Antioxidative effect of the herbal remedy Qin Huo Yi Hao and its active component tetramethylpyrazine on high glucose-treated endothelial cells

Tetramethylpyrazine protects neural stem cells against sevoflurane-induced toxicity through Akt/GSK-3β pathway

Sevoflurane, a commonly used anesthetic, has been found to cause neural stem cell (NSC) injury, thereby contributing to neurocognitive impairment following general anesthesia. Tetramethylpyrazine (TMP), one of the most widely used medicinal compounds isolated from a traditional Chinese herb, possess neuroprotective activity. However, its effect on sevoflurane-induced NSC injury remains unclear. NSCs were pretreated with indicated concentrations of TMP for 2 h and then exposed to sevoflurane for 6 h. Cell injury was measured using lactate dehydrogenase (LDH) release assay. Cell viability and proliferation were detected by cell counting kit-8 (CCK-8) assay and 5-bromo-2'-deoxyuridine (BrdU) labeling, respectively. Apoptotic cells were detected using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The levels of cleaved caspase-3, phosphorylated protein kinase B (Akt) and phosphorylated glycogen synthase kinase-3β (GSK-3β) were detected by western blotting. Our results showed exposure to sevoflurane decreased the viability and proliferation of NSCs, while TMP preserved NSC viability and proliferation after sevoflurane exposure. In addition, the expression of cleaved caspase-3 and TUNEL positive cells were markedly decreased in TMP-treated NSCs compared with the control. Furthermore, pretreatment with TMP significantly increased the levels of phosphorylated Akt and GSK-3β in sevoflurane-injured NSCs. However, an upstream inhibitor of Akt, LY294002 abolished the protective of TMP on the cell viability of NSCs. In conclusion, these findings indicate that TMP protects NSCs from sevoflurane-induced toxicity through Akt/GSK-3β pathway.

Artesunate and Tetramethylpyrazine Exert Effects on Experimental Cerebral Malaria in a Mechanism of Protein S-Nitrosylation

Cerebral malaria (CM) is caused by Plasmodium falciparum, resulting in severe sequelae; one of its pathogenic factors is the low bioavailability of nitric oxide (NO). Our previous study suggested that the combination of artesunate (AS) and tetramethylpyrazine (TMP) exerts an adjuvant therapeutic effect on the symptoms of experimental CM (ECM) and that NO regulation plays an important role. In the present study, we further verified the effects of AS+TMP on cerebral blood flow (CBF) and detected NO-related indicators. We focused on the role of NO through S-nitrosoproteome based on previous proteomics data and explored the mechanism of AS+TMP for improving pathological ECM symptoms. We observed that AS+TMP reduces adhesion, increases CBF, and regulates NO synthase (NOS) activity, thereby regulating the level of S-nitrosothiols, such as metabolism-related or neuro-associated receptors, for improving ECM symptoms. These results demonstrated that AS+TMP could be an effective strategy in adjuvant therapy of CM.

Activation of nuclear factor-kappa B by TNF promotes nucleus pulposus mineralization through inhibition of ANKH and ENPP1

Spontaneous mineralization of the nucleus pulposus (NP) has been observed in cases of intervertebral disc degeneration (IDD). Inflammatory cytokines have been implicated in mineralization of multiple tissues through their modulation of expression of factors that enable or inhibit mineralization, including TNAP, ANKH or ENPP1. This study examines the underlying factors leading to NP mineralization, focusing on the contribution of the inflammatory cytokine, TNF, to this pathologic event. We show that human and bovine primary NP cells express high levels of ANKH and ENPP1, and low or undetectable levels of TNAP. Bovine NPs transduced to express TNAP were capable of matrix mineralization, which was further enhanced by ANKH knockdown. TNF treatment or overexpression promoted a greater increase in mineralization of TNAP-expressing cells by downregulating the expression of ANKH and ENPP1 via NF-κB activation. The increased mineralization was accompanied by phenotypic changes that resemble chondrocyte hypertrophy, including increased RUNX2 and COL10A1 mRNA; mirroring the cellular alterations typical of samples from IDD patients. Disc organ explants injected with TNAP/TNF- or TNAP/shANKH-overexpressing cells showed increased mineral content inside the NP. Together, our results confirm interactions between TNF and downstream regulators of matrix mineralization in NP cells, providing evidence to suggest their participation in NP calcification during IDD.

Ligustrazine alleviates cyclophosphamide-induced hepatotoxicity via the inhibition of Txnip/Trx/NF-κB pathway

AIMS

Cyclophosphamide (CP) is a common therapeutic drug for cancer, but exposure to CP can cause acute hepatotoxicity. This study aimed to elucidate the protective effects of Ligustrazine (2, 3, 5, 6-tetramethylpyrazine, TMP) on hepatotoxicity induced by CP or its active metabolite 4-hydroperoxycyclophosphamide (4-HC).

MAIN METHODS

We presented a comprehensive investigation about the hepatoprotection of TMP on CP-induced mice and 4-HC-treated HSC-LX2 cells. Liver function was detected via enzyme-linked immunosorbent assay (ELISA). Hepatic histopathology analysis was performed via hematoxylin and eosin (H&E) and Masson staining. Survival of hepatocytes was detected by TUNEL assay. Related proteins in the thioredoxin (Trx)-interacting protein (Txnip)/Trx/Nuclear factor-kappa B (NF-κB) pathway were measured by western blotting.

