NMDAR Signaling Research Articles

Modular Arrangement of Synaptic and Intrinsic Homeostatic Plasticity within Visual Cortical Circuits.

Neocortical circuits use synaptic and intrinsic forms of homeostatic plasticity to stabilize key features of network activity, but whether these different homeostatic mechanisms act redundantly, or can be independently recruited to stabilize different network features, is unknown. Here we used pharmacological and genetic perturbations both in vitro and in vivo to determine whether synaptic scaling and intrinsic homeostatic plasticity (IHP) are arranged and recruited in a hierarchical or modular manner within L2/3 pyramidal neurons in rodent V1. Surprisingly, although the expression of synaptic scaling and IHP was dependent on overlapping trafficking pathways, they could be independently recruited by manipulating spiking activity or NMDAR signaling, respectively. Further, we found that changes in visual experience that affect NMDAR activation but not mean firing selectively trigger IHP, without recruiting synaptic scaling. These findings support a modular model in which synaptic and intrinsic homeostatic plasticity respond to and stabilize distinct aspects of network activity.

Homeostatic regulation of circuit activity through temperature-sensing rather than activity-sensing

Electrical signaling between nerve cells coordinates essential functions of the body. However, neurons face their own regulatory challenges, as they need to produce relatively constant activity patterns as the environment changes. Like homeostatic control that occurs within other organ systems, neural circuits are subject to homeostatic regulation as well, whereby deviations from a set point level of activity elicit corrective responses to maintain circuit output. To achieve this end, neural systems are thought to sense variables that relate to neuronal activity, such as firing rate, ion concentrations, and neuromodulators, to detect when an imbalance in activity occurs. While recording rhythmic motor activity associated with breathing in the American bullfrog, we made the surprising observation that acute cooling to 10°C silenced network activity, but after several minutes, bursting resumed and then overshot baseline frequency upon rewarming. Burst frequency drifted back to the initial value over tens of minutes, consistent with the fast regulation of an activity set point (n=9). Time controls with no temperature changes were stable throughout this period (n=7). Exposing the network to manipulations inducing similar perturbations that silence activity over the same timescale– hypoxia (n=6), glycine (n=6), and tetrodotoxin (n=4)– did not engage feedback regulation. These results suggested that temperature sensing, rather than activity sensing, controls network output. Cation channels activated by cooling in amphibians (TRPM8, n=4; TRPV3, n=4) and L-type Ca2+ channels (n=4) did not contribute to these responses. Experimental activation of the Na+/K+ pump with monensin, which raises intracellular Na+, reduced the compensation response both in the cold (p=0.01, unpaired t-test) and in the overshoot phase following warming, suggesting that cold-dependent inhibition of the Na+/K+ pump enhances network excitability. Finally, NMDA-glutamate receptors played a role in constraining the amount of compensation, as block of NMDARs with D-APV led to compensation that greatly exceeded those observed in the control experiments (n=5, p<0.0001, unpaired t-test), remaining elevated above baseline upon rewarming in all experiments. The cellular mechanisms by which raising intracellular Na+ with monensin and NMDAR signaling influence compensation responses are ongoing. Overall, these results uncover a temperature-sensitive control system that regulates activity in neural circuits. Our results introduce that some neural systems may replace typical activity sensors with regulatory systems that are instead tuned to environmental cues to defend activity set points. R01NS114514, R15NS112920-01A1. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract WP322: GluN2A-NMDAR Mediated Increased Neuronal Prostaglandin E2 Release and Microglial Activation Exacerbates Ischemic Brain Injury Under Hyperhomocysteinemic Condition

