Renovascular Hypertensive Rats Research Articles

Gstp1 negatively regulates blood pressure in hypertensive rat via promoting APLNR ubiquitination degradation mediated by Nedd4.

Hypertension is a leading risk factor for disease burden worldwide. Vascular contraction and remodeling contribute to the development of hypertension. Glutathione S-transferase P1 (Gstp1) plays several critical roles in both normal and neoplastic cells. In this study, we investigated the effect of Gstp1 on hypertension and on vascular smooth muscle cell (VSMC) contraction and phenotypic switching. We identified the higher level of Gstp1 in arteries and VSMCs from hypertensive rats compared with normotensive rats for the first time. We then developed Adeno-associated virus 9 (AAV9) mediated Gstp1 downregulation and overexpression in rats and measured rat blood pressure by using the tail-cuff and the carotid catheter method. We found that the blood pressure of spontaneously hypertensive rats (SHR) and 2-kidney-1-clip (2K1C) renovascular hypertensive rats rose significantly with Gstp1 downregulation and reduced apparently after Gstp1 overexpression. Gstp1 did not influence blood pressure of normotensive Wistar-Kyoto (WKY) rats and Sprague-Dawley (SD) rats. Further in vitro study indicated that Gstp1 knockdown in SHR-VSMCs promoted cell proliferation, migration, dedifferentiation and contraction. Results from bioinformatic analysis showed that the Apelin/APLNR system was involved in the effect of Gstp1 on SHR-VSMCs. The rise in blood pressure of SHR induced by Gstp1 knockdown could be reversed by APLNR antagonist F13A. We further found that Gstp1 enhanced the association between APLNR and Nedd4 E3 ubiquitin ligases to induce APLNR ubiquitination degradation. Thus, in the present study, we discovered a novel anti-hypertensive role of Gstp1 in hypertensive rats and provided the experimental basis for designing an effective anti-hypertensive therapeutic strategy.

Cerebral Perfusion Characteristics and Dynamic Brain Structural Changes in Stroke-Prone Renovascular Hypertensive Rats: A Preclinical Model for Cerebral Small Vessel Disease.

Hypertension is a leading cause of cerebral small vessel disease (CSVD) and vascular dementia in elderly individuals. We aimed to assess cerebral perfusion and dynamic changes in brain structure in stroke-prone renovascular hypertensive rats (RHRSPs) with different durations of hypertension and to investigate whether they have pathophysiological features similar to those of humans with CSVD.The RHRSP model was established using the two-kidney, two-clip (2k2c) method, and the Morris water maze (MWM) test, MRI, immunohistochemistry, and biochemical analysis were performed at multiple time points for up to six months following the 2k2c operation.Systolic blood pressure was significantly greater in the RHRSP group than in the sham-operated group at week 4 post-surgery and continued to increase over time, leading to cognitive decline by week 20. Arterial spin labeling revealed cerebral hypoperfusion in the RHRSP group at 8 weeks, accompanied by vascular remodeling and decreased vessel density. Diffusion tensor imaging and Luxol fast blue staining indicated that white matter disintegration and demyelination gradually progressed in the corpus callosum and that myelin basic protein levels decreased. Eight weeks after surgery, blood-brain barrier (BBB) leakage into the corpus callosum was observed. The albumin leakage area was negatively correlated with the myelin sheath area (r=-0.88, p<0.001). RNA-seq analysis revealed downregulation of most angiogenic genes and upregulation of antiangiogenic genes in the corpus callosum of RHRSPs 24 weeks after surgery.RHRSPs developed cerebral hypoperfusion, BBB disruption, spontaneous white matter damage, and cognitive impairment as the duration of hypertension increased. RHRSPs share behavioral and neuropathological characteristics with CSVD patients, making them suitable animal models for preclinical trials related to CSVD.

Antihypertensive and Antioxidant Effects of an Aqueous Extract of Asafetida in Renovascular Hypertensive Rats

Recently, the effect of an aqueous extract of asafetida on acute angiotensin II hypertensive rats was evaluated. The present study evaluated the antihypertensive and antioxidant effects of asafetida on a rat model of renovascular hypertension (RVH) using four groups. RVH was induced by clipping the renal artery; the sham group underwent surgery but without clipping. The RVH rats received losartan (Los, an AT1 receptor antagonist) or asafetida by gavage for 4 weeks. On the 28th day, the femoral artery was cannulated, and the systolic blood pressure (SBP), mean arterial pressure (MAP), and heart rate (HR) were recorded. Finally, the levels of superoxide dismutase (SOD) activity, malondialdehyde (MDA), and total thiol content in the kidney and heart tissues were measured. In RVH rats, SBP and MAP significantly increased compared with the control. Los and the extract significantly reduced the changes in SBP, MAP, and HR that were induced in the RVH rats (P &lt;0.05–0.001). In RVH rats, levels of MDA significantly increased and the content of total thiol and SOD decreased in both the heart and kidney tissues. Los plus the extract significantly decreased MDA and increased total thiol and SOD in the heart and kidney tissues. We concluded that an aqueous extract of asafetida gum has antihypertensive and antioxidant effects in the RVH rat model. The effect of the extract is similar to that of Los, which suggests that this effect of asafetida is mediated via an effect on the angiotensin Type I receptor.

