Thick Brain Slices Model the Ischemic Penumbra

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Abstract
Hypothalamic brain slices, varying in thickness from 400μ to 1,000μ, were assessed by studying 2-deoxyglucose (2DG) metabolism, lactate accumulation, inulin spaces, and morphology at the light and ultrastructural levels. Evidence of increased glycolytic flux due to anaerobic metabolism is found at thicknesses greater than 600μ in association with a progressive increase in the inulin-exclusion space. The metabolic profiles, as a function of depth into the slices, reveal that 700-μ slices function in a manner similar to 540-μ slices at the surfaces, but with a core of increased 2DG phosphorylation at the slice center. In contrast, the 1000-μ slices show significant reductions of 2DG and increases in 2DG6P relative to the 540-μ slices at the slice surface as well as in the slice interior, suggesting impaired transport of 2DG into cells and spread of ischemic injury from the slice interior to the slice surface. Despite these metabolic changes, only minor morphologic changes of ischemic injury were found at the center of thicker slices, and in vitro glucose utilization of 1000-μ slices remained constant for up to 15 h. These three slice thicknesses should provide a useful model for studying the neurochemistry and neuropharmacology of the ischemic penumbra.