热应激对肉鸡抗氧化能力及腓肠肌纤维类型的影响

    Effects of heat stress on antioxidant capacity and gastrocnemius musclefiber types of broilers

    • 摘要:
      目的 研究慢性热应激对黄羽肉鸡肝脏和肌肉的抗氧化能力与内质网应激以及腓肠肌肌纤维类型的影响.
      方法 试验选用20只47日龄黄羽肉鸡,随机分为常温组和慢性热应激组,每组10只.鸡只饲养在人工气候室,试验期30 d.试验结束采集血液、肝脏和腓肠肌样品,利用试剂盒法检测血清生化指标、血清激素以及血清和肝脏抗氧化指标.利用实时荧光定量PCR法检测内质网应激(Endoplasmic reticulum stress, ERS)相关基因和腓肠肌不同肌纤维肌球蛋白重链(Myosin heavy chain, MyHC)基因mRNA的表达.
      结果和结论 慢性热应激显著降低肉鸡平均日增质量、血清甘油三酯(TG)、甲状腺激素(T3和T4)、胰岛素样生长因子1(Insulin-like growth factor 1, IGF-1),显著升高血清皮质酮(CORT)水平(P < 0.05).同时,慢性热应激显著升高血清中丙二醛(MDA)含量,降低血清和肝脏谷胱甘肽过氧化物酶(GSH-PX)活性和肝脏总抗氧化能力(T-AOC)(P < 0.05).此外,慢性热应激显著提高肉鸡肝脏和腓肠肌中热休克蛋白70(Heat shock protein 70, HSP70)基因以及腓肠肌中转录激活因子4(Activating transcription factor 4, ATF4)基因mRNA的表达(P < 0.05),降低腓肠肌中葡萄糖调节蛋白78(Glucose-regulated protein 78, GRP78)基因mRNA的表达,而对肝脏中ATF4GRP78基因mRNA的表达量无显著影响.最后,慢性热应激显著降低腓肠肌慢肌(Slow myofiber,SM)MyHC基因mRNA表达量(P < 0.05)而对快红肌(Fast red myofiber, FRM)和快白肌(Fast white myofiber, FWM)MyHC基因mRNA表达量无影响.研究结果提示,慢性热应激可能通过降低血清生长和代谢激素、机体抗氧化能力以及引发细胞内质网应激影响肉鸡生长和腓肠肌纤维类型.

       

      Abstract:
      Objective The present study was conducted to investigate the effects of chronic heat stress on antioxidant capacity, endoplasmic reticulum stress and gastrocnemius muscle fiber types of yellow feather broilers.
      Method Twenty 47-day-old yellow feather broilers were randomly divided into control and chronic heat stress groups with 10 broilers in each group. The broilers were raised in an artificial climate chamber for 30 days. At the end of the trial, the samples of blood, liver and gastrocnemius muscle were collected. Serum biochemical indexes, hormones and antioxidant indexes of liver and gastrocnemius muscle were determined using the commerical assay kit method. And the mRNA expression of endoplasmic reticulum stress (ERS) related genes and myosin heavy chain (MyHC) of different skeletal muscle fiber types were detected using real-time quantitative PCR.
      Result and conclusion Chronic heat stress significantly (P < 0.05) decreased the average daily gain, serum TG content, thyroid hormone (T3 and T4), and insulin-like growth factor 1 (IGF-1) levels, and increased serum corticosterone (CORT) concentration. Meanwhile, chronic heat stress markedly (P < 0.05) enhanced serum malondialdehyde (MDA) content, and reduced serum, GSH-PX activity and total antioxidant capacity (T-AOC) in liver.In addition, chronic heat stress remarkablly (P < 0.05) elevated the mRNA expression of heat shock protein 70 (HSP70) in liver and gastrocnemius muscle, and of activating transcription factor 4 (ATF4) in gastrocnemius muscle, and decreased the glucose-regulated protein 78 (GRP78) mRNA expression in gastrocnemius muscle, with no obvious effect on the mRNA expression of ATF4 and GRP78 in liver. Moreover, chronic heat stress significantly (P < 0.05) inhibited the mRNA expression of slow myofiber MyHC, with no influence on MyHC mRNA expression of fast red myofiber and fast white myofiber. In conclusion, this results suggest that chronic heat stress may affect broiler growth and gastrocnemius muscle fiber types by decreasing serum hormones involved in growth and metabolism, antioxidant capacity and eliciting ERS.

       

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