Brain-derived neurotrophic factor: a mediator of inflammation-associated neurogenesis in Alzheimer's disease

The neuroprotective effect of vitamin D in Parkinson's disease: association or causation

Parkinson's disease (PD) is a chronic neurodegenerative disease (NDD) due to the degeneration of dopaminergic neurons (DNs) in the substantia nigra (SN). PD is characterized by diverse motor symptoms such as rigidity, resting tremors, and bradykinesia, and non-motor symptoms such as cognitive dysfunction and sleep disturbances. Vitamin D (VD), VD receptor (VDR), and VD metabolites are present in the brain and play a role in maintaining the development, differentiation, and functions of the DNs. VDRs exert protective effects against PD neuropathology by modulating functional capacity and DNs neurotransmission in the SN. In virtue of its anti-inflammatory and antioxidant activities, VD could be effective in the prevention and treatment of PD. VD exerts a neuroprotective effect by reducing oxidative stress and mitochondrial dysfunction, and by increasing autophagy and brain-derived neurotrophic factor (BDNF). Low VD serum level is connected with cognitive dysfunction and the development of dementia in PD. The VD-mediated cognitive augmenting effect is interrelated to the safeguarding of synaptic plasticity and modulation of neurotransmitter release. VD deficiency is linked with the severity of olfactory dysfunction which precedes the progression of symptomatic PD. However, the precise role of VD in PD remains unidentified, and there is a conflict about whether treatment with VD can ameliorate PD or not.

Masitinib as a neuroprotective agent: a scoping review of preclinical and clinical evidence

OBJECTIVES

Masitinib, originally developed as a tyrosine kinase inhibitor for cancer treatment, has shown potential neuroprotective effects in various neurological disorders by modulating key pathways implicated in neurodegeneration. This scoping review aimed to summarize the current evidence of masitinib's neuroprotective activities from preclinical to clinical studies.

METHODS

This scoping review was conducted following the guidelines described by Arksey and O'Malley and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The inclusion criteria covered all original studies reporting on the neuroprotective effects of masitinib, including clinical studies, animal studies, and in vitro studies.

RESULTS

A total of 16 studies met the inclusion criteria and were included in the review. These comprised five randomized controlled trials (RCTs), one post-hoc analysis study, one case report, and nine animal studies. The RCTs focused on Alzheimer's disease (two studies), multiple sclerosis (two studies), and amyotrophic lateral sclerosis (one study). Across all included studies, masitinib consistently demonstrated neuroprotective properties. However, the majority of RCTs reported concerns regarding the safety profile of masitinib. Preclinical studies revealed the neuroprotective mechanisms of masitinib, which include inhibition of certain kinases interfering with cell proliferation and survival, reduction of neuroinflammation, and exhibition of antioxidant activity.

CONCLUSION

The current evidence suggests a promising therapeutic benefit of masitinib in neurodegenerative diseases. However, further research is necessary to validate and expand upon these findings, particularly regarding the precise mechanisms through which masitinib exerts its therapeutic effects. Future studies should also focus on addressing the safety concerns associated with masitinib use.

The regulatory role of BDNF in neuroimmune axis function and neuroinflammation induced by chronic stress: A new therapeutic strategies for neurodegenerative disorders

Neurodegenerative disorders account for a high proportion of neurological diseases that significantly threaten public health worldwide. Various factors are involved in the pathophysiology of such diseases which can lead to neurodegeneration and neural damage. Furthermore, neuroinflammation is a well-known factor in predisposing factors of neurological and especially neurodegenerative disorders which can be strongly suppressed by "anti-inflammatory" actions of brain-derived neurotrophic factor (BDNF). Stress has has also been identified as a risk factor in developing neurodegenerative disorders potentially leading to increased neuroinflammation in the brain and progressive loss in neuronal structures and impaired functions in the CNS. Recently, more studies have increasingly been focused on the role of neuroimmune system in regulating the neurobiology of stress. Emerging evidence indicate that exposure to chronic stress might alter the susceptibility to neurodegeneration via influencing the microglia function. Microglia is considered as the first responding group of cells in suppressing neuroinflammation, leading to an increased inflammatory cytokine signaling that promote the synaptic plasticity deficiencies, impairment in neurogenesis, and development of neurodegenerative disorders. In this review we discuss how exposure to chronic stress might alter the neuroimmune response potentially leading to progress of neurodegenerative disorders. We also emphasize on the role of BDNF in regulating the neuroimmune axis function and microglia modulation in neurodegenerative disorders.

