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Halvorson BD, Bao Y, Singh KK, Frisbee SJ, Hachinski V, Whitehead SN, Melling CWJ, Chantler PD, Goldman D, Frisbee JC. Thromboxane-induced cerebral microvascular rarefaction predicts depressive symptom emergence in metabolic disease. J Appl Physiol (1985) 2024; 136:122-140. [PMID: 37969083 DOI: 10.1152/japplphysiol.00410.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 11/14/2023] [Accepted: 11/14/2023] [Indexed: 11/17/2023] Open
Abstract
Previous studies have suggested that the loss of microvessel density in the peripheral circulation with evolving metabolic disease severity represents a significant contributor to impaired skeletal muscle oxygenation and fatigue-resistance. Based on this and our recent work, we hypothesized that cerebral microvascular rarefaction was initiated from the increased prooxidant and proinflammatory environment with metabolic disease and is predictive of the severity of the emergence of depressive symptoms in obese Zucker rats (OZRs). In male OZR, cerebrovascular rarefaction followed the emergence of elevated oxidant and inflammatory environments characterized by increased vascular production of thromboxane A2 (TxA2). The subsequent emergence of depressive symptoms in OZR was associated with the timing and severity of the rarefaction. Chronic intervention with antioxidant (TEMPOL) or anti-inflammation (pentoxifylline) therapy blunted the severity of rarefaction and depressive symptoms, although the effectiveness was limited. Blockade of TxA2 production (dazmegrel) or action (SQ-29548) resulted in a stronger therapeutic effect, suggesting that vascular production and action represent a significant contributor to rarefaction and the emergence of depressive symptoms with chronic metabolic disease (although other pathways clearly contribute as well). A de novo biosimulation of cerebrovascular oxygenation in the face of progressive rarefaction demonstrates the increased probability of generating hypoxic regions within the microvascular networks, which could contribute to impaired neuronal metabolism and the emergence of depressive symptoms. The results of the present study also implicate the potential importance of aggressive prodromic intervention in reducing the severity of chronic complications arising from metabolic disease.NEW & NOTEWORTHY With clinical studies linking vascular disease risk to depressive symptom emergence, we used obese Zucker rats, a model of chronic metabolic disease, to identify potential mechanistic links between these two negative outcomes. Depressive symptom severity correlated with the extent of cerebrovascular rarefaction, after increased vascular oxidant stress/inflammation and TxA2 production. Anti-TxA2 interventions prevasculopathy blunted rarefaction and depressive symptoms, while biosimulation indicated that cerebrovascular rarefaction increased hypoxia within capillary networks as a potential contributing mechanism.
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Affiliation(s)
- Brayden D Halvorson
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Yuki Bao
- Department of Biomedical Engineering, University of Western Ontario, London, Ontario, Canada
| | - Krishna K Singh
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Stephanie J Frisbee
- Department of Pathology and Laboratory Medicine, University of Western Ontario, London, Ontario, Canada
| | - Vladimir Hachinski
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
| | - Shawn N Whitehead
- Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada
| | - C W James Melling
- Department of Kinesiology, University of Western Ontario, London, Ontario, Canada
| | - Paul D Chantler
- Division of Exercise Physiology, West Virginia University, Morgantown, West Virginia, United States
| | - Daniel Goldman
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Jefferson C Frisbee
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
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Dwivedi PS, Rasal VP, Chavan RS, Khanal P, Gaonkar VP. Feronia elephantum reverses insulin resistance in fructose-induced hyper-insulinemic rats; an in-silico, in-vitro, and in-vivo approach. JOURNAL OF ETHNOPHARMACOLOGY 2023:116686. [PMID: 37279812 DOI: 10.1016/j.jep.2023.116686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 05/13/2023] [Accepted: 05/24/2023] [Indexed: 06/08/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Feronia elephantum corr. (synonym: Feronia limonia, Murraya odorata, Schinus Limonia, or Limonia acidissima; common names: Bela, Kath, Billin, and Kavitha), belonging to the family Rutaceae has been known for clinical conditions such as pruritus, diarrhea, impotence, dysentery, heart diseases, and is also used as a liver tonic. However, the effect of the fruit pulp of F. elephantum on insulin resistance has yet not been reported. AIM OF THE STUDY The present study aimed to assess the effect of hydroalcoholic extract/fraction of F. elephantum fruit pulp on fasting blood glucose, oral glucose tolerance test, and glucose uptake in fructose-induced insulin-resistant rats and predict the gene-set enrichment of lead hits of F. elephantum with targets related to insulin resistance. MATERIAL AND METHODS System biology tools were used to predict the best category of fraction and propose a possible mechanism. Docking was carried out with adiponectin and its receptor (hub gene). Further, fructose supplementation was used for the induction of insulin resistance. Later, three doses of extract (400, 200, and 100 mg/kg) and a flavonoid-rich fraction (63 mg/kg) were used for treatment along with metformin as standard. The physical parameters like body weight, food intake, and water intake were measured along with oral glucose tolerance test, insulin tolerance test, glycogen content in skeletal muscles and liver, glucose uptake by rat hemidiaphragm, lipid profiles, anti-oxidant biomarkers, and histology of the liver and adipose tissue. RESULTS Network pharmacology reflected the potency of F. elephantum to regulate adiponectin (ADIPOQ) which may promote the reversal of insulin resistance and inhibit α-amylase and α-glucosidase. Vitexin was predicted to modulate the most genes associated with diabetes mellitus. Further, F. elephantum ameliorated the exogenous glucose clearance, promoted insulin sensitivity, reduced oxidative stress, and improved glucose and lipid metabolism. HPLC profiling revealed the presence of apigenin and quercetin in the extract for the first time. CONCLUSION The fruit pulp of F. elephantum reverses insulin resistance by an increase in glucose uptake and a decrease in gluconeogenesis which may be due to the regulation of multiple proteins via multiple bio-actives.
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Affiliation(s)
- Prarambh Sr Dwivedi
- Department of Pharmacology and Toxicology, KLE College of Pharmacy, Belagavi, KLE Academy of Higher Education and Research (KAHER), Belagavi, 590010, India.
| | - V P Rasal
- Department of Pharmacology, Rani Chennamma College of Pharmacy, Belagavi, 590010, India
| | - Rajashekar S Chavan
- Department of Pharmacology and Toxicology, KLE College of Pharmacy, Belagavi, KLE Academy of Higher Education and Research (KAHER), Belagavi, 590010, India
| | - Pukar Khanal
- Department of Pharmacology and Toxicology, KLE College of Pharmacy, Belagavi, KLE Academy of Higher Education and Research (KAHER), Belagavi, 590010, India.
| | - Vishakha Parab Gaonkar
- Department of Pharmaceutical Quality Assurance, KLE College of Pharmacy, Belagavi, KLE Academy of Higher Education and Research (KAHER), Belagavi, 590010, India
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Samaha MM, Helal MG, El-Sherbiny M, Said E, Salem HA. Indapamide Increases IRS1 Expression and Modifies Adiponectin/NLRP3/PPARγ Crosstalk in Type 2 Diabetic Rats. Antioxidants (Basel) 2022; 11:antiox11040691. [PMID: 35453376 PMCID: PMC9026493 DOI: 10.3390/antiox11040691] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 03/27/2022] [Accepted: 03/29/2022] [Indexed: 02/01/2023] Open
Abstract
The current study aimed to evaluate the anti-diabetic effects of canagliflozin (CANA) and indapamide (INDA) and their impacts as adiponectin modulators in experimentally induced type 2 diabetes mellitus (T2DM). T2DM was associated with a significant rise in blood glucose level and HbA1C%, andreduced adiponectin and insulin secretions. Moreover, the malondialdehyde (MDA) contents in both the epididymal adipocytes and soleus muscle significantly escalated, while the total antioxidant capacity (TAC) and epididymal adipocyte Nrf2 expression significantly declined. Moreover, serum TNF-α, epididymal adipocyte’s NOD-like receptor protein 3, NLRP3, NF-κB and CD68 expressions markedly escalated, and serum IL-10 significantly declined. Furthermore, there was a significant escalation in PPARγ expression in epididymal adipocytes, with a significant reduction in soleus muscle’s expression of IRS1. CANA and INDA treatments markedly reduced blood glucose levels, increased adiponectin and insulin secretion, enhanced anti-oxidant defenses, and reduced oxidative burden, with marked anti-inflammatory impact. Interestingly, the impact of indapamide on DM indices and oxidative and inflammatory changes was comparable to that of canagliflozin. Nevertheless, indapamide had a superior effect compared to canagliflozin on HbA1c%, expression of IRS1 and reduction of NF-κB and CD68 expressions. INDA could be effective in regulating T2DM, with underlined anti-diabetic, antioxidant, and anti-inflammatory properties. INDA increased IRS1 expression and modified adiponectin/NLRP3/PPARγ crosstalk. The impacts of INDA are comparable to those of the standard anti-diabetic drug CANA.
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Affiliation(s)
- Mahmoud M. Samaha
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt; (M.M.S.); (M.G.H.); (H.A.S.)
| | - Manar G. Helal
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt; (M.M.S.); (M.G.H.); (H.A.S.)
| | - Mohamed El-Sherbiny
- Department of Basic Medical Sciences, College of Medicine, AlMaarefa University, Riyadh P.O. Box 71666, Saudi Arabia;
- Department of Anatomy, Faculty of Medicine, Mansoura University, Mansoura 35516, Egypt
| | - Eman Said
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt; (M.M.S.); (M.G.H.); (H.A.S.)
- Faculty of Pharmacy, New Mansoura University, New Mansoura 7723730, Egypt
- Correspondence:
| | - Hatem A. Salem
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt; (M.M.S.); (M.G.H.); (H.A.S.)
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Khanal P, Patil BM. Reversal of insulin resistance by Ficus benghalensis bark in fructose-induced insulin-resistant rats. JOURNAL OF ETHNOPHARMACOLOGY 2022; 284:114761. [PMID: 34678414 DOI: 10.1016/j.jep.2021.114761] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 10/06/2021] [Accepted: 10/18/2021] [Indexed: 06/13/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Bark of Ficus benghalensis L. (family: Moraceae), commonly known as Banyan is recorded as Nyagrodha in Ayurvedic Pharmacopeia of India to manage burning sensation, obesity, diabetes, bleeding disorders, thirst, skin diseases, wounds, and dysmenorrhoea. However, the effect of F. benghalensis bark over glycolysis, gluconeogenesis, and appetite regulation in insulin-resistant pathogenesis has not been reported yet. AIM OF THE STUDY The present study aimed to investigate the effect of hydroalcoholic extract of F. benghalensis bark in gluconeogenesis, glycolysis, and appetite regulation in fructose-induced insulin resistance in experimental rats. MATERIALS AND METHODS Male Wister rats were supplemented with fructose in drinking water (10% w/v for 42 days and 20% w/v for next 12 days; a total of 54 days); insulin resistance was confirmed via the elevated area under the curve of the glucose during oral glucose tolerance test after 54 days and was subjected with extract treatment for next 30 days. After 30 days of treatment, animals were fasted to perform oral glucose and insulin tolerance test to estimate glucose and insulin levels. The blood sample was collected for biochemical estimation and the liver homogenate was prepared to estimate hepatic enzymes and enzymatic and non-enzymatic anti-oxidant biomarkers followed by histopathological evaluation. Also, glycogen content was quantified in gastrocnemius muscle and liver homogenates. Further, reported bioactives from the F. benghalensis were retrieved from the ChEBI database and docked against hexokinase, phosphofructokinase, glucose-6-phosphatase, lactate dehydrogenase, and fructose-1,6-biphosphatase to identify the probable lead hits against the enzymes involved in gluconeogenesis. RESULTS Treatment with the F. benghalensis bark extract significantly increased the body weight and food intake and significantly decreased fructose supplemented water intake. Further, treatment with extract significantly increased the exogenous glucose clearance and well responded to the exogenous insulin. Further, extract treatment improved lipid metabolism, ameliorated plasma leptin, and multiple enzymatic and non-enzymatic antioxidant biomarkers. Likewise, it also improved gluconeogenesis mediated pathogenesis of non-alcoholic fatty liver injury. Additionally, molecular docking also identified mucusisoflavone A and B as lead hits in downregulating gluconeogenesis. CONCLUSION Hydroalcoholic extract of F. benghalensis bark may prevent insulin resistance by downregulating gluconeogenesis and improving the appetite in fructose-induced insulin-resistant rats.
