去势对鸡脂肪代谢的影响及其分子机理研究

发布时间：2018-12-17 05:35

【摘要】：脂肪定向沉积和改善肉品质是肉鸡生产中亟待解决的问题。研究表明,性腺轴激素对脂肪代谢和定向沉积具有显著影响。本研究利用去势公、母鸡为试验模型,分别与对照组对比,分析脂肪含量、肉品质、激素水平的变化,以及腹脂和胸肌组织中相关基因的差异表达,从组织和分子水平系统研究性腺激素的变化对脂肪代谢的影响,为提高肌内脂肪含量的优质肉鸡肉品质选择技术提供理论基础。试验一：去势鸡脂肪含量和肉品质的变化以北京油鸡为素材,在3周龄对公、母鸡进行去势手术,与对照组在相同条件下饲养,共四组。分别在13周龄(每组10只)、17周龄(每组20只)和22周龄(每组10只)屠宰测定。结果表明：1)公、母鸡去势后血清中甘油三酯(TG)和肝脏总脂含量显著增加(P0.05),腹脂率显著提高(P0.05)。2)去势改善了鸡肉的色泽、嫩度和风味,肉品质得到提高,主要表现在IMF含量显著增加(P0.05),肉色红度降低黄度升高(P0.05),剪切力显著降低(P0.05),肌纤维变细密(P0.05),肌苷酸(IMP)含量增加,脂肪酸含量与组成发生改变。试验二：去势鸡性腺激素变化对脂肪沉积的影响对13、17和22周龄鸡血清中睾酮(T)、雌二醇(E2)和卵泡刺激素(FSH)含量进行测定,检测17周龄鸡腹脂与胸肌中T、E2和FSH含量及其受体表达变化,并对腹脂重与激素含量进行相关分析。结果表明：1)公鸡去势后随周龄增加血清T含量极显著下降(P0.01),腹脂和胸肌中T含量也显著降低(P0.05),且公鸡腹脂重与血清、腹脂中T含量存在极显著负相关(P0.01)。2)母鸡去势后随周龄增加血清E2含量显著低于对照组(P0.05),FSH含量显著高于对照组(P0.05),腹脂中E2含量与ESR1受体表达量显著下降(P0.05),腹脂中FSH含量与FSHR受体表达量有升高的趋势,母鸡腹脂重与腹脂E2含量存在极显著负相关(P0.01)。试验三：去势对鸡脂类代谢的分子调控机理选取17周龄去势组与对照组的公、母鸡为研究对象,利用表达谱测序技术分析腹脂(n=3)和胸肌(n=3)中脂质代谢基因表达变化及相关信号通路。综合以上结果表明：1)腹脂和胸肌中差异表达基因均显著富集在ECM受体互作途径、焦点粘连和细胞黏附分子信号通路(P0.05),说明这些通路可能在调控鸡脂类沉积过程中发挥重要作用。2)鸡去势后性腺激素发生改变,由类固醇生物合成及脂肪代谢相关信号通路介导,导致腹脂中脂类合成基因(SCD、MSMO1、FABP7等)上调,脂肪分解(MGLL)和类固醇合成(CYP2D6)基因下调,促进腹脂沉积(P0.05)。3)公鸡去势后T含量下降,由类固醇激素生物合成及胆酸生物合成、脂肪细胞因子信号通路介导,可能通过上调胸肌中CD36,下调DIPOQ、AKR1D1和CYP2D6等脂类代谢基因表达促进IMF沉积；母鸡去势后E2含量分泌减少,FSH含量升高,由不饱和脂肪酸生物合成和花生四烯酸代谢通路介导,可能通过上调胸肌中PECR,下调HSD17B12和EPHX2等脂类代谢基因表达促进IMF沉积(P0.05)。
[Abstract]:Fat directional deposition and meat quality improvement are urgent problems in broiler production. The results showed that gonadal axis hormones had significant effects on fat metabolism and directional deposition. In this study, using ovariectomized male and hen as experimental model, we compared with the control group to analyze the changes of fat content, meat quality, hormone level, and the differentially expressed genes in abdominal fat and pectoralis muscle. The effects of gonadal hormone changes on fat metabolism were systematically studied at the tissue and molecular levels to provide a theoretical basis for the selection of quality chicken meat with higher intramuscular fat content. Experiment 1: the changes of fat content and meat quality of ovariectomized chickens were treated by ovariectomization of male and female chickens at the age of 3 weeks, and were raised under the same conditions as the control group. Slaughter was performed at the age of 13 weeks (10 rats per group), 17 weeks (20 rats per group) and 22 weeks (10 rats per group). The results showed that: 1) the serum triglyceride (TG) and liver total lipid content in male and female hens were significantly increased after castration (P0.05), and the abdominal fat rate was significantly increased (P0.05). 