Acute 4-aminopyridine seizures increase the regional cerebral blood flow in the thalamus and neocortex, but not in the entire allocortex of the mouse brain.

Systemic injections of 4-aminopyridine precipitate epileptiform generalized seizures characterized mainly by shivering of the body, tail movements and tonic-clonic convulsions in rats and mice. However, only few details are known as concerns which brain regions are possibly affected and stimulated by the compound. The aim of the present study was to investigate the changes in regional cerebral blood flow in mice by using the lipophilic compound technetium-99m-hexamethyl-propyleneamineoxime (99mTc-HMPAO). Whilst the uptake of 99mTc-HMPAO was increased significantly in the neocortex and thalamus following the induction of acute 4-aminopyridine seizures, no such changes were observed in the allocortex of the mice. The increases in uptake in the neocortex and thalamus were completely prevented by carbamazepine (which abolished the symptoms of the seizure, too). The primary involvement of the neocortex and thalamus points to the importance of thalamocortical circuits in the precipitation and maintenance of experimental 4-aminopyridine convulsions.