Specialized hepatocyte-like cells regulate Drosophila lipid metabolism

Lipid metabolism is essential for growth and generates much of the energy needed during periods of starvation. In Drosophila, fasting larvae release large quantities of lipid from the fat body but it is unclear how and where this is processed. Here we identify the oenocyte as the principal cell type accumulating lipid droplets during starvation. Tissue-specific manipulations of the Slimfast amino-acid channel, the Lsd2 fat-storage regulator and the Brummer lipase indicate that oenocytes act downstream of the fat body. In turn, oenocytes are required for depleting stored lipid from the fat body during fasting. Hence, lipid-metabolic coupling between the fat body and oenocytes is bidirectional. When food is plentiful, oenocytes have critical roles in regulating growth, development and feeding behaviour. In addition, they specifically express many different lipid-metabolizing proteins, including Cyp4g1, an omega-hydroxylase regulating triacylglycerol composition. These findings provide evidence that some lipid-processing functions of the mammalian liver are performed in insects by oenocytes.     

葛根素对脂肪细胞糖脂代谢作用研究

探讨葛根素对脂肪细胞糖、脂代谢的影响.建立3T3-L1脂肪细胞IR模型,葡萄糖氧化酶法测定葛根素处理48 h后培养液中葡萄糖残存量、铜试剂显色法测定游离脂肪酸浓度.与模型组比较,葛根素高、低剂量组葡萄糖消耗量显著增加(P<0.05),游离脂肪酸水平呈现降低趋势.葛根素明显增加脂肪细胞的葡萄糖消耗,对TNF-α诱导的脂肪分解无明显作用.     

Effects of over-expressing resistin on glucose and lipid metabolism in mice

Resistin, a newly discovered peptide hormone mainly secreted by adipose tissues, is present at high levels in serum of obese mice and may be a potential link between obesity and insulin resistance in rodents. However, some studies of rat and mouse models have associated insulin resistance and obesity with decreased resistin expression. In humans, no relationship between resistin level and insulin resistance or adiposity was observed. This suggests that additional studies are necessary to determine the specific role ofresistin in the regulation of energy metabolism and adipogenesis. In the present study, we investigated the effect of resistin in vivo on glucose and lipid metabolism by over-expressing resistin in mice by intramuscular injection of a recombinant eukaryotic expression vector pcDNA3.1-Retn encoding porcine resistin gene. After injection, serum resistin and serum glucose （GLU） levels were significantly increased in the pcDNA3.1-Retn-treated mice; there was an obvious difference in total cholesterol （TC） level between the experiment and the control groups on Day 30. In pcDNA3.1-Retn-treated mice, both free fatty acid （FFA） and high density lipoprotein （HDL） cholesterol levels were markedly lower than those of control, whereas HDL cholesterol and triglyceride （TG） levels did not differ between the two groups. Furthermore, lipase activity was expressly lower on Day 20. Our data suggest that resistin over-expressed in mice might be responsible for insulin resistance and parameters related to glucose and lipid metabolism were changed accordingly.     

低聚木糖降脂作用研究

采用喂食高脂饲料的方法建立高脂血症小鼠模型,观察低聚木糖对高脂血症成年小鼠血清总胆固醇(TC)、血清总甘油三脂(TG)和高密度胆固醇(HDL-c)含量的影响.结果表明,低聚木糖可有效降低高脂血症小鼠血清TC、TG含量,但对低密度胆固醇(LDL-c)含量的升高无明显效果.     

Influence of cosmic radiation on lymphocyte micronucleus, serum lipid peroxide and antioxidation capacity in aircrew members

This study looks into the influence of cosmic radiation at high altitudes on human bodies. Results reveal that the cytokinesis-block micronuclei (CBMN) and conventional cultured micronuclei in peripheral blood lymphocytes, serum levels of lipid peroxide, Superoxide dismutase, and the total antioxidation capacity by chemical colorimetry all increased significantly in aircrew members. There exists a linear relationship between the CBMN and the average annual effective doses of radiation received or the average annual flying hours. With both of them, a trend shows that the serum lipid peroxide levels increase as well. Either the lipid peroxide or CBMN can sensitively reflect the recent changes in flight load. These findings indicate that cosmic radiation impairs the stability of chromosomes and genome, and induces lipid oxidative damage in aircrews; Lymphocyte CBMN and serum lipid peroxide can be used as monitoring indicators in the cosmic radiation protection for aircrew members.     

NNK结构与其代谢机理和致癌性研究

目的从化学结构的角度研究4-(N-甲基-N-亚硝胺)-1-(3-吡啶基)-丁酮(4-(methylnitro-samino)-1-(3-pyridyl)-1-butanone,NNK)的代谢机理和致癌性。方法利用HyperChem计算化学软件,在扩展休克分子轨道法的基础上进行计算,分析计算结果,阐述NNK的代谢机理以及其致癌性。结果前线轨道的能量差很小,而且LUMO能量低于原子轨道能量,决定了NNK代谢反应既可以接受电子作为氧化剂发生还原反应,也可以提供电子作为还原剂发生氧化反应。电荷分布的局部集中,为亲电试剂的进攻提供了便利。无论是NNK还是其初级代谢产物,高风险诱变性和致癌性基团的存在是其具有潜在致癌性的基础。结论从计算结果可以对NNK的代谢机理和致癌性作出令人满意的合理解释。     

Insulin signalling and the regulation of glucose and lipid metabolism.