KEY FINDINGS

The results indicated that CP or 4-HC could increase the levels of alanine aminotransferase and aspartate aminotransferase, enhance inflammatory factors and oxidative indicators, and suppress the activity of oxidoreductases. Moreover, significant changes in liver histological structure, fibrosis, and cell death were observed through the activation of Txnip/Trx/NF-κB pathway. In contrast, administration of TMP significantly reversed these above changes. Furthermore, TMP intervention participated in the inhibition of NLRP3 inflammasome accompanied with pyroptosis, as well as upregulating Trx expression and downregulating p-NF-κB, while the protective effect of TMP was limited to the involvement of Txnip overexpression.

SIGNIFICANCE

TMP treatment could significantly alleviate the hepatotoxicity process as evidenced by improving the structure and function of the liver, inhibiting oxidative stress and inflammation accompanied with pyroptosis, which was positively correlated with the inhibition of Txnip/Trx/NF-κB pathway.

iTRAQ-based proteomic analysis of duck muscle related to lipid oxidation

Lipid oxidation is the main cause of quality deterioration in meat and meat products. To facilitate the identification of candidate molecular biomarkers that are linked to lipid oxidation, we performed the proteomic analysis of duck muscle using isobaric tag for relative and absolute quantification (iTRAQ), followed by parallel reaction monitoring (PRM) to confirm the iTRAQ results. Pectoralis major muscles were divided into 2 groups in accordance with lipid oxidation, and iTRAQ-based analysis identified a total of 301 differentially expressed proteins, of which 15 proteins were examined by PRM assay. Proteins involved in lipid binding and metabolism, lipolysis, stress response, oxidative respiratory chain, and redox regulation were found to be differentially expressed between 2 groups and might affect lipid oxidation in muscles. The findings could contribute to the improved understanding of key proteins and processes engaged in lipid oxidation of meat.

SANT, a novel Chinese herbal monomer combination, decreasing tumor growth and angiogenesis via modulating autophagy in heparanase overexpressed triple-negative breast cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Astragalus mongholicus, Solanum nigrum Linn, Lotus plumule, Ligusticum are widely used traditional herbal medicines for cancer treatment in China. They were typical drugs selected from Gubenyiliu II and series of formula (GYII), which were developed on the foundation of YIQIHUOXUEJIEDU theory. In the present study, four active ingredients (Astragaloside IV, α-solanine, neferine, and 2,3,5,6-tetramethylpyrazine) derived from medicines above were applied in combination as SANT.

AIM OF THE STUDY

Triple-negative breast cancer (TNBC) is a serious threat to women's health worldwide. Heparanase (HPSE) is often up-regulated in breast cancer with the properties of facilitating tumorigenesis and influencing the autophagy process in cancer cells. This study aimed at evaluating the anti-tumor potential of SANT in treating HPSE related TNBC both in-vitro and in-vivo.

MATERIALS AND METHODS

In this study, we explored the correlation between HPSE expression and survival of breast cancer patients in databases. We performed MTS, trans-well and wound scratch assays to assess the impact of SANT on cell proliferation and migration. Confocal microscopy observation and western blots were applied to verify the autophagy flux induced by SANT. Mice models were employed to evaluate the efficacy and safety of SANT in-vivo by tumor weights and volumes or serum index, respectively. To analyze the underlying mechanisms of SANT, we conducted human autophagy PCR array and angiogenesis proteome profiler on tumor tissues.

RESULTS

Patients with elevated HPSE expression were associated with a poor outcome in both RFS (P = 1.7e-12) and OS (P = 0.00016). SANT administration significantly inhibited cancer cells' proliferation and migration, enhanced autophagy flux, and slightly reduced the active form of HPSE in-vitro. SANT also suppressed tumor growth and angiogenesis in-vivo. Human autophagy PCR array results indicated that SANT increased the ATG16L1, ATG9B, ATG4D gene expressions while decreased TMEM74 and TNF gene expressions.Angiogenesis proteome profiler results showed SANT reduced protein level of HB-EGF, thrombospondin-2, amphiregulin, leptin, IGFBP-9, EGF, coagulation factor III, and MMP-9 (pro and active form) in tumor, raised the protein expression of serpin E1 and platelet factor 4.

CONCLUSIONS

These findings indicated that herbal compounds SANT may be a promising candidate in anti-cancer drug discovery. It also provides novel strategies for using natural compounds to achieve optimized effect.

2,3,5,6-Tetramethylpyrazine improves diet-induced whole-body insulin resistance via suppressing white adipose tissue lipolysis in mice

Ectopic lipid accumulation in skeletal muscle and liver arises when nutrient storage systems are exposed to chronic energy surplus, leading to whole-body insulin resistance and metabolic disorders. One recent study has shown 2,3,5,6-tetramethylpyrazine (TMP), highly enriched in roasted foodstuffs, such as cocoa and peanuts, significantly decreases blood lipids levels and ameliorates ApoE-defect induced atherosclerosis suggesting a potent role of TMP in lipid dysregulation improvement. Here, we evaluated the impact of TMP treatment on high fat diet (HFD)-induced insulin resistance. Using hyperinsulinemic-euglycemic mouse clamp, we demonstrated 4-week TMP treatment improved whole-body insulin resistance in HFD-fed mice through suppressing lipolysis in white adipose tissue associated with reduced triglyceride in liver and improved glucose uptake in skeletal muscle. Collectively, our work provides proof-of-concept data to support the development of white adipose tissue-targeted medicine for the treatment of metabolic disorder.

