Mammals in northern regions chronically suffer from low temperatures during autumn-winter seasons. The aim of this study was to investigate the response of intestinal amino acid transport and the amino acid pool in muscle to chronic cold exposure via Min pig models (cold adaptation) and Yorkshire pig models (non-cold adaptation). Furthermore, this study explored the beneficial effects of glucose supplementation on small intestinal amino acid transport and amino acid pool in muscle of cold-exposed Yorkshire pigs. Min pigs (Exp. 1) and Yorkshire pigs (Exp. 2) were divided into a control group (17 °C, n = 6) and chronic cold exposure group (7 °C, n = 6), respectively. Twelve Yorkshire pigs (Exp. 3) were divided into a cold control group and cold glucose supplementation group (8 °C). The results showed that chronic cold exposure inhibited peptide transporter protein 1 (PepT1) and excitatory amino acid transporter 3 (EAAT3) expression in ileal mucosa and cationic amino acid transporter-1 (CAT-1) in the jejunal mucosa of Yorkshire pigs (P < 0.05). In contrast, CAT-1, PepT1 and EAAT3 expression was enhanced in the duodenal mucosa of Min pigs (P < 0.05). Branched amino acids (BCAA) in the muscle of Yorkshire pigs were consumed by chronic cold exposure, accompanied by increased muscle RING-finger protein-1 (MuRF1) and muscle atrophy F-box (atrogin-1) expression (P < 0.05). More importantly, reduced concentrations of dystrophin were detected in the muscle of Yorkshire pigs (P < 0.05). However, glycine concentration in the muscle of Min pigs was raised (P < 0.05). In the absence of interaction between chronic cold exposure and glucose supplementation, glucose supplementation improved CAT-1 expression in the jejunal mucosa and PepT1 expression in the ileal mucosa of cold-exposed Yorkshire pigs (P < 0.05). It also improved BCAA and inhibited MuRF1 and atrogin-1 expression in muscle (P < 0.05). Moreover, dystrophin concentration was improved by glucose supplementation (P < 0.05). In summary, chronic cold exposure inhibits amino acid absorption in the small intestine, depletes BCAA and promotes protein degradation in muscle. Glucose supplementation ameliorates the negative effects of chronic cold exposure on amino acid transport and the amino acid pool in muscle.

北方地区的哺乳动物在秋冬季节长期遭受低温之苦。本研究的目的是通过 Min 猪模型（冷适应）和 Yorkshire 猪模型（非冷适应）研究肠道氨基酸转运和肌肉中的氨基酸库对慢性冷暴露的反应。此外，本研究探讨了葡萄糖补充剂对冷暴露约克夏猪肌肉中小肠氨基酸转运和氨基酸库的有益影响。Min 猪 (Exp. 1) 和 Yorkshire 猪 (Exp. 2) 分为对照组 (17 °C, n  = 6) 和慢性冷暴露组 (7 °C, n = 6），分别。12 只约克夏猪 (Exp. 3) 分为冷对照组和冷葡萄糖补充组 (8 °C)。结果表明，慢性冷暴露抑制约克夏猪回肠黏膜肽转运蛋白 1（PepT1）和兴奋性氨基酸转运蛋白 3（EAAT3）以及空肠黏膜阳离子氨基酸转运蛋白 1（CAT-1）的表达（P  < 0.05）。相反，CAT-1、PepT1 和 EAAT3 在闽猪十二指肠黏膜中的表达增强（P  < 0.05）。约克夏猪肌肉中的支链氨基酸 (BCAA) 因长期寒冷暴露而被消耗，同时肌肉 RING-finger-protein-1 (MuRF1) 和肌肉萎缩 F-box (atrogin-1) 表达增加（P < 0.05)。更重要的是，在约克夏猪的肌肉中检测到抗肌萎缩蛋白浓度降低 ( P  < 0.05)。但闽猪肌肉中甘氨酸浓度升高（P  < 0.05）。在慢性冷暴露和葡萄糖补充之间没有相互作用的情况下，葡萄糖补充改善了冷暴露约克夏猪空肠粘膜中的 CAT-1 表达和回肠粘膜中的 PepT1 表达（ P < 0.05 ）  。它还能改善 BCAA，抑制肌肉中 MuRF1 和 atrogin-1 的表达（P  < 0.05）。此外，抗肌萎缩蛋白浓度通过补充葡萄糖得到改善（P < 0.05)。总之，长期寒冷会抑制小肠中氨基酸的吸收，消耗 BCAA 并促进肌肉中的蛋白质降解。葡萄糖补充剂可改善长期寒冷暴露对氨基酸转运和肌肉中氨基酸库的负面影响。