沉默PLIN1基因与异丙肾上腺素对3T3-L1脂肪细胞脂解的机制探究

目的 研究沉默PLIN1基因与异丙肾上腺素(ISO)联合作用对3T3-L1脂肪细胞脂解的影响及机制探讨。方法 sh-PLIN1干扰载体成功转染后,以浓度为10μM的ISO处理3T3-L1脂肪细胞。采用油红O进行脂滴染色,观察脂滴形态;采用酶学方法测定甘油三酯(TG)和甘油含量,了解细胞脂解情况;采用Western-Blot法检测脂肪细胞中围脂滴蛋白A(PLIN1A)、脂肪甘油三酯脂肪酶(ATGL)、激素敏感性脂肪酶(HSL)和其磷酸化蛋白(p-HSL)的表达水平;双抗体夹心ABC-ELISA法检测细胞中环磷酸腺苷(cAMP)和蛋白激酶A(PKA)的浓度。结果 与空白组比较,ISO+sh-PLIN1组和ISO组脂滴变小,TG含量降低,甘油含量升高,有统计学意义(P<0.01)。同时,ISO+sh-PLIN1组和 sh-PLIN1组中ATGL 表达量均升高,有统计学意义(P<0.05)。ISO+sh-PLIN1转染组和ISO组中HSL、p-HSL、cAMP及 PKA 的表达量均上调(P<0.05)。结论 ISO促进脂解作用可能是cAMP/PKA通路介导,增加HSL和p-HSL的表达量来实现,而cAMP/PKA信号通路不能介导沉默PLIN1的促脂解作用。     

Carnosic acid inhibits TLR4-MyD88 signaling pathway in LPS-stimulated 3T3-L1 adipocytes

BACKGROUND/OBJECTIVES

Carnosic acid (CA), found in rosemary (Rosemarinus officinalis) leaves, is known to exhibit anti-obesity and anti-inflammatory activities. However, whether its anti-inflammatory potency can contribute to the amelioration of obesity has not been elucidated. The aim of the current study was to investigate the effect of CA on Toll-like receptor 4 (TLR4) pathways in the presence of lipopolysaccharide (LPS) in 3T3-L1 adipocytes.

MATERIALS/METHODS

3T3-L1 adipocytes were treated with CA (0-20 µM) for 1 h, followed by treatment with LPS for 30 min; mRNA expression of adipokines and protein expression of TLR4-related molecules were then measured.

RESULTS

LPS-stimulated 3T3-L1 adipocytes showed elevated mRNA expression of tumor necrosis factor (TNF)-α, interleukin-6, and monocyte chemoattractant protein-1, and CA significantly inhibited the expression of these adipokine genes. LPS-induced up regulation of TLR4, myeloid differentiation factor 88, TNF receptor-associated factor 6, and nuclear factor-κB, as well as phosphorylated extracellular receptor-activated kinase were also suppressed by pre-treatment of 3T3-L1 adipocytes with CA.

CONCLUSIONS

Results of this study suggest that CA directly inhibits TLR4-MyD88-dependent signaling pathways and decreases the inflammatory response in adipocytes.     

Pear pomace water extract inhibits adipogenesis and induces apoptosis in 3T3-L1 adipocytes

Obesity occurs when a person''s calorie intake exceeds the amount of energy burns, which may lead to pathologic growth of adipocytes and the accumulation of fat in the tissues. In this study, the effect and mechanism of pear pomace extracts on 3T3-L1 adipocyte differentiation and apoptosis of mature adipocytes were investigated. The effects of pear pomace extract on cell viability and the anti-adipogenic and proapoptotic effects were investigated via MTT assay, Oil red O staining, western blot analysis and apoptosis assay. 3T3-L1 preadipocytes were stimulated with DMEM containing 10% FBS, 0.5 mM 3-isobutyl-1-methylxanthine (IBMX), 5 µg/ml insulin and 1 µM dexamethasone for differentiation to adipocytes. 3T3-L1 cells were cultured with PBS or water extract of pear pomace. Water extract of pear pomace effectively inhibited lipid accumulations and expressions of PPAR-γ and C/EBPα in 3T3-L1 cells. It also increased expression of p-AMPK and decreased the expression of SREBP-1c and FAS in 3T3-L1 cells. The induction of apoptosis was observed in 3T3-L1 cells treated with pear pomace. These results indicate that pear pomace water extract inhibits adipogenesis and induces apoptosis of adipocytes and thus can be used as a potential therapeutic substance as part of prevention or treatment strategy for obesity.     

