In vitro radioautographic study of the monoaminergic innervation of cat red nucleus. Identification of serotoninergic terminals.

This study emphasizes the existence of a dense plexus of serotoninergic nerve terminals having specifically accumulated tritiated serotonin in vitro in the red nucleus of cat. These terminals innervate the whole rostrocaudal extension of the nucleus, being frequently in close apposition to the cell bodies and proximal dendrites of magnocellular neurons in its caudal part. A possible involvement of this serotoninergic input in the modulation of cerebello-rubro-spinal activity is proposed.