脂蛋白脂酶活性与早发冠心病临床表型关系的初步探讨

目的：探讨脂蛋白脂酶（LPL）活性与早发冠心病临床表型的关系。方法：测定106例早发冠心病患者（病例组）肝素化后血浆LPL活性，血脂参数和血浆C反应蛋白（CRP）浓度，与54例非冠心病者（对照组）进行比较；病例组按照患者临床表型分组，分析LPL活性特点。结果：病例组肝素化后血浆LPL活性低于对照组 [ (26.18±3.90) mmol·L^-1·min^-1 vs (35.27±5.96) mmol·L^-1·min^-1, P<0.05]，急性心肌梗死组LPL活性明显低于不稳定性心绞痛和稳定性心绞痛组。双因素相关分析，LPL与CRP呈显著负相关（r=-0.234，P<0.01）；多因素回归分析，低LPL活性可能是早发冠心病独立的危险因子（OR=6.32，95%CI 1.96-18.24，P<0.05)。结论：低LPL 活性是早发冠心病独立的危险因子，LPL活性与早发冠心病临床表型相关联。     

高脂饮食兔肺泡巨噬细胞［Ca2+］i及ACE活性变化

目的： 了解高脂饮食对兔肺泡巨噬细胞胞浆游离钙浓度(［Ca²⁺］_i)及血管紧张素Ⅰ转换酶 (ACE) 活性的影响，探索哮喘与高脂饮食相关的可能机制。方法: 高胆固醇饮食法建立高脂兔模型(ｎ=6)，8周后离体支气管肺泡灌洗；Fura2/am测定肺泡巨噬细胞［Ca²⁺］_i,紫外法检测ACE活性。结果: 高脂组肺泡巨噬细胞［Ca²⁺］_i显著高于正常组 (P＜0.01)；其支气管肺泡灌洗液(BALF)及肺泡巨噬细胞上清液中ACE活性显著高于正常组 (均P＜0.01)；高脂组BALF中肺泡巨噬细胞数、肺泡巨噬细胞［Ca²⁺］_i 及肺泡巨噬细胞培养上清液ACE活性均与血清总胆固醇含量呈正相关，r分别为0.851、0.840、0.847(均P＜0.05)。结论: 高脂饮食导致兔肺泡巨噬细胞活化，活性增高的肺泡巨噬细胞处于易激状态。     

膳食黑米皮对载脂蛋白E基因缺陷小鼠诱导型一氧化氮合酶表达的影响

目的:探讨膳食黑米皮对载脂蛋白E基因缺陷小鼠(apoE基因缺陷小鼠)动脉粥样硬化(AS)形成的影响及其作用机制,为AS的膳食防治研究提供理论依据。方法:分离apoE基因缺陷小鼠心脏,用油红O染色法和图像分析法检测小鼠主动脉窦动脉粥样斑块面积的大小。分离小鼠血清,硝酸还原酶法检测一氧化氮(NO^-₂/NO^-₃)含量;分离小鼠主动脉,抽提总蛋白,放射免疫法检测诱导型一氧化氮合酶(iNOS)的活性;抽提总RNA,用逆转录-聚合酶链式反应(RT-PCR)检测iNOSmRNA的表达。结果:黑米皮组apoE基因缺陷小鼠主动脉窦动脉粥样斑块面积显著低于阳性组和白米皮组(P＜0.01)。黑米皮组与白米皮组血清中NO^-₂/NO^-₃含量并无显著差异(P＞0.05);黑米皮组小鼠主动脉iNOS的活性和iNOSmRNA的表达量显著低于阳性组和白米皮组(P＜0.05)。结论:膳食黑米皮可抑制apoE基因缺陷小鼠iNOSmRNA的表达,这可能是黑米皮抗AS作用的机制之一。     

动脉粥样硬化家兔血浆及组织金属硫蛋白含量变化

目的:在家兔动脉粥样硬化(AS)模型上观察肝、主动脉组织及血浆金属硫蛋白(MT)含量变化,认识AS时机体氧化防御系统的改变。方法:家兔高脂饮食8周,复制高脂血症-动脉粥样硬化模型,分别以 血红蛋白饱和法和硫代巴比妥酸法测定家兔肝、主动脉组织及血浆MT及丙二醛(MDA)含量。结果:AS家兔肝组织和血浆MT水平分别较对照组高318%(P＜0.01)和62%(P＜0.01),而主动脉组织MT含量较对照组低33%(P＜0.01)。肝、主动 脉组织及血浆MDA含量分别较对照组高95%(P＜0.01),76%(P＜0.05)和42%(P＜0.01),肝组织,血浆MT变化与MDA变化相关。结论:AS家兔肝组织和血浆MT产生增多与脂质过氧化损伤有关。     

