性激素对3T3-L1前脂肪细胞和脂肪细胞胰岛素敏感性的影响

目的观察不同浓度雌、雄激素对3T3-L1前脂肪细胞葡萄糖转运的影响,探讨性激素在胰岛素抵抗形成中的意义。方法体外培养3T3-L1前脂肪细胞,并诱导其分化成熟,利用2-脱氧-[3H]-D-葡萄糖掺入法,研究不同浓度的17β雌二醇、睾酮对胰岛素刺激的前脂肪细胞和脂肪细胞葡萄糖摄取能力的影响。结果10-8mol/L的17β雌二醇即能够抑制3T3-L1前脂肪细胞胰岛素刺激状态下的葡萄糖转运,且呈现明显的浓度依赖性抑制;而睾酮为10-8mol/L时3T3-L1前脂肪细胞胰岛素刺激状态下的葡萄糖转运并无明显影响,在浓度达到10-7mol/L开始出现抑制效应,浓度越高抑制效应越明显。结论性激素可以调节3T3-L1前脂肪细胞的胰岛素敏感性。     

Differential Immunohistochemical Expression of Syndecan-1 and Tumor Necrosis Factor Alpha in Colonic Mucosa of Patients with Crohn’s Disease

Tumor necrosis factor alpha (TNFα) in intestinal mucosa plays a key role in the inflammation characterizing Crohn’s disease (CD). Moreover, adhesion molecule syndecan-1 mediates the maintenance of mucosal integrity and supports tissue repair. Therefore, our aim in this study was to correlate simultaneous expression of TNFα and syndecan-1 in patients affected by CD. Biopsies from 10 patients with CD of large bowel and 10 subjects with irritable bowel syndrome (controls) were studied by immunohistochemical detection of both TNFα and syndecan-1 on successive serial sections. Overall labeling index (OLI) was indicated by the percentage of positive stromal (i.e., nonepithelial) cells/1000 counted in randomized fields, whereas selected labeling index (SLI) was represented by the simultaneous evaluation of both molecules in a same single selected field of each specimen. TNFα and syndecan-1 OLI were significantly higher in CD compared with controls, while SLI showed an inverse relationship between the molecules in CD which was not observed in controls. Epithelial syndecan-1 cytoplasmatic staining of superficial epithelium was associated with loss of basolateral staining in the crypts and high stromal TNFα in CD. In conclusion, TNFα and syndecan-1 expression is increased in the intestinal mucosa of patients with CD. However, the expression of the two molecules is inversely related when a single field is considered, these data supporting the possibility of a downregulation exerted by TNFα.     

Insulin stimulates IGFBP-2 expression in 3T3-L1 adipocytes through the PI3K/mTOR pathway

Insulin-like growth factor binding protein 2 (IGFBP-2) has been implicated in the etiology of several diseases, including the metabolic syndrome. Although IGFBP-2 derives mostly from the liver, recent evidence in mice and humans indicate that aging and obesity are associated with altered IGFBP-2 levels in white adipocytes. The present study was aimed at determining the mechanisms that control IGFBP-2 expression in mature adipocytes. IGFBP-2 mRNA and protein expression in serum-deprived 3T3-L1 adipocytes were twofold increased by acute insulin treatment. Co-treatments with the phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin or the mammalian target of rapamycin (mTOR) inhibitor rapamycin blunted the effects of insulin. Coherently, IGFBP-2 mRNA levels were robustly increased in adipocytes lacking either TSC2 or 4E-BP1. Insulin triggered the recruitment of CAAT/enhancer binding protein α (C/EBPα) to the IGFBP-2 proximal promoter. These findings suggest that insulin upregulates IGFBP-2 expression through a PI3K/mTOR/C/EBPα pathway in white adipocytes.     

Fas凋亡相关基因在双酚A诱导成年雄性大鼠生殖毒性中的作用

目的探讨Fas凋亡途径相关基因在双酚A（BPA）诱导成年雄性大鼠生殖毒性中的作用。方法 40只成年Wistar雄性大鼠随机等分为4组：溶媒对照组（玉米油）和低、中、高剂量BPA喂养组（10、50、250μg/kg·bw/d）。大鼠在喂养35周后处死,称量睾丸、附睾、肝、肾及心脏重量并计算脏器系数;观察精子形态及计算精子畸形率。采用荧光实时定量PCR（RT-PCR）测定睾丸组织中自杀相关因子（Fas/Fas-L）、天冬氨酸特异酶切的半胱氨酸蛋白酶3（Caspase-3）mRNA含量。结果高剂量BPA喂养大鼠精子畸形率以及睾丸组织中Fas-L mRNA及Caspase-3 mRNA含量高于对照组,差异均有显著性（P!0.05）。结论在BPA的人体每日容许摄入量水平下（TDI=50μg/kg·bw/d）,未观察到生殖细胞损伤的效应;但长期经膳食暴露高剂量BPA（250μg/kg·bw/d）可致成年雄性大鼠生殖细胞损伤,其机制可能与BPA上调Fas-L mRNA和Caspase-3的表达有关。     

