Usual and unusual methods for detection of lipid peroxides as indicators of tissue injury in cerebral ischemia: what is appropriate and useful?

Oxidants, antioxidants and the ischemic brain

Despite numerous defenses, the brain is vulnerable to oxidative stress resulting from ischemia/reperfusion. Excitotoxic stimulation of superoxide and nitric oxide production leads to formation of highly reactive products, including peroxynitrite and hydroxyl radical, which are capable of damaging lipids, proteins and DNA. Use of transgenic mutants and selective pharmacological antioxidants has greatly increased understanding of the complex interplay between substrate deprivation and ischemic outcome. Recent evidence that reactive oxygen/nitrogen species play a critical role in initiation of apoptosis, mitochondrial permeability transition and poly(ADP-ribose) polymerase activation provides additional mechanisms for oxidative damage and new targets for post-ischemic therapeutic intervention. Because oxidative stress involves multiple post-ischemic cascades leading to cell death, effective prevention/treatment of ischemic brain injury is likely to require intervention at multiple effect sites.

Prereperfusion flushing of ischemic territory: a therapeutic study in which histological and behavioral assessments were used to measure ischemia-reperfusion injury in rats with stroke

OBJECT

In ischemic stroke, the ischemic crisis activates a cascade of traumatic events that are potentiated by reperfusion and eventually lead to neuronal degeneration. The primary aim of this study was to investigate a procedure that could minimize this damage by interfering with the interactions between reestablished blood flow and ischemically damaged tissue, as well as by improving regional microcirculation.

METHODS

Using a novel hollow filament, the authors flushed the ischemic territory with heparinized saline before vascular reperfusion after occlusion of the middle cerebral artery (MCA). The results demonstrate a statistically significant (p < 0.001) reduction in infarct volume (75%; from 45.3 +/- 3.6% to 11.4 +/- 1.7%, determined with Nissl staining) in rats in which a 2-hour MCA occlusion was followed by a 48-hour reperfusion. Infarction and neuronal degeneration were confirmed using silver staining, which revealed a significantly larger infarct (36.3%, p < 0.05) than that detected with Nissl staining. The long-term neuroprotection of the prereperfusion flushing was also evaluated. This was determined by a series of motor behavior tasks (foot placing, parallel bar traversing, rope and ladder climbing) performed up to 28 days after reperfusion. Motor deficits were found to be significantly ameliorated in animals that underwent the flushing procedure (p < 0.001). In addition, neurological outcome was also improved significantly (p < 0.001) in the same animals.

CONCLUSIONS

These results indicate that interaction between reperfusion and the metabolically and biochemically compromised tissue could be interrupted by the prereperfusion flushing procedure, which could lead to a reduction in brain injury from stroke. Mechanical reopening of the cerebral occlusion with local flushing and isolated reperfusion of the regionally injured brain might offer new treatment options for patients with stroke.