Icariin Prevents Amyloid Beta-Induced Apoptosis via the PI3K/Akt Pathway in PC-12 Cells

Icariin improves cognitive impairment by inhibiting ferroptosis of nerve cells

AIM

We investigated the effect and mechanism of Icariin (ICA) on improving neurobehavioral ability of mice with Alzheimer's disease (AD).

METHODS

We selected 10-month-old APP/PS1 mice (AD) and wild-type C57BL/6J mice (Normal). After intragastric administration of ICA, Morris water maze was employed to detect neurobehavioral improvements, and to assay key ferroptosis indicators and oxidative stress levels. The common target of ICA for resisting ferroptosis and AD was predicted by network pharmacology.

RESULTS

ICA could improve the neurobehavioral, memory and motor abilities of AD mice. It could lower the ferroptosis level and enhance the resistance to oxidative stress. After inhibition of MDM2, ICA could no longer improve the cognitive ability of AD mice, nor could it further inhibit ferroptosis. Network pharmacological analysis revealed that MDM2 might be the target of ICA action.

CONCLUSIONS

We found that ICA can inhibit ferroptosis of nerve cells, thereby ameliorating neural damage in mice with AD.

Molecular mechanisms regulating the pharmacological actions of icariin with special focus on PI3K-AKT and Nrf-2 signaling pathways

Icariin is a primary active component of the traditional Chinese medicinal plant Epimedium grandiflorum. A range of pharmacological effects of icariin has been researched by modern science to explain its traditional medicinal uses. Attributing to the wide range of pharmacological properties like anti-osteoporosis, anti-inflammation, anti-oxidative stress, anti-depression, and anti-tumor property possessed by icariin, it is now being considered a potential therapeutic agent for a wide variety of disorders ranging from neoplasm, neurodegenerative disorders, osteoporosis, and cardiovascular diseases. Various signaling pathways including NFκB/NALP3, IGF-1, MiR-223-3p/ NALP3, TLR4/ NFκB, and WNT1/β-catenin are involved in the different biological actions exerted by icariin. Apart from these pathways, PI3K-AKT (Phosphoinositide 3 kinase-Protein kinase B) and Nrf-2 (nuclear erythroid 2-related factor 2) signaling pathways are two important pathways that form the fundamental basis for the pharmaceutical efficacy of icariin. This review gives an overview of previous in vitro and in vivo studies that investigated the potential role of icariin via PI3K-AKT and Nrf-2 signaling pathways to provide greater insights into its potential clinical use in a variety of disorders.

The neuroprotective effects of icariin on ageing, various neurological, neuropsychiatric disorders, and brain injury induced by radiation exposure

Epimedium brevicornum Maxim, a Traditional Chinese Medicine, has been used for the treatment of impotence, sinew and bone disorders, “painful impediment caused by wind-dampness,” numbness, spasms, hypertension, coronary heart disease, menopausal syndrome, bronchitis, and neurasthenia for many years in China. Recent animal experimental studies indicate that icariin, a major bioactive component of epimedium may effectively treat Alzheimer’s disease, cerebral ischemia, depression, Parkinson’s disease, multiple sclerosis, as well as delay ageing. Our recent study also suggested that epimedium extract could exhibit radio-neuro-protective effects and prevent ionizing radiation-induced impairment of neurogenesis. This paper reviewed the pharmacodynamics of icariin in treating different neurodegenerative and neuropsychiatric diseases, ageing, and radiation-induced brain damage. The relevant molecular mechanisms and its anti-neuroinflammatory, anti-apoptotic, anti-oxidant, as well as pro-neurogenesis roles were also discussed.

PI3K/Akt Signaling Pathway Ameliorates Oxidative Stress-Induced Apoptosis upon Manganese Exposure in PC12 Cells