Celastrol ameliorates energy metabolism dysfunction of hypertensive rats by dilating vessels to improve hemodynamics.

The impact of hypertension on tissue and organ damage is mediated through its influence on the structure and function of blood vessels. This study aimed to examine the potential of celastrol, a bioactive compound derived from Tripterygium wilfordii Hook F, in mitigating hypertension-induced energy metabolism disorder and enhancing blood perfusion and vasodilation. In order to investigate this phenomenon, we conducted in vivo experiments on renovascular hypertensive rats, employing indirect calorimetry to measure energy metabolism and laser speckle contrast imaging to evaluate hemodynamics. In vitro, we assessed the vasodilatory effects of celastrol on the basilar artery and superior mesenteric artery of rats using the Multi Wires Myograph System. Furthermore, we conducted preliminary investigations to elucidate the underlying mechanism. Moreover, administration of celastrol at doses of 1 and 2mg/kg yielded a notable enhancement in blood flow ranging from 6 to 31% across different cerebral and mesenteric vessels in hypertensive rats. Furthermore, celastrol demonstrated a concentration-dependent (1 × 10-7 to 1 × 10-5M) arterial dilation, independent of endothelial function. This vasodilatory effect could potentially be attributed to the inhibition of Ca2+ channels on vascular smooth muscle cells induced by celastrol. These findings imply that celastrol has the potential to ameliorate hemodynamics through vasodilation, thereby alleviating energy metabolism dysfunctions in hypertensive rats. Consequently, celastrol may hold promise as a novel therapeutic agent for the treatment of hypertension.

Enhanced angiogenesis in the thalamus induced by a novel TSPO ligand ameliorates cognitive deficits after focal cortical infarction

Neuronal loss in the ipsilateral thalamus after focal cortical infarction participates in post-stroke cognitive deficits, and enhanced angiogenesis in the thalamus is expected to reduce neuronal damage. We hypothesize that novel translocator protein (TSPO) ligand, 2-Cl-MGV-1, can promote angiogenesis, attenuate neuronal loss in the thalamus, and ameliorate post-stroke cognitive deficits. Cortical infarction was induced by distal middle cerebral artery occlusion (dMCAO) in stroke-prone renovascular hypertensive rats. 2-Cl-MGV-1 or dimethyl sulfoxide was administered 24 h after dMCAO and then for 6 or 13 days. Spatial learning and memory were assessed using the Morris water maze. Neuronal loss, TSPO expression, angiogenesis, and intrinsic pathway were determined by immunofluorescence and immunoblotting 7 and 14 days after dMCAO. Cortical infarction caused post-stroke cognitive deficits and secondary neuronal loss with gliosis in the ipsilateral thalamus within 14 days of dMCAO. Increased angiogenesis and elevated expression of vascular TSPO were detected in the ipsilateral thalamus, and treatment with 2-Cl-MGV-1 enhanced angiogenesis by stimulating the PI3K-AKT-mTOR pathway. The effects of 2-Cl-MGV-1 on angiogenesis coincided with reduced neuronal loss in the thalamus and contributed to improvements in post-stroke cognitive deficits. Our findings suggest that 2-Cl-MGV-1 stimulates angiogenesis, ameliorates neuronal loss in the thalamus, and improves post-stroke cognitive deficits.

Chronic red laser treatment induces hypotensive effect in two-kidney one-clip model of renovascular hypertension in rat.

