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AgRP 神经元中的慢性 G 信号传递不会导致肥胖。

Chronic G signaling in AgRP neurons does not cause obesity.

机构信息

Department of Biochemistry, University of Washington, Seattle, WA 98195;

Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195.

出版信息

Proc Natl Acad Sci U S A. 2020 Aug 25;117(34):20874-20880. doi: 10.1073/pnas.2004941117. Epub 2020 Aug 6.

Abstract

Maintaining energy homeostasis requires coordinating physiology and behavior both on an acute timescale to adapt to rapid fluctuations in caloric intake and on a chronic timescale to regulate body composition. Hypothalamic agouti-related peptide (AgRP)-expressing neurons are acutely activated by caloric need, and this acute activation promotes increased food intake and decreased energy expenditure. On a longer timescale, AgRP neurons exhibit chronic hyperactivity under conditions of obesity and high dietary fat consumption, likely due to leptin resistance; however, the behavioral and metabolic effects of chronic AgRP neuronal hyperactivity remain unexplored. Here, we use chemogenetics to manipulate G signaling in AgRP neurons in mice to explore the hypothesis that chronic activation of AgRP neurons promotes obesity. Inducing chronic G signaling in AgRP neurons initially increased food intake and caused dramatic weight gain, in agreement with published data; however, food intake returned to baseline levels within 1 wk, and body weight returned to baseline levels within 60 d. Additionally, we found that, when mice had elevated body weight due to chronic G signaling in AgRP neurons, energy expenditure was not altered but adiposity and lipid metabolism were both increased, even under caloric restriction. These findings reveal that the metabolic and behavioral effects of chronic G signaling in AgRP neurons are distinct from the previously reported effects of acute G signaling and also of leptin insensitivity.

摘要

维持能量平衡需要协调生理学和行为学,既要在急性时间尺度上适应热量摄入的快速波动,又要在慢性时间尺度上调节身体成分。下丘脑刺鼠相关肽 (AgRP) 表达神经元会被热量需求急性激活,这种急性激活促进了食物摄入的增加和能量消耗的减少。在更长的时间尺度上,AgRP 神经元在肥胖和高脂肪饮食摄入的情况下表现出慢性过度活跃,这可能是由于瘦素抵抗所致;然而,慢性 AgRP 神经元过度活跃的行为和代谢效应仍未得到探索。在这里,我们使用化学遗传学方法来操纵小鼠 AgRP 神经元中的 G 信号,以探索慢性激活 AgRP 神经元会促进肥胖的假设。在 AgRP 神经元中诱导慢性 G 信号最初会增加食物摄入并导致体重明显增加,这与已发表的数据一致;然而,在 1 周内,食物摄入量恢复到基线水平,体重在 60 天内恢复到基线水平。此外,我们发现,当由于 AgRP 神经元中的慢性 G 信号导致小鼠体重增加时,能量消耗没有改变,但肥胖和脂质代谢都增加了,即使在热量限制下也是如此。这些发现表明,AgRP 神经元中慢性 G 信号的代谢和行为效应与之前报道的急性 G 信号和瘦素不敏感的效应不同。

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