Involvement of glutamate-cystine/glutamate transporter system in aspirin-induced acute gastric mucosa injury.

Large-dose or long-term use of aspirin tends to cause gastric mucosa injury, which is recognized as the major side effect of aspirin. It has been demonstrated that glutamate exerts a protective effect on stomach, and the level of glutamate is critically controlled by cystine/glutamate transporter (Xc(-)). In the present study, we investigated the role of glutamate-cystine/glutamate transporter system in aspirin-induced acute gastric mucosa injury in vitro and in vivo. Results showed that in human gastric epithelial cells, aspirin incubation increased the activity of LDH and the number of apoptotic cells, meanwhile down-regulated the mRNA expression of Xc(-) accompanied with decreased glutamate release. Similar results were seen in a rat model. In addition, exogenous l-glutamate attenuated the gastric mucosa injury and cell damage induced by aspirin both in vitro and in vivo. Taken together, our results demonstrated that acute gastric mucosa injury induced by aspirin is related to reduction of glutamate-cystine/glutamate transporter system activity.

Involvement of DDAH/ADMA pathway in the pathogenesis of rheumatoid arthritis in rats.

Endothelial dysfunction is the early stage of atherosclerosis, which is typically associated with rheumatoid arthritis (RA), a chronic inflammatory autoimmune disorder. Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, is not only an independent predictor for endothelial dysfunction but also a proinflammatory mediator. It has been shown that the level of ADMA was elevated in patients with RA. In the present study, we investigated the potential effect of ADMA on inflammation process in collagen-induced arthritis (CIA) animal model and primary cultured fibroblast-like synoviocytes (FLS) exposed to tumor necrosis factor-α (TNF-α). In CIA rats, the plasma levels of inflammatory cytokines TNF-α, interleukin-1ß (IL-1ß) and IL-6 were markedly increased, while the plasma levels of ADMA did not increase. The expression of dimethylarginine dimethylohydrolase2 (DDAH2), the key enzyme for ADMA degradation, was markedly reduced in inflamed joint synovium of CIA rats. Moreover, the expression of anti-inflammatory factor cortistatin (CST) was markedly decreased in joint synovium of CIA rats. Treatment of cultured FLS with TNF-α significantly increased the levels of ADMA, and decreased the expression of DDAH2 mRNA and protein accompany with an increase in the levels of IL-1ß and IL-6 and a reduction in the expression of CST mRNA and protein, and the effects of TNF-α were abolished by DDAH2 overexpression. Treatment of FLS with ADMA also significantly increased the levels of IL-1ß and IL-6, and reduced the expression of CST. These findings suggest that DDAH/ADMA participates in the pathogenesis of RA, and that the effect of DDAH/ADMA may be mediated by CST.

Two new selaginellin derivatives from Selaginella tamariscina (Beauv.) Spring.

Two new selaginellin derivatives, selaginellins K (1) and L (2), were isolated from Selaginella tamariscina (Beauv.) Spring and characterized as 2-formyl-4,4'-dihydroxy-3-[(4-hydroxyphenyl)ethynyl]biphene and 4,4'-dihydroxy-2-methyl-3-[(4-hydroxyphenyl)ethynyl]biphene on the basis of their spectroscopic data including UV, IR, 1D, and 2D NMR as well as HR-ESI-MS spectroscopic analysis.

Selaginellins I and J, two new alkynyl phenols, from Selaginella tamariscina (Beauv.) Spring.

Selaginellins I (1) and J (2), two new compounds, were isolated from Selaginella tamariscina (Beauv.) Spring and were characterized as (R,S)-4-((2',4'-dihydroxy-4-(hydroxymethyl)-3-((4-hydroxyphenyl)ethynyl)biphenyl-2-yl)(4-hydroxyphenyl)methylene)cyclohexa-2,5-dienone (1) and (R,S)-4-((3-((3,4-dihydroxyphenyl)ethynyl)-4'-hydroxy-4-(hydroxymethyl)biphenyl-2-yl)(4-hydroxyphenyl)methylene)cyclohexa-2,5-dienone (2) on the basis of UV, IR, 1D and 2D NMR, and HR-ESI-MS spectroscopic analysis.

