WKY Control Group Research Articles

Aerobic exercise improves renal fibrosis in spontaneously hypertensive rats

Objective: To study the effects of aerobic exercise training on renal fibrosis in spontaneously hypertensive rats (SHR), and to explore the protective effect of exercise on renal damage in hypertensive rats. Methods: Eight-week-old male SHR and Wistar Kyoto rats of the same age (WKY) were randomly divided into 4 groups (n=6): sedentary WKY control group (WKY-S), sedentary SHR control group (SHR-S), low-intensity exercise group (SHR-L) and medium-intensity exercise group (SHR-M). SHR-L group and SHR-M group were set at a slope of 0° at 14 m/min (35% of the maximum aerobic speed) and 20 m/min (50% of the maximum aerobic speed), running on a sports treadmill for 14 weeks, 5 times a week, and 60 min each time. WKY-S and SHR-S groups were kept quietly. Blood pressure was measured 72 hours after exercise training. And the serum levels of creatinine (Scr) and BUN were detected. The morphology of renal tissue was observed by hematoxylin and eosin (HE) staining. The collagen deposition of renal tissue was observed by Masson staining, and the renal collagen volume fraction (CVF) was calculated. Results: Compared with WKY-S group, blood pressure, serum Scr and BUN, kidney CVF levels and AngⅡ, AT1R, TGF-β, α-SMA, CTGF expressions in SHR-S group were increased significantly (P＜0.05). Compared with SHR-S group, blood pressure, serum Scr and BUN, kidney CVF level and AngⅡ, AT1R, TGF-β, α-SMA, CTGF expressions in SHR-L and SHR-M groups were decreased significantly (P＜0.05) and the decreasing trend was more obvious in SHR-M group (P＜0.05). Conclusion: Aerobic exercise can improve renal fibrosis and renal function in spontaneously hypertensive rats by inhibiting the AngⅡ-AT1R-TGF-β pathway.

Icariin modulates eNOS activity via effect on post-translational protein-protein interactions to improve erectile function of spontaneously hypertensive rats.

Type 5 phosphodiesterase inhibitor (PDE5I) has become the first-line treatment for erectile dysfunction (ED). However, its effective rate for hypertension ED is only 60%-70%. How to improve the efficacy of ED treatment is the focus of current research. To explore whether icariin can improve the erectile function of spontaneously hypertensive rats (SHR) by affecting post-translational protein-protein interactions to regulate endothelial nitric oxide synthetase (eNOS) activity. Twelve-week-old healthy male SHR rats and Wistar-Kyoto rats (WKY) were randomly divided into four groups: SHR control group, SHR+icariin (10mg/kg·d gavage) treatment group, WKY control group, and WKY+icariin (10mg/kg·d gavage) treatment group (n=5). After 4weeks, the maximum penile intracavernous pressure/mean arterial pressure (ICPmax/MAP), the expression of heat-shock protein 90 (Hsp90), caveolin-1, calmodulin, p-eNOS, and eNOS in penile cavernous tissue and the content of nitric oxide (NO) and cGMP were measured. The interaction between eNOS and Hsp90, caveolin-1, and calmodulin were detected by immunoprecipitation. The ICPmax/MAP in the SHR+icariin treatment group (0.08±0.01, 0.23±0.07, 0.40±0.05) was significantly higher than the SHR group (0.03±0.01, 0.13±0.03, 0.21±0.02) under 3V and 5V electrical stimulations (P<.05). Compared with the SHR group, the expression of HSP90, calmodulin, P-eNOS, eNOS, and P-eNOS/eNOS in the penile cavernous tissue of rats in the WKY group and the SHR+icariin treatment group were significantly increased (P<.05), and the expression of caveolin-1 was significantly decreased (P<.05). The NO content (2.16±0.22μmol/g) and cGMP concentration (3.69±0.12pmol/mg) in the SHR+icariin treatment group were significantly higher than those in the SHR group (1.01±0.14μmol/g, 2.31±0.22pmol/mg) (P<.05). Compared with the SHR group, the interaction between eNOS and HSP90 in the cavernosa of the rats in the SHR+icariin treatment group was significantly increased (P<.05), the interaction between eNOS and caveolin-1 was significantly decreased (P<.01), and the interaction between eNOS and calmodulin did not significantly change. Up-regulating the expression of HSP90 and calmodulin and inhibiting caveolin-1 in SHR corpus cavernosum, promoting the interaction between eNOS and HSP90, inhibiting the interaction between eNOS and caveolin-1, increasing p-eNOS/eNOS, may be the mechanism of icariin that improves SHR erectile function.

