NMDA receptor in the hippocampus alters neurobehavioral phenotypes through inflammatory cytokines in rats with sporadic Alzheimer-like disease

Neuroprotective effects of MK-801 against cerebral ischemia reperfusion

Introduction

& Objective: Cerebral ischemia/reperfusion (I/R) injury, the second cause of death globally, involves increased NMDA receptor activity leading to neuronal damage due to excessive sodium and calcium ion entry. Therefore, targeting NMDA receptor may potentially reduce cell death induced by brain injury. Our study aimed to investigate the role of NMDA receptors in hippocampal neuronal activity induced by I/R.

Methods

In this study, Wistar rats were divided into four groups: sham, I/R, I/R + MK801, and I/R + NMDA. Cerebral I/R injury was induced by temporarily occluding the common and vertebral carotid arteries, followed by reperfusion. MK801 or NMDA was administered to the rats after a specific reperfusion time. Neuronal density and cell morphology in the hippocampal CA1 region were assessed using Nissl and H&E staining. The expression of BDNF, p-CREB, and c-fos was evaluated through Western blot analysis. Additionally, neuronal activity in CA1 pyramidal neurons were examined using single unit recording technique.

Results

Our results showed that cerebral I/R injury caused significant damage to CA1 pyramidal neurons compared to the sham group. However, treatment with MK-801 improved hippocampal cell survival compared to the I/R group. Furthermore, MK-801 administration in I/R rats increased BDNF, c-fos, and p-CREB levels while decreasing cleaved caspase-3 activity compared to the I/R group. Additionally, electrophysiological data showed that MK-801 increased firing rates of CA1 pyramidal neurons during the reperfusion phase.

Conclusion

MK-801 shows promise as a therapeutic agent for cerebral I/R injury by enhancing cell survival, upregulating neuroplasticity factors, and increasing firing rates of CA1 pyramidal neurons. It exerts a specific protective effect against cerebral I/R injury.

Genetic architecture of hippocampus subfields volumes in Alzheimer's disease

BACKGROUND

The hippocampus is a heterogeneous structure, comprising histologically and functionally distinguishable hippocampal subfields. The volume reductions in hippocampal subfields have been demonstrated to be linked with Alzheimer's disease (AD). The aim of our study is to investigate the hippocampal subfields' genetic architecture based on the Alzheimer's Disease Neuroimaging Initiative (ADNI) data set.

METHODS

After preprocessing the downloaded genetic variants and imaging data from the ADNI database, a co-sparse reduced rank regression model was applied to analyze the genetic architecture of hippocampal subfields volumes. Homology modeling, docking, molecular dynamics simulations, and Co-IP experiments for protein-protein interactions were used to verify the function of target protein on hippocampal subfields successively. After that, the association analysis between the candidated genes on the hippocampal subfields volume and clinical scales were performed.

RESULTS

The results of the association analysis revealed five unique genetic variants (e.g., ubiquitin-specific protease 10 [USP10]) changed in nine hippocampal subfields (e.g., the granule cell and molecular layer of the dentate gyrus [GC-ML-DG]). Among five genetic variants, USP10 had the strongest interaction effect with BACE1, which affected hippocampal subfields verified by MD and Co-IP experiments. The results of association analysis between the candidated genes on the hippocampal subfields volume and clinical scales showed that candidated genes influenced the volume and function of hippocampal subfields.

CONCLUSIONS

Current evidence suggests that hippocampal subfields have partly distinct genetic architecture and may improve the sensitivity of the detection of AD.

N-methyl-d-aspartate receptors: Structure, function, and role in organophosphorus compound poisoning

Acute organophosphorus compound (OP) poisoning induces symptoms of the cholinergic crises with the occurrence of severe epileptic seizures. Seizures are induced by hyperstimulation of the cholinergic system, but are enhanced by hyperactivation of the glutamatergic system. Overstimulation of muscarinic cholinergic receptors by the elevated acetylcholine causes glutamatergic hyperexcitation and an increased influx of Ca2+ into neurons through a type of ionotropic glutamate receptors, N-methyl-d-aspartate (NMDA) receptors (NMDAR). These excitotoxic signaling processes generate reactive oxygen species, oxidative stress, and activation of the neuroinflammatory response, which can lead to recurrent epileptic seizures, neuronal cell death, and long-term neurological damage. In this review, we illustrate the NMDAR structure, complexity of subunit composition, and the various receptor properties that change accordingly. Although NMDARs are in normal physiological conditions important for controlling synaptic plasticity and mediating learning and memory functions, we elaborate the detrimental role NMDARs play in neurotoxicity of OPs and focus on the central role NMDAR inhibition plays in suppressing neurotoxicity and modulating the inflammatory response. The limited efficacy of current medical therapies for OP poisoning concerning the development of pharmacoresistance and mitigating proinflammatory response highlights the importance of NMDAR inhibitors in preventing neurotoxic processes and points to new avenues for exploring therapeutics for OP poisoning.

Impaired erythropoietin-producing hepatocellular B receptors signaling in the prefrontal cortex and hippocampus following maternal immune activation in male rats

An environmental risk factor for schizophrenia (SZ) is maternal infection, which exerts longstanding effects on the neurodevelopment of offspring. Accumulating evidence suggests that synaptic disturbances may contribute to the pathology of the disease, but the underlying molecular mechanisms remain poorly understood. Erythropoietin-producing hepatocellular B (EphB) receptor signaling plays an important role in synaptic plasticity by regulating the formation and maturation of dendritic spines and regulating excitatory neurotransmission. We examined whether EphB receptors and downstream associated proteins are susceptible to environmental risk factors implicated in the etiology of synaptic disturbances in SZ. Using an established rodent model, which closely imitates the characteristics of SZ, we observed the behavioral performance and synaptic structure of male offspring in adolescence and early adulthood. We then analyzed the expression of EphB receptors and associated proteins in the prefrontal cortex and hippocampus. Maternal immune activation offspring showed significantly progressive cognitive impairment and pre-pulse inhibition deficits together with an increase in the expression of EphB2 receptors and NMDA receptor subunits. We also found changes in EphB receptor downstream signaling, in particular, a decrease in phospho-cofilin levels which may explain the reduced dendritic spine density. Besides, we found that the AMPA glutamate, another glutamate ionic receptor associated with cofilin, decreased significantly in maternal immune activation offspring. Thus, alterations in EphB signaling induced by immune activation during pregnancy may underlie disruptions in synaptic plasticity and function in the prefrontal cortex and hippocampus associated with behavioral and cognitive impairment. These findings may provide insight into the mechanisms underlying SZ.

MK-801 and cognitive functions: Investigating the behavioral effects of a non-competitive NMDA receptor antagonist

RATIONALE

MK-801 (dizocilpine) is a non-competitive NMDA receptor antagonist originally explored for anticonvulsant potential. Despite its original purpose, its amnestic properties led to the development of pivotal models of various cognitive impairments widely employed in research and greatly impacting scientific progress. MK-801 offers several advantages; however, it also presents drawbacks, including inducing dose-dependent hyperlocomotion or ambiguous effects on anxiety, which can impact the interpretation of behavioral research results.

OBJECTIVES

The present review attempts to summarize and discuss the effects of MK-801 on different types of memory and cognitive functions in animal studies.

RESULTS

A plethora of behavioral research suggests that MK-801 can detrimentally impact cognitive functions. The specific effect of this compound is influenced by variables including developmental stage, gender, species, strain, and, crucially, the administered dose. Notably, when considering the undesirable effects of MK-801, doses up to 0.1 mg/kg were found not to induce stereotypy or hyperlocomotion.

