Picrotoxin-, kainic acid- and seizure-induced Fos in brainstem, with special reference to catecholamine cell groups.

One of the original views about motor convulsions with bilateral synchronous EEG discharges was that ascending projections from deep midline brainstem neurons subserve discharge synchronisation. We examined this in kainic acid- and picrotoxin-induced seizures using the distribution of Fos protein expression in the brainstem as a possible marker of brainstem neuronal activation. Before seizure, Fos was present in parabrachial nucleus, central grey and A1/C1 cell groups and, to a lesser extent, in A2/C2 cell groups and A6 neurons. Seizure correlated with further induction of Fos in these cell groups as well as in A6 neurons. There was no Fos in other cell groups with bilateral cerebro-cortical projections nor in cell groups likely to participate in the expression of seizures, reflecting a limitation of the Fos method. This study provides evidence of locus coeruleus involvement in these two models of seizure.