Manganese (Mn)-induced neurotoxicity has aroused public concerns for many years, but its precise mechanism is still poorly understood. Herein, we report the impacts of the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway in mediating neurological effects induced by manganese sulfate (MnSO₄) exposure in PC12 cells. In this study, cells were treated with MnSO₄ for 24 h in the absence or presence of LY294002 (a special inhibitor of PI3K). We investigated cell viability and apoptosis signals, as well as levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and malondialdehyde (MDA). The mRNA levels of B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), and Caspase-3 were also quantified through real-time quantitative PCR (RT-qPCR); protein levels of serine/threonine protein kinase (Akt) and forkhead box O3A (Foxo3a) were determined by western blot. Increasing of MnSO₄ doses led to decreased SOD, GSH-Px, and CAT activities, while the level of MDA was upregulated. Moreover, cell apoptosis was significantly increased, as the mRNA of Bcl-2 and Caspase-3 was significantly decreased, while Bax mRNA was increased. Phosphorylated Akt (p-Akt) and Foxo3a (p-Foxo3a) were upregulated in a dose-dependent manner. In addition, LY294002 pretreatment reduced the activity of SOD, GSH-Px, and CAT but elevated MDA levels. Meanwhile, LY294002 pretreatment also increased cell apoptosis given the upregulated Bax and Caspase-3 mRNAs and decreased Bcl-2 mRNA. In summary, the PI3K/Akt signaling pathway can be activated by MnSO₄ exposure and mediate MnSO₄-induced neurotoxicity.

Icariin Ameliorates Alzheimer's Disease Pathology by Alleviating Myelin Injury in 3 × Tg-AD Mice

Alzheimer's disease (AD) is a neurodegenerative disease characterized by excessive deposition of β amyloid (Aβ), hyperphosphorylation of tau protein, and neuronal cell death. Recent studies have shown that myelin cell damage, which leads to cognitive dysfunction, occurs before AD-related pathological changes. Here, we examine the effect of icariin (ICA), a prenylated flavonol glycoside, in improving cognitive function in AD model mice. ICA has been reported to exhibit cardiovascular protective functions and antiaging effects. In this study, we used 3 × Tg-AD mice as an AD model. The Morris water maze and Y maze tests were performed to assess the learning and memory of the mice. Immunofluorescence analysis of Aβ1-42 deposition and myelin basic protein (MBP) expression in the mouse hippocampus was performed. Tau protein phosphorylation and MBP protein expression in the hippocampus were further analyzed by Western blotting. Myelin damage in the mouse optic nerve was evaluated by electron microscopy, and LFB staining was performed to assess myelin morphology in the mouse corpus callosum. MBP, Mpp5, and Egr2 transcript levels were quantified by qPCR. We observed that ICA treatment improved the learning and memory of 3 × Tg-AD mice and reduced Aβ deposition and tau protein phosphorylation in the hippocampus. Moreover, this treatment protocol increased myelin-related gene expression and reduced myelin damage.

Senegenin Inhibits Aβ1-42-Induced PC12 Cells Apoptosis and Oxidative Stress via Activation of the PI3K/Akt Signaling Pathway

BACKGROUND/AIM

Apoptosis and oxidative stress have been considered as key events in the pathogenesis of Alzheimer's disease (AD). Senegenin (Sen), the major and most effective ingredient of Radix Polygalae, which has anti-apoptotic and anti-oxidative effects. The aim of this study was to investigate the anti-apoptotic and anti-oxidant effects of Sen on Aβ_1-42-induced PC12 cells apoptosis and oxidative stress as well as its possible signaling pathway.

METHODS

Rat pheochromocytoma (PC12) cells were treated by 20 μM Aβ_1-42 and then divided into 5 different treatment groups (Control; Aβ_1-42 20 μM; Aβ_1-42 20 μM + Sen 10 μM; Aβ_1-42 20 μM + Sen 30 μM; Aβ_1-42 20μM + Sen 60 μM). PC12 cells activity was detected by MTT assay. Colony formation assay was performed to assess the clonogenic ability of cells. The cell apoptosis was detected by Annexin-V/PI staining. The pro-apoptotic protein (Bax), anti-apoptotic protein (Bcl-2), anti-oxidative stress factor (HO-1, Nuclear Nrf2, Total Nrf2) and pathway-related protein (Akt, P-Akt, PI3K, P-PI3K) were tested by Western blot. The reactive oxygen species (ROS) level was assessed with a DCFH-DA probe.

RESULTS

The results indicated that Sen dose-dependently increased cell viability and reduced the number of apoptotic cells. The ratio of P-PI3K/PI3K and P-Akt/Akt increased in a dose-dependent manner under the treatment of Sen, suggesting that Sen might activate the PI3K/Akt signaling pathway. Moreover, Sen upregulates the ratio of Bcl-2/Bax. Further study revealed that Sen can play an antioxidant role in enhancing HO-1, promoting Nrf2 nuclear translocation and reducing ROS accumulation to reduce oxidative stress.

