Icariside II, a novel phosphodiesterase 5 inhibitor, protects against H2 O2 -induced PC12 cells death by inhibiting mitochondria-mediated autophagy

Icariside II prevents kidney fibrosis development in chronic kidney disease by promoting fatty acid oxidation

Renal interstitial fibrosis (RIF) is the main pathological basis for the progression of chronic kidney disease (CKD), however, effective interventions are limited. Here, we investigated the effect of Icariside II (ICA-II) on RIF and explored the underlying mechanisms. Rats receiving 5/6 ablation and infarction (A/I) surgery were gavaged with ICA-II (5 or 10 mg/kg) for 8 weeks. In vitro, TGF-β1-stimulated NRK-52E cells were treated with ICA-II and (or) oleic acid, etomoxir, ranolazine, fenofibrate, and GW6471. The effects of ICA-II on RIF, fatty acid oxidation, lipid deposition, and mitochondrial function were determined by immunoblotting, Oil red O staining, colorimetric, and fluorometric assays. Using adeno-associated virus injection and co-culture methods, we further determined mechanisms of ICA-II anti-RIF. ICA-II ameliorated the fibrotic responses in vivo and in vitro. RNA-seq analysis indicated that ICA-II regulated fatty acid degradation and PPAR pathway in 5/6 (A/I) kidneys. ICA-II attenuated lipid accumulation and up-regulated expression of PPARα, CPT-1α, Acaa2, and Acadsb proteins in vivo and in vitro. Compared to ICA-II treatment, ICA-II combined with Etomoxir exacerbated mitochondrial dysfunction and fibrotic responses in TGF-β-treated NRK-52E cells. Importantly, we determined that ICA-II improved lipid metabolism, fatty acid oxidation, mitochondrial function, and RIF by restoring PPARα. Co-culture revealed that ICA-II decreased the expression of Fibronectin, Collagen-I, α-SMA, and PCNA proteins in NRK-49F cells by restoring PPARα of renal tubular cells. ICA-II may serve as a promising therapeutic agent for RIF in 5/6 (A/I) rats, which may be important for the prevention and treatment of CKD.

Protective mechanisms of quercetin in neonatal rat brain injury induced by hypoxic-ischemic brain damage (HIBD)

Neonatal hypoxic-ischemic brain damage (HIBD) is a leading cause of infant mortality worldwide. This study explored whether quercetin (Que) exerts neuroprotective effects in a rat model of HIBD. A total of 36 seven-day-old Sprague-Dawley rats were divided into control, Que, HI, and HI + Que groups. The Rice method was used to establish HIBD in HI and HI + Que rats, which were treated with hypoxia (oxygen concentration of 8%) for 2 h after ligation of the left common carotid artery. The rats in the HI + Que group were intraperitoneally injected with Que (30 mg/kg) 1 h before hypoxia, and the rats in the Que group were only injected with the same amount of Que. Brain tissues were harvested 24 h postoperation and assessed by hematoxylin and eosin staining, 2,3,5-triphenyltetrazolium chloride staining, and terminal deoxynucleotidyl transferase dUTP nick-end labeling assay; relative gene and protein levels were evaluated by RT-qPCR, IHC, or western blot (WB) assay. Brain tissue morphologies were characterized by transmission electron microscopy (TEM); LC3B protein levels were assessed by immunofluorescence staining. Escape latencies and platform crossing times were significantly improved (p < .05) in HI + Que groups; infarct volume significantly decreased (p < .001), whereas the numbers of autophagic bodies and apoptotic cells increased and decreased, respectively. Meanwhile, NLRX1, ATG7, and Beclin1 expressions were significantly upregulated, and mTOR and TIM23 expressions, LC3B protein level, and LC 3II/LC 3I ratio were significantly downregulated. Que exerted neuroprotective effects in a rat model of HIBD by regulating NLRX1 and autophagy.

Icariside II suppresses ferroptosis to protect against MPP+-Induced Parkinson's disease through Keap1/Nrf2/GPX4 signaling

Parkinson's disease (PD) is recognized as a degenerative and debilitating neurodegenerative disorder. The novel protective role of icariside II (ICS II) as a plant-derived flavonoid compound in neurodegenerative diseases has aroused much attention. Herein, the definite impacts of ICS II on the process of PD and the relevant action mechanism were studied. Human neuroblastoma SK-N-SH cells were challenged with 1-methyl-4-phenylpyridinium ion (MPP+) to construct the PD cell model. MTT assay and flow cytometry analysis, respectively, appraised cell viability and apoptosis. Caspase 3 Activity Assay examined caspase 3 activity. Corresponding kits examined oxidative stress levels. BODIPY 581/591 C11 assay evaluated lipid reactive oxygen species. Iron Assay Kit assessed iron content. Western blot tested the expression of apoptosis-, ferroptosis- and Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2)/glutathione peroxidase 4 (GPX4) signaling-associated proteins. Molecular docking verified the binding of ICS II with Keap1. The existing experimental results unveiled that ICS II elevated the viability whereas reduced the apoptosis, oxidative stress, and ferroptosis in MPP+-treated SK-N-SH cells in a concentration-dependent manner. Furthermore, ICS II declined Keap1 expression while raised Nrf2, heme oxygenase 1, and GPX4 expression. In addition, ICS II had a strong binding with Keap1 and Nrf2 inhibitor ML385 partially abolished the suppressive role of ICS II in MPP+-triggered apoptosis, oxidative stress, and ferroptosis in SK-N-SH cells. To summarize, ICS II might inhibit apoptosis, oxidative stress, and ferroptosis in the MPP+-stimulated PD cell model, which might be due to the activation of Keap1/Nrf2/GPX4 signaling.

Piceatannol Protects PC-12 Cells against Oxidative Damage and Mitochondrial Dysfunction by Inhibiting Autophagy via SIRT3 Pathway

Oxidative stress has been identified as a major cause of cellular injury in a variety of neurodegenerative disorders. This study aimed to investigate the cytoprotective effects of piceatannol on hydrogen peroxide (H₂O₂)-induced pheochromocytoma-12 (PC-12) cell damage and explore the underlying mechanisms. Our findings indicated that piceatannol pre-treatment significantly attenuated H₂O₂-induced PC-12 cell death. Furthermore, piceatannol effectively improved mitochondrial content and mitochondrial function, including enhancing mitochondrial reactive oxygen species (ROS) elimination capacity and increasing mitochondrial transcription factor (TFAM), peroxisome-proliferator-activated receptor-γ coactivator-1α (PGC-1α) and mitochondria Complex IV expression. Meanwhile, piceatannol treatment inhibited mitochondria-mediated autophagy as demonstrated by restoring mitochondrial membrane potential, reducing autophagosome formation and light chain 3B II/I (LC3B II/I) and autophagy-related protein 5 (ATG5) expression level. The protein expression level of SIRT3 was significantly increased by piceatannol in a concentration-dependent manner. However, the cytoprotective effect of piceatannol was dramatically abolished by sirtuin 3 (SIRT3) inhibitor, 3-(1H-1,2,3-Triazol-4-yl) pyridine (3-TYP), which led to an exacerbated mitochondrial dysfunction and autophagy in PC-12 cells under oxidative stress. In addition, the autophagy activator (rapamycin) abrogated the protective effects of piceatannol on PC-12 cell death. These findings demonstrated that piceatannol could alleviate PC-12 cell oxidative damage and mitochondrial dysfunction by inhibiting autophagy via the SIRT3 pathway.

