Insulin receptor number is reduced in healthy offspring of patients with essential hypertension

BACKGROUND: Epidemiologic studies have shown that healthy offspring of hypertensive patients exhibit many features of the metabolic syndrome, such as hyperinsulinemia, insulin resistance, and lipid disorders. Patients with essential hypertension have reduced numbers of insulin receptors. The aim of this study was to examine whether the number of insulin receptors is reduced in the erythrocytes of healthy offspring of hypertensive patients in comparison to the offspring of healthy normotensive subjects. METHODS: The study population consisted of 25 healthy offspring of patients with essential hypertension (group A) and 28 healthy offspring of healthy normotensive individuals (group B). The two groups were matched for sex, age, and body mass index. Systolic blood pressure (SBP) and diastolic blood pressure (DBP), resting heart rate (HR), plasma insulin levels, and human insulin receptor (hINR) number in erythrocytes were determined in each participant. RESULTS: Mean SBP, DBP, and resting HR were significantly higher in group A than in group B (121 +/- 13 v 110 +/- 10 mm Hg, 78 +/- 6 v 73 +/- 8 mm Hg, and 76 +/- 4 v 72 +/- 6 beats/min; P < .01, P < .05, and P < .01, respectively). Plasma insulin levels were significantly higher, whereas hINR density was significantly lower, in group A than in group B (21 +/- 7 v 15 +/- 6 pIU/mL, P < .01, and 5.6 +/- 1.4 v 6.8 +/- 1.3 receptors x 10(3)/red cell, P < .01, respectively). CONCLUSIONS: Our findings suggest that increased SBP, DBP, HR, plasma insulin levels, and decreased erythrocyte hINR density preexist in healthy offspring of patients with essential hypertension.     

Adiponectin and resistin plasma levels in healthy individuals with prehypertension

Prehypertension seems to be related to increased cardiovascular risk in healthy subjects, while hypoadiponectinemia and hyperresistinemia may contribute to insulin resistance and accelerated atherogenesis. This study investigated whether plasma levels of adiponectin (known to increase insulin sensitivity) and resistin (a protein possibly involved in inflammatory activities) are affected in healthy individuals with prehypertension, and to compare the findings to those of healthy normotensives matched for age, gender, and body mass index. Twenty-six (14 men and 12 women) healthy individuals with prehypertension (mean age, 52+/-5 years; mean body mass index, 23+/-1.5 kg/m2) and 24 healthy normotensives (13 men and 11 women; mean age 53+/-6 years; body mass index 23.2+/-1.4 kg/m2) were studied. The adiponectin and resistin plasma levels were determined by the enzyme-linked immunosorbent assay method. Plasma resistin levels were significantly higher, while adiponectin plasma levels were significantly lower, in prehypertensive subjects compared with normotensive subjects (10.62+/-3.17 ng/mL vs. 6.72+/-3.15 ng/mL and 6.26+/-2.18 mg/mL vs. 12.12+/-4.8 mg/mL; p < 0.01, respectively). The findings suggest that healthy individuals with prehypertension have significantly higher resistin plasma levels and significantly lower adiponectin plasma levels compared with healthy normotensives. These findings may represent another possible mechanism that may increase the cardiovascular risk in this special group of patients, needing further investigation.     

Resistin serum levels are increased but not correlated with insulin resistance in chronic hemodialysis patients

BACKGROUND/AIMS: Insulin resistance is a well-known phenomenon in uremia. Resistin, a recently discovered insulin inhibitor secreted by adipocytes, is associated with obesity and insulin resistance in mice. Adiponectin, also secreted by adipocytes, is known to reduce insulin resistance in humans. The aim of the present study was to address the hypothesis that changes in resistin or adiponectin serum levels may relate to body composition and to insulin resistance in patients with end-stage renal disease. METHODS: In a cross-sectional study, 33 non-diabetic patients (24 males and 9 females, mean age 61.5+/-15.8 years) with end-stage renal disease on chronic hemodialysis (treatment duration 41+/-31 months) that lacked signs of infection were enrolled. The control group consisted of 33, matched for age, sex and body mass index (BMI), healthy volunteers (22 males, 11 females, mean age 62.6+/-12.1 years). BMI (kg/m(2)) was calculated from body weight and height. Body fat (%) was measured by means of bioelectrical impedance. Blood samples were taken always in the morning after a 12-hour fasting period before and after the hemodialysis session. Resistin and adiponectin serum concentrations were measured by enzyme immunoassays and insulin by an electrochemiluminescence immunoassay. The post-treatment values were corrected regarding the hemoconcentration. The homeostasis model assessment index (HOMA-R) was calculated as an estimate of insulin resistance from the fasting glucose and insulin serum levels. RESULTS: Pre-treatment resistin serum levels were significantly increased in hemodialysis patients compared to healthy controls (19.2+/-6.2 vs. 3.9+/-1.8 ng/ml; p<0.001). Hemodialysis did not alter resistin levels, as pre- and post-treatment levels were not different when corrected for hemoconcentration (19.2+/-6.2 vs. 18.7+/-5.0 ng/ml; p=0.54). Adiponectin levels were also increased in hemodialysis patients compared to healthy controls (25.4+/-21.5 vs. 10.5+/-5.9 microg/ml; p<0.001). A significant inverse correlation was observed between the serum adiponectin levels before the hemodialysis session on the one hand and the BMI (r=-0.527, p=0.002), the HOMA-R (r=-0.378, p<0.05) and the fasting insulin levels (r=-0.397, p<0.05) on the other. However, no significant correlation was observed between serum resistin levels on the one hand versus HOMA-R index (3.2+/-3.9 mmol.microIU/ml; r=-0.098, p=0.59), insulin levels (13.3+/-14.4 mU/l; r=-0.073, p=0.69), glucose levels (89+/-13 mg/dl; r=-0.049, p=0.78), BMI (25.6+/-3.7 kg/m(2); r=-0.041, p=0.82) and body fat content (26.4+/-8.4%; r=-0.018, p=0.94) on the other hand. CONCLUSION: Resistin serum levels are significantly elevated in non-diabetic patients with end-stage renal disease that are treated by hemodialysis. The hemodialysis procedure does not affect the resistin levels. Along with previous observations in patients with renal insufficiency in the pre-dialysis stage, our findings implicate an important role of the kidney in resistin elimination. However, increased resistin serum levels in hemodialysis patients are not related to reduced insulin sensitivity encountered in uremia.     

