Permanent focal and transient global cerebral ischemia increase glial and neuronal expression of heme oxygenase-1, but not heme oxygenase-2, protein in rat brain.
Two heme oxygenase (HO) proteins have been identified to date; HO-1, a stress-induced protein, and HO-2, a constitutively expressed isoform. Recently, it was demonstrated that HO-1 mRNA expression is increased following transient global ischemia. The present study examined the effects of global and focal ischemia on HO-1 and HO-2 protein, using immunocytochemistry. Following 20 min of ischemia (rat 4 vessel occlusion model with hypotension) and 6 h of recirculation, increased HO-1 immunoreactivity was evident in hippocampal neurons. After 24 h of recirculation, HO-1 was observed in both hippocampal neurons and astroglial cells. By 72 h, expression was primarily glial and restricted to CA1 and CA3c. In addition to hippocampus, HO-1 was also evident in both neurons and glia in cerebral cortex and thalamus, and in striatal glial cells. Twenty-four hours following permanent focal ischemia, HO-1 immunoreactivity was observed in astroglial cells in the penumbra region surrounding the infarct. In contrast to HO-1, the pattern of HO-2 immunoreactivity was not altered following transient global or permanent focal ischemia. The increased expression of HO-1 following ischemia may confer protection against oxidative stress, but might also contribute to the subsequent neuronal degeneration.
Geddes
J W
JW
Department of Anatomy and Neurobiology, Sanders-Brown Center on Aging, University of Kentucky, Lexington 40536-0230, USA. jwgeddes@aging.coa.uky.edu
Pettigrew
L C
LC
Holtz
M L
ML
Craddock
S D
SD
Maines
M D
MD
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002545:Brain Ischemia / Q000201:enzymology*; D002536:Cerebral Arteries / Q000502:physiology; D006419:Heme Oxygenase (Decyclizing) / Q000096:biosynthesis*; D007150:Immunohistochemistry; D002546:Ischemic Attack, Transient / Q000201:enzymology*; D007527:Isoenzymes / Q000096:biosynthesis*; D008297:Male; D009457:Neuroglia / Q000201:enzymology*; D009474:Neurons / Q000201:enzymology*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000473:pathology
D007527:Isoenzymes; D012333:RNA, Messenger; D006419:Heme Oxygenase (Decyclizing)