熱應(yīng)激對(duì)肉仔雞肝AMPKα1及脂肪代謝相關(guān)分子基因表達(dá)的影響

周華金，胡希怡，楊家昶，丁祥文，王 玉，宋志剛

(山東農(nóng)業(yè)大學(xué)動(dòng)物科技學(xué)院/動(dòng)物醫(yī)學(xué)院，泰安 271018)

熱應(yīng)激降低家禽生長(zhǎng)性能，增加經(jīng)濟(jì)損失[1]。肉雞因其體溫高，無(wú)汗腺以及代謝旺盛等特點(diǎn)致使其自身蒸發(fā)散熱能力有限，因而對(duì)熱應(yīng)激特別敏感[2]。熱應(yīng)激導(dǎo)致肉雞采食量降低，繼而影響脂肪代謝[3]。肝是禽類脂肪酸從頭合成的主要場(chǎng)所，熱應(yīng)激可調(diào)節(jié)家禽肝脂肪代謝[4]。急性熱應(yīng)激提高肉仔雞血清中甘油三酯、高密度脂蛋白膽固醇和低密度脂蛋白膽固醇含量，激活脂肪酸合成相關(guān)酶，增加脂肪沉積[5]。熱應(yīng)激提高了肝中乙酰輔酶A羧化酶α(ACACA)、?；o酶A合成酶(ACSF3)以及硬脂酰輔酶A脫氫酶(SCD)等脂肪代謝相關(guān)酶的基因表達(dá)量，影響脂肪代謝[6]。

肝細(xì)胞以膽固醇為原料合成膽汁酸，是肝清除膽固醇的主要方式[7]。膽汁酸分子具有特殊的表面活性，能催化脂類物質(zhì)成為油水混合物的液滴，可擴(kuò)大脂類物質(zhì)同脂肪酶的接觸面，促進(jìn)脂類的消化和吸收[8]。同時(shí)，膽汁酸作為營(yíng)養(yǎng)信號(hào)，可激活特定受體，在營(yíng)養(yǎng)物質(zhì)轉(zhuǎn)運(yùn)、消化和代謝中起重要作用[9]。膽汁酸信號(hào)通路在哺乳動(dòng)物上引起廣泛關(guān)注，不僅可以調(diào)節(jié)脂肪代謝和腸道吸收，還可作為新陳代謝調(diào)節(jié)者和分子標(biāo)簽，影響整個(gè)機(jī)體脂肪、葡萄糖和能量代謝[10-11]。

固醇調(diào)節(jié)元件結(jié)合蛋白-1c(Sterol regulatory element binding protein- 1c,SREBP-1c)是膽固醇和脂肪酸生物合成中的關(guān)鍵轉(zhuǎn)錄因子，優(yōu)先參與脂肪酸合成相關(guān)基因的調(diào)控，可直接刺激編碼脂肪酸合成酶的基因轉(zhuǎn)錄[12-13]。脂肪酸轉(zhuǎn)運(yùn)蛋白1(Fatty acid transport protein1，F(xiàn)ATP-1)促進(jìn)脂肪細(xì)胞吸收脂肪酸，在脂肪細(xì)胞的分化中發(fā)揮重要作用[14]。載脂蛋白B(Apolipoprotein B，APOB)是肝中轉(zhuǎn)運(yùn)內(nèi)源性甘油三酯和膽固醇的功能蛋白，在雞肝、腎組織中有較高表達(dá)，與脂肪的沉積相關(guān)[15]。肝X受體(Liver X receptor，LXR)和法尼酯X受體(Farnesoid X receptor，F(xiàn)XR)在膽汁酸和膽固醇代謝過(guò)程中起重要的調(diào)節(jié)作用，通過(guò)對(duì)靶基因表達(dá)的調(diào)節(jié)來(lái)維持脂肪代謝的平衡。膽固醇7-羥化酶(Cholesterol 7-alpha hydroxyl-lase，CYP7A1)是膽固醇轉(zhuǎn)化為膽汁酸過(guò)程中主要的限速酶[16]。AMP活化蛋白激酶(AMP-activated protein kinase，AMPK)參與調(diào)節(jié)細(xì)胞代謝和整個(gè)機(jī)體的新陳代謝活動(dòng)，作為能量感受器維持內(nèi)環(huán)境的穩(wěn)定。AMPK參與脂肪的代謝調(diào)節(jié)，外周AMPK的磷酸化降低脂肪酸合成酶的轉(zhuǎn)錄活性，促進(jìn)脂肪酸氧化[17]。

