Accumulation of brown adipose tissue in patients with Chagas heart disease

Treadmill running alleviates adipose tissue browning and lipolysis in rats with heart failure

This study observed the effects of treadmill running on adipose tissue browning and lipolysis in rats with induced heart failure and elucidated the possible mechanism. Rats underwent abdominal aortic constriction as a model of heart failure. Cardiac function was detected by echocardiography. We detected serum levels of norepinephrine and interleukin 6, cardiac atrial natriuretic peptide and brain natriuretic peptide and marker genes of browning, white adipose tissue (WAT), and lipolysis in adipose tissue. Rats with heart failure showed typical symptoms such as increased heart weight and mRNA levels of atrial natriuretic peptide and brain natriuretic peptide and decreased left ventricular ejection fraction. Exercise partially improved left ventricular diastolic function and significantly decreased atrial natriuretic peptide expression. Rats with heart failure showed significantly reduced body weight and ratios of muscle and fat weight to body weight. Exercise significantly increased body weight and the ratio of muscle weight to body weight. Heart failure stimulated the expression of proliferator-activated receptor-gamma coactivator-1-alpha and uncoupling protein 1 in epididymal WAT, inguinal WAT, and brown adipose tissue but decreased that of adiponectin and leptin in inguinal WAT. Lipolysis, characterized by high adipose triglyceride lipase and hormone-sensitive lipase expression, was activated in all adipose tissues. Exercise reduced browning and lipolysis in adipose tissues. Rats with heart failure had abnormally high levels of serum norepinephrine and interleukin 6, which could be suppressed by exercise. Exercise may improve cardiac cachexia and inhibit the browning and lipolysis of adipose tissue by downregulating sympathetic nervous system activity and inflammation.

The human uncoupling protein-1 gene (UCP1): present status and perspectives in obesity research

Energy expenditure through brown adipose tissue thermogenesis contributes either to maintenance of body temperature in a cold environment or to wasted food energy, i.e. cold-induced or diet-induced thermogenesis. Both mechanisms are due to a specific and unique protein: the uncoupling protein-1. Uncoupling protein-1 is exclusively expressed in mitochondria of brown adipocytes where it uncouples respiration from ATP synthesis, dissipating the proton gradient as heat. In humans, although uncoupling protein-1 can be detected, the inability to quantify brown adipose tissue makes it difficult to argue for a role for uncoupling protein-1 in thermogenesis and energy expenditure. This review summarizes data supporting the existence of brown adipocytes and the role of UCP1 in energy dissipation in adult humans. Understanding the mechanisms which regulate transcription and expression of the human UCP1 gene will facilitate the identification of molecules able to increase the levels of this protein in order to modulate energy expenditure in adult humans.