Spontaneously Hypertensive Rats Research Articles

Long-term intake of corn gluten meal protein hydrolysate attenuated hypertension development and modulated associated plasma metabolite levels in spontaneously hypertensive rats

This study evaluated the long-term antihypertensive effect of corn gluten meal protein hydrolysate (CGM-H) on spontaneously hypertensive rats (SHRs). Plausible pathways governing blood pressure were also evaluated based on untargeted metabolomic analysis. The casein diet containing 1 % of CGM-H and peptides obtained from ultrafiltration membranes attenuated the development of hypertension in SHRs after a 6-week oral administration with similar efficacy, while the control group showed progressive hypertension. Plasma renin and angiotensin converting enzyme (ACE) activity and total peroxides level of the corn peptides-treated groups decreased when compared with the control (p < 0.05). In addition, the corn peptides up-regulated antihypertensive metabolites such as prostaglandin K2 and 11-ketotestosterone, while corticosterone, biotin, and plasma fatty acids were down-regulated. This study demonstrates that corn peptides did not only inhibit ACE and renin activities, but also modulated the biosynthesis and metabolisms of fatty acids, sex hormones, and aldosterone, which would have contributed to attenuation of hypertension.

2-(4-Methylthiazol-5-yl) Ethyl Nitrate Hydrochloride Ameliorates Cognitive Impairment via Modulation of Oxidative Stress and Nuclear Factor Kappa B (NF-κB) Signaling Pathway in Chronic Cerebral Hypoperfusion-Associated Spontaneously Hypertensive Rats

Hypertension reduces the bioavailability of vascular nitric oxide (NO) and contributes to the onset of vascular dementia (VaD). A loss of NO bioavailability increases inflammation and oxidative stress. 2-(4-Methylthiazol-5-yl) ethyl nitrate hydrochloride (W1302) is a novel nitric oxide donor (NOD) which is undergoing phase I clinical trials in China for the treatment of VaD. In this study, we investigated the protective effects of W1302 in VaD rats induced by the permanent occlusion of a bilateral common carotid arteries model related to spontaneous hypertension (SHR-2VO), and we further explored the underlying mechanisms. Nimodipine was used as a positive control. Our results showed that W1302 treatment for 4 weeks (10 mg/Kg/day) exhibited stronger improvement in the spatial learning and memory deficits in SHR-2VO rats compared with nimodipine with slightly lower systolic blood pressure (SBP). Meanwhile, W1302 treatment significantly increased NO and cGMP production, restored mitochondrial membrane potential and attenuated oxidative stress as evidenced by increasing ATP production and reducing malondialdehyde (MDA) levels in the brain. Furthermore, W1302 treatment markedly inhibited the iNOS activity and decreased TNF-α expression via inhibiting the nuclear factor kappa B (NF-κB) signaling pathway. Nimodipine treatment also restored these aberrant changes, but its ATP production was weaker than that of W1302, and there was no significant effect on NO release. Taken together, W1302 exhibited beneficial effects on complications in VaD with hypertension, which is involved in suppressing oxidative damage, and the inflammatory reaction might be mediated by an increase in NO release. Therefore, W1302 has therapeutic potential for the treatment of VaD caused by chronic cerebral hypoperfusion-associated spontaneous hypertension.

Hemodynamic Parameters in Spontaneously Hypertensive Rats with Obesity and Chemically Induced Colitis during Probiotic Therapy.

We studied the dynamics of the main hemodynamic parameters in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats with visceral obesity and chemically induced colitis (CIC) against the background of probiotic therapy. Systolic BP, HR, and body temperature were recorded over 36 days using a wireless telemetry system. During 8 days (3 days before CIC induction and until the end of the experiment) the animals were intragastrically administered a probiotic based on Lactobacillus delbrueckii D5 strain. At baseline, systolic BP was significantly higher in the SHR group, while HR and body temperature did not differ in SHR and WKY rats. On day 8 after CIC induction, systolic BP, HR, and body temperature in SHR were significantly increased in comparison with the initial values. In the group of WKY rats, all indices at the end of the experiment remained at the initial levels. Probiotic therapy in SHR, in contrast to WKY rats, did not lead to normalization of body temperature and hemodynamic disorders resulting from CIC.

