第112期：生長豬免疫系統(tǒng)激活后對葡萄糖的需要量

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

生長豬免疫系統(tǒng)激活后對葡萄糖的需要量

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

　　被激活后的免疫細胞需要利用葡萄糖，靜脈注射大量脂多糖會導致胰島素耐受和嚴重的低血糖。因此，本試驗的目的是測量內(nèi)毒素攻毒后維持血糖水平所需要的葡萄糖量，以此作為白細胞葡萄糖的需要量。試驗選用15頭禁食的雜交小母豬（30.3 ± 1.7 kg）雙側頸靜脈插管，隨機分為2個處理組：對照組（n=7）靜脈注射10 ml生理鹽水，試驗組（n=8）進行脂多糖攻毒并使用血糖鉗技術維持血糖水平（脂多糖，大腸桿菌055:B5，5ug/kg體重；使用50%葡萄糖溶液維持血糖水平）。注射后，每10 min監(jiān)測血糖水平，并調(diào)節(jié)處理組葡萄糖輸送速度以維持血糖水平8 h。豬只在處理前8 h開始禁食，并在整個實驗階段禁食。處理組豬只在處理后直腸溫度顯著上升（39.8℃ VS. 38.8℃，P＜0.01）。對照組豬注射后300-480 min期間血糖水平比初始值低20%（P=0.01），而試驗組豬只沒有明顯變化（P=0.96）。試驗組總計需要116±8g葡萄糖維持血糖水平的穩(wěn)定。與對照組相比，試驗組豬只血漿胰島素、血漿尿素氮、β-羥基丁酸、l-乳酸、脂多糖結合蛋白含量顯著升高（分別提高295、108、29、133和13%，P≤0.04），而游離脂肪酸含量顯著下降（66%，P＜0.01）。處理組第120min時中性白細胞顯著降低84%（P＜0.01），并在第480min恢復到對照組水平?？傊?，與對照組相比，試驗組豬只淋巴細胞、單核細胞、嗜酸性粒細胞和嗜堿性細胞顯著降低（75、87、70和50%，P≤0.05）。免疫應激對于代謝的調(diào)節(jié)和維持血糖水平需要的大量葡萄糖都說明養(yǎng)分的分配從生長轉向免疫系統(tǒng)。葡萄糖是免疫系統(tǒng)的重要養(yǎng)分，本試驗的研究結果表明生長豬在嚴重的急性應激條件下對葡萄糖的需要量為約1.1g/kg代謝體重/小時。

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.

翻譯：朱滔      來源：豬營養(yǎng)國際論壇CSIS