Hyperhomocysteinemia (Hhcy), a metabolic disorder is recognized as a risk factor for ischemic stroke. However, the impact of Hhcy on stroke outcome is not known. Using a rodent model of experimental stroke, we recently showed that predisposition to Hhcy exacerbates ischemic brain injury. The findings also showed that Hhcy triggers GluN2A subunit containing NMDA receptor (GluN2A-NMDAR) stimulation that act in conjunction with ischemia-induced pathways involving GluN2B subunit containing NMDAR (GluN2B-NMDAR) stimulation to enhance stroke pathology. The current study evaluated whether GluN2A-NMDAR-mediated increased expression of cyclooxygenase-2 (COX-2) and excessive release of the pro-inflammatory mediator prostaglandin E2 (PGE2) from neurons results in increased microglial activation and exacerbated ischemic brain injury. HHcy was induced by implantation of Alzet pumps with L-homocysteine in adult male Wistar rats. Cerebral ischemia was induced by middle cerebral artery occlusion (60 min) in control and Hhcy rats. In a subset of Hhcy rats, NVP-AAM077, a pharmacological inhibitor of GluN2A-NMDAR was injected intravenously at the onset of stroke. At specified times following reperfusion, brain tissues were processed for FluroJade staining, immunoblotting with COX2 antibody, immunohistochemistry with COX2/NeuN and Iba1 antibodies, prostaglandin E2 (PGE2) assay and RT-PCR. FluroJade staining shows an early onset and exacerbation of ischemic injury in Hhcy rats. This involves increased expression of COX-2 in neurons, release of PGE2, and a shift in microglial morphology from ramified state to active amoeboid state, 6h after reperfusion. Administration of NVP-AAM077 attenuates the increase in COX2 expression and PGE2 levels as well as microglial activation. The findings demonstrate that an early onset of neuroinflammatory response mediated through GluN2A-NMDAR stimulation could contribute to the exacerbation of ischemic brain injury under Hhcy conditions. As GluN2A-NMDAR stimulation is primarily involved in promoting synaptic plasticity, neuronal growth, and survival, establishing their role in promoting neuroinflammatory response could lead to a paradigm shift in our understanding of the consequences of NMDAR signaling.

Cannabinerol (CBNR) Influences Synaptic Genes Associated with Cytoskeleton and Ion Channels in NSC-34 Cell Line: A Transcriptomic Study.

Cannabinoids are receiving great attention as a novel approach in the treatment of cognitive and motor disabilities, which characterize neurological disorders. To date, over 100 phytocannabinoids have been extracted from Cannabis sativa, and some of them have shown neuroprotective properties and the capacity to influence synaptic transmission. In this study, we investigated the effects of a less-known phytocannabinoid, cannabinerol (CBNR), on neuronal physiology. Using the NSC-34 motor-neuron-like cell line and next-generation sequencing analysis, we discovered that CBNR influences synaptic genes associated with synapse organization and specialization, including genes related to the cytoskeleton and ion channels. Specifically, the calcium, sodium, and potassium channel subunits (Cacna1b, Cacna1c, Cacnb1, Grin1, Scn8a, Kcnc1, Kcnj9) were upregulated, along with genes related to NMDAR (Agap3, Syngap1) and calcium (Cabp1, Camkv) signaling. Moreover, cytoskeletal and cytoskeleton-associated genes (Actn2, Ina, Trio, Marcks, Bsn, Rtn4, Dgkz, Htt) were also regulated by CBNR. These findings highlight the important role played by CBNR in the regulation of synaptogenesis and synaptic transmission, suggesting the need for further studies to evaluate the neuroprotective role of CBNR in the treatment of synaptic dysfunctions that characterize motor disabilities in many neurological disorders.

Tau-S214 Phosphorylation Inhibits Fyn Kinase Interaction and Increases the Decay Time of NMDAR-mediated Current

Fyn kinase SH3 domain interaction with PXXP motif in the Tau protein is implicated in AD pathology and is central to NMDAR function. Among seven PXXP motifs localized in proline-rich domain of Tau protein, tandem 5th and 6th PXXP motifs are critical to Fyn-SH3 domain interaction. Here, we report the crystal structure of Fyn-SH3 -Tau (207–221) peptide consisting of 5th and 6th PXXP motif complex to 1.01 Å resolution. Among five AD-specific phosphorylation sites encompassing the 5th and 6th PXXP motifs, only S214 residue showed interaction with SH3 domain. Biophysical studies showed that Tau (207–221) with S214-phosphorylation (pS214) inhibits its interaction with Fyn-SH3 domain. The individual administration of Tau (207–221) with/without pS214 peptides to a single neuron increased the decay time of evoked NMDA current response. Recordings of spontaneous NMDA EPSCs at +40 mV indicate an increase in frequency and amplitude of events for the Tau (207–221) peptide. Conversely, the Tau (207–221) with pS214 peptide exhibited a noteworthy amplitude increase alongside a prolonged decay time. These outcomes underscore the distinctive modalities of action associated with each peptide in the study. Overall, this study provides insights into how Tau (207–221) with/without pS214 affects the molecular framework of NMDAR signaling, indicating its involvement in Tau-related pathogenesis.