2) castration improved the color, tenderness and flavor of chicken. The meat quality was improved, mainly in the increase of IMF content (P0.05), the decrease of color redness of meat (P0.05), the decrease of shearing force (P0.05), and the fineness of muscle fiber (P0.05). Inosine (IMP) content increased, fatty acid content and composition changed. Experiment 2: the effect of the change of gonadal hormone on fat deposition in ovariectomized chickens. The levels of testosterone (T), estradiol (E 2) and follicle stimulating hormone (FSH) in serum of 1317 and 22 week old chickens were determined, and the T of abdominal fat and pectoralis muscle of 17 weeks old chickens were detected. The changes of E _ 2 and FSH contents and their receptor expression, and the correlation between abdominal fat weight and hormone content were analyzed. The results showed that: 1) after ovariectomized, serum T content decreased significantly (P0.01), abdominal fat and chest muscle T content also decreased significantly (P0.05), and the weight of abdominal fat and serum of rooster increased significantly (P0.01). There was a significant negative correlation (P0.01) in T content in abdominal fat (P0.01). 2) the serum E _ 2 content in hens increased with the age of week after castration (P0.05), FSH was significantly higher than that in the control group (P0.05). E2 content and ESR1 receptor expression in abdominal fat decreased significantly (P0.05), FSH content and FSHR receptor expression in abdominal fat tended to increase, and there was a very significant negative correlation between abdominal fat weight and abdominal fat E2 content in hens (P0.01). Experiment 3: the molecular regulation mechanism of ovariectomy on lipid metabolism in chickens. The male and female chickens of 17 weeks old ovariectomized group and control group were selected as the research objects. The changes of lipid metabolism gene expression and related signal pathways in abdominal fat (nf3) and pectoralis muscle (nf3) were analyzed by expression profiling and sequencing. The results showed that: 1) the differentially expressed genes in abdominal fat and pectoralis were significantly enriched in ECM receptor interaction pathway, focal adhesion and cellular adhesion molecular signaling pathway (P0.05). These pathways may play an important role in the regulation of lipid deposition in chickens. 2) the changes of gonadal hormones after ovariectomy are mediated by steroid biosynthesis and signal pathways related to fat metabolism, leading to the lipid synthesis gene (SCD,) in abdominal fat. MSMO1,FABP7 et al.) up-regulated adipose (MGLL) and steroid synthesis (CYP2D6) gene down-regulated abdominal fat deposition (P0.05). 3) T content decreased after ovariectomized by steroid hormone biosynthesis and cholic acid biosynthesis. Adipocyte factor signaling pathway may promote the deposition of IMF by up-regulating the expression of lipid metabolism genes such as DIPOQ,AKR1D1 and CYP2D6 in pectoralis muscle by up-regulating CD36,. After castration, the secretion of E2 decreased and the content of FSH increased, mediated by unsaturated fatty acid biosynthesis and arachidonic acid metabolism pathway, which may be mediated by upregulation of PECR, in the pectoralis muscle. Down-regulation of lipid metabolism genes such as HSD17B12 and EPHX2 promoted IMF deposition (P0.05).
【学位授予单位】：中国农业科学院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S831

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