LEVELS of mRNAs encoding for subunits of glutamate receptors were measured by in situ hybridization in the rat striatum after unilateral injections of 6-hydroxydopamine in the substantia nigra. When compared with the contralateral striatum, levels of NMDAR1, GluR1 and GluR2 mRNAs were significantly higher in the dopamine-deafferented striatum. Comparison with saline-injected rats showed that the NMDAR1 and the GluR1 mRNA labelling was increased in the striatum ipsilateral to the lesion. In contrast, GluR2 mRNA labelling in 6-OHDA-injected rats was not different from that in saline-injected rats. These results support the hypothesis that experimental dopamine deafferentation induces functional changes at the level of glutamatergic synapses in the striatum.