Endogenous ACh effects on NMDA-induced interictal-like discharges along the septotemporal hippocampal axis of adult rats and their modulation by an early life generalized seizure.

Purpose:   Our earlier findings of the modulation of cholinergic neurotransmission by an early life generalized seizure and the reported interaction between muscarinic and N-methyl-d-aspartate (NMDA) receptors prompted us to investigate the effects of endogenous acetylcholine (ACh) on the frequency (Hz) of the epileptiform discharges following NMDA-receptor activation in the hippocampal slice.

Methods:   A sustained (>20 min) generalized convulsion was induced in Sprague-Dawley juvenile rats by intraperitoneal injection with pentylenetetrazole (PTZ, 70-90 mg/kg) at postnatal day (P) 20. Temporal and septal hippocampal slices were prepared of normal (N) and PTZ-treated (PTZ) adult (≥P60) rats, and CA3 field potentials were recorded during perfusion with Mg(2+) -free artificial cerebrospinal fluid (ACSF) or with ACSF containing 50 μm 4-aminopyridine (4-AP).