Hypothetical mechanism of sodium pump regulation by estradiol under primary hypertension

Calcium signaling in endothelial and vascular smooth muscle cells: sex differences and the influence of estrogens and androgens

Calcium signaling in vascular endothelial cells (ECs) and smooth muscle cells (VSMCs) is essential for the regulation of vascular tone. However, the changes to intracellular Ca2+ concentrations are often influenced by sex differences. Furthermore, a large body of evidence shows that sex hormone imbalance leads to dysregulation of Ca2+ signaling and this is a key factor in the pathogenesis of cardiovascular diseases. In this review, the effects of estrogens and androgens on vascular calcium-handling proteins are discussed, with emphasis on the associated genomic or nongenomic molecular mechanisms. The experimental models from which data were collected were also considered. The review highlights 1) in female ECs, transient receptor potential vanilloid 4 (TRPV4) and mitochondrial Ca2+ uniporter (MCU) enhance Ca2+-dependent nitric oxide (NO) generation. In males, only transient receptor potential canonical 3 (TRPC3) plays a fundamental role in this effect. 2) Female VSMCs have lower cytosolic Ca2+ levels than males due to differences in the activity and expression of stromal interaction molecule 1 (STIM1), calcium release-activated calcium modulator 1 (Orai1), calcium voltage-gated channel subunit-α1C (CaV1.2), Na+-K+-2Cl- symporter (NKCC1), and the Na+/K+-ATPase. 3) When compared with androgens, the influence of estrogens on Ca2+ homeostasis, vascular tone, and incidence of vascular disease is better documented. 4) Many studies use supraphysiological concentrations of sex hormones, which may limit the physiological relevance of outcomes. 5) Sex-dependent differences in Ca2+ signaling mean both sexes ought to be included in experimental design.

Effective substances and mechanism of red ginseng on rats with spleen-deficiency syndrome based on the substance and energy metabolism as well as the "brain-gut" axis

ETHNOPHARMACOLOGICAL RELEVANCE

Red ginseng (RG), a processed product of ginseng (GS), is a generally used qi-tonifying medicine in Traditional Chinese Medicine (TCM). According to the TCM principle, RG is also generally applied to spleen-deficiency syndrome (SDS) clinically for its warmer property. However, the effective substances and mechanism of RG on SDS have not been well investigated.

AIM OF THE STUDY

The aim of this study was to explore the effective substances and their mechanism of RG on SDS.

MATERIALS AND METHODS

The SDS model was established with a compound factor method involving an irregular diet, excessive fatigue and sennae folium with a bitter-cold property. The medicine of RG was split by multi-mode separation methods and analyzed by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS). The appearance indexes such as body weight, body temperature, swimming endurance, urine output, and water content of fecal were determined. The biochemical indexes such as D-xylose, SP, VIP and AChE in the digestive system, CRH, ACTH, CORT, E, T3, T4, T, E2 and 5-HT in the endocrine system, CS, NCR, IDH1, COX and Na⁺-K⁺-ATPase in the metabolism of substance and energy, cAMP and cGMP in the cyclic nucleotide system were analyzed by Enzyme-linked immunosorbent assay (ELISA) kits and biochemical kits. The serum metabolites were analyzed by UPLC-QTOF/MS. Furthermore, the gut microbiota and short-chain fatty acids (SCFAs) in feces were analyzed by 16S rRNA sequencing and headspace gas chromatography-mass method.