有關(guān)熱應(yīng)激持續(xù)時(shí)間對(duì)肝脂肪代謝影響的研究不多，未見(jiàn)關(guān)于AMPK在應(yīng)激調(diào)控肝脂肪代謝中作用的報(bào)道。本試驗(yàn)通過(guò)探究長(zhǎng)、短期熱應(yīng)激對(duì)肉仔雞肝AMPKα1及脂肪代謝相關(guān)分子基因表達(dá)的影響，以期擴(kuò)展熱應(yīng)激影響肉仔雞肝脂肪代謝的理論，為生產(chǎn)中防控肉仔雞熱應(yīng)激提供科學(xué)參考。

1 材料與方法

1.1 試驗(yàn)設(shè)計(jì)

體重相近的1日齡雄性AA肉仔雞(Arbor Acres) 120只(購(gòu)自泰安大寶孵化場(chǎng))，嚴(yán)格控制飼養(yǎng)環(huán)境。試驗(yàn)開(kāi)始時(shí)飼養(yǎng)溫度35 ℃，根據(jù)肉雞日齡每周降低2～3 ℃，直到降到23 ℃。環(huán)境濕度為40%～50%，溫度和濕度隨肉雞生長(zhǎng)情況做相應(yīng)調(diào)整。光照程序按照23 h光照、1 h黑暗執(zhí)行。前期日糧粗蛋白含量為21%、代謝能為12.55 MJ·kg-1，后期日糧粗蛋白含量為19%、代謝能為12.97 MJ·kg-1。飼養(yǎng)階段自由采食和飲水。28日齡選取體重相近的健康肉雞96只，隨機(jī)分為4組(每組4個(gè)重復(fù)，每個(gè)重復(fù)6只雞)：24 h熱應(yīng)激組和24 h對(duì)照組、72 h熱應(yīng)激組和72 h對(duì)照組。28日齡08:00開(kāi)始試驗(yàn)，統(tǒng)計(jì)各組雞體重、余料量，記錄加料量，熱應(yīng)激處理組溫度為(33±1)℃ ，對(duì)照組(23±1)℃。29和31日齡上午08:00每個(gè)組在飼喂前稱重，每次稱取雞只的體重和剩余料量，計(jì)算熱應(yīng)激24和72 h的采食量和體增重，每個(gè)重復(fù)選取2只雞，翅靜脈采集血液后4 ℃、400 g離心10 min，取上清放置于-20 ℃保存，而后屠宰，采集肝樣品，用冰冷的生理鹽水漂洗新鮮的肝樣品后，液氮速凍，放于-80 ℃保存。

1.2 血漿指標(biāo)測(cè)定

血漿中葡萄糖(GLU)、尿酸(UA)、總膽固醇(TCHO)、總膽汁酸 (TBA)、甘油三脂(TG) 利用比色法采用分光光度計(jì)進(jìn)行測(cè)定，試劑盒購(gòu)自南京建成試劑有限公司。

1.3 RT-PCR對(duì)基因表達(dá)的測(cè)定

肝總RNA用Trizol法提取，利用瓊脂糖凝膠電泳和生物分光光度計(jì)(Biophotometer plusone，德國(guó) Eppendorf)分別檢測(cè)總RNA的質(zhì)量和濃度。按照TaKaRa RNA PCR 反轉(zhuǎn)錄試劑盒操作說(shuō)明進(jìn)行反轉(zhuǎn)錄。反應(yīng)體系：500 ng總RNA, 5 mmol·L-1MgCl2, 1 μL RT buffer, 1 mmol·L-1dNTP, 2.5 U 逆轉(zhuǎn)錄酶(AMV), 0.7 mmol·L-1Oligod (T) 和10 U Ribonuclease inhibitor，加DEPC水至10 μL。42 ℃反應(yīng)40 min, 99 ℃滅活5 min，降低到5 ℃反應(yīng) 5 min。cDNA合成以后進(jìn)行熒光定量PCR。引物序列見(jiàn)表1，由上海生工生物技術(shù)有限公司合成。通過(guò)對(duì)混合樣品進(jìn)行標(biāo)準(zhǔn)曲線測(cè)定確定引物的質(zhì)量和最佳的稀釋濃度。反應(yīng)體系為20 μL∶10 μL SYBR Premix Ex TaqTM (2×)，上游引物和下游引物(10 μmol·L-1)各0.4 μL, 0.4 μL ROX Reference Dye Ⅱ(50×), 2 μL cDNA模板和6.8 μL去離子水。兩步法熒光定量PCR反應(yīng)條件：第一步95 ℃變性 10 s, 1個(gè)循環(huán)，第二步95 ℃變性5 s，60 ℃退火34 s, 40個(gè)循環(huán)。

