1
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Wang M, Geng X, Li K, Wang Y, Duan X, Hou C, Zhao L, Zhou H, Zhao D. Berberine ameliorates mesenteric vascular dysfunction by modulating perivascular adipose tissue in diet-induced obese in rats. BMC Complement Med Ther 2022; 22:198. [PMID: 35879716 PMCID: PMC9310483 DOI: 10.1186/s12906-022-03667-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 07/04/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Berberine (BBR) has been found to have antiobesity effects, and obesity can lead to adipose tissue degeneration. As a special adipose tissue, perivascular adipose tissue (PVAT) is closely related to vascular function and affects vasoconstriction and relaxation. What happens to PVAT in the early stages of diet-induced obesity and how BBR affects vascular function is the focus of our experimental study.
Methods
Sprague–Dawley rats were fed a high-fat diet (fat 34% kcal) for 4 weeks to simulate early obesity. Obese rats were treated with BBR (200 mg/kg) or metformin (MET, 100 mg/kg) by gavage for 2 weeks. The mesenteric arterioles were studied by atomic force microscopy (AFM). The force vs. time curves were observed and analysed to indicate vascular function. Nitric oxide (NO) and noradrenaline (NA) release was quantified using an organ bath with fluorescence assays and ELISA, respectively. Network pharmacology was used to analyse the overlapping targets related to BBR and obesity-related diseases, and the expression of NOS in mesenteric PVAT was further analysed with immunohistochemistry and real-time PCR. The serum inflammatory factor levels were tested.
Results
BBR significantly reduced the levels of blood glucose, blood lipids and inflammatory factors in serum. It also effectively improved abnormal mesenteric vasoconstriction and relaxation in obese rats. There was no significant change in mesenteric vascular structure, but NO production and eNOS expression were significantly increased in mesenteric PVAT (P < 0.01), and NA was decreased (P < 0.05) in obese rats. All these changes in the mesenteric arterioles and PVAT of obese rats were reversed by treatment with BBR and MET.
Conclusions
In diet-induced obesity in rats, the function of vasoconstriction and relaxation in mesenteric arterioles is altered, NO is increased, and NA is decreased in mesenteric PVAT. All these changes were reversed by BBR, suggesting a novel effect of BBR in ameliorating mesenteric vascular dysfunction by regulating PVAT.
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Shi Z, Zhao D, Cassaglia PA, Brooks VL. Sites and sources of sympathoexcitation in obese male rats: role of brain insulin. Am J Physiol Regul Integr Comp Physiol 2020; 318:R634-R648. [PMID: 31967846 PMCID: PMC7099464 DOI: 10.1152/ajpregu.00317.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 01/13/2020] [Accepted: 01/13/2020] [Indexed: 12/21/2022]
Abstract
In males, obesity increases sympathetic nerve activity (SNA), but the mechanisms are unclear. Here, we investigate insulin, via an action in the arcuate nucleus (ArcN), and downstream neuropathways, including melanocortin receptor 3/4 (MC3/4R) in the hypothalamic paraventricular nucleus (PVN) and dorsal medial hypothalamus (DMH). We studied conscious and α-chloralose-anesthetized Sprague-Dawley rats fed a high-fat diet, which causes obesity prone (OP) rats to accrue excess fat and obesity-resistant (OR) rats to maintain fat content, similar to rats fed a standard control (CON) diet. Nonspecific blockade of the ArcN with muscimol and specific blockade of ArcN insulin receptors (InsR) decreased lumbar SNA (LSNA), heart rate (HR), and mean arterial pressure (MAP) in OP, but not OR or CON, rats, indicating that insulin supports LSNA in obese males. In conscious rats, intracerebroventricular infusion of insulin increased MAP only in OP rats and also improved HR baroreflex function from subnormal to supranormal. The brain sensitization to insulin may elucidate how insulin can drive central SNA pathways when transport of insulin across the blood-brain barrier may be impaired. Blockade of PVN, but not DMH, MC3/4R with SHU9119 decreased LSNA, HR, and, MAP in OP, but not OR or CON, rats. Interestingly, nanoinjection of the MC3/4R agonist melanotan II (MTII) into the PVN increased LSNA only in OP rats, similar to PVN MTII-induced increases in LSNA in CON rats after blockade of sympathoinhibitory neuropeptide Y Y1 receptors. ArcN InsR expression was not increased in OP rats. Collectively, these data indicate that obesity increases SNA, in part via increased InsR signaling and downstream PVN MC3/4R.
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Affiliation(s)
- Zhigang Shi
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
| | - Ding Zhao
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
- School of Pharmacy, Hebei Medical University, Shijiazhuang, People's Republic of China
| | - Priscila A Cassaglia
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
| | - Virginia L Brooks
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
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3
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Mahata SK, Corti A. Chromogranin A and its fragments in cardiovascular, immunometabolic, and cancer regulation. Ann N Y Acad Sci 2019; 1455:34-58. [PMID: 31588572 PMCID: PMC6899468 DOI: 10.1111/nyas.14249] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 09/09/2019] [Accepted: 09/13/2019] [Indexed: 12/11/2022]
Abstract
Chromogranin A (CgA)-the index member of the chromogranin/secretogranin secretory protein family-is ubiquitously distributed in endocrine, neuroendocrine, and immune cells. Elevated levels of CgA-related polypeptides, consisting of full-length molecules and fragments, are detected in the blood of patients suffering from neuroendocrine tumors, heart failure, renal failure, hypertension, rheumatoid arthritis, and inflammatory bowel disease. Full-length CgA and various CgA-derived peptides, including vasostatin-1, pancreastatin, catestatin, and serpinin, are expressed at different relative levels in normal and pathological conditions and exert diverse, and sometime opposite, biological functions. For example, CgA is overexpressed in genetic hypertension, whereas catestatin is diminished. In rodents, the administration of catestatin decreases hypertension, cardiac contractility, obesity, atherosclerosis, and inflammation, and it improves insulin sensitivity. By contrast, pancreastatin is elevated in diabetic patients, and the administration of this peptide to obese mice decreases insulin sensitivity and increases inflammation. CgA and the N-terminal fragment of vasostatin-1 can enhance the endothelial barrier function, exert antiangiogenic effects, and inhibit tumor growth in animal models, whereas CgA fragments lacking the CgA C-terminal region promote angiogenesis and tumor growth. Overall, the CgA system, consisting of full-length CgA and its fragments, is emerging as an important and complex player in cardiovascular, immunometabolic, and cancer regulation.