Neuroprotective Effects of Cannabispirenone A against NMDA-Induced Excitotoxicity in Differentiated N2a Cells.

The endocannabinoid system is found throughout the central nervous system, and its cannabinoids receptor 1 is critical in preventing neurotoxicity caused by N-methyl-D-aspartate receptor activation (NMDARs). The activity of NMDARs places demands on endogenous cannabinoids to regulate their calcium currents. Endocannabinoids keep NMDAR activity within safe limits, protecting neural cells from excitotoxicity. Cannabinoids are remembered to deliver this outcome by repressing presynaptic glutamate discharge or obstructing postsynaptic NMDAR-managed flagging pathways. The endocannabinoid system must exert a negative influence proportional to the strength of NMDAR signaling for such control to be effective. The goal of this paper is to draw the attention towards the neuroprotective mechanism of constituents of Cannabis sativa against NMDA-induced excitotoxic result. Phytochemical investigation of the cannabis flowers led to the isolation of nine secondary metabolites. A spiro-compound, Cannabispirenone A, which on treatment of the cells prior to NMDA exposure significantly increases cell survival while decreasing ROS production, lipid peroxidation, and intracellular calcium. Our findings showed that this compound showed neuroprotection against NMDA-induced excitotoxic insult, has antioxidative properties, and increased cannabinoid receptor 1 expression, which may be involved in the signaling pathway for this neuroprotection.

Extended genome‐wide association study employing the African Genome Resources Panel identifies novel susceptibility loci for Alzheimer’s Disease in individuals of African ancestry

AbstractBackgroundAlthough African Americans are twice as likely to develop Alzheimer’s Disease (AD), individuals with African ancestry are under‐represented in genetic research of the disease. In the largest AD genome‐wide association studies to date for African‐Americans (Reitz et al. JAMA 2013; Kunkle at al. JAMA Neurol 2021) we previously identified several novel susceptibility loci in addition to APOE, including ABCA7, API5, RBFOX1, and IGF1R.MethodWe performed a genome‐wide association meta‐analysis of 2,844 AD cases and 6,251 cognitively healthy controls of African ancestry (AA) assembled across 17 different cohorts. Single‐variant association analysis was conducted adjusting for age, sex, principal components, and subsequently APOE, applying logistic regression for case‐control and general estimating equations for family‐based datasets. Within‐study results were meta‐analyzed using METAL, and followed by gene‐based, pathway, scRNA‐seq, and colocalization analyses.ResultSingle variant meta‐analysis identified a novel genome‐wide significant AD risk locus in the MPDZ gene on chromosome 9p23 (rs141610415, MAF = .002, P = 3.68×10−9). MPDZ (MUPP1) is a vital component of the NMDAR signaling complex in excitatory synapses of hippocampal neurons critical for learning and memory. Two additional novel common loci and 9 novel rare loci approached genome‐wide significance at P<9×10−7. Genes at these loci are acting in biologically plausible pathways: signal transduction (PLEKHG1), synaptic transmission (CNTNAP4), synaptic connectivity (SDK1), neural development/function (SRGAP3, KIDINS220, UNC5C, TSSC1, TANC2), and neuronal differentiation (ASCL1). Single‐cell RNA‐sequence analysis shows that all genes are expressed in the brain, and that expression of the orthologs of SRGAP3, TANC2, and MMP16 is upregulated with amyloid toxicity in zebrafish. Pathway analyses support the notion that immune response, transcription/DNA repair, lipid processing, and intracellular trafficking are major AD‐associated pathways in African Americans. Except for SIPA1L2 and ACER3, all previously reported loci, including ABCA7, API5, RBFOX1 and IGF1R, remain genome‐wide or close to genome‐wide significant.ConclusionWe identified several novel loci for AD in individuals with African ancestry with the strongest association observed for MPDZ involved in hippocampal synaptic signaling. Identification of a significant number of loci at suggestive significance indicates that future studies with further increased sample size will be critical to identify additional disease‐associated loci in individuals of African ancestry.

