Quenching revisited: Low level direct current inhibits amygdala-kindled seizures

We have reported that low frequency stimulation (1 Hz for 15 min), applied after kindling stimulation of the amygdala, inhibited the development and e xpression of amygdala-kindled seizures, an effect we termed quenching. Subs equently we discovered that this effect could only be achieved when certain stimulators were used that also emitted a low-level direct current (DC). T he studies reported here indicate that DC, applied once daily for 15 min at intensities of 5-15 mu A, produced an intensity-related attenuation of kin dling development and an increase in the afterdischarge threshold. This eff ect persisted in some animals for at least 1 month after discontinuation of the DC. In fully kindled animals, a robust increase in seizure threshold a nd persistent seizure inhibition were also observed using 10 mu A of DC adm inistered for 14 days. These results clarify and extend our original findin gs of a quenching effect; however, the mechanisms by which low level DC ind uces quenching require further elucidation.