Salidroside improves brain ischemic injury by activating PI3K/Akt pathway and reduces complications induced by delayed tPA treatment

The effect of salidroside in promoting endogenous neural regeneration after cerebral ischemia/reperfusion involves notch signaling pathway and neurotrophic factors

BACKGROUND

Salidroside is the major bioactive and pharmacological active substance in Rhodiola rosea L. It has been reported to have neuroprotective effects on cerebral ischemia/reperfusion (I/R). However, whether salidroside can enhance neural regeneration after cerebral I/R is still unknown. This study investigated the effects of salidroside on the endogenous neural regeneration after cerebral I/R and the related mechanism.

METHODS

Focal cerebral I/R was induced in rats by transient middle cerebral artery occlusion/reperfusion (MCAO/R). The rats were intraperitoneally treated salidroside once daily for 7 consecutive days. Neurobehavioral assessments were performed at 3 days and 7 days after the injury. TTC staining was performed to assess cerebral infarct volume. To evaluate the survival of neurons, immunohistochemical staining of Neuronal Nuclei (NeuN) in the ischemic hemisphere were conducted. Also, immunofluorescence double or triple staining of the biomarkers of proliferating neural progenitor cells in Subventricular Zone (SVZ) and striatum of the ischemia hemisphere were performed to investigate the neurogenesis. Furthermore, reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to detect the expression of neurotrophic factors (NTFs) brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). Expression of Notch1 and its target molecular Hes1 were also analyzed by western-blotting and RT-PCR.

RESULTS

Salidroside treatment ameliorated I/R induced neurobehavioral impairment, and reduced infarct volume. Salidroside also restored NeuN positive cells loss after I/R injury. Cerebral I/R injury significantly increased the expression of 5-Bromo-2'-Deoxyuridine (BrdU) and doublecotin (DCX), elevated the number of BrdU/Nestin/DCX triple-labeled cells in SVZ, and BrdU/Nestin/glial fibrillary acidic protein (GFAP) triple-labeled cells in striatum. Salidroside treatment further promoted the proliferation of BrdU/DCX labeled neuroblasts and BrdU/Nestin/GFAP labeled reactive astrocytes. Furthermore, salidroside elevated the mRNA expression and protein concentration of BDNF and NGF in ischemia periphery area, as well. Mechanistically, salidroside elevated Notch1/Hes1 mRNA expression in SVZ. The protein levels of them were also increased after salidroside administration.

CONCLUSIONS

Salidroside enhances the endogenous neural regeneration after cerebral I/R. The mechanism of the effect may involve the regulation of BDNF/NGF and Notch signaling pathway.

Neurovascular glial unit: A target of phytotherapy for cognitive impairments

BACKGROUND

Neurovascular glial unit (NVGU) dysfunction has been reported to be an early and critical event in the pathophysiology of Alzheimer's disease (AD) and vascular dementia (VD). Although herbal medicines, with their favorable safety profiles and low adverse effects, have been suggested to be useful for the treatment of cognitive impairment, the potential role of the NVGU as the target of the effects of herbal medicines is still unclear.

PURPOSE

This review aimed to retrieve evidence from experimental studies of phytopharmaceuticals targeting the NVGU for the treatment of cognitive impairment in AD and VD, and discussed the potential of phytopharmaceuticals to improve cognitive impairment from the perspective of the NVGU.

STUDY DESIGN AND METHODS

We systematically searched PubMed, Google Scholar, Web of Science, and CNKI. The keywords used for searching information on the NVGU in the treatment of cognitive impairments included "Alzheimer's disease," "Vascular dementia," "Herbal medicines," "Natural products," "Neurovascular," "Adverse reaction," and "Toxicity, etc." We selected studies on the basis of predefined eligibility criteria.

RESULTS

NVGU mainly consists of endothelial cells, pericytes, astrocytes, microglia, oligodendrocytes, and neurons, and damage to these cells can induce cognitive impairment by impairing the blood-brain barrier (BBB) and cerebral blood flow (CBF) as well as neuronal function. The active components of herbal medicines, including Ginkgo biloba L., Ginseng Radix et Rhizoma, Epimedium Folium, Chuanxiong Rhizoma, Carthami flos, and Acorus tatarinowii Schott, as well as traditional Chinese medicine prescriptions have shown the potential to improve BBB function and increase CBF to prevent cognitive impairment by inhibiting astrocyte and microglia activation, protecting oligodendrocyte myelin function, reducing neuronal apoptosis, and promoting angiogenesis.

CONCLUSIONS

Herbal medicines demonstrate great potential to prevent cognitive impairment. Multiple components from herbal medicines may function through different signaling pathways to target the NVGU. Future studies using novel drug-carrier or delivery systems targeting the NVGU will certainly facilitate the development of phytopharmaceuticals for AD and VD.

