Wistar-Kyoto Rats Research Articles

Abstract P421: Differential Osmolyte Profiles in Hypertensive and Normotensive Rats.

Hypertension is known to be associated with water-electrolyte balance disturbances that lead to changes in osmotic pressure. Osmolytes are small organic molecules essential for cellular adaptation to changes in osmotic pressure. This study investigates the levels of osmolytes in serum and tissues using two well-established rat models of hypertension: spontaneously hypertensive rats (SHRs) and Wistar-Kyoto rats with angiotensin II-induced hypertension (WKY-ANG). Experiments were conducted on male Wistar-Kyoto (WKY) rats, SHRs, and WKY-ANG rats. Blood and tissue samples were collected from all groups for liquid chromatography with mass spectrometry (LC-MS) analysis of selected osmolytes. Anesthetized SHR and WKY-ANG rats displayed significantly elevated mean arterial blood pressures compared to WKY rats (118.4±1.3, 110.2±0.9, and 76.5±1.2 mmHg, respectively). The serum and tissue levels of sarcosine were significantly decreased in SHRs compared to WKY rats (1.90±0.21 vs. 3.80±0.80 for serum, 55.55±9.79 vs 92.37±10.57 for liver, 6.06±0.78 vs. 10.55±1.19 for renal cortex, 9.14±0.45 vs.13.83±1.14 for renal medulla, 11.59±1.17 vs. 22.34±3.11 for lungs, 1.80±0.14 vs. 3.30±0.39 for heart, respectively). Reduced levels of beta-alanine were observed only in the serum of SHRs compared to WKY and WKY-ANG rats (6.48±0.93 vs. 59.43±9.47, 41.32±3.13 respectively). Additionally, higher levels of L-alanine were noted in the renal cortex and medulla of WKY than in SHRs and WKY-ANG rats (19685±592.3 vs. 14510±456.8, 14289±719.4 for cortex and 14043±560.3 vs. 11520±206.8, 10651±292.4 for medulla, respectively). Conversely, SHR rats exhibited significantly higher levels of serum glycerophosphocholine (GPC) than WKY-ANG rats (38.21±10.02 vs. 12.47±2.25). Simultaneously, lower levels of betaine were observed in the lungs of SHR rats when compared to WKY and WKY-ANG rats (1 and 351.20±36.02, 607.10±64.20, 606.70±55.88 for lungs respectively). All results are indicated in μmol/L and means±SE. In conclusion significant alterations in osmolyte concentrations are evident in hypertensive rats. These findings suggest that hypertension may be associated with disruptions in osmolyte balance. Further studies are needed to assess the potential clinical significance of osmolyte disturbances in hypertension.

Chronic Administration of Red Yeast Rice Mitigates Endothelial Dysfunction in Spontaneously Hypertensive Rats by Inhibiting Oxidative Stress and Endothelial Nitric Oxide Synthase Uncoupling.

Hypertension is associated with endothelial dysfunction. An imbalance in the production of Nitric Oxide (NO) and Reactive Oxygen Species (ROS), leading to impaired NO-cyclic Guanosine Monophosphate (cGMP) pathway, contributes to this disorder. Red Yeast Rice (RYR), produced from the fermentation of rice with Monascus purpureus, is a traditional functional food originating from China. Although recognized for its anti-dyslipidemia properties, there has been growing evidence regarding the anti-hypertensive effects of RYR. However, these studies only focused on its direct and short-term effects. This study aims to investigate the vasoprotective effects of chronic oral RYR administration using Spontaneously Hypertensive Rats (SHR). SHR were randomly divided into 3 groups: SHR - Control; SHR - RYR extract (100 mg/kg/day); SHR - lovastatin (10 mg/kg/day). Wistar-Kyoto Rats (WKY) were used as normotensive controls. All animals were treated for 12 weeks by oral gavage. Systolic Blood Pressure (SBP) was measured weekly (tail-cuff method). Vascular reactivity was determined using isolated rat aortic rings in an organ bath. Aortic ROS, NO, tetrahydrobiopterin (BH4), and cGMP levels were evaluated. Administration of RYR attenuated SBP elevation and enhanced endothelium-dependent vasodilation in aortic rings. In addition, RYR decreased ROS production and significantly improved the level of vascular NO, BH4, and cGMP. In an SHR model, treatment with RYR for 12 weeks exerts an SBP lowering effect that can be attributed to improved vascular function via reduction of oxidative stress, decreased endothelial NO Synthase (eNOS) uncoupling and enhanced NO-cGMP pathway.