Icariside II preconditioning evokes robust neuroprotection against ischaemic stroke, by targeting Nrf2 and the OXPHOS/NF-κB/ferroptosis pathway

BACKGROUND AND PURPOSE

Astrocytic nuclear factor erythroid-derived 2-related factor 2 (Nrf2) is a potential therapeutic target of ischaemic preconditioning (IPC). Icariside II (ICS II) is a naturally occurring flavonoid derived from Herba Epimedii with Nrf2 induction potency. This study was designed to clarify if exposure to ICS II mimicks IPC neuroprotection and if Nrf2 from astrocytes contributes to ICS II preconditioning against ischaemic stroke.

EXPERIMENTAL APPROACH

Mice with transient middle cerebral artery occlusion (MCAO)-induced focal cerebral ischaemia and primary astrocytes challenged with oxygen-glucose deprivation (OGD) were used to explore the neuroprotective effect of ICS II preconditioning. Additionally, Nrf2-deficient mice were pretreated with ICS II to determine whether ICS II exerts its neuroprotection by activating Nrf2.

KEY RESULTS

ICS II pretreatment mitigated cerebral injury in the mouse model of ischaemic stroke along with improving long-term recovery. Furthermore, proteomics screening identified Nrf2 as a crucial gene evoked by ICS II treatment and required for the anti-oxidative effect and anti-inflammatory effect of ICS II. Also, ICS II directly bound to Nrf2 and reinforced the transcriptional activity of Nrf2 after MCAO. Moreover, ICS II pretreatment exerted cytoprotective effects on astrocyte cultures following lethal OGD exposure, by promoting Nrf2 nuclear translocation and activating the OXPHOS/NF-κB/ferroptosis axis, while neuroprotection was decreased in Nrf2-deficient mice and Nrf2 siRNA blocked effects of ICS II.

CONCLUSION AND IMPLICATIONS

ICS II preconditioning provides robust neuroprotection against ischaemic stroke via the astrocytic Nrf2-mediated OXPHOS/NF-κB/ferroptosis axis. Thus, ICS II could be a promising Nrf2 activator to treat ischaemic stroke.

Icariside II Exerts Anti-Type 2 Diabetic Effect by Targeting PPARα/γ: Involvement of ROS/NF-κB/IRS1 Signaling Pathway

Type 2 diabetes mellitus (T2DM) is a multisystem and complex metabolic disorder which is associated with insulin resistance and impairments of pancreatic β-cells. Previous studies have shown that icariside II (ICS II), one of the main active ingredients of Herba Epimedii, exerts potent anti-inflammatory and anti-oxidative properties. In this study, we investigated whether ICS II exerted anti-T2DM profile and further explored its possible underlying mechanism both in vivo and in vitro. db/db mice were administered ICS II (10, 20, 40 mg·kg−1) for 7 weeks. We found that ICS II dose-dependently attenuated hyperglycemia and dyslipidemia, as well as inhibited hepatic steatosis and islet architecture damage in db/db mice. Moreover, ICS II not only dramatically reduced inflammatory cytokines and oxidative stress, but also up-regulated PPARα/γ protein expressions, phosphorylation of Akt, GSK3β and IR, meanwhile, down-regulated phosphorylation of NF-κB(p65) and IRS1 in db/db mice. In palmitic acid (PA)-treated HepG2 or MIN6 cells, ICS II (5−20 μM) concentration-dependently promoted the cell viability via mediating PPARα/γ/NF-κB signaling pathway. PPARα/γ knockout by CRISPR-Cas9 system partly abolished the protective effects of ICS II on HepG2 or MIN6 cells following PA insults. These findings reveal that ICS II effectively confer anti-T2DM property by targeting PPARα/γ through mediation of ROS/NF-κB/IRS1 signaling pathway.

Oroxin A reduces oxidative stress, apoptosis, and autophagy and improves the developmental competence of porcine embryos in vitro

Oroxin A (OA) is a flavonoid isolated from Oroxylum indicum (L.) Kurz that has various biological activities, including antioxidant activities. This study aimed to examine the viability of using OA in an in vitro culture (IVC) medium for its antioxidant effects and related molecular mechanisms on porcine blastocyst development. In this study, we investigated the effects of OA on early porcine embryo development via terminal deoxynucleotidyl transferase dUTP nick-end labeling, 5-ethynyl-2'-deoxyuridine labeling, quantitative reverse transcription PCR, and immunocytochemistry. Embryos cultured in the IVC medium supplemented with 2.5 μM of OA had an increased blastocyst formation rate, total cell number, and proliferation capacity, along with a low apoptosis rate. OA supplementation decreased reactive oxygen species levels, while increasing glutathione levels. OA-treated embryos exhibited an improved intracellular mitochondrial membrane potential and reduced autophagy. Moreover, levels of pluripotency- and antioxidant-related genes were upregulated, whereas those of apoptosis- and autophagy-related genes were downregulated by OA addition. In conclusion, OA improves preimplantation embryonic development by reducing oxidative stress and enhancing mitochondrial function.

Piezocatalytic and Photocatalytic Hydrogen Peroxide Evolution of Sulfide Solid Solution Nano-Branches from Pure Water and Air

Hydrogen peroxide (H₂ O₂ ) as a useful chemical has a wide range of applications, and the development of efficient semiconducting materials for H₂ O₂ production is deemed as a promising strategy to realize the energy conversion. In this paper, Cd_x Zn_1-x S (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) nano-branches are fabricated and the piezocatalytic and photocatalytic H₂ O₂ evolution performance are studied. Under ultrasound condition, the H₂ O₂ yield of as-synthesized solid solutions is all higher than those of pristine ZnS and CdS, and optimal evolution rate achieves 21.9 µmol g^-1 h^-1 for Cd_0.5 Zn_0.5 S without any sacrificial agent, while it is increased to 151.6 µmol g^-1 h^-1 under visible light irradiation. The piezo/photoelectrochemical tests, piezoresponse force microscopy (PFM), and computational simulation reveal that the nano-branch structure benefits the mechanical energy conversion more, favoring the H₂ O₂ evolution for Cd_0.5 Zn_0.5 S, and a higher concentration of charge carriers is generated in photocatalysis. The active radical trapping and in situ electron spin resonance (ESR) experiments demonstrate that both of the H₂ O₂ generation pathways are originated from oxygen reduction by the sequential two-step single-electron reaction. This work opens a door for promoting the H₂ O₂ production from nanostructure and solid solution design.

