Role of Argininosuccinate Synthase 1 -Dependent L-Arginine Biosynthesis in the Protective Effect of Endothelial Sirtuin 3 Against Atherosclerosis.

Atherosclerosis is initiated with endothelial cell (EC) dysfunction and vascular inflammation under hyperlipidemia. Sirtuin 3 (SIRT3) is a mitochondrial deacetylase. However, the specific role of endothelial SIRT3 during atherosclerosis remains poorly understood. The present study aims to study the role and mechanism of SIRT3 in EC function during atherosclerosis. Wild-type Sirt3f/f mice and endothelium-selective SIRT3 knockout Sirt3f/f; Cdh5Cre/+ (Sirt3EC-KO) mice are injected with adeno-associated virus (AAV) to overexpress PCSK9 and fed with high-cholesterol diet (HCD) for 12 weeks to induce atherosclerosis. Sirt3EC-KO mice exhibit increased atherosclerotic plaque formation, along with elevated macrophage infiltration, vascular inflammation, and reduced circulating L-arginine levels. In human ECs, SIRT3 inhibition resulted in heightened vascular inflammation, reduced nitric oxide (NO) production, increased reactive oxygen species (ROS), and diminished L-arginine levels. Silencing of SIRT3 results in hyperacetylation and deactivation of Argininosuccinate Synthase 1 (ASS1), a rate-limiting enzyme involved in L-arginine biosynthesis, and this effect is abolished in mutant ASS1. Furthermore, L-arginine supplementation attenuates enhanced plaque formation and vascular inflammation in Sirt3EC-KO mice. This study provides compelling evidence supporting the protective role of endothelial SIRT3 in atherosclerosis and also suggests a critical role of SIRT3-induced deacetylation of ASS1 by ECs for arginine synthesis.

Branched-chain amino acid supplementation impairs insulin sensitivity and promotes lipogenesis during exercise in diet-induced obese mice.

OBJECTIVE: Branched-chain amino acids (BCAAs) are popular dietary supplements for exercise. However, increased BCAA levels positively correlate with obesity and diabetes. The metabolic impact of BCAA supplementation on insulin sensitivity during exercise is less understood. METHODS: Male C57BL/6 mice were fed for 12 weeks with a high-fat diet, normal chow diet, or BCAA-restricted high-fat diet. They were subjected to running exercise with or without BCAA treatment for another 12 weeks. RESULTS: Exercise reduced body weight, improved insulin sensitivity, lowered BCAAs in plasma, and inhibited the upregulation of BCAAs and metabolites caused by BCAA supplementation in the subcutaneous white adipose tissue (sWAT) of obese mice. BCAA supplementation reversed insulin sensitivity ameliorated by exercise. The phosphorylation of protein kinase B (Ser473 and Ser474) was decreased by BCAAs in the sWAT of obese mice. However, BCAA supplementation had no such effects in lean mice. BCAAs also increased the expression of fatty acid synthase and other lipogenesis genes in the sWAT of exercised obese mice. BCAA restriction had no effect on body weight and insulin sensitivity in obese mice. CONCLUSIONS: BCAA supplementation impaired the beneficial effect of exercise on glycolipid metabolism in obese but not lean mice. Caution should be taken regarding the use of BCAAs for individuals with obesity who exercise.

The Effect of Salvianolic Acid on Vascular Protection and Possible Mechanisms.

Salvia miltiorrhiza (Danshen), as an important traditional Chinese medicinal plant, has been used in China for the treatment of cardiovascular diseases for hundreds of years. Salvianolic acids (salvianolic acid A and salvianolic acid B) as the most abundant water-soluble component extracted from Salvia miltiorrhiza have attracted more and more attention from cardiovascular scientists due to its comprehensive cardiovascular actions. In vivo and in vitro studies have rendered salvianolic acid an excellent drug candidate for the treatment and prevention of cardiovascular diseases. In this review, we surveyed the protective effects of salvianolic acid A and salvianolic acid B against cardiovascular diseases and the pharmacological basis, providing a strong scientific rationale for elucidating the important role of Salvia miltiorrhiza in cardiovascular therapy. More importantly, we also hope to provide new inspiration and perspectives on the development and innovation of small-molecule cardiovascular drugs based on salvianolic acid.

A polysaccharide extract from the medicinal plant Maidong inhibits the IKK-NF-κB pathway and IL-1ß-induced islet inflammation and increases insulin secretion.

