Postsynaptic Density Research Articles

Effect of Reboxetine Treatment on BDNF, Synaptophysin, and PSD-95 Levels in the Spinal Dorsal Horn of Rats with Diabetic Neuropathy

Objective: It is known that neuropathic pain is accompanied by alterations in the levels of neurotrophic factors and synaptic proteins in the microenvironment of the spinal dorsal horn. Such changes contribute to hyperalgesia and allodynia processes; thus, analgesic drugs can exert their pharmacological effects by affecting the expressions, levels, or functions of these endogenous substances. In this study, based on the knowledge that reboxetine (a selective noradrenaline reuptake inhibitor) has the potential for antihyperalgesic efficacy in diabetic neuropathy, we aimed to examine the probable effects of this drug on diabetes-induced changes in brain-derived neurotrophic factor (BDNF), synaptophysin (the pre-synaptic marker of synaptic integration), and postsynaptic density-95 (PSD-95) (the postsynaptic marker of synaptic integration) levels in the superficial laminae of the dorsal horn. 
 Methods: Experimental diabetes was induced by a single-dose injection of streptozotocin (STZ) (50 mg/kg) in rats. After four week-long induction period of painful diabetic neuropathy, rats were treated orally with 8 mg/kg reboxetine for two weeks. Hyperalgesia responses were evaluated by using the Randall–Selitto and Hargreave's tests. Following the pain tests, immunohistochemical studies were performed.
 Results: Two weeks of reboxetine administration increased the reduced paw withdrawal thresholds and shortened the paw withdrawal latencies of diabetic rats in neuropathic pain tests, indicating the antihyperalgesic efficacy of this drug. Moreover, augmented BDNF and synaptophysin levels in diabetic rats reversed by reboxetine treatment. However, there was no alteration in the densities of PSD-95, in both STZ-diabetic and reboxetine-treated STZ-diabetic rats. 
 Conclusion: The obtained results suggested that inhibition of central sensitization and modulation of spinal plasticity seem to be pharmacological mechanisms underlying reboxetine's antihyperalgesic effects on diabetic rats. However, further studies are still needed to clarify the exact mechanism of action.

Neuropathological insights from SHANK3 mutant animal models

SHANK3 is a protein primarily found in the postsynaptic density (PSD) of excitatory synapses in the brain. Heterozygous mutations in the shank3 gene have been linked to autism spectrum disorder (ASD) and intellectual disability. There are various animal models carrying mutant SHANK3 that have provided valuable insights into the pathogenesis of ASD. In this review, we will discuss these animal models, with a specific focus on the neuropathology observed in shank3 mouse and monkey models. These models are particularly important as they share closer similarities to humans and are capable of more accurately recapitulating the neuropathological features observed in individuals with ASD. Mice with mutations in the shank3 gene exhibit deficits in social behavior, communication, and repetitive behaviors, which are core features of ASD and support the link between SHANK3 and ASD. However, studies of monkey models with SHANK3 targeting by CRISPR/Cas9 have demonstrated that, unlike mice with completely knocked-out shank3 genes, the monkey model with complete deletion of SHANK3 displays a reduction in the number of neuronal cells. This review discusses the species-specific neuropathology in SHANK3/shank3 knockout mice and monkeys. The differences in neuropathology in SHANK3/shank3 mutant mouse and monkey models suggest that non-human primate models are highly valuable for investigating the mechanism of neurodegeneration that may selectively occur in primate brains.

The polysaccharides from the fruits of Lycium barbarum ameliorate high-fat and high-fructose diet-induced cognitive impairment via regulating blood glucose and mediating gut microbiota