表1引物序列

Table1Gene-specificprimersofrelatedgenes

基因名稱Genename引物序號(hào)GenBankaccessionNo.引物序列(5'→3')Primerssequence定位Orientation片段大小/bpAmpliconsizeSREBP-1cAY029224GCCCTCTGTGCCTTTGTCTTCACTCAGCCATGATGCTTCTTCCForwardReverse130LXRAJ507202GTCCCTGACCCTAATAACCGCGTCTCCAACAACATCACCTCTATGForwardReverse185APOBM18421CACGCCTCACAGACCAAGTACCAGTCAAACGGCACATCTAForwardReverse407FATP-1NM_001039602.1TACAATGTGCTCCAGAAGGGGTCTGGTTGAGGATGTGACTCForwardReverse179CYP7A1AY700578GATCTTCCCAGCCCTTGTGGAGCCTCTCCCAGCTTCTCACForwardReverse82FXRAF492497AGTAGAAGCCATGTTCCTCCGTTGCAGTGCATATTCCTCCTGTGTCForwardReverse182GAPDHNM_204305ACATGGCATCCAAGGAGTGAGGGGGAGACAGAAGGGAACAGAForwardReverse266AMPKα1DQ302133CGGAGATAAACAGAAGCACGAGCGATTCAGGATCTTCACTGCAACForwardReverse266

參照文獻(xiàn)[18]的方法用2-ΔΔCT法定量目標(biāo)基因相對(duì)表達(dá)量，以GAPDH作為參照基因進(jìn)行校準(zhǔn)

According to reference [18], the relative expression of target genes were determined by 2-ΔΔCTmethod, usingGAPDHas the reference gene for calibration

1.4 數(shù)據(jù)分析

數(shù)據(jù)采用SAS (Version 8e，SAS Institute，1998)統(tǒng)計(jì)軟件ANOVA法進(jìn)行單因子方差分析，試驗(yàn)數(shù)據(jù)用“平均值±標(biāo)準(zhǔn)誤(Mean±SE)”表示，P<0.05表示處理效應(yīng)差異顯著。

2 結(jié) 果

2.1 熱應(yīng)激對(duì)肉仔雞生長(zhǎng)性能的影響

由圖1可知，24 與72 h熱應(yīng)激均顯著降低肉仔雞平均體增重(P<0.05)；由圖2可知，24 與72 h熱應(yīng)激均顯著降低肉仔雞平均采食量(P<0.05)。

2.2 熱應(yīng)激對(duì)肉仔雞血液生化指標(biāo)的影響

由表2可知，與對(duì)照組相比，24 h熱應(yīng)激顯著高肉仔雞血漿中葡萄糖(GLU)和總膽汁酸(TBA)含量(P<0.05)；由表3可知，與對(duì)照組相比，72 h熱應(yīng)激顯著提高肉仔雞血漿中葡萄糖(GLU)、甘油三脂(TG)和總膽固醇(TCHO)含量(P<0.05)。

柱形圖上所標(biāo)字母相異表示差異顯著(P<0.05)，未標(biāo)字母表示差異不顯著(P>0.05)。下圖同Different letters on the column charts indicate significant differences between treatments (P<0.05), no letters on the column charts mean no significant difference between treatments (P>0.05). The following figures are the same圖1 熱應(yīng)激24 和72 h對(duì)肉仔雞體增重的影響Fig.1 Effects of heat stress for 24 and 72 h on the body weight gain of broiler chickens

圖2 熱應(yīng)激24和72 h對(duì)肉仔雞采食量的影響Fig.2 Effects of heat stress for 24 and 72 h on feed intake of broiler chickens