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Affiliation(s)
- Pukar Khanal
- Department of Pharmacology and Toxicology, KLE College of Pharmacy Belagavi, KLE Academy of Higher Education and Research (KAHER), Belagavi-590010, India.
| | - B M Patil
- Department of Pharmacology and Toxicology, KLE College of Pharmacy Belagavi, KLE Academy of Higher Education and Research (KAHER), Belagavi-590010, India.
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Samaha MM, Helal MG, El-Sherbiny M, Said E, Salem HA. Diacerein versus adipoRon as adiponectin modulators in experimentally-induced end-stage type 2 diabetes mellitus in rats. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2022; 90:103806. [PMID: 34974166 DOI: 10.1016/j.etap.2021.103806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Revised: 12/25/2021] [Accepted: 12/28/2021] [Indexed: 06/14/2023]
Abstract
The objective of the present study is to evaluate and compare the possible anti-diabetic effects of adipoRon and diacerein in type 2 diabetes mellitus (T2DM) rats. T2DM is marked by impaired oxidative, inflammatory and metabolic signaling. Indeed, T2DM progression is associated with elevated HbA1C%, low adiponectin and insulin concentration. Moreover, in this study epididymal adipose tissue and soleus muscle MDA contents significantly escalated, while serum TAC and epididymal adipose Nrf2 significantly declined. Nevertheless, serum TNF-α, epididymal NLRP3, NF-κB, PPARγ and CD68 expression rose significantly with a parallel significant reduction in serum IL-10 and soleus muscle expression of IRS1. Both adipoRon and diacerein significantly improved adiponectin and insulin secretion with augmentation of anti-oxidant defenses and diminution of oxidative burden, with obvious anti-inflammatory consequences (p < 0.05). Thus, adipoRon and diacerein positively modulated adiponectin expression with down-regulation of NF-κB/NLRP3/PPARγ expression with subsequent improvement in glycemic control, inflammatory and oxidative signaling.
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Affiliation(s)
- Mahmoud M Samaha
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Manar G Helal
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Mohamed El-Sherbiny
- Department of Basic Medical Sciences, College of Medicine, Almaarefa University, P.O. Box 71666, Riyadh, 11597, Saudi Arabia; Department of Anatomy, Faculty of Medicine, Mansoura University, Mansoura, Egypt.
| | - Eman Said
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt; Faculty of Pharmacy, New Mansoura University, 7723730 New Mansoura, Egypt.
| | - Hatem A Salem
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
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Yang JY, Zhang TT, Dong Z, Shi HH, Xu J, Mao XZ, Wang YM, Xue CH. Dietary Supplementation with Exogenous Sea-Cucumber-Derived Ceramides and Glucosylceramides Alleviates Insulin Resistance in High-Fructose-Diet-Fed Rats by Upregulating the IRS/PI3K/Akt Signaling Pathway. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:9178-9187. [PMID: 33560835 DOI: 10.1021/acs.jafc.0c06831] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Endogenous ceramide is considered to be associated with the progress of insulin resistance. However, the effects of dietary exogenous glucosylceramides and ceramides on insulin resistance are unclear. A model of fructose-induced male Sprague Dawley rats was used to compare the effects of sea-cucumber-derived glucosylceramides and ceramides on insulin resistance. Both glucosylceramides and ceramides significantly improved glucose tolerance, reduced the concentrations of serum glucose and glycosylated hemoglobin, and alleviated the accompanied hypertension. Ceramides significantly enhanced glycogen levels in skeletal muscle, whereas glucosylceramides significantly increased the hepatic glycogen levels. Moreover, glucosylceramides alleviated insulin resistance by inhibiting gluconeogenesis, promoting glycogen synthesis and insulin signal transduction in the liver; meanwhile, ceramides were mainly due to the promotion of glycogen synthesis and insulin signal transduction in skeletal muscle. Additionally, glucosylceramides and ceramides effectively attenuated inflammation in adipose tissue. These results indicate that glucosylceramides and ceramides have potential value in the prevention and alleviation of insulin resistance.
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Affiliation(s)
- Jin-Yue Yang
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong 266003, People's Republic of China
| | - Tian-Tian Zhang
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong 266003, People's Republic of China
| | - Zhe Dong
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong 266003, People's Republic of China
| | - Hao-Hao Shi
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong 266003, People's Republic of China
| | - Jie Xu
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong 266003, People's Republic of China
| | - Xiang-Zhao Mao
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong 266003, People's Republic of China
- Laboratory of Marine Drugs & Biological Products, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, Shandong 266237, People's Republic of China
| | - Yu-Ming Wang
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong 266003, People's Republic of China
- Laboratory of Marine Drugs & Biological Products, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, Shandong 266237, People's Republic of China
| | - Chang-Hu Xue
- College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong 266003, People's Republic of China
- Laboratory of Marine Drugs & Biological Products, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, Shandong 266237, People's Republic of China
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Brands MW. Role of Insulin-Mediated Antinatriuresis in Sodium Homeostasis and Hypertension. Hypertension 2018; 72:1255-1262. [DOI: 10.1161/hypertensionaha.118.11728] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Michael W. Brands
- From the Department of Physiology, Medical College of Georgia, Augusta, GA
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Shaligram S, Sangüesa G, Akther F, Alegret M, Laguna JC, Rahimian R. Differential effects of high consumption of fructose or glucose on mesenteric arterial function in female rats. J Nutr Biochem 2018; 57:136-144. [PMID: 29727795 DOI: 10.1016/j.jnutbio.2018.03.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 01/16/2018] [Accepted: 03/20/2018] [Indexed: 12/25/2022]
Abstract
We have recently shown that type of supplemented simple sugar, not merely calorie intake, determines adverse effects on metabolism and aortic endothelial function in female rats. The aim of the current study was to investigate and compare the effects of high consumption of glucose or fructose on mesenteric arterial reactivity and systolic blood pressure (SBP). Sprague-Dawley female rats were supplemented with 20% w/v glucose or fructose in drinking water for 8 weeks. Here, we show that both sugars alter insulin signaling in mesenteric arteries (MA), assessed by a reduction in phosphorylated Akt, and increase in SBP. Furthermore, ingestion of glucose or fructose enhances inducible nitric oxide synthase (iNOS) expression and contractile responses to endothelin and phenylephrine in MA of rats. The endothelium-dependent vasodilation to acetylcholine and bradykinin as well as the relaxation responses to the nitric oxide donor sodium nitroprusside are impaired in MA of fructose- but not glucose-supplemented rats. In contrast, only glucose supplementation increases the expression of phosphorylated endothelial NOS (eNOS) in MA of rats. In conclusion, this study reveals that supplementation with fructose or glucose in liquid form enhances vasocontractile responses and increases iNOS expression in MA, effects which are accompanied by increased SBP in those groups. On the other hand, the preserved vasodilatory responses in MA from glucose-supplemented rats could be attributed to the enhanced level of phosphorylated eNOS expression in this group.
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Affiliation(s)
- Sonali Shaligram
- Department of Physiology & Pharmacology, Thomas J. Long School of Pharmacy & Health Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Gemma Sangüesa
- Department of Pharmacology Toxicology and Therapeutic Chemistry, School of Pharmacy and Food Sciences, University of Barcelona
| | - Farjana Akther
- Department of Physiology & Pharmacology, Thomas J. Long School of Pharmacy & Health Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Marta Alegret
- Department of Pharmacology Toxicology and Therapeutic Chemistry, School of Pharmacy and Food Sciences, University of Barcelona; IBUB (Institute of Biomedicine, University of Barcelona); CIBERobn (Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición)
| | - Juan C Laguna
- Department of Pharmacology Toxicology and Therapeutic Chemistry, School of Pharmacy and Food Sciences, University of Barcelona; IBUB (Institute of Biomedicine, University of Barcelona); CIBERobn (Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición)
| | - Roshanak Rahimian
- Department of Physiology & Pharmacology, Thomas J. Long School of Pharmacy & Health Sciences, University of the Pacific, Stockton, CA 95211, USA.
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Thompson JA, D'Angelo G, Mintz JD, Fulton DJ, Stepp DW. Pressor recovery after acute stress is impaired in high fructose-fed Lean Zucker rats. Physiol Rep 2016; 4:4/12/e12758. [PMID: 27335430 PMCID: PMC4923227 DOI: 10.14814/phy2.12758] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 03/16/2016] [Indexed: 11/24/2022] Open
Abstract
Insulin resistance is a powerful predictor of cardiovascular disease; however, the mechanistic link remains unclear. This study aims to determine if early cardiovascular changes associated with short‐term fructose feeding in the absence of obesity manifest as abnormal blood pressure control. Metabolic dysfunction was induced in Lean Zucker rats by short‐term high‐fructose feeding. Rats were implanted with telemetry devices for the measurement of mean arterial blood pressure (MAP) and subjected to air jet stress at 5 and 8 weeks after feeding. Additional animals were catheterized under anesthesia for the determination of MAP and blood flow responses in the hind limb and mesenteric vascular beds to intravenous injection of isoproterenol (0.001–0.5 μm), a β‐adrenergic agonist. Metabolic dysfunction in high‐fructose rats was not accompanied by changes in 24‐h MAP. Yet, animals fed a high‐fructose diet for 8 weeks exhibited a marked impairment in blood pressure recovery after air‐jet stress. Dose‐dependent decreases in MAP and peripheral blood flow in response to isoproterenol treatment were significantly attenuated in high‐fructose rats. These data suggest that impaired blood pressure recovery to acute mental stress precedes the onset of hypertension in the early stages of insulin resistance. Further, blunted responses to isoproterenol implicate β2‐adrenergic sensitivity as a possible mechanism responsible for altered blood pressure control after short‐term high‐fructose feeding.