High-fat and high-fructose diet (HFFD) consumption can induce cognitive dysfunction and gut microbiota disorder. In the present study, the effects of the polysaccharides from the fruits of Lycium barbarum L. (LBPs) on HFFD-induced cognitive deficits and gut microbiota dysbiosis were investigated. The results showed that intervention of LBPs (200 mg/kg/day) for 14 weeks could significantly prevent learning and memory deficits in HFFD-fed mice, evidenced by a reduction of latency and increment of crossing parameters of platform quadrant in Morris water maze test. Moreover, oral administration of LBPs enhanced the expression of postsynaptic density protein 95 and brain-derived neurotrophic factor and reduced the activation of glial cells in hippocampus. Besides, LBPs treatment enriched the relative abundances of Allobaculum and Lactococcus and reduced the relative abundance of Proteobacteria in gut bacterial community of HFFD-fed mice, accompanied by increased levels of short-chain fatty acids (SCFAs) as well as expression of associated G protein-coupled receptors. Furthermore, LBPs intervention prevented insulin resistance, obesity and colonic inflammation. Finally, a significant correlation was observed among neuroinflammation associated parameters, gut microbiota and SCFAs through Pearson correlation analysis. Collectively, these findings suggested that the regulation of gut microbiota might be the potential mechanism of LBPs on preventing cognitive dysfunction induced by HFFD.

Effect of Cerebralcare Granule® combined with memantine on Alzheimer's disease

Ethnopharmacological relevanceIn elderly people, Alzheimer's disease (AD) is the most common form of dementia. It has been shown that traditional Chinese medicine (TCM) based on phytomedicines enhances the therapeutic effects of modern medicine when taken in conjunction with them. Modern medicine N-methyl-D-aspartate receptor (NMDA) antagonist memantine (Mm) are mainly used in the clinical treatment of AD. TCM Cerebralcare Granule® (CG) has long been an effective treatment for headaches, dizziness, and other symptoms. In this study, we employ a blend of CG and Mm to address Alzheimer's disease-like symptoms and explore their impacts and underlying mechanisms. Aim of the studyThe objective of our study was to observe the effects of CG combined with Memantine (Mm) on learning and memory impairment of AD mice induced by D-galactose and to explore the mechanism at work. Materials and methodsCG and Mm were combined to target multiple pathological processes involved in AD. For a thorough analysis, we performed various experiments such as behavioral detection, pathological detection, proteomic detection, and other experimental methods of detection. ResultsIt was found that the combination of CG and Mm was significantly effective for improving learning and memory in AD mice as well as brain pathology. The serum and hippocampal tissue of AD mice were significantly enhanced with catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities and malondialdehyde (MDA) levels were decreased with this treatment. In AD mice, a combination of Mm and CG (CG + Mm) significantly increased the levels of the anti-inflammatory factors IL-4 and IL-10, decreased the levels of pro-inflammatory factors (IL-6, IL-1β) and tumor necrosis factor-alpha (TNF-α), improved synaptic plasticity by restoring synaptophysin (SYP) and postsynaptic density protein-95 (PSD-95) expression in the hippocampus, enhanced Aβ phagocytosis of microglia in AD mice, and increased mitochondrial respiratory chain enzyme complexes I, II, III, and IV, lead to an increase in the number of functionally active NMDA receptors in the hippocampus. Proteomic analysis GO analysis showed that the positive regulation gene H3BIV5 of G protein coupled receptor signal pathway and synaptic transmission was up-regulated, while the transsynaptic signal of postsynaptic membrane potential and regulation-related gene Q5NCT9 were down-regulated. Most proteins showed significant enriched signal transduction pathway profiles after CG + Mm treatment, based on the KEGG pathway database. ConclusionThe data supported the idea that CG and Mm could be more effective in treating AD mice induced by D-galactose than Mm alone. We provided a basis for the clinical use of CG with Mm.

LPC20K modified from krill oil ameliorates the scopolamine-induced cognitive impairment

Alzheimer’s disease (AD) is characterized by cognitive impairment. It is common in the elderly. Etiologically, dysfunction of cholinergic neurotransmitter system is prominent in AD. However, disease modifying drug for AD is still unavailable. We hypothesized that krill oil and modified krill oil containing 20 % lysophosphatidylcholine-docosahexaenoic acid (LPC-DHA, LPC20K) could play a crucial role in AD by improving cognitive functions measured by several behavioral tests. We found that LPC20K could ameliorate short-term, long-term, spatial, and object recognition memory under cholinergic hypofunction states. To find the underlying mechanism involved in the effect of LPC20K on cognitive function, we investigated changes of signaling molecules using Western blotting. Expression levels of protein kinase C zeta (PKCζ) and postsynaptic density protein 95 (PSD-95), and phosphorylation levels of extracellular signal-regulated kinase (ERK), Ca2+/calmodulin-dependent protein kinase Ⅱ (CaMKⅡ), and cAMP response element-binding protein (CREB) were significantly increased in LPC20K-administered group compared to those in the memory impairment group. Moreover, the expression levels of BDNF were temporally increased especially 6 or 9 h after administration of LPC20K compared with the control group. These results suggest that LPC20K could ameliorate memory impairment caused by hypocholinergic state by enhancing the expression levels of PKCζ and PSD-95, and phosphorylation levels of ERK, CaMKⅡ and CREB and increasing BDNF expression levels. Therefore, LPC20K could be used as a dietary supplement against cognitive impairment observed in diseases such as AD with a hypocholinergic state.