Abstract P448: Follistatin Improves Vascular Function by Regulating Perivascular Adipose Tissue in Essential Hypertension

Introduction: Essential hypertension is characterized by resistance artery remodeling induced by oxidative stress. Most vessels are surrounded by perivascular adipose tissue (PVAT) which regulates vascular tone via release of vasoactive substances. In physiological conditions, PVAT induces an anticontractile effect. In pathological conditions such as hypertension, PVAT exhibit increased oxidative stress resulting in augmented contraction and reduced relaxation. Follistatin, an antioxidant glycoprotein, has been shown to induce adipose tissue browning which is linked to improved vasorelaxation and BP. We hypothesize that follistatin, through ROS inhibition and PVAT browning, lowers BP and improves vessel function in a model of essential hypertension. Methods: Spontaneously hypertensive rats (SHR) were treated with vehicle or follistatin every other day for 8 weeks. Wistar Kyoto (WKY) rats served as normotensive controls. BP was measured weekly by radiotelemetry. Mesenteric arteries and PVAT were used. KCl-induced smooth muscle contraction was assessed using wire myography. ROS was measured by DHE (dihydroethidium) staining. Vasodilator nitric oxide (NO) bioavailability in PVAT was measured using DAF-2 FM. Protein expression of markers for ROS or PVAT browning was measured by immunohistochemistry. Results: Follistatin significantly lowered BP in SHRs and restored anticontractile effect of PVAT. Increased ROS in SHR vessels and PVAT were also inhibited. Follistatin inhibited SHR PVAT-induced vascular oxidative stress. SHR PVAT NO bioavailability was increased by acute follistatin treatment via ROS inhibition. Follistatin also increased expression of brown adipose tissue markers in SHR PVAT suggesting PVAT browning. Limitations: Above studies do not confirm whether PVAT pathology causes hypertension in this model. Vascular dysfunction is an independent risk factor for CVD and our studies do not yet consider effects of follistatin on end-organ damage. Conclusions: Follistatin lowers BP in SHRs likely via improved vascular and perivascular structure and function. Specifically, follistatin inhibited perivascular ROS, increased NO and induced PVAT browning suggesting improved regulation of vascular function and thus, BP. Future work will utilize proteomic assays to identify novel mediators of follistatin effects on PVAT in the SHR.

Abstract P205: Single-nucleus Sequencing Reveals Endothelial Cell-specific Dysregulation in the Kidney in Multiple Models of Hypertension

The kidney plays a crucial role in the onset and progression of hypertension. To investigate the roles of different renal cell types in hypertension, we applied single-nucleus sequencing and spatial transcriptome sequencing to kidney samples from three well-established hypertension models: C57BL/6 mice treated with Ang II, the Dahl salt-sensitive (SS) rat on high-salt diets, and the spontaneously hypertensive rat (SHR), along with their respective controls including Sprague-Dawley (SD) and Wistar Kyoto (WKY) rats. Our dataset comprised 179,637 nuclei from 24 samples across 12 experimental conditions, identifying 17 major cell types including various epithelial cells, endothelial cells, vascular smooth muscle cells, fibroblasts, and immune cells. At baseline, differentially expressed genes between the SS and SD groups were specifically enriched in endothelial cell pathways related to vascular development. This included expression deficiencies in genes involved in angiogenesis in SS rats, such as Arhgap24 and Nox4. Compensatory expression changes in these genes were observed in the SS rats after a high-salt diet and in 26-week-old SHR, but not in their respective controls. These genes were also associated with multiple blood pressure-associated single-nucleotide polymorphisms (SNPs). Furthermore, changes in endothelial cell communication were most prominent upon stimuli, with impaired PTPRM (Protein Tyrosine Phosphatase Receptor Type M) signaling being a robust feature in hypertension models, involving angiogenic endothelial cells in the SS model and proliferating capillary endothelial cells in the SHR model. Our study highlights the critical role of renal endothelial cell angiogenic dysfunction in the pathogenesis of hypertension and suggests a link between specific renal endothelial cell subtype dysregulation and hypertension development.

O101 THE ANGIOTENSIN II TYPE 1 RECEPTOR-BIASED AGONIST REDUCES BLOOD PRESSURE IN SPONTANEOUSLY HYPERTENSIVE RATS AND RESTORES VENTRICULAR HYPERTROPHY BY AFFECTING THE CONNEXIN 43 PATHWAY

