proBDNF expression induces apoptosis and inhibits synaptic regeneration by regulating the RhoA-JNK pathway in an in vitro post-stroke depression model

The therapeutic potential of curculigoside in poststroke depression: a focus on hippocampal neurogenesis and mitochondrial function

OBJECTIVES

To investigate the effects and mechanism of curculigoside against poststroke depression (PSD).

METHODS

In vivo, a PSD rat model was created by combining bilateral common carotid artery occlusion and chronic unpredictable mild stress stimulations. After 4-week modeling and intragastrically administration of curculigoside, the effects of curculigoside on behavior, hippocampal neurogenesis, and hippocampal mitochondrial oxidative phosphorylation (OxPhos) were investigated. In vitro, PSD-like primary neural stem cells (NSCs) model was established by oxygen-glucose deprivation/recovery (OGD/R) combing high-corticosterone (CORT) concentration, followed by treatment with curculigoside. The investigation subsequently examined the impact of curculigoside on mitochondrial OxPhos, proliferation, and differentiation of NSCs under OGD/R + CORT conditions.

KEY FINDINGS

In vivo, PSD rats showed significantly depressive behaviors, dysfunctional neurogenesis in hippocampus, as well as decreased hippocampus adenosine triphosphate (ATP) levels, reduced electron transport chain complexes activity, and downregulates mitochondrial transcription factor A (TFAM) and PPAR-gamma coactivator 1 alpha (PGC-1α) expression in hippocampus. In vitro, OGD/R +CORT significantly injured the proliferation and differentiation, as well as impaired the mitochondrial OxPhos in NSCs. Curculigoside treatment was effective in improving these abnormal changes.

CONCLUSION

Curculigoside may repair hippocampal neurogenesis in PSD rats by enhancing hippocampal mitochondrial OxPhos, and has shown a great potential for anti-PSD.

p75 neurotrophin receptor modulation in mild to moderate Alzheimer disease: a randomized, placebo-controlled phase 2a trial

p75 neurotrophin receptor (p75NTR) signaling pathways substantially overlap with degenerative networks active in Alzheimer disease (AD). Modulation of p75NTR with the first-in-class small molecule LM11A-31 mitigates amyloid-induced and pathological tau-induced synaptic loss in preclinical models. Here we conducted a 26-week randomized, placebo-controlled, double-blinded phase 2a safety and exploratory endpoint trial of LM11A-31 in 242 participants with mild to moderate AD with three arms: placebo, 200 mg LM11A-31 and 400 mg LM11A-31, administered twice daily by oral capsules. This trial met its primary endpoint of safety and tolerability. Within the prespecified secondary and exploratory outcome domains (structural magnetic resonance imaging, fluorodeoxyglucose positron-emission tomography and cerebrospinal fluid biomarkers), significant drug-placebo differences were found, consistent with the hypothesis that LM11A-31 slows progression of pathophysiological features of AD; no significant effect of active treatment was observed on cognitive tests. Together, these results suggest that targeting p75NTR with LM11A-31 warrants further investigation in larger-scale clinical trials of longer duration. EU Clinical Trials registration: 2015-005263-16 ; ClinicalTrials.gov registration: NCT03069014 .

The Molecular Pathway of p75 Neurotrophin Receptor (p75NTR) in Parkinson's Disease: The Way of New Inroads

Parkinson's disease (PD) is a chronic and progressive neurodegenerative disease of the brain. PD is characterized by motor and non-motor symptoms. The p75 neurotrophin receptor (p75NTR) is a functional receptor for different growth factors including pro-brain derived neurotrophic factor (pro-BDNF), neurotrophin 3 (NT-3), and neurotrophin 4 (NT-4). Consequently, this review aimed to illustrate the detrimental and beneficial role of p75NTR in PD. Diverse studies showed that p75NTR and its downstream signaling are intricate in the pathogenesis of PD. Nevertheless, pro-apoptotic and pro-survival pathways mediated by p75NTR in PD were not fully clarified. Of note, p75NTR plays a critical role in the regulation of dopaminergic neuronal survival and apoptosis in the CNS. Particularly, p75NTR can induce selective apoptosis of dopaminergic neurons and progression of PD. In addition, p75NTR signaling inhibits the expression of transcription factors which are essential for the survival of dopaminergic neurons. Also, p75NTR expression is connected with the severity of dopaminergic neuronal injury. These verdicts implicate p75NTR signaling in the pathogenesis of PD, though the underlying mechanistic pathways remain not elucidated. Collectively, the p75NTR signaling pathway induces a double-sword effect either detrimental or beneficial depending on the ligands and status of PD neuropathology. Therefore, p75NTR signaling seems to be protective via phosphoinositide 3-kinase (PI3K)/AKT and Bcl-2 and harmful via activation of JNK, caspase 3, nuclear factor kappa B (NF-κB), and RhoA pathways.

