Vinpocetine Attenuates Pathological Cardiac Remodeling by Inhibiting Cardiac Hypertrophy and Fibrosis.

PURPOSE: Pathological cardiac remodeling, characterized by cardiac hypertrophy and fibrosis, is a pathological feature of many cardiac disorders that leads to heart failure and cardiac arrest. Vinpocetine, a derivative of the alkaloid vincamine, has been used for enhancing cerebral blood flow to treat cognitive impairment. However, its role in pathological cardiac remodeling remains unknown. The aim of this study is to examine the effect of vinpocetine on pathological cardiac remodeling induced by chronic stimulation with angiotensin II (Ang II). METHODS: Mice received Ang II infusion via osmotic pumps in the presence of vehicle or vinpocetine. Cardiac hypertrophy and fibrosis were assessed by morphological, histological, and biochemical analyses. Mechanistic studies were carried out in vitro with isolated mouse adult cardiac myocytes and fibroblasts. RESULTS: We showed that chronic Ang II infusion caused cardiac hypertrophy and fibrosis, which were all significantly attenuated by systemic administration of vinpocetine. In isolated adult mouse cardiomyocytes, vinpocetine suppressed Ang II-stimulated myocyte hypertrophic growth. In cultured cardiac fibroblasts, vinpocetine suppressed TGFß-induced fibroblast activation and matrix gene expression, consistent with its effect in attenuating cardiac fibrosis. The effects of vinpocetine on cardiac myocyte hypertrophy and fibroblast activation are likely mediated by targeting cyclic nucleotide phosphodiesterase 1 (PDE1). CONCLUSIONS: Our results reveal a novel protective effect of vinpocetine in attenuating pathological cardiac remodeling through suppressing cardiac myocyte hypertrophic growth and fibroblast activation and fibrotic gene expression. These studies may also shed light on developing novel therapeutic agents for antagonizing pathological cardiac remodeling.

Higenamine protects ischemia/reperfusion induced cardiac injury and myocyte apoptosis through activation of ß2-AR/PI3K/AKT signaling pathway.

Cardiomyocyte apoptosis contributes to ischemic cardiac injury and the development of heart failure. Higenamine is a key component of the Chinese herb aconite root that has been prescribed for treating symptoms of heart failure for thousands of years in the oriental Asian countries. It has been shown that higenamine has anti-apoptotic effects in a few cell types including cardiomyocytes. However, the pharmacological target and molecular mechanism of higenamine in the heart are still not fully illustrated. Herein, we report that higenamine protected myocyte apoptosis and ischemia/reperfusion (I/R) injury through selective activation of beta2-adrenergic receptor (ß2-AR). In particular, we show that higenamine significantly reduced I/R-induced myocardial infarction in mice. In both primary neonatal rat and adult mouse ventricular myocytes, we show higenamine inhibited cell apoptosis and also reduced biochemical markers of apoptosis such as cleaved caspase 3 and 9. More importantly, we show that the anti-apoptotic effects of higenamine in cardiomyocytes were completely abolished by ß2-AR but not ß1-AR antagonism. Furthermore, we confirmed that higenamine attenuated I/R-induced myocardial injury and reduced cleaved caspases in a ß2-AR dependent manner in intact mouse hearts. Higenamine stimulated AKT phosphorylation and required PI3K activation for the anti-apoptotic effect in cardiomyocytes. These findings together suggest that anti-apoptotic and cardiac protective effects of higenamine are mediated by the ß2-AR/PI3K/AKT cascade.

Nuclear cardiac myosin light chain 2 modulates NADPH oxidase 2 expression in myocardium: a novel function beyond muscle contraction.

