Apelin-13 Suppresses Neuroinflammation Against Cognitive Deficit in a Streptozotocin-Induced Rat Model of Alzheimer's Disease Through Activation of BDNF-TrkB Signaling Pathway

Apelin alleviated neuroinflammation and promoted endogenous neural stem cell proliferation and differentiation after spinal cord injury in rats

Background

Spinal cord injury (SCI) causes devastating neurological damage, including secondary injuries dominated by neuroinflammation. The role of Apelin, an endogenous ligand that binds the G protein-coupled receptor angiotensin-like receptor 1, in SCI remains unclear. Thus, our aim was to investigate the effects of Apelin in inflammatory responses and activation of endogenous neural stem cells (NSCs) after SCI.

Methods

Apelin expression was detected in normal and injured rats, and roles of Apelin in primary NSCs were examined. In addition, we used induced pluripotent stem cells (iPSCs) as a carrier to prolong the effective duration of Apelin and evaluate its effects in a rat model of SCI.

Results

Co-immunofluorescence staining suggested that Apelin was expressed in both astrocytes, neurons and microglia. Following SCI, Apelin expression decreased from 1 to 14 d and re-upregulated at 28 d. In vitro, Apelin promoted NSCs proliferation and differentiation into neurons. In vivo, lentiviral-transfected iPSCs were used as a carrier to prolong the effective duration of Apelin. Transplantation of transfected iPSCs in situ immediately after SCI reduced polarization of M1 microglia and A1 astrocytes, facilitated recovery of motor function, and promoted the proliferation and differentiation of endogenous NSCs in rats.

Conclusion

Apelin alleviated neuroinflammation and promoted the proliferation and differentiation of endogenous NSCs after SCI, suggesting that it might be a promising target for treatment of SCI.

[Inhibition connexin 43 by mimetic peptide Gap27 mediates protective effects on 6-hydroxydopamine induced Parkinson's disease mouse model]

OBJECTIVE

To explore whether the using of mimetic peptide Gap27, a selective inhibitor of connexin 43 (Cx43), could block the death of dopamine neurons and influence the expression of Cx43 in 6-hydroxydopamine (6-OHDA)-induced Parkinson's disease mouse models.

METHODS

Eighteen C57BL/6 mice were randomly divided into control group, 6-OHDA group and 6-OHDA+Gap27 group, with 6 mice in each group. Bilateral substantia nigra stereotactic injection was performed. The control group was injected with ascorbate solution, 6-OHDA group was injected with 6-OHDA solution, and 6-OHDA+Gap27 group was injected with 6-OHDA and Gap27 mixed solution. Immuno-histochemical staining was used to detect the number of dopamine neurons, quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of Cx43 messenger ribonucleic acid (mRNA), immuno-fluorescence staining was used to detect the distribution of Cx43 protein, the contents of Cx43 protein and Cx43 phosphorylation at serine 368 (Cx43-ps368) in mouse midbrain were detected by Western blot.

RESULTS

After injection of 6-OHDA, numerous dopamine neurons in substantia nigra died as Cx43 content increased, Cx43-ps368 content decreased. Mixing Gap27 while injecting 6-OHDA could reduce the number of death dopamine neurons and weaken the changes of Cx43 and Cx43-ps368 content caused by 6-OHDA. The number of tyrosine hydroxylase (TH) immunoreactive positive neurons in 6-OHDA group decreased to 27.7% ± 0.02% of the control group (P < 0.01); The number of TH immunoreactive positive neurons in 6-OHDA+Gap27 group was (1.64±0.16) times higher than that in 6-OHDA group (P < 0.05); The content of total Cx43 protein in 6-OHDA group was (1.44±0.07) times higher than that in 6-OHDA+Gap27 group (P < 0.05) while (1.68±0.07) times higher than that in control group (P < 0.01). In 6-OHDA group, the content of Cx43-ps368 protein and its proportion in total Cx43 protein were significantly lower than that in 6-OHDA+Gap27 group (P < 0.05).

CONCLUSION

In 6-OHDA mouse models, mimetic peptide Gap27 played a protective role in reducing the damage to substantia nigra dopamine neurons, which was induced by 6-OHDA. The overexpression of Cx43 protein might have neurotoxicity to dopamine neuron. Meanwhile, decreasing Cx43 protein level and keeping Cx43-ps368 protein level may be the protective mechanisms of Gap27.

Circulating brain-derived neurotrophic factor dysregulation and its linkage with lipid level, stenosis degree, and inflammatory cytokines in coronary heart disease

Background

Brain‐derived neurotrophic factor (BDNF) regulates the lipid metabolism, atherosclerosis plaque formation, and inflammatory process, while the study about its clinical role in coronary heart disease (CHD) is few. The present study intended to explore the expression of BDNF and its relationship with stenosis, inflammation, and adhesion molecules in CHD patients.

Methods

After serum samples were obtained from 207 CHD patients, BDNF, tumor necrosis factor‐alpha (TNF‐α), interleukin (IL)‐1β, IL‐6, IL‐8, IL‐17A, vascular cell adhesion molecule‐1 (VCAM‐1), and intercellular adhesion molecule‐1 (ICAM‐1) levels were determined using ELISA. Then, the BDNF level was also examined in 40 disease controls (DCs) and 40 healthy controls (HCs), separately.

Results

BDNF was lower in CHD patients than in DCs and HCs (median (95% confidential interval) value: 5.6 (3.5–9.6) ng/mL vs. 10.7 (6.1–17.0) ng/mL and 12.6 (9.4–18.2) ng/mL, both p < 0.001). BDNF could well distinguish CHD patients from DCs (area under the curve [AUC]: 0.739) and HCs (AUC: 0.857). BDNF was negatively associated with triglyceride (p = 0.014), total cholesterol (p = 0.037), and low‐density lipoprotein cholesterol (p = 0.008). BDNF was negatively associated with CRP (p < 0.001), TNF‐α (p < 0.001), IL‐1β (p = 0.008), and IL‐8 (p < 0.001). BDNF was negatively related to VCAM‐1 (p < 0.001) and ICAM‐1 (p = 0.003). BDNF was negatively linked with the Gensini score (p < 0.001).

Conclusion

BDNF reflects the lipid dysregulation, inflammatory status, and stenosis degree in CHD patients.

Activation of TGR5 Ameliorates Streptozotocin-Induced Cognitive Impairment by Modulating Apoptosis, Neurogenesis, and Neuronal Firing

Takeda G protein-coupled receptor 5 (TGR5) is the first known G protein-coupled receptor specific for bile acids and is recognized as a new and critical target for type 2 diabetes and metabolic syndrome. It is expressed in many brain regions associated with memory such as the hippocampus and frontal cortex. Here, we hypothesize that activation of TGR5 may ameliorate streptozotocin- (STZ-) induced cognitive impairment. The mouse model of cognitive impairment was established by a single intracerebroventricular (ICV) injection of STZ (3.0 mg/kg), and we found that TGR5 activation by its agonist INT-777 (1.5 or 3.0 μg/mouse, ICV injection) ameliorated spatial memory impairment in the Morris water maze and Y-maze tests. Importantly, INT-777 reversed STZ-induced downregulation of TGR5 and glucose usage deficits. Our results further showed that INT-777 suppressed neuronal apoptosis and improved neurogenesis which were involved in tau phosphorylation and CREB-BDNF signaling. Moreover, INT-777 increased action potential firing of excitatory pyramidal neurons in the hippocampal CA3 and medial prefrontal cortex of ICV-STZ groups. Taken together, these findings reveal that activation of TGR5 has a neuroprotective effect against STZ-induced cognitive impairment by modulating apoptosis, neurogenesis, and neuronal firing in the brain and TGR5 might be a novel and potential target for Alzheimer's disease.

