Kisspeptin-10 Facilitates a Plasma Membrane-Driven Calcium Oscillator in Gonadotropin-Releasing Hormone-1 Neurons
Kisspeptin-10 Facilitates a Plasma Membrane-Driven Calcium Oscillator in Gonadotropin-Releasing Hormone-1 Neurons
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DOI：
10.1210/en.2008-0979
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发表时间：
2009-03-01
期刊：
影响因子：
4.8
通讯作者：
Wray, Susan
中科院分区：
文献类型：
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作者：
Constantin, Stephanie;Caligioni, Claudia Simone;Wray, Susan
Kisspeptins是G蛋白偶联受体（GPR）-54的天然配体，是GnRH-1分泌的最有效刺激物，因此对生殖功能至关重要。然而，kisspeptins增强钙调节神经肽分泌的机制尚不清楚。在本研究中，我们使用GnRH-1神经元保持在小鼠鼻外植体检查GPR 54的表达和信号转导。在基础条件下，GnRH-1细胞表现出细胞内钙离子浓度（[Ca 2 +]（i））的自发基线振荡，这严重依赖于电压门控的河豚毒素（TTX）敏感性钠通道的操作，并且不与细胞内池的钙释放偶联。通过kisspeptin-10激活天然GPR 54引发了[Ca 2 +]（i）静止GnRH-1细胞中的振荡，增加了振荡细胞中钙尖峰的频率，导致单个尖峰在活性细胞亚群中叠加成平台爆发型钙信号。这些变化主要反映了GPR 54激活通过该受体与磷脂酶C信号通路偶联对质膜振荡器活性的刺激作用。这一途径的两个组分，肌醇1，3，4-三磷酸和蛋白激酶C，有助于受体介导的基线[Ca 2 +]（i）振荡的调节。TTX和2-氨基乙基二苯硼酸酯一起消除激动剂诱导的[Ca 2 +]（i）升高，几乎在所有细胞中，而氟灭酸效果较差。总之，这些结果表明，质膜钙振荡器是自发地在大多数产前GnRH-1神经元和促进kisspeptin-10通过磷脂酰肌醇二磷酸水解和去极化的神经元，通过激活TTX敏感的钠通道和非选择性阳离子通道。（内分泌学150：1400-1412，2009）
Kisspeptins, the natural ligands of the G-protein-coupled receptor (GPR)-54, are the most potent stimulators of GnRH-1 secretion and as such are critical to reproductive function. However, the mechanism by which kisspeptins enhance calcium-regulated neuropeptide secretion is not clear. In the present study, we used GnRH-1 neurons maintained in mice nasal explants to examine the expression and signaling of GPR54. Under basal conditions, GnRH-1 cells exhibited spontaneous baseline oscillations in intracellular calcium concentration ([Ca2+](i)), which were critically dependent on the operation of voltage-gated, tetrodotoxin (TTX)-sensitive sodium channels and were not coupled to calcium release from intracellular pools. Activation of native GPR54 by kisspeptin-10 initiated [Ca2+](i) oscillations in quiescent GnRH-1 cells, increased the frequency of calcium spiking in oscillating cells that led to summation of individual spikes into plateau-bursting type of calcium signals in a subset of active cells. These changes predominantly reflected the stimulatory effect of GPR54 activation on the plasma membrane oscillator activity via coupling of this receptor to phospholipase C signaling pathways. Both components of this pathway, inositol 1,3,4-trisphosphate and protein kinase C, contributed to the receptor-mediated modulation of baseline [Ca2+](i) oscillations. TTX and 2-aminoethyl diphenylborinate together abolished agonist-induced elevation in [Ca2+](i) in almost all cells, whereas flufenamic acid was less effective. Together these results indicate that a plasma membrane calcium oscillator is spontaneously operative in the majority of prenatal GnRH-1 neurons and is facilitated by kisspeptin-10 through phosphatidyl inositol diphosphate hydrolysis and depolarization of neurons by activating TTX-sensitive sodium channels and nonselective cationic channels. (Endocrinology 150: 1400-1412, 2009)