蒙药“通拉嘎-5”对脂肪细胞葡萄糖摄取的影响及其机制研究

目的探讨"通拉嘎-5"对3T3-L1脂肪细胞葡萄糖摄取的影响及其作用机制。方法将3T3-L1前脂肪细胞诱导分化为脂肪细胞后,"通拉嘎-5"作用于3T3-L1脂肪细胞24 h,用3H标记的2-脱氧-葡萄糖([3H]2-DG)示踪检测胰岛素介导的3T3-L1脂肪细胞摄取葡萄糖的情况;"通拉嘎-5"作用3T3-L1脂肪细胞48 h后,用Real-time PCR检测PPARγ和LXRα的基因表达,用Western blot检测PPARγ和LXRα的蛋白表达。结果 "通拉嘎-5"能促进胰岛素介导的3T3-L1脂肪细胞的葡萄糖摄取(比阴性对照组高1.915倍,P<0.05);能明显上调3T3-L1脂肪细胞和LXRα基因(比阴性对照组高2.895倍,P<0.01)和蛋白(比阴性对照组高1.977倍,P<0.01)表达;而对PPARγ基因和蛋白表达无明显的影响。结论 "通拉嘎-5"可能通过提高3T3-L1脂肪细胞LXRα的基因和蛋白表达,促进胰岛素介导的葡萄糖摄取功能,改善胰岛素抵抗,可能为"通拉嘎-5"治疗非酒精性脂肪肝(NAFLD)的作用机制之一。     

Neu-p12 Neu-p68 Neu-p150对胰岛素抵抗3T3-L1脂肪细胞的葡萄糖摄取的影响

目的:在细胞水平,从Neu-p12、Neu-p68、Neu-p150中筛选可以改善胰岛素抵抗的药物。方法:采用"鸡尾酒"法,诱导分化出成熟的3T3-L1脂肪细胞,300μM油酸(OA)作用6 h建立胰岛素抵抗的细胞模型。实验分为5组,对照组、10 nM褪黑素组、10 nM Neu-p12组、10 nM Neu-p68组和10 nM Neu-p150组,采用2-脱氧-[3H]-D-葡萄糖的摄取实验,测定进入细胞内的葡萄糖的差异。结果:加药组的葡萄糖摄取率分别增加了508%、740%、499%、316%。结论:10 nM Neu-p12、10 nM Neu-p68、10 nM Neu-p150都可以促进胰岛素抵抗的3T3-L1脂肪细胞对葡萄糖的吸收,并且10 nM Neu-p12的效果最好。     

急性寒冷刺激诱导小鼠米黄色脂肪细胞 形成方法的建立

目的：建立急性寒冷刺激诱导小鼠皮下米黄色脂肪细胞形成的方法。方法：连续3天每天4 h预冷刺激使小鼠适应寒冷环境,然后持续24 h进行急性寒冷刺激,诱导小鼠皮下脂肪中米黄色脂肪细胞形成。采用免疫组化检测皮下脂肪中Ucp1阳性细胞,荧光定量PCR检测米黄色脂肪细胞标志性基因Ucp1、Prdm16、Pgc1α、Cidea的转录,Western blot检测米黄色脂肪细胞标志性蛋白Prdm16和Ucp1的表达。结果：急性寒冷刺激后小鼠皮下脂肪中Ucp1阳性细胞数量明显增加,Ucp1、Prdm16、Pgc1α、Cidea转录明显上调,Prdm16、Ucp1蛋白表达明显升高。结论：本研究建立的急性寒冷刺激诱导小鼠皮下米黄色脂肪细胞形成的方法可靠,可用于米黄色脂肪细胞形成调控机制的研究。     

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.     

Atorvastatin and fenofibric acid differentially affect the release of adipokines in the visceral and subcutaneous cultures of adipocytes that were obtained from patients with and without mixed dyslipidemia

In this study, we compared the effects of atorvastatin and fenofibric acid, which were administered alone or in combination, on the secretory function of human adipocytes that were obtained from the visceral and subcutaneous adipose tissues of 19 mixed dyslipidemic patients and 19 subjects with a normal lipid profile. The adipocytes were incubated in vitro in the presence of atorvastatin and/or fenofibric acid. The secretory function of the cells was determined using ELISA assays. The visceral adipocytes released significantly more adiponectin and IL-6 and less PAI-1 than those that were obtained from subcutaneous tissue. The levels and patterns of adipokine release differed between the patients with or without lipid abnormalities and between the adipocytes that were obtained from visceral or subcutaneous adipose tissue. The culture that contained hypolipidemic drugs resulted in the significant changes of the release of adipokines. The effects of atorvastatin and fenofibric acid on the hormonal function of human adipocytes may be, in part, responsible for the clinical efficacy of these drugs in the prevention and treatment of dyslipidemia-related cardiovascular and metabolic disorders. The study supports the concept that the pleiotropic effects of fenofibrate and atorvastatin may be, in part, a result of their impact on the secretory function of adipocytes.     

