TRPV1 activation prevents high-salt diet-induced nocturnal hypertension in mice

Dietary salt, vascular dysfunction, and cognitive impairment

Excessive salt consumption is a major health problem worldwide leading to serious cardiovascular events including hypertension, heart disease, and stroke. Additionally, high-salt diet has been increasingly associated with cognitive impairment in animal models and late-life dementia in humans. High-salt consumption is harmful for the cerebral vasculature, disrupts blood supply to the brain, and could contribute to Alzheimer's disease pathology. Although animal models have advanced our understanding of the cellular and molecular mechanisms, additional studies are needed to further elucidate the effects of salt on brain function. Furthermore, the association between excessive salt intake and cognitive impairment will have to be more thoroughly investigated in humans. Since the harmful effects of salt on the brain are independent by its effect on blood pressure, in this review, I will specifically discuss the evidence, available in experimental models and humans, on the effects of salt on vascular and cognitive function in the absence of changes in blood pressure. Given the strong effects of salt on the function of immune cells, I will also discuss the evidence linking salt consumption to gut immunity dysregulation with particular attention to the ability of salt to disrupt T helper 17 (Th17) cell homeostasis. Lastly, I will briefly discuss the data implicating IL-17A, the major cytokine produced by Th17 cells, in vascular dysfunction and cognitive impairment.

A comprehensive review of plant-derived salt substitutes: Classification, mechanism, and application

The diseases caused by excessive sodium intake derived from NaCl consumption have attracted widespread attention worldwide, and many researchers are committed to finding suitable ways to reduce sodium intake during the dietary process. Salt substitute is considered an effective way to reduce sodium intake by replacing all/part of NaCl in food without reducing the saltiness while minimizing the impact on the taste and acceptability of the food. Plant-derived natural ingredients are generally considered safe and reliable, and extensive research has shown that certain plant extracts or specific components are effective salt substitutes, which can also give food additional health benefits. However, these plant-derived salt substitutes (PSS) have not been systematically recognized by the public and have not been well adopted in the food industry. Therefore, a comprehensive review of PSS, including its material basis, flavor characteristics, and taste mechanism is helpful for a deeper understanding of PSS, accelerating its research and development, and promoting its application.

Citropten Inhibits Vascular Smooth Muscle Cell Proliferation and Migration via the TRPV1 Receptor

Vascular smooth muscle cell (VSMC) proliferation and migration play critical roles in arterial remodeling. Citropten, a natural organic compound belonging to coumarin and its derivative classes, exhibits various biological activities. However, mechanisms by which citropten protects against vascular remodeling remain unknown. Therefore, in this study, we investigated the inhibitory effects of citropten on VSMC proliferation and migration under high-glucose (HG) stimulation. Citropten abolished the proliferation and migration of rat vascular smooth muscle cells (RVSMCs) in a concentration-dependent manner. Also, citropten inhibited the expression of proliferation-related proteins, including proliferating cell nuclear antigen (PCNA), cyclin E1, cyclin D1, and migration-related markers such as matrix metalloproteinase (MMP), MMP2 and MMP9, in a concentration-dependent manner. In addition, citropten inhibited the phosphorylation of ERK and AKT, as well as hypoxia-inducible factor-1α (HIF-1α) expression, mediated to the Krüppel-like factor 4 (KLF4) transcription factor. Using pharmacological inhibitors of ERK, AKT, and HIF-1α also strongly blocked the expression of MMP9, PCNA, and cyclin D1, as well as migration and the proliferation rate. Finally, molecular docking suggested that citropten docked onto the binding site of transient receptor potential vanilloid 1 (TRPV1), like epigallocatechin gallate (EGCG), a well-known agonist of TRPV1. These data suggest that citropten inhibits VSMC proliferation and migration by activating the TRPV1 channel.

Hypertension: Causes and Consequences of Circadian Rhythms in Blood Pressure

Hypertension is extremely common, affecting approximately 1 in every 2 adults globally. Chronic hypertension is the leading modifiable risk factor for cardiovascular disease and premature mortality worldwide. Despite considerable efforts to define mechanisms that underlie hypertension, a potentially major component of the disease, the role of circadian biology has been relatively overlooked in both preclinical models and humans. Although the presence of daily and circadian patterns has been observed from the level of the genome to the whole organism, the functional and structural impact of biological rhythms, including mechanisms such as circadian misalignment, remains relatively poorly defined. Here, we review the impact of daily rhythms and circadian systems in regulating blood pressure and the onset, progression, and consequences of hypertension. There is an emphasis on the impact of circadian biology in relation to vascular disease and end-organ effects that, individually or in combination, contribute to complex phenotypes such as cognitive decline and the loss of cardiac and brain health. Despite effective treatment options for some individuals, control of blood pressure remains inadequate in a substantial portion of the hypertensive population. Greater insight into circadian biology may form a foundation for novel and more widely effective molecular therapies or interventions to help in the prevention, treatment, and management of hypertension and its related pathophysiology.

Research trends and hotpots on the relationship between high salt and hypertension: A bibliometric and visualized analysis

INTRODUCTION

A high salt diet is a significant risk factor for hypertension, and scholarly investigations into this relationship have garnered considerable attention worldwide. However, bibliometric analyses in this field remain underdeveloped. This study aimed to conduct a bibliometric and visual analysis of research progress on the link between high salt and hypertension from 2011 to 2022 with the goal of identifying future research trends and providing valuable insights for this field.

METHODS

High salt and hypertension data were obtained from the Web of Science Core Collection database. Microsoft Excel, Scimago Graphica, CiteSpace, and VOSviewer software were employed to analyze publication output trends, the most productive countries or regions, journals, authors, co-cited references, and keywords.

RESULTS

After screening, 1470 papers met the inclusion criteria. Relevant publications increased annually by 3.66% from 2011 to 2022. The United States led in research productivity, with The Journal of Hypertension publishing the most papers, and David L. Mattson as the most prolific author. Oxidative stress has emerged as a prominent research topic, and extensive investigations have been conducted on related mechanisms. "Oxidative stress," "gut microbiota," and "kidney injury" are recent hotspots that are expected to remain so, and this study carefully characterizes the mechanism of high salt-induced hypertension based on these hotspots.

CONCLUSION

This study utilized bibliometric and visualization analysis to identify the development trends and hotspots of publications related to high salt and hypertension. The findings of this study offer valuable insights into the forefront of emerging trends and future directions in this field.

Targeting temperature-sensitive transient receptor potential channels in hypertension: far beyond the perception of hot and cold

Transient receptor potential (TRP) channels are nonselective cation channels and participate in various physiological roles. Thus, changes in TRP channel function or expression have been linked to several disorders. Among the many TRP channel subtypes, the TRP ankyrin type 1 (TRPA1), TRP melastatin type 8 (TRPM8), and TRP vanilloid type 1 (TRPV1) channels are temperature-sensitive and recognized as thermo-TRPs, which are expressed in the primary afferent nerve. Thermal stimuli are converted into neuronal activity. Several studies have described the expression of TRPA1, TRPM8, and TRPV1 in the cardiovascular system, where these channels can modulate physiological and pathological conditions, including hypertension. This review provides a complete understanding of the functional role of the opposing thermo-receptors TRPA1/TRPM8/TRPV1 in hypertension and a more comprehensive appreciation of TRPA1/TRPM8/TRPV1-dependent mechanisms involved in hypertension. These channels varied activation and inactivation have revealed a signaling pathway that may lead to innovative future treatment options for hypertension and correlated vascular diseases.

Association between spicy food and hypertension among Han Chinese aged 30-79 years in Sichuan Basin: a population-based cross-sectional study

BACKGROUND

While spicy food is believed to have cardiovascular-protective effects, its impact on hypertension remains uncertain due to conflicting findings from previous studies. This study aimed to explore the association between spicy food and hypertension in Sichuan Basin, China.

METHODS

The baseline data of 43,657 residents aged 30-79 in the Sichuan Basin were analyzed including a questionnaire survey (e.g., sociodemographics, diet and lifestyle, medical history), medical examinations (e.g., height, body weight, and blood pressure), and clinical laboratory tests (e.g., blood and urine specimens). Participants were recruited by multi-stage, stratified cluster sampling in consideration of both sex ratio and age ratio between June 2018 and February 2019. Multivariable logistic regression was performed to explore the effect of spicy food on hypertension and multivariable linear regression was applied to estimate the effect of spicy food on systolic and diastolic blood pressure (SBP/DBP).