Ameliorative effect of scopolamine-induced cognitive dysfunction by Fufangmuniziqi formula: The roles of alkaloids, saponins, and flavonoids

ETHNOPHARMACOLOGICAL RELEVANCE

Fufangmuniziqi formula (FFMN), a traditional Uyghur medicine used in China, is derived from an ancient Uyghur medical book and consists of 13 herbs. The herbs of FFMN, such as Peganum harmala L., Glycyrrhiza uralensis Fisch., and Nigella glandulifera, have been demonstrated to have acetylcholinesterase (AChE) inhibitory, anti-neuroinflammatory, or antioxidant effects. Therefore, FFMN may have a good anti-Alzheimer's disease (AD) effect, but its specific action and mechanism need to be further proven.

AIM OF THE STUDY

This study aims to investigate the anti-AD effects of FFMN and the role played by alkaloids, flavonoids, and saponins in anti-AD.

MATERIALS AND METHODS

The alkaloids, flavonoids, and saponins fractions of FFMN were prepared by macroporous resin chromatography. The absorbed ingredients in the drug-containing serum were identified by UPLC⁃Q⁃TOF⁃MS. An AD mouse model was established by intraperitoneal injection of scopolamine (SCO). The role of different fractions of FFMN in the anti-AD process was examined by Morris water maze (MWM), in-vitro cell, and AChE inhibition assay.

RESULTS

A total of 20 ingredients were identified in the serum samples collected after oral administration of FFMN, and seven compounds were selected as candidate active compounds. MWM experiments showed that different fractions of FFMN could significantly improve SCO-induced learning memory impairment in mice. The alkaloids fraction (ALK) regulated cholinergic function by inhibiting AChE activity, activating choline acetyltransferase activity, and protein expression. Flavonoids and saponins were more potent than the ALK in downregulating pro-inflammatory factors or inflammatory mediators, such as TNF-α, MPO, and nitric oxide. Western blot results further confirmed that flavonoids and saponins attenuated neuroinflammation by inhibiting the phosphorylation of IκB and NF-κB p65. This result was also verified by in-vitro cellular assays. FFMN enhanced antioxidant defense by increasing the activity of superoxide dismutase and reducing the production of MDA. Combined with cellular experiments, flavonoids and saponins were proven more protective against oxidative damage.

CONCLUSION

FFMN improved cognitive and memory impairment in the SCO-induced AD mouse model. ALK mainly enhanced the function of the cholinergic system. Flavonoid and saponin fractions mainly attenuated neuroinflammation and oxidative stress by modulating the NF-κB pathway. All these findings strongly suggested that the combination of alkaloid, flavonoid, and saponin fractions derived from FFMN is a promising anti-AD agent that deserves further development.

Dexmedetomidine mitigates neuroinflammation in an Alzheimer's disease mouse model via the miR-204-3p/FBXL7 signaling axis