Insulin therapy may increase blood pressure levels in type 2 diabetes mellitus

OBJECTIVE: To assess the effects of insulin therapy on blood pressure levels in type 2 diabetes mellitus (T2 DM). MATERIAL AND METHODS: This is a retrospective analysis of clinical records of 313 T2DM patients (125 men and 188 women), excluding those with proteinuria or hypertensive diseases and those taking drugs that may influence blood pressure levels except antihypertensive therapy. Mean age was 56.3 +/- 11.7 years and mean duration of diabetes was 7.1 +/- 5.5 years. After one week of observation under diet and maximal doses of oral antidiabetic drugs, patients who did not improve their glucose control were changed towards insulin therapy (n=129) and formed the insulin treated group (ITG), those who improved their glucose levels were maintained under oral therapy (n=184) and formed the orally treated group (OTG). Blood pressure levels were compared between the two groups at baseline and after a mean follow-up period of 12.1 +/- 6.1 months. Hypertension was considered if patients were known and treated or if SBP >=140 mmHg and/or DBP >=90 mmHg. RESULTS: At baseline, patients in ITG were moderately older (58.4 +/- 11 vs 54.9 +/- 12.1 years, p<0.05), had a longer duration of diabetes (9.2 +/- 6.2 vs 5.7 +/- 5 years, p<0.01), a lower BMI (24.6 +/- 4.6 vs 28.8 +/- 6.6 kg/m(2), p<0.01) and a higher frequency of retinopathy (44% vs 31.1%, p<0.05). There was no significant difference regarding sex ratio, WHR, family history of hypertension, plasma levels of creatinine and lipid parameters. SBP, DBP and frequency of hypertension were similar in both groups at baseline. After follow up, insulin treated group exhibited higher levels of SBP (150 +/- 25.7 vs 138.6 +/- 27.1 mmHg, p<0.001) and DBP (84.1 +/- 13 vs 75.8 +/- 14.9 mmHg, p<0.001) than orally treated group. Progression rate of hypertension frequency was mildly but not significantly higher in ITG than in OTG (+21% vs +12%, p=0.08) and was associated with weight gain in ITG only. SBP increase was mildly correlated with weight gain (p=0.06). In ITG, higher values of BMI (> 27 kg/m(2)) at baseline were associated with the highest increases of blood pressure levels under insulin therapy. No significant relationship was found with insulin doses. CONCLUSION: Insulin therapy may contribute to the development of hypertension in T2DM obese patients. Additional prospective randomised studies are required for a better appreciation of such influence.     

Plasma resistin, adiponectin and leptin levels in lean and obese subjects: correlations with insulin resistance

OBJECTIVE: Adipose tIssue regulates insulin sensitivity via the circulating adipocytokines, leptin, resistin and adiponectin. The objective of this study was to compare the levels of resistin, adiponectin and leptin in lean and obese subjects and determine the relationship between circulating adipocytokines and insulin resistance. METHODS: We examined plasma levels of resistin, adiponectin and leptin in 17 lean subjects with a mean body mass index (BMI) of approximately 23 and 34 non-diabetic obese individuals with a mean BMI approximately 33. Insulin resistance was assessed using the homeostasis model assessment ratio (HOMA-R) formula derived from fasting insulin and glucose levels. RESULTS: Resistin levels were not significantly different between the two groups but were significantly higher in women compared with men, 35.4+/-6.5 (s.e.) vs 15.4+/-2.9 microg/L, P<0.01. Resistin did not correlate with BMI but did significantly correlate with HOMA-R, P<0.01, and this correlation remained significant after adjustment for gender and BMI. Adiponectin levels were significantly lower in obese compared with lean subjects, P<0.005, and higher in women, P<0.001, but showed no significant correlation with HOMA-R. Leptin levels were significantly higher in obese subjects and women and correlated with HOMA-R and resistin. DISCUSSION: In this small group of patients we demonstrated that insulin resistance correlated most strongly with leptin levels. A significant correlation between resistin levels and insulin resistance was also observed. Although a similar trend was apparent for adiponectin, the correlation with insulin resistance did not achieve statistical significance.     