Purpose: Hypertension is one of the common causes of cardiovascular diseases. Long-term hypertension can lead to structural and functional impairment of the heart. Therefore, active treatment of hypertension is highly significant in preventing target organ damage. Angiotensin II (AngII) plays a crucial role in hypertension-induced cardiac hypertrophy. Reportedly, TRV027, an AngII type 1 receptor (AT1R) biased agonist, can competitively bind to AT1R and inhibit the AngII-induced damage. Whether TRV027 could lower blood pressure and treat hypertensive cardiac hypertrophy remains unknown. Methods: Spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were selected, and some of the SHRs were administered with TRV027. H9C2 cells were utilized for in vitro study to explore the underlying mechanism of TRV027. A multidisciplinary approach combining pathology and molecular techniques was used to explore the role and mechanism of TRV027 in reducing blood pressure and restoring ventricular hypertrophy. Results: Our studies revealed that TRV027 reduced blood pressure and restored hypertension-induced ventricular hypertrophy in SHRs. Moreover, the modulated expression of Connexin43 (Cx43) and phosphorylation of the MAPK/ERK pathway were normalized by TRV027. After the inhibition of Cx43 expression, cardiomyocytes recovered from hypertrophy and damage, followed by the modulation of phosphorylation of the MAPK/ERK pathway. Conclusion: TRV027 demonstrates a potential to lower the blood pressure in SHRs and ameliorate hypertension-induced cardiac hypertrophy. While AngII stimulated cardiomyocyte injury by decreasing Cx43 expression and increasing the phosphorylation of the MAPK/ERK pathway, TRV027 repaired the hypertrophy by restoring the expression of the Cx43/MAPK/ERK pathway.

Abstract P138: Diet Influences the Expression of Renal Sodium-Glucose Cotransporters in Juvenile Male Rats

Poor nutrition and metabolic dysfunction are becoming more prevalent among children, as evident by increasing childhood obesity in recent years. The kidney sodium-glucose cotransporter 2 (SGLT2) is a contributor to overall metabolic homeostasis, with inhibition of SGLT2 significantly reducing circulating glucose and lipids. The study objective was to determine if diet influences the expression of renal glucose transporters in young rats. Weanling male Wistar Kyoto rats received 1) standard laboratory chow, 2) AIN-93G diet, or 3) a high-fat diet (60% kcal, HFD). Each dietary group was then further subdivided to receive either filtered water or 5% (w/v) sucrose solution ad libitum . Four weeks later, animals were euthanized and kidneys were collected and processed. mRNA expression of Sglt1 , Sglt2 , Sqstm1 , and Nlrp3 was determined using gene specific primers and RT-PCR. Renal SGLT2 protein expression was visualized using immunohistochemistry and quantified using Imagej software. Diet significantly influenced the renal expression of both Sglt1 ( P =0.005) and Sglt2 (P=0.046), while beverage did not have a significant effect on either ( P =0.7 and P =0.4, respectively). Rats fed the HFD had more than 30% reduction in Sglt1 mRNA expression as compared to rats fed chow, and ~20% reduction in Sglt2 as compared to rats fed AIN. Preliminary data suggest that diet and beverage significantly altered renal protein expression of SGLT2, with rats fed chow having the lowest renal expression that was slightly increased with sugar consumption (1.5% versus 2.7%, respectively). Rats fed AIN had the greatest expression, but was drastically reduced in rats consuming sugar (4% versus 1.2%, respectively). To determine if autophagy and inflammasome activation is involved, the expression of Sqstm1 and Nlrp3 was measured by RT-PCR. Similarly, rats fed HFD had the lowest expression of both Sqstm1 ( P<0.001) and Nlrp3 ( P=0.03). Sqstm1 and Nlrp3 mRNA expression was decreased with sugar consumption in rats fed chow and AIN, whereas Sqstm1 ( P =0.01) and Nlrp3 ( P <0.001) mRNA expression was increased in rats fed HFD with sugar beverage. Our data suggest that diet significantly influences renal glucose transporter expression in juvenile rats in a way that may be mediated by autophagic impairment. The modulatory effect of sugar consumption on SGLT2 protein, Sqstm1, and Nlrp3 was diet-dependent, highlighting the importance of nutrition to renal physiology within weeks after weaning.

O70 INVOLVEMENT OF MICRORNAs-146a-5P, -155-5P, AND -29b-5P IN CARDIAC REMODELLING AND DYSFUNCTION IN SPONTANEOUSLY HYPERTENSIVE RATS

Background: MicroRNAs have been implicated in the pathogenesis of cardiovascular disease. However, the contribution of microRNAs remain poorly understood in the context of hypertensive cardiac pathology. Aim: We investigated the role of miR-146a-5p, -155-5p, and -29b-5p in the development of cardiac hypertrophy and dysfunction in male and female spontaneously hypertensive rats (SHR). Methods: Seven (7)-month-old SHR (n=7 male, n=10 female), and age- and sex-matched normotensive Wistar Kyoto rats (WKY, n=7 male, n=9 female) were used for the study. Cardiac geometry and function were determined from echocardiography. Plasma levels of inflammatory markers were measured by ELISA. Collagen fraction area was determined from histological sections of the left ventricle (LV). MicroRNA, and mRNA expression of target genes was determined in the LV by RT-qPCR. Group differences were ascertained from 2-way ANOVA. Associations were determined from pearson's correlation. Results: In SHR, normalised heart and LV masses, LVPWTd, RWT, E, A, E/e’, and collagen fraction area were significantly greater compared to WKY. MidFS, e’, and a’ were significantly lower in SHR versus WKY. Female rats exhibited significantly greater LV mRNA expression of Lox1, Col1a/Col3a ratio, and plasma levels of CRP, IL-6, and TNF-α compared to males. MiR-29b-5p showed similar expression levels across experimental groups. MiR-146a-5p was upregulated in SHR and exhibited positive associations with BP, normalised heart and LV masses, RWT, collagen fraction area, and E/e’ ratio, but negative associations with e’. Conversely, miR-155-5p was downregulated in females and only positively associated with absolute heart, LV, kidney masses, and stroke volume. Conclusion: Upregulation of miR-146a-5p was associated with indices of concentric LVH, diastolic dysfunction, reactive fibrosis, and may be involved in the hypertensive-induced LV remodelling; whereas, changes in expression of miR-155-5p may be involved with a cardiac phenotype related to sexual dimorphism.

