Weaning stress can cause tight junctions damage and intestinal permeability enhancement, which leads to intestinal imbalance and growth retardation, thereby causing damage to piglet growth and development. Spermine can reduce stress. However, the mechanism of spermine modulating the intestinal integrity in pigs remains largely unknown. This study aims to examine whether spermine protects the intestinal barrier integrity of piglets through ras-related C3 botulinum toxin substrate 1 (Rac1)/phospholipase C-γ1 (PLC-γ1) signaling pathway. In vivo, 80 piglets were categorised into 4 control groups and 4 spermine groups (10 piglets per group). The piglets were fed with normal saline or spermine at 0.4 mmol/kg BW for 7 h and 3, 6 and 9 d. In vitro, we investigated whether spermine protects the intestinal barrier after a tumor necrosis factor α (TNF-α) challenge through Rac1/PLC-γ1 signaling pathway. The in vivo study found that spermine supplementation increased tight junction protein mRNA levels and Rac1/PLC-γ1 signaling pathway gene expression in the jejunum of piglets. The serum D-lactate content was significantly decreased after spermine supplementation (P < 0.05). The in vitro study found that 0.1 μmol/L spermine increased the levels of tight junction protein expression, Rac1/PLC-γ1 signaling pathway and transepithelial electrical resistance, and decreased paracellular permeability (P < 0.05). Further experiments demonstrated that spermine supplementation enhanced the levels of tight junction protein expression, Rac1/PLC-γ1 signaling pathway and transepithelial electrical resistance, and decreased paracellular permeability compared with the NSC-23766 and U73122 treatment with spermine after TNF-α challenge (P < 0.05). Collectively, spermine protects intestinal barrier integrity through Rac1/PLC-γ1 signaling pathway in piglets.

断奶应激可引起紧密连接破坏和肠道通透性增强，从而导致肠道失衡和生长迟缓，从而对仔猪生长发育造成损害。精液可以减轻压力。然而，精胺调节猪肠道完整性的机制在很大程度上仍然未知。本研究旨在检测精胺是否通过ras相关的C3肉毒杆菌毒素底物1（Rac1）/磷脂酶C-γ1（PLC-γ1）信号通路保护仔猪肠道屏障的完整性。在体内，80头仔猪被分为4个对照组和4个精胺组（每组10头仔猪）。仔猪用生理盐水或精胺按 0.4 mmol/kg BW 喂养 7 小时和 3、6 和 9 天。体外，我们通过 Rac1/PLC-γ1 信号通路研究了在肿瘤坏死因子 α (TNF-α) 攻击后精胺是否保护肠道屏障。体内研究发现，补充精胺可增加仔猪空肠中紧密连接蛋白 mRNA 水平和 Rac1/PLC-γ1 信号通路基因表达。补充精胺后血清 D-乳酸含量显着降低（P  < 0.05)。体外研究发现0.1 μmol/L精胺增加紧密连接蛋白表达水平、Rac1/PLC-γ1信号通路和跨上皮电阻，降低细胞旁通透性（P  < 0.05）。进一步的实验表明，与 TNF-α 激发后用精胺处理的 NSC-23766 和 U73122 相比，补充精胺可增强紧密连接蛋白表达、Rac1/PLC-γ1 信号通路和跨上皮电阻的水平，并降低细胞旁通透性（P  < 0.05）。总的来说，精胺通过 Rac1/PLC-γ1 信号通路保护仔猪肠道屏障的完整性。