CONCLUSION

Dizocilpine continues to be of significant importance in preclinical research, facilitating the exploration of various procognitive therapeutic agents. However, given its potential undesirable effects, it is imperative to meticulously determine the appropriate dosages and conduct supplementary evaluations for any undesirable outcomes, which could complicate the interpretation of the findings.

Fluoxetine combined with swimming exercise synergistically reduces lipopolysaccharide-induced depressive-like behavior by normalizing the HPA axis and brain inflammation in mice

Major depression disorder is a debilitating psychiatric disease affecting millions of people worldwide. This disorder is the leading cause of morbidity and mortality in high-income countries. Selective serotonin reuptake inhibitors such as fluoxetine are first-line drugs for treating depression-related disorders, but not all patients respond well to these antidepressants. This study aimed to evaluate whether fluoxetine combined with aerobic exercise can affect lipopolysaccharide (LPS)-induced depressive-like behavior, hypothalamic-pituitary-adrenal (HPA) axis dysregulation, and brain inflammation in mice. Male mice were exposed to fluoxetine, swimming exercise, or a combination of both and finally treated with LPS. We measured depression-related symptoms such as anhedonia, behavioral despair, weight gain, and food intake. Hormones (corticosterone and testosterone) and cytokines (IL-1β, IL-6, TNF-α, IL-10) were also measured in serum and brain (hippocampus and prefrontal cortex), respectively. The findings indicated that LPS induced anhedonia and behavioral despair and increased corticosterone, hippocampal IL-1β, TNF-α, and decreased testosterone and hippocampal IL-10 in mice. Fluoxetine and exercise separately reduced LPS-induced depressive-like behavior, while their combination synergistically reduced these symptoms in LPS-treated mice. We found fluoxetine alone increased food intake and body weight in LPS-treated mice. Fluoxetine and exercise combination reduced corticosterone, hippocampal TNF-α, and prefrontal IL-6 and TNF-α levels and increased testosterone and hippocampal and prefrontal IL-10 levels more effectively than fluoxetine alone in LPS-treated mice. This study suggests that swimming exercise combined with fluoxetine can affect depression-related behavior, HPA axis, and brain inflammation more effectively than when they are used separately.

Levodopa-induced dyskinesia: interplay between the N-methyl-D-aspartic acid receptor and neuroinflammation

Parkinson's disease (PD) is a common neurodegenerative disorder of middle-aged and elderly people, clinically characterized by resting tremor, myotonia, reduced movement, and impaired postural balance. Clinically, patients with PD are often administered levodopa (L-DOPA) to improve their symptoms. However, after years of L-DOPA treatment, most patients experience complications of varying severity, including the "on-off phenomenon", decreased efficacy, and levodopa-induced dyskinesia (LID). The development of LID can seriously affect the quality of life of patients, but its pathogenesis is unclear and effective treatments are lacking. Glutamic acid (Glu)-mediated changes in synaptic plasticity play a major role in LID. The N-methyl-D-aspartic acid receptor (NMDAR), an ionotropic glutamate receptor, is closely associated with synaptic plasticity, and neuroinflammation can modulate NMDAR activation or expression; in addition, neuroinflammation may be involved in the development of LID. However, it is not clear whether NMDA receptors are co-regulated with neuroinflammation during LID formation. Here we review how neuroinflammation mediates the development of LID through the regulation of NMDA receptors, and assess whether common anti-inflammatory drugs and NMDA receptor antagonists may be able to mitigate the development of LID through the regulation of central neuroinflammation, thereby providing a new theoretical basis for finding new therapeutic targets for LID.

Adolescent swimming exercise following maternal valproic acid treatment improves cognition and reduces stress-related symptoms in offspring mice: Role of sex and brain cytokines

Valproic acid (VPA) treatment during pregnancy is a risk factor for developing autism spectrum disorder, cognitive deficits, and stress-related disorders in children. No effective therapeutic strategies are currently approved to treat or manage core symptoms of autism. Active lifestyles and physical activity are closely associated with health and quality of life during childhood and adulthood. This study aimed to evaluate whether swimming exercise during adolescence can prevent the development of cognitive dysfunction and stress-related disorders in prenatally VPA-exposed mice offspring. Pregnant mice received VPA, afterwards, offspring were subjected to swimming exercise. We assessed neurobehavioral performances and inflammatory cytokines (interleukin-(IL)6, tumor-necrosis-factor-(TNF)α, interferon-(IFN)γ, and IL-17A) in the hippocampus and prefrontal cortex of offspring. Prenatal VPA treatment increased anxiety-and anhedonia-like behavior and decreased social behavior in male and female offspring. Prenatal VPA exposure also increased behavioral despair and reduced working and recognition memory in male offspring. Although prenatal VPA increased hippocampal IL-6 and IFN-γ, and prefrontal IFN-γ and IL-17 in males, it only increased hippocampal TNF-α and IFN-γ in female offspring. Adolescent exercise made VPA-treated male and female offspring resistant to anxiety-and anhedonia-like behavior in adulthood, whereas it only made VPA-exposed male offspring resistant to behavioral despair, social and cognitive deficits in adulthood. Exercise reduced hippocampal IL-6, TNF-α, IFN-γ, and IL-17, and prefrontal IFN-γ and IL-17 in VPA-treated male offspring, whereas it reduced hippocampal TNF-α and IFN-γ in VPA-treated female offspring. This study suggests that adolescent exercise may prevents the development of stress-related symptoms, cognitive deficits, and neuroinflammation in prenatally VPA-exposed offspring mice.

Pharmacological Characterization of [18F]-FNM and Evaluation of NMDA Receptors Activation in a Rat Brain Injury Model

PURPOSE

NMDA receptors (NMDARs) dysfunction plays a central role in the physiopathology of psychiatric and neurodegenerative disorders whose mechanisms are still poorly understood. The development of a PET (positron emission tomography) tracer able to selectively bind to the NMDARs intra-channel PCP site may make it possible to visualize NMDARs in an open and active state. We describe the in vitro pharmacological characterization of [¹⁸F]-fluoroethylnormemantine ([¹⁸F]-FNM) and evaluate its ability to localize activated NMDA receptors in a rat preclinical model of excitotoxicity.

PROCEDURES

The affinity of the non-radioactive analog for the intra-channel PCP site was determined in a radioligand competition assay using [³H]TCP ([³H]N-(1-[thienyl]cyclohexyl)piperidine) on rat brain homogenates. Selectivity was also investigated by the displacement of specific radioligands targeting various cerebral receptors. In vivo brain lesions were performed using stereotaxic quinolinic acid (QA) injections in the left motor area (M1) of seven Sprague Dawley rats. Each rat was imaged with a microPET/CT camera, 40 min after receiving a dose of 30 MBq + / - 20 of [¹⁸F]-FNM, 24 and 72 h after injury. Nine non-injured rats were also imaged using the same protocol.

RESULTS

FNM displayed IC₅₀ value of 13.0 ± 8.9 µM in rat forebrain homogenates but also showed significant bindings on opioid receptors. In the frontal and left somatosensory areas, [¹⁸F]FNM PET detected a mean of 37% and 41% increase in [¹⁸F]FNM uptake (p < 0,0001) 24 and 72 h after QA stereotaxic injection, respectively, compared to the control group.

CONCLUSIONS

In spite of FNM's poor affinity for NMDAR PCP site, this study supports the ability of this tracer to track massive activation of NMDARs in neurological diseases.

