NMDAR2B Research Articles

Charge-specific adverse effects of polystyrene nanoplastics on zebrafish (Danio rerio) development and behavior

Nanoplastics are being detected with increasing frequency in aquatic environments. Although evidence suggests that nanoplastics can cause overt toxicity to biota across different trophic levels, but there is little understanding of how materials such as differently charged polystyrene nanoplastics (PS-NP) impact fish development and behavior. Following exposure to amino-modified (positive charge) PS-NP, fluorescence accumulation was observed in the zebrafish brain and gastrointestinal tract. Positively charged PS-NP induced stronger developmental toxicity (decreased spontaneous movement, heartbeat, hatching rate, and length) and cell apoptosis in the brain and induced greater neurobehavioral impairment as compared to carboxyl-modified (negative charge) PS-NP. These findings correlated well with fluorescence differences indicating PS-NP presence. Targeted neuro-metabolite analysis by UHPLC-MS/MS reveals that positively charged PS-NP decreased levels of glycine, cysteine, glutathione, and glutamic acid, while the increased levels of spermine, spermidine, and tyramine were induced by negatively charged PS-NP. Positively charged PS-NP interacted with the neurotransmitter receptor N-methyl-D-aspartate receptor 2B (NMDA2B), whereas negatively charged PS-NP impacted the G-protein-coupled receptor 1 (GPR1), each with different binding energies that led to behavioral differences. These findings reveal the charge-specific toxicity of nanoplastics to fish and provide new perspective for understanding PS-NP neurotoxicity that is needed to accurately assess potential environmental and health risks of these emerging contaminants.

Inhibition of the NR2B–PSD95 Interaction Exerts Neuroprotective Effects on Retinal Ischemia–Reperfusion Injury

Glaucoma is a neurodegenerative disease characterized by progressive retinal ganglion cell (RGC) death. Recently, many studies have reported that the N-methyl D-aspartate receptor 2B (NR2B) subunit is excitotoxic in the pathogenesis of glaucoma, but the molecular mechanism should be further explored. In our present study, we investigated the involvement of the NR2B–postsynaptic density protein-95 (PSD95) complex in RGC apoptosis in an experimental glaucoma animal model and determined whether inhibition of the NR2B–PSD95 interaction protected RGCs. We found that levels of NR2B, phosphorylated NR2B (p-NR2B) and PSD95 were significantly increased after 12 h of reperfusion, and the protein expression levels were maintained after 24 h of reperfusion in the ischemia–reperfusion (I/R) injury model. Immunohistochemical staining showed that NR2B and PSD95 partially colocalized in the ganglion cell layer (GCL). Increased levels of NR2B and p-NR2B were also detected in the rat chronic ocular hypertension (COH) model, while decreased PSD95 levels accompanied by severe injury were observed. Tat-NR2B9c treatment significantly increased RGC survival in the I/R injury model by disrupting the NR2B–PSD95 interaction, as confirmed by Brn3A fluorescent labelling and TdT-mediated dUTP nick-end labelling (TUNEL) assays. Levels of the apoptosis-related proteins Bax and cleaved caspase-3 decreased as the number of surviving RGCs increased. Together, our results suggest that the NR2B–PSD95 complex was involved in RGC death in the retinal I/R injury model. Tat-NR2B9c exerted a neuroprotective effect on RGC survival in the retinal I/R injury model by disrupting the NR2B–PSD95 interaction.

Design, synthesis and biological evaluation of novel procaine derivatives for intravenous anesthesia

A series of novel procaine derivatives for intravenous anesthesia were prepared and evaluated by physicochemical properties and pharmacodynamic experiments in vivo and in vitro. Systematic optimization of procaine led to the identification of 6f, 6g, 6h, 6o, 6p and 6q with higher TI value and moderate log D. Compared with procaine (TI = 1.65), most procaine derivatives demonstrated better security, among whichcompound 6h (TI = 2.68)was the most notable one and showed fewer adverse events in animals. The result of hNR2B-HEK293 assay indicated that compound 6h suppressed the NMDA receptor 2B subtype channel activity and it showed more than 80% inhibitory effect at the concentration of 500 μM.

