THE effect of the 5-HT4 agonist, BIMU-8 was studied on [(3)]choline outflow
in guinea pig brain slices and synaptosomes. BIMU-8 did not modify [(3)]ch
oline efflux in slices kept at rest, but increased [H-3]choline outflow in
electrically stimulated slices of cerebral cortex (CC), hippocampus (hip) a
nd nucleus basalis magnocellularis (nbm). This effect was prevented by the
selective 5-HT4 antagonist, GR 125487. Conversely, BIMU-8 did not affect [H
-3]choline efflux in hippocampal synaptosomes depolarized with KCI 20mM. Th
ese results provide evidence that BIMU-8 increases the electrically trigger
ed [H-3]choline efflux in CC, hip and nbm slices. A possible role of 5-HT4
agonists in memory and learning diseases is suggested. (C) 1999 Lippincott
Williams & Wilkins.