Tetramethylpyrazine alleviates diabetic nephropathy through the activation of Akt signalling pathway in rats

In the whole world, the principal cause of end-stage renal disease is diabetic nephropathy (DN), which is one of the most relentless complications of diabetes. However, there is a shortfall of compelling DN treatments and the mechanism potentially able to alleviate renal injury remains ambiguous. In this experiment, we estimated the preventive actions of tetramethylpyrazine (TMP) on DN in rats and further investigated the underlying mechanism. The different doses of TMP (100 mg/kg, 150 mg/kg and 200 mg/kg) were orally given each day for 8 weeks in streptozotocin (STZ) - nicotinamide (NCT) - induced type-2 diabetic (T2D) rats. The metabolic parameters of diabetes, blood urea nitrogen (BUN), serum creatinine (SCR), urinary protein and oxidative stress parameters were assessed. Microstructural changes in kidney were observed, and the expression of Akt signalling pathway proteins was measured by western blotting. TMP administration in T2D rats improved diabetic condition, as demonstrated by significant (P < 0.05) increase of body weight and fasting serum insulin (FSI) level, reduction of fasting blood glucose (FBG) and glycosylated haemoglobin (HbA1c) level and regulation of lipid profile and oral glucose tolerance in a dose-dependent manner. TMP treatment also reduced BUN, SCR, urinary protein and oxidative stress and prevented renal injury in diabetic rats. TMP activated Akt signalling pathway, increased the levels of p-Akt and Bcl-2, and diminished the expressions of p-GSK-3β, Bax and cleaved caspase-3. In conclusion, TMP ameliorates diabetic nephropathy in T2D rats by initiating the Akt signalling, improving the metabolic markers of diabetes and suppressing oxidative stress.

Effects of tetramethylpyrazine phosphate on pancreatic islet microcirculation in SD rats

PURPOSES

Abnormal islet microcirculation impetus the insulin production and accelerates progression of Type 1 and 2 diabetes. In this study, we investigated whether tetramethylpyrazine phosphate (TMPP), a vasoactive substance, could regulate the islet microcirculation and insulin concentration and improve glycaemia in SD rats.

METHODS

SD rats were randomly divided into two groups, the control and TMPP groups. Each group was further divided into three subgroups according to the intravenous injection of either saline, 15 or 30% glucose. The non-radioactive microsphere technique was adopted to measure the organ blood flow. Nitric oxide synthase (NOS) blocker L-NAME was used to address whether NO was involved in mediating the vasoactive effects of TMPP.

RESULTS

In the TMPP group, TMPP increased the PBF (pancreatic blood flow), IBF (islet blood flow), and fIBF (fraction of islet blood flow out of pancreatic blood flow) by 57, 76 and 47%, respectively, after 30% glucose infusion, compared with the control, indicating that TMPP could regulate islet microcirculation. Furthermore, TMPP induced a 66% elevation of IBF and 37% of fIBF in the 30% glucose subgroups than the 15% ones. In 30% glucose-treated subgroups, TMPP improved the blood glucose concentration by 10%, compared with the control (19.3 ± 0.64 vs 17.32 ± 0.56 mmol/l, P < 0.05), without influencing the insulin secretion. Blocking NO formation prevented the enhanced PBF and IBF, evoking by TMPP with 30% glucose.

CONCLUSIONS

TMPP can regulate the pancreatic islet microcirculation and possess a hypoglycemia effect after glucose infusion through affecting the islet microcirculation.

Cellular and Molecular Mechanisms of Diabetic Atherosclerosis: Herbal Medicines as a Potential Therapeutic Approach

An increasing number of patients diagnosed with diabetes mellitus eventually develop severe coronary atherosclerosis disease. Both type 1 and type 2 diabetes mellitus increase the risk of cardiovascular disease associated with atherosclerosis. The cellular and molecular mechanisms affecting the incidence of diabetic atherosclerosis are still unclear, as are appropriate strategies for the prevention and treatment of diabetic atherosclerosis. In this review, we discuss progress in the study of herbs as potential therapeutic agents for diabetic atherosclerosis.

Tetramethylpyrazine-Loaded Hydrogels: Preparation, Penetration Through a Subcutaneous-Mucous-Membrane Model, and a Molecular Dynamics Simulation

Tetramethylpyrazine (TMP) was extracted from Ligusticum chuanxiong hort. The compound is known to have a variety of medicinal functions; in particular, it is used for the treatment of cerebral ischemic diseases. TMP-loaded hydrogels offer an excellent preparation with the capacity to bypass the blood-brain barrier, allowing treatment of the brain through intranasal administration. We prepared TMP-loaded hydrogels using carbomer 940 and evaluated the release of TMP from the hydrogel. We determined the release rate using Franz-type diffusion cell experiments with a subcutaneous-mucous-membrane model and also by a molecular dynamics (MD) simulation. In general, the former method was more complicated than the latter was. The dynamic behavior of TMP release from the hydrogel was revealed by analysis of the mean square displacement of the trajectory in the MD simulation. The coefficient of TMP diffusion from the hydrogel was calculated at different temperatures (277, 298, and 310 K) by using MD software. The results showed that the coefficient of diffusion increased with an increase in temperature. This trend was observed both experimentally and in the MD simulation. Therefore, the MD simulation was a complementary method to verify the experimental data.