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Affiliation(s)
| | - Gerard D'Angelo
- Vascular Biology Center, Georgia Regents University, Augusta, Georgia
| | - James D Mintz
- Vascular Biology Center, Georgia Regents University, Augusta, Georgia
| | - David J Fulton
- Vascular Biology Center, Georgia Regents University, Augusta, Georgia
| | - David W Stepp
- Vascular Biology Center, Georgia Regents University, Augusta, Georgia
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Effects of Lesions to Capsaicin-Sensitive Nerves on Blood Pressure in Metabolic Syndrome in Rats. ACTA ACUST UNITED AC 2015. [DOI: 10.1007/s11055-015-0109-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Shawky NM, Shehatou GS, Abdel Rahim M, Suddek GM, Gameil NM. Levocetirizine ameliorates high fructose diet-induced insulin resistance, vascular dysfunction and hepatic steatosis in rats. Eur J Pharmacol 2014; 740:353-63. [DOI: 10.1016/j.ejphar.2014.07.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 07/09/2014] [Accepted: 07/11/2014] [Indexed: 11/15/2022]
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Moreno JA, Hong E. A single oral dose of fructose induces some features of metabolic syndrome in rats: role of oxidative stress. Nutr Metab Cardiovasc Dis 2013; 23:536-542. [PMID: 22386006 DOI: 10.1016/j.numecd.2011.10.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 10/04/2011] [Accepted: 10/25/2011] [Indexed: 10/28/2022]
Abstract
BACKGROUND AND AIMS To determine if a single oral dose of fructose to rats reproduces some features of metabolic syndrome observed after chronic administration and if so, to investigate its mechanisms. METHODS AND RESULTS Systolic blood pressure was measured in rats before and after oral administration of fructose, and in animals pretreated with lipoic acid, methyldopa, losartan or streptozotocin. In other rats, glucose, insulin, uric acid, and insulin sensitivity index, were determined before and after fructose or lipoic acid plus fructose. Glutathione was measured in liver before and after fructose administration. In aortic rings from other rats, incubation with mannitol, fructose, or fructose plus lipoic acid was evaluated on the relaxation by acetylcholine. Fructose produced a moderate increase in blood pressure, which was prevented by lipoic acid or streptozotocin. Methyldopa and losartan decreased the pressor response minimally. Fructose increased oxidized glutathione, plasma glucose, insulin and uric acid, and diminished the insulin sensitivity index, and the reduced glutathione. Lipoic acid prevented hyperglycemia and hyperuricemia, and improved the insulin sensitivity index. Finally, endothelial dysfunction was prevented by lipoic acid. CONCLUSION A single dose of fructose reproduces some of the features of metabolic syndrome, most changes were caused by oxidative stress and insulin resistance.
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Affiliation(s)
- J A Moreno
- Faculty of Medicine, UNAM, Coyoacán DF 04510, Mexico.
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Zhou K, Kumar U, Yuen VG, McNeill JH. The effects of phentolamine on fructose-fed rats. Can J Physiol Pharmacol 2012; 90:1075-85. [DOI: 10.1139/y2012-063] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Metabolic syndrome (MS) is a combination of medical disorders that increase the risk of developing cardiovascular disease and diabetes. MS is associated with obesity, increased blood pressure, hyperlipidemia, and hyperglycemia. This study was designed to investigate the pharmacological profile of phentolamine, a nonselective α adrenergic receptor antagonist, in the prevention of increased blood pressure in fructose-fed rats. Phentolamine prevented the fructose-induced increase in systolic blood pressure without affecting insulin sensitivity and major metabolic parameters. The levels of plasma noradrenaline and angiotensin II, 2 proposed contributors to the development of fructose-induced elevated blood pressure, were examined. Neither noradrenaline nor angiotensin II levels were affected by phentolamine treatment. Since overproduction of nitric oxide has been shown to lead to an elevation in peroxynitrite, the role of oxidative stress, a proposed mechanism of fructose-induced elevated blood pressure and insulin resistance, was examined by measuring plasma levels of total nitrate/nitrite. Plasma nitrate/nitrite was significantly elevated in all fructose-fed animals, regardless of treatment with phentolamine. Another proposed contributor toward fructose-induced MS is an elevation in uric acid levels. In this experiment, plasma levels of uric acid were found to be increased by dietary fructose and were unaffected by phentolamine treatment.
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Affiliation(s)
- Kangbin Zhou
- The University of British Columbia, Faculty of Pharmaceutical Sciences, 2146 East Mall, Vancouver, BC V6T 1Z3, Canada
| | - Ujendra Kumar
- The University of British Columbia, Faculty of Pharmaceutical Sciences, 2146 East Mall, Vancouver, BC V6T 1Z3, Canada
| | - Violet G. Yuen
- The University of British Columbia, Faculty of Pharmaceutical Sciences, 2146 East Mall, Vancouver, BC V6T 1Z3, Canada
| | - John H. McNeill
- The University of British Columbia, Faculty of Pharmaceutical Sciences, 2146 East Mall, Vancouver, BC V6T 1Z3, Canada
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Bhatt NM, Chavda M, Desai D, Zalawadia R, Patel VB, Burade V, Sharma AK, Singal PK, Gupta S. Cardioprotective and antihypertensive effects of Enicostemma littorale Blume extract in fructose-fed rats. Can J Physiol Pharmacol 2012; 90:1065-73. [PMID: 22784355 DOI: 10.1139/y2012-055] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the protective effects of Enicostemma littorale Blume (EL) extract on hypertension and insulin resistance along with its associated cardiovascular complications in high fructose (HF) fed rats. For this, rats were divided among 4 groups: (i) control, fed laboratory chow; (ii) fed with a high level of fructose; (iii) fed with a high level of fructose plus E. littorale extract; and (iv) fed with a high level of fructose plus rosiglitazone (Rg). EL and Rg treatments were given simultaneously with HF diet. The results show that untreated HF-fed rats showed altered oral glucose tolerance, increased fasting insulin, and increased fasting glucose. These rats also exhibited hypertriglyceridemia, moderate hypertension, platelet hyperaggregability, decreased prothrombin time, activated partial thromboplastin time, altered vascular reactivity, and increased serum levels of enzymes (creatine kinase, type muscle-brain (CK-MB), aspartate aminotransferase (SGOT), lactate dehydrogenase (LDH), and alanine aminotransferase (SGPT). This is the first demonstration of platelet hyperaggregation and prothrombotic alteration in HF-fed rats. HF-fed rats treated with EL showed improved insulin resistance, along with reduced hypertriglyceridemia, hypertension, platelet aggregability, blood coagulation, serum enzymes (CK-MB, SGOT, LDH and SGPT), and vascular reactivity. These effects of EL in HF-induced hypertensive rats might be associated with the suppression of hyperinsulinemia and hypertriglyceridemia, along with its antiatherogenic and antithrombogenic potential. These data indicate that the aqueous extract of EL has great therapeutic potential for the prevention and (or) management of insulin resistance and the associated hypertension.
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Affiliation(s)
- Niraj M Bhatt
- Department of Biochemistry, Faculty of Science, The M.S. University of Baroda, Vadodara, India
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15
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Testosterone-dependent increase in blood pressure is mediated by elevated Cyp4A expression in fructose-fed rats. Mol Cell Biochem 2011; 359:409-18. [PMID: 21894443 DOI: 10.1007/s11010-011-1035-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 08/13/2011] [Indexed: 01/13/2023]
Abstract
Endothelial dysfunction and increased blood pressure following insulin resistance play an important role in the development of secondary cardiovascular complications. The presence of testosterone is essential for the development of endothelial dysfunction and increased blood pressure. Testosterone regulates the synthesis of vasoconstrictor eicosanoids such as 20-hydroxyeicosatetranoic acid (20-HETE). In a series of studies, we examined: (1) the role of the androgen receptor in elevating blood pressure and (2) the effects of Cyp4A-catalyzed 20-HETE synthesis on vascular reactivity and blood pressure in fructose-fed rats. In the first study, intact and castrated male rats were made insulin resistant by feeding fructose for 9 weeks following which their superior mesenteric arteries (SMA) were isolated and examined for changes in endothelium-dependent relaxation in the presence and absence of 1-aminobenzotriazole (ABT) and N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS), which are inhibitors of 20-HETE synthesis. In another study, male rats were treated with either ABT or the androgen receptor blocker, flutamide, following which changes in insulin sensitivity, blood pressure, and vascular Cyp4A expression were measured. In the final study, HET0016, which is a more selective inhibitor of 20-HETE synthesis, was used to confirm our earlier findings. Treatment with HET0016 or ABT prevented or ameliorated the increase in blood pressure. Gonadectomy or flutamide prevented the increase in both the Cyp4A and blood pressure. Furthermore, both ABT and DDMS improved relaxation only in the intact fructose-fed rats. Taken together our results suggest that in the presence of testosterone, the Cyp4A/20-HETE system plays a key role in elevating the blood pressure secondary to insulin resistance.
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Abdulla MH, Sattar MA, Johns EJ. The Relation between Fructose-Induced Metabolic Syndrome and Altered Renal Haemodynamic and Excretory Function in the Rat. Int J Nephrol 2011; 2011:934659. [PMID: 21785727 PMCID: PMC3139200 DOI: 10.4061/2011/934659] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 04/30/2011] [Accepted: 05/15/2011] [Indexed: 11/20/2022] Open
Abstract
This paper explores the possible relationships between dietary fructose and altered neurohumoral regulation of renal haemodynamic and excretory function in this model of metabolic syndrome. Fructose consumption induces hyperinsulinemia, hypertriglyceridaemia, insulin resistance, and hypertension. The pathogenesis of fructose-induced hypertension is dubious and involves numerous pathways acting both singly and together. In addition, hyperinsulinemia and hypertension contribute significantly to progressive renal disease in fructose-fed rats. Moreover, increased activity of the renin-angiotensin and sympathetic nervous systems leading to downregulation of receptors may be responsible for the blunted vascular sensitivity to angiotensin II and catecholamines, respectively. Various approaches have been suggested to prevent the development of fructose-induced hypertension and/or metabolic alteration. In this paper, we address the role played by the renin-angiotensin and sympathetic nervous systems in the haemodynamic alterations that occur due to prolonged consumption of fructose.
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Affiliation(s)
- Mohammed H Abdulla
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, 11800 Penang, Malaysia
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Palanisamy N, Viswanathan P, Ravichandran MK, Anuradha CV. Renoprotective and blood pressure-lowering effect of dietary soy protein via protein kinase C beta II inhibition in a rat model of metabolic syndrome. Can J Physiol Pharmacol 2010; 88:28-37. [PMID: 20130736 DOI: 10.1139/y09-110] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
We studied whether substitution of soy protein for casein can improve insulin sensitivity, lower blood pressure (BP), and inhibit protein kinase C betaII (PKCbetaII) activation in kidney in an acquired model of metabolic syndrome. Adult male rats were fed 4 different diets: (i) starch (60%) and casein (20%) (CCD), (ii) fructose (60%) and casein (20%) (FCD), (iii) fructose (60%) and soy protein (20%) (FSD), and (iv) starch (60%) and soy protein (20%) (CSD). Renal function parameters, BP, pressor mechanisms, PKCbetaII expression, oxidative stress, and renal histology were evaluated after 60 days. FCD rats displayed insulin resistance and significant changes in body weight, kidney weight, urine volume, plasma and urine electrolytes accompanied by significant changes in renal function parameters compared with CCD rats. Elevated BP, plasma angiotensin-converting enzyme (ACE) activity, renal oxidative stress, and reduced nitrite (NO) and kallikrein activity were observed. Western blot analysis revealed enhanced renal expression of membrane-associated PKCbetaII in the FCD group. Histology showed fatty infiltration and thickening of glomeruli while urinary protein profile revealed a 5-fold increase in albumin. Substitution of soy protein for casein improved insulin sensitivity, lowered BP and PKCbetaII activation and restored renal function. Antioxidant action, inhibitory effect on ACE and PKCbetaII activation, and increased availability of kinins and NO could be contributing mechanisms for the benefits of dietary soy protein.