Establishment of the circadian metabolic phenotype strategy in spontaneously hypertensive rats: a dynamic metabolomics study

BackgroundCircadian rhythms play a fundamental role in the progression of cardiovascular events. Almost all cardiovascular diseases have a circadian misalignment usually characterized by changes in metabolites. This study aimed to dynamically monitor rhythmic biomarkers, to elucidate the metabolic pathways that are potentially under circadian control in spontaneously hypertensive rats (SHRs), and to eventually establish a circadian metabolic phenotype strategy based on metabolomics.MethodsIn this study, an untargeted metabolomics technology was used to dynamically monitor changes in serum metabolites between SHR model group and WKY control group. Liquid chromatography-mass spectrometry (LC–MS) combined with multivariate statistical analysis was applied to identify markers of hypertension rhythm imbalance. The concentrations of amino acids and their metabolites identified as markers were quantified by a subsequent targeted metabolomics analysis. Overall, these approaches comprehensively explored the rhythm mechanism and established a circadian metabolic phenotype strategy.ResultsThe metabolic profile revealed a disorder in the diurnal metabolism pattern in SHRs. Moreover, multivariate statistical analysis revealed metabolic markers of rhythm homeostasis, such as arginine, proline, phenylalanine, citric acid, l-malic acid, succinic acid, etc., accompanied by an imbalance in hypertension. The key metabolic pathways related to rhythm imbalance in hypertension were found by enrichment analysis, including amino acid metabolism, and the tricarboxylic acid cycle (TCA). In addition, the quantitative analysis of amino acids and their metabolites showed that the changes in leucine, isoleucine, valine, taurine, serine, and glycine were the most obvious.ConclusionsIn summary, this study illustrated the relationship between metabolites and the pathways across time on hypertension. These results may provide a theoretical basis for personalized treatment programmes and timing for hypertension.

Impact of a Multichannel Blocker in Attenuating Intramyocardial Artery Remodeling in Hypertensive Rats through Increased Nitric Oxide Bioavailability.

Dronedarone is recommended for the treatment of atrial fibrillation. However, we do not know its effect on vascular remodeling. This study was designed to assess whether dronedarone has the potential to improve the intramyocardial artery remodeling induced by chronic hypertension. Ten-month-old male spontaneously hypertensive rats (SHR) were randomly assigned to receive dronedarone (100 mg/kg) or vehicle. Age-matched male Wistar-Kyoto rats served as controls. After 14 days of treatment, we studied the structure (geometry and fibrosis) of the intramyocardial artery using histological analysis. Nitric oxide (NO) in plasma was analyzed. In the untreated SHR, we observed a significant increase in external diameter, lumen diameter, wall width, cross-sectional area, and collagen volume density, as was expected in the experimental model. Dronedarone induced a significant decrease in wall width, cross-sectional area, and collagen volume density in SHR-D in comparison with untreated SHR. The values obtained in SHR-D were similar in the WKY control group. We found significantly higher NO levels in plasma in SHR-D than in untreated SHR. Dronedarone improves the intramyocardial artery remodeling induced by chronic hypertension in SHR through increased nitric oxide bioavailability.

Icariin improves SHR erectile function via inhibiting eNOS uncoupling.

The aim of the study was to investigate whether or not the effect of icariin on erectile function of SHR is associated with inhibition of eNOS uncoupling. Ten 12-week-old male WKY rats and 10 age-matched male SHR were evenly randomised into SHR control group, SHR+ icariin treatment group, WKY control group and WKY+ icariin group. After being treated for 4weeks, ICPmax/MAP, the expression of NT, monomer and dimer of eNOS and the level of BH4, BH2, DHFR, NADPH oxidase and GTPCH1 in the corpus cavernosum were determined. The ICPmax/MAP and the value of BH4, DHFR and GTPCH1 in the SHR icariin treatment group were significantly higher than that of the SHR group and less than that of the WYK group and icariin-treated WKY group (p<0.05). The value of BH2, NADPH oxidase, the ratio of eNOS monomers/dimmers and NT in the SHR icariin treatment group was significantly less than that of in the SHR group and higher than that of the WYK control group and icariin-treated WKY group (p<0.05). Hypertension increases eNOS uncoupling in the corpus cavernosum of SHR. Inhibiting uncoupling of eNOS may be an important mechanism of icariin to improve SHR erectile function.