Serum concentrations of adipocytokines in patients with hyperthyroidism and hypothyroidism before and after control of thyroid function

OBJECTIVE: Adipose tissue is a hormonally active system that produces and releases different bioactive substances. Leptin, adiponectin and resistin are some of the recently discovered adipocytokines that participate in the regulation of intermediate metabolism. The aim of this study was to evaluate the circulating levels of leptin, adiponectin and resistin in patients with thyroid dysfunction before and after normalization of thyroid function with appropriate therapy. PATIENTS AND MEASUREMENTS: We studied 20 patients with hyperthyroidism (16 women and 4 men; mean age 47.2 +/- 3.9 years) and 20 patients with hypothyroidism (17 women and 3 men; 51.5 +/- 4.1 years). A group of 20 euthyroid subjects served as control group. Patients were evaluated at the time of diagnosis and again after normalization of thyroid function with appropriate therapy. Serum concentrations of free T4 (FT4), total T3, TSH, insulin, leptin, adiponectin and resistin were measured in all subjects. RESULTS: Hyperthyroid patients showed significantly decreased leptin levels in comparison with controls (11.0 +/- 1.1 vs. 30.4 +/- 5.0 microg/l, P < 0.001). No significant differences in adiponectin levels between hyperthyroid and control groups were found (27.8 +/- 4.0 vs. 46.0 +/- 12.0 mg/l, NS). Patients with hyperthyroidism exhibited reduced resistin levels in comparison with euthyroid subjects (6.4 +/- 0.8 vs. 8.4 +/- 0.7 microg/l, P < 0.05). Normalization of circulating thyroid hormone was accompanied by a nonsignificant increase in leptin levels (12.9 +/- 1.7 microg/l, P < 0.01 vs. control) and no significant modification both in adiponectin (32.0 +/- 7.1 mg/l, NS) and resistin (5.4 +/- 0.7 microg/l, NS) levels. Adjustment of adipocytokine concentrations for body mass index (BMI) showed that treatment of hyperthyroidism induced a significant reduction in adjusted resistin concentrations (0.21 +/- 0.03 vs. 0.28 +/- 0.03 microg/l/BMI units, P < 0.05), with no changes in adjusted leptin and adiponectin. Hypothyroid patients showed significantly lower leptin levels compared with the controls (16.0 +/- 3.5 vs. 30.4 +/- 5.0 microg/l, P < 0.05). Adiponectin levels in patients with hypothyroidism (71.8 +/- 16.0 mg/l) were similar to those in the control group and were not modified with therapy. Resistin levels were significantly reduced among hypothyroid patients (5.8 +/- 1.0 microg/l, P < 0.05), and were not increased after levothyroxine therapy. A significant rise in BMI-corrected leptin levels was observed after replacement therapy, with no changes in adiponectin- and resistin-corrected values. CONCLUSIONS: The results suggest that (1) low serum leptin levels are present in both hyperthyroid and hypothyroid patients but are only increased after therapy in the latter; (2) resistin might be implicated in the insulin resistance state that accompanies thyrotoxicosis; and (3) inadequate secretion of adiponectin seems to have no role in metabolic changes associated with thyroid dysfunction.     

Increase in adiponectin levels during pioglitazone therapy in relation to glucose control, insulin resistance as well as ghrelin and resistin levels

Glitazones increase the secretion of the adipocyte-derived hormone adiponectin. Furthermore, the gastric signal peptide ghrelin is known to suppress adiponectin expression in adipocyte cell culture models. It is not known whether the increase in adiponectin during glitazone therapy is due to a suppression of ghrelin levels, a decrease of resistin concentrations or an amelioration of glucose control. In 10 patients (age 71+/-9 yr, body mass index 29.9+/-3.6 kg/m(2), HbA1c 6.9+/-0.5%) with Type 2 diabetes, who had already been treated with sulfonylureas, we additionally initiated a pioglitazone therapy (30 mg/day) for 12 weeks. To investigate the pioglitazone effect independently of blood glucose, glycosylated hemoglobin (HbA1c) was kept unchanged by reducing the daily dose of sulfonylurea if necessary. Ghrelin concentration [radioimmunoassay (RIA), Phoenix Pharmaceuticals, Mountain View, CA, USA], adiponectin levels [enzyme-linked immunosorbent assay (ELISA), Biovendor, Heidelberg, Germany] as well as resistin concentrations (ELISA, Linco Research, St. Charles, MO, USA) were measured before and after pioglitazone. Glucose control remained unchanged within the 12-week pioglitazone therapy (HbA1c 6.9+/-0.5% before vs 6.8+/-0.6% after pioglitazone) while body weight increased from 86.6+/-9.2 to 88.0+/-9.4 kg (p<0.05), and insulin concentration decreased from 19.6+/-5.7 to 10.1+/-1.6 microU/ml (p<0.05). Adiponectin concentration increased in all patients from 7.70+/-2.47 to 23.33+/-8.28 microg/ml (p<0.01), while resistin concentrations tended to decrease (by 15%; p=0.059). However, ghrelin remained unchanged during therapy. No correlations were observed either between ghrelin, resistin, insulin and adiponectin, or between body weight and hormone plasma levels. The increase in adiponectin levels during pioglitazone therapy seems to be at least partly independent of blood glucose and insulin concentration as well as of ghrelin levels, and it was not associated with a decrease in resistin concentrations.     

