Relation between rCBF and neuronal apoptosis in penumbra following focal cerebral infarction

AIM: To study regional cerebral blood flow (rCBF) and neuronal apoptosis in penumbra following focal cerebral infarction in rats. METHODS: To establish the model of focal cerebral infarction based on the principle of photochemical initiation of thrombosis. Laser Doppler flowmetry was used to measure rCBF in ischemic core and penumbra. The numbers and anatomic distribution of apoptosis cells were examined in situ histologically with terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-fluorescein nick end-labeling (TUNEL) assay in adjacent sections. RESULTS: rCBF in penumbra decreased to the minimum at 6 h in which it was 30.88%±7.11% of normal. From 9 h to 48 h, rCBF in penumbra increased gradually. At 48 h, 91.90%±4.56% of normal cerebral blood flow was recovered which was significant differences than others. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-fluorescein nick end-labeling (TUNEL) assay demonstrated that TUNEL-positive cells occurred at 6 h and were expending in a radial fashion only in penumbra. The numbers of apoptosis cells were progressively increased with time and to the maximum in penumbra after 48 h following focal cerebral infarction. CONCLUSION: There were delayed neuronal apoptosis following focal cerebral infarction. The mechanism may be related to ischemia-reperfusion injury induced by the recovery of rCBF in penumbra.