Soluble extract of soybean fermented with Aspergillus oryzae GB107 inhibits fat accumulation in cultured 3T3-L1 adipocytes

BACKGROUND/OBJECTIVESThis study was conducted to investigate the effects of fermented soybean (FS) extract on adipocyte differentiation and fat accumulation using cultured 3T3-L1 adipocytes.MATERIALS/METHODS3T3-L1 adipocytes were treated with FS and nonfermented soybean (NFS) extract during differentiation for 10 days in vitro. Oil red O staining was performed and glycerol-3-phosphate dehydrogenase (GPDH) activity was measured for analysis of fat accumulation. Expressions of adipogenic genes were measured.RESULTSSoluble extract of soybean fermented with Aspergillus oryzae GB107 contained higher levels of low-molecular-weight protein than conventional soybean protein did. FS extract (50 µg/ml) inhibited adipocyte differentiation and fat accumulation during differentiation of 3T3-L1 preadipocytes for 10 days in vitro. Significantly lower GPDH activity was observed in differentiated adipocytes treated with the FS extract than those treated with NFS extract. Treatment with FS extract resulted in decreased expression levels of leptin, adiponectin, and adipogenin genes, which are associated with adipogenesis.CONCLUSIONSThis report is the first to demonstrate that the water-soluble extract from FS inhibits fat accumulation and lipid storage in 3T3-L1 adipocytes. Thus, the soybean extract fermented with A. oryzae GB107 could be used to control lipid accumulation in adipocytes.     

磷脂酰肌醇3-激酶/蛋白激酶B信号转导通路在苯醌致HL-60细胞增殖过程中的作用

目的 探讨磷脂酰肌醇3-激酶/蛋白激酶B(PI3K/Akt)信号转导通路在苯醌(BQ)致HL-60细胞增殖中的作用.方法 取对数生长期的HL-60细胞,分为对照组(PBS处理细胞)、BQ染毒组(3 μmol/L BQ染毒)、LY294002+BQ染毒组(3μmol/L BQ染毒前加20 μmol/L LY294002),用alamar blue 法检测细胞增殖率,免疫印迹(Western blot)法检测细胞内p-Akt、Akt蛋白的表达,流式细胞仪检测细胞周期情况.结果 BQ染毒组细胞增殖率(185.00%±30.00%)和S、G2期细胞比例(分别为48.23%±1.37%、15.40%±1.21%)均高于对照组(分别为100.00%±0.00%、42.47%±0.45%、5.40%±0.40%),G1期细胞比例(36.37%±0.40%)低于对照组(52.13%±0.75%),差异均有统计学意义(P＜0.05);BQ染毒组细胞内p-Akt蛋白表达量明显高于对照组,差异有统计学意义(P<0.05),Akt表达量与对照组的差异无统计学意义(P＞0.05).LY294002+BQ染毒组细胞增殖率(82.59%±15.00%)和S、G2期细胞比例(分别为42.03%±0.50%、3.87%±0.47%)比BQ染毒组低,G1期细胞比例(54.43%±0.40%)比BQ染毒组高,差异均有统计学意义(P<0.05),细胞内p-Akt蛋白表达量明显低于BQ染毒组,差异有统计学意义(P<0.05);Akt蛋白表达量与BQ染毒组的差异无统计学意义(P>0.05).结论 PI3K/Akt信号转导通路在BQ致HL-60细胞增殖过程中可能起着重要作用.