"NO" Time in Fear Response: Possible Implication of Nitric-Oxide-Related Mechanisms in PTSD.

Post-traumatic stress disorder (PTSD) is a psychiatric condition characterized by persistent fear responses and altered neurotransmitter functioning due to traumatic experiences. Stress predominantly affects glutamate, a neurotransmitter crucial for synaptic plasticity and memory formation. Activation of the N-Methyl-D-Aspartate glutamate receptors (NMDAR) can trigger the formation of a complex comprising postsynaptic density protein-95 (PSD95), the neuronal nitric oxide synthase (nNOS), and its adaptor protein (NOS1AP). This complex is pivotal in activating nNOS and nitric oxide (NO) production, which, in turn, activates downstream pathways that modulate neuronal signaling, including synaptic plasticity/transmission, inflammation, and cell death. The involvement of nNOS and NOS1AP in the susceptibility of PTSD and its comorbidities has been widely shown. Therefore, understanding the interplay between stress, fear, and NO is essential for comprehending the maintenance and progression of PTSD, since NO is involved in fear acquisition and extinction processes. Moreover, NO induces post-translational modifications (PTMs), including S-nitrosylation and nitration, which alter protein function and structure for intracellular signaling. Although evidence suggests that NO influences synaptic plasticity and memory processing, the specific role of PTMs in the pathophysiology of PTSD remains unclear. This review highlights pathways modulated by NO that could be relevant to stress and PTSD.

Ultrastructural analysis of nigrostriatal dopaminergic terminals in a knockin mouse model of DYT1 dystonia.

DYT1 dystonia is associated with decreased striatal dopamine release. In this study, we examined the possibility that ultrastructural changes of nigrostriatal dopamine terminals could contribute to this neurochemical imbalance using a serial block face/scanning electron microscope (SBF/SEM) and three-dimensional reconstruction to analyse striatal tyrosine hydroxylase-immunoreactive (TH-IR) terminals and their synapses in a DYT1(ΔE) knockin (DYT1-KI) mouse model of DYT1 dystonia. Furthermore, to study possible changes in vesicle packaging capacity of dopamine, we used transmission electron microscopy to assess the synaptic vesicle size in striatal dopamine terminals. Quantitative comparative analysis of 80 fully reconstructed TH-IR terminals in the WT and DYT1-KI mice indicate (1) no significant difference in the volume of TH-IR terminals; (2) no major change in the proportion of axo-spinous versus axo-dendritic synapses; (3) no significant change in the post-synaptic density (PSD) area of axo-dendritic synapses, while the PSDs of axo-spinous synapses were significantly smaller in DYT1-KI mice; (4) no significant change in the contact area between TH-IR terminals and dendritic shafts or spines, while the ratio of PSD area/contact area decreased significantly for both axo-dendritic and axo-spinous synapses in DYT1-KI mice; (5) no significant difference in the mitochondria volume; and (6) no significant difference in the synaptic vesicle area between the two groups. Altogether, these findings suggest that abnormal morphometric changes of nigrostriatal dopamine terminals and their post-synaptic targets are unlikely to be a major source of reduced striatal dopamine release in DYT1 dystonia.

