Amino acids that centrally influence blood pressure and regional blood flow in conscious rats

Amino Acids during Pregnancy and Offspring Cardiovascular-Kidney-Metabolic Health

Amino acids are essential for normal pregnancy and fetal development. Disruptions in maternal amino acid metabolism have been associated with various adult diseases later in life, a phenomenon referred to as the developmental origins of health and disease (DOHaD). In this review, we examine the recent evidence highlighting the significant impact of amino acids on fetal programming, their influence on the modulation of gut microbiota, and their repercussions on offspring outcomes, particularly in the context of cardiovascular-kidney-metabolic (CKM) syndrome. Furthermore, we delve into experimental studies that have unveiled the protective effects of therapies targeting amino acids. These interventions have demonstrated the potential to reprogram traits associated with CKM in offspring. The discussion encompasses the challenges of translating the findings from animal studies to clinical applications, emphasizing the complexity of this process. Additionally, we propose potential solutions to overcome these challenges. Ultimately, as we move forward, future research endeavors should aim to pinpoint the most effective amino-acid-targeted therapies, determining the optimal dosage and mode of administration. This exploration is essential for maximizing the reprogramming effects, ultimately contributing to the enhancement of cardiovascular-kidney-metabolic health in offspring.

Effects of Vineyard Agro-management Practices on Soil Bacterial Community Composition, and Diversity

Changes in land use strongly affect soil biological and physico-chemical structure and characteristics, which are strongly related to agricultural conversion of natural habitats to man-made usage. These are among the most important and not always beneficial changes, affecting loss of habitats. In Golan Heights basaltic soils, vineyards are currently a driving force in land-use change. Such changes could have an important effect on soil microbial community that play an important role in maintaining stable functioning of soil ecosystems. This study investigated the microbial communities in five different agro-managements using molecular tools that can clarify the differences in microbial community structure and function. Significant differences in soil microbial community composition were found. However, no differences in alpha diversity or functionality were found between the treatments. To the best of our knowledge, this is the first report indicating that the bacterial community in different agro-managements provide an insight into the potential function of a vineyard system.

Searching for Metabolic Markers of Stroke in Human Plasma via NMR Analysis

More than 12 million people around the world suffer a stroke every year, one every 3 s. Stroke has a variety of causes and is often the result of a complex interaction of risk factors related to age, genetics, gender, lifestyle, and some cardiovascular and metabolic diseases. Despite this evidence, it is not possible to prevent the onset of stroke. The use of innovative methods for metabolite analysis has been explored in the last years to detect new stroke biomarkers. We use NMR spectroscopy to identify small molecule variations between different stages of stroke risk. The Framingham Stroke Risk Score was used in people over 63 years of age living in long-term care facilities (LTCF) to calculate the probability of suffering a stroke. Using this parameter, three study groups were formed: low stroke risk (LSR, control), moderate stroke risk (MSR) and high stroke risk (HSR). Univariate statistical analysis showed seven metabolites with increasing plasma levels across different stroke risk groups, from LSR to HSR: isoleucine, asparagine, formate, creatinine, dimethylsulfone and two unidentified molecules, which we termed "unknown-1" and "unknown-3". These metabolic markers can be used for early detection and to detect increasing stages of stroke risk more efficiently.

The Impact of Nutrient Intake and Metabolic Wastes during Pregnancy on Offspring Hypertension: Challenges and Future Opportunities

Hypertension can have its origin in early life. During pregnancy, many metabolic alterations occur in the mother that have a crucial role in fetal development. In response to maternal insults, fetal programming may occur after metabolic disturbance, resulting in programmed hypertension later in life. Maternal dietary nutrients act as metabolic substrates for various metabolic processes via nutrient-sensing signals. Different nutrient-sensing pathways that detect levels of sugars, amino acids, lipids and energy are integrated during pregnancy, while disturbed nutrient-sensing signals have a role in the developmental programming of hypertension. Metabolism-modulated metabolites and nutrient-sensing signals are promising targets for new drug discovery due to their pathogenic link to hypertension programming. Hence, in this review, we pay particular attention to the maternal nutritional insults and metabolic wastes affecting fetal programming. We then discuss the role of nutrient-sensing signals linking the disturbed metabolism to hypertension programming. This review also summarizes current evidence to give directions for future studies regarding how to prevent hypertension via reprogramming strategies, such as nutritional intervention, targeting nutrient-sensing signals, and reduction of metabolic wastes. Better prevention for hypertension may be possible with the help of novel early-life interventions that target altered metabolism.