2.3 熱應(yīng)激對(duì)肉仔雞脂肪代謝相關(guān)基因表達(dá)的影響

由圖3可知，與對(duì)照組相比，24 h熱應(yīng)激對(duì)肉仔雞肝中FATP-1、SREBP-1c、APOB和LXR基因表達(dá)均無(wú)顯著影響(P>0.05) (圖3A)；72 h熱應(yīng)激顯著上調(diào)肉仔雞肝中FATP-1、SREBP-1c、APOB和LXR基因的相對(duì)表達(dá)量(P<0.05)(圖3B)。

2.4 熱應(yīng)激對(duì)肉仔雞肝CYP7A1信號(hào)通路相關(guān)基因表達(dá)的影響

由圖4可知，與對(duì)照組相比，24 h熱應(yīng)激對(duì)肉仔雞肝中FXR和CYP7A1基因表達(dá)無(wú)顯著性影響(P>0.05)(圖4A)；72 h熱應(yīng)激對(duì)肉仔雞肝中FXR和CYP7A1基因表達(dá)有增加的趨勢(shì)(0.05

2.5 熱應(yīng)激對(duì)肉仔雞肝AMPK的影響

由圖5可知，與對(duì)照組相比，24 h熱應(yīng)激對(duì)肉仔雞肝中AMPKα1 基因表達(dá)沒(méi)有造成顯著影響(P>0.05)；72 h熱應(yīng)激顯著上調(diào)肉仔雞肝中AMPKα1基因表達(dá)(P<0.05)。

表2熱應(yīng)激24h對(duì)肉仔雞血液生化指標(biāo)的影響

Table2Effectsof24-hourheatstressonplasmametabolitesinbroilerchickens

項(xiàng)目Item對(duì)照Control熱應(yīng)激HeatstressP值P-value尿酸/(mmol·L-1)UA0.53±0.030.54±0.030.7668葡萄糖/(mmol·L-1)GLU13.49±0.28b15.55±0.26a0.0001甘油三酯/(mmol·L-1)TG0.17±0.030.27±0.040.0611總膽固醇/(mmol·L-1)TCHO3.13±0.183.50±0.140.1129總膽汁酸/(μmol·L-1)TBA35.33±1.60b42.21±2.03a0.0271

同行數(shù)據(jù)后所標(biāo)字母相異表示差異顯著(P<0.05)，未標(biāo)字母表示差異不顯著(P>0.05)。下同

Different letters in the same row means significant difference between treatments (P<0.05), no letters in the same row means not significant difference between treatments (P>0.05).The same as below

表3熱應(yīng)激72h對(duì)肉仔雞血液生化指標(biāo)的影響

Table3Effectsof72-hourheatstressonplasmametabolitesinbroilerchickens

項(xiàng)目Item對(duì)照Control熱應(yīng)激HeatstressP值P-value尿酸/(mmol·L-1)UA0.47±0.020.52±0.030.2891葡萄糖/(mmol·L-1)GLU13.67±0.16b16.71±0.52a<0.0001甘油三酯/(mmol·L-1)TG0.34±0.04b0.82±0.11a0.0012總膽固醇/(mmol·L-1)TCHO2.76±0.16b3.52±0.18a0.0073總膽汁酸/(μmol·L-1)TBA38.52±3.4138.20±2.620.9430

圖3 24 和72 h熱應(yīng)激對(duì)肉仔雞肝脂肪代謝相關(guān)基因表達(dá)的影響Fig.3 Effects of heat stress for 24(A) and 72 h(B) on the mRNA expression of FATP-1, SREBP-1c, APOB and LXR in livers of broiler chickens

圖4 24 和72 h熱應(yīng)激對(duì)肉仔雞肝CYP7A1信號(hào)通路相關(guān)基因表達(dá)的影響Fig.4 Effect of heat stress for 24(A) and 72 h(B) on the genes expression in CYP7A1 signal pathway in livers of broiler chickens

圖5 24和72 h熱應(yīng)激對(duì)肉仔雞肝AMPKα1基因表達(dá)的影響Fig.5 Effect of heat stress for 24 and 72 h on gene expression of AMPKα1 in livers of broiler chickens

3 討 論

3.1 熱應(yīng)激對(duì)肉仔雞生長(zhǎng)性能的影響

高溫可直接引起家禽采食量的降低。本研究結(jié)果顯示，熱應(yīng)激顯著降低肉仔雞平均體增重和采食量，這與前期研究結(jié)果一致[19-21]。已有研究表明，熱應(yīng)激誘導(dǎo)下丘腦-垂體-腎上腺皮質(zhì)軸(Hypothalamic-pituitary-adrenal, HPA)的激活，腎上腺皮質(zhì)大量釋放皮質(zhì)酮影響家禽采食行為是造成生產(chǎn)性能下降的主要原因[22]。

