Effect Of Fastigial Nucleus Stimulation On DNA Damage And Repair With Stroke In Rats And Patients 2.DNA Damage And Repair In The Blood Of Patient With Ischemic Stroke

Objectives To investigate the molecular mechanisms of fastigial nucleus (FN) electrical stimulation protecting against ischemia-reperfusion induced oxidative DNA damage in rat brain. Methods Male Wistar rats weighting 250±30g were 106 dividing into 4 groups:(1) pure model group,(2)fastigial nucleus stimulation group, (3) fastigial nucleus-lesion group, (4) sham-operated group. The third group was destroyed by ibotemic acid (IBO) 5 days before FN stimulation. The focal cerebral ischemia and reperfusion model was made by thread embolish of middle cerebral artery in all groups except the fourth group.Rats were killed at 6,24 and 48 hours after ischemia/reperfusion. The brain was removed, sliced into 2-mm sections. The third 2-mmsection was applied to DNA or RNA extraction Coronal sections of 20μm thickness at the caudate level were cut on a cryostat at -20℃.DNA was analyzed by HPLC with the electrochemical (EC) detection. Using a semi-quantitative reverse transcription- polymerase chain reaction assay on total mRNA from the ischemic tissue, OGG1 mRNA was determined in rat brains. Ku70 mRNA was hybridized with a rat OGG1 cDNA probe. DNA fragmentation was detected by terminal deoxynucleotidyl transferase-mediated uridine 5′-triphosphate-biotin nick end-labeling (TUNEL).Results (1) Oxidative DNA damage product, 8-hydroxy-2′-deoxyguanosine (8-ohdG) was accumulated following ischemia- reperfusion in rat brains. The amount of 8-ohdG in FN stimulation group was significantly reduced compared with that of pure model group and FN-lesion group (P<0.01), whereas no significant difference was observed in pure model group and FN-lesion group. (2) rOGG1 mRNA expression in pure model group after reperfusion was not different from that in FN-lesion group, levels of rOGG1 mRNA at 6 hours after ischemia/reperfusion was very low, rOGG1 mRNA expression at 24 and 48 hours after ischemia/reperfusion increased a little in pure model group and FN-lesion group, but there was a significant reduction compared with sham-operatedgroup and FN stimulation group(P<0.01).rOGG1 mRNA expression in FN stimulation group at 6 hours after reperfusion was not different from that in sham-operated group, but rOGG1 transcript level at 24 and 48 hours after ischemia/reperfusion increased significantly (P<0.01).(3)Ku70 mRNA expression in pure model group after reperfusion was not different from that in FN-lesion group, but there was a significant reduction compared with FN-stimulation group and sham-operated group(P<0.01).Ku70 mRNA expression in FN-stimulation group at 24 and 48 hours after reperfusion was not different from that in sham-operated group.(4)Basal ganglia in sham-operated group was observed 1 to 5 Tunel-positive cells. The number of Tunel-positive cells in FN-stimulation group, FN-lesion group and pure model group after reperfusion increased significantly compared with sham-operated group (P<0.01), whereas the number of Tunel-positive cells in FN-stimulation group reduced significantly compared with that of pure model group and FN-lesion group (P<0.01). The number of Tunel-positive cells in pure model group was not different from that in FN-lesion group. Conclusions (1)Ischemic injury occurs during the reperfusion phase of ischemia-reperfusion insults may be due toDNA damage. (2) The activity of DNA repair enzyme reduction may involve the mechanism of apoptotic neuron death after ischemia/reperfusion. (3)The neuroprotective mechanism of fastigial nucleus electrieal stimulation is associated with upregulation DNA repair enzymatic activity.