[Transient brain ischemia: NMDA receptor modulation and delayed neuronal death]

Area of Science:

• Neuroscience
• Cellular Biology
• Pathophysiology

Context:

• Transient global ischemia, a condition of reduced blood flow, leads to oxygen-glucose deprivation in the brain.
• This deprivation triggers excitotoxicity, primarily through the excessive accumulation of glutamate.
• Specific neuronal populations, like hippocampal CA1 pyramidal neurons, exhibit heightened vulnerability to these ischemic insults.

Purpose:

• To review the neurophysiological, cellular, and molecular mechanisms underlying post-ischemic plasticity of NMDA receptors.
• To compare the plasticity and vulnerability of NMDA receptors in sensitive CA1 neurons versus resistant CA3 neurons.
• To discuss the implications for stroke treatment and the reasons behind the failure of clinical trials using NMDA receptor antagonists.

Summary:

• Ischemia-induced glutamate accumulation potentiates NMDA receptors, initiating cell death pathways in vulnerable neurons.
• Changes in the balance of protein tyrosine kinases/phosphatases and increased surface NMDA receptor density contribute to selective neuronal death.
• Understanding these mechanisms is crucial for developing effective stroke therapies.

Impact:

• Provides insights into the selective vulnerability of neuronal populations to ischemic injury.
• Highlights potential therapeutic targets for mitigating neuronal death after stroke.
• Offers explanations for the limited success of NMDA receptor antagonist therapies in clinical trials.