Novel Blood Pressure-Lowering Effect of Spathulenol in Rats

In recent years, natural compounds from plant sources are sought after as alternative anti-hypertensive treatments. Spathulenol (Spa), a terpenoid plant metabolite obtained mainly from the Origanum species has shown anecdotal evidence of blood pressure (BP)-lowering properties probably through the effects on vasoreactivity. This study aimed to investigate the BP-lowering activities of Spa in vivo as well as to ascertain the mechanisms of action in vitro. Male Sprague-Dawley (SD) rats (n=16) and spontaneously hypertensive rats (SHR) (n=16) with their normotensive Wistar-Kyoto (WKY) rats (n=16) as controls were subjected to anaesthesia and administered intravenous boluses of Spa at 0.0, 0.045, 0.90, 0.18, 0.36, and 0.7 mg/kg or positive control losartan at 0.0, 0.6, 1.2, 1.8, 2.4 and 3.0 mg/kg. The BP and heart rate (HR) of the rats were recorded by a computerised physiographical system (Power Lab) through carotid arterial cannulation that was connected to a pressure transducer. The data were analysed by using the Lab Chart 6 software. Spathulenol was also tested for angiotensin-converting enzyme (ACE) inhibitory activity by using the ACE1 inhibitor screening kit (PromoKine). Spathulenol was able to decrease the BP of rats in a dose-dependent manner with the BP-lowering effect being significantly (p &lt; 0.05) higher in the SHRs than in the WKY controls. Furthermore, Spa was able to inhibit the ACE activity suggesting the possibility that this could be one of the mechanisms underlying the observed BP-lowering effect.

Antihypertensive treatment during pregnancy induces long-term changes in gut microbiota and the behaviors of the attention deficit hyperactivity disorder offspring

The pathogenesis of attention-deficit/hyperactivity disorder (ADHD) has not been fully elucidated. Gestational hypertension could double the probability of ADHD in the offspring, while the initial bacterial communication between the mother and offspring has been associated with psychiatric disorders. Thus, we hypothesize that antihypertensive treatment during pregnancy may abate the impairments in neurodevelopment of the offspring. To test this hypothesis, we chose Captopril and Labetalol, to apply to pregnant spontaneously hypertensive rat (SHR) dams and examined the outcomes in the male offspring. Our data demonstrated that maternal treatment with Captopril and Labetalol had long-lasting changes in gut microbiota and behavioral alterations, including decreased hyperactivity and increased curiosity, spatial learning and memory in the male offspring. Increased diversity and composition were identified, and some ADHD related bacteria were found to have the same change in the gut microbiota of both the dam and offspring after the treatments. LC-MS/MS and immunohistochemistry assays suggested elevated expression of brain derived neurotrophic factor (BDNF) and dopamine in the prefrontal cortex and striatum of offspring exposed to Captopril/ Labetalol, which may account for the improvement of the offspring's psychiatric functions. Therefore, our results support the beneficial long-term effects of the intervention of gestational hypertension in the prevention of ADHD.

Cholinergic Stimulation Exerts Cardioprotective Effects and Alleviates Renal Inflammatory Responses after Acute Myocardial Infarction in Spontaneous Hypertensive Rats (SHRs)

Background: In this investigation, we explored the effects of pharmacological cholinergic stimulation on cardiac function and renal inflammation following acute myocardial infarction (AMI) in spontaneously hypertensive rats (SHRs). Methods: Adult male SHRs were randomized into three experimental groups: sham-operated; AMI + Veh (infarcted, treated with vehicle); and AMI + PY (infarcted, treated with the cholinesterase inhibitor, pyridostigmine bromide (PY)—40 mg/kg, once daily for seven days). Rats were euthanized 7 or 30 days post-surgery. The clinical parameters were assessed on the day before euthanasia. Subsequent to euthanasia, blood samples were collected and renal tissues were harvested for histological and gene expression analyses aimed to evaluate inflammation and injury. Results: Seven days post-surgery, the AMI + PY group demonstrated improvements in left ventricular diastolic function and autonomic regulation, and a reduction in renal macrophage infiltration compared to the AMI + Veh group. Furthermore, there was a notable downregulation in pro-inflammatory gene expression and an upregulation in anti-inflammatory gene expression. Analysis 30 days post-surgery showed that PY treatment had a sustained positive effect on renal gene expression, correlated with a decrease in biomarkers, indicative of subclinical kidney injury. Conclusions: Short-term cholinergic stimulation with PY provides both cardiac and renal protection by mitigating the inflammatory response after AMI.

