Effect Of Perivascular Adipose Tissue Research Articles

Abstract P226: Sex-Dependent Effects of Perivascular Adipose Tissue on Arterial Stiffness in Hypertensive

Dillon McClintock, Department of Mechanical Engineering, Michigan State University, East Lansing, MI Sydney Bush, Department of Mechanical Engineering, Michigan State University, East Lansing, MI Lisa Sather, Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI Nathan Tykocki, Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI Adam Lauver, Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI Stephanie W Watts, Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI Sara Roccabianca, Department of Mechanical Engineering, Michigan State University, East Lansing, MI Perivascular adipose tissue (PVAT) plays a crucial role in arterial mechanics by significantly reducing arterial stiffness in the thoracic aorta in normotensive rats. This study aims to test the hypothesis that impact of PVAT on arterial stiffness is sex-dependent in an adiposity-driven hypertension rat model. Thoracic aorta from male and female Dahl Salt-Sensitive rats were fed control (10% fat-CD) and high-fat (60% fat-HFD) diets over 16 weeks. Uniaxial mechanical tests were then conducted on aorta samples with PVAT (+PVAT) and without PVAT (-PVAT). In -PVAT samples, arterial wall stiffness at 20% stretch (mimicking in vivo conditions), was higher in males compared to females on a HFD but not on a CD. HFD rats also had higher systolic blood pressures, but the increase was significant only in females. +PVAT samples’ stiffness was reduced by a 95% factor in all groups as compared to -PVAT samples. Furthermore, when including PVAT, the sex difference in the HF diet group was absent. These results suggest that PVAT has a beneficial effect that is preserved in this adiposity-driven hypertension animal model after 16 weeks on diet. Furthermore, remodeling of the arterial wall is more pronounced in male versus female rats and the inclusion of PVAT dampens this sex difference.

Correction to: Leptin-Dependent and Leptin-Independent Paracrine Effects of Perivascular Adipose Tissue on Neointima Formation.

Correction to: Leptin-Dependent and Leptin-Independent Paracrine Effects of Perivascular Adipose Tissue on Neointima Formation.

Signals From Inflamed Perivascular Adipose Tissue Contribute to Small-Vessel Dysfunction in Women With Human Immunodeficiency Virus.

People with the human immunodeficiency virus (PWH) have microvascular disease. Because perivascular adipose tissue (PVAT) regulates microvascular function and adipose tissue is inflamed in PWH, we tested the hypothesis that PWH have inflamed PVAT that impairs the function of their small vessels. Subcutaneous small arteries were dissected with or without PVAT from a gluteal skin biopsy from 11 women with treated HIV (WWH) aged < 50 years and 10 matched women without HIV, and studied on isometric myographs. Nitric oxide (NO) and reactive oxygen species (ROS) were measured by fluorescence microscopy. Adipokines and markers of inflammation and ROS were assayed in PVAT. PVAT surrounding the small arteries in control women significantly (P < .05) enhanced acetylcholine-induced endothelium-dependent relaxation and NO, and reduced contractions to thromboxane and endothelin-1. However, these effects of PVAT were reduced significantly (P < .05) in WWH whose PVAT released less adiponectin but more markers of ROS and inflammation. Moderation of contractions by PVAT were correlated positively with adipose adiponectin. PVAT from WWH has oxidative stress, inflammation, and reduced release of adiponectin, which may contribute to enhanced contractions and therefore could promote small-artery dysfunction.

Endothelium-Independent Anti-Contractile Effect of Rat Aorta Perivascular Adipose Tissue at Control and Metabolic Disorders Induced by the Cafe Diet

The use of high-calorie nutrition can lead to morpho-functional changes of the vascular bed that have clinical importance, however, the modulatory effect of perivascular adipose tissue (PVAT) on the vascular system in this process remains poorly characterized. The aim of this work was to study the direct effect of PVAT on the contractile activity of rat aortic smooth muscle in metabolic disorders that occur when using the cafe diet (CD). It was shown that 7 weeks of keeping animals on this diet led to excessive accumulation of visceral adipose tissue, disorders of carbohydrate and lipid metabolism, manifested in the form of hyperglycemia and hypertriglyceridemia, which characterizes the development of the metabolic syndrome. An important functional role of PVAT in the regulation of vascular tone was demonstrated using wire myography on annular without endothelium segments of the thoracic aorta of the rat. In the control group of animals on a standard diet, the presence of PVAT reduced vasoconstriction caused by stimulation by phenylephrine. In the experimental group, in rats with the metabolic syndrome caused by DC, there was a decrease in the protective effect of PVAT. The implementation of this effect was carried out with the participation of voltage-dependent and/or Ca2+-activated K+-channels of smooth muscles, while the involvement of ATP-sensitive K+-channels was weak and independent from metabolic changes caused by the use of CD. Part of the anticontractile effect of PVAT was mediated through nitric oxide (NO) produced by PVAT itself. Under metabolic changes caused by CD, the endothelium-independent anticontractile effect of NO is completely eliminated without changing the sensitivity of vascular smooth muscles to it.

