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Blunted metabolic responses to cold and insulin stimulation in brown adipose tissue of obese humans
Author(s) -
Orava Janne,
Nuutila Pirjo,
Noponen Tommi,
Parkkola Riitta,
Viljanen Tapio,
Enerbäck Sven,
Rissanen Aila,
Pietiläinen Kirsi H.,
Virtanen Kirsi A.
Publication year - 2013
Publication title -
obesity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.438
H-Index - 199
eISSN - 1930-739X
pISSN - 1930-7381
DOI - 10.1002/oby.20456
Subject(s) - brown adipose tissue , medicine , endocrinology , insulin , weight loss , adipose tissue , obesity , carbohydrate metabolism , stimulation , glucose uptake , biology
Objective Inactive brown adipose tissue (BAT) may predispose to weight gain. This study was designed to measure metabolism in the BAT of obese humans, and to compare it to that in lean subjects. The impact of weight loss on BAT and the association of detectable BAT with various metabolic characteristics were also assessed. Design and Methods Using positron emission tomography (PET), cold‐ and insulin‐stimulated glucose uptake and blood flow in the BAT of obese and lean humans were quantified. Further, cold‐induced glucose uptake was measured in obese subjects before and after a 5‐month conventional weight loss. Results Mean responses in BAT glucose uptake rate to both cold and insulin stimulation were twice as large in lean as in obese subjects. Blood flow in BAT was also lower in obese subjects under cold conditions. The increase in cold‐induced BAT glucose uptake rate after weight loss was not statistically significant. Subjects with cold‐activated detectable BAT were leaner and had higher whole‐body insulin sensitivity than BAT‐negative subjects, irrespective of age and gender. Conclusions The effects of cold and insulin on BAT activity are severely blunted in obesity, and the presence of detectable BAT may contribute to a metabolically healthy status.