Anti-Obesity Effect of Nostoc commune Ethanol Extract In Vitro and In Vivo

Nostoc commune is an edible terrestrial blue-green alga. It has shown many beneficial effects on human health. This study aimed to investigate the phytochemical assay of N. commune ethanol extract (NEE) and its anti-obesity effects. The effect of a high-calorie diet on lipid accumulation in 3T3-L1 preadipocytes is investigated, and a Wistar rat model is used to demonstrate the anti-obesity effect of NEE and its mechanism. The results showed that the NEE has phytochemical compounds, such as total polyphenol, total flavonoids, and total terpenoids. NEE was also shown to suppress cell proliferation and lipid accumulation (26.9%) in 3T3-L1 preadipocytes. Furthermore, NEE reduced the body weight (13.5%), fat tissue weight (13.3%), and the serum FFA (19.4%), TG (14.2%), TC (11.8%), and LDL-C (16.4%) of rats. In histopathology, NEE was shown to diminish the size of adipocytes and hepatic lipid droplets. The NEE downregulated the mRNA expression of adipogenesis (PPAR-γ, SREBP-1c) and lipid lysis-related genes (ATGL, HSL) in epididymal adipose tissue. The NEE also upregulated the mRNA expression of β-oxidation related genes (AMPK, CPT-1, PPAR-α) in the liver. Overall, this study suggests NEE has the potential to be developed as a functional food for anti-obesity.     

Alterations of insulin sensitivity by the implantation of 3T3-L1 cells in nude mice. A role for TNF-alpha?

Aims/hypothesis. Visceral adipocytes have different functions than those from the subcutaneous fat area. These differences could contribute to the pathological significance of excessive visceral fat accumulation for accompanying insulin resistance and hyperinsulinaemia. This study addresses this hypothesis and describes a unique method to clarify whether the functional differences between visceral and subcutaneous adipocytes depend on their anatomical location. Methods. 3T3-L1 cells or TNF-α overexpressing CHO cells were implanted into subcutaneous fat area or mesenteric area as visceral fat area in athymic mice of BALB/C strain. Then, serum insulin, glucose, TNF-α, and several markers of lipid metabolism were measured in the fasting condition. OGTT was also analysed. Results. During the course of glucose loading, the mice which had 3T3-L1 cells implanted into mesenteric area but not into subcutaneous fat area showed remarkably increased serum insulin and TMF-α concentrations, compared to the control mice. Moreover, serum insulin concentrations of the mice, implanted with TNF-α overexpressing cells into subcutaneous fat area, were apparently higher than that of control mice. Conclusion/interpretation. This method of implanting adipose cells into subcutaneous or visceral fat area showed high TNF-α concentration and insulin resistance by the adipose cells in visceral area of nude mice. Furthermore, we found that the functional significance of visceral fat accumulation for TNF-α-induced insulin resistance is partly caused by the interaction of adipocytes with surrounding conditions in mesenteric area. [Diabetologia (2002) 45: ▪–▪] Received: 15 February 2001 and in revised form: 21 December 2001     

前脂肪细胞与蚕丝支架体外复合培养的实验研究

目的 观察蚕丝对前脂肪细胞吸附作用及蚕丝对前脂肪细胞形态和功能的影响,为脂肪组织工程支架选择提供依据.方法 从家蚕蚕茧中抽丝所得的原料蚕丝,经胰蛋白酶消化后与原料蚕丝分别制成三维支架,将前脂肪细胞制成细胞悬液接种在支架上,倒置显微镜和扫描电镜观察前脂肪细胞的吸附和生长.结果 在消化后的蚕丝三维支架可看见前脂肪细胞1～2 d后完全贴壁.培养3～7 d细胞生长增殖十分活跃,两周时,蚕丝支架网眼充满前脂肪细胞,扫描电镜见细胞与支架紧密贴附适度伸展并有基质分泌.结论 蚕丝对前脂肪细胞具有良好的吸附作用,并能维持前脂肪细胞正常形态和功能,蚕丝是前脂肪细胞立体培养时的天然支架.