The Effect of Reserpine on Transmission in the Spinal Cord

Engberg, I., A. Lundberg and R. W. Ryall. The effect of reserpine on transmission in the spinal cord. Acta physiol. scand. 1968. 72. 115–122. In unanesthetized acute spinal cats, in which monoamine oxidase is inhibited, an i.v. injection of reserpine gives a profound depression of transmission from the flexor reflex afferents (FRA) to primary afferents and motoneurones. The effect is similar to that evoked by the monoamhe precursors DOPA or 5-HTP including a release of late reflex actions from the FRA. In chrohic spinal cats reserpine has no effect on transmission from the FRA. The effect of reserpine is partially reversed by the 5-HT antagonist Deseril (which also partially reverses the effect of 5-HTP) but not by phenoxybenzamine (which reverses the effect of DOPA). It is postulated that reserpine acts by liberation of 5-HT from descending fibres. The possibility that reserpine also acts on transmission from the FRA through liberation of noradrenaline is discussed.