Dopamine tone regulates D1 receptor trafficking and delivery in striatal neurons in dopamine transporter-deficient mice.

In vivo, G protein-coupled receptors (GPCR) for neurotransmitters undergo complex intracellular trafficking that contribute to regulate their abundance at the cell surface. Here, we report a previously undescribed alteration in the subcellular localization of D1 dopamine receptor (D1R) that occurs in vivo in striatal dopaminoceptive neurons in response to chronic and constitutive hyperdopaminergia. Indeed, in mice lacking the dopamine transporter, D1R is in abnormally low abundance at the plasma membrane of cell bodies and dendrites and is largely accumulated in rough endoplasmic reticulum and Golgi apparatus. Decrease of striatal extracellular dopamine concentration with 6-hydroxydopamine (6- OHDA) in heterozygous mice restores delivery of the receptor from the cytoplasm to the plasma membrane in cell bodies. These results demonstrate that, in vivo, in the central nervous system, the storage in cytoplasmic compartments involved in synthesis and the membrane delivery contribute to regulate GPCR availability and abundance at the surface of the neurons under control of the neurotransmitter tone. Such regulation may contribute to modulate receptivity of neurons to their endogenous ligands and related exogenous drugs.