Glutamate and dopamine receptors contribute to the lateral spread of epileptiform discharges in rat neocortical slices

Abstract

SUMMARYPurpose: The effects of AMPA-type glutamate receptor as well as dopamine D1 and D2 receptors on the lateral propagation of epileptiform field potentials (EFP) were studied across adjacent areas of rat neocortical tissues. Methods: Epileptiform burst discharges were induced by superfusion of Mg 2+ -free artificial cerebrospinal fluid. Simultaneous field potential recordings of EFP were obtained from four microelectrodes placed 2-3 mm apart across coronal slices in the third layer of the neocortex. The effects of AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), dopamine D1 receptor agonist SKF 81297, and dopamine D2 receptor agonist quinpirole on lateral propagation of burst discharges were investigated. Results: CNQX, applied focally between recording sites, blocked rapid propagation across treated areas and resulted in the emergence of spatially separate, independent pacemakers. Focal application of SKF 81297 between recording sites increased the repetition rate of EFP, but reduced the amplitude as well as the duration of epileptic discharges. However, addition of SKF 81297 to the bath medium abolished EFP. Both local and systemic applications of quinpirole irreversibly enhanced repetition rate of epileptiform burst discharges. Conclusions: The results indicate the prerequisite of AMPA synaptic transmission for synchronized lateral propagation of Mg 2+ -free ACSFinduced epileptic activity and the modulatory effects of dopamine D1 and D2 receptors on both EFP initiation and propagation in epileptic tissues.

Propagation of cortical spreading depression into the hippocampus: The role of the entorhinal cortex

“…EC was the bottommost of the slices in the chamber that superfused by ACSF. Drugs were applied in the same direction of the ACSF flow directly over EC to prevent drug diffusion to the other parts of the slice (Goda et al, ; Gorji et al, ). (iv) Forty‐five minutes after the first KCl injection, the second KCl application was performed (CSD 2).…”

Spatiotemporal dynamics of high-K+-induced epileptiform discharges in hippocampal slice and the effects of valproate

“…The propagation of epileptiform discharges can be understood as a pulse of synchronous activity transmitted from one neuronal population to the next, involving a rapid process during which neighboring neurons are recruited to generate discharges throughout the spatial extent of the network [7] . Previous studies have revealed that an improved understanding of the propagation patterns of epileptiform discharges, such as pathways and speed, could provide valuable insights into understanding the mechanisms of epileptogenesis and lead to better treatment of patients with epilepsy [8][9][10][11] .…”