Attenuation of blood pressure in spontaneously hypertensive rats by acupuncture was associated with reduction oxidative stress and improvement from endothelial dysfunction.

BackgroundHypertension can be treated effectively by acupuncture; however, the association between acupuncture and endothelial function remains unknown. This study aimed to investigate the effects of acupuncture on endothelial dysfunction and oxidative stress-related parameters in spontaneously hypertensive animals.MethodsEighteen-week-old Wistar–Kyoto rats (WKYs) and spontaneously hypertensive rats (SHRs) were arbitrarily divided into four groups: WKY control (n = 8), SHR control (n = 8), SHR sham-acupuncture (n = 8) and SHR acupuncture (n = 8). The SHR acupuncture group had electroacupuncture for 6 consecutive weeks on acupoints ST36 and LR3. Blood pressure was monitored during the treatment period, and animals were euthanized at the 6th week. Aortas were harvested for determination of angiotensin II levels, NADPH oxidase activity and nitrate/nitrite levels. The level of reactive oxygen species (ROS) was determined by dihydroethidium (DHE) imaging, and functional studies were performed to assess vascular reactivity. Endothelial nitric oxide synthase was measured by Western blot assay.ResultsBlood pressure at the end of treatment was significantly lower in the SHR acupuncture group (185.0 ± 5.6 mmHg) compared with the SHR sham-acupuncture and the SHR control groups (201.0 ± 5.4 and 197.4 ± 5.9 mmHg, respectively; P < 0.001). Serum angiotensin II level in the SHR control group was significantly higher than in the WKY control group (P < 0.001), while it was significantly attenuated by acupuncture treatment (P = 0.023). DHE staining showed that ROS level was reduced in the aortas (P = 0.0017) and carotid arteries (P = 0.039) of acupuncture-treated SHRs. Biochemical assays showed that acupuncture inhibited the NADPH oxidase activity (P = 0.022) and enhanced antioxidant capacity (P = 0.0039). In functional studies, endothelium-dependent relaxation of aortic rings (P = 0.018) and carotid arteries (P = 0.022) in response to acetylcholine was improved in the SHR acupuncture group. Aortas of SHRs receiving acupuncture also expressed an elevated level of eNOS (P > 0.001) and p-eNOS (P = 0.012) and a reduced nitrotyrosine level (P = 0.0012). The nitrate/nitrite level in aortic tissue was also attenuated after acupuncture (P = 0.0018).ConclusionThe effects of acupuncture in treating hypertension were associated with reduced oxidative stress, increased nitric oxide bioavailability and endothelial function in SHRs.Electronic supplementary materialThe online version of this article (doi:10.1186/s13020-016-0110-0) contains supplementary material, which is available to authorized users.

Rg3-enriched Korean Red Ginseng enhances blood pressure stability in spontaneously hypertensive rats

BackgroundKorean Red Ginseng (Panax ginseng) has been shown to exert antihypertensive effects. In particular, ginsenoside Rg3 is thought to be a potent modulator of vascular function. The present study was performed to examine the antihypertensive efficacy of Korean Red Ginseng (KRG) extract and Rg3-enriched KRG (REKRG) extract. MethodsSpontaneously hypertensive rats (SHRs) and Wistar–Kyoto rats (WKYs) were divided into six groups (WKY control, WKY-KRG, WKY-REKRG, SHR control, SHR-KRG, and SHR-REKRG), and systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured at the carotid artery, followed by injection of 3mg/kg KRG or 3mg/kg REKRG. ResultsREKRG treatment significantly decreased SBP and DBP 3hours post-treatment in the SHR group compared with SHR control group. However, SBP and DBP were not significantly different in KRG-treated SHRs compared with control SHRs. REKRG treatment did not significantly alter SBP or DBP 3hours post-treatment in the WKY group compared with WKY control group. Similarly, there were no differences in SBP or DBP with KRG treatment in the WKY group and WKY control group. Both KRG and REKRG increased endothelial nitric oxide synthase phosphorylation levels in the aorta, and the increases in endothelial nitric oxide synthase phosphorylation levels by REKRG treatment were higher than those with KRG treatment. Similarly, nitric oxide production in plasma from WKYs and SHRs was also increased by both KRG and REKRG. ConclusionThese results suggest that REKRG has a more beneficial effect on blood pressure control than KRG in SHRs.

