Postsynaptic Density Research Articles

5-HT2A Receptor Knockout Mice Show Sex-Dependent Differences following Acute Noribogaine Administration.

Noribogaine (noribo) is the primary metabolite from ibogaine, an atypical psychedelic alkaloid isolated from the root bark of the African shrub Tabernanthe iboga. The main objective of this study was to test the hypothesis that molecular, electrophysiological, and behavioral responses of noribo are mediated by the 5-HT2A receptor (5-HT2AR) in mice. In that regard, we used male and female, 5-HT2AR knockout (KO) and wild type (WT) mice injected with a single noribo dose (10 or 40 mg/kg; i.p.). After 30 min., locomotor activity was recorded followed by mRNA measurements by qPCR (immediate early genes; IEG, glutamate receptors, and 5-HT2AR levels) and electrophysiology recordings of layer V pyramidal neurons from the medial prefrontal cortex. Noribo 40 decreased locomotion in male, but not female WT. Sex and genotype differences were observed for IEG and glutamate receptor expression. Expression of 5-HT2AR mRNA increased in the mPFC of WT mice following Noribo 10 (males) or Noribo 40 (females). Patch-clamp recordings showed that Noribo 40 reduced the NMDA-mediated postsynaptic current density in mPFC pyramidal neurons only in male WT mice, but no effects were found for either KO males or females. Our results highlight that noribo produces sexually dimorphic effects while the genetic removal of 5HT2AR blunted noribo-mediated responses to NMDA synaptic transmission.

Simple Method for the Preparation of Postsynaptic Density Fraction from Mouse Brain.

Postsynaptic density (PSD) is a morphologically and functionally specialized postsynaptic membrane structure of excitatory synapses. It contains hundreds of proteins such as neurotransmitter receptors, adhesion molecules, cytoskeletal proteins, and signaling enzymes. The study of the molecular architecture of the PSD is one of the most intriguing issues in neuroscience research. The isolation of the PSD from the brain of an animal is necessary for subsequent biochemical and morphological analyses. Many laboratories have developed methods to isolate PSD from the animal brain. In this chapter, we present a simple method to isolate PSD from the mouse brain using sucrose density gradient-based purification of synaptosomes followed by detergent extraction.

Deep insights into the mechanism of isorhamnetin's anti-motion sickness effect based on photoshoproteomics.

Isorhamnetin has recently been found to exhibit a remarkable anti-motion sickness effect, yet the underlying mechanism is still unclear. Herein, network pharmacology was employed to conduct a preliminary analysis on the possible biological processes involved. Results showed that common targets were localized in membranes, mitochondria, and glutamatergic synapses. In particular, protein phosphorylation, protein serine/threonine/tyrosinase activity and signal transduction might play a role in isorhamnetin's anti-motion sickness effect. Thus, mice phosphoproteomics analysis was further performed to explore the phosphorylated protein changes in the motion sickness process. Results showed that differentially phosphorylated proteins have an effect on postsynaptic density, glutamatergic synapses and other sites and are involved in various neurodegenerative disease pathways, endocytic pathways, cAMP signaling pathways and MAPK signaling pathways. Two key differentially phosphorylated proteins in glutamatergic synapses, namely, DLGAP and EPS8, might play key roles in isorhamnetin's anti-motion sickness process. The final molecular experimental verification results from qRT-PCR and western blot analyses indicated that isorhamnetin firstly regulates glutamatergic synapses and then reduces the excitability of the vestibular nucleus through inhibiting the NMDAR1/CaMKII/CREB signaling pathway, ultimately alleviating a series of symptoms of motion sickness in mice. The findings of this study provide valuable insights and a useful theoretical basis for the application of isorhamnetin as a new anti-motion sickness food ingredient.

Super-Resolution Imaging of Tau Proteins in Isolated and Immobilized Brain Synaptosomes.

Tau protein has important physiological functions at both presynaptic and postsynaptic terminals. Pathological tau species are also associated with synaptic dysfunctions in several neurodegenerative disorders, especially Alzheimer's disease. To understand tau distribution inside synaptic compartments, super-resolution imaging is required. Here, we describe a facile protocol to immobilize and image brain synaptosomes without aggregation artefacts, by substituting the standard fixative paraformaldehyde with ethylene glycol bis(succinimidyl succinate) (EGS). Super-resolution imaging of tau proteins is achieved through three-color direct stochastic optical reconstruction microscopy (dSTORM). Tau protein is found to colocalize with synaptic vesicles as well as postsynaptic densities.