RESULTS

Concerning hypertension, negative associations with spicy food consumption were observed only in females: compared to those who do not eat spicy food, the odds ratios of consuming spicy food 6-7 days/week, consuming spicy food with strong strength, and years of eating spicy food-to-age ratio were 0.886 (0.799, 0.982), 0.757 (0.587, 0.977), 0.632 (0.505, 0.792), respectively. No significant association was found in males (All P trends > 0.05). In the stratified analyses, participants in the subgroup who were 50 to 79 years old (OR, 95%CI: 0.814, 0.763, 0.869), habitually snored (OR, 95%CI: 0.899, 0.829, 0.976), had a BMI < 24 kg/m2 (OR, 95%CI: 0.886, 0.810, 0.969), had a normal waist circumference (OR, 95%CI: 0.898, 0.810, 0.997), and had no dyslipidemia (OR, 95%CI: 0.897, 0.835, 0.964) showed a significantly stronger association. For SBP, consuming spicy food had negative effects in both genders, but the effect was smaller in males compared to females: among males, the β coefficients for consuming spicy food 1-2 days/week, weak strength, and years of eating spicy food-to-age ratio were 0.931 (-1.832, -0.030), -0.639 (-1.247, -0.032), and - 2.952 (-4.413, -1.492), respectively; among females, the β coefficients for consuming spicy food 3-5 days/week, 6-7 days/week, weak strength, moderate strength, and years of eating spicy food-to-age ratio were - 1.251 (-2.115, -0.388), -1.215 (-1.897, -0.534), -0.788 (-1.313, -0.263), -1.807 (-2.542, -1.072), and - 5.853 (-7.195, -4.512), respectively. For DBP, only a positive association between the years of eating spicy food-to-age ratio and DBP was found in males with β coefficient (95%CI ) of 1.300 (0.338, 2.263); Little association was found in females (all P trends > 0.05), except for a decrease of 0.591 mmHg ( 95%CI: -1.078, -0.105) in DBP among participants who consumed spicy food 1-2 days/week, compared to those who did not consume spicy food.

CONCLUSION

Spicy food may lower SBP and has an antihypertensive effect, particularly beneficial for women and individuals with fewer risk factors in the Sichuan Basin. Spicy food consumption may decrease DBP in women but increase it in men. Further multicenter prospective cohort studies are needed to confirm these findings.

Capsaicin improves hypertension and cardiac hypertrophy via SIRT1/NF-κB/MAPKs pathway in the hypothalamic paraventricular nucleus

BACKGROUND

Hypertension has seriously affected a large part of the adult and elderly population. The complications caused by hypertension are important risk factors for cardiovascular disease accidents. Capsaicin, a pungent component of chili pepper has been revealed to improve hypertension. However, its potential mechanism in improving hypertension remains to be explored.

PURPOSE

In the present study, we aimed to investigate whether capsaicin could attenuate the SIRT1/NF-κB/MAPKs pathway in the paraventricular nucleus of hypothalamus (PVN).

METHODS

We used spontaneous hypertensive rats (SHRs) as animal model rats. Micro osmotic pump was used to give capsaicin through PVN for 28 days, starting from age12-week-old.

RESULTS

The results showed that capsaicin significantly reduced blood pressure from the 16th day of infusion onward. At the end of the experimental period, we measured cardiac hypertrophy index and the heart rate (HR), and the results showed that the cardiac hypertrophy and heart rate of rats was significantly improved upon capsaicin chronic infusion. Norepinephrine (NE) and epinephrine (EPI) in plasma of SHRs treated with capsaicin were also decreased. Additionally, capsaicin increased the protein expression and number of positive cells of SIRT1 and the 67-kDa isoform of glutamate decarboxylase (GAD67), decreased the production of reactive oxygen species (ROS), number of positive cells of NOX2, those of Angiotensin Converting Enzyme (ACE) and p-IKKβ, tyrosine hydroxylase (TH), the gene expression levels of NOX4 and pro-inflammatory cytokines. Capsaicin also decreased the relative protein expressions of protein in MAPKs pathway.

CONCLUSION

Current data indicated that capsaicin within the PVN improves hypertension and cardiac hypertrophy via SIRT1/NF-κB/MAPKs pathway in the PVN of SHRs, supporting its potential as candidate drug for preventing and improving hypertension.

The Vanilloid (Capsaicin) Receptor TRPV1 in Blood Pressure Regulation: A Novel Therapeutic Target in Hypertension?

Today's sedentary lifestyle with excess food and little exercise increases the number of people with hypertension, a major risk factor for stroke. New knowledge of treatments in this field is of utmost importance. In animal experiments, the activation by capsaicin of TRPV1-expressing sensory afferents evokes a drop in blood pressure by triggering the Bezold-Jarisch reflex. In hypertensive rats, capsaicin reduces blood pressure. Conversely, genetic ablation of the TRPV1 receptor results in elevated nocturnal (but not diurnal) blood pressure. These observations imply a therapeutic potential for TRPV1 activation in hypertensive patients. Indeed, in a major epidemiological study involving 9273 volunteers, dietary capsaicin was found to lower the risk for hypertension. New research indicates that the mechanism of action of capsaicin on blood pressure regulation is far more complex than previously thought. In addition to the well-recognized role of capsaicin-sensitive afferents in blood pressure regulation, TRPV1 seems to be expressed both in endothelial cells and vascular smooth muscle. This review aims to evaluate the therapeutic potential of TRPV1-targeting drugs in hypertensive patients.

New opportunities and challenges of natural products research: When target identification meets single-cell multiomics

Natural products, and especially the active ingredients found in traditional Chinese medicine (TCM), have a thousand-year-long history of clinical use and a strong theoretical basis in TCM. As such, traditional remedies provide shortcuts for the development of original new drugs in China, and increasing numbers of natural products are showing great therapeutic potential in various diseases. This paper reviews the molecular mechanisms of action of natural products from different sources used in the treatment of inflammatory diseases and cancer, introduces the methods and newly emerging technologies used to identify and validate the targets of natural active ingredients, enumerates the expansive list of TCM used to treat inflammatory diseases and cancer, and summarizes the patterns of action of emerging technologies such as single-cell multiomics, network pharmacology, and artificial intelligence in the pharmacological studies of natural products to provide insights for the development of innovative natural product-based drugs. Our hope is that we can make use of advances in target identification and single-cell multiomics to obtain a deeper understanding of actions of mechanisms of natural products that will allow innovation and revitalization of TCM and its swift industrialization and internationalization.

Beneficial effects of capsaicin and dihydrocapsaicin on endothelial inflammation, nitric oxide production and antioxidant activity

Capsaicin and dihydrocapsaicin (DHC) are major pungent capsaicinoids produced in chili peppers. Capsaicin has been previously shown to promote vascular health by increasing nitric oxide (NO) production and reducing inflammatory responses. While capsaicin has been extensively studied, whether DHC exerts cardiovascular benefits through similar mechanisms remains unclear. The current study aimed to investigate the direct effects of DHC on endothelial inflammation, NO release, and free radical scavenging properties. DHC at concentrations up to 50 µM did not affect cell viability, while concentrations of 100 and 500 µM of DHC led to endothelial cytotoxicity. Capsaicin decreased cell viability at concentration of 500 µM. To investigate the effects of capsaicinoids on endothelial activation, we first demonstrated that TNFα induced Ser536 phosphorylation of p65 NFκB, expressions of adhesion molecules, vascular cell adhesion molecule (VCAM)-1 and intercellular adhesion molecule (ICAM)-1, and IL-6 production in primary human endothelial cells. These effects were robustly abrogated by DHC. Consistently, DHC treatment led to a marked reduction in TNFα-mediated monocyte adhesion to endothelial cells. Additionally, NO production was significantly induced by DHC and capsaicin compared to vehicle control. Similar to capsaicin and vitamin C, DHC scavenged DPPH (1,1-diphenyl-2-picrylhydrazyl) free radicals in vitro. Our present study highlights the benefits of DHC and capsaicin treatment on human endothelial cells and provides evidence to support cardiovascular benefits from capsicum consumption.

Activation of TRPV1 improves natriuresis and salt sensitivity in high-fat diet fed mice

Western diet (WD) intake increases morbidity of obesity and salt-sensitive hypertension albeit mechanisms are largely unknown. We investigated the role of transient receptor potential vanilloid 1 (TRPV1) in WD intake-induced hypertension. TRPV1^-/- and wild-type (WT) mice were fed a normal (CON) or Western diet (WD) for 16-18 weeks. Mean arterial pressure (MAP) after normal sodium glucose (NSG) loading with or without L-NAME (a NO synthase inhibitor) or N-oleoyldopamine (OLDA, a TRPV1agonist) was not different between the two strains on CON.WT or TRPV1^-/- mice fed WD had increased MAP after NSG, with a greater magnitude in TRPV1^-/- mice. OLDA decreased while L-NAME increased MAP in WT-WD but not in TRPV1^-/--WD mice. The urinary nitrates plus nitrites excretion (UNOx), an indicator of renal NO production, was increased in both strains on CON after NSG. TRPV1 ablation with WD intake abolished NSG-induced increment in UNOx. OLDA further increased while L-NAME prevented NSG-induced increment in UNOx in WT-WD mice. Urinary sodium excretion was increased in both strains on CON and in WT-WD mice but not in TRPV1^-/--WD mice after NSG. OLDA further increased while L-NAME prevented NSG-induced increases in sodium excretion in WT-WD but not in TRPV1^-/--WD mice. Thus, TRPV1 ablation increases salt sensitivity during WD intake possibly via impaired renal NO production and sodium excretion. Activation of TRPV1 enhances renal NO production and sodium excretion, resulting in prevention of increased salt sensitivity during WD intake.

