Xin Hairui, Zhang Xiaojun, Sun Dengsheng, Zhang Chuang, Hao Yue, Gu Xianhong
State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, No.2 Yuanmingyuan West Road, Haidian District, 100193 Beijing, China.
State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, No.2 Yuanmingyuan West Road, Haidian District, 100193 Beijing, China.
J Therm Biol. 2018 Oct;77:122-130. doi: 10.1016/j.jtherbio.2018.08.008. Epub 2018 Aug 18.
The insulin-like activity of insulin-like growth factor-1 (IGF-1) is heavily blunted by IGF binding proteins (IGFBPs, including IGFBP-1 and IGFBP-3). The effects of heat stress (HS) on the IGF-1 and IGFBPs in growing pigs are still not clear. This study aimed to investigate the alterations of IGF-1 and IGFBPs under chronic HS in growing pigs. Twenty-seven growing large white barrows with similar body weight were collected from nine litters and were assigned into three treatments. The litter effect is balanced in all treatments. Treatments were: 1) thermal-neutral (TN) group (23 °C), 2) chronic HS group (33 °C), and 3) pair-fed in TN condition (PFTN). The experiment lasted for 21 days. Compared with TN controls, decreased FI, lower average body weight gain, higher rectal temperature and increased respiration rates were observed in HS pigs. On D7, increased plasma insulin concentration and insulin:glucose ratio were observed in HS pigs compared to TN controls. A overall elevation of plasma IGF-1:IGFBP-3 ratio was detected in HS pigs compared with PFTN and TN counterparts. Besides, hepatic IGF-1 gene expression of HS pigs was 50% higher than TN counterparts. PFTN pigs, however, had no differences in plasma IGF-1:IGFBP-3 ratio and hepatic IGF-1 gene expression, compared with TN pigs. PFTN pigs increased plasma IGFBPs concentration and hepatic IGFBPs gene expression, compared with TN controls. However, no differences in plasma IGFBPs concentration and hepatic IGFBPs gene expression were observed between TN and HS group. Liver IRS-1 gene and protein expressions of HS pigs tended to be increased compared with TN controls, while PFTN pigs still kept liver IRS-1 gene and protein expressions in normal level. High temperature (33 °C), independent of feed intake reduction, increased IGF-1 but did not affect IGFBPs levels in growing pigs.
胰岛素样生长因子-1（IGF-1）的胰岛素样活性会被IGF结合蛋白（IGFBPs，包括IGFBP-1和IGFBP-3）严重削弱。热应激（HS）对生长猪体内IGF-1和IGFBPs的影响仍不清楚。本研究旨在调查生长猪在慢性热应激条件下IGF-1和IGFBPs的变化。从9窝中选取27头体重相近的生长大白公猪，分为三种处理组。所有处理组的窝效应均得到平衡。处理组分别为：1）热中性（TN）组（23°C），2）慢性热应激组（33°C），3）TN条件下的配对饲喂组（PFTN）。实验持续21天。与TN对照组相比，热应激猪的采食量降低、平均体重增加减少、直肠温度升高且呼吸频率增加。在第7天，与TN对照组相比，热应激猪的血浆胰岛素浓度和胰岛素：葡萄糖比值升高。与PFTN组和TN组相比，热应激猪的血浆IGF-1：IGFBP-3比值总体升高。此外，热应激猪肝脏IGF-1基因表达比TN组高50%。然而，与TN猪相比，PFTN猪的血浆IGF-1：IGFBP-3比值和肝脏IGF-1基因表达没有差异。与TN对照组相比，PFTN猪的血浆IGFBPs浓度和肝脏IGFBPs基因表达增加。然而，TN组和热应激组之间的血浆IGFBPs浓度和肝脏IGFBPs基因表达没有差异。与TN对照组相比，热应激猪肝脏IRS-1基因和蛋白表达有升高趋势，而PFTN猪的肝脏IRS-1基因和蛋白表达仍保持在正常水平。高温（33°C），不依赖于采食量减少，会增加生长猪的IGF-1，但不影响IGFBPs水平。
