Catalpol stimulates VEGF production via the JAK2/STAT3 pathway to improve angiogenesis in rats' stroke model

Integrated Strategies for Targeting Arteriogenesis and Angiogenesis After Stroke

The interdependence between arteriogenesis and angiogenesis is crucial for enhancing perfusion by synchronously improving leptomeningeal collaterals (LMCs) and microvascular networks after stroke. However, current approaches often focus on promoting arteriogenesis and angiogenesis separately, neglecting the potential synergistic benefits of targeting both processes simultaneously. Therefore, it is imperative to consider both arteriogenesis and angiogenesis as integral and complementary strategies for post-stroke revascularization. To gain a deeper understanding of their relationships after stroke and to facilitate the development of targeted revascularization strategies, we compared them based on their timescale, space, and pathophysiology. The temporal differences in the occurrence of arteriogenesis and angiogenesis allow them to restore blood flow at different stages after stroke. The spatial differences in the effects of arteriogenesis and angiogenesis enable them to specifically target the ischemic penumbra and core infarct region. Additionally, the endothelial cell, as the primary effector cell in their pathophysiological processes, is promising target for enhancing both. Therefore, we provide an overview of key signals that regulate endothelium-mediated arteriogenesis and angiogenesis. Finally, we summarize current therapeutic strategies that involve these signals to promote both processes after stroke, with the aim of inspiring future therapeutic advances in revascularization.

The impact of cytokines in neuroinflammation-mediated stroke

Cerebral stroke is ranked as the third most common contributor to global mortality and disability. The involvement of inflammatory mechanisms, both peripherally and within the CNS, holds significance in the pathophysiological cascades following the initiation of stroke. After the onset of acute stroke, predominantly ischemic, a subsequent phase of neuroinflammation ensues. It is a dual-effect process that not only exacerbates injury, leading to cell death, but paradoxically, it also serves a shielding role in facilitating recovery. Cytokines serve as pivotal mediators within the inflammatory cascade, actively contributing to the progression of ischemic damage. Stroke is followed by increased expression of pro-inflammatory cytokines including TNF-α, IL-1β, IL-6, etc. leading to the recruitment and stimulation of glial cells and peripheral leukocytes at the site of injury, promoting neuroinflammation. Cytokines can directly induce neuronal injury and death through various mechanisms, including excitotoxicity, oxidative stress, HPA-axis activation, secretion of matrix metalloproteinase and apoptosis. They can also amplify the inflammatory response, leading to further neuronal damage. Therapeutic strategies aimed at modulating cytokine release, immune response and cytokine signalling or activity are being explored as potential interventions to mitigate neuroinflammation and its detrimental effects in stroke. In this review, we have given a concise summary of our current knowledge of the function of various cytokines, brain inflammation and various signalling and molecular pathways including JAK/STAT3, TGF-β/Smad, MAPK, HMGB1/TLR and NF-κB modulated cytokines regulation in stroke. Therapeutic agents such as MCC950, genistein, edaravone, minocycline, etc. targeting various cytokines-associated signalling pathways have shown efficacy in preclinical and clinical trials reducing the pathophysiology of the illness were also addressed in this study.

Promotion Effect of Catalpol on Angiogenesis and Potential Mechanisms: A Research Based on Network Pharmacology

Catalpol, a natural iridoid glycoside, has potential therapeutic benefits, including anti-inflammatory and neuroprotective effects. Investigating catalpol's role in angiogenesis is critical for understanding its potential therapeutic applications, particularly in diseases where modulating angiogenesis is beneficial. This study investigates catalpol's influence on angiogenesis and its mechanisms, combining network pharmacology and in vitro experiments. The target genes corresponding to the catalpol were analyzed by SwissTargetPrediction. Then angiogenesis-related targets were acquired from databases like GeneCards. Subsequently, the Database for Annotation, Visualization and Integrated Discovery was employed for Gene Ontology and pathway analysis, while Cytoscape visualized protein interactions. The effect of catalpol on viability and angiogenesis of HUVECs was further examined using Cell Counting Kit-8 and angiogenesis assays. RT-qPCR and western blot were applied to check the expression of angiogenesis-related proteins. Totally, 312 target genes of catalpol and 823 angiogenesis-related targets were obtained with 56 common targets leading to PPI network analysis, highlighting hub genes (AKT1, EGFR, STAT3, MAPK3, and CASP3). These hub genes were mainly enriched in lipid and atherosclerosis pathway and EGFR-related pathway. The in vitro experimental results showed that catalpol achieved a concentration-dependent increase in HUVECs viability. Catalpol also promoted the migration and angiogenesis of HUVECs and up-regulated the expression of EGFR. EGFR knockdown inhibited the effect of catalpol on HUVECs. Catalpol promotes angiogenesis in HUVECs by upregulating EGFR and angiogenesis-related proteins, indicating its potential therapeutic application in vascular-related diseases.

The Janus face of HIF-1α in ischemic stroke and the possible associated pathways

Stroke is the most devastating disease, causing paralysis and eventually death. Many clinical and experimental trials have been done in search of a new safe and efficient medicine; nevertheless, scientists have yet to discover successful remedies that are also free of adverse effects. This is owing to the variability in intensity, localization, medication routes, and each patient's immune system reaction. HIF-1α represents the modern tool employed to treat stroke diseases due to its functions: downstream genes such as glucose metabolism, angiogenesis, erythropoiesis, and cell survival. Its role can be achieved via two downstream EPO and VEGF strongly related to apoptosis and antioxidant processes. Recently, scientists paid more attention to drugs dealing with the HIF-1 pathway. This review focuses on medicines used for ischemia treatment and their potential HIF-1α pathways. Furthermore, we discussed the interaction between HIF-1α and other biological pathways such as oxidative stress; however, a spotlight has been focused on certain potential signalling contributed to the HIF-1α pathway. HIF-1α is an essential regulator of oxygen balance within cells which affects and controls the expression of thousands of genes related to sustaining homeostasis as oxygen levels fluctuate. HIF-1α's role in ischemic stroke strongly depends on the duration and severity of brain damage after onset. HIF-1α remains difficult to investigate, particularly in ischemic stroke, due to alterations in the acute and chronic phases of the disease, as well as discrepancies between the penumbra and ischemic core. This review emphasizes these contrasts and analyzes the future of this intriguing and demanding field.

Microalgae Octapeptide IIAVEAGC Alleviates Oxidative Stress and Neurotoxicity in 6-OHDA-Induced SH-SY5Y Cells by Regulating the Nrf2/HO-1and Jak2/Stat3 Pathways

Neurodegenerative diseases are characterized by the progressive loss of selectively vulnerable populations of neurons, and many factors are involved in its causes. Neurotoxicity and oxidative stress, are the main related factors. The octapeptide Ile-Ile-Ala-Val-Glu-Ala-Gly-Cys (IEC) was identified from the microalgae Isochrysis zhanjiangensis and exhibited potential anti-oxidative stress activity. In this study, the stability of α-synaptic protein binding to IEC was modeled using molecular dynamics, and the results indicated binding stabilization within 60 ns. Oxidative stress in neurons is the major cause of α-synaptic protein congestion. Therefore, we next evaluated the protective effects of IEC against oxidative stress and neurotoxicity in 6-ohdainduced Parkinson's disease (PD) model SH-SY5Y cells in vitro. In oxidative stress, IEC appeared to increase the expression of the antioxidant enzymes HO-1 and GPX through the antioxidant pathway of Nrf2, and molecular docking of IEC with Nrf2 and GPX could generate hydrogen bonds. Regarding apoptosis, IEC protected cells by increasing the Bcl-2/Bax ratio, inhibiting the caspase cascade, acting on p53, and modulating the Jak2/Stat3 pathway. The results indicated that IEC exerted neuroprotective effects through the inhibition of α-synaptic protein aggregation and antioxidant activity. Therefore, microalgal peptides have promising applications in the prevention and treatment of neurodegenerative diseases.

A study on the mechanism of Beclin-1 m6A modification mediated by catalpol in protection against neuronal injury and autophagy following cerebral ischemia

OBJECTIVE

Catalpol (CAT) has various pharmacological activities and plays a protective role in cerebral ischemia. It has been reported that CAT played a protective role in cerebral ischemia by upregulaing NRF1 expression. Bioinformatics analysis reveals that NRF1 can be used as a transcription factor to bind to the histone acetyltransferase KAT2A. However, the role of KAT2A in cerebral ischemia remains to be studied. Therefore, we aimed to investigate the role of CAT in cerebral ischemia and its related mechanism.

METHODS

In vitro, a cell model of oxygen and glucose deprivation/reperfusion (OGD/R) was constructed, followed by evaluation of neuronal injury and the expression of METTL3, Beclin-1, NRF1, and KAT2A. In vivo, a MCAO rat model was prepared by means of focal cerebral ischemia, followed by assessment of neurological deficit and brain injury in MCAO rats. Neuronal autophagy was evaluated by observation of autophagosomes in neurons or brain tissues by TEM and detection of the expression of LC3 and p62.

RESULTS

In vivo, CAT reduced the neurological function deficit and infarct volume, inhibited neuronal apoptosis in the cerebral cortex, and significantly improved neuronal injury and excessive autophagy in MCAO rats. In vitro, CAT restored OGD/R-inhibited cell viability, inhibited cell apoptosis, LDH release, and neuronal autophagy. Mechanistically, CAT upregulated NRF1, NRF1 activated METTL3 via KAT2A transcription, and METTL3 inhibited Beclin-1 via m6A modification.

