The present study aimed to determine the primary sequence of ovine xenin and clarify the mRNA expression and peptide localization of xenin in the gastrointestinal tract in sheep. The colocalization of xenin and glucose-dependent insulinotropic polypeptide was also compared in the antrum and duodenum. Analysis of the nucleotide sequence of ovine xenin revealed a high degree (97.9%) of sequence homology of the sequence between sheep and cattle, and the amino acids sequence determined for ovine xenin coincided (100%) with that of other mammalian species. Real-time quantitative PCR for ovine xenin did not show regional difference in the mRNA expression ratio of xenin. In contrast to the real-time quantitative PCR results, anti-xenin positive cells were abundantly localized in the abomasal antrum (P < 0.01) and at a lesser amount in the duodenum, but no antixenin positive cells were observed in the other regions. Anti-xenin single-positive cells were in a majority in the abomasal antrum, whereas anti-xenin single-positive cells, and anti-GIP single-positive cells, and double-positive cells were even colocalized in the duodenum. These results suggest that abomasal antrum is a major source of xenin in the ovine gastrointestinal tract.

本研究旨在确定绵羊xenin的一级序列，阐明xenin在绵羊胃肠道中的mRNA表达和肽定位。还在胃窦和十二指肠中比较了 xenin 和葡萄糖依赖性促胰岛素多肽的共定位。绵羊Xenin的核苷酸序列分析表明，绵羊和牛之间的序列具有高度（97.9%）的序列同源性，所确定的绵羊Xenin的氨基酸序列与其他哺乳动物物种的氨基酸序列一致（100%）。绵羊 xenin 的实时定量 PCR 未显示 xenin mRNA 表达率的区域差异。与实时定量 PCR 结果相反，抗 xenin 阳性细胞大量位于皱胃窦（P< 0.01)，十二指肠数量较少，但在其他区域未观察到抗毒素阳性细胞。抗xenin单阳性细胞主要集中在真胃窦，而抗xenin单阳性细胞、抗GIP单阳性细胞和双阳性细胞甚至共定位于十二指肠。这些结果表明皱胃窦是羊胃肠道中异素的主要来源。