To evaluate whether the chronic effect of photobiomodulation therapy (PBM) onsystolic arterial pressure (SAP)from two kidneys one clip (2K-1C) hypertension animal models can cause a hypotensive effect. Serum levels of nitric oxide were also analyzed and the assessment of lipid peroxidation of the thoracic aorta artery. Male Wistar rats were used. Hypertensive animals (2K-1C) with Systolic arterial pressure (SAP) greater than or equal to 160mmHg were used. Systolic arterial pressure (SAP) was determined by the tail plethysmography technique. Normotensive (2K) and hypertensive (2K-1C) rats were treated to PBM for 4weeks using a laser whose irradiation parameters were: red wavelength (λ) = 660nm: operating continuously; 56s per point (3 points) spot size = 0.0295 cm2; average optical power of 100 mW; energy of 5.6J per point; irradiance of 3.40 W/cm2; fluency of 190J/cm2 per point. The application was on the animals tails, at 3 different points simultaneously, in contact with the skin. To assess serum nitrite and nitrate (NOx) levels, blood collection was performed after chronic PBM treatment, 24h after the last laser application. The evaluation of the lipid peroxidation of the thoracic aorta artery was performed by measuring the concentration of hydroperoxide by the FOX method. Chronic photobiomodulation therapy (PBM) by red laser (660nm) can induce a hypotensive effect in 64% of 2K-1C hypertensive animals, which we say responsive animals. There was no difference in serum NO levels 24h after the last red laser application, between treated and non-treated groups. Aortic rings from 2K-1C hypertensive animals present a higher lipid peroxidation. The chronic PBM treatment by red laser decreased aortic rings lipid peroxidation in hypertensive responsive groups, compared to control. our results indicate that chronic PBM made by red laser has an important hypotensive effect in renovascular hypertensivemodels, by a mechanism that involves decrease in oxidative stress from vascular beds.

Targeting the adenosine monophosphate-activated protein kinase signalling pathway by bempedoic acid attenuates Angiotensin II-induced cardiac remodelling in renovascular hypertension in rats

The crosstalk between the renin-angiotensin system and Adenosine monophosphate-activated protein kinase (AMPK) gained significant interest due to their involvement in the pathogenesis of several cardiovascular diseases. Angiotensin II (Ang II) plays a crucial role in developing cardiac remodelling by inducing energy imbalance, inflammation, oxidative and endoplasmic reticulum stress, and transforming growth factor-β (TGF-β)-induced fibrosis. Ang II directly or through extracellular signal-regulated kinase (ERK) activation impairs AMPK signalling with well-known antioxidant, anti-inflammatory, and anti-fibrotic effects. AimThis study aimed to investigate the role of bempedoic acid, a novel antihyperlipidemic drug, in attenuating hypertension-induced cardiac remodelling in rats by modulating Ang II-induced damage and activating the AMPK signalling pathway. MethodSixty adult male Sprague Dawley rats were randomly allocated into the Sham control group, Hypertensive group, Captopril group (30 mg/kg), and Bempedoic acid group (30 mg/kg). Hypertension was induced by left renal artery ligation in all groups except the Sham control group. Treatment with captopril and bempedoic acid started 14 days post-surgy and lasted two weeks. Finally, Hemodynamic measurements and electrocardiographic examination were done followed by heart tissue samples collection for biochemical, histopathological, and immunohistochemical examinations. Key findingsBempedoic acid preserved the cardiac function and electrocardiogram patterns. It inhibited endoplasmic reticulum stress, exhibited antioxidant activity, and increased endothelial nitric oxide synthase activity. Bempedoic acid interfered with ERK signalling pathways, including nuclear factor-κB and TGF-β, exerting anti-inflammatory and anti-fibrotic effects. SignificanceThese findings indicate the cardioprotective and antihypertrophic activity of bempedoic acid, which are suggested to result from energy-independent AMPK downstream signalling activation.

Acute inhibition of nicotinamide adenine dinucleotide phosphate oxidase in the commissural nucleus of the solitary tract reduces arterial pressure and renal sympathetic nerve activity in renovascular hypertension.

A growing body of evidence suggests that oxidative stress plays a role in the pathophysiology of hypertension. However, the involvement of the reactive oxygen species (ROS) in the commissural nucleus of the solitary tract (commNTS) in development the of hypertension remains unclear. We evaluated the hemodynamic and sympathetic responses to acute inhibition of NADPH oxidase in the commNTS in renovascular hypertensive rats. Under anesthesia, male Holtzman rats were implanted with a silver clip around the left renal artery to induce 2-kidney 1-clip (2K1C) hypertension. After six weeks, these rats were anesthetized and instrumented for recording mean arterial pressure (MAP), renal blood flow (RBF), renal vascular resistance (RVR), and renal sympathetic nerve activity (RSNA) during baseline and after injection of apocynin (nicotinamide adenine dinucleotide phosphate oxidase inhibitor), NSC 23766 (RAC inhibitor) or saline into the commNTS. Apocynin into the commNTS decreased MAP, RSNA, and RVR in 2K1C rats. NSC 23766 into the commNTS decreased MAP and RSNA, without changing RVR in 2K1C rats. These results demonstrate that the formation of ROS in the commNTS is important to maintain sympathoexcitation and hypertension in 2K1C rats and suggest that NADPH oxidase in the commNTS could be a potential target for therapeutics in renovascular hypertension.