Recent studies demonstrated that NADPH oxidase 2 (NOX2) expression in myocardium after ischemia-reperfusion (IR) is significantly upregulated. However, the underlying mechanisms remain unknown. This study aims to determine if nuclear cardiac myosin light chain 2 (MYL2), a well-known regulatory subunit of myosin, functions as a transcription factor to promote NOX2 expression following myocardial IR in a phosphorylation-dependent manner. We examined the phosphorylation status of nuclear MYL2 (p-MYL2) in a rat model of myocardial IR (left main coronary artery subjected to 1 h ligation and 3 h reperfusion) injury, which showed IR injury and upregulated NOX2 expression as expected, accompanied by elevated H2O2 and nuclear p-MYL2 levels; these effects were attenuated by inhibition of myosin light chain kinase (MLCK). Next, we explored the functional relationship of nuclear p-MYL2 with NOX2 expression in H9c2 cell model of hypoxia-reoxygenation (HR) injury. In agreement with our in vivo findings, HR treatment increased apoptosis, NOX2 expression, nuclear p-MYL2 and H2O2 levels, and the increases were ameliorated by inhibition of MLCK or knockdown of MYL2. Finally, molecular biology techniques including co-immunoprecipitation (Co-IP), chromatin immunoprecipitation (ChIP), DNA pull-down and luciferase reporter gene assay were utilized to decipher the molecular mechanisms. We found that nuclear p-MYL2 binds to the consensus sequence AGCTCC in NOX2 gene promoter, interacts with RNA polymerase II and transcription factor IIB to form a transcription preinitiation complex, and thus activates NOX2 gene transcription. Our results demonstrate that nuclear MYL2 plays an important role in IR injury by transcriptionally upregulating NOX2 expression to enhance oxidative stress in a phosphorylation-dependent manner.

A novel pathway of NADPH oxidase/vascular peroxidase 1 in mediating oxidative injury following ischemia-reperfusion.

Vascular peroxidase 1 (VPO1) can utilize reactive oxygen species (ROS) generated from NADPH oxidase (NOX) to catalyze peroxidative reactions. This study was performed to identify a novel pathway of NOX/VPO1 in mediating the oxidative injury following myocardial ischemia reperfusion (IR). In a rat model of myocardial IR, the infarct size, serum creatine kinase (CK) activity, apoptosis, NOX activity, NOX2 and VPO1 expression were measured. In a cell (rat heart-derived H9c2 cells) model of hypoxia/reoxygenation (HR), the apoptosis, NOX activity, NOX2 and VPO1 expression, and H(2)O(2) and HOCl levels were examined. In vivo, IR caused 54.8 ± 1.7 % infarct size in myocardium accompanied by elevated activities of CK, caspase-3 and NOX, up-regulated VPO1 expression and high numbers of myocardial apoptotic cells; these effects were attenuated by pretreatment with the inhibitor of NOX. In vitro, inhibition of NOX or silencing of NOX2 or VPO1 expression significantly suppressed HR-induced cellular apoptosis concomitantly with decreased HOCl production. Inhibition of NOX or silencing of NOX2 led to a decrease in H(2)O(2) production accompanied by a decrease in VPO1 expression and HOCl production. However, silencing of VPO1 expression did not affect NOX2 expression and H(2)O(2) production. H(2)O(2)-induced VPO1 expression was partially reversed by JNK or p38 MAPK inhibitor. Our results demonstrate a novel pathway of NOX2/VPO1 in myocardium, where VPO1 coordinates with NOX2 and amplifies the role of NOX-derived ROS in oxidative injury following IR.

Inhibition of vascular peroxidase alleviates cardiac dysfunction and apoptosis induced by ischemia-reperfusion.