Asprosin contributes to vascular remodeling in hypertensive rats via superoxide signaling.

Proliferation and migration of vascular smooth muscle cells (VSMCs) contribute to vascular remodeling. Asprosin, a newly discovered protein hormone, is involved in metabolic diseases. Little is known about the roles of asprosin in cardiovascular diseases. This study focused on the role and mechanism of asprosin on VSMC proliferation and migration, and vascular remodeling in a rat model of hypertension. VSMCs were obtained from the aortic media of 8-week-old male Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). Asprosin was upregulated in the VSMCs of SHR. For in vitro studies, asprosin promoted VSMC proliferation and migration of WKY and SHR, and increased Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) activity, NOX1/2/4 protein expressions and superoxide production. Knockdown of asprosin inhibited the proliferation, migration, NOX activity, NOX1/2 expressions and superoxide production in the VSMCs of SHR. The roles of asprosin in promoting VSMC proliferation and migration were not affected by hydrogen peroxide scavenger, but attenuated by superoxide scavenger, selective NOX1 or NOX2 inhibitor. Toll-like receptor 4 (TLR4) was upregulated in SHR, TLR4 knockdown inhibited asprosin overexpression-induced proliferation, migration and oxidative stress in VSMCs of WKY and SHR. Asprosin was upregulated in arteries of SHR, and knockdown of asprosin in vivo not only attenuated oxidative stress and vascular remodeling in aorta and mesentery artery, but also caused a subsequent persistent antihypertensive effect in SHR. Asprosin promotes VSMC proliferation and migration via NOX-mediated superoxide production. Inhibition of endogenous asprosin expression attenuates VSMC proliferation and migration, and vascular remodeling of SHR.

Microbiota-derived acetate attenuates neuroinflammation in rostral ventrolateral medulla of spontaneously hypertensive rats.

Increased neuroinflammation in brain regions regulating sympathetic nerves is associated with hypertension. Emerging evidence from both human and animal studies suggests a link between hypertension and gut microbiota, as well as microbiota-derived metabolites short-chain fatty acids (SCFAs). However, the precise mechanisms underlying this gut-brain axis remain unclear. The levels of microbiota-derived SCFAs in spontaneously hypertensive rats (SHRs) were determined by gas chromatography-mass spectrometry. To observe the effect of acetate on arterial blood pressure (ABP) in rats, sodium acetate was supplemented via drinking water for continuous 7 days. ABP was recorded by radio telemetry. The inflammatory factors, morphology of microglia and astrocytes in rostral ventrolateral medulla (RVLM) were detected. In addition, blood-brain barrier (BBB) permeability, composition and metabolomics of the gut microbiome, and intestinal pathological manifestations were also measured. The serum acetate levels in SHRs are lower than in normotensive control rats. Supplementation with acetate reduces ABP, inhibits sympathetic nerve activity in SHRs. Furthermore, acetate suppresses RVLM neuroinflammation in SHRs, increases microglia and astrocyte morphologic complexity, decreases BBB permeability, modulates intestinal flora, increases fecal flora metabolites, and inhibits intestinal fibrosis. Microbiota-derived acetate exerts antihypertensive effects by modulating microglia and astrocytes and inhibiting neuroinflammation and sympathetic output.

Transgenic human C-reactive protein affects oxidative stress but not inflammation biomarkers in the aorta of spontaneously hypertensive rats