Stereotaxic-assisted gene therapy in Alzheimer's and Parkinson's diseases: therapeutic potentials and clinical frontiers

INTRODUCTION

Alzheimer's disease (AD) and Parkinson's disease (PD) are neurodegenerative disorders causing cognitive deficits and motor difficulties in the elderly. Conventional treatments are mainly symptomatic with little ability to halt disease progression. Gene therapies to correct or silence genetic mutations predisposing to AD or PD are currently being developed in preclinical studies and clinical trials, relying mostly on systemic delivery, which reduces their effectiveness. Imaging-guided stereotaxic procedures are used to locally deliver therapeutic cargos to well-defined brain sites, hence raising the question whether stereotaxic-assisted gene therapy has therapeutic potentials.

AREAS COVERED

The authors summarize the studies that investigated the use of gene therapy in PD and AD in animal and clinical studies over the past five years, with a special emphasis on the combinatorial potential with stereotaxic delivery. The advantages, limitations and futuristic challenges of this technique are discussed.

EXPERT OPINION

Robotic stereotaxis combined with intraoperative imaging has revolutionized brain surgeries. While gene therapies are bringing huge innovations to the medical field and new hope to AD and PD patients and medical professionals, the efficient and targeted delivery of such therapies is a bottleneck. We propose that careful application of stereotaxic delivery of gene therapies can improve PD and AD management. [Figure: see text].

Role of Cholinergic Signaling in Alzheimer's Disease

Acetylcholine, a neurotransmitter secreted by cholinergic neurons, is involved in signal transduction related to memory and learning ability. Alzheimer’s disease (AD), a progressive and commonly diagnosed neurodegenerative disease, is characterized by memory and cognitive decline and behavioral disorders. The pathogenesis of AD is complex and remains unclear, being affected by various factors. The cholinergic hypothesis is the earliest theory about the pathogenesis of AD. Cholinergic atrophy and cognitive decline are accelerated in age-related neurodegenerative diseases such as AD. In addition, abnormal central cholinergic changes can also induce abnormal phosphorylation of ttau protein, nerve cell inflammation, cell apoptosis, and other pathological phenomena, but the exact mechanism of action is still unclear. Due to the complex and unclear pathogenesis, effective methods to prevent and treat AD are unavailable, and research to explore novel therapeutic drugs is various and active in the world. This review summaries the role of cholinergic signaling and the correlation between the cholinergic signaling pathway with other risk factors in AD and provides the latest research about the efficient therapeutic drugs and treatment of AD.

Apelin-13 protects against memory impairment and neuronal loss, Induced by Scopolamine in male rats

The present study aimed to evaluate the effects of Apelin-13 on scopolamine-induced memory impairment in rats. Forty male rats were divided into five groups of eight. The control group received no intervention; the scopolamine group underwent stereotaxic surgery and received 3 mg/kg intraperitoneal scopolamine. The treatment groups additionally received 1.25, 2.5 and 5 µg apelin-13 in right lateral ventricles for 7 days. All rats (except the control group) were tested for the passive avoidance reaction, 24 h after the last drug injection. For histological analysis, hippocampal sections were stained with cresyl violet; synaptogenesis biochemical markers were determined by immunoblotting. Apelin-13 alleviated scopolamine-induced passive avoidance memory impairment and neuronal loss in the rats' hippocampus (P<0.001). The reduction observed in mean concentrations of hippocampal synaptic proteins (including neurexin1, neuroligin, and postsynaptic density protein 95) in scopolamine-treated animals was attenuated by apelin-13 treatment. The results demonstrated that apelin-13 can protect against passive avoidance memory deficiency, and neuronal loss, induced by scopolamine in male rats. Further experimental and clinical studies are required to confirm its therapeutic potential in neurodegenerative diseases.

Research Progress on Mechanism of Neuroprotective Roles of Apelin-13 in Prevention and Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is the most common type of dementia. Currently, more than 50 million people live with dementia worldwide, and this number is expected to increase. Some of the typical pathological changes of AD include amyloid plaque, hyperphosphorylation of tau protein, secretion of inflammatory mediators, and neuronal apoptosis. Apelin is a neuroprotective peptide that is widely expressed in the body. Among members of apelin family, apelin-13 is the most abundant with a high neuroprotective function. Apelin-13/angiotensin domain type 1 receptor-associated proteins (APJ) system regulates several physiological and pathophysiological cell activities, such as apoptosis, autophagy, synaptic plasticity, and neuroinflammation. It has also been shown to prevent AD development. This article reviews the research progress on the relationship between apelin-13 and AD to provide new ideas for prevention and treatment of AD.

Repetitive Transcranial Magnetic Stimulation Improves Brain-Derived Neurotrophic Factor and Cholinergic Signaling in the 3xTgAD Mouse Model of Alzheimer’s Disease

Background:

Alzheimer’s disease (AD) is a debilitating disorder involving the loss of plasticity and cholinergic neurons in the cortex. Pharmaceutical treatments are limited in their efficacy, but brain stimulation is emerging as a treatment for diseases of cognition. More research is needed to determine the biochemical mechanisms and treatment efficacy of this technique.

Objective:

We aimed to determine if forebrain repetitive transcranial magnetic stimulation can improve cortical BDNF gene expression and cholinergic signaling in the 3xTgAD mouse model of AD.

Methods:

Both B6 wild type mice and 3xTgAD mice aged 12 months were given daily treatment sessions for 14 days or twice weekly for 6 weeks. Following treatment, brain tissue was extracted for immunological stains for plaque load, as well as biochemical analysis for BDNF gene expression and cholinergic signaling via acetylcholinesterase and choline acetyltransferase ELISA assays.

Results:

For the 3xTgAD mice, both 14 days and 6 weeks treatment regimens resulted in an increase in BDNF gene expression relative to sham treatment, with a larger increase in the 6-week group. Acetylcholinesterase activity also increased for both treatments in 3xTgAD mice. The B6 mice only had an increase in BDNF gene expression for the 6-week group.

Conclusion:

Brain stimulation is a possible non-invasive and nonpharmaceutical treatment option for AD as it improves both plasticity markers and cholinergic signaling in an AD mouse model.

Magnolol attenuates the locomotor impairment, cognitive deficit, and neuroinflammation in Alzheimer's disease mice with brain insulin resistance via up-regulating miR-200c

In this study, we aimed to investigate the effect of Magnolol on Alzheimer's disease (AD). After the model of streptozotocin-induced AD mice with brain insulin resistance was established, the mice were treated with Magnolol or miR-200c antagomiR. The abilities of ambulations, rearings, discrimination, spatial learning, and memory were evaluated by open-field test (OFT), novel object recognition (NOR), and morris water maze (MWM) tests. The levels of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), and miR-200c in the mice hippocampus were evaluated by enzyme-linked immunosorbent assay, Western blot, or Quantitative real-time Polymerase Chain Reaction. In AD mice model, streptozotocin induced the locomotor impairment and cognitive deficit, up-regulated levels of MDA, TNF-α, IL-6, and CRP, while down-regulated levels of GSH, SOD, and miR-200c. Magnolol increased the rearings numbers and discrimination index of AD mice in OFT and NOR tests. Magnolol increased the number of entries in the target quadrant and time spent in the target quadrant and decreased the escape latency of AD mice in the MWM test. Magnolol also down-regulated the levels of MDA, TNF-α, IL-6, and CRP, and up-regulated the levels of GSH, SOD, and miR-200c in the hippocampus tissues of AD mice. However, miR-200c antagomiR did the opposite and further offset the effects of the Magnolol on AD mice. Magnolol attenuated the locomotor impairment, cognitive deficit, and neuroinflammatory in AD mice with brain insulin resistance via up-regulating miR-200c.