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Affiliation(s)
- Sushil K Mahata
- VA San Diego Healthcare System, San Diego, California.,Metabolic Physiology & Ultrastructural Biology Laboratory, Department of Medicine, University of California, San Diego, La Jolla, California
| | - Angelo Corti
- IRCCS San Raffaele Scientific Institute, San Raffaele Vita-Salute University, Milan, Italy
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4
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Systemic Outcomes of (Pyr 1)-Apelin-13 Infusion at Mid-Late Pregnancy in a Rat Model with Preeclamptic Features. Sci Rep 2019; 9:8579. [PMID: 31189936 PMCID: PMC6561917 DOI: 10.1038/s41598-019-44971-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 05/29/2019] [Indexed: 01/27/2023] Open
Abstract
Preeclampsia is a syndrome with diverse clinical presentation that currently has no cure. The apelin receptor system is a pleiotropic pathway with a potential for therapeutic targeting in preeclampsia. We established the systemic outcomes of (Pyr1)-apelin-13 administration in rats with preeclamptic features (TGA-PE, female transgenic for human angiotensinogen mated to male transgenic for human renin). (Pyr1)-apelin-13 (2 mg/kg/day) or saline was infused in TGA-PE rats via osmotic minipumps starting at day 13 of gestation (GD). At GD20, TGA-PE rats had higher blood pressure, proteinuria, lower maternal and pup weights, lower pup number, renal injury, and a larger heart compared to a control group (pregnant Sprague-Dawley rats administered vehicle). (Pyr1)-apelin-13 did not affect maternal or fetal weights in TGA-PE. The administration of (Pyr1)-apelin-13 reduced blood pressure, and normalized heart rate variability and baroreflex sensitivity in TGA-PE rats compared to controls. (Pyr1)-apelin-13 increased ejection fraction in TGA-PE rats. (Pyr1)-apelin-13 normalized proteinuria in association with lower renal cortical collagen deposition, improved renal pathology and lower immunostaining of oxidative stress markers (4-HNE and NOX-4) in TGA-PE. This study demonstrates improved hemodynamic responses and renal injury without fetal toxicity following apelin administration suggesting a role for apelin in the regulation of maternal outcomes in preeclampsia.
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Sakamoto M, Matsutani D, Kayama Y. Clinical Implications of Baroreflex Sensitivity in Type 2 Diabetes. Int Heart J 2019; 60:241-246. [PMID: 30799384 DOI: 10.1536/ihj.18-455] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The evaluation of baroreflex sensitivity (BRS), which maintains systemic circulatory homeostasis, is an established tool to assess cardiovascular autonomic neuropathy in type 2 diabetes mellitus (T2DM). As BRS plays an important function in blood pressure regulation, reduced BRS leads to an increase in blood pressure variability, which further leads to reduced BRS. This sequence of events becomes a vicious cycle. The major risk factors for reduced BRS are T2DM and essential hypertension, but many other risk factors have been reported to influence BRS. In recent years, reports have indicated that glycemic variability (GV), such as short- and long-term GV that are considered important risk factors for macrovascular and microvascular complications, is involved in reductions in BRS independently of blood glucose levels. In this review, we discuss reduced BRS in T2DM, its features, and the potential for its reversal.
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Affiliation(s)
- Masaya Sakamoto
- Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Jikei University School of Medicine
| | - Daisuke Matsutani
- Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Jikei University School of Medicine
| | - Yosuke Kayama
- Department of Cardiology, Jikei University School of Medicine
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6
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Shi Z, Cassaglia PA, Pelletier NE, Brooks VL. Sex differences in the sympathoexcitatory response to insulin in obese rats: role of neuropeptide Y. J Physiol 2019; 597:1757-1775. [PMID: 30628058 DOI: 10.1113/jp277517] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 12/20/2018] [Indexed: 12/17/2022] Open
Abstract
KEY POINTS Intracerebroventricular insulin increased sympathetic nerve activity (SNA) and baroreflex control of SNA and heart rate more dramatically in obese male rats; in obese females, the responses were abolished. In obese males, the enhanced lumbar SNA (LSNA) responses were associated with reduced tonic inhibition of LSNA by neuropeptide Y (NPY) in the PVN. However, PVN NPY injection decreased LSNA similarly in obesity prone/obesity resistant/control rats. Collectively, these results suggest that NPY inputs were decreased. In obese females, NPY inhibition in the PVN was maintained. Moreover, NPY neurons in the arcuate nucleus became resistant to the inhibitory effects of insulin. A high-fat diet did not alter arcuate NPY neuronal InsR expression in males or females. Obesity-induced 'selective sensitization' of the brain to the sympathoexcitatory effects of insulin and leptin may contribute to elevated basal SNA, and therefore hypertension development, in males with obesity. These data may explain in part why obesity increases SNA less in women compared to men. ABSTRACT Obesity increases sympathetic nerve activity (SNA) in men but not women; however, the mechanisms are unknown. We investigated whether intracerebroventricular insulin infusion increases SNA more in obese male than female rats and if sex differences are mediated by changes in tonic inhibition of SNA by neuropeptide Y (NPY) in the paraventricular nucleus (PVN). When consuming a high-fat diet, obesity prone (OP) rats accrued excess fat, whereas obesity resistant (OR) rats maintained adiposity as in rats eating a control (CON) diet. Insulin increased lumbar SNA (LSNA) similarly in CON/OR males and females under urethane anaesthesia. The LSNA response was magnified in OP males but abolished in OP females. In males, blockade of PVN NPY Y1 receptors with BIBO3304 increased LSNA in CON/OR rats but not OP rats. Yet, PVN nanoinjections of NPY decreased LSNA similarly between groups. Thus, tonic PVN NPY inhibition of LSNA may be lost in obese males as a result of a decrease in NPY inputs. By contrast, in females, PVN BIBO3304 increased LSNA similarly in OP, OR and CON rats. After insulin, PVN BIBO3304 failed to increase LSNA in CON/OR females but increased LSNA in OP females, suggesting that with obesity NPY neurons become resistant to the inhibitory effects of insulin. These sex differences were not associated with changes in arcuate NPY neuronal insulin receptor expression. Collectively, these data reveal a marked sex difference in the impact of obesity on the sympathoexcitatory actions of insulin and implicate sexually dimorphic changes in NPY inhibition of SNA in the PVN as one mechanism.