Melatonin treatment improves cognitive deficits by altering inflammatory and neurotrophic factors in the hippocampus of obese mice

Overweight and obesity are associated with an increased risk of developing dementia and cognitive deficits. Neuroinflammation is one of the most important mechanisms behind cognitive impairment in obese patients. In recent years, the neuroendocrine hormone melatonin has been suggested to have therapeutic effects for memory decline in several neuropsychiatric and neurological conditions. However, the effects of melatonin on cognitive function under obesity conditions still need to be clarified. The purpose of this study was to determine whether melatonin treatment can improve cognitive impairment in obese mice. To this end, male C57BL6 mice were treated with a high-fat diet (HFD) for 20 weeks to induce obesity. The animal received melatonin for 8 weeks. Cognitive functions were evaluated using the Y maze, object recognition test, and the Morris water maze. We measured inflammatory cytokines including tumor necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-17A, and brain-derived neurotrophic factor (BDNF) in the hippocampus of obese mice. Our results show that HFD-induced obesity significantly impaired working, spatial and recognition memory by increasing IFN-γ and IL-17A and decreasing BDNF levels in the hippocampus of mice. On the other hand, melatonin treatment effectively improved all cognitive impairments and reduced TNF-α, IFN-γ, and IL-17A and elevated BDNF levels in the hippocampus of obese mice. Taken together, this study suggests that melatonin treatment could have a beneficial role in the treatment of cognitive impairment in obesity.

Effects of chronic vagal nerve stimulation in the treatment of β-amyloid-induced neuropsychiatric symptoms

Alzheimer's Disease (AD) is the leading cause of dementia and, at the time of diagnosis, half of AD patients display at least one neuropsychiatric symptom (NPS). However, there is no effective therapy for NPSs; furthermore, current treatments of NPSs accelerate cognitive decline. Due to the ineffectiveness and negative consequences of current treatments for NPSs, new approaches are strongly needed. Currently, indications for vagal nerve stimulation (VNS) include epilepsy, stroke rehabilitation and major depression but not NPSs or AD. Therefore, we investigated whether chronic VNS can treat NPSs in a rat model of AD. Here, we report the intracerebroventricular injection of amyloid-β (Aβ) results in depression-like behaviors and memory impairment in rats. Chronic VNS (0.8 mA, 500 μs, 30 Hz, 5 min/day) showed strong antidepressant and anxiolytic effects, and improved memory performance. Additionally, the anxiolytic effect of VNS was retained in the non-Aβ-treated rats. VNS also decreased aggressiveness and increased locomotor activity in both Aβ-treated and non-Aβ-treated rats. Recent studies showed VNS alters glutamatergic receptor levels, thus levels of GluA1, GluN2A, and GluN2B were determined. A significant reduction in GluN2B levels was seen in the hippocampus of VNS-treated groups which may relate to the anxiolytic effects and increased locomotor activity of VNS. In conclusion, VNS could be an effective treatment of NPSs, especially depression and anxiety, in AD patients without impairing cognition.

Feature aggregation graph convolutional network based on imaging genetic data for diagnosis and pathogeny identification of Alzheimer's disease

The roles of brain regions activities and gene expressions in the development of Alzheimer's disease (AD) remain unclear. Existing imaging genetic studies usually has the problem of inefficiency and inadequate fusion of data. This study proposes a novel deep learning method to efficiently capture the development pattern of AD. First, we model the interaction between brain regions and genes as node-to-node feature aggregation in a brain region-gene network. Second, we propose a feature aggregation graph convolutional network (FAGCN) to transmit and update the node feature. Compared with the trivial graph convolutional procedure, we replace the input from the adjacency matrix with a weight matrix based on correlation analysis and consider common neighbor similarity to discover broader associations of nodes. Finally, we use a full-gradient saliency graph mechanism to score and extract the pathogenetic brain regions and risk genes. According to the results, FAGCN achieved the best performance among both traditional and cutting-edge methods and extracted AD-related brain regions and genes, providing theoretical and methodological support for the research of related diseases.

Beneficial effects of levetiracetam in streptozotocin-induced rat model of Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder among the elderly. In the light of increasing AD prevalence and lack of effective treatment, new strategies to prevent or reverse this condition are needed. Levetiracetam (LEV) is a newer antiepileptic drug that is commonly used to treat certain types of seizures. Researches indicated that LEV has several other pharmacological activities, including improvement of cognitive function. In this study, the recovery effects of chronic (28 days) administration of LEV (50, 100, and 150 mg/kg, ip) on cognitive deficits caused by the intracerebroventricular (icv) injection of streptozotocin (STZ), as a model for sporadic AD, were evaluated in rats. We also considered the protective effects of LEV against hippocampal cell loss, oxidative damage, acetylcholinesterase (AChE) activity, neuroinflammation, and tauopathy caused by STZ. LEV (100 and 150 mg/kg) significantly attenuated the STZ-induced learning and memory impairments in the passive avoidance and Morris water maze (MWM) tasks. In addition, LEV suppressed STZ-induced hippocampal neuronal loss, while restored alterations in the redox status (lipid peroxides and glutathione), AChE activity, proinflammatory cytokines (IL-1β, IL-6, TNF-α), and hyperphosphorylation of tau linked to STZ administration. In conclusion, our study demonstrated that LEV alleviated hippocampal cell death and memory deficits in STZ-AD rats, through mitigating oxidative damage, suppression of proinflammatory cytokines expression, and inhibition of abnormal tau hyperphosphorylation.

Glibenclamide ameliorates the expression of neurotrophic factors in sevoflurane anaesthesia-induced oxidative stress and cognitive impairment in hippocampal neurons of old rats

Introduction

Several antidiabetic medications have been proposed as prospective treatments for cognitive impairments in type 2 diabetes patients, glibenclamide (GBC) among them. Our research aimed to evaluate the impact of GBC on hippocampal learning memory and inflammation due to enhanced neurotrophic signals induced by inhalation of sevoflurane.

Material and Methods

Rats (Sprague Dawley, both sexes) were assigned to four groups: a control (vehicle, p.o.), GBC (10 mg/kg b.w.; p.o.), low-dose sevoflurane and low-dose sevoflurane + GBC (10 mg/kg b.w.; p.o.) for 23 days. Terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) staining was performed to analyse the count of apoptotic cells and ELISA was conducted to assess the protein signals. A Western blot, a Y-maze test, and a Morris maze test were performed, and the results analysed. Blood and tissues were collected, and isolation of RNA was performed with qRT-PCR.

Results

The Morris maze test results revealed an improvement in the length of the escape latency on days 1 (P < 0.05), 2 (P < 0.01), 3, and 4 in the low-dose Sevo group. Time spent in the quadrant and crossing axis and the percentage of spontaneous alterations showed a substantial decrease in the low-dose Sevo group which received GBC at 10 mg/kg b.w. Significant increases were shown in IL-6 and TNF-α levels in the low-dose Sevo group, whereas a decrease was evident in the GBC group.

Conclusion

Our results indicate that glibenclamide may be a novel drug to prevent sevoflurane inhalation-induced impaired learning and reduce brain-derived neurotrophic factor release, which may be a vital target for the development of potential therapies for cognitive deficits and neurodegeneration.

