Calpain inhibitors block long-term potentiation

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Long-term potentiation (LTP) is a crucial form of synaptic plasticity.
• LTP serves as a cellular model for learning and memory processes.
• The specific role of calpains in LTP mechanisms requires further elucidation.

Purpose of the Study:

• To investigate the involvement of calcium-activated thiol proteases (calpains) in the biochemical mechanisms of LTP.
• To evaluate the efficacy of novel, potent calpain inhibitors in blocking LTP.

Main Methods:

• Extracellular application of novel calpain inhibitors (N-acetyl-Leu-Leu-norleucinal and N-acetyl-Leu-Leu-methioninal) in rat hippocampal slices.
• Assessment of LTP in the Schaffer collateral-CA1 synaptic zone and perforant path-stimulated dentate granule cells.
• Evaluation of inhibitor effects on baseline synaptic transmission and timing of application relative to tetanic stimulation.

Main Results:

• Newly developed calpain inhibitors potently blocked LTP in both hippocampal slice and intact hippocampus preparations.
• These inhibitors did not alter baseline synaptic transmission.
• LTP blockade was observed when inhibitors were applied before, but not after, tetanic stimulation.
• The less potent calpain inhibitor leupeptin also blocked LTP at sufficient concentrations.

Conclusions:

• Calpains play a critical role in the induction or early maintenance of LTP.
• Novel calpain inhibitors are effective tools for dissecting the molecular pathways of synaptic plasticity.
• Targeting calpains may offer therapeutic avenues for modulating learning and memory.