The functional and molecular roles of p75 neurotrophin receptor (p75NTR) in epilepsy

Epilepsy is a chronic neurological disorder manifested by recurring unprovoked seizures resulting from an imbalance in the inhibitory and excitatory neurotransmitters in the brain. The process of epileptogenesis involves a complex interplay between the reduction of inhibitory gamma-aminobutyric acid (GABA) and the enhancement of excitatory glutamate. Pro-BDNF/p75NTR expression is augmented in both glial cells and neurons following epileptic seizures and status epileptics (SE). Over-expression of p75NTR is linked with the pathogenesis of epilepsy, and augmentation of pro-BDNF/p75NTR is implicated in the pathogenesis of epilepsy. However, the precise mechanistic function of p75NTR in epilepsy has not been completely elucidated. Therefore, this review aimed to revise the mechanistic pathway of p75NTR in epilepsy.

SorCS2 is involved in promoting periodontitis-induced depression-like behaviour in mice

BACKGROUND

Emerging evidence supports the association between periodontitis and depression, although the mechanisms are unclear. This study investigated the role of SorCS2 in the pathogenesis of periodontitis-induced depression.

MATERIALS AND METHODS

An experimental periodontitis model was established using SorCS2 knockout mice and their wild-type littermates, and depression-like behaviour was evaluated. The expression of proBDNF signalling, neuronal activity, and glutamate-associated signalling pathways were further measured by western blotting and immunofluorescence. In addition, neuroinflammatory status, astrocytic and microglial markers, and the expression of corticosterone-related factors were measured by immunofluorescence, western blotting, and enzyme-linked immunosorbent assays.

RESULTS

SorCS2 deficiency alleviated periodontitis-induced depression-like behaviour in mice. Further results suggested that SorCS2 deficiency downregulated the expression of pro-BDNF and glutamate signalling and restored neuronal activities in mice with periodontitis. Neuroinflammation in the mouse hippocampus was triggered by experimental periodontitis but was not affected by SorCS2 deficiency. The levels of corticosterone and the expression of glucocorticoid receptors were also not altered.

CONCLUSION

Our study, for the first time, reveals the critical role of SorCS2 in the pathogenesis of periodontitis-induced depression. The underlying mechanism involves proBDNF and glutamate signalling in the hippocampus, providing a novel therapeutic target for periodontitis-associated depression.

Research progress on post-stroke depression

Stroke is a highly prevalent and widely detrimental cardiovascular disease, frequently resulting in impairments of both motor function and neural psychological capabilities, such as post-stroke depression (PSD). PSD is the most prevalent neuropsychological disorder among stroke patients, characterized by persistent emotional lowness and diminished interest as its primary features. This article summarizes the mechanism research, animal models and related treatments of PSD. Further improvements are needed in the screening of research subjects and the construction of animal models in the study of PSD. At the same time, in the study of the mechanism of PSD, we need to consider the interaction between multiple systems. The treatment of PSD requires more careful consideration. This can help us to find something new in the study of the mechanism of complex PSD, which provides a new direction for us to develop new treatment delivery.

Serum brain-derived neurotrophic factor concentration is different between autism spectrum disorders and intellectual disability children and adolescents

PURPOSE

Recent studies showed that mature brain-derived neurotrophic factor (mBDNF) and its precursor proBDNF are associated with autism spectrum disorders (ASD). Whether their levels are different between ASD and intellectual disability (ID) subjects is not clear. The aim of this study is to compare the serum mBDNF and proBDNF concentration, and mBNDF/proBDNF ratio in ASD and ID volunteers.

