Differential temporal and spatial post-injury alterations in cerebral cell morphology and viability

Combination of ischemia and beta-amyloid (A beta) toxicity has been shown to simultaneously increase neuro-inflammation, endogenous A beta deposition, and neurodegeneration. However, studies on the evolution of infarct and panorama of cellular degeneration as a synergistic or overlapping mechanism between ischemia and A beta toxicity are lacking. Here, we compared fluorojade B (FJB) and hematoxylin and eosin (H&E) stains primarily to examine the chronology of infarct, and the viability and morphological changes in neuroglia and neurons located in different brain regions on d1, d7, and d28 post A beta toxicity and endothelin-1 induced ischemia (ET1) in rats. We demonstrated a regional difference in cellular degeneration between cortex, corpus callosum, striatum, globus pallidus, and thalamus after cerebral injury. Glial cells in the cortex and corpus callosum underwent delayed FJB staining from d7 to d28, but neurons in cortex disappeared within the first week of cerebral injury. Striatal lesion core and globus pallidus of A beta + ET1 rats showed extensive degeneration of neuronal cells compared with ET1 rats alone starting from d1. Differential and exacerbated expressions of cyclooxygenase-2 might be the cause of excessive neuronal demise in the striatum of A beta + ET1 rats. Such an investigation may improve our understanding to identify and manipulate a critical therapeutic window post comorbid injury.

Automated summary

The combination of ischemia and A beta toxicity in brain injury leads to increased neuro-inflammation, A beta deposition, and neurodegeneration. This study found regional differences in cellular degeneration post cerebral injury, with delayed FJB staining in glial cells in the cortex and corpus callosum, and early disappearance of neurons in the cortex. Additionally, A beta + ET1 rats showed extensive degeneration of neuronal cells, potentially due to exacerbated expressions of cyclooxygenase-2 in the striatum.