BackgroundC-reactive protein (CRP) is an acute inflammatory protein detected in obese patients with metabolic syndrome. Moreover, increased CRP levels have been linked with atherosclerotic disease, congestive heart failure, and ischemic heart disease, suggesting that it is not only a biomarker but also plays an active role in the pathophysiology of cardiovascular diseases. Since endothelial dysfunction plays an essential role in various cardiovascular pathologies and is characterized by increased expression of cell adhesion molecules and inflammatory markers, we aimed to detect specific markers of endothelial dysfunction, inflammation, and oxidative stress in spontaneously hypertensive rats (SHR) expressing human CRP. This model is genetically predisposed to the development of the metabolic syndrome.MethodsTransgenic SHR male rats (SHR-CRP) and non-transgenic SHR (SHR) at the age of 8 months were used. Metabolic profile (including serum and tissue triglyceride (TAG), serum insulin concentrations, insulin-stimulated incorporation of glucose, and serum non-esterified fatty acids (NEFA) levels) was measured. In addition, human serum CRP, MCP-1 (monocyte chemoattractant protein-1), and adiponectin were evaluated by means of ELISA, histological analysis was used to study morphological changes in the aorta, and western blot analysis of aortic tissue was performed to detect expression of endothelial, inflammatory, and oxidative stress markers.ResultsThe presence of human CRP was associated with significantly decreased insulin-stimulated glycogenesis in skeletal muscle, increased muscle and hepatic accumulation of TAG and decreased plasmatic cGMP concentrations, reduced adiponectin levels, and increased monocyte chemoattractant protein-1 (MCP-1) levels in the blood, suggesting pro-inflammatory and presence of multiple features of metabolic syndrome in SHR-CRP animals. Histological analysis of aortic sections did not reveal any visible morphological changes in animals from both SHR and SHR-CRP rats. Western blot analysis of the expression of proteins related to the proper function of endothelium demonstrated significant differences in the expression of p-eNOS/eNOS in the aorta, although endoglin (ENG) protein expression remained unaffected. In addition, the presence of human CRP in SHR in this study did not affect the expression of inflammatory markers, namely p-NFkB, P-selectin, and COX2 in the aorta. On the other hand, biomarkers related to oxidative stress, such as HO-1 and SOD3, were significantly changed, indicating the induction of oxidative stress.ConclusionsOur findings demonstrate that CRP alone cannot fully induce the expression of endothelial dysfunction biomarkers, suggesting other risk factors of cardiovascular disorders are necessary to be involved to induce endothelial dysfunction with CRP.

Exercise-induced cardiac mitochondrial reorganization and enhancement in spontaneously hypertensive rats.

The myocardium is a highly oxidative tissue in which mitochondria are essential to supply the energy required to maintain pump function. When pathological hypertrophy develops, energy consumption augments and jeopardizes mitochondrial capacity. We explored the cardiac consequences of chronic swimming training, focusing on the mitochondrial network, in spontaneously hypertensive rats (SHR). Male adult SHR were randomized to sedentary or trained (T: 8-week swimming protocol). Blood pressure and echocardiograms were recorded, and hearts were removed at the end of the training period to perform molecular, imaging, or isolated mitochondria studies. Swimming improved cardiac midventricular shortening and decreased the pathological hypertrophic marker atrial natriuretic peptide. Oxidative stress was reduced, and even more interesting, mitochondrial spatial distribution, dynamics, function, and ATP were significantly improved in the myocardium of T rats. In the signaling pathway triggered by training, we detected an increase in the phosphorylation level of both AKT and glycogen synthase kinase-3 β, key downstream targets of insulin-like growth factor 1 signaling that are crucially involved in mitochondria biogenesis and integrity. Aerobic exercise training emerges as an effective approach to improve pathological cardiac hypertrophy and bioenergetics in hypertension-induced cardiac hypertrophy.

Mechanism and functional substances of Saiga antelope horn in treating hypertension with liver-yang hyperactivity syndrome explored using network pharmacology and metabolomics

Ethnopharmacological relevanceSaiga antelope horn (SAH) is a traditional Chinese medicine for treating hypertension with liver-yang hyperactivity syndrome (Gan-Yang-Shang-Kang, GYSK), that has a long history of clinical application and precise efficacy, but its mechanism and functional substances are still unknown. Based on the demand for alternative research on the rare and endangered SAH, the group designed and carried out the following studies. Aim of the studyThe purpose of this research was to demonstrate the functional substances and mechanisms of SAH in the treatment of GYSK hypertension. Materials and methodsThe GYSK-SHR model was constructed by administering a decoction of aconite to spontaneously hypertensive rats (SHRs). Blood pressure (BP), behavioural tests related to GYSK, and pathological changes in the kidneys, heart and aorta were measured to investigate the effects of SAH on GYSK-SHRs. Proteomic analysis was used to identify the keratins and peptides of SAH. Moreover, network pharmacology and plasma metabolomics studies were carried out to reveal the mechanisms by which functional peptides in SAH regulate GYSK-hypertension. ResultsSAH has a significant antihypertensive effect on GYSK hypertensive animals. It has also been proven to be effective in protecting the function and structural integrity of the kidneys, heart and aorta. Moreover, SAH improved the abnormalities of 31 plasma biomarkers in rats. By constructing a “biomarker-target-peptide” network, 10 functional peptides and two key targets were screened for antihypertensive effects of SAH. The results indicated that SAH may exert a therapeutic effect by re-establishing the imbalance of renin-angiotensin (RAS) system. ConclusionsFunctional peptides from keratin contained in SAH are the main material basis for the treatment of GYSK-hypertension and exhibited the protective effect on the GYSK-SHR model through the RAS system.

