Agonist stimulation provokes dendritic and axonal dopamine D-1 receptor redistribution in primary cultures of striatal neurons

To investigate the influence of neurotransmitter on G-protein-coupled recep tor trafficking and compartimentalization in neurons, we have developed a m odel of primary neuronal cultures from fetal rat striatum on which we have studied the cellular and subcellular distribution and trafficking of the D- 1 dopaminergic receptor. This receptor is known to be somatodendritic and a xonal targeted in vivo, mostly to extrasynaptic locations. Immunohistochemi cal studies at the light and electron microscopic levels showed that, in cu ltures, the D-1 dopaminergic receptor is expressed in the absence of dopami ne stimulation. The pattern of D-1 dopaminergic receptor immunostaining aft er stimulation by the D-1 dopaminergic receptor agonist SKF 82958 (1 mu M) is dramatically modified with a decrease of the number of labeled D-1 dopam inergic receptor puncta (- 40%) and an increase of their size in both dendr ites ( + 120%) and axons ( + 240%). Seven hours after removal of the agonis t, return to normal pattern was observed. The D-1 dopaminergic receptor ant agonist SCH 23390 (2 mu M) abolishes the effect of SKF 82958. Electron micr oscopy demonstrated, in dendrites, a translocation of the labeling from the plasma membrane to endosomes. Axonal D-1 dopaminergic receptor redistribut ion after acute stimulation indicates that the D-1 dopaminergic receptor is membrane targeted and responsive to stimulation. These results validate primary culture of striatal neurons to study subcell ular localization and intraneuronal trafficking of G-protein-coupled recept ors. This preparation will he useful to address various questions concernin g the behavior and the trafficking of these receptors in neurons in relatio n to the neurotransmitter environment. (C) 2000 IBRO. Published by Elsevier Science Ltd. All rights reserved.