Analysis of the Ability of Capsaicin to Modulate the Human Gut Microbiota In Vitro

Previous studies on capsaicin, the bioactive compound in chili peppers, have shown that it may have a beneficial effect in vivo when part of a regular diet. These positive health benefits, including an anti-inflammatory potential and protective effects against obesity, are often attributed to the gut microbial community response to capsaicin. However, there is no consensus on the mechanism behind the protective effect of capsaicin. In this study, we used an in vitro model of the human gut microbiota to determine how regular consumption of capsaicin impacts the gut microbiota. Using a combination of NextGen sequencing and metabolomics, we found that regular capsaicin treatment changed the structure of the gut microbial community by increasing diversity and certain SCFA abundances, particularly butanoic acid. Through this study, we determined that the addition of capsaicin to the in vitro cultures of the human gut microbiome resulted in increased diversity of the microbial community and an increase in butanoic acid. These changes may be responsible for the health benefits associated with CAP consumption.

TRPV1 inhibits smooth muscle cell phenotype switching in a mouse model of abdominal aortic aneurysm

The natural outcome of abdominal aortic aneurysm (AAA) is that of slow progression and ultimate rupture, then a life-threatening hemorrhage consequently. Ruptured AAA is a dramatic catastrophe and constitutes one of the leading causes of acute death in elderly men. However, the mechanism of AAA is still unclear. Transient receptor potential vanilloid (TRPV) family has protective effects in cardiovascular diseases. In this study, we revealed the expression and the pathogenesis of TRPV1 in a mouse AAA model. The results presented here identify TRPV1 could be a potential therapeutic target for AAA treatment.

Interactions between Chemesthesis and Taste: Role of TRPA1 and TRPV1

In addition to the sense of taste and olfaction, chemesthesis, the sensation of irritation, pungency, cooling, warmth, or burning elicited by spices and herbs, plays a central role in food consumption. Many plant-derived molecules demonstrate their chemesthetic properties via the opening of transient receptor potential ankyrin 1 (TRPA1) and transient receptor potential vanilloid 1 (TRPV1) channels. TRPA1 and TRPV1 are structurally related thermosensitive cation channels and are often co-expressed in sensory nerve endings. TRPA1 and TRPV1 can also indirectly influence some, but not all, primary taste qualities via the release of substance P and calcitonin gene-related peptide (CGRP) from trigeminal neurons and their subsequent effects on CGRP receptor expressed in Type III taste receptor cells. Here, we will review the effect of some chemesthetic agonists of TRPA1 and TRPV1 and their influence on bitter, sour, and salt taste qualities.

TRPV5 attenuates abdominal aortic aneurysm in mice by regulating KLF4-dependent phenotype switch of aortic vascular smooth muscle cells

Abdominal aortic aneurysm (AAA) is a fatal vascular disease with insidious symptoms. However, the mechanism behind its development remains unclear. The transient receptor potential vanilloid (TRPV) family has crucial protective effects against cardiovascular diseases, but the role of TRPV5 in AAA has yet to be reported. In this study, ApoE^-/- mice were intraperitoneally injected with AAV-GFP or AAV-TRPV5. After 30 days, mice were further administered with angiotensin II (Ang II, 1.44 mg/kg/day) by using osmotic pumps to induce the AAA model or Saline for 28 days, (i.e., Saline + AAV-GFP, Saline + AAV-TRPV5, Ang II + AAV-GFP and Ang II + AAV-TRPV5 groups were established). Compared with the control group, the incidence of AAA and the maximal diameter of the abdominal aorta markedly decreased in Ang II + AAV-TRPV5, which was detected by vascular ultrasound at 28 day. Meanwhile, less collagen and elastin degradation were observed in the Ang II + AAV-TRPV5 group by using Masson and Elastin stains. Moreover, more α-SMA and less MMP2 was observed in the abdominal aortas collected at 28 day by immunohistochemistry. In vitro, primary mouse vascular smooth muscle cells (VSMCs) were treated with Ang II (1 μM) to induce phenotype switch. Sh-TRPV5 and AdTRPV5 were used to transfect VSMCs. PCR and Western blotting were used to access the expression of contractile marker, including α-SMA and SM-22α. The results showed that the mRNA and protein level of α-SMA and SM-22α were decreased under the stimulation of Ang II, but could be attenuated by TRPV5 overexpression. The cell scratch assay demonstrated that the migration ability of VSMCs was increased in Ang II treated group and could be ameliorated by TRPV5 overexpression. Above all, VSMCs transformed from the contractile into secretory phenotype under Ang II stimuli, but could be rescued by TRPV5 overexpression. Furthermore, TRPV5 overexpression suppressed the increased expression of KLF4 induced by Ang II treatment in VSMCs. The data demonstrated that TRPV5 could inhibit AAA formation and play a critical role in the VSMC phenotype switch by downregulating KLF4, suggesting TRPV5 as a new strategy for treating AAA.

New Insights Into Peptide Cannabinoids: Structure, Biosynthesis and Signaling

Classically, the endocannabinoid system (ECS) consists of endogenous lipids, of which the best known are anandamide (AEA) and 2 arachidonoylglycerol (2-AG), their enzyme machinery for synthesis and degradation and their specific receptors, cannabinoid receptor one (CB1) and cannabinoid receptor two (CB2). However, endocannabinoids also bind to other groups of receptors. Furthermore, another group of lipids are considered to be endocannabinoids, such as the fatty acid ethanolamides, the fatty acid primary amides and the monoacylglycerol related molecules. Recently, it has been shown that the hemopressin peptide family, derived from α and β chains of hemoglobins, is a new family of cannabinoids. Some studies indicate that hemopressin peptides are expressed in the central nervous system and peripheral tissues and act as ligands of these receptors, thus suggesting that they play a physiological role. In this review, we examine new evidence on lipid endocannabinoids, cannabinoid receptors and the modulation of their signaling pathways. We focus our discussion on the current knowledge of the pharmacological effects, the biosynthesis of the peptide cannabinoids and the new insights on the activation and modulation of cannabinoid receptors by these peptides. The novel peptide compounds derived from hemoglobin chains and their non-classical activation of cannabinoid receptors are only starting to be uncovered. It will be exciting to follow the ensuing discoveries, not only in reference to what is already known of the classical lipid endocannabinoids revealing more complex aspects of endocannabinoid system, but also as to its possibilities as a future therapeutic tool.

Impact of capsaicin on aroma release: in vitro and in vivo analysis

Capsaicin is the main bioactive compound in chili pepper that leads to the perception of "spiciness". However, the effect of capsaicin on aroma release in the nose remains unexplained. This is the first study designed to measure capsaicin's impact on aroma release during consumption. In vitro studies, using static headspace analysis by atmospheric pressure chemical ionization-mass spectrometry (APCI-MS), showed no impact of capsaicin (5 ppm) on the gas-liquid partitioning equilibria of a range of aroma compounds. However, a significant reduction in aroma release was observed in vivo, during oral melting of a model ice cube system (p < 0.05) included 5 ppm capsaicin. The total release of aroma into the nasal cavity was decreased, such that only 49% of 3-methylbutanal, 60% of 1-octen-3-ol and 83% of linalool was released. This is the first evidence of capsaicin's reduction effect on aroma release during consumption. It was also found that 5 ppm capsaicin increased saliva secretion by 75%, which may have led to the dilution of aroma compounds in the mouth and directly impacted the aroma release into the nasal cavity. The most hydrophilic compound (3-methylbutanal) was affected by capsaicin to a greater extent than the hydrophobic compound (linalool), the solvent effect of the additional saliva may explain this.

Dietary capsaicin-mediated attenuation of hypertension in a rat model of renovascular hypertension

Background: Capsaicin, a pungent component of chili pepper, has been reported to decrease blood pressure (BP) and to cause vasorelaxation via nitric oxide (NO) production. However, it is still unclear how dietary capsaicin effects on renovascular hypertension. To examine this, we observed the effects of dietary capsaicin on BP in 2-kidney, 1-clip renovascular hypertension (2K1C) rats, and investigated the participation of NO in the mechanism.Methods: Rats with 2K1C or sham-operated rats (SHAM) were treated with 0.006% capsaicin diet (CAP) or control diet (CTL) for 6 weeks. Systolic BP (SBP) was measured by tail-cuff method once a week. In the end, mean arterial BP (MAP) was measured in the rats under anesthesia. These observations were performed also in the rats taking a NO synthase (NOS) inhibitor (LN). After rats were euthanized, thoracic aortas were collected and used for western blot analyses to evaluate the phosphorylated ratio of endothelial NOS (eNOS), protein kinase A (PKA) and B (Akt), in order to explore a mechanism of the effects on BP by dietary capsaicin.Results: SBP and MAP in 2K1C rats were significantly higher than in SHAM rats when fed CTL, but not when fed CAP. Those in 2K1C-CAP rats were significantly lower than in 2K1C-CTL rats. LN suppressed the effect of dietary capsaicin. The ratios of phosphorylated (p-) eNOS/eNOS and p-Akt/Akt, but not p-PKA/PKA, were significantly increased in rats fed CAP compared with rats fed CTL.Conclusion: Dietary capsaicin may alleviate 2K1C renovascular hypertension, probably via enhancing phosphorylation of Akt and eNOS.Abbreviations: 2K1C: 2-kidney, 1-clip hypertension model; Akt: protein kinase B; Ang II: angiotensin II; ANOVA: measures analysis of variance; BP: blood pressure; EC: endothelial cell; eNOS: endothelial nitric oxide synthase; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; L-NAME, LN: Nω-Nitro-L-arginine methyl ester hydrochloride; MA: mesenteric arteries; MAP: mean arterial blood pressure; NO: nitric oxide; PKA: protein kinase A; PVDF: polyvinylidene difluoride; SBP: Systolic blood pressure; SHR: spontaneously hypertensive rats; SN: sympathetic nervous; TRPV1: transient receptor potential vanilloid type 1; WKY: Wistar Kyoto rats.