Number 2 Feibi Recipe Inhibits H2O2-Mediated Oxidative Stress Damage of Alveolar Epithelial Cells by Regulating the Balance of Mitophagy/Apoptosis

Reactive oxygen species (ROS)-mediated alveolar epithelial cell (AEC) injury and apoptosis are considered to be the initiating link of idiopathic pulmonary fibrosis (IPF), and protecting AECs can alleviate IPF. This study aimed to explore the protective effect of number 2 Feibi recipe (FBR-2) medicated serum on H₂O₂-mediated oxidative stress injury in AECs and further explore its mechanism. We found that FBR-2 can regulate downstream antioxidant enzymes expression by activating nuclear factor erythroid 2-related factor 2 (Nrf2), reducing the level of intracellular ROS, protecting mitochondrial function and improving cell survival. FBR-2 can also activate mitophagy through the PINK1/Parkin pathway. Moreover, FBR-2 can inhibit apoptosis by blocking the mitochondrial apoptosis mechanism. In summary, these data indicate that FBR-2 medicated serum can inhibit H₂O₂-mediated oxidative stress damage in AECs by regulating the balance of mitophagy/apoptosis. This study provides new evidence for the antifibrotic effect of FBR-2 and provides new drug candidates for the clinical treatment of IPF.

Icariside II Attenuates Methamphetamine-Induced Neurotoxicity and Behavioral Impairments via Activating the Keap1-Nrf2 Pathway

Chronic and long-term methamphetamine (METH) abuse is bound to cause damages to multiple organs and systems, especially the central nervous system (CNS). Icariside II (ICS), a type of flavonoid and one of the main active ingredients of the traditional Chinese medicine Epimedium, exhibits a variety of biological and pharmacological properties such as anti-inflammatory, antioxidant, and anticancer activities. However, whether ICS could protect against METH-induced neurotoxicity remains unknown. Based on a chronic METH abuse mouse model, we detected the neurotoxicity after METH exposure and determined the intervention effect of ICS and the potential mechanism of action. Here, we found that METH could trigger neurotoxicity, which was characterized by loss of dopaminergic neurons, depletion of dopamine (DA), activation of glial cells, upregulation of α-synuclein (α-syn), abnormal dendritic spine plasticity, and dysfunction of motor coordination and balance. ICS treatment, however, alleviated the above-mentioned neurotoxicity elicited by METH. Our data also indicated that when ICS combated METH-induced neurotoxicity, it was accompanied by partial correction of the abnormal Kelch 2 like ECH2 associated protein 1 (Keap1)-nuclear factor erythroid-2-related factor 2 (Nrf2) pathway and oxidative stress response. In the presence of ML385, an inhibitor of Nrf2, ICS failed to activate the Nrf2-related protein expression and reduce the oxidative stress response. More importantly, ICS could not attenuate METH-induced dopaminergic neurotoxicity and behavioral damage when the Nrf2 was inhibited, suggesting that the neuroprotective effect of ICS on METH-induced neurotoxicity was dependent on activating the Keap1-Nrf2 pathway. Although further research is needed to dig deeper into the actual molecular targets of ICS, it is undeniable that the current results imply the potential value of ICS to reduce the neurotoxicity of METH abusers.

Puerarin inhibits FUNDC1-mediated mitochondrial autophagy and CSE-induced apoptosis of human bronchial epithelial cells by activating the PI3K/AKT/mTOR signaling pathway

Increasing evidence suggests that the pathogenesis of chronic obstructive pulmonary disease (COPD) is associated with FUN14 domain protein 1 (FUNDC1)-mediated mitophagy. Recently, studies have reported that puerarin has protective effects against excessive oxidative damage in cells. Therefore, we hypothesized that puerarin may be involved in COPD progression via regulating FUNDC1 mediated mitophagy. We found that the viability of cigarette smoke extract (CSE)-stimulated human bronchial epithelial cells (HBECs) was enhanced and apoptosis was reduced after treatment with different concentrations of puerarin. Puerarin reversed mitochondrial membrane potential (MMP) levels and ATP content, and decreased reactive oxygen species (ROS) content in CSE stimulated HBECs. Moreover, puerarin significantly inhibited apoptosis related proteins, as well as the expression of mitophagy related proteins. After inhibition of FUNDC1 phosphorylation by protein phosphatase inhibitor (PH0321), puerarin restored MMP level, decreased ROS content, promoted ATP synthesis, and downregulated autophagy related protein expression in HBECs. In addition, mitochondrial division inhibitor (Mdivi) inhibited the expression of autophagy related proteins and reduced apoptosis after blocking cell autophagy, which was the same as the inhibition of puerarin. Finally, puerarin activated the PI3K/Akt/mTOR signaling pathway to participate in COPD progression by up regulating the phosphorylation levels of PI3K, Akt and mTOR.

Salvianolic acid B attenuates oxidative stress-induced injuries in enterocytes by activating Akt/GSK3β signaling and preserving mitochondrial function

The cellular and tissue damage induced by oxidative stress (OS) contribute to a variety of human diseases, which include gastrointestinal diseases. Salvianolic acid B (Sal B), which is a natural polyphenolic acid in Salvia miltiorrhiza, exhibits prominent antioxidant properties. However, its precise function and molecular mechanisms in protecting normal intestine epithelium from OS-induced damage are still poorly defined. In this study, we tried to clarify this relationship. Here, we found Sal B addiction in the rat intestinal epithelial cell, IEC-6, prevented H₂O₂-induced cell viability decrease and apoptosis induction, ameliorated H₂O₂-induced intestinal epithelial barrier dysfunction and mitochondrial dysfunction, and suppressed H₂O₂-induced production of ROS to varying degrees, ranging from 10% to 30%. Moreover, by employing an ischemia reperfusion model of rats, we also discovered that Sal B treatment reversed ischemia and a reperfusion-caused decrease in villus height and crypt depth, decreased proliferation of enterocytes, and increased the apoptotic index in the jejunum and ileum. Mechanistically, Sal B treatment up-regulated the phosphorylated level of Akt and GSK3β in enterocytes in vitro and in vivo, and PI3K inhibitor LY294002 treatment abrogated the protective effects of Sal B. Meanwhile, the inactivation of GSK3β reversed the oxidative stress-induced apoptosis and mitochondrial dysfunction in IEC-6 cells. Together, our results demonstrated that the damage of intestinal epithelial cells in in vitro and in vivo models were both attenuated by Sal B treatment, and such antioxidant activity might very possibly be attributed to the activation of Akt/GSK3β signaling.