Mechanism of new optimized Sheng-Mai-San Formula to regulate cardiomyocyte apoptosis through NMDAR pathway

Background and objectivesIschemic heart failure (HF) has become a disease that seriously endangers people's life and health. As a herbal formula widely used in clinical practice, new optimized Sheng-Mai-San (NO-SMS) has been shown to be significantly effective in improving cardiac function, increasing exercise tolerance, and slowing the progression of myocardial fibrosis in heart failure patients in multi-center clinical studies in various regions of China. In our previous pharmacodynamic and toxicological studies, we found that a medium-dose formulation (8.1 g of raw drug/kg) was the most effective in the treatment of heart failure, but its mechanism of action is still being investigated. The present study is exploring its relationship with cardiomyocyte apoptosis. Materials and methodsWe investigated and verified this through two parts of experiments, in vivo and in vitro. Firstly, we prepared male SD rats with heart failure models by ligating the left anterior descending branch of the coronary artery (EF ≤ 50%), which were treated with NO-SMS Formula (8.1 g of raw drug/kg/d), Ifenprodil (5.4 mg/kg/d) or Enalapril (0.9 mg/kg/d) prepared suspensions by gavage for 4 weeks. The cardiac and structural changes were evaluated by echocardiography, H&E, and MASSON staining. The apoptosis of cardiomyocytes in each group was detected by Western blot, qRT-PCR, and ELISA. In vitro cell experiments include H9c2 cardiomyocyte injury induced by H2O2 and NMDA respectively, and the groups were incubated with NO-SMS and Ifenprodil-containing serum for 24 h. Apoptosis was detected by Annexin V-FITC/PI double-staining method, and the rest of the assays were consistent with the in vivo experiments. ResultsCompared with the model group, the NO-SMS formula group and the Ifenprodil group could significantly improve cardiac function, delay myocardial fibrosis, reduce the expression of pro-apoptotic proteins, mRNA, and the concentration levels of Ca2+ and ROS in heart failure rats and H9c2 cardiomyocytes with H2O2 and NMDA-induced injury, which could significantly reduce the apoptosis rate of damaged cardiomyocytes and effectively inhibit the apoptosis of cardiomyocytes. ConclusionNO-SMS Formula improved cardiac function, inhibited ventricular remodeling and cardiomyocyte apoptosis in HF rats, and its mechanism may be related to the regulation of the NMDAR signaling pathway, inhibition of large intracellular Ca2+ inward flow, and ROS production in cardiomyocytes.

Myelinating Co-Culture as a Model to Study Anti-NMDAR Neurotoxicity.

Anti-NMDA receptor (NMDAR) encephalitis is frequently associated with demyelinating disorders (e.g., multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), myelin oligodendrocyte glycoprotein-associated disease (MOGAD)) with regard to clinical presentation, neuropathological and cerebrospinal fluid findings. Indeed, autoantibodies (AABs) against the GluN1 (NR1) subunit of the NMDAR diminish glutamatergic transmission in both neurons and oligodendrocytes, leading to a state of NMDAR hypofunction. Considering the vital role of oligodendroglial NMDAR signaling in neuron-glia communication and, in particular, in tightly regulated trophic support to neurons, the influence of GluN1 targeting on the physiology of myelinated axon may be of importance. We applied a myelinating spinal cord cell culture model that contains all major CNS cell types, to evaluate the effects of a patient-derived GluN1-specific monoclonal antibody (SSM5) on neuronal and myelin integrity. A non-brain reactive (12D7) antibody was used as the corresponding isotype control. We show that in cultures at the late stage of myelination, prolonged treatment with SSM5, but not 12D7, leads to neuronal damage. This is characterized by neurite blebbing and fragmentation, and a reduction in the number of myelinated axons. However, this significant toxic effect of SSM5 was not observed in earlier cultures at the beginning of myelination. Anti-GluN1 AABs induce neurodegenerative changes and associated myelin loss in myelinated spinal cord cultures. These findings may point to the higher vulnerability of myelinated neurons towards interference in glutamatergic communication, and may refer to the disturbance of the NMDAR-mediated oligodendrocyte metabolic supply. Our work contributes to the understanding of the emerging association of NMDAR encephalitis with demyelinating disorders.

