Quá trình lão hóa diễn ra ở mọi cơ quan trong cơ thể và gây ra những hậu quả rất nghiêm trọng. Tuy nhiên nếu thực hiện tích cực một số biện pháp, chúng ta có thể trì hoãn quá trình lão hóa. | 408 NOVEL CELLULAR PATHWAYS the necrotic zone of aged rats lacked NeuN immunopositivity in 28 of the ipsilateral cortical volume. The infarcted area continued to expand and by day 7 reached 35 to 41 of the ipsilateral cortical volume in both young and aged rats. This suggests that the timing of neuronal loss in aged rats is accelerated but the ultimate extent of brain cell loss is not significantly different from that in young rats. It should be noted however that the greater number of degenerating neurons in aged rats is seen only if the infarct area is relatively large for small infarcts there is no age difference in the number of surviving neurons in the ischemic border zones Sutherland Dix Auer 1996 Lindner Gribkoff Donlan et al. 2003 . Neuronal Degeneration and Loss through Postischemic Apoptosis Are Accelerated in Aged Rats Fluoro JadeB-staining showed that aged rats had an unusually high number of degenerating neurons in the infarct core as early as day 3 while young rats had a lower number vs. young rats P . Interestingly the number of degenerating neurons did not rise further in aged animals even though the infarcted area continued to expand so that by day 7 the numbers of degenerating neurons were almost the same in both age-groups Popa-Wagner Schroder Schmoll et al. 1999 Zhao Puurunen Schallert et al. 2005a. Aging increases the susceptibility of the CNS to apoptotic events Hiona Leeuwenburgh 2004 . One possible mechanism of increased expression of pro-apoptotic proteins in aged animals is via increased NO production by constitutive NO synthase isoforms in a model of transient global ischemia Martinez-Lara Canuelo Siles et al. 2005 . The particular vulnerability of the aged brain to apoptosis Gozal Row Kheirandish et al. 2003 is confirmed by our finding that aged rats had considerably more apoptotic cells 3 days after ischemia than did young rats 2-fold increase over young rats P Popa-Wagner et al. 2007 . At day 7 the ratio was .