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ON THE BACK COVER: Schematic illustration that shows: In pathology, Tau (in green) targets the tyrosine kinase Fyn (yellow) to dendritic spines, where it phosphorylates subunit NR2b of the NMDA receptor (NMDAR, dark blue at the postsynaptic density), which leads to recruitment of PSD‐95 (light blue) and formation of NMDAR/PSD95 complexes. Aβ oligomers (orange, extracellular) induce excitotoxicity by signalling through NMDAR/PSD95 complexes.Credit: Alison Carlisle, Queensland Brain Institute, The University of Queensland.image

Loss of the E3 ubiquitin ligase TRIM67 alters the post-synaptic density proteome.

The E3 ubiquitin ligase TRIM67 is enriched in the central nervous system and is required for proper neuronal development. Previously we demonstrated TRIM67 coordinates with the closely related E3 ubiquitin ligase TRIM9 to regulate cytoskeletal dynamics downstream of the netrin-1 during axon guidance and axon branching in early neuronal morphogenesis. Interestingly, loss of Trim67 impacts cognitive flexibility in a spatial learning and memory task. Despite this behavioral phenotype, it was previously uninvestigated if TRIM67 was involved in synapse formation or function. Here we demonstrate TRIM67 localizes to the post-synaptic density (PSD) within dendritic spines. Furthermore, we show that loss of Trim67 significantly changes a subset of proteins within the PSD proteome, including changes in the regulation of the actin and microtubule cytoskeletons. Collectively, our data propose a synaptic role for TRIM67.

Modulation of the conformational landscape of the PDZ3 domain by perturbation on a distal non-canonical α3 helix: decoding the microscopic mechanism of allostery in the PDZ3 domain.

While allosteric signal transduction is crucial for protein signaling and regulation, the dynamic process of allosteric communication remains poorly understood. The third PDZ domain (PDZ stands for the common structural domain shared by the postsynaptic density protein (PSD95), Drosophila disc large tumor suppressor (DlgA), and zonula occludens-1 protein (ZO-1)) serves as a classic example of a single-domain allosteric protein, demonstrating a long-range coupling between the C-terminal α helix (known as the α3 helix) and ligand binding. A molecular level understanding of how the α3 helix modulates the ligand binding affinity of the PDZ3 domain is still lacking. In this study, extensive molecular dynamics simulations corroborated with principal component analysis (PCA), ligand binding free energy calculations, energetic frustration analysis and Markov state model analysis are employed to uncover such molecular details. We demonstrate the definite presence of a binding competent closed-like state in the conformational landscape of wild-type PDZ3. The population modulations of this closed state and other binding incompetent states in the landscape due to α3-truncation/mutation of PDZ3 are explored. A correlation between the closed state population and calculated binding free energy is established, which supports the conformation selection mechanism. Covariance analysis identified the presence of correlated motion between two distant loops (β1-β2 and β2-β3) in the wild-type PDZ3 system, which weakened due to truncation/mutation in the distant α3 helix. It has also been observed that whenever the α3 helix was perturbed, the β2-β3 loop got further away from the binding groove and it is found to be correlated with the binding free energy values. Energetic frustration analysis of the PDZ3 domain also showed that the β2-β3 loop is highly frustrated. Finally, MSM analysis revealed a relevant timescale (closed to open state transition), which is similar to the observed experimental signal transduction timescale for the system. These observations led to the conclusion that the distantly located α3 helix plays a pivotal role in regulating the conformational landscape of the PDZ3 domain, determining the ligand binding affinity and resulting in allosteric behavior of the domain.