Transcranial photobiomodulation therapy ameliorates perioperative neurocognitive disorder through modulation of mitochondrial function in aged mice

Perioperative neurocognitive disorder (PND) is a serious nervous system complication characterized by progressive cognitive impairment, especially in geriatric population. However, the neuropathogenesis of PND is complex, and there are no approved disease-modifying therapeutic options. Mitochondrial dysfunction has been demonstrated to contribute to the occurrence and development of PND. Transcranial near-infrared (tNIR) light treatment helps to improve mitochondrial dysfunction and enhance cognition, but its effect on PND remains unclear. Here, we evaluated the effect of tNIR light treatment on PND caused by anesthesia and surgery in aged mice. We built the PND models with 18-month C57BL/6 male mice by exploratory laparotomy under isoflurane inhalation anesthesia, and treated by tNIR light with wavelength 810 nm for 2 weeks. The short-term and long-term changes in cognitive function were analyzed by behavioral tests. We further explored the effects of tNIR light on mitochondria, synapses, neurons, and signaling pathways through different experimental methods. The results demonstrated that the cognitive impairment and mitochondrial dysfunction in PND mice were ameliorated after tNIR light treatment. Further experiments demonstrated that photobiomodulation therapy (PBMT) increased synapse-related protein expression, neuronal survival, and protected synapse from depletion. Moreover, downregulated sirtuin 1 (SIRT1) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) were increased after tNIR light treatment. Our results suggested that tNIR light was an effective treatment of PND through PBMT effect, accompanied by synaptic and neuronal improvement. The improvement of mitochondrial dysfunction mediated by SIRT1/PGC-1α signaling pathway might participate in this process. Those findings might provide a novel and noninvasive therapeutic target for PND.

Identifying disease-critical cell types and cellular processes across the human body by integration of single-cell profiles and human genetics

Genome-wide association studies (GWAS) provide a powerful means to identify loci and genes contributing to disease, but in many cases the related cell types/states through which genes confer disease risk remain unknown. Deciphering such relationships is important for identifying pathogenic processes and developing therapeutics. Here, we introduce sc-linker, a framework for integrating single-cell RNA-seq (scRNA-seq), epigenomic maps and GWAS summary statistics to infer the underlying cell types and processes by which genetic variants influence disease. We analyzed 1.6 million scRNA-seq profiles from 209 individuals spanning 11 tissue types and 6 disease conditions, and constructed gene programs capturing cell types, disease progression, and cellular processes both within and across cell types. We evaluated these gene programs for disease enrichment by transforming them to SNP annotations with tissue-specific epigenomic maps and computing enrichment scores across 60 diseases and complex traits (average N= 297K). Cell type, disease progression, and cellular process programs captured distinct heritability signals even within the same cell type, as we show in multiple complex diseases that affect the brain (Alzheimer’s disease, multiple sclerosis), colon (ulcerative colitis) and lung (asthma, idiopathic pulmonary fibrosis, severe COVID-19). The inferred disease enrichments recapitulated known biology and highlighted novel cell-disease relationships, including GABAergic neurons in major depressive disorder (MDD), a disease progression M cell program in ulcerative colitis, and a disease-specific complement cascade process in multiple sclerosis. In autoimmune disease, both healthy and disease progression immune cell type programs were associated, whereas for epithelial cells, disease progression programs were most prominent, perhaps suggesting a role in disease progression over initiation. Our framework provides a powerful approach for identifying the cell types and cellular processes by which genetic variants influence disease.

All roads lead to Rome - a review of the potential mechanisms by which exerkines exhibit neuroprotective effects in Alzheimer's disease

Age-related neurodegenerative disorders such as Alzheimer’s disease (AD) have become a critical public health issue due to the significantly extended human lifespan, leading to considerable economic and social burdens. Traditional therapies for AD such as medicine and surgery remain ineffective, impractical, and expensive. Many studies have shown that a variety of bioactive substances released by physical exercise (called “exerkines”) help to maintain and improve the normal functions of the brain in terms of cognition, emotion, and psychomotor coordination. Increasing evidence suggests that exerkines may exert beneficial effects in AD as well. This review summarizes the neuroprotective effects of exerkines in AD, focusing on the underlying molecular mechanism and the dynamic expression of exerkines after physical exercise. The findings described in this review will help direct research into novel targets for the treatment of AD and develop customized exercise therapy for individuals of different ages, genders, and health conditions.

Adipokines as Immune Cell Modulators in Multiple Sclerosis

Multiple sclerosis (MS), a chronic inflammatory and demyelinating disease of the central nervous system (CNS), is a major clinical and societal problem, which has a tremendous impact on the life of patients and their proxies. Current immunomodulatory and anti-inflammatory therapies prove to be relatively effective; however, they fail to concomitantly stop ongoing neurological deterioration and do not reverse acquired disability. The proportion to which genetic and environmental factors contribute to the etiology of MS is still incompletely understood; however, a recent association between MS etiology and obesity was shown, with obesity greatly increasing the risk of developing MS. An altered balance of adipokines, which are white adipose tissue (WAT) hormones, plays an important role in the low-grade chronic inflammation during obesity by their pervasive modification of local and systemic inflammation. Vice versa, inflammatory factors secreted by immune cells affect adipokine function. To explore the role of adipokines in MS pathology, we will here review the reciprocal effects of adipokines and immune cells and summarize alterations in adipokine levels in MS patient cohorts. Finally, we will discuss proof-of-concept studies demonstrating the therapeutic potential of adipokines to target both neuroinflammation and neurodegeneration processes in MS.

Regulatory role of Apelin-13-mediated PI3K/AKT signaling pathway in the glucose and lipid metabolism of mouse with gestational diabetes mellitus

OBJECTIVE

To investigate the regulatory mechanism of Apelin-13-mediated PI3K/AKT signaling pathway in the glucose and lipid metabolism of gestational diabetes mellitus (GDM) mouse.

METHODS

GDM mice models were established and treated with Apelin-13 and/or PI3K/AKT inhibitor LY294002. Then, the indicators of glucose and lipid metabolism and the levels of inflammatory factors were detected. Besides, the levels of indicators of oxidative stress in the placenta of mice were measured. Western blotting was also carried out to determine the expression of PI3K/AKT pathway-related proteins in all groups.

RESULTS

In comparison with the Control group, mice in the GDM group presented with the continuous increase in the level of FBG as the time went on, while FINS level decreased evidently. Besides, the fetus alive ratio in the GDM group was much lower with significant increased weight of fetal mouse and weight of placenta; the mice had significant decreased levels of IL-6, IL-1β, TNF-α and MCP-1, and in the placenta, the levels of SOD, GPx, GSH and CAT were also reduced evidently, with significant downregulation of p-PI3K/PI3K and p-AKT/AKT. However, indicators above in the GDM mice treated with Apelin-13 had significant improvement as compared to those in the GDM group, and the improvement was reversed by LY294002 treatment.

CONCLUSION

Apelin-13, possibly by activating the PI3K/AKT pathway, could improve the glucose and lipid metabolism, reduce the damage caused by oxidative stress and inflammatory reaction, and protect the pancreas islet, thereby improving the pregnancy outcome of GDM mice.

Apelin receptor homodimer inhibits apoptosis in vascular dementia

Apelin receptor (APJ), a member of family A of the G protein-coupled receptors (GPCRs), is a potential pharmaceutical target for diseases of the nervous system. Our previous work revealed that human APJ can form a homodimer that has different functional characteristics than the monomer. To investigate the effects of APJ homodimers on neuroprotection in vascular dementia (VD), we established VD model in rats and treated the animals by injecting apelin-13 into the lateral ventricle. In addition, we established an oxygen-glucose deprivation/reoxygenation (OGD/R) model in SH-SY5Y cells treated with apelin-13. After apelin-13 stimulation in the VD rat, the level of APJ and APJ homodimer were elevated. Furthermore, APJ homodimer decreased the level of cleaved caspase-3 and cleaved caspase-9 via the Gα_i3 and Gα_q signaling pathway, thereby increasing the number of neurons and inhibiting apoptosis. Consequently, APJ homodimers may serve as a unique mechanism for neuroprotection against VD and provide new pharmaceutical targets for VD.

