Metabolic profile of blood serum in experimental arterial hypertension.

The etiology of essential hypertension is intricate, since it employs simultaneously various body systems related to the regulation of blood pressure in one way or another: the sympathetic nervous system, renin-angiotensin-aldosterone and hypothalamic-pituitary-adrenal systems, renal and endothelial mechanisms. The pathogenesis of hypertension is influenced by a variety of both genetic and environmental factors, which determines the heterogeneity of the disease in human population. Hence, there is a need to perform research on experimental models - inbred animal strains, one of them being ISIAH rat strain, which is designed to simulate inherited stress-induced arterial hypertension as close as possible to primary (or essential) hypertension in humans. To determine specific markers of diseases, various omics technologies are applied, including metabolomics, which makes it possible to evaluate the content of low-molecular compounds - amino acids, lipids, carbohydrates, nucleic acids fragments - in biological samples available for clinical analysis (blood and urine). We analyzed the metabolic profile of the blood serum of male ISIAH rats with a genetic stress-dependent form of arterial hypertension in comparison with the normotensive WAG rats. Using the method of nuclear magnetic resonance spectroscopy (NMR spectroscopy), 56 metabolites in blood serum samples were identified, 18 of which were shown to have significant interstrain differences in serum concentrations. Statistical analysis of the data obtained showed that the hypertensive status of ISIAH rats is characterized by increased concentrations of leucine, isoleucine, valine, myo-inositol, isobutyrate, glutamate, glutamine, ornithine and creatine phosphate, and reduced concentrations of 2-hydroxyisobutyrate, betaine, tyrosine and tryptophan. Such a ratio of the metabolite concentrations is associated with changes in the regulation of glucose metabolism (metabolic markers - leucine, isoleucine, valine, myo-inositol), of nitric oxide synthesis (ornithine) and catecholamine pathway (tyrosine), and with inflammatory processes (metabolic markers - betaine, tryptophan), all of these changes being typical for hypertensive status. Thus, metabolic profiling of the stress-dependent form of arterial hypertension seems to be an important result for a personalized approach to the prevention and treatment of hypertensive disease.

Hypotensive Effects of Arginase Inhibition by L-Norvaline in Genetic Models of Normotensive and Hypertensive Rats.

The main effect of arginase inhibition after administration of L-norvaline is a decrease in BP. At the same time, norvaline causes various side effects in normotensive and hypertensive animals. In our experiments, L-norvaline was administered intraperitoneally (30 mg/kg) for 7 days to normotensive WAG rats (Wistar Albino Glaxo) and hypertensive ISIAH rats (Inherited, Stress-Induced Arterial Hypertension). In ISIAH rats, BP decrease was accompanied by an increase in diuresis, while in WAG rats, diuresis remained unchanged or little changed. At the same time, hypertensive rats demonstrated an increase of catecholamine content in the adrenal glands, while in normotensive animals, it was decreased. The differences in the effects of norvaline can be associated with different mechanisms of BP maintenance in normotensive and hypertensive animals. Normally, BP is maintained by the regulatory influences of the nitric oxide system. In hypertension, this system is weakened, and the hypotensive effects are probably achieved via increased diuresis.

[Genes Associated with Increased Stress Sensitivity in Hypertensive ISIAH Rats].

Inherited stress-induced arterial hypertension (ISIAH) rats are characterized by increased stress reactivity of the hypothalamic-pituitary-adrenal and sympathoadrenal systems. The genetic basis of increased susceptibility to stress was studied in hypertensive ISIAH rats. Adrenal transcriptomes were sequenced in hypertensive ISIAH and normotensive WAG rats, and nine differentially expressed genes (DEGs) were found in the X-chromosome locus that was previously associated with mild emotional stress-induced increases in blood pressure and plasma corticosterone and an increased adrenal weight in ISIAH rats. An analysis of the functions performed by DEG-encoded proteins suggested the Sms (spermine synthase) gene to be the most likely candidate gene in the X-chromosome locus associated with an elevated stress susceptibility in ISIAH rats.

RatDEGdb: a knowledge base of differentially expressed genes in the rat as a model object in biomedical research.

