Single-strand DNA damages and its relationship with morphological change of neurons at early stage of rat cerebral ischemia／reperfusion

Objective: To discuss the DNA-strand breaks at early stage of middle cerebral artery occlusion/ reperfusion (MCAO/R). Methods: Neurons number and morphologic change were observed by Nissl stain method, and DNA strand breaks were in situ detected by using DNA polymerase- I Klenow fragment-mediated nick end-labelling method (Klenow method). Results: Six hours after reperfusion, a few neurons in damaged regions appeared morphologic changes while a few Klenow-positive cells were detected (P<0. 01). Twenty-four hours after reperfusion lots of neurons showed morphologic change while the number of Klenow-positive cells immediately and remarkably increased (P<0. 01). Seventy-two hours after reperfusion the number of neurons decreased significantly and the number of Klenow-positive cells was also less than that in 24 h (P<0. 05). Conclusion: ① 24 h after reperfusion when the number of Klenow-positive cells reached peak value, DNA single-strand breaks (SSBs) took place in many Klenow-positive cells, and presumed

Single-strand DNA damages and its relationship with morphological change of neurons at early stage of rat cerebral ischemia/reperfusion

Objective:To discuss the DNA-strand breaks at early stage of middle cerebral artery occlusion/reperfusion (MCAO/R). Methods: Neurons number and morphologic change were observed by Nissl stain method, and DNA strand breaks were in situ detected by using DNA polymerase- I Klenow fragment-mediated nick end-labelling method (Klenow method). Results: Six hours after reperfusion, a few neurons in damaged regions appeared morphologic changes while a few Klenow-positive cells were detected (P＜ 0. 01 ).Twenty-four hours after reperfusion lots of neurons showed morphologic change while the number of Klenow-positive cells immediately and remarkably increased (P＜0. 01). Seventy-two hours after reperfusion the number of neurons decreased significantly and the number of Klenow-positive cells was also less than that peak value, DNA single-strand breaks (SSBs) took place in many Klenow-positive cells, and presumed that DNA SSBs might be an important step in DNA-damage procession which might be induced by free radicals.morphological change, which indicated that lots of neurons had already progressed to irreversible damages when DNA SSBs took place.