RESULTS

The pharmacological experiments showed that total saponin fraction (RGTSF), less polar fraction (RGLPF), and polysaccharides faction (RGPSF) significantly modulated the "brain-gut" axis-related indexes (the levels of VIP, AChE, and 5-HT). Besides, RGTSF also significantly modulated the hypothalamic-pituitary-adrenal (HPA) axis-related indexes as well as the substance and energy metabolism-related indexes (the levels of ACTH, CORT, A, Na⁺-K⁺-ATPase, COX, NCR and CS). RGPSF also significantly modulated the hypothalamus-pituitary-thyroid (HPT) axis-related indexes (the levels of T3 and T4). Secondly, metabolomics indicated that RGTSF could significantly regulate the abnormal metabolic pathways associated with the development of SDS, which involved steroid hormone biosynthesis, taurine and hypotaurine metabolism, primary bile acid biosynthesis, and amino acid metabolism. Subsequently, the study of gut microbiota indicated that RGLPF could increase the diversities of the gut microbiota and the relative abundance of Firmicutes in rats with SDS, while RGWEF significantly increased the relative abundance of Bacteroidetes. At the genus level, RGLPF could increase the relative abundance of Lactobacillus in rats with SDS and decrease that of Akkermansia. Meanwhile, the water-eluted fraction (RGWEF) showed a stronger regulation in SCFAs.

CONCLUSION

It is for the first time that the effective substances of red ginseng on spleen-deficiency syndrome were studied systematically, and the different mechanisms of the RG fractions involved in substance and energy metabolism as well as the "brain-gut" axis were revealed. The present study demonstrated that RGTSF, RGPSF, and RGLPF were the effective substances of red ginseng for ameliorating spleen-deficiency syndrome, indicating that ginsenosides composed of primary and secondary saponins as well as polysaccharides were the main effective substances for red ginseng in ameliorating spleen-deficiency syndrome.

The Na+/K+-ATPase: A potential therapeutic target in cardiometabolic diseases

Cardiometabolic diseases (CMD) are a direct consequence of modern living and contribute to the development of multisystem diseases such as cardiovascular diseases and diabetes mellitus (DM). CMD has reached epidemic proportions worldwide. A sodium pump (Na+/K+-ATPase) is found in most eukaryotic cells' membrane and controls many essential cellular functions directly or indirectly. This ion transporter and its isoforms are important in the pathogenesis of some pathological processes, including CMD. The structure and function of Na+/K+-ATPase, its expression and distribution in tissues, and its interactions with known ligands such as cardiotonic steroids and other suspected endogenous regulators are discussed in this review. In addition, we reviewed recent literature data related to the involvement of Na+/K+-ATPase activity dysfunction in CMD, focusing on the Na+/K+-ATPase as a potential therapeutic target in CMD.

The effect of curculigo orchioides (Xianmao) on kidney energy metabolism and the related mechanism in rats based on metabolomics

The Chinese materia medica Xianmao (XM) is widely used in Chinese clinics and the traditional Chinese medicine diets. Although XM is often used to study its kidney-yang effect, the research on its effect on kidney energy metabolism and its mechanism is still relatively lacking. In this study, rats were given different doses of XM water extract for 4 weeks. Biochemical method was used to detect the content of serum biochemical indexes of liver and kidney function and blood lipid indicators, and HE staining method was used to observe the histopathological of liver and kidney in rats. The kidney Na+-K+-ATPase, Ca2+-Mg2+-ATPase, SDH (succinate dehydrogenase) enzyme activity, and the content of ATP in rats were measured. Metabolomics technology was used to analyze the potential biomarkers related to the effects of XM on kidney energy metabolism, and then, the metabolic pathways were analyzed. RT-PCR was used to detect the expression of Ampk, Sirt1, Ppar-α, and Pgc-1α mRNA in kidney of rats. The results showed, compared with the blank control group, there was no significant effect on liver and kidney function in XMH, XMM, and XML groups. These significantly increased the kidney Na+-K+-ATPase, Ca2+-Mg2+-ATPase, SDH enzyme activity, and ATP content in XMH, XMM, and XML groups. Mitochondrial metabolic rate was inhibited in XMH group, but it was significantly increased in XMM and XML groups. The number of mitochondria was increased in XMH, XMM, and XML groups. Overall, these effects may be mediated by TCA cycle metabolism, butanoate metabolism, propanoate metabolism, alanine, aspartate, and glutamate metabolism, retinol metabolism, purine metabolism, pentose phosphate metabolism, aminoacyl-tRNA biosynthesis, valine, leucine, and isoleucine biosynthesis, and degradation metabolism pathways, as well as by increasing expression of upstream genes Ampk, Sirt1, Ppar-α, and Pgc-1α mRNA.