The Role of Transient Receptor Potential Vanilloid 1 in Common Diseases of the Digestive Tract and the Cardiovascular and Respiratory System

Transient receptor potential vanilloid subtype 1 (TRPV1), a member of the transient receptor potential vanilloid (TRPV) channel family, is a nonselective cation channel that is widely expressed in sensory nerve fibers and nonneuronal cells, including certain vascular endothelial cells and smooth muscle cells. The activation of TRPV1 may be involved in the regulation of various physiological functions, such as the release of inflammatory mediators in the body, gastrointestinal motility function, and temperature regulation. In recent years, a large number of studies have revealed that TRPV1 plays an important role in the physiological and pathological conditions of the digestive system, cardiovascular system, and respiratory system, but there is no systematic report on TRPV1. The objective of this review is to explain the function and effects of TRPV1 on specific diseases, such as irritable bowel syndrome, hypertension, and asthma, and to further investigate the intrinsic relationship between the expression and function of TRPV1 in those diseases to find new therapeutic targets for the cure of related diseases.

Long-term administration of fatty acid amide hydrolase inhibitor (URB597) to rats with spontaneous hypertension disturbs liver redox balance and phospholipid metabolism

PURPOSE

The effect of chronic administration of [3-(3-carbamoylphenyl)phenyl] N-cyclohexylcarbamate (URB597), inhibitor of fatty acid amide hydrolase (FAAH) that hydrolyzes anandamide, on cross-talk between endocannabinoid system, oxidative status and pro-inflammatory factors in the liver of spontaneously hypertensive rats (SHRs) was investigated.

MATERIALS/METHODS

Experiments were conducted using SHRs and normotensive control Wistar-Kyoto rats treated by intraperitoneal injection with URB597 for 14 days. The biochemical parameters were assayed in the rat's livers.

RESULTS

In the liver of SHRs an increase in endocannabinoids level, the activity of enzymes degrading them and expression of the cannabinoid receptor type 2 (CB₂) receptor as well as a decrease in the expression of the CB₁ and vanilloid 1 receptor (TRPV1) were shown. These changes were related to inflammatory conditions as well as oxidative stress resulting from increased reactive oxygen species (ROS) generation due to enhanced activity of enzymes generating ROS accompanied by decrease in the effectiveness of transcription activity of nuclear factor erythroid 2 and the activity of antioxidant enzymes, as well as level of glutathione and vitamins. Chronic administration of URB597 to SHRs caused a decrease in FAAH activity and an increase in anandamide and N-arachidonoyl-dopamine level as well as a decrease in CB₂ and an increase in TRPV1 receptor expression. The levels/activities of pro- and antioxidant and inflammatory factors tended to normalize, but phospholipid peroxidation and DNA modifications were increased.

CONCLUSION

In conclusion, long-term chronic administration of URB597 to SHRs by altering interactions between endocannabinoid and redox systems enhances some liver metabolic disturbances observed in hypertension.

The Regulation of Pulmonary Vascular Tone by Neuropeptides and the Implications for Pulmonary Hypertension

Pulmonary hypertension (PH) is an incurable, chronic disease of small pulmonary vessels. Progressive remodeling of the pulmonary vasculature results in increased pulmonary vascular resistance (PVR). This causes secondary right heart failure. PVR is tightly regulated by a range of pulmonary vasodilators and constrictors. Endothelium-derived substances form the basis of most current PH treatments. This is particularly the case for pulmonary arterial hypertension. The major limitation of current treatments is their inability to reverse morphological changes. Thus, there is an unmet need for novel therapies to reduce the morbidity and mortality in PH. Microvessels in the lungs are highly innervated by sensory C fibers. Substance P and calcitonin gene-related peptide (CGRP) are released from C-fiber nerve endings. These neuropeptides can directly regulate vascular tone. Substance P tends to act as a vasoconstrictor in the pulmonary circulation and it increases in the lungs during experimental PH. The receptor for substance P, neurokinin 1 (NK1R), mediates increased pulmonary pressure. Deactivation of NK1R with antagonists, or depletion of substance P prevents PH development. CGRP is a potent pulmonary vasodilator. CGRP receptor antagonists cause elevated pulmonary pressure. Thus, the balance of these peptides is crucial within the pulmonary circulation (Graphical Abstract). Limited progress has been made in understanding their impact on pulmonary pathophysiology. This is an intriguing area of investigation to pursue. It may lead to promising new candidate therapies to combat this fatal disease. This review provides a summary of the current knowledge in this area. It also explores possible future directions for neuropeptides in PH.

Genetic predisposition to salt-sensitive normotension and its effects on salt taste perception and intake

Salt sensitivity is an independent CVD and mortality risk factor, which is present in both hypertensive and normotensive populations. It is genetically determined and it may affect the relationship between salt taste perception and salt intake. The aim of this study was to explore the genetic predisposition to salt sensitivity in a young and a middle-aged adult population and its effects on salt taste perception and salt intake. The effects of Na loading on blood pressure (BP) were investigated in twenty normotensive subjects and salt sensitivity defined as the change in BP after 7 d of low-Na (51·3 mmol Na/d) and 7 d of high-Na diet (307·8 mmol Na/d). Salt taste perception was identified using the British Standards Institution sensory analysis method (BS ISO 3972:2011). Salt intake was assessed with a validated FFQ. DNA was genotyped for SNP in the SLC4A5, SCNN1B and TRPV1 genes. The subjects with AA genotype of the SLC4A5 rs7571842 exhibited the highest increase in BP (∆ systolic BP=7·75 mmHg, P=0·002, d=2·4; ∆ diastolic BP=6·25 mmHg, P=0·044, d=1·3; ∆ mean arterial pressure=6·5 mmHg, P=0·014, d=1·7). The SLC4A5 rs10177833 was associated with salt intake (P=0·037), and there was an association between salt taste perception and salt sensitivity (rs 0·551, P=0·041). In conclusion, there is a genetic predisposition to salt sensitivity and it is associated with salt taste perception. The association between salt taste perception and discretionary salt use suggests that preference for salty taste may be a driver of salt intake in a healthy population and warrants further investigation.

Important roles of the Ca2+-sensing receptor in vascular health and disease

Ca²⁺-sensing receptor (CaSR), a member of G protein-coupled receptor family, is widely expressed in the vascular system, including perivascular neurons, vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs). When stimulated, CaSR can further increase the cytosolic Ca²⁺ concentration ([Ca²⁺]_cyt) in two ways: intracellular Ca²⁺ release from endo/sarcoplasmic reticulum (ER/SR) and extracellular Ca²⁺ entry through Ca²⁺-permeable cation channels. In endothelium, increased Ca²⁺ subsequently activate nitric oxide synthase (NOS) and intermediate conductance Ca²⁺-activated K⁺ channels (IKCa), resulting in vasodilation through NOS-mediated NO release or membrane hyperpolarization. In VSMCs, CaSR-induced intracellular Ca²⁺ increase causes blood vessel constriction. CaSR activation predominantly induces vasorelaxation of whole vascular tissues through VECs-dependent mechanisms; however, CaSR-induced Ca²⁺ signaling in VSMCs may play a braking role in CaSR-mediated vasorelaxation. Emerging evidence reveals the importance of CaSR in the regulation of vascular tone and blood pressure. Here, we summarized recent advances in CaSR-mediated vascular reaction and the underlying mechanisms in different species, including humans. In addition, several studies have demonstrated that CaSR dysfunction may be associated with some fatal vascular diseases, such as pulmonary arterial hypertension, primary hypertension, diabetes, acute myocardial infarction and vascular calcification. With the advance of studies on CaSR in vascular health and disease, it is expected positive modulators or negative modulators of CaSR used for the treatment of specific diseases may be promising therapeutic options for the prevention and/or treatment of vascular diseases.

Sex-dependent difference in the association between frequency of spicy food consumption and risk of hypertension in Chinese adults

PURPOSE

The aim of our study was to explore the association between frequency of spicy food consumption and risk of hypertension in Chinese adults.