Protective effect of phloroglucinol against myocardial ischaemia-reperfusion injury is related to inhibition of myeloperoxidase activity and inflammatory cell infiltration.

1. It has been shown that phloroglucinol has anti-inflammatory and anti-oxidant properties. Both inflammatory cell infiltration and myeloperoxidase (MPO) activation play an important role in myocardial reperfusion injury. The aim of the present study was to explore the effect of phloroglucinol on myocardial reperfusion injury and the mechanisms involved. 2. Anaesthetized rats were pretreated with phloroglucinol (15 or 30 mg/kg, i.g.) or vehicle (5 mmol/L carboxymethyl cellulose sodium) 30 min prior to experimentation. The left main coronary artery was subjected to 1 h occlusion followed by 3 h reperfusion. Infarct size, the release of creatine kinase (CK), inflammatory cell infiltration, MPO activity and protein content, catalase in the blood and myocardium, and myocardial apoptosis were measured. 3. Following myocardial ischaemia and reperfusion in vehicle-treated rats, infarct size was 43.5 ± 3.7% (relative to the area at risk). Accompanying detrimental changes included elevated CK, enhanced inflammatory cell infiltration, high numbers of myocardial apoptotic cells, elevated caspase 3 activity, increased MPO activity and content in the plasma and myocardium and reduced catalase activity. These effects were attenuated by pretreatment with both doses of phloroglucinol (15 and 30 mg/kg, i.g.). 4. The results of the present study suggest that phloroglucinol protects the myocardium against ischaemia-reperfusion injury in rats and that its beneficial effects are related to inhibition of MPO activity and inflammatory cell infiltration.

A new flavonoid from Selaginella tamariscina (Beauv.) Spring.

A new flavonoid, 6-(2-hydroxy-5-carboxyphenyl)-apigenin (1), together with two new natural products, 3-(4-hydroxyphenyl)-6,7-dihydroxy coumarin (2), 1-methoxy-3-methylanthraquinone (3) and four known compounds, were isolated from Selaginella tamariscina (BEAUV.) SPRING. The structures of the new isolated compounds were elucidated on the basis of 1D and 2D NMR as well as ESI-HR-MS spectroscopic analysis.

Protective effect of selaginellin on glutamate-induced cytotoxicity and apoptosis in differentiated PC12 cells.

L-glutamate plays a key role in neuronal cell death associated with many neurodegenerative conditions such as cerebral ischemia, hypoxia, Alzheimer's, Huntington's, and Parkinson's diseases. Selaginellin, a component extracted from Saussurea pulvinata (Hook.et Grev.) Maximo, was assessed for its ability to protect rat pheochromocytoma (PC12) cells against oxidative toxicity induced by glutamate. The differentiated PC12 cells were pretreated with various concentrations (10(-7), 3 x 10(-7), or 10(-6) M) of selaginellin for 1 h prior to exposure to L-glutamate. Selaginellin was shown to protect PC12 cells against glutamate toxicity, as determined by characteristic morphological features, lactate dehydrogenase release and cell viability, and apoptosis as evaluated by Hoechst 33342 staining assay and caspase-3 activity. In addition, the increase in levels of reactive oxygen species and decrease in klotho gene expression induced by glutamate were significantly reversed by selaginellin. Our study suggests that selaginellin has a neuroprotective effect against L-glutamate-induced neurotoxicity through mechanisms related to anti-oxidation and anti-apoptosis via scavenging reactive oxygen species and up-regulating the expression of klotho gene.

Demethylbellidifolin prevents nitroglycerin tolerance via improved aldehyde dehydrogenase 2 activity.