Abstract 13047: The Modulatory Effects of Perivascular Adipose Tissue on the Renal Arterial Vasorelaxation and Its Relationship With Kidney Function in Metabolic Syndrome

Metabolic syndrome (MetS) is a cluster condition that increases the risk of cardiovascular diseases and type 2 diabetes. Perivascular adipose tissue (PVAT) regulates the arterial tone. We have demonstrated that the renal arterial PVAT enhances the vasorelaxation response in MetS model strains, SHRSP.Z- Lepr fa /IzmDmcr rats (SPZF) and SHR/NDmcr-cp rats (CP). Furthermore, we have found that overactivation of angiotensin II type 1 receptor (AT1R) signaling and a decrease in apelin levels in PVAT leads to a decline in compensatory PVAT effects. MetS is associated with chronic kidney disease, and the dysfunction of the PVAT favoring the vasorelaxation response could be a reason for kidney disease development. Therefore, we investigated the relationship between PVAT function and kidney function using MetS model rats.Renal arteries were isolated from the male and female SPZF and CP at 23 weeks of age. Vasorelaxation and mRNA transcript levels in PVAT were examined using organ bath methods and quantitative real-time polymerase chain reaction, respectively. Systolic blood pressure (sBP) was measured using a tail-cuff method. Insulin, glucose, and creatinine in the serum and protein in the urine were measured using commercial kits and eGFR, and the HOMA-IR were calculated.sBP was higher in SPZF than CP, but lower in females than males. HOMA-IR and urine protein levels were the lowest, while eGFR and enhancing effects of PVAT on acetylcholine-induced relaxations were the highest in female CP among the groups. eGFR was negatively correlated with sBP, HOMA-IR, and urinary protein levels. The enhancements of relaxations by PVAT were negatively correlated with sBP, HOMA-IR, and AT1R activity in PVAT.This study suggests that the insulin resistance and high blood pressure are associated with PVAT dysfunction, resulting from AT1 activation in PVAT, while it does not support the hypothesis that the disappearance of the effects of PVAT directly leads to kidney dysfunction.

AT1 receptors modulate ethanol-induced loss of anticontractile effect of perivascular adipose tissue

Ethanol consumption activates renin-angiotensin-aldosterone system (RAAS), which plays a major role in the pro-contractile and hypertensive effects linked to ethanol. We hypothesized that ethanol consumption induces loss of the anticontractile effect of perivascular adipose tissue (PVAT)through RAAS-mediated mechanisms. We examined the contribution of angiotensin II type 1 receptors (AT1R) to ethanol-induced PVAT dysfunction. With this purpose, male Wistar Hannover rats were treated with ethanol 20 % (in volume ratio) and/or losartan (antagonist of AT1R; 10 mg/kg/day, gavage) for 9 weeks. Losartan prevented the increase in blood pressure and the loss of the anticontractile effect of PVAT induced by ethanol consumption. PVAT dysfunction occurred after 3 and 9 weeks of treatment with ethanol in an endothelium-dependent manner. Blockade of AT1R prevented ethanol-induced reduction of adiponectin levels in PVAT from ethanol-treated rats. Functional assays revealed that ethanol impaired the anticontractile effect of PVAT-derived angiotensin (1–7) and endothelial nitric oxide (NO). In conclusion, AT1R are implicated in ethanol-induced loss of the anticontractile effect of PVAT. In PVAT, AT1R activation decreases the production of adiponectin, a PVAT-derived factor that promotes vasorelaxation in an endothelium-dependent manner. In the endothelium, AT1R favors the production of superoxide (O2•-) leading to a reduction in NO bioavailability. These responses impair the vasodilator action induced by PVAT-derived angiotensin (1–7), which occurs via Mas receptors located in endothelial cells. Ethanol-induced PVAT dysfunction favors vascular hypercontractility, a response that could contribute to the hypertensive state associated with ethanol consumption.