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder characterized by neuroinflammation. Dexmedetomidine (Dex) is known for its neuroprotective properties in clinical settings. In this study, we investigated the potential of Dex in protecting against neuroinflammation in an AD mouse model induced by amyloid-beta (Aβ) injection. First, in the AD mouse model, Aβ injection were administered, and the model was confirmed through behavioral tests, including the Morris water maze and Y-maze. Neuroinflammatory states in Aβ-injected mice were assessed using hematoxylin and eosin staining and enzyme-linked immunosorbent assay. Expression levels of microRNA (miR)-204-3p and F-box/LRR-repeat protein 7 (FBXL7) in mouse tissues were determined through real-time quantitative polymerase chain reaction and Western blot. The binding interaction between miR-204-3p and FBXL7 was elucidated using dual-luciferase analysis. Aβ-injected mice exhibited cognitive impairment, neuroinflammation, and downregulated miR-204-3p. Upregulation of miR-204-3p reduced inflammatory infiltration and mitigated neuroinflammation in Aβ-injected mice. Dex treatment reduced inflammation in hippocampal tissues of Aβ-injected mice. Dex treatment upregulated miR-204-3p, leading to suppressed FBXL7 expression in tissues. Inhibition of miR-204-3p or overexpression of FBXL7 reversed the alleviating effect of Dex on neuroinflammation in Aβ-injected mice. Overall, Dex increased miR-204-3p expression, resulting in the inhibition of FBXL7, and subsequently alleviated neuroinflammation in Aβ-injected mice.

Molecular and neural roles of sodium-glucose cotransporter 2 inhibitors in alleviating neurocognitive impairment in diabetic mice

Diabetes causes a variety of molecular changes in the brain, making it a real risk factor for the development of cognitive dysfunction. Complex pathogenesis and clinical heterogeneity of cognitive impairment makes the efficacy of current drugs limited. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) gained our attention as drugs with potential beneficial effects on the CNS. In the present study, these drugs ameliorated the cognitive impairment associated with diabetes. Moreover, we verified whether SGLT2i can mediate the degradation of amyloid precursor protein (APP) and modulation of gene expression (Bdnf, Snca, App) involved in the control of neuronal proliferation and memory. The results of our research proved the participation of SGLT2i in the multifactorial process of neuroprotection. SGLT2i attenuate the neurocognitive impairment through the restoration of neurotrophin levels, modulation of neuroinflammatory signaling, and gene expression of Snca, Bdnf, and App in the brain of diabetic mice. The targeting of the above-mentioned genes is currently seen as one of the most promising and developed therapeutic strategies for diseases associated with cognitive dysfunction. The results of this work could form the basis of a future administration of SGLT2i in diabetics with neurocognitive impairment.

Selective Targeting of Class I HDAC Reduces Microglial Inflammation in the Entorhinal Cortex of Young APP/PS1 Mice

BG45 is a class Ⅰ histone deacetylase inhibitor (HDACI) with selectivity for HDAC3. Our previous study demonstrated that BG45 can upregulate the expression of synaptic proteins and reduce the loss of neurons in the hippocampus of APPswe/PS1dE9 (APP/PS1) transgenic mice (Tg). The entorhinal cortex is a pivotal region that, along with the hippocampus, plays a critical role in memory in the Alzheimer's disease (AD) pathology process. In this study, we focused on the inflammatory changes in the entorhinal cortex of APP/PS1 mice and further explored the therapeutic effects of BG45 on the pathologies. The APP/PS1 mice were randomly divided into the transgenic group without BG45 (Tg group) and the BG45-treated groups. The BG45-treated groups were treated with BG45 at 2 months (2 m group), at 6 months (6 m group), or twice at 2 and 6 months (2 and 6 m group). The wild-type mice group (Wt group) served as the control. All mice were killed within 24 h after the last injection at 6 months. The results showed that amyloid-β (Aβ) deposition and IBA1-positive microglia and GFAP-positive astrocytes in the entorhinal cortex of the APP/PS1 mice progressively increased over time from 3 to 8 months of age. When the APP/PS1 mice were treated with BG45, the level of H3K9K14/H3 acetylation was improved and the expression of histonedeacetylase1, histonedeacetylase2, and histonedeacetylase3 was inhibited, especially in the 2 and 6 m group. BG45 alleviated Aβ deposition and reduced the phosphorylation level of tau protein. The number of IBA1-positive microglia and GFAP-positive astrocytes decreased with BG45 treatment, and the effect was more significant in the 2 and 6 m group. Meanwhile, the expression of synaptic proteins synaptophysin, postsynaptic density protein 95, and spinophilin was upregulated and the degeneration of neurons was alleviated. Moreover, BG45 reduced the gene expression of inflammatory cytokines interleukin-1β and tumor necrosis factor-α. Closely related to the CREB/BDNF/NF-kB pathway, the expression of p-CREB/CREB, BDNF, and TrkB was increased in all BG45 administered groups compared with the Tg group. However, the levels of p-NF-kB/NF-kB in the BG45 treatment groups were reduced. Therefore, we deduced that BG45 is a potential drug for AD by alleviating inflammation and regulating the CREB/BDNF/NF-kB pathway, and the early, repeated administration of BG45 can play a more effective role.