METHODS

Children and adolescents with ASD or ID between the ages of 4 and 22 were recruited in Tianjin, China. Serum mBDNF and proBDNF level were tested and Wechsler Preschool and Primary Scale of Intelligence (WPPSI), Wechsler Intelligence Scale for Children (WISC), and Childhood Autism Rating Scale (CARS) evaluations were conducted.

RESULTS

Serum mBDNF concentration and the ratio of mBDNF to proBDNF was higher in ASD subjects than that in ID subjects (P = 0.035 and P < 0.001, respectively), while serum proBDNF of ASD participants was lower compared to that of ID participants (P < 0.001). CARS score was positively correlated with serum mBDNF level (r = 0.33, P = 0.004) and m/p ratio (r = 0.39, P < 0.001), and negatively correlated with serum proBDNF level (r = -0.39, <0.001) after adjusting for age and IQ. The AUC of mBDNF, proBDNF, and m/p ratio were 0.741, 0.790, and 0.854, respectively, after adjusted for age and IQ.

CONCLUSION

Serum mBDNF, proBDNF and m/p ratio were different between ASD and ID group. The three biomarkers displayed good diagnostic values for classification of ASD and ID subjects.

Genetic and Pharmacological Modulation of P75 Neurotrophin Receptor Attenuate Brain Damage After Ischemic Stroke in Mice

The precursor nerve growth factor (ProNGF) and its receptor p75 neurotrophin receptor (p75NTR) are upregulated in several brain diseases, including ischemic stroke. The activation of p75NTR is associated with neuronal apoptosis and inflammation. Thus, we hypothesized that p75NTR modulation attenuates brain damage and improves functional outcomes after ischemic stroke. Two sets of experiments were performed. (1) Adult wild-type (WT) C57BL/6 J mice were subjected to intraluminal suture-middle cerebral artery occlusion (MCAO) to induce cerebral ischemia. Pharmacological inhibitor of p75NTR, LM11A-31 (50 mg/kg), or normal saline was administered intraperitoneally (IP) 1 h post-MCAO, and animals survived for 24 h. (2) Adult p75NTR heterozygous knockout (p75NTR+/-) and WT were subjected to photothrombotic (pMCAO) to induce ischemic stroke, and the animals survived for 72 h. The sensory-motor function of animals was measured using Catwalk XT. The brain samples were collected to assess infarction volume, edema, hemorrhagic transformation, neuroinflammation, and signaling pathway at 24 and 72 h after the stroke. The findings described that pharmacological inhibition and genetic knocking down of p75NTR reduce infarction size, edema, and hemorrhagic transformation following ischemic stroke. Additionally, p75NTR modulation significantly decreased several anti-apoptosis markers and improved sensory motor function compared to the WT mice following ischemic stroke. Our observations exhibit that the involvement of p75NTR in ischemic stroke and modulation of p75NTR could improve the outcome of ischemic stroke by increasing cell survival and enhancing motor performance. LM11A-31 has the potential to be a promising therapeutic agent for ischemic stroke. However, more evidence is needed to illuminate the efficacy of LM11A-31 in ischemic stroke.

Mechanisms associated with post-stroke depression and pharmacologic therapy

Stroke is one of the most common cerebrovascular diseases, which is the cause of long-term mental illness and physical disability, Post-stroke depression (PSD) is the most common neuropsychiatric complication after stroke, and its mechanisms are characterized by complexity, plurality, and diversity, which seriously affects the quality of survival and prognosis of patients. Studies have focused on and recognized neurotransmitter-based mechanisms and selective serotonin-reuptake inhibitors (SSRIs) can be used to treat PSD. Neuroinflammation, neuroendocrinology, neurotrophic factors, and the site of the stroke lesion may affect neurotransmitters. Thus the mechanisms of PSD have been increasingly studied. Pharmacological treatment mainly includes SSRIs, noradrenergic and specific serotonergic antidepressant (NaSSA), anti-inflammatory drugs, vitamin D, ect, which have been confirmed to have better efficacy by clinical studies. Currently, there is an increasing number of studies related to the mechanisms of PSD. However, the mechanisms and pharmacologic treatment of PSD is still unclear. In the future, in-depth research on the mechanisms and treatment of PSD is needed to provide a reference for the prevention and treatment of clinical PSD.