No benefit of HIF prolyl hydroxylase inhibition for hypertensive renal damage in renovascular hypertensive rats.

Introduction: We previously reported that malignant hypertension is associated with impaired capillary density of target organs. Here, we tested the hypothesis that stabilization of hypoxia-inducible factor (HIF) in a modified "preconditioning" approach prevents the development of malignant hypertension. To stabilize HIF, we employed pharmacological inhibition of HIF prolyl hydroxylases (PHD), that profoundly affect HIF metabolism. Methods: Two-kidney, one-clip renovascular hypertension (2K1C) was induced in rats; controls were sham operated. 2K1C rats received either intermittent injections of the PHD inhibitor ICA (2-(1-chloro-4-hydroxyisoquinoline-3-carboxamido) acetate) or placebo. Thirty-five days after clipping, the frequency of malignant hypertension was assessed (based on weight loss and the occurrence of characteristic vascular lesions). In addition, kidney injury was compared between all ICA treated versus all placebo treated 2K1C, regardless of the occurrence of malignant hypertension. HIF stabilization was evaluated by immunohistochemistry, and HIF target gene expression by RT-PCR. Results: Blood pressure was elevated to the same degree in ICA- and placebo-treated 2K1C compared to control rats. ICA treatment did not affect the frequency of malignant hypertension or the extent of kidney tissue fibrosis, inflammation, or capillary density. There was a trend towards higher mortality and worse kidney function in ICA-treated 2K1C rats. ICA increased the number of HIF-1α-positive renal tubular cell nuclei and induced several HIF-1 target genes. In contrast, expression of HIF-2α protein as well as HIF-2 target genes were markedly enhanced by 2K1C hypertension, irrespective of ICA treatment. Discussion: We conclude that intermittent PHD inhibition did not ameliorate severe renovascular hypertension in rats. We speculate that the unexpected strong renal accumulation of HIF-2α in renovascular hypertension, which could not be further augmented by ICA, may contribute to the lack of a benefit from PHD inhibition.

Methyl Palmitate Modulated NMDA-Induced Cerebral Hyperemia in Hypertensive Rats

N-methyl-D-aspartate (NMDA) receptors were found to be dysfunctional in hypertensive rats. Methyl palmitate (MP) has been shown to diminish the nicotine-induced increase in blood flow in the brainstem. The aim of this study was to determine how MP modulated NMDA-induced increased regional cerebral blood flow (rCBF) in normotensive (WKY), spontaneously hypertensive (SHR), and renovascular hypertensive (RHR) rats. The increase in rCBF after the topical application of experimental drugs was measured using laser Doppler flowmetry. Topical NMDA application induced an MK-801-sensitive increase in rCBF in anesthetized WKY rats, which was inhibited by MP pretreatments. This inhibition was prevented by pretreatment with chelerythrine (a PKC inhibitor). The NMDA-induced increase in rCBF was also inhibited by the PKC activator in a concentration-dependent manner. Neither MP nor MK-801 affected the increase in rCBF induced by the topical application of acetylcholine or sodium nitroprusside. Topical application of MP to the parietal cortex of SHRs, on the other hand, increased basal rCBF slightly but significantly. MP enhanced the NMDA-induced increase in rCBF in SHRs and RHRs. These results suggested that MP had a dual effect on the modulation of rCBF. MP appears to play a significant physiological role in CBF regulation.

Influence of Intestinal Barrier on Alleviating an Increase in Blood Pressure by Sodium Alginate Intake in 2-Kidney, 1-Clip Renovascular Hypertensive Rats.

Sodium alginate (SALG) is a substance derived from brown seaweed that has been shown to reduce blood pressure (BP). However, its effects on renovascular hypertension caused by 2-kidney, 1-clip (2K1C) are not yet clear. Previous research suggests that hypertensive rats have increased intestinal permeability, and that SALG improves the gut barrier in inflammatory bowel disease mouse models. Therefore, the goal of this study was to determine whether the antihypertensive effects of SALG involve the intestinal barrier in 2K1C rats. Rats were fed either a 1.0% SALG diet or a control diet for six weeks after being subjected to 2K1C surgery or a sham operation. The systolic BP was measured weekly, and the mean arterial BP was measured at the end of the study. Intestinal samples were taken for analysis, and plasma lipopolysaccharide (LPS) levels were measured. The results showed that BP in 2K1C rats was significantly higher than in SHAM rats when fed CTL, but not when fed SALG. The gut barrier in 2K1C rats was improved by SALG intake. Plasma LPS levels also differed depending on the animal model and diet. In conclusion, dietary SALG may alleviate 2K1C renovascular hypertension by altering the gut barrier.