CONCLUSION

CAT activated the NRF1/KAT2A/METTL3 axis and downregulated Beclin-1 expression, thus relieving neuronal injury and excessive autophagy after cerebral ischemia.

Shengmaisan combined with Liuwei Dihuang Decoction alleviates chronic intermittent hypoxia-induced cognitive impairment by activating the EPO/EPOR/JAK2 signaling pathway

Chronic intermittent hypoxia (CIH), a principal pathophysiological aspect of obstructive sleep apnea (OSA), is associated with cognitive deficits. Clinical evidence suggests that a combination of Shengmaisan and Liuwei Dihuang Decoctions (SMS-LD) can enhance cognitive function by nourishing yin and strengthening the kidneys. This study aimed to assess the efficacy and underlying mechanisms of SMS-LD in addressing cognitive impairments induced by CIH. We exposed C57BL/6N mice to CIH for five weeks (20%-5% O2, 5 min/cycle, 8 h/day) and administered SMS-LD intragastrically (15.0 or 30 g·kg-1·day) 30 min before each CIH session. Additionally, AG490, a JJanus kinase 2 (JAK2) inhibitor, was administered via intracerebroventricular injection. Cognitive function was evaluated using the Morris water maze, while synaptic and mitochondrial structures were examined by transmission electron microscopy. Oxidative stress levels were determined using DHE staining, and the activation of the erythropoietin (ER)/ER receptor (EPOR)/JAK2 signaling pathway was analyzed through immunohistochemistry and Western blotting. To further investigate molecular mechanisms, HT22 cells were treated in vitro with either SMS-LD medicated serum alone or in combination with AG490 and then exposed to CIH for 48 h. Our results indicate that SMS-LD significantly mitigated CIH-induced cognitive impairments in mice. Specifically, SMS-LD treatment enhanced dendritic spine density, ameliorated mitochondrial dysfunction, reduced oxidative stress, and activated the EPO/EPOR/JAK2 signaling pathway. Conversely, AG490 negated SMS-LD's neuroprotective and cognitive improvement effects under CIH conditions. These findings suggest that SMS-LD's beneficial impact on cognitive impairment and synaptic and mitochondrial integrity under CIH conditions may predominantly be attributed to the activation of the EPO/EPOR/JAK2 signaling pathway.

Navigating neurological disorders: harnessing the power of natural compounds for innovative therapeutic breakthroughs

Novel treatments are needed as neurological issues become more frequent worldwide. According to the report, plants, oceans, microorganisms, and animals contain interesting drug discovery compounds. Alzheimer's, Parkinson's, and stroke reviews emphasize neurological disorders' complexity and natural substances' safety. Learn about marine-derived and herbal substances' neuroprotective characteristics and applications. Molecular pathways show these substances' neurological healing effects. This article discusses clinical usage of Bryostatin-1, Fucoidan, Icariin, Salvianolic acid, Curcumin, Resveratrol, etc. Their potential benefits for asthma and Alzheimer's disease are complex. Although limited, the study promotes rigorous scientific research and collaboration between traditional and alternative medical practitioners. Unexplored natural compounds, quality control, well-structured clinical trials, and interdisciplinary collaboration should guide future study. Developing and employing natural chemicals to treat neurological illnesses requires ethical sourcing, sustainability, and public awareness. This detailed analysis covers natural chemicals' current state, challenges, and opportunities in neurological disorder treatment. See also the graphical abstract(Fig. 1).

Study on the Neuroprotective Effects of Eight Iridoid Components Using Cell Metabolomics

Iridoid components have been reported to have significant neuroprotective effects. However, it is not yet clear whether the efficacy and mechanisms of iridoid components with similar structures are also similar. This study aimed to compare the neuroprotective effects and mechanisms of eight iridoid components (catalpol (CAT), genipin (GE), geniposide (GEN), geniposidic acid (GPA), aucubin (AU), ajugol (AJU), rehmannioside C (RC), and rehmannioside D (RD)) based on corticosterone (CORT)-induced injury in PC12 cells. PC12 cells were randomly divided into a normal control group (NC), model group (M), positive drug group (FLX), and eight iridoid administration groups. Firstly, PC12 cells were induced with CORT to simulate neuronal injury. Then, the MTT method and flow cytometry were applied to evaluate the protective effects of eight iridoid components on PC12 cell damage. Thirdly, a cell metabolomics study based on ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q/TOF-MS) was performed to explore changes in relevant biomarkers and metabolic pathways following the intervention of administration. The MTT assay and flow cytometry analysis showed that the eight iridoid components can improve cell viability, inhibit cell apoptosis, reduce intracellular ROS levels, and elevate MMP levels. In the PCA score plots, the sample points of the treatment groups showed a trend towards approaching the NC group. Among them, AU, AJU, and RC had a weaker effect. There were 38 metabolites (19 metabolites each in positive and negative ion modes, respectively) identified as potential biomarkers during the experiment, among which 23 metabolites were common biomarkers of the eight iridoid groups. Pathway enrichment analysis revealed that the eight iridoid components regulated the metabolism mainly in relation to D-glutamine and D-glutamate metabolism, arginine biosynthesis, the TCA cycle, purine metabolism, and glutathione metabolism. In conclusion, the eight iridoid components could reverse an imbalanced metabolic state by regulating amino acid neurotransmitters, interfering with amino acid metabolism and energy metabolism, and harmonizing the level of oxidized substances to exhibit neuroprotective effects.

Catalpol rescues LPS-induced cognitive impairment via inhibition of NF-Κb-regulated neuroinflammation and up-regulation of TrkB-mediated BDNF secretion in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Septic-associated encephalopathy (SAE) is a key manifestation of sepsis. Nevertheless, specific treatment for SAE is still lacking. Catalpol is an active component derived from Rehmanniae Radix, and has been demonstrated to be a potential neuroprotective agent. However, its effect on SAE still needs to be fully explored.

AIM

To address the benefits of catalpol on post-sepsis cognitive deterioration and related mechanisms.

MATERIALS AND METHODS

Novel object recognition test, temporal order task, histopathology, and immunochemistry were applied to address the benefits of catalpol on LPS-triggered post-sepsis cognitive decline in mice. Xuebijing injection (10 ml/kg) has been utilized as a positive control in the above animal studies. After treatment, the catalpol content in the hippocampus was determined using LC-MS/MS. Finally, the mechanisms of catalpol were further assessed in BV2 and PC12 cells in vitro using Western blot, RT-PCR, flow cytometry, molecular docking tests, thermal shift assay, transmission electron microscopy, and immunofluorescence analysis.

RESULTS

Behavior tests showed that catalpol therapy could lessen the cognitive impairment induced by LPS damage. HE, Nissl, immunofluorescence, transmission electron microscopy, and Golgi staining further reflected that catalpol treatment could restore lymphocyte infiltration, blood-brain barrier (BBB) degradation, and the decreasing complexity of dendritic trees. According to LC-MS/MS analysis, catalpol had a 136 ng/mg concentration in the hippocampus. In vitro investigation showed that catalpol could inhibit microglia M1 polarization via blocking NF-κB phosphorylation, translocation and then reducing inflammatory cytokine release in BV2 microglia cells. Brain-derived neurotrophic factor (BDNF) release up-regulation and TrkB pathway activation were observed in the catalpol treatment group in vivo and in vitro. The effect of catalpol on enhancing BDNF expression was inhibited by the specific inhibitor of TrkB (GNF-5837) in PC12 cells. Further molecular docking tests showed that catalpol formed weak hydrophobic bonds with TrkB. Besides, thermal shift assay also reflected that catalpol incubation caused a considerable change in the melting temperature of the TrkB.

CONCLUSION

Catalpol alleviates LPS-triggered post-sepsis cognitive impairment by reversing neuroinflammation via blocking the NF-κB pathway, up-regulating neurotrophic factors via the activation of TrkB pathway, and preserving BBB integrity.

Understanding mechanistic aspect of the therapeutic role of herbal agents on neuroplasticity in cerebral ischemic-reperfusion injury

ETHNOPHARMACOLOGICAL RELEVANCE

Stroke is one of the leading causes of death and disability. The only FDA-approved therapy for treating stroke is tissue plasminogen activator (tPA), exhibiting a short therapeutic window. Due to this reason, only a small number of patients can be benefitted in this critical period. In addition, the use of endovascular interventions may reverse vessel occlusion more effectively and thus help further improve outcomes in experimental stroke. During recovery of blood flow after ischemia, patients experience cognitive, behavioral, affective, emotional, and electrophysiological changes. Therefore, it became the need for an hour to discover a novel strategy for managing stroke. The drug discovery process has focused on developing herbal medicines with neuroprotective effects via modulating neuroplasticity.

AIM OF THE STUDY

We gather and highlight the most essential traditional understanding of therapeutic plants and their efficacy in cerebral ischemia-reperfusion injury. In addition, we provide a concise summary and explanation of herbal drugs and their role in improving neuroplasticity. We review the pharmacological activity of polyherbal formulations produced from some of the most frequently referenced botanicals for the treatment of cerebral ischemia damage.

MATERIALS AND METHODS

A systematic literature review of bentham, scopus, pubmed, medline, and embase (elsevier) databases was carried out with the help of the keywords like neuroplasticity, herbal drugs, neural progenitor cells, neuroprotection, stem cells. The review was conducted using the above keywords to understand the therapeutic and mechanistic role of herbal neuroprotective agents on neuroplasticity in cerebral ischemic-reperfusion injury.

