Dopaminergic transplants in experimental parkinsonism: cellular mechanisms of graft-induced functional recovery.

The ability of intrastriatal grafts of fetal mesencephalic dopamine neurons to ameliorate the symptoms of experimental and clinical parkinsonism has raised the question of the mechanisms underlying the transplant-induced functional effects. Recent studies have taken advantage of quantitative cytochemical and in situ hybridization techniques to study functional graft-host interactions at the cellular level in the rat Parkinson model. The results provide evidence that behaviorally functional grafts restore dopaminergic neurotransmission and normalize dopamine receptor function in the denervated striatum, and that these effects are likely to depend on both synaptic and extrasynaptic mechanisms.