Acceleration of Biological Aging and Underestimation of Subjective Age Are Risk Factors for Severe COVID-19

In an epidemic, it is important to have methods for reliable and rapid assessment of risk groups for severe forms of the disease for their priority vaccination and for the application of preventive lockdown measures. The aim of this study was to investigate risk factors for severe forms of COVID-19 in adults using indicators of biological and subjective aging. Longitudinal studies evaluated the severity of the disease and the number of cases. Respondents (447) were divided into "working group" and "risk group" (retirees with chronic diseases). During the lockdown period (in mid-2020), accelerated aging was observed in the group of workers (by 3.9-8 years for men and an increase at the tendency level for women). However, the respondents began to feel subjectively younger (by 3.3-7.2 years). In the risk group, there were no deviations from the expected biopsychological aging. The number of cases at the end of 2020 was 31% in workers and 0% in the risk group. Reasonably, the risk group followed the quarantine rules more strictly by 1.5 times. In working men, indicators of relative biological and relative subjective aging (measured in both 2019 and mid-2020) significantly influenced the incidence at the end of 2020. In women, only the indicators obtained in mid-2020 had a significant impact. The relative biological aging of an individual tested in the middle of 2020 had a direct impact on the risk of infection (p < 0.05) and on the probability of death (p < 0.0001). On the contrary, an increase in the relative subjective (psychological) aging index reduced the risk of infection (at the tendency level, p = 0.06) and the risk of death (p < 0.0001). Both the risk of infection and the risk of death increased with calendar age at the tendency level. Conclusions: Indicators of individual relative biological and subjective aging affect the probability of getting COVID-19 and its severity. The combination of high indicators of biological aging and underestimated indicators of subjective aging is associated with increased chances of developing severe forms of the disease.

Molecular pathways underlying tissue injuries in the bladder with ketamine cystitis

Ketamine cystitis (KC) is a chronic bladder inflammation leading to urinary urgency, frequency, and pain. The pathogenesis of KC is complicated and involves multiple tissue injuries in the bladder. Recent studies indicated that urothelium disruption, lamina propria fibrosis and inflammation, microvascular injury, neuropathological alterations, and bladder smooth muscle (BSM) abnormalities all contribute to the pathogenesis of KC. Ketamine has been shown to induce these tissue injuries by regulating different signaling pathways. Ketamine can stimulate antiproliferative factor, adenosine triphosphate, and oxidative stress to disrupt urothelium. Lamina propria fibrosis and inflammation are associated with the activation of cyclooxygenase-2, nitric oxide synthase, immunoglobulin E, and transforming growth factor β1. Ketamine contributes to microvascular injury via the N-methyl-D aspartic receptor (NMDAR), and multiple inflammatory and angiogenic factors such as tumor necrosis factor α and vascular endothelial growth factor. For BSM abnormalities, ketamine can depress the protein kinase B, extracellular signal-regulated kinase, Cav1.2, and muscarinic receptor signaling. Elevated purinergic signaling also plays a role in BSM abnormalities. In addition, ketamine affects neuropathological alterations in the bladder by regulating NMDAR- and brain-derived neurotrophic factor-dependent signaling. Inflammatory cells also contribute to neuropathological changes via the secretion of chemical mediators. Clarifying the role and function of these signaling underlying tissue injuries in the bladder with KC can contribute to a better understanding of the pathophysiology of this disease and to the design of effective treatments for KC.

Impact of the apelin/APJ axis in the pathogenesis of Parkinson's disease with therapeutic potential

The pathogenesis of Parkinson's disease (PD) remains elusive. There is still no available disease-modifying strategy against PD, whose management is mainly symptomatic. A growing amount of preclinical evidence shows that a complex interplay between autophagy dysregulation, mitochondrial impairment, endoplasmic reticulum stress, oxidative stress, and excessive neuroinflammation underlies PD pathogenesis. Identifying key molecules linking these pathological cellular processes may substantially aid in our deeper understanding of PD pathophysiology and the development of novel effective therapeutic approaches. Emerging preclinical evidence indicates that apelin, an endogenous neuropeptide acting as a ligand of the orphan G protein-coupled receptor APJ, may play a key neuroprotective role in PD pathogenesis, via inhibition of apoptosis and dopaminergic neuronal loss, autophagy enhancement, antioxidant effects, endoplasmic reticulum stress suppression, as well as prevention of synaptic dysregulation in the striatum, excessive neuroinflammation, and glutamate-induced excitotoxicity. Underlying signaling pathways involve phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin, extracellular signal-regulated kinase 1/2, and inositol requiring kinase 1α/XBP1/C/EBP homologous protein. Herein, we discuss the role of apelin/APJ axis and associated molecular mechanisms on the pathogenesis of PD in vitro and in vivo and provide evidence for its challenging therapeutic potential.

MOGONET integrates multi-omics data using graph convolutional networks allowing patient classification and biomarker identification

To fully utilize the advances in omics technologies and achieve a more comprehensive understanding of human diseases, novel computational methods are required for integrative analysis of multiple types of omics data. Here, we present a novel multi-omics integrative method named Multi-Omics Graph cOnvolutional NETworks (MOGONET) for biomedical classification. MOGONET jointly explores omics-specific learning and cross-omics correlation learning for effective multi-omics data classification. We demonstrate that MOGONET outperforms other state-of-the-art supervised multi-omics integrative analysis approaches from different biomedical classification applications using mRNA expression data, DNA methylation data, and microRNA expression data. Furthermore, MOGONET can identify important biomarkers from different omics data types related to the investigated biomedical problems.

Apelin-13 attenuates spatial memory impairment by anti-oxidative, anti-apoptosis, and anti-inflammatory mechanism against ethanol neurotoxicity in the neonatal rat hippocampus

It has been shown that alcohol consumption by pregnant women can have detrimental effects on the developing fetus and lead to fetal alcohol spectrum disorders (FASD). Exposure to alcohol in rat pups during this period causes long-term changes in the structure of the animal's hippocampus, leading to impaired hippocampal-related brain functions such as navigation tasks and spatial memory. Apelin-13, a principal neuropeptide with inhibitory effects on neuroinflammation and brain oxidative stress production, has beneficial properties on memory impairment and neuronal injury. The protective effects of apelin-13 have been evaluated on ethanol-related neurotoxicity in the hippocampus of rat pups. Rat pups from 2 until 10 postnatal day, similar to the third trimester of pregnancy in humans, were intubated total daily dose of ethanol (5/27 g/kg/day). Immediately after intubation, 25 and 50 μg/ kg of apelin-13 was injected subcutaneously. By using Morris water maze task, the hippocampus- dependent memory and spatial learning were evaluated 36 days after birth. Then, Immunohistochemical staining was done to determine the levels of GFAP and caspase-3. ELISA assay was also performed to measure both TNF-α and antioxidant enzymes levels. The current study demonstrates that administration of apelin-13 attenuates spatial memory impairment significantly (P < 0.001). After ethanol neurotoxicity, apelin-13 could also increase the catalase level (P < 0.001), activity of total superoxide dismutase as well as glutathione concentration noticeably (P < 0.05). Other impacts of it could be mentioned as attenuating TNF-α production and also preventing lipid peroxidation (P < 0.001). In addition, the results showed that the level of GFAP as a neuroinflammation factor and the number of active caspase-3 positive cells can be decreased by apelin-13 (P < 0.01). Regarding the protective effects of apelin-13 against ethanol-induced neurotoxicity, it is a promising therapeutic choice for FASD; but more studies are needed.