Spontaneously hypertensive rats exhibit increased liver flavin monooxygenase expression and elevated plasma TMAO levels compared to normotensive and Ang II-dependent hypertensive rats.

Background: Flavin monooxygenases (FMOs) are enzymes responsible for the oxidation of a broad spectrum of exogenous and endogenous amines. There is increasing evidence that trimethylamine (TMA), a compound produced by gut bacteria and also recognized as an industrial pollutant, contributes to cardiovascular diseases. FMOs convert TMA into trimethylamine oxide (TMAO), which is an emerging marker of cardiovascular risk. This study hypothesized that blood pressure phenotypes in rats might be associated with variations in the expression of FMOs. Methods: The expression of FMO1, FMO3, and FMO5 was evaluated in the kidneys, liver, lungs, small intestine, and large intestine of normotensive male Wistar-Kyoto rats (WKY) and two distinct hypertensive rat models: spontaneously hypertensive rats (SHRs) and WKY rats with angiotensin II-induced hypertension (WKY-ANG). Plasma concentrations of TMA and TMAO were measured at baseline and after intravenous administration of TMA using liquid chromatography-mass spectrometry (LC-MS). Results: We found that the expression of FMOs in WKY, SHR, and WKY-ANG rats was in the descending order of FMO3 > FMO1 >> FMO5. The highest expression of FMOs was observed in the liver. Notably, SHRs exhibited a significantly elevated expression of FMO3 in the liver compared to WKY and WKY-ANG rats. Additionally, the plasma TMAO/TMA ratio was significantly higher in SHRs than in WKY rats. Conclusion: SHRs demonstrate enhanced expression of FMO3 and a higher plasma TMAO/TMA ratio. The variability in the expression of FMOs and the metabolism of amines might contribute to the hypertensive phenotype observed in SHRs.

Calcium-sensing receptor-mediated macrophage polarization improves myocardial remodeling in spontaneously hypertensive rats.

Chronic inflammation is a key element in the progression of essential hypertension (EH). Calcium plays a key role in inflammation, so its receptor, the calcium-sensing receptor (CaSR), is an essential mediator of the inflammatory process. Compelling evidence suggests that CaSR mediates inflammation in tissues and immune cells, where it mediates their activity and chemotaxis. Macrophages (Mφs) play a major role in the inflammatory response process. This study provided convincing evidence that R568, a positive regulator of CaSR, was effective in lowering blood pressure in spontaneously hypertensive rats (SHRs), improving cardiac function by alleviating cardiac hypertrophy and fibrosis. R568 can increase the content of CaSR and M2 macrophages (M2Mφs, exert an anti-inflammatory effect) in myocardial tissue, reduce M1 macrophages (M1Mφs), which have a pro-inflammatory effect in this process. In contrast, NPS2143, a negative state regulator of CaSR, exerted the opposite effect in all of the above experiments. Following this study, R568 increased CaSR content in SHR myocardial tissue, lowered blood pressure, promoted macrophages to M2Mφs and improved myocardial fibrosis, but interestingly, both M1Mφs and M2Mφs were increased in the peritoneal cavity of SHRs, the number of M2Mφs remained lower than M1Mφs. In vitro, R568 increased CaSR content in RAW264.7 cells (a macrophage cell line), regulating intracellular Ca2+ ([Ca2+]i) inhibited NOD-like receptor family protein 3 (NLRP3) inflammasome activation and ultimately prevented its conversion to M1Mφs. The results showed that a decrease in CaSR in hypertensive rats causes further development of hypertension and cardiac damage. EH myocardial remodeling can be improved by CaSR overexpression by suppressing NLRP3 inflammasome activation and macrophage polarization toward M1Mφs and increasing M2Mφs.