The herb dwarf lilyturf tuber (Maidong, Ophiopogonis Radix) is widely used in Chinese traditional medicine to manage diabetes and its complications. However, the role of Maidong polysaccharide extract (MPE) in pancreatic ß-cell function is unclear. Here, we investigated whether MPE protects ß-cell function and studied the underlying mechanisms. We treated db/db and high-fat diet (HFD)-induced obese mice with 800 or 400 mg/kg MPE or water for 4 weeks, followed by an oral glucose tolerance test. Pancreas and blood were collected for molecular analyses, and clonal MIN6 ß-cells and primary islets from HFD-induced obese mice and normal chow diet-fed mice were used in additional analyses. In vivo, MPE both increased insulin secretion and reduced blood glucose in the db/db mice but increased only insulin secretion in the HFD-induced obese mice. MPE substantially increased the ß-cell area in both models (3-fold and 2-fold, p < 0.01, for db/db and HFD mice, respectively). We observed reduced nuclear translocation of the p65 subunit of NF-κB in islets of MPE-treated db/db mice, coinciding with enhanced glucose-stimulated insulin secretion (GSIS). In vitro, MPE potentiated GSIS and decreased interleukin 1ß (IL-1ß) secretion in MIN6 ß-cells. Incubation of MIN6 cells with tumor necrosis factor α (TNFα), interferon-γ, and IL-1ß amplified IL-1ß secretion and inhibited GSIS. These effects were partially reversed with MPE or the IκB kinase ß inhibitor PS1145, coinciding with reduced activation of p65 and p-IκB in the NF-κB pathway. We conclude that MPE may have potential for therapeutic development for ß-cell protection.

Pharmacological basis and new insights of resveratrol action in the cardiovascular system.

Resveratrol (trans-3,4',5-trihydroxystilbene) belongs to the family of natural phytoalexins. Resveratrol first came to our attention in 1992, following reports of the cardioprotective effects of red wine. Thereafter, resveratrol was shown to exert antioxidant, anti-inflammatory, anti-proliferative, and angio-regulatory effects against atherosclerosis, ischaemia, and cardiomyopathy. This article critically reviews the current findings on the molecular basis of resveratrol-mediated cardiovascular benefits, summarizing the broad effects of resveratrol on longevity regulation, energy metabolism, stress resistance, exercise mimetics, circadian clock, and microbiota composition. In addition, this article also provides an update, both preclinically and clinically, on resveratrol-induced cardiovascular protection and discusses the adverse and inconsistent effects of resveratrol reported in both preclinical and clinical studies. Although resveratrol has been claimed as a master anti-aging agent against several age-associated diseases, further detailed mechanistic investigation is still required to thoroughly unravel the therapeutic value of resveratrol against cardiovascular diseases at different stages of disease development. LINKED ARTICLES: This article is part of a themed section on The Pharmacology of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.6/issuetoc.

Vitamin D Supplementation Prevents Placental Ischemia Induced Endothelial Dysfunction by Downregulating Placental Soluble FMS-Like Tyrosine Kinase-1.

Maternal vitamin D deficiency in pregnancy has been associated with an increased risk of preeclampsia. Vascular endothelial dysfunction is a major phenotype of pregnancies with preeclampsia, contributing to increased maternal hypertension and proteinuria. We sought to determine whether vitamin D supplementation would alleviate preeclampsia associated endothelial dysfunction and explore the underlying mechanism using the reduced uterine perfusion pressure (RUPP) rat model. RUPP operated rats were supplemented with 1,25(OH)2D (RUPP+VD) on day 1, 7, and 14 of pregnancy by subcutaneous injection. On day 19 of pregnancy, after the measurement of blood pressure and urine collection, maternal blood serum and placenta samples were collected. 1,25(OH)2D treatment significantly improved endothelial dysfunction by reducing apoptosis and increasing nitric oxide (NO) production in blood vessels of RUPP operated rats compared to untreated RUPP rats. 1,25(OH)2D significantly down-regulated the expression of placental soluble FMS-like tyrosine kinase-1 (sFlt-1) in RUPP rats. Furthermore, the circulating sFlt-1 levels in maternal serum were positively correlated with the expression of placental sFlt-1 and were restored to a normal pregnant level by 1,25(OH)2D treatment in RUPP rats. Incubation of endothelial cell line with rat serum from RUPP+VD group significantly increased NO production and decreased caspase-3 activity compared with serum from untreated RUPP rats. Moreover, neutralization of sFlt-1 using the specific antibody mimicked the effect of 1,25(OH)2D, which abolished the deleterious effect of RUPP rat's serum on NO production and apoptosis. These results suggest that vitamin D supplementation is protective against RUPP induced endothelial dysfunction by downregulating placental sFlt-1, which can possibly alleviate preeclampsia associated symptoms.