Plasma adiponectin concentration in relation to severity of coronary atherosclerosis and cardiovascular risk factors in middle-aged men

Adiponectin, an adipocyte-derived protein, seems to be a link between obesity, insulin resistance, and atherosclerosis. The present study investigated the association between adiponectin and coronary artery disease in middle-aged men. Material and methods: We examined 48 men (aged 40–60) with angiographically confirmed coronary atherosclerosis and 19 healthy men, matched by age, as a control group. Concentrations of glucose and lipids were estimated with enzymatic methods. Plasma level of adiponectin, total and free testosterone, estradiol, estrone, DHEA-S, and insulin were estimated with RIA commercial kits. Results: Men with coronary atherosclerosis had lower plasma adiponectin level than controls (16.2±9.2 vs 20.5±6.7 μg/mL; p<0.05). However, after including BMI and waist as covariate data in ANCOVA, the difference in adiponectin levels between men with CAD and controls lost statistical significance (respectively for BMI and waist: p=0.4 and p=0.7). Moreover, although not significant, adiponectin levels decreased as a function of the number of significantly narrowed coronary arteries. In a priori comparison the lowest adiponectin plasma concentration was in men with three-vessel coronary artery disease (14.3±9.8 μg/mL) and the highest in controls (20.5±6.8 μg/mL; p=0.09). Adiponectin plasma level correlated negatively (p<0.05) with BMI, waist, percentage of total fat, fasting-insulin-resistance index (FIRI), total cholesterol and triglycerides, and positively with quantitative insulin sensitivity check index (QUICKI), HDL cholesterol, total testosterone, and total testosterone/estradiol ratio. Conclusions: Our data suggest that low plasma adiponectin level is connected with insulin resistance syndrome and atherogenic lipid profile. It seems that adiponectin plays a role in pathogenesis of coronary atherosclerosis, especially in obese and insulin-resistant subjects.     

The negative correlation between plasma adiponectin and blood pressure depends on obesity: a family-based association study in SAPPHIRe

BACKGROUND: The association between plasma adiponectin level and blood pressure remains inconclusive. Because obese subjects may have different mechanisms to regulate blood pressure, we hypothesized that obesity may be an important modifier. In order to minimize confounding effects from unidentified factors, a family-based design was employed to explore the relationship. METHODS: A total of 1,048 subjects from 478 Chinese or Japanese families with a mean age of 50.4 +/- 9.0 years were included (the SAPPHIRe (Stanford-Asian Pacific Program in Hypertension and Insulin Resistance) cohort). Blood pressure was recorded automatically and the average of the last two out of three consecutive readings was used in the analysis. A subject with "hypertension" was defined as one with a systolic blood pressure (SBP) > or =140 mm Hg, or a diastolic blood pressure (DBP) > or =90 mm Hg, or who was already on medication for hypertension. Obesity was defined as having a body mass index (BMI) > or =25 kg/m(2). The updated homeostasis model assessment was used for calculating the indices of insulin sensitivity (HOMA2 %S). Fasting plasma adiponectin was determined using radioimmunoassay. RESULTS: Subjects with hypertension had significantly lower plasma adiponectin levels than those without hypertension (5.99 +/- 3.64 microg/ml vs. 6.65 +/- 3.86 microg/ml, P < 0.01). Plasma adiponectin level correlated negatively with hypertension after adjusting for age, sex, and HOMA2%S (odds ratio (OR) 0.94, 95% confidence interval (CI) 0.90-0.98). In subjects without hypertension (n = 349), the plasma adiponectin level correlated negatively with SBP in those who were obese, after adjustment for age, sex, BMI, and HOMA2 %S (beta = -0.58, P = 0.03). The association was not significant in those without obesity. CONCLUSIONS: Plasma adiponectin level correlates negatively with hypertension. In subjects without hypertension, the relationship between plasma adiponectin level and SBP depends on the presence of obesity.     

