Rapid Communication: Regional Variability in DNA Fragmentation After Global Ischemia Evidenced by Combined Histological and Gel Electrophoresis Observations in the Rat Brain

Abstract

We have studied whether the delayed cell death induced by transient forebrain ischemia is associated with an internucleosomal cleavage of DNA into oligonucleosome-sized fragments. The integrity of genomic DNA in various brain regions after a 20-min four-vessel ischemia was examined using gel electrophoresis. We found typical ladders of oligonucleosomal DNA fragments in the striatum and in the Ammon's horn. In the latter we also often found a random DNA degradation as a smear pattern. These findings were reinforced by a specific in situ labeling of DNA breaks in tissue sections. A dark staining of nuclei was observed in the cell bodies of neurons--in particular in the head of the caudate and in the vulnerable CA1 hippocampal area. With biochemical and histological approaches, there was no evidence of DNA degradation in regions that are resistant to the injury. We conclude that the association of multiple mechanisms of cell damage may occur after a global ischemia. The regional variability in DNA fragmentation stresses the importance of using histological approaches in parallel with gel electrophoresis.

Differences in DNA Fragmentation following Transient Cerebral or Decapitation Ischemia in Rats

“…The domination of order even late after the initial ischemic period strengthens the suggestion, despite the absence of morphological evidence, that ischemic neurons are using some component of the apoptotic machinery. The accu mulating evidence in support of this conclusion from our own studies and those in other laborato ries (Heron et al, 1993;Linnik et al, 1993;Mac Manus et al, 1993;Okamoto et al, 1993;Tominaga et al, 1993;MacManus et al, 1994;Sei et al, 1994), now also including studies of epilepsy (Pollard et al, 1994), indicates that such research might lead to discoveries of new molecular targets for drug inter vention in the debilitating postischemic neuronal degeneration of stroke.…”

Pathophysiology of Cerebral Ischemia and Brain Trauma: Similarities and Differences

“…Linnik and colleagues (1993) first provided evidence for programmed cell death by showing that inhibition of protein synthesis was neuroprotective in a model of transient global ischemia. Subsequent studies identified DNA laddering and sensitive indicators of DNA damage associated with apoptosis (Heron et al, 1993;Petito et al, 1997). In addition, histopathological verification of injury models supports the hypothesis that at least a subpopulation of neurons die by apoptotic mechanisms.…”

The Dietary Excitotoxins β‐N‐Methylamino‐l‐Alanine and β‐N‐Oxalylamino‐l‐Alanine Induce Necrotic‐ and Apoptotic‐Like Death of Rat Cerebellar Granule Cells

“…However, there is now compelling evidence in a number of neuronal cell types, including CGC, that apoptosis as well as necrosis underlie the death of neurones after an excitotoxin exposure (Kure et al, 1991;Heron et al, 1993;Linnik et al, 1993;MacManus et al, 1993MacManus et al, , 1994Ankarcrona et al, 1995; FIG. 8.…”