Baroreflex Sensitivity, Cardiac and Kidney Remodeling and Deterioration in Vasoactive Substances Content in Blood in Experimental Model of Renovascular Hypertension. Action of Natural Flavone, Luteolin

This study aimed to analyze pharmacological actions of phenolic compound luteolin on the renal and cardiac hypertrophy, blood pressure (BP), baroreflex sensitivity (BRS), levels of epoxyeicosatrienoic acids (EETs), prostaglandin E-2 (PGE-2) and endothelin-1 (E1) in plasma in the 2 kidney - 1 clip (2K-1C) model of renovascular hypertension (RVH). All animals, were randomized into 2 groups: control (normal) I - sham-operated, II- RVH male Wistar rats, which after 4 weeks of surgical intervention secondly randomized to control II group, treated 0.1% dimethyl sulphoxide (DMSO) and main group - with luteolin in 15 DMSO, 3 mg/kg body weight, intraperitonially, during 2 weeks. ET-1, EETs and PGE2 levels investigated in carotid artery blood plasma and analyzed using ELISA kits. All data statistically analyzed using the SPSS-10.0 program. In RVH rats BP increased by 32%, cardiac and right kidney hypertrophy and reduction in parasympathetic component of BRS by 40% and sympathetic by 39%. The plasma level of total trans-EETs and PGE2 in RVH rats decreased by 44% and 50% respectively, while the level of ET-1 increased by 67%. Two weeks treatment with luteolin lowered BP, improved parasympathetic, without marked changes in sympathetic component of BRS. Deremodeling of cardiac and renal hypertrophy under prolonged treatment with luteolin accompanied with increasing in the level of EETs by 44%, PGE-2 by 50% and markedly reducing of plasma content of ET-1 (by 60%). Inhibition of EET hydrolase using low doses of luteolin provides beneficial cardio and renoprotective action in experimental model of RVH.

Heart rate fragmentation in renovascular hypertensive rats

Although rapid oscillations of the heart rate (HR) are attributed to vagal modulation of the heart, a pattern of ultra-rapid HR variation has been named heart rate fragmentation (HRF). It is a recently proposed approach to evaluate sino-atrial instability characterized by the presence of numerous inflections points in a series of successive values of cardiac intervals. HRF is increased in aging and coronary diseases. Hypertension markedly alters HRV indices and might affect HRF as well. This study aimed to investigate the HRF in renovascular hypertension in rats. Wistar rats were anesthetized, and hypertension was surgically induced by partial constriction of the left renal artery with a silver clip with a 0.2 mm gap. In one kidney one clip (1K1C) hypertension model, the contralateral kidney was removed. In two kidneys one clip (2K1C) model, the contralateral kidney was kept intact. Sham-operated control rats underwent to same surgical procedures without receiving the clip around the renal artery. After 45 days (2K1C) or 60 days (1K1C), animals were instrumented with a catheter into the femoral artery, and on the following day, their arterial pressure (AP) was directly recorded without the effect of anesthesia. For HRF analysis, pulse interval (PI) series were generated and transformed into a sequence of symbols “-1,” “0,” or “1” when the difference between successive PI values (transitions) was negative, zero, or positive, respectively. Following, sequences of 4 consecutive symbols were classified according to the number of transitions. The total percentage of inflection points (PIP) and the percentage of sequences with zero (W0), one (W1), two (W2), or three (W3) inflection points were quantified. As expected, the arterial pressure increased in both groups of hypertension rats compared to control counterparts. All HRF indices were found similar in 1K1C hypertensive rats compared to their control counterparts. Nevertheless, in 2K1C hypertensive rats HRF was found to be lower than normotensive controls (PIP: 64±7 vs. 79±1% and W2: 30±1 vs. 39±1% in 2K1C and normotensive controls, respectively). In conclusion, high blood pressure itself does not affect HRF, although, depending on the model of hypertension used, HRF can be markedly impaired. The interpretation of these findings is challenging, and the high levels of angiotensin in the 2K1C model may affect cardiac pacemaker cells, making their action potentials more stable than unstable. However, the specific mechanisms by which this could happen still need to be studied. Funding Sources: FAPESP, CAPES and CNPq This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Toll-like receptors (TLR2 and TLR4) antagonist mitigates the onset of cerebral small vessel disease through PI3K/Akt/GSK3β pathway in stroke-prone renovascular hypertensive rats