Hepatoprotective and cardioprotective effects of empagliflozin in spontaneously hypertensive rats fed a high-fat diet

A combination of liver and heart dysfunction worsens the prognosis of human survival. The aim of this study was to investigate whether empagliflozin (a sodium-glucose transporter-2 inhibitor) has beneficial effects not only on cardiac and renal function but also on hepatic function. Adult (6-month-old) male spontaneously hypertensive rats (SHR) were fed a high-fat diet (60% fat) for four months to induce hepatic steatosis and mild heart failure. For the last two months, the rats were treated with empagliflozin (empa, 10 mg.kg-1.day-1 in the drinking water). Renal function and oral glucose tolerance test were analyzed in control (n=8), high-fat diet (SHR+HF, n=10), and empagliflozin-treated (SHR+HF+empa, n=9) SHR throughout the study. Metabolic parameters and echocardiography were evaluated at the end of the experiment. High-fat diet feeding increased body weight and visceral adiposity, liver triglyceride and cholesterol concentrations, and worsened glucose tolerance. Although the high-fat diet did not affect renal function, it significantly worsened cardiac function in a subset of SHR rats. Empagliflozin reduced body weight gain but not visceral fat deposition. It also improved glucose sensitivity and several metabolic parameters (plasma insulin, uric acid, and HDL cholesterol). In the liver, empagliflozin reduced ectopic lipid accumulation, lipoperoxidation, inflammation and pro-inflammatory HETEs, while increasing anti-inflammatory EETs. In addition, empagliflozin improved cardiac function (systolic, diastolic and pumping) independent of blood pressure. The results of our study suggest that hepatoprotection plays a decisive role in the beneficial effects of empagliflozin in preventing the progression of cardiac dysfunction induced by high-fat diet feeding.

High-Density Lipoprotein Signaling via Sphingosine-1-Phosphate Receptors Safeguards Spontaneously Hypertensive Rats against Myocardial Ischemia/Reperfusion Injury.

High-density lipoprotein (HDL) protects against ischemia/reperfusion (I/R) injury via signaling through scavenger-receptor class B type-I (SR-BI) and sphingosine-1-phosphate receptors (S1PRs). We recently reported that HDL protects the hearts of spontaneously hypertensive rats (SHRs) against I/R injury in an SR-BI-dependent manner. In this study, we examined the role of S1PRs in HDL-induced protection against myocardial I/R injury in hypertensive rats. Hearts from Wistar Kyoto rats (WKYs) and SHRs were subjected to I/R injury using a modified Langendorff system. The hearts were treated with or without HDL in the presence or absence of a receptor- or kinase-specific antagonist. Cardiac hemodynamics and infarct size were measured. Target proteins were analyzed by immunoblotting and ELISA, and nitrite levels were measured using Greis reagent. HDL protected the hearts of WKYs and SHRs against I/R injury. HDL, however, was more protective in WKYs. HDL protection in SHRs required lipid uptake via SR-BI and S1PR1 and S1PR3 but not S1PR2. The hearts from SHRs expressed significantly lower levels of S1PR3 than the hearts from WKYs. HDL differentially activated mediators of the SAFE and RISK pathways in WKYs and SHRs and resulted in nitric oxide generation. Blockage of these pathways abrogated HDL effects. HDL protects against myocardial I/R injury in normotensive and hypertensive rats, albeit to varying degrees. HDL protection in hearts from hypertensive rodents involved SR-BI-mediated lipid uptake coupled with signaling through S1PR1 and S1PR3. The extent of HDL-induced cardiac protection is directly proportional to S1PR3 expression levels. Mechanistically, the safeguarding effects of HDL involved activation of the SAFE and RISK pathways and the generation of nitric oxide.

GLP-1 in hypothalamic paraventricular nucleus promotes sympathetic activation and hypertension.