Salidroside postconditioning attenuates ferroptosis-mediated lung ischemia-reperfusion injury by activating the Nrf2/SLC7A11 signaling axis

BACKGROUND

Ferroptosis, an iron-dependent programmed necrosis, is linked to lung ischemia-reperfusion injury. Salidroside is a glycoside derived from the Rhodiola rosea plant that exhibits anti-inflammatory and antioxidant properties. However, it is uncertain whether salidroside alleviates lung ischemia-reperfusion injury. This investigation explored the function of salidroside in ferroptosis in lung ischemia-reperfusion injury.

METHODS

A lung ischemia-reperfusion model was established in wild-type and Nrf2^-/- mice, and pulmonary epithelial cells were exposed to hypoxia/regeneration in vitro. We evaluated ferroptosis-related factors by western blotting, transmission electron microscopy, and fluorescence microscopy. To investigate the regulation of Nrf2 by salidroside, coimmunoprecipitation and luciferase reporter assays were used. Transwell assays were used to detect macrophage migration.

RESULTS

The data indicated that salidroside postconditioning significantly reduced ferroptosis and alleviated lung ischemia-reperfusion injury in wild-type mice, as evidenced by improved histology and inflammation, reduced lipid peroxides and iron overload, and the induction of Nrf2, SLC7A11, and GPX4 expression. Salidroside activated Nrf2 signaling, resulting in Keap1-Nrf2 dissociation, nuclear translocation, and increased antioxidant-response element reporter activity. Sal consistently inhibited hypoxia/regeneration-induced pulmonary epithelial cell ferroptosis by activating the Nrf2 signaling pathway. Furthermore, ferroptotic cells recruited macrophages via CCL2, whereas salidroside lowered CCL2 expression and inhibited ferroptosis-induced macrophage chemotaxis in lung ischemia-reperfusion injury. Additionally, the antiferroptotic effects of salidroside against lung ischemia-reperfusion injury were eliminated in Nrf2^-/- mice.

CONCLUSIONS

This study clearly shows that salidroside postconditioning attenuates ferroptosis-mediated lung ischemia-reperfusion injury by activating the Nrf2/SLC7A11 signaling axis.

Salidroside intensifies mitochondrial function of CoCl2-damaged HT22 cells by stimulating PI3K-AKT-MAPK signaling pathway

BACKGROUND

Salidroside (Sal), an active component from Rhodiola crenulata, has been confirmed to exert neuroprotective effects against hypoxia. However, its molecular mechanisms of intensifying mitochondrial function still largely unknown. In the present study, we aimed to explore the mechanisms by which Sal heightened mitochondrial function in CoCl₂-induced HT22 hypoxic injury.

METHODS

The hypoxic condition of HT22 cells was performed by CoCl₂ stimulus. We then investigated the effects of Sal on the viability of hypoxic HT22 cells by cell counting kit-8. The contents of lactate dehydrogenase (LDH) release in cultured supernatant were detected by using commercial biochemical kit. Superoxide free radical scavenging activity, total antioxidant capacity assay kit with ferric reducing ability of plasma and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) methods were employed to detect the free radical scavenging ability and antioxidant capacity of Sal. Meanwhile, intracellular reactive oxygen species (ROS), Ca2+ and mitochondrial membrane potential (MMP) were determined by corresponding specific labeled probes. Mitochondrial morphology was tested by Mito-tracker green with confocal microscopy. Hoechst 33342 and Annexin V-FITC/propidium iodide staining were also employed to evaluate the effect of Sal on cell apoptosis. Oxygen consumption rate (OCR), real-time ATP production and proton efflux rate were measured using a Seahorse analyzer. Additionally, the potential interactions of Sal with PI3K-AKT signaling pathway-related proteins were predicted and tested by molecular docking, molecular dynamics simulation (MDS) and localized surface plasmon resonance (LSPR) techniques, respectively. Furthermore, the protein levels of p-PI3K, PI3K, p-AKT, AKT, p-JNK, JNK, p-p38 and p38 were estimated by western blot analysis.

RESULTS

Sal alleviated CoCl2-induced hypoxic injury in HT22 cells as evidenced by increased cell viability and decreased LDH release. In vitro antioxidant test confirmed that Sal had marvelous antioxidant abilities. The protected mitochondrial function by Sal treatment was illustrated by the decrease of ROS, Ca2+, mitochondrial fragment and the increase of MMP. In addition, Sal ameliorated the apoptosis of HT22 cells by decreasing Hoechst 33342 positive cells and the rate of apoptotic cells. Enhancement of energy metabolism in HT22 by Sal was demonstrated by increased OCR, real-time ATP generation and proton efflux rate. The molecular docking confirmed the potential binding of Sal to PI3K, AKT and CaMK II proteins with calculated binding energy of -1.32, -4.21 and -4.38 kcal/mol, respectively. The MDS test revealed the average hydrogen bond of complex Sal-PI3K and Sal-AKT were 0.79 and 4.46, respectively. The results of LSPR verified the potential binding of Sal to proteins PI3K, AKT and HIF-1α with affinity values of 5.20 × 10 - 3, 2.83 × 10 - 3 and 3.97 × 10 - 3 KD, respectively. Western blot analysis further argued that Sal consolidated the levels of p-PI3K and p-AKT. Meanwhile, Sal could downregulate the proteins expression of p-JNK and p-p38.

