Stability and autolysis of cortical neurons in post-mortem adult rat brains

Abstract

We investigated the dynamics of autolytic damage of the cortical neurons in adult brains for 24 hours at room temperature (+20 degrees C) after cardiac arrest. The progressive histological and ultrastructural changes were documented using routine and immunohistochemical staining as well as electron microscopy. Our results demonstrated that there were no autolytic damages in the ultrastructure of cerebral neurons in the first 6 hours after warm cardiac arrest, in agreement with previous studies in other mammals. Interestingly, the activation of caspase-3 was observed in a significant number of neurons of the cerebellum and neocortex 9 hours following cardiac arrest. No significant changes related to autolysis were observed using amnio-cupric acid and Nissl (thionine) staining.

Keywords: Brain death; apoptosis; autolysis; caspase-3; cerebral anoxia; cerebral hypoxia.

Figure 1

Postmortem temperature changes of the animals’ carcasses.

Figure 2

A. Rat cortical neuron at1 hour after warm cardiac arrest. Intact cellular ultra-structures (scale bar — 0.5µm). B. Rat cortical neuron at 3 hours after warm cardiac arrest. The mitochondria are intact in general but some signs of its swelling just appeared (black arrows) (scale bar —0.5µm). C. Rat cortical neuron at 6 hours after warm cardiac arrest with vacuolization of RER (black arrows) (scale bar — 0.5µm). D. Rat cortical neuron at 9 hours after warm cardiac arrest. Mitochondria and nuclear membrane of the neuron are intact. Vacuolization of RER., disappearance of ribosomes, initial signs of autolysis and welling of the lysosome (black arrow) are seen (scale bar — 1.0µm). E. Rat cortical neuron at 12 hours after warm cardiac arrest. Autolysis, swelling of the lysosome (black arrow) are present (scale bar — 0.5µm). F. Rat cortical neuron at 24 hours after warm cardiac arrest. Cell autolysis, chromatolysis (black arrow) are seen (scale bar — 1.0µm).

Figure 3

A. and B. Absence of appreciable histological changes of the hippocampal neurons at 12 hours after warm cardiac arrest (H&E, ×100; ×400). C. Absence of the picnotic neurons at 9 hours after warm cardiac arrest (Nissl, ×400). D. Rouleaux formation (black arrow) of erythrocytes (blood sludge) in the cerebral cortex microcirculation at 1 hour after warm cardiac arrest (amino cupric silver method, ×400).

Figure 4

A. There is no activation of caspase-3 in the cerebellar cortex neurons’ cytoplasm 3 hours after warm cardiac arrest (caspase-3 immunostaining, ×400). B. Activation of caspase-3 in the neuron of cerebellar cortex (black arrow) at 3 hours after warm cardiac arrest (caspase-3 immunostaining, ×400). C. Activation of caspase-3 in the neuron of cerebellar cortex (black arrows) at 9 hours after warm cardiac arrest (caspase-3 immunostaining, ×400). D. Activation of caspase-3 in the neuron of cerebellar cortex (black arrows) at 12 hours after warm cardiac arrest (caspase-3 immunostaining, ×400).