The aim of this study was to investigate the effect of demethylbellidifolin (DMB), a major xanthone compound of Swertia davidi franch, on nitroglycerin (NTG) tolerance. In the in vivo portion of the study, pretreatment of Sprague-Dawley rats with NTG (10 mg/kg) for 8 days caused tolerance to the depressor effect of NTG. This was evident because the depressor effect of NTG (150 microg/kg, I. V.) was almost completely abolished in the tolerant rats. The tolerance could be diminished by treatment with DMB. In the in vitro study, the exposure of aortic rings of Sprague-Dawley rats to NTG (10 microM) for 30 min caused tolerance to the vasodilating effect of NTG. The tolerance is evident because of a substantial right shift of the NTG concentration-relaxation curves. This shift was reduced by pretreatment of the aortic rings with DMB. In cultured human umbilical vein endothelial cells (HUVECs), incubation of NTG for 16 h increased reactive oxygen species (ROS) production, attenuated cyclic guanosine monophosphate (cGMP) levels and decreased the activity of aldehyde dehydrogenase 2 (ALDH-2), the main enzyme responsible for NTG bioactivation. All the effects mentioned above were prevented by co-incubation with DMB. In conclusion, DMB prevents NTG tolerance via increasing ALDH-2 activity through decreasing ROS production.

Involvement of prolylcarboxypeptidase in the effect of rutaecarpine on the regression of mesenteric artery hypertrophy in renovascular hypertensive rats.

1. Previous studies indicate that rutaecarpine blocks increases in blood pressure and inhibits vascular hypertrophy in experimentally hypertensive rats. The aim of the present study was to determine whether the effects of rutaecarpine are related to activation of prolylcarboxypeptidase (PRCP). 2. Renovascular hypertensive rats (Goldblatt two-kidney, one-clip (2K1C)) were developed using male Sprague-Dawley rats. Chronic treatment with rutaecarpine (10 or 40 mg/kg per day) or losartan (20 mg/kg per day) for 4 weeks to the hypertensive rats caused a sustained dose-dependent attenuation of increases in blood pressure, increased lumen diameter and decreased media thickness, which was accompanied by a similar reduction in the media cross-sectional area : lumen area ratio in mesenteric arteries compared with untreated hypertensive rats. 3. Angiotensin (Ang) II expression was significantly increased in mesenteric arteries of hypertensive rats compared with sham-operated rats. No significant differences in plasma AngII levels were observed between untreated hypertensive and sham-operated rats. Hypertensive rats treated with high-dose rutaecarpine had significantly decreased Ang II levels in both the plasma and mesenteric arteries. 4. Expression of PRCP protein or kallikrein mRNA was significantly inhibited in the right kidneys and mesenteric arteries of hypertensive rats. However, expression of PRCP protein and kallikrein mRNA was significantly increased after treatment with rutaecarpine or losartan (20 mg/kg per day). 5. The data suggest that the repression of increases in systolic blood pressure and reversal of mesenteric artery remodelling by rutaecarpine may be related to increased expression of PRCP in the circulation and small arteries in 2K1C hypertensive rats.

Selaginellin C, a new natural pigment from Selaginella pulvinata Maxim (Hook et Grev.).

A novel compound, selaginellin C (1), was isolated from Selaginella pulvinata Maxim (Hook et Grev.) as (R,S)-4-((1,2-dihydroxyethyl)-2',4'-dihydroxy-3-((4-hydroxyphenyl)ethynyl)biphenyl-2-yl)((4-hydroxyphenyl)methylene)cyclohexa-2,5-dienone, along with two known compounds, selaginellin (2) and selaginellin A (3). The structure of the new compound was elucidated on the basis of 1D and 2D NMR as well as HR-ESI-MS spectroscopic analysis.

Calcitonin gene-related peptide-mediated antihypertensive and anti-platelet effects by rutaecarpine in spontaneously hypertensive rats.

We have previously reported that Chinese traditional medicine rutaecarpine (Rut) produced a sustained hypotensive effect in phenol-induced and two-kidney, one-clip hypertensive rats. The aims of this study are to determine whether Rut could exert antihypertensive and anti-platelet effects in spontaneously hypertensive rats (SHR) and the underlying mechanisms. In vivo, SHR were given Rut and the blood pressure was monitored. Blood was collected for the measurements of calcitonin gene-related peptide (CGRP), tissue factor (TF) concentration and activity, and platelet aggregation, and the dorsal root ganglia were saved for examining CGRP expression. In vitro, the effects of Rut and CGRP on platelet aggregation were measured, and the effect of CGRP on platelet-derived TF release was also determined. Rut exerted a sustained hypotensive effect in SHR concomitantly with the increased synthesis and release of CGRP. The treatment of Rut also showed an inhibitory effect on platelet aggregation concomitantly with the decreased TF activity and TF antigen level in plasma. Study in vitro showed an inhibitory effect of Rut on platelet aggregation in the presence of thoracic aorta, which was abolished by capsazepine or CGRP(8-37), an antagonist of vanilloid receptor or CGRP receptor. Exogenous CGRP was able to inhibit both platelet aggregation and the release of platelet-derived TF, which were abolished by CGRP(8-37). The results suggest that Rut exerts both antihypertensive and anti-platelet effects through stimulating the synthesis and release of CGRP in SHR, and CGRP-mediated anti-platelet effect is related to inhibiting the release of platelet-derived TF.