CONCLUSION

Collectively, our findings suggested that Sal can intensify mitochondrial function of CoCl2-simulated hypoxia injury in HT22 cells by stimulating PI3K-AKT-MAPK signaling pathway. Sal is a potential agent for mitochondrial protection against hypoxia with the underlying molecular mechanisms of energy metabolism being further elucidated.

Salidroside inhibited cerebral ischemia/reperfusion-induced oxidative stress and apoptosis via Nrf2/Trx1 signaling pathway

Cerebral ischemia reperfusion injury (CIRI) is still a serious problem threatening human health. Salidroside (SAL) is a natural phenylpropanoid glycoside compound with antioxidant, anti-inflammatory, and anti-ischemic properties. This study investigated the protective mechanism of SAL on middle cerebral artery occlusion (MCAO)- and oxygen-glucose deprivation/reoxygenation (OGD/R) model-induced CIRI via regulating the nuclear factor erythroid 2-related factor 2 (Nrf2)/thioredoxin 1 (Trx1) axis. The results indicated that SAL (50 mg/kg or 100 mg/kg, intraperitoneal injection) not only effectively alleviated infarction rate, improved histopathological changes, relieved apoptosis by strengthening the suppression of cleaved caspase-3 and Bax/Bcl-2 proteins and decreased malondialdehyde (MDA) formation, but also increased superoxide dismutase (SOD) and catalase (CAT) activities and upregulated the expressions of Nrf2 and Trx1 on MCAO-induced CIRI rats. SAL also efficiently inhibited apoptosis and decreased oxidative stress in OGD/R-stimulated PC12 cells. Furthermore, blocking the Nrf2/Trx1 pathway using tretinoin, an Nrf2 inhibitor, significantly reversed the protective effect of SAL on OGD/R-induced oxidative stress. Moreover, SAL reduced the expression of apoptosis signal-regulating kinase-1 (ASK1) and mitogen-activated protein kinase (MAPK) family proteins. These results demonstrated that SAL inhibited oxidative stress through Nrf2/Trx1 signaling pathway, and subsequently reduced CIRI-induced apoptosis by inhibiting ASK1/MAPK.

The mechanism of ferroptosis regulating oxidative stress in ischemic stroke and the regulation mechanism of natural pharmacological active components

Cerebrovascular diseases, such as ischemic stroke, pose serious medical challenges worldwide due to their high morbidity and mortality and limitations in clinical treatment strategies. Studies have shown that reactive oxygen species (ROS)-mediated inflammation, excitotoxicity, and programmed cell death of each neurovascular unit during post-stroke hypoxia and reperfusion play an important role in the pathological cascade. Ferroptosis, a programmed cell death characterized by iron-regulated accumulation of lipid peroxidation, is caused by abnormal metabolism of lipids, glutathione (GSH), and iron, and can accelerate acute central nervous system injury. Recent studies have gradually uncovered the pathological process of ferroptosis in the neurovascular unit of acute stroke. Some drugs such as iron chelators, ferrostatin-1 (Fer-1) and liproxstatin-1 (Lip-1) can protect nerves after neurovascular unit injury in acute stroke by inhibiting ferroptosis. In addition, combined with our previous studies on ferroptosis mediated by natural compounds in ischemic stroke, this review summarized the progress in the regulation mechanism of natural chemical components and herbal chemical components on ferroptosis in recent years, in order to provide reference information for future research on ferroptosis and lead compounds for the development of ferroptosis inhibitors.

Rhodiola crenulate alleviates hypobaric hypoxia-induced brain injury via adjusting NF-κB/NLRP3-mediated inflammation

BACKGROUND

Rhodiola crenulate (R. crenulate), a famous Tibetan medicine, has been demonstrated to possess superiorly protective effects in high-altitude hypoxic brain injury (HHBI). However, its mechanisms on HHBI are still largely unknown.

METHODS

Herein, the protective effects and underlying mechanisms of R. crenulate on HHBI of BABL/c mice were explored through in vivo experiments. The mice model of HHBI was established using an animal hypobaric and hypoxic chamber. R. crenulate extract (RCE) (0.5, 1.0 and 2.0 g/kg) was given by gavage for 7 days. Pathological changes and neuronal viability of mice hippocampus and cortex were evaluated using H&E and Nissl staining, respectively. The brain water content (BWC) in mice was determined by calculating the ratio of dry to wet weight of brain tissue. And serum of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH-Px) and lactate dehydrogenase (LDH) were detected via commercial biochemical kits. Synchronously, the contents of total antioxidant capacity (T-AOC), lactic acid (LA), adenosine triphosphate (ATP), succinate dehydrogenase (SDH), pyruvate kinase (PK), Ca²⁺-Mg²⁺-ATPcase, Na⁺-K⁺-ATPcase, TNF-α, IL-1β and IL-6 in brain tissue were quantitative analysis by corresponding ELISA assay. Subsequently, NLRP3, ZO-1, claudin-5, occluding, p-p65, p65, ASC, cleaved-caspase-1, caspase-1 and IL-18 were determined by immunofluorescent and western blot analyses.

