Piceatannol and resveratrol share inhibitory effects on hydrogen peroxide release, monoamine oxidase and lipogenic activities in adipose tissue, but differ in their antilipolytic properties

International audiencePiceatannol is a hydroxylated derivative of resveratrol. While both dietary polyphenols coexist in edible plants and fruits, and share equivalent concentrations in several wines, the influence of piceatannol on adiposity has been less studied than that of resveratrol. Though resveratrol is now recognized to limit fat deposition in various obesity models, the benefit of its dietary supplementation remains under debate regarding human obesity treatment or prevention. The research for more potent resveratrol analogs is therefore still undergoing. This prompted us to compare various effects of piceatannol and resveratrol directly on human adipose tissue (hAT). Hydrogen peroxide release was measured by Amplex Red-based fluorescence in subcutaneous hAT samples from obese patients. Interactions of stilbenes with human amine oxidases and quinone reductase were assessed by radiometric methods, computational docking and electron paramagnetic resonance. Influences on lipogenic and lipolytic activities were compared in mouse adipocytes. Resveratrol and piceatannol inhibited monoamine oxidase (MAO) with respective IC50 of 18.5 and 133.7 μM, but not semicarbazide-sensitive amine oxidase (SSAO) in hAT. For both stilbenes, the docking scores were better for MAO than for SSAO. Piceatannol and resveratrol similarly hampered hydrogen peroxide detection in assays with and without hAT, while they shared pro-oxidant activities when incubated with purified quinone reductase. They exhibited similar dose-dependent inhibition of adipocyte lipogenic activity. Only piceatannol inhibited basal and stimulated lipolysis when incubated at a dose ≥100 μM. Thus, piceatannol exerted on fat cells dose-dependent effects similar to those of resveratrol, except for a stronger antilipolytic action. In this regard, piceatannol should be useful in limiting the lipotoxicity related to obesity when ingested or administered alone - or might hamper the fat mobilization induced by resveratrol when simultaneously administered with it

Fabrication process for sub-8 nm HfZrO2-based ferroelectric tunnel junctions with enhanced properties

International audienceKeeping the miniaturisation pace in the modern semiconductor technology, while chasing an increased computing efficiency, has stimulated the research to focus on novel computing paradigms. One of these is neuromorphic engineering, which aims at the physical implementation of devices mimicking biological neuron and synapses. In this context, memristors based on ferroelectric material are promising candidates to implement synaptic functions. For instance ferroelectric tunnel junction (FTJ) memristors, based on HfZrO2 (HZO) have shown synaptic learning abilities [1]. In addition, HZO processes are already fully compatible with the CMOS industry, with oxide layers thinner than 10 nm. In this work we present a comparative study of different HZO-based FTJs. By interface engineering, we aimed at improving the structural and electrical performances of ultra-thin ferroelectric HZO films. The HZO was synthesized by magnetron sputtering from a Hf0.5Zr0.5O2 ceramic target and subsequently crystallized by rapid thermal annealing [2]. We compared the structural properties and the electrical performances of sub-8 nm HZO layers sandwiched between bottom and top electrodes made of titanium nitride or tungsten. Furthermore, we probed the effect on the ferroelectric properties of HZO of the insertion of an ultra-thin titanium layer at the electrode/HZO interface. The microstructure and the chemical properties of HZO were investigated by means of glancing incidence X-ray diffraction, transmission electron microscopy, and electron energy loss spectroscopy. Electrical characterization was conducted using the positive-up-negative-down-technique and by the acquisition of current vs voltage characteristics. We propose optimized stacks with enhanced ferroelectricity, which are considered for the implementation of FTJs, and for the demonstration of synaptic learning mechanisms for neuromorphic applications. References: [1] L. Chen et al. Nanoscale, vol. 10, no. 33, pp. 15826–15833, 2018. [2] J. Bouaziz, et al., ACS Applied Electronic Materials 1 (9), 1740-1745, 2019

Chronic apelin treatment improves hepatic lipid metabolism in obese and insulin-resistant mice by an indirect mechanism

International audienc

EPA induces in vivo and in vitro expression of the apelin/APJ system in muscle.

