两株乳杆菌体内外降胆固醇的筛选及相关机制的研究

发布时间：2018-04-28 19:03

本文选题：益生菌 + 乳酸菌　；参考：《中南大学》2010年博士论文

【摘要】： 目的从正常人肠道粪便中分离的潜在目的菌中筛选出有降胆固醇能力的菌株,并进行鉴定。方法通过改良的胆固醇MRS培养基作为筛选模型进行目的菌的筛选,并对降胆固醇能力较好的菌株进行初步鉴定。结果经过初筛和复筛,筛选出4株降胆固醇能力在30%以上的菌株,降解率分别为M7-544.7%,M2-134.2%,M10-2-8 32.5%,MM1-16为32.4%；将M7-5和M2-1进行鉴定,M7-5为发酵乳酸杆菌,M2-1为植物乳酸杆菌。结论菌株M7-5和M2-1在体外有较强的降胆固醇能力,经鉴定分别为发酵乳杆菌及植物乳杆菌,有待于将其应用于动物体内进行进一步研究。目的观察2株乳酸杆菌对高脂饮食喂养的SD大鼠胆固醇代谢的影响,评价其对高脂饮食喂养的SD大鼠降胆固醇作用的有效性和安全性,从而为筛选到有利于人体降胆醇的功能菌提供依据。方法 40只SD大鼠随机分为4组,K组喂养普通饲料,E、F、I组喂养改良高脂饲料,同时以2株乳酸菌干预,E组是M2-1,F组是M7-5。I组不加益生菌,为高脂模型组,6周末处死大鼠,检测大鼠血脂指标,血清总胆叶酸、肝脂质、粪脂质,体重增加量,Lee指数,肝组织病理学检查及血清谷丙转氨酶等指标。结果 l、高脂模型组血清TC、TG、LDL-C较正常对照组比均升高(P0.05),差异有显著性,乳酸菌E组和F组比高脂模型组下降,以F组效果最好,差异有显著性。 2、第4周和第6周,高脂模型组血胆汁酸与正常对照组比升高,但无显著性差异,益生菌E组较高脂模型组下隆,差异有统计学意义。 3、粪胆汁酸和胆固醇高脂模型组升高,与正常对照组比,P0.05,差异有显著性；乳酸菌E组的胆汁酸和F组的胆固醇均升高,分别与高脂模型组及正常对照组比较,P0.05,差异有显著性。 4、高脂模型组Lee's指数比正常对照组高,P0.05,差异有显著性；乳酸菌E组和F组均比高脂模型组低,比正常组高,尤其在第6周,F组与高脂模型组比差异有显著性(P0.05)。 5、高脂模型组及乳酸菌E组和F组,每周体重增加量较正常对照组高,有显著性差异；第6周乳酸菌F组体重增加量下降,比高脂模型组降低,差异有显著性。 6、肝病理检查HE染色高脂模型组肝脂肪变性较明显,与正常对照组比有显著性差异而乳酸菌E组和F组不明显,与正常对照组无差异。 7、高脂模型组血清谷丙转氨酶升高,但分别与其他各组比较无显著性差异。结论 1、改良高脂饮食配方连续喂养SD大鼠6周,可以成功造出高脂固醇血症模型。 2、对两株乳杆菌M7-5和M2-1对SD大鼠高脂血症模型有降胆固醇作用,以M7-5效果更好。 3两株乳酸菌可能的降脂机制是减少了肝脂质沉积和增加了粪脂的排泄,它们的机制可能不完全相同,前者以增加粪胆固醇的排泄为主,而后者则以增加粪胆汁酸的排出为主。目的探讨两株乳酸菌影响SD大鼠饮食性高脂血症脂质代谢的可能机制方法实验动物、分组、建模和干预方法同第2章,第6周末处死大鼠,留取各组肝脏及回肠粘膜上皮标本,用实时荧光定量PCR技术检测肝脏孤核受体FXR及细胞表面受体ABCA1和ABCG5基因mRNA的表达,检测回肠粘膜上皮组织LXRa、ABCA1和ABCG5基因mRNA的表达。结果 1、高脂模型组,肝组织FXR受体及LXRα受体,回肠粘膜上皮组织LXRα、ABCA1及ABCG5受体与正常对照组比较差异有统计学意义(P0.05),而肝组织ABCG5表达无明显上调。 2、乳酸菌E组(植物乳肝菌M2-1)肝组织FXR表达与高脂模型组相比显著下调,LXRα则显著上调,回肠粘肠上皮组织细胞表面受体ABCG5上调(P0.05)。 3、乳酸菌F组(发酵乳杆菌M7-5)肝组织孤核受体FXR与高脂模型组比表达下调,肝组织LXRα、ABCG5,回肠粘膜上皮组织LXRα、ABCA1、ABCG5与高脂膜型组相比均上调,有统计学意义(P0.05)。结论 1、发酵乳杆菌M7-5和植物乳杆菌M2-1可降低高脂饮食喂养的SD大鼠血清胆固醇。 2、发酵乳杆菌M7-5和植物乳杆菌M2-1作用靶点可能涉及了肝组织和回肠粘膜的某些受体。前者抑制肝脏FXR的表达,可能上调肝、肠粘膜组织LXR2、ABCA1、ABCG5的表达,降胆固醇作用主要以增加体内胆固醇的排泄为主。后者则显著抑制肝组织FXR的表达,上调肝组织LXRa回肠粘膜上皮组织ABCG5的表达,其降胆固醇作用主要在于增加体内胆汁酸的合成,加速胆汁酸的排泄为主。
[Abstract]:objective
A cholesterol lowering strain was screened from the potential bacteria isolated from the feces of normal people and identified.
Method
The improved cholesterol MRS medium was used as a screening model to screen the target bacteria, and the strains with good cholesterol lowering ability were primarily identified.
Result
After screening and screening, 4 strains of cholesterol lowering ability were screened over 30%. The degradation rates were M7-544.7%, M2-134.2%, M10-2-8 32.5% and MM1-16 32.4%, M7-5 and M2-1 were identified, M7-5 was lactobacillus fermented and M2-1 was Lactobacillus.
conclusion
Strain M7-5 and M2-1 have a strong ability to reduce cholesterol in vitro. They are identified as Lactobacillus fermenting and Lactobacillus plantarum, which need to be further studied in animals.
objective
The effect of 2 lactobacilli on the cholesterol metabolism of SD rats fed by high fat diet was observed, and the efficacy and safety of the cholesterol lowering effect on SD rats fed by high fat diet were evaluated.
