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Plasticity in the Functional Properties of NMDA Receptors Improves Network Stability during Severe Energy Stress.

Nikolaus BueschkeLara Amaral-SilvaMin HuAlvaro AlvarezJoseph M Santin
Published in: The Journal of neuroscience : the official journal of the Society for Neuroscience (2024)
Brain energy stress leads to neuronal hyperexcitability followed by a rapid loss of function and cell death. In contrast, the frog brainstem switches into a state of extreme metabolic resilience that allows them to maintain motor function during hypoxia as they emerge from hibernation. NMDA receptors (NMDARs) are Ca 2+ -permeable glutamate receptors that contribute to the loss of homeostasis during hypoxia. Therefore, we hypothesized that hibernation leads to plasticity that reduces the role of NMDARs within neural networks to improve function during hypoxia. To test this, we assessed a circuit with a large involvement of NMDAR synapses, the brainstem respiratory network of female bullfrogs, Lithobates catesbeianus Contrary to our expectations, hibernation did not alter the role of NMDARs in generating network output, nor did it affect the amplitude, kinetics, and hypoxia sensitivity of NMDAR currents. Instead, hibernation strongly reduced NMDAR Ca 2+ permeability and enhanced desensitization during repetitive stimulation. Under severe hypoxia, the normal NMDAR profile caused network hyperexcitability within minutes, which was mitigated by blocking NMDARs. After hibernation, the modified complement of NMDARs protected against hyperexcitability, as disordered output did not occur for at least one hour in hypoxia. These findings uncover state-dependence in the plasticity of NMDARs, whereby multiple changes to receptor function improve neural performance during metabolic stress without interfering with their normal role during healthy conditions.
Keyphrases
  • endothelial cells
  • cell death
  • neural network
  • climate change
  • magnetic resonance imaging
  • resting state
  • computed tomography
  • drug induced
  • functional connectivity
  • blood brain barrier
  • heat stress
  • respiratory tract