Chronic developmental exposure to low-dose ([C8mim][PF6]) induces neurotoxicity and behavioural abnormalities in rats

Ionic liquids (ILs) are widely used for their physical and chemical properties. Toxicological assessments of ILs could help to avoid their threat to human health, but these are rarely reported, and no assessments of IL neurotoxicity in mammals have been performed. Here, we aimed to evaluate the neurotoxicity of chronic 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim][PF6]) (0, 1 mg/kg) exposure during development on rats. Our results indicated that chronic exposure to low-dose ([C8mim][PF6]) induces behavioural abnormalities, including cognitive deficits, social communication disorders, and sensory gating function impairment. Moreover, rats subjected to chronic ([C8mim][PF6]) exposure showed hypofunction of glutamatergic excitatory synapses, including increased expression of NMDA receptor subunits, increased density and immaturity of dendritic spines, and increased expression of PSD95. Additionally, ([C8mim][PF6]) exposure resulted in hippocampal-specific inflammatory activation, indicated by increased levels of proinflammatory factors, elevated nuclear localisation of NF-κB, and activation of microglia and astrocytes. In conclusion, chronic exposure to low-dose ([C8mim][PF6]) induced neurotoxicity, including damage to glutamatergic excitatory synapses and inflammatory activation, which may illuminate the associated behavioural abnormalities. The results presented here may be helpful for the safe use of ILs in the future.

Can Ketogenic Diet Improve Alzheimer's Disease? Association With Anxiety, Depression, and Glutamate System

Background: Alzheimer's disease is the most common neurodegenerative disorder in our society, mainly characterized by loss of cognitive function. However, other symptoms such as anxiety and depression have been described in patients. The process is mediated by alterations in the synaptic and extrasynaptic activity of the neurotransmitter glutamate, which are linked to a hypometabolism of glucose as the main source of brain energy. In that respect, Ketogenic diet (KD) has been proposed as a non-pharmacological treatment serving as an alternative energy source to the neurons increasing the fat percentage and reducing the carbohydrates percentage, showing promising results to improve the cognitive symptoms associated with different neurodegenerative disorders, including AD. However, the association of this type of diet with emotional symptoms and the modulation of glutamate neurotransmission systems after this dietary reduction of carbohydrates are unknown.

Objective: The aim of this short review is to provide update studies and discuss about the relationship between KD, anxiety, depression, and glutamate activity in AD patients.

Discussion: The main results suggest that the KD is an alternative energy source for neurons in AD with positive consequences for the brain at different levels such as epigenetic, metabolic and signaling, and that the substitution of carbohydrates for fats is also associated with emotional symptoms and glutamate activity in AD.

Treadmill exercise sex-dependently alters susceptibility to depression-like behaviour, cytokines and BDNF in the hippocampus and prefrontal cortex of rats with sporadic Alzheimer-like disease

Alzheimer's disease (AD) is associated with increased depression-related behaviours. Previous studies have reported a greater risk of AD and depression in women. In recent years, we and others have provided evidence that exercise during life could be used as a therapeutic strategy for stress-related disorders such as depression. The main goal of the current study was to determine whether treadmill exercise during life can reduce depression-related behaviours in male and female Wistar rats with sporadic Alzheimer-like disease (ALD). Animals were subjected to treadmill exercise eight weeks before and four weeks after ALD induction by streptozocin (STZ). We measured body weight, food intake, and depression-related symptoms in rats using five behavioural tests. We measured brain-derived-neurotrophic factor (BDNF), tumour-necrosis factor (TNF)-α, and interleukin (IL)-10 levels in the hippocampus and prefrontal cortex of animals. Our findings showed that exercise but not ALD induction decreased body weight and food intake in male and female rats. ALD induction increased depression-related symptoms and hippocampal TNF-α in male and female rats. Besides, treadmill exercise alone decreased depression-related behaviours and increased hippocampal BDNF in females but not males. We also found that treadmill exercise decreased depression-related behaviours and TNF-α in the hippocampus and prefrontal cortex, and increased IL-10 in the prefrontal cortex and BDNF in the hippocampus of female ALD-induced rats. However, treadmill exercise only reduced anhedonia-like behaviour and hippocampal TNF-α in male ALD-induced rats. Overall, the evidence from this study suggests that treadmill exercise alters depression-related behaviours, brain BDNF and cytokines in a sex-dependant manner in rats with sporadic Alzheimer-like disease.

Ficus deltoidea: Potential inhibitor of pro-inflammatory mediators in lipopolysaccharide-induced activation of microglial cells

ETHNOPHARMACOLOGICAL RELEVANCE

Ficus deltoidea Jack (FD) is widely consumed in traditional medicine as a treatment for various diseases in Malaysia. Each part of the plant such as its leave, stem, fruit and root are used traditionally to treat different types of diseases. Vitexin and isovitexin are bioactive compounds abundantly found in the leaves of FD that possessed many pharmacological properties including neuroprotection. Nonetheless, its effects on key events in neuroinflammation are unknown.

AIM OF THE STUDY

To determine the inhibitory properties of FD aqueous extract on pro-inflammatory mediators involved in lipopolysaccharide (LPS)-induced microglial cells.

METHODS

Vitexin and isovitexin in the extract were quantified via high performance liquid chromatography (HPLC). The extract was evaluated for its cytotoxicity activity via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Pre-treatment with the extract on LPS-induced microglial cells was done to determine its antioxidant and anti-neuroinflammatory properties by measuring the level of reactive oxygen species (ROS), nitric oxide (NO), tumour necrosis factor alpha (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) via 2'-7'-dichlorofluorescin diacetate (DCFDA) assay, Griess assay and Western blot respectively.

RESULTS

The extract at all tested concentrations (0.1 μg/mL, 1 μg/mL, 10 μg/mL, 100 μg/mL) were not cytotoxic as the percentage viability of microglial cells were all above ~80%. At the highest concentration (100 μg/mL), the extract significantly reduced the formation of ROS, NO, TNF-α, IL-1β and IL-6 in microglial cells induced by LPS.

CONCLUSION

The extract showed neuroprotective effects by attenuating the levels of pro-inflammatory and cytotoxic factors in LPS-induced microglial cells, possibly by mediating the nuclear factor-kappa B (NF-κB) signalling pathway.

Swimming exercise decreases depression-like behaviour and inflammatory cytokines in a mouse model of type 2 diabetes

NEW FINDINGS

What is the central question of this study? Can swimming exercise decrease depression-like behaviour and inflammation in type 2 diabetic mice? What is the main finding and its importance? Swimming exercise decreased depression-like behaviour by reducing inflammation in type 2 diabetic mice. Swimming exercise might be useful for the treatment of depression-related disorders in patients with type 2 diabetes.

ABSTRACT

Clinical and experimental studies have shown that type 2 diabetes is associated with depression-related disorders. Inflammation has been identified as a common mechanism in both type 2 diabetes and depression. Several studies have suggested that swimming exercise might be able to reduce depression-related symptoms. The present study aimed to explore whether swimming exercise can decrease depression-like behaviour in type 2 diabetic mice. To induce type 2 diabetes, male C57BL6 mice were treated with a high-fat diet and streptozocin. Type 2 diabetic animals were subjected to swimming exercise for 4 weeks. Then, depression-like behaviours were evaluated by sucrose preference, novelty-suppressed feeding, social interaction and tail suspension tests. We also measured levels of glucose, insulin and pro-inflammatory cytokines such as interleukin-1β and tumour necrosis factor-α in the serum of animals. The results indicated that type 2 diabetes significantly increased anhedonia- and depression-like behaviours in mice. We also found significant increases in glucose, insulin and inflammatory cytokines in diabetic mice. Moreover, swimming exercise reduced anhedonia- and depression-like behaviour in type 2 diabetic mice. Swimming exercise also decreased glucose and inflammatory cytokines in the serum of mice with type 2 diabetes. Collectively, this study demonstrates that swimming exercise decreased depression-like behaviour by reducing inflammation in type 2 diabetic mice. Further clinical studies are needed to validate these findings in patients with type 2 diabetes.