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Affiliation(s)
- Zhigang Shi
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA
| | - Priscila A Cassaglia
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA
| | - Nicole E Pelletier
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA
| | - Virginia L Brooks
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA
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Chaudhary P, Schreihofer AM. Improved glucose homeostasis in male obese Zucker rats coincides with enhanced baroreflexes and activation of the nucleus tractus solitarius. Am J Physiol Regul Integr Comp Physiol 2018; 315:R1195-R1209. [PMID: 30256679 DOI: 10.1152/ajpregu.00195.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Young adult male obese Zucker rats (OZR) develop insulin resistance and hypertension with impaired baroreflex-mediated bradycardia and activation of nucleus tractus solitarius (NTS). Because type 1 diabetic rats also develop impaired baroreflex-mediated NTS activation, we hypothesized that improving glycemic control in OZR would enhance compromised baroreflexes and NTS activation. Fasting blood glucose measured by telemetry was comparable in OZR and lean Zucker rats (LZR) at 12-17 wk. However, with access to food, OZR were chronically hyperglycemic throughout this age range. By 15-17 wk of age, tail samples yielded higher glucose values than those measured by telemetry in OZR but not LZR, consistent with reports of exaggerated stress responses in OZR. Injection of glucose (1g/kg ip) produced larger rises in glucose and areas under the curve in OZR than LZR. Treatment with metformin (300 mg·kg-1·day-1) or pioglitazone (5 mg·kg-1·day-1) in drinking water for 2-3 wk normalized fed glucose levels in OZR with no effect in LZR. After metformin treatment, area under the curve for blood glucose after glucose injection was reduced in OZR and comparable to LZR. Hyperinsulinemia was slightly reduced by each treatment in OZR, but insulin was still greatly elevated compared with LZR. Neither treatment reduced hypertension in OZR, but both treatments significantly improved the blunted phenylephrine-induced bradycardia and NTS c-Fos expression in OZR with no effect in LZR. These data suggest that restoring glycemic control in OZR enhances baroreflex control of heart rate by improving the response of the NTS to raising arterial pressure, even in the presence of hyperinsulinemia and hypertension.
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Affiliation(s)
- Parul Chaudhary
- Department of Physiology and Anatomy, University of North Texas Health Science Center , Fort Worth, Texas
| | - Ann M Schreihofer
- Department of Physiology and Anatomy, University of North Texas Health Science Center , Fort Worth, Texas
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Chai BK, Lau YS, Loong BJ, Rais MM, Ting KN, Dharmani DM, Mohankumar SK. Co-administration of conjugated linoleic acid and rosiglitazone increases atherogenic co-efficient and alters isoprenaline-induced vasodilatation in rats fed high fat diet. Physiol Res 2018; 67:729-740. [PMID: 29750886 DOI: 10.33549/physiolres.933706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The cis(c)-9, trans(t)-11 (c9,t11) and t10,c12 isomers of conjugated linoleic acid (CLA) have been reported as agonists of peroxisome proliferator-activated receptor (PPAR) and beneficial in lipidemia and glycemia. However, it is unclear whether CLA isomers enhance or antagonize effects of conventional drugs targeting PPAR. Male Sprague-Dawley rats were fed high fat diet (HFD) for 8 weeks and treated without or with CLA, rosiglitazone or both for 4 weeks. Oral glucose tolerance and surrogate markers of insulin resistance were not significantly different for all treatments compared to untreated normal diet (ND) or HFD group, except lipoprotein levels. The combination of CLA and rosiglitazone had suppressed levels of low and high density lipoproteins (46 % and 25 %, respectively), compared to HFD-alone. Conversely, the atherogenic co-efficient of the animals received HFD or HFD+rosiglitazone+CLA was 2-folds higher than ND, HFD+rosiglitazone or HFD+CLA. Isolated aortic rings from the combined CLA and rosiglitazone treated animals were less sensitive to isoprenaline-induced relaxation among endothelium-denuded aortas with a decreased efficacy and potency (R(max)=53+/-4.7 %; pEC50=6+/-0.2) compared to endothelium-intact aortas (R(max)=100+/-9.9 %; pEC50=7+/-0.2). Our findings illustrate that the combination of CLA and rosiglitazone precede the atherogenic state with impaired endothelium-independent vasodilatation before the onset of HFD-induced insulin resistance.
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Affiliation(s)
- B K Chai
- Department of Biomedical Sciences, Faculty of Science, University of Nottingham Malaysia Campus, Semenyih, Selangor, Malaysia. TIFAC CORE Herbal Drugs JSS College of Pharmacy, Jagadguru Sri Shivrathreeshwara University, Mysuru, India. or
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9
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Bandyopadhyay GK, Mahata SK. Chromogranin A Regulation of Obesity and Peripheral Insulin Sensitivity. Front Endocrinol (Lausanne) 2017; 8:20. [PMID: 28228748 PMCID: PMC5296320 DOI: 10.3389/fendo.2017.00020] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 01/23/2017] [Indexed: 01/15/2023] Open
Abstract
Chromogranin A (CgA) is a prohormone and granulogenic factor in endocrine and neuroendocrine tissues, as well as in neurons, and has a regulated secretory pathway. The intracellular functions of CgA include the initiation and regulation of dense-core granule biogenesis and sequestration of hormones in neuroendocrine cells. This protein is co-stored and co-released with secreted hormones. The extracellular functions of CgA include the generation of bioactive peptides, such as pancreastatin (PST), vasostatin, WE14, catestatin (CST), and serpinin. CgA knockout mice (Chga-KO) display: (i) hypertension with increased plasma catecholamines, (ii) obesity, (iii) improved hepatic insulin sensitivity, and (iv) muscle insulin resistance. These findings suggest that individual CgA-derived peptides may regulate different physiological functions. Indeed, additional studies have revealed that the pro-inflammatory PST influences insulin sensitivity and glucose tolerance, whereas CST alleviates adiposity and hypertension. This review will focus on the different metabolic roles of PST and CST peptides in insulin-sensitive and insulin-resistant models, and their potential use as therapeutic targets.