Tetramethylpyrazine blocks TFAM degradation and up-regulates mitochondrial DNA copy number by interacting with TFAM

The natural small molecule compound: 2,3,5,6-tetramethylpyrazine (TMP), is a major component of the Chinese medicine Chuanxiong, which has wide clinical applications in dilating blood vessels, inhibiting platelet aggregation and treating thrombosis. Recent work suggests that TMP is also an antitumour agent. Despite its chemotherapeutic potential, the mechanism(s) underlying TMP action are unknown. Herein, we demonstrate that TMP binds to mitochondrial transcription factor A (TFAM) and blocks its degradation by the mitochondrial Lon protease. TFAM is a key regulator of mtDNA replication, transcription and transmission. Our previous work showed that when TFAM is not bound to DNA, it is rapidly degraded by the ATP-dependent Lon protease, which is essential for mitochondrial proteostasis. In cultured cells, TMP specifically blocks Lon-mediated degradation of TFAM, leading to TFAM accumulation and subsequent up-regulation of mtDNA content in cells with substantially low levels of mtDNA. In vitro protease assays show that TMP does not directly inhibit mitochondrial Lon, rather interacts with TFAM and blocks degradation. Pull-down assays show that biotinylated TMP interacts with TFAM. These findings suggest a novel mechanism whereby TMP stabilizes TFAM and confers resistance to Lon-mediated degradation, thereby promoting mtDNA up-regulation in cells with low mtDNA content.

Mechanisms and Clinical Application of Tetramethylpyrazine (an Interesting Natural Compound Isolated from Ligusticum Wallichii): Current Status and Perspective

Tetramethylpyrazine, a natural compound from Ligusticum wallichii (Chuan Xiong), has been extensively used in China for cardiovascular and cerebrovascular diseases for about 40 years. Because of its effectiveness in multisystems, especially in cardiovascular, its pharmacological action, clinical application, and the structural modification have attracted broad attention. In this paper its mechanisms of action, the clinical status, and synthetic derivatives will be reviewed briefly.

Comprehensive Evaluation of the Metabolism of Genipin-1-β-d-gentiobioside in Vitro and in Vivo by Using HPLC-Q-TOF

To examine the metabolism of genipin-1-β-d-gentiobioside (GG), its distribution and biotransformation in vivo and in vitro were investigated. Urine, plasma, feces, and various organs were collected after oral administration of GG to normal rats and pseudo-germ-free rats to evaluate GG metabolism in vivo. GG was incubated with intestinal flora and primary hepatocytes in vitro to investigate microbial and hepatic metabolism. Using HPLC-Q-TOF-LC/MS, 11 metabolites of GG were absolutely or tentatively identified in terms possible elemental compositions, retention times, and characteristics of fragmentation patterns corresponding to eight biotransformations: deglycosylation, hydroxylation, sulfate conjugation, glucuronidation, hydrogenation, demethylation, glycosylation, and dehydration. Fewer metabolites were detected in pseudo-germ-free rats than in conventional rats. Moreover, geniposide and genipin were generated by the deglycoslation of intestinal bacteria. Geniposidic acid was detected in rat primary-hepatocyte incubation. This study first explores the metabolism of GG in vivo and in vitro. The results can aid the elucidation of PK profiles and clinical usage of gardenia fruit.

Cardiovascular Actions and Therapeutic Potential of Tetramethylpyrazine (Active Component Isolated from Rhizoma Chuanxiong): Roles and Mechanisms

Tetramethylpyrazine (TMP), a pharmacologically active component isolated from the rhizome of the Chinese herb Rhizoma Chuanxiong (Chuanxiong), has been clinically used in China and Southeast Asian countries for the prevention and treatment of cardiovascular diseases (CVDs) for about fifty years. The pharmacological effects of TMP on the cardiovascular system have attracted great interest. Emerging experimental studies and clinical trials have demonstrated that TMP prevents atherosclerosis as well as ischemia-reperfusion injury. The cardioprotective effects of TMP are mainly related to its antioxidant, anti-inflammatory, or calcium-homeostasis effects. This review focuses on the roles and mechanisms of action of TMP in the cardiovascular system and provides a novel perspective on TMP's clinical use.

Tetramethylpyrazine protects CoCl2-induced apoptosis in human umbilical vein endothelial cells by regulating the PHD2/HIF/1α-VEGF pathway

Tetramethylpyrazine (TMP), one of the active ingredients isolated from a Chinese herbal prescription, possesses protective effects against apoptosis in endothelial cells. However, the underlying mechanism of its protective effects in endothelial cells remains to be elucidated. Using human umbilical vein endothelial cells (HUVECs), the present study assessed the protective effects of TMP on CoCl2-induced apoptosis. Following pre-incubation with CoCl2 (150 µM/ml) for 4 h, the HUVECs were treated with TMP at different concentrations (50, 100 and 200 µM/ml) for 8 h. TMP upregulated the expression of prolyl hydroxylase (PHD)2, reduced the protein and mRNA expression levels of vascular endothelial growth factor (VEGF), and reduced the expression of HIF-1α only at the protein level, not at the mRNA level in HUVECs, in a concentration-dependent manner. Furthermore, silencing of the PHD2 gene with small interfering (si)RNAs abolished the reduction in the expression of hypoxia-inducible factor (HIF)-1α and VEGF by TMP. In addition, TMP protected CoCl2-induced HUVEC injury via an apoptosis pathway, as characterized by the increased ratio of cell viability and the reduced percentage of apoptotic and terminal deoxynucleotidyl transferase dUTP nick end labeling-positive HUVECs, activation of caspase-3, -8 and -9, B-cell lymphoma (Bcl)-2/Bcl-2-activated X protein expression, as well as the release of cytochrome c. The protective properties of TMP were partially attributed to the mRNA and protein expression levels of PHD, since silencing of the PHD2 gene with siRNAs abolished these effects. The present study demonstrated that the antiapoptotic effect of TMP in CoCl2-induced HUVECs was, at least in part, via the regulation of the PHD2/HIF-1α signaling pathway.

