Reduced lipolysis and increased lipogenesis in adipose tissue from pinealectomized rats adapted to training

The current study investigated the effects of chronic training and pinealectomy on the lipogenic and lipolytic activity of adipose tissue. Pinealectomized and sham-operated adult male Wistar rats were distributed in to four subgroups: pinealectomized untrained, pinealectomized trained, control untrained and control trained. At the end of the training period (8 wk) the rats were killed. Blood samples were collected for glucose, insulin and leptin determinations. Peri-epididymal adipocytes were isolated for measurement of in vitro rates of lipolysis and incorporation of substrates (D-[U-14C]-glucose, L-[U-14C]-lactate, [2-14C]-acetate and [1-14C]-palmitate) into lipids, and samples of epididymal adipose tissue were homogenized for evaluation of glucose-6-phosphate dehydrogenase maximal activity. Pinealectomy resulted in a significantly increased lipolytic capacity in response to isoproterenol and a decrease in circulating leptin levels without affecting the rates of incorporation of different substrates into lipids. However, only in the intact control group did training promote a higher basal and isoproterenol-stimulated lipolysis, increase the incorporation of palmitate (esterification), decrease the incorporation of acetate (lipogenesis) into lipids and diminish circulating leptin levels. These effects of exercise training were not seen in pinealectomized rats. However, pinealectomized trained animals showed a marked reduction in lipolysis and an increased rate of acetate incorporation. In conclusion, we demonstrated for the first time that the pineal gland plays an important role in the regulation of lipid metabolism in such a way that its absence caused a severe alteration in the balance between lipogenesis and lipolysis, which becomes evident with the adaptation to exercise training.     

Lipolysis and apoptosis of adipocytes induced by neuropeptide Y—Y5 receptor antisense oligodeoxynucleotides in obese rats

目的:探讨神经肽Y-Y5受体反义基因治疗后饮食性肥胖大鼠减肥减重效应与外周白色脂肪细胞体积、数目变化的关系。方法:建立饮食性肥胖大鼠模型,侧脑室注射Y5受体编码起始区反义、正义、错义寡脱氧核糖核酸及生理盐水,采用MPLAS-500多媒体彩色病理图文分析系统计算平均脂肪细胞面积,基因组DNA提取物凝胶电泳检测脂肪细胞凋亡,RT-PCR分析凋亡相关基因bc1-2、bax表达的改变。结果:(1)Y5受体反义基因治疗后大鼠进食量与体重显著降低,外周白色脂肪组织湿重与平均脂肪细胞面积明显减少;(2)脂肪组织基因组DNA提取物凝胶电泳出现凋亡特征性梯状条带;(3)凋亡相关基因bc1-2表达下调、bax表达上调。结论:平均脂肪细胞面积减小、脂肪细胞凋亡增加可能是Y5受体反义基因治疗减肥减重的重要原因。     

双(α-呋喃甲酸)氧钒的胰岛素样作用

钒作为人体必需的微量元素,在葡萄糖的代谢过程中起着重要作用.大量的体内外研究表明微量元素钒具有"胰岛素样(insulin-mimics)"作用,研究表明它能增加胰岛素的敏感性,是"胰岛素的促进剂(insulin-enhancing agent)",可用于治疗和缓解1型和2型糖尿病.     

人类β-肾上腺素受体基因的遗传多态性及其与肥胖的关系

在世界范围内,肥胖和超重的发生率正在稳步增长.过去有关候选基因的大量研究已经表明,大多数基因与人类脂肪组织中肥胖的发生相关.与人体体质量相关的40%以上的基因变异可以产生遗传差异.β-肾上腺素受体在人体能量平衡调节中扮演重要作用,交感神经系统的高度激活被认为与肥胖的发生密切相关.β-肾上腺素受体的单核苷酸多态性如β1-肾上腺素受体Gly389Arg,β2-肾上腺素受体Gln27Glu和β3-肾上腺素受体Trp64Arg已经被证明能够改变受体的功能,并与肥胖的发生有关.本文就β-肾上腺素受体的遗传多态性以及它们在肥胖发生中的作用作一综述.     