Asymmetric dimethylarginine induces TNF-alpha production via ROS/NF-kappaB dependent pathway in human monocytic cells and the inhibitory effect of reinioside C.

Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase (NOS) inhibitor, has been implicated in vascular inflammation through induction of reactive oxygen species (ROS) and proinflammatory genes in endothelial cells. However, relatively few attentions have been paid to the effect of ADMA on monocytes, one of the important cells throughout all stages of atherosclerosis. In the present study, we found that reinioside C, the main component extracted from Polygala fallax Hemsl., dose-dependently inhibited tumor necrosis factor-alpha (TNF-alpha) production induced by ADMA in monocytes, Furthermore, reinioside C attenuated ADMA-induced generation of reactive oxygen species and activation of nuclear factor-kappaB (NF-kappaB) activity in monocytes in a dose-dependent manner, this effect was inhibited by l-arginine (NOS substrate) and PDTC (inhibitor of NF-kappaB). These data suggest that reinioside C could attenuate the increase of TNF-alpha induced by exogenous ADMA through inhibition ROS/NF-kappaB pathway in monocytes.

[Effects of Tongxinluo on cell viability and tissue factor in AngII induced vascular endothelial cells].

OBJECTIVE: To determine the effects of Tongxinluo on cell viability and tissue factor (TF) in AngII induced vascular endothelial cells and to investigate its mechanism. METHODS: AngII(10(-6)mol/L) was added to human vascular endothelial cells (HUVECs) culture media alone or with various concentration of Tongxinluo drug containing plasma (5%,10%, and 20%) added 30 minutes before AngII. Cell viability was evaluated after 24-hour incubation with AngII in a dose manner. TF, AngII type 1 receptor (AT(1)) mRNA, NO synthase (NOS) and NO were observed after 24-hour incubation with AngII. In addition, NOS inhibitor nomega-nitro-larginine (L-NAME) was added 30 minutes before Tongxinluo and AngII. Cell viability, TF, AT(1)mRNA, the level of NOS and NO were evaluated after 24-hour incubation with Tongxinluo and AngII. RESULTS: Tongxinluo significantly improved AngII induced endothelial cell viability and the effect was the most obvious at 10%. Tongxinluo (10%) decreased the TF and AT(1) mRNA while increased the NOS and NO levels. L-NAME obviously inhibited the effects of Tongxinluo on cell viability, TF, AT(1) mRNA, and NOS and NO levels. CONCLUSION: Up-regulating NOS-NO signaling may be the mechanism of Tongxinluo on cell viability and TF in AngII induced vacular endothelial cells.

[Inhibitory effect of reinioside C on LOX-1 expression induced by ox-LDL].

OBJECTIVE: To investigate the effect of reinioside C (RC) on the expression of lectin-like oxidized low density lipoprotein receptor (LOX)-1 mRNA and LOX-1 protein induced by oxidized low density lipoprotein (ox-LDL) in cultured human umbilical vein endothelial cells (HUVEC). METHODS: HUVECs were cultured with ox-LDL (50 mg/L) for 24 h in the absence or presence of RC (1, 3, and 10 micromol/L). The expressions of LOX-1 mRNA and LOX-1 protein were examined by RT-PCR and Western-blot. RESULTS: Incubation with ox-LDL (50 mg/L) significantly raised the expression of LOX-1 mRNA and LOX-1 protein,which was concentration-dependent. CONCLUSION: RC can inhibit the increased expression of LOX-1 mRNA and LOX-1 protein induced by ox-LDL in HUVECs.

The protective effects of rutaecarpine on gastric mucosa injury in rats.