Modifiable risk factors of dementia linked to excitation-inhibition imbalance

Recent evidence identifies 12 potentially modifiable risk factors for dementia to which 40% of dementia cases are attributed. While the recognition of these risk factors has paved the way for the development of new prevention measures, the link between these risk factors and the underlying pathophysiology of dementia is yet not well understood. A growing number of recent clinical and preclinical studies support a role of Excitation-Inhibition (E-I) imbalance in the pathophysiology of dementia. In this review, we aim to propose a conceptual model on the links between the modifiable risk factors and the E-I imbalance in dementia. This model, which aims to address the current gap in the literature, is based on 12 mediating common mechanisms: the hypothalamic-pituitary-adrenal (HPA) axis dysfunction, neuroinflammation, oxidative stress, mitochondrial dysfunction, cerebral hypo-perfusion, blood-brain barrier (BBB) dysfunction, beta-amyloid deposition, elevated homocysteine level, impaired neurogenesis, tau tangles, GABAergic dysfunction, and glutamatergic dysfunction. We believe this model serves as a framework for future studies in this field and facilitates future research on dementia prevention, discovery of new biomarkers, and developing new interventions.

The Neuroprotection of Verbascoside in Alzheimer’s Disease Mediated through Mitigation of Neuroinflammation via Blocking NF-κB-p65 Signaling

Verbascoside (VB) is a phenylethanoid glycoside extracted from the herbaceous plant Verbascum sinuatum and plays a neuroprotective role in Alzheimer’s disease (AD). The goal of this study was to explore the neuroprotective mechanism of VB. Based on the proteomics analysis, immunohistochemistry, immunofluorescence, Western blot, and ELISA were utilized to explore the neuroprotective mechanism of VB in context of neuroinflammation in APP/PS1 mice, LPS-induced BV2 cells, and/or Aβ_1-42-stimulated N2a cells. Proteomic analysis demonstrated that the neuroprotection of VB correlated closely to its anti-inflammatory effect. VB significantly blocked microglia and astrocyte against activation in brains of APP/PS1 mice, suppressed the generation of IL-1β as well as IL-6, and boosted that of IL-4, IL-10 and TGF-β in vivo, which were analogous to results acquired in vitro. Furthermore, VB effectively restrained the phosphorylation of IKKα+β, IκBα, and NF-κB-p65 in APP/PS1 mice; LPS-induced BV2 cells, and Aβ_1-42-stimulated N2a cells and lowered the tendency of NF-κB-p65 translocation towards nucleus in vitro. These results demonstrate that the neuroprotective effect of VB correlates to the modulation of neuroinflammation via NF-κB-p65 pathway, making VB as a hopeful candidate drug for the prevention and treatment of AD.

Microglia Function on Precursor Cells in the Adult Hippocampus and Their Responsiveness to Serotonin Signaling

Microglia are the resident immune cells of the adult brain that become activated in response to pathogen- or damage-associated stimuli. The acute inflammatory response to injury, stress, or infection comprises the release of cytokines and phagocytosis of damaged cells. Accumulating evidence indicates chronic microglia-mediated inflammation in diseases of the central nervous system, most notably neurodegenerative disorders, that is associated with disease progression. To understand microglia function in pathology, knowledge of microglia communication with their surroundings during normal state and the release of neurotrophins and growth factors in order to maintain homeostasis of neural circuits is of importance. Recent evidence shows that microglia interact with serotonin, the neurotransmitter crucially involved in adult neurogenesis, and known for its role in antidepressant action. In this chapter, we illustrate how microglia contribute to neuroplasticity of the hippocampus and interact with local factors, e.g., BDNF, and external stimuli that promote neurogenesis. We summarize the recent findings on the role of various receptors in microglia-mediated neurotransmission and particularly focus on microglia’s response to serotonin signaling. We review microglia function in neuroinflammation and neurodegeneration and discuss their novel role in antidepressant mechanisms. This synopsis sheds light on microglia in healthy brain and pathology that involves serotonin and may be a potential therapeutic model by which microglia play a crucial role in the maintenance of mood.