Antibiotic-induced gut microbiota depletion from early adolescence exacerbates spatial but not recognition memory impairment in adult male C57BL/6 mice with Alzheimer-like disease

Gut microbiota dysbiosis is associated with cognitive dysfunctions and Alzheimer's disease (AD). This study set out to better understand the relationship between gut microbiota depletion and cognitive abilities in mice with or without Alzheimer-like disease. Male C57BL/6 mice from early adolescence received an antibiotic cocktail, and then in adulthood, animals were subjected to a stereotaxic surgery to induce Alzheimer-like disease using amyloid-beta (Aβ) 1-42 microinjection. To assess cognitive functions in mice, three behavioural tests including the Y maze, object recognition, and Morris water maze were used. We also measured brain-derived-neurotrophic factor (BDNF), tumour-necrosis factor (TNF)-α, interleukin (IL)-6, and Aβ42 in the brain. Our findings showed that antibiotics treatment impaired object recognition memory, whereas did not alter spatial memory in healthy mice. Antibiotics treatment in mice significantly exacerbated spatial memory impairment following the induction of AD in both the Y maze and Morris water maze test. There were significant correlations between these behavioural tests. In addition, healthy animals treated with antibiotics displayed a significant reduction in brain IL-6. We observed that antibiotics treatment significantly decreased both cytokines TNF-α and IL-6 in the brain of AD-induced mice. However, no alterations were found in brain BDNF levels following both antibiotics treatment and AD induction. These findings show that antibiotic-induced gut microbiota depletion from early adolescence to adulthood can impair cognitive abilities in mice with or without Alzheimer-like disease. Overall, this study suggests that gut microbiota manipulation from early adolescence to adulthood may adversely affect the normal development of cognitive functions.

Perinatal fluoxetine dose-dependently affects prenatal stress-induced neurobehavioural abnormalities, HPA-axis functioning and underlying brain alterations in rat dams and their offspring

Both untreated and SSRI antidepressant treated maternal depression during the perinatal period can pose both short-and long-term health risks to the offspring. Therefore, it is essential to have an effective SSRI treatment consisting of the lowest effective dose beneficial to the mother, without causing adverse effects on offspring development. The effects of prenatal stress on neurobehavioral outcomes were studied in the pregnant and lactating rat dam, and her offspring. Furthermore, stressed dams were treated with different doses of fluoxetine (FLX; 5, 10and 25 mg/kg) during pregnancy and the postpartum period. We found that prenatal stress-induced anxiety-and depressive-like behaviour and increased HPA-axis function in pregnant and postpartum dams, and in offspring. Maternal stress impaired object recognition but did not affect spatial memory in offspring. Prenatal stress decreased whole-brain serotonin and brain-derived-neurotrophic-factor, and increased interleukin-17 and malondialdehyde, but did not affect oxytocin and interleukin-6 in the brains of offspring. Maternal treatment with 5 mg/kg FLX during the perinatal period did not rescue any stress-induced anxiety/depressive-like behaviour in the pregnant and postpartum dam and had only a few rescuing effects in offspring. Maternal FLX treatment with 10 mg/kg did rescue most stress-induced anxiety-and depressive-like behaviour or HPA-axis-function in dams and offspring. The highest dose tested, 25 mg/kg FLX, had the rescuing properties in dams while having the same, or an even greater, detrimental effect as prenatal stress on offspring behaviour and molecular alterations in the brain. Our results show prenatal stress rescuing properties for FLX treatment in the pregnant and postpartum dam, with dose-dependent effects on the offspring.

Role of Haptoglobin as a Marker of Muscular Improvement in Patients with Multiple Sclerosis after Administration of Epigallocatechin Gallate and Increase of Beta-Hydroxybutyrate in the Blood: A Pilot Study

Here, we report on the role of haptoglobin (Hp), whose expression depends on the synthesis of interleukin 6 (IL-6), related to the pathogenesis of multiple sclerosis (MS), as a possible marker of muscle improvement achieved after treatment with the polyphenol epigallocatechin gallate (EGCG) and an increase in the ketone body beta-hydroxybutyrate (BHB) in the blood. After 4 months of intervention with 27 MS patients, we observed that Hp does not significantly increase, alongside a significant decrease in IL-6 and a significant increase in muscle percentage. At the same time, Hp synthesis is considerably and positively correlated with IL-6 both before and after treatment; while this correlation occurs significantly reversed with muscle percentage before treatment, no correlation is evident after the intervention. These results seem to indicate that Hp could be a marker of muscle status and could be a diagnosis tool after therapeutic intervention in MS patients.

The combination of fluoxetine and environmental enrichment reduces postpartum stress-related behaviors through the oxytocinergic system and HPA axis in mice

Gestational stress can increase postpartum depression in women. To treat maternal depression, fluoxetine (FLX) is most commonly prescribed. While FLX may be effective for the mother, at high doses it may have adverse effects on the fetus. As environmental enrichment (EE) can reduce maternal stress effects, we hypothesized that a subthreshold dose of FLX increases the impact of EE to reduce anxiety and depression-like behavior in postpartum dams exposed to gestational stress. We evaluated this hypothesis in mice and to assess underlying mechanisms we additionally measured hypothalamic-pituitary-adrenal (HPA) axis function and brain levels of the hormone oxytocin, which are thought to be implicated in postpartum depression. Gestational stress increased anxiety- and depression-like behavior in postpartum dams. This was accompanied by an increase in HPA axis function and a decrease in whole-brain oxytocin levels in dams. A combination of FLX and EE remediated the behavioral, HPA axis and oxytocin changes induced by gestational stress. Central administration of an oxytocin receptor antagonist prevented the remediating effect of FLX + EE, indicating that brain oxytocin contributes to the effect of FLX + EE. These findings suggest that oxytocin is causally involved in FLX + EE mediated remediation of postpartum stress-related behaviors, and HPA axis function in postpartum dams.

Roflumilast and tadalafil improve learning and memory deficits in intracerebroventricular Aβ1-42 rat model of Alzheimer's disease through modulations of hippocampal cAMP/cGMP/BDNF signaling pathway

BACKGROUND

Alzheimer's disease (AD) is the most prevalent age-dependent neurodegenerative disease characterized by progressive impairment of memory and cognitive functions. Cyclic nucleotides like cAMP and cGMP are well-known to play an important role in learning and memory functions. Enhancement of cAMP and cGMP levels in the hippocampus by phosphodiesterase (PDE) inhibitors might be a novel therapeutic approach for AD. Thus, the present study was planned to explore the therapeutic potential of roflumilast (RFM) and tadalafil (TDF) phosphodiesterase inhibitors in intracerebroventricular (ICV) Aβ1-42 induced AD in rats.

METHODS

ICV Aβ1-42 was administered in rats followed by treatment with RFM (0.05 mg/kg) and TDF (0.51 mg/kg) for 15 days. Novel object recognition (NOR), and Morris water maze (MWM) test were performed during the drug treatment schedule. On the day, 22 rats were sacrificed, and hippocampus was separated for biochemical, neuroinflammation, and histopathological analysis.

RESULTS

Aβ1-42 infused rats were induce behavioral impairment and increased AChE, BACE-1, Aβ1-42, GSK-3β, phosphorylated tau (p-Tau), pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) levels, oxidative stress (increased MDA, Nitrite and decreased GSH), histopathological changes, and reduced cAMP, cGMP, and BDNF levels. RFM and TDF significantly attenuated Aβ1-42 induced memory deficits and neuropathological alterations in the hippocampus.

