Previous studies revealed altered levels of the circulating insulin-like growth factor-I (IGF-I) and of its binding protein-3 (IGFBP-3) in subjects with coronary atherosclerosis, metabolic syndrome and premature atherosclerosis. Hyperlipidemia is a powerful risk factor of atherosclerosis. We expected IGF-I and IGFBP-3 alterations in subjects with moderate/severe hyperlipidemia but without any clinical manifestation of atherosclerosis. Total IGF-I and IGFBP-3 were assessed in 56 patients with mixed hyperlipidemia (MHL; cholesterol>6.0 mmol/l, triglycerides>2.0 mmol/l), in 33 patients with isolated hypercholesterolemia (IHC; cholesterol>6.0 mmol/l, triglycerides<2.0 mmol/l), and in 29 healthy controls (cholesterol<6.0 mmol/l, triglycerides<2.0 mmol/l). The molar ratio of IGF-I/IGFBP-3 was used as a measure of free IGF-I. IHC subjects differed from controls by lower total IGF-I (164±60 vs. 209±73 ng/ml, p=0.01) and IGF-I/IGFBP-3 ratio (0.14±0.05 vs. 0.17±0.04, p=0.04). Compared to controls, MHL subjects had lower total IGF-I (153±54 ng/ml, p=0.0002) and IGFBP-3 (2.8±0.6 mg/ml, p<0.0001), but higher IGF-I/IGFBP-3 ratio (0.25±0.06, p<0.0001). Differences remained significant after the adjustment for clinical and biochemical covariates, except for triglycerides. Patients with both IHC and MHL have lower total IGF-I compared to controls. The mechanism is presumably different in IHC and MHL. Because of prominent reduction of IGFBP-3 in patients with MHL, they have reduced total IGF-I despite the actual elevation IGF-I/IGFBP-3 ratio as a surrogate of free IGF-I., J. Malík, T. Štulc, D. Wichterle, V. Melenovský, E. Chytilová, Z. Lacinová, J. Marek, R. Češka., and Obsahuje bibliografii a bibliografické odkazy
Retinol binding protein 4 (RBP4) is a novel adipokine which might be involved in the development of insulin resistance. The aim of the study was to investigate the expression of RBP4 mRNA in subcutaneous and visceral fat depots and the relationship between RBP4 plasma and mRNA levels relative to indices of adiposity and insulin resistance. In 59 Caucasian women (BMI 20 to 49 kg/m2 ) paired samples of subcutaneous and visceral fat were obtained for RBP4, leptin and GLUT 4 mRNA analysis using reverse transcription-quantitative PCR. Euglycemic hyperinsulinemic clamp and computed tomography scans were performed. RBP4 mRNA levels as well as GLUT 4 mRNA and leptin mRNA levels were lower (P<0.001, P<0.01 and P<0.001, respectively) in visceral compared to subcutaneous fat. No differences were found in RBP4 mRNA expression in the two fat depots or in RBP4 plasma levels between subgroups of non-obese subjects (n=26), obese subjects without metabolic syndrome (n=17) and with metabolic syndrome (n=16). No correlations between RBP4 mRNA or plasma levels relative to adiposity, glucose disposal rate and GLUT 4 mRNA expression in adipose tissue were found. There was a weak positive correlation between plasma RBP4 and plasma triglycerides (r = 0.30, p<0.05) and between plasma RBP4 and blood glucose (r = 0.26, p<0.05). Regardless of the state of adiposity or insulin resistance, RBP4 expression in humans was lower in visceral than in subcutaneous fat. We found no direct relationship between either RBP4 mRNA or its plasma levels and the adiposity or insulin resistance. and Obsahuje bibliografii a bibliografické odkazy