Cattle Encephalon Glycoside and Ignotin Protects Neurons Against Microglia-Induced Neuroinflammation via Elevating BDNF Expression and Inhibiting TLR4/NF-κB Pathway

Neuroinflammation is involved in the pathology and progression of Alzheimer's disease (AD) and is closely related to microglial activation. We have previously reported that cattle encephalon glycoside and ignotin (CEGI) could inhibit the activation of microglia in APP/PS1 mice, a mouse model of familial AD. However, the anti-neuroinflammatory mechanisms of CEGI have not yet been fully elucidated. Here, we aimed to investigate the role of CEGI in microglia-mediated neuroinflammation in AD. APP/PS1 mice were treated with CEGI intraperitoneally for 30 days, and then their cognition was assessed. We showed that CEGI alleviated cognitive damage with higher nesting scores, preferential indices, and spontaneous alternation rates in APP/PS1 mice. Moreover, CEGI treatment effectively reduced microglial activation and Iba-1 levels in the cortex of APP/PS1 mice. Additionally, CEGI decreased pro-inflammatory factors production and neuroinflammation-mediated neuronal damage in vivo and in vitro. Finally, CEGI upregulated BDNF levels and downregulated TLR4 and p-NF-κB p65 levels in vivo and in vitro. Taken together, these findings indicated that CEGI could attenuate cognitive deficits in APP/PS1 mice and suppress microglia-induced neuroinflammation via increasing BDNF expression and inhibiting the TLR4/NF-κB pathway.

Pharmacological Strategies to Improve Dendritic Spines in Alzheimer's Disease

To deeply understand late onset Alzheimer's disease (LOAD), it may be necessary to change the concept that it is a disease exclusively driven by aging processes. The onset of LOAD could be associated with a previous peripheral stress at the level of the gut (changes in the gut microbiota), obesity (metabolic stress), and infections, among other systemic/environmental stressors. The onset of LOAD, then, may result from the generation of mild peripheral inflammatory processes involving cytokine production associated with peripheral stressors that in a second step enter the brain and spread out the process causing a neuroinflammatory brain disease. This hypothesis could explain the potential efficacy of Sodium Oligomannate (GV-971), a mixture of acidic linear oligosaccharides that have shown to remodel gut microbiota and slowdown LOAD. However, regardless of the origin of the disease, the end goal of LOAD-related preventative or disease modifying therapies is to preserve dendritic spines and synaptic plasticity that underlay and support healthy cognition. Here we discuss how systemic/environmental stressors impact pathways associated with the regulation of spine morphogenesis and synaptic maintenance, including insulin receptor and the brain derived neurotrophic factor signaling. Spine structure remodeling is a plausible mechanism to maintain synapses and provide cognitive resilience in LOAD patients. Importantly, we also propose a combination of drugs targeting such stressors that may be able to modify the course of LOAD by acting on preventing dendritic spines and synapsis loss.

Evolution of BDNF serum levels during the first six months after alcohol withdrawal

OBJECTIVES

Brain-Derived Neurotrophic Factor (BDNF) has been associated with alcohol dependence and appear to vary after withdrawal, although the link with the withdrawal outcome on the long term is unknown. We aimed to assess the evolution of BDNF levels during the six months following withdrawal and determine the association with the status of alcohol consumption.

METHODS

Serum BDNF levels of alcohol-dependent patients (n = 248) and biological and clinical parameters were determined at the time of alcohol cessation (D0), 14 days (D14), 28 days (D28), and 2, 4, and 6 months after (M2, M4, M6).