RESULTS

Neuroplasticity emerged as an alternative to improve recovery and management after cerebral ischemic reperfusion injury. Neuroplasticity is a physiological process throughout one's life in response to any stimuli and environment. Traditional herbal medicines have been established as an adjuvant to stroke therapy since they were used from ancient times and provided promising effects as an adjuvant to experimental stroke. The plants and phytochemicals such as Curcuma longa L., Moringa oliefera Lam, Panax ginseng C.A. Mey., and Rehmannia glutinosa (Gaertn.) DC., etc., have shown promising effects in improving neuroplasticity after experimental stroke. Such effects occur by modulation of various molecular signalling pathways, including PI3K/Akt, BDNF/CREB, JAK/STAT, HIF-1α/VEGF, etc. CONCLUSIONS: Here, we gave a perspective on plant species that have shown neuroprotective effects and can show promising results in promoting neuroplasticity with specific targets after cerebral ischemic reperfusion injury. In this review, we provide the complete detail of studies conducted on the role of herbal drugs in improving neuroplasticity and the signaling pathway involved in the recovery and management of experimental stroke.

Protective effects of catalpol on cardio-cerebrovascular diseases: A comprehensive review

Catalpol, an iridoid glucoside isolated from Rehmannia glutinosa, has gained attention due to its potential use in treating cardio-cerebrovascular diseases (CVDs). This extensive review delves into recent studies on catalpol's protective properties in relation to various CVDs, such as atherosclerosis, myocardial ischemia, infarction, cardiac hypertrophy, and heart failure. The review also explores the compound's anti-oxidant, anti-inflammatory, and anti-apoptotic characteristics, emphasizing the role of vital signaling pathways, including PGC-1α/TERT, PI3K/Akt, AMPK, Nrf2/HO-1, estrogen receptor (ER), Nox4/NF-κB, and GRP78/PERK. The article discusses emerging findings on catalpol's ability to alleviate diabetic cardiovascular complications, thrombosis, and other cardiovascular-related conditions. Although clinical studies specifically addressing catalpol's impact on CVDs are scarce, the compound's established safety and well-tolerated nature suggest that it could be a valuable treatment alternative for CVD patients. Further investigation into catalpol and related iridoid derivatives may unveil new opportunities for devising natural and efficacious CVD therapies.

Purification and structural analysis of a novel polysaccharide from Rehmannia Radix Praeparata

In this paper, the purification, structure, and antioxidant activity of Rehmannia Radix Praeparata polysaccharide (RRPP) were studied. The RRPP was separated using DEAE-52 cellulose and Sephadex G-100. The RRPP consisted of xylose, glucose, rhamnose, galactose, and mannose in ratios of 10.64:5.58:3.52:1.39:1.0. No protein was detected in the RRPP fraction, and the molecular weight of RRPP was about 1.75 × 106  Da. The basic skeleton information was obtained using periodic acid oxidation-Smith degradation, and RRPP contained 1→, 1 → 2, 1 → 3, 1 → 4, 1 → 2,6, 1 → 4,6 or 1 → 6, 1 → 2,3, 1 → 2,3,4, and other glycosidic bonds. Fourier transform infrared spectroscopy also showed that RRPP has both α- and β-glycosidic bonds. The in vitro antioxidant activity test showed that RRPP could potentialize scavenging effect on ABTS+· and its scavenging rate was 91.3%.

Biomarkers based on multiplatform comprehensive analysis: A systematic analysis of Geng-Nian-Shu in perimenopausal syndrome

Although Geng-Nian-Shu has been shown to be clinically effective in perimenopausal syndrome, its active components and mechanism have not yet been elucidated. To demonstrate the mechanism-based biomarkers of Geng-Nian-Shu in treating perimenopausal syndrome, a total of 135 chemical constituents including 52 prototype blood constituents were identified via high-performance liquid chromatography-quadrupole-time of flight/mass spectrometry. Then, network pharmacology showed significant enrichment for the PhosphoInositide-3 Kinase/Akt pathway, suggesting that it may be the main regulatory pathway for the Geng-Nian-Shu treatment of the perimenopausal syndrome. Subsequently, multivariate analysis was performed between the Geng-Nian-Shu sham-treated and Geng-Nian-Shu ovariectomy-treated groups and further screened out 18 prototype blood constituents by correlation analysis with plasma estrogen levels to identify potential biomarkers associated with Geng-Nian-Shu treat the ovariectomy-induced perimenopausal syndrome. Finally, the results of pharmacological experimental verification and Pearson correlation analysis indicated that catalpol, ligustilide, paeoniflorin, and gallic acid were selected as biomarkers of Geng-Nian-Shu which were strongly and positively correlated with PhosphoInositide-3 Kinase/Akt signaling pathway. In this study, based on high-performance liquid chromatography-quadrupole-time of flight/mass spectrometry combined with pharmacodynamics, network pharmacology, pharmacology, and other disciplines, we explored the effects and mechanisms of Geng-Nian-Shu in the treatment of perimenopausal syndrome at multiple levels. Using multiplatform technology to investigate the role of Geng-Nian-Shu represents a new strategy for the selection and verification of biomarkers of Geng-Nian-Shu and provides a basis for further development and utilization of Geng-Nian-Shu.

A comprehensive review of stroke-related signaling pathways and treatment in western medicine and traditional Chinese medicine

This review provides insight into the complex network of signaling pathways and mechanisms involved in stroke pathophysiology. It summarizes the historical progress of stroke-related signaling pathways, identifying potential interactions between them and emphasizing that stroke is a complex network disease. Of particular interest are the Hippo signaling pathway and ferroptosis signaling pathway, which remain understudied areas of research, and are therefore a focus of the review. The involvement of multiple signaling pathways, including Sonic Hedgehog (SHH), nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE), hypoxia-inducible factor-1α (HIF-1α), PI3K/AKT, JAK/STAT, and AMPK in pathophysiological mechanisms such as oxidative stress and apoptosis, highlights the complexity of stroke. The review also delves into the details of traditional Chinese medicine (TCM) therapies such as Rehmanniae and Astragalus, providing an analysis of the recent status of western medicine in the treatment of stroke and the advantages and disadvantages of TCM and western medicine in stroke treatment. The review proposes that since stroke is a network disease, TCM has the potential and advantages of a multi-target and multi-pathway mechanism of action in the treatment of stroke. Therefore, it is suggested that future research should explore more treasures of TCM and develop new therapies from the perspective of stroke as a network disease.

Phosphorylation of STAT3 at Tyr705 contributes to TFEB-mediated autophagy-lysosomal pathway dysfunction and leads to ischemic injury in rats

We previously reported that permanent ischemia induces marked dysfunction of the autophagy-lysosomal pathway (ALP) in rats, which is possibly mediated by the transcription factor EB (TFEB). However, it is still unclear whether signal transducer and activator of transcription 3 (STAT3) is responsible for the TFEB-mediated dysfunction of ALP in ischemic stroke. In the present study, we used AAV-mediated genetic knockdown and pharmacological blockade of p-STAT3 to investigate the role of p-STAT3 in regulating TFEB-mediated ALP dysfunction in rats subjected to permanent middle cerebral occlusion (pMCAO). The results showed that the level of p-STAT3 (Tyr705) in the rat cortex increased at 24 h after pMCAO and subsequently led to lysosomal membrane permeabilization (LMP) and ALP dysfunction. These effects can be alleviated by inhibitors of p-STAT3 (Tyr705) or by STAT3 knockdown. Additionally, STAT3 knockdown significantly increased the nuclear translocation of TFEB and the transcription of TFEB-targeted genes. Notably, TFEB knockdown markedly reversed STAT3 knockdown-mediated improvement in ALP function after pMCAO. This is the first study to show that the contribution of p-STAT3 (Tyr705) to ALP dysfunction may be partly associated with its inhibitory effect on TFEB transcriptional activity, which further leads to ischemic injury in rats.

Network pharmacology to explore the mechanism of scutellarin in the treatment of brain ischaemia and experimental verification of JAK2/STAT3 signalling pathway

Scutellarin is used to treat brain ischaemia. However, its underlying mechanism of action remains unclear. This study aimed to elucidate the potential mechanism of action of scutellarin in brain ischaemia through network pharmacology and experimental verification. The JAK2/STAT3 signalling pathway was identified and experimentally verified. Expression of JAK2/STAT3 signalling related proteins in TNC-1 astrocytes with BV-2 microglia-conditioned medium (CM), CM + lipopolysaccharide (LPS) (CM + L), and CM pretreated with scutellarin + LPS (CM + SL) was analysed by Western Blot and immunofluorescence staining. Expression levels of JAK2, p-JAK2, STAT3, and p-STAT3 were evaluated in astrocytes pre-treated with AG490. Middle cerebral artery occlusion (MCAO) in rats was performed in different experimental groups to detect expression of the above biomarkers. Network pharmacology suggested that the JAK2/STAT3 signalling pathway is one of the mechanisms by which scutellarin mitigates cerebral ischaemic damage. In TNC-1 astrocytes, p-JAK2 and p-STAT3 expression were significantly up-regulated in the CM + L group. Scutellarin promoted the up-regulation of various markers and AG490 neutralised the effect of scutellarin. In vivo, up-regulation of p-JAK2 and p-STAT3 after ischaemia is known. These results are consistent with previous reports. Scutellarin further enhanced this upregulation at 1, 3, and 7 d after MCAO. Scutellarin exerts its therapeutic effects on cerebral ischaemia by activating the astrocyte JAK2/STAT3 signalling, which provides a firm experimental basis for its clinical application.

