Cigarette smoking increases levels of retinol-binding protein-4 in healthy men with normal glucose tolerance

Department of Endocrinology, Jingxi Branch, Beijing Chaoyang Hospital, Captial Medical University, Beijing 100043, China.
Chinese medical journal (Impact Factor: 1.02). 05/2012; 125(10):1686-1689.

ABSTRACT Background Smoking is related with insulin resistance and type 2 diabetes mellitus. Retinol-binding protein-4 is a new adipocytokine associated with insulin resistance. We investigated the serum levels of a series of adipocytokines including retinol-binding protein-4 in smokers and non-smokers to explore the possible roles of adipocytokines on smoking induced insulin resistance.

Methods A total of 136 healthy male subjects (92 smokers and 44 non-smokers) with normal glucose tolerance were enrolled in the study. Adipocytokines including retinol-binding protein-4, visfatin, leptin, resistin, adiponectin were measured for the comparison between the two groups. Serum lipid profile, glucose, true insulin and proinsulin levels were measured as well in both groups. Food intake spectrum was also investigated.

Results Both groups had similar profile of food consumption; visfatin, leptin, resistin and adiponectin, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, alanine aminotransferase, aspartate aminotransferase, as well as blood pressure and body mass index, were similar in both groups. Triglycerides, retinol-binding protein-4 and homeostatic model assessment index for insulin resistance were higher in smoker group ((2.58±2.53) vs. (1.60±0.94) mmol/L, (26.05±8.50) vs. (21.83±8.40) µg/ml, and 2.25±2.08 vs. 1.58±1.15, respectively).

Conclusion Smoking may have effect on insulin sensitivity, which is correlated with retinol-binding protein-4.

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    ABSTRACT: BACKGROUND: Endothelial dysfunction is an independent risk factor for cardiovascular events. Inflammatory mediators released by the adipose tissue can lead to local insulin resistance and endothelial dysfunction. This study addressed the relationship of adipocytokines with endothelial function and blood pressure. METHODS: In 92 newly diagnosed, drug-naive essential hypertensive patients (HT, mean age 49 yrs) without organ damage and 66 normotensive subjects (NT, mean age 47 yrs), by an automated system, we measured endothelium-dependent and -independent vasodilation as brachial artery flow-mediated dilation before and after administration of glyceryl-trinitrate. Retinol binding protein-4 (RBP4) and resistin levels were determined by ELISA and RIA, respectively. Oxidative stress was evaluated by measuring serum malondyaldehyde (MDA). RESULTS: Flow-mediated dilation was significantly (p = 0.03) lower in HT (5.3 [PLUS-MINUS SIGN] 2.6%) than NT (6.1 [PLUS-MINUS SIGN] 3.1%), while response to glyceryl-trinitrate (7.5 [PLUS-MINUS SIGN] 3.7% vs 7.9 [PLUS-MINUS SIGN] 3.4%) was similar. RBP4 (60.6 [PLUS-MINUS SIGN] 25.1 vs 61.3 [PLUS-MINUS SIGN] 25.9 mug/ml), resistin (18.8 [PLUS-MINUS SIGN] 5.3 vs 19.9 [PLUS-MINUS SIGN] 6.1 ng/ml) and MDA levels (2.39 [PLUS-MINUS SIGN] 1.26 vs 2.08 [PLUS-MINUS SIGN] 1.17 nmol/ml) were not different in HT and NT.RBP4 (r = [MINUS SIGN]0.25; p = 0.04) and resistin levels (r = [MINUS SIGN]0.29; p = 0.03) were related to flow-mediated dilation in NT, but not in HT (r = [MINUS SIGN]0.03 and r = [MINUS SIGN]0.10, respectively). In NT multivariate analysis, including RBP4 and confounders showed that only BMI or waist circumference remained related to flow- mediated dilation. In the multivariate model including resistin and confounders, BMI, age and resistin were significantly related to flow-mediated dilation, while only age significant correlated with this parameter when BMI was replaced by waist circumference. CONCLUSIONS: Adipocytokine levels may be independent predictors of endothelial dysfunction in the peripheral circulation of healthy subjects, providing a pathophysiological link between inflammation from adipose tissue and early vascular alterations.
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