舒张性心力衰竭兔Ca2+调控蛋白mRNA和蛋白质的表达

目的:探讨心肌细胞内Ca²⁺超负荷以及Ca²⁺调控蛋白在舒张性心力衰竭(DHF)发生中的作用。方法:采用RT-PCR和Westernblot技术测定实验兔Ca²⁺调控蛋白mRNA和蛋白质表达的变化。结果:⑴DHF兔心肌细胞内Ca²⁺含量显著高于假手术组(P＜0.01);⑵DHF兔SRCa²⁺-ATPase活性明显低于假手术组(P＜0.01);⑶DHF兔SRCa²⁺-ATPase和细胞膜L型Ca²⁺通道的mRNA水平明显低于假手术组(P＜0.05),而磷酸受纳蛋白、兰尼碱受体和肌集钙蛋白的mRNA转录无明显差异(P＞0.05);⑷DHF兔SRCa²⁺-ATPase的蛋白质表达明显低于假手术组(P＜0.05);磷酸受纳蛋白的相对含量与假手术组无明显差异(P＞0.05)。结论:SRCa²⁺-ATPase的mRNA和蛋白质表达减低以及细胞膜L型Ca²⁺通道mRNA转录减低是导致心肌细胞内Ca²⁺超负荷及DHF发生的重要因素。     

茶多酚对酒精诱导的小鼠肝脂质过氧化和血清ALT活性变化的影响

目的: 研究茶多酚(TP)对酒精性肝损伤的防治作用。方法: 通过离体和整体实验,采用分光光度法和血清生化检测法,检测肝组织脂质过氧化产物丙二醛(MDA)水平和血清谷丙转氨酶(ALT)的活性。结果: 离体实验中,TP+酒精组肝MDA水平明显低于生理盐水+酒精组(P＜0.01)。整体实验中,TP+酒精组小鼠肝脏MDA水平和血清中ALT活性均显著低于生理盐水+酒精组(P＜0.05)。此外,灌酒精1h后再给TP组,小鼠肝脏MDA含量也明显低于酒精+生理盐水组(P＜0.01)。结论: 茶多酚能抑制酒精引起的小鼠肝组织MDA水平和血清ALT活性的升高,可能具有防治酒精性肝损伤的作用。     

衰老大鼠急性肺损伤诱导肾功能受损

目的:观察衰老大鼠的急性肺损伤(ALI)是否可进一步诱导肾功能受损。方法:Wistar雄性大鼠40只, 复制成衰老模型, 然后再随机分成对照组(静脉注射生理盐水), ALI组(静脉注射脂多糖, LPS)及LPS组(左心室内注射LPS), 后两组再分2h及6h组。每组8只。注LPS后2h或6h收集血并取肺、肾。制备肺、肾组织匀浆待测。结果:ALI组在注LPS后仅至6h时血中肌酐(Cr)、尿素氮(BUN)含量才有显著升高(均P＜0.01)。而LPS组Cr、BUN含量均无显著升高。ALI组血中乳酸(LD)、丙二醛(MDA)及一氧化氮(NO)含量在注LPS后2h时均显著升高(P＜0.05, P＜0.01);而肺组织中谷胱甘肽过氧化物酶(GSH-P_X)及Na⁺-K⁺-ATPase活性均显著下降(均P＜0.01);上述变化持续至观察的6h时。ALI组在注LPS后仅至6h时, 肾组织中MDA、NO含量才有显著升高(均P＜0.01)及GSH-P_X、Na⁺-K⁺-ATPase活性显著下降(P＜0.01)。而在LPS组, 除注LPS后2h时的血中和2h、6h的肺组织中NO含量显著升高(均P＜0.05)及2h时的肺组织中Na⁺-K⁺-ATPase活性显著下降(P＜0.05)外, 其它均无显著变化。结论:给衰老大鼠静脉内注射5mg/kg的LPS可致ALI, 并可进一步诱导肾功能受损。     

参与脂蛋白代谢酶研究的进展

肝性脂酶(HL)、脂蛋白脂酶(LPL)和卵磷脂胆固醇酰基转移酶(LCAT)是血浆脂蛋白代谢中三个关键酶,与血浆脂质转运蛋白(LTP)一起调控脂蛋白代谢。几十年来它们一直受到人们关注。本文重点介绍近几年来有关这三个酶研究的进展。 1.HL 肝素化血浆中存在二种脂酶活性:HL和LPL。HL是肝实质细胞合成、转运到肝窦状隙内皮细胞表面发挥生理作用,故又称为肝内皮细胞脂酶(HEL)。它是一种糖蛋白,在肝细胞经过一系列糖基化加工。HL-Ⅰ(Mr.51000)和HL-Ⅱ(Mr.53000)代表细胞内加工过程两个不同阶段。在合成类固醇激素的细胞如肾上腺和卵巢细胞也发现HL存在。     