Reactive Oxygen Species Are Central Mediators of Vascular Dysfunction and Hypertension Induced by Ethanol Consumption.

Consumption of high amounts of ethanol is a risk factor for development of cardiovascular diseases such as arterial hypertension. The hypertensive state induced by ethanol is a complex multi-factorial event, and oxidative stress is a pathophysiological hallmark of vascular dysfunction associated with ethanol consumption. Increasing levels of reactive oxygen species (ROS) in the vasculature trigger important processes underlying vascular injury, including accumulation of intracellular Ca2+ ions, reduced bioavailability of nitric oxide (NO), activation of mitogen-activated protein kinases (MAPKs), endothelial dysfunction, and loss of the anticontractile effect of perivascular adipose tissue (PVAT). The enzyme nicotinamide adenine dinucleotide phosphate (NADPH) oxidase plays a central role in vascular ROS generation in response to ethanol. Activation of the renin-angiotensin-aldosterone system (RAAS) is an upstream mechanism which contributes to NADPH oxidase stimulation, overproduction of ROS, and vascular dysfunction. This review discusses the mechanisms of vascular dysfunction induced by ethanol, detailing the contribution of ROS to these processes. Data examining the association between neuroendocrine changes and vascular oxidative stress induced by ethanol are also reviewed and discussed. These issues are of paramount interest to public health as ethanol contributes to blood pressure elevation in the general population, and it is linked to cardiovascular conditions and diseases.

Abstract P232: New Anti-contractile Effect Of Skeletal Muscle Is Lost In Hypertension

Since the discovery of the anti-contractile effect of perivascular adipose tissue (PVAT), it has been established that it has a crucial role in vascular function and diseases, including hypertension. However, PVAT has a minimal role in arteries surrounded by skeletal muscles (SM) compared to other vessels. During physical exercise, SM releases several factors ("myokines") that can modulate blood flow, but it is unclear if SM directly controls vascular tone in physiological conditions. The type of SM, glycolytic or oxidative, may also affect vascular dynamics. We hypothesized that SM exhibits an anti-contractile effect crucial for vascular function, which is lost in hypertension. Femoral (FA) and carotid (CA) arteries, adjacent to glycolytic and oxidative SM, respectively, from male and female SHR and Wistar (W) (12-weeks old) rats were mounted in a wire myograph in the absence (-SM) or presence (+SM) of attached or de-attached SM. Concentration-response curves (1nM-100μM) to serotonin (5-HT), phenylephrine (Phe), and thromboxane A2 analog (U46619) were performed. The presence of SM reduced contraction in FA from male (AUC 5-HT: -SM: 442±1 vs. +SM 339±2; p&gt;0.05) and female W rats (AUC: 5-HT: -SM 258.7 ± 18.5 vs. +SM 277±21; p&gt;0.05). Similarly, SM-induced anti-contractile effects were observed in Phe and U46619 curves and in de-attached SM. The anti-contractile effect was absent in W rats CA (AUC: 5-HT: Male: -SM 270±19 vs. +SM 257 ± 25; Female: -SM 250±35 vs. +SM 258±32). Lactate dehydrogenase inhibitor (GSK2837808A, 10nM) abolished the SM anti-contractile effect. In SHR, this anti-contractile effect in FA was not observed (AUC: 5-HT: -SM 103±27 vs. +SM 94±25). FA from SHR showed hypo-contractility to 5-HT (32%) and increased smoothelin expression, an atrophy marker, when measured by Western blot (AU: FA: W: 22861±4504 vs. SHR: 6065±1026; p&gt;0.05). Tests of plantarflexion were performed in vivo to assess SM function. SHR showed a reduction in tetanic contraction (27%), isometric twitch force (27%), and fatigue (22%). These data reveal a new anti-contractile effect of glycolytic SM mediated by lactate and lost in hypertension. Therefore, paracrine and endocrine factors from SM represent a new frontier of vascular physiology research.