RESULTS

Abstinence decreased during follow-up and was 31.9% after six months. BDNF levels increased by 14 days after withdrawal and remained elevated throughout the six-month period, independently of alcohol consumption. Serum BDNF levels evolved over time (p < 0.0001), with a correlation between BDNF and GGT levels. The prescription of baclofen at the time of withdrawal was associated with higher serum BDNF levels throughout the follow-up and that of anti-inflammatory drugs with lower BDNF levels.

CONCLUSIONS

A link between BDNF levels, liver function, and the inflammatory state in the context of alcohol abuse and not only with alcohol dependence itself is proposed.

BDNF levels and liver stiffness in subjects with alcohol use disorder: Evaluation after alcohol withdrawal

Background: Brain-derived neurotrophic factor (BDNF) plays a key role in the processes of withdrawal and addiction in alcohol use disorder (AUD), and is also involved in liver homeostasis. The role of BDNF in liver damage and its link with liver stiffness are not known. We hypothesize that serum BDNF levels are linked to changes in hepatic elasticity, both of which depend on variations in alcohol consumption.Objectives: We aimed to study the evolution of BDNF levels and changes in the liver stiffness (LS) of AUD subjects, within two months following withdrawal.Methods: We measured LS by FibroScan® (as an indicator of the degree of liver fibrosis), gamma glutamyl transferase (GGT) levels (as a nonspecific but sensitive marker of liver status) and serum BDNF levels of 62 alcohol-dependent subjects without previously identified liver complications. Measures were obtained at the time of withdrawal (M0) and two months later (M2). Results: BDNF levels increased after alcohol withdrawal and small variations of LS were observed. BDNF values increased significantly according to fibrosis stages measured by LS (p = .028 at M0), and were predicted by GGT levels in a regression model (p = .007 at M0 and p = .003 at M2).Conclusion: In AUD, BDNF levels were associated with measured LS when divided into fibrosis risk categories. Changes in LS and BDNF levels after alcohol withdrawal may be related to changes in homeostatic mechanisms, in addition to those of liver status.

Is Blood Brain-Derived Neurotrophic Factor a Useful Biomarker to Monitor Mild Cognitive Impairment Patients?

Availability of reliable prognostic biomarkers that are also able to monitor preventive/therapeutic interventions in patients with mild cognitive impairment (MCI) is crucial. Cerebral brain-derived neurotrophic factor (BDNF) alterations were evidenced in Alzheimer's disease, but the value of blood BDNF in MCI is unclear, especially because of the incomplete/incorrect management of the numerous confounding factors unrelated to the disease. This study, applying a multidisciplinary methodological approach, aimed at clarifying whether blood BDNF can really mirror the cognitive symptoms of MCI, thus supporting the evaluation of clinical protocols' effectiveness as well as the definition of the conversion rate to dementia. Healthy elderly subjects (HE) and MCI patients were assessed for sociodemographic, neuropsychological, pharmacological, and lifestyle data, and plasma BDNF was measured (baseline); then, in the MCI cohort, the biomarker was tested in a comprehensive cognitive stimulation intervention (CS) as well as in a 2-year follow-up period. Plasma BDNF, cleansed from all the interfering factors, (1) did not discriminate HE and MCI patients; (2) in MCI patients reflected mood, social engagement, and subjective memory complaints but not cognition; (3) changed due to CS, although with no correlations to cognitive performances; and (4) predicted no functional deterioration. Our data indicate that the possible biased use of plasma BDNF in MCI is critically risky.