Icariside II: Anticancer Potential and Molecular Targets in Solid Cancers

Icariside II, an active flavonoid, is extracted from the traditional Chinese medicinal herb Epimedii. It possesses multiple biological and pharmacological properties, including anti-inflammatory, anticancer, and anti-osteoporotic properties. In recent years, apoptosis has become the hot spot in anticancer therapies. Icariside II exerts positive effects on inducing apoptosis and inhibiting proliferation in various cancers. The antitumorigenic activity of Icariside II was also proven through cell cycle arrest, triggering autophagy, reducing cellular metabolism, and inhibiting cancer metastasis and tumor-associated angiogenesis. Additionally, Icariside II, as a natural product, contributed to a synergistic effect alongside chemotherapeutic drugs. Due to its poor aqueous solubility and permeability, more strategies were developed to improve its therapeutic effects. This review aimed to summarize the chemopreventive properties of Icariside II in solid tumors and reveal its underlying molecular mechanisms.

Icariside II protects cardiomyocytes from hypoxia‑induced injury by upregulating the miR‑7‑5p/BTG2 axis and activating the PI3K/Akt signaling pathway

Icariside II (ICS II) has been reported to have protective effects against oxidative stress. However, whether ICS II protects cardiomyocytes from myocardial infarction (MI), and the associated underlying mechanisms, remain to be elucidated. Therefore, the current study investigated the effects of ICS II on hypoxia‑injured H9c2 cells, as well as the associated molecular mechanisms. A hypoxic injury model was established to emulate the effects of MI. The effects of ICS II on the proliferation of rat cardiomyocyte H9c2 cells were assessed with cell counting kit‑8 assays. The apoptotic status of the cells was assessed by flow cytometry, and the expression of apoptosis‑related proteins was analyzed by western blotting. A microRNA (miRNA/miR) microarray was used to quantify the differential expression of miRNAs after ICS II treatment, and the levels of miR‑7‑5p were further quantified by reverse transcription‑quantitative PCR. Whether ICS II affected hypoxia‑injured cells via miR‑7‑5p was subsequently examined, and the target of miR‑7‑5p was also investigated by bioinformatics analysis and luciferase reporter assays. The effects of ICS II on the PI3K/Akt pathway were then evaluated by western blot analysis. Hypoxia treatment decreased viability and the migration and invasion abilities of H9c2 cells, and also induced apoptosis. ICS II significantly increased viability and reduced hypoxia‑associated apoptosis. Moreover, ICS II treatment led to the upregulation of miR‑7‑5p, and the protective effects of ICS II were found to rely on miR‑7‑5p. Moreover, BTG anti‑proliferation factor (BTG2) was identified as a direct target of miR‑7‑5p, and overexpression of BTG2 inhibited the protective effects of miR‑7‑5p. Finally, ICS II treatment resulted in the activation of the PI3K/Akt signaling pathway, which is essential for the survival of H9c2 cells under hypoxic conditions. In summary, ICS II reduces hypoxic injury in H9c2 cells via the miR‑7‑5p/BTG2 axis and activation of the PI3K/Akt signaling pathway.

Neuroprotective Effects of Trilobatin, a Novel Naturally Occurring Sirt3 Agonist from Lithocarpus polystachyus Rehd., Mitigate Cerebral Ischemia/Reperfusion Injury: Involvement of TLR4/NF-κB and Nrf2/Keap-1 Signaling

Aims: Neuroinflammation and oxidative stress are deemed the prime causes of brain injury after cerebral ischemia/reperfusion (I/R). Since the silent mating-type information regulation 2 homologue 3 (Sirt3) pathway plays an imperative role in protecting against neuroinflammation and oxidative stress, it has been verified as a target to treat ischemia stroke. Therefore, we attempted to seek novel Sirt3 agonist and explore its underlying mechanism for stroke treatment both in vivo and in vitro. Results: Trilobatin (TLB) not only dramatically suppressed neuroinflammation and oxidative stress injury after middle cerebral artery occlusion in rats, but also effectively mitigated oxygen and glucose deprivation/reoxygenation injury in primary cultured astrocytes. These beneficial effects, along with the reduced proinflammatory cytokines via suppressing Toll-like receptor 4 (TLR4) signaling pathway, lessened oxidative injury via activating nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways, in keeping with the findings in vivo. Intriguingly, the TLB-mediated neuroprotection on cerebral I/R injury was modulated by reciprocity between TLR4-mediated neuroinflammatory responses and Nrf2 antioxidant responses as evidenced by molecular docking and silencing TLR4 and Nrf2, respectively. Most importantly, TLB not only directly bonded to Sirt3 but also increased Sirt3 expression and activity, indicating that Sirt3 might be a promising therapeutic target of TLB. Innovation: TLB is a naturally occurring Sirt3 agonist with potent neuroprotective effects via regulation of TLR4/nuclear factor-kappa B and Nrf2/Kelch-like ECH-associated protein 1 (Keap-1) signaling pathways both in vivo and in vitro. Conclusion: Our findings indicate that TLB protects against cerebral I/R-induced neuroinflammation and oxidative injury through the regulation of neuroinflammatory and oxidative responses via TLR4, Nrf2, and Sirt3, suggesting that TLB might be a promising Sirt3 agonist against ischemic stroke.

Icariside II, a PDE5 Inhibitor, Suppresses Oxygen-Glucose Deprivation/Reperfusion-Induced Primary Hippocampal Neuronal Death Through Activating the PKG/CREB/BDNF/TrkB Signaling Pathway

Background

Ischemic stroke remains the leading cause of death and adult disability. Cerebral ischemic/reperfusion (I/R) injury is caused by ischemic stroke thereafter aggravates overwhelming neuronal apoptosis and even the death of neurons. Of note, hippocampus is more susceptive to cerebral I/R injury than the other brain region. This study was designed to explore the effects and mechanism of icariside II (ICS II), a pharmacologically active compound exists in herbal Epimedii with previous study-proved as a phosphodiesterase 5 (PDE5) inhibitor, on the oxygen glucose deprivation/reoxygenation (OGD/R)-induced primary hippocampal neurons injury.

