Cortical spreading depression-induced preconditioning in mouse neocortex is lamina specific

Area of Science:

• Neuroscience
• Cellular Physiology
• Neuroprotection Research

Background:

• Cortical spreading depression (CSD) is known to provide neuroprotection against ischemia when applied days in advance.
• The potential for immediate neuroprotection via CSD has not been previously explored.

Purpose of the Study:

• To investigate the immediate neuroprotective effects of repeated cortical spreading depression (CSD) episodes.
• To determine the time course and cellular mechanisms of rapid CSD-induced preconditioning in mouse neocortical slices.

Main Methods:

• Repeated CSD induction at 15- and 30-minute intervals in mouse neocortical brain slices.
• Measurement of neuronal membrane depolarization and intracellular calcium in response to CSD.
• Assessment of neuroprotection using oxygen-glucose deprivation (OGD) models.
• Pharmacological inhibition of adenosine pathways (A1 receptors, ecto-5'-nucleotidase, nucleoside transporters).

Main Results:

• Repeated CSD at 15-minute intervals significantly reduced subsequent depolarization and calcium influx in layer V neurons, indicating preconditioning.
• This preconditioning effect diminished with a 30-minute interval, suggesting a duration of 15-30 minutes.
• A single CSD episode prolonged neuronal survival during OGD.
• Layer II/III neurons did not exhibit CSD-induced preconditioning, highlighting lamina specificity.
• Adenosine pathway inhibition (A1 receptor antagonist, ecto-5'-nucleotidase inhibition, nucleoside transporter blockade) partially or fully prevented preconditioning.

Conclusions:

• Rapid preconditioning by repeated CSD episodes occurs in layer V pyramidal neurons but not layer II/III neurons.
• This rapid neuroprotection is time-limited, lasting between 15 and 30 minutes.
• Adenosine signaling is the primary mediator of CSD-induced rapid preconditioning.