Disaggregation of Polyribosomes in Intact Gerbils Following Ischemia. An Ultrastructural Study

Adult gerbils were subjected to either unilateral or bilateral common carotid artery ligation for varying periods of time with varying durations of recovery. Selected brain regions were prepared for ultrastructural study after perfusion fixation. Dissociation of polyribosomes was observed in neurons but not in glial cells of the cerebral cortex and thalamus after 30 minutes of unilateral occlusion with no recovery period. At the other extreme, disaggregation was present in all brain regions studied after 60 minutes of bilateral occlusion followed by a 60-minute recovery period. Still longer recovery periods result in the appearance of some neurons with normally aggregated polyribosomes. The results suggest that a relatively long period of ischemia induces a derangement of neuronal protein synthesis that may persist for some time after restoration of circulation.