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Affiliation(s)
- Nallasamy Palanisamy
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalai Nagar, Tamil Nadu 608002, India
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Oreocnide integrifolia (Gaud.) Miq leaf water extract improves metabolic alterations in high fructose fed insulin resistant and hypertensive rats. Eur J Integr Med 2010. [DOI: 10.1016/j.eujim.2010.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Pérez-Torres I, El Hafidi M, Pavón N, Infante O, Avila-Casado MC, Baños G. Effect of gonadectomy on the metabolism of arachidonic acid in isolated kidney of a rat model of metabolic syndrome. Metabolism 2010; 59:414-23. [PMID: 19801156 DOI: 10.1016/j.metabol.2009.08.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 07/30/2009] [Accepted: 08/12/2009] [Indexed: 01/10/2023]
Abstract
Influence of sex on arachidonic acid metabolism, a pathway involved in the link between metabolic syndrome (MS) and renal damage, was studied in isolated perfused kidney. Metabolic syndrome was induced by feeding 30% sucrose solution for 24 weeks to intact and gonadectomized female (Ovx) and male (Cas) rats. Systolic blood pressure, albuminuria, as well as prostaglandin E(2) and thromboxane B(2) from urine and perfusate increased in MS male and MS ovariectomized females; castration reduced them in MS males. Perfusion of arachidonic acid in kidneys from MS males increased perfusion pressure compared with controls. No difference appeared in perfusion pressure between control and MS females. Castration diminished perfusion pressure in MS; the opposite was observed in Ovx MS. Perfusion with arachidonic acid plus indomethacin decreased perfusion pressure in MS male kidneys and in Cas MS. In Ovx MS, arachidonic acid plus indomethacin decreased perfusion pressure, but not in female control, MS, and Ovx control. Increase in perfusion pressure with arachidonic acid in both male MS and Ovx MS was related to cyclooxygenase (COX)-1 and COX-2 overexpression in kidney. Castration reduced the expression of COX-1 and COX-2 in MS to control levels. The results suggest that the alteration in arachidonic acid metabolism associated with changes in the expression of COX-1 and COX-2 induced by sucrose intake, and influenced by sex hormones, may contribute to renal damage.
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Affiliation(s)
- Israel Pérez-Torres
- Department of Pathology, Instituto Nacional de Cardiología Ignacio Chávez Juan Badiano 1, Sección XVI, Tlalpan, 14080 México DF, México
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Mustafa S, Vasudevan H, Yuen VG, McNeill JH. Renal expression of arachidonic acid metabolizing enzymes and RhoA/Rho kinases in fructose insulin resistant hypertensive rats. Mol Cell Biochem 2009; 333:203-9. [PMID: 19633817 DOI: 10.1007/s11010-009-0220-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Accepted: 07/09/2009] [Indexed: 01/29/2023]
Abstract
Fructose feeding has been shown to induce insulin resistance and hypertension. Renal protein expression for the cytochrome P (CYP) 450 arachidonic acid metabolizing enzymes has been shown to be altered in other models of diet-induced hypertension. Of special interest is CYP4A, which produces the potent vasoconstrictor, 20-hydroxyeicosatetraenoic acid and CYP2C, which catalyzes the formation of the potent dilators epoxyeicosatrienoic acids as well as soluble epoxide hydrolase (sEH) which metabolizes the latter to dihydroxyeicosatrienoic acids. The RhoA/Rho kinase (ROCK) signaling pathway is downstream of arachidonic acid and is reported to mediate metabolic-cardio-renal dysfunctions in some experimental models of insulin resistance and diabetes. The aim of the present study was to determine the expression of CYP4A, CYP2C23, CYP2C11, sEH, RhoA, ROCK-1, ROCK-2, and phospho-Lin-11/Isl-1/Mec-3 kinase (LIMK) in kidneys of fructose-fed (F) rats. Male Wistar rats were fed a high fructose diet for 8 weeks. Body weight, systolic blood pressure, insulin sensitivity, and renal expression of the aforementioned proteins were assessed. No change was observed in the body weight of F rats; however, euglycemia and hyperinsulinemia implicating impaired glucose tolerance and significant elevation in systolic blood pressure were observed. Renal expression of CYP4A and CYP2C23 was significantly increased while that of CYP2C11 and sEH was not changed in F rats. Equal expression for RhoA in both control and F rats and an enhanced level of ROCK-1 and ROCK-2 constitutively activate 130 kDa cleavage fragments as well as phospho-LIMK. These data suggest that the kidneys could be actively participating in the pathogenesis of insulin resistance-induced hypertension through the arachidonic acid CYP 450-RhoA/Rho kinase pathway(s).
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Affiliation(s)
- Sally Mustafa
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, The University of British Columbia, 2146 East Mall, Vancouver, BC, V6T 1Z3, Canada
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Peredo H, Mayer M, Carranza A, Puyó A. Pioglitazone and Losartan Modify Hemodynamic and Metabolic Parameters and Vascular Prostanoids in Fructose-Overloaded Rats. Clin Exp Hypertens 2009; 30:159-69. [DOI: 10.1080/10641960801946889] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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22
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Abnormalities of endothelium-dependent responses in mesenteric arteries from Otsuka Long-Evans Tokushima Fatty (OLETF) rats are improved by chronic treatment with thromboxane A2 synthase inhibitor. Atherosclerosis 2009; 205:87-95. [DOI: 10.1016/j.atherosclerosis.2008.11.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Revised: 10/24/2008] [Accepted: 11/12/2008] [Indexed: 11/22/2022]
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23
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Tran LT, Yuen VG, McNeill JH. The fructose-fed rat: a review on the mechanisms of fructose-induced insulin resistance and hypertension. Mol Cell Biochem 2009; 332:145-59. [PMID: 19536638 DOI: 10.1007/s11010-009-0184-4] [Citation(s) in RCA: 258] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 06/09/2009] [Indexed: 02/07/2023]
Abstract
The metabolic syndrome is an important public health concern that predisposes individuals to the development of cardiovascular disease and/or Type 2 diabetes. The fructose-fed rat is an animal model of acquired systolic hypertension that displays numerous features of the metabolic syndrome. This animal model is used to study the relationship between insulin resistance/compensatory hyperinsulinemia and the development of hypertension. Several mechanisms have been proposed to mediate the link between insulin resistance and hypertension. In this review, we have addressed the role of sympathetic nervous system overactivation, increased production of vasoconstrictors, such as endothelin-1 and angiotensin II, and prostanoids in the development of hypertension in fructose-fed rats. The roles of nitric oxide, impaired endothelium-dependent relaxation and sex hormones in the pathogenesis of the fructose-fed induced hypertensive rats have also been highlighted. More recently, increased formation of reactive oxygen species and elevated levels of uric acid have been reported to contribute to fructose-induced hypertension.
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Affiliation(s)
- Linda T Tran
- Division of Pharmacology & Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, V6T 1Z3, Canada
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Hsieh PS, Jin JS, Chiang CF, Chan PC, Chen CH, Shih KC. COX-2-mediated inflammation in fat is crucial for obesity-linked insulin resistance and fatty liver. Obesity (Silver Spring) 2009; 17:1150-7. [PMID: 19247274 DOI: 10.1038/oby.2008.674] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The aim was to examine the role of cyclooxygenase (COX)-2-mediated inflammation in the development of obese linked insulin resistance and fatty liver. The rats were fed separately regular diet (CONT), high-fat diet (HFD) ad libitum, or energy restrictedly for 12 weeks. Rats fed HFD ad libitum were further divided into three subgroups co-treated with vehicle (HFa), or a selective COX-2 inhibitor celecoxib (HFa-Cel) or mesulid (HFa-Mes). Euglycemic hyperinsulinemic clamp (EHC) experiment was performed at the end of study. Another set of rats with similar grouping was further divided into those with a 4, 8, or 12-week intervention period for hepatic sampling. Body weight was increased significantly and similarly in HFa, HFa-Cel, and HFa-Mes. Time-dependent increases in plasma insulin, glucose, 8-isoprostanes, leptin levels, homeostasis model assessment of insulin resistance (HOMA-IR) and hepatic triglyceride contents shown in HFa were significantly reversed in HFa-Cel and HFa-Mes. During EHC period, the reduction in stimulation of whole body glucose uptake, suppression of hepatic glucose production and metabolic clearance rate of insulin shown in HFa were significantly reversed in HFa-Cel and HFa-Mes. The enhanced COX-2 and tumor necrosis factor-alpha (TNF-alpha) but attenuated PPAR-gamma and C/EBP-alpha mRNA expressions in epididymal fat shown in HFa were significantly reversed in HFa-Cel and HFa-Mes. The increases in average cell size of adipocytes and CD68 positive cells shown in HFa were also significantly reversed in HFa-Cel and HFa-Mes. Our findings suggest that COX-2 activation in fat inflammation is important in the development of insulin resistance and fatty liver in high fat induced obese rats.
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Affiliation(s)
- Po-Shiuan Hsieh
- Department of Physiology and Biophysics, National Defense Medical Center, Taipei, Taiwan.
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Chronic etanercept treatment prevents the development of hypertension in fructose-fed rats. Mol Cell Biochem 2009; 330:219-28. [PMID: 19440659 DOI: 10.1007/s11010-009-0136-z] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Accepted: 04/16/2009] [Indexed: 12/12/2022]
Abstract
The purpose of this study was to investigate the effect of chronic treatment with etanercept (a soluble recombinant fusion protein consisting of the extracellular ligand-binding domain of tumor necrosis factor receptor type 2) on the development of hypertension in fructose-fed rats (FFR). High fructose feeding and treatment with etanercept (0.3 mg/kg, three times per week) was initiated simultaneously in male Wistar rats. Systolic blood pressure, fasted plasma parameters, insulin sensitivity, vascular reactivity, plasma angiotensin II (Ang II), and norepinephrine were determined following 9 weeks of treatment. FFR exhibited insulin resistance, hyperinsulinemia, hypertriglyceridemia, endothelial dysfunction, and hypertension. Treatment with etanercept prevented the rise in blood pressure without affecting insulin levels, insulin sensitivity, triglycerides, or Ang II levels in FFR. Etanercept treatment improved acetylcholine-induced relaxation and normalized endothelial nitric oxide synthase expression in aortas from FFR. The results of this study suggest that treatment with etanercept prevented the development of hypertension by improving vascular function and restoring endothelial nitric oxide synthase expression in FFR.