Lipoprotein lipase underlies the vascular anti-contractile effect of perivascular adipose tissue (PVAT)

Physiologically, perivascular adipose tissue (PVAT) exerts an anti-contractile effect on the vasculature. This effect is mediated by the biosynthesis and liberation of a myriad of anti-contractile molecules (e.g., adipokines). However, this anti-contractile function generally is lost with aging and cardiovascular diseases such as hypertension and diabetes. Lipoprotein lipase (LPL) is an enzyme classically known for hydrolyzing triglycerides into free fatty acids and glycerol. However, it is unknown whether LPL underlies the anti-contractile effect of PVAT. Specifically, we hypothesized that by inhibiting lipoprotein lipase (LPL) activity with Atglistatin, we would abolish the anti-contractile effect of PVAT. To test this hypothesis, mesenteric resistance arteries (MRA), with and without PVAT, were isolated from 3-month-old male Wistar rats and mounted on a wire myograph. Phenylephrine concentration-response curves were performed with and without Atglistatin (10 -5 M). As expected, PVAT exerted a significant anti-contractile effect on phenylephrine-induced contraction [Emax (mN), -PVAT-vehicle: 18.1±3.0 vs. +PVAT-vehicle: 7.1±1.1, p&lt;0.05]. Incubation of MRA with intact PVAT with Atglistatin significantly increased contraction [Emax (mN), +PVAT-vehicle: 7.1±1.1vs. +PVAT-Atglistatin: 22.6±4.2, p&lt;0.05], suggesting that LPL is indeed important for the anti-contractile effect of PVAT. Crucially, no difference was observed with Atglistatin in MRA lacking PVAT [Emax (mN), -PVAT-vehicle: 18.1±3.0 vs. -PVAT-Atglistatin: 18.5±2.9, p&gt;0.05], indicating that Atglistatin was not increasing contraction via non-PVAT-dependent mechanisms. Overall, these data suggest that LPL is an important mechanism mediating the anti-contractile effect of PVAT and that reduced LPL activity could be contributing to pro-contractile PVAT in aging and cardiovascular diseases. NHLBI (R00HL151889), NIGMS (1P20GM103641 - Pilot Project), UofSC SOM (Startup funds) 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.

Identification of a biomarker and immune infiltration in perivascular adipose tissue of abdominal aortic aneurysm.

Objective: Abdominal aortic aneurysm (AAA) refers to unusual permanent dilation of the abdominal aorta, and gradual AAA expansion can lead to fatal rupture. However, we lack clear understanding of the pathogenesis of this disease. The effect of perivascular adipose tissue (PVAT) on vascular functional status has attracted increasing attention. Here, we try to identify the potential mechanisms linking AAA and PVAT. Methods: We downloaded dataset GSE119717, including 30 dilated AAA PVAT samples and 30 non-dilated aorta PVAT samples from AAA cases, from Gene Expression Omnibus to identify differentially expressed genes (DEGs). We performed pathway enrichment analysis by Metascape, ClueGo and DAVID to annotate PVAT functional status according to the DEGs. A protein-protein interaction network, the support vector machine (SVM)-recursive feature elimination and the least absolute shrinkage and selection operator regression model were constructed to identify feature genes. Immune infiltration analysis was explored by CIBERSORT. And the correlation between feature gene and immune cells was also calculated. Finally, we used the angiotensin II (Ang II)-ApoE−/− mouse model of AAA to verify the effect of feature gene expression by confirming protein expression using immunohistochemistry and western blot. Results: We identified 22 DEGs, including 21 upregulated genes and 1 downregulated gene. The DEGs were mainly enriched in neutrophil chemotaxis and IL-17 signaling pathway. FOS was identified as a good diagnostic feature gene (AUC = 0.964). Immune infiltration analysis showed a higher level of T cells follicular helper, activated NK cells, Monocytes, activated Mast cells in AAA group. And FOS was correlated with immune cells. Immunohistochemistry and western blot confirmed higher FOS expression in PVAT of the AAA mouse model compared to control group. Conclusion: The differentially expressed genes and pathways identified in this study provide further understanding of how PVAT affects AAA development. FOS was identified as the diagnostic gene. There was an obvious difference in immune cells infiltration between normal and AAA groups.

Impaired Endothelial Function and Enhanced Contractility of Microarterioles from Persons Living with Human Immunodeficiency Virus (HIV+) is Mediated by Inflamed Perivascular Adipose Tissue