RESULTS

The results demonstrated that RCE remarkably alleviated pathological damage, BWC, as well enhanced neuronal viability. Furthermore, the oxidative stress injuries were reversely abrogated after RCE treatment, evidenced by the increases of SOD, GSH-Px and T-AOC, while the decreases of MDA and LDH contents. Marvelously, the administration of RCE rectified and balanced the abnormal energy metabolism via elevating the levels of ATP, SDH, PK, Ca²⁺-Mg²⁺-ATPcase and Na⁺-K⁺-ATPcase, and lowering LA. Simultaneously, the expression of tight junction proteins (ZO-1, claudin-5 and occludin) was enhanced, illustrating RCE treatment might maintain the integrity of blood-brain barrier (BBB). Additionally, RCE treatment confined the contents of IL-6, IL-1β and TNF-α, and attenuated fluorescent signal of NLRP3 protein. Concurrently, the results of western blot indicated that RCE treatment dramatically restrained p-p65/p65, ASC, NLRP3, cleaved-caspase-1/caspase-1 and IL-18 protein expressions in brain tissues of mice.

CONCLUSION

RCE may afford a protectively intervention in HHBI of mice through suppressing the oxidative stress, improving energy metabolism and the integrity of BBB, and subsiding inflammatory responses via the NF-κB/NLRP3 signaling pathway. As a promising agent for the treatment of mice HHBI, the deep-crossing molecular mechanisms of R. crenulate still needs to be further elucidated to identify novel core hub targets.

Efficacy of Chinese herbal medicine for tPA thrombolysis in experimental stroke: A systematic review and meta-analysis

BACKGROUND

Tissue-type plasminogen activator (tPA) remains the sole FDA approved thrombolytic drug for ischemic stroke. But delayed thrombolytic therapy with tPA may increase the risk of hemorrhagic transformation. Many Chinese herbal medicines have been used as tPA helpers to enhance the capacity of tPA and minimize the risk of hemorrhagic transformation. The efficacy of Chinese herbal medicines on tPA thrombolysis is not systematically analyzed.

METHODS

We searched the following three databases up to January 2022: Web of Science, PubMed, and Scopus. Studies that reported the efficacy and safety of Chinese herbal medicines on tPA thrombolysis in experimental stroke were included. The efficacy outcomes were neurological score and infarct volume, the safety outcomes were cerebral hemorrhage and blood brain barrier (BBB) damage. We used the checklist of CAMARADES to assess the quality of included studies. Standardized mean difference (SMD) with 95% confidence intervals were used to assess all the outcomes. Subgroup analyses were performed to explore the sources of heterogeneity. Trim and fill method and Egger's test were used to assess the potential publication bias. Sensitivity analyses were used to identify the stability of the results.

RESULTS

A total of nine studies including 11 Chinese herbal medicines fulfilled the inclusion criteria and were subsequently analyzed. The pooled data demonstrated that Chinese herbal medicines improved neurological score (2.23 SMD, 1.42-3.04), infarct volume (1.08 SMD, 0.62-1.54), attenuated cerebral hemorrhage (1.87 SMD, 1.34-2.4), and BBB dysfunction (1.9 SMD, 1.35-2.45) following tPA thrombolysis in experimental stroke. Subgroup analysis indicated that the route of drug delivery, dosage of tPA, and stroke model used may be factors inducing heterogeneity and influencing the efficacy.

CONCLUSION

Treatment with Chinese herbal medicines significantly improved neurological score and infarct volume, reduced cerebral hemorrhage and BBB damage after tPA thrombolysis. This study supports Chinese herbal medicine as an adjuvant therapy in reducing the side effects of tPA thrombolysis after acute ischemic stroke. The results should be interpreted with more caution since this article was based on animal studies.

Analgecine protects against cerebral ischemia-reperfusion through apoptosis inhibition and anti-neuroinflammation in rats

Stroke influence the quality of life of patients and leave big public health issues as acute cerebrovascular disease all over the world. Analgecine (AGC) relieves pain and accelerates repair of nerve injury. This current study aims to observe the pharmacological effects and related mechanisms of AGC in cerebral ischemic stroke among middle cerebral artery ischemia-reperfusion (MCAO) rats. After seven days of AGC administration, motor function was enhanced as evidenced by the prehensile traction test. Morphological ameliorations were observed by immunohistochemistry analysis. The protein expression levels of HSP70, Bcl-2, Bax, TRAF-6, MyD88, BDNF, NGF, pCREB, CREB, pTrkB, TrkB, pAKT and AKT were estimated by western blot. Meanwhile, AGC alleviated MCAO-induced inflammation chiefly by decreasing inflammatory cytokines in rat brain tissues. These results above suggested that MCAO-caused brain infarction was obviously alleviated by AGC. The immunohistochemistry data showed that AGC reduced neuronal injury and apoptosis, and inhibited microglia and astrocytes activation. The protein results suggested the expression of apoptosis-relevant proteins decreased among AGC treated groups and the neurotrophin related proteins were obviously enhanced by CREB/BDNF/TrkB/AKT and HSP70/Bcl-2/Bax pathways. Collectively, the results demonstrated that AGC primarily promoted neuro-nutrition, reduced the injury of nerve apoptosis and ameliorated neuroinflammation. In summary, AGC played a neuroprotective role, which had provided reliable evidence for AGC to be a potential drug in treating stroke.