The animal models used in biomedical research cover virtually every human disease. RatDEGdb, a knowledge base of the differentially expressed genes (DEGs) of the rat as a model object in biomedical research is a collection of published data on gene expression in rat strains simulating arterial hypertension, age-related diseases, psychopathological conditions and other human afflictions. The current release contains information on 25,101 DEGs representing 14,320 unique rat genes that change transcription levels in 21 tissues of 10 genetic rat strains used as models of 11 human diseases based on 45 original scientific papers. RatDEGdb is novel in that, unlike any other biomedical database, it offers the manually curated annotations of DEGs in model rats with the use of independent clinical data on equal changes in the expression of homologous genes revealed in people with pathologies. The rat DEGs put in RatDEGdb were annotated with equal changes in the expression of their human homologs in affected people. In its current release, RatDEGdb contains 94,873 such annotations for 321 human genes in 836 diseases based on 959 original scientific papers found in the current PubMed. RatDEGdb may be interesting first of all to human geneticists, molecular biologists, clinical physicians, genetic advisors as well as experts in biopharmaceutics, bioinformatics and personalized genomics. RatDEGdb is publicly available at https://www.sysbio.ru/RatDEGdb.

Antisense Oligonucleotides Immobilized on Silicon-Organic Nanoparticles as a Tool for Prolonged Correction of Hypertensive States.

We propose an original method for controlling BP by administration of Si~ODN nanocomposites containing antisense oligonucleotides fixed on silicon-organic nanoparticles. ODN in nanocomposites are targeted to mRNA of the genes encoding angiotensin-converting enzyme (ACE1) and type 1 angiotensin-II receptor (AT1A). The experiments were performed on hypertensive ISIAH rats, a genetic model of hypertension. Single inhalation or intraperitoneal administration of the nanocomposites targeted to ACE1 mRNA or ATA1 mRNA, respectively, led to a pronounced decrease (by ~30 mm Hg) in systolic BP in ISIAH rats over a week. The use of scrambled ODN in the nanocomposites had no effect. A decrease in the expression of ACE1 and AT1A genes under the effect of the corresponding antisense ODN was demonstrated, which attested to directed effect of the test preparations.

[Epigenetic Mechanisms of Blood-Pressure Regulation].

The role of epigenetic mechanisms involved in blood-pressure regulation has been reviewed. It is known that some periods in early pre- and postnatal ontogenesis are very sensitive to some environmental and endogenous influences. These periods are characterized as highly vulnerable to the formation of a complex of epigenetic changes that may determine the trajectory of the further formation of physiological systems involved in the blood-pressure regulation. Early life influences on these systems may predispose an individual to the development of hypertensive disease in further life. In some cases, the transmission of epigenetic changes to the next generations may resolve the contradiction between the high heritability of arterial hypertensive disease and the low total contribution of polymorphic DNA variants in the population variability of blood pressure values.

[Differential alternative splicing in brain regions of rats selected for aggressive behavior].

Profiles of alternative mRNA isoforms have been determined in three brain regions of rats from an aggressive and a tame line selected for 74 generations. Among 2319 genes with alternatively spliced exons, approximately 84% were confirmed by analyzing public databases. Based on Gene Ontology-guided clustering of alternatively spliced genes, it has been found that the sample was enriched in synapse-specific genes (FDR < 10^(-17)). Patterns of gene expression in the brains of animals with genetically determined high or low aggression were more frequently found to differ in the use of alternatively spliced exons than in animals environmentally conditioned for increased or lowered propensity to aggression. For the Adcyap1r1 gene, five alternatively spliced mRNA isoforms have been represented differentially in aggressive animals. A detailed analysis of the gene that encodes glutamate ionotropic receptor NMDA type subunit 1 (Grin1) has confirmed significant differences in the levels of its alternatively spliced isoforms in certain brain regions of tame and aggressive rats. These differences may affect the behavior in rats genetically selected for aggression levels.

[Increase in the concentration of sEH protein in renal medulla of ISIAH rats with inherited stress-induced arterial hypertension].

