Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

There is increasing evidence that visceral adipose tissue is a causative risk factor for fatty liver and nonalcoholic steatohepatitis. Adipose tissue-derived secretory proteins are collectively named adipocytokines. Obesity and mainly visceral fat accumulation impair adipocyte function and adipocytokine secretion and the altered release of these proteins contributes to hypertension, impaired fibrinolysis and insulin resistance. This review summarizes recent findings on the role of the adipocytokines adiponectin, leptin and resistin in the context of hepatic insulin resistance, fatty liver and liver fibrosis. Elevated levels of resistin antagonize hepatic insulin action and raise plasma glucose levels. Leptin exerts insulin-sensitizing effects, but obesity has been linked to leptin resistance and low levels of circulating leptin receptor, indicating that high levels of leptin cannot mediate its beneficial effects. Adiponectin improves insulin sensitivity; however, low circulating adiponectin is found in the obese state. Adiponectin is an anti-inflammatory protein, whereas leptin augments inflammation and fibrogenesis. Disturbed adipocytokine secretion might, therefore, promote hepatic steatosis and the development of nonalcoholic steatohepatitis. The beneficial effects of the therapeutic approaches so far tested in the treatment of fatty liver disease and fibrosis might be due to the modulation of these adipocytokines.
 ...
PMID:Mechanisms of disease: adipocytokines and visceral adipose tissue--emerging role in nonalcoholic fatty liver disease. 1626 8

For better understanding the role of each element involved in the physiopathology of obesity and insulin resistance, researchers can use experimental models, which may in controlled manner evaluate the participation of each element on the obesity and insulin resistance and provide information for better understanding the physiopathology and treatment of obesity and insulin resistance. Experimental obesity and insulin resistance can be due to a deficient response to leptin, secondary to hypoleptinemia and/or mutations on leptin receptor, by modifications on insulin receptor, deletion or diminished insulin signal transduction, enhancement of the effects of orexigen peptides and/or diminution of anorexigen peptides actions on hypothalamus, as well as secondary to arterial hypertension, as in the spontaneously hypertension. Obesity and insulin resistance can also be induced by glucocorticoid excess, frutose enriched and cafeteria diet and due to hypothalamus lesions induced by neonatal administration of monossodium glutamate.
 ...
PMID:[Experimental models of insulin resistance and obesity: lessons learned]. 1676 85

Obesity-induced hypertension and essential hypertension in lean patients are two different forms of hypertension. The main goal of this study was to test whether there are differences in biochemical parameters between subjects with obesity-associated hypertension and those with essential hypertension. We examined whether the biochemical responses to angiotensin-converting enzyme inhibitor (ACEI) ramipril therapy reveal properties of these two conditions that might explain the differences in clinical outcome. Before ramipril therapy, the hypertensive group exhibited increases in ACE activity (p<0.05), plasma malondialdehyde (MDA) concentration and the malondialdehyde/nitric oxide end-product ratio (MDA/NO(x)) (p<0.05), and decreases in xanthine oxidase (XO) activity (p<0.05) and plasma nitric oxide end-product (NO(x)) level (p<0.01). Before medication, plasma endothelin-1 (ET-1), plasma leptin, and leptin receptor levels were normal. Following ramipril treatment, ACE activity normalized. Before ACE inhibitor treatment, the obese-hypertensive group exhibited elevated levels of plasma ET-1 (p<0.05), plasma leptin (p<0.01), XO activity (p<0.05), plasma MDA and MDA/NO(x) (p<0.05), and reduced levels of plasma NO(x)(p<0.01) and leptin receptors (p<0.001). Following medication, the plasma NO(x) level, MDA/NO(x), and XO activity returned to normal while ACE activity decreased (p<0.001). In patients with essential hypertension, NO availability and ACE activity, and in those with obesity-associated hypertension, hyperleptinemic effects, NO level, endothelin-1 concentration and XO activity, may be important factors in the pathology.
 ...
PMID:Different pathomechanisms of essential and obesity-associated hypertension in adolescents. 1689 99

Leptin and/or ghrelin, initially thought to be considered messengers of energy metabolism, are now considered to play a role in normal and complicated pregnancy. In this study, pregnant, spontaneously hypertensive rats (SHR) have been used to evaluate, for the first time, the modification of leptin and ghrelin both at serum and tissue levels. In SHR, we evaluate plasma leptin level and tissue protein expression in both placenta and adipose tissue at the end of gestation (day 20) versus normotensive Wistar-Kyoto (WKY) animals. The expression of functional leptin receptor (Ob-Rb) in peripheral tissues and in the hypothalamus was evaluated. Moreover, we measured plasma ghrelin level and its mRNA expression in the stomach and placenta. SHR strain presented significantly lower plasma leptin levels when compared with those found in pregnant or not WKY controls. Interestingly, in the placenta, leptin gene expression was higher in SHR than normotensive WKY. Moreover, we demonstrated a resistance to the effects of leptin via 'downregulation' of hypothalamic receptors in pregnant SHR. Conversely, SHR presented significantly higher ghrelin plasma levels when compared with those found in pregnant or not WKY. However, we observed that ghrelin level in the stomach of SHR did not change during pregnancy, and on the opposite, mRNA ghrelin in the placenta of SHR was lower than that of normotensive rats, suggesting a different production of this hormone in the fetal-placental unit. These data gain further insight into metabolic hormone modifications observed in a model of pre-existing hypertension associated with pregnancy.
 ...
PMID:Maternal adaptations to pregnancy in spontaneously hypertensive rats: leptin and ghrelin evaluation. 1776