Mechanisms of retinal photoreceptor loss in spontaneously hypertensive rats

Retinal neurodegenerative diseases, including hypertensive retinopathy, involve progressive damage to retinal neurons, leading to visual impairment. In this study, we investigated the pathological mechanisms underlying retinal neurodegeneration in spontaneously hypertensive rats (SHR), using Wistar Kyoto (WKY) rats as normotensive controls. We observed that SHR exhibited significantly higher blood pressure and decreased retinal thickness, indicating retinal neurodegeneration. Molecular tests including quantitative real-time polymerase chain reaction, immunoblot, and immunofluorescent staining showed elevated levels of the pro-inflammatory cytokine tumor necrosis factor-α, apoptotic markers (Fas, FasL, caspase-8, active caspase-3, and cleaved poly (ADP-ribose) polymerase), and necroptotic markers (receptor-interacting protein kinase-1 and -3) in SHR retinas. Additionally, we found elevated transforming growth factor-β (TGF-β) levels in the retinal pigment epithelium (RPE) of SHR, with a decrease in lecithin retinol acyltransferase (LRAT), which regulates retinoid metabolism and photoreceptor health. In human RPE cells (ARPE-19), TGF-β administration suppressed mRNA and protein levels of LRAT; and vactosertib, a selective inhibitor of TGF-β receptor kinase type 1, reversed the effect of TGF-β. These findings suggest that hypertension-induced retinal neurodegeneration involves inflammation, apoptosis, necroptosis, and disrupted retinoid metabolism, providing potential therapeutic targets for hypertensive retinopathy.

Differential gene expression in the kidneys of SHR and WKY rats after intravenous administration of Akkermansia muciniphila-derived extracellular vesicles

Although Akkermansia muciniphila (Am) plays a beneficial role as a probiotic in the treatment of metabolic syndrome, the mechanisms remain elusive. We tested the hypothesis that Am extracellular vesicles (AmEVs) protect against hypertension through modulation of gene expression in the kidneys of spontaneously hypertensive rats (SHRs). Extracellular vesicles purified from anaerobically cultured Am (1.0 × 108 or 1.0 × 109 particles/kg) or vehicles were injected into the tail veins of Wistar-Kyoto rats (WKYs) and SHRs weekly for 4 weeks. Renal cortical tissues isolated from both rat strains were analyzed by trichrome stain and RT-qPCR. AmEVs protect against the development of hypertension in SHRs without a serious adverse reaction. AmEVs increased the expression of vasocontracting Agt and At1ar as well as vasodilating At2r, Mas1 and Nos2 in the kidneys of both strains. These results indicate that AmEVs have a protective effect against hypertension without a serious adverse reaction. Therefore, it is foreseen that AmEVs may be utilized as a novel therapeutic for the treatment of hypertension.

Fecal Microbiota Transplantation Regulates Blood Pressure by Altering Gut Microbiota Composition and Intestinal Mucosal Barrier Function in Spontaneously Hypertensive Rats.

Hypertension is accompanied by gut microbiota imbalance, but the role of bacteria in the pathogenesis of hypertension requires further study. In this study, we used fecal microbiota transplantation to determine the impact of microbiota composition on blood pressure in spontaneous hypertensive rats (SHRs), using normotensive Wistar Kyoto (WKY) rats as controls. SHRs were randomly divided into two groups (n = 10/group), SHR and SHR-T (SHR plus fecal transplantation) and WKY into WKY and WKY-T (WKY plus fecal transplantation). SHR-T received fecal transplantation from WKY, while WKY-T received fecal transplantation from SHR. Blood pressure was measured from the tail artery in conscious rats. 16S rDNA gene amplicon sequencing was used to analyze bacterial composition. Circulating levels of diamine oxidase, D-lactate, FITC-Dextrans, and lipopolysaccharide were determined. Hematoxylin and eosin (H&E) staining was used to observe structural changes in the intestinal mucosa. Immunofluorescence, Western blot, and RT-PCR were utilized to determine changes in the expression of tight junction proteins. Following cross fecal transplantation, blood pressure decreased in SHR and increased in WKY. Significant differences in gut microbial composition were found between hypertensive and normotensive rats, specifically regarding the relative abundance of lactic and butyric acid-producing bacteria. Changes in gut microbiota composition also impacted the intestinal mucosal barrier integrity. Moreover, fecal transplantation affected the expression of tight junction proteins that may impact intestinal mucosal permeability and structural integrity. Blood pressure may be associated with butyric acid-producing intestinal microbiota and its function in regulating the integrity of intestinal mucosal barrier.

