Wouters Mira M, Gibbons Simon J, Roeder Jaime L, Distad Marne, Ou Yijun, Strege Peter R, Szurszewski Joseph H, Farrugia Gianrico
Enteric Neuroscience Program, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
Gastroenterology. 2007 Sep;133(3):897-906. doi: 10.1053/j.gastro.2007.06.017. Epub 2007 Jun 20.
BACKGROUND & AIMS: Interstitial cells of Cajal (ICC) are required for normal gastrointestinal motility. Loss of ICC is associated with several motility disorders. The mechanisms modulating ICC survival and proliferation are poorly understood. This study aimed to establish whether 5-hydroxytryptamine (5-HT) plays a role in regulating ICC proliferation.
Expression of 5-HT receptor mRNA was investigated in muscle strips, in purified populations of ICC, and in identified single cells. The effect of 5-HT(2B) receptor ligands on ICC numbers was studied in primary cell cultures. Proliferation of ICC was determined by counting Ki67-positive cells in culture.
Of the 5-HT receptors known to be involved in proliferation, 5-HT(2B) receptor mRNA was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in jejunal muscle, whereas 5-HT(1A), 5-HT(1D), and 5-HT(2C) receptor mRNAs were not. 5-HT(2B) receptor mRNA was found in single ICC and cells purified by flow cytometry. Exogenous 5-HT (1 micromol/L) increased (66% +/- 9%, P < .005) ICC numbers in culture. The 5-HT(2) receptor antagonist, ritanserin, and the 5-HT(2B) receptor antagonist, SB204741, inhibited the effect of 5-HT. The 5-HT(2B) receptor agonist BW 723C86 induced a concentration-dependent increase in ICC number (50% +/- 6% at 50 nM, P < .04) and increased ICC proliferation (25% +/- 3% vs 19 +/- 1% in controls, P < .03).
These studies establish that 5-HT(2B) receptors are expressed on ICC. Exogenous 5-HT regulates ICC numbers through 5-HT(2B) receptors in part by increasing ICC proliferation. The 5-HT(2B) receptor may serve as a novel pathway to regulate ICC numbers.
Cajal间质细胞（ICC）是正常胃肠动力所必需的。ICC的缺失与多种动力障碍有关。调节ICC存活和增殖的机制尚不清楚。本研究旨在确定5-羟色胺（5-HT）是否在调节ICC增殖中起作用。
在肌条、纯化的ICC群体和已鉴定的单细胞中研究5-HT受体mRNA的表达。在原代细胞培养中研究5-HT(2B)受体配体对ICC数量的影响。通过计数培养物中Ki67阳性细胞来确定ICC的增殖。
在已知参与增殖的5-HT受体中，通过逆转录聚合酶链反应（RT-PCR）在空肠肌中检测到5-HT(2B)受体mRNA，而未检测到5-HT(1A)、5-HT(1D)和5-HT(2C)受体mRNA。在单个ICC和通过流式细胞术纯化的细胞中发现了5-HT(2B)受体mRNA。外源性5-HT（1 μmol/L）增加了培养物中ICC的数量（66%±9%，P<.005）。5-HT(2)受体拮抗剂利坦色林和5-HT(2B)受体拮抗剂SB204741抑制了5-HT的作用。5-HT(2B)受体激动剂BW 723C86诱导ICC数量呈浓度依赖性增加（50 nM时为50%±6%，P<.04），并增加了ICC的增殖（与对照组的19±1%相比为25%±3%，P<.03）。
这些研究表明5-HT(2B)受体在ICC上表达。外源性5-HT部分通过增加ICC增殖，经由5-HT(2B)受体调节ICC数量。5-HT(2B)受体可能是调节ICC数量的一条新途径。