A new perspective on hippocampal synaptic plasticity and post-stroke depression

Post-stroke depression, a common complication after stroke, severely affects the recovery and quality of life of patients with stroke. Owing to its complex mechanisms, post-stroke depression treatment remains highly challenging. Hippocampal synaptic plasticity is one of the key factors leading to post-stroke depression; however, the precise molecular mechanisms remain unclear. Numerous studies have found that neurotrophic factors, protein kinases and neurotransmitters influence depressive behaviour by modulating hippocampal synaptic plasticity. This review further elaborates on the role of hippocampal synaptic plasticity in post-stroke depression by summarizing recent research and analysing possible molecular mechanisms. Evidence for the correlation between hippocampal mechanisms and post-stroke depression helps to better understand the pathological process of post-stroke depression and improve its treatment.

Exploring Rosiglitazone's Potential to Treat Alzheimer's Disease through the Modulation of Brain-Derived Neurotrophic Factor

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that debilitates over 55 million individuals worldwide. Currently, treatments manage and alleviate its symptoms; however, there is still a need to find a therapy that prevents or halts disease progression. Since AD has been labeled as "type 3 diabetes" due to its similarity in pathological hallmarks, molecular pathways, and comorbidity with type 2 diabetes mellitus (T2DM), there is growing interest in using anti-diabetic drugs for its treatment. Rosiglitazone (RSG) is a peroxisome proliferator-activated receptor-gamma agonist that reduces hyperglycemia and hyperinsulinemia and improves insulin signaling. In cellular and rodent models of T2DM-associated cognitive decline and AD, RSG has been reported to improve cognitive impairment and reverse AD-like pathology; however, results from human clinical trials remain consistently unsuccessful. RSG has also been reported to modulate the expression of brain-derived neurotrophic factor (BDNF), a protein that regulates neuroplasticity and energy homeostasis and is implicated in both AD and T2DM. The present review investigates RSG's limitations and potential therapeutic benefits in pre-clinical models of AD through its modulation of BDNF expression.

Research Progress on the Pharmacodynamic Mechanisms of Sini Powder against Depression from the Perspective of the Central Nervous System

Depression is a highly prevalent emotional disorder characterized by persistent low mood, diminished interest, and loss of pleasure. The pathological causes of depression are associated with neuronal atrophy, synaptic loss, and neurotransmitter activity decline in the central nervous system (CNS) resulting from injuries, such as inflammatory responses. In Traditional Chinese Medicine (TCM) theory, patients with depression often exhibit the liver qi stagnation syndrome type. Sini Powder (SNP) is a classic prescription for treating such depression-related syndrome types in China. This study systematically summarized clinical applications and experimental studies of SNP for treatments of depression. We scrutinized the active components of SNP with blood-brain barrier (BBB) permeability and speculated about the corresponding pharmacodynamic pathways relevant to depression treatment through intervening in the CNS. Therefore, this article can enhance our understanding of SNP's pharmacological mechanisms and formula construction for depression treatment. Moreover, a re-demonstration of this classic TCM prescription in the modern-science language is of great significance for future drug development and research.

Microbiota-derived short-chain fatty acids may participate in post-stroke depression by regulating host's lipid metabolism

BACKGROUND

Post-stroke depression (PSD) is a common mental disorder of stroke survivors, its pathogenesis remains elusive. Previous studies suggested a role of the microbiota-gut-brain (MGB) axis in stroke and depression. In this study, we characterized microbial composition and function, and gut-brain metabolic signatures, in PSD rats. We aim to explore how disordered gut microbes participate in the pathogenesis of PSD through the MGB axis.

MATERIALS AND METHODS

16S rRNA gene sequence and fecal metabolome analysis were performed to identify the gut microbiome and their functional metabolites in PSD rats. Then, the lipid metabolic signatures in the prefrontal cortex (PFC) of PSD were conducted by liquid chromatography mass spectrometry. Finally, the potential pathway between gut and brain in the onset of PSD were explored.