A hierarchical approach to removal of unwanted variation for large-scale metabolomics data

Liquid chromatography-mass spectrometry-based metabolomics studies are increasingly applied to large population cohorts, which run for several weeks or even years in data acquisition. This inevitably introduces unwanted intra- and inter-batch variations over time that can overshadow true biological signals and thus hinder potential biological discoveries. To date, normalisation approaches have struggled to mitigate the variability introduced by technical factors whilst preserving biological variance, especially for protracted acquisitions. Here, we propose a study design framework with an arrangement for embedding biological sample replicates to quantify variance within and between batches and a workflow that uses these replicates to remove unwanted variation in a hierarchical manner (hRUV). We use this design to produce a dataset of more than 1000 human plasma samples run over an extended period of time. We demonstrate significant improvement of hRUV over existing methods in preserving biological signals whilst removing unwanted variation for large scale metabolomics studies. Our tools not only provide a strategy for large scale data normalisation, but also provides guidance on the design strategy for large omics studies.

Mass spectrometry-based metabolomics is a powerful method for profiling large clinical cohorts but batch variations can obscure biologically meaningful differences. Here, the authors develop a computational workflow that removes unwanted data variation while preserving biologically relevant information.

The trace amine theory of spontaneous hypertension as induced by classic monoamine oxidase inhibitors

The classic monoamine oxidase inhibitors (MAOIs) tranylcypromine (TCP) and phenelzine (PLZ) are powerful antidepressants that come with an equally powerful stigma, and are thus rarely prescribed-despite their well-established effectiveness. Some of these preconceptions appear to stem from unclarity, as the etiology of a rare but important side effect, 'spontaneous hypertension' (SH)-a significant increase in blood pressure absent dietary tyramine ingestion-remains improperly elucidated. This paper aims at uprooting some of the stigma surrounding MAOIs by advancing the trace amine (TA) theory as the causative underpinning of SH. This theory posits that SH results from the considerable influx of TAs observed following TCP- or PLZ-administration. TAs are known, albeit at greatly supraphysiological levels, to raise blood pressure on account of their propensity to exert potent indirect sympathomimetic effects; additionally, some research posits that TAs may induce vasoconstrictive effects partly or wholly separate therefrom, which would then constitute a second hypertensive mechanism. TAs are endogenous to the human body in low quantities. Both TCP and PLZ cause marked elevations of 2-phenylethylamine (PEA), meta- and para-tyramine (m-/p-TYR), octopamine (OA), and tryptamine (TRYP), following both acute and (sub)chronic administration. This paper holds that TYR plays a pivotal role in causing SH, due to its strong pressor effect. Cautious treatment of SH is advised, given its typically self-limiting nature. The risk of hypotensive overshoots must be taken into account. For severe cases, this paper urges reconsideration, following suitable confirmation trials, of antipsychotics (notably risperidone) as these agents may reduce striatal p-TYR levels.

The Aging GABAergic System and Its Nutritional Support

Aging is associated with a decline in hormones and an associated decline in GABAergic function and calcium and ion current dysregulation. Neurosteroid hormones act as direct calcium channel blockers, or they can act indirectly on calcium channels through their interaction with GABA receptors. The calcium channel dysfunction associated with hormone loss further leads to an excitatory cell state, which can ultimately lead to cell death. The calcium theory of aging posits that cellular mechanisms, which maintain the homeostasis of cytosol Ca2+ concentration, play a key role in brain aging and that sustained changes in Ca2+ homeostasis provide the final common pathway for age-associated brain changes. There is a link between hormone loss and calcium dysregulation. Loss of calcium regulation associated with aging can lead to an excitatory cell state, primarily in the mitochondria and nerve cells, which can ultimately lead to cell death if not kept in check. A decline in GABAergic function can also be specifically tied to declines in progesterone, allopregnanolone, and DHEA levels associated with aging. This decline in GABAergic function associated with hormone loss ultimately affects GABAergic inhibition or excitement and calcium regulation throughout the body. In addition, declines in GABAergic function can also be tied to vitamin status and to toxic chemicals in the food supply. The decline in GABAergic function associated with aging has an effect on just about every body organ system. Nutritional support of the GABAergic system with supportive foods, vitamins, and GABA or similar GABA receptor ligands may address some of the GABAergic dysfunction associated with aging.

