Patterns of neurotransmitter receptor distributions following cortical spreading depression

Spreading depression (SD), a self-propagating depolarization of neurons and glia, is believed to play a role in different neurological disorders including migraine aura and acute brain ischaemia. Initiation and propagation of SD modulate excitability of neuronal network. A brief period of excitation heralds SD which is immediately followed first by prolonged nerve cell depression and later by an excitatory phase. The aim of the present study was to characterize local and remote transmitter receptor changes after propagation of cortical SD. Quantitative receptor autoradiography was used to asses 16 transmitter receptor types in combined striatum-hippocampus-cortex slices of the rat 1 h after induction of cortical SD. In neocortical tissues, local increases of glutamate NMDA, AMPA, and kainate receptor binding sites were observed. In addition to up-regulation of ionotropic glutamate receptors, receptor binding sites of GABAA, muscarinic M1 and M2, adrenergic α1 and α2, and serotonergic 5-HT2 receptors were increased in the hippocampus. Cortical SD also upregulated NMDA, AMPA, kainate, GABAA, serotonergic 5-HT2, adrenergic α2 and dopaminergic D1 receptor binding sites in the striatum. These findings indicate selective changes in several receptors binding sites both in cortical and subcortical regions by SD which may explain delayed excitatory phase after SD. Mapping of receptor changes by cortical SD increases our understanding of the mechanism of SD action in associated neurological disorders.