The phosphodiesterase type 4 inhibitor, rolipram, enhances glucocorticoid receptor function

Previous studies have demonstrated that antidepressants can enhance glucocorticoid receptor (GR) translocation and function, possibly through activation of cAMP and downstream cAMP dependent protein kinases. Accordingly, we examined GR function in cells treated with rolipram, a phosphodiesterase (PDE) type 4 inhibitor that antagonizes cAMP breakdown. Compared with vehicle-treated cells, rolipram alone and in combination with dexamethasone significantly enhanced GR function as measured in both mouse L929 cells and rat C6 glioma cells stably transfected with reporter genes driven by upstream glucocorticoid response elements. Rolipram's facilitation of GR function was reversible by the GR antagonist, RU486, and was associated with reduced cytosloic GR binding, indicating rolipram enhancement of GR nuclear translocation. Finally, rolipram potently augmented GR enhancement by the antidepressant, desipramine. These findings broaden the potential pathways by which PDE type 4 inhibitors can influence cellular function and indicate that these agents may have special utility in disorders associated with impaired GR-mediated feedback inhibition.