metabolic dynamic changes in rat model of permanent middle cerebral artery occlusion(MCAO) within one week

followed up for two months with 1H MRS.Methods:A total of 18 rats were randomized into three different groups

the normal( n =6)

the sham-operated( n =6) and cerebral ischemic group ( n =6).A rat model of permanent MCAO was induced by occluding the right middle cerebral artery. 1H MRS was performed within the area of cerebral infarction and the homologous area of the contralateral hemisphere at the following time points:30min

1

3

6

12

24h

3

7

15d

1 and 2months after cerebral ischemia.Results:In the normal and the sham-operated group

bilateral metabolites were symmetrically distributed

no significant differences in NAA

Ch and Cr concentration were found between two hemispheres( P >0.05).The marked increase in NAA

Ch and Cr was recognizable in bilateral spectra 30min after cerebral ischemia and sustained up to the period of 3-6hours

there was no significant difference in NAA

Ch and Cr concentration between two hemispheres( P >0.05).NAA reached the lowest level at 24hours and Ch and Cr at 3days

and then NAA

Ch and Cr gradually increased with time.The increase in NAA was especially obvious which increased by 1.5 times at 2 months than that at 24hours after cerebral ischemia.The earliest detection of lactate was at 10 minutes within the infarct.The lactate concentration elevated and peaked at 12 hours

and a partial recovery of the reduction of lactate was seen at 3 days.However

the elevation in lactate was no longer observed during the period of up to 2 month follow-up.Conclusion:(1) 1HMRS can early detect the metabolite changes induced by middle cerebral artery occlusion in rats.(2).Abnormalities in chronic stage of cerebral ischemia in rats could also be found and gave important information for evaluating neuroprotective strategies.