Proteomic Characteristics of the Prefrontal Cortex and Hippocampus in Mice with Chronic Ketamine-Induced Anxiety and Cognitive Impairment

Schizophrenia, a complex psychiatric disorder with diverse symptoms, has been linked to ketamine, known for its N-methyl-D-aspartate (NMDA) receptor antagonistic properties. Understanding the distinct roles and mechanisms of ketamine is crucial, especially regarding its induction of schizophrenia-like symptoms. Recent research highlights the impact of ketamine on key brain regions associated with schizophrenia, specifically the prefrontal cortex (PFC) and hippocampus (Hip). This study focused on these regions to explore proteomic changes related to anxiety and cognitive impairment in a chronic ketamine-induced mouse model of schizophrenia. After twelve consecutive days of ketamine administration, brain tissues from these regions were dissected and analyzed. Using tandem mass tag (TMT) labeling quantitative proteomics techniques, 34,797 and 46,740 peptides were identified in PFC and Hip, corresponding to 5,668 and 6,463 proteins, respectively. In the PFC, a total of 113 proteins showed differential expression, primarily associated with the immuno-inflammatory process, calmodulin, postsynaptic density protein, and mitochondrial function. In the Hip, 129 differentially expressed proteins were screened, mainly related to synaptic plasticity proteins and mitochondrial respiratory chain complex-associated proteins. Additionally, we investigated key proteins within the glutamatergic synapse pathway and observed decreased expression levels of phosphorylated CaMKII and CREB. Overall, the study unveiled a significant proteomic signature in the chronic ketamine-induced schizophrenia mouse model, characterized by anxiety and cognitive impairment in both the PFC and Hip, and this comprehensive proteomic dataset may not only enhance our understanding of the molecular mechanisms underlying ketamine-related mental disorders but also offer valuable insights for future disease treatments.

An enriched environment promotes cognitive recovery and cerebral blood flow in aged mice under sevoflurane anaesthesia.

Sevoflurane is an inhalation anaesthetic agent widely used in clinical settings. Despite good surgical outcomes using sevoflurane, patients frequently develop postoperative cognitive dysfunction (POCD). An enriched environment (EE), as a rehabilitation technique, could provide objects and tools to facilitate neuromotor and visual stimuli and brain activity, and is reported to improve cognitive functions. We aim to investigate the impairments of sevoflurane inhalation on cognitive function in mice and determine the benefits of EE in ameliorating POCD. Eighteen-month-old mice were exposed to sevoflurane inhalation for 2 h and then placed in standard environment (SE) or EE cages. The mice without sevoflurane exposure in standard or EE cages were used as controls. The behavioural tests include Morris water maze, Y maze and novel object recognition. Magnetic resonance imaging (MRI) was used to determine the blood circulation in the brains. The proangiogenic factors (CD31, angiopoietin-1, vascular endothelial growth factor, and N-cadherin) and neurotrophic (brain-derived neurotrophic factor, post-synaptic density protein 95) expression in hippocampus of aged mice were evaluated by Western blotting and RT-PCR analysis. Sevoflurane-exposed mice demonstrated reduced performance in learning, memory and spatial memory tests. Enriched environment improved the behavioural performance of sevoflurane-exposed animals. Sevoflurane exposure reduced the blood flow in the brains, and these effects were ameliorated by EE habitation. The EE also promoted the expression of angiogenic and neurotropic factors in sevoflurane-exposed animals. In summary, EE is effective in ameliorating the side-effects of sevoflurane exposure in aged mice.

Chlorogenic Acid Mitigates Ferroptosis by Activating the Nrf2/GPX4 Pathway through Keap1 Blockade in Vascular Dementia Rats

