Striatal NMDAR2B mRNA expression after bilateral cortical and unilateral nigral deafferentation.

We have studies by in situ hybridization histochemistry the regulation of NMDAR2B mRNA expression by dopaminergic (DA) and cortical glutamatergic afferent fibres in the rat striatum. The effects induced by a unilateral lesion of the medial forebrain bundle and a bilateral lesion of the sensorimotor cortex were analysed in the dorsal striatum 3 weeks after the lesions. Using a 35S-labelled specific oligonucleotide probe no change in NMDAR2B mRNA level was found in DA-depleted striatum compared with the normal rat striatum. However, following cortical lesions, the levels of NMDAR2B mRNA were significantly increased, specifically in the striatal projection area of the SM cortex. These results suggest that NMDAR2B mRNA expression is regulated by cortico-striatal fibres in a topographic manner.