Abstract：

Objective To explore the effects of phosphatidylinositol 3-kinase/ Serine-threonine kinase (PI3K/Akt) signal pathway on the proliferation of HL-60 cells exposed to benzoquinone (BQ). Methods HL-60 cells were divided into 3 groups: control group (treated with PBS), BQ group (treated with 3 μmol/L BQ) and LY294002 plus BQ group (treated with 20 μmol/L LY294002 plus 3 μmol/L BQ). The cell proliferation was measured with alamar blue dye assay. Western blot assay was used to detect the expression of p-Akt and Akt proteins and flow cytometer was used to observe the cell cycle. Results The cell proliferation rate and the cell proportion in the S, G2 phase of BQ group were 185.00%±30.00%, 48.23%±1.37% and 15.40%±1.21%, respectively, which were significantly higher than those ( 100.00%±0.00%, 42.47%±0.45% and 5.40%±0.40%) of control group (P<0.05 ). But the cell proportion rate (36.37%±0.40% ) in the G1 phase in BQ group was significantly lower than that (52.13%±0.75% ) in control group (P<0.05). The expression level of p-Akt protein in BQ group was significantly higher than that in control group (P<0.05). The cell proliferation rate and the cell proportion in the S, G2 phase of LY294002 plus BQ group were 82.59%±15.00%, 42.03%±0.50% and 3.87%± 0.47%, respectively, which were significantly lower than those of BQ group (P<0.05). But the cell proportion rate (54.43%±0.40%) in the G1 phase in LY294002 plus BQ group was significantly higher than that in BQ group (P<0.05 ). Conclusion The PI3K/Akt signal pathway may play an important role in the proliferation of HL-60 cells exposed to BQ.     

儿茶素和咖啡碱组合对3T3-L1细胞增殖及脂肪代谢的影响

目的研究对儿茶素和咖啡碱对3T3-L1细胞的增殖及脂肪代谢的影响。方法采用四甲基偶氮唑盐比色法(MTT)检测对3T3-L1细胞增殖的影响;3T3-L1细胞诱导分化8d后,对各组细胞进行油红O染色并测定细胞内甘油三酯(TG)含量;细胞分化12d后,添加儿茶素和咖啡碱组合或同时添加去甲肾上腺素(NA)作用24h,分析各组细胞内脂肪分解。结果儿茶素能明显抑制3T3-L1细胞的增殖;儿茶素和咖啡碱组合能明显抑制3T3-L1细胞分化后,细胞内TG的沉积,且在相同儿茶素浓度下,咖啡碱浓度越高抑制效果越明显。咖啡碱明显提高NA诱导成熟脂肪细胞脂解的能力,且呈剂量效应关系。结论儿茶素和咖啡碱组合能够抑制脂肪细胞增殖和甘油三酯积聚,咖啡碱促进激素诱导脂肪细胞中脂肪分解。     

Release of a specific set of proinflammatory adipokines by differentiating 3T3-L1 cells

ObjectiveAlthough there is a large amount of data on the role of preadipocytes in promoting the release of proinflammatory cytokines and chemokines in response to macrophage-derived cytokines, the direct role of insulin and saturated fatty acids in modulating the release of inflammatory cytokines by cells differentiating along the adipocytic lineage is less understood.Methods3T3-L1 murine preadipocyte cells were cultured for 3 d in a proliferating medium in the presence or absence of insulin 0.2 nmol/L plus palmitic acid 1 μmol/L. In parallel, 3T3-L1 cells were cultured in a differentiation medium containing dexamethasone, insulin, and isobutyl methyl xanthine in the absence or presence of palmitic acid for 3 d. The levels of several cytokines were evaluated in the culture supernatants by a bead-based multiplex immunoassay.ResultsUnder the proliferation conditions, insulin plus palmitic acid promoted a significant increase in the release of interleukin-6, keratinocyte-derived chemokine (KC)/chemokine ligand-1 (CXCL-1), monocyte chemotactic protein-1 (MCP-1), and regulated and normal T cells expressed and presumably secreted (RANTES) by 3T3-L1 preadipocytes. Of note, the release of KC/CXCL-1, MCP-1, and RANTES increased significantly with adipocytic differentiation, and the addition of palmitic acid to differentiating 3T3-L1 cells resulted in a further significant promotion of KC/CXCL1, MCP-1, and RANTES, coupled to the increase of additional cytokines.ConclusionsTaken together, these data show that a restricted common group of cytokines/chemokines (KC/CXCL1, MCP-1, and RANTES) is upregulated in proliferating and differentiating 3T3-L1 adipocytes in response to insulin and palmitic acid and that differentiating adipocytes respond with an increased range of cytokines with respect to proliferating 3T3-L1 preadipocytes.     