The concentration of soluble epoxide hydrolase (sEH) protein was studied in renal medulla of adult rats from hypertensive ISIAH strain and normotensive WAG strain. The sEH is a key enzyme in metabolism of epoxyeicosatrienoic acids capable of activating endothelial NO-synthase and nitrogen oxide formation, and therefore being vasodilators. An increase in the sEH protein concentration (that we found) allows one to assume that the oxidative stress is increased in the renal medulla of hypertensive rats, and the bloodflow is decreased.

Quercetin Attenuates Benzo(α)pyrene-induced CYP1A Expression.

We studied effects of nutrient quercetin on cytochromes' Р450 1А (CYP1A) activities (measured spectrofluorimetrically using 7-ethoxy-resorufin for CYP1A1 and 7-methoxy-resorufin for CYP1A2 as substrates), on mRNA levels (measured by RT-PCR), and on DNA-binding activities (evaluated by an electrophoretic mobility shift assay) of proteins regulating CYP1A expression in untreated and benzo(α)pyrene (BaP)-treated rats. Wistar rats received quercetin, BaP, or both once daily for 1-3 days. Quercetin did not influence CYP1A1 in untreated rats but inhibited BaP-mediated CYP1A induction on the transcriptional level decreasing positive input (AhR functional activity) and increasing negative input (AhRR/ARNT expression and Oct-1 and C/EBP functional activities).

Toward Gene Therapy of Hypertension: Experimental Study on Hypertensive ISIAH Rats.

TiO2-based nanocomposites were prepared to deliver oligonucleotides into cells. The nanocomposites were designed by the immobilization of polylysine-containing oligonucleotides on TiO2-nanoparticles (TiO2·PL-DNA). We showed for the first time the possibility of using the proposed nanocomposites for treatment of hypertensive disease by introducing them into hypertensive ISIAH rats developed as a model of stress-sensitive arterial hypertension. The mRNA of the gene encoding angiotensin I-converting enzyme (ACE1) involved in the synthesis of angiotensin II was chosen as a target. Administration (intraperitoneal injection and inhalation) of the nanocomposite showed a significant (by 20-30 mm Hg) decrease in systolic blood pressure when the nanocomposite contained the ACE1 gene-targeted oligonucleotide. When using the oligonucleotide with a random sequence, no effect was observed. Further development and improvement of the inhalation nanocomposite drug delivery to systemic hypertensive disease treatment promises new possibilities for clinical practice.

Stress-sensitive arterial hypertension, haemodynamic changes and brain metabolites in hypertensive ISIAH rats: MRI investigation.

NEW FINDINGS: What is the central question of this study? Stress-sensitive arterial hypertension is considered to be controlled by changes in central and peripheral sympathetic regulating mechanisms, which eventually result in haemodynamic alterations and blood pressure elevation. Therefore, study of the early stages of development of hypertension is of particular interest, because it helps in understanding the aetiology of the disease. What is the main finding and its importance? Non-invasive in vivo investigation in ISIAH rats demonstrated that establishment of sustainable stress-sensitive hypertension is accompanied by a decrease in prefrontal cortex activity and mobilization of hypothalamic processes, with considerable correlations between haemodynamic parameters and individual metabolite ratios. The study of early development of arterial hypertension in association with emotional stress is of great importance for better understanding of the aetiology and pathogenesis of the hypertensive disease. Magnetic resonance imaging (MRI) was applied to evaluate the changes in haemodynamics and brain metabolites in 1- and 3-month-old inherited stress-induced arterial hypertension (ISIAH) rats (10 male rats) with stress-sensitive arterial hypertension and in control normotensive Wistar Albino Glaxo (WAG) rats (eight male rats). In the 3-month-old ISIAH rats, the age-dependent increase in blood pressure was associated with increased blood flow through the renal arteries and decreased blood flow in the lower part of the abdominal aorta. The renal vascular resistance in the ISIAH rats decreased during ageing, although at both ages it remained higher than the renal vascular resistance in WAG rats. An integral metabolome portrait demonstrated that development of hypertension in the ISIAH rats was associated with an attenuation of the excitatory and energetic activity in the prefrontal cortex, whereas in the WAG rats the opposite age-dependent changes were observed. In contrast, in the hypothalamus of 3-month-old ISIAH rats, an increase in energetic activity and prevalence of excitatory over inhibitory neurotransmitters was noticed. The blood flow through the main arteries showed a positive correlation with glutamate and glutamine levels in the hypothalamus and a negative correlation with the hypothalamic GABA level. The blood pressure values were positively correlated with hypothalamic choline levels. Thus, the early development of stress-sensitive hypertension in the ISIAH rats is accompanied by considerable changes both in brain metabolite ratios and in the parameters of blood flow through the main arteries.

