Institute of Dairy Science, MoE Key Laboratory of Molecular Animal Nutrition, College of Animal Sciences, Zhejiang University, Hangzhou, China.
College of Animal Sciences and Technology, Huazhong Agricultural University, Wuhan, China.
J Sci Food Agric. 2019 Jan 15;99(1):100-108. doi: 10.1002/jsfa.9148. Epub 2018 Jul 12.
Peptide absorption from the forestomach plays a vital role in protein nutrition of dairy cows. This study was conducted to investigate the mechanism of dipeptide absorption in the forestomach of dairy cows using isolated omasal epithelial cells (OECs) and ruminal epithelial cells (RECs).
Compared with RECs, the OECs formed a less tight monolayer, but had greater ability to transport glycylsarcosine (Gly-Sar) (P < 0.05). The OEC monolayers were immunopositive for the antibodies of anti-junction proteins. Gly-Sar transport was significantly greater at 37 °C than that at 4 °C, with an optimal pH of 6.0-6.5, and was decreased significantly by diethylpyrocarbonate and dipeptide Met-Gly (P < 0.05). The apical-to-basolateral transport was significantly greater than basolateral-to-apical transport (P < 0.05). Knockdown of peptide transporter 1 (PepT1) resulted in less Gly-Sar uptake in OECs, whereas overexpression of PepT1 in OECs resulted in higher Gly-Sar uptake (P < 0.05). Additionally, the expression of PepT1 was upregulated by the treatment with various dipeptides (P < 0.05).
The OECs have a greater ability to transport Gly-Sar than RECs do. Both passive and active routes are involved in the process of Gly-Sar absorption in the isolated cultured forestomach epithelial cells from dairy cows. © 2018 Society of Chemical Industry.
肽从瘤胃吸收在奶牛的蛋白质营养中起着至关重要的作用。本研究旨在使用分离的网胃上皮细胞（OEC）和瘤胃上皮细胞（REC）来研究奶牛网胃中二肽吸收的机制。
与 REC 相比，OEC 形成的单层更不紧密，但具有更大的甘氨酰肌氨酸（Gly-Sar）转运能力（P<0.05）。OEC 单层对抗连接蛋白抗体呈免疫阳性。Gly-Sar 转运在 37°C 时显著高于 4°C，最佳 pH 值为 6.0-6.5，二乙基焦碳酸盐和二肽 Met-Gly 显著降低（P<0.05）。顶侧至基底外侧的转运明显大于基底外侧至顶侧的转运（P<0.05）。肽转运蛋白 1（PepT1）的敲低导致 OEC 中 Gly-Sar 的摄取减少，而 OEC 中 PepT1 的过表达导致 Gly-Sar 的摄取增加（P<0.05）。此外，用各种二肽处理可上调 PepT1 的表达（P<0.05）。
OEC 比 REC 具有更强的转运 Gly-Sar 的能力。在从奶牛分离培养的网胃上皮细胞中，Gly-Sar 的吸收涉及被动和主动途径。 © 2018 化学工业协会。