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Affiliation(s)
| | - Sushil K. Mahata
- Department of Medicine, University of California San Diego, La Jolla, CA, USA
- Department of Medicine, Metabolic Physiology and Ultrastructural Biology Laboratory, VA San Diego Healthcare System, San Diego, CA, USA
- *Correspondence: Sushil K. Mahata,
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10
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Goltsman I, Khoury EE, Winaver J, Abassi Z. Does Thiazolidinedione therapy exacerbate fluid retention in congestive heart failure? Pharmacol Ther 2016; 168:75-97. [PMID: 27598860 DOI: 10.1016/j.pharmthera.2016.09.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The ever-growing global burden of congestive heart failure (CHF) and type 2 diabetes mellitus (T2DM) as well as their co-existence necessitate that anti-diabetic pharmacotherapy will modulate the cardiovascular risk inherent to T2DM while complying with the accompanying restrictions imposed by CHF. The thiazolidinedione (TZD) family of peroxisome proliferator-activated receptor γ (PPARγ) agonists initially provided a promising therapeutic option in T2DM owing to anti-diabetic efficacy combined with pleiotropic beneficial cardiovascular effects. However, the utility of TZDs in T2DM has declined in the past decade, largely due to concomitant adverse effects of fluid retention and edema formation attributed to salt-retaining effects of PPARγ activation on the nephron. Presumably, the latter effects are potentially deleterious in the context of pre-existing fluid retention in CHF. However, despite a considerable body of evidence on mechanisms responsible for TZD-induced fluid retention suggesting that this class of drugs is rightfully prohibited from use in CHF patients, there is a paucity of experimental and clinical studies that investigate the effects of TZDs on salt and water homeostasis in the CHF setting. In an attempt to elucidate whether TZDs actually exacerbate the pre-existing fluid retention in CHF, our review summarizes the pathophysiology of fluid retention in CHF. Moreover, we thoroughly review the available data on TZD-induced fluid retention and proposed mechanisms in animals and patients. Finally, we will present recent studies challenging the common notion that TZDs worsen renal salt and water retention in CHF.
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Affiliation(s)
- Ilia Goltsman
- Department of Physiology, Biophysics and Systems Biology, The Bruce Rappaport, Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Emad E Khoury
- Department of Physiology, Biophysics and Systems Biology, The Bruce Rappaport, Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Joseph Winaver
- Department of Physiology, Biophysics and Systems Biology, The Bruce Rappaport, Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Zaid Abassi
- Department of Physiology, Biophysics and Systems Biology, The Bruce Rappaport, Rappaport Faculty of Medicine, Technion, Haifa, Israel; Department of Laboratory Medicine, Rambam Human Health Care Campus, Haifa, Israel.
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11
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Zhao LY, Li J, Yuan F, Li M, Zhang Q, Huang YY, Pang JY, Zhang B, Sun FY, Sun HS, Li Q, Cao L, Xie Y, Lin YC, Liu J, Tan HM, Wang GL. Xyloketal B attenuates atherosclerotic plaque formation and endothelial dysfunction in apolipoprotein e deficient mice. Mar Drugs 2015; 13:2306-26. [PMID: 25874925 PMCID: PMC4413213 DOI: 10.3390/md13042306] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 03/30/2015] [Accepted: 04/03/2015] [Indexed: 12/31/2022] Open
Abstract
Our previous studies demonstrated that xyloketal B, a novel marine compound with a unique chemical structure, has strong antioxidant actions and can protect against endothelial injury in different cell types cultured in vitro and model organisms in vivo. The oxidative endothelial dysfunction and decrease in nitric oxide (NO) bioavailability are critical for the development of atherosclerotic lesion. We thus examined whether xyloketal B had an influence on the atherosclerotic plaque area in apolipoprotein E-deficient (apoE-/-) mice fed a high-fat diet and investigated the underlying mechanisms. We found in our present study that the administration of xyloketal B dose-dependently decreased the atherosclerotic plaque area both in the aortic sinus and throughout the aorta in apoE-/- mice fed a high-fat diet. In addition, xyloketal B markedly reduced the levels of vascular oxidative stress, as well as improving the impaired endothelium integrity and NO-dependent aortic vasorelaxation in atherosclerotic mice. Moreover, xyloketal B significantly changed the phosphorylation levels of endothelial nitric oxide synthase (eNOS) and Akt without altering the expression of total eNOS and Akt in cultured human umbilical vein endothelial cells (HUVECs). Here, it increased eNOS phosphorylation at the positive regulatory site of Ser-1177, while inhibiting phosphorylation at the negative regulatory site of Thr-495. Taken together, these findings indicate that xyloketal B has dramatic anti-atherosclerotic effects in vivo, which is partly due to its antioxidant features and/or improvement of endothelial function.
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MESH Headings
- Animals
- Antioxidants/adverse effects
- Antioxidants/pharmacology
- Antioxidants/therapeutic use
- Aorta/drug effects
- Aorta/metabolism
- Aorta/physiopathology
- Aorta/ultrastructure
- Apolipoproteins E/deficiency
- Apolipoproteins E/metabolism
- Cardiovascular Agents/adverse effects
- Cardiovascular Agents/pharmacology
- Cardiovascular Agents/therapeutic use
- Cells, Cultured
- Diet, High-Fat/adverse effects
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/physiopathology
- Endothelium, Vascular/ultrastructure
- Human Umbilical Vein Endothelial Cells/cytology
- Human Umbilical Vein Endothelial Cells/drug effects
- Human Umbilical Vein Endothelial Cells/metabolism
- Humans
- Lipid Metabolism, Inborn Errors/drug therapy
- Lipid Metabolism, Inborn Errors/metabolism
- Lipid Metabolism, Inborn Errors/pathology
- Lipid Metabolism, Inborn Errors/physiopathology
- Male
- Mice, Knockout
- Nitric Oxide Synthase Type III/genetics
- Nitric Oxide Synthase Type III/metabolism
- Oxidative Stress/drug effects
- Phosphorylation/drug effects
- Plaque, Atherosclerotic/etiology
- Plaque, Atherosclerotic/prevention & control
- Protein Processing, Post-Translational/drug effects
- Proto-Oncogene Proteins c-akt/genetics
- Proto-Oncogene Proteins c-akt/metabolism
- Pyrans/adverse effects
- Pyrans/pharmacology
- Pyrans/therapeutic use
- Specific Pathogen-Free Organisms
- Vasodilation/drug effects
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Affiliation(s)
- Li-Yan Zhao
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; E-Mails: (L.-Y.Z.); (F.Y.); (Y.X.); (J.L.)
| | - Jie Li
- Department of Anesthesiology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510080, China; E-Mail:
| | - Feng Yuan
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; E-Mails: (L.-Y.Z.); (F.Y.); (Y.X.); (J.L.)
| | - Mei Li
- VIP Healthcare Center, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510630, China; E-Mail:
| | - Quan Zhang
- Department of Pathophysiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; E-Mails: (Q.Z.); (Q.L.); (L.C.)
| | - Yun-Ying Huang
- Department of Pharmacy, The fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou 510182, China; E-Mail:
| | - Ji-Yan Pang
- Department of Applied Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510080, China; E-Mails: (J.-Y.P.); (Y.-C.L.)