Sex-Independent Cognition Improvement in Response to Kaempferol in the Model of Sporadic Alzheimer's Disease

Alzheimer's disease (AD) is associated with neural oxidative stress and inflammation, and it is assumed to affect more women than men with unknown mechanisms. Kaempferol (KMP) as a potent natural antioxidant has been known to exhibit various biological and pharmacological functions, including antioxidant and anti-inflammatory. We aimed here to evaluate the role of gender difference in response to KMP on the rat model of sporadic AD. Forty-six female and male Wistar rats were divided into six groups of sham, streptozotocin (STZ) + saline (SAL), STZ + KMP. Female rats were ovariectomized, and then all animals received an intracerebroventricular bilateral injection of STZ (3 mg/kg) to induce the AD model. KMP (10 mg/kg) was intraperitoneally administered for 21 consecutive days. Afterward, spatial learning and memory were assessed via the Morris water maze task (MWM). Finally, the hippocampus level of superoxide dismutase (SOD), glutathione, and malondialdehyde were measured using calorimetric kits. Data showed a significant cognition deficit in STZ + SAL compared with the sham. To sum up, we reported that chronic KMP treatment increase significantly improved acquisition and retrieval of spatial memory as evident by longer TTS (total time spent) and short-latency to the platform in MWM. In addition, KMP increased the levels of SOD and glutathione in the hippocampus of rats. Also, KMP decreased hippocampal levels of malondialdehyde in both genders. In conclusion, KMP successfully restores spatial memory impairment independent of gender difference. This memory restoration may at least in part be mediated through boosting the hippocampal level of SOD and glutathione.

Neuroprotective gain of Apelin/APJ system

Apelin is an endogenous ligand of G protein-coupled receptor APJ. In recent years, many studies have shown that the apelin/APJ system has neuroprotective properties, such as anti-inflammatory, anti-oxidative stress, anti-apoptosis, and regulating autophagy, blocking excitatory toxicity. Apelin/APJ system has been proven to play a role in various neurological diseases and may be a promising therapeutic target for nervous system diseases. In this paper, the neuroprotective properties of the apelin/APJ system and its role in neurologic disorders are reviewed. Further understanding of the pathophysiological effect and mechanism of the apelin/APJ system in the nervous system will help develop new therapeutic interventions for various neurological diseases.

Physical Exercise-Induced Myokines in Neurodegenerative Diseases

Neurodegenerative diseases (NDs), such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS), are disorders characterized by progressive degeneration of the nervous system. Currently, there is no disease-modifying treatments for most NDs. Meanwhile, numerous studies conducted on human and animal models over the past decades have showed that exercises had beneficial effects on NDs. Inter-tissue communication by myokine, a peptide produced and secreted by skeletal muscles during exercise, is thought to be an important underlying mechanism for the advantages. Here, we reviewed studies about the effects of myokines regulated by exercise on NDs and their mechanisms. Myokines could exert beneficial effects on NDs through a variety of regulatory mechanisms, including cell survival, neurogenesis, neuroinflammation, proteostasis, oxidative stress, and protein modification. Studies on exercise-induced myokines are expected to provide a novel strategy for treating NDs, for which there are no adequate treatments nowadays. To date, only a few myokines have been investigated for their effects on NDs and studies on mechanisms involved in them are in their infancy. Therefore, future studies are needed to discover more myokines and test their effects on NDs.

R13 preserves motor performance in SOD1G93A mice by improving mitochondrial function

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by death of motor neurons in the brain and spinal cord. However, so far, there is no effective treatment for ALS.

Methods: In this study, R13, a prodrug of 7,8-dihydroxyflavone, selectively activating tyrosine kinase receptor B (TrkB) signaling pathway, was administered prophylactically to 40-day old SOD1^G93A mice for 90 days. The motor performance was investigated by rotarod test, climbing-pole test, grip strength test and hanging endurance test. Afterwards, the spinal cord and medulla oblongata of 130-day old mice were harvested, and the proteomics revealed the effect of R13 on mouse protein expression profile. Astrocytes and microglial proliferation were assessed by immunohistochemical analysis. The number of motor neurons in the spinal cord is determined by Nissl staining. The effect of R13 on gastrocnemius morphology was assessed by HE staining. The effect of R13 on the survival rate was accomplished with worms stably expressing G93A SOD1.

Results: Behavioral tests showed that R13 significantly attenuated abnormal motor performance of SOD1^G93A mice. R13 reduced the advance of spinal motor neuron pathology and gastrocnemius muscle atrophy. The proliferation of microglia and astrocytes was reduced by R13 treatment. Mitochondriomics analysis revealed that R13 modified the mitochondrial protein expression profiles in the medulla oblongata and spinal cord of SOD1^G93A mice, particularly promoting the expression of proteins related to oxidative phosphorylation (OXPHOS). Further study found that R13 activated AMPK/PGC-1α/Nrf1/Tfam, promoted mitochondrial biogenesis and ameliorated mitochondrial dysfunction. Lastly, R13 prolonged the survival rate of worms stably expressing G93A SOD1.

Conclusions: These findings suggest oral R13 treatment slowed the advance of motor system disease in a reliable animal model of ALS, supporting that R13 might be useful for treating ALS.

N-acetylserotonin alleviated the expression of interleukin-1β in retinal ischemia-reperfusion rats via the TLR4/NF-κB/NLRP3 pathway

This study aimed to explore the effects of N-acetylserotonin (NAS) on the expression of interleukin-1β (IL-1β) in the retina of retinal ischemia-reperfusion injury (RIRI) rats via the toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB)/nod-like receptor pyrin domain containing 3 (NLRP3) signaling pathway. In this study, adult male Sprague Dawley rats were randomly divided into the sham, RIRI, RIRI + NAS and RIRI + TAK-242 + NAS groups. The rats in the RIRI + NAS and RIRI + TAK-242 + NAS groups were intraperitoneally injected with NAS 30 min before and after modeling. TAK-242, a selective TLR4 inhibitor, was administered by intraperitoneal injection in RIRI + TAK-242 + NAS group. The RIRI rat model was established by elevating the intraocular pressure to 110 mmHg for 60 min. The retinal structure and edema were assessed by H&E staining. The expression levels of TLR4, phosphorylated NF-κB (p-NF-κB), NLRP3, cleaved Caspase-1, and IL-1β in the retina of each group were detected using immunohistochemistry and Western blot. The correlations of the differences of TLR4⁺ and cleaved Caspase-1⁺ with IL-1β⁺ cells (between the NAS and the RIRI groups) were analyzed, using linear regression in the RIRI + NAS group. Results showed that thinner retina, more RGCs, and less TLR4⁺, p-NF-κB⁺, NLRP3⁺, cleaved Caspase-1⁺, and IL-1β⁺ cells in the retina were observed in the RIRI + NAS and RIRI + TAK-242 + NAS groups compared with the RIRI group 12 h after RIRI (all P < 0.01). Western blot analysis results showed that the expression of IL-1β in the RIRI + NAS group began to increase 6 h after RIRI, and it reached a high level 12 h after RIRI, and then decreased. And it was lower at each time point in the RIRI + NAS group than in the RIRI group, and there existed significant difference (all P < 0.01). Besides, the expression levels of TLR4, p-NF-κB, NLRP3, and cleaved Caspase-1 proteins in the RIRI + NAS and RIRI + TAK-242 + NAS groups decreased 12 h after RIRI compared with those in the RIRI group (all P < 0.01). The difference in IL-1β⁺ cells was significantly correlated with those of TLR4⁺ and cleaved Caspase-1⁺ cells in the RIRI + NAS group (r² = 0.9054 or 0.7431, P < 0.01). In conclusion, NAS could attenuate the expression of IL-1β by inhibiting the TLR4/NF-κB/NLRP3 signaling pathway, reduce the retina edema, and promote the survival of RGCs, thereby alleviating the retinal injury and exert its neuroprotective effect.

