Distinct expression of phosphorylated N‐methyl‐D‐aspartate receptor NR1 subunits by projection neurons and interneurons in the striatum of normal and amphetamine‐treated rats

Abstract

N-methyl-D-aspartate (NMDA) receptors are heteromeric assemblies of subunits (NR1 and NR2A-D), and are enriched in the striatum. Receptor phosphorylation has recently been demonstrated on the NR1 subunit at three serine residues, 897, 896, and 890, which appear to correspond to the level of receptor activity. In this study, expression of phospho-specific NR1 subunits at serine 897 (pNR1S897), serine 896 (pNR1S896), or serine 890 (pNR1S890) in neurochemically identified neurons of the adult rat striatum was detected by using double-immunofluorescent labeling or combined in situ hybridization and immunohistochemistry. In both the dorsal and ventral striatum, pNR1S897 was expressed at high levels in projection neurons containing >55% dynorphin (striatonigral) and >90% enkephalin (striatopallidal) and in interneurons that were 100% positive for choline, >90% positive for parvalbumin, and >45% positive for somatostatin (co-containing neuropeptide Y and neuronal nitric oxide synthase). Low levels of pNR1S896 were present in a small portion of projection neurons (<15% for both populations of projection neurons) and were almost lacking in the three types of interneurons. Interestingly, pNR1S890 was exclusively expressed in most parvalbumin-containing interneurons (70-80%). Acute administration of a psychostimulant, amphetamine, increased the number of dynorphin-containing projection neurons and parvalbumin interneurons showing detectable levels of pNR1S896 and pNR1S890, respectively. These results demonstrate the distinct expression of phospho-NR1 subunits in different populations of striatal projection neurons and interneurons at variable levels in normal rats; they also demonstrate that phosphorylation of NR1, at least on serine 896 and 890 sites, is sensitive to drug exposure.

Quantitative Analysis of Brain Nuclear Phosphoproteins Identifies Developmentally Regulated Phosphorylation Events

“…For example, it has been demonstrated that acute administration of the psychostimulant, amphetamine, causes an increase in the phosphorylation of the N-methyl-D-aspartate receptor NR1 subunit at serine 890 and 896, but not serine 897 in the brain52. As depicted in Figure 5A and 5B, two different proteins, heterogeneous nuclear ribonucleoprotein C (hnRNP C) and methyl-CpG-binding protein 2 (MeCP2), exhibited distinct abundance distribution patterns of phosphorylation at different residues.…”

Individual and Combined Effects of Methamphetamine and Ketamine on Conditioned Place Preference and NR1 Receptor Phosphorylation in Rats

“…In the single-labeling study, quantifications of immunoreactivity were carried out by counting the total numbers and determining the relative intensities of neurons which were immunoreactive to pNR1S897 in different areas as follows: (i) five selected areas [dorsolateral (DL), dorsomedial (DM), ventrolateral (VL), ventromedial (VM), and central subdivisions] in the dorsal striatum (namely CPu) [22] (see fig. 1 A); (ii) the ventral striatum (namely NAc) histochemically subdivided into a core region and a shell region for measurement [33] (see fig.…”

“…NR1 shows phosphorylation at three distinct serine sites (897, 896, and 890) in the carboxyl tail region (intracellular domain). The previous study found that phosphorylated NR1 at serine 897 (pNR1S897) was expressed in the brains of the normal rats at the highest level amid three phosphorylated NR1 subunits (pNR1S897, pNR1S896, pNR1S890) [22] . It is an appropriate way to investigate the phosphorylation of NR1 serine 897 following the repeated drug exposure [22] , but the phosphorylation status of the NR1 has not been measured in the major regions (VTA and striatum) of reward system after chronic drug exposure.…”

“…5 A: b, d, f, h). There was no significant difference of fluorescence intensities between groups (p 1 0.05), but the data from counting positive neurons showed the significant difference between groups according to one-way ANOVA (F (3,22) = 5.645, p ! 0.01).…”

Comparative Effects of Acute or Chronic Administration of Levodopa to 6-OHDA-lesioned Rats on the Expression and Phosphorylation of N-methyl-d-aspartate Receptor NR1 Subunits in the Striatum

“…Subcellular localization and phosphorylation state of NR1 could determine properties of NMDA receptors [15]. Within NR1, phosphorylation by protein kinase C (PKC) and protein kinase A (PKA) occurs on serine residues 890 and 896 (S890 and S896) and serine 897 (S897), respectively, in the carboxy tail region of the protein [16,17]. NMDAelicited currents are enhanced by activation of PKC and PKA.…”