Insight into the transcription factors regulating Ischemic Stroke and Glioma in Response to Shared Stimuli

Cerebral ischemic stroke and glioma are the two leading causes of patient mortality globally. Despite physiological variations, 1 in 10 people who have an ischemic stroke go on to develop brain cancer, most notably gliomas. In addition, glioma treatments have also been shown to increase the risk of ischemic strokes. Stroke occurs more frequently in cancer patients than in the general population, according to traditional literature. Unbelievably, these events share multiple pathways, but the precise mechanism underlying their co-occurrence remains unknown. Transcription factors (TFs), the main components of gene expression programmes, finally determine the fate of cells and homeostasis. Both ischemic stroke and glioma exhibit aberrant expression of a large number of TFs, which are strongly linked to the pathophysiology and progression of both diseases. The precise genomic binding locations of TFs and how TF binding ultimately relates to transcriptional regulation remain elusive despite a strong interest in understanding how TFs regulate gene expression in both stroke and glioma. As a result, the importance of continuing efforts to understand TF-mediated gene regulation is highlighted in this review, along with some of the primary shared events in stroke and glioma.

Effect of Huangdisan grain on improving cognitive impairment in VD rats and its mechanism in immune inflammatory response

BACKGROUND

Vascular dementia (VD) is the second most common type of dementia after Alzheimer's disease (AD). Although the incidence rate is very high, there is no definitive treatment for VD. And it has serious impact on the quality of life of VD patients. In recent years, more and more studies about the clinical efficacy and pharmacological effects of traditional Chinese medicine (TCM) in the treatment of VD have been conducted. And Huangdisan grain has been used to treat VD patients with a good curative effect in clinic.

OBJECTIVE

This study was designed to investigate the effect of Huangdisan grain on the inflammatory response and cognitive function of VD rats modeled by bilateral common carotid artery occlusion (BCCAO), that aimed to improve the treatment methods for VD.

METHODS

8-week-old healthy SPF male Wistar rats (280 ± 20 g) were randomly divided into the normal group (Gn, n = 10), sham operated group (Gs, n = 10), and operated group (Go, n = 35). The VD rat models in Go group were established by BCCAO. 8 weeks after surgery, the operated rats were screened by the hidden platform trail of Morris Water Maze (MWM), and the rats with cognitive dysfunction were further randomly divided into the impaired group (Gi, n = 10) and TCM group (Gm, n = 10). The VD rats in Gm group were given the intragastric administration of Huangdisan grain decoction once a day for 8 weeks, and the other groups were given intragastric administration of normal saline. Then the cognitive ability of rats in each group was detected by the MWM Test. The lymphocyte subsets in peripheral blood and hippocampus of rats were measured by flow cytometry. The levels of cytokines (IL-1β, IL-2, IL-4, IL-10, TNF-α, INF-γ, MIP-2, COX-2, iNOS) in peripheral blood and hippocampus were measured by ELISA (enzyme linked immunosorbent assay). The number of Iba-1⁺ CD68⁺ co-positive cells in the CA1 region of hippocampus was measured by immunofluorescence.

RESULTS

Compared with the Gn group, the escape latencies of the Gi group were prolonged (P < 0.01), the time spent in the former platform quadrant was shortened (P < 0.01), and the number of times of crossing over the former platform location was reduced (P < 0.05). But compared with the Gi group, the escape latencies of Gm group were shortened (P < 0.01), the time spent in the former platform quadrant was prolonged (P < 0.05), and the number of times of crossing over the former platform location was increased (P < 0.05). The number of Iba-1⁺ CD68⁺ co-positive cells in the CA1 region of hippocampus of VD rats in Gi group was increased (P < 0.01) compared with the Gn group. And the proportions of T Cells, CD4⁺ T Cells, CD8⁺ T Cells in the hippocampus were increased (P < 0.01). The level of pro-inflammatory cytokines in the hippocampus was increased significantly, such as IL-1β (P < 0.01), IL-2 (P < 0.01), TNF-α (P < 0.05), IFN-γ (P < 0.01), COX-2 (P < 0.01), MIP-2 (P < 0.01) and iNOS (P < 0.05). And the level of IL-10 (P < 0.01), a kind of anti-inflammatory cytokine, was decreased. The proportions of T Cells (P < 0.05), CD4⁺ T Cells (P < 0.01) and NK Cells (P < 0.05) in the peripheral blood of the VD rats in Gi group were decreased, and the level of IL-1β, IL-2, TNF-α, IFN-γ, COX-2, MIP-2 and iNOS was increased significantly (P < 0.01) compared with the Gn group. Meanwhile, the level of IL-4 and IL-10 was decreased (P < 0.01). Huangdisan grain could reduce the number of Iba-1⁺ CD68⁺ co-positive cells in the CA1 region of hippocampus (P < 0.01), decrease the proportions of T Cells, CD4⁺ T Cells, CD8⁺ T Cells and the level of IL-1β, MIP-2 in hippocampus (P < 0.01) of VD rats. Moreover, it could rise the proportion of NK Cells (P < 0.01) and the level of IL-4 (P < 0.05), IL-10 (P < 0.05), and decrease the level of IL-1β (P < 0.01), IL-2 (P < 0.05), TNF-α (P < 0.01), IFN-γ (P < 0.01), COX-2 (P < 0.01) and MIP-2 (P < 0.01) in peripheral blood of VD rats.

CONCLUSION

This study indicated that Huangdisan grain could decrease the activation of microglia/macrophages, regulate the proportions of lymphocyte subsets and the level of cytokines, which could adjust the immunologic abnormalities of VD rats, and ultimately improve cognitive function.

The role of traditional herbal medicine for ischemic stroke: from bench to clinic-A critical review

BACKGROUND

Ischemic stroke (IS) is a leading cause of death and severe long-term disability worldwide. Over the past few decades, considerable progress has been made in anti-ischemic therapies. However, IS remains a tremendous challenge, with favourable clinical outcomes being generally difficult to achieve from candidate drugs in preclinical phase testing. Traditional herbal medicine (THM) has been used to treat stroke for over 2,000 years in China. In modern times, THM as an alternative and complementary therapy have been prescribed in other Asian countries and have gained increasing attention for their therapeutic effects. These millennia of clinical experience allow THM to be a promising avenue for improving clinical efficacy and accelerating drug discovery.

PURPOSE

To summarise the clinical evidence and potential mechanisms of THMs in IS.

METHODS

A comprehensive literature search was conducted in seven electronic databases, including PubMed, EMBASE, the Cochrane Central Register of Controlled Trials, the Chinese National Knowledge Infrastructure, the VIP Information Database, the Chinese Biomedical Literature Database, and the Wanfang Database, from inception to 17 June 2022 to examine the efficacy and safety of THM for IS, and to investigate experimental studies regarding potential mechanisms.

RESULTS

THM is widely prescribed for IS alone or as adjuvant therapy. In clinical trials, THM is generally administered within 72 h of stroke onset and are continuously prescribed for over 3 months. Compared with Western medicine (WM), THM combined with routine WM can significantly improve neurological function defect scores, promote clinical total effective rate, and accelerate the recovery time of stroke with fewer adverse effects (AEs). These effects can be attributed to multiple mechanisms, mainly anti-inflammation, antioxidative stress, anti-apoptosis, brain blood barrier (BBB) modulation, inhibition of platelet activation and thrombus formation, and promotion of neurogenesis and angiogenesis.

CONCLUSIONS

THM may be a promising candidate for IS management to guide clinical applications and as a reference for drug development.

FL-DTD: an integrated pipeline to predict the drug interacting targets by feedback loop-based network analysis

Drug target discovery is an essential step to reveal the mechanism of action (MoA) underlying drug therapeutic effects and/or side effects. Most of the approaches are usually labor-intensive while unable to identify the tissue-specific interacting targets, especially the targets with weaker drug binding affinity. In this work, we proposed an integrated pipeline, FL-DTD, to predict the drug interacting targets of novel compounds in a tissue-specific manner. This method was built based on a hypothesis that cells under a status of homeostasis would take responses to drug perturbation by activating feedback loops. Therefore, the drug interacting targets can be predicted by analyzing the network responses after drug perturbation. We evaluated this method using the expression data of estrogen stimulation, gene manipulation and drug perturbation and validated its good performance to identify the annotated drug targets. Using STAT3 as a target protein, we applied this method to drug perturbation data of 500 natural compounds and predicted five compounds with STAT3 interacting activities. Experimental assay validated the STAT3-interacting activities of four compounds. Overall, our evaluation suggests that FL-DTD predicts the drug interacting targets with good accuracy and can be used for drug target discovery.

The Signaling Pathways and Targets of Natural Compounds from Traditional Chinese Medicine in Treating Ischemic Stroke

Ischemic stroke (IS) is a common neurological disorder associated with high disability rates and mortality rates. At present, recombinant tissue plasminogen activator (r-tPA) is the only US(FDA)-approved drug for IS. However, due to the narrow therapeutic window and risk of intracerebral hemorrhage, r-tPA is currently used in less than 5% of stroke patients. Natural compounds have been widely used in the treatment of IS in China and have a wide range of therapeutic effects on IS by regulating multiple targets and signaling pathways. The keywords "ischemia stroke, traditional Chinese Medicine, Chinese herbal medicine, natural compounds" were used to search the relevant literature in PubMed and other databases over the past five years. The results showed that JAK/STAT, NF-κB, MAPK, Notch, Nrf2, and PI3K/Akt are the key pathways, and SIRT1, MMP9, TLR4, HIF-α are the key targets for the natural compounds from traditional Chinese medicine in treating IS. This study aims to update and summarize the signaling pathways and targets of natural compounds in the treatment of IS, and provide a base of information for the future development of effective treatments for IS.