Hippocampus-prefrontal cortex inputs modulate spatial learning and memory in a mouse model of sepsis induced by cecal ligation puncture.

Sepsis-associated encephalopathy (SAE) often leads to cognitive impairments. However, the pathophysiology of SAE is complex and unclear. Here, we investigated the role of hippocampus (HPC)-prefrontal cortex (PFC) in cognitive dysfunction in sepsis induced by cecal ligation puncture (CLP) in mice. The neural projections from the HPC to PFC were first identified via retrograde tracing and viral expression. Chemogenetic activation of the HPC-PFC pathway was shown via immunofluorescent staining of c-Fos-positive neurons in PFC. Morris Water Maze (MWM) and Barnes maze (BM) were used to evaluate cognitive function. Western blotting analysis was used to determine the expression of glutamate receptors and related molecules in PFC and HPC. Chemogenetic activation of the HPC-PFC pathway enhanced cognitive dysfunction in CLP-induced septic mice. Glutamate receptors mediated the effects of HPC-PFC pathway activation in CLP mice. The activation of the HPC-PFC pathway resulted in significantly increased levels of NMDAR, AMPAR, and downstream signaling molecules including CaMKIIa, pCREB, and BDNF in PFC. However, inhibition of glutamate receptors using 2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo (F)quinoxaline (NBQX), which is an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR inhibitor), or D-2-amino-5-phosphonopentanoate (D-AP5), which is an NMDA receptor antagonist abolished this increase. Our study reveals the important role of the HPC-PFC pathway in improving cognitive dysfunction in a mouse model of CLP sepsis and provides a novel pathogenetic mechanism for SAE.

A requirement for astrocyte IP3R2 signaling for whisker experience-dependent depression and homeostatic upregulation in the mouse barrel cortex.

Changes to sensory experience result in plasticity of synapses in the cortex. This experience-dependent plasticity (EDP) is a fundamental property of the brain. Yet, while much is known about neuronal roles in EDP, very little is known about the role of astrocytes. To address this issue, we used the well-described mouse whiskers-to-barrel cortex system, which expresses a number of forms of EDP. We found that all-whisker deprivation induced characteristic experience-dependent Hebbian depression (EDHD) followed by homeostatic upregulation in L2/3 barrel cortex of wild type mice. However, these changes were not seen in mutant animals (IP3R2–/–) that lack the astrocyte-expressed IP3 receptor subtype. A separate paradigm, the single-whisker experience, induced potentiation of whisker-induced response in both wild-type (WT) mice and IP3R2–/– mice. Recordings in ex vivo barrel cortex slices reflected the in vivo results so that long-term depression (LTD) could not be elicited in slices from IP3R2–/– mice, but long-term potentiation (LTP) could. Interestingly, 1 Hz stimulation inducing LTD in WT paradoxically resulted in NMDAR-dependent LTP in slices from IP3R2–/– animals. The LTD to LTP switch was mimicked by acute buffering astrocytic [Ca2+]i in WT slices. Both WT LTD and IP3R2–/– 1 Hz LTP were mediated by non-ionotropic NMDAR signaling, but only WT LTD was P38 MAPK dependent, indicating an underlying mechanistic switch. These results demonstrate a critical role for astrocytic [Ca2+]i in several EDP mechanisms in neocortex.

Synaptic Mechanisms Underlying Temporally Precise Information Processing in the VNLL, an Auditory Brainstem Nucleus.