- Department of Education of Guangdong Province, Guangdong Province Key Laboratory of Functional Molecules in Oceanic Microorganism, Sun Yat-sen University, Guangzhou 510080, China
| | - Bin Zhang
- Guangdong Cardiovascular Institute, Guangdong General Hospital, Guangzhou 510080, China; E-Mail:
| | - Fang-Yun Sun
- Lab for Basic Research of Life Science, School of Medicine, Tibet Institute for Nationalities, Xianyang 712082, China; E-Mails:
| | - Hong-Shuo Sun
- Departments of Surgery and Physiology, Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON M5G 1G6, Canada; E-Mail:
| | - Qian Li
- Department of Pathophysiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; E-Mails: (Q.Z.); (Q.L.); (L.C.)
| | - Lu Cao
- Department of Pathophysiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; E-Mails: (Q.Z.); (Q.L.); (L.C.)
| | - Yu Xie
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; E-Mails: (L.-Y.Z.); (F.Y.); (Y.X.); (J.L.)
| | - Yong-Cheng Lin
- Department of Applied Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510080, China; E-Mails: (J.-Y.P.); (Y.-C.L.)
- Department of Education of Guangdong Province, Guangdong Province Key Laboratory of Functional Molecules in Oceanic Microorganism, Sun Yat-sen University, Guangzhou 510080, China
| | - Jie Liu
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; E-Mails: (L.-Y.Z.); (F.Y.); (Y.X.); (J.L.)
| | - Hong-Mei Tan
- Department of Pathophysiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; E-Mails: (Q.Z.); (Q.L.); (L.C.)
- Department of Education of Guangdong Province, Guangdong Province Key Laboratory of Functional Molecules in Oceanic Microorganism, Sun Yat-sen University, Guangzhou 510080, China
- Authors to whom correspondence should be addressed; E-Mails: (H.-M.T.); (G.-L.W.); Tel./Fax: +86-020-8733-4055 (H.-M.T.); Tel.: +86-020-8733-0300 (G.-L.W.); Fax: +86-020-8733-1155 (G.-L.W.)
| | - Guan-Lei Wang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; E-Mails: (L.-Y.Z.); (F.Y.); (Y.X.); (J.L.)
- Department of Education of Guangdong Province, Guangdong Province Key Laboratory of Functional Molecules in Oceanic Microorganism, Sun Yat-sen University, Guangzhou 510080, China
- Authors to whom correspondence should be addressed; E-Mails: (H.-M.T.); (G.-L.W.); Tel./Fax: +86-020-8733-4055 (H.-M.T.); Tel.: +86-020-8733-0300 (G.-L.W.); Fax: +86-020-8733-1155 (G.-L.W.)
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12
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Diet-induced obesity prevents the development of acute traumatic coagulopathy. J Trauma Acute Care Surg 2015; 77:873-7; discussion 878. [PMID: 25423535 DOI: 10.1097/ta.0000000000000461] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Obesity and hemorrhagic shock following trauma are predictors of mortality but have conflicting effects on coagulation. Following hemorrhage, tissue injury and hypoperfusion lead to acute traumatic coagulopathy (ATC), producing a hypocoagulable state. Inversely, obesity promotes clotting and impairs fibrinolysis to yield a hypercoagulable state. High rates of venous thromboembolism, organ failure, and early mortality may be caused by hypercoagulability in obese patients. We hypothesize that obesity prevents the development of ATC following injury-induced hemorrhagic shock. METHODS Male Sprague-Dawley rats (250-275 g) were fed a high-fat diet (32%kcal from fat) for 4 weeks to 6 weeks and diverged into obesity-resistant (OR, n = 9) and obesity-prone (OP, n = 9) groups. Age-matched control (CON) rats were fed normal diet (10% kcal from fat, n = 9). Anesthetized rats were subjected to an uncontrolled hemorrhage by a Grade V splenic injury to a mean arterial pressure (MAP) of 40 mm Hg. Hypotension (MAP, 30-40 mm Hg) was maintained for 30 minutes to induce shock. MAP, heart rate, lactate, base excess, cytokines, blood loss, and thrombelastography (TEG) parameters were measured before and after hemorrhagic shock. RESULTS At baseline, OP rats exhibited a shorter time to 20-mm clot (K), and higher rate of clot formation (α angle), clot strength (maximal amplitude), and coagulation index, compared with the CON rats (p < 0.05), indicating enhanced coagulation. Physiologic parameters following shock were similar between groups. In the CON and OR rats, shock prolonged the time to clot initiation (R) and K and decreased α angle and coagulation index (all p < 0.05 vs. baseline). In contrast, shock had no effect on these TEG parameters in the OP rats. Maximal amplitude was the only TEG parameter affected by shock in the OP rats, which was decreased in all groups. CONCLUSION Obesity prevents the development of ATC following hemorrhage shock. Complications associated with obesity following hemorrhagic shock may be attributed to the preserved hypercoagulable state.
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Bandyopadhyay GK, Lu M, Avolio E, Siddiqui JA, Gayen JR, Wollam J, Vu CU, Chi NW, O'Connor DT, Mahata SK. Pancreastatin-dependent inflammatory signaling mediates obesity-induced insulin resistance. Diabetes 2015; 64:104-16. [PMID: 25048197 DOI: 10.2337/db13-1747] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Chromogranin A knockout (Chga-KO) mice exhibit enhanced insulin sensitivity despite obesity. Here, we probed the role of the chromogranin A-derived peptide pancreastatin (PST: CHGA(273-301)) by investigating the effect of diet-induced obesity (DIO) on insulin sensitivity of these mice. We found that on a high-fat diet (HFD), Chga-KO mice (KO-DIO) remain more insulin sensitive than wild-type DIO (WT-DIO) mice. Concomitant with this phenotype is enhanced Akt and AMPK signaling in muscle and white adipose tissue (WAT) as well as increased FoxO1 phosphorylation and expression of mature Srebp-1c in liver and downregulation of the hepatic gluconeogenic genes, Pepck and G6pase. KO-DIO mice also exhibited downregulation of cytokines and proinflammatory genes and upregulation of anti-inflammatory genes in WAT, and peritoneal macrophages from KO mice displayed similarly reduced proinflammatory gene expression. The insulin-sensitive, anti-inflammatory phenotype of KO-DIO mice is masked by supplementing PST. Conversely, a PST variant peptide PSTv1 (PST-NΔ3: CHGA(276-301)), lacking PST activity, simulated the KO phenotype by sensitizing WT-DIO mice to insulin. In summary, the reduced inflammation due to PST deficiency prevented the development of insulin resistance in KO-DIO mice. Thus, obesity manifests insulin resistance only in the presence of PST, and in its absence obesity is dissociated from insulin resistance.
