EXPRESSION OF CEREBELLAR SPECIFIC GLUTAMATE AND GABA(A) RECEPTOR SUBUNITS IN HETEROTOPIC CEREBELLAR GRAFTS

In the cerebellum, up-and downregulation of specific GABA(A) and NMDA receptor subunits coincide with granule cell migration and differentia tion. In this study, in situ hybridization techniques with GABA(A) and NMDA receptor subunit specific probes were employed to assess whether the molecular phenotype of heterotopically grafted cerebellar granule cells corresponds to that of normal cerebellum. The cerebellar anlage of rat fetuses was stereotactically grafted into the rostral striatum of adult rats. Eight weeks after transplantation, analysis demonstrat ed acquisition of an adult differentiation status reflected by abundan t GABA(A) alpha 6 and NR2C mRNA expression in granule cells. Complete lack of NR2B transcripts, molecular markers of immature granule cells, argues against persistence of undifferentiated cells. The data sugges t that intrinsic cell-autonomous factors largely determine the molecul ar commitment of granule cells and that a restricted specific environm ent is not necessary to promote granule cell differentiation. (C) 1997 Elsevier Science B.V.