L-Citrulline acts as potential hypothermic agent to afford thermotolerance in chicks
L-Citrulline acts as potential hypothermic agent to afford thermotolerance in chicks
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DOI：
10.1016/j.jtherbio.2017.07.007
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发表时间：
2017-10-01
影响因子：
2.7
通讯作者：
Furuse, Mitsuhiro
中科院分区：
文献类型：
--
作者：
Chowdhury, Vishwajit S.;Han, Guofeng;Furuse, Mitsuhiro
最近我们证明 L-瓜氨酸 (L-Cit) 会导致雏鸡体温过低。然而，L-Cit 如何介导低温的问题仍然难以捉摸。因此，本研究的目的是检查 L-Cit 介导的低温过程中的一些可能因素，并确认 L-Cit 是否也能赋予雏鸡耐热性。给雏鸡口服 L-Cit，同时腹腔注射一氧化氮合酶 (NOS) 抑制剂 N-G-硝基-L-精氨酸甲酯盐酸盐 (L-NAME)，以检查 NO 在低温过程中的参与情况。雏鸡口服 L-Cit 后，还对食物摄入量和血浆代谢物进行了分析。为了检查耐热性，在暴露于高环境温度（35+/-1℃）180分钟之前，给雏鸡口服单剂量的L-Cit（15mmol/10ml/kg体重）或在短短1小时内两次相同的剂量（两次口服给药）。尽管服用 L-Cit 后直肠温度降低，但 L-NAME 降低幅度更大。 L-NAME可降低血浆中总NO2和NO3（NOx），证实其对NO的抑制作用。在研究的 300 分钟内，单次口服 L-Cit 介导持续的低温状态，而不影响食物摄入。进一步发现，经 L-Cit 处理的雏鸡的血浆葡萄糖显着降低。两次口服 L-Cit（而非单次口服）可在雏鸡血浆 NOx 没有显着变化的情况下提供耐热性。总之，我们的结果表明 L-Cit 介导的低温和耐热性可能不参与 NO 的产生。 L-Cit 介导的耐热性进一步表明，L-Cit 可能作为一种重要的营养补充剂，有助于应对夏季炎热。
Recently we demonstrated that L-citrulline (L-Cit) causes hypothermia in chicks. However, the question of how L-Cit mediates hypothermia remained elusive. Thus, the objective of this study was to examine some possible factors in the process of L-Cit-mediated hypothermia and to confirm whether L-Cit can also afford thermotolerance in young chicks. Chicks were subjected to oral administration of L-Cit along with intraperitoneal injection of a nitric oxide synthase (NOS) inhibitor, N-G-nitro-L-arginine methyl ester HCl (L-NAME), to examine the involvement of NO in the process of hypothermia. Food intake and plasma metabolites were also analyzed after oral administration of L-Cit in chicks. To examine thermotolerance, chicks were orally administered with a single dose of L-Cit (15 mmol/10 ml/kg body weight) or the same dose twice within a short interval of 1 h (dual oral administration) before the exposure to high ambient temperature (35 +/- 1 degrees C) for 180 min. Although the rectal temperature was reduced following administration of L-Cit, L-NAME caused a greater reduction. L-NAME reduced total NO2 and NO3 (NOx) in plasma, which confirmed its inhibitory effect on NO. A single oral administration of L-Cit mediated a persistent state of hypothermia for the 300 min of the study without affecting food intake. It was further found that plasma glucose was significantly lower in L-Cit-treated chicks. Dual oral administration of L-Cit, but not a single oral administration, afforded thermotolerance without a significant change in plasma NOx in chicks. In conclusion, our results suggest that L-Cit-mediated hypothermia and thermotolerance may not be involved in NO production. L-Cit-mediated thermotolerance further suggests that L-Cit may serve as an important nutritional supplement that could help in coping with summer heat.