Objective Development of brown-like/beige adipocytes in white adipose tissue (WAT) helps to reduce obesity. Thus, we investigated the effects of resveratrol, a dietary polyphenol capable of preventing obesity and related complications in humans and animal models, on brown-like adipocyte formation in inguinal WAT (iWAT). Methods CD1 female mice (5-month-old) were fed a high-fat diet with/without 0.1% resveratrol. In addition, primary stromal vascular cells separated from iWAT were subjected to resveratrol treatment. Markers of brown-like (beige) adipogenesis were measured and the involvement of AMP-activated protein kinase (AMPK) α1 was assessed using conditional knockout. Results Resveratrol significantly increased mRNA and/or protein expression of brown adipocyte markers including uncoupling protein 1 (UCP1), PR domain-containing 16 (PRDM16), Cell death-inducing DFFA-like effector A (Cidea), elongation of very long chain fatty acids protein 3 (Elovl3), peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α), cytochrome C and pyruvate dehydrogenase (PDH) in differentiated iWAT stromal vascular cells (SVC), suggesting that resveratrol induced brown-like adipocyte formation in vitro. Concomitantly, resveratrol markedly enhanced AMPKα1 phosphorylation and differentiated SVC oxygen consumption. Such changes were absent in cells lacking AMPKα1, showing that AMPKα1 is a critical mediator of resveratrol action. Resveratrol also induced beige adipogenesis in vivo along with the appearance of multiocular adipocytes, increased UCP1 expression and enhanced fatty acid oxidation. Conclusion Resveratrol induces brown-like adipocyte formation in iWAT via AMPKα1 activation and suggest that its beneficial anti-obesity effects may be partly due to the browning of WAT and as a consequence, increased oxygen consumption.

SUMMARY Promoting brown adipose tissue (BAT) development is an attractive strategy for the treatment of obesity, as activated BAT dissipates energy through thermogenesis; however, the mechanisms controlling BAT formation are not fully understood. We hypothesized that as a master regulator of energy metabolism, AMP-activated protein kinase (AMPK) may play a direct role in the process and found that AMPKα1 (PRKAA1) ablation reduced Prdm16 expression and impaired BAT development. During early brown adipogenesis, the cellular levels of α-ketoglutarate (α-KG), a key metabolite required for TET-mediated DNA demethylation, were profoundly increased and required for active DNA demethylation of the Prdm16 promoter. AMPKα1 ablation reduced isocitrate dehydrogenase 2 activity and cellular α-KG levels. Remarkably, postnatal AMPK activation with AICAR or metformin rescued obesity-induced suppression of brown adipogenesis and thermogenesis. In summary, AMPK is essential for the epigenetic control of BAT development through α-ketoglutarate, thus linking a metabolite to progenitor cell differentiation and thermogenesis.

SUMMARY1. The kinetic properties of the main conductance state of y-aminobutyric acidA (GABA) receptor channels from somata of mouse spinal cord neurones in cell culture were investigated using patch clamp techniques.2. Whole-cell GABA receptor currents increased in a concentration-dependent manner from 0 5 to 5 /tM. R. L. MACDONALD, C. J. ROGERS AND R. E. TWYMAN suggesting that there was a population of single openings of short duration. The two longest burst time constants were longer than the two longest open time constants, suggesting that the bursts from the two longest burst components were composed of two or more openings.8. From these data we conclude that the main conductance of the GABA receptor channel has at least three open and two closed states whose time constants are concentration independent. The channel opens into a single-opening burst and into two complex bursts consisting of multiple openings. Single-opening bursts may be composed primarily of openings to the 01 state while complex bursts may be composed primarily of openings to the 02 and 03 states.9. We present a preliminary model for the gating of the main conductance of the GABA receptor channel.