Spontaneously Hypertensive Rats Present Exacerbated Focal Stroke Behavioral Outcomes.

This study aimed to analyze the effects of systemic arterial hypertension (SAH) in a model of permanent ischemic stroke (focal ischemia due to thermocoagulation of pial vessels) on sensorimotor function (cylinder test and patch removal test), behavioral tasks (novelty habituation memory open field task) and cerebral infarct size in adult male spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY) for 42 days after the occurrence of a stroke. We observed that the stroke caused asymmetry in the front paws and delayed adhesive removal. These effects were spontaneously reduced in WKY rats, but not in SHR. Short- and long-term novelty habituation memories were abolished by stroke in WYK and SHR. On the 3rd day after stroke, the size of the focal cerebral infarct was the same in WKY and SHR. However, on the 7th day, the infarct size decreased in WKY rats, but not SHR. These results suggested that SAH impairment of sensorimotor recovery in rats subjected to cerebral ischemia could be related to augmented focal cerebral infarct size. Moreover, the behavioral tasks used in this study were unaffected by Systemic Arterial Hypertension. Our results highlight the need for animal models of comorbidities in stroke research.

Effects of acupuncture on endothelial active factors and related autonomic neurotransmitters in spontaneous hypertension rats

To observe the effects of acupuncture at "antihypertensive acupoint prescription" on endothelial active factors and related autonomic neurotransmitters in spontaneous hypertension rats, and explore the vascular regulation and central regulation mechanisms of acupuncture for anti-hypertension. Thirty SPF grade male spontaneous hypertension rats were randomly divided into a model group (15 rats) and an acupuncture group (15 rats). Besides, 15 Wistar Kyoto rats were collected as a blank control group (normal group). In the acupuncture group, acupuncture was delivered at the "antihypertensive acupoint prescription" (bilateral "Renying" [ST 9], "Quchi" [LI 11], "Zusanli" [ST 36], "Taichong" [LR 3] and "Neiguan" [PC 6]), with needles retained for 30 min, once daily. The duration of intervention was 28 days. Every week, using the the irritation scale, the sign of sympathetic irritation was evaluated dynamically. The arterial blood pressure of the rats tail was determined, using non-invasive blood pressure measurement system. ELISA was adopted to detect the levels of calcitonin gene-related peptide (CGRP), nitric oxide (NO), endothelin-1 (ET-1), neuropeptide Y (NPY) in the serum. DAB chromogenic in situ hybridization (CISH) was provided to detect the mRNA expression of endothelial nitric oxide synthase (eNOS) in the internal carotid artery and the arcuate nucleus (ARC), and that of CGRP in the paraventricular nucleus posterior (PVP) and the ventrolateral medulla (VLM). Liquid chromatography-mass spectrometry (LC-MS) was used to detect the levels of epinephrine (E) and norepinephrine (NE) in the paraventricular nucleus anterior (PVA). Compared with the normal group, the irritation scores, systolic blood pressure and diastolic blood pressure were increased at each time point in the model group (P<0.05). When compared with the model group, the irritation scores after the intervention for 3 and 4 weeks, and systolic and diastolic blood pressure after intervention for 2, 3 and 4 weeks were reduced in the acupuncture group (P<0.05). In comparison with the normal group, the serum CGRP and NO levels of the rats were decreased (P<0.05), and the serum ET-1 and NPY levels, as well as E and EN levels in PVA were increased (P<0.05) in the model group. The levels of serum CGRP and NO were elevated (P<0.05), and the serum ET-1 and NPY levels, as well as E and EN levels of PVA were reduced (P<0.05) in the acupuncture group when compared with those of the model group. In the model group, the media of internal carotid artery exhibited thickening and remodeling, while the neuron volume in ARC was small. In the acupuncture group, every layer of internal carotid artery was acceptably arranged, and the parvicellular neuron of ARC was moderate in volume. For the in situ hybridization of eNOS mRNA for the rats of each group, the smooth muscle cells were predominantly expressed in each layer of the internal carotid artery, whereas the expression of parvicellular neurons was dominated in ARC. In the model group, the large and small neurosecretory cells were distributed sparsely in the nerves of PVP; in the acupuncture group, the cells of these two species were distributed regularly; and there were few species of glial cell in the VLM of either the model group or the acupuncture group. In each group, for the in situ hybridization of CGRP mRNA, the small neurosecretory cells were expressed predominately in the PVP, while, the expression of glial cell nuclei and the cell cytoplasm was dominated in the VLM. Compared with the normal group, the mRNA expression of eNOS in the internal carotid artery and ARC and that of CGRP mRNA in the PVP and VLM was decreased in the model group (P<0.05). In the acupuncture group, when compared with the model group, the mRNA expression of eNOS in the internal carotid artery and ARC and that of CGRP in the PVP and VLM was increased in the acupuncture group (P<0.05). Acupuncture at "antihypertensive acupoint prescription" can upregulate the level of vascular relaxing factors, downregulate the level of contracting factors, enhance the response of relaxing factors in targeting blood vessels and regulating the center. The mechanism may be related to the modulation of the sympathetic-adrenergic autonomic neurotransmitters in the paraventricular nucleus in spontaneous hypertension rats.