Myeloperoxidase (MPO) is involved in myocardial ischemia-reperfusion (IR) injury and vascular peroxidase (VPO) is a newly identified isoform of MPO. This study was conducted to explore whether VPO is involved in IR-induced cardiac dysfunction and apoptosis. In a rat Langendorff model of myocardial IR, the cardiac function parameters (left ventricular pressure and the maximum derivatives of left ventricular pressure and coronary flow), creatine kinase (CK) activity, apoptosis, VPO1 activity were measured. In a cell (rat-heart-derived H9c2 cells) model of hypoxia-reoxygenation (HR), apoptosis, VPO activity, and VPO1 mRNA expression were examined. In isolated heart, IR caused a marked decrease in cardiac function and a significant increase in apoptosis, CK, and VPO activity. These effects were attenuated by pharmacologic inhibition of VPO. In vitro, pharmacologic inhibition of VPO activity or silencing of VPO1 expression significantly suppressed HR-induced cellular apoptosis. Our results suggest that increased VPO activity contributes to IR-induced cardiac dysfunction and inhibition of VPO activity may have the potential clinical value in protecting the myocardium against IR injury.

Beneficial effects of capsiate on ethanol-induced mucosal injury in rats are related to stimulation of calcitonin gene-related Peptide release.

Capsiate is a non-pungent analogue of capsaicin from CH-19 Sweet peppers. Capsaicin is reported to trigger calcitonin gene-related peptide (CGRP) release through activation of transient receptor potential vanilloid subfamily member 1 (TRPV1) and produces beneficial effects on gastric mucosa. This study aimed to investigate whether capsiate is able to produce beneficial effects on gastric mucosa and whether the protective effects of capsipate occur through a mechanism involving the activation of TRPV1 and CGRP release. A rat model of gastric mucosal injury was established by the oral administration of acidified ethanol. Gastric tissues were collected for analysis of the gastric ulcer index, cellular apoptosis, activities of caspase-3, catalase and superoxide dismutase (SOD), and levels of CGRP, TNF-α, and malondialdehyde (MDA). Our results show that the acute administration of ethanol significantly increased the gastric ulcer index concomitantly with an increase in cellular apoptosis, caspase-3 activity, and TNF-α and MDA levels, as well as a decrease in the activities of catalase and SOD. Pretreatment with 1 mg/kg capsiate attenuated ethanol-induced gastric mucosal injury and cellular apoptosis accompanied by an increase in CGRP level, catalase, and SOD activities, and a decrease in caspase-3 activity, and TNF-α and MDA levels. The effects of capsiate were inhibited by capsazepine, an antagonist of TRPV1. These results suggest that capsiate is able to produce beneficial effects on ethanol-induced gastric mucosal injury. These effects are related to the stimulation of CGRP release through the activation of TRPV1.

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.

Higenamine attenuates cardiac fibroblast abstract and fibrosis via inhibition of TGF-ß1/Smad signaling.

RATIONALE: Higenamine (HG), is one of the main active components in many widely used Chinese herbs, and a common ingredient of health products in Europe and North America. Several groups, including our own, have previously shown the beneficial effects of HG against cardiomyocyte death during acute ischemic damage. However, the effect of HG on chronic cardiac remodeling, such as cardiac fibrosis, remains unknown. OBJECTIVE: Herein, we aim to investigate the role of HG in cardiac fibrosis in vivo as well as its cellular and molecular mechanisms. METHODS AND RESULTS: Chronic pressure overload with transverse aortic constriction (TAC) significantly increased cardiac hypertrophy, fibrosis, and cardiac dysfunction in mice, which were significantly attenuated by HG. Consistently, cardiac fibrosis induced by the chronic infusion of isoproterenol (ISO), was also significantly reduced by HG. Interestingly, our results showed that HG had no effect on adult mouse CM hypertrophy in vitro. However, HG suppressed the activation of cardiac fibroblasts (CFs) in vitro. Furthermore, TGF-ß1-induced expression of ACTA2, a marker of fibroblast activation, was significantly suppressed by HG. Concomitantly, HG inhibited TGF-ß1-induced phosphorylation of Smad2/3 in CFs. HG also reduced the expression of extracellular matrix molecules such as collagen I and collagen III. To our surprise, the inhibitory effect of HG on CFs activation was independent of the activation of the beta2 adrenergic receptor (ß2-AR) that is known to mediate the effect of HG on antagonizing CMs apoptosis. CONCLUSION: Our findings suggest that HG ameliorates pathological cardiac fibrosis and dysfunction at least partially by suppressing TGF-ß1/Smad signaling and CFs activation.