Electroacupuncture ameliorates chronic unpredictable mild stress-induced depression-like behavior and cognitive impairment through suppressing oxidative stress and neuroinflammation in rats

BackgroundDepression is associated with lowered mood, anxiety, anhedonia, cognitive impairments, and even suicidal tendencies in severe cases. Yet few studies have directed acupuncture's mechanism toward enhancing axonal repair correlated with synaptic plasticity and anti-inflammatory effects related to oxidative stress in the hippocampus. MethodsMale Sprague-Dawley (SD) rats were randomly divided into control group (CON), chronic unpredictable mild stress (CUMS) group, CUMS + electroacupuncture group (EA), and CUMS + fluoxetine group (FLX) (n = 10/group). Rats were given a 28-day treatment at the Shangxing (GV23) and Fengfu (GV16) acupoints with electroacupuncture or fluoxetine (2.1 mg/kg). ResultsRats exposed to CUMS induced depression-like behaviors and spatial learning-memory impairment, changed the ionized calcium binding adaptor molecule 1 (IBA-1), Vglut1, myelin basic protein (MBP), and postsynaptic density protein 95 (PSD95) level of hippocampal, increased the Nod-like receptor protein 3 (NLRP3), atypical squamous cell (ASC), Caspase level and hippocampal reactive oxygen species (ROS), and prompted the activation of Epha4-mediated signaling and an inflammatory response. Conversely, electroacupuncture administration reduced these changes and prevented depression-like behaviors and cognitive impairment. Electroacupuncture also promoted hippocampal expression of Sirtuin1(SIRT1), Nuclear factor erythroid 2-like (Nrf2), Heme oxygenase-1 (HO-1); reduced the expression of interleukin-1β (IL-1β), interleukin-18 (IL-18), and tumor necrosis factor-alpha (TNF-α); and prevented neural damage, particularly the synaptic myelin sheath, and neuroinflammation by regulating Eph receptor A4 (EphA4) in the hippocampal. ConclusionThese results indicate that electroacupuncture prevents depression-like behaviors with cognitive impairment and synaptic and neuronal damage, probably by reducing EphA4, which mediates ROS hyperfunction and the inflammatory response.

Mimicking hypomethylation of FUS requires liquid–liquid phase separation to induce synaptic dysfunctions

The hypomethylation of fused in sarcoma (FUS) in frontotemporal lobar degeneration promotes the formation of irreversible condensates of FUS. However, the mechanisms by which these hypomethylated FUS condensates cause neuronal dysfunction are unknown. Here we report that expression of FUS constructs mimicking hypomethylated FUS causes aberrant dendritic FUS condensates in CA1 neurons. These hypomethylated FUS condensates exhibit spontaneous, and activity induced movement within the dendrite. They impair excitatory synaptic transmission, postsynaptic density-95 expression, and dendritic spine plasticity. These neurophysiological defects are dependent upon both the dendritic localisation of the condensates, and their ability to undergo liquid–liquid phase separation. These results indicate that the irreversible liquid–liquid phase separation is a key component of hypomethylated FUS pathophysiology in sporadic FTLD, and this can cause synapse dysfunction in sporadic FTLD.

Bioinformatics Analysis of Disc Large Homolog-4 (DLG-4) As Parameters in Neuroplasticity

Disc Large Homolog-4 (DLG-4), also known as Post Synaptic Density 95 (PSD95) is believed to have an important role in the function and organization of the synapse. DLG-4 is the main protein structure at the synapse that is able to bind to various molecules on the surface of the postsynaptic membrane. This review aims to determine the biomolecular characteristics of DLG-4 and the role of DLG-4 as an important parameter in neuroplasticity. Biomolecular characteristic analysis was obtained through various bioinformatics websites namely NCBI, PROTPARAM, TMHMM, PEPTIDE CUTTER, NETNGLYC, TARGETP and KEGG PATHWAY. The DLG-4 gene is located on chromosome 17p13.1 and has 25 exon. The DLG-4 protein consists of 764 amino acids with a molecular weight of 80.47 kDa. DLG-4 has a structure of 3 N-terminal PDZ domains, a Src Homology 3 (SH3) domain and a guanilate kinase-like C-terminal domain. This protein has a stability score of 48.61. The aliphatic index is 85.42. DLG-4 is found inside, outside, and on transmembranes, as determined by THMM. There are 37 enzymes that are predicted to be able to split the DLG-4 protein. The DLG-4 protein shows 3 potential sites of glycosylation of amino acids. The target location of the DLG-4 protein is mostly in other locations (other = 0.6556), secretory pathway (0.3328), and only slightly in mitochondria (0.0116). The DLG-4 protein is strongly associated with the glutamatergic system in postsynaptic neurons. The glutamatergic system is concerned with the molecular mechanism of memory development and cognitive function, long-term potentiation (LTP). These findings support the fact that DLG-4 protein plays a role in neuroplasticity mechanisms in the brain.