Combined Antihypertensive and Cardioprotective Effects of Nebivolol and Hydrochlorothiazide in Spontaneous Hypertensive Rats

The antihypertensive and cardioprotective effects of the combination of nebivolol (NEB) and hydrochlorothiazide (HCTZ) in spontaneously hypertensive rats (SHR) were investigated. SHR and age-matched Wistar-Kyoto normotensive rats were randomly assigned to one of six groups: SHR treated with NEB (1 mg/kg/day, intragastric); SHR treated with HCTZ (5 mg/kg/day, intragastric); SHR treated with NEB plus HCTZ (1 + 2.5 mg/kg/day); SHR treated with NEB plus HCTZ (1 + 5 mg/kg/day), along with a SHR and a WKY control group. The effects of NEB and HCTZ on clinical chemistry parameters and on cardiac function and structure were evaluated. NEB and HCTZ in combination had synergistic antihypertensive effects and significantly reduced heart rate and blood pressure compared with monotherapy with either agent. These effects were independent of water intake, urine output and electrolyte excretion. NEB plus HCTZ was associated with reduced oxidative stress in terms of glutathione availability, lower angiotensin I levels as index of plasma renin activity and reduced clearance of urinary sodium compared with HCTZ alone. Cardiac morphometric data and antioxidant parameters indicate that NEB may influence cardiac structure by reducing hypertrophy and by enhancing the availability of endothelial nitric oxide - a unique characteristic of NEB. The authors suggest that a combination of NEB and HCTZ for the treatment of hypertension may be useful for the synergistic characteristics of both drugs.

Effects of losartan, ramipril and their combination on left ventricular remodeling and function in spontaneous hypertensive rats

To evaluate the effects of losartan, an angiotensin receptor blocker, ramipril, an angiotensin converting enzyme inhibitor, and their combination on left ventricular remodeling and diastolic function in SHR at the same level of blood pressure. Sixty-two SHRs and 20 WKYs were divided randomly into 5 groups: WKY-control group, SHR-control group, SHR-ramipril group, SHR-losartan group, and SHR-combination group. Twelve weeks after feeding, 6 rats from each group were randomly selected to undergo hemodynamic examination and then killed to undergo further examinations, and 24 weeks after the remaining rats underwent the same examinations. The hemodynamic examination included the systolic blood pressure (SBP) of the caudal artery, left ventricular systolic pressure (LVSP), left ventricle end diastolic pressure (LVEDP), maximum uprising velocity of left ventricle pressure (dP/dtmax), and maximum declining velocity of left ventricle pressure (-dP/dtmax), and tau. Then the hearts were taken out to measure the weight of heart, undergo pathological examination, measure the intracellular free calcium concentrations, hydroxyproline concentration, interstitial collagen volume fraction (CVF), perivascular collagen area/luminal area (PVCA/LA), the mRNA expression of SR Ca(2+)-ATPase, phospholamban and L-type calcium channel, and the protein levels of SR Ca(2+)-ATPase. The myocardial ultrastructure was analyzed by electron microscopy. The speed, extent, and sustained time of blood pressure decrease were better in the combination group than in the other 2 treatment groups. Twelve and 24 weeks after treatment the levels of LVM/BW in the combination group were significantly lower than those of the control group, however, without significant differences among the 3 treatment groups. The values of LVSP, LVEDP, and tau 12 and 24 weeks after treatment in the 3 treatment groups were all significantly lower and the levels of -dP/dtmax significantly higher than those of the control group (all P < 0.01). The values of CVF in the myocardium and PCVA/VA of the heart wall arteriole 12 and 24 weeks after in the 3 treatment groups were significantly lower than those of the control group, and the CVF in the myocardium 12 weeks after in the combination group was significantly than that of the ramipril group. Microscopy showed that the degree of myocardial fibrosis in the 3 treatment groups were significantly milder than those of the control group, and the ultrastructure improvement improved along with the lapse of time in the sequence of combination group > losartan group > ramipril group. The concentrations of hydroxyproline in cardiac muscle cells of the 3 treatment 12 and 24 weeks after were significantly than those of the control group and decreased gradually time-dependently. The expression of Ca(2+)-ATPase mRNA 24 weeks after of the ramipril, losartan, and combination groups were 53.5%, 72.9%, and 76.7% higher than that of the control group, and the Ca(2+)-ATPase protein expression of the 3 treatment groups were 28.9%, 33.3%, and 49.3% higher than that of the control group. The expression of L-type Ca(2+) channel mRNA of the 3 treatment groups were 51.8%, 76.8%, and 98.2% than that of the control group. Both losartan and ramipril reverse LVH and left ventricular diastolic dysfunction. A combination of these two drugs is more effective than single drug treatment for improvement of myocardial fibrosis and ultrastructure. All three-treatment groups can raise calcium-handling proteins mRNA and protein expressions, which may be the underlying molecular mechanisms for their therapeutic effects.