Method
40 SD rats were randomly divided into 4 groups. Group K was fed with common feed, E, F, and I group were fed with improved high fat diet, while 2 strains of lactic acid bacteria were fed, group E was M2-1, group F was M7-5.I group without probiotics, high fat model group, and rats were killed at the end of 6 weeks. The blood lipid index, serum total gallic acid, liver lipid, fecal lipid, weight gain, Lee index, liver tissue were detected. Pathological examination and serum glutamic pyruvic transaminase.
Result
L, the serum level of TC, TG and LDL-C in the high fat model group was higher than that of the normal control group (P0.05). The difference was significant. The E and F groups of lactic acid bacteria and F group were lower than those of the high fat model group. The effect of F group was the best, the difference was significant.
In the 2, fourth and sixth weeks, the blood bile acid in the high fat model group was higher than that in the normal control group, but there was no significant difference. The higher lipid model group in the probiotic E group had a significant difference.
3, the fecal bile acid and the cholesterol high fat model group increased, compared with the normal control group, P0.05, the difference was significant, the cholesterol of the E group of lactic acid bacteria and the cholesterol in the F group increased, respectively, compared with the high fat model group and the normal control group, respectively, the difference was significant.
4, the Lee's index in the high fat model group was higher than that in the normal control group, and the difference was significantly higher than that of the normal control group. The E group and the F group of lactic acid bacteria were lower than the high fat model group and higher than those of the normal group. Especially in the sixth weeks, the difference between the F group and the high fat model group was significantly higher than that of the F group (P0.05).
5, the weight gain of the high fat model group and the E group and the F group was higher than that of the normal control group, and there was a significant difference. The weight gain decreased in the group F of lactic acid bacteria in sixth weeks, which was significantly lower than that in the high fat model group.
6, liver pathology examination HE staining high fat model group liver fatty degeneration is more obvious, compared with the normal control group, there is significant difference, but the lactic acid bacteria group E and F group is not obvious, and no difference with the normal control group.
7, serum alanine aminotransferase increased in the high fat group, but there was no significant difference between the two groups.
conclusion
1, the high fat diet formula can be used to continuously produce SD rats for 6 weeks, and the hyperlipidemic model can be successfully produced.