麻黄对脂肪细胞脂质代谢影响的实验研究

目的：研究麻黄对脂肪细胞脂质代谢的影响。方法：用正常大鼠附睾处脂肪细胞,分别观察麻黄对由１４Ｃ标记的葡萄糖转化的脂肪合成及由去甲肾上腺素（ＮＥ）促进的脂肪分解的作用。结果：麻黄可促进由葡萄糖转化的脂肪合成,并且这种作用与基质溶液的ｐＨ值有关;麻黄尚可抑制由ＮＥ促进的脂肪分解作用。结论：麻黄具有促进脂肪细胞脂肪合成的作用,该作用不是由麻黄碱所致,其作用机制与胰岛素有类同之处。     

Injection lipolysis for reduction of saddlebag trochanteric bulges ‐ half‐side controlled pilot study

Background: Phosphatidylcholine, a lecithin extracted from soybeans can reduce serum cholesterol to some extent. Intravenous use may prevent fat embolism in polytrauma patients. When injected intralesionally in a formulation containing also deoxycholate and ethanol it is supposed to act as “fat burner” to reduce undesired fat deposits; there is little evidence‐based scientific support for this indictaion. Objective: To evaluate the capability of phosphatidylcholin + deoxycholate + ethanol (PPC/DC/E) to reduce body fat with a half‐side pilot study for the reduction of saddlebag trochanteric bulges. Methods: PPC/DC/E was injected into the right posterior trochanteric areas three times at weeks 0, 3 and 6. Treatment areas and the same regions of the contralateral side as a control were evaluated by sonography. Tape measurements were taken and the thickness of the subcutaneous adipose tissue (SAT) was measured with an optical device (Lipometer^®) at baseline and at week 8 and week 20 (2 and 14 weeks after completign therapy). Results: In this half‐side trial, no significant reduction of subcutaneous fat was achieved after three treatments with PPC/DC/E when compared to the untreated side.Transient inflammatory reactions occurred in all patients. Limitations: Only the commercially available formulation containing the three components was tested. Conclusion: The off‐label use of PPC/DC/E as a “fat burner” did not produce measurable reduction of undesired trochanteric fat deposits.     

The role of calcium in insulin action. III. Calcium distribution in fat cells; its kinetics and the effects of adrenaline, insulin and procaine-HCl.

The effects of adrenaline, insulin and procaine-HCl on Ca distribution in intact fat cells and on Ca binding to fat cell ghost membranes have been investigated. 1. Fat cells incubated in 45Ca containing media till isotopic equilibrium indicated that the exchangeable Ca in these cells averages 25.7 +/-3.2nmol/mg protein, which represents approximately 9.8% of their ttotal Ca content. 2. Perifusion of 45Ca prelabelled fat cells gave washout curves whose analysis conformed with three kinetically distinct Ca pools (Fig. 1). The fast exchangeable pool (Compartment A) had an efflux rate constant of 0.193 +/-0. 013 min.-. The release of Ca from the second and thrid pools (Compartments B and C) was much slower with efflux rate constants of 0.032 +/-0.0018 min.-1 and 0.0042 +/- 0.0006 min.-1 respectively. Changing the Ca concentration in the perifusing medium modified the initial fast phase and its rate constant, while added dinitrophenol (DNP) inhibited the efflux rate from the later compartments...     

Human Adipose Tissue in Culture

Explants of human adipose tissue were cultured for several days with noradrenaline (NA). After the culture period the explants were carefully washed, preincubated and then incubated for 2 h by a technique analogous to those generally used to study adipose tissue metabolism. The results show that explants cultured with NA were considerably less responsive to the acute lipolytic effect of catecholamines than explants not previously exposed to NA. The diminished responsiveness could not be reversed by the addition of phentolamine or by preincubating the explants with a prostaglandin antagonist and it was dependent upon the concentration of noradrenaline used in the culture medium as well as upon the period of time that the explants were exposed to the hormone. The cyclic AMP (cAMP) levels did not increase in response to NA in these explants. Addition of theophylline or dibutyryl cAMP elicited a lipolytic response. However, the phosphodiesterase levels were not increased in the explants cultured with noradrenaline. When freshly excised tissue specimens were incubated in the culture medium which had previously contained NA the acute lipolytic effect of catecholamines was blunted. The results indicate that an antagonist is formed during the incubation with NA which inhibits the responsiveness to catecholamines. The effect of the antagonist seems to be exerted at a step prior to the formation of cAMP.