Glucagon-like peptide-1 (GLP-1) and its analogs are widely used for treatment of diabetes. Paraventricular nucleus (PVN) is crucial for regulating cardiovascular activity. This study aims to determine the roles of GLP-1 and its receptors (GLP-1R) in PVN in regulating sympathetic outflow and blood pressure. Experiments were carried out in male normotensive rats and spontaneously hypertensive rats (SHR). Renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) were recorded. GLP-1 and GLP-1R expression was present in the PVN. PVN microinjection of GLP-1R agonist recombinant human GLP-1 (rhGLP-1) or EX-4 increased RSNA and MAP, which were prevented by GLP-1R antagonist EX9-39 or GLP-1R antagonist 1, superoxide scavenger tempol, antioxidant N-acetylcysteine, NADPH oxidase inhibitor apocynin, adenylyl cyclase inhibitor SQ22536 or protein kinase A (PKA) inhibitor H89. PVN microinjection of rhGLP-1 increased superoxide production, NADPH oxidase activity, cAMP level, adenylyl cyclase and PKA activity, which were prevented by SQ22536 or H89. GLP-1 and GLP-1R were upregulated in the PVN of SHR. PVN microinjection of GLP-1 agonist increased RSNA and MAP in both WKY and SHR, but GLP-1 antagonists caused greater effects in reducing RSNA and MAP in SHR than in WKY. The increased superoxide production and NADPH oxidase activity in the PVN of SHR were augmented by GLP-1R agonists, but attenuated by GLP-1R antagonists. These results indicate that activation of GLP-1R in PVN increased sympathetic outflow and blood pressure via cAMP-PKA-mediated NADPH oxidase activation and subsequent superoxide production. GLP-1 and GLP-1R upregulation in the PVN partially contribute to sympathetic overactivity and hypertension.Significance Statement Activation of GLP-1 receptors in paraventricular nucleus (PVN) increases sympathetic activity and blood pressure, which are mediated by cAMP-PKA-NADPH oxidase-superoxide production. Intervention of GLP-1 receptors in the PVN may play beneficial roles in attenuating sympathetic overactivity and hypertension. The central effects may have a major impact during GLP-1 receptor agonist therapy in patients with hypertension.

Renal upregulation of NCC counteracts empagliflozin-mediated NHE3 inhibition in normotensive but not in hypertensive male rats.

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) reduce blood pressure (BP) in hypertensive patients, yet the precise molecular mechanisms remain elusive. SGLT2i inhibits proximal tubule (PT) NHE3-mediated sodium reabsorption in normotensive rodents, yet no hypotensive effect is observed under this scenario. This study examined the effect of empagliflozin (EMPA) on renal tubular sodium transport in normotensive and spontaneously hypertensive rats (SHRs). It also tested the hypothesis that EMPA-mediated PT NHE3 inhibition in normotensive rats is associated with upregulation of distal nephron apical sodium transporters. EMPA administration for 14 days reduced BP in 12-week-old SHRs but not in age-matched Wistar rats. PT NHE3 activity was inhibited by EMPA treatment in both Wistar and SHRs. In Wistar rats, EMPA increased NCC activity, mRNA expression, protein abundance, and phosphorylation levels, but not in SHRs. SHRs showed higher NKCC2 activity and abundance of cleaved ENaC α and γ subunits compared to Wistar rats, none of which were affected by EMPA. Another set of male Wistar rats was treated with EMPA, the NCC inhibitor hydrochlorothiazide (HCTZ), EMPA combined with HCTZ or vehicle for 14 days. In these rats, BP reduction was observed only with combined EMPA and HCTZ treatment, not with either drug alone. These findings suggest that NCC upregulation counteracts EMPA-mediated inhibition of PT NHE3 in male normotensive rats, maintaining their baseline BP. Moreover, the reduction of NHE3 activity without further upregulation of major apical sodium transporters beyond the PT may contribute to the BP-lowering effect of SGLT2i in experimental models and patients with hypertension.

Comparative proteomic analysis of renal tissue of normotensive and hypertensive rats.