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Affiliation(s)
- Gautam K Bandyopadhyay
- VA San Diego Healthcare System, San Diego, CA Department of Medicine, University of California, San Diego, San Diego, CA
| | - Minh Lu
- VA San Diego Healthcare System, San Diego, CA
| | - Ennio Avolio
- Department of Medicine, University of California, San Diego, San Diego, CA
| | | | | | - Joshua Wollam
- Department of Medicine, University of California, San Diego, San Diego, CA
| | - Christine U Vu
- Department of Medicine, University of California, San Diego, San Diego, CA
| | - Nai-Wen Chi
- VA San Diego Healthcare System, San Diego, CA Department of Medicine, University of California, San Diego, San Diego, CA
| | - Daniel T O'Connor
- VA San Diego Healthcare System, San Diego, CA Department of Medicine, University of California, San Diego, San Diego, CA
| | - Sushil K Mahata
- VA San Diego Healthcare System, San Diego, CA Department of Medicine, University of California, San Diego, San Diego, CA
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14
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Borges GR, Morgan DA, Ketsawatsomkron P, Mickle AD, Thompson AP, Cassell MD, Mohapatra DP, Rahmouni K, Sigmund CD. Interference with peroxisome proliferator-activated receptor-γ in vascular smooth muscle causes baroreflex impairment and autonomic dysfunction. Hypertension 2014; 64:590-6. [PMID: 24914194 DOI: 10.1161/hypertensionaha.114.03553] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
S-P467L mice expressing dominant negative peroxisome proliferator-activated receptor-γ selectively in vascular smooth muscle exhibit impaired vasodilation, augmented vasoconstriction, hypertension, and tachycardia. We hypothesized that tachycardia in S-P467L mice is a result of baroreflex dysfunction. S-P467L mice displayed increased sympathetic traffic to the heart and decreased baroreflex gain and effectiveness. Carotid arteries exhibited inward remodeling but no changes in distensibility or stress/strain. Aortic depressor nerve activity in response to increased arterial pressure was blunted in S-P467L mice. However, the arterial pressure and heart rate responses to aortic depressor nerve stimulation were unaltered in S-P467L mice, suggesting that the central and efferent limbs of the baroreflex arc remain intact. There was no transgene expression in nodose ganglion and no change in expression of the acid-sensing ion channel-2 or -3 in nodose ganglion. There was a trend toward decreased expression of transient receptor potential vanilloid-1 receptor mRNA in nodose ganglion, but no difference in the immunochemical staining of transient receptor potential vanilloid-1 receptor in the termination area of the left aortic depressor nerve in S-P467L mice. Although there was no difference in the maximal calcium response to capsaicin in cultured nodose neurons from S-P467L mice, there was decreased desensitization of transient receptor potential vanilloid-1 receptor channels. In conclusion, S-P467L mice exhibit baroreflex dysfunction because of a defect in the afferent limb of the baroreflex arc caused by impaired vascular function, altered vascular structure, or compromised neurovascular coupling. These findings implicate vascular smooth muscle peroxisome proliferator activated receptor-γ as a critical determinant of neurovascular signaling.
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Affiliation(s)
- Giulianna R Borges
- From the Department of Pharmacology (G.R.B., D.A.M., P.K., A.D.M., D.P.M., K.R., C.D.S.), Department of Anatomy and Cell Biology (A.P.T., M.D.C.), and Center on the Functional Genomics of Hypertension (K.R., C.D.S.), Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City
| | - Donald A Morgan
- From the Department of Pharmacology (G.R.B., D.A.M., P.K., A.D.M., D.P.M., K.R., C.D.S.), Department of Anatomy and Cell Biology (A.P.T., M.D.C.), and Center on the Functional Genomics of Hypertension (K.R., C.D.S.), Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City
| | - Pimonrat Ketsawatsomkron
- From the Department of Pharmacology (G.R.B., D.A.M., P.K., A.D.M., D.P.M., K.R., C.D.S.), Department of Anatomy and Cell Biology (A.P.T., M.D.C.), and Center on the Functional Genomics of Hypertension (K.R., C.D.S.), Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City
| | - Aaron D Mickle
- From the Department of Pharmacology (G.R.B., D.A.M., P.K., A.D.M., D.P.M., K.R., C.D.S.), Department of Anatomy and Cell Biology (A.P.T., M.D.C.), and Center on the Functional Genomics of Hypertension (K.R., C.D.S.), Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City
| | - Anthony P Thompson
- From the Department of Pharmacology (G.R.B., D.A.M., P.K., A.D.M., D.P.M., K.R., C.D.S.), Department of Anatomy and Cell Biology (A.P.T., M.D.C.), and Center on the Functional Genomics of Hypertension (K.R., C.D.S.), Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City
| | - Martin D Cassell
- From the Department of Pharmacology (G.R.B., D.A.M., P.K., A.D.M., D.P.M., K.R., C.D.S.), Department of Anatomy and Cell Biology (A.P.T., M.D.C.), and Center on the Functional Genomics of Hypertension (K.R., C.D.S.), Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City
| | - Durga P Mohapatra
- From the Department of Pharmacology (G.R.B., D.A.M., P.K., A.D.M., D.P.M., K.R., C.D.S.), Department of Anatomy and Cell Biology (A.P.T., M.D.C.), and Center on the Functional Genomics of Hypertension (K.R., C.D.S.), Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City
| | - Kamal Rahmouni
- From the Department of Pharmacology (G.R.B., D.A.M., P.K., A.D.M., D.P.M., K.R., C.D.S.), Department of Anatomy and Cell Biology (A.P.T., M.D.C.), and Center on the Functional Genomics of Hypertension (K.R., C.D.S.), Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City
| | - Curt D Sigmund
- From the Department of Pharmacology (G.R.B., D.A.M., P.K., A.D.M., D.P.M., K.R., C.D.S.), Department of Anatomy and Cell Biology (A.P.T., M.D.C.), and Center on the Functional Genomics of Hypertension (K.R., C.D.S.), Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City.