脑卒中患者急性期血浆抵抗素和瘦素水平及其相关性研究

目的探讨脑卒中患者急性期血浆抵抗素、瘦素水平及与年龄、血压、血糖(Glu)、血脂、胰岛素的关系。方法选择59例脑出血(脑出血组)患者、54例脑梗死(脑梗死组)患者和57例健康老年人(对照组),采用酶联免疫法测定各组患者空腹血浆抵抗素、瘦素水平,同时检测空腹Glu、血脂、胰岛素,测量血压,进行各组比较。结果无论脑出血组还是脑梗死组抵抗素、瘦素水平都明显高于对照组,差异有显著性(P<0.05)。采用相关分析发现,脑出血组抵抗素和收缩压(SBP)、Glu、胰岛素均呈显著正相关(P<0.01),脑梗死组抵抗素和Glu、TG、胰岛素均呈显著正相关(P<0.05)。脑出血组瘦素和SBP、Glu、胰岛素均呈显著正相关(P<0.05或P<0.01),和高密度脂蛋白呈显著负相关(P<0.05),脑梗死组瘦素和SBP、DBP、Glu、胰岛素均呈显著正相关(P<0.05或P<0.01),脑出血组、脑梗死组抵抗素和瘦素浓度都呈显著正相关(P<0.05)。结论脑卒中急性期血浆抵抗素、瘦素水平升高,可能通过联合影响机体能量代谢和平衡,在脑卒中发生过程中发挥重要调控作用。     

Effects of retinoid therapy on insulin sensitivity, lipid profile and circulating adipocytokines

OBJECTIVE: In vitro and in vivo models indicate that all-trans retinoic acids influence glucose and lipid metabolism. We aimed to evaluate the effects of chronic treatment with acitretin, an all-trans retinoic acid, on glucose metabolism, lipid profile and adiponectin and resistin levels. DESIGN: Ten normoglycemic, normolipemic patients affected with psoriasis vulgaris were studied before and after 1 and 3 months of oral treatment with 35 microg of acitretin. METHODS: Glucose metabolism, lipid profile, and adiponectin and resistin levels were evaluated in basal conditions and after acitretin treatment. Ten healthy subjects matched for age, body mass index (BMI) and insulin sensitivity were studied as controls. RESULTS: One-month acitretin treatment reduced psoriasis activity, insulin sensitivity, evaluated as QUICKI values (0.364 +/- 0.034 versus 0.329 +/- 0.051; P < 0.05) and HOMA-IR index (1.53 +/- 0.73 versus 2.59 +/- 1.41; P < 0.05), and high-density lipoprotein (HDL)-cholesterol levels (45.2 +/- 11.7 versus 39.4 +/- 10.4 mg/dl; P = 0.01). The impairment in glucose and lipid homeostasis was transient and not associated to BMI variations. Adiponectin levels did not change during the treatment, while resistin levels, which were higher in untreated patients than in controls (9.4 +/- 4.4 versus 6.2 +/- 2.1 ng/ml; P = 0.05), fell within the normal range after 1 and 3 months of therapy. The normalization of resistin levels occurred without significant changes in circulating tumor necrosis factor alpha (TNFalpha) levels, which persisted elevated throughout the treatment. CONCLUSIONS: Treatment with a low dose of acitretin induced a mild, transient reduction of insulin sensitivity and HDL-cholesterol levels that was not related to modifications of adiponectin, resistin and TNFalpha levels. Although the role of resistin in humans remains elusive, the levels of this adipocytokine seem to be affected, at least in part, by retinoids.     

Relationship of adiponectin to body fat distribution,insulin sensitivity and plasma lipoproteins: evidence for independent roles of age and sex

AIMS/HYPOTHESIS: Increased intra-abdominal fat is associated with insulin resistance and an atherogenic lipoprotein profile. Circulating concentrations of adiponectin, an adipocyte-derived protein, are decreased with insulin resistance. We investigated the relationships between adiponectin and leptin, body fat distribution, insulin sensitivity and lipoproteins. METHODS: We measured plasma adiponectin, leptin and lipid concentrations, intra-abdominal and subcutaneous fat areas by CT scan, and insulin sensitivity index (S(I)) in 182 subjects (76 M/106F). RESULTS: Adiponectin concentrations were higher in women than in men (7.4+/-2.9 vs 5.4+/-2.3 micro g/ml, p<0.0001) as were leptin concentrations (19.1+/-13.7 vs 6.9+/-5.1 ng/ml, p<0.0001). Women were more insulin sensitive (S(I): 6.8+/-3.9 vs 5.9+/-4.4 x 10(-5) min(-1)/(pmol/l), p<0.01) and had more subcutaneous (240+/-133 vs 187+/-90 cm(2), p<0.01), but less intra-abdominal fat (82+/-57 vs 124+/-68 cm(2), p<0.0001). By simple regression, adiponectin was positively correlated with age ( r=0.227, p<0.01) and S(I) ( r=0.375, p<0.0001), and negatively correlated with BMI ( r=-0.333, p<0.0001), subcutaneous ( r=-0.168, p<0.05) and intra-abdominal fat ( r=-0.35, p<0.0001). Adiponectin was negatively correlated with triglycerides ( r=-0.281, p<0.001) and positively correlated with HDL cholesterol ( r=0.605, p<0.0001) and Rf, a measure of LDL particle buoyancy ( r=0.474, p<0.0001). By multiple regression analysis, adiponectin was related to age ( p<0.0001), sex ( p<0.005) and intra-abdominal fat ( p<0.01). S(I) was related to intra-abdominal fat ( p<0.0001) and adiponectin ( p<0.0005). Both intra-abdominal fat and adiponectin contributed independently to triglycerides, HDL cholesterol and Rf. CONCLUSION/INTERPRETATION: These data suggest that adiponectin concentrations are determined by intra-abdominal fat mass, with additional independent effects of age and sex. Adiponectin could link intra-abdominal fat with insulin resistance and an atherogenic lipoprotein profile.     