Involvement of PI3K, Akt and RhoA in Oestradiol Regulation of Cardiac iNOS Expression

BACKGROUND

Oestradiol is an important regulatory factor with several positive effects on the cardiovascular (CV) system. We evaluated the molecular mechanism of the in vivo effects of oestradiol on the regulation of cardiac inducible nitric oxide (NO) synthase (iNOS) expression and activity.

METHODS

Male Wistar rats were treated with oestradiol (40 mg/kg, intraperitoneally) and after 24 h the animals were sacrificed. The concentrations of NO and L-Arginine (L-Arg) were determined spectrophotometrically. For protein expressions of iNOS, p65 subunit of nuclear factor-κB (NFκB-p65), Ras homolog gene family-member A (RhoA), angiotensin II receptor type 1 (AT1R), insulin receptor substrate 1 (IRS-1), p85, p110 and protein kinase B (Akt), Western blot method was used. Coimmunoprecipitation was used for measuring the association of IRS-1 with the p85 subunit of phosphatidylinositol- 3-kinase (PI3K). The expression of iNOS messenger ribonucleic acid (mRNA) was measured with the quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemical analysis of the tissue was used to detect localization and expression of iNOS in heart tissue.

RESULTS

Oestradiol treatment reduced L-Arg concentration (p<0.01), iNOS mRNA (p<0.01) and protein (p<0.001) expression, level of RhoA (p<0.05) and AT1R (p<0.001) protein. In contrast, plasma NO (p<0.05), Akt phosphorylation at Thr308 (p<0.05) and protein level of p85 (p<0.001) increased after oestradiol treatment.

CONCLUSION

Our results suggest that oestradiol in vivo regulates cardiac iNOS expression via the PI3K/Akt signaling pathway, through attenuation of RhoA and AT1R.

Changes in cardiac Na+/K+-ATPase expression and activity in female rats fed a high-fat diet

The aim of this study was to investigate whether the presence of endogenous estradiol alters the effects of a high-fat (HF) diet on activity/expression of the cardiac Na⁺/K⁺-ATPase, via PI3K/IRS and RhoA/ROCK signalling cascades in female rats. For this study, female Wistar rats (8 weeks old, 150-200 g) were fed a standard diet or a HF diet (balanced diet for laboratory rats enriched with 42% fat) for 10 weeks. The results show that rats fed a HF diet exhibited a decrease in phosphorylation of the α₁ subunit of Na⁺/K⁺-ATPase by 30% (p < 0.05), expression of total α₁ subunit of Na⁺/K⁺-ATPase by 31% (p < 0.05), and association of IRS1 with p85 subunit of PI3K by 42% (p < 0.05), while the levels of cardiac RhoA and ROCK2 were significantly increased by 84% (p < 0.01) and 62% (p < 0.05), respectively. Our results suggest that a HF diet alters cardiac Na⁺/K⁺-ATPase expression via molecular mechanisms involving RhoA/ROCK and IRS-1/PI3K signalling in female rats.

The water extract of Veratrilla baillonii could attenuate the subacute toxicity induced by Aconitum brachypodum

BACKGROUND

Aconitum brachypodum Diels (Family Ranunculaceae) is a Chinese ethnodrug and is well known for both its therapeutic application and high toxicity. However, no detoxication strategy is available for the complete elimination of the toxicity of Aconitum plants. Veratrilla baillonii Franch is believed to possess antitoxic effects on the toxicity induced by Aconitum plants and has been clinically used for hundreds of time by Naxi and Lisu nationalities in Yunnan Province of China. To further address the mechanism of the detoxication of Veratrilla baillonii, the effect of water decoction of Veratrilla baillonii (WVBF) on subacute toxicology of SD rats induced by Aconitum brachypodum (CFA), a genus Aconitum, was determined and studied in the present work.