Allopurinol attenuates oxidative injury in rat hearts suffered ischemia/reperfusion via suppressing the xanthine oxidase/vascular peroxidase 1 pathway.

Allopurinol, a xanthine oxidase (XO) inhibitor, is reported to alleviate myocardial ischemia/reperfusion (I/R) injury by reducing the production of reactive oxygen species (ROS). As an XO-derived product, H2O2 can act as a substrate of vascular peroxidase 1 (VPO1) to induce the generation of hypochlorous acid (HOCl), a potent oxidant. This study aims to explore whether the XO/VPO1 pathway is involved in the anti-oxidative effects of allopurinol on the myocardial I/R injury. In a rat heart model of I/R, allopurinol alleviated I/R oxidative injury accompanied by decreased XO activity, XO-derived products (H2O2 and uric acid), and VPO1 expression (mRNA and protein). In a cardiac cell model of hypoxia/reoxygenation (H/R), allopurinol or XO siRNA reduced H/R injury concomitant with decreased XO activity, VPO1 expression as well as the XO and VPO1-derived products (H2O2, uric acid, and HOCl). Although knockdown of VPO1 could also exert a beneficial effect on H/R injury, it did not affect XO activity, XO expression, and XO-derived products. Based on these observations, we conclude that the novel pathway of XO/VPO1 is responsible for, at least partly, myocardial I/R-induced oxidative injury, and allopurinol exerted the cardioprotective effects on myocardial I/R injury via inhibiting the XO/VPO1 pathway.

The role of the DDAH-ADMA pathway in the protective effect of resveratrol analog BTM-0512 on gastric mucosal injury.

A recent study showed that resveratrol, a polyphenol found in many plant species, exerts dual effects on gastric mucosal injury. By using the model of ethanol-induced gastric mucosal injury in the present study, we explored the effect of trans-3,5,4'-trimethoxystilbene (BTM-0512), a novel analog of resveratrol, on gastric mucosal injury and the possible underlying mechanisms. Gastric mucosal injury in the rat was induced by oral administration of acidified ethanol. The gastric tissues were collected for determination of the gastric ulcer index, asymmetric dimethylarginine (ADMA) and nitric oxide (NO) contents, the activity of dimethylarginine dimethylaminohydrolase (DDAH) and superoxide anion (O2(-)) or hydroxyl radical (OH*) formation. The results showed that acute administration of ethanol significantly increased the gastric ulcer index concomitantly with the decrease in DDAH activity and NO content as well as the increase in ADMA content, effects that were reversed by pretreatment with BTM-0512 (100 mg/kg) or L-arginine (300 mg/kg). Administration of BTM-0512 did not show a significant effect on O2(-) or OH. formation. The results suggest that BTM-0512 could protect the gastric mucosa against ethanol-induced injury, which is mainly related to an increase in DDAH activity and subsequent decrease in ADMA content.

Reversal of isoprenaline-induced cardiac remodeling by rutaecarpine via stimulation of calcitonin gene-related peptide production.

Dysfunction of capsaicin-sensitive sensory nerves is involved in cardiac remodeling, and rutaecarpine has been shown to exert a beneficial effect on cardiac function through activating the sensory nerves. This study was conducted to explore the potential inhibitory effect of rutaecarpine on cardiac remodeling and the underlying mechanisms. A rat cardiac remodeling model was established by injection of isoprenaline (5 mg/kg per day, s.c.) for 10 days. Rutaecarpine (10 or 40 mg/kg, i.g.) was coadministrated with isoprenaline to evaluate the effect of rutaecarpine on cardiac remodeling. After echocardiographic analysis was performed, blood samples were collected to quantify calcitonin gene-related peptide (CGRP), dorsal root ganglia were isolated for examining CGRP mRNA expression, and the hearts were weighed and saved for evaluating the parameters related to apoptosis and hypertrophy. Isoprenaline significantly increased the ratio of left ventricle weight to body weight, the cross-sectional area of cardiomyocytes, cardiac apoptosis, and collagen deposition concomitantly with decreased CGRP production, which were reversed by rutaecarpine treatment. The beneficial effects of rutaecarpine were attenuated by pretreatment with capsaicin, which selectively depleted CGRP. These results suggest that rutaecarpine was able to reverse isoprenaline-induced cardiac remodeling through stimulating CGRP production.

