Fengyang Huang

DNA methylation of leptin and adiponectin promoters in children is reduced by the combined presence of obesity and insulin resistance

Objective:Epigenetic alterations have been suggested to be associated with obesity and related metabolic disorders. Here we examined the correlation between obesity and insulin resistance with the methylation frequency of the leptin (LEP) and adiponectin (ADIPOQ) promoters in obese adolescents with the aim to identify epigenetic markers that might be used as tools to predict and follow up the physiological alterations associated with the development of the metabolic syndrome.Subjects:One hundred and six adolescents were recruited and classified according to body mass index and homeostasis model of assessment-insulin resistance index. The circulating concentrations of leptin, adiponectin and of several metabolic markers of obesity and insulin resistance were determined by standard methods. The methylation frequency of the LEP and ADIPOQ promoters was determined by methylation-specific PCR (MS-PCR) in DNA obtained from peripheral blood samples.Results:Obese adolescents without insulin resistance showed higher and lower circulating levels of, respectively, leptin and adiponectin along with increased plasmatic concentrations of insulin and triglycerides. They also exhibited the same methylation frequency than lean subjects of the CpG sites located at −51 and −31 nt relative to the transcription start site of the LEP gene. However, the methylation frequency of these nucleotides dropped markedly in obese adolescents with insulin resistance. We found the same inverse relationship between the combined presence of obesity and insulin resistance and the methylation frequency of the CpG site located at −283 nt relative to the start site of the ADIPOQ promoter.Conclusions:These observations sustain the hypothesis that epigenetic modifications might underpin the development of obesity and related metabolic disorders. They also validate the use of blood leukocytes and MS-PCR as a reliable and affordable methodology for the identification of epigenetic modifications that could be used as molecular markers to predict and follow up the physiological changes associated with obesity and insulin resistance.

Effect of losartan on vascular function in fructose-fed rats: the role of perivascular adipose tissue.

Recent studies have shown the effect of perivascular adipose tissue (PVAT) on the regulation of vascular function; however, its role in the model of metabolic syndrome remains unclear. The aim of this study was to examine the effect of losartan on PVAT-derived vascular dysfunction in fructose-induced hypertensive rats. Rats were fed with either water, 10% fructose, or 10% fructose with 10mg/kg losartan for 8 weeks. In the isolated aorta with PVAT and endothelium, contraction induced by norepinephrine (NE) was more potent in fructose-fed rats compared to control rats. Losartan normalized blood pressure, insulin resistance, and NE-induced vasoconstriction in fructose-fed rats. In the aortic rings with/without endothelium and with/without PVAT, losartan could not improve the acetylcholine-induced relaxation in fructose-fed rats. The observation suggested that losartan partly improved the PVAT-associated vascular regulation in fructose-induced hypertensive rats.

Endothelial activation and systemic inflammation in obese asthmatic children.

Asthma and obesity are prevalent disorders, each with a significant impact on the public health. The causality relating obesity and asthma has not been established. The objective of this article is to investigate whether asthma could exacerbate the endothelial activation and to determine the relationship between systemic inflammation and endothelial activation in obese asthmatic children. Eighty-nine children (10-16 years old) were divided according to their diagnosis (asthma, obese nonasthmatic, and obese asthmatic children). Twenty healthy children formed the control group. Three adhesion molecules (E-selectin, sICAM-1, and sVCAM-1) and C-reactive protein (CRP) were measured in serum samples. The levels of sICAM-1 were significantly higher in obese nonasthmatic and obese asthmatic children versus control and lean asthmatic children (414.7+/-154.7, 434.9+/-181.1, 238.6+/-117.8, and 351.2+/-153.5 ng/mL, respectively). No difference was observed between obese nonasthmatic and obese asthmatic groups. No difference of the levels of CRP, E-selectin, and sVCAM-1 was found among the study groups. Correlation analysis showed that E-selectin associated significantly with body mass index (BMI), CRP and the other two adhesion molecules. CRP depended on BMI. sICAM-1 associated with CRP, BMI, and triglycerides. Correlations were verified in multiple regression analysis models in the whole study groups: CRP levels depended on sICAM-1, E-selectin, and sICAM-1 concentrations depended on BMI. Correlations were verified in asthmatic subjects: CRP depended on sICAM-1. These results confirmed the endothelial activation in obese children. Mild nonallergic asthma in our study did not exacerbate the endothelial activation in obese or lean asthmatic children. Significant association between systemic inflammation and endothelial activation was observed in asthmatic children.