In utero exposure to methylmercury impairs cognitive function in adult offspring: Insights from proteomic modulation

Methylmercury (MeHg) is a hazardous substance that has unique neurodevelopmental toxic effects. However, its molecular alteration profile, sensitive response biomarkers, and mechanism of neuronal injury remain largely unknown. Here, the effects of intrauterine methylmercury chloride (low-, medium- and high-dose groups: 0.6 mg/kg/d, 1.2 mg/kg/d, 2.4 mg/ kg /d, respectively) exposure on learning and memory were assessed in offspring rats by behavioral tests, pathological analysis and hippocampal proteomic analysis. The results suggested that intrauterine MeHg exposure impairs spatial learning and memory and leads a significant reduction in the number and dispersion scattered arrangement in the hippocampus of offspring. Furthermore, in the tandem mass tag-based proteomics analysis, compared with the control group, a total of 74 differentially expressed proteins (DEPs) were found in the MeHg exposure groups; specifically, 32 down-regulated and 42 up-regulated proteins were identified. In addition, the pathways enrichment analysis indicated that these DEPs are implicated in several biological processes, such as synaptic plasticity and energy metabolism, as well as various molecular functional categories. Simultaneously, MeHg reduced the postsynaptic density, diminished the active zone, amplified the synaptic cleft and changed the synaptic interface of pyramidal cells. Western blot analysis further revealed that MeHg significantly reduced the levels of Forkhead box protein (FOXP2), Synaptophysin (SYP) and Postsynaptic density protein 95 (PSD-95), and down-regulated the N-methyl-D-aspartate receptor 1 (NMDAR1), N-methyl-D-aspartate receptor 2 A (NR2A) and N-methyl-D-aspartate receptor 2B (NR2B). In general, from a functional perspective, most overlapping proteins were related to NMDA receptor-mediated glutamatergic signaling, which is an excitotoxicity mechanism known to influence learning and memory. These discoveries contribute to our understanding of the relationship between MeHg and cognitive deficits and provide insight into the protein mediators of this relationship and possible prospective early biomarkers.

Mangiferin: Analgesic properties in neuropathic pain, molecular docking and meta-analysis

Aim: To investigate the analgesic effects of mangiferin (MAF) in experimental neuropathic pain (NPP) models and underlying mechanism. Methods: Databases including Pubmed, Web of Science, Embase, Cochrane Library, China national knowledge infrastructure (CNKI), Wangfang, and Weipu were used to search for the related studies. The search terms such as MAF, NPP, meta-analysis, rat, and mouse were used in various scientific databases. Meta-analysis was used to assay the analgesic efficacy of MAF. Further, molecular docking analysis was used to measure bindings of MAF and NPP-related proteins. Results: 6 studies were eventually included for the meta-analysis according to the inclusion and exclusion criteria. The meta-analysis results demonstrated that MAF significantly inhibited acetic acid-induced writhing responses, formalin-induced pain behavior, thermal analgesia, and mechanical allodynia as compared with the model control. However, risk of bias especially blinding existed in the included studies. The publication bias was checked by Begg's and Egger's tests. The molecular docking analysis indicated that MAF bound to 62 pain-related proteins at different levels. The top 10 predicted target proteins of MAF were glutamate carboxypeptidase II (GCPII), dopamine transporter (DAT), N-methyl-d-aspartic acid receptor 2B (NMDAR2B), transient receptor potential member 8 (TRPM8), monoamine oxidase type B (MAO-B), sodium voltage-gated channel alpha subunit 9A (SCN9A), fatty acid amide hydrolase (FAAH), gamma-secretase (GS), angiopoietin-1 (ANGPT1), and ANGPT2 based on the scores assessed by hydrogen bonding and hydrophobic interactions. Conclusions: In summary, MAF exerts the analgesic efficacy in the murine experimental pain models, which is associated with this compound binding to the NPP-related target proteins.

Inhibition of Spinal TRPV1 Reduces NMDA Receptor 2B Phosphorylation and Produces Anti-Nociceptive Effects in Mice with Inflammatory Pain.

Transient receptor potential vanilloid 1 (TRPV1) has been implicated in peripheral inflammation and is a mediator of the inflammatory response to various noxious stimuli. However, the interaction between TRPV1 and N-methyl-D-aspartate (NMDA) receptors in the regulation of inflammatory pain remains poorly understood. This study aimed to investigate the analgesic effects of intrathecal administration of capsazepine, a TRPV1 antagonist, on carrageenan-induced inflammatory pain in mice and to identify its interactions with NMDA receptors. Inflammatory pain was induced by intraplantar injection of 2% carrageenan in male ICR mice. To investigate the analgesic effects of capsazepine, pain-related behaviors were evaluated using von Frey filaments and a thermal stimulator placed on the hind paw. TRPV1 expression and NMDA receptor phosphorylation in the spinal cord and glutamate concentration in the spinal cord and serum were measured. Intrathecal treatment with capsazepine significantly attenuated carrageenan-induced mechanical allodynia and thermal hyperalgesia. Moreover, carrageenan-enhanced glutamate and phosphorylation of NMDA receptor subunit 2B in the spinal cord were suppressed by capsazepine administration. These results indicate that TRPV1 and NMDA receptors in the spinal cord are associated with inflammatory pain transmission, and inhibition of TRPV1 may reduce inflammatory pain via NMDA receptors.