ABSTRACT To examine the effect and mechanism of Toll-Like Receptors (TLR2, TLR4) antagonist in CSVD. The rat model of stroke-induced renovascular hypertension (RHRSP) was constructed. TLR2 and TLR4 antagonist was administrated by Intracranial injection. Morris water maze was used to observe the behavioral changes of rat models. HE staining, TUNEL staining and Evens Blue staining were performed to evaluate the permeability of the blood-brain barrier (BBB) and examine the CSVD occurrence and neuronal apoptosis. The inflammation and oxidative stress factors were detected by ELISA. Hypoxia-glucose-deficiency (OGD) ischemia model was constructed in cultured neurons. Western blot and ELISA were used to examine the related protein expression in TLR2/TLR4 signaling pathway and PI3K/Akt/GSK3β signaling pathway. The RHRSP rat model was successfully constructed, and the blood well and BBB permeability were altered. The RHRSP rats showed cogitative impairment and excessive immune response. After TLR2/TLR4 antagonist administration, the behavior of model rats were improved, cerebral white matter injury was reduced, and the expression of several key inflammatory factors including TLR4, TLR2, Myd88 and NF-kB were decreased, as well as the ICAM-1, VCAM-1, inflammation and oxidative stress factors. In vitro experiments showed that TLR4 and TLR2 antagonist increased the cell viability, inhibited the apoptosis, and decreased p-Akt and p-GSK3β expression. Moreover, the PI3K inhibitors resulted in decreased anti-apoptotic and anti-inflammatory effects of TLR4 and TLR2 antagonist. These results suggested that TLR4 and TLR2 antagonist achieved protective effect on the RHRSP through the PI3K/Akt/GSK3β pathway.

Chronic administration of catalase inhibitor attenuates hypertension in renovascular hypertensive rats

AimsReactive oxygen species like hydrogen peroxide (H2O2) are produced endogenously and may participate in intra- and extracellular signaling, including modulation of angiotensin II responses. In the present study, we investigated the effects of chronic subcutaneous (sc) administration of the catalase inhibitor 3-amino-1,2,4-triazole (ATZ) on arterial pressure, autonomic modulation of arterial pressure, hypothalamic expression of AT1 receptors and neuroinflammatory markers and fluid balance in 2-kidney, 1clip (2K1C) renovascular hypertensive rats. Materials and methodsMale Holtzman rats with a clip occluding partially the left renal artery and chronic sc injections of ATZ were used. Key findingsSubcutaneous injections of ATZ (600 mg/kg of body weight/day) for 9 days in 2K1C rats reduced arterial pressure (137 ± 8, vs. saline: 182 ± 8 mmHg). ATZ also reduced the sympathetic modulation and enhanced the parasympathetic modulation of pulse interval, reducing the sympatho-vagal balance. Additionally, ATZ reduced mRNA expression for interleukins 6 and IL-1β, tumor necrosis factor-α, AT1 receptor (0.77 ± 0.06, vs. saline: 1.47 ± 0.26 fold change), NOX 2 (0.85 ± 0.13, vs. saline: 1.75 ± 0.15 fold change) and the marker of microglial activation, CD 11 (0.47 ± 0.07, vs. saline, 1.34 ± 0.15 fold change) in the hypothalamus of 2K1C rats. Daily water and food intake and renal excretion were only slightly modified by ATZ. SignificanceThe results suggest that the increase of endogenous H2O2 availability with chronic treatment with ATZ had an anti-hypertensive effect in 2K1C hypertensive rats. This effect depends on decreased activity of sympathetic pressor mechanisms and mRNA expression of AT1 receptors and neuroinflammatory markers possibly due to reduced angiotensin II action.