Salidroside Exerts Beneficial Effect on Testicular Ischemia-Reperfusion Injury in Rats

Testicular torsion-detorsion results in testicular ischemia-reperfusion injury, which is associated with overgeneration of reactive oxygen species. Salidroside, a major bioactive ingredient extracted from Rhodiola rosea, has strong antioxidant activity. The purpose of this study was to examine the effect of salidroside on testicular ischemia-reperfusion injury. Sixty rats were randomly separated into 3 experimental groups: group A = sham-operated control; group B = testicular ischemia-reperfusion; and group C = testicular ischemia-reperfusion treated with salidroside. The rats in the sham-operated control group received all surgical procedures except testicular torsion-detorsion. The testicular ischemia-reperfusion group underwent 2 hours of left testicular torsion followed by detorsion. The rats in the salidroside-treated group received the same surgical procedure as in testicular ischemia-reperfusion group, but salidroside was injected intraperitoneally at reperfusion. Testicular malondialdehyde content (a reliable index of reactive oxygen species) and protein expression of superoxide dismutase and catalase which are primary antioxidant enzymes in testes were measured at 4 hours after reperfusion. Testicular spermatogenesis was evaluated at 3 months after reperfusion. The malondialdehyde content increased significantly, while superoxide dismutase and catalase protein expression and testicular spermatogenesis reduced significantly in ipsilateral testes of testicular ischemia-reperfusion group, as compared with sham-operated control group. Therapy with salidroside significantly reduced malondialdehyde content and significantly enhanced superoxide dismutase and catalase protein expression and spermatogenesis in ipsilateral testes, as compared with testicular ischemia-reperfusion group. The present findings indicate that treatment with salidroside ameliorates testicular ischemia-reperfusion injury by reducing reactive oxygen species level by upregulating superoxide dismutase and catalase protein expression.

Rhodiola rosea: A Therapeutic Candidate on Cardiovascular Diseases

Cardiovascular diseases, also known as circulatory diseases, are diseases of the heart and blood vessels, and its etiology is hyperlipidemia, thick blood, atherosclerosis, and hypertension. Due to its high prevalence, disability, and mortality, it seriously threatens human health. According to reports, the incidence of cardiovascular disease is still on the rise. Rhodiola rosea is a kind of traditional Chinese medicine, which has the effects of antimyocardial ischemia-reperfusion injury, lowering blood fat, antithrombosis, and antiarrhythmia. Rhodiola rosea has various chemical components, and different chemical elements have the same pharmacological effects and medicinal values for various cardiovascular diseases. This article reviews the research on the pharmacological effects of Rhodiola rosea on cardiovascular diseases and provides references for the clinical treatment of cardiovascular diseases.

Preclinical Evidence and Possible Mechanisms of Rhodiola rosea L. and Its Components for Ischemic Stroke: A Systematic Review and Meta-Analysis

Background: Rhodiola rosea L. has long been used as traditional medicines in Europe and Asia to treat a variety of common conditions and diseases including Alzheimer's disease, cardiovascular disease, cognitive dysfunctions, cancer, and stroke. Previous studies reported that Rhodiola rosea L. and its components (RRC) improve ischemia stroke in animal models. Here, we conducted a systematic review and meta-analysis for preclinical studies to evaluate the effects of RRC and the probable neuroprotective mechanisms in ischemic stroke. Methods: Studies of RRC on ischemic stroke animal models were searched in seven databases from inception to Oct 2021. The primary measured outcomes included the neural functional deficit score (NFS), infarct volume (IV), brain water content, cell viability, apoptotic cells, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL)-positive cells, B-cell lymphoma-2 (Bcl-2) level and tumor necrosis factor-α (TNF-α) level. The secondary outcome measures were possible mechanisms of RRC for ischemic stroke. All the data were analyzed via RevMan version 5.3. Results: 15 studies involving 345 animals were identified. Methodological quality for each included studies was accessed according to the CAMARADES 10-item checklist. The quality score of studies range from 1 to 7, and the median was 5.53. Pooled preclinical data showed that compared with the controls, RRC could improve NFS (Zea Longa (p < 0.01), modified neurological severity score (mNSS) (p < 0.01), rotarod tests (p < 0.01), IV (p < 0.01), as well as brain edema (p < 0.01). It also can increase cell viability (p < 0.01), Bcl-2 level (p < 0.01) and reduce TNF-α level (p < 0.01), TUNEL-positive cells (p < 0.01), apoptotic cells (p < 0.01). Conclusion: The findings suggested that RRC can improve ischemia stroke. The possible mechanisms of RRC are largely through antioxidant, anti-apoptosis activities, anti-inflammatory, repressing lipid peroxidation, antigliosis, and alleviating the pathological blood brain barrier damage.