Strain-Specific Single-Nucleotide Polymorphisms in Hypertensive ISIAH Rats.

Single-nucleotide polymorphisms (SNPs) in the coding and regulatory regions of genes can affect transcription rate and translation efficiency, modify protein function, and, in some cases, cause the development of diseases. In the current study, the RNA-Seq approach has been used to discover strain-specific SNPs in ISIAH (inherited stress-induced arterial hypertension) rats, which are known as a model of stress-induced arterial hypertension. The comparison of the ISIAH SNPs with genome sequencing data available for another 42 rat strains and substrains, 11 of them known as hypertensive, showed a considerable genetic distance between the genotypes of ISIAH and all other rat strains and substrains. The study revealed 1849 novel SNPs specific for ISIAH rats and 158 SNPs present only in the genotypes of hypertensive rats. Amino acid substitutions with possible deleterious effect on protein function were detected. Several of them were found in the genes associated with hypertension. These SNPs may be considered as novel molecular targets for further studies aimed at assessing their potential in the therapy of stress-induced hypertension.

Parameters of Blood Flow in Great Arteries in Hypertensive ISIAH Rats with Stress-Dependent Arterial Hypertension.

Magnetic resonance angiography was used to examine blood flow in great arteries of hypertensive ISIAH and normotensive Wistar rats. In hypertensive ISIAH rats, increased vascular resistance in the basin of the abdominal aorta and renal arteries as well as reduced fraction of total renal blood flow were found. In contrast, blood flow through both carotid arteries in ISIAH rats was enhanced, which in suggests more intensive blood supply to brain regulatory centers providing enhanced stress reactivity of these rats characterized by stress-dependent arterial hypertension.

[Comparative Analysis of Behavior in The Open-field Test in Wild Grey Rats (Rattus norvegicus) and in Grey Rats Subjected to Prolonged Selection for Tame And Aggressive Behavior].

The aim of this work is analysis of the open-field behavior in grey rats selected for the tame and aggressive behavior in comparison with the wild grey rats. Significant influences of the rat group factor on the 13 of 19 behavioral features studied in the open-field were found. This effect, in general, depends on existence of great differences between behaviors of the wild rats from the one hand and behaviors of the tame and aggressive rats from the other. The behaviors of the rats from the last two groups are practically identical. Multidimensional analysis confirms the distinct separation in coordinates of the two main components of the wild rat behavior from the behavior of both the tame and selectively bred aggressive rats. The first main component dimension corresponds to the grade of fear, which was significantly enhanced in the wild rats. So, in spite of the equality of behavioral aggressiveness of the wild rats and the rats selected for aggression with the glove test, the behavior of selected aggressive rats in the open-field is analogous to behavior of the rats selected for tameness. Comparison of behavioral features with the hormonal stress responsiveness allowed us to conclude that the aggressive behavior of the wild and se lected for aggression rats based on different motivational and neuroendocrine processes.

[Expression of Catechol-O-Methyltransferase (Comt), Mineralocorticoid Receptor (Mlr), and Epithelial Sodium Channel (ENaC) Genes in Kidneys of Hypertensive ISIAH Rats at Rest and during Response to Stress].

Emotional stress plays a significant role in the processes of the development of arterial hypertension, especially in the presence of genetic predisposition. The origin and maintenance of hypertensive status during stress development can be activated by the sympathetic nervous system. An increase in sympathetic stimulation can, in turn, result in a change in the functions of kidneys, which provide fluid and electrolyte balance of the organism. A comparative study of the mRNA expression level of catechol-o-methyltransferase (Comt), mineralocorticoid receptor (Mlr), and ß-subunit of epithelial sodium channel (ß-ENaC) genes was conducted on the kidneys of hypertensive ISIAH rats and normotensive WAG rats at rest and after the effect of emotional stress. The discovered changes in the expression level of the selected genes confirm their involvement in increased sympathetic stimulation of the kidney, along with changes in the function of kidney regulation of fluid and electrolyte balance, which is an important factor of the development of sustained hypertension in the ISIAH rats strain.

