Inhibition by GABA, baclofen and gabapentin of dopamine release from rabbit caudate nucleus: Are there common or different sites of action?

Slices of rabbit caudate nucleus were preincubated with [ 3H]dopamine then superfused and stimulated electrically. Baclofen, GABA and gabapentin 10 −4 and 10 −3 mol/l reduced the stimulation-evoked overflow of tritium in a similar manner. The effects of the substances were reinvestigated while one of them was present in a high concentration throughout the superfusion. These interaction experiments showed that baclofen and GABA have a common presynaptic site of action which is different from that of gabapentin.