Turkish Neurosurgery
2009 , Vol 19 , Num 4
Neuroproctective Effects of Ischemic Tolerance (Preconditioning) and Postconditioning
Uludag University School of Medicine, Department of Physiology, Bursa, Turkey
Elucidation of the endogenous cell survival pathways involved in ischemic
tolerance (preconditioning) and postconditioning has significant clinical
implications for preventing neuronal damage in susceptible patients. Ischemic
tolerance is a phenomenon in which the brain protects itself against future injury by
adapting to low doses of noxious insults. Ischemic postconditioning is defined as
brief periods of reperfusion alternating with re-occlusion applied during the very
early minutes of reperfusion that mechanically alters the hydrodynamics of
reperfusion. Similar pathways and molecules play a role in pre-and
postconditioning but their roles and timing are different in each conditioning.
Understanding the neuroprotective effects of mechanisms underlying
conditionings has been elusive, but NMDA receptor activation, nitric oxide,
inflammatory cytokines, and suppression of the innate immune system appear to
have a role. Reactive oxygen species and classical ligand stimuli play a role in
postconditioning with KATP channels and protein kinase C pathways acting as
mediators.
Keywords :
Preconditioning, Postconditioning, Neuronal protection