Weight loss induced by 6‐month lifestyle intervention improves early endothelial activation and fibrinolysis in obese adolescents

BACKGROUND Adolescent obesity is associated with an increased risk of adult obesity and subsequent cardiovascular diseases. The present study aimed to assess the effect of weight loss after 6-month lifestyle intervention in obese adolescents on biomarkers of endothelial activation and fibrinolytic system. METHODS Eighty-five obese adolescents aged 10 to 16 years were assigned to a 6-month lifestyle intervention and 61 completed the programme. We examined the effect of the intervention on adhesion molecules (selectin E, soluble intercellular adhesion molecule 1 and soluble vascular adhesion molecule 1) and fibrinolytic parameters [plasminogen activator inhibitor-1 (PAI-1) and fibrinogen]. Thirty-six lean adolescents were studied only at baseline as a comparison group. RESULTS Compared with lean participants, obese adolescents at baseline demonstrated significantly higher levels of triglycerides, glucose, insulin, homeostasis model assessment, soluble intercellular adhesion molecule 1, PAI-1 and fibrinogen. After 6-month lifestyle intervention, those obese adolescents with decreased standard deviation score-body mass index (SDS-BMI) displayed significant decreases in insulin (19.2 ± 11.2 vs. 26.8 ± 13.2 mU/L, P≤ 0.01), homeostasis model assessment (4.24 ± 3.19 vs. 6.58 ± 4.08, P≤ 0.01), selectin E (100.2 ± 60.9 vs. 116.0 ± 69.0 ng/mL, P≤ 0.01) and PAI-1 (39.6 ± 38.0 vs. 51.8 ± 25.6 ng/mL, P≤ 0.05) with respect to the baseline levels. No changes in these parameters were observed in the obese adolescents with stable or increased SDS-BMI. The changes of triglycerides after intervention in subgroup with decreased SDS-BMI were significantly greater than those in subgroup with stable SDS-BMI. CONCLUSIONS The present study demonstrated increased endothelial activation and impairment of the fibrinolytic system in early life, which is in part reversible by a 6-month lifestyle intervention.

Role of central and sympathetic nervous systems in pressor effect of L-NAME.

The pressor effect of Nω-nitric-l-arginine methyl ester (l-NAME) in rats has been attributed to the inhibition of the endothelial nitric oxide synthase; however, recent findings suggest that the central and sympathetic nervous systems may be also involved. In the present work, the authors attempted to study the possible central and sympathetic mechanisms involved in the pressor effect of l-NAME. They compared mean arterial pressure response during 1 h of continuous infusion of normal saline or l-NAME (0.031 mg · kg−1 · min−1) in Wistar rats treated with reserpine, adrenal medullectomy, pithing, and pithing + medullectomy. After 15–20 min infusion, a significantly greater increase of mean arterial pressure was observed in anesthetized rats with l-NAME and l-NAME + medullectomy versus rats with l-NAME + reserpine and l-NAME + pithing, and the magnitude of the difference increased further during the continuous 1-h l-NAME infusion. Adrenal medullectomy totally abolished the pressor effect of l-NAME in pithed group. The present findings suggest that the central and sympathetic nervous systems play important roles in the maintenance of the pressor effect of l-NAME, while the adrenal medulla becomes important only when the sympathetic nervous system has been suppressed.

Plasminogen Activator Inhibitor-1, Fibrinogen, and Lung Function in Adolescents with Asthma and Obesity

Background. Obesity promotes a low-grade systemic inflammatory state that may act on the lung to exacerbate asthma. There is little information on the relationship between systemic inflammation and lung function in children and adolescents. Objectives. To explore the relationship among fibrinogen, plasminogen activator inhibitor-1 (PAI-1), lung function in adolescents with the presence of asthma, and/or obesity. Methods. Totally 178 adolescents (boys and girls) were involved; four groups were divided according to their diagnosis: non-obese and non-asthmatic controls (n = 38), non-obese asthmatics (n = 31), obese non-asthmatics (n = 62), obese asthmatics (n = 47). The levels of PAI-1 and fibrinogen were determined in blood samples. The lung function was evaluated with spirometry by measuring forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and forced expiratory flows between 25 and75% (FEF25–75%). Results. Compared to healthy controls, obese adolescents with or without asthma show higher levels of fibrinogen (289.2 ± 61.5, 328.4 ± 54.9, and 324.9 ± 68.9 mg/dL, respectively), PAI-1 (36.0 ± 17.3, 53.2 ± 22.3, and 52.6 ± 24.7 ng/mL, respectively), and the reduced FEV1/FVC ratio (87.7 ± 7.7, 81.6 ± 8.6, and 81.7 ± 6.9, respectively). In the whole studied subjects, FEV1/FVC ratio shows significant inverse correlation with PAI-1 (r = −0.185), fibrinogen (r = −0.157), body mass index (BMI; r = −0.303), insulin(r = −0.198), and HOMA (r = −0.173). In the 78 asthmatic subjects, FVC correlates positively with BMI. Conclusion. Our data demonstrate that the degree of systemic inflammation and the degree of obesity in the whole studied adolescents groups correlate negatively with lung function, suggesting an obstructive pulmonary pattern. Further studies are needed to identify the pathophysiological mechanism for such association.