The effects of rosiglitazone and metformin on the plasma concentrations of resistin in patients with type 2 diabetes mellitus

Resistin is a protein secreted from adipose tissue that is thought to play a role in insulin sensitivity. We examined the effects of rosiglitazone and metformin on the plasma resistin levels in individuals with type 2 diabetes mellitus. Patients with type 2 diabetes mellitus who showed poor glycemic control with glimepiride (4 mg/d) were randomized to rosiglitazone (4 mg/d) and metformin (500 mg bid) treatment groups. All subjects continued glimepiride treatment as well. The plasma concentrations of resistin were measured at baseline and at 6 months of treatment for both groups. The anthropometric parameters, fasting plasma glucose, HbA1c, total cholesterol, triglyceride, high-density lipoprotein cholesterol, free fatty acids, and adiponectin concentrations were also measured. After 6 months of treatment, the reduction in plasma glucose levels was similar between the 2 groups. There were no significant changes in the lipid profiles of either group during the study period. The plasma resistin levels decreased in the rosiglitazone group (2.49 +/- 1.93 vs 1.95 +/- 1.59 ng/ml; P < .05) but increased in the metformin group (2.61 +/- 1.69 vs 5.13 +/- 2.81 ng/ml; P < .05). The plasma adiponectin concentrations were increased in the rosiglitazone group (2.91 +/- 1.46 vs 4.23 +/- 1.77 microg/ml; P < .05) but were unchanged in the metformin group. In summary, rosiglitazone treatment decreased the plasma resistin levels whereas metformin treatment increased them in patients with type 2 diabetes mellitus showing poor glycemic control with sulfonylurea therapy. These results suggest that the observed changes in plasma resistin levels are not the consequences of improved insulin resistance, nor are they consequences of glycemic control. Considering the potential role of resistin in insulin resistance, decrease in resistin levels may contribute to improving insulin action with rosiglitazone treatment.     

高血压病患者血清脂联素浓度的变化及其意义

目的探讨原发性高血压病患者血清脂联素浓度的变化及其与血压之间的关系。方法本研究选取原发性高血压病患者50例及健康人50例(正常对照组),常规测量血压、体质量、身高,计算体质量指数,检测血清脂联素、空腹血糖、血清胰岛素、总胆固醇、高密度脂蛋白胆固醇、甘油三酯等指标。再将50例高血压病患者分成两组,每组25例,分别用血管紧张素转换酶抑制剂西拉普利及血管紧张素Ⅱ受体拮抗剂替米沙坦治疗2周,治疗前后均检测上述指标。结果①原发性高血压病患者与健康对照者比较,血清脂联素水平下降犤(4.13±1.89)μg/mlvs(7.09±2.85)μg/ml,P<0.05犦,健康对照组脂联素浓度与体质量指数、总胆固醇呈负相关(r=-0.28,-0.26,P<0.05);②原发性高血压组血清脂联素浓度与收缩压、舒张压、甘油三酯呈显著负相关(r=-0.36、-0.32、-0.37,P<0.05),高血压组与健康对照组两组合并比较,脂联素浓度与BMI体质量指数、收缩压、舒张压呈显著负相关(r=-0.29、-0.28、-0.31,P<0.01);③高血压患者分别用西拉普利及替米沙坦治疗两周后,血压显著下降(P<0.05),血清脂联素浓度明显升高(P<0.05)。结论在原发性高血压病患者中,血清脂联素水平下降并与血压之间存在一定的相关性,与脂代谢紊乱亦相关。     

Perturbations in adiponectin,leptin and resistin levels in acromegaly: lack of correlation with insulin resistance

BACKGROUND: Insulin resistance, impaired glucose tolerance and type 2 diabetes are common in acromegalic subjects. The mechanism underlying this insulin resistance is unclear. DESIGN: We investigated the levels of the adipocytokines, resistin, adiponectin and leptin in a group of 18 acromegalic subjects and 18 control subjects matched for age, gender and body mass index. RESULTS: Here we demonstrate for the first time significant elevation in adiponectin levels in acromegalic subjects compared to control subjects 12.5 +/- 1.2 vs. 8.97 +/- 1.1 mg/l, P = 0.029. The resistin levels were similar in acromegalic subjects and controls; 20.65 +/- 2.99 vs. 19.03 +/- 4.72 micro g/l. No evidence of a correlation between adiponectin and insulin resistance as calculated from HOMA-R was found. No correlation was observed either between adiponectin or resistin levels and GH levels, total IGF-I or free IGF-I levels. Leptin levels were significantly reduced in acromegalic subjects, 8.22 +/- 2.26 vs. 18.3 +/- 4.1 micro g/l, P = 0.004. In control subjects, significant correlations between leptin levels and HOMA-R and between resistin levels and HOMA-R were observed. These relationships were not apparent in acromegalic subjects. CONCLUSION: From these data we conclude that changes in resistin and adiponectin levels are unlikely to account for the insulin resistance of acromegaly.     

