Regulation of striatal dopamine receptors by corticosterone: an in vivo and in vitro study

Abstract The effects of chronic corticosterone administration and adrenalectomy on the expression of brain dopamine receptors were studied in rats. In situ hybridization and receptor binding autoradiography were carried out to determine D 1 , D 2 and D 3 receptor expression in dorsal and ventral striata. Except for down-regulation of D 2 mRNA in dorsal striatum after 2 week corticosterone treatment, no other significant changes were detected. In addition, the transcriptional regulation of D 1 and D 2 gene promoters by glucocorticoids was studied in neuroblastoma cell lines using transient transfections. While a small segment of the D 2 -promoter could be activated three-fold by dexamethasone, large fragments of neither D 1 or D 2 promoters were regulated by this treatment. Glucocorticoids do not appear to have direct overall effects on striatal dopamine receptor expression. The observed down-regulation of D 2 receptor mRNA in the dorsal striatum in vivo is likely secondary to increased striatal dopamine release induced by corticosterone.