S-44-2: ANTIHYPERTENSIVE EFFECT OF GALANGIN IN RENAL ARTERY STENOSIS-INDUCED HYPERTENSIVE RATS

Background: Galangin is a natural flavonoid found in honey and Alpinia officinarum. Several reports have suggested the anti-mutagenic, antioxidant, anti-proliferative, and apoptotic effects. However, the antihypertensive effect of galangin in renovascular hypertension has not been investigated. Aims: This study aims to investigate the effect of galangin on blood pressure and cardiac changes in renovascular hypertension. Methods: Male Sprague Dawley rats (180–220 g) were induced hypertension by clipping the left renal artery, 2-kidney-1-clip (2K-1C). After 3 weeks of the induction period, galangin (30 and 60 mg/kg) and losartan (10 mg/kg) were given to the rats for 4 weeks (n = 8/group). Blood pressure and cardiac function were evaluated at the end of the experimental day. The level of angiotensin-converting enzyme (ACE) activity, angiotensin II, and oxidative stress markers were assessed in the plasma and cardiac tissue of rats. The protein expression of angiotensin II receptor type 1 (AT1R), transforming growth factor-beta 1 (TGF- β 1) and collagen type I (Col I) were determined in cardiac tissue. Statistical analysis was carried out by one-way ANOVA followed by Tukey post hoc test. A p value less than 0.05 was considered statistically significant. Results: Hypertension and cardiac dysfunction and hypertrophy were observed in 2K-1C rats compared to the sham-operated rats (p &lt; 0.05). Treatment with galangin (30 and 60 mg/kg) decreased high blood pressure and improved cardiac function as well as alleviated left ventricular hypertrophy in 2K-1C hypertensive rats (p &lt; 0.05). This result was related with the reduction of systemic ACE activity and angiotensin II levels in 2K-1C hypertensive rats that were treated with galangin (p &lt; 0.05). Moreover, the expression of AT1R, TGF- β 1 and Col I in cardiac tissue was modulated by treatment with galangin (p &lt; 0.05). Additionally, galangin showed anti-oxidative effects as it reduced the production of superoxide and malondialdehyde levels in cardiac tissue of rats (p &lt; 0.05). Conclusion: Galangin exhibited an antihypertensive effect and alleviated cardiac alteration in renovascular hypertensive rats. The underlying mechanism might be related to its inhibitory effects on renin-angiotensin system and anti-oxidative properties renal artery stenosis-induced hypertensive rats. Furthermore, the beneficial effect of galangin on heart might mediate the suppression of AT1R, TGF- β 1 and Col I pathway.

S-51-6: RENOVASCULAR HYPERTENSION AND BRAIN: ROLE OF THE RENIN-ANGIOTENSIN SYSTEM AND SODIUM

Renovascular hypertension is a type of secondary hypertension. Renovascular hypertensive 2-kidney, 1-clip (2K1C) rats have an increased activity of the renin-angiotensin system, and it is an experimental model to study renovascular hypertension. Renovascular hypertensive 2K1C rats have an imbalance of RAS components in the brain, an impairment of the baroreflex and they present an increase in daily intake of hypertonic NaCl solution. Therefore, we focused on studying: 1) the effects of overexpression of RAS components in the in the nucleus of the solitary tract (NTS), a brainstem area involved with cardiovascular control, 2) the brain mechanisms involved with the sodium appetite (operationally defined as an ingestion of hypertonic NaCl solution) in 2K1C rats. In adult Holtzman rats, the left renal artery was partially occluded by a silver clip with an opening of 0.2 mm to induce 2K1C. The experiments started after 6 weeks (hypertension plateau). We observed that increasing angiotensin type 2 receptor (AT2R) expression in the NTS attenuated the development of renovascular hypertension and also reversed the impairment of the baroreflex observed in 2K1C rats. Furthermore, an observed decrease in mRNA levels of angiotensin-converting enzyme 2 in the NTS of 2K1C rats was restored to control levels after viral-mediated increases in AT2R at this site. Virally mediated blockade of an intracellular pathway activated by angiotensin II (ANG II) acting in type 1 receptor (AT1R) in the NTS attenuated the development of renovascular hypertension and also reversed the impairment of the baroreflex. Daily 0.3 M NaCl intake transiently increased from the 2nd to the 5th week after 2K1C surgery. On the 6th week, in spite of comparable daily 0.3 M NaCl intake between 2K1C and sham rats, water deprivation (used to induce sodium appetite) produced a greater increase 0.3 M NaCl intake in 2K1C rats. Moreover, this intake is totally blocked by central AT1R and mineralocorticoid receptor antagonism. These data demonstrated that ANG II acting in the AT1R in the NTS is involved with the development of hypertension and baroreflex impairment in 2K1C and that AT2 overexpression at the same site can counteract these effects. In addition, the results demonstrated the participation of ANG II and aldosterone acting centrally in the enhanced sodium intake in water deprived 2K1C rats.

TAK1 Improves Cognitive Function via Suppressing RIPK1-Driven Neuronal Apoptosis and Necroptosis in Rats with Chronic Hypertension.