Large glutamatergic, somatic synapses mediate temporally precise information transfer. In the ventral nucleus of the lateral lemniscus, an auditory brainstem nucleus, the signal of an excitatory large somatic synapse is sign inverted to generate rapid feedforward inhibition with high temporal acuity at sound onsets, a mechanism involved in the suppression of spurious frequency information. The mechanisms of the synaptically driven input-output functions in the ventral nucleus of the lateral lemniscus are not fully resolved. Here, we show in Mongolian gerbils of both sexes that, for stimulation frequencies up to 200 Hz, the EPSC kinetics together with short-term plasticity allow for faithful transmission with only a small increase in latency. Glutamatergic currents are exclusively mediated by AMPARs and NMDARs. Short-term plasticity is frequency-dependent and composed of an initial facilitation followed by depression. Physiologically relevant output generation is limited by the decrease in synaptic conductance through short-term plasticity (STP). At this endbulb synapse, STP acts as a low pass filter and increases the dynamic range of the conductance dependent input-output relation, while NMDAR signaling slightly increases the sensitivity of the input-output function. Our computational model shows that STP-mediated filtering limits the intensity dependence of the spike output, thus maintaining selectivity to sound transients. Our results highlight the interaction of cellular features that together give rise to the computations in the circuit.SIGNIFICANCE STATEMENT Auditory information processing in the brainstem is a prerequisite for generating our auditory representation of the environment. Thereby, many processing steps rely on temporally precise filtering. Precise feedforward inhibition is a key motif in auditory brainstem processing and produced through sign inversion at several large somatic excitatory synapses. A particular feature of the ventral nucleus of the lateral lemniscus is to produce temporally precise onset inhibition with little temporal variance independent of sound intensity. Our cell-physiology and modeling data explain how the synaptic characteristics of different current components and their short-term plasticity are tuned to establish sound intensity-invariant onset inhibition that is crucial for filtering out spurious frequency information.

Reduced Reelin Expression Induces Memory Deficits through Dab-1/ NMDAR Signaling Pathway: Cronobacter sakazakii Infection in a Rat Model of Experimental Meningitis

The purpose of this study was to examine whether the Cronobacter sakazakii infection-induced inflammation alters the Reelin signaling pathway that is involved in learning and memory. To test this, postnatal day (PND)-15 rat pups were either treated with Luria Bertani broth/Escherichia coli OP50/C. sakazakii through oral gavage or maintained as control and allowed to stay with their mothers until PND-24. Experimental groups’ rats were subjected to long-term novel object recognition test during their adolescent age PND-30–32. Observed behavioral data showed that C. sakazakii infection causes a deficit in recognition of novel objects from known objects. Further, our analysis showed that C. sakazakii infection-mediated inflammation decreases the Reelin expression by proteolytic cleavage and alters its receptor apolipoprotein E-receptor (ApoER)-2 splice variants ApoER2 (ex19) and ApoER2 (Δ). Subsequently, downregulated Reelin alters the phosphorylation of disabled adapter protein (Dab)-1 and leads to differential expression of N-methyl-D-aspartate (NMDA) receptor subunits 2A and 2B. Further, the NMDA receptor influences the expression of postsynaptic density (PSD)-95 protein and brain-derived neurotrophic factor (BDNF). Observed results suggest a deficit in recognition of novel objects possibly due to the alternation in Reelin signaling pathway.

Another win for mimetic peptides in stroke: Disruption of TRPM2-NMDAR signaling

Glutamate excitotoxicity during ischemia triggers an intracellular signaling avalanche leading to cell death, yet blocking NMDA receptors directly in human stroke trials failed. In this issue of Neuron, Zong etal. (2022) disrupt downstream NMDAR-TRPM2 coupling to improve stroke outcomes, supporting intracellular NMDAR signaling as an alternate therapeutic target.

Recent Reports on Redox Stress-Induced Mitochondrial DNA Variations, Neuroglial Interactions, and NMDA Receptor System in Pathophysiology of Schizophrenia.

