Background & objectives: Ischemic stroke is the thirdleading cause of death and disability in
most of the human societies. There is no effective treatment due to complexity of the
pathophysiological mechanisms. Today, more researches are designed to introduce involving
factors and new treatment strategies in brain ischemia. The objective of this study is to introduce
an experimental model of the focal cerebral ischemia in rat with increased success rate and low
mortality rate.
Methods: In this research 32 male rats (Sprague-Dawley) were studied as in four experimental groups. Animals were anesthetized with chloralhydrate (400mg/kg, ip). Focal cerebral ischemia was induced by intraluminal filament method. A silicon coated nylon filament was used for
middle cerebral artery occlusion. Regional cerebral blood flow was monitored by laser Doppler
flowmetery to guide the insertion of the filament into the vascular pathway. 24 hours after
ischemia (90minutes), animals were assessed for neurological outcome, infarct volume and brain
edema formation. A new and reformed neurological test was used for evaluation of neurological
deficits. 2 - millimeter coronal sections were collected from 6 levels of the brain and stained,
digitized and quantified by using an image analysis system. Ischemic brain edema formation was
investigated by brain water content detection.
Results: Induction of ischemia in ischemic group, seriously caused impairment of motor
functions (neurological deficit score 4±0.5) While sham operated rats had no motor deficit and
infarction. Mean total infarct volume of left (ischemic) hemisphere was 402±43 mm3 and 62.7
percent of infarction occurred in cortical regions of the brain. Induction of focal cerebral
ischemia in the left (ischemic) hemisphere of the brain significantly increased water content
(compared to both hemispheres of sham (84±0.23 percent group and right hemisphere of the
same group. Success rate of ischemia induction was 100 percent and there was no mortality due
to technical problems.
Conclusion: Our findings indicate that continuous recording of regional cerebral blood flow
using laser Doppler flowmeter had significant role in increasing success rate and lowering
mortality rate in the present model of ischemic rat. This experimental model with high success
rate and low limitation can be used for brain ischemia studies and evaluating new therapeutic
strategies