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.

An update on vinpocetine: New discoveries and clinical implications.

Vinpocetine, a derivative of the alkaloid vincamine, has been clinically used in many countries for treatment of cerebrovascular disorders such as stroke and dementia for more than 30 years. Currently, vinpocetine is also available in the market as a dietary supplement to enhance cognition and memory. Due to its excellent safety profile, increasing efforts have been put into exploring the novel therapeutic effects and mechanism of actions of vinpocetine in various cell types and disease models. Recent studies have revealed a number of novel functions of vinpocetine, including anti-inflammation, antagonizing injury-induced vascular remodeling and high-fat-diet-induced atherosclerosis, as well as attenuating pathological cardiac remodeling. These novel findings may facilitate the repositioning of vinpocetine for preventing or treating relevant disorders in humans.

Fasudil ameliorates the ischemia/reperfusion oxidative injury in rat hearts through suppression of myosin regulatory light chain/NADPH oxidase 2 pathway.

Fasudil is a potent Rho-kinase (ROCK) inhibitor and can relax smooth muscle or cardiac muscle contraction through decreasing the phosphorylation level of myosin regulatory light chain (p-MLC20 or p-MLC2v), while p-MLC2v can function as a transcription factor to promote the NADPH oxidase 2 (NOX2) expression in rat hearts subjected to ischemia/reperfusion (I/R). This study aims to explore whether fasudil can protect the rat hearts against I/R oxidative injury through suppressing NOX2 expression via reduction of p-MLC2v level. The SD rat hearts were subjected to 1h-ischemia plus 3h-reperfusion, which showed myocardial injuries (myocardial fiber loss and disarray, increase of creatine kinase release and myocardial infarction/apoptosis), increase in ROCK activity and nuclear p-MLC2v level concomitant with up-regulation of NOX2 and H2O2 production; these phenomena were attenuated by fasudil in a dose-dependent manner. Next, we verified the cardioprotective effect of fasudil and the underlying mechanisms in hypoxia-reoxygenation (H/R) -treated H9c2 cells. Consistent with the results in vivo, the H/R-treated H9c2 cells showed cellular injury (increase in apoptotic ratio), elevation in ROCK activity and nuclear p-MLC2v level, accompanied by up-regulation of NOX2 and H2O2 production; these effects were blocked in the presence of fasudil in a dose-dependent way. Based on these observations, we conclude that beneficial effect of fasudil against myocardial I/R or H/R oxidative injury is related to the suppression of NOX2 expression through decrease of the p-MLC2v level. Our findings also highlight that intervention of MLC2v phosphorylation by drugs may provide a novel strategy to protect heart from I/R oxidative injury.

A novel function of nuclear nonmuscle myosin regulatory light chain in promotion of xanthine oxidase transcription after myocardial ischemia/reperfusion.

