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The role of the acetylcholine-mediated system in the organization of postictal antinociception was investigated. For this purpose, nicotinic and muscarinic cholinergic receptor antagonists were microinjected into the nucleus raphe magnus (NRM), a key structure of the endogenous pain inhibitory system. After the tail-flick test baseline recording, male Wistar rats (N=8 per group) were submitted to stereotaxic surgery for the introduction of a guide cannula aiming at the NRM. Five days after surgery, atropine or mecamylamine (1µg/0.2µL, 3µg/0.2µL, or 5µg/0.2µL) was microinjected into the NRM. The tail-flick withdrawal latency was recorded immediately after peripheral treatment with pentylenetetrazole (PTZ) (64mg/kg), in two different interictal time windows, and for 130minutes after the last seizure evoked by intraperitoneal injection of PTZ. The blockade of GABA-mediated Cl^– influx caused tonic–clonic convulsions in …