GLUCOCORTICOIDS STIMULATE TRH AND C-FOS C-JUN GENE COEXPRESSION IN CULTURED HYPOTHALAMIC NEURONS/

To explore whether the protooncogenes, c-fos/c-jun, might be involved in regulating the effect of glucocorticoids on thyrotropin-releasing h ormone in fetal rat diencephalic neurons, their localization and trans criptional activity were investigated using double-labeled in situ hyb ridization, Northern blot and nuclear run-on assays. The results showe d that TRH mRNA was coexpressed with both c-jun and c-fos in the same neurons. Treatment with dexamethasone, a synthetic glucocorticoid, at 10(-8) M, enhanced transcriptional activity resulting in an increase i n both cell number and intensity of all three mRNAs. The existence of c-fos/c-jun in thyrotropin-releasing hormone neurons and the increased transcriptional activity following dexamethasone treatment suggests t hat these protooncogenes could mediate the effect of glucocorticoids o n thyrotropin-releasing hormone gene expression. (C) 1998 Elsevier Sci ence B.V.