Parasympathetic brainstem origin sites of triggered external and internal carotid vasodilation are not distributed topographically in the rat

Cranial parasympathetic activation produces vasodilation in the head and neck region, but little is known about its central and peripheral mechanisms. This study was conducted to examine whether external and internal carotid-vasodilation origin sites triggered by chemical stimulation are distributed topographically in the parasympathetic brainstems of anesthetized rats, and to examine the effects of peripheral receptors on vasodilation. Microinjection of the neuromodulator candidate l-cysteine revealed that external and internal carotid vasodilation-triggering sites were distributed non-topographically along the full extent of the parasympathetic parvocellular reticular formation (PcRt). Intravenous injection of a muscarinic blocker and a nitric oxide synthase inhibitor abolished external carotid vasodilation, suggesting the peripheral involvement of muscarinic and nitric oxide receptors. Further work is needed to fully understand the PcRt mechanisms underlying timely and appropriate vasodilation to support various cranial functions.

Nicotine Exposure Along with Oral Contraceptive Treatment in Female Rats Exacerbates Post-cerebral Ischemic Hypoperfusion Potentially via Altered Histamine Metabolism

Smoking-derived nicotine (N) and oral contraceptives (OCs) synergistically exacerbate ischemic brain damage in the female, and the underlying mechanisms remain elusive. Our published study showed that N toxicity is exacerbated by OC via altered mitochondrial electron transport chain function. Because mitochondria play an important role in cellular metabolism, we investigated the global metabolomic profile of brains of adolescent and adult female Sprague-Dawley rats exposed to N with or without OC (N+/-OC). Rats were randomly exposed to saline or N+/-OC for 16-21 days followed by random allocation into two cohorts. The first cohort was used to characterize the cortical metabolome. Pathway enrichment analysis showed a significant increase in several histamine metabolites including 1-methylhistamine, 1-methyl-4-imidazoleacetate, and 1-ribosyl-imidazleacetate, along with carnosine and homocarnosine in adolescent and adult animals treated with N and N+OC in relation to respective saline controls, which may be reflective of altered histamine metabolism with nicotine treatment. We also observed reduced levels of the neurotransmitters N-acetyl-aspartyl-glutamate (NAAG), gamma-aminobutyrate (GABA), and N-methyl-GABA in N+OC treatment in adolescent animals. The second cohort underwent bilateral carotid artery occlusion and hypotension followed by cerebral blood flow (CBF) assessment a day later. Autoradiographic images of the brain 24 h after ischemic episodes showed severe reduction in cortical and hippocampal local CBF in N+/-OC-exposed rats compared with saline treated. Because GABA and histamine are critical for CBF maintenance, altered metabolism of these neurotransmitters may be responsible for observed severe post-ischemic hypoperfusion, which in turn exacerbates ischemic brain damage.

Early Origins of Hypertension: Should Prevention Start Before Birth Using Natural Antioxidants?

Hypertension may originate in early life. Reactive oxygen species (ROS) generated due to the exposure of adverse in utero conditions causes developmental programming of hypertension. These excessive ROS can be antagonized by molecules which are antioxidants. Prenatal use of natural antioxidants may reverse programming processes and prevent hypertension of developmental origin. In the current review, firstly we document data on the impact of oxidative stress in hypertension of developmental origin. This will be followed by effective natural antioxidants uses starting before birth to prevent hypertension of developmental origin in animal models. It will also discuss evidence for the common mechanisms underlying developmental hypertension and beneficial effects of natural antioxidant interventions used as reprogramming strategies. A better understanding of the reprogramming effects of natural antioxidants and their interactions with common mechanisms underlying developmental hypertension is essential. Therefore, pregnant mothers and their children can benefit from natural antioxidant supplementation during pregnancy in order to reduce their risk for hypertension later in life.

Amino Acids and Developmental Origins of Hypertension

During pregnancy, amino acids are important biomolecules that play essential roles in fetal growth and development. Imbalanced amino acid intake during gestation may produce long-term morphological or functional changes in offspring, for example, developmental programming that increases the risk of developing hypertension in later life. Conversely, supplementation with specific amino acids could reverse the programming processes in early life, which may counteract the rising epidemic of hypertension. This review provides an overview of the evidence supporting the importance of amino acids during pregnancy and fetal development, the impact of amino acids on blood pressure regulation, insight from animal models in which amino acids were used to prevent hypertension of developmental origin, and interactions between amino acids and the common mechanisms underlying development programming of hypertension. A better understanding of the pathophysiological roles of specific amino acids and their interactions in developmental programming of hypertension is essential so that pregnant mothers are able to benefit from accurate amino acid supplementation during pregnancy in order to prevent hypertension development in their children.