Serum pro-BDNF levels correlate with phospho-tau staining in Alzheimer's disease

Disruption of brain-derived neurotrophic factor (BDNF) biosynthesis and/or signaling has been implicated in the pathogenesis of Alzheimer's disease (AD). We used postmortem brain and fluid samples from 20 patients with variable severity of AD and 11 controls to investigate whether BDNF levels in serum and brain tissue correlated with hippocampal pathology. Total BDNF, precursor BDNF (pro-BDNF), and mature BDNF were measured in cerebrospinal fluid, serum, and 3 postmortem brain regions. Histological markers for AD pathology, the BDNF cognate receptor (TrkB), and glia were measured in the hippocampus (HIP). Lower pro-BDNF levels were observed in the entorhinal and frontal cortices in AD cases compared with controls. AD cases also exhibited significantly lower staining densities of the cognate BDNF receptor TrkB in the HIP compared with controls, and TrkB staining was inversely correlated with both Amylo-Glo and pTau staining in the same region, suggesting a relationship between the density of the cognate BDNF receptor and accumulation of AD pathology. In addition, higher serum pro-BDNF levels correlated with lower HIP pro-BDNF levels and higher pTau staining in the HIP. Total BDNF levels in cortical regions were also negatively correlated with Amylo-Glo staining in the HIP suggesting that reduced BDNF cortical levels might influence hippocampal amyloid accumulation. These results strongly suggest that altered BDNF and TrkB receptors are involved in AD pathology and therefore warrant investigations into therapies involving the BDNF pathway.

Centella asiatica Prevents Increase of Hippocampal Tumor Necrosis Factor-α Independently of Its Effect on Brain-Derived Neurotrophic Factor in Rat Model of Chronic Stress

Centella asiatica ameliorates memory impairment and induces expression of hippocampal brain-derived neurotropic factor (BDNF) in chronically stressed rats. The relationship between the anti-inflammatory effect of Centella asiatica on hippocampal BDNF and the involvement of sirtuin-1, a BDNF expression regulator, in neuroprotective mechanisms of Centella asiatica warrants an investigation. We investigated the effect of Centella asiatica ethanolic extracts (CA) on TNF-α, IL-10, and SIRT1 levels and whether these predicted BDNF expression in rat hippocampus after chronic stress. For the experiments, thirty male rats (Sprague Dawley) were divided into six groups: nonstressed-control, stressed-control, nonstressed +CA 300mg/kg/d, stressed +CA 150 mg/kg/d, stressed +CA 300 mg/kg/d, and stressed +CA 600 mg/kg/d. On day 28, rats were sacrificed and hippocampus was dissected out. Hippocampal TNF-α, IL-10, SIRT1, and BDNF were measured by enzyme-linked immunosorbent assay. Hippocampal TNF-α level was significantly higher in the stressed-control compared to nonstressed-control groups. Across all stress conditions, rats receiving the highest dose of CA had the lowest mean TNF-α and highest mean BDNF. There were no significant differences in IL-10 and SIRT1 levels between groups. Hippocampal TNF-α did not predict hippocampal BDNF in a regression analysis. In conclusion, lower TNF-α and higher BDNF in the hippocampus support the hypothesis that these factors independently contribute to Centella asiatica's neuroprotective effect in chronically stressed rats.

Early treadmill exercise increases macrophage migration inhibitory factor expression after cerebral ischemia/reperfusion

The neuroprotective function of macrophage migration inhibitory factor (MIF) in ischemic stroke was rarely evaluated. This study aimed to investigate the effects of early treadmill exercise on recovery from ischemic stroke and to determine whether these effects are associated with the expression levels of MIF and brain-derived neurotrophic factor (BDNF) in the ischemic area. A total of 40 male Sprague-Dawley rats were randomly assigned to the ischemia and exercise group [middle cerebral artery occlusion (MCAO)-Ex, n = 10), ischemia and sedentary group (MCAO-St, n = 10), sham-surgery and exercise group (Sham-Ex, n = 10), or sham-surgery and sedentary group (Sham-St, n = 10). The MCAO-Ex and MCAO-St groups were subjected to MCAO for 60 minutes, whereas the Sham-Ex and Sham-St groups were subjected to an identical operation without MCAO. Rats in the MCAO-Ex and Sham-Ex groups then ran on a treadmill for 30 minutes once a day for 5 consecutive days. After reperfusion, the hanging time tested by the wire hang test was longer and the relative fractional anisotropy determined by MRI was higher in the peri-infarct region of the MCAO-Ex group compared with the MCAO-St group. The expression levels of MIF and BDNF in the peri-infarct region were upregulated in the MCAO-Ex group. Increased MIF and BDNF levels were positively correlated with relative fractional anisotropy changes in the peri-infarct region. There was no significant difference in the levels of MIF and BDNF in the peri-infarct region between the Sham-Ex and Sham-St groups. Our study demonstrated that early exercise (initiated 48 hours after the MCAO) could improve motor and neuronal recovery after ischemic stroke. Furthermore, the increased levels of MIF and BDNF in the peri-infarct region (penumbra) may be one of the mechanisms of enhanced neurological function recovery. All experiments were approved by the Institutional Animal Care and Use Committee in Asan Medical Center in South Korea (2016-12-126).