Methods

Effects of ICS II on primary hippocampal neuronal impairment and apoptosis induced by OGD/R were examined by MTT, lactate dehydrogenase (LDH) release, TUNEL staining, and flow cytometry, respectively. Activation of memory-related signaling pathways was measured using Western blot analysis. The direct interaction between ICS II and PDE5 was further evaluated by molecular docking.

Results

ICS II (12.5, 25, 50 μM) markedly abrogated OGD/R-induced hippocampal neuronal death as suggested by the increase in neurons viability and the decrease in cellular LDH release. Furthermore, ICS II not only effectively decreased the protein expression and activity of PDE5, restored the 3′5′-cyclic guanosine monophosphate (cGMP) level and its downstream target protein kinase G (PKG) activity but also increased the phosphorylation of cAMP response element binding protein (CREB) level, expressions of brain derived neurotrophic factor (BDNF), and tyrosine protein kinase B (TrkB). Mechanistically, the inhibitory effects of ICS II were abrogated by Rp-8-Br-cGMP (a PKG inhibitor) or ANA-12 (a TrkB inhibitor), which further confirmed that the favorable effects of ICS II were attributed to its activation of the PKG/CREB/BDNF signaling pathways. Intriguingly, ICS II might effectively bind and inhibited PDE5 activity as demonstrated by relatively high binding scores (−6.52 kcal/mol).

Conclusions

ICS II significantly rescues OGD/R-induced hippocampal neuronal injury. The mechanism is, at least partly, due to inhibition of PDE5 and activation of PKG/CREB/BDNF/TrkB signaling pathway. Hence it is thought that ICS II might be a potential naturally PDE5 inhibitor to combat cerebral I/R injury.

Effect of Icariside II and Metformin on Penile Erectile Function, Histological Structure, Mitochondrial Autophagy, Glucose-Lipid Metabolism, Angiotensin II and Sex Hormone in Type 2 Diabetic Rats With Erectile Dysfunction

INTRODUCTION

Type 2 diabetes mellitus erectile dysfunction (T2DMED) is one of the common complications of type 2 diabetes mellitus (T2DM). Icariside II (ICA II), a flavonoid derived from Epimedium, has been shown to improve erectile function in T2DMED rats.

AIM

To investigate the effect of ICA II and metformin (MET) on penile erectile function, mitochondrial autophagy, glucose-lipid metabolism in rats with T2DMED.

METHODS

In the control and T2DMED groups, rats were administered normal saline. In the MET group, rats were administered MET for 0.2 g/kg/day. In the ICA II+MET group, rats were administered ICA II for 10 mg/kg/day and MET for 0.2 g/kg/day.

RESULTS

The number of mating rats, number of erectile rats, erection rate, erection frequency, intracorneal pressure, and intracorneal pressure/mean arterial pressure in the ICA II+MET group and control group were significantly higher than corresponding values in than T2DMED group. The absolute values of fasting plasma glucose, glycated haemoglobin in the ICA II+MET group, MET group, and control group were significantly lower than in the T2DMED group. The advanced glycation end product (AGE) values in the ICA II+MET group and the MET group were lower than in the T2DMED group. The receptors for the AGE values and angiotensin II values in the ICA II+MET group were lower than in the T2DMED and MET groups. The high-density lipoprotein values, testosterone values, nitric oxide synthase activity, and cyclic guanosine monophosphate content in the ICA II+MET and control groups were higher than in the T2DMED group. The low-density lipoprotein values, triglyceride values, estradiol values, and total cholesterol values in the ICA II+MET and control groups were lower than in the T2DMED group.

CONCLUSION

ICA II could increase erectile function and smooth muscle cell/collagen fibril proportions, decreased mitochondrial autophagy, and AGE concentrations and improve lipid metabolism, nitric oxide synthase activity, cyclic guanosine monophosphate content, testosterone, estradiol, and Ang II in rat with T2DMED. Zhang J, Li S, Zhang S, et al. Effect of Icariside II and Metformin on Penile Erectile Function, Histological Structure, Mitochondrial Autophagy, Glucose-Lipid Metabolism, Angiotensin II and Sex Hormone in Type 2 Diabetic Rats With Erectile Dysfunction. J Sex Med 2020;8:168-177.

Icariside II, a phosphodiesterase 5 inhibitor, attenuates cerebral ischaemia/reperfusion injury by inhibiting glycogen synthase kinase-3β-mediated activation of autophagy

Background and Purpose

Cerebral ischaemia/reperfusion causes exacerbated neuronal damage involving excessive autophagy and neuronal loss. The present study was designed to investigate the effect of icariside II, one of main active ingredients of Herba Epimedii on this loss and whether this is related to its PDE 5 inhibitory action.

Experimental Approach

Focal cerebral ischaemia was induced in the rat by transient middle cerebral artery occlusion over 2 hr, followed by reperfusion with icariside II, 3‐methylamphetamine or rapamycin. The effect of icariside II was determined measuring behaviour changes and the size of the infarction. The expressions of PDE 5, autophagy‐related proteins and the level of phosphorylation of glycogen synthase kinase‐3β (GSK‐3β) were determined. Cultured primary cortical neurons were subjected to oxygen and glucose deprivation followed by reoxygenation in the presence and absence of icariside II. A surface plasmon resonance assay and molecular docking were used to explore the interactions of icariside II with PDE 5 or GSK‐3β.

Key Results

Icariside II not only protected against induced ischaemic reperfusion injury in rats but also attenuated such injury in primary cortical neurons. The neuroprotective effects of icariside II on such injury were attributed to interfering with the PKG/GSK‐3β/autophagy axis by directly bounding to PDE 5 and GSK‐3β.

Conclusions and Implications

These findings indicate that icariside II attenuates cerebral I/R‐induced injury via interfering with PKG/GSK‐3β/autophagy axis. This study raises the possibility that icariside II and other PDE 5 inhibitors maybe effective in the treatment ischaemia stroke.

