Reduced hippocampal expression of dopamine D1 receptor in sandy mice.

<p>(A) Expression levels of mRNAs for serotonin 5-HT₄ receptor relative to those of GAPDH in the hippocampus (n = 10 each). (B) Relative expression levels of mRNAs for dopamine D₁ receptor in the hippocampus were reduced in mutant mice as compared with wild-type mice (+/+: 6.04±0.17; −/−: 5.16±0.2, n = 10 each; <i>p</i> = 0.0068).</p

Basic properties of synaptic transmission at mossy fiber synapse.

<p>(A) Input-output relationship at the mossy fiber-CA3 synapse. The amplitude of the presynaptic fiber volley (left) and fEPSP (right) was plotted against the stimulus intensity (n = 15 slices each). (B) Frequency facilitation induced by repetitive stimulation was reduced in mutant mice at the stimulus frequency of 0.2 Hz (+/+: 54.0±2.8% increase, n = 8; −/−: 42.9±3.3% increase, n = 11; <i>p</i> = 0.039), but not at 1 Hz (+/+: n = 7; −/−: n = 10). (C) No significant difference in facilitation of fEPSP induced by paired stimulation (+/+: n = 8; −/−: n = 9).</p

Passive and active somatic membrane properties of dentate granule cells.

<p>(A) Reduced input resistance in mutant mice (+/+: 494.8±48.4 MΩ, n = 12 cells; −/−: 373.6±33.4 MΩ, n = 14 cells; <i>p</i> = 0.0477).v (B) Shorter membrane time constant in mutant mice (+/+: 33.2±2.2 ms; −/−: 24.9±1.4 ms; <i>p</i> = 0.0109). (C–F) There was no significant difference in resting membrane potentials (C), the current intensity to evoke a single spike (D), the maximal number of spikes during sustained depolarization (E), or spike amplitude (F).</p

Synaptic potentiation induced by forskolin at mossy fiber synapse.

<p>(A) Pooled data showing potentiation of mossy fiber synaptic transmission by bath-applied forskolin (10 µM). There was no significant difference in the magnitude of potentiation between wild-type and mutant mice (<i>p</i> = 0.6905, n = 5 each). The effect of serotonin examined in the same mice was shown in (B) and was larger in mutant mice (<i>p</i> = 0.0159). (B) Significant correlation between serotonin- and forskolin-induced synaptic potentiation in mutant mice (r² = 0.8177, <i>p</i> = 0.00351), but not in wild-type mice (r² = 0.5067, <i>p</i> = 0.1775).</p

A Naturally Occurring Null Variant of the NMDA Type Glutamate Receptor NR3B Subunit Is a Risk Factor of Schizophrenia

<div><p>Hypofunction of the <i>N</i>-methyl-D-aspartate type glutamate receptor (NMDAR) has been implicated in the pathogenesis of schizophrenia. Here, we investigated the significance of a common human genetic variation of the NMDAR NR3B subunit that inserts 4 bases within the coding region (insCGTT) in the pathogenesis of schizophrenia. The cDNA carrying this polymorphism generates a truncated protein, which is electrophysiologically non-functional in heterologous expression systems. Among 586 schizophrenia patients and 754 healthy controls, insCGTT was significantly overrepresented in patients compared to controls (odds ratio = 1.37, <i>p</i> = 0.035). Among 121 schizophrenia patients and 372 healthy controls, genetic analyses of normal individuals revealed that those carrying insCGTT have a predisposition to schizotypal personality traits (<i>F_1,356</i> = 4.69, <i>p</i> = 0.031). Furthermore, pre-pulse inhibition, a neurobiological trait disturbed in patients with schizophrenia, was significantly impaired in patients carrying insCGTT compared with those with the major allele (<i>F_1,116</i> = 5.72, <i>p</i> = 0.018, <i>F_1,238</i> = 4.46, <i>p</i> = 0.036, respectively). These results indicate that a naturally occurring null variant in NR3B could be a risk factor of schizophrenia.</p></div

Clinical characteristics of patients with schizophrenia and healthy controls.

<p>Data are shown mean (standard deviation). CPZeq: chlorpromazine equivalent of total antipsychotics.</p><p>IQ: Intelligence Quotient, PANSS: Positive and Negative Symptom Scale.</p

Neuromelanin imaging in the midbrain.

<p>A, C: 30-year-old male with schizophrenia, CR_SN = 12.9, CR_LC = 10.7; B, D: 26-year-old female healthy control, CR_SN = 6.2, CR_LC = 7.6 Demonstrating a region of interest drawn around the substantia nigra and midbrain tegmentum side on Figure 1B and locus ceruleus on Figure 1D.</p

Effect of insCGTT type on distribution of NR3B in HEK293T cells.

<p><b>A</b>, HEK293T cells transfected with GluR1 tagged with GFP at the extracellular N-terminus or intracellular C-terminus were stained with a GFP antibody under non-permeabilized conditions on ice, as verification of the specificity of cell surface receptor detection using immunostaining. <b>B</b>, HEK293T cells transfected with GFP-tagged NR3B major type or insCGTT type (green) were stained with GFP antibody under non-permeabilized condition to detect the cell surface population (surface GFP, red). <b>C</b>, Quantification of the surface levels of NR3B major type and insCGTT type with and without NR1. Because expression level of major type and insCGTT were different, the level was normalized by total GFP fluorescence in each cell. Data are expressed as a normalized value to that of major type alone. n = 55, 52, 59, and 52 for GFP-NR3B major type only, GFP-NR3B major type with NR1, GFP-NR3B insCGTT type only, and GFP-NR3B insCGTT type with NR1, respectively. *: p < 0.05; **: p < 0.01; ns: not significant. <b>D</b>, Surface biotinylation of NR3B major type and insCGTT type. GFP-tagged NR3B major type or insCGTT type was coexpressed with NR1 in HEK293T cells and the surface population was labeled by biotin. NR3B types in both total (T) and biotinylated surface population (S) were detected by anti-GFP antibody. Total fractions represent 1/8 of the starting material applied in surface fractions. α-Tubulin (Tub), an intracellular protein, was not biotinylated, confirming specificity of surface biotinylation.</p

Glutamate-induced whole-cell current recorded from HEK293T cells expressing major type or insCGTT type NR3B.

<p><b>A</b>, Sample traces of glutamate-induced whole-cell current recorded in HEK293T cells coexpressing NR1 and NR2A with or without NR3B major type or insCGTT type. The recordings were performed at -60 mV in the presence of 10 μM glycine and in the absence of Mg²⁺. <b>B</b>, The normalized current amplitude from cells without NR3B, with NR3B major type or insCGTT type. The major type NR3B suppressed the current to a statistically significant level, whereas insCGTT type did not show such suppression. The time course of current decay reflects the clearance of puffed glutamate from extracellular fluid by perfusion rather than the kinetics of channel opening and closing. n = 14, each. **: p<0.01 from control, *: p<0.05 from major type, ns: not significant.</p

Neuromelanin imaging characteristics of patients with schizophrenia and healthy controls.

<p>SR, signal ratio; SNc, substantia nigra; LC, locus coeruleus; CR_SN, contrast ratio of SNc; CR_LC, contrast ratio of LC;</p><p>MaxSR, maximum signal intensity.</p><p>Data are presented as mean ± standard deviation.</p><p>*p<0.05 compared to controls,</p>$<p>p<0.005 compared to controls.</p