Lipolysis drives expression of the constitutively active receptor GPR3 to induce adipose thermogenesis

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温度和高脂食物对黑线仓鼠代谢产热和体脂累积的影响

能量代谢的适应性调节是小型哺乳动物应对环境季节性变化的主要策略之一。为探讨不同温度下动物在代谢产热能量支出与脂肪累积之间的权衡策略,以成年雄性黑线仓鼠为研究对象开展了3 个实验:实验1 将动物驯化于高脂和低脂食物;实验2 将动物暴露于低温(5℃)和暖温(30℃);实验3 将饲喂高脂食物的动物暴露于低温。以食物平衡法测定摄食量、摄入能和消化率,以开放式氧气分析仪测定代谢产热,以索氏抽提法测定脂肪含量。结果发现,取食高脂食物的黑线仓鼠摄食量显著减少,但脂肪累积显著增加;暖温下摄食量显著减少,但体脂含量显著增加,低温下摄食量显著升高,但体脂含量显著减少;饲喂高脂食物的黑线仓鼠在低温下摄入能显著增加,非颤抖性产热增强,但体脂含量显著降低。结果表明高脂食物对黑线仓鼠体脂累积的影响与环境温度有关,低温诱导脂肪动员,暖温促进脂肪贮存;低温下黑线仓鼠增加能量摄入不能完全补偿用于产热的能量支出,导致脂肪动员增加;暖温下代谢产热降低是脂肪累积的主要因素;与能量摄入相比代谢产热的能量支出在体脂累积的适应性变化中发挥更重要的作用。     

Food-derived regulatory factors against obesity and metabolic syndrome

Abstract

Obesity is a key factor in metabolic syndrome. The study of metabolic syndrome focuses on the anti-weight gain properties of physiological mechanisms and food components. Abnormal energy metabolism is a major risk factor of metabolic syndrome. Chronic inflammation is a feature of obesity; cytokines from hypertrophied adipocytes cause inflammation in both adipose tissue and blood vessels, resulting in symptoms of metabolic syndrome. Tumor necrosis factor-α causes insulin resistance in adipocytes and regression of brown adipocytes, resulting in abnormal energy metabolism. Functional foods can serve as a strategy for prevention and treatment of obesity linked with metabolic processes in white and brown adipose tissues. Diet-induced thermogenesis caused by certain food components stimulates burning of stored fat within adipose tissues. A mechanistic understanding of dietary thermogenesis via the sympathetic nerve system will prove valuable for the development of precise strategies for the practical prevention of metabolic syndrome.     

Diversity of pollination ecology in the Schismatoglottis Calyptrata Complex Clade (Araceae)

• Field studies integrating pollination investigations with an assessment of floral scent composition and thermogenesis in tropical aroids are rather few. Thus, this study aimed to investigate the pollination biology of nine species belonging to Schismatoglottis Calyptrata Complex Clade. The flowering mechanism, visiting insect activities, reproductive system, thermogenesis and floral scent composition were examined.
• Anthesis for all species started at dawn and lasted 25–29 h. Colocasiomyia (Diptera, Drosophilidae) are considered the main pollinators for all the investigated species. Cycreon (Coleoptera, Hydrophilidae) are considered secondary pollinators as they are only present in seven of the nine host plants, despite the fact that they are the most effective pollen carrier, carrying up to 15 times more pollen grains than Colocasiomyia flies. However, the number of Colocasiomyia individuals was six times higher than Cycreon beetles. Chaloenus (Chrysomelidae, Galeuricinae) appeared to be an inadvertent pollinator. Atheta (Coleoptera, Staphylinidae) is considered a floral visitor in most investigated species of the Calyptrata Complex Clade in Sarawak, but a possible pollinator in S. muluensis. Chironomidae midges and pteromalid wasps are considered visitors in S. calyptrata.
• Thermogenesis in a biphasic pattern was observed in inflorescences of S. adducta, S. calyptrata, S. giamensis, S. pseudoniahensis and S. roh. The first peak occurred during pistillate anthesis; the second peak during staminate anthesis. Inflorescences of all investigated species of Calyptrata Complex Clade emitted four types of ester compound, with methyl ester‐3‐methyl‐3‐butenoic acid as a single major VOC (volatile organic compound). The appendix, pistillate zone, staminate zone and spathe emitted all these compounds.
• A mixed fly–beetle pollination system is considered an ancestral trait in the Calyptrata Complex Clade, persisting in Sarawak taxa, whereas the marked reduction of interpistillar staminodes in taxa from Peninsular Malaysia and especially, Ambon, Indonesia, is probably linked to a shift in these taxa to a fly‐pollinated system.

     

Biology and pathological implications of brown adipose tissue: promises and caveats for the control of obesity and its associated complications

The discovery of metabolically active brown adipose tissue (BAT) in adult humans has fuelled the research of diverse aspects of this previously neglected tissue. BAT is solely present in mammals and its clearest physiological role is non‐shivering thermogenesis, owing to the capacity of brown adipocytes to dissipate metabolic energy as heat. Recently, a number of other possible functions have been proposed, including direct regulation of glucose and lipid homeostasis and the secretion of a number of factors with diverse regulatory actions. Herein, we review recent advances in general biological knowledge of BAT and discuss the possible implications of this tissue in human metabolic health. In particular, we confront the claimed thermogenic potential of BAT for human energy balance and body mass regulation, mostly based on animal studies, with the most recent quantifications of human BAT.     

ERRγ Preserves Brown Fat Innate Thermogenic Activity

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Increase in the Thermic Effect of Food in Women by Adrenergic Amines Extracted from Citrus Aurantium

Objective: To compare the thermic response to a meal between men and women of varied body composition and to determine whether adrenergic amines extracted from citrus aurantium (CA) induce an increase in metabolic rate and enhance the thermic response to the meal. Research Methods and Procedures: In 30 healthy weight‐stable subjects (17 women, 13 men; BMI: 20 to 42 kg/m²), body composition was determined by bioimpedance analysis followed by resting energy expenditure for 20 minutes, and the thermic effect of food (TEF) of a 1.7‐MJ, 30‐gram protein meal was determined intermittently for 300 minutes by indirect calorimetry. In a subset of 22 subjects, the TEFs of CA alone and when added to the same 1.7‐MJ meal were determined. Blood pressure and pulse before and throughout the studies and catecholamine excretion were determined. Results: TEF was significantly lower in women than men (152 ± 7 vs. 190 ± 12 kJ and 8.8 ± 0.4% vs. 11.0 ± 0.7% of meal), independently of age and magnitude of adiposity. The thermic response to CA alone was higher in men, but, when added to the meal, CA increased TEF only in women and to values no longer different from men. CA had no effect on blood pressure and pulse rate but increased epinephrine excretion by 2.4‐fold. Discussion: A 20% lower TEF in women suggests a diminished sympathetic nervous system response to meals, because with CA, TEF increased by 29% only in women. However, this acute response may not translate into a chronic effect or a clinically significant weight loss over time.     

Adaptive Thermogenesis in Mice Is Enhanced by Opsin 3-Dependent Adipocyte Light Sensing

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