This research investigates the mechanisms that contribute to the enhanced cardiovascular disease (CVD) in HIV+ persons. It tests the hypothesis that perivascular adipose tissue (PVAT) mediates the microvascular dysfunction. Subcutaneous microarterioles were dissected from gluteal skin biopsies from 11 HIV+ and 10 matched control women aged &lt; 50 years who were free of CVD risk factors (except increased BMI). Arterioles were mounted on isometric myographs with or without PVAT. Nitric oxide (NO) and reactive oxygen species (ROS) were measured by fluorescence microscopy. PVAT significantly (P &lt; 0.05) enhanced endothelium‐ dependent relaxation (EDR) and NO with acetylcholine and moderated contractions with thromboxane and endothelin 1 (ET1). But these effects of PVAT were significantly (P &lt; 0.05) diminished in HIV+ vs control subjects. Although microarterioles from HIV+ had enhanced ROS with ET1. ROS was not affected by PVAT. Incubated PVAT from HIV+ persons released significantly (P &lt; 0.05) more leptin (47 +/‐ 8 vs 22 +/‐ 3 ng · mg‐1) and less adiponectin (3.0 +/‐ 0.4 vs 4.6 +/‐ 0.5 µg · mg‐1) but more 8‐isoprostane F2α (2.5 +/‐ 0.4 vs 1.3 +/‐ 0.3 µmol · mg‐1) and inflammatory cytokines such as TNFα (11 +/‐ 1 vs 5 +/‐ 1 pg · mg‐1).ConclusionPVAT from young HIV+ women has enhanced oxidative stress and inflammation and impaired ability to enhance microarteriolar NO and moderated contractility. Thus, PVAT and adipokines should be novel foci for therapy to reduce CVD in HIV+ persons.

The Vasoactive Effect of Perivascular Adipose Tissue and Hydrogen Sulfide in Thoracic Aortas of Normotensive and Spontaneously Hypertensive Rats.

The objective of this study was to investigate the vasoregulatory role of perivascular adipose tissue (PVAT) and its mutual interaction with endogenous and exogenous H2S in the thoracic aorta (TA) of adult normotensive Wistar rats and spontaneously hypertensive rats (SHRs). In SHRs, hypertension was associated with cardiac hypertrophy and increased contractility. Regardless of the strain, PVAT revealed an anticontractile effect; however, PVAT worsened endothelial-dependent vasorelaxation. Since H2S produced by both the vascular wall and PVAT had a pro-contractile effect in SHRs, H2S decreased the sensitivity of adrenergic receptors to noradrenaline in Wistar rats. While H2S had no contribution to endothelium-dependent relaxation in Wistar rats, in SHRs, H2S produced by the vascular wall had a pro-relaxant effect. We observed a larger vasorelaxation induced by exogenous H2S donor in SHRs than in Wistar rats. Additionally, in the presence of PVAT, this effect was potentiated. We demonstrated that PVAT of the TA aggravated endothelial function in SHRs. However, H2S produced by the TA vascular wall had a pro-relaxation effect, and PVAT revealed anti-contractile activity mediated by the release of an unknown factor and potentiated the vasorelaxation induced by exogenous H2S. All these actions could represent a form of compensatory mechanism to balance impaired vascular tone regulation.

The Role of Perivascular Adipose Tissue in Early Changes in Arterial Function during High-Fat Diet and Its Combination with High-Fructose Intake in Rats

The aim of the current study was to evaluate the influence of a high-fat diet and its combination with high-fructose intake on young normotensive rats, with focus on the modulatory effect of perivascular adipose tissue (PVAT) on the reactivity of isolated arteries. Six-week-old Wistar–Kyoto rats were treated for 8 weeks with a control diet (10% fat), a high-fat diet (HFD; 45% fat), or a combination of the HFD with a 10% solution of fructose. Contractile and relaxant responses of isolated rat arteries, with preserved and removed PVAT for selected vasoactive stimuli, were recorded isometrically by a force displacement transducer. The results demonstrated that, in young rats, eight weeks of the HFD might lead to body fat accumulation and early excitation of the cardiovascular sympathetic nervous system, as shown by increased heart rate and enhanced arterial contractile responses induced by endogenous noradrenaline released from perivascular sympathetic nerves. The addition of high-fructose intake deteriorated this state by impairment of arterial relaxation and resulted in mild elevation of systolic blood pressure; however, the increase in arterial neurogenic contractions was not detected. The diet-induced alterations in isolated arteries were observed only in the presence of PVAT, indicating that this structure is important in initiation of early vascular changes during the development of metabolic syndrome.