2, two strains of Lactobacillus M7-5 and M2-1 have a cholesterol lowering effect on the hyperlipidemia model of SD rats, with a better M7-5 effect.
3 the possible mechanism of lipid lowering in two strains of lactic acid bacteria is to reduce the liver lipid deposition and increase excretion of fecal fat. Their mechanisms may not be the same. The former mainly increases excretion of fecal cholesterol, while the latter mainly increases excretion of fecal bile acid.
objective
The possible mechanism of two strains of lactic acid bacteria affecting lipid metabolism in SD rats with diet induced hyperlipidemia
Method
Experimental animals, groups, modeling and intervention methods were killed in second chapters and sixth weekends. The liver and ileum mucosa epithelial specimens were left in each group. The expression of FXR of the liver nucleus receptor and the expression of mRNA of the cell surface receptor ABCA1 and ABCG5 gene were detected by real time fluorescence quantitative PCR, and the expression of LXRa, ABCA1 and ABCG5 gene mRNA in the intestinal mucosa of the ileum was detected.
Result
1, high fat model group, FXR receptor and LXR alpha receptor in liver tissue, LXR alpha, ABCA1 and ABCG5 receptor in ileum mucosa were significantly different from those of normal control group (P0.05), but the expression of ABCG5 in liver tissue was not significantly up.
2, the expression of FXR in the group of lactic acid bacteria E (M2-1) was significantly lower than that in the high fat model group, while the LXR alpha was up significantly up, and the cell surface receptor ABCG5 of the intestinal mucosa was up regulated (P0.05).
3, lactic acid bacteria F group (Lactobacillus fermented M7-5) liver tissue nucleus receptor FXR and high fat model group down down expression, the liver tissue LXR alpha, ABCG5, the ileum mucosa epithelial tissue LXR alpha, ABCA1, ABCG5 and higher fat membrane group up up, there is statistical significance (P0.05).
conclusion
1, Lactobacillus fermentum M7-5 and Lactobacillus plantarum M2-1 can reduce the serum cholesterol of SD rats fed with high-fat diet.
2, the target of Lactobacillus fermented M7-5 and Lactobacillus plantarum M2-1 may involve some receptors in the liver and ileum mucosa. The former inhibits the expression of FXR in the liver, may up-regulation the expression of LXR2, ABCA1, and ABCG5 in the liver and intestinal mucosa, and the main cholesterol lowering effect is mainly to increase the excretion of cholesterol in the body. The latter significantly inhibits the FXR in the liver tissue. Expression, up regulation of the expression of ABCG5 in the epithelial tissue of the LXRa ileum of the liver. Its cholesterol lowering effect is mainly to increase the synthesis of bile acids in the body and to accelerate the excretion of bile acids.

【学位授予单位】：中南大学
【学位级别】：博士
【学位授予年份】：2010
【分类号】：R371

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