Impact of low-to moderate-intensity exercise training on the mRNA expression of purine receptors across various vessels in SHR.

In this study, we developed an exercise training protocol for assessing both blood pressure dynamics and mRNA expression levels of purine receptors in various vascular tissues during physical activity. The objective is to assess the impact of exercise training on blood pressure regulation in spontaneously hypertensive rats (SHR) and purine receptors in vascular tissues. Wistar Kyoto (WKY) and SHR rats were randomly allocated into sedentary (Sed) and exercise training (ExT) groups. Rats in the Sed groups were allowed unrestricted movement, whereas those in the ExT groups underwent a 16-week regimen of low- to moderate-intensity treadmill exercise. Throughout the intervention period, blood pressure measurements and body weight recordings were conducted. Additionally, mRNA expressions of purine receptors P2X1, P2Y1, and P2Y2 in renal artery (RA), internal carotid artery (Int), thoracic aorta (Aor), and caudal artery (Cau) tissues were assessed. In the Sed group, body weight of SHR rats was observed to be lower compared to the three other groups. Over the course of the exercise regimen, blood pressure in the ExT group of SHR rats reduced gradually, converging towards levels similar to those observed in WKY rats by the conclusion of the exercise period. Regarding mRNA expression patterns of P2X1 receptors across the four blood vessels, WKY and SHR rats demonstrated similar sequences, consistently displaying the highest expression levels in the Cau. Conversely, mRNA expressions of P2Y1 and P2Y2 receptors exhibited distinct sequences across the four blood vessels in both WKY and SHR rats. Notably, compared to the Sed group of WKY rats, mRNA expression of P2X1 receptor in the Int of SHR rats revealed an increase, while expressions in the Aor of WKY rats and the Cau of SHR rats decreased following exercise. Expression of P2Y1 receptor mRNA decreased across all four types of blood vessels in SHR rats. Post-exercise, P2Y1 receptor mRNA expression increased in the Aor, decreased in the Cau of WKY rats, and increased in the Int and renal artery (RA) of SHR rats. Conversely, expressions of P2Y2 receptor mRNA decreased in the Int and Aor of SHR rats. Except for the Aor of WKY rats, expressions of P2Y2 receptor mRNA increased in the other arteries of both rat types following exercise. Differences in the distribution of purine receptor subtypes among distinct arterial segments in both WKY and SHR rats were observed. Exercise training was found to enhance mRNA expression levels of P2Y receptors in these rat models. This finding implies that exercise training might reduce hypertension in SHR rats by bolstering the purinergic relaxation response.

GABA-immunoreactivity in Neuroepithelial Bodies of Spontaneously Hypertensive Rats

Neuroepithelial bodies (NEBs) are complex sensory receptors dispersed throughout the intrapulmonary airways. They are composed of pulmonary neuroendocrine cells (PNECs) which have a large amount of dense-core vesicles containing calcitonin gene-related peptide (CGRP), serotonin (5HT), substance P (SP) and δ-aminobutyric acid (GABA). NEBs are densely innervated by vagal sensory terminals, dorsal root afferents and intrinsic motor fibres. Their location, neurochemical composition and dense innervation make NEBs a key component for the regulation of lung homeostasis. Pulmonary arterial hypertension is a rare disease characterized by morphological alterations in the microcirculation of the lungs causing a wide array of complications and high mortality. Spontaneously hypertensive rats (SHRs) are a common model for essential hypertension, that may develop secondary pulmonary hypertension and thus can be used as an animal model to study pulmonary pressure changes. The present study focuses on the immunohistochemical demonstration of GABA in the NEBs and its potential role in the regulation of the pulmonary pressure. Two groups of SHRs were used and age-matched normotensive Wistar Kyoto (WKY) rats served as controls. We found single PNECs and clusters of GABA-immunoreactive cells protruding into the lumen of the intrapulmonary airways in all examined groups of SHRs and in the normotensive WKY rats. However, the expressional levels statistically differed within the two age groups of SHRs and the controls. Specifically, the NEBs and PNECs in 1-month-old SHRs and particularly in 3-month-old SHRs showed more intense GABA-immunostaining compared to the WKY rats. In conclusion, NEBs and PNECs react to the alterations of the pulmonary pressure homeostasis by an increased GABA expression as a preventive or reactive regulation mechanism against developing pulmonary hypertension.