Obesity is an increasing health problem not only in the industrialized western countries but, also in the developing countries like India. The adipose tissue specific obese (ob) gene and its peptide product leptin were discovered in 1994. Leptin binding to specific receptors in the hypothalamus results in altered expression of orexigenic and anorexigenic neuropeptides that regulate neuroendocrine functions and energy homeostasis. Recent patents and experimental evidence suggest that leptin plays an important role in the pathogenesis of obesity and eating disorders. Central leptin action also includes regulation of blood pressure, bone mass, and immune function. Peripherally also, leptin plays an important role in direct regulation of immune cells, pancreatic beta cells, adipocytes and muscle cells. Leptin receptors are present on human endothelial cells, and it has been shown to induce angiogenesis both in vitro and in vivo. Further, leptin appears to be a potential pressure and volume regulating factor and may function pathophysiologically as a common link to obesity and hypertension. Obesity is also a risk factor for several other cardiovascular diseases like myocardial hypertrophy, myocardial infarction, coronary atherosclerosis and increased cardiovascular morbidity and mortality. Recent progress in understanding central and peripheral leptin receptor signaling pathways may provide potential new targets to combat obesity, hypertension etc.
 ...
PMID:Leptin and the cardiovascular system: a review. 1822 Nov 8

Chronic stress and increased sympathetic nerve activity have been associated with cardiovascular disorders such as hypertension, myocardial infarction and stroke. The aim of this study was to investigate the role of nerve growth factor (NGF) on the expression of tyrosine hydroxylase (TH), vascular-endothelial growth factor (VEGF) and leptin receptor (OB-R) in brain, adrenal and cardiovascular tissues of adult male and female mice following a chronic stress procedure. It was found that daily restraint for 10 consecutive days alters TH levels in hypothalamic and brainstem areas related to sympathetic activation, in both male and female mice. Chronic stress procedure also modifies heart and aorta VEGF levels in male mice, and adrenal glands TH in female mice. The NGF administration in stressed mice reverted the stress-induced up-regulation of TH levels in male and female mice hypothalamic nuclei and in male locus coeruleus. Administration of NGF in stressed animals also down-regulated OB-R levels in the hypothalamus of both male and female mice and in the female aorta. Our findings indicate that repeated restraint in mice has an effect on TH and VEGF protein content at different brain and peripheral sites involved in the sympathetic and cardio-vascular response to stressful stimuli. NGF administration is able to counteract some of these stress-induced changes. Since NGF is known to be up-regulated during stress, a possible functional significance of our observations is that the circulating NGF released during and following stress may serve to prevent possible deficits and/or damage linked to stress-induced sympathetic and cardiovascular activation.
 ...
PMID:Repeated restraint and nerve growth factor administration in male and female mice: effect on sympathetic and cardiovascular mediators of the stress response. 1828 16

Leptin receptor-deficient db/db mice develop human type 2 diabetes mellitus, hypertension, and obesity with disrupted circadian blood pressure (BP) rhythm. Whether leptin is the sole mechanism mediating autonomic imbalance and hypertension is unclear. To explore this notion further, we measured BP by radiotelemetry combined with fast Fourier transformation and assessed autonomic function pharmacologically before and after renin-angiotensin system blockade with enalapril. The resting period BP (117+/-3 versus 108+/-1.0 mm Hg) and heart rate (HR; 488+/-12 versus 436+/-8 bpm) were higher in db/db mice compared with db/+ mice. BP and HR amplitudes were lower in db/db mice compared with db/+ mice. BP response to trimetaphan (-43+/-5 versus -27+/-3 mm Hg) and HR response to metoprolol (-59+/-12 versus -5+/-4 bpm) were greater in db/db mice than in db/+ mice. The HR response to atropine was blunted in db/db mice (59+/-17 versus 144+/-24 bpm), as were baroreflex sensitivity and HR variability. Enalapril improved autonomic regulation in db/db mice. Stimulation of central alpha-2 adrenoreceptors enhanced both parasympathetic HR control and baroreflex sensitivity in db/db mice. We suggest that functional, rather than structural, alpha-2 adrenoceptor changes and the renin-angiotensin system are involved in the increased sympathetic and decreased parasympathetic tones in db/db mice. Our data suggest that db/db mice exhibit features found in humans with type 2 diabetic autonomic neuropathy and could serve as a model for this complication.
Hypertension 2009 Feb
PMID:Diabetic hypertensive leptin receptor-deficient db/db mice develop cardioregulatory autonomic dysfunction. 1902 83