Abstract P171: Comparison Of Modulation Of Renal Arterial Tone By Perivascular Adipose Tissue Between Two Animal Models Of Metabolic Syndrome

Sex differences have recently been noticed in the regulation of arterial tone by perivascular adipose tissue (PVAT). In SHRSP.Z- Lepr fa /IzmDmcr (SHRSP.ZF) rats, an animal model of metabolic syndrome (MetS), we demonstrated that mesenteric and renal PVAT in female rats consistently have an enhancing effect on vasodilation at 23 weeks, an age by which the effect of PVAT is impaired in the male rats. This could explain the sex differences in the prevalence of cardiovascular complications in patients with MetS. Therefore, we determined whether the sex difference in PVAT response also occurs in another animal model of MetS, SHR/NDmcr-cp (SHR-cp) rats.Renal arteries were isolated from male and female 23-week-old SHR-cp rats, and ring preparations with and without PVAT were made. After a stable contraction was obtained by phenylephrine administration, vasodilation in response to acetylcholine was examined using organ bath methods.Vasodilation in arteries without PVAT from female rats was smaller than that in arteries without PVAT from male rats, and presence of PVAT in arteries from female rats increased vasodilation to the same level as that observed in arteries without PVAT from male rats. Furthermore, renal PVAT in male rats was shown to have an enhancing effect on vasodilation.The present study did not identify sex differences in renal PVAT-mediated modulation in SHR-cp rats because the enhancing effects of PVAT did not disappear in male SHR-cp rats, in contrast to that observed in male SHRSP.ZF rats at the same age. The difference in PVAT response in male rats between two MetS models may be due to differences in the severity of MetS symptoms, especially blood pressure, between the models.

Deletion of Seipin Attenuates Vascular Function and the Anticontractile Effect of Perivascular Adipose Tissue.

Seipin locates in endoplasmic reticulum (ER) and regulates adipogenesis and lipid droplet formation. Deletion of Seipin has been well-demonstrated to cause severe general lipodystrophy, however, its role in maintaining perivascular adipose tissue (PVAT) and vascular homeostasis has not been directly assessed. In the present study, we investigated the role of Seipin in mediating the anticontractile effect of PVAT and vascular function. Seipin expression in PVAT and associated vessels were detected by qPCR and western-blot. Seipin is highly expressed in PVAT, but hardly in vessels. Structural and functional alterations of PVAT and associated vessels were compared between Seipin−/− mice and WT mice. In Seipin−/− mice, aortic and mesenteric PVAT were significantly reduced in mass and adipose-derived relaxing factors (ADRFs) secretion, but increased in macrophage infiltration and ER stress, as compared with those in WT mice. Aortic and mesenteric artery rings from WT and Seipin−/− mice were mounted on a wire myograph. Vasoconstriction and vasodilation were studied in vessels with and without PVAT. WT PVAT augmented relaxation but not Seipin−/− PVAT, which suggest impaired anticontractile function in PVAT of Seipin−/− mice. Thoracic aorta and mesenteric artery from Seipin−/− mice had impaired contractility in response to phenylephrine (PHE) and relaxation to acetylcholine (Ach). In conclusion, Seipin deficiency caused abnormalities in PVAT morphology and vascular functions. Our data demonstrated for the first time that Seipin plays a critical role in maintaining PVAT function and vascular homeostasis.

Cyclooxygenase-dependent mechanisms mediate in part the anti-dilatory effects of perivascular adipose tissue in uterine arteries from pregnant rats

Uterine perivascular adipose tissue (PVAT) contributes to uterine blood flow regulation in pregnancy, at least in part, due to its effects on uterine artery reactivity. We tested the hypothesis that uterine PVAT modulates the balance between the contribution of nitric oxide synthase (NOS)- and cyclooxygenase (COX)-dependent pathways to acetylcholine (ACh)-induced relaxation in isolated uterine arteries. Concentration-response curves to ACh (1 nM – 30 µM) were performed on uterine arteries from pregnant and non-pregnant rats. Arteries were exposed to Krebs-Henseleit solution (control) or PVAT-conditioned media (PVATmedia) in the presence of the following inhibitors: L-NAME (NOS inhibitor), indomethacin (COX inhibitor), SC560 (COX-1 inhibitor), NS398 (COX-2 inhibitor), SQ 29,548 (thromboxane receptor (TP) inhibitor). In arteries incubated with PVATmedia, the presence of indomethacin increased ACh-induced relaxation, reversing the anti-dilatory effect of PVATmedia. NOS inhibition reduced ACh-induced relaxation in uterine arteries from pregnant rats, and exposure to PVATmedia did not change this effect. Selective inhibition of COX-1 but not COX-2 suppressed relaxation responses to ACh in control arteries. The presence of PVATmedia abolished the effect of COX-1 inhibition. Incubation of uterine arteries from pregnant rats with PVATmedia increased production of thromboxane B2 (TxB2, p = 0.01) but thromboxane receptor (TP) inhibition did not affect the anti-dilatory properties of PVATmedia. In conclusion, inhibition of COX signaling suppressed the anti-dilatory effects of PVATmedia, while PVATmedia had no effect on the contribution of the NOS/NO pathway to ACh-induced relaxation in uterine arteries from pregnant rats, indicating that the anti-dilatory effects of uterine PVAT are mediated in part by COX-dependent mechanisms.