Electroacupuncture stimulation ameliorates cognitive impairment induced by long-term high-fat diet by regulating microglial BDNF

Long-term high-fat diet (HFD) in adolescents leads to impaired hippocampal function and increases the risk of cognitive impairment. Studies have shown that HFD activates hippocampal microglia and induces hippocampal inflammation, which is an important factor for cognitive impairment. Electroacupuncture stimulation (ES), a nerve stimulation therapy, is anti-inflammatory. This study explored its therapeutic potential and mechanism of action in obesity-related cognitive impairment. 4-week-old C57 mice were given either normal or HFD for 22 weeks. At 19 weeks, some of the HFD mice were treated with ES and nigericin sodium salt. The cognitive behavior was assessed through Morris water maze test at 23 weeks. Western blotting was used to detect the expression levels of pro-inflammatory molecules IL-1β and IL-1R, synaptic plasticity related proteins synaptophysin and Postsynaptic Density-95 (PSD-95), and apoptotic molecules (Caspase-3 and Bcl-2), in the hippocampus. The number, morphology, and status of microglia, along with the brain-derived neurotrophic factor（BDNF） content, were analyzed using immunofluorescence. ES treatment improved cognitive deficits in HFD model mice, and decreased the expressions of microglial activation marker, CD68, and microglial BDNF. Inhibition of proinflammatory cytokine, IL-1β, and IL-1R promoted PSD-95 and synaptophysin expressions. Peripheral NLRP3 inflammasome agonist injections exacerbated the cognitive deficits in HFD mice and promoted the expressions of IL-1β and IL-1R in the hippocampus. The microglia showed obvious morphological damage and apoptosis. Collectively, our findings suggest that ES inhibits inflammation, regulates microglial BDNF, and causes remodeling of hippocampal function in mice to counteract obesity-like induced cognitive impairment. Overexcitation of peripheral inflammasome complexes induces hippocampal microglia apoptosis, which hinders the effects of ES.

Impairments of Spatial Memory and N-methyl-d-aspartate Receptors and Their Postsynaptic Signaling Molecules in the Hippocampus of Developing Rats Induced by As, Pb, and Mn Mixture Exposure.

Exposure to metal mixtures is recognized as a real-life scenario, needing novel studies that can assess their complex effects on brain development. There is still a significant public health concern associated with chronic low levels of metal exposure. In contrast to other metals, these three metals (As, Pb, and Mn) are commonly found in various environmental and industrial contexts. In addition to additive or synergistic interactions, concurrent exposure to this metal mixture may also have neurotoxic effects that differ from those caused by exposure to single components. The NMDA receptor and several important signaling proteins are involved in learning, memory, and synaptic plasticity in the hippocampus, including CaMKII, postsynaptic density protein-95 (PSD-95), synaptic Ras GTPase activating protein (SynGAP), a negative regulator of Ras-MAPK activity, and CREB. We hypothesized that alterations in the above molecular players may contribute to metal mixture developmental neurotoxicity. Thus, the aim of this study was to investigate the effect of these metals and their mixture at low doses (As 4 mg, Pb 4 mg, and Mn 10 mg/kg bw/p.o) on NMDA receptors and their postsynaptic signaling proteins during developing periods (GD6 to PD59) of the rat brain. Rats exposed to As, Pb, and Mn individually or at the same doses in a triple-metal mixture (MM) showed impairments in learning and memory functions in comparison to the control group rats. Declined protein expressions of NR2A, PSD-95, p- CaMKII, and pCREB were observed in the metal mix-exposed rats, while the expression of SynGAP was found to be enhanced in the hippocampus as compared to the controls on PD60. Thereby, our data suggest that alterations in the NMDA receptor complex and postsynaptic signaling proteins could explain the cognitive dysfunctions caused by metal-mixture-induced developmental neurotoxicity in rats. These outcomes indicate that incessant metal mixture exposure may have detrimental consequences on brain development.

