早期断奶仔猪脂类代谢变化及分子调控机制研究

Study on lipid metabolism change and molecular regulation mechanism in early weaned piglets

为研究早期断奶仔猪体内脂类物质含量的变化,并分析肝脏和皮下脂肪组织中脂类代谢相关酶基因的表达水平,本文从代谢物和基因表达两方面阐明仔猪早期断奶过程的脂类代谢变化。试验选取4个窝的16头18日龄仔猪,每窝取1头仔猪进行采血,然后屠宰取样;另外12头进行断奶处理(早期断奶组),每4头一起饲养在与母猪栏环境相同的小栏中,饲喂配合饲料。母猪正常哺乳4个窝中剩余的仔猪(非早期断奶组)。在断奶后第1、3、7天(分别对应仔猪19、21、25日龄),从早期断奶组和非早期断奶组各取4头仔猪进行称重,采血后,屠宰采集肝脏、背最长肌、皮下脂肪等进行测定分析。结果表明:(1)早期断奶可显著降低仔猪血清甘油三酯(TG)、总胆固醇、高密度脂蛋白(HDL)和低密度脂蛋白(LDL)含量,且变化规律一致,均在断奶后第3天开始下降。与非断奶仔猪比较,仔猪在断奶后的第3、7天,血清TG含量分别降低了26.51%(P<0.05)和36.71%(P<0.05);胆固醇含量分别降低了26.18%(P<0.05)和40.93%(P<0.05);HDL含量分别降低了29.69%(P<0.05)和31.34%(P<0.05)。断奶仔猪血清LDL含量在断奶后的第1、3、7天分别比非断奶仔猪降低了24.05%(P<0.05)、37.65%(P<0.05)和23.17%(P<0.05)。(2)早期断奶处理可提高仔猪肝脏中ATP-柠檬酸裂解酶(ACL)基因的表达水平,但是乙酰CoA羧化酶(ACC)、脂肪酸合成酶(FAS)和固醇调节元件结合蛋白-1(SREBP-1)基因的表达水平降低,并表现为一致的变化趋势。与非断奶同日龄仔猪比较,在断奶后第1、3、7天,断奶仔猪肝脏ACL基因的表达水平分别提高113.33%(P<0.05)、106.15%(P<0.05)和100.00%(P<0.05),ACC表达水平分别降低26.67%(P<0.05)、53.51%(P<0.05)和33.86%(P<0.05),FAS表达水平分别降低72.57%(P<0.05)、85.71%(P<0.05)和27.66%(P<0.05),SREBP-1表达水平分别降低58.72%(P<0.05)、47.69%(P<0.05)和11.69%(P<0.05)。(3)早期断奶使仔猪皮下脂肪组织中甘油三酯脂肪酶(ATGL)的表达水平升高,使FAS的表达水平降低。在断奶后的第1、3、7天,脂肪组织中ATGL表达水平分别升高51.02%(P<0.05)、50.00%(P<0.05)和26.50%(P>0.05),FAS表达水平分别降低73.33%(P<0.05)、60.17%(P<0.05)和37.10%(P<0.05)。由此可见,仔猪在早期断奶过程中,机体通过新陈代谢动员脂肪,为其机体提供能量,从而保证供给平衡。

The purpose of this experiment was to study the changes of lipid content in early weaning piglets,analyze the gene expression level of lipid metabolism related enzymes in liver and subcutaneous fat tissue,and clarify the lipid metabolism changes in early weaning piglets from both metabolite and gene expression.Piglets from four litters were selected.At the 18-day old,four piglets were randomly selected from each litter,totally 16 piglets.After weighted,piglets were treated as follows.Firstly,four piglets,one from each litter were slaughtered for the sample collection.Secondly,the other 12 piglets were weaned(weaned group).According to the body weight and sex,every four per pen were raised in the same environment of sow pen and fed with complete feed.Meanwhile,the remaining piglets(unweaned group)were normally lactated by sows.At the 1st,3rd and 7th day after weaning(corresponding to the age of 19,21 and 25 days old),each 4 piglets were taken from the weaned group and the unweaned group for weighting and blood collection.And then the liver,subcutaneous fat of longissimus dorsi and other tissues were collected for analysis.Test results were as follows:(1)Serum concentrations of triglyceride(TG),cholesterol,high density lipoprotein(HDL)and low density lipoprotein(LDL)of early weaned piglets were significantly reduced(P<0.05).(2)The gene expression levels of acetyl-CoA(ACC),fatty acid synthetase(FAS)and SREBP-1 were decreased(P<0.05)in liver of weaned pigs.(3)The gene expression of FAS was decreased(P<0.05)in subcutaneous adipose tissue of early-weaned piglets,while adipose triacylglyceride lipase(ATGL)increased(P<0.05).Collectively,in the early weaning process,energy was provided for the body to ensure the supply balance by mobilizing fat.