CONCLUSION

Sen is effective in inhibiting apoptosis and oxidative stress in Aβ_1-42-induced PC12 cells, which likely contribute to the development of novel therapies for AD.

Apoptotic Pathways and Alzheimer's Disease: Probing Therapeutic Potential

Apoptosis is an intrinsic biochemical, cellular process that regulates cell death and is crucial for cell survival, cellular homeostasis, and maintaining the optimum functional status. Apoptosis in a predetermined and programmed manner regulates several molecular events, including cell turnover, embryonic development, and immune system functions but may be the exclusive contributor to several disorders, including neurodegenerative manifestations, when it functions in an aberrant and disorganized manner. Alzheimer's disease (AD) is a fatal, chronic neurodegenerative disorder where apoptosis has a compelling and divergent role. The well-characterized pathological features of AD, including extracellular plaques of amyloid-beta, intracellular hyperphosphorylated tangles of tau protein (NFTs), inflammation, mitochondrial dysfunction, oxidative stress, and excitotoxic cell death, also instigate an abnormal apoptotic cascade in susceptible brain regions (cerebral cortex, hippocampus). The apoptotic players in these regions affect cellular organelles (mitochondria and endoplasmic reticulum), interact with trophic factors, and several pathways, including PI3K/AKT, JNK, MAPK, mTOR signalling. This dysregulated apoptotic cascade end with an abnormal neuronal loss which is a primary event that may precede the other events of AD progression and correlates well with the degree of dementia. The present review provides insight into the diverse and versatile apoptotic mechanisms that are indispensable for neuronal survival and constitute an integral part of the pathological progression of AD. Identification of potential targets (restoring apoptotic and antiapoptotic balance, caspases, TRADD, RIPK1, FADD, TNFα, etc.) may be valuable and advantageous to decide the fate of neurons and to develop potential therapeutics for treatment of AD.

Activation of IGF-1 pathway and suppression of atrophy related genes are involved in Epimedium extract (icariin) promoted C2C12 myotube hypertrophy

The regenerative effect of Epimedium and its major bioactive flavonoid icariin (ICA) have been documented in traditional medicine, but their effect on sarcopenia has not been evaluated. The aim of this study was to investigate the effects of Epimedium extract (EE) on skeletal muscle as represented by differentiated C2C12 cells. Here we demonstrated that EE and ICA stimulated C2C12 myotube hypertrophy by activating several, including IGF-1 signal pathways. C2C12 myotube hypertrophy was demonstrated by enlarged myotube and increased myosin heavy chains (MyHCs). In similar to IGF-1, EE/ICA activated key components of the IGF-1 signal pathway, including IGF-1 receptor. Pre-treatment with IGF-1 signal pathway specific inhibitors such as picropodophyllin, LY294002, and rapamycin attenuated EE induced myotube hypertrophy and MyHC isoform overexpression. In a different way, EE induced MHyC-S overexpression can be blocked by AMPK, but not by mTOR inhibitor. On the level of transcription, EE suppressed myostatin and MRF4 expression, but did not suppress atrogenes MAFbx and MuRF1 like IGF-1 did. Differential regulation of MyHC isoform and atrogenes is probably due to inequivalent AKT and AMPK phosphorylation induced by EE and IGF-1. These findings suggest that EE/ICA stimulates pathways partially overlapping with IGF-1 signaling pathway to promote myotube hypertrophy.

PC12 and THP-1 Cell Lines as Neuronal and Microglia Model in Neurobiological Research

Models based on cell cultures have become a useful tool in modern scientific research. Since primary cell lines are difficult to obtain and handle, neoplasm-derived lines like PC12 and THP-1 offer a cheap and flexible solution for neurobiological studies but require prior differentiation to serve as a neuronal or microglia model. PC12 cells constitute a suitable research model only after differentiation by incubation with nerve growth factor (NGF) and THP-1 cells after administering a differentiation factor such as phorbol 12-myristate-13-acetate (PMA). Still, quite often, studies are performed on these cancer cells without differentiation. The study aimed to assess the impact of PC12 or THP-1 cell differentiation on sensitivity to harmful factors such as Aβ25-35 (0.001–5 µM) (considered as one of the major detrimental factors in the pathophysiology of Alzheimer’s disease) or lipopolysaccharide (1–100 µM) (LPS; a pro-inflammatory factor of bacterial origin). Results showed that in most of the tests performed, the response of PC12 and THP-1 cells induced to differentiation varied significantly from the effect in undifferentiated cells. In general, differentiated cells showed greater sensitivity to harmful factors in terms of metabolic activity and DNA damage, while in the case of the free radicals, the results were heterogeneous. Obtained data emphasize the importance of proper differentiation of cell lines of neoplastic origin in neurobiological research and standardization of cell culture handling protocols to ensure reliable results.