Perivascular adipose tissue from human systemic and coronary vessels: the emergence of a new pharmacotherapeutic target

Fat cells or adipocytes are distributed ubiquitously throughout the body and are often regarded purely as energy stores. However, recently it has become clear that these adipocytes are engine rooms producing large numbers of metabolically active substances with both endocrine and paracrine actions. White adipocytes surround almost every blood vessel in the human body and are collectively termed perivascular adipose tissue (PVAT). It is now well recognized that PVAT not only provides mechanical support for any blood vessels it invests, but also secretes vasoactive and metabolically essential cytokines known as adipokines, which regulate vascular function. The emergence of obesity as a major challenge to our healthcare systems has contributed to the growing interest in adipocyte dysfunction with a view to discovering new pharmacotherapeutic agents to help rescue compromised PVAT function. Very few PVAT studies have been carried out on human tissue. This review will discuss these and the hypotheses generated from such research, as well as highlight the most significant and clinically relevant animal studies showing the most pharmacological promise. LINKED ARTICLES: This article is part of a themed section on Fat and Vascular Responsiveness. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-3.     

Obesity and risk of vascular disease: importance of endothelium-dependent vasoconstriction

Obesity has become a serious global health issue affecting both adults and children. Recent devolopments in world demographics and declining health status of the world's population indicate that the prevalence of obesity will continue to increase in the next decades. As a disease, obesity has deleterious effects on metabolic homeostasis, and affects numerous organ systems including heart, kidney and the vascular system. Thus, obesity is now regarded as an independent risk factor for atherosclerosis-related diseases such as coronary artery disease, myocardial infarction and stroke. In the arterial system, endothelial cells are both the source and target of factors contributing to atherosclerosis. Endothelial vasoactive factors regulate vascular homeostasis under physiological conditions and maintain basal vascular tone. Obesity results in an imbalance between endothelium-derived vasoactive factors favouring vasoconstriction, cell growth and inflammatory activation. Abnormal regulation of these factors due to endothelial cell dysfunction is both a consequence and a cause of vascular disease processes. Finally, because of the similarities of the vascular pathomechanisms activated, obesity can be considered to cause accelerated, 'premature' vascular aging. Here, we will review some of the pathomechanisms involved in obesity-related activation of endothelium-dependent vasoconstriction, the clinical relevance of obesity-associated vascular risk, and therapeutic interventions using 'endothelial therapy' aiming at maintaining or restoring vascular endothelial health. LINKED ARTICLES: This article is part of a themed section on Fat and Vascular Responsiveness. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-3.     

Glitazone-like action of glimepiride and glibenclamide in primary human adipocytes

Aim: Sulphonylureas (SUs) are among the most widely used oral hypoglycaemic drugs that stimulate insulin secretion. In addition, SUs have pleiotropic effects on other tissues. Conflicting findings have been reported regarding the effects of SUs on adipocytes. We have now investigated the actions of glimepiride and glibenclamide (=glyburide) in primary human adipocytes. Methods: Primary cultured human white pre‐adipocytes were differentiated in vitro according to a standard protocol. Lipid accumulation was assessed by Oil Red O staining and determination of triglyceride content; gene expression was measured by RT PCR and Western blotting. Results: Initially, we characterized the genes regulated during human pre‐adipocyte differentiation by performing global microarray analysis. Treatment with glimepiride and glibenclamide caused an increased accumulation of lipid droplets and triglycerides. In addition, genes involved in lipid metabolism were induced and chemokine expression was decreased. Interestingly, the effects of SUs were generally qualitatively and quantitatively similar to those of pioglitazone. In direct comparison, glibenclamide was more potent than glimepiride with respect to the induction of fatty acid binding protein 4 (FABP4) (EC₅₀ 0.32 vs. 2.8 µM), an important adipocyte marker gene. SU‐induced differentiation was virtually completely blocked by the peroxisome proliferator‐activated receptor γ (PPARγ)‐antagonist T0070907 but not affected by diazoxide, indicating PPARγ activation by SUs. Repaglinide had no effect on adipogenesis, although it causes insulin liberation like SUs. Conclusions: In primary human pre‐adipocytes, glibenclamide and glimepiride strongly induced differentiation, apparently by activating PPARγ. Thus, SUs but not repaglinide may be used to influence insulin resistance beyond their effect on insulin liberation.     

Future of GPR109A agonists in the treatment of dyslipidaemia

Abnormal blood lipids are the major modifiable risk factor underlying the development of cardiovascular disease. Niacin has a profound ability to reduce low-density lipoprotein-C, very low-density lipoprotein-C and triglycerides and is the most effective pharmacological agent to increase high-density lipoprotein-C. Recently, the receptor for niacin, GPR109A, was discovered. GPR109A in the adipocyte mediates a niacin-induced inhibition of lipolysis, which could play a crucial part in its role as a lipid-modifying drug. GPR109A in epidermal Langerhans cells mediates flushing, an unwanted side effect of niacin therapy. For the past decade, the functions of GPR109A have been studied and full or partial agonists have been developed in an attempt to achieve the beneficial effects of niacin while avoiding the unwanted flushing side effect. This review presents what is known to date about GPR109A biology and function and the future of GPR109A as a pharmacological target.