第112期：生长猪免疫系统激活后对葡萄糖的需要量

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2017. J. Anim. Sci. 95(11): 5020-5029

生长猪免疫系统激活后对葡萄糖的需要量

S. K. Kvidera, E. A. Horst, E. J. Mayorga, M. V. Sanz-Fernandez, M. Abuajamieh and L. H. Baumgard

　　被激活后的免疫细胞需要利用葡萄糖，静脉注射大量脂多糖会导致胰岛素耐受和严重的低血糖。因此，本试验的目的是测量内毒素攻毒后维持血糖水平所需要的葡萄糖量，以此作为白细胞葡萄糖的需要量。试验选用15头禁食的杂交小母猪（30.3 ± 1.7 kg）双侧颈静脉插管，随机分为2个处理组：对照组（n=7）静脉注射10 ml生理盐水，试验组（n=8）进行脂多糖攻毒并使用血糖钳技术维持血糖水平（脂多糖，大肠杆菌055:B5，5ug/kg体重；使用50%葡萄糖溶液维持血糖水平）。注射后，每10 min监测血糖水平，并调节处理组葡萄糖输送速度以维持血糖水平8 h。猪只在处理前8 h开始禁食，并在整个实验阶段禁食。处理组猪只在处理后直肠温度显著上升（39.8℃ VS. 38.8℃，P＜0.01）。对照组猪注射后300-480 min期间血糖水平比初始值低20%（P=0.01），而试验组猪只没有明显变化（P=0.96）。试验组总计需要116±8g葡萄糖维持血糖水平的稳定。与对照组相比，试验组猪只血浆胰岛素、血浆尿素氮、β-羟基丁酸、l-乳酸、脂多糖结合蛋白含量显著升高（分别提高295、108、29、133和13%，P≤0.04），而游离脂肪酸含量显著下降（66%，P＜0.01）。处理组第120min时中性白细胞显著降低84%（P＜0.01），并在第480min恢复到对照组水平。总之，与对照组相比，试验组猪只淋巴细胞、单核细胞、嗜酸性粒细胞和嗜碱性细胞显著降低（75、87、70和50%，P≤0.05）。免疫应激对于代谢的调节和维持血糖水平需要的大量葡萄糖都说明养分的分配从生长转向免疫系统。葡萄糖是免疫系统的重要养分，本试验的研究结果表明生长猪在严重的急性应激条件下对葡萄糖的需要量为约1.1g/kg代谢体重/小时。

Estimating glucose requirements of an activated immune system in growing pigs

S. K. Kvidera, E. A. Horst, E. J. Mayorga, M. V. Sanz-Fernandez, M. Abuajamieh and L. H. Baumgard

Activated immune cells become obligate glucose utilizers, and a large i.v. lipopolysaccharide (LPS) dose causes insulin resistance and severe hypoglycemia. Therefore, study objectives were to quantify the amount of glucose needed to maintain euglycemia following anendotoxin challenge as a proxy of leukocyte glucose requirements. Fifteen fasted crossbred gilts (30.3 ± 1.7 kg) were bilaterally jugular catheterizedand assigned 1 of 2 i.v. bolus treatments: control (CON; 10 mL sterile saline;n = 7) or LPS challenge + euglycemic clamp (LPS-Eu; Escherichia coli 055:B5; 5 μg/kg BW; 50% dextrose infusion to maintain euglycemia; n = 8). Following administration, blood glucose was determined every 10 min and dextrose infusionrates were adjusted in LPS-Eu pigs to maintain euglycemia for 8 h. Pigs werefasted for 8 h prior to the bolus and remained fasted throughout the challenge. Rectal temperature was increased in LPS-Eu pigs relative to CON pigs (39.8 vs.38.8°C; P < 0.01). Relative to the base line, CON pigs had 20% decreased blood glucose from 300 to 480 min post bolus (P = 0.01) whereas circulating glucose content in LPS-Eu pigs did not differ (P = 0.96) from prebolus levels. A total of 116 ± 8 g of infused glucose was required to maintain euglycemia in LPS-Eu pigs. Relative to CON pigs, overall plasma insulin, blood urea nitrogen, β-hydroxybutrate, l-lactate, and LPS-binding protein were increased in LPS-Eu pigs (295, 108, 29, 133, and 13%, respectively; P ≤ 0.04) whereas NEFA was decreased (66%; P < 0.01). Neutrophils in LPS-Eu pigs were decreased 84% at 120 min post bolus and returned to CON levels by 480 min (P < 0.01). Overall, lymphocytes, monocytes, eosinophils, and basophils were decreased in LPS-Eu pigs relative to CON pigs (75, 87, 70, and50%, respectively; P ≤ 0.05). These alterations in metabolism and the large amount of glucose needed to maintain euglycemia indicate nutrient repartitioning away from growth toward the immune system. Glucose is an important fuel for the immune system, and data from this study established that the glucose requirements of an intensely and acute lyactivated immune system in growing pigs are approximately 1.1 g/kg BW0.75/h.

翻译：朱滔      来源：猪营养国际论坛CSIS