GABAB, not GABAA receptors play a role in cortical postictal refractoriness

- Postictal refractoriness is present one min after cortical afterdischarges in rats.
- This refractoriness remains untouched by GABAA receptor antagonist.
- Whereas the GABAB receptor antagonist CGP35348 partly blocked refractoriness.

Postictal refractoriness may be taken as an expression of lasting activity of inhibitory systems arresting seizures. We tested drugs interfering with GABAergic inhibitory system in pairs of cortical epileptic afterdischarges induced with 1-min interval in rats. Under control conditions the second stimulation failed to elicit an afterdischarge. This postictal refractoriness was not affected by antagonists of GABAA receptors acting at three binding sites (bicuculline, picrotoxin, benzodiazepine inverse agonist Ro 19-4603) as well as by a less specific antagonist pentetrazol. In contrast, antagonist of GABAB receptors CGP35348 partially blocked the refractoriness. Cooperation of different inhibitory systems is probably necessary to abolish postictal refractoriness in neocortex.This article is part of the Special Issue entitled 'GABAergic Signaling in Health and Disease'.