Serum concentrations of adiponectin and resistin in hyperthyroid Graves' disease patients

This study was undertaken to determine whether serum adiponectin and resistin levels are influenced by hyperthyroidism and autoimmune factors and to find out whether their levels are dependent on the presence of ophthalmopathy. We measured serum concentrations of adiponectin and resistin in 76 patients (63 women, 13 men) with Graves' disease (GD) and compared them with levels of the control group which consisted of 30 healthy subjects. Patients were separated into two groups according to the presence or the absence of thyroid-associated ophthalmopathy (TAO). TAO (-) group consisted of 26 subjects without eye signs of GD and TAO (+) group included 50 subjects with ophthalmopathy. The latter group was further divided into 2 subgroups: with active TAO [26 patients, clinical activity score (CAS)> or =4] and with inactive TAO (24 patients, CAS<4). Groups did not differ in age, sex, body mass index (kg/m2) and smoking habits. Compared with euthyroid subjects, hyperthyroid GD patients had elevated mean serum adiponectin concentrations (19.96+/-4.97 microg/ml vs 15.01+/-3.99 microg/ml, p<0.001). However we did not observe any disparity between the TAO (-) and TAO (+) groups (20.60+/-5.06 microg/ml vs 19.63+/-4.94 microg/ml, p=ns). Comparing patients with a CAS> or =4 and patients with a CAS<4, we found similar mean serum concentrations of adiponectin (20.04+/-5.01 microg/ml vs 18.74+/-4.83 microg/ml, p=ns). Serum levels of resistin did not differ between the hyperthyroid patients and control subjects (13.11+/-4.26 ng/ml vs 12.82+/-4.75 ng/ml, p=ns). Serum resistin levels did not differ between TAO (+) and TAO (-) groups nor in patients with active and inactive TAO. Serum adiponectin correlated significantly with free T4 (FT4), free T3 (FT3), and TSH-R antibodies (TRAb) in GD patients (r=0.40, 0.41, and 0.37, respectively; p<0.001 for each). Serum resistin levels were not correlated with thyroid hormones and thyroid antibodies. The variables that in simple linear regression analyses were found to be correlated with serum adiponectin were then used in multiple regression analysis. In a model including adiponectin as dependent variable and FT4, FT3 and TRAb levels as independent variables, FT3 and TRAb remained as parameters independently related to adiponectin level (R2=0.35, p<0.001). CONCLUSIONS: Elevated serum adiponectin levels in GD patients are related to the degree of hyperthyroidism and autoimmune process. The presence and activity of ophthalmopathy is not a modifier of serum adiponectin and resistin.     

Is adiponectin level a predictor of nonalcoholic fatty liver disease in nondiabetic male patients？

AIM: To study the levels of adiponectin in nondiabetic patients with nonalcoholic fatty liver disease (NAFLD) in comparison with control group. METHODS: Thirty-five patients who had elevated serum aminotransferase levels with bright liver and 34 healthy volunteers without liver disease were evaluated. Age, gender and body mass index (BMI) were recorded. Fasting plasma glucose, insulin, adiponectin, proinsulin and lipid profile were measured. A standard oral glucose tolerance test (OGTT) with insulin response was performed and the index of insulin resistance was calculated according to the homeostasis model assessment (HOMA) method. RESULTS: According to the OGTT results, none of the participants had diabetes. Serum adiponectin levels were statistically significantly lower in patients with NAFLD than in control group (8.14±3.4μg/mL vs 12.4±9.4μg/mL, respectively, P<0.01). A statistically significant correlation was found between adiponectin and BMI (r: -0.33, P<0.01), HOMA (r: -0.26, P<0.05), proinsulin (r:-0.32, P<0.01), AST (r: -0.25, P<0.05), ALT (r: -0.26, P<0.05) or GGT (r: -0.22, P<0.05). In multiple regression analysis models, adiponectin levels were the only predictor of NAFLD in males, whereas in female group it was the BMI. CONCLUSION: Low adiponectin level might be a predictor of NAFLD especially in male nondiabetics.     