Behavioral and neurobiological changes in a novel mouse model of schizophrenia induced by the combination of cuprizone and MK-801

Schizophrenia is a mental illness characterized by episodes of psychosis, apathy, social withdrawal, and cognitive impairment. White matter lesions and glutamatergic hypofunction are reported to be the key pathogeneses underlying the multiple clinical symptoms of schizophrenia. Cuprizone (CPZ) is a copper chelator that selectively injures oligodendrocytes, and MK-801 is an antagonist of the N-methyl d-aspartate (NMDA) receptor. To better mimic the psychosis and complicated pathogenesis of schizophrenia, a novel possible mouse model was established by the combination of CPZ and MK-801. After exposure to CPZ for 5 weeks, the mice received a daily intraperitoneal injection of MK-801 for 2-weeks. Behavioral changes in the mouse model were evaluated using Y-maze, object recognition, and open field tests. Pathological changes were observed by transmission electron microscopy, oil red O staining, immunohistochemistry, and western blotting. The results showed that the novel mouse model induced by CPZ plus MK-801 exhibited severe spatial and recognition memory deficits, hyperactivity, and anxiety disorder. Moreover, the mice showed obvious demyelination and white matter damage and decreased expression levels of myelin basic protein (MBP) and 2′,3′-cyclic nucleotide-3′-phosphodiesterase (CNPase) in the corpus callosum. Furthermore, the phosphorylation levels of Fyn and NMDA receptor 2B in the corpus callosum and NMDA receptor 1 in the cerebral cortex were noticeably decreased. Taken together, the novel mouse model induced by the combination of cuprizone and MK-801 showed comprehensive behavioral and neurobiological changes, which might make it a suitable animal model for schizophrenia.

Angiotensin II induces cognitive decline and anxiety-like behavior via disturbing pattern of theta-gamma oscillations

Hypertension is the most common chronic disease accompanied by cognitive decline and anxiety-like behavior. Angiotensin II (Ang II) induces hypertension by activating angiotensin II receptor subtype 1 (AT1R). The purpose of the study was to examine the potential underlying mechanism of alterations in cognition and anxiety-like behavior induced by Ang II. Adult C57 mice were intraperitoneal injected with either 1 mg/kg/d Ang II or saline individually for 14 consecutive days. Ang II resulted in cognitive decline and anxious like behavior in C57 mice. Moreover, Ang II disturbed bidirectional synaptic plasticity and neural oscillation coupling between high theta and gamma on PP (perforant pathway)-DG (dentate gyrus) pathway. In addition, Ang II decreased the expression of N-methyl-d-aspartate receptor (NR) 2A and NR 2B and increased the expression of GABAAR α1. The data suggest that Ang II disturb neural oscillations via altering excitatory and inhibitory (E/I) balance and eventually damage cognition and anxiety-like behavior in mice.

Resveratrol attenuates arsenic-induced cognitive deficits via modulation of Estrogen-NMDAR-BDNF signalling pathway in female mouse hippocampus.

Chronic inorganic arsenic (iAs) exposure induces deleterious effects on CNS including oxidative stress, cognitive deficits and altered brain neurochemistry. Little is known about the association between iAs and estrogen receptor expression in brain regions. Owing to the neuroprotective and estrogenic activities of resveratrol (RES), we examined the combined effects of arsenic trioxide (As2O3) and RES on neurobehavioural functions, estrogen signalling and associated neurochemical changes in mouse hippocampus. As2O3 alone (2 and 4mg/kg bw) or along with RES (40mg/kg bw) was administered orally for 45days to adult female mice. From days 33 to 45, open field, elevated plus maze and Morris water maze tests were conducted to evaluate locomotion, anxiety and learning and memory. On day 46, animals were euthanized and brain tissue and hippocampi obtained therefrom were processed for atomic absorption spectrophotometry and western blotting respectively. As2O3 alone exposure resulted in enhanced anxiety levels, reduced locomotion and impaired learning and memory. As2O3-induced behavioural deficits were accompanied by downregulation of estrogen receptor (ERα) expression with a concomitant reduction of BDNF and NMDAR 2B levels in the hippocampus. However, the behavioural alterations and expression of these markers were restored in RES-supplemented mice. Moreover, a dose-dependent iAs accumulation was observed in serum and brain tissues of mice receiving As2O3 alone whereas simultaneous administration of As2O3 with RES facilitated iAs efflux. These results suggest that reduced ERα expression with associated downregulation of BDNF and NMDAR 2B levels could be a mechanism by which iAs induces cognitive impairment; hence, the modulation of estrogen-NMDAR-BDNF pathway by RES represents a potential avenue to recover behavioural deficits induced by this neurotoxin.

