Severe Global Cerebral Ischemia-Induced Programmed Necrosis of Hippocampal CA1 Neurons in Rat Is Prevented by 3-Methyladenine: A Widely Used Inhibitor of Autophagy

Abstract

The true programmed mechanisms of delayed neuronal death induced by global cerebral ischemia/reperfusion injury remain incompletely characterized. Autophagic cell death and programmed necrosis are 2 kinds of programmed cell death distinct from apoptosis. Here, we studied the death mechanisms of hippocampal cornu ammonis 1 neuronal death after a 20-minute severe global ischemia/reperfusion injury in young adult rats and the effects of 3-methyladenine (3-MA), a widely used inhibitor of autophagy. The morphological changes detected by electron microscopy, together with the activation of autophagy, transferase-mediated UTP nick end-labeling-positive neurons, and delayed death, demonstrated that cornu ammonis 1 neuronal death induced in this paradigm was programmed necrosis. No significant activation of caspase-3 after injury was detected by Western blot and immunohistochemistry. Treatment with 3-MA provided time-dependent protection against cornu ammonis 1 neuronal death at 7 days of reperfusion when it was administered before ischemia; administration 60 minutes after reperfusion was not beneficial. The redistribution of the lysosomal enzyme cathepsin B after injury was inhibited by 3-MA administered before ischemia, suggesting that this might be another important mechanism for the protective effect of 3-MA in ischemic neuronal injury.

Increased Intracranial Pressure after Diffuse Traumatic Brain Injury Exacerbates Neuronal Somatic Membrane Poration but not Axonal Injury: Evidence for Primary Intracranial Pressure-Induced Neuronal Perturbation

“…In a model of spinal cord injury, cathepsin-B was shown upregulated with higher levels of activity at the epicenter of injury 5 days after injury (Ellis et al, 2005). The redistribution of cathepsin-B from the lysosomal compartment to the cytosol has previously been observed in vitro and after ischemic injury in vivo and is associated with an increase in neuronal death and dysfunction (Hill et al, 1997;Zhang et al, 2009;Kilinc et al, 2010;Oberle et al, 2010;Wang et al, 2011). In vitro cathepsin-B has been shown capable of precipitating cell death under various molecular stimuli within 24 hours when released from lysosomes with compromised membrane integrity in a pathway initiated by cleavage of Bid to form truncated-Bid.…”

Role of autophagy in the pathogenesis of multiple sclerosis

“…Activation of the autophagic pathway in ischemia leads to the death of astrocytes and neurons, which can be rescued by autophagy inhibitors [68,69] . Meanwhile, blockade of microglial autophagy in permanent middle cerebral artery occlusion by autophagy inhibitors reduces the severity of the disease [70] .…”

Ischemic Stroke Mechanisms, Prevention, and Treatment: The Anesthesiologist’s Perspective

“…Some experimental evidence suggests that reducing autophagy early after infarction can attenuate injury progression (71,(74)(75)(76). Conversely, other studies indicate that promoting autophagy may induce cells to undergo apoptotic rather than necrotic cell death, leading to reduced lesion sizes (71,77,78). Inadequate autophagy may also contribute to cell death in stroke (79).…”