Cellular distributions of AMPA glutamate receptor subunits in fetal ventral mesencephalon transplants in the dopamine-depleted striatum of a rat

To demonstrate the cellular distributions of alpha-amino-3-hydroxy-5-methyl -4-isoxazolepropionate receptor subunits (GluR1, GluR2/3, and GluR4) in the intrastriatal grafts of a rat model of Parkinson's disease, immunocytochem istry was performed in 6-hydroxydopamine rats with intrastriatal transplant s of fetal ventral mesencephalon (VM). In the fetal VM (at embryonic day 15 ) in which the tyrosine hydroxylase (TH) immunoreactivity was intensely obs erved, no GluR subunit immunoreactivity was detected. Within the intrastria tal fetal VM grafts containing TH-positive cells, a large number of cells i mmunoreactive for GluR1 and GluR2/3 were observed. However, the GluR1- and GluR2/3-positive cells tended to locate homogeneously within the grafts and were composed of various cell sizes and shapes, mainly medium-sized and as piny cells. Weak GluR4-positive cells were seen in the grafts, although in some cases the staining was too faint to see any immunoreactive cells at al l. Double immunostaining revealed that a part of TH-positive cells in the g rafts was also immunopositive for GluR1 or GluR2/3. Both dopaminergic neuro ns and nondopaminergic neurons in the VM transplants appear to be modified functionally by glutamatergic afferents via various glutamate receptors, in cluding GluR1 and GluR2/3 and, to a lesser extent, GluR4. (C) 1998 Elsevier Science Inc.