A systematic review on botany, processing, application, phytochemistry and pharmacological action of Radix Rehmnniae

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Rehmanniae (RR) is the tuber root of Rehmannia glutionsa Libosch, which was firstly recorded in Shennong's Classic of Materia Medica (⟪⟫). RR is a non-toxic and wide used traditional Chinese medicine. RR has the effect of clearing heat, generating essence, cooling blood, stopping bleeding, nourishing yin and blood, and filling marrow. It is used in clinic in the form of processed decoction pieces, including Dry Radix Rehmnniae (DRR) and Rehmanniae Radix Praeparata (RRP). The application of RR in traditional Chinese medicine (TCM) prescriptions can treat various diseases, such as anemia, irregular menstruation, deficiency of liver yin, renal failure and so on.

AIM OF REVIEW

This paper aims to provide a comprehensive and productive review of RR, which mainly contains botanical characteristics, processing methods, traditional application, chemical composition, quality control and pharmacological action.

MATERIALS AND METHODS

Literature search was conducted through the Web of Science, Baidu Scholar, ScienceDirect, PubMed, CNKI, and WanFang DATA using the keywords "Radix Rehmnniae", "Rehmanniae Radix Praeparata", "processing", "clinical application", "chemical composition", "quality control", and "pharmacological action". In addition, information was collected from relevant textbooks, reviews, and documents.

RESULTS

RR is a traditional Chinese herbal medicine with clinical value and rich resources. More than 100 components have been isolated and identified from RR. It has multiple pharmacological actions, such as hemostasis, antioxidation, anti-osteoporosis, lowering blood sugar, improving renal function, anti-inflammation, protecting neuronal function, antidepression and anti-anxiety. DRR and RRP are two different processed products of RR. After processing, there are great changes in property, taste, efficacy, clinical application, chemical composition and pharmacological action. At present, identifying chemical constituents of RR and its medicinal value has been deeply studied. However, there is a lack of research on the reasons for the differences in pharmacological effects between DRR and RRP. The reasons for these differences need to be further verified. Catalpol, the active component of RR, has been studied extensively in the literature, but the pharmacological effects of catalpol cannot represent the pharmacological effects of the whole RR. In the future, effective components such as rehmannioside D, polysaccharide, total glycosides, and effective parts in RR need to be further studied and developed. The pharmacodynamic material basis and mechanism of RR need to be further discussed. The scientific connotation and processing methods of RRP need to be studied and standardized.

Protective effect of baicalin against arsenic trioxide-induced acute hepatic injury in mice through JAK2/STAT3 signaling pathway

Baicalin (BA) is a kind of flavonoid that is isolated from Scutellaria baicalensis Georgi, which has been verified to have hepatoprotective effects in some diseases. However, the role of BA in acute hepatic injury induced by arsenic trioxide (ATO) remains unclear. The aim of this study was to investigate the protective action of BA on acute hepatic injury induced by ATO and to probe its possible mechanism. Mice were pretreated with BA (50, 100 mg/kg) by gavage. After 7 h, ATO (7.5 mg/kg) was injected intraperitoneally to induce liver injury. After 7 days of treatment, serum and hepatic specimens were collected and assayed to evaluate the hepatoprotective effect of BA. Pathological sections and the liver function index indicated that ATO caused significant liver injury. The fluorescence of reactive oxygen species and oxidative stress indicators showed that ATO also increased oxidative stress. The inflammatory markers in ATO-induced mice also increased significantly. Staining of the terminal deoxynucleotidyl transferase dUTP nick end labeling and apoptotic factor assay showed that apoptosis increased. However, with BA pretreatment, these changes were significantly weakened. In addition, BA treatment promoted the expression of proteins related to the JAK2/STAT3 signaling pathway. The results suggest that BA can ameliorate acute ATO-induced hepatic injury in mice, which is related to the inhibition of oxidative stress, thereby reducing inflammation and apoptosis. The mechanism of this protection is potentially related to the JAK2/STAT3 signaling pathway.

The Salutary Effects of Catalpol on Diesel Exhaust Particles-Induced Thrombogenic Changes and Cardiac Oxidative Stress, Inflammation and Apoptosis

Inhaled particulate air pollution exerts pulmonary inflammation and cardiovascular toxicity through secondary systemic effects due to oxidative stress and inflammation. Catalpol, an iridiod glucoside, extracted from the roots of Rehmannia glutinosa Libosch, has been reported to possess anti-inflammatory and antioxidant properties. Yet, the potential ameliorative effects of catalpol on particulate air pollution-induced cardiovascular toxicity, has not been studied so far. Hence, we evaluated the possible mitigating mechanism of catalpol (5 mg/kg) which was administered to mice by intraperitoneal injection one hour before the intratracheal (i.t.) administration of a relevant type of pollutant particle, viz. diesel exhaust particles (DEPs, 30 µg/mouse). Twenty-four hours after the lung deposition of DEPs, several cardiovascular endpoints were evaluated. DEPs caused a significant shortening of the thrombotic occlusion time in pial microvessels in vivo, induced platelet aggregation in vitro, and reduced the prothrombin time and the activated partial thromboplastin time. All these actions were effectively mitigated by catalpol pretreatment. Likewise, catalpol inhibited the increase of the plasma concentration of C-reactive proteins, fibrinogen, plasminogen activator inhibitor-1 and P- and E-selectins, induced by DEPs. Moreover, in heart tissue, catalpol inhibited the increase of markers of oxidative (lipid peroxidation and superoxide dismutase) and nitrosative (nitric oxide) stress, and inflammation (tumor necrosis factor α, interleukin (IL)-6 and IL-1β) triggered by lung exposure to DEPs. Exposure to DEPs also caused heart DNA damage and increased the levels of cytochrome C and cleaved caspase, and these effects were significantly diminished by the catalpol pretreatment. Moreover, catalpol significantly reduced the DEPs-induced increase of the nuclear factor κB (NFκB) in the heart. In conclusion, catalpol significantly ameliorated DEPs-induced procoagulant events and heart oxidative and nitrosative stress, inflammation, DNA damage and apoptosis, at least partly, through the inhibition of NFκB activation.

Feasibility of Catalpol Intranasal Administration and Its Protective Effect on Acute Cerebral Ischemia in Rats via Anti-Oxidative and Anti-Apoptotic Mechanisms

Purpose

Patients and Methods

Results

Conclusion

F-box and WD repeat domain-containing 7 (FBXW7) mediates the hypoxia inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) signaling pathway to affect hypoxic-ischemic brain damage in neonatal rats

The aim of this study was to determine whether F-box and WD repeat domain-containing 7 (FBXW7) can mediate the hypoxia inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) signaling pathway to affect neonatal hypoxic-ischemic brain damage (HIBD) in neonatal rats. HIBD rats were treated with LV-shFBXW7. Cerebral infarct size was determined by 2,3,5-triphenyltetrazolium chloride (TTC) staining, while microvessel density (MVD) was evaluated by immunohistochemistry. Learning and memory were tested using the Morris water maze (MWM) test. FBXW7 and HIF-1α/VEGF signaling pathway proteins were measured by Western blotting. Brain microvascular endothelial cells (BMECs) were isolated to establish an oxygen-glucose deprivation (OGD) model to evaluate treatment with FBXW7 siRNA. Cell viability was detected using a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay, while cell migration was evaluated using a wound healing assay. The tube formation of BMECs was also assessed. The results demonstrated that HIBD rats exhibited increased protein expression of FBXW7, HIF-1α, and VEGF. HIBD rats also displayed increased cerebral infarct size, prolonged escape latency and a decreased number of platform crossings. However, HIBD rats treated with LV-shFBXW7 exhibited reversal of these changes. In vitro experiments showed that BMECs in the OGD group had significantly decreased cell viability, shorter vascular lumen length, and shorter migration distance than cells in the control group. Moreover, silencing FBXW7 promoted proliferation, tube formation and migration of BMECs. Taken together, silencing FBXW7 upregulates the HIF-1α/VEGF signaling pathway to promote the angiogenesis of neonatal HIBD rats after brain injury, reducing infarct volume and improving recovery of nerve function in HIBD rats.

Repair Mechanisms of the Neurovascular Unit after Ischemic Stroke with a Focus on VEGF

The functional neural circuits are partially repaired after an ischemic stroke in the central nervous system (CNS). In the CNS, neurovascular units, including neurons, endothelial cells, astrocytes, pericytes, microglia, and oligodendrocytes maintain homeostasis; however, these cellular networks are damaged after an ischemic stroke. The present review discusses the repair potential of stem cells (i.e., mesenchymal stem cells, endothelial precursor cells, and neural stem cells) and gaseous molecules (i.e., nitric oxide and carbon monoxide) with respect to neuroprotection in the acute phase and regeneration in the late phase after an ischemic stroke. Commonly shared molecular mechanisms in the neurovascular unit are associated with the vascular endothelial growth factor (VEGF) and its related factors. Stem cells and gaseous molecules may exert therapeutic effects by diminishing VEGF-mediated vascular leakage and facilitating VEGF-mediated regenerative capacity. This review presents an in-depth discussion of the regeneration ability by which endogenous neural stem cells and endothelial cells produce neurons and vessels capable of replacing injured neurons and vessels in the CNS.

