From the Departments of Neurosurgery (M.K., K.K., H.S., S.W.) and Anatomy
II (R.S.), Mie University School of Medicine, Mie, Japan.
Correspondence to: Kenji Kanamaru, MD, DMSc, Department of Neurosurgery, Mie University School of Medicine, Tsu, Mie 514, Japan. E-mail kanamaru{at}clin.medic.mie-u.ac.jp
Background and
PurposeSubarachnoid hemorrhage (SAH)-induced
heme oxygenase-1 (HO-1) in glia throughout the rat brain
without affecting heme oxygenase-2 (HO-2). However, the
relationship between cerebral vasospasm and the expression of heme
oxygenases after SAH is thus far unknown. The purpose of
the present study was to clarify the effect of vasospasm on the
expression of heme oxygenases in a rat model of
SAH.
MethodsEndothelin, hemolysate, hemolysate saturated with carbon
monoxide (CO-hemolysate), and saline were injected into the cisterna
magna of adult rats. Angiography was repeated before each injection and
15 and 60 minutes and 24 hours after each injection.
Immunocytochemistry for HO-1, HO-2, and glial fibrillary acidic protein
(GFAP) was performed 24 hours after the injection.
ResultsA significant vasospasm occurred in the basilar artery
after the injection of endothelin, hemolysate, and CO-hemolysate. The
degree of vasospasm was most prominent 15 minutes after each injection.
There was no significant difference in the degree of vasospasm among
injections. The HO-1 was induced exclusively in the glial cells
throughout the brain after injection of hemolysate and CO-hemolysate;
however, it was not induced by endothelin and saline. In the dentate
gyrus of the hippocampus and the molecular layer of the cerebellum, the
HO-1-positive cells were also stained for GFAP, suggesting astrocytic
glial cells. On the other hand, HO-2 immunoreactivity was abundant in
neurons and was not affected by endothelin, hemolysate, CO-hemolysate,
or saline.
ConclusionsIt is suggested that heme per se, rather than
ischemia induced by vasospasm, plays a pivotal role in the
expression of HO-1 in this rat model.
Departments
of Neurology and Neurosurgery,
University of California at San Francisco,
VA Medical Center,
San Francisco, California
© 1998 American Heart Association, Inc.
Original Contributions
Effect of Vasospasm on Heme Oxygenases in a Rat Model of Subarachnoid Hemorrhage
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