CONCLUSION

The outcomes of the current study indicate that RFM and TDF lead to memory enhancement through upregulation of cAMP/cGMP/BDNF pathway, thus they may have a therapeutic potential in cognitive deficits associated with AD.

Neurobiological effects of forced swim exercise on the rodent hippocampus: a systematic review

Forced swimming is a common exercise method used for its low cost and easy management, as seen in studies with the hippocampus. Since it is applied for varied research purposes many protocols are available with diverse aspects of physical intensity, time and periodicity, which produces variable outcomes. In the present study, we performed a systematic review to stress the neurobiological effects of forced swim exercise on the rodent hippocampus. Behavior, antioxidant levels, neurotrophins and inflammatory markers were the main topics examined upon the swimming effects. Better results among these analyses were associated with forced exercise at moderate intensity with an adaptation period and the opposite for continuous exhausting exercises with no adaptation. On further consideration, a standard swimming protocol is necessary to reduce variability of results for each scenario investigated about the impact of the forced swimming on the hippocampus.

Forced swimming is a common exercise method used for its low cost and easy management, as seen in studies with the hippocampus. Since it is applied for varied research purposes many protocols are available with diverse aspects of physical intensity, time and periodicity, which produces variable outcomes. In the present study, we performed a systematic review to stress the neurobiological effects of forced swim exercise on the rodent hippocampus. Behavior, antioxidant levels, neurotrophins and inflammatory markers were the main topics examined upon the swimming effects. Better results among these analyses were associated with forced exercise at moderate intensity with an adaptation period and the opposite for continuous exhausting exercises with no adaptation. On further consideration, a standard swimming protocol is necessary to reduce variability of results for each scenario investigated about the impact of the forced swimming on the hippocampus.

The dialog between neurons and microglia in Alzheimer's disease: The neurotransmitters view

Microglia play a vital role in maintaining brain homeostasis. Their continuous sensing of surrounding micro-environments is crucial for their activity. Cross talk between specific neurons and microglia might occur through specific neurotransmitter receptors on microglia. Impairment with this interaction might result in pathological activity of microglia against potential insults. The reason for this activity in many neurodegenerative diseases such as Alzheimer's disease (AD) is not known. However, several papers report of the effects of different neurotransmitter agonists on microglial cells function that relate to their activity in AD. This review aims to summarize those works and to raise potential fundamental questions for future research.

Environmental enrichment alters neurobehavioral development following maternal immune activation in mice offspring with epilepsy

Epilepsy is a chronic brain disease affecting millions of people worldwide. Anxiety-related disorders and cognitive deficits are common in patients with epilepsy. Previous studies have shown that maternal infection/immune activation renders children more vulnerable to neurological disorders later in life. Environmental enrichment has been suggested to improve seizures, anxiety, and cognitive impairment in animal models. The present study aimed to explore the effects of environmental enrichment on seizure scores, anxiety-like behavior, and cognitive deficits following maternal immune activation in offspring with epilepsy. Pregnant mice were treated with lipopolysaccharides-(LPS) or vehicle, and offspring were housed in normal or enriched environments during early adolescence to adulthood. To induce epilepsy, adult male and female offspring were treated with Pentylenetetrazol-(PTZ), and then anxiety-like behavior and cognitive functions were assessed. Tumor-necrosis-factor (TNF)-α and interleukin (IL) 10 were measured in the hippocampus of offspring. Maternal immune activation sex-dependently increased seizure scores in PTZ-treated offspring. Significant increases in anxiety-like behavior, cognitive impairment, and hippocampal TNF-α and IL-10 were also found following maternal immune activation in PTZ-treated offspring. However, there was no sex difference in these behavioral abnormalities in offspring. Environmental enrichment reversed the effects of maternal immune activation on behavioral and inflammatory parameters in PTZ-treated offspring. Overall, the present findings highlight the adverse effects of prenatal maternal immune activation on seizure susceptibility and psychiatric comorbidities in offspring. This study suggests that environmental enrichment may be used as a potential treatment approach for behavioral abnormalities following maternal immune activation in PTZ-treated offspring.

Integrated phytochemical analysis based on UHPLC-LTQ-Orbitrap and network pharmacology approaches to explore the potential mechanism of Lycium ruthenicum Murr. for ameliorating Alzheimer's disease

Based on compelling experimental and clinical evidence, the fruit of Lycium ruthenicum Murr. (LRM), a unique traditional Tibetan medicine, exerts beneficial effects on ameliorating learning and memory deficits of Alzheimer's disease (AD) and other neurodegenerative disorders. However, the potential active constituents and biological mechanism of LRM are still unknown. In this study, the major chemical constituents of LRM were first analyzed by ultra-high-pressure liquid chromatography coupled with linear ion trap-Orbitrap tandem mass spectrometry (UHPLC-LTQ-Orbitrap). A total of 35 constituents were confirmed or tentatively identified. Furthermore, the network-based pharmacological strategy was applied to clarify the molecular mechanism of LRM on AD based on the identified components. Totally, 143 major targets were screened and supposed to be effective players in alleviating AD. Then, the LRM chemicals-major LRM putative targets-major pathways network was constructed, implying potential biological function of LRM on AD. More importantly, 12 core genes which can be modulated by LRM were identified, and they may play a pivotal role in alleviating some major symptoms of AD. This study provided a scientific basis for further investigation and application of LRM, which demonstrated that the network pharmacology approach could be a powerful way for the mechanistic studies of folk medicines.

Shenqi Xingnao Granules ameliorates cognitive impairments and Alzheimer’s disease-like pathologies in APP/PS1 mouse model

Objective

Alzheimer's disease (AD) is along with cognitive decline due to amyloid-β (Aβ) plaques, tau hyperphosphorylation, and neuron loss. Shenqi Xingnao Granules (SQXN), a traditional Chinese medicine, significantly ameliorated the cognitive function and daily living abilities of patients with AD. However, till date, no study has investigated the mechanism of action of SQXN on AD. The present study aimed to verify the effects of SQXN treatment on cognitive impairments and AD-like pathologies in APP/PS1 mice.

Methods

Four-month-old APP/PS1 transgenic (Tg) mice were randomly divided into a model group and SQXN-treated (3.5, 7, 14 g/kg per day) groups. Learning-memory abilities were determined by Morris water maze and object recognition test. All mice were sacrificed and the brain samples were collected after 75 d. The soluble Aβ contents were detected by Elisa kit; The levels of expression of NeuN, APP, phosphorylated tau and related protein were measured by Western blotting; The inflammation factors were detected by the proinflammatory panel kit.

Results

Four-month-old APP/PS1 mice were administered SQXN by oral gavage for 2.5 months. Using the Morris water maze tests and Novel object recognition, we found that SQXN restored behavioral deficits in the experimental group of Tg mice when compared with the controls. SQXN also inhibited neuronal loss (NeuN marker). SQXN treatment decreased soluble Aβ42 through inhibiting the expression of sAPPβ and BACE-1 without regulating full-length amyloid precursor protein (FL APP). Insulin degrading enzyme (IDE), the Aβ degrading enzyme, were increased by SQXN. In addition, SQXN reduced hyperphosphorylated tau protein levels and prevented excessive activation of p-GSK-3β in the brain of APP/PS1 mice. Compared with APP/PS1 transgenic negative mice, IFN-γ, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-12p70, KC/GRO and TNF-α were not obviously changed in the brain of 6.5-month-old APP/PS1 transgenic (Tg) mice. However, SQXN could inhibited the expression of IL-2.