Paracrine Effects of Perivascular Adipose Tissue on Atherogenesis: Role of Extracellular Vesicles‐Mediated Intercellular Communications

Background Development of atherosclerosis depends on the interaction between various factors. Type 2 diabetes accelerates these interactions and predisposes to rapid progression of atherosclerosis. Diminution of vasoprotective effects of perivascular adipose tissue (PVAT) in metabolic disorders suggests a molecular link between diabetes and atherosclerosis. Objectives To assess the paracrine role of the PVAT on the progression of diabetic atherosclerosis, via intercellular communications between PVAT and the underlying vasculature. Methods Periaortic adipose tissue from Type 2 diabetic (db/db) mice were transplanted around the right common carotid arteries of ApoE-/- mice, followed by 16 weeks of atherogenic diet. Carotid arteries and adipose tissues were assessed for lesion formation and inflammatory markers, respectively. Adipose stem cells (ASCs) from PVAT were treated with lipopolysaccharide (1µg/ml), palmitate (200µM), and high-glucose (42 mM) for 24 hrs (denoted as P-ASCs) to mimic type 2 diabetes-associated metabolic alterations. Small extracellular vesicles (sEV) were isolated from the conditioned media. Aortic vascular smooth muscle cells (SMCs) were incubated with ASC-derived sEV (25µg/ml). The migratory potential of SMCs was evaluated by wound healing assay. Results Histological analysis displayed accelerated atherogenic plaque formation with transplantation of type 2 diabetic PVAT around the carotid arteries of ApoE-/- mice, which is otherwise resistant to plaque formation. Pro-inflammatory markers were significantly increased in periaortic adipose tissue from db/db compared to WT. sEV secreted from P-ASCs greatly enhanced the SMC migration when compared with the control ASCs. Conclusions Our data shows type 2 diabetes-accelerated progression of atherosclerosis is mediated by PVAT-derived sEV.

Melatonin reverses the loss of the anticontractile effect of perivascular adipose tissue in obese rats.

Perivascular adipose tissue (PVAT) undergoes functional changes in obesity. Increased oxidative stress is a central mechanism whereby obesity induces loss of the anticontractile effect of PVAT. Melatonin is an antioxidant that displays vasoprotective action in cardiovascular disease. Here, we sought to investigate whether melatonin would restore the anticontractile effect of periaortic PVAT in obesity. Male Wistar Hannover rats were treated for 10weeks with a high-calorie diet. Melatonin (5mg/kg/d, p.o., gavage) was administered for 2weeks. Functional findings showed that obesity-induced loss of the anticontractile effect of PVAT and treatment with melatonin reversed this response. Tiron [a scavenger of superoxide anion (O2 - )] restored the anticontractile effect of PVAT in aortas from obese rats, suggesting a role for reactive oxygen species (ROS) in such response. Decreased superoxide dismutase (SOD) activity and augmented levels of ROS were detected in periaortic PVAT from obese rats. These responses were accompanied by decreased levels of nitric oxide (NO) in PVAT. Treatment with melatonin restored SOD activity, decreased ROS levels, and increased NO bioavailability in PVAT from obese rats. Here, we first reported the beneficial effects of melatonin in periaortic PVAT in obesity. Melatonin reversed the adverse effects of obesity in PVAT that included overproduction of ROS, reduced SOD activity, and decreased bioavailability of NO. Therefore, PVAT may constitute an important target for the treatment of obesity-induced vascular dysfunction and melatonin emerges as a potential tool in the management of the vascular complications induced by obesity.

Anticontractile Effect of Perivascular Adipose Tissue But Not of Endothelium Is Enhanced by Hydrogen Sulfide Stimulation in Hypertensive Pregnant Rat Aortae.

