Department of Animal Science, Iowa State University, Ames, Iowa, USA.
PLoS One. 2013 Aug 1;8(8):e70215. doi: 10.1371/journal.pone.0070215. Print 2013.
Excessive heat exposure reduces intestinal integrity and post-absorptive energetics that can inhibit wellbeing and be fatal. Therefore, our objectives were to examine how acute heat stress (HS) alters intestinal integrity and metabolism in growing pigs. Animals were exposed to either thermal neutral (TN, 21°C; 35-50% humidity; n=8) or HS conditions (35°C; 24-43% humidity; n=8) for 24 h. Compared to TN, rectal temperatures in HS pigs increased by 1.6°C and respiration rates by 2-fold (P<0.05). As expected, HS decreased feed intake by 53% (P<0.05) and body weight (P<0.05) compared to TN pigs. Ileum heat shock protein 70 expression increased (P<0.05), while intestinal integrity was compromised in the HS pigs (ileum and colon TER decreased; P<0.05). Furthermore, HS increased serum endotoxin concentrations (P=0.05). Intestinal permeability was accompanied by an increase in protein expression of myosin light chain kinase (P<0.05) and casein kinase II-α (P=0.06). Protein expression of tight junction (TJ) proteins in the ileum revealed claudin 3 and occludin expression to be increased overall due to HS (P<0.05), while there were no differences in claudin 1 expression. Intestinal glucose transport and blood glucose were elevated due to HS (P<0.05). This was supported by increased ileum Na(+)/K(+) ATPase activity in HS pigs. SGLT-1 protein expression was unaltered; however, HS increased ileal GLUT-2 protein expression (P=0.06). Altogether, these data indicate that HS reduce intestinal integrity and increase intestinal stress and glucose transport.
暴露在高温下会降低肠道的完整性和吸收后的能量代谢，从而影响健康甚至危及生命。因此，我们的目的是研究急性热应激（HS）如何改变生长猪的肠道完整性和代谢。动物分别在热中性（TN，21°C；35-50%湿度；n=8）或 HS 条件（35°C；24-43%湿度；n=8）下暴露 24 小时。与 TN 相比，HS 组猪的直肠温度升高 1.6°C，呼吸率增加 2 倍（P<0.05）。正如预期的那样，HS 组猪的采食量比 TN 组减少了 53%（P<0.05），体重也减轻了（P<0.05）。回肠热休克蛋白 70 的表达增加（P<0.05），而 HS 组猪的肠道完整性受损（回肠和结肠跨膜电阻降低；P<0.05）。此外，HS 增加了血清内毒素浓度（P=0.05）。肠道通透性增加伴随着肌球蛋白轻链激酶（P<0.05）和酪蛋白激酶 II-α（P=0.06）的蛋白表达增加。回肠紧密连接（TJ）蛋白的蛋白表达显示，由于 HS，claudin 3 和 occludin 的表达总体上增加（P<0.05），而 claudin 1 的表达没有差异。由于 HS，肠道葡萄糖转运和血糖升高（P<0.05）。这得到了 HS 组猪回肠钠/钾（Na+/K+）ATP 酶活性增加的支持。SGLT-1 蛋白表达不变；然而，HS 增加了回肠 GLUT-2 蛋白表达（P=0.06）。总的来说，这些数据表明 HS 降低了肠道完整性，增加了肠道应激和葡萄糖转运。