Apelin-13 activates the hippocampal BDNF/TrkB signaling pathway and suppresses neuroinflammation in male rats with cisplatin-induced cognitive dysfunction

It has been established that cisplatin causes neuronal damage and cognitive impairment. However, the mechanism is not sufficiently clear. Apelin-13 is an endogenous peptide with strong neuroprotective effects through the synthesis of neurotrophic factors and suppression of inflammation. The aim of this study was to investigate the role of brain-derived neurotrophic factor/tropomyosin receptor kinase B (BDNF/TrkB) signaling pathway and the potential inhibitory effects of apelin-13 in the mechanism of cisplatin-induced hippocampal damage and cognitive impairment. Apelin-13 was administered to adult sprague dawley male rats at a dose of 20 nmol/kg every day for 4 weeks, cisplatin was administered at a dose of 5 mg/kg once a week for 4 weeks. The spatial and recognition memory tests of the rats were performed on the 5th week. BDNF and the inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) levels were measured by ELISA in hippocampal homogenates. Pyramidal neuron and glial cell damage in the hippocampal CA1, CA3 and dentate gyrus (DG) were analyzed histologically. TrkB activity in the hippocampus was determined by immunohistochemical methods. Cisplatin impaired spatial and recognition memory in rats, while apelin-13 improved spatial memory but did not affect recognition memory. Cisplatin suppressed BDNF in the hippocampus while increased IL-1β and TNF-α. In contrast, apelin-13 administration increased BDNF but significantly suppressed TNF-α and IL-1B. Cisplatin caused pyramidal neuron and glial cell damage in CA1, CA3 and DG. In the cisplatin + apelin-13 group, however, pyramidal neuron and glial cell damage was less than those without apelin-13. Cisplatin increased TrkB activity in the hippocampus, which was counteracted by apelin-13. In conclusion, apelin-13 reduced the cisplatin-induced cognitive deficiency, by suppressing inflammation and stimulating the synthesis and activation of neurotrophic factors in hippocampal tissue.

Protriptyline improves spatial memory and reduces oxidative damage by regulating NFκB-BDNF/CREB signaling axis in streptozotocin-induced rat model of Alzheimer's disease

Antidepressants are well known to exert their role via upregulation of brain derived neurotrophic factor (BDNF). BDNF has been reported to exerts its neuroprotective effect in rodent and primate models as well as in patients of Alzheimer's disease (AD). The aim of our study was to evaluate the effect of protriptyline (PRT), a tricyclic antidepressant, in streptozotocin (STZ)- induced rat model of AD. Total 10 µl of STZ was injected into each ventricle (1 mg/kg). PRT (10 mg/kg, i.p.) treatment was started 3-day post STZ administration and continued till 21 days. We found that STZ treatment significantly increased pTau, Aβ42 and BACE-1 expression, oxidative stress and neurodegeneration in hippocampus and cortex of adult rats. STZ induced impairment in spatial learning and retention memory was associated with increased NFκB and reduced CREB and BDNF expression in cortex and hippocampus. Interestingly, PRT treatment significantly reduced pTau, Aβ42 and BACE-1 levels, neurodegeneration, oxidative stress and glial activation, contributing to the improved spatial learning and retention memory in STZ treated rats. Moreover, PRT treatment significantly improved p-ERK/ERK ratio and enhanced BDNF and CREB levels by reducing NFκB and GFAP expression in STZ treated rats. Our data suggest that impaired NFκB and CREB signaling potentially contribute in AD pathogenesis by elevating oxidative stress and neuroinflammation mediated neurodegeneration. Our study has established protriptyline as a multi target molecule in pre-clinical model of AD and further investigations on PRT like molecules could pave way for further development of effective new treatments in neurodegenerative disorders.

The beneficial role of the synthetic microneurotrophin BNN20 in a focal demyelination model

BNN20, a C17-spiroepoxy derivative of the neurosteroid dehydroepiandrosterone, has been shown to exhibit strong neuroprotective properties but its role in glial populations has not been assessed. Our aim was to investigate the effect of BNN20 on glial populations by using in vitro and in vivo approaches, taking advantage of the well-established lysophosphatidylcholine (LPC)-induced focal demyelination mouse model. Our in vivo studies, performed in male mice, showed that BNN20 treatment leads to an increased number of mature oligodendrocytes (OLs) in this model. It diminishes astrocytic accumulation during the demyelination phase leading to a faster remyelination process, while it does not affect oligodendrocyte precursor cell recruitment or microglia/macrophage accumulation. Additionally, our in vitro studies showed that BNN20 acts directly to OLs and enhances their maturation even after they were treated with LPC. This beneficial effect of BNN20 is mediated, primarily, through the neurotrophin receptor TrkA. In addition, BNN20 reduces microglial activation and their transition to their pro-inflammatory state upon lipopolysaccharides stimulation in vitro. Taken together our results suggest that BNN20 could serve as an important molecule to develop blood-brain barrier-permeable synthetic agonists of neurotrophin receptors that could reduce inflammation, protect and increase the number of functional OLs by promoting their differentiation/maturation.

Shenzao jiannao oral liquid, an herbal formula, ameliorates cognitive impairments by rescuing neuronal death and triggering endogenous neurogenesis in AD-like mice induced by a combination of Aβ42 and scopolamine

ETHNOPHARMACOLOGICAL RELEVANCE

According to the theory of traditional Chinese medicine (TCM), Alzheimer's disease (AD) is identified as "forgetfulness" or "dementia", and is mainly caused by "kidney essence deficiency" which ultimately induces "encephala reduction". Therefore, herbal formulas possessing the efficacy of nourishing kidney essence or replenishing brain marrow are commonly served as effective strategies for AD treatment. Shenzao jiannao oral liquid (SZJN), a traditional Chinese preparation approved by the China Food and Drug Administration (CFDA), is used for the treatment of insomnia and mind fatigue at present for its efficacy of nourishing kidneys. In present study, we found that SZJN could improve cognitive function of AD-like mice.

AIMS OF STUDY

This study aims to investigate the effects of SJZN on ameliorating cognitive deficits of AD-like mouse model, and to illuminate the underlying mechanisms from the perspective of neuroprotection and neurogenesis.

MATERIALS AND METHODS

Kunming mice (28 ± 2 g) were randomly allocated into seven groups: control, sham, model, donepezil and SZJN groups (low, middle and high). The AD mouse model was established by Aβ42 combined with scopolamine. SZJN were intragastrically administrated at doses of 0.3, 1.5 and 7.5 g/kg for 28 days. Morris water maze (MWM) test was applied to determine the cognitive function. Hematoxylin eosin (HE) and Nissl staining were carried out to evaluate pathological damages in the cortex and hippocampal tissues. To explore the protective effects of SZJN on multiple pathogenic factors of AD, protein levels of Aβ42, glial fibrillary acidic protein (GFAP), Bax, Bcl-2, Caspase-3, synaptophysin (SYP), brain-derived neurotrophic factor (BDNF), and neurogenesis related proteins were assessed using Immunofluorescence (IF) and western blot analysis. In vitro, the AD cell model was established by transduction of APP_695swe genes into Neural stem cells (NSCs) isolated from the hippocampal tissues of neonatal C57BL/6 mice. Cell viability assay and neurosphere formation assay were carried out to verify the efficacy of SZJN on proliferation of NSCs.

RESULTS

Our results demonstrated that SZJN (1.5 g/kg and 7.5 g/kg) treatment significantly ameliorated cognitive deficits of AD-like mice. SZJN (7.5 g/kg) treatment significantly retarded the pathological damages including neuronal degeneration, neuronal apoptosis, Aβ peptides aggregation and reaction of astrocytes in AD-like mice. In addition, SZJN (7.5 g/kg) increased the expression of BDNF and SYP, and restored the abnormal level of MDA and SOD in the brain of AD-like mice. Furthermore, SZJN treatment for 28 days remarkably increased the proliferation of NSCs evidenced by more Nestin⁺ and BrdU⁺ cells in the hippocampal DG regions, and increased the amount of mature neurons marked by NeuN both in the cortex and hippocampal DG regions. In vitro, SZJN treatement (16, 32, 64 mg/ml) promoted the proliferation of NSCs evidenced by the increased amount and enlarged size of the neurospheres (p < 0.05).

