Oxoglutarate dehydrogenase complex controls glutamate-mediated neuronal death

Area of Science:

• Neuroscience
• Biochemistry
• Cell Biology

Background:

• Brain injury involves neuroinflammation, excitotoxicity from glutamate, and mitochondrial dysfunction, all contributing to neuronal death.
• Aneurysmal subarachnoid hemorrhage (SAH) is a critical condition involving these pathological mechanisms.

Purpose of the Study:

• To investigate the role of neuroinflammation, extracellular glutamate, and mitochondrial dysfunction in neuronal death following SAH.
• To elucidate the specific impact of nitric oxide (NO) on the 2-oxoglutarate dehydrogenase complex (OGDHC) and subsequent neuronal survival.

Main Methods:

• Retrospective analysis of SAH patient data.
• In vitro studies using rat cortex homogenate, primary neuronal cultures, and cell lines (B35, NG108-15).
• Techniques included high-resolution respirometry, electron spin resonance, fluorescent microscopy, enzymatic assays, and immunocytochemistry.

Main Results:

• Elevated extracellular glutamate and NO metabolites correlated with poor SAH outcomes.
• NO inhibited OGDHC more readily than mitochondrial respiration, causing glutamate accumulation and neuronal death.
• Thiamine (TH) reactivated OGDHC, reducing extracellular glutamate, calcium influx, and cell death across multiple cell types.

Conclusions:

• Loss of control over extracellular glutamate due to insufficient OGDHC activity is a critical driver of neuronal death in SAH.
• Thiamine's protective effect against glutamate toxicity highlights OGDHC reactivation as a potential therapeutic strategy.