Brown and beige adipose tissue: New therapeutic targets for metabolic disorders

Brown adipocytes constitute a specialized tissue in heat build-up (i.e., thermogenesis) due to their mitochondrial uncoupling capacity, as they express thermogenic genes, playing a role in the energy metabolism of the whole body in mammals through non-shivering thermogenesis. Beige adipocytes originate in white adipose tissue (WAT) through the tissue browning process and are phenotypically similar to brown adipocytes. Considering that the activity of these cells is essential to reduce the incidence of metabolic diseases, including obesity, type 2 diabetes, and dyslipidemia, the stimulation of the brown fat and the development of beige adipose tissue has become a promising therapeutic target to treat clinical conditions. Due to the low amount of brown adipose tissue (BAT) in human adults, both phenomena (i.e., activation of brown and development of beige adipocytes) are related to better control of body weight, adiposity, insulin resistance, and hyperlipidemia. This review focuses on the comprehensively discussion of the metabolic importance of BAT activation and/or browning of WAT, and approaches that lead to the biogenesis of these thermogenic fats, such as cold exposure, thyroid hormones, physical exercise, diet and pharmacological agents (i.e., β3-adrenergic receptor agonist, glucagon-like peptide 1, mineralocorticoid receptor antagonists, ephedrine). These stimulatory agents have shown promise in activating BAT in humans. Frow our review, concluded that there are still many obstacles to be overcome in the upcoming years to better assess the real impact of BAT activation on metabolic health (i.e., absence of insulin resistance and metabolic syndrome), and elucidate many questions surrounding BAT physiology, so that this organ can indeed be considered an attractive therapeutic target for the prevention and reversal of obesity and metabolic disorders.