Effect Of Limb Ischemic Preconditioning On Subsequent Focal Ischemic Injury In Rats

Objective: To explore the effect of limb ischemic preconditioning on subsequent focal cerebral ischemic injuries in rats, whether it reduces brain infarct volume and neurological deficits caused by subsequent focal cerebral ischemia. Method: Sixty adult Sprague-Dawley rats were randomly assigned to one of three groups: MCAo alone (control group), LIP 0 d group (permanent focal cerebral ischemia was given immediately after limb ischemic preconditioning) and LIP 1 d group(permanent focal cerebral ischemia was given following 24hours of limb ischemic preconditioning). Limb ischemic preconditioning was induced by three 10-minute cycles of left femoral vessels clamped in rats.Permanent middle cerebral artery occlusion (MCAo) was produced in SD rats using the intraluminal filament technique introduced by Longa et al. Animal was graded of neurological score before and following 24hours of MCAocculusion and deeply anesthetized and decapitated, brain was removed quickly. Seven coronal forebrain sections (2mm thick) weretaken from the frontal pole,each brainsection was processed for histochemical triphenyltetrazolium chloride (TTC) staining. Digital images were captured from the TTC-stained slices using a digital camera link to a camputer equipped with image processing software and the volume of infarct and ischemic area of rat brain were calculated. Data were analyzed with stastical method of ANOVA and Kruskal-Wallis test. Detecting the effect of limb ischemic preconditioning on subsequent focal ischemic damage and neurological deficits in rats. Result: Severe ischemic size was produced by permanent MCAo method in three group, there was no significant difference in the resulting infarct volume of LIP0d group(217.05± 120.00mm~3) and LIP1d group:(210.75±132.68mm~3) compared with controls group(252.79±131.89 mm~3) (p>0.05).In contrast, there was significant difference in neurological outcomes of LIPOd group (mean rank:18.11, P<0.05) compared with controls (mean rank:27.80), but there was no significant difference in neurological outcomes of LIP 1d group (mean rank:19.68,P > 0.05) compared with controls (mean rank:27.80),Using Kruskal-Wallis test. Conclusions: Limb ischemic preconditioning performed 0 d and 1 d prior to permanent focal cerebral ischemia could not reduced infarct size.But limb ischemic preconditioning attenuate neurological deficits performed 0 d prior to permanent focal cerebral ischemia, LIP performed Id prior to permanent focal cerebral ischemia could not afford the protection against neurological deficits induced by severe focal cerebral ischemia.