Identification of insulin-regulated aminopeptidase (IRAP) in the rat pineal gland and the modulation of melatonin synthesis by angiotensin IV
Identification of insulin-regulated aminopeptidase (IRAP) in the rat pineal gland and the modulation of melatonin synthesis by angiotensin IV
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DOI：
10.1016/j.brainres.2018.09.015
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发表时间：
2019-02-01
期刊：
影响因子：
2.9
通讯作者：
Afeche, Solange Castro
中科院分区：
文献类型：
--
作者：
Abrahao, Mariana Vieira;Teixeira dos Santos, Natalia Fernanda;Afeche, Solange Castro
松果体中存在局部肾素-血管紧张素系统（RAS）。除了血管紧张素 II (Ang II) 之外，还描述了其他活性代谢物。在本研究中，我们旨在研究 Ang IV 在褪黑激素合成中的作用以及松果体中其提议的 (IRAP)/AT(4) 受体（胰岛素调节氨肽酶）的存在。使用分离的松果体细胞在体外研究 Ang IV 对褪黑激素合成的影响。使用 Leu-4Me-β-萘酰胺作为底物，通过蛋白质印迹和荧光测定法评估 IRAP 蛋白表达和活性。通过 HPLC 分析褪黑激素，通过共聚焦显微镜分析钙含量，通过免疫测定分析 cAMP。Ang IV 显着增强 NE 诱导的褪黑激素合成，其程度与 Ang 所达到的水平相似。松果体细胞中的这种 Ang IV 效应似乎是由细胞内钙含量增加介导的，而不是由 cAMP 介导的。在松果体中鉴定了 (IRAP)/AT(4) 的表达和活性，其在膜部分中显着高于在可溶部分中。 Ang IV显着降低松果体膜部分中的IRAP活性。本研究的主要发现如下：（1）Ang IV增强松果体细胞中NE刺激的褪黑激素的产生，（2）大鼠松果体中存在（TRAP）/AT（4）受体，以及（3）Ang IV抑制IRAP活性并增加松果体细胞[Ca2+]（i）。我们得出结论，Ang IV是RAS的重要组成部分，并且调节大鼠松果体中褪黑激素的合成。
A local renin-angiotensin system (RAS) has been postulated in the pineal gland. In addition to angiotensin II (Ang II), other active metabolites have been described. In this study, we aimed to investigate a role for Ang IV in melatonin synthesis and the presence of its proposed (IRAP)/AT(4) receptor (insulin-regulated aminopeptidase) in the pineal gland.The effect of Ang IV on melatonin synthesis was investigated in vitro using isolated pinealocytes. IRAP protein expression and activity were evaluated by Western blot and fluorimetry using Leu-4Me-beta-naphthylamide as a substrate. Melatonin was analyzed by HPLC, calcium content by confocal microscopy and cAMP by immunoassay.Ang IV significantly augmented the NE-induced melatonin synthesis to a similar degree as that achieved by Ang This Ang IV effect in pinealocytes appears to be mediated by an increase in the intracellular calcium content but not by cAMP. The (IRAP)/AT(4) expression and activity were identified in the pineal gland, which were significantly higher in membrane fractions than in soluble fractions. Ang IV significantly reduced IRAP activity in the pineal membrane fractions.The main findings of the present study are as follows: (1) Ang IV potentiates NE-stimulated melatonin production in pinealocytes, (2) the (TRAP)/AT(4) receptor is present in the rat pineal gland, and (3) Ang IV inhibits IRAP activity and increases pinealocytes [Ca2+](i).We conclude that Ang IV is an important component of RAS and modulates melatonin synthesis in the rat pineal gland.