Pretreatment with β-Boswellic Acid Improves Blood Stasis Induced Endothelial Dysfunction: Role of eNOS Activation

Vascular endothelial cells play an important role in modulating anti-thrombus and maintaining the natural function of vascular by secreting many active substances. β-boswellic acid (β-BA) is an active triterpenoid compound from the extract of boswellia serrate. In this study, it is demonstrated that β-BA ameliorates plasma coagulation parameters, protects endothelium from blood stasis induced injury and prevents blood stasis induced impairment of endothelium-dependent vasodilatation. Moreover, it is found that β-BA significantly increases nitric oxide (NO) and cyclic guanosine 3’, 5’-monophosphate (cGMP) levels in carotid aortas of blood stasis rats. To stimulate blood stasis-like conditions in vitro, human umbilical vein endothelial cells (HUVECs) were exposed to transient oxygen and glucose deprivation (OGD). Treatment of β-BA significantly increased intracellular NO level. Western blot and immunofluorescence as well as immunohistochemistry reveal that β-BA increases phosphorylation of enzyme nitric oxide synthase (eNOS) at Ser1177. In addition, β-BA mediated endothelium-dependent vasodilatation can be markedly blocked by eNOS inhibitor L-NAME in blood stasis rats. In OGD treated HUEVCs, the protective effect of β-BA is attenuated by knockdown of eNOS. In conclusion, the above findings provide convincing evidence for the protective effects of β-BA on blood stasis induced endothelial dysfunction by eNOS signaling pathway.

Ligustrazine monomer against cerebral ischemia/reperfusion injury

Ligustrazine (2,3,5,6-tetramethylpyrazine) is a major active ingredient of the Szechwan lovage rhizome and is extensively used in treatment of ischemic cerebrovascular disease. The mechanism of action of ligustrazine use against ischemic cerebrovascular diseases remains unclear at present. This study summarizes its protective effect, the optimum time window of administration, and the most effective mode of administration for clinical treatment of cerebral ischemia/reperfusion injury. We examine the effects of ligustrazine on suppressing excitatory amino acid release, promoting migration, differentiation and proliferation of endogenous neural stem cells. We also looked at its effects on angiogenesis and how it inhibits thrombosis, the inflammatory response, and apoptosis after cerebral ischemia. We consider that ligustrazine gives noticeable protection from cerebral ischemia/reperfusion injury. The time window of ligustrazine administration is limited. The protective effect and time window of a series of derivative monomers of ligustrazine such as 2-[(1,1-dimethylethyl)oxidoimino]methyl]-3,5,6-trimethylpyrazine, CXC137 and CXC195 after cerebral ischemia were better than ligustrazine.

Tetramethylpyrazine enhances vascularization and prevents osteonecrosis in steroid-treated rats

Steroid-induced osteonecrosis of the femoral head (steroid-induced ONFH) is an avascular necrosis disease of bone. Tetramethylpyrazine (TMP), with significant vascular protective properties, has been widely used for the treatments of ischemic neural disorders and cardiovascular diseases. However, its role in the treatment of steroid-induced ONFH has not been evaluated. In this study, our results showed that TMP significantly decreased the ratio of empty lacuna, adipose tissue area, and adipocyte perimeter in steroid-induced ONFH rats histopathologically. TMP also reduced the levels of serum lipid dramatically by haematological examination. According to the micro-CT quantification, TMP could improve the microstructure of the trabecular bone and increases bone mineral density in steroid-induced ONFH rats. Moreover, TMP significantly increased the vessel volume, vessel surface, percentage of vessel volume, and vessel thickness of the femoral heads by micro-CT. Interestingly, the downregulation of VEGF and FLK1 proteins in the sera and necrotic femoral heads could be reversed by TMP treatment, and this was true for their mRNA expressions in femoral heads. In conclusion, these findings suggest for the first time that TMP may prevent steroid-induced ONFH and also enhance femoral head vascularization by inhibiting the effect of steroid on VEGF/FLK1 signal pathway.

Traditional Chinese medicine's intervention in endothelial nitric oxide synthase activation and nitric oxide synthesis in cardiovascular system

Cardiovascular disease (CVD) is one of the most dangerous diseases which has become a major cause of human death. Many researches evidenced that nitric oxide (NO)/endothelial nitric oxide synthase (eNOS) system plays a significant role in the occurrence and development of CVD. NO, an important signaling molecule, closely associated with the regulation of vasodilatation, blood rheology, blood clotting and other physiological and pathological processes. The synthesis of NO in the endothelial cells primarily depends on the eNOS activity, thus the exploration of the mechanisms and effects of the eNOS activation on NO production is of great significance. Recently, studies on the effects of traditional Chinese medicine (TCM) and its extracts on eNOS activation and NO synthesis have gradually attracted more and more attentions. In this paper, we reviewed the mechanisms of NO synthesis and eNOS activation in the vascular endothelial cells (VECs) and intervention of TCM, so as to provide reference and train of thought to the intensive study of NO/eNOS system and the research and development of new drug for the treatment of CVD.

Tetramethylpyrazine ameliorates high glucose-induced endothelial dysfunction by increasing mitochondrial biogenesis

Tetramethylpyrazine (TMP) is an active compound isolated from a Chinese herbal prescription that is widely used in traditional Chinese medicine for the treatment of inflammatory and cardiovascular diseases. We have previously reported that TMP acts as a potent antioxidant protecting endothelial cells against high glucose-induced damages. However, the molecular mechanism responsible for the antioxidant effect of TMP remains to be elucidated. In this study, we show that TMP increases nitric oxide production in endothelial cells and promotes endothelium-dependent relaxation in rate aortic rings. The antioxidant effect of TMP appears attributable to its ability to activate the mitochondrial biogenesis, as reflected in an up-regulation of complex III and amelioration of mitochondrial membrane potential. Furthermore, TMP is able to reverse high glucose-induced suppression of SIRT1 and the biogenesis-related factors, including PGC-1α, NRF1 and TFAM, suggesting a new molecular mechanism underlying the protective effect of TMP on the endothelium.

