INTRASTRIATAL GRAFTS OF FETAL MESENCEPHALIC CELL-SUSPENSIONS IN MPP-LESIONED RATS - A MICRODIALYSIS STUDY IN-VIVO()

The striatum of rats was lesioned by unilateral administration of MPP. Two weeks later, a suspension of fetal mesencephalic cells (FMC), ob tained from 14-day rat embryos, was injected into the lesioned striatu m. Two weeks after grafting, the success of implantation and recovery of dopamine function were assessed by tyrosine hydroxylase immunocytoc hemistry (TH) and the measurement of striatal dopamine content. In add ition, the extracellular concentrations of dopamine and dopamine metab olites were studied by microdialysis in vivo before and after perfusio n of MPP+ to induce dopamine release from vesicular stores. TH+ cell b odies were seen in the lesioned grafted striata, indicating that fetal cells survived in these striata. In addition, there was a marked incr ease in TH-immunoreactivity in the neuronal fibers and terminals in th e area surrounding the cell implant, suggesting a compensatory respons e of the host tissue which may involve fiber sprouting. Grafting induc ed a recovery in indices of dopamine function, including recovery in d opamine content, and basal and MPP+-induced dopamine release. Thus, gr afts of FMC may provide a significant recovery of dopamine function in MPP+-lesioned striata.