[Differentially expressed genes in the locus associated with relative kidney weight and resting blood pressure in hypertensive rats of the ISIAH strain].

The comparative full-genome sequencing of transcriptomes of the renal cortex and medulla from hypertensive ISIAH rats and normotensive WAG rats revealed the differential expression of genes in the locus of chromosome 11 associated to the traits of resting blood pressure and relative kidney weight. Six differentially expressed genes (Kcne1, Rcan1, Mx1, Mx2, Tmprss2, and RGD1559516) were identified in the renal cortex, and three genes (Rcan1, Mx2, and Tmprss2) were identified in the renal medulla. An analysis of the functions of these genes pointed at the Rcan1 gene as the most relevant candidate gene associated with both the traits of resting blood pressure and relative kidney weight in ISIAH rats. The elevation of the transcription levels of the Mx1 and Mx2 genes in hypertensive ISIAH rats may represent an adaptation that contributes to the alleviation of inflammatory processes in the kidneys.

[SECRETORY ACTIVITY OF ATRIAL CARDIOMYOCYTES IN NORMOTENSIVE AND HYPERTENSIVE RATS DURING STRESS].

The pioneer overall ultrastructural and immune-enzymatic evaluation of the secretory activity of atrial myoendocrine cells in WAG strain (control) and in ISIAH rats with inherited stress induced arterial hypertension has been carried out. It was revealed that under basal conditions the cardiac hormone synthesis, storage and secretion in myoendocrine cells of hypertensive rats were certainly intensified, and the atrial natriuretic peptide (ANP) blood concentration was reliably higher than in normotensive WAG rats. All rats demonstrated the unidirectional reaction during the subchronic restraint stress: the ANP release was depressed, the peptides accumulated in the cardiomyocyte numerous large secretory granules, and ANP blood concentration 6 times decreased, while interline differences preserved. It is concluded that the cardiac natriuretic peptides as a hypotensive chain of the hemodynamic regulation, compensatory response to the development of inherited arterial hypertension and participate in the realization of stress reactions.

[Evolutionary and Genetic Roots of Hypertensive Disease].

This review concerns issues related to the evolutionary and genetic origins of hypertensive disease. An evolutionary approach is used to account for the predisposition of modern people to the development of a pathology such as hypertensive disease. Many studies indicate the importance of "ancestral" alleles, which provided perfect adaptation to the environment and lifestyle of our distant relatives, with respect to the increase in hypertensive disease development among modern individuals.

[MORPHOLOGICAL AND VISCOELASTIC PROPERTIES OF ISIAH RATS MYOCARDIUM DURING THE DEVELOPMENT OF ARTERIAL HYPERTENSION].

The comprehensive study of morphometrical parameters and viscoelastic properties of right ventricle and left ventricle papillary muscles of ISIAH rats during the development of arterial hypertension has been carried out. It is established the significant increase of the index of heart mass to body mass and to tibia length of ISIAH rats in comparison with WAG rats of the same age. There are no any significant differences of "stress-strain" dependences of all experimental groups.

Inhibition of secretory activity of atrial myocytes in hypertensive rats after losartan treatment.

Male ISIAH rats with inherited stress-induced arterial hypertension (BP 174.0 ± 1.3 mm Hg) received antagonist of angiotensin II receptors losartan in a dose of 10 mg/kg/day for 16 days. Ultrastructural study of the right atrium showed signs of dramatic and pronounced inhibition of synthesis of the natriuretic peptides (changes in the composition of secretory granules and decrease in their population density and size) the atrial myocytes against the background of persistent BP decrease in hypertensive rats to 142.0 ± 4.2 mm Hg. We concluded that myoendocrine cells in rats with stable hypertension retain ability to respond adequately to distention of the atria with blood.