Department of Anatomy, Shiga University of Medical Science, Otsu, Shiga, Japan.
Am J Physiol Gastrointest Liver Physiol. 2009 Nov;297(5):G974-80. doi: 10.1152/ajpgi.00147.2009.
Acyl ghrelin has a 28-amino acid sequence with O-n-octanoyl acid modification at the serine 3 position, whereas des-acyl ghrelin has no octanoyl acid modification. Although these peptides exert different physiological functions, no previous studies have shown the different localization of acyl ghrelin and des-acyl ghrelin in the stomach. Here we have developed an antibody specific for des-acyl ghrelin that does not crossreact with acyl ghrelin. Both acyl ghrelin- and des-acyl ghrelin-immunoreactive cells were distributed in the oxyntic and antral mucosa of the rat stomach, with higher density in the antral mucosa than oxyntic mucosa. Immunofluorescence double staining showed that acyl ghrelin- and des-acyl ghrelin-positive reactions overlapped in closed-type round cells, whereas des-acyl ghrelin-positive reaction was found in open-type cells in which acyl ghrelin was negative. Acyl ghrelin-/des-acyl ghrelin-positive closed-type cells contain obestatin; on the other hand, des-acyl ghrelin-positive open-type cells contain somatostatin. We measured the release of acyl ghrelin and des-acyl ghrelin in vascularly perfused rat stomach by ELISA, and the effects of different intragastric pH levels on the release of each peptide were examined. The release of des-acyl ghrelin from the perfused stomach was greater at pH 2 than at pH 4; however, the release of acyl ghrelin was not affected by intragastric pH. The present study demonstrated the differential localization of acyl ghrelin and des-acyl ghrelin in the rat stomach and their different responses to the intragastric pH.
酰基 ghrelin 具有 28 个氨基酸序列，在丝氨酸 3 位带有 O-辛酰酸修饰，而去酰基 ghrelin 则没有辛酰酸修饰。虽然这些肽具有不同的生理功能，但以前的研究并未显示胃中酰基 ghrelin 和去酰基 ghrelin 的不同定位。在这里，我们开发了一种针对去酰基 ghrelin 的特异性抗体，该抗体不会与酰基 ghrelin 发生交叉反应。酰基 ghrelin 和去酰基 ghrelin 免疫反应细胞均分布在大鼠胃的胃底和胃窦黏膜中，胃窦黏膜中的密度高于胃底黏膜。免疫荧光双重染色显示，酰基 ghrelin 和去酰基 ghrelin 阳性反应在封闭型圆形细胞中重叠，而在开放型细胞中仅发现去酰基 ghrelin 阳性反应，而酰基 ghrelin 为阴性。酰基 ghrelin/去酰基 ghrelin 阳性的封闭型细胞含有 obestatin；另一方面，去酰基 ghrelin 阳性的开放型细胞含有生长抑素。我们通过 ELISA 测量了血管灌注大鼠胃中酰基 ghrelin 和去酰基 ghrelin 的释放，并检查了不同胃内 pH 值水平对每种肽释放的影响。在 pH 2 时，从灌注胃中释放的去酰基 ghrelin 大于 pH 4 时；然而，胃内 pH 值对酰基 ghrelin 的释放没有影响。本研究表明，酰基 ghrelin 和去酰基 ghrelin 在大鼠胃中的定位不同，并且对胃内 pH 值的反应也不同。