Chronic black tea extract consumption improves endothelial function in ovariectomized rats.

PURPOSE: Menopause escalates the risk of cardiovascular diseases in women. There is an unmet need for better treatment strategy for estrogen-deficiency-related cardiovascular complications. Here we investigated the impact of chronic black tea extract (BT) consumption on cardiovascular function and lipid metabolism using a rat model of estrogen deficiency. METHODS: Female Sprague-Dawley rats were ovariectomized (OVX) and treated with BT (15 mg/kg/day, 4 weeks; active ingredients: theaflavins) or estrogen (E2) treatment for 4 weeks. Serum was collected for measuring cholesterol, triacylglycerol and estradiol levels. Changes in vascular reactivity were examined. The protein levels of NADPH oxidases were assessed by Western blotting. Reactive oxygen species (ROS) level was measured using dihydroethidium fluorescence imaging. The concentrations of cGMP were measured using ELISA kit. RESULTS: Aortic rings from control, BT-treated and E2-treated OVX rats exhibited a greater increase in Phe-induced contraction after inhibition of NO synthase compared with those from OVX rats. ACh-induced endothelium-dependent relaxations were augmented in aortae and renal arteries in BT/E2-treated OVX rats than in OVX rats. BT/E2 treatment improved flow-mediated dilatation in small mesenteric resistance arteries of OVX rats. BT/E2 treatment restored the eNOS phosphorylation level and reversed the up-regulation of NADPH oxidases and ROS overproduction in OVX rat aortae. ACh-stimulated cGMP production was significantly elevated in the aortae from BT- and E2-treated rats compared with those from OVX rats. BT/E2 treatment reduced circulating levels of total cholesterol. CONCLUSIONS: The present study reveals the novel benefits of chronic BT consumption to reverse endothelial dysfunction and favorably modifying cholesterol profile in a rat model of estrogen deficiency and provides insights into developing BT as beneficial dietary supplements for postmenopausal women.

Chronic cranberry juice consumption restores cholesterol profiles and improves endothelial function in ovariectomized rats.

PURPOSE: Postmenopausal women experience higher risks for cardiovascular diseases than age-matched men and pre-menopausal women. There is a need for better treatment strategy for estrogen-deficient-related cardiovascular complications. We and others have recently reported that activated renin-angiotensin system and the associated oxidative stress impaired endothelium-dependent relaxation in ovariectomized rat, while angiotensin receptor blocker rescues endothelial dysfunction. Dietary supplements and lifestyle modifications provide an alternative way to improve cardiovascular health. The present study tests the hypothesis that chronic cranberry juice consumption improves cholesterol profiles and vascular functions in estrogen-deficient animal model. The effect of cranberry consumption on expression and activity of renin-angiotensin system in the vasculature will be determined. METHODS: Ovariectomized rats were treated daily with commercial cranberry juice at 7 mg/kg for 8 weeks, a dosage comparable to recent clinical studies. Serum was collected for measuring cholesterol levels while aorta was isolated for isometric force assay and expression studies. RESULTS: Cranberry juice consumption reduced circulating levels of total cholesterol, triacylglycerols, HDL, nHDL, and nHDL/HDL ratio. Meanwhile, cranberry juice consumption improved endothelium-dependent relaxation in aorta of ovariectomized rats by restoring p-eNOS level (endothelial nitric oxide synthase phosphorylated at ser-1177), reversing the up-regulated levels of renin-angiotensin system markers (angiotensin-converting enzyme, angiotensin II, and angiotensin II type 1 receptor), and normalizing the elevated NAD(P)H oxidase expression and oxidative stress. CONCLUSIONS: Our data demonstrate the novel cardiovascular benefits of cranberry juice consumption in improving both vascular functions and cholesterol profiles, providing insight into developing cranberry products into useful dietary supplements for postmenopausal women.

Capsaicinoids lower plasma cholesterol and improve endothelial function in hamsters.