Icariside II inhibits lipopolysaccharide-induced inflammation and amyloid production in rat astrocytes by regulating IKK/IκB/NF-κB/BACE1 signaling pathway

β-amyloid (Aβ) is one of the inducing factors of astrocytes activation and neuroinflammation, and it is also a crucial factor for the development of Alzheimer's disease (AD). Icariside II (ICS II) is an active component isolated from a traditional Chinese herb Epimedium, which has shown to attnuate lipopolysaccharide (LPS)-induced neuroinflammation through regulation of NF-κB signaling pathway. In this study we investigated the effects of ICS II on LPS-induced astrocytes activation and Aβ accumulation. Primary rat astrocytes were pretreated with ICS II (5, 10, and 20 μM) or dexamethasone (DXMS, 1 μM) for 1 h, thereafter, treated with LPS for another 24 h. We found that ICS II pretreatment dose dependently mitigated the levels of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) in the astrocytes. Moreover, ICS II not only exerted the inhibitory effect on LPS-induced IκB-α degradation and NF-κB activation, but also decreased the levels of Aβ1-40, Aβ1-42, amyloid precursor protein (APP) and beta secretase 1 (BACE1) in the astrocytes. Interestingly, molecular docking revealed that ICS II might directly bind to BACE1. It is concluded that ICS II has potential value as a new therapeutic agent to treat neuroinflammation-related diseases, such as AD.

Propofol weakens hypoxia-aroused apoptosis and autophagy via elevating microRNA-137 in neurocytes

BACKGROUND

Hypoxia was proven to cause brain cell apoptosis and autophagy. Herein, we tested the influences of propofol, a commonly used intravenous sedative hypnotic drug, on apoptosis and autophagy aroused by hypoxia stimulation in PC-12 and HT-22 cells.

METHODS

Followed by hypoxia and/or propofol treatment, cell viability of PC-12 and HT-22 cells, apoptosis and autophagy, along with microRNA-137 (miR-137) expression were measured, respectively. Then, miR-137 inhibitor was transfected to silence miR-137. Whether miR-137 took part in the impacts of propofol on hypoxia-exposed cells was explored. Finally, the activities of PI3K/AKT/mTOR and ERK pathways were measured.

RESULTS

Hypoxia stimulation aroused cell apoptosis and elevated cell autophagy in PC-12 and HT-22 cells. Propofol weakened the apoptosis and autophagy of PC-12 and HT-22 cells aroused by hypoxia. Moreover, propofol elevated the miR-137 level in PC-12 and HT-22 cells. Silencing miR-137 declined the influences of propofol on hypoxia-induced injuries. Besides, propofol promoted PI3K/AKT/mTOR and ERK pathways activation in hypoxia-exposed cells through raising miR-137.

CONCLUSION

Propofol weakened hypoxia-aroused apoptosis and autophagy of PC-12 and HT-22 cells might be through raising miR-137 level and thereby promoting PI3K/AKT/mTOR and ERK pathways activation.

Glycine Protects against Hypoxic-Ischemic Brain Injury by Regulating Mitochondria-Mediated Autophagy via the AMPK Pathway

Hypoxic-ischemic encephalopathy (HIE) is detrimental to newborns and is associated with high mortality and poor prognosis. Thus, the primary aim of the present study was to determine whether glycine could (1) attenuate HIE injury in rats and hypoxic stress in PC12 cells and (2) downregulate mitochondria-mediated autophagy dependent on the adenosine monophosphate- (AMP-) activated protein kinase (AMPK) pathway. Experiments conducted using an in vivo HIE animal model and in vitro hypoxic stress to PC12 cells revealed that intense autophagy associated with mitochondrial function occurred during in vivo HIE injury and in vitro hypoxic stress. However, glycine treatment effectively attenuated mitochondria-mediated autophagy. Additionally, after identifying alterations in proteins within the AMPK pathway in rats and PC12 cells following glycine treatment, cyclosporin A (CsA) and 5-aminoimidazole-4-carboxamide-1-b-4-ribofuranoside (AICAR) were administered in these models and indicated that glycine protected against HIE and CoCl₂ injury by downregulating mitochondria-mediated autophagy that was dependent on the AMPK pathway. Overall, glycine attenuated hypoxic-ischemic injury in neurons via reductions in mitochondria-mediated autophagy through the AMPK pathway both in vitro and in vivo.

CZ2HF mitigates β-amyloid 25-35 fragment-induced learning and memory impairment through inhibition of neuroinflammation and apoptosis in rats

Cu‑zhi‑2‑hao‑fang (CZ2HF), a traditional Chinese medicine, has been used clinically for the treatment of amnesia. However, whether CZ2HF is capable of alleviating learning and memory impairment in Alzheimer's disease (AD) remains to be elucidated. The present study was designed to explore the effect and mechanism of CZ2HF on β‑amyloid 25‑35 (Aβ25‑35)‑induced impairment in the learning and memory of rats. Morris water maze test was used to determine spatial learning and memory ability in Aβ25‑35‑induced AD rats and hippocampal neuronal damage and apoptosis were observed using hematoxylin and eosin staining, Nissl staining and terminal deoxynucleotidyltransferase‑mediated dUTP nick‑end labeling (TUNEL) assays, respectively. The levels of β‑amyloid 1‑42 (Aβ1‑42), pro‑inflammatory factors, such as cyclooxygenase‑2 (COX‑2), tumor necrosis factor‑α (TNF‑α) and interleukin‑1β (IL‑1β) and apoptosis‑associated genes including B cell leukemia/lymphoma 2 (Bcl‑2), Bcl-2‑associated X, apoptosis regulator (Bax), pro‑caspase‑3, inhibitor of κB (IκB‑α) degradation and phosphorylated‑nuclear factor‑κB p65 (p‑NF‑κB p65) activation were analyzed using western blotting. The findings of the present study revealed that CZ2HF treatment significantly attenuated Aβ25‑35‑induced cognitive impairments in rats. Subsequently, CZ2HF treatment markedly inhibited neuronal damage and deletions. Furthermore, CZ2HF reduced TNF‑α, IL‑1β, COX‑2 protein expression levels, Bax/Bcl‑2 ratio, and reduced Aβ1‑42 and active‑caspase‑3 levels. In addition, IκB‑α degradation and p‑NF‑κB p65 activation were reduced by CZ2HF. These findings suggested that CZ2HF treatment improved Aβ25‑35‑induced learning and memory impairment and hippocampal neuronal injury, and its underlying mechanism may be due to the inhibition of neuroinflammation and neuronal apoptosis. CZ2HF may be a potential agent for the treatment of AD.