Changes and significance of hydrogen sulfide/cystathionine gamma-lyase system in hypertension: an experimental study with rats

To explore the significance of hydrogen sulfide/cystathionine gamma-lyase (H(2)S/CSE) system in the development of hypertension and the effects of H(2)S/CSE system on the modulation of aortic remodeling process of hypertension. Eight 4-week-old male WKY rats were used as WKY control group, and another sixteen SHR rats at the age of 4 weeks were randomly divided into SHR control group (n = 8) and SHR + NaHS (H(2)S donor) group (n = 8). The rats of SHR control and WKY control were injected with normal saline and the rats of the SHR + NaHS group were injected with NaHS each day. Five weeks later, the blood pressure and the left-to-whole heart weight ratio were determined. The transcriptional level of CSE in aorta and the H(2)S level in plasma were detected. The morphometric parameters of the thoracic aorta including the outer radius, medium area and ratio of wall thickness to lumen radius were detected too. At the age of 9 weeks the systolic blood pressure and the left-to-whole heart weight ratio of the SHR control rats were both higher than those of the WKY control rats [(184 +/- 12) mm Hg vs (108 +/- 23) mm Hg, 1 mm Hg = 0.133 kPa, and (0.853 +/- 0.021) vs (0.826 +/- 0.024)]. The transcriptional level of CSE in aorta and the H(2)S level in serum of the rats in the SHR control group were both lower than those of the rats in the WKY control group (9.3 +/- 0.7) x 10(-8) fmol vs (16.1 +/- 1.0) x 10(-8) fmol, and (20 +/- 9) micro mol/L vs (48 +/- 13) micro mol/L, while the morphometric parameters of the thoracic aorta including the outer radius, the medium area and ratio of lumen radius and wall thickness of the SHR control rats were all higher compared with those of the WKY control rats [outer radius: (1999 +/- 45) micro m vs (1790 +/- 96) micro m], medium area: (0.60 +/- 0.06) mm(2) vs (0.48 +/- 0.03) mm(2), and ratio of wall thickness to lumen radius: (0.066 +/- 0.006) vs (0.060 +/- 0.004). The exogenous administration of NaHS made the systolic blood pressure of rats in the SHR + NaHS group much lower than that of the rats in SHR control group [(158 +/- 13) mm Hg vs (184 +/- 12) mm Hg], however, the transcriptional level of CSE in aorta and the H(2)S level in serum of the rats in SHR + NaHS group were much higher than those of the rats in SHR control group [(12.4 +/- 1.0) x 10(-8) fmol vs (9.3 +/- 0.7) x 10(-8) fmol] vs [(96 +/- 32) micro mol/L vs (20 +/- 9) micro mol/L]. The morphometric parameters of SHR + NaHS group were lower than those of the SHR control group. Down regulation of H(2)S/CSE system is a major factor in the development of spontaneous hypertension and the accompanying structural remodeling of aorta. Exogenous administration of H(2)S may attenuate the process of hypertension.

