Contribution of muscarinic receptors to in vitro and in vivo effects of Ruscus extract.

The objectives of this study were to evaluate, in vitro and in vivo, the contribution of muscarinic receptors to the effects of Ruscus extract. Ruscus extract was tested in competition binding experiments at recombinant human muscarinic receptors, heterologous expressed in Chinese Hamster Ovary (CHO) cells and in cellular assays measuring Ca2+ liberation and activator protein-1 (AP-1) reporter gene activation. The impact of muscarinic blockade on prolonged treatment outcome was evaluated using the hamster cheek pouch (HCP) microcirculation examining macromolecular permeability increase induced by histamine or ischemia/reperfusion (I/R), mean arteriolar and venular diameters, functional capillary density and I/R-induced leukocyte rolling and sticking. Ruscus extract exhibited affinities for muscarinic receptor subtypes at a range of 50-100µg/ml and behaved as partial agonist at human recombinant M1 and M3 receptors for Ca2+ liberation, confirmed in an AP-1 reporter gene assay. In the HCP model, topical application of atropine completely or partially blocked Ruscus extract-induced reductions of histamine- and I/R-induced increases of macromolecular permeability and leukocyte-endothelium interaction. Our results showed that Ruscus extract in vitro binds and activates different subtypes of muscarinic receptors and in vivo its anti-inflammatory effects are, at least partially, mediated via muscarinic receptors.

A Slow- Compared with a Fast-Release Form of Oral Arginine Increases Its Utilization for Nitric Oxide Synthesis in Overweight Adults with Cardiometabolic Risk Factors in a Randomized Controlled Study.

BACKGROUND: Oral l-arginine supplements can have a beneficial effect on nitric oxide (NO)-related functions when subjects have cardiovascular disease risk factors. OBJECTIVE: The study was designed to determine the utilization for NO synthesis of oral l-arginine as a function of the cardiometabolic risk and the speed of absorption by comparing immediate-release arginine (IR-Arg), as in supplements, and sustained-release arginine (SR-Arg), which mimics the slow release of dietary arginine. METHODS: In a randomized, single-blind, 2-period crossover, controlled trial (1 wk of treatment, >2 wk of washout), using [(15)N-(15)N-(guanidino)]-arginine for the first morning dose, we compared the bioavailability (secondary outcome) and utilization for NO synthesis (primary outcome) of 1.5 g IR- and SR-Arg 3 times/d in 12 healthy overweight [body mass index (BMI; in kg/m(2)): 25-30] adults with the hypertriglyceridemic waist phenotype [HTW; plasma triglycerides (TGs): >150 mg/dL; waist circumference: >94 cm (men) or >80 cm (women)] and 15 healthy control adults (CON; BMI: 18.5-25; no elevated TGs and waist circumference). RESULTS: Plasma oral arginine areas under the curve were lower after supplementation with SR-Arg than with IR-Arg (112 ± 52.3 and 142 ± 50.8 µmol ⋅ h/L; P < 0.01). The utilization of oral arginine for NO synthesis was 58% higher in HTW subjects than in CON subjects and higher with SR-Arg than with IR-Arg (P < 0.05 both), particularly in HTW subjects (group-by-treatment interaction, P < 0.05). In HTW subjects administered the SR form, utilization for NO synthesis was 32% higher than with the IR form and 87% higher than in CON subjects who were administered the SR form. CONCLUSION: In overweight adults with the HTW phenotype, a slow- compared with a fast-release form of oral arginine markedly favors the utilization of arginine for NO synthesis. The utilization of low-dose, slow-release arginine for NO synthesis is higher in overweight adults with the HTW phenotype than in healthy controls, suggesting that the sensitivity of NO synthesis to the dietary arginine supply increases with cardiometabolic risk. The trial was registered at clinicaltrials.gov as NCT02352740.

l-Arginine Supplementation Alleviates Postprandial Endothelial Dysfunction When Baseline Fasting Plasma Arginine Concentration Is Low: A Randomized Controlled Trial in Healthy Overweight Adults with Cardiometabolic Risk Factors.

BACKGROUND: Vascular endothelial dysfunction, the hallmark of early atherosclerosis, is induced transiently by a high-fat meal. High doses of free l-arginine supplements reduce fasting endothelial dysfunction. OBJECTIVE: We sought to determine the effects of a low dose of a sustained-release (SR) l-arginine supplement on postprandial endothelial function in healthy overweight adults with cardiometabolic risk factors and to investigate whether this effect may vary by baseline arginine status. METHODS: In a randomized, double-blind, 2-period crossover, placebo-controlled trial (4-wk treatment, 4-wk washout), we compared the effects of 1.5 g SR-l-arginine 3 times/d (4.5 g/d) with placebo in 33 healthy overweight adults [body mass index (BMI, in kg/m(2)): 25 to >30] with the hypertriglyceridemic waist (HTW) phenotype [plasma triglycerides > 150 mg/dL; waist circumference > 94 cm (men) or > 80 cm (women)]. The main outcome variable tested was postprandial endothelial function after a high-fat meal (900 kcal), as evaluated by use of flow-mediated dilation (FMD) and Framingham reactive hyperemia index (fRHI), after each treatment. By use of subgroup analysis, we determined whether the effect was related to the baseline plasma arginine concentration. RESULTS: In the total population, the effects of SR-arginine supplementation on postprandial endothelial function were mixed and largely varied with baseline fasting arginine concentration (P-interaction < 0.05). In the lower half of the population (below the median of 78.2 µmol arginine/L plasma), but not the upper half, SR-arginine supplementation attenuated the postprandial decrease in both FMD (29% decrease with SR-arginine compared with 50% decrease with placebo) and fRHI (5% increase with SR-arginine compared with 49% decrease with placebo), resulting in significantly higher mean ± SEM values with SR-arginine (FMD: 4.0% ± 0.40%; fRHI: 0.41 ± 0.069) than placebo (FMD: 2.9% ± 0.31%; fRHI: 0.21 ± 0.060) at the end of the postprandial period (P < 0.05). CONCLUSIONS: Supplementation with low-dose SR-arginine alleviates postprandial endothelial dysfunction in healthy HTW adults when the baseline plasma arginine concentration is relatively low. The benefits of arginine supplementation may be linked to a lower ability to mobilize endogenous arginine for nitric oxide synthesis during a postprandial challenge. This trial was registered at clinicaltrials.gov as NCT02354794.