Salidroside-pretreated mesenchymal stem cells contribute to neuroprotection in cerebral ischemic injury in vitro and in vivo

Mesenchymal stem cells (MSCs) are considered a promising tool for treating cerebral ischemic injury. However, their poor survival after transplantation limits their therapeutic effect and applications. Salidroside has been reported to exert potent cytoprotective and neuroprotective effects. This study aimed to investigate whether salidroside could improve MSC survival under hypoxic-ischemic conditions and, subsequently, alleviate cerebral ischemic injury in a rat model. MSCs were pretreated by salidroside under hypoxic-ischemic conditions. The cell proliferation, migratory capacity, and apoptosis were evaluated by means of Cell Counting Kit-8, transwell assay, and flow cytometry. MSCs pretreated with salidroside were transplanted into the rats subsequent to middle cerebral artery occlusion. The grip strength, 2,3,5-triphenyltetrazolium chloride, and hematoxylin-eosin staining were used to analyze the therapeutic efficiency and pathological changes. The mature neuron marker NeuN and astrocyte marker GFAP in the focal area were detected by immunofluorescence. These results indicated that salidroside promoted the proliferation, migration and reduced apoptosis of MSCs under hypoxic-ischemic conditions. In vivo experiments revealed that transplantation of salidroside-pretreated MSCs strengthened the therapeutic efficiency by enhancing neurogenesis and inhibiting neuroinflammation in the hippocampal CA1 area after ischemia. Our results suggest that pretreatment with salidroside could be an effective strategy to enhance the cell survival rate and the therapeutic effect of MSCs in treating cerebral ischemic injury.

Salidroside Improves Chronic Stress Induced Depressive Symptoms Through Microglial Activation Suppression

Depression is a severe neurological disorder highly associated with chronic mental stress stimulation, which involves chronic inflammation and microglial activation in the central nervous system (CNS). Salidroside (SLDS) has been reported to exhibit anti-neuroinflammatory and protective properties on neurological diseases. However, the mechanism underlying the effect of SLDS on depressive symptoms has not been well elaborated. In the present study, the effects of SLDS on depressive behaviors and microglia activation in mice CNS were investigated. Behavioral tests, including Forced swimming test (FST), Open field test (OFT) and Morris water maze (MWM) revealed that SLDS treatment attenuated the depressive behaviors in stress mice. SLDS treatment significantly reduced the microglial immunoreactivity for both Iba-1 and CD68, characteristic of deleterious M1 phenotype in hippocampus of stress mice. Additionally, SLDS inhibited microglial activation involving the suppression of ERK1/2, P38 MAPK and p65 NF-κB activation and thus reduced the expression and release of neuroinflammatory cytokines in stress mice as well as in lipopolysaccharide (LPS)-induced primary microglia. Also, SLDS changed microglial morphology, attachment and reduced the phagocytic ability in LPS-induced primary microglia. The results demonstrated that SLDS treatment could improve the depressive symptoms caused by unpredictable chronic stress, indicating a potential therapeutic application of SLDS in depression treatment by interfering microglia-mediated neuroinflammation.

Alisol A 24-acetate protects against brain microvascular endothelial cells injury through inhibiting miR-92a-3p/tight junctions axis

Blood brain barrier (BBB) dysfunction developed with aging is related to brain microvascular endothelial cells (BMECs) injury and losses of tight junctions (TJs). In the present study, we found that Alisol A 24-acetate (AA), a natural compound frequently used as treatment against vascular diseases was essential for BMECs injury and TJs degradation. Our experimental results showed that AA enhanced cell viability and increased zonula occludens-1 (ZO-1), claudin-5, and occludin expression in the oxygen-glucose deprivation (OGD)-induced BMECs. The exploration of the underlying mechanism revealed that AA restrained miR-92a-3p, a noncoding RNA involved in endothelial cells senescence and TJs impairment. To test the role of the miR-92a-3p in BMECs, the cells were transfected with miR-92a-3p mimics and inhibitor. The results showed that miR-92a-3p mimics inhibited cell viability and elevated lactate dehydrogenase (LDH) levels as well as suppressed ZO-1, claudin-5 and occludin expression, while the miR-92a-3p inhibitor reversed the above results. These findings were similar to the therapeutic effects of AA in the OGD-induced BMECs. Bioinformatics analysis and dual-luciferase assay confirmed ZO-1 and occludin were the target genes of miR-92a-3p mediated AA protective roles. In summary, the data demonstrated that AA protected against BMECs damage and TJs loss through the inhibition of miR-92a-3p expression. This provided evidence for AA application in aging-associated BBB protection.

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.

Recent advances in chemistry and bioactivity of Sargentodoxa cuneata

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Sargentodoxa comprises only one species, Sargentodoxa cuneata (Oliv.) Rehd et al., widely distributed in the subtropical zone of China. The plant is extensively used in traditional medicine for treating arthritis, joint pains, amenorrhea, acute appendicitis and inflammatory intestinal obstruction. Pharmacological studies show anti-inflammatory, antioxidant, antitumor, antimicrobial, and anti-sepsis activities.

