Effect of dopamine agonists and antagonists on the electrical activity of substantia nigra neurons transplanted into the lateral ventricle of the rat.

Pieces of fetal rat mesencephalon containing the substantia nigra were transplanted into the lateral ventricle of rats pretreated with 6-OHDA injections into the ipsilateral substantia nigra. Extracellular recordings from these grafts revealed spontaneously active neurons with action potential waveforms and firing rates similar to those found in substantia nigra zona compacta in situ. Furthermore, local application of dopamine agonists inhibited, while dopamine antagonists increased zona compacta activity, both in situ and of cells from nigral grafts. We conclude that substantia nigra grafts contain spontaneously active neurons similar to those of zona compacta in situ, and that some of the mechanisms regulating nigral neuronal activity in situ are also present in this preparation.