摘要
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-mediat-ed nick end-labelling method (Klenow method). Results: Six hours after reperfusion, a few neurons in dam-aged 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 that DNA SSBs might be an important step in DNA-damage procession which might be induced by free radicals. ② At the same time when lots of DNA SSBs were produced, many neurons in the damaged regions showed morphological change, which indicated that lots of neurons had already progressed to irreversible damages when DNA SSBs took place.
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 that DNA SSBs might be an important step in DNA-damage procession which might be induced by free radicals.② At the same time when lots of DNA SSBs were produced, many neurons in the damaged regions showed morphological change, which indicated that lots of neurons had already progressed to irreversible damages when DNA SSBs took place.