Nuclear myosin regulates gene transcription and this novel function might be modulated through phosphorylation of the myosin regulatory light chain (p-MLC20). Nonmuscle MLC20 (nmMLC20) is also present in the nuclei of cardiomyocytes and a potential nmMLC20 binding sequence has been identified in the promoter of the xanthine oxidase (XO) gene. Thus, we investigated its function in the regulation of XO transcription after myocardial ischemia/reperfusion (IR). In a rat model of myocardial IR and a cardiomyocyte model of hypoxia/reoxygenation (HR) injury, the cardiac or cell injury, myosin light chain kinase (MLCK) content, XO expression and activity, XO-derived products, and level of nuclear p-nmMLC20 were detected. Coimmunoprecipitation (co-IP), chromatin immunoprecipitation, DNA pull-down, and luciferase reporter gene assays were used to decipher the molecular mechanisms through which nmMLC20 promotes XO expression. IR or HR treatment dramatically elevated nuclear p-nmMLC20 level, accompanied by increased XO expression, activity, and products (H2O2 and uric acid), as well as the IR or HR injury; these effects were ameliorated by inhibition of MLCK or knockdown of nmMLC20. Our findings from these experiments demonstrated that nuclear p-nmMLC20 binds to the consensus sequence GTCGCC in the XO gene promoter, interacts with RNA polymerase II and transcription factor IIB to form a transcription preinitiation complex, and hence activates XO gene transcription. These results suggest that nuclear p-nmMLC20 plays an important role in IR/HR injury by transcriptionally upregulating XO gene expression to increase oxidative stress in myocardium. Our findings demonstrate nuclear nmMLC20 as a potential new therapeutic target to combat cardiac IR injury.

Alpha lipoic acid protects heart against myocardial ischemia-reperfusion injury through a mechanism involving aldehyde dehydrogenase 2 activation.

Recent studies demonstrate that alpha lipoic acid can prevent nitroglycerin tolerance by restoring aldehyde dehydrogenase 2 (ALDH2) activity and ALDH2-mediated detoxification of aldehydes is thought as an endogenous mechanism against ischemia-reperfusion injury. This study was performed to explore whether the cardioprotective effect of alpha lipoic acid was related to activation of ALDH2 and the underlying mechanisms. In a Langendorff model of ischemia-reperfusion in rats, cardiac function, activities of creatine kinase (CK) and ALDH2, contents of 4-hydroxy-2-nonenal (4-HNE) and malondialdehyde (MDA) were measured. In a cell model of hypoxia-reoxygenation, the apoptosis, ALDH activity, reactive oxygen species level, 4-HNE and MDA contents were examined. In the isolated hearts, ischemia-reperfusion treatment led to cardiac dysfunction accompanied by an increase in 4-HNE and MDA contents. Pretreatment with lipoic acid significantly up-regulated myocardial ALDH2 activity concomitantly with an improvement of cardiac dysfunction and a decrease in 4-HNE and MDA contents, these effects were blocked by the inhibitor of ALDH2. Similarly, in the cultured cardiomyocytes, hypoxia-reoxygenation treatment induced apoptosis accompanied by an increase in the production of reactive oxygen species, 4-HNE and MDA. Administration of lipoic acid significantly up-regulated cellular ALDH2 activity concomitantly with a reduction in apoptosis, production of reactive oxygen species, 4-HNE and MDA, these effects were reversed in the presence of ALDH2 or PKCε inhibitors. Our results suggest that the cardioprotective effects of lipoic acid on ischemia-reperfusion injury are through a mechanism involving ALDH2 activation. The regulatory effect of lipoic acid on ALDH2 activity is dependent on PKCε signaling pathway.

Phloroglucinol protects gastric mucosa against ethanol-induced injury through regulating myeloperoxidase and catalase activities.