METHODS

Data were extracted from the 2009 wave of the China Health and Nutrition Survey, consisting of 9273 apparently healthy adults. Height, weight, and blood pressure (BP) were measured and diet was assessed with three consecutive 24-h recalls in combination with a weighed food inventory. Frequency of spicy food consumption and degree of pungency in spicy food consumption were self-reported. Hypertension was defined as systolic BP (SBP) ≥ 140 mmHg and/or diastolic BP (DBP) ≥ 90 mmHg, or having known hypertension. Multilevel mixed-effects models were constructed to estimate changes in SBP and DBP levels as well as risk of hypertension.

RESULTS

Higher frequency of spicy food consumption was significantly associated with lower SBP and DBP levels and lower risk of hypertension in female participants after adjustment for potential confounders (all P trend < 0.05) and cluster effects at different levels (individual, community, and province). Compared with female participants who did not eat spicy food, the adjusted odds ratios of hypertension were 0.740 (95% CI 0.569, 0.963; P = 0.025) in female participants who consumed usually, and 0.760 (95% CI 0.624, 0.925; P = 0.006) in female participants who ate spicy food with moderate pungency. There was no significant association of spicy food consumption with hypertension in male participants.

CONCLUSIONS

Frequency of spicy food consumption was inversely associated with risk of hypertension in female, but not male adults.

Modulation of the Oxidative Stress and Lipid Peroxidation by Endocannabinoids and Their Lipid Analogues

Growing evidence supports the pivotal role played by oxidative stress in tissue injury development, thus resulting in several pathologies including cardiovascular, renal, neuropsychiatric, and neurodegenerative disorders, all characterized by an altered oxidative status. Reactive oxygen and nitrogen species and lipid peroxidation-derived reactive aldehydes including acrolein, malondialdehyde, and 4-hydroxy-2-nonenal, among others, are the main responsible for cellular and tissue damages occurring in redox-dependent processes. In this scenario, a link between the endocannabinoid system (ECS) and redox homeostasis impairment appears to be crucial. Anandamide and 2-arachidonoylglycerol, the best characterized endocannabinoids, are able to modulate the activity of several antioxidant enzymes through targeting the cannabinoid receptors type 1 and 2 as well as additional receptors such as the transient receptor potential vanilloid 1, the peroxisome proliferator-activated receptor alpha, and the orphan G protein-coupled receptors 18 and 55. Moreover, the endocannabinoids lipid analogues N-acylethanolamines showed to protect cell damage and death from reactive aldehydes-induced oxidative stress by restoring the intracellular oxidants-antioxidants balance. In this review, we will provide a better understanding of the main mechanisms triggered by the cross-talk between the oxidative stress and the ECS, focusing also on the enzymatic and non-enzymatic antioxidants as scavengers of reactive aldehydes and their toxic bioactive adducts.

Combined effect of acid-sensing ion channel 3 and transient receptor potential vanilloid 1 gene polymorphisms on blood pressure variations in Taiwanese

OBJECTIVES

Both acid-sensing ion channel acid-sensing ion channel 3 (ASIC3) and transient receptor potential vanilloid 1 (TRPV1) have been proposed to be involved in the pathophysiology of hypertension. Common colocalization of ASIC3 and TRPV1 channels in the same sensory neuron has been reported. We aimed to study the combined ASIC3 and TRPV1 gene polymorphisms in the risk of hypertension.

MATERIALS AND METHODS

To test the statistical association between genetic polymorphisms of the ASIC3 and TRPV1 genes and blood pressure (BP) variations in Taiwanese, 551 unrelated individuals (286 men and 265 women) having routine health examinations were recruited. The participants had no history of cardiovascular disease or use of medication for hypertension.

RESULTS

Six ASIC3 and four TRPV1 gene polymorphisms were genotyped, and only the ASIC3 rs2288646 polymorphism was associated with variations in BP in the participants. In subgroup analysis, we found participants carrying the combined ASIC3 rs2288646 AA or AG and TRPV1 rs8065080 CC genotypes (combined genotypes) had significantly higher systolic, mean and diastolic BP compared with the other subgroups (P = 0.009, 0.003, and 0.006, respectively, after Bonferroni correction). Interaction analysis also revealed significant gene-gene interaction in the systolic, mean, and diastolic BP in the ASIC3 and TRPV1 genotypes (interaction P = 0.006, 0.002, and 0.002, respectively). A trend of increasing frequencies of the combined genotype was observed in normotensive, prehypertensive, and hypertensive subgroups (P for trend = 0.001), as well as in those with higher systolic and diastolic BPs (P for trend = 9.13 × 10-4 and P for trend = 5.5 × 10-5, respectively).

CONCLUSION

Our data show a combined effect of ASIC3 and TRPV1 gene polymorphisms in BP variations in Taiwanese. These results suggest that the interaction between ASIC3 and TRPV1 is involved in BP regulation.

Endothelial dysfunction in pulmonary arterial hypertension: an evolving landscape (2017 Grover Conference Series)

Endothelial dysfunction is a major player in the development and progression of vascular pathology in pulmonary arterial hypertension (PAH), a disease associated with small vessel loss and obstructive vasculopathy that leads to increased pulmonary vascular resistance, subsequent right heart failure, and premature death. Over the past ten years, there has been tremendous progress in our understanding of pulmonary endothelial biology as it pertains to the genetic and molecular mechanisms that orchestrate the endothelial response to direct or indirect injury, and how their dysregulation can contribute to the pathogenesis of PAH. As one of the major topics included in the 2017 Grover Conference Series, discussion centered on recent developments in four areas of pulmonary endothelial biology: (1) angiogenesis; (2) endothelial-mesenchymal transition (EndMT); (3) epigenetics; and (4) biology of voltage-gated ion channels. The present review will summarize the content of these discussions and provide a perspective on the most promising aspects of endothelial dysfunction that may be amenable for therapeutic development.

Endothelial dysfunction and vascular disease - a 30th anniversary update

The endothelium can evoke relaxations of the underlying vascular smooth muscle, by releasing vasodilator substances. The best-characterized endothelium-derived relaxing factor (EDRF) is nitric oxide (NO) which activates soluble guanylyl cyclase in the vascular smooth muscle cells, with the production of cyclic guanosine monophosphate (cGMP) initiating relaxation. The endothelial cells also evoke hyperpolarization of the cell membrane of vascular smooth muscle (endothelium-dependent hyperpolarizations, EDH-mediated responses). As regards the latter, hydrogen peroxide (H₂ O₂ ) now appears to play a dominant role. Endothelium-dependent relaxations involve both pertussis toxin-sensitive G_i (e.g. responses to α₂ -adrenergic agonists, serotonin, and thrombin) and pertussis toxin-insensitive G_q (e.g. adenosine diphosphate and bradykinin) coupling proteins. New stimulators (e.g. insulin, adiponectin) of the release of EDRFs have emerged. In recent years, evidence has also accumulated, confirming that the release of NO by the endothelial cell can chronically be upregulated (e.g. by oestrogens, exercise and dietary factors) and downregulated (e.g. oxidative stress, smoking, pollution and oxidized low-density lipoproteins) and that it is reduced with ageing and in the course of vascular disease (e.g. diabetes and hypertension). Arteries covered with regenerated endothelium (e.g. following angioplasty) selectively lose the pertussis toxin-sensitive pathway for NO release which favours vasospasm, thrombosis, penetration of macrophages, cellular growth and the inflammatory reaction leading to atherosclerosis. In addition to the release of NO (and EDH, in particular those due to H₂ O₂ ), endothelial cells also can evoke contraction of the underlying vascular smooth muscle cells by releasing endothelium-derived contracting factors. Recent evidence confirms that most endothelium-dependent acute increases in contractile force are due to the formation of vasoconstrictor prostanoids (endoperoxides and prostacyclin) which activate TP receptors of the vascular smooth muscle cells and that prostacyclin plays a key role in such responses. Endothelium-dependent contractions are exacerbated when the production of nitric oxide is impaired (e.g. by oxidative stress, ageing, spontaneous hypertension and diabetes). They contribute to the blunting of endothelium-dependent vasodilatations in aged subjects and essential hypertensive and diabetic patients. In addition, recent data confirm that the release of endothelin-1 can contribute to endothelial dysfunction and that the peptide appears to be an important contributor to vascular dysfunction. Finally, it has become clear that nitric oxide itself, under certain conditions (e.g. hypoxia), can cause biased activation of soluble guanylyl cyclase leading to the production of cyclic inosine monophosphate (cIMP) rather than cGMP and hence causes contraction rather than relaxation of the underlying vascular smooth muscle.