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15
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Guimaraes PS, Huber DA, Campagnole-Santos MJ, Schreihofer AM. Development of attenuated baroreflexes in obese Zucker rats coincides with impaired activation of nucleus tractus solitarius. Am J Physiol Regul Integr Comp Physiol 2014; 306:R681-92. [PMID: 24573182 DOI: 10.1152/ajpregu.00537.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adult obese Zucker rats (OZR; >12 wk) develop elevated sympathetic nerve activity (SNA) and mean arterial pressure (MAP) with impaired baroreflexes compared with adult lean Zucker rats (LZR) and juvenile OZR (6-7 wk). In adult OZR, baroreceptor afferent nerves respond normally to changes in MAP, whereas electrical stimulation of baroreceptor afferent fibers produces smaller reductions in SNA and MAP compared with LZR. We hypothesized that impaired baroreflexes in OZR are linked to reduced activation of brain stem sites that mediate baroreflexes. In conscious adult rats, a hydralazine (HDZ)-induced reduction in MAP evoked tachycardia that was initially blunted in OZR, but equivalent to LZR within 5 min. In agreement, HDZ-induced expression of c-Fos in the rostral ventrolateral medulla (RVLM) was comparable between groups. In contrast, phenylephrine (PE)-induced rise in MAP evoked markedly attenuated bradycardia with dramatically reduced c-Fos expression in the nucleus tractus solitarius (NTS) of adult OZR compared with LZR. However, in juvenile rats, PE-induced hypertension evoked comparable bradycardia in OZR and LZR with similar or augmented c-Fos expression in NTS of the OZR. In urethane-anesthetized rats, microinjections of glutamate into NTS evoked equivalent decreases in SNA, heart rate (HR), and MAP in juvenile OZR and LZR, but attenuated decreases in SNA and MAP in adult OZR. In contrast, microinjections of glutamate into the caudal ventrolateral medulla, a target of barosensitive NTS neurons, evoked comparable decreases in SNA, HR, and MAP in adult OZR and LZR. These data suggest that OZR develop impaired glutamatergic activation of the NTS, which likely contributes to attenuated baroreflexes in adult OZR.
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How JMY, Wardak SA, Ameer SI, Davey RA, Sartor DM. Blunted sympathoinhibitory responses in obesity-related hypertension are due to aberrant central but not peripheral signalling mechanisms. J Physiol 2014; 592:1705-20. [PMID: 24492842 DOI: 10.1113/jphysiol.2013.269670] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The gut hormone cholecystokinin (CCK) acts at subdiaphragmatic vagal afferents to induce renal and splanchnic sympathoinhibition and vasodilatation, via reflex inhibition of a subclass of cardiovascular-controlling neurons in the rostroventrolateral medulla (RVLM). These sympathoinhibitory and vasodilator responses are blunted in obese, hypertensive rats and our aim in the present study was to determine whether this is attributable to (i) altered sensitivity of presympathetic vasomotor RVLM neurons, and (ii) aberrant peripheral or central signalling mechanisms. Using a diet-induced obesity model, male Sprague-Dawley rats exhibited either an obesity-prone (OP) or obesity-resistant (OR) phenotype when placed on a medium high fat diet for 13-15 weeks; control animals were placed on a low fat diet. OP animals had elevated resting arterial pressure compared to OR/control animals (P < 0.05). Barosensitivity of RVLM neurons was significantly attenuated in OP animals (P < 0.05), suggesting altered baroreflex gain. CCK induced inhibitory responses in RVLM neurons of OR/control animals but not OP animals. Subdiaphragmatic vagal nerve responsiveness to CCK and CCK1 receptor mRNA expression in nodose ganglia did not differ between the groups, but CCK induced significantly less Fos-like immunoreactivity in both the nucleus of the solitary tract and the caudal ventrolateral medulla of OP animals compared to controls (P < 0.05). These results suggest that blunted sympathoinhibitory and vasodilator responses in obesity-related hypertension are due to alterations in RVLM neuronal responses, resulting from aberrant central but not peripheral signalling mechanisms. In obesity, blunted sympathoinhibitory mechanisms may lead to increased regional vascular resistance and contribute to the development of hypertension.
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17
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Cheng KC, Asakawa A, Li YX, Chung HH, Amitani H, Ueki T, Cheng JT, Inui A. Silymarin induces insulin resistance through an increase of phosphatase and tensin homolog in Wistar rats. PLoS One 2014; 9:e84550. [PMID: 24404172 PMCID: PMC3880317 DOI: 10.1371/journal.pone.0084550] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 11/15/2013] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND AIMS Phosphatase and tensin homolog (PTEN) is a phosphoinositide phosphatase that regulates crucial cellular functions, including insulin signaling, lipid and glucose metabolism, as well as survival and apoptosis. Silymarin is the active ingredient in milk thistle and exerts numerous effects through the activation of PTEN. However, the effect of silymarin on the development of insulin resistance remains unknown. METHODS Wistar rats fed fructose-rich chow or normal chow were administered oral silymarin to identify the development of insulin resistance using the homeostasis model assessment of insulin resistance and hyperinsulinemic- euglycemic clamping. Changes in PTEN expression in skeletal muscle and liver were compared using western blotting analysis. Further investigation was performed in L6 cells to check the expression of PTEN and insulin-related signals. PTEN deletion in L6 cells was achieved by small interfering ribonucleic acid transfection. RESULTS Oral administration of silymarin at a dose of 200 mg/kg once daily induced insulin resistance in normal rats and enhanced insulin resistance in fructose-rich chow-fed rats. An increase of PTEN expression was observed in the skeletal muscle and liver of rats with insulin resistance. A decrease in the phosphorylation of Akt in L6 myotube cells, which was maintained in a high-glucose condition, was also observed. Treatment with silymarin aggravated high-glucose-induced insulin resistance. Deletion of PTEN in L6 cells reversed silymarin-induced impaired insulin signaling and glucose uptake. CONCLUSIONS Silymarin has the ability to disrupt insulin signaling through increased PTEN expression. Therefore, silymarin should be used carefully in type-2 diabetic patients.
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Affiliation(s)
- Kai-Chun Cheng
- Department of Psychosomatic Internal Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Akihiro Asakawa
- Department of Psychosomatic Internal Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Ying-Xiao Li
- Department of Psychosomatic Internal Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Hsien-Hui Chung
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan City, Taiwan
| | - Haruka Amitani
- Department of Psychosomatic Internal Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Takatoshi Ueki
- Department of Neuroanatomy, Hamamatsu University School of Medicine. Hamamatsu, Japan
| | - Juei-Tang Cheng
- Department of Medical Research, Chi-Mei Medical Center, Yong Kang, Tainan City, Taiwan
| | - Akio Inui
- Department of Psychosomatic Internal Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
- * E-mail:
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18
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Iliescu R, Tudorancea I, Irwin ED, Lohmeier TE. Chronic baroreflex activation restores spontaneous baroreflex control and variability of heart rate in obesity-induced hypertension. Am J Physiol Heart Circ Physiol 2013; 305:H1080-8. [PMID: 23913707 PMCID: PMC3798752 DOI: 10.1152/ajpheart.00464.2013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 07/27/2013] [Indexed: 12/21/2022]
Abstract
The sensitivity of baroreflex control of heart rate is depressed in subjects with obesity hypertension, which increases the risk for cardiac arrhythmias. The mechanisms are not fully known, and there are no therapies to improve this dysfunction. To determine the cardiovascular dynamic effects of progressive increases in body weight leading to obesity and hypertension in dogs fed a high-fat diet, 24-h continuous recordings of spontaneous fluctuations in blood pressure and heart rate were analyzed in the time and frequency domains. Furthermore, we investigated whether autonomic mechanisms stimulated by chronic baroreflex activation and renal denervation-current therapies in patients with resistant hypertension, who are commonly obese-restore cardiovascular dynamic control. Increases in body weight to ∼150% of control led to a gradual increase in mean arterial pressure to 17 ± 3 mmHg above control (100 ± 2 mmHg) after 4 wk on the high-fat diet. In contrast to the gradual increase in arterial pressure, tachycardia, attenuated chronotropic baroreflex responses, and reduced heart rate variability were manifest within 1-4 days on high-fat intake, reaching 130 ± 4 beats per minute (bpm) (control = 86 ± 3 bpm) and ∼45% and <20%, respectively, of control levels. Subsequently, both baroreflex activation and renal denervation abolished the hypertension. However, only baroreflex activation effectively attenuated the tachycardia and restored cardiac baroreflex sensitivity and heart rate variability. These findings suggest that baroreflex activation therapy may reduce the risk factors for cardiac arrhythmias as well as lower arterial pressure.
