D1/D2 receptor synergism on CREB DNA-binding activities in the caudate-putamen of rat.

Cyclic AMP-responsive element-binding protein (CREB) is a transcription factor that is activated by cyclic AMP-dependent protein kinase and regulates the induction of fos. In order to elucidate the cellular pathway of D1/D2 dopamine receptor synergism, the effect of D1 and D2 agonists on CREB DNA-binding activities was studied in the caudate-putamen of rats with an ipsilateral 6-hydroxydopamine-lesion of the medial forebrain bundle. Combined administration of D1 (SKF38393) and D2 (bromocriptine or quinpirole) agonists resulted in enhanced CREB-binding activities at a dose that did not enhance it when given separately. These results suggest that D1/D2 dopamine receptors play synergistic role in inducing CREB DNA-binding activities in the dopamine-depleted caudate-putamen of rats.