Comparative proteomic analysis of kidney tissue from normotensive (WKY) and spontaneously hypertensive (SHR) rats revealed quantitative and qualitative changes in renal proteins. The number of renal proteins specific for WKY rats (blood pressure 110-120 mm Hg) was 13-16. There were 20-24 renal proteins specific for SHR (blood pressure 180 mm Hg and more). The total number of identified renal proteins common for both rat strains included 972-975 proteins. A pairwise comparison of all possible (SHR-WKY) variants identified 8 proteins specific only for normotensive (WKY) animals, and 7 proteins specific only for hypertensive ones (SHR). Taking into consideration their biological roles, the lack of some enzyme proteins in hypertensive rats (for example, biliverdin reductase A) reduces the production of molecules exhibiting antihypertensive properties, while the appearance of others (e.g. betaine-homocysteine S-methyltransferase 2, septin 2, etc.) can be interpreted as a compensatory reaction. Renal proteins with altered relative content (with more than 2.5-fold change) accounted for no more than 5% of all identified proteins. Among the proteins with an increased relative content in hypertensive animals, the largest group consisted of proteins involved in the processes of energy generation and carbohydrate metabolism, as well as antioxidant and protective proteins. In the context of the development of hypertension, the identified relative changes can apparently be considered compensatory. Among the proteins with the most pronounced decrease in the relative content in hypertensive rats, the dramatic reduction in acyl-CoA medium-chain synthetase-3 (ACSM3) appears to make an important contribution to the development of renal pathology in these animals.

Blood-Pressure-Lowering and Endothelium-Dependent Vasorelaxant Effects of Nutgall Tree in Rats.

Hypertension is the crucial modifiable risk factor for cardiovascular diseases, and efforts to identify functional foods that are effective for hypertension control are increasing. The nutgall tree (NT, Rhus chinensis Mill.) is used in traditional medicine and food because of its medicinal value. However, the role of NT in hypertension has not been investigated. Therefore, the hypotensive effect of NT leaf ethanol extract (NTE) was investigated in spontaneously hypertensive rats (SHRs). SHRs were allocated to three groups (control, 300, or 1000 mg/kg NTE), and blood pressure was measured before and after oral administration. Systolic and diastolic blood pressure significantly decreased in the NTE 1000 mg/kg group and was the lowest at 2 h after administration (-26.4 ± 10.3, -33.5 ± 9.8%, respectively). Daily NTE administration for five days also resulted in a similar effect. Further, the vasorelaxant effects and related mechanisms were investigated in the aortas of Sprague Dawley rats. NTE showed the dose-dependent blood-vessel-relaxing effect, and its mechanism involves the NO-sGC-cGMP pathway, activation of K+ channels, and reduction in the vasoconstrictive action of angiotensin II. Therefore, our study provides basic data indicating the potential use of NTE as a functional food for high blood pressure.

Parvalbumin interneuron deficiency in the prefrontal and motor cortices of spontaneously hypertensive rats: an attention-deficit hyperactivity disorder animal model insight.

Attention deficit hyperactivity disorder (ADHD) is characterized by impairments in developmental-behavioral inhibition, resulting in impulsivity and hyperactivity. Recent research has underscored cortical inhibition deficiencies in ADHD via the gamma-aminobutyric acid (GABA)ergic system, which is crucial for maintaining excitatory-inhibitory balance in the brain. This study explored postnatal changes in parvalbumin (PV) immunoreactivity, indicating GABAergic interneuron types, in the prefrontal (PFC) and motor (MC) cortices of spontaneously hypertensive rats (SHRs), an ADHD animal model. Examining PV- positive (PV+) cells associated with dopamine D2 receptors (D2) and the impact of dopamine on GABA synthesis, we also investigated changes in the immunoreactivity of D2 and tyrosine hydroxylase (TH). Brain sections from 4- to 10-week-old SHRs and Wistar Kyoto rats (WKYs) were immunohistochemically analyzed, comparing PV+, D2+ cells, and TH+ fiber densities across age-matched SHRs and WKYs in specific PFC/MC regions. The results revealed significantly reduced PV+ cell density in SHRs: prelimbic (~20% less), anterior cingulate (~15% less), primary (~15% less), and secondary motor (~17% less) cortices. PV+ deficits coincided with the upregulation of D2 in prepubertal SHRs and the downregulation of TH predominantly in pubertal/postpubertal SHRs. Reduced PV+ cells in various PFC regions could contribute to inattention/behavioral alterations in ADHD, while MC deficits could manifest as motor hyperactivity. D2 upregulation and TH deficits may impact GABA synthesis, exacerbating behavioral deficits in ADHD. These findings not only shed new light on ADHD pathophysiology but also pave the way for future research endeavors.