METHODS

The clinical behavior and number of survivors for different dosage of WVBF (25, 50, 100mg/kg) on CFA (4mg/kg) induced rats were observed until day 28. Histological changes and haematological parameters were evaluated. Moreover, Na⁺-K⁺-ATPase pathway in heart as well as key enzymes in liver were determined to further discuss the mechanism.

RESULTS

The results showed that the exposure of CFA led to some subacute toxicity to rats, especially male ones, accompanied with abnormality of serum biochemical index in rats' serum. The toxicological target organs of CFA may be the heart, liver, kidney and brain. It is demonstrated that WVBF could attenuate the toxicity induced by Aconitum brachypodum via promoting the metabolic enzymes CYP3A1 and CYP3A2 in liver, downregulating the expression of Sodium/Calcium exchanger 1 (NCX1) and SCN5A sodium channal mRNA, and inducing Na⁺/K⁺-ATPase activity in heart. This study provides insights into detoxifying measures of Aconitum plants.

CONCLUSIONS

Aconitum brachypodum may lead to subacute toxicity of rats after long term of administration, and the toxicity could be attenuated by Veratrilla baillonii via promoting the metabolic enzymes in liver, downregulating the expression of NCX1 and SCN5A mRNA, and inducing Na⁺/K⁺-ATPase activity in heart.

The ginseng's fireness is associated with the lowering activity of liver Na(+)-K(+)-ATPase

ETHNOPHARMACOLOGICAL RELEVANCE

Ginseng is an herbal medicine used worldwide that possesses a wide range of pharmacological activities. However, its side effects are rarely discussed. The experience of Chinese medicine has revealed that taking ginseng at a high dose chronically can cause fireness, i.e., the ginseng-abuse syndrome. Here, we explored the mechanism of ginseng's fireness by comparing the energy metabolism of mice affected by red ginseng (RG), ginseng (GS), ginseng leaves (GL) and American ginseng (AG), which exhibit different drug properties according to the theory of TCM.

MATERIALS AND METHODS

KM mice were randomly divided into five groups (n≥30 per group) and administered distilled water or drugs, respectively. Mice receiving RG, GS, or GL received 4.5g/(kgday), while the mice receiving AG received 3g/(kgday). Control mice received distilled water. The duration of exposure for all groups was 31 days. The mice's physical characteristics, such as eye condition, rectal temperature, saliva secretion, urine, stool weight, blood coagulation time and swimming time, were measured at different times after administration. Energy metabolism indexes were measured via TSE phenoMaster/LabMaster animal monitoring system, including the mice' 24h oxygen consumption (VO2), carbon dioxide production (VCO2), heat production (H) and energy expenditure (EE). Biochemical indices were measured by ultraviolet spectrophotometer and microplate reader, including pyruvic acid content in serum and succinate dehydrogenase (SDH) activity, lactate dehydrogenase (LDH) activity, the Na(+)-K(+)-ATPase activity and the content of glycogen in the liver tissue.

RESULTS

After 31 days of drug administration, mice in the RG and GS groups exhibited obviously more eye secretions, less saliva secretion and less urine. Compared with the control group, the swimming times of mice in the GS, AG and GL groups were significantly prolonged; the clotting time of mice in the GL was extended significantly; VCO2, H and EE of mice in the GS group were obviously increased; Pyruvate content of mice in the RG group showed an initial decrease followed by an increase; SDH activity of mice in the AG and GL groups was significantly inhibited; LDH activity of the mice showed no significant difference among different groups; Na(+)-K(+)-ATP enzyme activity of the RG and GS groups showed up-regulation initially and then down-regulation; the content of hepatic glycogen of mice in the GS and GL groups increased significantly.

CONCLUSION

The results demonstrated that RG and GS with their warm drug nature could enhance the body's energy metabolism to produce their dryness to the body. The liver Na(+)-K(+)-ATP enzyme activity may be the primary index for indicating the fireness of ginseng. In addition, our results demonstrated that ginseng, especially red ginseng, is not suitable for long time application with a higher dose.

