Amino acids stimulate cholecystokinin release through the Ca2+-sensing receptor
Amino acids stimulate cholecystokinin release through the Ca2+-sensing receptor
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DOI：
10.1152/ajpgi.00387.2010
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发表时间：
2011-04-01
影响因子：
4.5
通讯作者：
Liddle, Rodger A.
中科院分区：
文献类型：
--
作者：
Wang, Yu;Chandra, Rashmi;Liddle, Rodger A.
王勇，钱德拉R， Samsa LA, Gooch B, Fee BE, Cook JM, Vigna SR, Grant AO, Liddle RA。氨基酸通过Ca2+感应受体刺激胆囊收缩素释放。[J] .中国生物医学工程学报，2011,31(2):526 - 526。首次发表于2010年12月23日；doi: 10.1152 / ajpgi.00387.2010。胆囊收缩素（CCK）由小肠近端离散的内分泌细胞产生，并在摄入食物后释放。CCK是负责胆囊收缩的主要激素，对胰腺分泌、胃排空和饱腹感有强有力的影响。除脂肪外，消化的蛋白质和芳香氨基酸也是CCK释放的主要刺激物。然而，氨基酸影响CCK分泌的细胞机制尚不清楚。最初在甲状旁腺细胞上发现的Ca2+感应受体（CaSR）不仅对细胞外Ca2+敏感，而且被细胞外芳香氨基酸激活。据推测，该受体可能参与胃肠激素的分泌。利用表达CCK启动子驱动/增强型绿色荧光蛋白（GFP）转基因的转基因小鼠，我们已经能够鉴定和纯化活的肠道CCK细胞。通过荧光活化细胞分选，使肠粘膜CCK细胞富集bb100 ~ 200倍。然后将这些细胞用于实时PCR鉴定CaSR。CaSR特异性抗体的免疫组织化学染色证实了CaSR与CCK细胞的共定位。在负载Ca2+敏感染料的分离CCK细胞中，氨基酸苯丙氨酸和色氨酸，但非芳香氨基酸，引起细胞内Ca2+的增加（[Ca2+](i)）。[Ca2+](i)的增加被CaSR抑制剂Calhex 231阻断。苯丙氨酸和色氨酸刺激肠CCK细胞释放CCK，这种刺激也被CaSR抑制所阻断。从分离的CCK-GFP细胞的电生理记录显示，这些细胞具有主要的向外整流钾电流。苯丙氨酸抑制基础K+通道活性，引起CCK细胞去极化，这与激素分泌所必需的变化一致。这些发现表明氨基酸通过激活CaSR直接作用于CCK细胞刺激CCK释放，提示CaSR是氨基酸调控CCK分泌的生理机制。
Wang Y, Chandra R, Samsa LA, Gooch B, Fee BE, Cook JM, Vigna SR, Grant AO, Liddle RA. Amino acids stimulate cholecystokinin release through the Ca2+-sensing receptor. Am J Physiol Gastrointest Liver Physiol 300: G528-G537, 2011. First published December 23, 2010; doi: 10.1152/ajpgi.00387.2010.-Cholecystokinin (CCK) is produced by discrete endocrine cells in the proximal small intestine and is released following the ingestion of food. CCK is the primary hormone responsible for gallbladder contraction and has potent effects on pancreatic secretion, gastric emptying, and satiety. In addition to fats, digested proteins and aromatic amino acids are major stimulants of CCK release. However, the cellular mechanism by which amino acids affect CCK secretion is unknown. The Ca2+-sensing receptor (CaSR) that was originally identified on parathyroid cells is not only sensitive to extracellular Ca2+ but is activated by extracellular aromatic amino acids. It has been postulated that this receptor may be involved in gastrointestinal hormone secretion. Using transgenic mice expressing a CCK promoter driven/enhanced green fluorescent protein (GFP) transgene, we have been able to identify and purify viable intestinal CCK cells. Intestinal mucosal CCK cells were enriched > 200-fold by fluorescence-activated cell sorting. These cells were then used for real-time PCR identification of CaSR. Immunohistochemical staining with an antibody specific for CaSR confirmed colocalization of CaSR to CCK cells. In isolated CCK cells loaded with a Ca2+-sensitive dye, the amino acids phenylalanine and tryptophan, but not nonaromatic amino acids, caused an increase in intracellular Ca2+ ([Ca2+](i)). The increase in [Ca2+](i) was blocked by the CaSR inhibitor Calhex 231. Phenylalanine and tryptophan stimulated CCK release from intestinal CCK cells, and this stimulation was also blocked by CaSR inhibition. Electrophysiological recordings from isolated CCK-GFP cells revealed these cells to possess a predominant outwardly rectifying potassium current. Administration of phenylalanine inhibited basal K+ channel activity and caused CCK cell depolarization, consistent with changes necessary for hormone secretion. These findings indicate that amino acids have a direct effect on CCK cells to stimulate CCK release by activating CaSR and suggest that CaSR is the physiological mechanism through which amino acids regulate CCK secretion.