Hypoxia-inducible factor-1: Regulatory mechanisms and drug development in stroke

Stroke is an acute cerebrovascular disease caused by sudden rupture of blood vessels in the brain or blockage of blood vessels, which has now become one of the main causes of adult death. During stroke, hypoxia-inducible factor-1 (HIF-1), as an important regulator under hypoxia conditions, is involved in the pathological process of stroke by regulating multi-pathways, such as glucose metabolism, angiogenesis, erythropoiesis, cell survival. However, the roles of HIF-1 in stroke are still controversial, which are related with ischemic time and degree of ischemia. The regulatory mechanisms of HIF-1 in stroke include inflammation, autophagy, oxidative stress, apoptosis and energy metabolism. The potential drugs targeting HIF-1 have attracted more attention, such as HIF-1 inhibitors, HIF-1 stabilizers and natural products. Based on the role of HIF-1 in stroke, HIF-1 is expected to be a potential target for stroke treatment. Resolving when and what interventions for HIF-1 to take during stroke will provide novel strategies for stroke treatment.

Neuroprotective Phytochemicals in Experimental Ischemic Stroke: Mechanisms and Potential Clinical Applications

Ischemic stroke is a challenging disease with high mortality and disability rates, causing a great economic and social burden worldwide. During ischemic stroke, ionic imbalance and excitotoxicity, oxidative stress, and inflammation are developed in a relatively certain order, which then activate the cell death pathways directly or indirectly via the promotion of organelle dysfunction. Neuroprotection, a therapy that is aimed at inhibiting this damaging cascade, is therefore an important therapeutic strategy for ischemic stroke. Notably, phytochemicals showed great neuroprotective potential in preclinical research via various strategies including modulation of calcium levels and antiexcitotoxicity, antioxidation, anti-inflammation and BBB protection, mitochondrial protection and antiapoptosis, autophagy/mitophagy regulation, and regulation of neurotrophin release. In this review, we summarize the research works that report the neuroprotective activity of phytochemicals in the past 10 years and discuss the neuroprotective mechanisms and potential clinical applications of 148 phytochemicals that belong to the categories of flavonoids, stilbenoids, other phenols, terpenoids, and alkaloids. Among them, scutellarin, pinocembrin, puerarin, hydroxysafflor yellow A, salvianolic acids, rosmarinic acid, borneol, bilobalide, ginkgolides, ginsenoside Rd, and vinpocetine show great potential in clinical ischemic stroke treatment. This review will serve as a powerful reference for the screening of phytochemicals with potential clinical applications in ischemic stroke or the synthesis of new neuroprotective agents that take phytochemicals as leading compounds.

Neuroprotective Effect for Cerebral Ischemia by Natural Products: A Review

Natural products have a significant role in the prevention of disease and boosting of health in humans and animals. Stroke is a disease with high prevalence and incidence, the pathogenesis is a complex cascade reaction. In recent years, it’s reported that a vast number of natural products have demonstrated beneficial effects on stroke worldwide. Natural products have been discovered to modulate activities with multiple targets and signaling pathways to exert neuroprotection via direct or indirect effects on enzymes, such as kinases, regulatory receptors, and proteins. This review provides a comprehensive summary of the established pharmacological effects and multiple target mechanisms of natural products for cerebral ischemic injury in vitro and in vivo preclinical models, and their potential neuro-therapeutic applications. In addition, the biological activity of natural products is closely related to their structure, and the structure-activity relationship of most natural products in neuroprotection is lacking, which should be further explored in future. Overall, we stress on natural products for their role in neuroprotection, and this wide band of pharmacological or biological activities has made them suitable candidates for the treatment of stroke.

Inflammation-Mediated Angiogenesis in Ischemic Stroke

Stroke is the leading cause of disability and mortality in the world, but the pathogenesis of ischemic stroke (IS) is not completely clear and treatments are limited. Mounting evidence indicate that neovascularization is a critical defensive reaction to hypoxia that modulates the process of long-term neurologic recovery after IS. Angiogenesis is a complex process in which the original endothelial cells in blood vessels are differentiated, proliferated, migrated, and finally remolded into new blood vessels. Many immune cells and cytokines, as well as growth factors, are directly or indirectly involved in the regulation of angiogenesis. Inflammatory cells can affect endothelial cell proliferation, migration, and activation by secreting a variety of cytokines via various inflammation-relative signaling pathways and thus participate in the process of angiogenesis. However, the mechanism of inflammation-mediated angiogenesis has not been fully elucidated. Hence, this review aimed to discuss the mechanism of inflammation-mediated angiogenesis in IS and to provide new ideas for clinical treatment of IS.

The bidirectional role of the JAK2/STAT3 signaling pathway and related mechanisms in cerebral ischemia-reperfusion injury

The Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway, a well-conserved and basic intracellular signaling cascade, is mostly inactivated under basal conditions, although it can be phosphorylated under extracellular stimulation; in addition, it can influence the transcription and expression of multiple genes involved in biological processes such as cellular growth, metabolism, differentiation, degradation and angiogenesis. The inflammatory response, apoptosis, oxidative stress and angiogenesis are the main factors involved in the pathogenesis of ischemic stroke. Numerous studies have confirmed that the JAK2/STAT3 axis can be activated rapidly by ischemic stress, which is closely related to the regulation of these important pathological processes. However, different opinions on the specific role of this signaling pathway remain. In this paper, we review and summarize previous studies on the JAK2/STAT3 pathway in ischemic stroke.

Astragaloside IV Protects 6-Hydroxydopamine-Induced SH-SY5Y Cell Model of Parkinson's Disease via Activating the JAK2/STAT3 Pathway

Objectives

Astragaloside IV (AS-IV), the main active component of Astragalus membranaceus, bears anti-inflammatory, antioxidant, and neuroprotective activity. Parkinson’s disease (PD) is a common neurodegenerative disease. This study explored the protective effect of AS-IV on the cell model of PD.

Materials and Methods

SH-SY5Y cells were incubated with different concentrations (10, 50, 100, 150, and 200 μM) of 6-hydroxydopamine (6-OHDA) for 0, 3, 6, 12, 24, and 48 h to establish the PD cell model. Different concentrations (0, 25, 50, 100, 150, and 200 μM) of AS-IV or 15 mM JAK2/STAT3 pathway inhibitor SC99 was added for intervention 2 h before 6-OHDA treatment. The viability and morphological damage of 6-OHDA-treated SH-SY5Y cells were measured using MTT assay and Hoechst 33258 staining. The expression of microtubule associated protein 2 (MAP2) was detected by immunofluorescence staining. The levels of inflammation and oxidative stress were measured using ELISA. Apoptosis of 6-OHDA-treated SH-SY5Y cells was detected using flow cytometry, and phosphorylation level of JAK2 and STAT3 were detected using Western blot analysis.

Results

The survival rate of SH-SY5Y cells treated with 100 μM 6-OHDA for 24 h was about 50%. AS-IV (25–100 μM) significantly improved the viability (all p < 0.01), increased MAP2 expression, and repaired the morphological damage induced by 6-OHDA. AS-IV inhibited IL-1β, IL-6, and TNF-α level (all p < 0.05), reduced MDA and ROS content and increased SOD concentration, thereby reducing inflammation and oxidative stress (all p < 0.01) in 6-OHDA-treated SH-SY5Y cells. Moreover, AS-IV decreased apoptosis rate and Bax/Bcl-2 ratio induced by 6-OHDA (all p < 0.05). Mechanically, AS-IV significantly increased the phosphorylation of JAK2 and STAT3 (p < 0.01); the addition of SC99 decreased the cell viability, increased the apoptosis rate, enhanced the levels of inflammatory factors and oxidative stress.

Conclusion

AS-IV enhanced the cell viability, and inhibited apoptosis, inflammation and oxidative stress of 6-OHDA-treated SH-SY5Y cells via activating the JAK2/STAT3 signaling pathway. This study may confer novel insights for the management of PD.

Therapeutic modulation of the phosphatidylinositol 3-kinases (PI3K) pathway in cerebral ischemic injury

The cerebral ischemic reperfusion injury may leads to morbidity and mortality in patients. phosphatidylinositol 3-kinase (PI3K) signaling pathway has been believed to work in association with its downstream targets, other receptors, and pathways that may offer antioxidant, anti-inflammatory, anti-apoptotic effects, neuroprotective role in neuronal excitotoxicity. This review elaborates the mechanistic interventions of the PI3K pathway in cerebral ischemic injury in context to nuclear factor erythroid 2-related factor 2 (Nrf2) regulation, Hypoxia-inducible factor 1 signaling (HIF-1), growth factors, Endothelial NOS (eNOS) proinflammatory cytokines, Erythropoietin (EPO), Phosphatase and tensin homologous protein of chromosome 10 gene (PTEN) signaling, NF-κB/Notch signaling, c-Jun N-terminal kinase (JNK) and Glycogen synthase kinase-3β (GSK-3β) signaling pathway. Evidences showing the activation of PI3K inhibits apoptotic pathway, which results in its neuroprotective effect in ischemic injury. Despite discussing the therapeutic role of the PI3K pathway in treating cerebral ischemic injury, the review also enlighten the selective modulation of PI3K pathway with activators and inhibitors which may provide promising results in clinical and preclinical settings.