阿魏酸钠对高脂血症致动脉粥样硬化过程中胆固醇和甘油三酯代谢的影响

目的：观察阿魏酸钠(SF)对高脂血症引起的动脉粥样硬化(AS)过程中胆固醇和甘油三酯代谢的影响，进一步探讨其抗动脉粥样硬化的作用机制。方法: 高胆固醇喂养复制AS动物模型；以氧化型低密度脂蛋白（ox-LDL）与小鼠巨噬细胞株RAW264.7细胞体外共培养，诱导建立泡沫细胞模型，与人肝母细胞瘤细胞株HepG2细胞体外共培养，建立损伤细胞模型；分别给予SF进行干预。检测实验动物AS斑块面积和血脂水平，油红O染色观察RAW264.7细胞内脂质堆积情况，高效液相色谱定量分析RAW264.7细胞内胆固醇的含量，逆转录聚合酶链反应（RT-PCR）测定HepG2细胞肝脂酶（HL）mRNA的表达水平。结果: (1)与高脂组相比，高脂+SF组动物主动脉粥样斑块面积明显减小（P<0.01），血浆甘油三酯水平显著降低（P<0.01），但血浆胆固醇水平无明显改变（P>0.05）；(2) 与ox-LDL组相比，ox-LDL+SF处理组中HepG2细胞HL mRNA表达水平显著增加（P<0.01），但RAW264.7细胞内胆固醇含量无明显改变（P>0.05）。结论: SF能降低高胆固醇导致的AS斑块面积，具有抗动脉粥样硬化的作用，其作用机制可能与上调HL mRNA表达水平从而降低血浆甘油三酯水平有关，而与血浆胆固醇水平和ox-LDL诱导的巨噬泡沫细胞形成无关。提示血浆甘油三酯升高是AS的独立危险因素，HL介导的甘油三酯代谢途径可能是AS治疗的潜在靶点。     

肾上腺髓质素对尾加压素Ⅱ刺激的血管平滑肌细胞增殖的影响

目的:观察肾上腺髓质素(ADM)对尾加压素Ⅱ(UⅡ)刺激的血管平滑肌细胞(VSMC)增殖的影响。方法:贴块法培养大鼠胸主动脉VSMC;[³H]-胸腺嘧啶([³H]-TdR)掺入测定反映VSMCDNA合成;[γ-³²P]-ATP标记的同位素法测定丝裂素活化蛋白激酶(MAPK)活性。结果:UⅡ(10^-8mol/L)显著促进VSMC-TdR掺入和激活MAPK比对照组分别高38%(P＜0.05)和260%(P＜0.01)。UⅡ加10^-10、10^-9、10^-8mol/LADM组VSMC-TdR掺入分别较UⅡ组低7%(P＞0.05)、32%(P＜0.05)和41%(P＜0.01)。MAPK活性分别低24%(P＞0.05)、32%(P＜0.05)和36%(P＜0.05)。结论:肾上腺髓质素抑制UⅡ诱导的VSMC增殖,可能与其抑制MAPK活性有关。     