4-Hydroxynonenal dependent alteration of TRPV1-mediated coronary microvascular signaling

We demonstrated previously that TRPV1-dependent regulation of coronary blood flow (CBF) is disrupted in diabetes. Further, we have shown that endothelial TRPV1 is differentially regulated, ultimately leading to the inactivation of TRPV1, when exposed to a prolonged pathophysiological oxidative environment. This environment has been shown to increase lipid peroxidation byproducts including 4-Hydroxynonenal (4-HNE). 4-HNE is notorious for producing protein post-translation modification (PTM) via reactions with the amino acids: cysteine, histidine and lysine. Thus, we sought to determine if 4-HNE mediated post-translational modification of TRPV1 could account for dysfunctional TRPV1-mediated signaling observed in diabetes. Our initial studies demonstrate 4-HNE infusion decreases TRPV1-dependent coronary blood flow in C57BKS/J (WT) mice. Further, we found that TRPV1-dependent vasorelaxation was suppressed after 4-HNE treatment in isolated mouse coronary arterioles. Moreover, we demonstrate 4-HNE significantly inhibited TRPV1 currents and Ca²⁺ entry utilizing patch-clamp electrophysiology and calcium imaging respectively. Using molecular modeling, we identified potential pore cysteines residues that, when mutated, could restore TRPV1 function in the presence of 4-HNE. Specifically, complete rescue of capsaicin-mediated activation of TRPV1 was obtained following mutation of pore Cysteine 621. Finally, His tag pull-down of TRPV1 in HEK cells treated with 4-HNE demonstrated a significant increase in 4-HNE binding to TRPV1, which was reduced in the TRPV1 C621G mutant. Taken together these data suggest that 4-HNE decreases TRPV1-mediated responses, at both the in vivo and in vitro levels and this dysfunction can be rescued via mutation of the pore Cysteine 621. Our results show the first evidence of an amino acid specific modification of TRPV1 by 4-HNE suggesting this 4-HNE-dependent modification of TRPV1 may contribute to microvascular dysfunction and tissue perfusion deficits characteristic of diabetes.

The role of transient receptor potential channels in hypertension and metabolic vascular damage

NEW FINDINGS

What is the topic of this review? Transient receptor potential (TRP) channels are highly implicated in the pathogenesis of hypertension and the regulation of metabolism. What advances does it highlight? Dysfunction of TRP channels leads to hypertension and metabolic disorders. Elucidating the role of TRP channels in hypertension and metabolic vascular damage would facilitate the design of novel target therapeutics for these intractable diseases. Intracellular Ca²⁺ homeostasis is critical for vascular function and the regulation of metabolism. Metabolic disorders are major risk factors for hypertension. A family of transient receptor potential (TRP) channels plays an important role in the regulation of cellular calcium signalling and cardiometabolic function. Emerging evidence indicates that TRP channels are highly implicated in the pathogenesis of hypertension and metabolic disorders. Dysfunction of TRP channels leads to hypertension and metabolic dysfunction. Activation of certain subtypes of TRP channels could attenuate metabolic vascular damage and alleviate hypertension. Therefore, elucidating the role of TRP channels in the physiological state and in cardiometabolic diseases will facilitate the design of novel targeted therapeutics for these intractable diseases.

Dietary Capsaicin Protects Cardiometabolic Organs from Dysfunction

Chili peppers have a long history of use for flavoring, coloring, and preserving food, as well as for medical purposes. The increased use of chili peppers in food is very popular worldwide. Capsaicin is the major pungent bioactivator in chili peppers. The beneficial effects of capsaicin on cardiovascular function and metabolic regulation have been validated in experimental and population studies. The receptor for capsaicin is called the transient receptor potential vanilloid subtype 1 (TRPV1). TRPV1 is ubiquitously distributed in the brain, sensory nerves, dorsal root ganglia, bladder, gut, and blood vessels. Activation of TRPV1 leads to increased intracellular calcium signaling and, subsequently, various physiological effects. TRPV1 is well known for its prominent roles in inflammation, oxidation stress, and pain sensation. Recently, TRPV1 was found to play critical roles in cardiovascular function and metabolic homeostasis. Experimental studies demonstrated that activation of TRPV1 by capsaicin could ameliorate obesity, diabetes, and hypertension. Additionally, TRPV1 activation preserved the function of cardiometabolic organs. Furthermore, population studies also confirmed the beneficial effects of capsaicin on human health. The habitual consumption of spicy foods was inversely associated with both total and certain causes of specific mortality after adjustment for other known or potential risk factors. The enjoyment of spicy flavors in food was associated with a lower prevalence of obesity, type 2 diabetes, and cardiovascular diseases. These results suggest that capsaicin and TRPV1 may be potential targets for the management of cardiometabolic vascular diseases and their related target organs dysfunction.

How Does Circadian Rhythm Impact Salt Sensitivity of Blood Pressure in Mice? A Study in Two Close C57Bl/6 Substrains

Background

Mouse transgenesis has provided the unique opportunity to investigate mechanisms underlying sodium kidney reabsorption as well as end organ damage. However, understanding mouse background and the experimental conditions effects on phenotypic readouts of engineered mouse lines such as blood pressure presents a challenge. Despite the ability to generate high sodium and chloride plasma levels during high-salt diet, observed changes in blood pressure are not consistent between wild-type background strains and studies.

Methods

The present work was designed in an attempt to determine guidelines in the field of salt-induced hypertension by recording continuously blood pressure by telemetry in mice submitted to different sodium and potassium loaded diets and changing experimental conditions in both C57BL/6N and C57BL/6J mice strain (Normal salt vs. Low salt vs. High-salt/normal potassium vs. High salt/low potassium, standard vs. modified light cycle, Non-invasive tail cuff blood pressure vs. telemetry).

Results

In this study, we have shown that, despite a strong blood pressure (BP) basal difference between C57BL/6N and C57BL/6J mice, High salt/normal potassium diet increases BP and heart rate during the active phase only (dark period) in the same extent in both strains. On the other hand, while potassium level has no effect on salt-induced hypertension in C57BL/6N mice, high-salt/low potassium diet amplifies the effect of the high-salt challenge only in C57BL/6J mice. Indeed, in this condition, salt-induced hypertension can also be detected during light period even though this BP increase is lower compared to the one occurring during the dark period. Finally, from a methodological perspective, light cycle inversion has no effect on this circadian BP phenotype and tail-cuff method is less sensitive than telemetry to detect BP phenotypes due to salt challenges.

Conclusions

Therefore, to carry investigations on salt-induced hypertension in mice, chronic telemetry and studies in the active phase are essential prerequisites.

Crosstalk between liver antioxidant and the endocannabinoid systems after chronic administration of the FAAH inhibitor, URB597, to hypertensive rats

Hypertension is accompanied by perturbations to the endocannabinoid and antioxidant systems. Thus, potential pharmacological treatments for hypertension should be examined as modulators of these two metabolic systems. The aim of this study was to evaluate the effects of chronic administration of the fatty acid amide hydrolase (FAAH) inhibitor [3-(3-carbamoylphenyl)phenyl]N-cyclohexylcarbamate (URB597) on the endocannabinoid system and on the redox balance in the livers of DOCA-salt hypertensive rats. Hypertension caused an increase in the levels of endocannabinoids [anandamide (AEA), 2-arachidonoyl-glycerol (2-AG) and N-arachidonoyl-dopamine (NADA)] and CB1 receptor and the activities of FAAH and monoacylglycerol lipase (MAGL). These effects were accompanied by an increase in the level of reactive oxygen species (ROS), a decrease in antioxidant activity/level, enhanced expression of transcription factor Nrf2 and changes to Nrf2 activators and inhibitors. Moreover, significant increases in lipid, DNA and protein oxidative modifications, which led to enhanced levels of proapoptotic caspases, were also observed. URB597 administration to the hypertensive rats resulted in additional increases in the levels of AEA, NADA and the CB1 receptor, as well as decreases in vitamin E and C levels, glutathione peroxidase and glutathione reductase activities and Nrf2 expression. Thus, after URB597 administration, oxidative modifications of cellular components were increased, while the inflammatory response was reduced. This study revealed that chronic treatment of hypertensive rats with URB597 disrupts the endocannabinoid system, which causes an imbalance in redox status. This imbalance increases the levels of electrophilic lipid peroxidation products, which later participate in metabolic disturbances in liver homeostasis.

Perspectives of TRPV1 Function on the Neurogenesis and Neural Plasticity

The development of new strategies to renew and repair neuronal networks using neural plasticity induced by stem cell graft could enable new therapies to cure diseases that were considered lethal until now. In adequate microenvironment a neuronal progenitor must receive molecular signal of a specific cellular context to determine fate, differentiation, and location. TRPV1, a nonselective calcium channel, is expressed in neurogenic regions of the brain like the subgranular zone of the hippocampal dentate gyrus and the telencephalic subventricular zone, being valuable for neural differentiation and neural plasticity. Current data show that TRPV1 is involved in several neuronal functions as cytoskeleton dynamics, cell migration, survival, and regeneration of injured neurons, incorporating several stimuli in neurogenesis and network integration. The function of TRPV1 in the brain is under intensive investigation, due to multiple places where it has been detected and its sensitivity for different chemical and physical agonists, and a new role of TRPV1 in brain function is now emerging as a molecular tool for survival and control of neural stem cells.