Increased serum resistin in nonalcoholic fatty liver disease is related to liver disease severity and not to insulin resistance

CONTEXT: The recently discovered hormone resistin is linked to the development of insulin resistance, but direct evidence of resistin levels in humans with nonalcoholic fatty liver disease (NAFLD) is lacking. METHODS: We conducted this study to assess the relationship between serum resistin and NAFLD. We measured serum resistin and biochemical, hormonal, and histological correlates in 28 NAFLD patients, 33 controls, and 30 obese patients [body mass index (BMI), >30 kg/m2] without NAFLD. RESULTS: Resistin and adiponectin expression were measured in sc adipose tissue by quantitative RT-PCR. Resistin was higher in NAFLD patients compared with controls (5.87 +/- 0.49 vs. 4.30 +/- 0.20 ng/ml; P = 0.002) and obese patients (4.37 +/- 0.27 ng/ml; P = 0.002). Increased resistin mRNA was also found in the adipose tissue of NAFLD patients compared with controls and obese subjects. CONCLUSIONS: Both NAFLD and obese patients had lower adiponectin levels, whereas leptin was increased only in the obese group. No correlation was found between resistin and high-sensitivity C-reactive protein, BMI, homeostasis model assessment, insulin, glucose, transaminases, and lipid values. A positive correlation was found between resistin and histological inflammatory score. These data report increased resistin in NAFLD patients that is related to the histological severity of the disease, but do not support a link between resistin and insulin resistance or BMI in these patients.     

Decreased plasma adiponectin is associated with insulin resistance and HDL cholesterol in overweight subjects

The purpose of this study was to investigate plasma adiponectin concentration and its relation with metabolic parameters in overweight and normal weight subjects. The study was carried out in 46 overweight subjects (20 male, 26 female; mean age 39.4 +/- 10.2 years) and 48 (19 male, 29 female; mean age 36.1 +/- 10.6 years) sex- and age-matched normal weight subjects. Anthropometric measurements were recorded and adiponectin, glucose, insulin, lipid profile, total homocysteine (tHcy) and fibrinogen levels were measured. The insulin resistance index was assessed by homeostasis model assessment for insulin resistance (HOMA-IR). Plasma mean adiponectin concentrations of the overweight subjects were significantly lower than those of normal weight subjects (15.0 +/- 4.2 vs 17.3 +/- 5.6 ng/ml) (P<0.05). In overweight subjects, adiponectin levels negatively correlated with body weight (r = -0.35, P<0.001), body mass index (BMI) (r = -0.28, P<0.006), systolic blood pressure (r = -0.21, P<0.04), fasting insulin (r = -0.19, P<0.01) and HOMA-IR (r = -0.20, P<0.01) and positively with high-density lipoprotein cholesterol (HDL-C) (r = 0.27, P<0.009). Overweight subjects with low HDL-C levels had significantly decreased plasma adiponectin levels compared to those with high HDL-C levels (P<0.05). Multiple regression analysis revealed that BMI, HOMA-IR and HDL-C explained 12%, 20% and 15% variance of the adiponectin concentrations. These findings may suggest that circulating adiponectin is associated with insulin resistance and HDL-C levels independent from BMI in overweight subjects.     

Decreased plasma adiponectin concentrations in nondiabetic women with elevated homeostasis model assessment ratios

OBJECTIVE: Whether the adipocyte-derived protein adiponectin is associated with insulin resistance independently of the effects of adiposity and the diabetic state is an important question. We explored, in a cross-sectional study of 486 Japanese nondiabetic women, the relationship between the calculated insulin resistance (homeostasis model assessment ratio (HOMA-R)) and adiponectin levels determined using a validated sandwich ELISA. DESIGN AND METHODS: All participants were stratified into tertiles for HOMA-R (approximately <1.5, 1.5< or = approximately <3.0, 3.0< or = approximately ) and the differences across tertiles of continuous variables were tested with ANOVA. Two-way ANOVA was used to determine possible relationships for plasma adiponectin between tertiles of HOMA-R and several stratified parameters. Multiple regression analyses were performed with HOMA-R or fasting serum insulin as dependent variable, and diastolic blood pressure (BP), body mass index (BMI), serum triglyceride (TG), leptin and adiponectin as independent determinants. RESULTS: Mean plasma adiponectin in the high HOMA-R group decreased compared with that in the low HOMA-R group both before (mean+/-s.e.m. 6.2+/-0.6 vs 9.2+/-0.3 microg/ml, P<0.001) and after adjustment for body fat mass (BFM) as kg or percent (0.31+/-0.04 vs 0.69+/-0.03, 0.18+/-0.02 vs 0.34+/-0.01, both P<0.001). HOMA-R was inversely associated with adiponectin levels both before (r=-0.37, P<0.001) and after adjustment for BFM (r=-0.49, -0.46, both P<0.001). After covariate adjustment for age, diastolic BP, BMI and serum TG, HOMA-R retained a significant correlation with adiponectin/BFM (kg). Both adiponectin and leptin were the significant determinants of HOMA-R or fasting insulin in multiple regression models. CONCLUSIONS: Adiponectin was inversely associated with insulin resistance in nondiabetic subjects, independently from age, BP, adiposity and serum lipids. Because adiponectin is thought to have an anti-atherogenic action, the presence of hypoadiponectinemia may predispose subjects to atherosclerosis, and may progress the atherogenesis in insulin resistance.