Watanabe Kanako, Kanno Takeshi, Oshima Tadayuki, Miwa Hiroto, Tashiro Chikara, Nishizaki Tomoyuki
Department of Physiology, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya 663-8501, Japan.
J Gastroenterol. 2008;43(5):322-6. doi: 10.1007/s00535-008-2163-z. Epub 2008 Jul 1.
N-methyl-D-aspartate (NMDA) receptor is the major excitatory neurotransmitter receptor in the central nervous system. Recent evidence has pointed to expression of NMDA receptor in peripheral non-neuronal tissues and organs; however, little is known about the expression of the receptor in the stomach. The present study identified what types of NMDA receptor subunits are expressed in the rat stomach and examined whether vagotomy affects their expression.
To see the expression and distribution of the mRNAs and proteins for the NMDA receptor subunits, real-time reverse transcription-polymerase chain reaction, Western blotting, in situ hybridization, and immunohistochemistry were carried out on rat stomach with and without vagotomy.
Of the NMDA receptor subunits, NR1, NR2 (2A, 2B, 2C, 2D), and NR3 (3A, 3B), all NR subunit mRNAs except for the NR2B subunit mRNA were expressed in the intact rat stomach, with huge expression of NR2D mRNA. Expression of NR2D subunit mRNA and protein significantly increased after vagotomy. Increased expression was found in mucosal cells, the myenteric plexus, and the outer membrane of the stomach with vagotomy.
Vagotomy upregulates expression of the NR2D subunit in the stomach and therefore, the NR2D subunit may be implicated in gastric motility.
N-甲基-D-天冬氨酸（NMDA）受体是中枢神经系统主要的兴奋性神经递质受体。最近有证据表明NMDA受体在外周非神经组织和器官中表达；然而，关于该受体在胃中的表达情况知之甚少。本研究确定了大鼠胃中表达哪些类型的NMDA受体亚基，并检测了迷走神经切断术是否会影响其表达。
为观察NMDA受体亚基的mRNA和蛋白质的表达及分布，对有或无迷走神经切断术的大鼠胃进行实时逆转录-聚合酶链反应、蛋白质印迹法、原位杂交和免疫组织化学检测。
在NMDA受体亚基中，NR1、NR2（2A、2B、2C、2D）和NR3（3A、3B），除NR2B亚基mRNA外，所有NR亚基mRNA均在完整大鼠胃中表达，其中NR2D mRNA表达量巨大。迷走神经切断术后，NR2D亚基mRNA和蛋白质的表达显著增加。迷走神经切断术后，胃黏膜细胞、肌间神经丛和胃外膜中均发现表达增加。
迷走神经切断术上调胃中NR2D亚基的表达，因此，NR2D亚基可能与胃动力有关。