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Tran LT, MacLeod KM, McNeill JH. Endothelin-1 modulates angiotensin II in the development of hypertension in fructose-fed rats. Mol Cell Biochem 2009; 325:89-97. [PMID: 19139972 DOI: 10.1007/s11010-008-0023-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Accepted: 12/30/2008] [Indexed: 02/07/2023]
Abstract
Two of the most potent vasoconstrictors, endothelin-1 (ET-1) and angiotensin II (Ang II), are upregulated in fructose hypertensive rats. It is unknown whether an interrelationship exists between these peptides that may contribute to the development of fructose-induced hypertension. The objective of this study was to investigate the existence of an interaction between the endothelin and renin angiotensin systems that may play a role in the development of fructose-induced hypertension. High fructose feeding and treatment with either bosentan, a dual endothelin receptor antagonist, or with L-158,809, an angiotensin type 1 receptor antagonist, were initiated simultaneously in male Wistar rats. Systolic blood pressure, fasted plasma parameters, insulin sensitivity, plasma Ang II, and vascular ET-1-immunoreactivity were determined following 6 weeks of high fructose feeding. Rats fed with a high fructose diet exhibited insulin resistance, hyperinsulinemia, hypertriglyceridemia, hypertension, and elevated plasma Ang II. Treatment with either bosentan or L-158,809 significantly attenuated the rise in blood pressure with no effect on insulin levels or insulin sensitivity in fructose-fed rats. Bosentan treatment significantly reduced plasma Ang II levels, while L-158,809 treatment significantly increased vascular ET-1-immunoreactivity in fructose-fed rats. Thus, treatment with the endothelin receptor antagonist prevented the development of fructose-induced hypertension and decreased plasma Ang II levels. These data suggest that ET-1 contributes to the development of fructose-induced hypertension through modulation of Ang II levels.
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Affiliation(s)
- L T Tran
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, V6T 1Z3, Canada
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Brands MW, Bell TD, Rodriquez NA, Polavarapu P, Panteleyev D. Chronic glucose infusion causes sustained increases in tubular sodium reabsorption and renal blood flow in dogs. Am J Physiol Regul Integr Comp Physiol 2008; 296:R265-71. [PMID: 19073906 DOI: 10.1152/ajpregu.90528.2008] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study tested the hypothesis that inducing hyperinsulinemia and hyperglycemia in dogs, by infusing glucose chronically intravenously, would increase tubular sodium reabsorption and cause hypertension. Glucose was infused for 6 days (14 mg.kg(-1).min(-1) iv) in five uninephrectomized (UNX) dogs. Mean arterial pressure (MAP) and renal blood flow (RBF) were measured 18 h/day using DSI pressure units and Transonic flow probes, respectively. Urinary sodium excretion (UNaV) decreased significantly on day 1 and remained decreased over the 6 days, coupled with a significant, sustained increase in RBF, averaging approximately 20% above control on day 6. Glomerular filtration rate and plasma renin activity (PRA) also increased. However, although MAP tended to increase, this was not statistically significant. Therefore, the glucose infusion was repeated in six dogs with 70% surgical reduction in kidney mass (RKM) and high salt intake. Blood glucose and plasma insulin increased similar to the UNX dogs, and there was significant sodium retention, but MAP still did not increase. Interestingly, the increases in PRA and RBF were prevented in the RKM dogs. The decrease in UNaV, increased RBF, and slightly elevated MAP show that glucose infusion in dogs caused a sustained increase in tubular sodium reabsorption by a mechanism independent of pressure natriuresis. The accompanying increase in PRA, together with the failure of either RBF or PRA to increase in the RKM dogs, suggests the site of tubular reabsorption was before the macula densa. However, the volume retention and peripheral edema suggest that systemic vasodilation offsets any potential renal actions to increase MAP in this experimental model in dogs.
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Affiliation(s)
- Michael W Brands
- Department of Physiology, CA-3098, Medical College of Georgia, Augusta, GA 30912-3000, USA.
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Hsieh PS, Tsai HC, Kuo CH, Chan JYH, Shyu JF, Cheng WT, Liu TT. Selective COX2 inhibition improves whole body and muscular insulin resistance in fructose-fed rats. Eur J Clin Invest 2008; 38:812-9. [PMID: 19021698 DOI: 10.1111/j.1365-2362.2008.02026.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
BACKGROUND The effects of cyclooxygenase-1 (COX1) and cyclooxygenase-2 (COX2) inhibition on insulin resistance in subjects with the metabolic syndrome remain elusive. Aims of this study were to examine the effects of COX1 and COX2 inhibitors on whole body and muscular insulin resistance in fructose-fed rats, an animal model of the metabolic syndrome. MATERIALS AND METHODS The rats on regular or 60% fructose-enriched diets for 6 weeks were further divided into rats combined with or without piroxicam (a selective COX1 inhibitor) or celecoxib (a selective COX2 inhibitor) treatment for an additional 2 weeks. Euglycaemic hyperinsulinaemic clamp (EHC) with a tracer dilution method was performed at the end of the study. RESULTS The present result showed that fructose-induced increases in systolic blood pressure and fasting plasma insulin levels were significantly suppressed in rats treated with celecoxib but not piroxicam. In the EHC period, celecoxib significantly reversed fructose-induced decreases in whole body glucose uptake, mainly by glucose storage. Hepatic glucose production and whole body glycolysis were not significantly changed among groups. Celecoxib but not piroxicam significantly reversed fructose-induced decreases in glycogen synthase activities in red and white quadriceps muscles and insulin-stimulated membrane GLUT4 recruitment in soleus muscles. Celecoxib and piroxicam both significantly diminished fructose-induced increases in plasma thromboxane B2 and 6-keto prostaglandin (PG) F1alpha; but only celecoxib treatment significantly attenuated a fructose-induced increase in 8-isoprostane levels. Plasma PGE metabolites were not different among groups. CONCLUSIONS This study demonstrates that a therapeutic dose of celecoxib, but not piroxicam, could significantly attenuate fructose-induced whole body and muscular insulin resistance in rats.
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Affiliation(s)
- P-S Hsieh
- Department of Physiology & Biophysics, National Defence Medical Centre, Taipei, Taiwan.
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Impact of a long-term sildenafil treatment on pressor response in conscious rats with insulin resistance and hypertriglyceridemia. Am J Hypertens 2008; 21:1258-63. [PMID: 18787522 DOI: 10.1038/ajh.2008.273] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Insulin resistance constitutes a risk factor for endothelial dysfunction and subsequent cardiovascular diseases including hypertension. Daily treatment with phosphodiesterase type 5 (PDE5) inhibitors has beneficial effects on endothelial function in men with increased cardiovascular risk. Endothelium-dependent vasomotor function is ultimately linked to blood pressure (BP) regulation. We postulated that sildenafil would ameliorate BP and biological markers of endothelial function in fructose-fed rats (FFRs). METHODS Wistar rats were fed a standard chow or a 60% fructose-enriched diet containing 12% fat for 8 weeks (FFR). From week 6 through 8, sildenafil (twice a day subcutaneously, 20 mg/kg) was administered followed by a 1-week washout period. At the end of the washout period, BP was recorded using radiotelemetry following cumulative infusion of norepinephrine (from 50 to 400 ng/kg/min). RESULTS FFR displayed both an impaired glucose tolerance and elevated triglyceridemia. The latter was corrected by sildenafil treatment. Resting BP was similar in all rats, whereas pressor responses were significantly enhanced in FFR (maximal increase in mean BP to norepinephrine: 25.6 +/- 3.8 vs. 40.8 +/- 4.0 mm Hg, P < 0.05) and normalized by sildenafil treatment (24.9 +/- 5.3 mm Hg, not significant vs. control). Urinary levels of 8-isoprostanes and thromboxane B(2) were increased in FFR and corrected by sildenafil treatment. CONCLUSION Thus, chronic treatment with sildenafil normalized BP regulation in an experimental model of insulin resistance and hypertriglyceridemia while restoring normal excretion of urinary biological markers of oxidative stress and cyclooxygenase-derived vasoconstrictors. The modulation of ROS and cyclooxygenase-derived vasoconstrictors generation by a chronic treatment with sildenafil may represent an added benefit beyond PDE5 inhibition.
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Dehydroepiandrosterone (DHEA) prevents the prostanoid imbalance in mesenteric bed of fructose-induced hypertensive rats. Eur J Nutr 2008; 47:349-56. [DOI: 10.1007/s00394-008-0734-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Accepted: 07/31/2008] [Indexed: 12/12/2022]
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Matsumoto T, Noguchi E, Ishida K, Kobayashi T, Yamada N, Kamata K. Metformin normalizes endothelial function by suppressing vasoconstrictor prostanoids in mesenteric arteries from OLETF rats, a model of type 2 diabetes. Am J Physiol Heart Circ Physiol 2008; 295:H1165-H1176. [PMID: 18641273 DOI: 10.1152/ajpheart.00486.2008] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We previously reported that in mesenteric arteries from aged Otsuka Long-Evans Tokushima fatty (OLETF) rats (a type 2 diabetes model) endothelium-derived hyperpolarizing factor (EDHF)-type relaxation is impaired while endothelium-derived contracting factor (EDCF)-mediated contraction is enhanced (Matsumoto T, Kakami M, Noguchi E, Kobayashi T, Kamata K. Am J Physiol Heart Circ Physiol 293: H1480-H1490, 2007). Here we investigated whether acute and/or chronic treatment with metformin might improve this imbalance between the effects of the above endothelium-derived factors in mesenteric arteries isolated from OLETF rats. In acute studies on OLETF mesenteric arteries, ACh-induced relaxation was impaired and the relaxation became weaker at high ACh concentrations. Both metformin and 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside [AICAR, an AMP-activated protein kinase (AMPK) activator that is also activated by metformin] 1) diminished the tendency for the relaxation to reverse at high ACh concentrations and 2) suppressed both ACh-induced EDCF-mediated contraction and ACh-stimulated production of prostanoids (thromboxane A2 and PGE2). In studies on OLETF arteries from chronically treated animals, metformin treatment (300 mg.kg(-1).day(-1) for 4 wk) 1) improved ACh-induced nitric oxide- or EDHF-mediated relaxation and cyclooxygenase (COX)-mediated contraction, 2) reduced EDCF-mediated contraction, 3) suppressed production of prostanoids, and 4) reduced superoxide generation. Metformin did not alter the protein expressions of endothelial nitric oxide synthase (eNOS), phospho-eNOS (Ser1177), or COX-1, but it increased COX-2 protein. These results suggest that metformin improves endothelial functions in OLETF mesenteric arteries by suppressing vasoconstrictor prostanoids and by reducing oxidative stress. Our data suggest that within the timescale studied here, metformin improves endothelial function through this direct mechanism, rather than by improving metabolic abnormalities.