Conclusion

These results demonstrate that SQXN ameliorates the cognitive impairments in APP/PS1 mice. The possible mechanisms involve its inhibition of neuronal loss, soluble Aβ deposition, tau hyperphosphorylation and inflammation.

Current Advances in Naturally Occurring Caffeoylquinic Acids: Structure, Bioactivity, and Synthesis

Caffeoylquinic acids (CQAs) are a broad class of secondary metabolites that have been found in edible and medicinal plants from various families. It has been 100 years since the discovery of chlorogenic acid in 1920. In recent years, a number of naturally derived CQAs have been isolated and structurally elucidated. Accumulated evidence demonstrate that CQAs have a wide range of biological activities, such as antioxidation, antibacterial, antiparasitic, neuroprotective, anti-inflammatory, anticancer, antiviral, and antidiabetic effects. Up to date, some meaningful progresses on the biosynthesis and total synthesis of CQAs have also been made. Therefore, it is necessary to comprehensively summarize the structure, biological activity, biosynthesis, and chemical synthesis of CQAs. This review provides extensive coverage of naturally occurring CQAs discovered from 1990 until 2020. Modern isolation techniques, chemical data (including structure, biosynthesis, and total synthesis), and bioactivity are summarized. This would be helpful for further research of CQAs as potential pharmaceutical agents.

Chemokine CCL2 impairs spatial memory and cognition in rats via influencing inflammation, glutamate metabolism and apoptosis-associated genes expression- a potential mechanism for HIV-associated neurocognitive disorder

AIMS

To explore the role of chemokine CC motif ligand 2 (CCL2) in spatial memory and cognition impairment, and the underlying mechanisms focused on inflammatory, glutamate metabolistic and apoptotic- associated mRNA expression.

MATERIALS AND METHODS

Stereotaxic surgery was performed here to establish a rat model by bilateral intra-hippocampal injection of CCL2. Morris water maze (MWM) and Novel object recognition test (NORT) were used to assess the learning, memory and cognitive ability respectively. RT-PCR was used to detect the relative mRNA expression of inflammatory, glutamate metabolistic and apoptotic- associated indexes. Nissl and TUNEL staining were performed to observe the morphological changes of hippocampal CA1 zone and quantified the apoptosis of hippocampal neurons of CA1 zones respectively.

KEY FINDINGS

We found CCL2 injured cognitive function in rats. Six days after CCL2 injection, we revealed the following obvious mRNA expression changes: (1) increasing of the neuroinflammatory cytokines IL-1β, CXCL-10, IL-6; (2) decreasing of the glutamate transporters GLT-1 and GLAST and increasing of PAG; (3) increasing of the apoptotic genes caspase-8, caspase-3 and Bax, while decreasing the anti-apoptotic gene Bcl-2. Further, Nissl staining and TUNEL confirmed the injury of the structure of hippocampal CA1 zones and the apoptosis of hippocampal neurons.

SIGNIFICANCE

Our results indicated that CCL2 impaired spatial memory and cognition, the involving mechanisms may link to the up-regulation of mRNA expression of the three major pathological events: inflammation, excitotoxicity and neuronal apoptosis, which were involved in HIV-associated neurocognitive disorder (HAND). Taken together, these findings suggest a potential therapeutic strategy against CCL2.

Inhibition of NF-κB might enhance the protective role of roflupram on SH-SY5Y cells under amyloid β stimulation via PI3K/AKT/mTOR signaling pathway

Alzheimer disease (AD) is a progressive neurodegenerative disease and mostly endanger the health of people older than 65 years. Accumulation of beta amyloid protein (Aβ) is the main characteristic of AD. Roflupram (ROF) could improve the behavior of AD in a mouse model. In this study, we first detected the increased concentration of molecules related to inflammatory response in serum sample of patients with AD. Next, a cell model of nuclear factor kappa B (NF-κB) inhibition and NF-κB overexpression was established in SH-SY5Y cells, Aβ was used to simulate the toxicity to cells. ROF treatment decreased expression of apoptosis-related molecules via inhibition of PI3K/AKT/mTOR signaling pathway, decreased expression of pro-inflammatory factors, and increased expression of key enzymes in the tricarboxylic acid (TCA) cycle was observed in SH-SY5Y cells after ROF treatment. Inhibition of NF-κB could enlarge these trends whereas overexpression of NF-κB could reduce these trends.

Prenatal maternal stress alters depression-related symptoms in a strain - and sex-dependent manner in rodent offspring

Stress during pregnancy adversely affects foetal development and leads to later behavioural outcomes in offspring. Preclinical studies have reported conflicting effects of prenatal stress on depression-related symptoms in rodent offspring. This study aimed to study the combined effect of strain and sex on prenatal stress outcomes in a single study. To this end, male and female offspring from outbred Wistar and inbred Lewis rats, and outbred NMRI and inbred C57BL6 mice were compared. As outcomes we focussed on depression-related behaviour and related molecular and neurochemical parameters. Prenatally stressed and non-stressed offspring were subjected to the sucrose preference, novelty-suppressed feeding, tail suspension, and forced swim tests. We measured basal and stress-induced corticosterone levels in the serum, and brain-derived-neurotrophic-factor (BDNF), interleukin-1β, tumor necrosis factor-α, glutamate and serotonin in the brain to determine changes in hypothalamic-pituitary-adrenal-(HPA)-axis function, neuroplasticity, neuroinflammation, and neurotransmission. Our findings revealed that prenatal stress increases depression-like behaviour, HPA-axis (re) activity, pro-inflammatory cytokines and glutamate levels, and decreases BDNF and serotonin levels in a strain and sex-dependent manner in rodent offspring. Overall, male and female Lewis rats, female Wistar rats, male NMRI mice and female C57BL6 mice were found to be most responsive to prenatal stress. Based on these results, we conclude that genetic background and sex contribute to the great diversity in the effects of prenatal maternal stress in rodents.

Ischemia-Triggered Glutamate Excitotoxicity From the Perspective of Glial Cells

A plethora of neurological disorders shares a final common deadly pathway known as excitotoxicity. Among these disorders, ischemic injury is a prominent cause of death and disability worldwide. Brain ischemia stems from cardiac arrest or stroke, both responsible for insufficient blood supply to the brain parenchyma. Glucose and oxygen deficiency disrupts oxidative phosphorylation, which results in energy depletion and ionic imbalance, followed by cell membrane depolarization, calcium (Ca²⁺) overload, and extracellular accumulation of excitatory amino acid glutamate. If tight physiological regulation fails to clear the surplus of this neurotransmitter, subsequent prolonged activation of glutamate receptors forms a vicious circle between elevated concentrations of intracellular Ca²⁺ ions and aberrant glutamate release, aggravating the effect of this ischemic pathway. The activation of downstream Ca²⁺-dependent enzymes has a catastrophic impact on nervous tissue leading to cell death, accompanied by the formation of free radicals, edema, and inflammation. After decades of “neuron-centric” approaches, recent research has also finally shed some light on the role of glial cells in neurological diseases. It is becoming more and more evident that neurons and glia depend on each other. Neuronal cells, astrocytes, microglia, NG2 glia, and oligodendrocytes all have their roles in what is known as glutamate excitotoxicity. However, who is the main contributor to the ischemic pathway, and who is the unsuspecting victim? In this review article, we summarize the so-far-revealed roles of cells in the central nervous system, with particular attention to glial cells in ischemia-induced glutamate excitotoxicity, its origins, and consequences.