A Network Pharmacology Approach to Estimate Potential Targets of the Active Ingredients of Epimedium for Alleviating Mild Cognitive Impairment and Treating Alzheimer's Disease

BACKGROUND

The present study made use of a network pharmacological approach to evaluate the mechanisms and potential targets of the active ingredients of Epimedium for alleviating mild cognitive impairment (MCI) and treating Alzheimer's disease (AD).

METHODS

The active ingredients of Epimedium were acquired from the Traditional Chinese Medicine System Pharmacology database, and potential targets were predicted using the TCMSP target module, SwissTargetPrediction, and PharmMapper database. Target proteins correlating with MCI and AD were downloaded from the GeneCards, DisGeNet, and OMIM databases. The common targets of Epimedium, MCI, and AD were identified using the Jvenn online tool, and a protein-protein interaction (PPI) network was constructed using the String database and Cytoscape. Finally, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of the common targets was performed using DAVID, and molecular docking between active ingredients and target genes was modeled using AutoDock Vina.

RESULTS

A total of 20 active ingredients were analyzed, and 337 compound-related targets were identified for Epimedium. Out of 236 proteins associated with MCI and AD, 54 overlapped with the targets of Epimedium. The top 30 interacting proteins in this set were ranked by topological analysis. GO and KEGG enrichment analysis suggested that the common targets participated in diverse biological processes and pathways, including cell proliferation and apoptosis, inflammatory response, signal transduction, and protein phosphorylation through cancer pathway, MAPK signaling pathway, PI3K-Akt signaling pathway, HIF-1 signaling pathway, sphingolipid signaling pathway, FoxO signaling pathway, and TNF signaling pathway. Molecular docking analysis suggested that the 20 active ingredients could bind to the top 5 protein targets.

CONCLUSIONS

The present study provides theoretical evidence for in-depth analysis of the mechanisms and molecular targets by which Epimedium protects against MCI, AD, and other neurodegenerative diseases and lays the foundation for pragmatic clinical applications and potential new drug development.

Standardized Bacopa monnieri Extract Ameliorates Learning and Memory Impairments through Synaptic Protein, Neurogranin, Pro-and Mature BDNF Signaling, and HPA Axis in Prenatally Stressed Rat Offspring

Prenatal stress (PNS) influences offspring neurodevelopment, inducing anxiety-like behavior and memory deficits. We investigated whether pretreatment of Bacopa monnieri extract (CDRI-08/BME) ameliorates PNS-induced changes in signaling molecules, and changes in the behavior of Wistar rat offspring. Pregnant rats were randomly assigned into control (CON)/prenatal stress (PNS)/PNS and exposed to BME treatment (PNS + BME). Dams were exposed to stress by placing them in a social defeat cage, where they observed social defeat from gestational day (GD)-16–18. Pregnant rats in the PNS + BME group were given BME treatment from GD-10 to their offspring’s postnatal day (PND)-23, and to their offspring from PND-15 to -30. PNS led to anxiety-like behavior; impaired memory; increased the level of corticosterone (CORT), adrenocorticotropic hormone, glucocorticoid receptor, pro-apoptotic Casepase-3, and 5-HT_2C receptor; decreased anti-apoptotic Bcl-2, synaptic proteins (synaptophysin, synaptotagmin-1), 5-HT_1A, receptor, phosphorylation of calmodulin-dependent protein kinase II/neurogranin, N-methyl-D-aspartate receptors (2A,2B), postsynaptic density protein 95; and conversion of pro and mature brain derived neurotropic factor in their offspring. The antioxidant property of BME possibly inhibiting the PNS-induced changes in observed molecules, anxiety-like behavior, and memory deficits. The observed results suggest that pretreatment of BME could be an effective coping strategy to prevent PNS-induced behavioral impairments in their offspring.