Schizophrenia (SZ) is a chronic psychiatric disorder affecting several people worldwide. Mitochondrial DNA (mtDNA) variations could invoke changes in the OXPHOS system, calcium buffering, and ROS production, which have significant implications for glial cell survival during SZ. Oxidative stress has been implicated in glial cells-mediated pathogenesis of SZ; the brain comparatively more prone to oxidative damage through NMDAR. A confluence of scientific evidence points to mtDNA alterations, Nrf2 signaling, dynamic alterations in dorsolateral prefrontal cortex (DLPFC), and provocation of oxidative stress that enhance pathophysiology of SZ. Furthermore, the alterations in excitatory signaling related to NMDAR signaling were particularly reported for SZ pathophysiology. Current review reported the recent evidence for the role of mtDNA variations and oxidative stress in relation to pathophysiology of SZ, NMDAR hypofunction, and glutathione deficiency. NMDAR system is influenced by redox dysregulation in oxidative stress, inflammation, and antioxidant mediators. Several studies have demonstrated the relationship of these variables on severity of pathophysiology in SZ. An extensive literature search was conducted using Medline, PubMed, PsycINFO, CINAHL PLUS, BIOSIS Preview, Google scholar, and Cochrane databases. We summarize consistent evidence pointing out a plausible model that may elucidate the crosstalk between mtDNA alterations in glial cells and redox dysregulation during oxidative stress and the perturbation of NMDA neurotransmitter system during current therapeutic modalities for the SZ treatment. This review can be beneficial for the development of promising novel diagnostics, and therapeutic modalities by ascertaining the mtDNA variations, redox state, and efficacy of pharmacological agents to mitigate redox dysregulation and augment NMDAR function to treat cognitive and behavioral symptoms in SZ.

Perillaldehyde improves cognitive function in vivo and in vitro by inhibiting neuronal damage via blocking TRPM2/NMDAR pathway

BackgroundVascular cognitive dysfunction in patients with vascular dementia (VD) is a kind of severe cognitive dysfunction syndrome caused by cerebrovascular diseases. At present, effective drugs to improve the cognitive function of VD patients still need to be explored. Transient Receptor Potential Melastatin 2 (TRPM2) channel is a nonspecific cation channel that plays a key role in the toxic death of neurons. Perillaldehyde (PAE) has the protective effect of epilepsy and insomnia and other central nervous system diseases. The aim of this study is to explore whether PAE improves cognitive function in VD rats and to investigate the potential mechanisms in vivo and vitro.MethodsVD rats were induced by bilateral common carotid arteries occlusion (2-vessel occlusion [2VO]) and treated with PAE for 4 weeks. The neuroprotective effects of PAE was subsequently assessed by the Morris water maze, hematoxylin–eosin (HE) staining, Golgi staining, electron microscopy, Neuron-specific nuclear protein (Neu N) staining, and TdT-mediated dUTP nick end labeling (TUNEL) staining. After primary hippocampal neurons were isolated, cell viability was detected by MTT assay and intracellular Ca2+ concentration was detected by calcium imaging assay. The content of Nitriteoxide (NO), Malondialdehyde (MDA) and Superoxide dismutase (SOD) activity in serum of rats were observed by Enzyme Linked Immunosorbent Assay (ELISA). Immunohistochemistry, Western blot, and Confocal laser scanning were used to detect the expression levels of N-methyl-d-asprtate receptor-2B (NR2B) and TRPM2.ResultsThe results showed that PAE can improve the number and activity of neurons, increase the length and number of dendrites in hippocampus, decrease the Vv value and PE value of neuronal nucleus and mitochondrial structure significantly, increase the s value and L value in nucleus structure, decrease the s value and L value in mitochondrial structure, and improve the learning and memory ability of rats significantly. And PAE can strengthen the ability of antioxidant stress confirmed by increasing the activity of SOD and reducing the production of MDA. The results of western blot, immunohistochemistry and immunofluorescence showed that PAE could reduce the level of TRPM2 and increase the expression of NR2B.ConclusionsTaken together, our findings provide evidence that the neuroprotective effects of PAE in VD rats maybe through TRPM2 inhibition and subsequent activation of NMDAR signaling pathway.