Activation of PPAR-γ by pioglitazone attenuates oxidative stress in aging rat cerebral arteries through upregulating UCP2

Increasing amounts of evidence implicate oxidative stress as having a pivotal role in age-related cerebrovascular dysfunction, which is an important risk factor for the development of cerebrovascular disease. Previous studies have shown that the activation of the expression of peroxisome proliferator-activated receptor gamma (PPAR-γ) in vascular endothelial cells results in an improvement of vascular function. Pioglitazone, a well-known PPAR-γ agonist, protects against oxidative stress in the rostral ventrolateral medulla by the upregulation of mitochondrial uncoupling protein 2 (UCP2). In this study, we sought to explore the effects and the underlying mechanisms of pioglitazone on age-related oxidative stress elevation and cerebrovascular dysfunction in aging rat cerebral arteries. A natural aging model was constructed and used in these experiments. One-month oral administration of pioglitazone (20 mg·kg·d) ameliorated the production of reactive oxygen species, promoted endothelial nitric oxide synthase phosphorylation and increased the nitric oxide available, thus improving endothelium-dependent relaxation in aging rat cerebral arteries. One-month pioglitazone administration also restored PPAR-γ expression and increased the levels of UCP2 in aging rat cerebral arteries. Using in vitro studies, we demonstrated that pioglitazone attenuated reactive oxygen species levels in aging human umbilical vein endothelial cells through PPAR-γ activation. Furthermore, we found that this occurs in an UCP2-dependent manner. Our study demonstrated that the activation of PPAR-γ by pioglitazone protected against oxidative stress damage in aging cerebral arteries by upregulating UCP2. PPAR-γ may be a new target in treating age-related cerebrovascular dysfunction.

Capsaicin may have important potential for promoting vascular and metabolic health

Capsaicin, the phytochemical responsible for the spiciness of peppers, has the potential to modulate metabolism via activation of transient receptor potential vanilloid 1 (TRPV1) receptors, which are found not only on nociceptive sensory neurons, but also in a range of other tissues. TRPV1 activation induces calcium influx, and in certain tissues this is associated with increased activation or expression of key proteins such as endothelial nitric oxide synthase (eNOS), uncoupling protein 2 (UCP2), KLF2, PPARdelta, PPARgamma, and LXRα. The calcium influx triggered by TRPV1 activation in endothelial cells mimics the impact of shear stress in this regard, activating and increasing the expression of eNOS-but also increasing expression of cox-2, thrombomodulin, and nrf2-responsive antioxidant enzymes, while decreasing expression of proinflammatory proteins. Hence, dietary capsaicin has favourably impacted endothelium-dependent vasodilation in rodents. TRPV1-mediated induction of LXRα in foam cells promotes cholesterol export, antagonising plaque formation. Capsaicin-mediated activation of TRPV1-expressing neurons in the gastrointestinal tract promotes sympathetically mediated stimulation of brown fat, raising metabolic rate. The increased expression of UCP2 induced by TRPV1 activation exerts a protective antioxidant effect on the liver in non-alcoholic fatty liver disease, and on vascular endothelium in the context of hyperglycaemia. In rodent studies, capsaicin-rich diets have shown favourable effects on atherosclerosis, metabolic syndrome, diabetes, obesity, non-alcoholic fatty liver, cardiac hypertrophy, hypertension and stroke risk. Clinically, ingestion of capsaicin-or its less stable non-pungent analogue capsiate-has been shown to boost metabolic rate modestly. Topical application of capsaicin via patch was found to increase exercise time to ischaemic threshold in patients with angina. Further clinical studies with capsaicin administered in food, capsules, or via patch, are needed to establish protocols that are tolerable for most patients, and to evaluate the potential of capsaicin for promoting vascular and metabolic health.

Activation of TRPV1 attenuates high salt-induced cardiac hypertrophy through improvement of mitochondrial function

BACKGROUND AND PURPOSE

High-salt diet induces cardiac remodelling and leads to heart failure, which is closely related to cardiac mitochondrial dysfunction. Transient receptor potential (TRP) channels are implicated in the pathogenesis of cardiac dysfunction. We investigated whether activation of TRP vanilloid (subtype 1) (TRPV1) channels by dietary capsaicin can, by ameliorating cardiac mitochondrial dysfunction, prevent high-salt diet-induced cardiac hypertrophy.

EXPERIMENTAL APPROACH

Male wild-type (WT) and TRPV1(-/-) mice were fed a normal or high-salt diet with or without capsaicin for 6 months. Their cardiac parameters and endurance capacity were assessed. Mitochondrial respiration and oxygen consumption were measured using high-resolution respirometry. The expression levels of TRPV1, sirtuin 3 and NDUFA9 were detected in cardiac cells and tissues.

KEY RESULTS

Chronic high-salt diet caused cardiac hypertrophy and reduced physical activity in mice; both effects were ameliorated by capsaicin intake in WT but not in TRPV1(-/-) mice. TRPV1 knockout or high-salt diet significantly jeopardized the proficiency of mitochondrial Complex I oxidative phosphorylation (OXPHOS) and reduced Complex I enzyme activity. Chronic dietary capsaicin increased cardiac mitochondrial sirtuin 3 expression, the proficiency of Complex I OXPHOS, ATP production and Complex I enzyme activity in a TRPV1-dependent manner.

CONCLUSIONS AND IMPLICATIONS

TRPV1 activation by dietary capsaicin can antagonize high-salt diet-mediated cardiac lesions by ameliorating its deleterious effect on the proficiency of Complex I OXPHOS. TRPV1-mediated amendment of mitochondrial dysfunction may represent a novel target for management of early cardiac dysfunction.

Calcitonin gene-related peptide: physiology and pathophysiology

Calcitonin gene-related peptide (CGRP) is a 37-amino acid neuropeptide. Discovered 30 years ago, it is produced as a consequence of alternative RNA processing of the calcitonin gene. CGRP has two major forms (α and β). It belongs to a group of peptides that all act on an unusual receptor family. These receptors consist of calcitonin receptor-like receptor (CLR) linked to an essential receptor activity modifying protein (RAMP) that is necessary for full functionality. CGRP is a highly potent vasodilator and, partly as a consequence, possesses protective mechanisms that are important for physiological and pathological conditions involving the cardiovascular system and wound healing. CGRP is primarily released from sensory nerves and thus is implicated in pain pathways. The proven ability of CGRP antagonists to alleviate migraine has been of most interest in terms of drug development, and knowledge to date concerning this potential therapeutic area is discussed. Other areas covered, where there is less information known on CGRP, include arthritis, skin conditions, diabetes, and obesity. It is concluded that CGRP is an important peptide in mammalian biology, but it is too early at present to know if new medicines for disease treatment will emerge from our knowledge concerning this molecule.

TRPV1 Activation Attenuates High-Salt Diet-Induced Cardiac Hypertrophy and Fibrosis through PPAR-δ Upregulation

High-salt diet-induced cardiac hypertrophy and fibrosis are associated with increased reactive oxygen species production. Transient receptor potential vanilloid type 1 (TRPV1), a specific receptor for capsaicin, exerts a protective role in cardiac remodeling that resulted from myocardial infarction, and peroxisome proliferation-activated receptors δ (PPAR-δ) play an important role in metabolic myocardium remodeling. However, it remains unknown whether activation of TRPV1 could alleviate cardiac hypertrophy and fibrosis and the effect of cross-talk between TRPV1 and PPAR-δ on suppressing high-salt diet-generated oxidative stress. In this study, high-salt diet-induced cardiac hypertrophy and fibrosis are characterized by significant enhancement of HW/BW%, LVEDD, and LVESD, decreased FS and EF, and increased collagen deposition. These alterations were associated with downregulation of PPAR-δ, UCP2 expression, upregulation of iNOS production, and increased oxidative/nitrotyrosine stress. These adverse effects of long-term high-salt diet were attenuated by chronic treatment with capsaicin. However, this effect of capsaicin was absent in TRPV1^−/− mice on a high-salt diet. Our finding suggests that chronic dietary capsaicin consumption attenuates long-term high-salt diet-induced cardiac hypertrophy and fibrosis. This benefit effect is likely to be caused by TRPV1 mediated upregulation of PPAR-δ expression.

Transient receptor potential channels as drug targets: from the science of basic research to the art of medicine

The large Trp gene family encodes transient receptor potential (TRP) proteins that form novel cation-selective ion channels. In mammals, 28 Trp channel genes have been identified. TRP proteins exhibit diverse permeation and gating properties and are involved in a plethora of physiologic functions with a strong impact on cellular sensing and signaling pathways. Indeed, mutations in human genes encoding TRP channels, the so-called "TRP channelopathies," are responsible for a number of hereditary diseases that affect the musculoskeletal, cardiovascular, genitourinary, and nervous systems. This review gives an overview of the functional properties of mammalian TRP channels, describes their roles in acquired and hereditary diseases, and discusses their potential as drug targets for therapeutic intervention.