The epidemic of type 2 diabetes and impaired glucose tolerance is one of the main causes of morbidity and mortality worldwide. In both disorders, tissues such as muscle, fat and liver become less responsive or resistant to insulin. This state is also linked to other common health problems, such as obesity, polycystic ovarian disease, hyperlipidaemia, hypertension and atherosclerosis. The pathophysiology of insulin resistance involves a complex network of signalling pathways, activated by the insulin receptor, which regulates intermediary metabolism and its organization in cells. But recent studies have shown that numerous other hormones and signalling events attenuate insulin action, and are important in type 2 diabetes.     

MSTN抗体联合中强度爬梯抗阻运动对IR大鼠脂代谢的影响

探讨MSTN抗体联合中等强度爬梯抗阻力运动干预对胰岛素抵抗(IR)大鼠脂质代谢的改善作用。首先制备MSTN抗体;其次在建立大鼠IR模型后,用MSTN抗体、中强度爬梯运动以及二者联合分别干预8周后取材分析血脂指标TC,HDL,LDL,TG,FFA等变化。WB、免疫组化等实验结果表明,制备的MSTN抗体可满足后续实验要求;OGTT和IST实验结果表明成功建立IR模型;分析大鼠血脂指标结果发现MSTN抗体、中强度爬梯抗阻运动对IR模型大鼠的脂质代谢均有改善作用,但二者联合改善效果更加显著,其中在HDL,LDL,FFA等指标较其他两组有显著性差异(p0.05,p0.01)。该项抗体联合运动的研究为IR患者促进脂质代谢提供了新的思路和实验依据。     

Effects of hypoxic exercise training on microRNA expression and lipid metabolism in obese rat livers

To investigate the effects of hypoxic exercise training on microRNA （miRNA） expression and the role of miRNA expression in regulating lipid metabolism, 20 dietary-induced obese SD rats were divided into a normoxic sedentary group （N, n=10） and a hypoxic exercise training group （H, n=10）. After four weeks, measurements were taken of body weight, body length, fat mass, serum lipid concentration, miRNAs differentially expressed in rat liver, and gene and protein expression levels of perexisome proliferator activated receptor a （PPARα）, fatty acid synthetase （FAS）, and carnitine palmitoyl transferase 1A （CPTIA） in rat liver. Body weight, Lee＇s index, fat mass, fat/weight ratio, and serum levels of total cholesterol （TC） and high density lipoprotein cholesterol （HDL-C） were all significantly lower in the H group than in the N group （P〈0.01）. Six miRNAs expressed significantly differently in the liver （P〈0.05）. Specifically, expression levels of miR-378b were significantly lower in the H group than in the N group （P〈0.05）. Compared with the normoxic sedentary group, hypoxic exercise training resulted in a lower ratio of FAS mRNA to CPTIA mRNA （P〈0.05）, as well as lower CPT1A protein levels （P〈0.01）, while a higher ratio of FAS to CPT1A protein levels （P〈0.01） was observed. In conclusion, hypoxic training may elevate the resistance of high fat diet induced obesity in rats by reducing the expression of miR-378b, and decrease the fatty acid mitochondrial oxidation in obese rat livers by decreasing the protein expression of CPTIA and increasing the protein expression ratio of FAS/CPTIA.     

长期有氧运动对肥胖大鼠血液及肝脏糖脂代谢的影响

将15月龄SD雄性大鼠分为正常对照组(CON)、高脂饮食组(HFD)和高脂饮食运动组(HFD+CE)。实验结束处死后取材,测定各组大鼠空腹血糖(PBG)、血清甘油三酯(TG)、胆固醇(TC)、高密度脂蛋白(HDL-C)、低密度脂蛋白(LDL-C)、肝脏TG、游离脂肪酸(FFA)及肝糖原(LG)浓度,空腹胰岛素水平(FINS)及胰岛素抵抗指数(HOMA-IR)。结果显示:与CON组相比,HFD组大鼠HDL-C、LG显著降低(P<0.01,P<0.05),PBG无显著性变化(P>0.05),TG、FINS、HOMA-IR均显著升高(P<0.05),血清TC、LDL-C、L-TG、L-FFA升高极显著(P<0.01);与HFD组相比,HFD+CE组大鼠HDL-C升高极显著(P<0.01),TC、PBG无显著变化(P>0.05),LG、L-TG、FINS、HOMA-IR均显著下降(P<0.05),LDL-C、L-FFA降低极显著(P<0.01)。结论:长期有氧运动对高脂诱导的肥胖大鼠具有明显降脂作用,并能降低血清胰岛素水平,改善胰岛素抵抗和肝脏糖脂代谢紊乱。