A new model for the study of high-K+-induced preconditioning in cultured neurones: Role of N-methyl-d-aspartate and α7-nicotinic acetylcholine receptors

Spreading depression (SD), whether elicited by local application of high K+ medium to the cortical surface or by other stimuli, can increase the brain's tolerance to a subsequent, severe ischaemic insult in vivo, a phenomenon termed preconditioning. Herein, we have developed and validated a robust in vitro protocol for high-K+-preconditioning of cultured neurones. This new model is especially appropriate to unravel the molecular mechanisms underlying neuronal preconditioning and subsequent ischaemic tolerance. With this new, optimised preparation, preconditioning was found to be dependent upon culture day in vitro, cell density, K+ concentration and duration of treatment. Finally, preconditioning was shown to be dependent upon N-methyl-d-aspartate (NMDA), CAM-kinase II signalling and α7-nicotinic (α7 nACh) receptor function, which is analogous to in vivo preconditioning induced by various stimuli.