Disposition of Proteins and Lipids in Synaptic Membrane Compartments Is Altered in Q175/Q7 Huntington's Disease Mouse Striatum.

Dysfunction at synapses is thought to be an early change contributing to cognitive, psychiatric and motor disturbances in Huntington’s disease (HD). In neurons, mutant Huntingtin collects in aggregates and distributes to the same sites as wild-type Huntingtin including on membranes and in synapses. In this study, we investigated the biochemical integrity of synapses in HD mouse striatum. We performed subcellular fractionation of striatal tissue from 2 and 6-month old knock-in Q175/Q7 HD and Q7/Q7 mice. Compared to striata of Q7/Q7 mice, proteins including GLUT3, Na+/K+ ATPase, NMDAR 2b, PSD95, and VGLUT1 had altered distribution in Q175/Q7 HD striata of 6-month old mice but not 2-month old mice. These proteins are found on plasma membranes and pre- and postsynaptic membranes supporting hypotheses that functional changes at synapses contribute to cognitive and behavioral symptoms of HD. Lipidomic analysis of mouse fractions indicated that compared to those of wild-type, fractions 1 and 2 of 6 months Q175/Q7 HD had altered levels of two species of PIP2, a phospholipid involved in synaptic signaling, increased levels of cholesterol ester and decreased cardiolipin species. At 2 months, increased levels of species of acylcarnitine, phosphatidic acid and sphingomyelin were measured. EM analysis showed that the contents of fractions 1 and 2 of Q7/Q7 and Q175/Q7 HD striata had a mix of isolated synaptic vesicles, vesicle filled axon terminals singly or in clusters, and ER and endosome-like membranes. However, those of Q175/Q7 striata contained significantly fewer and larger clumps of particles compared to those of Q7/Q7. Human HD postmortem putamen showed differences from control putamen in subcellular distribution of two proteins (Calnexin and GLUT3). Our biochemical, lipidomic and EM analysis show that the presence of the HD mutation conferred age dependent disruption of localization of synaptic proteins and lipids important for synaptic function. Our data demonstrate concrete biochemical changes suggesting altered integrity of synaptic compartments in HD mice that may mirror changes in HD patients and presage cognitive and psychiatric changes that occur in premanifest HD.

Oral Herb Medicine Paste Improves Learning and Memory Function in Elderly Spontaneous Hypertensive Rats

Background: Oral herb medicine paste (Gao-Zi-Yao) has long been a unique way for treating various diseases. The present study is to explore the effect of Gao-Zi-Yao on learning and memory function in elderly spontaneous hypertensive rats (SHR) and its possible mechanism. Methods: Male elderly SHR were received different doses of Gao-Zi-Yao for 4 weeks. Systolic blood pressure (SBP) and heart rate were monitored. Morris water maze was performed to test the learning and memory function of the rats. Number of neurons in hippocampus was counted by Nissl staining. Western blot was applied to detect the expressions of learning and memory function related proteins, N-methyl-d-aspartate receptor 2B (NMDAR 2B), glutamate receptor 1 (GluR1), phosphorylated-calmodulin-dependent protein kinase II (p-CaMK II), and phosphorylated-cAMP responsive element-binding protein (p-CREB) in rat hippocampus. Findings: Data showed that Gao-Zi-Yao reduced SBP in elderly SHR. The results of Morris water maze experiment showed that Gao-Zi-Yao dose-dependently improved learning and memory function. Number of neurons in the hippocampal dentate gyrus (DG) region of the elderly SHR was increased by Gao-Zi-Yao treatment. In addition, Gao-Zi-Yao elevated the protein expressions of NMDAR 2B, GluR1, p-CaMK II, and p-CREB in hippocampus. Interpretation: Gao-Zi-Yao decreases SBP and improves the learning and memory function of the elderly SHR by regulation of neuron number in hippocampal DG area and the expressions of learning and memory function related proteins. Funding Statement: This work was supported by the National Natural Science Foundation of China (81970422), Suzhou Municipal Science and Technology Bureau (SS201745, GSWS2019022, SYSD2020210), and 5th 333 Project of Jiangsu Province. Declaration of Interests: The authors stated 'not applicable.' Ethics Approval Statement: The experiments were performed in according with the National Institutes of Health Guidelines for the Use of Laboratory Animals (NIH, publication number 85-23, revised 1996.), which were approved by and performed according to guidelines for the care and use of animals established by Soochow University. All the herbs and other materials used in the preparation of Gao-Zi Yao were approved by National Health Commission of the People’s Republic of China.