Chlorogenic acid (CGA) is a dietary phenolic acid widely distributed in daily food and plants, but its role in vascular dementia (VaD) is still unclear. Hence, this study aimed to investigate whether CGA could rescue cognitive impairment in VaD, providing a new option for drug discovery. Novel object recognition and Morris water maze experiments revealed that CGA enhanced the learning and memory abilities in VaD rats. Nissl staining, Western blot, and transmission electron microscopy results demonstrated that CGA inhibited neuronal loss in the hippocampal CA1 region of VaD rats, increased the expression of synaptic‐related markers SYP and PSD95, thickened the postsynaptic density, and suppressed mitochondrial ridge rupture in neurons. GSH detection, MDA detection, and Western blot experiments indicated that CGA alleviated hippocampal GSH reduction and MDA elevation and increased the protein levels of GPX4 and SLC7A11. Cell activity, ROS detection, lipid peroxidation detection, intracellular Fe2+ level detection, GSH detection, and Western blot revealed that CGA inhibited the increase of intracellular Fe2+, ROS, and lipid peroxidation induced by OGD in PC12 cells, mitigated GSH reduction, and increased the protein levels of GPX4, SLC7A11, SYP, and PSD95. Western blot and immunofluorescence staining showed that CGA increased the expression of pSer40‐Nrf2 in the hippocampal tissue of VaD rats and PC12 cells, promoting Nrf2 nuclear translocation. Knockdown of Nrf2 prevented CGA from rescuing ferroptosis and synaptic damage induced by OGD in PC12 cells, as well as Nrf2 pathway activation. Molecular docking analysis suggested that CGA competitively bound to the Kelch domain of Keap1 with Nrf2 and then promoted Nrf2 release and activated downstream signaling pathways. In conclusion, our study suggests that CGA may activate the Nrf2 signaling pathway by disrupting the interaction between Nrf2 and Keap1 proteins, thereby inhibiting hippocampal neuronal ferroptosis and synaptic damage and ameliorating cognitive impairment in VaD. Practical Applications. Vascular dementia (VaD) stands as the second most prevalent type of dementia following Alzheimer’s disease. However, there is no effective clinical treatment drug available, and its pathogenic mechanisms remain elusive. This study proposed that CGA might activate the Nrf2‐GPX4 signaling pathway by competitively binding to Keap1, thereby attenuating hippocampal neuronal ferroptosis and synaptic damage and consequently ameliorating cognitive impairment in VaD. Our study may provide a novel option for drug research and development for VaD.

A106: Aerobic Exercise Modulates GPCR/cAMP/PKA Signaling Pathway and Complement-Microglia Axis to Prevent Synaptic Loss in APP/PS1 Mice

Purpose: Synaptic failure serves as a primary contributor to memory dysfunction in Alzheimer's disease (AD). Physical exercise has demonstrated the potential to thwart and delay degenerative alterations in memory functions linked to AD. Investigating the underlying mechanisms may unveil crucial insights into early pathological changes, offering breakthroughs for both understanding and treating AD. Methods: We utilized 3-month-old APP/PS1 mice and subjected them to a 12-week aerobic exercise intervention. The spatial learning and memory functions of the mice were assessed using the Morris water maze test, while Golgi staining was employed to determine dendritic spine density in each mouse group. To analyze the potential mechanisms mediating the effects of exercise intervention in the AD brain, we conducted RNA sequencing. Subsequently, pathway enrichment analysis, immunofluorescence, real-time quantitative PCR, and western blotting were employed to elucidate the impact of regular aerobic exercise on the GPCR/cAMP/PKA signaling pathway and complement-microglia axis. Results: Our findings reveal that a 12-week aerobic exercise intervention significantly enhanced spatial learning and memory function in APP/PS1 mice. Moreover, it led to a substantial increase in dendritic spine density and elevated expression of postsynaptic density protein 95 (PSD-95) in the cortex and hippocampus. Aerobic exercise demonstrated the ability to improve the expression of certain genes and enhance synaptic pathways in the brains of APP/PS1 mice. This suggests that aerobic exercise facilitates synaptic growth in APP/PS1 mice by modulating G protein-coupled receptors (GPCRs) and activating the cAMP signaling pathway, with significant alterations observed in the expressions of Hcar1 and Vipr2 genes. Furthermore, exercise intervention resulted in the significant down-regulation (P < 0.05 or P < 0.01) of cAMP, p-PKA/PKA, GluA1, and CaMKII protein expressions in the brain tissue of APP/PS1 mice, which were subsequently up-regulated after exercise (P < 0.01). Notably, regular aerobic exercise effectively suppressed the activation of IBA-1+ microglia cells (P < 0.01), reversed changes in M1 phenotype markers (Cd86 and iNOS) and M2 phenotype markers (Arg-1) of microglia cells (P < 0.05), reduced the production of promoters C1q and central factor C3 in the macrosomatic cascade (P < 0.05), and prevented the colocalization of microglia and PSD-95 (P < 0.01). Conclusion: In conclusion, our results indicate that physical exercise plays a pivotal role in fostering early synaptic growth and averting synaptic loss in Alzheimer's disease (AD). This effect may be attributed to the regulation of the G protein-coupled receptors (GPCRs)/cAMP/PKA signaling pathway and the suppression of complement-mediated microglial phagocytosis of synapses. This mechanistic insight underscores the inherent contribution of exercise to health promotion, offering potential avenues for synaptic-focused interventions in the early stages of AD treatment.