Lipoprotein lipase activity in patients with combined hyperlipidaemia

The aetiology of familial combined hyperlipidaemia remains obscure, with both genetic and environmental factors contributing to the phenotype, which is frequently associated with premature coronary heart disease. We have studied lipoprotein lipase (LPL) activity and hepatic lipase (HL) activity in patients with coronary heart disease to determine whether variation in lipase activities contributes to this phenotype. Forty-one patients (mean age 50 years; 30 male) were selected on the basis of cholesterol levels above 6.5 mmol/l and triglyceride levels above 2.2 mmol/1, with apoprotein B values over the 90th percentile. There was a family history of premature coronary heart disease in 78% and a personal history in 64%, at mean age 44, the patient group therefore predominantly corresponded to the common definition of familial combined hyperlipidaemia, appropriate in the absence of molecular markers. None of the patients was diabetic; hypertension and smoking were not over represented. Blood samples were taken following intravenous administration of heparin (100IU/kg body wt), and LPL and HL activities were measured. Mean post-heparin LPL was significantly lower in patients than controls 10 min after heparin administration (2.98 ± 1.04 and 3.86 ± 0.93 mol ml^-1 h^-1, respectively, P = 0.001), and 37% patients had values below the 10th percentile of controls. Both male and female patients had significantly higher HL activities than their respective controls at 5, 10, 20 and 30 minutes postheparin. As expected, both female patients and controls had lower HL activities than males, although this sex difference did not reach statistical significance in the patient group. Mean lipid and lipoprotein results were: cholesterol 8.2 mmol/1; triglycerides 4.2 mmol/l; high-density lipoprotein cholesterol 0.90 mmol/1; apoprotein Al 122 mg/dl; apoprotein B 171 mg/dl; lipoprotein (a) 23 mg/dl (median 10 mg/dl). High-density lipoprotein cholesterol and triglycerides were negatively correlated (r = -0.26, P = 0.05). HL was significantly related to body mass index at all time points whereas the negative correlation between post-heparin LPL and body mass index was significant only 30 min after heparin administration. Post-heparin LPL was only weakly correlated with triglycerides 10 and 20 min after heparin administration. These lipid and lipoprotein results are clearly potentially atherogenic as indicated by the extent of premature coronary heart disease in the group described. A decrease in LPL activity may contribute to this pattern.Abbreviations FCHL familial combined hyperlipidaemia - CHD coronary heart disease - LPL lipoprotein lipase - HL hepatic lipase - HDL high-density lipoprotein - VLDL very low density lipoprotein; - apo apoprotein - TG triglyceride - BMI body mass index Correspondence to: M. Seed     

Polymorphisms of the lipoprotein lipase gene are associated with atherosclerotic cerebral infarction in the Chinese

BACKGROUND: Lipoprotein lipase (LPL), which plays an essential role in plasma lipoprotein metabolism and transportation, appears to be a risk factor for ischemic vascular diseases. Several studies have recently reported the presence of relationship between HindIII, PvuII, Ser447Ter (C-->G) polymorphisms of LPL and ischemic vascular diseases. PURPOSE: We first studied the relationship between LPL polymorphisms and the risk of atherosclerotic cerebral infarction (CI) by detecting the frequencies of LPL HindIII, PvuII and Ser447Ter genotypes and combined genotypes in the Chinese. METHODS: We recruited 185 CI patients, confirmed by cranial computed tomography or magnetic resonance imaging/angiography, or both, and 186 control subjects. Polymerase chain reaction-restriction fragment length polymorphisms technique was used to detect HindIII, PvuII and Ser447Ter polymorphisms of the LPL gene. RESULTS: The frequencies of the H+H+ genotype and H+ allele did not differ between CI and control groups. The frequencies of the P+P+ genotype and P+ allele gene were significantly higher in the CI group (P=0.040, P=0.015). The frequencies of CG+GG genotype and G allele were lower in the CI group (P<0.001, P<0.001). In the CI group, the individuals with P+P+ genotype had a significantly higher level of plasma triglyceride (TG) and a lower level of plasma high density lipoprotein cholesterol (HDL-c). CG+GG genotypes were correlated with significantly higher levels of plasma total cholesterol (TC), HDL-c and low density lipoprotein cholesterol (LDL-c) in the CI group. The frequencies of H+/C and P+/C combined genotypes were higher in the CI group than in controls (P<0.001, P<0.001). The frequency of H+/P+/C combined genotype was significantly higher in the CI group than in controls (P<0.001). CONCLUSIONS: Our study suggests that PvuII and Ser447Ter polymorphisms are associated with lipid profile and CI.     

Effects of a brisk walk on lipoprotein lipase activity and plasma triglyceride concentrations in the fasted and postprandial states

This study aimed to determine whether changes in plasma heparin-releasable lipoprotein lipase (LPL) activity following a brisk walk were associated with decreases in fasting and/or postprandial triglyceride (TG) concentrations. Two groups of pre-menopausal women participated. In one group (fasting study group, n=10), TG concentrations and post-heparin plasma LPL activity were measured in the fasted state on two occasions: ~18 h after a 2-h treadmill walk at 50% maximal oxygen uptake (exercise trial); and after a day of no exercise (control trial). The other group (postprandial study group, n=9) undertook two oral fat tolerance tests (blood samples taken fasting and for 6 h after a high-fat meal), with plasma LPL activity measured 6 h after meal ingestion. Pre-conditions were the same as for the fasting study group (i.e. control and prior exercise). Prior exercise reduced fasting TG concentrations by 23 (7)% (fasting study group) [mean (SEM)] and by 18 (9)% (postprandial study group) (both P<0.05), and the postprandial TG response by 23 (6)% (postprandial study group) (P<0.01). Plasma LPL activity was not significantly increased by exercise in either the fasting or postprandial study groups. However, exercise-induced changes in both fasting and postprandial LPL activity were significantly correlated with the respective exercise-induced changes in fasting TG concentration and the postprandial TG response (r=−0.70 and −0.77 respectively, P<0.05 for both). These data suggest that increased LPL activity may contribute to the hypotriglyceridaemic effect of moderate exercise, although other mechanisms are also likely to be involved. Electronic Publication     