RESULTS

Compared to control and stroke rats, there were 10 genera (most of them belonged to phylum Firmicutes) significantly changed and 3 short chain fatty acids (SCFAs: butyric acid, acetic acid and pentanoic acid) significantly decreased in PSD rats. Meanwhile, altered gut microbial in PSD rats was significantly associated with these SCFAs. Compared with control and stroke rats, 57 lipid metabolites in the PFC of PSD rats were significantly changed. In addition, the altered SCFAs in PSD rats were also significantly correlated with most of disordered lipid metabolites in PFC.

CONCLUSIONS

Our findings suggest that the SCFAs may be a bridge of gut-brain communication. The Firmicutes-SCFAs-lipid metabolism might be a potential pathway to further investigate the MGB axis and pathogenesis of PSD.

Effects of Aloe-Emodin on the Expression of Brain Aquaporins and Secretion of Neurotrophic Factors in a Rat Model of Post-Stroke Depression

Post-stroke depression (PSD) is a common complication of stroke that can damage patients’ brains. More and more studies have been conducted on PSD in recent years, but the exact mechanism is still not understood. Currently, animal models provide an alternative approach to better understand the pathophysiology of PSD and may also pave the way for the discovery of new treatments for depression. This study investigated the therapeutic effect and mechanism of aloe-emodin (AE) on PSD rats. Previous studies have shown that AE positively affects PSD in rats by improving depression, increasing their activities and curiosities, enhancing the number of neurons, and ameliorating damage to brain tissue. Meanwhile, AE could up-regulate the expression of brain-derived neurotrophic factor (BDNF) and neurotrophic 3 (NTF3), but it could also down-regulate the expression of aquaporins (AQP3, AQP4, and AQP5), glial fibrillary acidic protein (GFAP), and transient receptor potential vanilloid 4 (TRPV4), which is helpful in maintaining homeostasis and alleviating encephaledema. AE may be a prospective solution in the future for the treatment of PSD patients.

Deciphering the Effect of Different Genetic Variants on Hippocampal Subfield Volumes in the General Population

The aim of this study was to disentangle the effects of various genetic factors on hippocampal subfield volumes using three different approaches: a biologically driven candidate gene approach, a hypothesis-free GWAS approach, and a polygenic approach, where AD risk alleles are combined with a polygenic risk score (PRS). The impact of these genetic factors was investigated in a large dementia-free general population cohort from the Study of Health in Pomerania (SHIP, n = 1806). Analyses were performed using linear regression models adjusted for biological and environmental risk factors. Hippocampus subfield volume alterations were found for APOE ε4, BDNF Val, and 5-HTTLPR L allele carriers. In addition, we were able to replicate GWAS findings, especially for rs17178139 (MSRB3), rs1861979 (DPP4), rs7873551 (ASTN2), and rs572246240 (MAST4). Interaction analyses between the significant SNPs as well as the PRS for AD revealed no significant results. Our results confirm that hippocampal volume reductions are influenced by genetic variation, and that different variants reveal different association patterns that can be linked to biological processes in neurodegeneration. Thus, this study underlines the importance of specific genetic analyses in the quest for acquiring deeper insights into the biology of hippocampal volume loss, memory impairment, depression, and neurodegenerative diseases.

Maternal immune activation-induced proBDNF-mediated neural information processing dysfunction at hippocampal CA3-CA1 synapses associated with memory deficits in offspring