Transient receptor potential vanilloid 1 activation by dietary capsaicin promotes urinary sodium excretion by inhibiting epithelial sodium channel α subunit-mediated sodium reabsorption

High salt (HS) intake contributes to the development of hypertension. Epithelial sodium channels play crucial roles in regulating renal sodium reabsorption and blood pressure. The renal transient receptor potential vanilloid 1 (TRPV1) cation channel can be activated by its agonist capsaicin. However, it is unknown whether dietary factors can act on urinary sodium excretion and renal epithelial sodium channel (ENaC) function. Here, we report that TRPV1 activation by dietary capsaicin increased urinary sodium excretion through reducing sodium reabsorption in wild-type (WT) mice on a HS diet but not in TRPV1(-/-) mice. The effect of capsaicin on urinary sodium excretion was involved in inhibiting αENaC and its related with-no-lysine kinase 1/serum- and glucocorticoid-inducible protein kinase 1 pathway in renal cortical collecting ducts of WT mice. Dietary capsaicin further reduced the increased αENaC activity in WT mice attributed to the HS diet. In contrast, this capsaicin effect was absent in TRPV1(-/-) mice. Immunoprecipitation study indicated αENaC specifically coexpressed and functionally interact with TRPV1 in renal cortical collecting ducts of WT mice. Additionally, ENaC activity and expression were suppressed by capsaicin-mediated TRPV1 activation in cultured M1-cortical collecting duct cells. Long-term dietary capsaicin prevented the development of high blood pressure in WT mice on a HS diet. It concludes that TRPV1 activation in the cortical collecting ducts by capsaicin increases urinary sodium excretion and avoids HS diet-induced hypertension through antagonizing αENaC-mediated urinary sodium reabsorption. Dietary capsaicin may represent a promising lifestyle intervention in populations exposed to a high dietary salt intake.

High-salt diet enhances hippocampal oxidative stress and cognitive impairment in mice

Previous evidence suggests that a high-salt (HS) diet may increase oxidative stress and contribute to the development of hypertension that is already present. Oxidative stress is thought to play a critical role in the development of neurodegenerative diseases. Lower dietary sodium intake putatively contributes to a lower rate of cognitive impairment; however, the specific effects of HS diet on cognitive function remain poorly understood. In this work, C57BL/6J mice were administered a normal-salt (NS) diet (0.4% NaCl) or a HS diet (7.0% NaCl) for 12 weeks, and cognitive ability and oxidative stress in the brain were measured. It was found that the HS diet significantly impaired retention of spatial memory. Additionally, superoxide anion production in the hippocampus was significantly increased in the HS diet mice compared with that in the NS mice. Interestingly, the antioxidant defense capacities for HS diet mice were markedly reduced in the hippocampus, but not in the cerebral cortex, compared with the NS mice. Taken together, these data demonstrate that HS diet directly impairs retention of spatial memory, which may be related to the increased oxidative stress observed in the hippocampus.

Transient receptor potential vanilloid in blood pressure regulation

PURPOSE OF REVIEW

The involvement of neurohormonal factors in the pathogenesis of hypertension has been extensively studied. However, the mechanisms underlying the role of the transient receptor potential vanilloid type 1 (TRPV1) channels in hypertension are still largely unknown. This review presents some of the most recent findings regarding the potential mechanisms of TRPV1 in mediating blood pressure, the pathophysiology of hypertension, and its related disorders.

RECENT FINDINGS

TRPV1 may be activated by exogenous vanilloid or endo-vanilloid compounds and its function modulated by vasoactive mediators. TRPV1 also interacts with various physiological and pathophysiological systems involved in salt and water homeostasis and cardiovascular homeostasis. Impairment of TRPV1 signaling may contribute to the pathogenesis of diseases such as hypertension, heart failure, atherosclerosis, diabetes, obesity, myocardial ischemia, and stroke.

SUMMARY

Accumulating evidence implicates TRPV1 as serving a key role in cardiovascular health by regulating cardiovascular function and protecting against cardiovascular injury. Given the large prevalence of hypertension and its related disorders, the possible involvement of TRPV1 makes it a potential target of therapy for cardiovascular disease. Future study of TRPV1 may enhance our understanding of several cardiovascular diseases and may unveil novel pharmacological strategies for treating hypertension.

TRPV1-mediated UCP2 upregulation ameliorates hyperglycemia-induced endothelial dysfunction

Background

Diabetic cardiovascular complications are characterised by oxidative stress-induced endothelial dysfunction. Uncoupling protein 2 (UCP2) is a regulator of mitochondrial reactive oxygen species (ROS) generation and can antagonise oxidative stress, but approaches that enhance the activity of UCP2 to inhibit ROS are scarce. Our previous studies show that activation of transient receptor potential vanilloid 1 (TRPV1) by capsaicin can prevent cardiometabolic disorders. In this study, we conducted experiments in vitro and in vivo to investigate the effect of capsaicin treatment on endothelial UCP2 and oxidative stress. We hypothesised that TRPV1 activation by capsaicin attenuates hyperglycemia-induced endothelial dysfunction through a UCP2-mediated antioxidant effect.

Methods

TRPV1^-/-, UCP2 ^-/- and db/db mice, as well as matched wild type (WT) control mice, were included in this study. Some mice were subjected to dietary capsaicin for 14 weeks. Arteries isolated from mice and endothelial cells were cultured. Endothelial function was examined, and immunohistological and molecular analyses were performed.

Results

Under high-glucose conditions, TRPV1 expression and protein kinase A (PKA) phosphorylation were found to be decreased in the cultured endothelial cells, and the effects of high-glucose on these molecules were reversed by the administration of capsaicin. Furthermore, high-glucose exposure increased ROS production and reduced nitric oxide (NO) levels both in endothelial cells and in arteries that were evaluated respectively by dihydroethidium (DHE) and DAF-2 DA fluorescence. Capsaicin administration decreased the production of ROS, restored high-glucose-induced endothelial dysfunction through the activation of TRPV1 and acted in a UCP2-dependent manner in vivo. Administration of dietary capsaicin for 14 weeks increased the levels of PKA phosphorylation and UCP2 expression, ameliorated the vascular oxidative stress and increased NO levels observed in diabetic mice. Prolonged dietary administration of capsaicin promoted endothelium-dependent relaxation in diabetic mice. However, the beneficial effect of capsaicin on vasorelaxation was absent in the aortas of UCP2 ^-/- mice exposed to high-glucose levels.

Conclusion

TRPV1 activation by capsaicin might protect against hyperglycemia-induced endothelial dysfunction through a mechanism involving the PKA/UCP2 pathway.

Transient receptor potential vanilloid 1 (TRPV1), TRPV4, and the kidney

Recent preclinical data indicate that activators of transient receptor potential channels of the vanilloid receptor subtype 1 (TRPV1) may improve the outcome of ischaemic acute kidney injury (AKI). The underlying mechanisms are unclear, but may involve TRPV1 channels in dorsal root ganglion neurones that innervate the kidney. Recent data identified TRPV4, together with TRPV1, to serve as major calcium influx channels in endothelial cells. In these cells, gating of individual TRPV4 channels within a four-channel cluster provides elementary calcium influx (calcium sparklets) to open calcium-activated potassium channels and promote vasodilation. The TRPV receptors can also form heteromers that exhibit unique conductance and gating properties, further increasing their spatio-functional diversity. This review summarizes data on electrophysiological properties of TRPV1/4 and their modulation by endogenous channel agonists such as 20-HETE, phospholipase C and phosphatidylinositide 3-kinase (PI3 kinase). We review important roles of TRPV1 and TRPV4 in kidney physiology and renal ischaemia reperfusion injury; further studies are warranted to address renoprotective mechanism of vanilloid receptors in ischaemic AKI including the role of the capsaicin receptor TRPV1 in primary sensory nerves and/or endothelium. Particular attention should be paid to understand the kidneys' ability to respond to ischaemic stimuli after catheter-based renal denervation therapy in man, whereas the discovery of novel pharmacological TRPV modulators may be a successful strategy for better treatment of acute or chronic kidney failure.

Update on vascular endothelial Ca2+ signalling: A tale of ion channels, pumps and transporters

A monolayer of endothelial cells (ECs) lines the lumen of blood vessels and forms a multifunctional transducing organ that mediates a plethora of cardiovascular processes. The activation of ECs from as state of quiescence is, therefore, regarded among the early events leading to the onset and progression of potentially lethal diseases, such as hypertension, myocardial infarction, brain stroke, and tumor. Intracellular Ca²⁺ signals have long been know to play a central role in the complex network of signaling pathways regulating the endothelial functions. Notably, recent work has outlined how any change in the pattern of expression of endothelial channels, transporters and pumps involved in the modulation of intracellular Ca²⁺ levels may dramatically affect whole body homeostasis. Vascular ECs may react to both mechanical and chemical stimuli by generating a variety of intracellular Ca²⁺ signals, ranging from brief, localized Ca²⁺ pulses to prolonged Ca²⁺ oscillations engulfing the whole cytoplasm. The well-defined spatiotemporal profile of the subcellular Ca²⁺ signals elicited in ECs by specific extracellular inputs depends on the interaction between Ca²⁺ releasing channels, which are located both on the plasma membrane and in a number of intracellular organelles, and Ca²⁺ removing systems. The present article aims to summarize both the past and recent literature in the field to provide a clear-cut picture of our current knowledge on the molecular nature and the role played by the components of the Ca²⁺ machinery in vascular ECs under both physiological and pathological conditions.