STAT3 activation by catalpol promotes osteogenesis-angiogenesis coupling, thus accelerating osteoporotic bone repair

BACKGROUND

Bone fracture repair has gained a lot of attention due to the high incidence of delayed union or even nonunion especially in osteoporotic patients, resulting in a dreadful impact on the quality of life. However, current therapies involve the costly expense and hence become unaffordable strategies for fracture recovery. Herein, developing new strategies for better bone repair is essential and urgent. Catalpol treatment has been reported to attenuate bone loss and promote bone formation. However, the mechanisms underlying its effects remain unraveled.

METHODS

Rat bone marrow mesenchymal stem cells (BMSCs) were isolated from rat femurs. BMSC osteogenic ability was assessed using ALP and ARS staining, immunofluorescence, and western blot analysis. BMSC-mediated angiogenic potentials were determined using the western blot analysis, ELISA testing, scratch wound assay, transwell migration assay, and tube formation assay. To investigate the molecular mechanism, the lentivirus transfection was used. Ovariectomized and sham-operated rats with calvaria defect were analyzed using micro-CT, H&E staining, Masson's trichrome staining, microfil perfusion, sequential fluorescent labeling, and immunohistochemistry assessment after administrated with/without catalpol.

RESULTS

Our results manifested that catalpol enhanced BMSC osteoblastic differentiation and promoted BMSC-mediated angiogenesis in vitro. More importantly, this was conducted via the JAK2/STAT3 pathway, as knockdown of STAT3 partially abolished beneficial effects in BMSCs. Besides, catalpol administration facilitated bone regeneration as well as vessel formation in an OVX-induced osteoporosis calvarial defect rat model.

CONCLUSIONS

The data above showed that catalpol could promote osteogenic ability of BMSC and BMSC-dependent angiogenesis through activation of the JAK2/STAT3 axis, suggesting it may be an ideal therapeutic agent for clinical medication of osteoporotic bone fracture.

Network Pharmacology-Based Prediction of Catalpol and Mechanisms against Stroke

Aim

To apply the network pharmacology method to screen the target of catalpol prevention and treatment of stroke, and explore the pharmacological mechanism of Catalpol prevention and treatment of stroke.

Methods

PharmMapper, GeneCards, DAVID, and other databases were used to find key targets. We selected hub protein and catalpol which were screened for molecular docking verification. Based on the results of molecular docking, the ITC was used to determine the binding coefficient between the highest scoring protein and catalpol. The GEO database and ROC curve were used to evaluate the correlation between key targets.

Results

27 key targets were obtained by mapping the predicted catalpol-related targets to the disease. Hub genes (ALB, CASP3, MAPK1 (14), MMP9, ACE, KDR, etc.) were obtained in the key target PPI network. The results of KEGG enrichment analysis showed that its signal pathway was involved in angiogenic remodeling such as VEGF, neurotrophic factors, and inflammation. The results of molecular docking showed that ACE had the highest docking score. Therefore, the ITC was used for the titration of ACE and catalpol. The results showed that catalpol had a strong binding force with ACE.

Conclusion

Network pharmacology combined with molecular docking predicts key genes, proteins, and signaling pathways for catalpol in treating stroke. The strong binding force between catalpol and ACE was obtained by using ITC, and the results of molecular docking were verified to lay the foundation for further research on the effect of catalpol on ACE. ROC results showed that the AUC values of the key targets are all >0.5. This article uses network pharmacology to provide a reference for a more in-depth study of catalpol's mechanism and experimental design.

Catalpol protects vascular structure and promotes angiogenesis in cerebral ischemic rats by targeting HIF-1α/VEGF

BACKGROUND

The initial factor in the occurrence, development, and prognosis of cerebral ischemia is vascular dysfunction in the brain, and vascular remodeling of the brain is the key therapeutic target and strategy for ischemic tissue repair. Catalpol is the main active component of the radix of Rehmannia glutinosa Libosch, and it exhibits potential pleiotropic protective effects in many brain-related diseases, including stroke.

PURPOSE

The present study was designed to investigate whether catalpol protects vascular structure and promotes angiogenesis in cerebral ischemic rats and to identify its possible mechanisms in vivo and in vitro.

STUDY DESIGN

Cerebral ischemic rats and oxygen-glucose deprivation-exposed brain microvascular endothelial cells were used to study the therapeutic potential of catalpol in vivo and in vitro.

METHODS

First, neurological deficits, histopathological morphology, infarct volume, vascular morphology, vessel density, and angiogenesis in focal cerebral ischemic rats were observed to test the potential treatment effects of catalpol. Then, oxygen-glucose deprivation-exposed brain microvascular endothelial cells were used to mimic the pathological changes in vessels during ischemia to study the effects and possible mechanisms of catalpol in protecting vascular structure and promoting angiogenesis.

RESULTS

The in vivo results showed that catalpol reduced neurological deficit scores and infarct volume, protected vascular structure, and promoted angiogenesis in cerebral ischemic rats. The in vitro results showed that catalpol improved oxygen-glucose deprivation-induced damage and promoted proliferation, migration, and in vitro tube formation of brain microvascular endothelial cells. The HIF-1α (hypoxia-inducible factor 1α)/VEGF (vascular endothelial growth factor) pathway was activated by catalpol both in the brains of cerebral ischemic rats and in primary brain microvascular endothelial cells, and the activating effects of catalpol were inhibited by SU1498.

CONCLUSION

The results of both the in vivo and in vitro studies proved that catalpol protects vascular structure and promotes angiogenesis in focal cerebral ischemic rats and that the mechanism is dependent on HIF-1α/VEGF.

Expression, Purification, Refolding, and Characterization of a Neverland Protein From Caenorhabditis elegans

Steroid hormones that serve as vital compounds are necessary for the development and metabolism of a variety of organisms. The neverland (NVD) family genes encode the conserved Rieske-type oxygenases, which are accountable for the dehydrogenation during the synthesis and regulation of steroid hormones. However, the His-tagged NVD protein from Caenorhabditis elegans expresses as inclusion bodies in Escherichia coli BL21 (DE3). This bottleneck can be solved through refolding by urea or the introduction of a maltose-binding protein (MBP) tag at the N-terminus. Through further research on purification after the introduction of a MBP tag at the N-terminus, the CD measurement and fluorescence-based thermal shift assay indicated that MBP was favorable for the NVD proteins' solubility and stability, which may be beneficial for the large-scale manufacture of NVD protein for further research. The structural model contained the Rieske [2Fe-2S] domain and non-heme iron-binding motif, which were similar to 3-ketosteroid 9 α-hydroxylase.

Traditional Chinese medicine formulas, extracts, and compounds promote angiogenesis

Ischemic diseases, such as ischemic heart diseases and ischemic stroke, are the leading cause of death worldwide. Angiogenic therapy is a wide-ranging approach to fighting ischemic diseases. However, compared with anti-angiogenesis therapy for tumors, less attention has been paid to therapeutic angiogenesis. Recently, Traditional Chinese medicine (TCM) has garnered increasing interest for its definite curative effect and low toxicity. A growing number of studies have reported that TCM formulas, extracts, and compounds from herbal medicines exert pro-angiogenic activity, which has been confirmed in a few clinical trials. For comprehensive analysis of relevant literature, global and local databases including PubMed, Web of Science, and China National Knowledge Infrastructure were searched using keywords such as "angiogenesis," "neovascularization," "traditional Chinese medicine," "formula," "extract," and "compound." Articles were chosen that are closely and directly related to pro-angiogenesis. This review summarizes the pro-angiogenic activity and the mechanism of TCM formulas, extracts, and compounds; it delivers an in-depth understanding of the relationship between TCM and pro-angiogenesis and will provide new ideas for clinical practice.

Determination of behavior of catalpol hexapropionate in simulated gastric conditions by UPLC-ESI-HRMS

Catalpol hexapropionate (CP-6) was designed and synthesized as anti-aging drug. In order to investigate the behavior of CP-6 in simulated gastric juice, ultra-high performance liquid chromatography-electrospray ionization-high resolution mass spectrometry was used to determinate the components produced in simulated gastric conditions. Six metabolites were identified with the possible metabolic processes proposed. Hydrolysis may be the main metabolic pathways. The relative contents of CP-6 and its metabolites were determined using their extractive ion chromatograms. The results show that the relative content of CP-6 is rapidly decreased about 15% during the first 0.5 h and generally stable after 0.5 h. The mainly produced metabolites are catalpol penta-propionate (CP-5), catalpol and a spot of catalpol tetra-propionate (CP-4), catalpol tri-propionate (CP-3), catalpol dipropionate (CP-2) and catalpol propionate (CP-1). The metabolitic process of CP-6 may be an hydrolysis under acid conditions. The research results can provide useful information for development and utilization of CP-6 as a pharmaceutical preparation.