The Impact of Coconut Oil and Epigallocatechin Gallate on the Levels of IL-6, Anxiety and Disability in Multiple Sclerosis Patients

Background: Due to the inflammatory nature of multiple sclerosis (MS), interleukin 6 (IL-6) is high in blood levels, and it also increases the levels of anxiety related to functional disability. Epigallocatechin gallate (EGCG) decreases IL-6, which could be enhanced by the anti-inflammatory effect of high ketone bodies after administering coconut oil (both of which are an anxiolytic). Therefore, the aim of this study was to assess the impact of coconut oil and EGCG on the levels of IL-6, anxiety and functional disability in patients with MS. Methods: A pilot study was conducted for four months with 51 MS patients who were randomly divided into an intervention group and a control group. The intervention group received 800 mg of EGCG and 60 mL of coconut oil, and the control group was prescribed a placebo. Both groups followed the same isocaloric Mediterranean diet. State and trait anxiety were determined before and after the study by means of the State-Trait Anxiety Inventory (STAI). In addition, IL-6 in serum was measured using the ELISA technique and functional capacity was determined with the Expanded Disability Status Scale (EDSS) and the body mass index (BMI). Results: State anxiety and functional capacity decreased in the intervention group and IL-6 decreased in both groups. Conclusions: EGCG and coconut oil improve state anxiety and functional capacity. In addition, a decrease in IL-6 is observed in patients with MS, possibly due to the antioxidant capacity of the Mediterranean diet and its impact on improving BMI.

4,5 caffeoylquinic acid and scutellarin, identified by integrated metabolomics and proteomics approach as the active ingredients of Dengzhan Shengmai, act against chronic cerebral hypoperfusion by regulating glutamatergic and GABAergic synapses

Dengzhan Shengmai (DZSM) is a proprietary Chinese medicine for remarkable curative effect as a treatment of cerebrovascular diseases, such as chronic cerebral hypoperfusion (CCH) and dementia based on evidence-based medicine, which have been widely used in the recovery period of ischemic cerebrovascular diseases. The purpose of this study was to investigate the active substances and mechanism of DZSM against CCH. Integrative metabolomic and proteomic studies were performed to investigate the neuroprotective effect of DZSM based on CCH model rats. The exposed components of DZSM in target brain tissue were analysed by a high-sensitivity HPLC-MS/MS method, and the exposed components were tested on a glutamate-induced neuronal excitatory damage cell model for the verification of active ingredients and mechanism of DZSM. Upon proteomic and metabolomic analysis, we observed a significant response in DZSM therapy from the interconnected neurotransmitter transport pathways including glutamatergic and GABAergic synapses. Additionally, DZSM had a significant regulatory effect on glutamate and GABA-related proteins including vGluT1 and vIAAT, suggested that DZSM could be involved in the vesicle transport of excitatory and inhibitory neurotransmitters in the pre-synaptic membrane. DZSM could also regulated the metabolism of arachidonic acid (AA), phospholipids, lysophospholipids and the expression of phospholipase A2 in post-synaptic membrane. The results of glutamate-induced neuronal excitatory injury cell model experiment for verification of active ingredients and mechanism of DZSM showed that there are five active ingredients, and among them, 4,5 caffeoylquinic acid (4,5-CQA) and scutellarin (SG) could simultaneously affect the GABAergic and glutamatergic synaptic metabolism as well as the related receptors, the NR2b subunit of NMDA and the α1 subunit of GABA_A. The active ingredients of DZSM could regulate the over-expression of the NMDA receptor, enhance the expression of the GABA_A receptor, resist glutamate-induced neuronal excitatory damage, and finally maintain the balance of excitatory and inhibitory synaptic metabolism dominated by glutamate and GABA. Furtherly, we compared the efficacy of DZSM, 4,5-CQA, SG and the synergistic effect of 4,5-CQA and SG, and the results showed that all the groups significantly improved cell viability compared with the model group (p < 0.001). The western blot results showed that DZSM, 4,5-CQA, SG and 4,5-CQA/SG co-administration groups could significantly regulate the expression of receptors (GABA_A α1 and NR2b subunit of NMDA) and synaptic-related proteins, such as Sv2a, Syp, Slc17a7, bin1 and Prkca, respectively. These results proved DZSM and its active ingredients (4,5-CQA and SG) had the effect of regulating glutamatergic and GABAergic synapses. Finally, membrane potential FLIPR assay of 4,5-CQA and SG was used for GABRA1 activity test, and it was found that the two compounds could increase GABA-induced activation of GABRA1 receptor (GABA 10 μM) in a dose-dependent manner with EC₅₀ value of 48.74 μM and 29.77 μM, respectively. Manual patch clamp method was used to record NMDA NR1/NR2B subtype currents, and scutellarin could cause around 10 % blockade at 10 μM (p＜0.05 compared with the control group). These studies provided definitive clues of the mechanism for the neuroprotective effect of DZSM for CCH treatment and the active compounds regulating glutamatergic and GABAergic synapses. Additionally, 4,5-CQA and SG might be potential drugs for the treatment of neurodegenerative disease related to CCH.

Intracerebral Injection of Streptozotocin to Model Alzheimer Disease in Rats

Animal models have promoted meaningful contribution to science including Alzheimer's disease (AD) research. Several animal models for AD have been used, most of them related to genetic mutations observed in familial AD. However, sporadic form of AD, also named late-onset is the most frequent form of the disease, which is multifactorial, being influenced by genetic, environmental and lifestyle factors. Here, we describe a protocol of an AD-like pathology of the sporadic form using Wistar rats by a single bilateral intracerebroventricular (icv) injection of streptozotocin (STZ, 2 mg/kg). Icv injection of STZ induces brain resistance to insulin and other pathological alterations related to those observed in AD, such as cognitive impairment and accumulation of phosphorylated tau protein and β-amyloid in the brain. Thus, icv injection of STZ is a useful tool to investigate the pathological mechanisms and the metabolic alterations involved in AD and to propose new therapeutic approaches and neuroprotective drugs.

Moderate protective effect of Kyotorphin against the late consequences of intracerebroventricular streptozotocin model of Alzheimer's disease

The established decrease in the level of endogenous kyotorphin (KTP) into the cerebrospinal fluid of patients with an advanced stage of Alzheimer's disease (AD) and the found neuroprotective activity of KTP suggested its participation in the pathophysiology of the disease. We aimed to study the effects of subchronic intracerebroventricular (ICV) treatment (14 days) with KTP on the behavioral, biochemical and histological changes in rats with streptozotocin (STZ-ICV)-induced model of sporadic AD (sAD). Three months after the administration of STZ-ICV, rats developed increased locomotor activity, decreased level of anxiety, impaired spatial and working memory. Histological data from the STZ-ICV group demonstrated decreased number of neurons in the CA1 and CA3 subfields of the hippocampus. The STZ-ICV group was characterized with a decrease of total protein content in the hippocampus and the prefrontal cortex as well as increased levels of the carbonylated proteins in the hippocampus. KTP treatment of STZ-ICV rats normalized anxiety level and regained object recognition memory. KTP abolished the protein loss in prefrontal cortex and decrease the neuronal loss in the CA3 subfield of the hippocampus. STZ-ICV rats, treated with KTP, did not show significant changes in the levels of the carbonylated proteins in specific brain structures or in motor activity and spatial memory compared to the saline-treated STZ-ICV group. Our data show a moderate and selective protective effect of a subchronic ICV administration of the dipeptide KTP on the pathological changes induced by an experimental model of sAD in rats.