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Affiliation(s)
- Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Tokyo 142-8501, Japan
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Xue W, Zhang M, Li J, Wu D, Niu L, Liang Y. Effects of Taurine on Aortic Rings Isolated from Fructose-fed Insulin Resistance Sprague–Dawley Rat are Changed. Cardiovasc Drugs Ther 2008; 22:461-8. [DOI: 10.1007/s10557-008-6124-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Accepted: 06/17/2008] [Indexed: 10/21/2022]
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Sellers MM, Stallone JN. Sympathy for the devil: the role of thromboxane in the regulation of vascular tone and blood pressure. Am J Physiol Heart Circ Physiol 2008; 294:H1978-86. [PMID: 18310512 DOI: 10.1152/ajpheart.01318.2007] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Historically, the vasodilatory prostanoids, especially prostacyclin and prostaglandin E(2), are believed to contribute significantly to the regulation of normal vascular tone and blood pressure (BP), primarily by counteracting the prevailing effects of the systemic vasoconstrictor systems, including angiotensin II, the catecholamines, and vasopressin. In contrast, the primary vasoconstrictor prostanoid thromboxane A(2) (TxA(2)) is produced in far smaller quantities in the normal state. While TxA(2) is believed to play a significant role in a variety of cardiovascular diseases, such as myocardial infarction, cerebral vasospasm, hypertension, preeclampsia, and various thrombotic disorders, its role in the regulation of vascular tone and BP in the normal physiological state is, at best, uncertain. Numerous studies have firmly established the dogma that TxA(2), while important in pathophysiological states in males, plays little or no role in the regulation of vascular tone or BP in females, except in the pulmonary vasculature. However, this concept is largely based on the predominant and preferential use of males in animal and human studies. Recent studies from our laboratory and others challenge this dogma and reveal that the TxA(2) pathway in the systemic vascular wall is an estrogen-dependent mechanism that appears to play an important role in the regulation of vascular tone and BP in females, in both normal and pathophysiological states. It is proposed that the potent vasoconstrictor action of TxA(2) is beneficial in the female in the normal state by acting as a local counterregulatory mechanism to increase vascular tone and BP and defend against hypotension that could result from the multiple estrogen-sensitive local vasodilator mechanisms present in the female vascular wall. Validation of this proposal must await further studies at the systemic, tissue, and molecular levels.
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Affiliation(s)
- Minga M Sellers
- Department of Veterinary Physiology & Pharmacology, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4466, USA
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Puyó AM, Mayer MA, Giorgi S, Gómez AH, Peredo HA. Noradrenaline and angiotensin II modify vascular prostanoid release in fructose-fed hypertensive rats. ACTA ACUST UNITED AC 2008; 27:161-5. [PMID: 18076476 DOI: 10.1111/j.1474-8673.2007.00409.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
1 A fructose-enriched diet induces hypertension, metabolic alterations and insulin resistance in rats, resembling human metabolic syndrome. Previously, we found that prostanoid production was altered in fructose-fed rats. 2 This study analysed the effects of incubation with noradrenaline (NA) and angiotensin II (Ang II) on prostanoid release in mesenteric vascular beds from control and fructose-fed rats. Animals which received fructose solution (10% w/v) for 22 weeks showed higher systolic blood pressure and triglyceridaemia. 3 In controls, NA increased 6-keto-prostaglandin (PG) F(1)alpha (prostacyclin metabolite) and thromboxane (TX) production. Ang II increased only TX release. In fructose-fed animals, NA increased 6-keto-PG F(1)alpha and TX. PGF(2)alpha (vasoconstrictor) was also elevated. Ang II also increased PGF(2)alpha and PGE(2) levels. 4 In conclusion, in fructose rats Ang II in vitro stimulates a vasoconstrictor prostanoid not stimulated in controls. This could be related to the observed in vivo blood pressure increase. In fructose-fed animals, NA and Ang II also augment vasodilator prostanoids, suggesting a compensatory mechanism because of long-term hypertension.
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Affiliation(s)
- A M Puyó
- Cátedras de Anatomía Humana (macro y microscópica), Instituto de Morfología J.J. Naón, Unidad de Neurosciencias; and 1a Cátedra de Anatomía, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
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Daily treatment with sildenafil reverses endothelial dysfunction and oxidative stress in an animal model of insulin resistance. Eur Urol 2007; 53:1272-80. [PMID: 18036727 DOI: 10.1016/j.eururo.2007.11.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 11/06/2007] [Indexed: 02/01/2023]
Abstract
OBJECTIVES Patients with insulin resistance exhibit endothelial dysfunction with decreased nitric oxide (NO) production and increased oxidative stress. We postulated that daily sildenafil improved endothelial function in fructose-fed rats. METHODS AND RESULTS Wistar rats were fed a standard or fructose-enriched diet (FFR) for 9 wk. From weeks 6-8, sildenafil was administered twice daily (sc, 20 m g/kg), followed by a 1-wk washout. Concentration-response curves (CRCs) to endothelium-dependent (acetylcholine [Ach] and A23187) and -independent (sodium nitroprusside [SNP]) relaxing agents were performed on isolated precontracted aortas and superior mesenteric arteries (SMAs). Vascular cyclic guanosine monophosphate (cGMP) content, urinary excretion of nitrates/nitrites (NOx) and 8-isoprostanes (IPT), and plasma levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were evaluated. Relaxations to ACh were significantly reduced in aortas and SMAs of FFR. Sildenafil restored ACh-induced relaxations in aortas and provoked a significant leftward shift of the CRC to ACh in SMAs, whereas it did not modify the enhanced relaxations to SNP in FFR. IL-6, TNF-alpha, vascular cGMP, and urinary NOx levels were not modified by the fructose or sildenafil treatment. Urinary IPT levels were significantly elevated in FFR and normalized by sildenafil. CONCLUSIONS Endothelial dysfunction and oxidative stress associated with insulin resistance can be reversed by daily sildenafil, even 1 wk after treatment cessation.
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Jiang J, Tran L, Vasudevan H, Xia Z, Yuen VG, McNeill JH. Endothelin-1 blockade prevents COX2 induction and TXA2 production in the fructose hypertensive rat. Can J Physiol Pharmacol 2007; 85:422-9. [PMID: 17612651 DOI: 10.1139/y06-088] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Feeding rats with a high fructose diet results in insulin resistance and hypertension. Fructose-hypertensive rats (FHR) have increased vascular levels of endothelin-1 (ET-1) and thromboxane (TXA2). We have previously shown that chronic treatment with either the dual endothelin receptor blocker, bosentan, or the thromboxane synthase inhibitor, dazmegrel, prevented fructose-induced increases in blood pressure, suggesting that both ET-1 and TXA2 play important roles in the development of hyperinsulinemia/insulin resistance-associated hypertension. In this study, we investigated the potential interrelationship between ET-1 and TXA2 in the development of fructose-induced hypertension in vivo. Male Wistar rats were fed on a high fructose diet for 9 weeks. Either bosentan or dazmegrel treatment (daily by oral gavage) was initiated 3 weeks after the start of fructose feeding for a total duration of 6 weeks. At the end of drug treatment, blood and aorta were collected from each animal. Plasma thromboxane B2 (TXB2), a stable TXA2 metabolite, increased significantly in FHR and was reduced to control level by both chronic bosentan and dazmegrel treatment. Protein expression of cyclooxygenase 2 (COX2) was elevated significantly in FHR aortas and treatment with bosentan and dazmegrel corrected these changes. These results indicate that the actions of ET-1 in the aorta of FHR may be mediated through COX2-derived TXA2. Bosentan may prevent the development of hypertension in fructose-fed rats through inhibition of COX2 induction and subsequently the reduction in plasma TXA2.
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Affiliation(s)
- Jihong Jiang
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC V6T 1Z3, Canada
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Tiwari S, Riazi S, Ecelbarger CA. Insulin's impact on renal sodium transport and blood pressure in health, obesity, and diabetes. Am J Physiol Renal Physiol 2007; 293:F974-84. [PMID: 17686957 DOI: 10.1152/ajprenal.00149.2007] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Insulin has been shown to have antinatriuretic actions in humans and animal models. Moreover, endogenous hyperinsulinemia and insulin infusion have been correlated to increased blood pressure in some models. In this review, we present the current state of understanding with regard to the regulation of the major renal sodium transporters by insulin in the kidney. Several groups, using primarily cell culture, have demonstrated that insulin can directly increase activity of the epithelial sodium channel, the sodium-phosphate cotransporter, the sodium-hydrogen exchanger type III, and Na-K-ATPase. We and others have demonstrated alterations in the expression at the protein level of many of these same proteins with insulin infusion or in hyperinsulinemic models. We also discuss how this regulation is perturbed in type I and type II diabetes mellitus. Finally, we discuss a potential role for regulation of insulin receptor signaling in the kidney in contributing to sodium balance and blood pressure.
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Affiliation(s)
- Swasti Tiwari
- Division of Endocrinology and Metabolism, Department of Medicine, Georgetown University, Washington, District of Columbia 20007, USA
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Torres IP, Hafidi ME, Zamora-González J, Infante O, Chavira R, Baños G. Modulation of aortic vascular reactivity by sex hormones in a male rat model of metabolic syndrome. Life Sci 2007; 80:2170-2180. [PMID: 17499811 DOI: 10.1016/j.lfs.2007.04.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2006] [Revised: 04/11/2007] [Accepted: 04/12/2007] [Indexed: 11/26/2022]
Abstract
Modulation by sex hormones of aortic reactivity in rats with the metabolic syndrome (MS) was investigated. The following groups of weanling male Wistar rats were used: control rats (C) received regular tap water while MS rats received 30% sucrose in their drinking water; both had rodent chow for 24 weeks. These two groups were further subdivided into the following four groups: intact (Int), castrated (Cas), castrated plus testosterone (T) and castrated plus estradiol (E). Vascular response of thoracic aortic rings to norepinephrine (NE), acetylcholine (ACh), indomethacin (Indo) and nitro-l-arginine-methyl ester (L-NAME) was investigated. Blood pressure (BP) and serum nitrates and nitrites were measured. BP and serum nitrates and nitrites were modified by castration and treatments with either T or E. Vasoconstriction in Int MS and Cas MS+T aortas was larger than in C and Cas C+T, respectively. Vasodilation in Int MS and Cas MS+T was reduced in comparison with C and Cas C+T, Cas MS and Cas MS+E. Indomethacin decreased vasoconstriction in all groups (P<0.002) but Int C and Cas C+T remained significantly smaller than Int MS and Cas MS+T. l-NAME in NE-contracted vessels induced a significant increase in vasoconstriction, except in Cas C+E rats; the responses of Int MS and Cas MS+T were significantly larger than in Int C and Cas C+T. The results suggest endothelial dysfunction in Int MS and Cas MS+T and a protective effect resulting from castration and castration plus E in MS animals, indicating a sex hormone influence.
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Affiliation(s)
- Israel Pérez Torres
- Department of Pathology, Instituto Nacional of Cardiología "Ignacio Chávez." Juan Badiano 1, Sección XVI, Tlalpan, 14080 México DF, México
| | - Mohammed El Hafidi
- Biochemistry, Instituto Nacional of Cardiología "Ignacio Chávez." Juan Badiano 1, Sección XVI, Tlalpan, 14080 México DF, México
| | - José Zamora-González
- Endocrinology, Instituto Nacional of Cardiología "Ignacio Chávez." Juan Badiano 1, Sección XVI, Tlalpan, 14080 México DF, México
| | - Oscar Infante
- Instrumentation, Instituto Nacional of Cardiología "Ignacio Chávez." Juan Badiano 1, Sección XVI, Tlalpan, 14080 México DF, México
| | - Roberto Chavira
- Department of Reproduction Biology, Instituto Nacional de la Nutrición "Salvador Zubirán". Vasco de Quiroga 15. Sección XVI, Tlalpan, 14080 México DF, México
| | - Guadalupe Baños
- Biochemistry, Instituto Nacional of Cardiología "Ignacio Chávez." Juan Badiano 1, Sección XVI, Tlalpan, 14080 México DF, México.
