Obese male subjects show increased resting forearm venous plasma noradrenaline concentration but decreased 24-hour sympathetic activity as evaluated by thrombocyte noradrenaline measurements

Abstract

OBJECTIVE: To study resting forearm venous plasma noradrenaline (NA) and 24 h sympathoadrenal activity evaluated by measurements of thrombocyte NA and adrenaline (A) in obese male subjects before and after weight reduction. DESIGN: Blood samples were collected in obese subjects and in controls after an overnight fast. MEASUREMENTS: Fatness and fat distribution parameters, plasma and thrombocyte NA and A, lymphocyte b b 2 -adrenoceptor mRNA, cAMP and lymphocyte subset composition. RESULTS: Forearm venous plasma NA at rest was signi®cantly elevated in the obese subjects and correlated to the body mass index and diastolic blood pressure. Thrombocyte NA and A correlated, however, negatively to the body fat % in obese subjects. Further analysis showed that thrombocyte NA and A were reduced in obese subjects with body fat % above 40% but not in the other groups. Weight reduction normalized both forearm venous plasma NA and thrombocyte NA and A. b b 2 -adrenoceptor mRNA correlated positively to the frequency of CD3 7 CD56 and CD3 CD8 cells in the blood and negatively to plasma A, but there was no difference in the mRNA level, cyclic AMP and lymphocyte subset composition between obese and controls. CONCLUSIONS: Sympathetic activity at rest as evaluated by forearm venous plasma NA was increased in the obese male subjects and this abnormality was related to the increase in body mass index and the arterial blood pressure. Thrombocyte NA and A, which is likely to re¯ect 24 h plasma catecholamine concentrations were reduced in obese subjects with a body fat % above 40%, probably due to a reduced physical activity in these subjects. Both catecholamine parameters were normalized by weight reduction.

Are Zucker obese rats a useful model for cardiovascular complications in metabolic syndrome? Physical, biochemical and oxidative stress considerations

“…Studies on in vivo ventricular function assessed by echocardiography gave mixed results; in some, improved function in ZO rat hearts [21] was found, while other authors reported a reduction in contractile function [22]. In our study, ZO rats tended to be tachycardiac in vivo; this tendency was reversed in vitro, where neurohumoral influences disappeared, suggesting for instance an increase in circulating catecholamines, which has already been observed in ZO rats [23], and in obese humans [24].…”

Leptin Levels Are Associated with Fat Oxidation and Dietary‐Induced Weight Loss in Obesity

“…Clearly additional studies are needed to complete our understanding of the mechanism. The finding of an inverse correlation between thrombocytic catecholamines and FM in obese subjects might, as discussed previously (35), reflect a reduction in the sympathoadrenal activity with increasing body mass index.…”

“…In 22 subjects, 12 obese and 10 lean, plasma and thrombocytic concentrations of adrenaline and noradrenaline were determined, as a measure of sympathetic activity as described previously (35). These subjects did not differ from the whole group with respect to age, height, weight, body composition, 24-hour EE, or fasting plasma leptin.…”

Lymphocyte glucocorticoid receptor mRNA correlates negatively to serum leptin in normal weight subjects

“…No differences were demonstrated between normal subjects or obese subjects as regards the b 2 -adrenoceptor mRNA level and the subset composition. 10 In conclusion, we have shown that the lymphocyte GCR mRNA concentration and serum leptin concentrations are inversely correlated and both of them related to the waist ± hip ratio in a group of normal non-obese subjects. It is suggested that the decrease in GCR mRNA concentration with increasing serum leptin concentrations is a counter-regulatory response to an increased body fat content.…”