PURPOSE: Capsaicinoids are the active compounds in chili pepper. The present study investigated the effect of capsaicinoids on plasma lipids, functionality of aorta including atherosclerotic plaque development, cholesterol absorption biomarker, fecal sterol excretion, and gene expression of major receptors, enzymes, and transporters involved in cholesterol metabolism. METHODS: Hamsters were divided into five groups and fed a high-cholesterol diet containing 0 % (CON), 0.010 % (LD), 0.015 % (MD), 0.020 % (HD), and 0.030 % (VD) capsaicinoids, respectively, for 6 weeks. Plasma lipids were measured using the enzymatic kits, and the gene expression of transporters, enzymes, and receptors involved in cholesterol absorption and metabolism was quantified using the quantitative PCR. Endothelial function was assessed by measuring the acetylcholine-induced endothelium-dependent relaxations in aorta. RESULTS: Capsaicinoids reduced plasma total cholesterol, non-high-density lipoprotein cholesterol, and triacylglycerols with high-density lipoprotein cholesterol being unaffected. All four experimental groups had a decrease in the atherosclerotic plaque compared with CON. Dietary capsaicinoids increased the fecal excretion of total acidic sterols possibly mediated by up-regulation of cholesterol 7α-hydroxylase and down-regulation of liver X receptor alpha. Plasma sterol analysis demonstrated that capsaicinoids decreased the ratio of plasma campesterol/cholesterol, suggesting they decreased cholesterol absorption. Capsaicinoids could improve the endothelium-dependent relaxations and reduce the endothelium-dependent contractions by inhibiting the gene expression of COX-2. However, no dose-dependent effect of capsaicinoids on these parameters was seen. CONCLUSION: Capsaicinoids were beneficial in improving lipoprotein profile and aortic function in hamsters fed a high-cholesterol diet.

Fo Shou San, an ancient Chinese herbal decoction, protects endothelial function through increasing endothelial nitric oxide synthase activity.

Fo Shou San (FSS) is an ancient herbal decoction comprised of Chuanxiong Rhizoma (CR; Chuanxiong) and Angelicae Sinensis Radix (ASR; Danggui) in a ratio of 2:3. Previous studies indicate that FSS promotes blood circulation and dissipates blood stasis, thus which is being used widely to treat vascular diseases. Here, we aim to determine the cellular mechanism for the vascular benefit of FSS. The treatment of FSS reversed homocysteine-induced impairment of acetylcholine (ACh)-evoked endothelium-dependent relaxation in aortic rings, isolated from rats. Like radical oxygen species (ROS) scavenger tempol, FSS attenuated homocysteine-stimulated ROS generation in cultured human umbilical vein endothelial cells (HUVECs), and it also stimulated the production of nitric oxide (NO) as measured by fluorescence dye and biochemical assay. In addition, the phosphorylation levels of both Akt kinase and endothelial NO synthases (eNOS) were markedly increased by FSS treatment, which was abolished by an Akt inhibitor triciribine. Likewise, triciribine reversed FSS-induced NO production in HUVECs. Finally, FSS elevated intracellular Ca(2+) levels in HUVECs, and the Ca(2+) chelator BAPTA-AM inhibited the FSS-stimulated eNOS phosphorylation. The present results show that this ancient herbal decoction benefits endothelial function through increased activity of Akt kinase and eNOS; this effect is causally via a rise of intracellular Ca(2+) and a reduction of ROS.

Electro-acupuncture attenuates stress-induced defecation in rats with chronic visceral hypersensitivity via serotonergic pathway.

Acupuncture has long been used for patients with irritable bowel syndrome. However, it has remained unclear. The aim of this study was to testify the effect of electro-acupuncture(EA) on (1) visceral hypersensitivity induced by the mechanical colorectal irritation during postnatal development of rats, and (2) stress-induced colonic motility changes on rats with chronic visceral hypersensitivity. The abdominal withdrawal reflex (pain threshold and score) for visceral hypersensitivity and fecal pellet output for motor dysfunction were selected as two indexes for measurement. In addition, the effect of EA on 5-HT(4a) receptor and serotonin transporter (SERT) expression in the colon mucosa was analyzed semi-quantitatively through immunohistochemistry and 5-HT concentration in the colon tissue was observed through spectro-photo-fluorimeter detection, respectively. Our results showed that EA significantly elevated pain threshold, decreased the scores and also decreased fecal pellet output during water avoid stress. Furthermore, EA decreased 5-HT concentration in colon in rats with CVH and CVH rats with water avoidance stress, and increased the 5-HT(4a) and SERT expression in rats with CVH. Thus, it can be concluded that EA attenuates behavioral hyperalgesia and stress-induced colonic motor dysfunction in CVH rats via serotonergic pathway.