AIM OF THE REVIEW

This review aims to summarize the information about distribution, traditional uses, chemical constituents and pharmacological activities of S. cuneata, as an attempt to provide a scientific basis for its traditional uses and to support its application and development for new drug development.

METHODOLOGY

Scientific information of S. cuneata was retrieved from the online bibliographic databases, including Web of Science, Google Scholar, PubMed, Springer Link, the Wiley online library, SciFinder, Baidu Scholar, China national knowledge infrastructure (CNKI) and WANFANG DATA (up to March 2020). We also search doctoral dissertations, master dissertations conference papers and published books. The keywords were used: "Sargentodoxa", "Da Xue Teng", "Hong Teng", "Xue Teng", "secondary metabolites", "chemical components", "biological activity", "pharmacology", "traditional uses".

OBSERVATIONS AND RESULTS

S. cuneata is utilized as valuable herbal medicines to treat various diseases in China. Over 110 chemical constituents have been isolated and identified from the stem of S. cuneata, including phenolic acids, phenolic glycosides, lignans, flavones, triterpenoids and other compounds. The extract and compounds of S. cuneata have a wide spectrum of pharmacological activities, including antitumor, anti-inflammatory, antioxidant, antimicrobial, anti-sepsis and anti-arthritis effects, as well as protective activity against cerebrovascular diseases.

CONCLUSION

S. cuneata has a rich legacy for the treatment of many diseases, especially arthritis and sepsis, which is reinforced by current investigations. However, the present studies about bioactive chemical constituents and detail pharmacological mechanisms of S. cuneata were insufficient. Further studies should focus on these aspects in relation to its clinical applications. This review has systematically summarized the traditional uses, phytochemical constituents and pharmacological effects of S. cuneata, providing references for the therapeutic potential of new drug development.

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.

Salidroside Inhibits Reactive Astrogliosis and Glial Scar Formation in Late Cerebral Ischemia via the Akt/GSK-3β Pathway

Cerebral ischemia leads to reactive astrogliosis and glial scar formation. Glial scarring can impede functional restoration during the recovery phase of stroke. Salidroside has been shown to have neuroprotective effects after ischemic stroke, but its impact on long-term neurological recovery, especially whether it regulates reactive astrogliosis and glial scar formation, is unclear. In this study, male adult C57/BL6 mice were subjected to transient cerebral ischemia injury followed by intravenous salidroside treatment. Primary astrocytes were treated with lipopolysaccharide (LPS) or conditioned medium from cultured primary neurons subjected to oxygen-glucose deprivation (CM-OGD). Salidroside significantly improved long-term functional outcomes following ischemic stroke in the rotarod and corner tests. It also reduced brain glial scar volume and decreased expression of the glial scar marker, glial fibrillary acidic protein (GFAP) and inhibited astrocyte proliferation. In primary astrocyte cultures, salidroside protected astrocytes from CM-OGD injury-induced reactive astroglial proliferation, increasing the percentage of cells in G0/G1 phase and reducing the S populations. The inhibitory effect of salidroside on the cell cycle was related to downregulation of cyclin D1 and cyclin-dependent kinase 4 (CDK4) mRNA expression and increased p27Kip1 mRNA expression. Similar results were found in the LPS-stimulated injury model in astroglial cultures. Western blot analysis demonstrated that salidroside attenuated the CM-OGD-induced upregulation of phosphorylated Akt and glycogen synthase kinase 3β (GSK-3β). Taken together, these results suggested that salidroside can inhibit reactive astrocyte proliferation, ameliorate glial scar formation and improve long-term recovery, probably through its effects on the Akt/GSK-3β pathway.

Reactive Oxygen Species/Caspase 3 Promotes Autophagy of Nigral Dopaminergic Neuron in Parkinson’s Disease

Parkinson’s disease (PD) is characterized as bradykinesia and sleep disorder, troubling numerous people. In the present study, we aimed to explore whether reactive oxygen species (ROS)/caspase 3 promotes PD to provide a basis for novel treatments of PD. Firstly, we applied 1-methyl-4-phenylpyridinium (MPP+) to stimulate PC12 cell lines to establish a PD cell model. Western blot and qRT-PCR analyses detected protein and mRNA expression of caspase 3, IL-1β, Bax, and BCL2. Finally, ROS detection kit determined ROS content. Compared with the controls, MPP+-treated PC12 exhibited significantly elevated caspase 3, caspase 3, and IL-1β at the protein level (p < 0.001). In addition, MMP + treatment increased Bax protein level in vitro, while decreased Bcl-2 protein expression (p <0.001). Moreover, MPP + induced oxidative stress which contributes to autophagy. The ROS in MPP + group was increased significantly (p < 0.001). ROS and caspase 3 participate in the pathogenesis of PD and enhances autophagy of nigral dopaminergic neuron.