Hypotensive and Cardioprotective Potential of Yellow Bedstraw Extract-Based Oral Liquid in Spontaneously Hypertensive Rats.

This study aimed to prepare, characterize and assess the antioxidant activity of yellow bedstraw extracts (YBEs), focusing on identifying extracts with high antioxidant capacity. The selected extract was loaded into an oral liquid formulation and further investigated for its therapeutic potential in reducing blood pressure and associated complications in spontaneously hypertensive Wistar kyoto rats (SHR). Rats were divided into untreated SHR and SHR treated with a YBE-based oral formulation over four weeks. After treatment, blood pressure was measured, and cardiac function was assessed using the Langendorff technique to simulate ex vivo ischemic conditions. Prooxidant levels were assessed in plasma while antioxidant activity was evaluated in red blood cells. Histological analyses of heart, kidney, and liver samples were conducted to assess pathological changes induced by hypertension. Our results showed that the oral formulation loaded with ethanol YBE effectively reduced blood pressure, preserved myocardial function under ischemic stress, and decreased oxidative stress markers in blood. Importantly, our formulation with YBE demonstrated potential in attenuating structural kidney damage associated with hypertension. Overall, these findings suggest a cardioprotective effect of orally administered YBE formulation, highlighting its potential as an herbal supplement. However, clinical studies are warranted to validate these findings and explore the extract's suitability for clinical use.

MiR-196a-5p hinders vascular smooth muscle cell proliferation and vascular remodeling via repressing BACH1 expression

Hyperproliferation of vascular smooth muscle cells (VSMCs) is a driver of hypertensive vascular remodeling. This study aimed to uncover the mechanism of BTB and CNC homology 1 (BACH1) and microRNAs (miRNAs) in VSMC growth and hypertensive vascular remodeling. With the help of TargetScan, miRWalk, miRDB, and miRTarBase online database, we identified that BACH1 might be targeted by miR-196a-5p, and overexpressed in VSMCs and aortic tissues from spontaneously hypertensive rats (SHRs). Gain- and loss-of-function experiments demonstrated that miR-196a-5p suppressed VSMC proliferation, oxidative stress and hypertensive vascular remodeling. Double luciferase reporter gene assay and functional verification showed that miR-196a-5p cracked down the transcription and translation of BACH1 in both Wistar Kyoto rats (WKYs) and SHRs. Silencing BACH1 mimicked the actions of miR-196a-5p overexpression on attenuating the proliferation and oxidative damage of VSMCs derived from SHRs. Importantly, miR-196a-5p overexpression and BACH1 knockdown cooperatively inhibited VSMC proliferation and oxidative stress in SHRs. Furthermore, miR-196a-5p, if knocked down in SHRs, aggravated hypertension, upregulated BACH1 and promoted VSMC proliferation, all contributing to vascular remodeling. Taken together, targeting miR-196a-5p to downregulate BACH1 may be a promising strategy for retarding VSMC proliferation and hypertensive vascular remodeling.

Renal denervation alleviates vascular remodeling in spontaneously hypertensive rats by regulating perivascular adipose tissue.

Vascular remodeling is the main pathological process that causes the damage of the target organ of hypertension. Perivascular adipose tissue (PVAT) surrounds blood vessels and plays a key role in the pathogenesis of various cardiovascular diseases. This study aimed to investigate the effects of renal denervation (RDN) on hypertensive vascular remodeling and to elucidate the role of PVAT in this process. Male spontaneously hypertensive rat (SHR) and Wistar-Kyoto (WKY) rat were selected. Aortic vascular remodeling was evaluated using hematoxylin and eosin (H&E) staining and Masson's trichrome staining. Morphological changes in the PVAT were observed through H&E and Oil Red O staining. Dihydroethidium was used to measure oxidative stress levels in PVAT, while western blot analysis was used to determine the expression levels of proteins associated with vascular remodeling. The results showed that the aortic medial thickness, media thickness/lumen diameter, collagen volume fraction, and reactive oxygen species (ROS) level in PVAT were significantly higher in the SHR group than in the WKY group. The indexes mentioned above were lower in the SHR-RDN group than in the SHR group. H&E staining revealed that fat droplets in PVAT in the SHR-RDN group became smaller and browning occurred. Moreover, the protein expression of uncoupling protein-1 (UCP-1) and neuregulin 4 (Nrg4) was significantly increased in the SHR-RDN group. In addition, the expression of adiponectin increased and the expression of leptin decreased in the SHR-RDN group compared to the SHR group. In conclusion, RDN can relieve hypertensive vascular remodeling, which may be associated with PVAT.