CONCLUSIONS

Our findings indicated that SZJN could ameliorate cognitive deficits by protecting neurons from death and triggering endogenous neurogenesis. Therefore, SZJN may be considered as a promising agent to restore neuronal loss and deter the deterioration in AD patients.

Intravenous Administration of Pyroglutamyl Apelin-13 Alleviates Murine Inflammatory Pain via the Kappa Opioid Receptor

Apelin is an endogenous neuropeptide, which has wide distribution in central nervous system and peripheral tissues. Pyroglutamyl apelin-13 [(pyr)apelin-13] is the major apelin isoform in human plasma. However, the role of peripheral (pyr)apelin-13 in pain regulation is unknown. The aim of this study was to investigate the effect of the peripheral injection of (pyr)apelin-13 on inflammatory pain using the formalin test as well as to evaluate the mechanistic basis for the effect. Results showed intravenous (i.v.) injection of (pyr)apelin-13 (10, 20 mg/kg) to significantly decrease licking/biting time during the second phase of the mouse formalin test. In contrast, i.v. injection of apelin-13 had no influence on such effect. Intramuscular injection of (pyr)apelin-13 reduced licking/biting time during the second phase only at a dose of 20 mg/kg. The antinociception of i.v. (pyr)apelin-13 was antagonized by the apelin receptor (APJ, angiotensin II receptor-like 1) antagonist, apelin-13(F13A). (pyr)apelin-13 (i.v. 20 mg/kg) markedly upregulated Aplnr and Adcy2 gene expression in the prefrontal cortex, whereas Fos gene expression was downregulated. The antinociception of i.v. (pyr)apelin-13 was blocked by the opioid receptor antagonist naloxone and the specific kappa opioid receptor (KOR) antagonist nor-binaltorphimine (nor-BNI). (pyr)Apelin-13 upregulated the dynorphin and KOR gene expression and protein levels in the mouse prefrontal cortex, not in striatum. (pyr)Apelin-13 did not influence the motor behavior. Our results demonstrate that i.v. injection of (pyr)apelin-13 induces antinociception via the KOR in the inflammatory pain mouse model.

Light Emitting Diode Therapy Protects against Myocardial Ischemia/Reperfusion Injury through Mitigating Neuroinflammation

Background

Neuroinflammation plays a key role in myocardial ischemia-reperfusion (I/R) injury. Previous studies showed that light-emitting diode (LED) therapy might improve M2 microglia activation and brain-derived neurotrophic factor (BDNF) expression, thereby exerting anti-inflammatory effects. Therefore, we hypothesized that LED therapy might reduce myocardial I/R injury by neuroinflammation modulation.

Objective

To explore the effect of LED therapy on myocardial I/R-induced injury and seek the underlying mechanism.

Methods

Thirty rats were randomly divided into three groups: Control group (without LED treatment or myocardial I/R, n = 6), I/R group (with myocardial I/R only, n = 12), and LED+I/R group (with myocardial I/R and LED therapy, n = 12). Electrocardiogram was recorded continuously during the procedure. In addition, brain tissue was extracted for BDNF, Iba1, and CD206 analyses, and heart tissue for myocardial injury (ischemic size and infarct size), IL-4 and IL-10 mRNA analysis.

Results

In comparison with the I/R group, the ischemia size and the infarct size were significantly attenuated by LED therapy in the LED+I/R group. Meanwhile, the microglia activation induced by I/R injury was prominently attenuated by LED treatment either. And it is apparent that there was also an increase in the beneficial neuroinflammation markers (BDNF and CD206) in the paraventricular nucleus (PVN) in the LED+I/R group. Furthermore, the anti-inflammatory cytokines, IL-4 and IL-10, were greatly decreased by I/R while improved by LED treatment in myocardium.

Conclusion

LED therapy might reduce neuroinflammation in PVN and decrease myocardium injury by elevating BDNF and M2 microglia.

Tau-Mediated Dysregulation of Neuroplasticity and Glial Plasticity

The inability of individual neurons to compensate for aging-related damage leads to a gradual loss of functional plasticity in the brain accompanied by progressive impairment in learning and memory. Whereas this loss in neuroplasticity is gradual during normal aging, in neurodegenerative diseases such as Alzheimer’s disease (AD), this loss is accelerated dramatically, leading to the incapacitation of patients within a decade of onset of cognitive symptoms. The mechanisms that underlie this accelerated loss of neuroplasticity in AD are still not completely understood. While the progressively increasing proteinopathy burden, such as amyloid β (Aβ) plaques and tau tangles, definitely contribute directly to a neuron’s functional demise, the role of non-neuronal cells in controlling neuroplasticity is slowly being recognized as another major factor. These non-neuronal cells include astrocytes, microglia, and oligodendrocytes, which through regulating brain homeostasis, structural stability, and trophic support, play a key role in maintaining normal functioning and resilience of the neuronal network. It is believed that chronic signaling from these cells affects the homeostatic network of neuronal and non-neuronal cells to an extent to destabilize this harmonious milieu in neurodegenerative diseases like AD. Here, we will examine the experimental evidence regarding the direct and indirect pathways through which astrocytes and microglia can alter brain plasticity in AD, specifically as they relate to the development and progression of tauopathy. In this review article, we describe the concepts of neuroplasticity and glial plasticity in healthy aging, delineate possible mechanisms underlying tau-induced plasticity dysfunction, and discuss current clinical trials as well as future disease-modifying approaches.

Apelin attenuates streptozotocin-induced learning and memory impairment by modulating necroptosis signaling pathway

Apelin is a neuropeptide that plays an important role in neuronal protection. In this study, we investigated the effects of apelin intracerebroventricular administration on spatial learning and memory-related behaviors, and necroptosis signaling pathways in the hippocampus of streptozotocin (STZ) -injected rats. Apelin treatment was implemented following STZ-induced dementia for 15 days. After conducting a behavioral test (Morris Water Maze), the cellular and molecular aspects were examined to detect the apelin effect on the necroptosis signaling pathway. We demonstrated that STZ administration significantly slowed down the learning capability. However apelin treatment notably reversed this neuroinflammation induced behavioral impairment. Furthermore, molecular investigations showed that apelin treatment reduced the hippocampal RIP1, RIP3, and TNF-α level. Our results suggest that apelin treatment attenuates STZ-induced dementia. This effect may be mediated by inhibition of the necroptosis signaling pathway which seems to be associated with the ability of apelin to reduce central TNF-α level. This data provides evidence of the neuroprotective effect of apelin on STZ-induced learning and memory impairment and characterize some of the underlying mechanisms.