Chronic hypertension is a major risk factor for cognitive impairment, which can promote neuroinflammation and neuronal loss in the central nervous system. Transforming growth factor β-activated kinase 1 (TAK1) is a key molecular component in determining cell fate and can be activated by inflammatory cytokines. This study aimed to investigate the role of TAK1 in mediating neuronal survival in the cerebral cortex and hippocampus under chronic hypertensive conditions. To that end, we used stroke-prone renovascular hypertension rats (RHRSP) as chronic hypertension models. Adeno-associated virus (AAV) designed to overexpress or knock down TAK1 expression were injected into the lateral ventricles of rats and the subsequent effects on cognitive function and neuronal survival under chronic hypertensive conditions were assessed. We found that, TAK1 knockdown in RHRSP markedly increased neuronal apoptosis and necroptosis and induced cognitive impairment, which could be reversed by Nec-1s, an inhibitor of receptor interacting protein kinase 1 (RIPK1). In contrast, overexpression of TAK1 in RHRSP significantly suppressed neuronal apoptosis and necroptosis and improved cognitive function. Further knockdown of TAK1 in sham-operated rats received similar phenotype with RHRSP. The results have been verified in vitro. In this study, we provide in vivo and in vitro evidence that TAK1 improves cognitive function by suppressing RIPK1-driven neuronal apoptosis and necroptosis in rats with chronic hypertension.

Quercetin decreases cardiac hypertrophic mediators and maladaptive coronary arterial remodeling in renovascular hypertensive rats without improving cardiac function.

Oxidative stress and MMP activity are found in the hearts and arteries in hypertension and contribute to the resulting hypertrophy and dysfunction. Quercetin is a flavonoid that reduces MMP-2 activity and ameliorates hypertrophic vascular remodeling of hypertension. The hypothesis is that treatment of hypertensive rats with quercetin ameliorates coronary maladaptive remodeling and decreases hypertrophic cardiac dysfunction by decreasing oxidative stress and MMP activity. Male Sprague-Dawley two-kidney, one-clip (2K1C) and Sham rats were treated with quercetin (10mg/kg/day) or its vehicle for 8weeks by gavage. Rats were analyzed at 10weeks of hypertension. Systolic blood pressure (SBP) was examined by tail-cuff plethysmography. Cardiac left ventricles were used to determine MMP activity by in situ zymography and oxidative stress by dihydroethidium. Immunofluorescence was performed to detect transforming growth factor (TGF)-β and nuclear factor kappa B (NFkB). Morphological analyses of heart and coronary arteries were done by H&E and picrosirius red, and cardiac function was measured by Langendorff. SBP was increased in 2K1C rats, and quercetin did not reduce it. However, quercetin decreased both oxidative stress and TGF-β in the left ventricles of 2K1C rats. Quercetin also decreased the accentuated MMP activity in left ventricles and coronary arteries of 2K1C rats. Quercetin ameliorated hypertension-induced coronary arterial hypertrophic remodeling, although it did not reduce cardiac hypertrophic remodeling and dysfunction. Quercetin decreases cardiac oxidative stress and TGF-β and MMP activity in addition to improving coronary remodeling, yet does not ameliorate cardiac dysfunction in 2K1C rats.

Effects of Electroacupuncture on the Expression of Glial Fibrillary Acidic Protein and Vascular Endothelial Growth Factor and Cell Structure in the Gliavascular Net of Cerebral Ischemic Tissues in Hypertensive Rats

Introduction: This study aims to explore the effects of electroacupuncture on the expression of GFAP and VEGF and cell structure in the glia vascular net of cerebral ischemic tissues in hypertensive rats. Material and Methods: Stroke-prone renovascular hypertensive rat (RHRSP) models and middle cerebral artery occlusion (MCAO) were established. After two hours of ischemia and at 1, 7, 14 and 28 days after reperfusion, the expression of GFAP and VEGF in rat cerebral ischemic tissues was detected by immunohistochemistry and light microscopy. Results: Positive GFAP cells were found in the semidarkness area after two hours of ischemic and one day of reperfusion in the control group, and these increased after 14 days, decreased after 14 days, and significantly decreased after 28 days, when compared to the sham group (P &lt; 0.01). Compared to the control group, GFAP-positive cells significantly increased after 7, 14 and 28 days of ischemic and reperfusion in the electric acupuncture group. Then, this significantly increased and reached the maximum after seven days of reperfusion, but decreased after 14 days. Contrarily, this significantly decreased after 30 day, but remained higher than that in sham-operated group (P &lt; 0.05). Compared to the control group, the number of positive VEGF cells increased after 7, 14 and 28 days of ischemic and reperfusion in the electric acupuncture group (P &lt; 0.01). Conclusions: Electric acupuncture can promote neurofunctional recovery in the cerebral ischemic area. The mechanism may be correlated with the regulation of the expression of GFAP and VEGF, and the rebuilding of the gliavascular net of cerebral ischemic tissues, thereby decreasing cerebral ischemic damage.