Serum Containing Tao-Hong-Si-Wu Decoction Induces Human Endothelial Cell VEGF Production via PI3K/Akt-eNOS Signaling

Tao-Hong-Si-Wu decoction (TSD) is a famous traditional Chinese medicine (TCM) and widely used for ischemic disease in China. TSD medicated serum was prepared after oral administration of TSD (1.6 g/kg) twice a day for 3 days in rats. TSD medicated serum induced human umbilical vein endothelial cells (HUVECs) proliferation, VEGF secretion, and nitric oxide (NO) production. These promoted effects of TSD were partly inhibited by treatment with PI3K inhibitor (LY294002) or eNOS inhibitor (L-NAME), respectively, and completely inhibited by treatment with LY294002 and L-NAME simultaneously. Western blot analysis findings further indicated that TSD medicated serum upregulated p-Akt and p-eNOS expressions, which were significantly inhibited by LY294002 or L-NAME and completely inhibited by both LY294002 and L-NAME; these results indicated that TSD medicated serum induced HUVECs VEGF expression via PI3K/Akt-eNOS signaling. TSD medicated serum contains hydroxysafflor yellow A, ferulic acid, and ligustilide detected by UPLC with standards, so these effect of TSD medicated serum may be associated with these three active compounds absorbed in serum.

A prescribed Chinese herbal medicine improves glucose profile and ameliorates oxidative stress in Goto-Kakisaki rats fed with high fat diet

Oxidative stress (OS) plays a role in hyperglycemia induced islet β cell dysfunction, however, studies on classic anti-oxidants didn’t show positive results in treating diabetes. We previously demonstrated that the prescribed Chinese herbal medicine preparation “Qing Huo Yi Hao” (QHYH) improved endothelial function in type 2 diabetic patients. QHYH protected endothelial cells from high glucose-induced damages by scavenging superoxide anion and reducing production of reactive oxygen species. Its active component protected C2C12 myotubes against palmitate-induced oxidative damage and mitochondrial dysfunction. In the present study, we investigated whether QHYH protected islet β cell function exacerbated by high fat diet (HFD) in hyperglycemic GK rats. 4-week-old male rats were randomly divided into high HFD feeding group (n = 20) and chow diet feeding group (n = 10). Each gram of HFD contained 4.8 kcal of energy, 52% of which from fat. Rats on HFD were further divided into 2 groups given either QHYH (3 ml/Kg/d) or saline through gastric tube. After intervention, serum glucose concentrations were monitored; IPGTTs were performed without anesthesia on 5 fasting rats randomly chosen from each group on week 4 and 16. Serum malondialdehyde (MDA) concentrations and activities of serum antioxidant enzymes were measured on week 4 and 16. Islet β cell mass and OS marker staining was done by immunohistochemistry on week 16. QHYH prevented the exacerbation of hyperglycemia in HFD feeding GK rats for 12 weeks. On week 16, it improved the exacerbated glucose tolerance and prevented the further loss of islet β cell mass induced by HFD. QHYH markedly decreased serum MDA concentration, increased serum catalase (CAT) and SOD activities on week 4. However, no differences of serum glucose concentration or OS were observed on week 16. We concluded that QHYH decreased hyperglycemia exacerbated by HFD in GK rats by improving β cell function partly via its antioxidant effect.

Neuroprotective effects of the Chinese Yi-Qi-Bu-Shen recipe extract on injury of rat hippocampal neurons induced by hypoxia/reoxygenation

OBJECTIVE

To explore the protective effects of the Chinese Yi-Qi-Bu-Shen recipe (YB) against neuronal injury induced by hypoxia-reoxygenation, which has shown beneficial effect in improving the brain function of type 2 diabetics likely through its antihyperglycemic, antioxidant activity, and investigate its mechanisms.

METHODS

The bilateral hippocampus was collected from newborn rats to establish single cell suspension. On the 10th day, the primarily cultured hippocampal neurons were randomly divided into five groups: the normal group (NG), the hypoxia/reoxygenation group (HG), and groups protected with small, medium and large dosages of YB (SG, MG and LG, respectively). The YB-protected groups were treated with different concentrations of YB containing serum before reoxygenation. The metabolic rate of MTT, the malondialdehyde (MDA) content, and the activity of superoxide dismutase (SOD) and lactate dehydrogenase (LDH) were measured with assay kits. The apoptosis rate of hippocampal neurons were tested using flow cytometry analysis. RT-PCR was used to evaluate the mRNA expressions of bcl-2 and bax genes.

RESULTS

The SOD activity, the cell survival rate, the bcl-2/bax ratio, and the bcl-2mRNA expression in the HG group were significantly lower (all P<0.01), but the levels of MDA and LDH, the apoptosis rate, and the bax mRNA expression were higher (all P<0.01) than those in the NG group. The SOD activity, the cell survival, the bcl-2mRNA expression, and the bcl-2/bax ratio were significantly higher in all of the YB-protected groups (all P<0.01), but the level of MDA and LDH, the apoptosis rate, and the bax mRNA expression were lower (P<0.01, P<0.05) than those in the HG group in a dose dependent manner.