It has been shown that oxidative stress plays an important role in the pathogenesis of ethanol-induced acute gastric mucosal injury, and phloroglucinol, a smooth muscle relaxant, has been reported to possess anti-oxidative properties. In this study, we explored the effect of phloroglucinol on ethanol-induced gastric mucosal injury and the possible underlying mechanisms. The rat model of gastric mucosal injury was induced by oral administration of acidified ethanol, and the gastric tissues were collected for analysis of gastric ulcer index (UI), cellular apoptosis, anti-O(2) ˙ or OH˙ formation activity, malondialdehyde (MDA) content, and the activities of myeloperoxidase (MPO), catalase and glutathione peroxidase. The results showed that acute administration of ethanol significantly increased gastric UI concomitantly with the increased cellular apoptosis, MDA contents, MPO activity as well as the decreased activities of catalase and anti-O(2) ˙ or OH˙ formation, which was reversed by pretreatment with phloroglucinol. Although ethanol treatment significantly decreased the activity of glutathione peroxidase, pretreatment with phloroglucinol did not significantly affect the activity of the same. The results suggest that phloroglucinol could protect the gastric mucosa against ethanol-induced injury, which is related to inhibiting the MPO activity and increasing the catalase activity in the gastric tissues.

Vanillyl nonanoate protects rat gastric mucosa from ethanol-induced injury through a mechanism involving calcitonin gene-related peptide.

Previous studies have demonstrated that capsaicin-sensitive sensory nerves are involved in the protection of gastric mucosa against damage by various stimuli and calcitoin gene-related peptide (CGRP) is a potential mediator in this process. This study was performed to explore the effect of vanillyl nonanoate, a capsaicin analog, on ethanol-induced gastric mucosal injury and the possible underlying mechanisms. A rat model of gastric mucosal injury was induced by oral administration of acidified ethanol and gastric tissues were collected for analysis of gastric ulcer index, cellular apoptosis, the activities of caspase-3, catalase and superoxide dismutase (SOD), levels of CGRP, TNF-α and malondialdehyde (MDA). The results showed that acute administration of ethanol significantly increased gastric ulcer index concomitantly with increased cellular apoptosis, caspase-3 activity, TNF-α and MDA levels as well as decreased activities of catalase and SOD. Pretreatment with 1mg/kg vanillyl nonanoate significantly attenuated ethanol-induced gastric mucosal injury and cellular apoptosis accompanied by increase of CGRP expression, and SOD activity and decrease of caspase-3 activity, TNF-α and MDA levels. The effects of vanillyl nonanoate were inhibited by capsazepine, an antagonist of capsaicin receptor. Our results suggested that vanillyl nonanoate was able to protect the gastric mucosa against ethanol-induced gastric mucosal injury. The underlying mechanism is related to stimulation of CGRP release and subsequent suppression of ethanol-induced inflammatory reaction, cellular apoptosis and oxidative stress.

Role of anandamide transporter in regulating calcitonin gene-related peptide production and blood pressure in hypertension.

OBJECTIVES: To explore the role of anandamide (AEA) transporter in regulating calcitonin gene-related peptide (CGRP) production and blood pressure. METHODS AND RESULTS: Plasma levels of AEA, CGRP, asymmetric dimethylarginine (ADMA) and nitric oxide in patients with essential hypertension, spontaneously hypertensive rats (SHRs) and 2 kidney 1 clip hypertensive rats and the CGRP mRNA expression in dorsal root ganglion of rats were measured. Peripheral blood lymphocytes were isolated to examine the AEA transporter activity, the role of AEA transporter in regulating CGRP mRNA expression or the effect of exogenous ADMA on AEA transporter activity. In both hypertensive patients and SHRs, the plasma level of AEA was elevated, but the AEA transporter activity was attenuated concomitantly with decreased CGRP production. Moreover, plasma ADMA level in SHRs was elevated accompanied by decreased nitric oxide level. By contrast, the plasma AEA level was elevated accompanied by increased CGRP production in 2 kidney 1 clip hypertensive rats, and there were no significant changes in plasma levels of ADMA, nitric oxide and the AEA transporter activity. In vitro, exogenous administration of AEA upregulated CGRP mRNA expression in lymphocytes, which was inhibited by AEA transporter blocker, AM404, and the AEA transporter activity was reduced by ADMA. CONCLUSION: Decreased plasma CGRP level in patients with essential hypertension or SHRs is likely due to the reduced AEA transporter activity, and the increased ADMA level may account for the reduced AEA transporter activity.