Identification and Analysis of Components in Yizhi Granule and Cynomolgus Monkey Plasma after Oral Administration by UPLC/ESI-Q-TOF MS and Their Protective Effects on PC12 Cells

Yizhi Granule (YZG) is a health food containing six traditional Chinese medicines (TCMs). It improves memory barriers in rat experiments. Here, we describe the first fast and sensitive ultraperformance liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC/ESI-Q-TOF MS) method for analyzing YZG in plasma. We used this technique for studies in cynomolgus monkey plasma. By comparing retention time, MS, and MS/MS data of reference compounds, 70 compounds were detected in YZG. Of these, 63 were identified including 60 saponins, 2 flavones, and 1 methyl ester. There were 33 saponins, 1 flavone, and 1 methyl ester in the plasma. Next, to study the therapeutic properties of YZG, the neuroprotective effect of some of the absorbed components was evaluated using PC12 cell damage caused by the Aβ _25-35 model. The results showed that 9 compounds protect PC12 cells from Aβ _25-35 with cell viability (%) of 111.00 ± 8.12 (G-Rb1), 102.20 ± 4.22 (G-Rb2), 100.34 ± 6.47 (G-Rd), 102.83 ± 2.10 (G-Re), 101.68 ± 7.64 (NG-Fa), 101.19 ± 7.83 (NG-R1), 102.53 ± 0.55 (NG-R2), 106.88 ± 4.95 (gypenoside A), and 103.95 ± 4.11 (gypenoside XLIX), respectively, versus the control group (87.51 ± 6.59). These results can reveal the real pharmacodynamic basis of YZG and provide a theoretical basis for subsequent studies. It can also provide some references for the research of Alzheimer's disease.

Icariin and Its Metabolites as Potential Protective Phytochemicals Against Alzheimer's Disease

Alzheimer’s disease (AD) is a neurodegenerative disorder affecting more than 35 million people worldwide. As the prevalence of AD is dramatically rising, there is an earnest need for the identification of effective therapies. Available drug treatments only target the symptoms and do not halt the progression of this disorder; thus, the use of natural compounds has been proposed as an alternative intervention strategy. Icariin, a prenylated flavonoid, has several therapeutic effects, including osteoporosis prevention, sexual dysfunction amelioration, immune system modulation, and improvement of cardiovascular function. Substantial studies indicate that icariin may be beneficial to AD by reducing the production of extracellular amyloid plaques and intracellular neurofibrillary tangles and inhibiting phosphodiesterase-5 activity. Moreover, increasing evidence has indicated that icariin exerts a protective role in AD also by limiting inflammation, oxidative stress and reducing potential risk factors for AD such as atherosclerosis. This mini-review discusses the multiple potential mechanisms of action of icariin on the pathobiology of AD including explanation regarding its bioavailability, metabolism and pharmacokinetic.

Icariin Activates Autophagy via Down-Regulation of the NF-κB Signaling-Mediated Apoptosis in Chondrocytes

Osteoarthritis (OA) is a common chronic and degenerative joint condition that is mainly characterized by cartilage degradation, osteophyte formation, and joint stiffness. The NF-κB signaling pathway in inflammation, autophagy, and apoptosis plays a prominent role in the progression of OA. Icariin, a prenylated flavonol glycoside extracted from Epimedium, have been proven to exert anti-osteoporotic and anti-inflammatory effects in OA. However, the action mechanisms of its effect on chondrocytes have yet to be elucidated. In the present study, we demonstrated that the in vitro therapeutic effects of icariin on rat chondrocytes in a dose-dependent manner. We found that TNF-α induced the production of IL-1, IL-6, IL-12, reactive oxygen species (ROS), nitric oxide (NO), Caspase-3, and Caspase-9 in chondrocytes. We also provided evidence that TNF-α inhibited autophagy markers (Atg 5, Atg 7) and prevented LC3 I translate to LC3 II. Furthermore, TNF-α induced matrix metalloproteinase (MMP)3 and MMP9 expression. The negative effects of TNF-α on chondrocytes can be partially blocked by treating with icariin or ammonium pyrrolidinedithiocarbamate (PDTC, an NF-κB inhibitor). The present study data also suggested that icariin suppressed both TNF-α-stimulated p65 nuclear translocation and IκBα protein degradation. These results indicated that icariin protected against OA by suppressing inflammatory cytokines and apoptosis, through activation of autophagy via NF-κB inhibition. In conclusion, icariin appears to favorably modulate autophagy and apoptosis in chondrocytes making it a promising compound for cartilage tissue engineering in the treatment of OA.

