Intracerebral dopaminergic transplants are not activated by electrical footshock stress activating in situ mesocorticolimbic neurons.

Male rats received a dopaminergic implant aimed either at the nucleus accumbens or the ventral tegmental area (VTA) following 6-hydroxydopamine lesion of their mesocorticolimbic dopaminergic system. Exposure to electrical footshock stress 6 months later markedly activated the mesocorticolimbic neurons in control animals as shown by the increase of dihydroxyphenylacetic acid (DOPAC) levels both in the nucleus accumbens and the VTA. However, no stress-induced activation was seen for the grafted neurons, irrespective of the area of implantation. These results indicate the lack of reinnervation and modulation of the grafted dopaminergic neurons by one of the important afferent systems regulating the activity of endogenous mesencephalic dopaminergic neurons.