The effect of acupuncture on hippocampal synaptic plasticity in Alzheimer Disease Mouse Model: Possible mechanisms of energy transportation in neurons

Objective: To study the mechanism of acupuncture-promoted synaptic plasticity in hippocampal neurons of senescence-accelerated mouse-prone 8 mice with respect to neuronal energy substrate transport. Methods: Forty-three senescence-accelerated mouse-prone 8 mice were randomly divided into Alzheimer’s disease model and acupuncture groups, and twenty senescence-accelerated mouse resistant 1 mice were used as the normal group. Acupuncture group received acupuncture at the “Baihui” and “Yongquan” acupoints for 40 days. The Morris water maze was used to detect the learning and memory capabilities of the mice, and in vivo electrophysiology and transmission electron microscopy were used to evaluate the synaptic functional and structural plasticity of hippocampal neurons. Glucose, lactate, and pyruvate in the hippocampal intercellular fluid, as well as the expression of glucose transporter 3 and monocarboxylate transporters 2 and 4, were analyzed using microdialysis, immunohistochemistry, and western blotting. Results: The Morris water maze data showed that compared with Alzheimer’s disease model mice, mice of acupuncture group exhibited a shorter escape latency, increased number of effective zone crossings, and increased percentage of swimming distance in the target quadrant. Acupuncture increased the postsynaptic density thickness of Alzheimer’s disease model mice and decreased the latency amplitude after tetanic stimulation and width of the synaptic cleft. Glucose, lactate, and pyruvate contents in the hippocampal intercellular fluid were significantly reduced in Alzheimer’s disease model mice, but the reductions were more pronounced after acupuncture treatment. Furthermore, acupuncture prominently elevated glucose transporter 3 and monocarboxylate transporters 2 expression in the CA1 and dentate gyrus regions of the hippocampus of Alzheimer’s disease model mice. The elevation of monocarboxylate transporters 4 expression mostly appeared in the CA1 region. Conclusion: Acupuncture improved the learning and memory capabilities as well as the hippocampal synaptic structural plasticity of senescence-accelerated mouse-prone 8 mice. Its effects were likely related to the regulation of glucose transporter 3, monocarboxylate transporters 2, and monocarboxylate transporters 4 expression in the hippocampal tissue to increase the energy substrate reserve of neurons and improve the substrate-matching ability of the cellular response.

Gens PSD-95 and GSK-3β expression improved by hair follicular stem cells-conditioned medium enhances synaptic transmission and cognitive abilities in the rat model of vascular dementia.

Vascular dementia (VaD) is a common type of dementia. The aim of this study was to investigate the cellular and molecular mechanism of conditioned medium (CM) in VaD. The rats were divided into four groups of control (n=9), sham-operation (n=10), VaD with vehicle (n=9), and VaD with CM (n=12) that received CM on days 4, 14, and 24 after 2VO. Before sacrificing the rats, cognitive performance was assessed through the open-field (OP), passive-avoidance, and Morris-water maze. The field-potential recording was used to investigate basal synaptic transmission (BST) and long-term potentiation (LTP). Subsequently, the hippocampus was dissected, and real-time PCR was used to quantify the expression levels of β1-catenin, insulin-like growth factor-1 (IGF-1), transforming growth factor-beta (TGF-β), glycogen synthase kinase-3β (GSK-3β), postsynaptic density protein 95 (PSD-95), and NR2B genes. The results indicated impaired performance in behavioral tests in 2VO rats, coupled with reductions in BST and LTP induction. The expression levels of β1-catenin, IGF-1, PSD-95, and TGF-β genes decreased, whereas NR2B and GSK-3β expression increased. Treatment with CM restores the expression of PSD-95 and GSK-3β as well as fear-memory, spatial learning, and grooming number without a positive effect on memory retrieval, time spent on the periphery and center of OP. The BST recovered upon administration of CM but, the LTP induction was still impaired. The recovery of BST in VaD rats appears to be the most important outcome of this study which is caused by the improvement of gene expression and leads to the restoration of fear memory.

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.