Sex Differences in Risk for Alzheimer's Disease Related to Neurotrophin Gene Polymorphisms: The Cache County Memory Study

Neurotrophins, including nerve-growth factor and brain-derived neurotrophic factor, have been implicated in Alzheimer's disease (AD). Associations between AD and neurotrophin signaling genes have been inconsistent, with few studies examining sex differences in risk. We examined four single-nucleotide polymorphisms (SNPs) involved in neurotrophin signaling (rs6265, rs56164415, rs2289656, rs2072446) and risk for AD by sex in a population-based sample of older adults. Three thousand four hundred and ninety-nine individuals without dementia at baseline [mean (standard deviation) age = 74.64 (6.84), 58% female] underwent dementia screening and assessment over four triennial waves. Cox regression was used to examine time to AD or right censoring for each SNP. Female carriers of the minor T allele for rs2072446 and rs56164415 had a 60% (hazard ratio [HR] = 1.60, 95% confidence interval [CI] = 1.02-2.51) and 93% (HR = 1.93, 95% CI = 1.30-2.84) higher hazard for AD, respectively, than male noncarriers of the T allele. Furthermore, male carriers of the T allele of rs2072446 had a 61% lower hazard (HR = 0.39, 95% CI = 0.14-1.06) than male noncarriers at trend-level significance (p = .07). The association between certain neurotrophin gene polymorphisms and AD differs by sex and may explain inconsistent findings in the literature.

Exercise training with concomitant nitric oxide synthase inhibition improved anxiogenic behavior, spatial cognition, and BDNF/P70S6 kinase activation in 20-month-old rats

This study aimed to investigate the effect of exercise and nitric oxide synthase (NOS) inhibition on memory, anxiety, and protein levels of brain-derived neurotrophic factor (BDNF) and P70S6 kinase (P70S6K). Twenty-month-old rats were divided into 6 groups: a control group, 2 groups treated with l-nitro-arginine methyl ester (L-NAME) (25 or 100 mg/kg) for 63 days, 2 groups treated with L-NAME (25 or 100 mg/kg) for 63 days plus 2 months of exercise, and 1 group treated with exercise. Behavioral tests were conducted to determine the anxiolytic and memory-improving role of exercise and NOS inhibition. BDNF, P70S6K, and cleaved caspase-3 protein levels in the hippocampus and prefrontal cortex were evaluated by Western blotting. Exercise and L-NAME (25 mg/kg) or their combination had an anxiolytic effect and improved spatial memory in old rats compared with the control or exercised group, respectively. Exercise and treatment with a low dose of L-NAME (25 mg/kg) each increased BDNF and P70S6K in the hippocampus and prefrontal cortex compared with levels in control rats. In comparison with exercise alone, co-treatment with exercise and a low dose of L-NAME (25 mg/kg) also increased BDNF and P70S6K in the hippocampus. The neuronal level of cleaved caspase-3 was reduced in the L-NAME (25 mg/kg) + exercise group compared with the exercised group. The L-NAME (100 mg/kg) + exercise treatment had no positive behavioral or molecular effects compared with exercise alone. The protective role of NOS inhibition and aerobic exercise against aging is probably modulated via BDNF and P70S6K in the brain.