Changes in protein and gene expression of angiotensin II receptors (AT1 and AT2) in aorta of diabetic and hypertensive rats.

Abstract Diabetes and hypertension have been associated with cardiovascular diseases and stroke. Some reports have related the coexistence of hypertension and diabetes with increase in the risk of developing vascular complications. Recently some studies have shown results suggesting that in the early stages of diabetes and hypertension exist a reduced functional response to vasopressor agents like angiotensin II (Ang II), which plays an important role in blood pressure regulation mechanism through the activation of its AT1 and AT2 receptors. For that reason, the aim of this work was to study the gene and protein expression of AT1 and AT2 receptors in aorta of diabetic SHR and WKY rats. Diabetes was induced by the administration of streptozotocin (60 mg/kg i.p.). After 4 weeks of the onset of diabetes, the protein expression was obtained by western blot and the mRNA expression by RT-PCR. Our results showed that the hypertensive rats have a higher mRNA and protein expression of AT1 receptors than normotensive rats while the AT2 expression remained unchanged. On the other hand, the combination of diabetes and hypertension increased the mRNA and protein expression of AT1 and AT2 receptors significantly. In conclusion, our results suggest that diabetes with hypertension modifies the mRNA and protein expression of AT1 and AT2 receptors. However, the overexpression of AT2 could be associated with the reduction in the response to Ang II in the early stage of diabetes.

Effect of Early Diabetes on the Expression of Alpha-1 Adrenergic Receptors in Aorta and Carotid Arteries of Wistar Kyoto and Spontaneously Hypertensive Rats

Hypertension and diabetes have been related to noradrenergic system impairment, especially to the response mediated by alpha-1 receptors. The aim of this work was to investigate possible changes in the expression of alpha-1 adrenergic receptors in aorta and carotid arteries of Wistar Kyoto and spontaneously hypertensive rats after 4 weeks of the onset of diabetes. Our results suggest that early diabetes modifies the expression of alpha-1 adrenergic receptors in aorta and carotid arteries of both WKY and SHR strains in a different way.

Increased antidepressant-like effect of desipramine combined with central stimulants (caffeine and amphetamine) in mice

Desipramine is a widely used antidepressive agent that inhibits the reuptake of noradrenaline and serotonin, and central stimulants such as caffeine and amphetamine help to release noradrenaline and serotonin. This work aimed to evaluate whether the combination of these agents could produce a stronger antidepressant-like effect than either of the drugs alone. To this end, male mice were treated with different doses of desipramine, caffeine, amphetamine, desipramine-caffeine and desipramine-amphetamine. The results showed that all drugs produced decreased immobility time in the forced swimming model. The combined treatment of desipramine (0.31, 1.0 or 3.1 mg/kg i.p.) with caffeine or amphetamine (0.31 or 1 mg/kg i.p.) reduced immobility time greater than either of those drugs alone. The combined treatment of desipramine (0.31, 1 and 3.1 mg/kg i.p.) with amphetamine or caffeine (0.1 and 1 mg/kg i.p.) did not increase the motor activity significantly compared to the control. These results also suggested that drugs which promote the release of noradrenaline and serotonin could increase antidepressant-like effect of desipramine.

Effect of Early Diabetes on the Response to Norepinephrine and Dopamine in Pithed Wistar Kyoto and Spontaneously Hypertensive Rats

Diabetes has been related to changes in vascular responses, mainly an increase in the vasoconstrictor responses and a decrease in the vasodilator responses. The literature has now begun to study the effects of diabetes in the early stages of development; the first studies on these stages indicate that diabetes produces different changes compared to the advanced stages. For that reason, the aim of this work was to evaluate the responses to norepinephrine and dopamine on normotensive and hypertensive rats with 4 weeks of diabetes evolution. The results showed that 4 weeks of diabetes produces a decrease of the vasopressor response to both agents (norepinephrine and dopamine). These results suggest that in the early stages, there are changes that help to decrease the pressor responses and these changes could disappear in the advanced stages.