单唾液酸神经节苷脂对2,5-己二酮诱导的PC12细胞凋亡的影响

目的研究单唾液酸神经节苷脂(GM1)对2,5-己二酮(2,5-HD)诱导PC12细胞凋亡的保护作用,并探讨其作用机制。方法以PC12细胞为神经元的细胞模型,2,5-HD、GM1及磷脂酰肌醇3-激酶(PI3-K)抑制剂LY294002单独或联合处理细胞,MTT法检测细胞存活率,Giemsa染色法观察细胞形态,琼脂糖凝胶电泳检测DNA断裂,流式细胞术(FCM)检测细胞凋亡率,免疫印迹检测蛋白激酶B(Akt)和磷酸化-Akt(P-Akt)蛋白的表达。结果GM1可以有效地改善凋亡引起的细胞形态学改变,提高细胞存活率(P<0.05),最高可提高36.35%;降低DNA断裂程度,减少凋亡率(P<0.001),最明显可降低69.36%。GM1能够促进Akt磷酸化,LY294002可以阻断这种作用。结论GM1对2,5-HD诱导的PC12细胞凋亡有保护作用。该保护作用可能是通过启动PI3-K信号通路,激活Akt及其下游信号而产生的。     

The protective effects of steamed ginger on adipogenesis in 3T3-L1 cells and adiposity in diet-induced obese mice

BACKGROUND/OBJECTIVESThe steamed ginger has been shown to have antioxidative effects and a protective effect against obesity. In the present study, we investigated the effects of ethanolic extract of steamed ginger (SGE) on adipogenesis in 3T3-L1 preadipocytes and diet-induced obesity (DIO) mouse model.MATERIALS/METHODSThe protective effects of SGE on adipogenesis were examined in 3T3-L1 adipocytes by measuring lipid accumulations and genes involved in adipogenesis. Male C57BL/6J mice were fed a normal diet (ND, 10% fat w/w), a high-fat diet (HFD, 60% fat w/w), and HFD supplemented with either 40 mg/kg or 80 mg/kg of SGE for 12 weeks. Serum chemistry was measured, and the expression of genes involved in lipid metabolism was determined in the adipose tissue. Histological analysis and micro-computed tomography were performed to identify lipid accumulations in epididymal fat pads.RESULTSIn 3T3-L1 cells, SGE significantly decreased lipid accumulation, with concomitant decreases in the expression of adipogenesis-related genes. SGE significantly attenuated the increase in body, liver, and epididymal adipose tissue weights by HFD. Serum total cholesterol and triglyceride levels were significantly lower in SGE fed groups compared to HFD. In adipose tissue, SGE significantly decreased adipocyte size than that of HFD and altered adipogenesis-related genes.CONCLUSIONSIn conclusion, steamed ginger exerted anti-obesity effects by regulating genes involved in adipogenesis and lipogenesis in 3T3-L1 cell and epididymal adipose tissue of DIO mice.     