Prenatal exposure to maternal infection increases the risk of offspring developing schizophrenia in adulthood. Current theories suggest that the consequences of MIA on mBDNF secretion may underlie the increased risk of cognitive disorder. There is little evidence for whether the expression of its precursor, proBDNF, is changed and how proBDNF-mediated signaling may involve in learning and memory. In this study, proBDNF levels were detected in the hippocampal CA1 and CA3 regions of male adult rats following MIA by prenatal polyI:C exposure. Behaviorally, learning and memory were assessed in contextual fear conditioning tasks. Local field potentials were recorded in the hippocampal CA3-CA1 pathway. The General Partial Directed Coherence approach was utilized to identify the directional alternation of neural information flow between CA3 and CA1 regions. EPSCs were recorded in CA1 pyramidal neurons to explore a possible mechanism involving the proBDNF-p75NTR signaling pathway. Results showed that the expression of proBDNF in the polyI:C-treated offspring was abnormally enhanced in both CA3 and CA1 regions. Meanwhile, the mBDNF expression was reduced in both hippocampal regions. Intra-hippocampal CA1 but not CA3 injection with anti-proBDNF antibody and p75NTR inhibitor TAT-Pep5 effectively mitigated the contextual memory deficits. Meanwhile, reductions in the phase synchronization between CA3 and CA1 and the coupling directional indexes from CA3 to CA1 were enhanced by the intra-CA1 infusions. Moreover, blocking proBDNF/p75NTR signaling could reverse the declined amplitude of EPSCs in CA1 pyramidal neurons, indicating the changes in postsynaptic information processing in the polyI:C-treated offspring. Therefore, the changes in hippocampal proBDNF activity in prenatal polyI:C exposure represent a potential mechanism involved in NIF disruption leading to contextual memory impairments.

Molecular and Functional Characterization of BDNF-Overexpressing Human Retinal Pigment Epithelial Cells Established by Sleeping Beauty Transposon-Mediated Gene Transfer

More and more patients suffer from multifactorial neurodegenerative diseases, such as age-related macular degeneration (AMD). However, their pathological mechanisms are still poorly understood, which complicates the development of effective therapies. To improve treatment of multifactorial diseases, cell-based gene therapy can be used to increase the expression of therapeutic factors. To date, there is no approved therapy for dry AMD, including late-stage geographic atrophy. We present a treatment option for dry AMD that transfers the brain-derived neurotrophic factor (BDNF) gene into retinal pigment epithelial (RPE) cells by electroporation using the plasmid-based Sleeping Beauty (SB) transposon system. ARPE-19 cells and primary human RPE cells were co-transfected with two plasmids encoding the SB100X transposase and the transposon carrying a BDNF transcription cassette. We demonstrated efficient expression and secretion of BDNF in both RPE cell types, which were further increased in ARPE-19 cell cultures exposed to hydrogen peroxide. BDNF-transfected cells exhibited lower apoptosis rates and stimulated neurite outgrowth in human SH-SY5Y cells. This study is an important step in the development of a cell-based BDNF gene therapy that could be applied as an advanced therapy medicinal product to treat dry AMD or other degenerative retinal diseases.

The Role of Brain-Derived Neurotrophic Factor Signaling in Central Nervous System Disease Pathogenesis

Recent studies have found abnormal levels of brain-derived neurotrophic factor (BDNF) in a variety of central nervous system (CNS) diseases (e.g., stroke, depression, anxiety, Alzheimer’s disease, and Parkinson’s disease). This suggests that BDNF may be involved in the pathogenesis of these diseases. Moreover, regulating BDNF signaling may represent a potential treatment for such diseases. With reference to recent research papers in related fields, this article reviews the production and regulation of BDNF in CNS and the role of BDNF signaling disorders in these diseases. A brief introduction of the clinical application status of BDNF is also provided.

Aluminium oxide nanoparticles compromise spatial memory performance and proBDNF-mediated neuronal function in the hippocampus of rats

Background

Alumina nanoparticles (aluminaNPs), which are widely used in a range of daily and medical fields, have been shown to penetrate blood-brain barrier, and distribute and accumulate in different brain areas. Although oral treatment of aluminaNPs induces hippocampus-dependent learning and memory impairments, characteristic effects and exact mechanisms have not been fully elucidated. Here, male adult rats received a single bilateral infusion of aluminaNPs (10 or 20 µg/kg of body weight) into the hippocampal region, and their behavioral performance and neural function were assessed.