Effects of 17β-estradiol on cardiac Na(+)/K(+)-ATPase in high fat diet fed rats

The aim of this study was to investigate in vivo effects of estradiol on Na(+)/K(+)-ATPase activity/expression in high fat (HF) diet fed rats. Adult male Wistar rats were fed normally (Control, n = 7) or with a HF diet (Obese, n = 14) for 10 weeks. After 10 weeks, half of the obese rats were treated with estradiol (Obese + Estradiol, n = 7, 40 μg/kg, i.p.) as a bolus injection and 24 h after treatment all the rats were sacrificed. Estradiol in vivo in obese rats in comparison with obese non-treated rats led to a statistically significant increase in concentration of serum Na(+) (p < 0.05), Na(+)/K(+)-ATPase activity (p < 0.01), expression of α1 (p < 0.01) and α2 (p < 0.05) subunit of Na(+)/K(+)-ATPase, both PI3K subunits p85 (p < 0.01), p110 (p < 0.05), and association of IRS-1 with p85 (p < 0.05), while significantly decrease expression of AT1 (p < 0.05) and Rho A (p < 0.01) proteins. Our results suggest that estradiol in vivo in pathophysiological conditions, such as obesity accompanied with insulin resistance stimulates activity and expression of Na(+)/K(+)-ATPase by a mechanism that involves the participation of IRS-1/PI3K/Akt signaling. In addition, the decreasing level of AT1 and Rho A proteins estradiol probably attenuates the detrimental effect of obesity to decreased IRS-1/PI3K association and consequently reduce Na(+)/K(+)-ATPase activity/expression.

Mitochondria DNA mutations cause sex-dependent development of hypertension and alterations in cardiovascular function

Aging is associated with conduit artery stiffening that is a risk factor for and can precede hypertension and ventricular dysfunction. Increases in mitochondria DNA (mtDNA) frequency have been correlated with aging. Mice with a mutation in the encoding domain (D257A) of a proof-reading deficient version of mtDNA polymerase-γ (POLG) have musculoskeletal features of premature aging and a shortened lifespan. However, few studies using these mice have investigated the effects of mtDNA mutations on cardiovascular function. We hypothesized that the proof-reading deficient mtDNA POLG leads to arterial stiffening, hypertension, and ventricular hypertrophy. Ten to twelve month-old D257A mice (n=13) and age- and sex-matched wild-type controls (n=13) were catheterized for hemodynamic and ventricular function measurements. Left common carotid arteries (LCCA) were harvested for mechanical tests followed by histology. Male D257A mice had pulmonary and systemic hypertension, arterial stiffening, larger LCCA diameter (701±45 vs. 597±60μm), shorter LCCA axial length (8.96±0.56 vs. 10.10±0.80mm), and reduced hematocrit (29.1±6.1 vs. 41.3±8.1; all p<0.05). Male and female D257A mice had biventricular hypertrophy (p<0.05). Female D257A mice did not have significant increases in pressure or arterial stiffening, suggesting that the mechanisms of hypertension or arterial stiffening from mtDNA mutations differ based on sex. Our results lend insight into the mechanisms of age-related cardiovascular disease and may point to novel treatment strategies to address cardiovascular mortality in the elderly.

In vivo effects of 17β-estradiol on cardiac Na(+)/K(+)-ATPase expression and activity in rat heart

In this study the in vivo effects of estradiol in regulating Na(+)/K(+)-ATPase function in rat heart was studied. Adult male Wistar rats were treated with estradiol (40μg/kg, i.p.) and after 24h the animals were sacrificed and the heart excised. Following estradiol administration, cardiac Na(+)/K(+)-ATPase activity, expression of the α1 subunit, and phosphorylation of the α1 subunit were significantly increased. These animals also had significantly decreased levels of digoxin-like immunoreactive factor(s). Na(+) levels were also significantly reduced but to a level that was still within the normal physiological range, highlighting the ability of the Na(+)/K(+)-ATPase to balance the ionic composition following treatment with estradiol. Estradiol treated rats also showed increased phosphorylation of protein kinase B (Akt), and extracellular-signal-regulated kinase 1/2 (ERK1/2). We therefore suggest a role for Akt and/or ERK1/2 in estradiol-mediated regulation of cardiac Na(+)/K(+)-ATPase expression and activity in rat heart.

