Ultrastructural Study of Neuronal Death in Rat Hippocampus after Transient and Permanent Focal Cerebral Ischemia

Objective: Morphological changes of CA1 neurons in rat hippocampus after transient and permanent focal cerebral ischemia were studied to clarify the nature of postischemic cell death in the subfield. Materials and Methods: Male adult rats were divided into 3 groups: Control (Shamoperated), transient ischemic group (30 minutes of MCAO followed by 48 hours of reperfusion), and permanent ischemic group (48 hours of MCAO). After the mentioned times, deep anesthesia was induced in the rats and their brains were removed and processed for transmission electron microscopy (TEM) and evaluation. Results: Electron-microscopic examination on day 2 showed key morphological signs of apoptosis in the permanent ischemic group, while morphological signs of necrosis were observed in the transient ischemic group. Conclusion: These results suggest necrosis (as dominant mechanism of neuronal death after transient ischemia) and apoptosis (after permanent ischemia) to be involved in neuronal death.