Changes in endogenous antioxidant enzymes during cerebral ischemia and reperfusion.
OBJECTIVE
The purpose of this study was to investigate the role of catalase (Cat), glutathione S transferase (GST), glutathione reductase (GR) and glutathione peroxidase (GPx) in cerebral ischemia induced by occluding the carotid arteries of male Wistar rats.


METHODS
The activities of the antioxidant enzymes Cat, GR, GPx and GST were measured in the cerebral cortex, cerebellum and hippocampus regions after varying periods of ischemia and reperfusion.


RESULTS
In all ischemia/reperfusion groups (0, 1 and 24 hours of reperfusion), the enzyme activities were found to be altered when compared to the sham-operated controls. The alterations were significant (p< or =0.05) in all reperfusion groups, particularly after 1 hour of reperfusion in all brain regions; however, maximum alterations were detected in the more vulnerable hippocampus.


CONCLUSIONS
Our findings indicate that the endogenous antioxidant enzymes are activated as soon as 1 hour after ischemia. In spite of significant up-regulation of these enzymes, a large number of neurons in selectively vulnerable regions of hippocampus undergo neurodegeneration. These biochemical changes suggest that vulnerability to oxidative stress in brain is region-specific. However, these changes which are adaptive or compromise the capacity of the brain to deal with the oxidative stress that could lead to neurodegeneration remains to be understood.
Kumari Naga
Kranthi
K
Department of Animal Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, AP, India.
Panigrahi
Manas
M
Prakash Babu
Phanithi
P
D000704:Analysis of Variance; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D001921:Brain / Q000201:enzymology / Q000473:pathology; D002545:Brain Ischemia / Q000201:enzymology* / Q000473:pathology; D002374:Catalase / Q000378:metabolism; D004195:Disease Models, Animal; D005982:Glutathione Transferase / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015424:Reperfusion; D013997:Time Factors
D000975:Antioxidants; D002374:Catalase; D005982:Glutathione Transferase