Yizhi Qingxin Formula Extract Ameliorates Cognitive Decline in Aged Rats via the Brain-Derived Neurotrophic Factor/Tropomyosin Receptor Kinase B Pathway

Cognitive impairment and decline in old age are primarily driven by the accumulation of age-related neuropathologies, and old age is thus the primary risk factor for neurodegenerative diseases such as AD. Here, we investigated the effects of Yizhi Qingxin formula (YQF) extract on cognitive impairment in aged rats and determine the role of the brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB) pathway underlying the neuroprotective effects of the YQF extract. Fifty male Wistar rats were randomly divided into five groups: Control group, Model group, Donepezil group, and YQF extract groups (treatment with YQF extract at two different doses). After treatment with YQF extract for 8 weeks, learning and cognitive abilities were assessed using the Morris water maze. Morphological changes in the hippocampus were observed using hematoxylin-eosin. Activated microglia and astrocytes were assessed using immunohistochemistry. Expressions of proteins and genes were examined using western blotting and real-time PCR. The results revealed that oral treatment with YQF extract dramatically improved spatial learning and memory ability and ameliorated histopathological and morphological characteristics in aged rats. YQF extract significantly increased acetylcholine and interleukin (IL)-10 levels but markedly decreased amyloid-β peptide, tumor necrosis factor alpha (TNFα), IL-2, and IL-6 levels. In addition, it inhibited the excessive activation of microglia and astrocytes, downregulated the expressions of TNFα and IL-2, and upregulated nerve growth factor, BDNF, and TrkB expressions. Furthermore, hippocampal extracellular signal-related kinase (Erk) and protein kinase B (Akt), the upstream signaling of BDNF/TrkB, were also activated by treatment with YQF extract. Our findings indicate that YQF extract activates the BDNF/TrkB pathway through the upregulation of Erk and Akt signaling, and the activated signaling pathway might contribute to the protective effects of YQF extract on cognitive impairment in aged rats.

BDNF promotes activation of astrocytes and microglia contributing to neuroinflammation and mechanical allodynia in cyclophosphamide-induced cystitis

BACKGROUND

Patients with interstitial cystitis/bladder pain syndrome (IC/BPS) often grieve over a low quality of life brought about by chronic pain. In our previous studies, we determined that neuroinflammation of the spinal dorsal horn (SDH) was associated with mechanisms of interstitial cystitis. Moreover, it has been shown that brain-derived neurotrophic factor (BDNF) participates in the regulation of neuroinflammation and pathological pain through BDNF-TrkB signaling; however, whether it plays a role in cyclophosphamide (CYP)-induced cystitis remains unclear. This study aimed to confirm whether BDNF-TrkB signaling modulates neuroinflammation and mechanical allodynia in CYP-induced cystitis and determine how it occurs.

METHODS

Systemic intraperitoneal injection of CYP was performed to establish a rat cystitis model. BDNF-TrkB signaling was modulated by intraperitoneal injection of the TrkB receptor antagonist, ANA-12, or intrathecal injection of exogenous BDNF. Mechanical allodynia in the suprapubic region was assessed using the von Frey filaments test. The expression of BDNF, TrkB, p-TrkB, Iba1, GFAP, p-p38, p-JNK, IL-1β, and TNF-α in the L6-S1 SDH was measured by Western blotting and immunofluorescence analysis.

RESULTS

BDNF-TrkB signaling was upregulated significantly in the SDH after CYP was injected. Similarly, the expressions of Iba1, GFAP, p-p38, p-JNK, IL-1β, and TNF-α in the SDH were all upregulated. Treatment with ANA-12 could attenuate mechanical allodynia, restrain activation of astrocytes and microglia and alleviate neuroinflammation. Besides, the intrathecal injection of exogenous BDNF further decreased the mechanical withdrawal threshold, promoted activation of astrocytes and microglia, and increased the release of TNF-α and IL-1β in the SDH of our CYP-induced cystitis model.

CONCLUSIONS

In our CYP-induced cystitis model, BDNF promoted the activation of astrocytes and microglia to release TNF-α and IL-1β, aggravating neuroinflammation and leading to mechanical allodynia through BDNF-TrkB-p38/JNK signaling.

Chromium picolinate attenuates cognitive deficit in ICV-STZ rat paradigm of sporadic Alzheimer's-like dementia via targeting neuroinflammatory and IRS-1/PI3K/AKT/GSK-3β pathway

Alzheimer's disease (AD) is prevalent in old age people and is one of the most common brain diseases. Brain insulin resistance, neuroinflammation, oxidative stress, and mitochondrial and cholinergic dysfunction are key features of the disease. In our study, streptozotocin (STZ) in a dose of 3 mg/kg was injected in male Wistar rats bilaterally through the intracerebroventricular (ICV) route on stereotaxic apparatus. Chromium picolinate (CrPic) was tested at doses of 1 mg/kg, 2 mg/kg, and 4 mg/kg, while rivastigmine (2 mg/kg) was used as reference standard drug. Cognitive dysfunction induced by STZ was assessed by behavioral tests like Morris water maze and novel object recognition test. Treatment with CrPic revealed attenuation of cognitive deficit. This was confirmed by behavioral tests, biochemical estimations of antioxidant enzymes, oxidative stress, nitrosative stress, and cholinergic and mitochondrial activity. CrPic did not change AchE activity significantly. STZ-induced neuroinflammation evident by increased TNF-α, IL-6, and CRP levels was also significantly decreased by CrPic. Dysfunctional insulin signaling after ICV-STZ was demonstrated by reduced IRS-1, PI3K, AKT, BDNF gene expression, and increased GSK-3β, NF-κB gene expression with the help of qRT-PCR. CrPic treatment produced an improvement in insulin signaling revealed by increased gene expression of IRS-1, PI3-K, AKT, BDNF, and decreased gene expression of GSK-3β and NF-κB. It was concluded that CrPic reversed AD pathology revealed by improved memory, reduced oxidative stress, neuroinflammation, mitochondrial dysfunction, and upregulated insulin signaling.

The Novel Perspectives of Adipokines on Brain Health

First seen as a fat-storage tissue, the adipose tissue is considered as a critical player in the endocrine system. Precisely, adipose tissue can produce an array of bioactive factors, including cytokines, lipids, and extracellular vesicles, which target various systemic organ systems to regulate metabolism, homeostasis, and immune response. The global effects of adipokines on metabolic events are well defined, but their impacts on brain function and pathology remain poorly defined. Receptors of adipokines are widely expressed in the brain. Mounting evidence has shown that leptin and adiponectin can cross the blood–brain barrier, while evidence for newly identified adipokines is limited. Significantly, adipocyte secretion is liable to nutritional and metabolic states, where defective circuitry, impaired neuroplasticity, and elevated neuroinflammation are symptomatic. Essentially, neurotrophic and anti-inflammatory properties of adipokines underlie their neuroprotective roles in neurodegenerative diseases. Besides, adipocyte-secreted lipids in the bloodstream can act endocrine on the distant organs. In this article, we have reviewed five adipokines (leptin, adiponectin, chemerin, apelin, visfatin) and two lipokines (palmitoleic acid and lysophosphatidic acid) on their roles involving in eating behavior, neurotrophic and neuroprotective factors in the brain. Understanding and regulating these adipokines can lead to novel therapeutic strategies to counteract metabolic associated eating disorders and neurodegenerative diseases, thus promote brain health.

The neuroprotective effect and action mechanism of polyphenols in diabetes mellitus-related cognitive dysfunction

BACKGROUND

Diabetes mellitus (DM) is a complex and prevalent metabolic disorder worldwide. Strong evidence has emerged that DM is a risk factor for the accelerated rate of cognitive decline and the development of dementia. Though traditional pharmaceutical agents are efficient for the management of DM and DM-related cognitive decrement, long-term use of these drugs are along with undesired side effects. Therefore, tremendous studies have focused on the therapeutic benefits of natural compounds at present. Ample evidence exists to prove that polyphenols are capable to modulate diabetic neuropathy with minimal toxicity and adverse effects.

PURPOSE

To describe the benefits and mechanisms of polyphenols on DM-induced cognitive dysfunction. In this review, we introduce an updated overview of associations between DM and cognitive dysfunction. The risk factors as well as pathological and molecular mechanisms of DM-induced cognitive dysfunction are summarized. More importantly, many active polyphenols that possess preventive and therapeutic effects on DM-induced cognitive dysfunction and the potential signaling pathways involved in the action are highlighted.

CONCLUSIONS

The therapeutic effects of polyphenols on DM-related cognitive dysfunction pave a novel way for the management of diabetic encephalopathy.