Effects of rhodioloside on the neurological functions of rats with total cerebral ischemia/reperfusion and cone neuron injury in the hippocampal CA1 region

Rhodioloside, the main effective constituent of Rhodiola rosea, demonstrates antiaging and antioxidative stress functions and inhibits calcium overloading in cells. These functions imply that rhodioloside may exert protective effects on hippocampal neurons after total cerebral ischemia/reperfusion injury. In this study, male Wistar rat models of total cerebral ischemia were constructed and randomly divided into four groups: sham-operation, ischemia/reperfusion, low-dosage, and high-dosage groups. The result showed that rhodioloside treatment reduced the apoptosis rates of hippocampal neurons and the histological grades of cone cells in the hippocampal CA1 region, but neuronal density was significantly increased. Besides, the protein expressions of Bcl-2/Bax and p53 were measured and found Bcl-2/Bax was increased and p53 protein level was reduced. Therefore, rhodioloside might have protective effects on rats with ischemia/reperfusion brain injury.

Antioxidant Effects of Salidroside in the Cardiovascular System

Cardiovascular disease is one of the main human health risks, and the incidence is increasing. Salidroside is an important bioactive component of Rhodiola rosea L., which is used to treat Alzheimer's disease, tumor, depression, and other diseases. Recent studies have shown that salidroside has therapeutic effects, to some degree, in cardiovascular diseases via an antioxidative mechanism. However, evidence-based clinical data supporting the effectiveness of salidroside in the treatment of cardiovascular diseases are limited. In this review, we discuss the effects of salidroside on cardiovascular risk factors and cardiovascular diseases and highlight potential antioxidant therapeutic strategies.

Salidroside as a potential neuroprotective agent for ischemic stroke: a review of sources, pharmacokinetics, mechanism and safety

Salidroside (Sal) is a bioactive extract principally from traditional herbal medicine such as Rhodiola rosea L., which has been commonly used for hundreds of years in Asia countries. The excellent neuroprotective capacity of Sal has been illuminated in recent studies. This work focused on the source, pharmacokinetics, safety and anti-ischemic stroke (IS) effect of Sal, especially emphasizing its mechanism of action and BBB permeability. Extensive databases, including Pubmed, Web of science (WOS), Google Scholar and China National Knowledge Infrastructure (CNKI), were applied to obtain relevant online literatures. Sal exerts powerful therapeutic effects on IS in experimental models either in vitro or in vivo due to its neuroprotection, with significantly diminishing infarct size, preventing cerebral edema and improving neurological function. Also, the findings suggest the underlying mechanisms involve anti-oxidation, anti-inflammation and anti-apoptosis by regulating multiple signaling pathways and key molecules, such as NF-κB, TNF-α and PI3K/Akt pathway. In pharmacokinetics, although showing a rapid absorption and elimination, bioavailability of Sal is elevated under some non-physiological conditions. The component and its metabolite (tyrosol) are capable of distributing to brain tissue and the later keeps a higher level of concentration. Moreover, Sal scarcely has obvious toxicity or side effects in a variety of animal experiments and clinical trials, but combination of drugs and perinatal use of medicine should be taken more attentions. Finally, as an active ingredient, not only is Sal isolated from diverse plants with limited yield, but also large batches of the products can be harvested by biological and chemical synthesis. With higher efficacy and better safety profiles, Sal could sever as a promising neuroprotectant for preventing and treating IS. Nevertheless, further investigations are still required to explore the pharmacodynamic and pharmacokinetic properties of Sal in the treatment of IS.

Neuroprotective effects of miR-532-5p against ischemic stroke

Stroke can cause death and disability and has a high incidence with many complications. So far, effective treatment options for stroke are still limited. MicroRNA-532-5p (miR-532-5p) is significantly downregulated in stroke. However, the role of miR-532-5p in ischemic stroke is still unclear. In this study, we established an in vivo middle cerebral artery occlusion (MCAO) model in mice. The expression level of miR-532-5p, neurological score, infarct area, neuronal apoptosis, and phosphoinositide 3-kinase (PI3K)/Akt signaling pathway-related molecules were examined. Low miR-532-5p levels and high phosphatase and tensin homolog deleted on chromosome 10 (PTEN) levels were detected in the mouse MCAO model. MiR-532-5p overexpression improved neurological dysfunction, reduced the infarct area, attenuated neuronal injury and apoptosis, and promoted the activation of the PI3K/Akt signaling pathway in MCAO mice. In vitro, we treated mouse neuroblastoma cells (N2a) with oxygen-glucose deprivation and reperfusion (OGD/R). The expression level of miR-532-5p, cell viability, cell apoptosis, and the PI3K/Akt signaling pathway-related molecules were detected. Consistent with the in vivo tests, the miR-532-5p level was decreased and the PTEN level was increased in OGD-treated N2a cells in vitro. The miR-532-5p mimic increased cell viability, decreased cell apoptosis, and activated the PI3K/Akt signaling pathway. Furthermore, PTEN was verified as a target gene of miR-532-5p by luciferase reporter assay. PTEN overexpression attenuated the protective effect of miR-532-5p in OGD-treated N2a cells. In summary, these findings reveal that miR-532-5p protects against ischemic stroke by inhibiting PTEN and activating the PI3K/Akt signaling pathway and may serve as a novel therapeutic target for ischemic stroke.