Effects of GHRP-2 and Cysteamine Administration on Growth Performance, Somatotropic Axis Hormone and Muscle Protein Deposition in Yaks (Bos grunniens) with Growth Retardation.
Effects of GHRP-2 and Cysteamine Administration on Growth Performance, Somatotropic Axis Hormone and Muscle Protein Deposition in Yaks (Bos grunniens) with Growth Retardation.
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DOI：
10.1371/journal.pone.0149461
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Niu Q
中科院分区：
文献类型：
--
作者：
Hu R;Wang Z;Peng Q;Zou H;Wang H;Yu X;Jing X;Wang Y;Cao B;Bao S;Zhang W;Zhao S;Ji H;Kong X;Niu Q
本研究的目的是探讨生长激素释放肽2（GHRP-2）和半胱胺（CS）给药对生长迟缓牦牛生长性能的影响，并试图阐明其调节机制。试验1，随机选取36头1岁青海高原牦牛（体重38~83.2 kg）进行体重和颈静脉血标本采集。体重较轻的牦牛群体体重与血清GHRH（P < 0.05，R = 0.45）、GH（P < 0.05，R = 0.47）、IGF-1（P < 0.05，R = 0.62）的关系显着相关。试验2，随机选取生长迟缓的1岁青海高原牦牛15头（平均体重54.8±8.24 kg），分为阴性对照组（NG）、GHRP-2注射组（GG）和半胱胺饲喂组（CG），每组5头。另选取5头生长性能正常的1岁青海高原牦牛（平均体重75.3±2.43 kg）作为阳性对照组（PG）。 GG和CG组的平均日增重（ADG）显着高于PG和NG组（P < 0.05）。 GHRP-2和CS给药均显着增加骨骼肌的肌纤维直径和面积（P<0.05）。 GHRP-2显着升高血清GH和IGF-1水平（P < 0.05），上调肝脏和骨骼肌中GHR、IGF-1和IGF-1R mRNA表达（P < 0.05），增强骨骼肌中PI3K、AKt和mTOR mRNA表达（P < 0.05）。 CS显着降低血清SS水平和下丘脑SS mRNA表达（P < 0.05），增强肝脏GHR和IGF-1 mRNA表达（P < 0.05），降低肌肉萎缩F-box（Atrogin-1）和肌肉环指1（MuRF1）mRNA表达（P < 0.05）。结论：牦牛生长迟缓主要是由于生长轴激素分泌不足所致。 GHRP-2和CS均可促进生长迟缓的牦牛的生长性能和GH、IGF-1的分泌。 GHRP-2主要通过上调蛋白质合成途径来增强肌肉蛋白质沉积，而CS主要通过下调泛素-蛋白酶体途径发挥作用。
The objective of this study was to investigate the effects of growth hormone-releasing peptide-2 (GHRP-2) and cysteamine (CS) administration on growth performance in yaks with growth retardation and try to elucidate its regulatory mechanisms. Trial 1, thirty-six 1-year-old Qinghai high plateau yaks (body weight 38–83.2 kg) were randomly chosen for body weight and jugular blood samples collection. The relationship between body weight and serum GHRH (P < 0.05, R = 0.45), GH (P < 0.05, R = 0.47), IGF-1 (P < 0.05, R = 0.62) was significantly correlated in yaks colonies with lighter body weights. Trial 2, fifteen 1-year-old Qinghai high plateau yaks with growth retardation (average body weight 54.8 ± 8.24 kg) were randomly selected and assigned to negative control group (NG), GHRP-2 injection group (GG) and cysteamine feeding group (CG), with 5 yaks per group. Another five 1-year-old Qinghai high plateau yaks with normal growth performance (average body weight 75.3 ± 2.43 kg) were selected as positive control group (PG). The average daily gain (ADG) of the GG and CG were significantly higher than those in the PG and NG (P < 0.05). Both GHRP-2 and CS administration significantly enhanced the myofiber diameter and area of skeletal muscle (P<0.05). GHRP-2 significantly enhanced the serum GH and IGF-1 levels (P < 0.05), and up-regulated GHR, IGF-1 and IGF-1R mRNA expression in the liver and skeletal muscle (P < 0.05), enhanced the mRNA expression of PI3K, AKt and mTOR in the skeletal muscle (P<0.05). CS significantly reduced the serum SS levels and the hypothalamus SS mRNA expression (P < 0.05), and enhanced GHR and IGF-1 mRNA expression in the liver (P < 0.05), decreased the mRNA expression of muscle atrophy F-box (Atrogin-1) and muscle ring finger 1 (MuRF1) mRNA (P < 0.05). Conclusions: Growth retardation in yaks was primarily due to somatotropic axis hormones secretion deficiency. Both GHRP-2 and CS administration can accelerate growth performance and GH, IGF-1 secretion in yaks with growth retardation. GHRP-2 enhanced muscle protein deposition mainly by up-regulated the protein synthesis pathways, whereas CS worked mainly by down-regulated the ubiquitin-proteasome pathway.