F 16915 prevents heart failure-induced atrial fibrillation: a promising new drug as upstream therapy.

Atrial fibrillation (AF) is a common complication of heart failure. The aim of the present study was to investigate the effects of a new pure docosahexaenoic acid derivative called F 16915 in experimental models of heart failure-induced atria dysfunction. The atrial dysfunction-induced AF was investigated (1) in a dog model of tachypacing-induced congestive heart failure and (2) in a rat model of heart failure induced by occlusion of left descending coronary artery and 2 months reperfusion. F 16915 (5 g/day for 4 weeks) significantly reduced the mean duration of AF induced by burst pacing in the dog model (989 ± 111 s in the vehicle group to 79 ± 59 s with F 16915, P < 0.01). This dose of F 16915 also significantly reduced the incidence of sustained AF (5/5 dogs in the vehicle group versus 1/5 with F 16915, P < 0.05). In the rat model, the percentage of shortening fraction in the F 16915 group (100 mg/kg p.o. daily) was significantly restored after 2 months (32.6 ± 7.4 %, n = 9 vs 17.6 ± 3.4 %, n = 9 in the vehicle group, P < 0.01). F 16915 also reduced the de-phosphorylation of connexin43 from atria tissue. The present results show that treatment with F 16915 reduced the heart dilation, resynchronized the gap junction activity, and reduced the AF duration in models of heart failure. Thus, F 16915 constitutes a promising new drug as upstream therapy for the treatment of AF in patients with heart failure.

Hexanic lipidosterolic extract of Serenoa repens inhibits the expression of two key inflammatory mediators, MCP-1/CCL2 and VCAM-1, in vitro.

UNLABELLED: What's known on the subject? and What does the study add? Pervasive inflammatory infiltrates, mainly composed of chronically activated T cells and monocytes/macrophages, have been observed in benign prostatic hyperplasia (BPH). Permixon®, a hexanic lipidosterolic extract of Serenoa repens (hexanic LSESr) used to treat urinary dysfunction in BPH patients, has anti-inflammatory activities. This paper provides new insights into the anti-inflammatory properties of Permixon®. We report that hexanic LSESr inhibits early steps of leukocyte infiltration in vitro by downregulating MCP-1/CCL2 and VCAM-1 expression. OBJECTIVE: To investigate the mechanisms by which hexanic lipidosterolic extract of Serenoa repens (hexanic LSESr) may prevent leukocyte infiltration in benign prostatic hyperplasia by studying its impact on monocyte chemoattractant protein 1/chemokine (C-C motif) ligand 2 (MCP-1/CCL2) and vascular cell adhesion molecule 1 (VCAM-1) expression in vitro. MATERIALS AND METHODS: After pretreatment with hexanic LSESr, human prostate (epithelial and myofibroblastic) cells and vascular endothelial cells were stimulated with proinflammatory cytokines. MCP-1/CCL2 and VCAM-1 mRNA expression was quantified by real-time PCR. ELISA kits were used to determine MCP-1/CCL2 levels in culture supernatants and VCAM-1 expression in living cells. RESULTS: Hexanic LSESr reduced MCP-1/CCL2 mRNA levels in both epithelial (BPH-1) and myofibroblastic (WPMY-1) prostate cell lines. Hexanic LSESr downregulated MCP1/CCL2 secretion by WPMY-1 cells in a concentration-dependent manner, more efficiently than Serenoa repens extracts obtained by supercritical carbon dioxide extraction. Hexanic LSESr inhibited tumour-necrosis-factor-α-induced MCP-1/CCL2 secretion by the human vascular endothelial cell line EAhy.926, as well as surface VCAM-1 protein expression, in a concentration-dependent manner. CONCLUSIONS: Hexanic LSESr impedes key steps of monocyte and T cell attraction and adherence by inhibiting MCP-1/CCL2 and VCAM-1 expression by human prostate and vascular cells in an inflammatory environment. These findings provide new insights into the anti-inflammatory effects of the hexanic lipidosterolic extract of Serenoa repens, Permixon®, in benign prostatic hyperplasia.