Effect of yellow capsicum extract on proliferation and differentiation of 3T3-L1 preadipocytes

ObjectivesTo evaluate the effect of effect of Yellow Capsicum extract (YCE) that is rich in capsaicin on the proliferation and differentiation of 3T3-L1 preadipocytes in vitro.Methods3T3 L1 cells that were exposed to differentiation-inducing medium containing high glucose DMEM (Dulbecco's Modified Eagle’s Medium) and subsequently were treated with capsaicin and YCE for their effect on adipocyte differentiation, changes in their triglyceride content, leptin secretion, expression of lipoprotein lipase, PPARγ, and CCAAT/enhancer-binding protein alpha (C/EBPα).ResultsBoth YCE and capsaicin inhibited proliferation and differentiation 3T3-L1 preadipocytes and suppressed accumulation of intracellular triglyceride in a dose-dependent manner. In addition, a significant decrease in the expression of lipoprotein lipase (LPL), leptin, PPARγ, and C/EBPα was noted in 3T3-L1 preadipocytes when induced to differentiate by YCE and Capsaicin.ConclusionsThe potent inhibitory action of YCE and Capsaicin on the differentiation of 3T3-L1 preadipocyte observed suggests that they (YCE and Capsaicin) have the potential to inhibit obesity that needs to be explored in future studies.     

MCHR1基因沉默对3T3-L1细胞诱导分化的影响

摘要:目的　运用RNA干扰技术沉默黑色素浓集激素受体1（Melanin-Concentrating Hormone Receptor 1,MCHR1）基因的表达,观察其对3T3-L1细胞诱导分化的影响,为肥胖症的基因治疗提供新思路。方法　用含绿色荧光蛋白的重组载体sh-MCHR1,通过脂质体法转染3T3-L1细胞。细胞诱导分化的同时用黑色素浓集激素（Melanin-Concentrating Hormone,MCH）干预,并在不同时点对脂滴进行油红O染色。采用RT-PCR以及Western blot分别检测过氧化物酶体增殖物激活受体γ（Peroxisome Proliferator-Activated Receptor γ,PPAR γ）、CCAAT/增强子结合蛋白-α（CCAAT/ Enhancer-Binding Protein α,C/EBPα）和脂肪酸结合蛋白2（adipocyte protein 2,ap2）mRNA和蛋白的表达。结果　重组载体sh-MCHR1成功转染;与阴性转染组相比,sh-MCHR1转染组d 10后,油红O 染液相对OD510值显著下降（P＜0.05）;PPARγ、C/EBPα和ap2 mRNA的表达量分别在d 6、d 8和d 8后显著下降（P＜0.05）;3者蛋白的表达量均在d 8后显著下降（P＜0.05）。结论　shRNA沉默MCHR1基因可减缓3T3-L1细胞诱导分化,其可能通过抑制PPARγ、C/EBPα和ap2的表达而实现。     

Expression of eotaxin in 3T3-L1 adipocytes and the effects of weight loss in high-fat diet induced obese mice

Eotaxin is an important inflammatory chemokine in eosinophil chemotaxis and activation and, thus, is implicated in asthma. Recently, obesity was associated with an increased prevalence of asthma, but the relationship between obesity and eotaxin expression has only been partially understood in obese mice and human studies. Therefore, we studied the expression patterns of eotaxin in 3T3-L1 preadipocytes/adipocytes to determine whether eotaxin levels are influenced by body weight gain and/or reduction in diet-induced obese mice. First, we investigated eotaxin expression during differentiation in 3T3-L1 adipocytes. Then, we treated 3T3-L1 preadipocytes/adipocytes with tumor necrosis factor-alpha (TNF-α), eotaxin, interleukin (IL)-4, IL-5, or leptin. To examine the effects of weight loss in high-fat diet induced obese mice, we fed C57BL/6 mice a high-fat diet or a normal diet for 26 weeks. Then, half of the high-fat diet group were fed a normal diet until 30 weeks to reduce weight. Epididymal adipose tissue, visceral adipose tissue, serum, and bronchoalveolar fluid of mice were examined for eotaxin expression. The results showed that eotaxin expression levels increased with adipocyte differentiation and that more eotaxin was expressed when the cells were stimulated with TNF-α, eotaxin, IL-4, IL-5, or leptin. An in vivo study showed that eotaxin levels were reduced in visceral adipose tissues when high-fat diet fed mice underwent weight loss. Taken together, these results indicate a close relationship between eotaxin expression and obesity as well as weight loss, thus, they indirectly show a relation to asthma.     