Changes of CaM-CaMK-CREB signaling pathway and related neuron factors in hippocampus of rats after sevoflurane and propofol administration.

To investigate the changes of CaM-CaMK-CREB signaling pathway and related neuron factors in hippocampus of rats after sevoflurane and propofol administration. A total of 90 SD rats, half male and half female, were selected. They were randomized into anesthesia group (AG) and control group (CG), in which 30 rats under propofol anesthesia in the AG were included in group A, 30 rats under sevoflurane anesthesia were included in group B, and 30 rats under mixed ventilation of air and oxygen were included in the CG. Before (10 rats were killed in each group) and at the end of anesthesia (2 weeks of anesthesia and 7 days of Morris water maze test), rats were respectively killed and then an appropriate amount of hippocampus was separated. Human tumor necrosis factor-alpha (TNF-α), vascular endothelial growth factor (VEGF), calmodulin (CaM), calmodulin-dependent kinase Ⅱ a (CaMK II a), NMDA receptor 2B (NR2B), cysteine aspartate specific protease-3 mRNA (Caspase-3mRNA) and protein contents were detected. The latency of rats in group A and group B, as well as their times of crossing the original platform on 1, 4, and 7d were markedly higher than those of the CG, and those in group B were markedly lower than those in group A (p<0.001). The total distance of rats in group A and group B on 1, 4, and 7d was significantly higher than that of the CG, and that in group B was dramatically lower than that in group A (p<0.001). The speed of rats in the three groups ranged from 1d to 7d, and there was no significant difference at different time points (p>0.05). At the end of anesthesia, the expression levels of CaM mRNA and protein in hippocampus of rats in group A and group B were remarkably higher than those of the CG, and those of CaMK II a mRNA and protein were remarkably lower than those of the CG; the CaM mRNA and protein expression levels in hippocampus of group A were significantly higher than those of group B, and those of CaMK IL a mRNA and protein were significantly lower than those of group B (p<0.001). Simultaneously, the expression levels of NR2BmRNA, Caspase-3mRNA and protein in hippocampus of group A and group B were substantially higher than those of the CG, and those in group B were substantially lower than those in group A (p<0.001). What's more, the TNF-a and VEGF expression levels in hippocampus of group A and B were markedly higher than those of the CG, and those in group B were dramatically lower than those of group A (p<0.001). Sevoflurane anesthesia on the CaM-CaMK-CREB signaling pathway and learning and memory function of rats is less volatile, which does better in safeguarding stability.

Spontaneous motor-behavior abnormalities in two Drosophila models of neurodevelopmental disorders

Mutations in hundreds of genes cause neurodevelopmental disorders with abnormal motor behavior alongside cognitive deficits. Boys with fragile X syndrome (FXS), a leading monogenic cause of intellectual disability, often display repetitive behaviors, a core feature of autism. By direct observation and manual analysis, we characterized spontaneous-motor-behavior phenotypes of Drosophila dfmr1 mutants, an established model for FXS. We recorded individual 1-day-old adult flies, with mature nervous systems and prior to the onset of aging, in small arenas. We scored behavior using open-source video-annotation software to generate continuous activity timelines, which were represented graphically and quantitatively. Young dfmr1 mutants spent excessive time grooming, with increased bout number and duration; both were rescued by transgenic wild-type dfmr1+ . By two grooming-pattern measures, dfmr1-mutant flies showed elevated repetitions consistent with perseveration, which is common in FXS. In addition, the mutant flies display a preference for grooming posterior body structures, and an increased rate of grooming transitions from one site to another. We raise the possibility that courtship and circadian rhythm defects, previously reported for dfmr1 mutants, are complicated by excessive grooming. We also observed significantly increased grooming in CASK mutants, despite their dramatically decreased walking phenotype. The mutant flies, a model for human CASK-related neurodevelopmental disorders, displayed consistently elevated grooming indices throughout the assay, but transient locomotory activation immediately after placement in the arena. Based on published data identifying FMRP-target transcripts and functional analyses of mutations causing human genetic neurodevelopmental disorders, we propose the following proteins as candidate mediators of excessive repetitive behaviors in FXS: CaMKIIα, NMDA receptor subunits 2A and 2B, NLGN3, and SHANK3. Together, these fly-mutant phenotypes and mechanistic insights provide starting points for drug discovery to identify compounds that reduce dysfunctional repetitive behaviors.

