Desensitization of D1 dopamine receptors down-regulates the Gsα subunit of G protein in SK-N-MC neuroblastoma cells

The effect of long-term (72 h) treatment with dopamine D1 receptor agonists, SKF 38393 and dopamine on D1 dopamine receptor and G-protein (GSα) was investigated in SK-N-MC neuroblastoma cells. The prolonged treatment of cells with 10 μM SKF 38393 or 10 μM dopamine resulted in a decrease in dopamine D1 receptor by 41 and 81%, respectively, as measured by specific antagonist [3H]SCH 23390 binding. Similary, the prolonged treatment of SK-N-MC cells with 10 μM SKF 38393 or 10μM dopamine resulted in a reduction of the level of GSα subunit of G-protein. The results indicate that agonist-induced down-regulation of D1 dopamine receptor may also modulate G-proteins.