MAPK8基因在小鼠源性3T3-Ll脂肪细胞诱导分化中表达水平的变化

[目的]观察小鼠源性3T3-L1脂肪前体细胞诱导分化过程中MAPK8基因表达水平的变化,探讨MAPK8基因与肥胖发生之间的关系.[方法]体外培养3T3-L1前体脂肪细胞,在诱导3T3-L1脂肪细胞分化成熟的不同时段,采用RT-PCR技术检测脂肪细胞中MAPK8基因的mRNA表达水平.[结果]MAPK8基因高表达于3T3-L1脂肪前体细胞中,随细胞分化成熟该基因表达水平逐渐下调.MAPK8基因表达水平除在诱导分化前至第4 d、第2～5 d、第6～10 d时段内差异无显著性外,其余各时段间差异均有显著性(P＜0.05).[结论]MAPK8基因与肥胖发生有关,在3T3-L1细胞分化过程中表达逐渐下调可能有利于脂肪细胞的分化成熟和脂质积聚.     

NYGGF4(PID1)基因过表达对脂肪细胞线粒体代谢的影响

【目的】 观察NYGGF4(PID1)基因过表达对脂肪细胞线粒体代谢的影响。 【方法】 以3T3-L1前体脂肪细胞为研究对象,体外培养稳定转染NYGGF4(PID1)基因(NYGGF4-pcDNA3.1 (+)/myc-His B)的3T3-L1前体脂肪细胞,以转染空载体[pcDNA3.1(+)/myc-His B]的3T3-L1前体脂肪细胞为对照,经1-甲基-3异丁基黄嘌呤(MIX)加地塞米松、胰岛素方案诱导分化为成熟脂肪细胞,采用Real-time PCR检测线粒体代谢酶指标:己糖激酶(Hexokinase,HKI)、乙酰辅酶A羧化酶(Acetyl-CoA,ACC)、柠檬酸合成酶( citrate synthase,CS)、肉毒碱棕榈酰转移酶1(Carnitine palmitoyl-transferase 1,CPT1)、细胞色素C(Cytochrome c,Cyc-c)基因表达水平。 【结果】 NYGGF4(PID1)过表达显著降低3T3-L1脂肪细胞己糖激酶、乙酰辅酶A羧化酶、柠檬酸合成酶、肉毒碱棕榈酰转移酶1、细胞色素C基因表达水平,差异有统计学意义。 【结论】 NYGGF4(PID1)基因过表达,下调3T3-L1脂肪细胞中定位于线粒体的代谢关键酶,提示NYGGF4(PID1)基因过表达能影响3T3-L1脂肪细胞的线粒体代谢。     

The inhibitory effect of dibutyryl cyclic AMP on docosahexaenoic acid-induced apoptosis in HL-60 cells through activation of the phosphatidylinositol-3 kinase pathway

Objective Docosahexaenoic acid (DHA) is known as a chemopreventive substance for cancers. Previously we reported that DHA induces apoptosis in HL-60 cells. The aim of this study was to clarify the role of phosphatidylinositol 3-kinase (PI3-kinase)/Akt signaling during DHA-induced apoptosis in HL-60 cells. Methods The inhibitory effects of dibutyryl cAMP (db-cAMP) or LY294002 (a specific inhibitor of the PI3-kinase/Akt pathway) on DHA-induced apoptosis in HL-60 cells were evaluated by the appearance of apoptosis, and from the activities of caspases (3 and 8), the phospholylation of Akt, and cleavage of Bid using DNA indexes, emzymatic measurement of fragmented substrates, and Western blotting, respectively. Results The pre-incubation of db-cAMP reduced the activation of caspasses (3 and 8) during the occurrence of DHA-induced apoptosis in HL-60. However, the inhibition of PI3-kinase/Akt signaling by LY294002 resulted in recovery of the caspases’ activities, appearance of apoptotic cells, and cleavage of the Bid molecule when LY294002 was co-treated with db-cAMP before the occurrence of DHA-induced apoptosis in HL-60. It was also confirmed that LY294002 strongly inhibited phospholylation of Akt during db-cAMP induced-reduction of DHA-induced apoptosis in HL-60. Conclusion We demonstrated that DHA-induced apoptosis was sensitive to the modulation of PI3-kinase activity by treatment with db-cAMP or LY294002. These results may provide new insights into the mechanisms of the anti-cancer activity of DHA.     