Previous investigations have shown that calcitonin gene-related peptide (CGRP) protects gastric mucosa against injury induced by acetylsalicylic acid (ASA) and that rutaecarpine activates vanilloid receptors to evoke CGRP release. In the present study, we examined the protective effects of rutaecarpine on gastric mucosa injury, and explored whether the protective effects of rutaecarpine are related to stimulation of endogenous CGRP release via activating vanilloid receptors in rats. In an ASA-induced ulceration model, gastric mucosal ulcer index, pH value of gastric juice and plasma concentrations of CGRP were determined. ASA significantly increased the gastric mucosal ulcer index and the back-diffusion of H+ through the mucosa. Rutaecarpine at the doses of 100 or 300 microg/kg (i.v.), and 300 or 600 microg/kg (intragastric, i.g.) reduced the ulcer index and back-diffusion of H+, which was abolished by pretreatment with capsaicin (50 mg/kg, s.c.) or capsazepine (3 mg/kg, i.v.), a competitive vanilloid receptor antagonist. Rutaecarpine significantly increased the plasma concentration of CGRP, which was also abolished by capsazepine. In a stress-induced ulceration model, rutaecarpine reduced gastric mucosal damages, which was abolished by capsazepine (5 mg/kg, i.p.). These results suggest that rutaecarpine protects the gastric mucosa against injury induced by ASA and stress, and that the gastroprotective effect of rutaecarpine is related to a stimulation of endogenous CGRP release via activation of the vanilloid receptor.

Aspirin protected against endothelial damage induced by LDL: role of endogenous NO synthase inhibitors in rats.

AIM: To study the protective effect of aspirin on damages of the endothelium induced by low-density lipoprotein (LDL), and whether the protective effect of aspirin is related to reduction of nitric oxide synthase inhibitor level. METHODS: Vascular endothelial injury was induced by a single injection of native LDL (4 mg/kg) in rats. Vasodilator responses to acetylcholine (ACh) in the isolated aortic rings were determined, and serum concentrations of asymmetric dimethylarginine (ADMA), malondialdehyde (MDA), tumour necrosis factor-alpha (TNF-alpha), and the activity of dimethylaminohydrolase (DDAH) were measured. RESULTS: A single injection of LDL (4 mg/kg) significantly decreased vasodilator responses to ACh, increased the serum level of ADMA, MDA, and TNF-alpha, and decreased DDAH activity. Aspirin (30 or 100 mg/kg) markedly reduced the inhibition of vasodilator responses to ACh by LDL, and the protective effect of aspirin at the lower dose was greater compared with high-dose aspirin group. Aspirin inhibited the increased level of MDA and TNF-alpha induced by LDL. Aspirin at the dose of 30 mg/kg, but not at higher dose (100 mg/kg), significantly reduced the concentration of ADMA and increased the activity of DDAH. CONCLUSION: Aspirin at the lower dose (30 mg/kg) protects the endothelium against damages elicited by LDL in vivo, and the protective effect of aspirin on endothelium is related to reduction of ADMA concentration by increasing DDAH activity.

The protective effects of ligustrazine on ischemia-reperfusion and DPPH free radical-induced myocardial injury in isolated rat hearts.

Previous investigations have suggested that tumor necrosis factor-alpha (TNF-alpha) can contribute to myocardial damage during ischemia-reperfusion. In the present study, we examined whether the cardioprotective effects of ligustrazine are related to inhibition of TNF-alpha production in the rat models of ischemia-reperfusion and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-induced myocardial injury. Ischemia for 20 min and reperfusion for 40 min caused a decline in cardiac function (left ventricular pressure, +/- d p/d t(max), heart rate and coronary flow) and an increase in the release of creatine kinase in coronary effluent and the content of TNF-alpha in myocardial tissues. Similarly, perfusion with DPPH (100 nM) for 30 min significantly decreased cardiac function, and increased the release of creatine kinase and the content of TNF-alpha. Ligustrazine at the concentration of 40 or 80 mg/L markedly improved cardiac function and reduced the release of creatine kinase and the content of TNF-alpha in myocardial tissues in hearts subjected to ischemia-reperfusion or DPPH perfusion. These results suggest that the cardioprotection afforded by ligustrazine is related to a reduction of TNF-alpha content by inhibition of free radical production in isolated rat hearts.

