Different metabolic responses of human brown adipose tissue to activation by cold and insulin
Janne Orava, Pirjo Nuutila, Martin E Lidell, Vesa Oikonen, Tommi Noponen, Tapio Viljanen, Mika Scheinin, Markku Taittonen, Tarja Niemi, Sven Enerbäck, Kirsi A Virtanen, Janne Orava, Pirjo Nuutila, Martin E Lidell, Vesa Oikonen, Tommi Noponen, Tapio Viljanen, Mika Scheinin, Markku Taittonen, Tarja Niemi, Sven Enerbäck, Kirsi A Virtanen
Abstract
We investigated the metabolism of human brown adipose tissue (BAT) in healthy subjects by determining its cold-induced and insulin-stimulated glucose uptake and blood flow (perfusion) using positron emission tomography (PET) combined with computed tomography (CT). Second, we assessed gene expression in human BAT and white adipose tissue (WAT). Glucose uptake was induced 12-fold in BAT by cold, accompanied by doubling of perfusion. We found a positive association between whole-body energy expenditure and BAT perfusion. Insulin enhanced glucose uptake 5-fold in BAT independently of its perfusion, while the effect on WAT was weaker. The gene expression level of insulin-sensitive glucose transporter GLUT4 was also higher in BAT as compared to WAT. In conclusion, BAT appears to be differently activated by insulin and cold; in response to insulin, BAT displays high glucose uptake without increased perfusion, but when activated by cold, it dissipates energy in a perfusion-dependent manner.
Copyright © 2011 Elsevier Inc. All rights reserved.
Source: PubMed