NMDA-induced preconditioning attenuates synaptic plasticity in the rat hippocampus

Area of Science:

• Neuroscience
• Neurophysiology
• Synaptic Plasticity

Background:

• Glutamate preconditioning protects hippocampal slices against hypoxia.
• The role of glutamate receptor agonists and preconditioning effects on synaptic plasticity require further investigation.

Purpose of the Study:

• To investigate the preconditioning ability of glutamate receptor agonists.
• To determine the effects of preconditioning on synaptic plasticity in rat hippocampal slices.

Main Methods:

• Rat hippocampal slices were exposed to N-methyl-D-aspartate (NMDA) for chemical insult and preconditioning.
• Population spike potentials (PS) and paired pulse parameters were measured.
• Long-term potentiation (LTP) was assessed in field recordings.
• Effects of nitric oxide synthase inhibitors and adenosine receptor antagonists were evaluated.

Main Results:

• NMDA preconditioning significantly improved recovery from chemical insult-induced damage (33% to 69%).
• Preconditioning enhanced paired pulse depression but did not alter paired pulse facilitation.
• NMDA preconditioning reduced population spike long-term potentiation (PS-LTP) and field LTP.
• The observed effects on PS-LTP were NMDA receptor-dependent and blocked by nitric oxide synthase inhibitors.

Conclusions:

• NMDA preconditioning enhances recovery from acute insults in hippocampal slices.
• Preconditioning with NMDA may have detrimental effects on neuronal plasticity, specifically LTP.
• Nitric oxide signaling is implicated in the NMDA-mediated effects on synaptic plasticity.