Selective up-regulation of dopamine D1 receptors in dendritic spines by NMDA receptor activation

Abstract

Glutamate, by activating N-methyl-D-aspartate (NMDA) receptors, alters the balance between dopamine D1 and D2 receptor signaling, but the mechanism responsible for this effect has not been known. We report here, using immunocytochemistry of primary cultures of rat neostriatal neurons, that activation of NMDA receptors recruits D1 receptors from the interior of the cell to the plasma membrane while having no effect on the distribution of D2 receptors. The D1 receptors were concentrated in spines as shown by colocalization with phalloidin-labeled actin filaments. The effect of NMDA on D1 receptors was abolished by incubation of cells in calcium-free medium and was mimicked by the calcium ionophore ionomycin. Recruitment of D1 receptors from the interior of the cell to the membrane was confirmed by subcellular fractionation. The recruited D1 receptors were functional as demonstrated by an increase in dopamine-sensitive adenylyl cyclase activity in membranes derived from cells that had been pretreated with NMDA. These results provide evidence for regulated recruitment of a G protein-coupled receptor in neurons, provide a cell biological basis for the effect of NMDA on dopamine signaling, and reconcile the conflicting hyperdopaminergic and hypoglutamatergic hypotheses of schizophrenia. Increasing evidence indicates that interactions between different types of neurotransmitter receptors represent a major mechanism of neuronal plasticity. A variety of physiological and pharmacological stimuli alter the efficacy of ␣-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-mediated synaptic transmission (1, 2). These changes in signaling have been accounted for in large part by changes in the distribution of ␣-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors between spines and the interior of the cell (3, 4). Although signaling in the dopaminergic pathway also shows a great deal of plasticity, little information is available about its cellular basis. In the present study, we examined the possibility that an alteration in the distribution of dopamine receptors might contribute to the ability of N-methyl-D-aspartate (NMDA) to alter the balance between D1 and D2 receptor signaling pathways. Materials and MethodsCell Culture. Cultures of striatal neurons were prepared from 18-to 19-day rat embryos. The cells were plated on poly-D-lysinecoated glass coverslips and cultured in Eagle's MEM plus F-12 (1:1). The cultures were grown in the presence of 5% FBS, penicillin, or streptomycin (100 mg͞ml). To suppress the growth of glial cells, FBS was equilibrated with N2 (1%) 2 days after plating, and cytosine arabinoside (5 M) was added for 48 h to the culture medium on day 5. Cells were maintained in culture for 2-3 weeks before experiments; at that time, virtually all cells from embryonic rat striatum seemed to be mature neurons. They resembled typical medium spiny neurons and stained positively for neuronal markers (5).Immunostaining. Cells were fixed for 20 min in ice-cold 2% paraformaldehyde, permeabilized with 0....

Genetic NMDA Receptor Deficiency Disrupts Acute and Chronic Effects of Cocaine but not Amphetamine

“…Altered expression of NMDA receptors in medium spiny neurons could possibly affect the regulation of postsynaptic D1 and D2 dopamine receptors in the striatum (Scott et al, 2002;Gandolfi and Dall'Olio, 1993;Micheletti et al, 1992), thus modulating the effects of psychostimulants (Xu et al, 1994;Moratalla et al, 1996b;Chausmer and Katz, 2001). This possibility was studied by quantifying receptor levels with radioligand binding, and by measuring the behavioral effects of direct dopamine receptor agonists.…”

Dopamine Dysfunction in Borderline Personality Disorder: A Hypothesis

“…Glutamate upregulates DA D1 receptors by NMDA receptor activation (Scott et al, 2002). Any alteration in these mechanisms could cause an impairment of DA-modulated cognitive function (Jentsch et al, 1997).…”

Regulation of neuromodulator receptor efficacy—implications for whole-neuron and synaptic plasticity

“…Synapse-specific regulation has been shown conclusively in the short-term (137). NM receptors in synaptic positions are also anchored by scaffolding and anchoring proteins, which indicates that positioning of membrane receptors at a specific site is relevant to NM receptor action (138; 139).…”