Overexpression of HIF-1α protects PC12 cells against OGD/R-evoked injury by reducing miR-134 expression

Nowadays, searching for new therapeutic targets for cerebral stroke treatment are still in urgent need. Our study explored the influences and mechanisms of HIF-1α on OGD/R-evoked injury. OGD/R treatment was conducted on PC12 cells to simulate ischemic injury. CCK-8, flow cytometry and qRT-PCR were conducted to determine the variations of cell viability, apoptosis and gene expression, respectively. Cell transfections were conducted to overexpress HIF-1α and miR-134. Variations of protein levels were evaluated by employing western blot. Results showed that OGD/R treatment induced cell injury through reducing viability, while enhancing apoptosis that was validated by the elevated ratios of C/P-PARP and C/P-caspase-3. HIF-1α expression was markedly increased by OGD/R treatment. HIF-1α overexpression attenuated OGD/R-evoked injury in PC12 cells and remarkably reversed OGD/R-triggered inhibitory effects on ERK1/2 and JAK1/STAT3 pathways. Besides, miR-134 was also down-regulated by HIF-1α overexpression in PC12 cells. Up-regulation of miR-134 notably counteracted HIF-1α overexpression-triggered neuro-protective impacts on OGD/R-evoked injury and ERK1/2 and JAK1/STAT3 pathways. Our present study reported that HIF-1α overexpression protected PC12 cells against OGD/R-evoked injury via down-regulation of miR-134, which making HIF-1α and miR-134 to be promising targets for cerebral stroke therapy.

Hydroxysafflor Yellow A Confers Neuroprotection from Focal Cerebral Ischemia by Modulating the Crosstalk Between JAK2/STAT3 and SOCS3 Signaling Pathways

Natural bioactive compounds have increasingly proved to be promising in evidence- or target-directed treatment or modification of a spectrum of diseases including cerebral ischemic stroke. Hydroxysafflor yellow A (HSYA), a major active component of the safflower plant, has drawn more interests in recent year for its multiple pharmacological actions in the treatment of cerebrovascular and cardiovascular diseases. Although the Janus kinase signaling, such as JAK2/STAT3 pathway, has been implicated in the modulation of the disease, the inhibition or activation of the pathway that contributed to the neuronal prevention from ischemic damages remains controversial. In this study, a series of experiments were performed to examine the dose- and therapeutic time window-related pharmacological efficacies of HSYA with emphasis on the HSYA-modulated interaction of JAK2/STAT3 and SOCS3 signaling in the MCAO rats. We found that HSYA treatment significantly rescued the neurological and functional deficits in a dose-dependent manner in the MCAO rats within 3 h after ischemia. HSYA treatment with a dosage of 8 mg/kg or higher markedly downregulated the expression of the JAK2-mediated signaling that was activated in response to ischemic insult, while it also promoted the expression of SOCS3 coordinately. In the subsequent experiments with the use of the JAK2 inhibitor WP1066, we found that the treatment of WP1066 alone or combination of WP1066/HSYA all exhibited inhibitory effects on JAK2-mediated signaling, while there was no influence on the SOCS3 activity of corresponding efficacious data in the MCAO rats, suggesting that excessive activation of JAK2/STAT3 might be necessary for HSYA to provoke SOCS3-negative feedback signaling. Taking together, our study demonstrates that HSYA might modulate the crosstalk between JAK2/STAT3 and SOCS3 signaling pathways that eventually contributed to its therapeutic roles against cerebral ischemic stroke.

Activating α7nAChRs enhances endothelial progenitor cell function partially through the JAK2/STAT3 signaling pathway

Microvascular injury is a common pathological process in ischemia-reperfusion injury. Endothelial progenitor cells (EPCs) are vital cells for angiogenesis and endothelial repair. These cells can home to injury sites and secrete angiogenic growth factors. α7nAChRs are pivotal in cholinergic angiogenesis, which is associated with endothelial cells and EPCs. Our study was designed to determine whether activating α7nAChRs enhances the function of EPCs and to explore the underlying mechanism. EPCs were derived from the bone marrow of male Sprague-Dawley rats and treated with an α7nAChR agonist (PNU282987), an α7nAChR antagonist (MLA) and a JAK2 antagonist (AG490). We then assayed the angiogenic abilities of the EPCs, including proliferation ability, adhesion ability, migration ability and in vitro tube formation ability. The levels of total JAK2 (t-JAK2), phosphorylated JAK2 (p-JAK2), total STAT3 (t-STAT3) and phosphorylated STAT3 (p-STAT3) were estimated by western blot analysis. PNU282987 treatment facilitated the angiogenic abilities of EPCs compared with the control regimen. The western blot data suggested that PNU282987 increased the levels of p-JAK2 and p-STAT3. However, the differences in t-JAK2 levels and t-STAT3 levels between the agonist-treated group and the control group were not significant. Moreover, treating EPCs with AG490 reduced STAT3 phosphorylation and attenuated the PNU282987-induced enhancement of EPCs. We demonstrated that activating α7nAChRs can enhance EPC functions partially through the JAK2/STAT3 signaling pathway. This study reveals that α7nAChRs are potential therapeutic targets for angiogenesis and that the JAK2/STAT3 pathway plays a vital role in the associated therapeutic mechanism.

Multiple Biological Effects of an Iridoid Glucoside, Catalpol and Its Underlying Molecular Mechanisms

Catalpol, an iridoid glucoside, is widely distributed in many plant families and is primarily obtained from the root of Rehmanniaglutinosa Libosch. Rehmanniaglutinosa is a plant very commonly used in Chinese and Korean traditional medicine for various disorders, including diabetes mellitus, neuronal disorders, and inflammation. Catalpol has been studied extensively for its biological properties both in vitro and in vivo. This review aims to appraise the biological effects of catalpol and their underlying mechanisms. An extensive literature search was conducted using the keyword "Catalpol" in the public domains of Google scholar, PubMed, and Scifinder. Catalpol exhibits anti-diabetic, cardiovascular protective, neuroprotective, anticancer, hepatoprotective, anti-inflammatory, and anti-oxidant effects in experimental studies. Anti-inflammatory and antioxidant properties are mostly related for its biological effect. However, some specific mechanisms are also elucidated. Elevated serotonin and BDNF level by catalpol significantly protect against depression and neurodegeneration. Catalpol demonstrated an increased mitochondrial biogenesis and activation of PI3K/Akt pathway for insulin sensitizing effect. Further, its cardiovascular protective effect was linked to PI3K/Akt, apelin/APJ and Jak-Stat pathway. Catalpol produced a significant reduction in cell proliferation and an increase in apoptosis in different cancer conditions. Overall, catalpol demonstrated multiple biological effects due to its numerous mechanisms including anti-inflammatory and antioxidant effects.

Catalpol Enhances Neurogenesis And Inhibits Apoptosis Of New Neurons Via BDNF, But Not The BDNF/Trkb Pathway

Background

The role of catalpol in brain neurogenesis and newborn neuron survival has not been previously determined in permanent middle cerebral artery occlusion (pMCAO).

Methods

Fifty-four rats were divided into 6 groups: pMCAO (model, n=9); sham operation (NS, n=9); catalpol treatment (5 mg/kg and 10 mg/kg subgroups, n=9 each); K252a (n=9); and K252a+catalpol 5 mg/kg (n=9) with stroke. The effects of catalpol on behavior, neurogenesis surrounding the infarction ipsilateral to pMCAO, and the expression of brain-derived neurotrophic factor (BDNF) and its receptor (TrkB) were evaluated. Vehicle or, K252a (i.p.), an inhibitor of TrkB phosphorylase.

Results

Repeated administration of catalpol reduced neurological deficits and significantly improved neurogenesis. Catalpol increased the number of newborn immature neurons, as determined by BrdU⁺-Nestin⁺ and BrdU⁺-Tuj-1⁺ staining, and downregulated cleaved caspase 3 in Tuj-1⁺ cells at day 7 following stroke. Moreover, catalpol increased the protein expression of Tuj-1, MAP2, and the Bcl-2/Bax ratio, as determined using Western blot. Catalpol also significantly increased brain levels of BDNF, but not TrkB, resulting in enhanced survival of newborn neurons via inhibition of apoptosis.

Conclusion

Catalpol may contribute to neurogenesis in infarcted brain regions and help promote the survival of newborn neurons by activating BDNF, but not BDNF/TrkB signaling.

Catalpol may improve axonal growth via regulating miR-124 regulated PI3K/AKT/mTOR pathway in neurons after ischemia

Background

MicroRNA-124 (miR-124) is a brain-specific miRNA molecule, the highest expression in the cortex and is associated with neuronal protection after stroke. This study aimed to investigate whether catalpol could affect miR-124 to regulate PI3K/AKT/mTOR pathway, promoting axonal growth in stroke rats.

Methods

Cells were divided into three groups: control group, miRNA124 agomir group, and miRNA124 antagomir group. To explore the mechanism, cells were divided into seven groups: control group, OGD group (OGD/R), miRNA124 agomir group, miRNA124 agomir plus catalpol group, miRNA124 antagomir group, miRNA124 antagomir plus catalpol group, and catalpol group. Before OGD/R, miRNA124 antagomir and microRNA124 agomir were transfected into neurons for 6 h by using ribo FECT nd Consumablesn/reper transfection kit. Cell survival and cell death were detected by MTT and LDH assay. Axonal growth was assessed by MAP-2 immunofluorescence staining. Western blotting and qPCR were used to detect the expression of molecules in the PI3K/AKT/mTOR pathway.

Results

Inhibition of miR-124 activated PI3K/AKT/mTOR pathway and promoted neuronal survival and axonal growth. The expression of miR-124 increased after OGD/R, and catalpol could inhibit miR-124 to activate PI3K/AKT/mTOR pathway to further promote axonal growth.

Conclusions

It is concluded that catalpol may inhibit miR-124 to activate PI3K/AKT/mTOR pathway, promoting axonal growth.