Icariin Prevents IL-1β-Induced Apoptosis in Human Nucleus Pulposus via the PI3K/AKT Pathway

Purpose

To explore the effect and possible mechanism of icariin, a prenylated flavonol glycoside derived from the Chinese herb Epimedium sagittatum that was applied to IL-1β pretreated human nucleus pulposus (NP) cells.

Methods

Human NP cells were isolated from intervertebral discs of patients with scoliosis and lumbar spondylolisthesis. The cells were divided into five groups: A (blank control); B (20 ng/ml IL-1β); C (20 ng/ml IL-1β + 20 μM icariin); D (20 μM icariin + 20 ng/ml IL-1β + 25 μM LY294002); E (20 ng/ml IL-1β + 25 μM LY294002). For each of the five groups, the CCK8, apoptosis rates, ROS rates, and JC-1 rates were determined and an electron micrograph was performed. Different expression levels of apoptosis proteins and proteins in the PI3K/AKT pathway were detected via western blot.

Results

We found that the damage effects on human nucleus pulposus cells from 20 ng/ml of IL-1β exposure were attenuated by icariin. When the PI3K/AKT pathway was blocked by LY294002, a specific inhibitor of this pathway, the protective effect of icariin was impaired. In summary, icariin might be a protective traditional Chinese medicine, which prevents inflammation-induced degeneration of intervertebral discs partly through the PI3K/AKT pathway.

Protective effects of Bushen Tiansui decoction on hippocampal synapses in a rat model of Alzheimer's disease

Bushen Tiansui decoction is composed of six traditional Chinese medicines: Herba Epimedii, Radix Polygoni multiflori, Plastrum testudinis, Fossilia Ossis Mastodi, Radix Polygalae, and Rhizoma Acorus tatarinowii. Because Bushen Tiansui decoction is effective against amyloid beta (Aβ) toxicity, we hypothesized that it would reduce hippocampal synaptic damage and improve cognitive function in Alzheimer's disease. To test this hypothesis, we used a previously established animal model of Alzheimer's disease, that is, microinjection of aggregated Aβ25-35 into the bilateral brain ventricles of Sprague-Dawley rats. We found that long-term (28 days) oral administration of Bushen Tiansui decoction (0.563, 1.688, and 3.375 g/mL; 4 mL/day) prevented synaptic loss in the hippocampus and increased the expression levels of synaptic proteins, including postsynaptic density protein 95, the N-methyl-D-aspartate receptor 2B subunit, and Shank1. These results suggested that Bushen Tiansui decoction can protect synapses by maintaining the expression of these synaptic proteins. Bushen Tiansui decoction also ameliorated measures reflecting spatial learning and memory deficits that were observed in the Morris water maze (i.e., increased the number of platform crossings and the amount of time spent in the target quadrant and decreased escape latency) following intraventricular injections of aggregated Aβ25-35 compared with those measures in untreated Aβ25-35-injected rats. Overall, these results provided evidence that further studies on the prevention and treatment of dementia with this traditional Chinese medicine are warranted.

Icariin Attenuates Synaptic and Cognitive Deficits in an Aβ1-42-Induced Rat Model of Alzheimer's Disease

Icariin (ICA), a prenylated flavanol glycoside present in abundant quantities in Epimedium sagittatum, has shown promise in the treatment and prevention of Alzheimer's disease. Damage to synaptic plasticity induced by amyloid-beta-mediated neurotoxicity is considered a main pathological mechanism driving the learning and memory deficits present in patients with Alzheimer's disease. This study investigated the neuroprotective effects of icariin in an Aβ_1–42-induced rat model of Alzheimer's disease. Our results showed that Aβ_1–42 injection induced loss of learning and memory behaviour in the Morris water maze, which could be reversed with intragastric administration of ICA. Furthermore, ICA reversed decreases in PSD-95, BDNF, pTrkB, pAkt, and pCREB expressions and prevented deterioration of synaptic interface structure. These findings indicate that ICA may improve synaptic plasticity through the BDNF/TrkB/Akt pathway and provide further evidence for its clinical application to improve learning and memory in patients with Alzheimer's disease.

Effects and mechanism of dexmedetomidine on neuronal cell injury induced by hypoxia-ischemia

BACKGROUND

The present study aims to investigate the protective effects of dexmedetomidine (DMED) on hypoxia ischemia injury induced by oxygen and glucose deprivation (OGD) in PC12 and primary neuronal cells.