與相近體重的哺乳動(dòng)物相比較，家禽血漿中含有較高的血糖濃度[23]。本研究結(jié)果顯示，24 和72 h熱應(yīng)激均顯著提高血漿中葡萄糖含量，此外，72 h熱應(yīng)激顯著提高了血漿中甘油三脂和膽固醇含量。相關(guān)研究顯示，機(jī)體在應(yīng)激條件下通過(guò)促進(jìn)體內(nèi)葡萄糖的動(dòng)員和生產(chǎn)提高血糖水平以維持穩(wěn)態(tài)[24]。短期應(yīng)激下，HPA軸通過(guò)與腎上腺素、胰島素、胰高血糖素和交感神經(jīng)系統(tǒng)的互作，提高血糖水平，滿足機(jī)體重要器官的能量供給[20]。而在長(zhǎng)期應(yīng)激時(shí)，HPA軸糖皮質(zhì)激素的負(fù)反饋調(diào)節(jié)障礙，會(huì)持續(xù)促進(jìn)糖皮質(zhì)激素分泌，使脂肪和肌肉組織的脂肪動(dòng)員和肝糖異生加強(qiáng)，導(dǎo)致游離脂肪酸和血糖水平升高[25]。本研究結(jié)果表明，長(zhǎng)期熱應(yīng)激時(shí)，機(jī)體肝脂肪代謝受到顯著影響。

3.2 熱應(yīng)激對(duì)肉仔雞肝脂肪調(diào)控因子的影響

對(duì)于鳥(niǎo)類而言，肝是脂肪生成的主要場(chǎng)所[26]。家禽中甘油三脂主要在肝中合成后輸出，在皮下脂肪、肝及肌肉組織等器官中貯存[27-28]。FATP-1是重要的轉(zhuǎn)運(yùn)蛋白之一，參與脂肪酸跨膜轉(zhuǎn)運(yùn)和脂肪沉積[29]。報(bào)道證明，F(xiàn)ATP-1不但直接調(diào)節(jié)脂肪酸跨膜轉(zhuǎn)運(yùn)，而且催化細(xì)胞內(nèi)脂肪酸轉(zhuǎn)化為?；o酶A，優(yōu)先合成細(xì)胞內(nèi)甘油三脂[30-31]。有研究表明，F(xiàn)ATP-1敲除后顯著降低脂肪細(xì)胞甘油三脂的含量[31]。SREBPs為膜轉(zhuǎn)錄因子家族，能夠參與調(diào)節(jié)脂類合成基因的表達(dá)。SREBP-1c在高脂肪合成組織中高度表達(dá)，例如肝和脂肪組織[32]。LXR激活的SREBP-1c可通過(guò)轉(zhuǎn)錄激活脂肪合成過(guò)程中的相關(guān)基因，激活脂肪合成通路[33]。APOB在決定肝細(xì)胞合成和分泌VLDL的能力中起重要作用[29,34]。APOB是形成極低密度脂蛋白的必要成分，翻譯過(guò)程中和翻譯前修飾對(duì)VLDL合成、分泌、肝脂肪平衡很重要[35]。哺乳動(dòng)物及家禽上，LXRs在脂類和膽固醇代謝上起重要調(diào)節(jié)作用，例如膽汁酸和脂肪酸的合成[36-37]。此外，LXRα不僅直接調(diào)控脂肪生成轉(zhuǎn)錄因子的表達(dá)，而且直接調(diào)控脂肪合成酶的表達(dá)，加強(qiáng)肝脂肪酸的合成[38]。研究表明，飼喂高膽固醇日糧的小鼠缺乏LXRα，顯著增加肝膽固醇的沉積[39]。本試驗(yàn)結(jié)果表明，短期熱應(yīng)激沒(méi)有影響肝中脂肪調(diào)控因子基因表達(dá)，長(zhǎng)期熱應(yīng)激顯著上調(diào)肝中FATP-1、SREBP-1C、APOB和LXR脂肪調(diào)控因子基因的表達(dá)，說(shuō)明短期熱應(yīng)激沒(méi)有影響肝脂肪代謝，長(zhǎng)期熱應(yīng)激則顯著調(diào)動(dòng)了能量的重新分配，使肝脂肪合成增加。