Demethylbellidifolin preserves endothelial function by reduction of the endogenous nitric oxide synthase inhibitor level.

The present study examined the anti-oxidation and protective effects of demethylbellidifolin (DMB), a xanthone compound extracted from swertia davidi Franch, on endothelium. The relationship between the protective effects of DMB on endothelium and the level of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, was also determined in the present study. DMB significantly inhibited Cu(2+)-induced low-density lipoprotein (LDL) oxidation and scavenged DPPH radicals. DMB significantly attenuated the inhibition of endothelium-dependent vasodilator responses, induced by lysophosphatidycholine (LPC) in vitro and LDL in vivo, and increased release of lactate dehydrogenase induced by LDL in cultured endothelial cells. DMB significantly attenuated the increased concentration of malondialdehyde and ADMA, and the decreased level of nitric oxide induced by LDL in vivo and in cultured endothelial cells. DMB also significantly reduced the decreased activity of dimethylarginine dimethylaminohydrolase (DDAH) induced by LDL in cultured endothelial cells. In summary, the present results suggest that DMB protects endothelial damage induced by LPC in vitro and LDL in vivo or in endothelial cells, and the protective effect of DMB on the endothelium is related to reduction of ADMA concentration via an increase of DDAH activity by inhibition of lipid peroxidation.

Protective effects of rutaecarpine in cardiac anaphylactic injury is mediated by CGRP.

Previous investigations have indicated that rutaecarpine activates the vanilloid receptor to evoke calcitonin gene-related peptide (CGRP) release. CGRP has been shown to alleviate cardiac anaphylactic injury. In the present study, the effect of rutaecarpine on cardiac anaphylaxis was examined. Challenge of presensitized guinea-pig hearts with a specific antigen caused marked decreases in coronary flow (CF), left ventricular pressure (LVP) and its derivatives (+/- dp/dt(max)), an increase in heart rate, and prolongation of the P-R interval. Rutaecarpine (0.3 or 1 microM) markedly increased the content of calcitonin gene-related peptide (CGRP) in the coronary effluent and decreased the content of tumor necrosis factor-alpha (TNF-alpha) in myocardial tissues concomitantly with a significant improvement of cardiac function and alleviation of the extension of the P-R interval. Rutaecarpine at the concentration of 1 microM also inhibited the sinus tachycardia. The protective effects of rutaecarpine on cardiac anaphylaxis were abolished by CGRP (8-37), a selective CGRP receptor antagonist. These results suggest that the protective effects of rutaecarpine on cardiac anaphylactic injury are related to inhibition of TNF-alpha production by stimulation of CGRP release.

Protective effects of evodiamine on myocardial ischemia-reperfusion injury in rats.

Previous investigations have indicated that the pharmacological activities of evodiamine, a major alkaloidal component of the dried, unripe fruit of Evodia rutaecarpa Bentham (Rutaceae), are associated with the stimulation of calcitonin gene-related peptide (CGRP) release and that CGRP protects the myocardium against ischemia-reperfusion injury. In the present study, we have examined whether evodiamine protects against myocardial ischemia-reperfusion injury in rats and whether the protective effects of evodiamine are related to the activation of capsaicin-sensitive sensory nerves. Rats were pretreated with evodiamine 10 min before the experiment, and then the left main coronary artery of rat hearts was subjected to 60 min occlusion followed by 180 min reperfusion. Infarct size, the activity of serum creatine kinase, serum concentrations of TNF-alpha and plasma concentrations of CGRP were measured. Pretreatment with evodiamine (30 or 60 microg/kg, i.v.) markedly increased the content of CGRP in plasma concomitantly with a significant reduction in infarct size, the activity of serum creatine kinase, and TNF-alpha level, and the effects of evodiamine were completely abolished by capsazepine (5.0 mg/kg, s.c.), a competitive vanilloid receptor antagonist. These results suggest that evodiamine exerts a protection against myocardial ischemia-reperfusion injury in rats and that the protective effects of evodiamine are related to stimulation of CGRP release via activation of vanilloid receptors.