Dietary vitamin E supplementation lowers blood pressure in spontaneously hypertensive rats.

In spontaneously hypertensive rats (SHRs) excess endogenous aldehydes bind sulfhydryl groups of membrane proteins, altering membrane Ca2+ channels and increasing cytosolic free calcium and blood pressure. The thiol compound, N-acetyl cysteine, normalizes elevated blood pressure in SHRs by binding excess endogenous aldehydes. Vitamin E increases tissue glutathione levels--a storage form of cysteine. The aim of the present study was to investigate whether a dietary supplementation of vitamin E lowers blood pressure and prevents renal vascular changes by normalizing tissue aldehyde conjugates and cytosolic [Ca2+] in SHRs. Starting at 12 weeks of age, animals were divided into three groups of six animals each. Animals in the WKY-control group and SHR-control group were given a normal diet and the SHR-vitamin E group a diet supplemented with vitamin E (34 mg/ kg feed) for the next 9 weeks. After 9 weeks, systolic blood pressure, platelet [Ca2+]i, and liver, kidney and aortic aldehyde conjugates were significantly higher in SHR controls as compared to WKY controls and the SHR-vitamin E group. SHR-controls also showed smooth muscle cell hyperplasia in the small arteries and arterioles of the kidney. Dietary vitamin E supplementation in SHRs lowered the systolic blood pressure, cytosolic [Ca2+], tissue aldehyde conjugates and attenuated adverse renal vascular changes.

Dietary vitamin B6 supplementation attenuates hypertension in spontaneously hypertensive rats.

In spontaneously hypertensive rats (SHRs) excess endogenous aldehydes bind sulfhydryl groups of membrane proteins, altering membrane Ca2+ channels, increasing cytosolic free calcium and blood pressure. N-acetyl cysteine normalizes elevated blood pressure in SHRs by binding excess endogenous aldehydes. It is known that dietary vitamin B6 supplementation can increase the level of endogenous cysteine. Our objective was to investigate whether a dietary supplementation of vitamin B6 can prevent hypertension and associated changes in SHRs. Starting at 7 weeks of age, animals were divided into three groups of six animals each. Animals in WKY-control group and SHR-control group were given a normal vitamin B6 diet; and SHR-vitamin B6 group, a high vitamin B6 diet (20 times the recommended dietary intake; RDA) for the next 14 weeks. After 14 weeks, systolic blood pressure, platelet [Ca2+]i and liver, kidney and aortic aldehyde conjugates were significantly higher in SHR controls compared to WKY controls. These animals also showed smooth muscle cell hyperplasia in the small arteries and arterioles of the kidneys. Dietary vitamin B6 supplementation attenuated the increase in systolic blood pressure, tissue aldehyde conjugates and associated changes. These results further support the hypothesis that aldehydes are involved in increased systolic blood pressure in SHRs and suggest that vitamin B6 supplementation may be an effective antihypertensive.

Do angiotensin converting enzyme inhibitors lower blood pressure in the rat partly via the humorally mediated antihypertensive system of the renal medulla?

It has been suggested that there is a negative-feedback interaction between the humoral renomedullary antihypertensive system and angiotensin II. If so, the acute blood pressure-lowering effects of angiotensin converting enzyme (ACE) inhibitors might be due, in part, to an increased secretion of renomedullary depressor substances. Groups of anaesthetized Wistar-Kyoto rats (WKY) with an intact or chemically destroyed renal medulla received either saline or the ACE inhibitor enalapril, and mean arterial pressure (MAP), heart rate and renal function were measured. MAP was clearly decreased after enalapril administration in the WKY controls with an intact renal medulla, but was not changed in the medullectomized group. In one WKY control group, where the prostaglandin and kallikrein-kinin systems had also been acutely blocked, the MAP reduction after enalapril was even more marked than in the intact controls. Thus, the acute blood pressure-lowering effect of enalapril is clearly dependent on an intact renal medulla, further suggesting that the renomedullary antihypertensive system is important to normal blood pressure homeostasis.