Retraction: “MicroRNA‐219 decreases hippocampal long‐term potentiation inhibition and hippocampal neuronal cell apoptosis in type 2 diabetes mellitus mice by suppressing the NMDAR signaling pathway,” by Zhang, L, Chen, Z‐W, Yang, S‐F, et al. CNS Neurosci Ther. 2019; 25: 69–77

Retraction: “MicroRNA‐219 decreases hippocampal long‐term potentiation inhibition and hippocampal neuronal cell apoptosis in type 2 diabetes mellitus mice by suppressing the NMDAR signaling pathway,” by Zhang, L, Chen, Z‐W, Yang, S‐F, et al. CNS Neurosci Ther. 2019; 25: 69–77

Attenuated NMDAR signaling on fast-spiking interneurons in prefrontal cortex contributes to age-related decline of cognitive flexibility

Ionotropic glutamate receptors of the NMDA and AMPA subtypes transduce excitatory signaling on neurons in the prefrontal cortex (PFC) in support of cognitive flexibility. Cognitive flexibility is reliably observed to decline at advanced ages, coinciding with changes in PFC glutamate receptor expression and neuronal physiology. However, the relationship between age-related impairment of cognitive flexibility and changes to excitatory signaling on distinct classes of PFC neurons is not known. In this study, one cohort of young adult (4 months) and aged (20 months) male F344 rats were characterized for cognitive flexibility on an operant set-shifting task. Expression of the essential NMDAR subunit, NR1, was correlated with individual differences in set-shifting abilities such that lower NR1 in the aged PFC was associated with worse set-shifting. In contrast, lower expression of two AMPAR subunits, GluR1 and GluR2, was not associated with set-shift abilities in aging. As NMDARs are expressed by both pyramidal cells and fast-spiking interneurons (FSI) in PFC, whole-cell patch clamp recordings were performed in a second cohort of age-matched rats to compare age-associated changes on these neuronal subtypes. Evoked excitatory postsynaptic currents were generated using a bipolar stimulator while AMPAR vs. NMDAR-mediated components were isolated using pharmacological tools. The results revealed a clear increase in AMPA/NMDA ratio in FSIs that was not present in pyramidal neurons. Together, these data indicate that loss of NMDARs on interneurons in PFC contributes to age-related impairment of cognitive flexibility.

Low-intensity ultrasound restores long-term potentiation and memory in senescent mice through pleiotropic mechanisms including NMDAR signaling

Advanced physiological aging is associated with impaired cognitive performance and the inability to induce long-term potentiation (LTP), an electrophysiological correlate of memory. Here, we demonstrate in the physiologically aged, senescent mouse brain that scanning ultrasound combined with microbubbles (SUS+MB), by transiently opening the blood–brain barrier, fully restores LTP induction in the dentate gyrus of the hippocampus. Intriguingly, SUS treatment without microbubbles (SUSonly), i.e., without the uptake of blood-borne factors, proved even more effective, not only restoring LTP, but also ameliorating the spatial learning deficits of the aged mice. This functional improvement is accompanied by an altered milieu of the aged hippocampus, including a lower density of perineuronal nets, increased neurogenesis, and synaptic signaling, which collectively results in improved spatial learning. We therefore conclude that therapeutic ultrasound is a non-invasive, pleiotropic modality that may enhance cognition in elderly humans.

Estrogen Receptor β Contributes to Both Hypertension and Hypothalamic Plasticity in a Mouse Model of Peri-Menopause.

Hypertension susceptibility in women increases at the transition to menopause, termed perimenopause, a state characterized by erratic estrogen fluctuation and extended hormone cycles. Elucidating the role of estrogen signaling in the emergence of hypertension during perimenopause has been hindered by animal models that are confounded by abrupt estrogen cessation or effects of aging. In the present study, accelerated ovarian failure (AOF) in estrogen receptor β (ERβ) reporter mice was induced by 4-vinylcyclohexene diepoxide in young mice to model early-stage ovarian failure (peri-AOF) characteristic of peri-menopause. It was found that administering ERβ agonists suppressed elevated blood pressure in a model of neurogenic hypertension induced by angiotensin II (AngII) in peri-AOF, but not in age-matched male mice. It was also found that ERβ agonist administration in peri-AOF females, but not males, suppressed the heightened NMDAR signaling and reactive oxygen production in ERβ neurons in the hypothalamic paraventricular nucleus (PVN), a critical neural regulator of blood pressure. It was further shown that deleting ERβ in the PVN of gonadally intact females produced a phenotype marked by a sensitivity to AngII hypertension. These results suggest that ERβ signaling in the PVN plays an important role in blood pressure regulation in female mice and contributes to hypertension susceptibility in females at an early stage of ovarian failure comparable to human perimenopause.