3.3 熱應(yīng)激對(duì)肉仔雞肝CYP7A1信號(hào)通路的影響

肝是機(jī)體膽固醇代謝的主要部位，游離脂肪酸分泌到膽汁或者進(jìn)一步轉(zhuǎn)化為膽汁酸，該過(guò)程主要受微粒體酶CYP7A1調(diào)節(jié)[40]。CYP7A1主要參與肝由膽固醇合成膽汁酸和膽固醇的過(guò)程[41]。使用LXR激活劑TO-901317處理家禽肝細(xì)胞，顯著性上調(diào)SREBP1、FAS、CYP7A1基因表達(dá)[27]。FXR作為膽汁酸的感受器，在肝細(xì)胞中激活后，調(diào)節(jié)膽汁酸的合成、排出和腸道中重新吸收，從而維持體內(nèi)膽固醇的穩(wěn)態(tài)。在小鼠上，F(xiàn)XR抑制膽汁酸生成，而LXR促進(jìn)膽汁酸生成。細(xì)胞中高濃度的膽汁酸是有毒的，因此，F(xiàn)XR對(duì)維持機(jī)體膽汁酸水平有重要作用[42]。小鼠FXR缺乏導(dǎo)致肝生成膽汁酸含量增加，干擾脂肪代謝，導(dǎo)致肝變性、炎癥和纖維化[43-44]。本試驗(yàn)結(jié)果表明，短期應(yīng)激提高了肉仔雞血漿中的膽汁酸含量，但沒(méi)有影響肝中FXR、CYP7A1基因表達(dá)，說(shuō)明短期熱應(yīng)激時(shí)血漿中膽汁酸含量增加可能跟肝中膽汁酸合成途徑無(wú)關(guān)；而長(zhǎng)期熱應(yīng)激時(shí)，血漿中膽汁酸含量未受影響，但是肝中CYP7A1和FXR基因表達(dá)有升高的趨勢(shì)，這是否是機(jī)體對(duì)抗熱應(yīng)激的一種負(fù)反饋反應(yīng)，值得進(jìn)一步研究。

3.4 熱應(yīng)激對(duì)肉仔雞肝AMPK的影響

AMPK在調(diào)控整個(gè)機(jī)體能量代謝上起重要作用，脂肪細(xì)胞生成的激素,例如瘦素和脂聯(lián)素也會(huì)影響AMPK，瘦素可激活骨骼肌中AMPK增加脂肪酸氧化，同時(shí)脂聯(lián)素可以激活肝中的AMPK，增加糖的利用和脂肪酸氧化，抑制肝中葡萄糖的生成[45]。AMPK是主要的細(xì)胞能量狀態(tài)感受器，AMP與ATP之比增加會(huì)激活A(yù)MPK[46]。作為能量感受器和代謝傳感器，AMPK可影響鳥(niǎo)類肝脂肪代謝，在短期的調(diào)節(jié)過(guò)程中，AMPK磷酸化抑制ACCα，繼而抑制丙二酰輔酶A和脂肪酸合成，AMPK控制肝葡萄糖和脂肪代謝，影響整個(gè)機(jī)體的能量利用[47-48]。外周AMPK激活后會(huì)關(guān)閉機(jī)體ATP生成的代謝過(guò)程，例如脂肪組織和肝中游離脂肪酸氧化[49-50]。本研究表明，24 h熱應(yīng)激對(duì)肝AMPKα1基因的表達(dá)無(wú)顯著影響，而72 h熱應(yīng)激則顯著提高肝AMPKα1基因表達(dá)，這一變化模式跟肝中脂肪代謝相關(guān)分子的變化一致，說(shuō)明AMPK信號(hào)通路可能在應(yīng)激影響肝脂肪代謝的機(jī)制中起著重要作用。

4 結(jié) 論

熱應(yīng)激顯著降低肉仔雞生產(chǎn)性能，短期熱應(yīng)激對(duì)肉仔雞肝脂肪代謝影響有限，長(zhǎng)期熱應(yīng)激則顯著改變?nèi)庾须u肝脂肪代謝，AMPK可能參與熱應(yīng)激對(duì)肝脂肪代謝的調(diào)控。

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