Kinin B1 receptor deficiency promotes enhanced adipose tissue thermogenic response to β3-adrenergic stimulation.

Kinin B1 receptor (B1R) has a key role in adipocytes to protect against obesity and glycemic metabolism, thus becoming a potential target for regulation of energy metabolism and adipose tissue thermogenesis. Kinin B1 knockout mice (B1KO) were subjected to acute induction with CL 316,243 and chronic cold exposure. Metabolic and histological analyses, gene and protein expression and RNA-seq were performed on interscapular brown adipose tissue (iBAT) and inguinal white adipose tissue (iWAT) of mice. B1KO mice, under acute effect of CL 316,243, exhibited increased energy expenditure and upregulated thermogenic genes in iWAT. They were also protected from chronic cold, showing enhanced non-shivering thermogenesis with increased iBAT mass (~ 90%) and recruitment of beige adipocytes in iWAT (~ 50%). Positive modulation of thermogenic and electron transport chain genes, reaching a 14.5-fold increase for Ucp1 in iWAT. RNA-seq revealed activation of the insulin signaling pathways for iBAT and oxidative phosphorylation, tricarboxylic acid cycle, and browning pathways for iWAT. B1R deficiency induced metabolic and gene expression alterations in adipose tissue, activating thermogenic pathways and increasing energy metabolism. B1R antagonists emerge as promising therapeutic targets for regulating obesity and associated metabolic disorders, such as inflammation and diabetes.

Branquinho J ，Neves RL ，Martin RP ，Arata JG ，Bittencourt CA ，Araújo RC ，Icimoto MY ，Pesquero JB ... -  《-》

Interscapular brown adipose tissue denervation does not promote the oxidative activity of inguinal white adipose tissue in male mice.

Labbé SM ，Caron A ，Festuccia WT ，Lecomte R ，Richard D ... -  《-》

Cold acclimation and pioglitazone combined increase thermogenic capacity of brown and white adipose tissues but this does not translate into higher energy expenditure in mice.

Valdivia LFG ，Castro É ，Eichler RADS ，Moreno MF ，de Sousa É ，Jardim GFR ，Peixoto ÁS ，Moraes MN ，Castrucci AML ，Nedergaard J ，Petrovic N ，Festuccia WT ，Reckziegel P ... -  《-》

Metabolic activity of brown, "beige," and white adipose tissues in response to chronic adrenergic stimulation in male mice.

Classical brown adipocytes such as those found in interscapular brown adipose tissue (iBAT) represent energy-burning cells, which have been postulated to play a pivotal role in energy metabolism. Brown adipocytes can also be found in white adipose tissue (WAT) depots [e.g., inguinal WAT (iWAT)] following adrenergic stimulation, and they have been referred to as "beige" adipocytes. Whether the presence of these adipocytes, which gives iWAT a beige appearance, can confer a white depot with some thermogenic activity remains to be seen. In consequence, we designed the present study to investigate the metabolic activity of iBAT, iWAT, and epididymal white depots in mice. Mice were either 1) kept at thermoneutrality (30°C), 2) kept at 30°C and treated daily for 14 days with an adrenergic agonist [CL-316,243 (CL)], or 3) housed at 10°C for 14 days. Metabolic activity was assessed using positron emission tomography imaging with fluoro-[(18)F]deoxyglucose (glucose uptake), fluoro-[(18)F]thiaheptadecanoic acid (fatty acid uptake), and [(11)C]acetate (oxidative activity). In each group, substrate uptakes and oxidative activity were measured in anesthetized mice in response to acute CL. Our results revealed iBAT as a major site of metabolic activity, which exhibited enhanced glucose and nonesterified fatty acid uptakes and oxidative activity in response to chronic cold and CL. On the other hand, beige adipose tissue failed to exhibit appreciable increase in oxidative activity in response to chronic cold and CL. Altogether, our results suggest that the contribution of beige fat to acute-CL-induced metabolic activity is low compared with that of iBAT, even after sustained adrenergic stimulation.

Labbé SM ，Caron A ，Chechi K ，Laplante M ，Lecomte R ，Richard D ... -  《-》

Liraglutide Activates Type 2 Deiodinase and Enhances β3-Adrenergic-Induced Thermogenesis in Mouse Adipose Tissue.

Liraglutide is a long-acting glucagon-like peptide 1 (GLP-1) receptor agonist used as an anti-hyperglycemic agent in type 2 diabetes treatment and recently approved for obesity management. Weight loss is attributed to appetite suppression, but therapy may also increase energy expenditure. To further investigate the effect of GLP-1 signaling in thermogenic fat, we assessed adipose tissue oxygen consumption and type 2 deiodinase (D2) activity in mice treated with liraglutide, both basally and after β3-adrenergic treatment. Male C57BL/6J mice were randomly assigned to receive liraglutide (400 μg/kg, n=12) or vehicle (n=12). After 16 days, mice in each group were co-treated with the selective β3-adrenergic agonist CL316,243 (1 mg/kg, n=6) or vehicle (n=6) for 5 days. Adipose tissue depots were assessed for gene and protein expression, oxygen consumption, and D2 activity. Liraglutide increased interscapular brown adipose tissue (iBAT) oxygen consumption and enhanced β3-adrenergic-induced oxygen consumption in iBAT and inguinal white adipose tissue (ingWAT). These effects were accompanied by upregulation of UCP-1 protein levels in iBAT and ingWAT. Notably, liraglutide increased D2 activity without significantly upregulating its mRNA levels in iBAT and exhibited additive effects to β3-adrenergic stimulation in inducing D2 activity in ingWAT. Liraglutide exhibits additive effects to those of β3-adrenergic stimulation in thermogenic fat and increases D2 activity in BAT, implying that it may activate this adipose tissue depot by increasing intracellular thyroid activation, adding to the currently known mechanisms of GLP-1A-induced weight loss.

Oliveira FCB ，Bauer EJ ，Ribeiro CM ，Pereira SA ，Beserra BTS ，Wajner SM ，Maia AL ，Neves FAR ，Coelho MS ，Amato AA ... -  《Frontiers in Endocrinology》