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Affiliation(s)
- Radu Iliescu
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
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McCully BH, Hasan W, Streiff CT, Houle JC, Woodward WR, Giraud GD, Brooks VL, Habecker BA. Sympathetic cardiac hyperinnervation and atrial autonomic imbalance in diet-induced obesity promote cardiac arrhythmias. Am J Physiol Heart Circ Physiol 2013; 305:H1530-7. [PMID: 24014675 DOI: 10.1152/ajpheart.00196.2013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Obesity increases the risk of arrhythmias and sudden cardiac death, but the mechanisms are unknown. This study tested the hypothesis that obesity-induced cardiac sympathetic outgrowth and hyperinnervation promotes the development of arrhythmic events. Male Sprague-Dawley rats (250-275 g), fed a high-fat diet (33% kcal/fat), diverged into obesity-resistant (OR) and obesity-prone (OP) groups and were compared with rats fed normal chow (13% kcal/fat; CON). In vitro experiments showed that both OR and OP rats exhibited hyperinnervation of the heart and high sympathetic outgrowth compared with CON rats, even though OR rats are not obese. Despite the hyperinnervation and outgrowth, we showed that, in vivo, OR rats were less susceptible to arrhythmic events after an intravenous epinephrine challenge compared with OP rats. On examining total and stimulus-evoked neurotransmitter levels in an ex vivo system, we demonstrate that atrial acetylcholine content and release were attenuated in OP compared with OR and CON groups. OP rats also expressed elevated atrial norepinephrine content, while norepinephrine release was suppressed. These findings suggest that the consumption of a high-fat diet, even in the absence of overt obesity, stimulates sympathetic outgrowth and hyperinnervation of the heart. However, normalized cardiac parasympathetic nervous system control may protect the heart from arrhythmic events.
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Affiliation(s)
- Belinda H McCully
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon; and
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Luckett BS, Frielle JL, Wolfgang L, Stocker SD. Arcuate nucleus injection of an anti-insulin affibody prevents the sympathetic response to insulin. Am J Physiol Heart Circ Physiol 2013; 304:H1538-46. [PMID: 23542919 DOI: 10.1152/ajpheart.00081.2013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Accumulating evidence suggests that insulin acts within the hypothalamus to alter sympathetic nerve activity (SNA) and baroreflex function. Although insulin receptors are widely expressed across the hypothalamus, recent evidence suggests that neurons of the arcuate nucleus (ARC) play an important role in the sympathoexcitatory response to insulin. The purpose of the present study was to determine whether circulating insulin acts directly in the ARC to elevate SNA. In anesthetized male Sprague-Dawley rats (275-425 g), the action of insulin was neutralized by microinjection of an anti-insulin affibody (1 ng/40 nl). To verify the efficacy of the affibody, ARC pretreatment with injection of the anti-insulin affibody completely prevented the increase in lumbar SNA produced by ARC injection of insulin. Next, ARC pretreatment with the anti-insulin affibody attenuated the lumbar sympathoexcitatory response to intracerebroventricular injection of insulin. Third, a hyperinsulinemic-euglycemic clamp increased lumbar, but not renal, SNA in animals that received ARC injection of a control affibody. However, this sympathoexcitatory response was absent in animals pretreated with the anti-insulin affibody in the ARC. Injection of the anti-insulin affibody in the adjacent ventromedial hypothalamus did not alter the sympathoexcitatory response to insulin. The ability of the anti-insulin affibody to prevent the sympathetic effects of insulin cannot be attributed to a general inactivation or nonspecific effect on ARC neurons as the affibody did not alter the sympathoexcitatory response to ARC disinhibition by gabazine. Collectively, these findings suggest that circulating insulin acts within the ARC to increase SNA.
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Affiliation(s)
- Brittany S Luckett
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
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Brooks VL, Cassaglia PA, Zhao D, Goldman RK. Baroreflex function in females: changes with the reproductive cycle and pregnancy. ACTA ACUST UNITED AC 2013; 9:61-7. [PMID: 22483197 DOI: 10.1016/j.genm.2012.02.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 02/24/2012] [Accepted: 02/27/2012] [Indexed: 11/15/2022]
Abstract
This review briefly describes the changes in baroreflex function that occur during female reproductive life, specifically during the reproductive cycle and pregnancy. The sensitivity or gain of baroreflex control of heart rate and sympathetic activity fluctuates during the reproductive cycle, reaching a peak when gonadal hormone levels increase, during the follicular phase in women and proestrus in rats. The increase in baroreflex sensitivity (BRS) is likely mediated by estrogen because ovariectomy in rats eliminates the BRS increase, the cyclic profile of changes in BRS mirror the changes in estrogen, and estrogen acts in the brainstem to increase BRS. In contrast, pregnancy depresses both BRS and the maximal level of sympathetic activity and heart rate evoked by severe hypotension. The decrease in BRS may be mediated by a reduction in the actions of insulin in the arcuate nucleus to support the baroreflex. In addition, increased levels of the neurosteroid progesterone metabolite 3α-OH-DHP act downstream in the rostral ventrolateral medulla to suppress maximal baroreflex increases in sympathetic activity. Consequently, these changes in baroreflex function impair blood pressure regulation in the presence of hypotensive challenges such as orthostasis and hemorrhage, a common event during delivery. As a result, peripartum hemorrhage is a major cause of human maternal death.
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Affiliation(s)
- Virginia L Brooks
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon 97239, USA.
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