CONCLUSION

The YB extract has a protective effect on hippocampal neurons against injury induced by hypoxia/reoxygenation, through its antioxidant activity and the regulation of apoptosis.

Fructus Gardenia (Gardenia jasminoides J. Ellis) phytochemistry, pharmacology of cardiovascular, and safety with the perspective of new drugs development

The phytochemistry, cardiovascular pharmacology, toxicology, side effect, and further development prospects of Gardenia jasminoides J. Ellis (GJE) and its main constituents crocins and iridoid glycosides were studied. Numerous studies have confirmed that crocins and iridoid glycosides had effects of antioxidation, anti-inflammatory, anti-atherosclerosis, anti-ischemic brain injuries, anti-platelet aggregation, anti-hyperglycemia, anti-hyperlipidemia, anti-hypertension, and so on. Some of them might be related to several attractive pharmacodynamic actions of GJE such as promoting endothelium growth, protecting neurons, and inducing their differentiation. Both of them make it possible for GJE to prevent and cure thromboembolism and cardiovascular diseases well. From our own basic pharmacological research of GJE extract on several rat models, it has been known that GJE extract markedly prolonged bleeding time and inhibited platelet aggregation and thrombosis. It has significant proliferation effect on both endothelial cells and endothelial progenitor cells as well. As the mechanisms of GJE on those diseases were discussed and summarized, questions about its genetoxicity and hepatotoxicity were also discussed during its safety study to make the foundation for long-term medication and clinical research in the near future.

Protective effect of ligustrazine against myocardial ischaemia reperfusion in rats: the role of endothelial nitric oxide synthase

1. The aim of the present study was to determine whether ligustrazine (2,3,5,6-tetramethylpyrazine; TMP) exerts a cardioprotective effect during myocardial ischaemia reperfusion (IR), and to investigate the underlying mechanisms and the role of endothelial nitric oxide synthase (eNOS) in cardioprotection. 2. Sprague-Dawley rats were divided into a sham group and five IR groups: IR control, TMP pretreated, TMP + wortmannin (a phosphatidylinositol 3-kinase (PI3K) inhibitor), N(G) -nitro-L-arginine methyl ester (L-NAME; a NOS inhibitor) and TMP + L-NAME. IR was produced by 35 min of regional ischaemia followed by 120 min of reperfusion. Myocardial infarct size, oxidative stress, myocardial apoptosis, nitric oxide (NO) production, and expression of phosphorylated protein kinase B (Akt) and eNOS were measured. 3. TMP markedly decreased infarct size and attenuated myocardial apoptosis, as evidenced by a decrease in the apoptotic index and reduced caspase-3 activity. TMP treatment caused a marked increase in NO production. Cotreatment with wortmannin or L-NAME completely blocked the TMP-induced NO increase. TMP induced phosphorylation of Akt at Ser 473 (1.61 ± 0.18 vs 0.79 ± 0.10 in the IR control group) and phosphorylation of eNOS at Ser1177 (1.87 ± 0.33 vs 0.94 ± 0.22 in the IR control group). Wortmannin abrogated the phosphorylation of Akt and eNOS induced by TMP. 4. These data suggest that ligustrazine has anti-apoptotic and cardioprotective effects against myocardial IR injury and that it acts through the PI3K/Akt pathway. In addition, the phosphorylation of eNOS with subsequent NO production was found to be an important downstream effector that contributes significantly to the cardioprotective effect of TMP.

TMP prevents retinal neovascularization and imparts neuroprotection in an oxygen-induced retinopathy model

PURPOSE

To evaluate the effects of tetramethylpyrazine (TMP) on retinal neovascularization (NV) and neuroprotection in an oxygen-induced retinopathy (OIR) model.

METHODS

Neonatal C57BL/6J mice were subjected to 75% oxygen from postnatal day 7 (P7) to P12 and then returned to room air. TMP (200 mg/kg) or normal saline was given daily from P12 to P17. Immunostaining, HE staining, TUNEL assay, and RT-PCR were used to assess the effects of TMP on retinal neurovascular repair.

RESULTS

TMP effectively prevented pathologic NV and accelerated physiologic revascularization by enhancing the formation of endothelial tip cells at the edges of the repairing capillary networks and preserving the astrocytic template in the avascular retina. TMP also prevented morphologic changes and significantly decreased TUNEL-positive cells in the avascular retina by rescuing neurons such as amacrine, rod bipolar, horizontal, and Müller cells. In TMP-treated mice retinas, there was a less obvious loss of amacrine cell bodies and their distinct bands; the number of both rod bipolar and horizontal cell bodies, as well as the density of their dendrites in the outer plexiform layer, was greater than that in OIR control mice. TMP not only decreased the loss of alignment of Müller cell bodies and distortion of processes but reduced the reactive expression of GFAP in Müller cells. Furthermore, HIF-1α and VEGF mRNA expression were downregulated in TMP-treated mice retinas.

CONCLUSIONS

TMP improved neurovascular recovery by preventing NV and protecting retinal astroglia cells and neurons from ischemia-induced cell death partially due to its downregulation of HIF-1α and VEGF mRNA expression.

Traditional Chinese medicine formula Qing Huo Yi Hao as superoxide anion scavenger in high glucose-treated endothelial cells

AIM

To investigate the effects of a traditional Chinese medicine formula Qing Huo Yi Hao (QHYH) and its components on hydroxyl radical (HO(•)) production in vitro and the activity of QHYH against free radicals in cultured endothelial cells induced by high glucose.

