Local Cerebral Glucose Utilization and Cytoskeletal Proteolysis as Indices of Evolving Focal Ischemic Injury in Core and Penumbra

Abstract

Summary:To ascertain the tempo of progression to irre versible injury in focal ischemia, we subjected halothane anesthetized Sprague-Dawley rats to photochemically in duced distal middle cerebral artery occlusion (dMCAO) combined with permanent ipsilateral and 1 h contralateral common carotid artery occlusions. Head temperature was maintained at 36°C. At times centered at either 1.5 or 3 h post-dMCAO, the rate of local glucose metabolism (lCMRgl) was measured by 2-deoxyglucose autoradiogra phy, and cytoskeletal proteolysis was assessed regionally by an immunoblotting procedure to detect spectrin break down products. At 1.5 h (n = 5), the cortical ischemic core was already severely hypometabolic (lCMRg1 15.5 ::t 10.8 J.l.moll00 g-I min -I, mean ::t SD), whereas the cor tical penumbral zone was hypermetabolic (69.0 ::t 9.7). (The lumped constant was verified to be unchanged by methylglucose studies.) Neutral red pH studies at this time point showed that both the core and penumbral Experimental successes in elucidating the patho physiology of cerebral ischemia and in developing effective strategies to reduce ischemic injury have made it incumbent to understand the time frame within which tissue progression to irreversible in jury occurs. Recent interest in this regard has fo cused on the means of defining and characterizing Received June 9, 1994; final revision received September 2, 1994; accepted October 17, 1994. 398zones were equally acidotic. By 3 h post-dMCAO (n = 6), ICMRgI in the penumbral zone had fallen to low levels (15.4 ::t 2.2 J.l.mol 100 g-I min-I) equal to those of the ischemic core (16.7 ::t 4.5). Correspondingly, spectrin breakdown in the ischemic core was advanced at both 2 and 3.5 h post-dMCAO (36 ::t 18% and 33 ::t 18% of total spectrin, respectively), whereas in the penumbral zone spectrin breakdown was less extensive and more highly variable at both times (22 ::t 23% and 29 ::t 16%). We conclude that irreversible deterioration of the ischemic core, as evidenced by the onset of local cytoskeletal pro teolysis, begins within 2 h of middle cerebral artery oc clusion. In the ischemic penumbra, the transition from glucose hyper-to hypometabolism occurs by 3.5 h and is associated with a milder and more variable degree of spectrin breakdown.

Relationship between Flow-Metabolism Uncoupling and Evolving Axonal Injury after Experimental Traumatic Brain Injury

“…However, the major findings that the degree of delayed axotomy correlated with the severity of the initial CBF reduction and flow-metabolism uncoupling and that a threshold relationship exists for this, do tend to support the idea that mismatches in energy supply are a major factor involved in the pathogenesis of progressive axonal injury. A previous study on the ischemic rat brain demonstrated that initially after injury, gray matter cytoskeletal injury was lower and more variable in the hypermetabolic penumbral areas compared to the hypometabolic core (Yao et al, 1995). However, levels were similar at later time points when all regions became hypometabolic, indicating that a period of energy failure is required for irreversible cytoskeletal breakdown.…”

Neuroprotective effects of gelsolin during murine stroke

“…Previous studies have shown that Ca 2+ -mediated proteolysis of cytoskeletal proteins such as spectrin and MAP-2 occurs during the first few hours after ischemia/reperfusion and correlates closely with subsequent neuronal degeneration and death (29,30,31). Because our data indicated that Ca 2+ influx through N-methyl-D-aspartate NMDA receptors and VDCC is enhanced in neurons lacking gelsolin, we performed immunohistochemical analyses to assess the development of Ca 2+ -mediated proteolysis following MCA occlusion in gsn +/+ and gsn -/-mice.…”

Early Delineation of Ischemic Tissue in Rat Brain Cryosections by High-Contrast Staining

“…21 A silver staining method was chosen since proteolysis of fibrillic macromolecules that are stained by silver starts a few minutes after onset of ischemia. 22,23 For SIS, the slides were submerged for 2 minutes into a silver impregnation solution (see below), which was shaken vigorously. Then the slides were washed in distilled water 6 times for 1 minute before they were transferred to a vigorously shaken developer solution for 3 minutes (see below).…”