二十二碳六烯酸对3T3-L1脂肪细胞脂联素mRNA的影响及其机制

目的探讨二十二碳六烯酸(docosahexaenoic acid,DHA)对3T3-L1脂肪细胞脂联素表达的影响及其机制。方法不同浓度DHA处理体外培养成熟的3T3-L1脂肪细胞,并选取一定浓度DHA加与不加过氧化物酶体增殖物激活受体γ(PPARγ)拮抗剂GW-9662处理脂肪细胞,实时荧光定量PCR分析处理前后脂联素基因和PPARγmRNA表达水平的差异。结果与对照组相比,当DHA浓度为50、100 mol/L时,脂联素表达水平分别增加71.89%、106.23%(P<0.05),随着浓度的增加脂联素表达降低,当DHA浓度达到400 mol/L时,脂联素表达水平最低(P<0.05)。当DHA浓度为100 mol/L时,脂肪细胞PPARγmRNA表达增加70.24%(P<0.05)。与对照组相比,DHA中加GW-9662处理组脂联素和PPARγmRNA表达水平分别降低97.32%、90.90%(P<0.05)。结论在一定浓度范围内,DHA对脂联素表达的影响呈剂量依赖关系,推测DHA可能是通过PPARγ途径调控脂肪细胞的脂联素表达。     

Naringin reduces fat deposition by promoting the expression of lipolysis and β-oxidation related genes

AimsNaringin, a flavonoid present in citrus fruits, has been known for the capacity to reduce lipid synthesis and anti-inflammatory. In this study, we investigated whether naringin increases lipolysis and fatty acid β-oxidation to change fat deposition.MethodsIn in vivo experiment, obese adult mice (20-weeks-old, n = 18) were divided into control group fed with normal diet and naringin-treated group fed with naringin-supplemented diet (5 g/kg) for 60 days, respectively. In in vitro experiment, differentiated 3T3-L1 adipocytes were treated for four days with or without naringin (100 µg/mL).ResultsSupplementing naringin significantly reduced the body weight, abdominal fat weight, blood total cholesterol content of mice, but did not affect food intake. In addition, naringin decreased levels of pro-inflammatory factors in adipose tissue including interleukin-1β (IL-1β), interleukin-6 (IL-6), and monocyte chemotactic protein 1 (MCP-1). Naringin increased the expression of AMP-activated protein kinase (AMPK), a key factor in cellular energy metabolism, and raised the ratio of p-AMPK/AMPK in mouse liver tissue. The protein expression of hormone-sensitive lipase (HSL), phospho-HSL563 (p-HSL563), p-HSL563/HSL, and adipocyte triglyceride lipase (ATGL) was significantly increased in the adipose tissue of naringin-treated mice. Furthermore, naringin enhanced the expression of fatty acid β-oxidation genes, including carnitine palmitoyl transferase 1 (CPT1), uncoupling protein 2 (UCP2), and acyl-coenzyme A oxidase 1 (AOX1) in mouse adipose tissue. In in vitro experiment, similar findings were observed in differentiated 3T3-L1 adipocytes with naringin treatment. The treatment remarkably reduced intracellular lipid content, increased the number of mitochondria and promoted the gene expression of HSL, ATGL, CPT1, AOX1, and UCP2 and the phosphorylation of HSL protein.ConclusionNaringin reduced body fat in obese mice and lipid content in differentiated 3T3-L1 adipocytes, which was associated with enhanced AMPK activation and upregulation of the expression of the lipolytic genes HSL, ATGL, and β-oxidation genes CPT1, AOX1, and UCP2.