METHODS

PC12 cells exposed to OGD was used to establish ischemia model. The OGD-induced cell injury was evaluated by alterations of cell viability, apoptosis and expressions of apoptosis-associated proteins. Oxidative stress and expressions of neurotrophic factors after OGD and DMED treatments were also explored. The activation of possible involved signaling pathways were studied after OGD and DMED treatments, along with the addition of inhibitors of these pathways. Finally, the effects of DMED on primary neuronal cells were verified according to the alterations of inflammatory cytokines release and oxidative stress.

RESULTS

DMED obviously increased cell viability and reduced cell apoptosis as well as ratio of Bax/Bcl-2 in OGD-treated PC12 cells. Then, the OGD-induced changes of LDH, MDA, SOD and GSH-Px as well as decreases of neurotrophic factors were all ameliorated by DMED treatment. Key kinases in Notch/NF-κB signaling pathway were up-regulated by OGD, whereas the up-regulations were decreased by DMED. In addition, inhibitor of Notch or NF-κB could augment the effects of DMED on OGD-induced cell injury. Finally, the protective effects of DMED were verified in primary neuronal cells.

CONCLUSION

DMED had protective effect on OGD-induced PC12 cell injury, depending on its anti-apoptotic, anti-oxidative activity and the inhibition of Notch/NF-κB activation. Our findings suggested that DMED could be used as a potential therapeutic drug for cerebral ischemia.

Icariin Prevents H2O2-Induced Apoptosis via the PI3K/Akt Pathway in Rat Nucleus Pulposus Intervertebral Disc Cells

Icariin is a prenylated flavonol glycoside derived from the Chinese herb Epimedium sagittatum. This study investigated the mechanism by which icariin prevents H₂O₂-induced apoptosis in rat nucleus pulposus (NP) cells. NP cells were isolated from the rat intervertebral disc and they were divided into five groups after 3 passages: (A) blank control; (B) 200 μM H₂O₂; (C) 200 μM H₂O₂ + 20 μM icariin; (D) 20 μM icariin + 200 μM H₂O₂ + 25 μM LY294002; (E) 200 μM H₂O₂ + 25 μM LY294002. LY294002 is a selective inhibitor of the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. NP cell viability, apoptosis rate, intracellular reactive oxygen species levels, and the expression of AKT, p-AKT, p53, Bcl-2, Bax, caspase-3 were estimated. The results show that, compared with the control group, H₂O₂ significantly increased NP cell apoptosis and the level of intracellular ROS. Icariin pretreatment significantly decreased H₂O₂-induced apoptosis and intracellular ROS and upregulated p-Akt and BCL-2 and downregulated caspase-3 and Bax. LY294002 abolished the protective effects of icariin. Our results show that icariin can attenuate H2O2-induced apoptosis in rat nucleus pulposus cells and PI3K/AKT pathway is at least partly included in this protection effect.

Pharmacological Effects of Active Components of Chinese Herbal Medicine in the Treatment of Alzheimer's Disease: A Review

Alzheimer's disease (AD), the most common neurodegenerative disorder associated with dementia, not only severely decreases the quality of life for its victims, but also brings a heavy economic burden to the family and society. Unfortunately, few chemical drugs designed for clinical applications have reached the expected preventive or therapeutic effect so far, and combined with their significant side-effects, there is therefore an urgent need for new strategies to be developed for AD treatment. Traditional Chinese Medicine has accumulated many experiences in the treatment of dementia during thousands of years of practice; modern pharmacological studies have confirmed the therapeutic effects of many active components derived from Chinese herbal medicines (CHM). Ginsenoside Rg1, extracted from Radix Ginseng, exerts a [Formula: see text]-secretase inhibitor effect so as to decrease A[Formula: see text] aggregation. It can also inhibit the apoptosis of neuron cells. Tanshinone IIA, extracted from Radix Salviae miltiorrhizae, and baicalin, extracted from Radix Scutellariae[Formula: see text] can inhibit the oxidative stress injury in neuronal cells. Icariin, extracted from Epimedium brevicornum, can decrease A[Formula: see text] levels and the hyperphosphorylation of tau protein, and can also inhibit oxidative stress and apoptosis. Huperzine A, extracted from Huperzia serrata, exerts a cholinesterase inhibitor effect. Evodiamine, extracted from Fructus Evodiae, and curcumin, extracted from Rhizoma Curcumae Longae, exert anti-inflammatory actions. Curcumin can act on A[Formula: see text] and tau too. Due to the advantages of multi-target effects and fewer side effects, Chinese medicine is more appropriate for long-term use. In this present review, the pharmacological effects of commonly used active components derived from Chinese herbal medicines in the treatment of AD are discussed.