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Arikawa E, Cheung C, Sekirov I, Battell ML, Yuen VG, McNeill JH. Effects of endothelin receptor blockade on hypervasoreactivity in streptozotocin-diabetic rats: vessel-specific involvement of thromboxane A2. Can J Physiol Pharmacol 2007; 84:823-33. [PMID: 17111027 DOI: 10.1139/y06-042] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Increased vasoconstrictor response to norepinephrine (NE) and endothelin (ET)-1 in arteries from diabetic animals is ameliorated by chronic endothelin receptor blockade with bosentan and was absent in endothelium-denuded arteries, suggesting the involvement of ET-1 and an endothelium-derived contracting factor such as thromboxane A2 (TxA2). To examine this possibility, we determined the effects of acute blockade of ET receptors or inhibition of TxA2 synthesis on the vascular function of superior mesenteric arteries (SMA) and renal arteries (RA) isolated from nondiabetic and 11-week streptozotocin (STZ) diabetic rats chronically treated with either bosentan or vehicle. Both in vitro incubation with bosentan and a selective ETA receptor blocker, BQ123, eradicated the increase in NE contractile responses in diabetic SMA. Additionally, in vitro incubation with the thromboxane synthase inhibitor, dazmegrel, abrogated the exaggerated NE and ET-1 contractile responses in diabetic SMA. Conversely, in RA, no significant acute effect of bosentan, BQ123, nor dazmegrel on vascular responses to NE was observed. Dazmegrel incubation attenuated the maximum contractile responses to ET-1 in diabetic RA; however, these responses in diabetic RA remained significantly greater than those of other groups. Diabetic RA but not SMA exhibited an enhanced contractile response to the TxA2 analogue U46619, which was corrected by chronic bosentan treatment. Immunohistochemical analyses in diabetic SMA revealed an increase in ETA receptor level that was normalized by chronic bosentan treatment. These data indicate that an interaction between ET-1 and TxA2 may be involved in mediating the exaggerated vasoconstrictor responses in diabetic arteries. Furthermore, the underlying mechanisms appear to be vessel specific.
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Affiliation(s)
- Emi Arikawa
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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Ghosh S, Rodrigues B, Ren J. Rat Models of Cardiac Insulin Resistance. METHODS IN MOLECULAR MEDICINE™ 2007; 139:113-43. [DOI: 10.1007/978-1-59745-571-8_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Peredo HA, Mayer MA, Rodríguez Fermepín M, Grinspon D, Puyó AM. Oral treatment and in vitro incubation with fructose modify vascular prostanoid production in the rat. ACTA ACUST UNITED AC 2006; 26:15-20. [PMID: 16371062 DOI: 10.1111/j.1474-8673.2005.00354.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
1.-- In the rat, a fructose-enriched diet induces hyperglycaemia, hypertriglyceridaemia, insulin resistance and hypertension; a model which resembles the human metabolic syndrome. 2.-- Prostanoids, metabolites of arachidonic acid, include vasoactive substances synthesized and released from the vascular wall that have been implicated in the increase of peripheral resistance, one of the mechanisms involved in the fructose-induced hypertension. 3.-- The aim of the present study was to: (i) analyse the effects of the in vitro incubation with fructose on the production and release of prostanoids in rat thoracic aorta and in rat mesenteric bed and (ii) compare the effects of incubation with those of the in vivo acute and chronic treatment of rats with fructose and with the combination of both in vivo and in vitro procedures. 4.-- Blood pressure, glycaemia and triglyceridaemia were significantly elevated in both 4- and 22-week fructose-treated groups. Meanwhile, body and heart weight as well as insulinaemia were similar between experimental animals and controls. 5.-- In aortae, 4 weeks of Fructose treatment did not modify the prostanoid pattern release, but in vitro incubation decreased prostacyclin (PGI(2)) production. However, after 22 weeks, fructose treatment and incubation exerted the same effect. 6.-- In mesenteric bed, after 4 weeks, the incubation and the combination of both procedures reduced the release of the vasodilators PGI(2) and PGE(2), while fructose treatment only diminished the PGE(2) release. On the contrary, the production of the vasoconstrictor thromboxane A(2) (TXA(2)) was enhanced by incubation and both the procedures. After 22 weeks, fructose treatment increased PGI(2) release, while it was reduced by incubation. The combination of both did not modify this peripheral resistance when compared with controls. Finally, incubation of tissues from treated rats increased the release of the vasoconstrictors, PGF(2alpha) and TXA(2). 7.-- In conclusion, the mesenteric bed, a resistance vascular bed, seems to be more sensitive than the aorta, a conductance vessel, to the effects of fructose on prostanoid production. This difference could be related to a more relevant role of resistance vessels in the regulation of peripheral resistance and consequently of blood pressure. The observed effects should contribute to a shift in the balance of the release of prostanoid in favour of vasoconstrictor metabolites. This phenomenon could be related to an increase in the peripheral resistance and the mild hypertension observed in the fructose-treated rats.
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Affiliation(s)
- H A Peredo
- Cátedras de Farmacotecnia I, Universidad de Buenos Aires, Junín 956, 1113 Buenos Aires and CONICET, República Argentina
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Vasudevan H, Nagareddy PR, McNeill JH. Gonadectomy prevents endothelial dysfunction in fructose-fed male rats, a factor contributing to the development of hypertension. Am J Physiol Heart Circ Physiol 2006; 291:H3058-64. [PMID: 16815981 DOI: 10.1152/ajpheart.00598.2005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulin resistance has been shown to be associated with increased blood pressure (BP). The sex hormones estrogen and testosterone have opposing effects in the development of increased BP. Since testosterone has been implicated in increased BP following insulin resistance, we have tried to dissect out the effects of insulin resistance on endothelium-dependent vasorelaxation in the presence and absence of testosterone. Both gonadectomized and sham-operated male Wistar rats fed with a high-fructose diet developed insulin resistance, but BP increased only in the sham-operated rats. Reintroduction of testosterone in vivo restored the increase in BP, thereby abolishing the protective effects of gonadectomy. Fructose feeding did not affect plasma testosterone levels. Insulin resistance induced endothelial dysfunction in the mesenteric arteries of sham-operated rats, which was prevented by gonadectomy, thus suggesting a key role for testosterone in the pathogenesis of secondary vascular complications. Subsequent to blocking the actions of endothelium-dependent hyperpolarizing factor (EDHF), relaxation to acetylcholine (ACh) was lower in sham-operated fructose-fed rats compared with other groups, suggesting the involvement of nitric oxide (NO) in vasorelaxation. Inhibition of NO synthesis nearly abolished the ACh-evoked relaxation in both fructose-fed groups, thus suggesting a testosterone-independent impairment of EDHF-mediated relaxation. The improvement in endothelial function following gonadectomy could be ascribed to a NO component, although plasma nitrite and nitrate levels were unchanged. In summary, testosterone is essential in vivo for the development of endothelial dysfunction and hypertension secondary to insulin resistance, suggesting a facilitatory role for testosterone in increasing BP in fructose-fed male rats.
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Affiliation(s)
- Harish Vasudevan
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, V6T 1Z3 Canada
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Wada K, Yatsuya H, Tamakoshi K, Otsukai R, Fujii C, Matsushita K, Sugiura K, Toyoshima H. A Positive Association between Leptin and Blood Pressure of Normal Range in Japanese Men. Hypertens Res 2006; 29:485-92. [PMID: 17044660 DOI: 10.1291/hypres.29.485] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The results of previous studies on the relationship between leptin and blood pressure are discordant. We investigated to what extent the serum leptin level was related to blood pressure independent of the degree of insulin resistance. The subjects were 1916 men aged 34-69 years whose mean body mass index (BMI) was 23.0 kg/m2. Blood pressure was regressed by leptin concentrations with adjustments for age, BMI, insulin resistance, triglyceride, high density lipoprotein cholesterol, low density lipoprotein cholesterol, physical activity, drinking habits and smoking status. Leptin was associated with diastolic blood pressure (DBP) (standardized beta: 0.092, p = 0.003), but not with systolic blood pressure (SBP) (standardized beta: 0.035, p = 0.25), although insulin resistance was positively associated with both SBP and DBP (standardized beta: 0.175 for SBP, p < 0.001 and 0.114 for DBP, p < 0.001) among all subjects. After subjects were divided into those with normal blood pressure (SBP <130 mmHg and DBP <85 mmHg) and those with higher blood pressure, leptin was positively and significantly associated with DBP (standardized beta: 0.106, p = 0.012) independent of the degree of insulin resistance, but not with SBP (standardized beta: 0.064, p = 0.13) among subjects in the normal blood pressure range. Among the subjects with higher blood pressure, however, neither the association of leptin with SBP nor that of leptin with DBP was statistically significant. These findings suggest that leptin may maintain and increase arterial tone, resulting in the elevation of DBP only within normal blood pressure range. It is also likely that leptin is a physiological mediator--or at least a marker--of some degree of DBP elevation in obesity.
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Affiliation(s)
- Keiko Wada
- Department of Public Health/Health Information Dynamic, Nagoya University Graduate School of Medicine, Nagoya, Japan
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D'Angelo G, Elmarakby AA, Pollock DM, Stepp DW. Fructose feeding increases insulin resistance but not blood pressure in Sprague-Dawley rats. Hypertension 2005; 46:806-11. [PMID: 16157789 DOI: 10.1161/01.hyp.0000182697.39687.34] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Fructose feeding has been widely reported to cause hypertension in rats, as assessed indirectly by tail cuff plethysmography. Because there are potentially significant drawbacks associated with plethysmography, we determined whether blood pressure changes could be detected by long-term monitoring with telemetry in age-matched male Sprague-Dawley rats fed either a normal or high-fructose diet for 8 weeks. Fasting plasma glucose (171+/-10 versus 120+/-10 mg/dL), plasma insulin (1.8+/-0.5 versus 0.7+/-0.1 microg/L), and plasma triglycerides (39+/-2 versus 30+/-2 mg/dL) were modestly but significantly elevated in fructose-fed animals. Using the hyperinsulinemic euglycemic clamp technique, the rate of glucose infusion necessary to maintain equivalent plasma glucose was significantly reduced in fructose-fed compared with control animals (22.9+/-3.6 versus 41.5+/-2.9 mg/kg per minute; P<0.05). However, mean arterial pressure (24-hour) did not change in the fructose-fed animals over the 8-week period (111+/-1 versus 114+/-2 mm Hg; week 0 versus 8), nor was it different from that in control animals (109+/-2 mm Hg). Conversely, systolic blood pressure measured by tail cuff plethysmography at the end of the 8-week period was significantly greater in fructose-fed versus control animals (162+/-5 versus 139+/-1 mm Hg; P<0.001). Together, these data demonstrate that long-term fructose feeding induces mild insulin resistance but does not elevate blood pressure. We propose that previous reports of fructose-induced hypertension reflect a heightened stress response by fructose-fed rats associated with restraint and tail cuff inflation.