Phosphorylation-dependent membraneless organelle fusion and fission illustrated by postsynaptic density assemblies

Membraneless organelles formed by phase separation of proteins and nucleic acids play diverse cellular functions. Whether and, if yes, how membraneless organelles in ways analogous to membrane-based organelles also undergo regulated fusion and fission is unknown. Here, using a partially reconstituted mammalian postsynaptic density (PSD) condensate as a paradigm, we show that membraneless organelles can undergo phosphorylation-dependent fusion and fission. Without phosphorylation of the SAPAP guanylate kinase domain-binding repeats, the upper and lower layers of PSD protein mixtures form two immiscible sub-compartments in a phase-in-phase organization. Phosphorylation of SAPAP leads to fusion of the two sub-compartments into one condensate accompanied with an increased Stargazin density in the condensate. Dephosphorylation of SAPAP can reverse this event. Preventing SAPAP phosphorylation invivo leads to increased separation of proteins from the lower and upper layers of PSD sub-compartments. Thus, analogous to membrane-based organelles, membraneless organelles can also undergo regulated fusion and fission.

Brain-enriched guanylate kinase-associated protein, a component of the post-synaptic density protein complexes, contributes to learning and memory

Brain-enriched guanylate kinase-associated protein (BEGAIN) is highly enriched in the post-synaptic density (PSD) fraction and was identified in our previous study as a protein associated with neuropathic pain in the spinal dorsal horn. PSD protein complexes containing N-methyl-d-aspartate receptors are known to be involved in neuropathic pain. Since these PSD proteins also participate in learning and memory, BEGAIN is also expected to play a crucial role in this behavior. To verify this, we first examined the distribution of BEGAIN in the brain. We found that BEGAIN was widely distributed in the brain and highly expressed in the dendritic regions of the hippocampus. Moreover, we found that BEGAIN was concentrated in the PSD fraction of the hippocampus. Furthermore, immunoelectron microscopy confirmed that BEGAIN was localized at the asymmetric synapses. Behavioral tests were performed using BEGAIN-knockout (KO) mice to determine the contribution of BEGAIN toward learning and memory. Spatial reference memory and reversal learning in the Barns circular maze test along with contextual fear and cued fear memory in the contextual and cued fear conditioning test were significantly impaired in BEGAIN-KO mice compared to with those in wild-type mice. Thus, this study reveals that BEGAIN is a component of the post-synaptic compartment of excitatory synapses involved in learning and memory.

Cognitive impairment is associated with BDNF-TrkB signaling mediating synaptic damage and reduction of amino acid neurotransmitters in heart failure.

Heart failure (HF) is often accompanied by cognitive impairment (CI). Brain-derived neurotrophic factor (BDNF) deficiency is closely associated with CI. However, the role and mechanism of BDNF in HF with CI is still not fully understood. Here, the case-control study was designed including 25 HF without CI patients (HF-NCI) and 50 HF with CI patients (HF-CI) to investigate the predictive value of BDNF in HF-CI while animal and cell experiments were used for mechanism research. Results found that BDNF levels in serum neuronal-derived exosomes were downregulated in HF-CI patients. There was no significant difference in serum BDNF levels among the two groups. HF rats showed obvious impairment in learning and memory; also, they had reduced thickness and length of postsynaptic density (PSD) and increased synaptic cleft width. Expression of BDNF, TrkB, PSD95, and VGLUT1 was significantly decreased in HF rats brain. In addition, compared with sham rats, amino acids were significantly reduced with no changes in the acetylcholine and monoamine neurotransmitters. Further examination showed that the number of synaptic bifurcations and the expression of BDNF, TrkB, PSD95, and VGLUT1 were all decreased in the neurons that interfered with BDNF-siRNA compared with those in the negative control neurons. Together, our results demonstrated that neuronal-derived exosomal BDNF act as effective biomarkers for prediction of HF-CI. The decrease of BDNF in the brain triggers synaptic structural damage and a decline in amino acid neurotransmitters via the BDNF-TrkB-PSD95/VGLUT1 pathway. This discovery unveils a novel pathological mechanism underlying cognitive impairment following heart failure.