Oral Supplementation with Betaine Powder Ameliorated High Blood Pressure in Spontaneously Hypertensive Rats.

Supplementation of betaine is associated with improved cardiac health, potentially due to its function in re-methylation of homocysteine, an independent risk factor for cardiovascular diseases. We investigated the effects of oral betaine supplementation on blood pressure homeostasis in spontaneously hypertensive (SHR) rats and Wistar Kyoto (WKY) rats in an 8 week-feeding trial with control (SHR-con and WKY-con) and 1% betaine supplemented (SHR-b and WKY-b) diets. Systolic, diastolic, and mean blood pressure in the SHR-b group were significantly lower at week 8 (p = 0.013, p = 0.011, p = 0.010, respectively). Furthermore, serum nitric oxide (NO) levels were significantly (p < 0.05) improved in the WKY-b and SHR-b groups, suggesting a healthy endothelial function. Additionally, the serum angiotensin I converting enzyme level in SHR-b rats was also significantly lowered, which may have been another reason for lower blood pressure. A significantly higher non-HDL level in the SHR-b group might reflect enhanced lipid secretion into the circulation in the form of very-low-density lipoprotein (VLDL). Betaine is known for its effect on the synthesis of phosphatidylcholine, a key component of VLDL. However, the long-term net outcomes of both blood pressure lowering and serum lipid increment should be further studied.

Vasohibin inhibition improves myocardial relaxation in a rat model of heart failure with preserved ejection fraction.

Heart failure with preserved ejection fraction (HFpEF) is a complex syndrome associated with increased myocardial stiffness and cardiac filling abnormalities. Prior studies implicated increased α-tubulin detyrosination, which is catalyzed by the vasohibin enzymes, as a contributor to increased stabilization of the cardiomyocyte microtubule network (MTN) and stiffness in failing human hearts. We explored whether increased MTN detyrosination contributed to impaired diastolic function in the ZSF1 obese rat model of HFpEF and designed a small-molecule vasohibin inhibitor to ablate MTN detyrosination in vivo. Compared with ZSF1 lean and Wistar Kyoto rats, obese rats exhibited increased tubulin detyrosination concomitant with diastolic dysfunction, left atrial enlargement, and cardiac hypertrophy with a preserved left ventricle ejection fraction, consistent with an HFpEF phenotype. Ex vivo myocardial phenotyping assessed cardiomyocyte mechanics and contractility. Vasohibin inhibitor treatment of isolated cardiomyocytes from obese rats resulted in reduced stiffness and faster relaxation. Acute in vivo treatment with vasohibin inhibitor improved diastolic relaxation in ZSF1 obese rats compared with ZSF1 lean and Wistar Kyoto rats. Vasohibin inhibition also improved relaxation in isolated human cardiomyocytes from both failing and nonfailing hearts. Our data suggest the therapeutic potential for vasohibin inhibition to reduce myocardial stiffness and improve relaxation in HFpEF.

Unraveling psilocybin's therapeutic potential: behavioral and neuroplasticity insights in Wistar-Kyoto and Wistar male rat models of treatment-resistant depression.

Our study aimed to unravel the unknown mechanisms behind the exceptional efficacy of Psilocybin (PSI) in treating treatment-resistant depression (TRD). Focusing on Wistar-Kyoto (WKY) rats with a TRD phenotype and Wistar (WIS) rats as a normative comparison, we investigated behavioral and neuroplasticity-related responses to PSI, striving to shed light on the distinctive features of its antidepressant effects. We set out to assess the behavioral impact of acute and prolonged PSI administration on WKY and WIS rats, employing Novel Object Recognition (NORT), Social Interaction (SI), and Forced Swimming Test (FST). Our secondary objectives involved exploring strain-specific alterations in neuroplasticity-related parameters, including brain-derived neurotrophic factor (BDNF) and activity-regulated cytoskeleton-associated protein (Arc). Conducting post-acute and extended assessments after a single PSI administration, we applied behavioral tests and biochemical analyses to measure serum BDNF levels and neuroplasticity-related parameters in the prefrontal cortex. Statistical analyses were deployed to discern significant differences between the rat strains and assess the impact of PSI on behavioral and biochemical outcomes. Our findings uncovered significant behavioral disparities between WKY and WIS rats, indicating passive behavior and social withdrawal in the former. PSI demonstrated pronounced pro-social and antidepressant effects in both strains, each with its distinctive temporal trajectory. Notably, we identified strain-specific variations in BDNF-related signaling and observed the modulation of Arc expression in WKY rats. Our study delineated mood-related behavioral nuances between WKY and WIS rat strains, underscoring the antidepressant and pro-social properties of PSI in both groups. The distinct temporal patterns of observed changes and the identified strain-specific neuroplasticity alterations provide valuable insights into the TRD phenotype and the mechanisms underpinning the efficacy of PSI.