Mechanisms of Heshouwuyin in regulating apoptosis of testicular cells in aging rats through mitochondrial pathway

BACKGROUND

Polygonum multiflorum has important effects on anti-aging and immunity enhancement. Many traditional Chinese medicine preparations based on Polygonum multiflorum are widely used for the clinical prevention and treatment of aging. However the mechanisms of these herb mixtures are often unknown. This study investigates the effect of Heshouwuyin, a Chinese herbal compound for invigorating the kidney, on the regulation of testicular cells apoptosis in aging rats.

METHODS

In this study, 18-month-old Wistar rats served as a model of natural aging and 12-month-old rats served as a young control group. Heshouwuyin group 1 and group 2 were comprised 18-month-old rats given Heshouwuyin intragastrically for 60 days and 30 days respectively. Then testes of the young control group were isolated in the age of 12 months, the other three groups were in the age of 18 months.

RESULTS

TUNEL assay showed that the rate of testicular cell apoptosis was obviously higher and Flow cytometry analysis showed that the rate of cell proliferation was significantly lower in the natural aging group than in the young control group and that intervention with Heshouwuyin could reverse this phenomenon. Therefore, we further applied microarray analysis to screen out differentially expressed genes regulated by Heshouwuyin and related to cell apoptosis. The expression of these genes was observed by quantitative fluorescence PCR, immunofluorescence staining, and western blot. The results showed that the expression of 14-3-3σ was significantly lower and that the expression of DR6, BAX, caspase-3 and Cytc were significantly higher in the natural aging group than in the young control group, but intervention with Heshouwuyin significantly reversed this phenomenon. Moreover, the curative efficacy of Heshouwuyin after 60 days was better than that of Heshouwuyin after 30 days.

CONCLUSION

Our study suggests that Heshouwuyin has anti-aging effects on the testis by means of inhibiting the occurrence of apoptosis in spermatogenic cells, thus improving the spermatogenic function of the testis. This is mainly achieved by regulating the expression of key genes in the mitochondrial apoptosis pathway.

Icaritin requires Phosphatidylinositol 3 kinase (PI3K)/Akt signaling to counteract skeletal muscle atrophy following mechanical unloading

Counteracting muscle atrophy induced by mechanical unloading/inactivity is of great clinical need and challenge. A therapeutic agent that could counteract muscle atrophy following mechanical unloading in safety is desired. This study showed that natural product Icaritin (ICT) could increase the phosphorylation level of Phosphatidylinositol 3 kinase (PI3K) at p110 catalytic subunit and promote PI3K/Akt signaling markers in C2C12 cells. This study further showed that the high dose ICT treatment could significantly attenuate the decreases in the phosphorylation level of PI3K at p110 catalytic subunit and its downstream markers related to protein synthesis, and inhibit the increases in protein degradation markers at mRNA and protein levels in rat soleus muscle following 28-day hindlimb unloading. In addition, the decreases in soleus muscle mass, muscle fiber cross-sectional area, twitch force, specific force, contraction time and half relaxation time could be significantly attenuated by the high dose ICT treatment. The low dose ICT treatment could moderately attenuate the above changes induced by unloading. Wortmannin, a specific inhibitor of PI3K at p110 catalytic subunit, could abolish the above effects of ICT in vitro and in vivo, indicating that PI3K/Akt signaling could be required by ICT to counteract skeletal muscle atrophy following mechanical unloading.

In Silico Insight into Potential Anti-Alzheimer's Disease Mechanisms of Icariin

Herbal compounds that have notable therapeutic effect upon Alzheimer's disease (AD) have frequently been found, despite the recent failure of late-stage clinical drugs. Icariin, which is isolated from Epimedium brevicornum, is widely reported to exhibit significant anti-AD effects in in vitro and in vivo studies. However, the molecular mechanism remains thus far unclear. In this work, the anti-AD mechanisms of icariin were investigated at a target network level assisted by an in silico target identification program (INVDOCK). The results suggested that the anti-AD effects of icariin may be contributed by: attenuation of hyperphosphorylation of tau protein, anti-inflammation and regulation of Ca²⁺ homeostasis. Our results may provide assistance in understanding the molecular mechanism and further developing icariin into promising anti-AD agents.