Sleep deprivation aggravates lipopolysaccharide-induced anxiety, depression and cognitive impairment: The role of pro-inflammatory cytokines and synaptic plasticity-associated proteins

Growing evidence indicates that neuroinflammation plays a critical role in anxiety, depression, and cognitive impairment. Sleep loss disrupts the host's immune balance and increases neuroinflammation. This study explored whether chronic sleep deprivation aggravates lipopolysaccharide-induced anxiety, depression, and cognitive impairment and assessed the underlying mechanisms. Lipopolysaccharide (250 μg/kg) was administered to adult mice for 9 days, accompanied with daily intermittent sleep deprivation from 12:00 to 18:00 by using an activity wheel. Anxiety, depression, and cognitive function were evaluated using a task battery consisting of an open field, elevated plus maze, tail suspension, forced swimming, and Morris water maze tests. The levels of pro-inflammatory cytokines and synaptic plasticity-associated proteins were examined by enzyme-linked immunosorbent assay and western blot, respectively. The results showed that lipopolysaccharide increased anxiety- and depression-like behaviors, impaired cognitive function, uprelated interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), and decreased brain-derived neurotrophic factor (BDNF), postsynaptic density-95 (PSD-95), and synaptophysin (SYN), which were aggravated by chronic sleep deprivation. These results suggest that chronic sleep deprivation exerted adverse effects on lipopolysaccharide-induced anxiety, depression, and cognitive impairment, which was associated with changes in pro-inflammatory cytokines and synaptic plasticity associated proteins.

Ketamine alleviates fear memory and spatial cognition deficits in a PTSD rat model via the BDNF signaling pathway of the hippocampus and amygdala

BackgroundPost-traumatic stress disorder (PTSD) is associated with traumatic stress experiences. This condition can be accompanied by learning and cognitive deficits. Studies have demonstrated that ketamine can rapidly and significantly alleviate symptoms in patients with chronic PTSD. Nonetheless, the effects of ketamine on neurocognitive impairment and its mechanism of action in PTSD remain unclear. MethodsIn this study, different concentrations of ketamine (5, 10, 15, and 20 mg/kg, i.p.) were evaluated in rat models of single prolonged stress and electrophonic shock (SPS&S). Expression levels of brain-derived neurotrophic factor (BDNF) and post-synaptic density-95 (PSD-95) in the hippocampus (HIP) and amygdala (AMG) were determined by Western blot analysis and immunohistochemistry. ResultsThe data showed that rats subjected to SPS&S exhibited significant PTSD-like cognitive impairment. The effect of ketamine on SPS&S-induced neurocognitive function showed a U-shaped dose effect in rats. A single administration of ketamine at a dosage of 10–15 mg/kg resulted in significant changes in behavioral outcomes. These manifestations of improvement in cognitive function and molecular changes were reversed at high doses (15–20 mg/kg). ConclusionOverall, ketamine reversed SPS&S-induced fear and spatial memory impairment and the down-regulation of BDNF and BDNF-related PSD-95 signaling in the HIP and AMG. A dose equal to 15 mg/kg rapidly reversed the behavioral and molecular changes and promoted the amelioration of cognitive dysfunction. The enhanced association of BDNF signaling with PSD-95 effects could be involved in the therapeutic efficiency of ketamine for PTSD.

Exaggerated translational repression of FMRP in AD synapses

AbstractBackgroundAlzheimer’s Disease (AD) is a progressive cognitive disorder where synapse loss has been well documented. Identifying and restoring molecular targets that are involved in synapse loss is crucial in restoring balanced synaptic function and communication. FMRP is an RNA‐binding protein that is essential protein for synapse formation and stability, and is understudied in AD. Understanding how FMRP may be dysregulated at the synaptic level in AD is integral in developing treatments for AD.MethodRNA‐immunoprecipitation of DJ‐1 was performed to detect whether DJ‐1 associates with the mRNA coding for FMRP. Synaptoneurosomes and postsynaptic densities we isolated from AD rodent model APP/PS1deltaE9 and postmortem human AD patients, as well as from appropriate controls, and performed Western blotting to analyze FMRP protein expression. SUnSET‐PLA assay was utilized to determine de novo synthesis of FMRP in DJ‐1 overexpression.ResultDJ‐1, which is an RNA‐binding protein that is overexpressed in AD synapses, associates with Fmr1, the mRNA coding for the protein FMRP. FMRP expression is decreased in AD synapses, as well as postsynaptic densities. When DJ‐1 is overexpressed in WT cultures, there is less newly synthesized FMRP.ConclusionHere, we show that DJ‐1 associates with Fmr1, which codes for another RNA‐binding protein, FMRP. DJ‐1 and FMRP are aberrantly expressed in AD synapses. DJ‐1 is overexpressed in AD synapses while FMRP is reduced. Furthermore, when DJ‐1 is overexpressed in WT cultures, FMRP synthesis is reduced, suggesting that DJ‐1 is a translational repressor of FMRP. Therefore, the reduction of FMRP in AD synapses are due to overexpression of DJ‐1, and the rescue of FMRP expression could potentially rescue synaptic loss in AD.