Lithocarpus polystachyus Rehd. leaves aqueous extract protects against hydrogen peroxide‑induced SH-SY5Y cells injury through activation of Sirt3 signaling pathway

Lithocarpus polystachyus Rehd. (sweet tea; ST) leaves is a type of Chinese folkloric medicine from southern China. The purpose of the present study was to explore the neuroprotective effect of ST, and to explore its underlying mechanisms in hydrogen peroxide (H2O2)‑induced neuronal cell injury in cultured human neuroblastoma. H2O2 was used as oxidant inducer and human SH‑SY5Y neuroblastoma cells were treated with various concentrations of ST. Cell viability and cell death were detected using MTT and LDH assays, respectively. Additionally, the production of intracellular and mitochondrial reactive oxygen species (ROS) were determined by 2',7'‑dichlorodihydrofluorescein diacetate (DCFH‑DA) and MitoSOX Red, respectively. The production of malondialdehyde (MDA), reduced glutathione (GSH) level, glutathione peroxidase (GSH‑Px), superoxide dismutase (SOD) activities, and NAD+/NADH ratio were confirmed using relevant kits. The expression of adenosine monophosphate‑activated protein kinase (AMPK), peroxisome proliferator‑activated receptor coactivator (PGC)‑1α, Sirt3, isocitrate dehydrogenase (IDH)2, forkhead boxO3a (Foxo3a), and SOD2 were analyzed by western blot analysis. It was demonstrated that pre‑treatment with ST enhanced cell viability and repressed cell death, and it also reduced intracellular and mitochondrial ROS accumulation. Additionally, ST attenuated MDA production and enhanced GSH level, GSH‑Px and SOD activities. Furthermore, ST not only increased NAD+/NADH ratio, but also inhibited the decrease of AMPK, PGC‑1α, Sirt3, IDH2, Foxo3a, and SOD2. The present study revealed that ST exerts protective effects against oxidative stress‑induced SH‑SY5Y cells injury, and the underlying mechanisms are, at least partly, associated with its antioxidant capacity and function through mitochondrial Sirt3 signaling pathway.

Synthesis and Biological Evaluation of Novel Alkyl Amine Substituted Icariside II Derivatives as Potential Anticancer Agents

A series of novel alkyl amine-substituted icariside II (ICA II) derivatives were synthesized by Mannich reactions at the 6-C position (compounds 4a–d) and changing the carbon chain length at the 7-OH position (compounds 7a–h), and their in vitro antitumor activity towards human breast cancer lines (MCF-7 and MDA-MB-231) and human hepatoma cell lines (HepG2 and HCCLM3-LUC) were evaluated by the MTT assay. Compared with ICA II, most of the twelve derivatives showed good micromole level activity and a preliminary structure-activity relationship (SAR) for the anticancer activity was obtained. Compound 7g showed the most potent inhibitory activity for the four cancer cell lines (13.28 μM for HCCLM3-LUC, 3.96 μM for HepG2, 2.44 μM for MCF-7 and 4.21 μM for MDA-MB-231), which was 2.94, 5.54, 12.56 and 7.72-fold stronger than that of ICA II. The preliminary SAR showed that the introduction of a alkyl amine substituent at 6-C was not favorable for the anticancer activity, while most of the 7-O-alkylamino derivatives exhibited good antitumor activity and the anticancer activity 7-O-alkylamino derivatives were influenced by the alkyl chain length and the different terminal amine substituents. Furthermore, the effects of compound 7g on apoptosis and cell cycle of MCF-7 cells were further investigated, which showed that compound 7g triggered apoptosis and arrested the cell cycle at the G0/G1 phase in MCF-7 cells. Our findings indicate that compound 7g may be a promising anticancer drug candidate lead.

Trilobatin Protects Against Oxidative Injury in Neuronal PC12 Cells Through Regulating Mitochondrial ROS Homeostasis Mediated by AMPK/Nrf2/Sirt3 Signaling Pathway

Oxidative stress-induced neuronal cell damage is a crucial factor in the pathogenesis of mitochondria-associated neurological diseases. Therefore, elimination of overproduction of mitochondrial reactive oxygen species (mtROS) may be a potential strategy for prevention and treatment of neurological diseases. In the present study, the neuroprotective effects of trilobatin (TLB), a novel small molecule monomer derived from Lithocarpus polystachyus Rehd, and its underlying mechanisms were investigated in vitro using hydrogen peroxide (H₂O₂)-induced oxidative stress model in a neuron-like PC12 cell. The findings revealed that pre-treatment with TLB dramatically concentration-dependently suppressed H₂O₂-induced PC12 cells damage by enhancing cell viability, repressed reduction of mitochondrial membrane potential (MMP) and decreased mtROS overgeneration, thereby deferring cell apoptosis. Further study demonstrated that TLB not only increased the enzymatic activities of glutathione peroxidase (GPx), isocitrate dehydrogenase 2 (IDH2),superoxide dismutase 2 (SOD2) and deacetylation of SOD2, but also activated silent mating-type information regulation 2 homolog 3 (Sirt3) within the mitochondria and thereby upregulating forkheadboxO3a (FoxO3a), which regulated mitochondrial DNA genes, then led to improving complex I activity and adenosine triphosphate (ATP) synthesis. What’s more, TLB up-regulated p-adenosine monophosphate-activated protein kinase (AMPK) level, the expression of peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α), and ERRα. Intriguingly, TLB failed to mitigate H₂O₂-induced PC12 injury in the presence of the AMPK inhibitor (Compound C), indicating that the beneficial effects of TLB on the regulation of mtROS homeostasis were reliance on AMPK -Sirt3 signaling pathway. Moreover, TLB also facilitated nuclear factor erythroid 2-related factor 2 (Nrf2) and promoted antioxidant gene expression in turn, and knockdown of Nrf2 by siRNA dramatically reduced the neuroprotective effects of TLB. Notably, AMPK inhibitor abolished the activation of Nrf2 and Sirt3, whereas, knockdown of Nrf2 blocked the upregulation of Sirt3, but it did not affect p-AMPK level. In conclusion, our findings demonstrate that TLB protects against oxidative injury in neuronal PC12 cells through regulating mtROS homeostasis in the first time, which is, at least partly, mediated through the AMPK/Nrf2/Sirt3 signaling pathway.