Intrathecally Administered Apelin-13 Alleviated Complete Freund’s Adjuvant-Induced Inflammatory Pain in Mice

Apelin is the endogenous ligand for APJ, a G-protein-coupled receptor. Apelin gene and protein are widely distributed in the central nervous system and peripheral tissues. The role of apelin in chronic inflammatory pain is still unclear. In the present study, a mouse model of complete Freund’s adjuvant (CFA)-induced inflammatory pain was utilized, and the paw withdrawal latency/threshold in response to thermal stimulation and Von Frey filament stimulation were recorded after intrathecal (i.t.) injection of apelin-13 (0.1, 1, and 10 nmol/mouse). The mRNA and protein expression, concentration of glutamic acid (Glu), and number of c-Fos immunol staining in lumbar spinal cord (L4/5) were determined. The results demonstrated that Apln gene expression in the lumbar spinal cord was down-regulated in the CFA pain model. Apelin-13 (10 nmol/mouse, i.t.) alleviated CFA-induced inflammatory pain, and it exhibited a more potent antinociceptive effect than apelin-36 and (pyr)apelin-13. The antinociception of apelin-13 could be blocked by APJ antagonist apelin-13(F13A). I.T. apelin-13 attenuated the increased levels of Aplnr, Grin2b, Camk2d, and c-Fos genes expression, Glu concentration, and NMDA receptor 2B (GluN2B) protein expression caused by CFA. Apelin-13 significantly reduced the number of Fos-positive cells in laminae III and IV/V of the dorsal horn. This study indicated that i.t. apelin-13 exerted an analgesic effect against inflammatory pain, which was mediated by activation of APJ, and inhibition of Glu/GluN2B function and neural activity of the spinal dorsal horn.

Characterization of kynurenine pathway in patients with diarrhea-predominant irritable bowel syndrome.

Our objectives are to demonstrate whether the kynurenine pathway is activated in diarrhea-type irritable bowel syndrome (IBS-D) patients, and whether the neurotoxic metabolite quinolinic acid (QUIN) is out of balance with the neuroprotective metabolite kynurenic acid (KYNA), and further explore whether this can lead to increased expression of N-methyl D-aspartate receptor 2B (NMDAR2B) in the enteric nervous system and in turn leads to intestinal symptoms and mood disorders. All enrolled healthy controls and patients accepted IBS Symptom Severity Scale (IBS-SSS) score, Self-rating Depression Scale (SDS) and Self-rating Anxiety Scale (SAS) anxiety and depression scores, and also underwent colonoscopy to collect ileum and colonic mucosa specimens. The expression of NMDAR2B in intestinal mucosa was detected by immunofluorescence, and fasting serum was collected to detect the tryptophan, kynurenine (KYN), KYNA and QUIN by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Our results showed that the KYN pathway of IBS-D patients was activated. The production of QUIN and KYNA was imbalanced and resulting in an increased NMDAR2B for patients with IBS-D, which may be involved in intestinal symptoms and mood disorders of IBS-D.

Compound Chai Jin Jie Yu Tablets, Acts as An Antidepressant by Promoting Synaptic Function in the Hippocampal Neurons

