Expression of somatostatin receptor subtypes on guinea pig gastric and colonic smooth muscle cells.
Expression of somatostatin receptor subtypes on guinea pig gastric and colonic smooth muscle cells.
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DOI：
10.1152/ajpgi.1999.277.1.g235
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发表时间：
1999-07
期刊：
影响因子：
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通讯作者：
V. Corleto;H. Christian Weber;Robert T. Jensen
中科院分区：
文献类型：
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作者：
V. Corleto;H. Christian Weber;Robert T. Jensen
体内和体外研究表明，生长抑素可以影响胃和结肠的运动和平滑肌收缩。最近的研究表明，这些作用可能是由平滑肌细胞上的生长抑素受体直接介导的。如果这是正确的，sst受体亚型是未知的。本研究旨在解决这些问题。由于豚鼠sst基因的核苷酸序列是未知的，我们使用sst亚型特异性引物的基础上比较人类和大鼠sst亚型和进行RT-PCR的DNA酶I处理的总RNA从豚鼠全脑。将PCR产物克隆到pCR Ⅱ中并测序，与人sst基因的相同区域（跨膜4-6）的核苷酸同源性分别为87%（sst 1）、90%（sst 2）、90%（sst 3）、99%（sst 4）和80%（sst 5）。与大鼠序列的同源性较低。从分散的豚鼠胃和结肠平滑肌细胞的DNA酶I处理的RNA衍生的第一链cDNA获得PCR产物。在胃和结肠平滑肌细胞中，我们检测到sst 1-sst 3和sst 5，并通过测序证实。通过Southern印迹分析和与豚鼠Sst 4特异性引物的杂交显示Sst 4的存在。从培养的结肠和胃平滑肌细胞的RT-PCR没有任何神经元素给出了相同的结果。这些结果表明，在豚鼠中，所有五种sst亚型都直接存在于胃和结肠平滑肌细胞上。以前的研究表明，在胃和结肠肌细胞上主要的sst 3亚型和sst 5亚型介导生长抑素的收缩作用，但在这两种细胞上都存在所有五种sst亚型的发现表明，其他sst亚型只有很小的收缩作用或没有收缩作用，豚鼠sst亚型与大鼠或人sst具有不同的药理学特征，或者这些其他SST亚型在肌肉细胞中具有一些尚未描述的生理功能。
In vivo and in vitro studies have demonstrated that somatostatin can influence motility and smooth muscle contractility of the stomach and colon. Recent studies have proposed that some of these effects may be mediated by somatostatin receptors (sst) directly on the smooth muscle cells. If this is correct, the sst receptor subtypes that are present are unknown. This study aimed to resolve these points. Because nucleotide sequences of guinea pig sst genes are unknown, we used sst subtype-specific primers based on comparisons of human and rat sst subtypes and performed RT-PCR of DNase I-treated total RNA from guinea pig total brain. PCR products were cloned in pCR II and sequenced and showed 87% (sst1), 90% (sst2), 90% (sst3), 99% (sst4), and 80% (sst5), respectively, nucleotide homology to the same region (transmembrane 4-6) of the human sst genes. Homology to rat sequences were lower. PCR products were obtained from first-strand cDNA derived from DNase I-treated RNA from dispersed guinea pig gastric and colonic smooth muscle cells. In gastric and colonic smooth muscle cells, we detected sst1-sst3and sst5, and all were confirmed by sequencing. The presence of sst4 was shown by Southern blot analysis and hybridization with a guinea pig sst4-specific primer. RT-PCR from cultured colonic and gastric smooth muscle cells devoid of any neural elements gave identical results. These results demonstrate that in the guinea pig all five sst subtypes are present directly on gastric and colonic smooth muscle cells. Previous studies have suggested that a predominant sst3 subtype on gastric and a sst5 subtype on colonic muscle cells mediated somatostatin's contractile effects, but the finding here that all five sst subtypes exist on both of these cells suggests that other sst subtypes have only a small or no contractile effect, sst subtypes in guinea pig have a different pharmacological profile from rat or human sst, or these other sst subtypes have some yet undescribed physiological function in muscle cells.