Results

The results indicated that the intra-hippocampus infusions at both doses of aluminaNPs did not cause spatial learning inability but memory deficit in the water maze task. This impairment was attributed to the effects of aluminaNP on memory consolidation phase through activation of proBDNF/RhoA pathway. Inhibition of the increased proBDNF by hippocampal infusions of p75^NTR antagonist could effectively rescue the memory impairment. Incubation of aluminaNPs exaggerated GluN2B-dependent LTD induction with no effects on LTD expression in hippocampal slices. AluminaNP could also depress the amplitude of NMDA-GluN2B EPSCs. Meanwhile, increased reactive oxygen specie production was reduced by blocking proBDNF-p75^NTR pathway in the hippocampal homogenates. Furthermore, the neuronal correlate of memory behavior was drastically weakened in the aluminaNP-infused groups. The dysfunction of synaptic and neuronal could be obviously mitigated by blocking proBDNF receptor p75^NTR, implying the involvement of proBDNF signaling in aluminaNP-impaired memory process.

Conclusions

Taken together, our findings provide the first evidence that the accumulation of aluminaNPs in the hippocampus exaggeratedly activates proBDNF signaling, which leads to neural and memory impairments.

Samhwangsasim-tang attenuates neuronal apoptosis and cognitive decline through BDNF-mediated activation of tyrosin kinase B and p75-neurotrophin receptors

BACKGROUND

Samhwangsasim-tang (SST) is a traditional medicine used to treat hypertension and arteriosclerosis. Additionally, due to the effects of its constituent herbs, SST is considered effective for memory-related disorders.

PURPOSE

We investigated the effects of SST on neuronal survival and memory in glutamate-induced hippocampal cells and in a mouse model of scopolamine-induced memory impairment.

METHODS

SST components were identified using 3D-ultra performance liquid chromatography (3D-UPLC). In vitro, we induced glutamate-induced excitotoxicity in HT22 cells after SST pretreatment. We used a cell counting kit-8 and cell cytotoxicity assay, flow cytometry, and western blotting to test the protective effects of SST on neuronal death. In vivo, C57BL/6J mice were administered with 150 and 300 mg/kg SST once daily for 7 days and then intraperitoneally injected with 1 mg/kg scopolamine for 7 days to induce cognitive impairment. We then measured cognitive behavior using a novel object recognition test (NORT) and passive avoidance test (PAT) and analyzed the histological and protein changes.

RESULTS

Our results showed that treatment with 50 and 100 μg/ml SST provided significant protection against glutamate-induced cell death. Flow cytometry and western blotting results suggested that 100 μg/ml SST treatment reduced oxidative stress and mitochondrial dysfunction. SST treatment also increased brain-derived neurotrophic factor (BDNF), its receptor, TrkB receptor, and cAMP-response element binding protein (CREB) activation while reducing the P75NTR and JNK signaling activation. Our in vivo results showed that SST administration improved cognitive impairment, similar to donepezil treatment (as a positive control), in NORT and PAT. SST and donepezil decreased neuronal cell death and apoptosis, and acetylcholine levels were increased in the scopolamine-treated hippocampus. Additionally, SST promoted CREB phosphorylation and BDNF maturation while reducing JNK and P75NTR activation; in contrast, donepezil did not alter levels of these proteins in the scopolamine-treated mouse hippocampus.

CONCLUSION

Our results suggest that SST has neuroprotective effects to attenuate neuronal cell death and oxidative stress through CREB/JNK signaling via BDNF activation. SST may regulate endogenous survival factors in the hippocampus, which may be a safe and potential clinical treatment for cognitive impairment in AD.

Insight Into the Mechanism of Exercise Preconditioning in Ischemic Stroke

Exercise preconditioning has attracted extensive attention to induce endogenous neuroprotection and has become the hotspot in neurotherapy. The training exercise is given multiple times before cerebral ischemia, effectively inducing ischemic tolerance and alleviating secondary brain damage post-stroke. Compared with other preconditioning methods, the main advantages of exercise include easy clinical operation and being readily accepted by patients. However, the specific mechanism behind exercise preconditioning to ameliorate brain injury is complex. It involves multi-pathway and multi-target regulation, including regulation of inflammatory response, oxidative stress, apoptosis inhibition, and neurogenesis promotion. The current review summarizes the recent studies on the mechanism of neuroprotection induced by exercise, providing the theoretical basis of applying exercise therapy to prevent and treat ischemic stroke. In addition, we highlight the various limitations and future challenges of translational medicine from fundamental study to clinical application.