Transcortical polarization in rat inhibits spreading depression

Area of Science:

• Neuroscience
• Neurophysiology
• Glial Cell Biology

Background:

• Spreading depression (SD) is a wave of intense neuronal activity followed by a long-lasting depression of electrical activity in the brain.
• The precise mechanisms regulating extracellular potassium concentration during SD are not fully understood, with glial cells potentially playing a key role.

Purpose of the Study:

• To investigate the effect of cortical polarization on the occurrence and duration of spreading depression (SD) in rats.
• To explore the potential involvement of glial cells in modulating extracellular potassium levels during SD.

Main Methods:

• Spreading depression (SD) was induced in the cerebral cortex of rats using a needle prick.
• Direct current (DC) potential changes were recorded using microelectrodes to monitor SD.
• Anodal or cathodal polarization currents were applied to the cortical surface before, during, and after SD induction.

Main Results:

• Anodic polarization (10-20 microA) of the cortical surface successfully blocked SD in the entire grey matter.
• Cathodic polarization produced similar blocking effects.
• Recovery of SD, in terms of both propagation and amplitude, was observed 45-60 minutes after polarization ceased.
• These polarization and recovery effects were reproducible within the same animal.

Conclusions:

• Cortical polarization is an effective method for blocking spreading depression (SD) in rats.
• The prolonged recovery period suggests significant alterations in the brain's ionic environment during and after polarization.
• These findings support further research into the role of glial cells in regulating extracellular potassium during SD.