Perivascular adipose tissue (PVAT) modulates the vascular tone. Hydrogen sulfide (H2S) is synthetized by cystathionine gamma-lyase (CSE) in brown PVAT. Modulation of vascular contractility by H2S is, in part, adenosine triphosphate (ATP)-sensitive potassium channels dependent. However, the role of PVAT-derived H2S in hypertensive pregnancy (HTN-Preg) is unclear. Therefore, we aimed to examine the involvement of H2S in the anticontractile effect of PVAT in aortae from normotensive and hypertensive pregnant rats. To this end, phenylephrine-induced contractions in the presence and absence of PVAT and endothelium in aortae from normotensive pregnant (Norm-Preg) and HTN-Preg rats were investigated. Maternal blood pressure, fetal-placental parameters, angiogenesis-related biomarkers, and H2S levels were also assessed. We found that circulating H2S is elevated in hypertensive pregnancy associated with angiogenic imbalance, fetal and placental growth restrictions, which revealed that there is H2S pathway activation. Moreover, under stimulated H2S formation PVAT, but not endothelium, reduced phenylephrine-induced contractions in aortae from HTN-Preg rats. Also, H2S synthesis inhibitor abolished anticontractile effects of PVAT and endothelium. Furthermore, anticontractile effect of PVAT, but not of endothelium, was eliminated by ATP-sensitive potassium channels blocker. In accordance, increases in H2S levels in PVAT and placenta, but not in aortae without PVAT, were also observed. In conclusion, anticontractile effect of PVAT is lost, at least in part, in HTN-Preg aortae and PVAT effect is ATP-sensitive potassium channels dependent in normotensive and hypertensive pregnant rat aortae. PVAT but not endothelium is responsive to the H2S stimulation in hypertensive pregnant rat aortae, implying a key role for PVAT-derived H2S under endothelial dysfunction.

Abstract P224: Cyclooxygenase-dependent Mechanisms Mediate In Part The Anti-dilatory Effects Of Uterine Perivascular Adipose Tissue In Rat Pregnancy

Introduction: Uterine perivascular adipose tissue (PVAT) contributes to uterine blood flow regulation in pregnancy, at least in part, due to its effects on uterine artery tone. We hypothesized that the anti-dilatory effects of uterine PVAT are mediated by vascular nitric oxide synthase (NOS)- and cyclooxygenase (COX)-dependent mechanisms. Methods: Main uterine arteries from pregnant and non-pregnant rats were mounted onto a wire myograph. Concentration-response curves to acetylcholine (ACh, 10 -9 - 3x10 -5 M) were performed on arteries exposed to physiological salt solution or PVAT-conditioned media (PVAT media ) in the presence of the following inhibitors: a) L-NAME (NOS inhibitor, 100 μM), b) indomethacin (COX inhibitor, 10 μM), c) SC560 (COX-1 inhibitor, 1 μM), d) NS398 (COX-2 inhibitor, 1 μM)]. Results: NOS inhibition abolished ACh-induced relaxation in uterine arteries from pregnant rats and exposure to PVAT media did not change this effect [AUC, (-)PVAT media : 244.6 ± 18.1 vs. (-)PVAT media /(+)L-NAME: 52.64 ± 7.4, p &lt; 0.0001; (+)PVAT media : 202.4 ± 15.5 vs. (+)PVAT media /(+)L-NAME: 56.17 ± 11.3, p &lt; 0.0001]. Indomethacin suppressed ACh-induced relaxation in uterine arteries from pregnant rats [AUC, (-)PVAT media : 243.6 ± 6.6 vs. (-)PVAT media /(+)Indomethacin: 123.6 ± 12.3, p &lt; 0.0001] but not in non-pregnant rats (p&gt;1.0). In arteries incubated with PVAT media , the presence of indomethacin increased ACh-induced relaxation [AUC, (+)PVAT media : 125.2 ± 11.4 vs. (+)PVAT media /(+)Indomethacin: 179.1 ± 14.7, p = 0.01]. COX-1 but not COX-2 inhibition suppressed relaxation responses to ACh [AUC, COX-1 inhibition, (-)PVAT media : 244.6 ± 12.0 vs. (-)PVAT media /(+)SC560: 142.4 ± 15.4, p = 0.02; COX-2 inhibition, (-)PVAT media vs. (-)PVAT media /(+)NS398, p=0.1). The anti-dilatory effects of PVAT were not observed in the presence of SC560 or NS398 (p&gt;0.05). Exposure to PVAT media increased the protein content of COX-1 (p=0.05) and COX-2 (p=0.03) and the production of thromboxane B 2 (p=0.01) in uterine arteries from pregnant rats. Conclusion: The anti-dilatory effects of PVAT-derived factors on uterine arteries are mediated in part by COX-derived products and this mechanism is specific to pregnancy.