METHODS

Hydroxyl radicals (HO(•)) were generated through Fenton reactions in vitro, and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) was used as a spin trap to form DMPO/HO(•) adducts detected using electron paramagnetic resonance (EPR). Immortalized mouse cerebral microvascular endothelial (bEnd.3) cells were treated with high glucose (35 mmol/L). The free radical scavenging ability of QHYH in the cells was evaluated using EPR. Superoxide dismutase (SOD) was used to identify the free radicals scavenged by QHYH in the cells.

RESULTS

QHYH and its 8 components concentration-dependently reduced DMPO/HO(•) signaling. The DMPO/HO(•) adduct scavenging ability of QHYH was 82.2%, which was higher than each individual component. The free radical scavenging ability of 1% QHYH in high glucose-treated bEnd.3 cells was approximately 70%. In these cells, the free radicals were also specifically reduced by SOD (400 U/mL), implying that the free radicals were primarily superoxide anions.

CONCLUSION

The results demonstrate that the QHYH formula is potent antioxidant acting as scavenge of superoxide anions in high glucose-treated endothelial cells.

Protective effect of tetramethylpyrazine isolated from Ligusticum chuanxiong on nephropathy in rats with streptozotocin-induced diabetes

PURPOSE

This study was designed to investigate the protective effect of tetramethylpyrazine isolated from Ligusticum chuanxiong, a traditional Chinese medicine, on diabetic nephropathy in a rat model, and to explore the possible mechanism involved in a protective function.

MATERIALS

Diabetes was induced in male Sprague-Dawley rats by a single intraperitoneal injection of 70mg/kg of streptozotocin. One week later, 200mg/kg/day of tetramethylpyrazine was administered intragastric gavage daily for 8 weeks. Renal functions and expression of vascular endothelial growth factor were examined at 4 and 8 weeks after tetramethylpyrazine administration.

RESULTS

Blood glucose and renal function were significantly improved in the tetramethylpyrazine-treated group compared to the untreated diabetic rats. Diabetic nephropathy resulted in an increase in the expression of vascular endothelial growth factor, while tetramethylpyrazine administration greatly decreased the expression.

CONCLUSIONS

Our results suggest that administration of tetramethylpyrazine may reduce kidney damage caused by diabetes. This protective effect may be mediated, in part, by downregulated expression of vascular endothelial growth factor in the kidney.

Tetramethylpyrazine inhibits hypoxia-induced pulmonary vascular leakage in rats via the ROS-HIF-VEGF pathway

Tetramethylpyrazine (TMP) is a reactive oxygen species (ROS) antagonist that has potent properties for the treatment of a variety of vascular diseases, such as ischemic stroke and pulmonary hypertension secondary to chronic obstructive pulmonary diseases. However, there are few data about the role of TMP in hypoxia-induced pulmonary vascular leakage. This study examined the effect of TMP on hypoxia-induced pulmonary vascular leakage and the underlying mechanisms. Rat pulmonary microvascular endothelial cells (RPMVECs) treated with TMP or not were subjected to hypoxic or normoxic conditions for 24 h, and the monolayer permeability, intracellular ROS, hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) proteins levels were determined. Additionally, rats administrated TMP were exposed to hypobaric hypoxia to evaluate the effect of TMP in vivo by measuring lung water content, pulmonary vascular leakage into the lungs and immunohistochemistry for HIF-1α and VEGF. Hypoxia was found to cause a significant increase in RPMVEC monolayer permeability and intracellular ROS, HIF-1α and VEGF protein levels. Treatment with TMP decreased the hypoxia-induced RPMVEC monolayer permeability and attenuated the elevation of ROS, HIF-1α and VEGF protein levels. TMP-treated animals showed less pulmonary vascular leakage and HIF-1α and VEGF expression compared with those exposed to hypoxia alone. These observations supported that TMP inhibited the increase in pulmonary vascular permeability induced by hypoxia. The underlying mechanisms may be related to the scavenging of intracellular ROS and the suppression of hypoxia-induced upregulation of HIF-1α and VEGF proteins.

The vasoprotective effect of JP05 through the activation of PI3K/Akt-dependent eNOS and MEK/ERK pathways in brain endothelial cells

AIM OF THE STUDY

Endothelial dysfunction is involved in stroke. Recent therapeutic options for stroke have focused on the combination therapy with a polyherbal mixture. This study was designed to provide insight into the effects of JP05, a water extract of 12 herbs, on the levels of regulators in bEnd.3 mouse brain endothelial cells.

MATERIALS AND METHODS

Production of endothelial nitric oxide synthase (eNOS)-mediated nitric oxide (NO), the expression of vascular endothelial growth factor (VEGF) and the phosphorylations of eNOS, phosphatidylinositol 3-kinase (PI3K)/Akt, extracellular signal-regulated protein kinase (ERK) and cAMP response element binding protein (CREB) in JP05 were assayed in bEnd.3 cells, a mouse brain endothelial line.

RESULTS

JP05 led to increase the levels of eNOS-mediated NO generation and VEGF expression in bEnd.3 cells. JP05 induced the phosphorylation of eNOS, Akt and ERK in bEnd.3 cells. As well, JP05 blocked the inhibition of PI3K/Akt and ERK activities by LY294002 (PI3K/Akt inhibitor) and PD98059 (mitogen-activated protein kinase inhibitor), respectively. JP05 also induced the phosphorylation of CREB, which plays an important role in endothelial cell function and blood vessel development.

CONCLUSION

Taken together, these results indicate that JP05 can upregulate eNOS-mediated NO generation and VEGF expression through the ERK and/or PI3K/Akt activation, an upstream event of angiogenesis. JP05 with vasoprotective properties has a potential therapy for human brain diseases including stroke.