ObjectiveTo investigate the effectiveness of compound Chai Jin Jie Yu Tablets (CJJYT) in ameliorating cognitive impairment associated with depression and its potential mechanism of action. MethodsIn vitro experiments, the hippocampus was isolated from the whole brain of the fetal rat and cultured into hippocampal neuron cells. 50 μM corticosterone (CORT) was added to each group 18 h before the experiment for modeling depression, with the exception of the control group. After modeling, the blank serum group was added with 10% blank serum, the CJJYT group and the venlafaxine group were added with the corresponding 10% drug-containing serum, and the control group and the model group were added with equal volumes of culture medium. The intracellular Ca2+ mean fluorescence intensity, miniature excitatory postsynaptic current (mEPSC) current amplitude, and frequency of different hippocampal neurons were evaluated as indicators of synaptic function in the hippocampal neurons. In addition, the expression of synaptic plasticity related proteins, synaptophysin-α (SYN-α), N-methyl-D-aspartate receptor 2A (NR2A), N-methyl-D- aspartate receptor 2B (NR2B), post synaptic density 95 protein (PSD-95), calcium/calmodulin dependent protein kinaseⅡ (CaMKⅡ) and synaptic associated protein (SynGAP) were detected in the hippocampal neurons by immunofluorescence staining and high content analysis (HCA) system. Then, reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the mRNA expression levels of SYN-α, NR2A, NR2B, PSD- 95, CaMKⅡ and SynGAP. For in vivo experiments, except for those in the blank control group, all rats were treated within a single cage for chronic unpredictable stress-induced depression modeling and subjected to corresponding drug interventions. Behavioral tests were used to detect depressive behavior and determine learning, memory and other cognitive abilities, whereas enzyme-linked immunosorbent assay (ELISA) was used to detect the CORT levels. Golgi-Cox staining was used to observe changes in the synaptic morphology of parahippocampal gyrus CA1 area (CA1) and dentategyrus (DG). ResultsIn vitro, CJJYT treatment reduced the intracellular Ca2+ mean flurorescence intensity in the hippocampal neurons (P < 0.05), causing a reduction in the frequency and current amplitude of mEPSC (P < 0.05), and thus inhibited the excessive activation of post-synaptic receptors. CJJYT treatment reduced the protein and mRNA expression of SYN-α, NR2A, NR2B and PSD-95 in the hippocampal neurons (P < 0.05), increased the mRNA and protein expression of CaMKⅡ and SynGAP (P < 0.05), and thereby improved the synaptic plasticity of the hippocampal neurons. In vivo, CJJYT intervention improved sucrose preference, voluntary activity , learning and memory ability of Morris water maze test, and suppressed appetite (P < 0.05), and increased the despair feeling of forced swimming test (P < 0.05). The CORT level was reduced (P < 0.05), leading to the repair of synaptic damage in the hippocampal neurons. ConclusionsCJJYT can improve the synaptic function of hippocampal neurons and has obvious protective effects on neurons. It can repair the structural damage in the hippocampal neurons, improving the cognitive ability of the depressed model rats. The mechanism of CJJYT improving cognition in depressed rats may be related to the transmission and function of SYN-α/NR and its downstream neurotransmitters.

PCC0208009, an indirect IDO1 inhibitor, alleviates neuropathic pain and co-morbidities by regulating synaptic plasticity of ACC and amygdala

Background and purposeIndoleamine 2, 3-dioxygenase 1 (IDO1) has been linked to neuropathic pain and IDO1 inhibitors have been shown to reduce pain in animals. Some studies have indicated that IDO1 expression increased after neuropathic pain in hippocampus and spinal cord, whether these changes existing in anterior cingulate cortex (ACC) and amygdala remains obscure and how IDO1 inhibition leads to analgesia is largely unknown. Here, we evaluated the antinociceptive effect of PCC0208009, an indirect IDO1 inhibitor, on neuropathic pain and examined the related neurobiological mechanisms. Experimental approachThe effects of PCC0208009 on pain, cognition and anxiogenic behaviors were evaluated in a rat model of neuropathic pain. Motor disorder, sedation and somnolence were also assessed. Biochemical techniques were used to measure IDO1-mediated signaling changes in ACC and amygdala. Key resultsIn rats receiving spinal nerve ligation (SNL), IDO1 expression level was increased in ACC and amygdala. PCC0208009 attenuated pain-related behaviors in the formalin test and SNL model and increased cognition and anxiogenic behaviors in SNL rats at doses that did not affect locomotor activity and sleeping. PCC0208009 inhibited IDO1 expression in ACC and amygdala by inhibiting the IL-6-JAK2/STAT3-IDO1-GCN2-IL-6 pathway. In addition, PCC0208009 reversed synaptic plasticity at the functional and structural levels by suppressing NMDA2B receptor and CDK5/MAP2 or CDK5/Tau pathway in ACC and amygdala. Conclusion and implicationsThese results support the role of IDO1-mediated molecular mechanisms in neuropathic pain and suggest that the IDO1 inhibitor PCC0208009 demonstrates selective pain suppression and could be a useful pharmacological therapy for neuropathic pain.