The extent of Lead‐induced Pathogenesis of Alzheimer’s disease, Synaptic Dysfunction and Cognitive Impairment in Rats

AbstractBackgroundThe hallmarks of Alzheimer’s disease (AD), like amyloid plaques and neurofibrillary tangles, are constituted of amyloid beta (Aβ) peptide and phosphorylated tau, respectively. Many studies reported the relationship between lead exposure and the progression of AD. However, the extent of lead‐induced pathogenesis and changes in proteins regulating synaptic plasticity in AD is lacking. The proposed study is designed to evaluate the pathogenesis of AD, synaptic dysfunction and cognitive impairment following lead exposure in rats.MethodThirty (30) Wistar rats (3 weeks old) will be obtained, acclimatized for one week, and randomly divided into five groups (n = 6). The rats will receive distilled deionized water containing 0% lead acetate [Pb2+] (ddH2O) or 0.5% [Pb2+] (ddH2O + 0.5% Pb2+) solution with a standard rat diet. Group I (baseline) will receive ddH2O for three (3) weeks. Group II (control) will receive ddH2O for nine (9) weeks. Groups III, IV, and V will receive (ddH2O + 0.5% Pb2+) solution for 3, 6, and 9 weeks respectively. Cognitive function will be conducted using 8‐ARWM as well as object recognition tests. The hippocampus will be extracted for immunohistochemical and biochemical studies. The levels of β‐secretase, Aβ42, tau protein (p‐tau), NMDAR subunit NR2B, postsynaptic density protein 95 (PSD‐95), Synaptophysin (SYP), and brain‐derived neurotrophic factor (BDNF) will be determined using Enzyme‐linked immunosorbent assay (ELISA) method. The expression levels of Aβ42, neurofibrillary tangle (NFT), NR2B, PSD‐95, and SYN will be determined using the immunohistochemical method. The expression of β‐secretase and BDNF will be determined using quantitative real‐time PCR.ResultLead could affect the levels of β‐secretase, Aβ42, p‐tau, NR2B, PSD‐95, SYP BDNF; the expression of Aβ42, NFT, NR2B, PSD‐95, SYN, and BDNF; and cognitive function.ConclusionThe results could reveal the extent to which lead‐induced pathogenesis, synaptic dysfunction and cognitive impairment in AD

Stauntonia chinensis injection relieves neuropathic pain by increasing the expression of PSD-95 and reducing the proliferation of phagocytic microglia.

Neuroinflammation induced by engulfment of synapses by phagocytic microglia plays a crucial role in neuropathic pain. Stauntonia chinensis is extracted from Stauntonia chinensis DC, which has been used as a traditional Chinese medicine to control trigeminal neuralgia or sciatica. However, the specific anti-neuralgia mechanism of Stauntonia chinensis is unknown. In this study, the analgesic effect of Stauntonia chinensis injection (SCI) in mice with neuropathic pain and the possible mechanisms are explored. We find that a local injection of 0.1 mL Stauntonia chinensis for 14 days can considerably relieve mechanical hyperalgesia and thermal hyperalgesia in mice with sciatic chronic constriction injury (CCI). Immunofluorescence staining shows that SCI reduces neuroinflammation in the spinal cord of CCI mice. RNA sequencing reveals that the expression of postsynaptic density protein 95 (PSD-95), a postsynaptic scaffold protein, is downregulated in the spinal cord of CCI mice, but upregulated after SCI administration. Immunofluorescence experiments also demonstrate that SCI administration reverses microglia proliferation and PSD-95 downregulation in CCI mice. These data suggest that SCI relieves neuropathic pain by increasing the expression of PSD-95 and reducing the proliferation of phagocytic microglia.