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Affiliation(s)
- Gerard D'Angelo
- Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912-2500, USA
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45
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Vasudevan H, Xiang H, McNeill JH. Differential regulation of insulin resistance and hypertension by sex hormones in fructose-fed male rats. Am J Physiol Heart Circ Physiol 2005; 289:H1335-42. [PMID: 15951347 DOI: 10.1152/ajpheart.00399.2005] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Differences in gender are in part responsible for the development of insulin resistance (IR) and associated hypertension. Currently, it is unclear whether these differences are dictated by gender itself or by the relative changes in plasma estrogen and/or testosterone. We investigated the interrelationships between testosterone and estrogen in the progression of IR and hypertension in vivo in intact and gonadectomized fructose-fed male rats. Treatment with estrogen significantly reduced the testosterone levels in both normal chow-fed and fructose-fed rats. Interestingly, fructose feeding induced a relative increase in estradiol levels, which did not affect IR in both intact and gonadectomized fructose-fed rats. However, increasing the estrogen levels improved insulin sensitivity in both intact and gonadectomized fructose-fed rats. In intact males, fructose feeding increased the blood pressure (140 +/- 2 mmHg), which was prevented by estrogen treatment. However, the blood pressure in the fructose-fed estrogen rats (125 +/- 1 mmHg) was significantly higher than that of normal chow-fed (113 +/- 1 mmHg) and fructose-fed gonadectomized rats. Estrogen treatment did not affect the blood pressure in gonadectomized fructose-fed rats (105 +/- 2 mmHg). These data suggest the existence of a threshold value for estrogen below which insulin sensitivity is unaffected. The development of hypertension in this model is dictated solely by the presence or absence of testosterone. In summary, the development of IR and hypertension is governed not by gender per se but by the interactions of specific sex hormones such as estrogen and testosterone.
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Affiliation(s)
- Harish Vasudevan
- Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, V6T 1Z3, Canada
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46
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Fike CD, Zhang Y, Kaplowitz MR. Thromboxane inhibition reduces an early stage of chronic hypoxia-induced pulmonary hypertension in piglets. J Appl Physiol (1985) 2005; 99:670-6. [PMID: 15802364 DOI: 10.1152/japplphysiol.01337.2004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The pulmonary vasoconstrictor, thromboxane, may contribute to the development of pulmonary hypertension. Our objective was to determine whether a combined thromboxane synthase inhibitor-receptor antagonist, terbogrel, prevents pulmonary hypertension and the development of aberrant pulmonary arterial responses in newborn piglets exposed to 3 days of hypoxia. Piglets were maintained in room air (control) or 11% O(2) (hypoxic) for 3 days. Some hypoxic piglets received terbogrel (10 mg/kg po bid). Pulmonary arterial pressure, pulmonary wedge pressure, and cardiac output were measured in anesthetized animals. A cannulated artery technique was used to measure responses to acetylcholine. Pulmonary vascular resistance for terbogrel-treated hypoxic piglets was almost one-half the value of untreated hypoxic piglets but remained greater than values for control piglets. Dilation to acetylcholine in preconstricted pulmonary arteries was greater for terbogrel-treated hypoxic than for untreated hypoxic piglets, but it was less for pulmonary arteries from both groups of hypoxic piglets than for control piglets. Terbogrel may ameliorate pulmonary artery dysfunction and attenuate the development of chronic hypoxia-induced pulmonary hypertension in newborns.
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Affiliation(s)
- Candice D Fike
- Dept. of Pediatrics, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157, USA.
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Abstract
Hypertension is a global health problem, affecting developing and developed countries alike. Most patients with hypertension are undiagnosed, and most diagnosed patients are either untreated or inadequately treated. Randomised controlled trial evidence suggests diuretic therapy for hypertension is as effective as newer drugs in reducing cardiovascular events. There is good evidence for the use of specific classes of drugs in hypertensive patients with a variety of associated clinical conditions, but for uncomplicated cases, the current emphasis in hypertension management is on blood pressure lowering rather than drug class. Individual patients vary in their responses to different drug classes, and optimal therapy for the individual is determined by trial and error. Pharmacogenomics may assist in tailoring therapy for individuals in the future. Emerging drugs include newer members of classes already established in clinical practice, for example, angiotensin II receptor antagonists, aldosterone receptor antagonists, calcium antagonists and centrally acting drugs; newer fixed-dose combination therapies; and more novel therapies, for example, endothelin (ET) receptor antagonists, activators of nitric oxide (NO)-sensitive guanylyl cyclase and vasopeptidase inhibitors.
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Affiliation(s)
- J A Whitworth
- John Curtin School of Medical Research, Australian National University, Canberra, ACT 0200, Australia.
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Puyó AM, Mayer MA, Cavallero S, Donoso AS, Peredo HA. Fructose overload modifies vascular morphology and prostaglandin production in rats. ACTA ACUST UNITED AC 2005; 24:29-35. [PMID: 15458541 DOI: 10.1111/j.1474-8673.2004.00313.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
1. A fructose (Fru)-enriched diet induces a mild increase in blood pressure associated with hyperglycaemia, hypertriglyceridaemia, and insulin resistance, resembling the human 'syndrome X', being an useful model to study hypertension and type 2 diabetes. 2. A sustained elevation of blood pressure is associated with cardiovascular structural modifications such as left ventricular hypertrophy and increased wall thickness:lumen diameter ratio in blood vessels. 3. Prostanoids (PR), metabolites of arachidonic acid through the cyclooxygenase pathway, include vasoactive substances synthesized and released by the vessel walls. 4. The aim of the present study was to analyse, in Fru-treated rats: (i) the morphology of mesenteric vessels and; (ii) the PR production in aorta and mesenteric vessels, in order to assess whether these parameters are related with the haemodynamic alterations observed in this experimental model. 5. Blood pressure, glycaemia and triglyceridaemia, were significantly elevated in both (4 and 22 weeks) Fru-treated groups. Meanwhile body and heart weight as well as insulinaemia were similar between experimental animals and controls. 6. The mesenteric vessels of Fru-treated rats (22 weeks) showed an increased thickness and area of the media when compared with the controls; meanwhile, the lumen diameter was similar in both groups. 7. The Fru treatment for 4 weeks did not modify PR production in aorta, whereas in the mesenteric bed it diminished prostaglandin (PG) E(2) release significantly compared with the controls. However, in the group treated for 22 weeks, Fru reduced PGI(2) production in the aorta, as assessed by 6-keto-PGF(1)alpha measurements. Meanwhile, in the mesenteric bed, the chronic Fru treatment decreased PGE(2) release but, rather surprisingly, increased the output of PGI(2) when compared with its corresponding controls. 8. In conclusion, the present study shows the existence of an alteration in the morphology of mesenteric vessels in Fru-treated rats, which could be related to an increase in peripheral resistance and the consequent mild hypertension observed in this model. However, a diminished release of vasodilator PRs, such as PGE(2) in mesenteric vessels at 4 and 22 weeks and PGI(2) in aorta at 22 weeks could further impair the vessel response. The increase in PGI(2) observed in the chronic group in mesenteric vessels could be attributed to a compensatory mechanism.
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Affiliation(s)
- A M Puyó
- Cátedras de Anatomía Humana Macro y Microscópica, Buenos Aires, Argentina
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Kawada N, Dennehy K, Solis G, Modlinger P, Hamel R, Kawada JT, Aslam S, Moriyama T, Imai E, Welch WJ, Wilcox CS. TP receptors regulate renal hemodynamics during angiotensin II slow pressor response. Am J Physiol Renal Physiol 2004; 287:F753-9. [PMID: 15213069 DOI: 10.1152/ajprenal.00423.2003] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the hypothesis that thromboxane A2(TxA2)-prostaglandin H2receptors (TP-Rs) mediate the hemodynamic responses and increase in reactive oxygen species (ROS) to ANG II (400 ng·kg−1·min−1sc for 14 days) using TP-R knockout (TP −/−) and wild-type (+/+) mice. TP −/− had normal basal mean arterial blood pressure (MAP) and glomerular filtration rate but reduced renal blood flow and increased filtration fraction (FF) and renal vascular resistance (RVR) and markers of ROS (thiobarbituric acid-reactive substances and 8-isoprostane PGF2α) and nitric oxide (NOx). Infusion of ANG II into TP +/+ increased ROS and thromboxane B2(TxB2) and increased RVR and FF. ANG II infusion into TP −/− mice reduced ANG I and increased aldosterone but caused a blunted increase in MAP (TP −/−: +6 ± 2 vs. TP +/+: +15 ± 3 mmHg) and failed to increase FF, ROS, or TxB2but increased NOx and paradoxically decreased RVR (−2.1 ± 1.7 vs. +2.6 ± 0.8 mmHg·ml−1·min−1·g−1). Blockade of AT1receptor of TP −/− mice infused with ANG II reduced MAP (−8 mmHg) and aldosterone but did not change the RVR or ROS. In conclusion, during an ANG II slow pressor response, AT1receptors activate TP-Rs that generate ROS and prostaglandins but inhibit NO. TP-Rs mediate all of the increase in RVR and FF, part of the increase in MAP, but are not implicated in the suppression of ANG I or increase in aldosterone. TP −/− mice have a basal increase in RVR and FF associated with ROS.
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Affiliation(s)
- Noritaka Kawada
- Cardiovascular Kidney Institute and Division of Nephrology and Hypertension, Georgetown University, Washington, DC 20007, USA
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Thirunavukkarasu V, Anitha Nandhini AT, Anuradha CV. Lipoic acid attenuates hypertension and improves insulin sensitivity, kallikrein activity and nitrite levels in high fructose-fed rats. J Comp Physiol B 2004; 174:587-92. [PMID: 15565449 DOI: 10.1007/s00360-004-0447-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2004] [Indexed: 11/24/2022]
Abstract
Chronic feeding of fructose to normal rats causes impaired glucose tolerance, loss of tissue sensitivity to insulin, hyperinsulinemia and hypertension. alpha-Lipoic acid (LA), a co-enzyme known for its potent antioxidant effects, stimulates insulin-mediated glucose uptake in clinical and experimental diabetes. The purpose of this study was to examine whether LA can mitigate fructose-induced insulin resistance and associated abnormalities. Male Wistar rats of body weights 150-170 g were divided into 4 groups containing 12 rats each. Control rats received a control diet containing starch and water ad libitum. Fructose rats received a fructose-enriched diet (>60% of total calories). Fructose + LA rats received a fructose diet and LA (35 mg/kg b.w.) intraperitoneally. Control + LA rats received a normal diet and LA (35 mg/kg b.w.) intraperitoneally. After the treatment period of 20 days, blood pressure (BP) was measured. Oral glucose-tolerance test, insulin-sensitivity index, urea and creatinine clearance tests, and plasma and urinary sodium and potassium levels were analysed. Kallikrein activity and nitrite content were assayed. Additionally, the activities of RBC-membrane Na(+)/K(+) ATPase and Ca(2+) ATPase enzymes were assayed. Fructose rats showed increased BP, decreased glucose tolerance, decreased insulin sensitivity and altered sodium and potassium levels and renal clearance. LA supplementation mitigated these alterations. The increase in BP was attenuated and the levels of biochemical parameters were brought close to normal. The BP-lowering effect of LA in fructose rats may be related to improvement in insulin sensitivity.
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Affiliation(s)
- V Thirunavukkarasu
- Department of Biochemistry, Faculty of Science, Annamalai University, 608002 Annamalai Nagar, Tamil Nadu, India
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