Icariside II alleviates oxygen-glucose deprivation and reoxygenation-induced PC12 cell oxidative injury by activating Nrf2/SIRT3 signaling pathway

Cerebral ischemia-reperfusion (I/R) injury is a key contributing factor to the pathogenic mechanisms involved in ischemic stroke. The present study was designed to explore the effects of icariside II (ICS II) on oxygen-glucose deprivation/reoxygenation (OGD/R)-induced PC12 cell oxidative injury. The results showed that ICS II ameliorated OGD/R-induced PC12 cell injury at the concentrations of 12.5, 25, and 50 μM, as evidenced by both the increase of cell viability and the decrease of LDH leakage from 33.96% ± 0.48% to 16.78% ± 0.78%, 13.12% ± 0.17%, 12.96% ± 0.10%, respectively. Moreover, ICS II not only attenuated the reactive oxygen species (ROS) from 212.2% ± 5.45%, 168.6% ± 5.29%, 148.7% ± 9.37%, 142.7% ± 7.76%, respectively, but also decreased the overproduction of mitochondrial ROS, as well as recovered the mitochondrial membrane potential (MMP) from 60.68% ± 7.90% to 76.71% ± 2.87%, 93.69% ± 4.41%, 95.92% ± 3.97%, respectively. Furthermore, OGD/R accelerated neuronal oxidative injury and apoptosis along with reduced nucleus-Nrf2, NQO-1, HO-1, Bcl-2 protein expressions, and increased Keap1, Bax and cleaved caspase-3 contents, whereas ICS II significantly reversed the abovementioned changes. Interestingly, ICS II also restrained the OGD/R-induced decrease in SIRT3 and IDH2 expressions. In conclusion, this study indicates that ICS II alleviates OGD/R-induced oxidative injury in PC12 cells, and its underlying mechanisms are due to the regulation of Nrf2/SIRT3 signaling pathway.

IcarisideII improves left ventricular remodeling in spontaneously hypertensive rats by inhibiting the ASK1-JNK/p38 signaling pathway

Inhibition or removal of excess reactive oxygen species can effectively protect cellular function or reduce cell death because oxidative stress is the main cause of cellular damage in many diseases. The flavonoid compound IcarisideII having a slight inhibitory effect on PDE5, is the main active components of epimedium in vivo and has a wide range of pharmacological effects on oxidation and apoptosis. However, whether IcarisideII has the same protective effect on ventricular remodeling in spontaneously hypertensive rats (SHR) is unknown. We found that compared with WKY rats, SHRs exhibited noticeable arterial hypertension. Additionally, echocardiography showed that the diameter of the left ventricle was enlarged, wall thickness was increased, and ejection fraction and short axis shortening rate were reduced. H&E staining demonstrated that SHR cells were disordered and noticeably hypertrophic. Masson trichrome staining revealed significant myocardial fibrosis in the myocardium. Tunel staining indicated that 4.39 times the percent of apoptotic cells were present in SHRs compared to WKY rats. In our study, intra-gastric administration of IcarisideII decreased blood pressure, promoted heart function recovery and improved ventricular remodeling in SHRs. Additionally, it reduced myocardial fibrosis, inhibited myocardial apoptosis, decreased the generation of reactive oxygen species and improved SOD activity. IcarisideII down-regulated the activation of the oxidative stress associated proteins ASK1, p38 and JNK; inhibited the expression of p53, Bax and cleaved-caspase3 in the mitochondrial apoptosis pathway; and up-regulated the expression of Bcl-2. In conclusion, this study indicates that IcarisideII can inhibit myocardial apoptosis and improve left ventricular remodeling in SHRs. It can be inferred that this mechanism may be related to the inhibition of the ASK1-JNK/p38 signaling pathway.

Icariside II, a PDE5 inhibitor from Epimedium brevicornum, promotes neuron-like pheochromocytoma PC12 cell proliferation via activating NO/cGMP/PKG pathway

Icariside II (ICS II), a phosphodiesterase 5 inhibitor (PDE 5-I), is a major ingredient of Epimedium brevicornum, with wide spectrum of neuroprotective properties. However, little is known about the potential beneficial effect of ICS II on neuronal cell proliferation, and its possible underlying mechanism remains still unclear. We hypothesized that the beneficial effect of ICS II on neuron-like highly differentiated rat pheochromocytoma (PC12) cell proliferation is correlated with the nitric oxide (NO) signaling pathway and its upstream of PI3K/AKT pathway. PC12 cells were treated with ICS II alone or together with L-NMMA, H89, KT-5823, and/or LY294002 (the inhibitor of NOS, PKA, PKG, PI3K, respectively). It was found that ICS II concentration-dependently promoted PC12 cells proliferation, and cell cycle analysis showed that the proportion of ICS II-treated PC12 cells in S phase was higher than that of control. Moreover, ICS II at the appropriate concentration (100 μM) not only increased nNOS expression, NO production, but also enhanced cGMP content and PKG activity. The addition of L-NMMA and KT-5 823 significantly inhibited the effects of ICS II on nNOS expression, NO production and PKG activity. Furthermore, LY294002 significantly decreased p-AKT level, NOS activity, NO production and nNOS expression, but it did not affect iNOS expression. These findings demonstrate that the beneficial effect of ICS II on neuronal cell proliferation, and its possible underlying mechanisms are, at least partly, through activating AKT/nNOS/NO/cGMP/PKG signaling pathway.

Icariside II Effectively Reduces Spatial Learning and Memory Impairments in Alzheimer's Disease Model Mice Targeting Beta-Amyloid Production

Icariside II (ICS II) is a broad-spectrum anti-cancer natural compound extracted from Herba Epimedii Maxim. Recently, the role of ICS II has been investigated in central nervous system, especially have a neuroprotective effect in Alzheimer’s disease (AD). In this study, we attempted to investigate the effects of ICS II, on cognitive deficits and beta-amyloid (Aβ) production in APPswe/PS1dE9 (APP/PS1) double transgenic mice. It was found that chronic ICS II administrated not only effectively ameliorated cognitive function deficits, but also inhibited neuronal degeneration and reduced the formation of plaque burden. ICS II significantly suppressed Aβ production via promoting non-amyloidogenic APP cleavage process by up-regulating a disintegrin and metalloproteinase domain 10 (ADAM10) expression, inhibited amyloidogenic APP processing pathway by down-regulating amyloid precursor protein (APP) and β-site amyloid precursor protein cleavage enzyme 1 (BACE1) expression in APP/PS1 transgenic mice. Meanwhile, ICS II attenuated peroxisome proliferator-activated receptor-γ (PPARγ) degradation as well as inhibition of eukaryotic initiation factor α phosphorylation (p-eIF2α) and PKR endoplasmic reticulum regulating kinase phosphorylation (p-PERK). Moreover, phosphodiesterase type 5 inhibitors (PDE5-Is) have recently emerged as a possible therapeutic target for cognitive enhancement via inhibiting Aβ levels, and we also found that ICS II markedly decreased phosphodiesterase-5A (PDE5A) expression. In conclusion, the present study demonstrates that ICS II could attenuate spatial learning and memory impairments in APP/PS1 transgenic mice. This protection appears to be due to the increased ADAM10 expression and decreased expression of both APP and BACE1, resulting in inhibition of Aβ production in the hippocampus and cortex. Inhibition of PPARγ degradation and PERK/eIF2α phosphorylation are involved in the course, therefore suggesting that ICS II might be a promising potential compound for the treatment of AD.