The hypothalamic arcuate nucleus was initially regarded as the principal site of leptin action, but there is increasing evidence for functional leptin receptors in extrahypothalamic sites, including the nucleus tractus solitarii (NTS). We demonstrated previously that arcuate injection of leptin increases sympathetic nerve activity (SNA) to brown adipose tissue and kidney. In this study, we tested the hypothesis that leptin signaling in the NTS affects sympathetic neural outflow. Using a stereotaxic device in anesthetized rats, we microinjected leptin (0.25 to 1.00 microg) or saline into the NTS while recording SNA to kidney and brown adipose tissue. Microinjection of leptin into the commissural and medial subnuclei of the caudal NTS at the level of the area postrema in Sprague-Dawley rats produced a dose-related increase in renal SNA (+112+/-15% with leptin 1 microg; n=7; P<0.001) but did not increase SNA to brown adipose tissue (-15+/-12%; P value not significant). This effect depended on intact functional leptin receptors, because it was not observed in Zucker obese rats that have a missense mutation in the leptin receptor. Rostral NTS injection of leptin failed to increase SNA, indicating that leptin signaling in the NTS is probably confined to the caudal NTS at the level of the area postrema. In summary, this study demonstrates that leptin signaling in the caudal NTS increases SNA to the kidney but not to the brown adipose tissue. The study strengthens the concept of a distributed brain network of leptin action and demonstrates that these distributed brain sites can mediate contrasting sympathetic responses to leptin.
Hypertension 2009 Feb
PMID:Leptin signaling in the nucleus tractus solitarii increases sympathetic nerve activity to the kidney. 1910 99

Mineralocorticoid receptors (MRs) are expressed in non-epithelial tissues, such as blood vessels, the heart and adipose tissue. The combined effects of aldosterone and insulin link the metabolic syndrome with hypertension and salt sensitivity. Eplerenone is the newly developed inhibitor of MRs that has significantly fewer adverse effects than similar doses of spironolactone. Eplerenone has been reported to have anti-hypertensive and protective effects on cardiovascular and renal injury in salt-sensitive hypertensive animal models, such as the Dahl salt-sensitive (DS) hypertensive rat and leptin receptor-deficient spontaneously hypertensive rat (SHR/cp). Eplerenone also increases nitric oxide bioavailability and improves impaired endothelial function by decreasing oxidative stress. Clinical studies support the concept that eplerenone is effective for the treatment of salt-sensitive hypertension as well as idiopathic hyperaldosteronism and does not have adverse anti-androgenic adverse effects. In Japan, eplerenone has been used clinically since 2007 for the treatment of hypertension, with its price being marginally lower than all types of angiotensin II receptor antagonists. This will inevitably result in an increasing number of hypertensive patients and those with primary aldosteronism being treated with this agent in the near future.
 ...
PMID:Effects of eplerenone, a selective mineralocorticoid receptor antagonist, on clinical and experimental salt-sensitive hypertension. 1930 Apr 47

The aim of the study was to investigate whether diverse clinical blood pressure phenotypes are associated with free leptin surrogates, as reflected by plasma leptin, human soluble leptin receptor, and their ratio (ie, free leptin index) in nonobese normoglycemic subjects. Three separate clinic blood pressure measurements and ambulatory blood pressure monitoring were implemented to divide 494 subjects (aged 44+/-5 years; 272 men; body mass index: <30 kg/m(2)) into hypertensives (n=166), white-coat hypertensives (n=82), masked hypertensives (n=66), and normotensives (n=180). Participants underwent echocardiography, while, from fasting venous blood samples, metabolic profile, plasma leptin, and its receptor levels were assessed. Hypertensives and masked hypertensives demonstrated higher levels of log (10)(leptin) and log (10)(free leptin index), as well as lower levels of log (10)(human soluble leptin receptor) with respect to normotensives. White-coat hypertensives had similar free leptin surrogates compared with normotensives. Younger age, 24-hour systolic and diastolic blood pressures, 24-hour heart rate, and left ventricle mass index were common correlates of free leptin surrogates. After adjustment for confounders, masked hypertensive and hypertensive with respect to normotensive phenotype were associated with log (10)(leptin) with odds ratios (95% CIs) of 1.31 (1.12 to 3.80) and 1.26 (1.09 to 2.24), respectively, log (10)(human soluble leptin receptor) with 0.65 (0.53 to 0.78) and 0.69 (0.57 to 0.84), respectively, and log (10)(free leptin index) with 2.46 (1.32 to 7.23) and 1.84 (1.26 to 3.73), respectively (P<0.05 for all of the cases). Free leptin surrogates are associated with masked hypertension in nonobese normoglycemic subjects. Free leptin is almost equally increased in masked and sustained hypertension, suggesting a similar leptin-related vascular impairment.
Hypertension 2009 Jun
PMID:Free leptin is associated with masked hypertension in nonobese subjects: a cross-sectional study. 1939 60


<< Previous 1 2 3 4 5 6 7 Next >>