A Review on Chronic Pain in Rheumatoid Arthritis: A Focus on Activation of NR2B Subunit of N-Methyl-D-Aspartate Receptors.

Chronic pain is a debilitating condition that occurs after tissue damage, which substantially affects the patient’s emotional state and physical activity. The chronic pain in rheumatoid arthritis (RA) is the result of various autoimmune-induced inflammatory reactions in the joints. Both types of peripheral and central pain processing can lead to sensitisation. Non-steroidal anti-inflammatory drugs (NSAIDs) and disease-modifying anti-rheumatic drugs (DMARDs) can result in potent anti-inflammatory effect. However, these drugs are not able to suppress the pain from RA for a prolonged period. For years, researchers have examined the role of the N-methyl-D-aspartic acid receptor 2B (NR2B) subunit of N-methyl-D-aspartate receptors (NMDAR) in chronic and neuropathic pain models. This NMDAR subtype can be found in at the peripheral and central nervous system and it represents an effective therapy for RA pain management. This review focuses on the NR2B subunit of NMDAR and the different pathways leading to its activation. Furthermore, specific attention is given to the possible involvement of NR2B subunit in the peripheral and central pathogenesis of RA.

Age-related changes in the number of cresyl-violet-stained, parvalbumin and NMDAR 2B expressing neurons in the human spiral ganglion

Animal-studies associate age-related hearing loss (presbycusis) with decreasing number of spiral ganglion neurons (SGNs) in Rosenthal’s canal (RC) of cochlea. The excitatory neurotransmitter for SGNs is glutamate (through its receptor NMDAR 2B), which can be neurotoxic through Ca2+ overload. Neurotoxicity is balanced by calcium-binding proteins (CBPs) like Parvalbumin (PV), which is the predominant CBP of the SGNs. To estimate the volume of the RC and total number of SGNs that are immunoreactive to PV and NMDAR 2B, we used unbiased stereology in 35 human cochleae derived from cadavers of persons from 2nd to 8th decade of life (subsequently statistically divided into two groups) and compared them to the total number of cresyl violet (CV) stained SGNs. We also estimated the volume of individual neurons and their nuclei. Regression analysis was made on estimated parameters against age. Hierarchical-cluster analysis was done on the neuronal against neuronal nuclear volumes.The average volume of the RC did not change with increasing age (p = 0.4115). The total number of SGNs (CV-stained and those separately expressing PV and NMDAR 2B) significantly decreased with age (p < 0.001). We identified three distinct populations of neurons on the basis of their volumes among SGNs. Thus, there is significant age-related decline in the total number of SGNs, which starts early in life. It may be due to ambient noise and inadequate neutralisation of excitotoxicity.

Behavioral and Neurodevelopmental Effects of Early Interventions in Adult Wistar Rats.

Interventions performed in the early period of life are associated with cognitive and behavioral changes in adulthood. The effects of interventions such as exposure to an early stressful life event or environmental enrichment on cognitive and behavioral development are studied. The aim of this study is to develop a new intervention method, to investigate the effects of early interventions on social interaction, memory anxiety levels and NR2B levels in prefrontal and hippocampus in adulthood. The hypothesis of the study is that exposure to the ambivalent mother will affect the behavioral performance of rats at least as much as one hour apart from the mother in the adult period and cause changes in the prefrontal cortex and hippocampus in the NR2B levels. In the study, the Wistar rats were divided into four groups as control group (12), group that remained 15 minutes apart from mother (Mild Stress) (12), group that remained 60 minutes apart from mother (Severe Stress) (14) and ambivalent mother group (13). In adulthood, the social interaction test, elevated plus maze and new object recognition test performances of rats were evaluated. ELISA method was used to evaluate the effect of interventions on the prefrontal cortex and hippocampus NMDA R2B levels. The important findings of the study were that in the new object recognition test, separation from the mother did not affect the recognition memory regardless of gender, while the short-term recognition memory of the females of the ambivalent mothers' group was better than the females in the other groups and the long-term memory performance of the mild stress groups men was better than the man in the other groups. In addition, in the social interaction test, the males of the ambivalent group and the mild stress group showed more aggressive behavior. It was determined that the prefrontal cortex NR2B level was higher in the mild stress and ambivalent mother group compared to the severe stress group, and NR2B level was increased in all intervention groups compared to the control group. In contrast to the hypothesis, the results of this study support that the ambivalent mother's group rats are not more adversely affected than the severe group rats and that the model created may be an environmental enrichment model rather than an early stressful life event exposure.