Fat cell enlargement is an independent marker of insulin resistance and ‘hyperleptinaemia’

Aims/hypothesis The aim of this study was to explore whether fat cell size in human subcutaneous and omental adipose tissue is independently related to insulin action and adipokine levels. Materials and methods Fat cells were prepared from abdominal subcutaneous biopsies obtained from 49 type 2 diabetic and 83 non-diabetic subjects and from omental biopsies obtained from 37 non-diabetic subjects. Cell size and insulin action on glucose uptake capacity in vitro were assessed in isolated fat cells. Insulin sensitivity in vivo was assessed with euglycaemic-hyperinsulinaemic clamps. Fasting blood samples were collected and adipokines and NEFA were measured. Results Negative correlations were found between subcutaneous fat cell size and insulin sensitivity assessed as M-value during clamp and as insulin action on glucose uptake in fat cells in vitro. This was seen in non-diabetic subjects after including age, sex and BMI in the analyses. No such relationship was found in type 2 diabetic subjects. In both groups, subcutaneous fat cell size correlated positively and independently with plasma levels of leptin but not to any of the other assessed adipokines. In non-diabetic subjects, omental fat cell size was independently and negatively correlated with insulin action in subcutaneous, but not omental, fat cells in vitro. Conclusions/interpretation Fat cell enlargement is associated with insulin resistance in non-diabetic individuals independently of BMI. This was not seen in type 2 diabetic subjects, suggesting that after development of type 2 diabetes other factors, not related to fat cell size, become more important for the modulation of insulin resistance.     

The Bone-Adipose Axis in Obesity and Weight Loss

Body fat and lean mass are correlated with bone mineral density, with obesity apparently exerting protection against osteoporosis. The pathophysiological relevance of adipose tissue in bone integrity resides in the participation of adipokines in bone remodeling through effects on deposition and resorption. On the other hand, the skeleton has recently emerged as an endocrine organ with effects on body weight control and glucose homeostasis through the actions of bone-derived factors such as osteocalcin and osteopontin. The cross-talk between adipose tissue and the skeleton constitutes a homeostatic feedback system with adipokines and molecules secreted by osteoblasts and osteoclasts representing the links of an active bone-adipose axis. Given the impact of bariatric surgery on absorption and the adipokine secretory pattern, to focus on the changes taking place following surgical-induced weight loss on this dynamic system merits detailed consideration.     

内脂素与子痫前期

内脂素(visfatin)是新近发现的一种主要由内脏脂肪细胞分泌的脂肪因子,结构复杂,存在基因多态性,具有调节糖脂代谢作用.内脂索增加胰岛素敏感性、促进血管平滑肌细胞成熟、参与炎症反应及血管生成,与动脉粥样硬化形成及血管内皮细胞受损和功能紊乱密切相关.子痫前期是一种病因不明的病理妊娠,严重危害母要生命,血管内皮细胞损伤...     

Soy isoflavones modulate adipokines and myokines to regulate lipid metabolism in adipose tissue,skeletal muscle and liver of male Huanjiang mini-pigs

Although a growing body of evidence suggests that soy isoflavones help regulate lipid metabolism, the underlying mechanism has not yet been thoroughly clarified. The present study was undertaken to determine the effects of soy isoflavones on the expression of genes involved in lipid metabolism in different adipose tissue depots, skeletal muscle and liver of male Huanjiang mini-pigs, as well as the expression of adipokines and myokines. A total of 36 male Huanjiang mini-pigs were fed basal diet (control, Con), low-dose soy isoflavones (LSI) and high-dose soy isoflavones (HSI). The results showed that LSI and HSI regulated the expression of genes involved in the anabolism and catabolism of fatty acids in dorsal subcutaneous (DSA), abdominal subcutaneous (ASA) and perirenal (PRA) adipose tissue depots, as well as longissimus dorsi muscle (LDM) and liver. LSI and HSI also regulated the expression of adipokines in DSA, ASA and PRA, and the expression of myokines in LDM in male Huanjiang mini-pigs. In addition, soy isoflavones regulated plasma glucose, leptin and adiponectin contents after treatment for two months. Our results indicate that soy isoflavones, by regulating the expression of adipokines and myokines, may regulate the metabolism of lipids and could have potential therapeutic applications in lipid abnormalities.     

The role of leptin in fetal growth: a short review from conception to delivery

Abnormally high- or low-serum maternal levels and/or levels in placental, umbilical blood, and fetus/neonate are associated with a wide spectrum of complicated pregnancies. Whereas the state of knowledge about mechanisms and pathways involving secondary or tertiary modulators is far from complete, the role of leptin from ovulation and implantation and throughout pregnancy underscores its importance in normal and abnormal states.     

成纤维细胞生长因子-21表达变化对3T3-L1脂肪细胞成纤维细胞生长因子受体及脂肪细胞因子的影响

目的 探讨FGF-21表达变化对FGF相关受体(FGFRs)和脂肪细胞因子表达的影响.方法 设计并构建2条针对小鼠FGF-21基因的短发夹状RNA(shRNA)序列,运用双荧光蛋白检测系统初步验证其有效性,筛选出抑制有效的pGenesil-FGF21重组质粒,分别用FGF-21过表达质粒pcDNA-FGF21和FGF-21 RNAi表达载体pGenesil-FGF21转染3T3-L1脂肪细胞,采用荧光定量PCR法检测FGF-21、FGFRs、脂联素、Visfatin以及瘦素(Leptin) 的mRNA表达水平.结果 成功构建2条FGF-21-shRNA重组质粒.转染上述重组载体的细胞内,两组pGenesil-FGF21 GFP平均荧光强度/RFP平均荧光强度均低于阴性对照组(均P<0.05),且pGenesil-FGF21-1组更低.转染pcDNA-FGF21的3T3-L1脂肪细胞内FGF-21 mRNA表达明显增加(P<0.01),转染pGenesil-FGF21-1的细胞内FGF-21 mRNA表达降低77.8%(P<0.05).FGF-21过表达的脂肪细胞内以β-klotho和FGFR1 mRNA表达明显升高,而Leptin mRNA表达明显降低;而FGF-21表达缺陷时则相反(均P<0.05).结论 FGF-21可能主要通过β-klotho和FGFR1途径激活受体后信号系统,并且可能通过影响脂肪细胞因子表达从而对代谢发挥其调控作用.     

Bone, Fat, and Body Composition: Evolving Concepts in the Pathogenesis of Osteoporosis

Disorders of body composition, including obesity and osteoporosis, have reached record proportions. Coincidentally, our understanding of the mechanisms controlling body mass also has greatly improved. Shared regulation at the hypothalamus and the bone marrow highlight major bone-fat interactions. The hypothalamus modulates fat and bone via the sympathetic nervous system by regulating appetite, insulin sensitivity, energy use, and skeletal remodeling. In the bone marrow, fat and bone cells arise from the same stem cells. Insights from disorders such as anorexia nervosa provide a new rationale for examining the mechanisms that link bone to fat. This article explores these relationships in the context of a new paradigm with implications for obesity and osteoporosis.