<p>(A) Apelin and (B) APJ mRNA expression in soleus muscle of ND (n = 7), HFD (n = 10) and HFD+EPA (n = 5). Results represent mean ±SEM **p<0.01, ***p<0.001, ns: not significant. (C) Apelin mRNA expression and (D) secretion in differentiated C2C12 cells treated with the indicated EPA concentrations or the corresponding BSA content for 24 hours after 12-hour serum deprivation. Data are mean ±SEM n = 4–5 in each condition. *p<0.05, **p<0.01 ***p<0.001. (E) Effect of 100 µM EPA in the absence or in the presence of the PI3K inhibitor LY294002 (20 µM) or the ERK 1/2 inhibitor U0126 (20 µM) for 24 h after 12-hour serum deprivation on apelin mRNA expression and (F) secretion in differentiated C2C12 cells. Results represent mean ±SEM (n = 4–5 in each condition) *p<0.05, **p<0.01, ns: not significant.</p

Plasma lipid composition.

<p>SFA (Saturated Fatty Acids), MUFAs (Mono-Unsaturated Fatty Acids) and PUFAs (Poly-Unsaturated Fatty Acids) were measured by gas-liquid chromatography in plasma of fasted mice after 10 weeks feeding with ND (black column, n = 6), HFD (white column, n = 12) or HFD+EPA (grey column, n = 9). Data are expressed as mean ±SEM. *p<0.05, **p<0.01, ***p<0.001 vs ND; # p<0.05, ## p<0.01, ### p<0.001 vs HFD. ns: not significant</p

Protective effect of EPA supplementation on the HFD-induced impaired glucose metabolism.

<p>(A) Glycemia and (B) insulinemia in 6 h-fasted mice fed a ND (n = 12), a HFD (n = 14) or a HFD+EPA (n = 14) after 10 weeks. Results represent mean ±SEM. ***p<0.001, (C) OGTT curves and area under the curve (AUC) of glycemia monitored during OGTT performed on 6 h fasted (during light period) mice after 9 weeks of diet in ND (n = 4), HFD (n = 6) and HFD+EPA (n = 6) mice. Results represent mean ±SEM. *p<0.05, **p<0.01, ***p<0.001 vs ND; and ## p<0.01, ### p<0.001 vs HFD.</p

Effect of EPA on adipokines and APJ mRNA expression in adipose tissue.

<p>(A) Leptin, (B) Adiponectin, (C) Apelin and (D) APJ expression in total adipose tissue of ND (n = 12), HFD (n = 14) and HFD+EPA mice (n = 14). Results represent mean ±SEM **p<0.01, ***p<0.001</p

Effect of EPA on muscle lipid metabolism.

<p>(A) Intramuscular triglycerides content in red gastrocnemius of ND (n = 9), HFD (n = 10) and HFD+EPA (n = 10) mice. (B) ¹⁴C-palmitate complete β-oxidation and mRNA expression of (C) CPT1b and (D) UCP3 in soleus muscle of ND (n = 9), HFD (n = 6–10) and HFD+EPA mice (n = 6–10). Results are mean ±SEM and were normalized to the ND group (100%) for B, C and D, *p<0.05, **p<0.01, ***p<0.001</p

Protective effect of EPA supplementation on the HFD-induced obesity.

<p>(A) Body weight in mice after 10-week feeding with a ND (n = 12), HFD (n = 14) or HFD+EPA(n = 14). Results represent mean ±SEM. *p<0.05, **p<0.01, ***p<0.001 vs ND; and ### p<0.001 vs HFD, ns: not significant. (B) fat and lean mass and (C) fat pads weights of subcutaneous (Subcut), perigonadal (Perigon) and mesenteric (Mes) adipose tissue in mice fed for 10 weeks with a ND or N (n = 12), HFD or H (n = 14) or HFD+EPA or E (n = 14) Results represent mean ±SEM. ***p<0.001, (D) Representative photographs of H&E staining of liver section of mice fed the different diets for 10 weeks (bar = 200 µm).</p