Estradiol In Vivo Induces Changes in Cardiomyocytes Size in Obese Rats

We studied the in vivo effects of estradiol on size and biochemical parameters of cardiomyocytes in pathophysiological conditions such as obesity and insulin resistance. Male Wistar rats were normally fed (controls, n = 7) or fed with high-fat diet (obese, n = 14). Half of the obese rats (obese + estradiol, n = 7) were treated with a single dose of estradiol (40 μg/kg, intraperitoneally) and 24 hours after treatment all the rats were killed. Estradiol in vivo in obese rats resulted in a significant increase in protein kinase B (Akt) activation ( P < .05) and decrease in heart mass ( P < .05), ratio of the heart mass/body mass ( P < .05), transverse diameters of cardiomyocytes ( P < .001), concentration of serum high-sensitivity C-reactive protein ( P < .001), and total cholesterol ( P < .01) compared with obese nontreated rats. Our results suggest that estradiol in obese/IR rats affects the size of cardiomyocytes and its actions lead in vivo to a reduction in obesity-induced cardiac hypertrophy, via Akt.

Effects of obesity and estradiol on Na+/K+-ATPase and their relevance to cardiovascular diseases

Obesity is associated with aberrant sodium/potassium-ATPase (Na(+)/K(+)-ATPase) activity, apparently linked to hyperglycemic hyperinsulinemia, which may repress or inactivate the enzyme. The reduction of Na(+)/K(+)-ATPase activity in cardiac tissue induces myocyte death and cardiac dysfunction, leading to the development of myocardial dilation in animal models; this has also been documented in patients with heart failure (HF). During several pathological situations (cardiac insufficiency and HF) and in experimental models (obesity), the heart becomes more sensitive to the effect of cardiac glycosides, due to a decrease in Na(+)/K(+)-ATPase levels. The primary female sex steroid estradiol has long been recognized to be important in a wide variety of physiological processes. Numerous studies, including ours, have shown that estradiol is one of the major factors controlling the activity and expression of Na(+)/K(+)-ATPase in the cardiovascular (CV) system. However, the effects of estradiol on Na(+)/K(+)-ATPase in both normal and pathological conditions, such as obesity, remain unclear. Increasing our understanding of the molecular mechanisms by which estradiol mediates its effects on Na(+)/K(+)-ATPase function may help to develop new strategies for the treatment of CV diseases. Herein, we discuss the latest data from animal and clinical studies that have examined how pathophysiological conditions such as obesity and the action of estradiol regulate Na(+)/K(+)-ATPase activity.

Regulation of Inducible Nitric Oxide Synthase (iNOS) and its Potential Role in Insulin Resistance, Diabetes and Heart Failure

Nitric oxide synthases (NOS) are the enzymes responsible for nitric oxide (NO) generation. NO is a reactive oxygen species as well as a reactive nitrogen species. It is a free radical which mediates several biological effects. It is clear that the generation and actions of NO under physiological and pathophysiological conditions are regulated and extend to almost every cell type and function within the circulation. In mammals 3 distinct isoforms of NOS have been identified: neuronal NOS (nNOS), inducible NOS (iNOS) and endothelial NOS (eNOS). The important isoform in the regulation of insulin resistance (IR) is iNOS. Understanding the molecular mechanisms regulating the iNOS pathway in normal and hyperglycemic conditions would help to explain some of vascular abnormalities observed in type 2 diabetes mellitus (T2DM). Previous studies have reported increased myocardial iNOS activity and expression in heart failure (HF). This review considers the recent animal studies which focus on the understanding of regulation of iNOS activity/expression and the role of iNOS agonists as potential therapeutic agents in treatment of IR, T2DM and HF.