胰高血糖素样肽-1受体信号直接激活脑片中弓状核的促性腺激素释放激素神经元活动,但在负能量平衡期间不能挽救去卵巢小鼠的促黄体生成素抑制。

GLP-1R Signaling Directly Activates Arcuate Nucleus Kisspeptin Action in Brain Slices but Does not Rescue Luteinizing Hormone Inhibition in Ovariectomized Mice During Negative Energy Balance.

作者信息

Heppner Kristy M, Baquero Arian F, Bennett Camdin M, Lindsley Sarah R, Kirigiti Melissa A, Bennett Baylin, Bosch Martha A, Mercer Aaron J, Rønnekleiv Oline K, True Cadence, Grove Kevin L, Smith M Susan

机构信息

Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University , Beaverton, OR 97006.

Department of Physiology and Pharmacology, Oregon Health & Science University , Portland, OR, 97239.

出版信息

eNeuro. 2017 Jan 20;4(1). doi: 10.1523/ENEURO.0198-16.2016. eCollection 2017 Jan-Feb.

Abstract

Kisspeptin (Kiss1) neurons in the hypothalamic arcuate nucleus (ARC) are key components of the hypothalamic-pituitary-gonadal axis, as they regulate the basal pulsatile release of gonadotropin releasing hormone (GnRH). ARC Kiss1 action is dependent on energy status, and unmasking metabolic factors responsible for modulating ARC Kiss1 neurons is of great importance. One possible factor is glucagon-like peptide 1 (GLP-1), an anorexigenic neuropeptide produced by brainstem preproglucagon neurons. Because GLP fiber projections and the GLP-1 receptor (GLP-1R) are abundant in the ARC, we hypothesized that GLP-1R signaling could modulate ARC Kiss1 action. Using ovariectomized mice, we found that GLP-producing fibers come in close apposition with ARC Kiss1 neurons; these neurons also contain mRNA. Electrophysiological recordings revealed that liraglutide (a long-acting GLP-1R agonist) increased action potential firing and caused a direct membrane depolarization of ARC Kiss1 cells in brain slices. We determined that brainstem preproglucagon mRNA is decreased after a 48-h fast in mice, a negative energy state in which ARC Kiss1 expression and downstream GnRH/luteinizing hormone (LH) release are potently suppressed. However, activation of GLP-1R signaling in fasted mice with liraglutide was not sufficient to prevent LH inhibition. Furthermore, chronic central infusions of the GLP-1R antagonist, exendin(9-39), in -fed mice did not alter ARC mRNA or plasma LH. As a whole, these data identify a novel interaction of the GLP-1 system with ARC Kiss1 neurons but indicate that CNS GLP-1R signaling alone is not critical for the maintenance of LH during fasting or normal feeding.

摘要

下丘脑弓状核(ARC)中的 kisspeptin(Kiss1)神经元是下丘脑 - 垂体 - 性腺轴的关键组成部分,因为它们调节促性腺激素释放激素(GnRH)的基础脉冲式释放。ARC Kiss1 的作用取决于能量状态,揭示负责调节 ARC Kiss1 神经元的代谢因子非常重要。一种可能的因素是胰高血糖素样肽 1(GLP - 1),它是由脑干前胰高血糖素神经元产生的一种厌食性神经肽。由于 GLP 纤维投射和 GLP - 1 受体(GLP - 1R)在 ARC 中大量存在,我们推测 GLP - 1R 信号传导可能调节 ARC Kiss1 的作用。使用去卵巢小鼠,我们发现产生 GLP 的纤维与 ARC Kiss1 神经元紧密相邻;这些神经元也含有 mRNA。电生理记录显示,利拉鲁肽(一种长效 GLP - 1R 激动剂)增加动作电位发放,并导致脑片中 ARC Kiss1 细胞直接膜去极化。我们确定,小鼠禁食 48 小时后脑干前胰高血糖素 mRNA 减少,禁食是一种负能量状态,此时 ARC Kiss1 的表达以及下游 GnRH/黄体生成素(LH)的释放受到强烈抑制。然而,用利拉鲁肽激活禁食小鼠的 GLP - 1R 信号传导不足以防止 LH 受到抑制。此外,在进食小鼠中慢性中枢注射 GLP - 1R 拮抗剂艾塞那肽(9 - 39)并不会改变 ARC 的 mRNA 或血浆 LH。总体而言,这些数据确定了 GLP - 1 系统与 ARC Kiss1 神经元之间的一种新相互作用,但表明仅中枢神经系统 GLP - 1R 信号传导对于禁食或正常进食期间 LH 的维持并非至关重要。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/898b/5247618/1a45a6c08219/enu0011722130001.jpg

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