Relationship of reduced glomerular filtration rate with alterations in plasma free amino acids and uric acid evaluated in healthy control and hypertensive subjects

The potential association between altered levels of plasma free amino acids (PFAAs) and uric acid (UA) with estimated glomerular filtration rate (eGFR) remains unknown among patients with hypertension. A total of 2804 healthy controls and 2455 hypertensive patients were included in the current analysis. eGFR was defined as reduced when it was <60 ml/min/1.73 m². The associations between reduced eGFR and individual PFAAs and UA in the healthy control and hypertension groups were explored by logistic regression analyses adjusted for potential confounding variables. Results show that UA had a significant positive association with reduced eGFR in both healthy control and hypertension groups (P < 0.001). Among the PFAAs, citrulline, glycine and phenylalanine showed significant positive associations with reduced eGFR in both healthy control (P < 0.01 to 0.001) and hypertension (P < 0.001) groups. Moreover, alanine, asparagine and methionine achieved significant positive associations with reduced eGFR only in the hypertension group (P < 0.01 to 0.001). Conversely, serine showed significant inverse associations with reduced eGFR in the hypertension group only (P < 0.001). Our findings provide first evidence for a strong relationship between distinct patterns of PFAAs and elevated UA with reduced eGFR in hypertension. The findings may appear useful in developing effective strategies for the prevention or early detection and treatment of declined kidney function in hypertension.

High dietary intake of aromatic amino acids increases risk of hypertension

Recent studies investigated the relation between amino acids and blood pressure. Our aim was to examine the association between intake of aromatic amino acids (AAAs) and risk of hypertension. A total of 4288 individuals, aged 20-70 years, participants of the Tehran Lipid and Glucose Study, who were free of hypertension at baseline (2008-2011), were followed for 3 years (2011-2014). Average intakes of AAAs including phenylalanine, tyrosine, and tryptophan were collected using a valid and reliable food frequency questionnaire at baseline. Adjusted logistic regression models were used to report odds ratio (OR) of hypertension across quartiles of AAAs. At the end of follow-up, 429 (10%) hypertension cases were ascertained. The adjusted OR of hypertension for percentage of AAAs from total protein intakes was 1.63 (95% confidence interval, 1.06-2.50; P for trend: .03) when comparing the highest quartile to the lowest. Furthermore, in the adjusted analyses, a statistically significant positive relationship was observed between the highest versus the lowest quartile intake of phenylalanine (OR = 1.66; 95% confidence interval, 1.14-2.47; P for trend: .03). However, there was no significant association of tyrosine and tryptophan intakes with hypertension risk. Our data suggest that AAAs may increase the risk of incident hypertension.

Hypotensive effect of S-adenosyl-L-methionine in hypertensive rats is reduced by autonomic ganglia and KATP channel blockers

S-adenosyl-L-methionine (SAM) is an amino acid involved in a number of physiological processes in the nervous system. Some evidence suggests a therapeutic potential of SAM in hypertension. In this study we investigated the effect of intracerebroventricular (ICV) infusions of SAM on arterial blood pressure in rats. Mean arterial blood pressure (MABP) and heart rate (HR) were measured at baseline and during ICV infusion of either SAM or vehicle (aCSF; controls) in conscious, male normotensive Wistar Kyoto rats (WKY) and Spontaneously Hypertensive Rats (SHR). MABP and HR were not affected by the vehicle. WKY rats infused with SAM (10 μM, 100 μM and 1 mM) showed a biphasic hemodynamic response i.e., mild hypotension and bradycardia followed by a significant increase in MABP and HR. On the contrary, SHR infused with SAM showed a dose-dependent hypotensive response. In separate series of experiments, pretreatment with hexamethonium, a ganglionic blocker as well as pretreatment with glibenclamide, a KATP channel blocker reduced the hemodynamic effects of SAM. SAM may affect the nervous control of arterial blood pressure via the autonomic nervous system and KATP channel-dependent mechanisms.

N-methylation of peptides and proteins: an important element for modulating biological functions

N-Methylation is one of the simplest chemical modifications often occurring in peptides and proteins of prokaryotes and higher eukaryotes. Over years of evolution, nature has employed N-methylation of peptides as an ingenious technique to modulate biological function, often as a mode of survival through the production of antibiotics. This small structural change can not only mobilize large protein complexes (as in the histone methylation), but also inhibits the action of enzymes by selective recognition of protein-protein interaction surfaces. In recent years through the advancement in synthetic approaches, the potential of N-methylation has begun to be revealed, not only in modulating biological activity and selectivity as well as pharmacokinetic properties of peptides, but also in delivering novel drugs. Herein, we summarize the current knowledge of the versatility of N-methylation in modulating biological, structural, and pharmacokinetic properties of peptides.