Cortical Spreading Depression (CSD) is the most likely culprit of the aura phase of migraine. It is, therefore, expected that antimigrainous treatments influence the onset or propagation of the spreading depression waves. Electrical stimulation triggers CSD via increase of the extracellular K⁺ concentration (Reid et al., 1987). The aim of the present study was to develop a reproducible protocol for electrical induction of CSD. Occurrences of CSD waves were recorded in the parietal or frontal cortices of anaesthetized male Sprague-Dawley rats. CSD was triggered by stimulation with near direct current (DC) charge-balanced biphasic pulse in the visual cortex using Teflon-coated stainless steel bipolar electrodes. The slow potential change, typically associated with CSD, was characterized by an initial slow negative recess followed by a more pronounced and faster main negative phase, a notch and slow repolarization and overshoot phases. It was found that proposed waveform could reproducibly induce CSD. The CSD waves propagated from the induction site to the distant recording sites in the cortex. The typical thresholds were found in the range of 700 - 1000 uA peak current amplitude. Finally, CSD induction was susceptible to NMDA receptor blockade by MK-801. Proposed waveform could be used in future studies of the physiology of CSD and for testing the effects of putative antimigrainous compounds on CSD.

Acknowledgement: 

The study was performed with the financial support of Cyberonics Ltd (Houston, Texas, USA) and Fonds Léon Frédéricq, University of Liege, Liege, Belgium.