Adipose tissue lipoprotein lipase activity in rats maintained at a reduced body weight

Male rats fed a cellulose-diluted diet maintained a reduced body weight. Adipose tissue lipoprotein lipase (LPL) activity decreased after two days of cellulose feeding, but was not different from chow-fed control levels with weight stabilized at 90% or 70% of the control group. Plasma triglyceride concentration decreased with weight loss and remained depressed with stabilized reduced weight. Regaining lost weight had no effect on LPL activity when compared with chow-fed controls or with levels obtained for the weight-reduced group. However, plasma triglyceride concentration returned to chow-fed control levels with weight gain. The disparity between these results and those obtained in obese human beings lends support to the hypothesis that the increase in adipose tissue LPL activity in weight-reduced obese human beings is indicative of a defect in regulation of adipose tissue metabolism.     

脂蛋白脂酶基因在子痫前期胎盘中的变化及意义

目的研究脂蛋白脂酶(lipoproteinlipase,LPL)mRNA在于痫前期患者胎盘组织中的表达与定位,探讨其在子痫前期病理生理过程中的作用。方法利用cDNA表达谱芯片检查子痫前期胎盘组织与正常胎盘组织之间的差异表达基因;根据筛选结果,采用半定量RT-PCR检测子痫前期患者胎盘组织(研究组)和正常孕妇胎盘组织(对照组)中LPLmRNA的表达;以原位杂交方法进行定位。结果在4轮杂交过程中,共筛选出22条有差异表达的基因,其中LPL基因为表达降低基因之一;正常胎盘组织和子痫前期胎盘组织中均存在LPLmRNA,子痫前期胎盘组织中LPLmRNA表达明显低于正常胎盘组织(0.208±0.067vs0.524±0.139,P<0.05);LPLmRNA分布在胎盘绒毛滋养细胞胞浆。结论胎盘组织中LPL的低表达可能参与子痫前期的发病过程。     

Role of hepatic and lipoprotein lipase in lipoprotein metabolism and atherosclerosis: studies in transgenic and knockout animal models and somatic gene transfer

Hepatic lipase (HL) and lipoprotein lipase (LPL) are the two major lipolytic enzymes responsible for the hydrolysis of triglycerides and phospholipids present in circulating plasma lipoproteins. Both lipases are attached to the vascular endothelium via cell surface proteoglycans. HL is primarily involved in the metabolism of chylomicron remnants, intermediate density lipoproteins and high-density lipoproteins whereas LPL catalyzes the hydrolysis of triglycerides from chylomicrons and very low-density lipoproteins. In addition to their traditional function as lipolytic enzymes, HL and LPL appear to serve as ligands that mediate the interaction of lipoproteins to cell surface receptors and/or proteoglycans. Over the past several years significant advances have been made in our understanding of new, alternative mechanisms by which HL and LPL modulate lipoprotein metabolism and the development of atherosclerosis in vivo. This review will summarize some of the new insights generated from the study of transgenic and knockout HL and LPL animal models as well as somatic gene transfer of these two lipases.     

Overexpression of lipoprotein lipase in transgenic rabbits leads to increased small dense LDL in plasma and promotes atherosclerosis

Lipoprotein lipase (LPL) is a key enzyme in the hydrolysis of triglyceride-rich lipoproteins. Previous studies using transgenic mice and rabbits have demonstrated that high level of LPL activity in adipose and skeletal muscle protects against diet-induced hypercholesterolemia and subsequently prevents aortic atherosclerosis. However, it is unknown, per se, whether increased LPL activity itself is antiatherogenic, or whether the antiatherogenic effect of LPL is dependent upon the LPL lipid-lowering effect. To address this issue, we fed LPL transgenic and littermate rabbits diets containing different amounts of cholesterol (0.3-0.6%) adjusted to maintain their plasma cholesterol concentrations at similarly high levels for 16 weeks. We analyzed their lipoprotein profiles and compared their susceptibility to atherosclerosis. The results showed that the overexpression of LPL in transgenic rabbits reduced remnant lipoproteins (beta-VLDL, d<1.006 g/ml) but concomitantly led to a significant increase of the large (d=1.02-1.04 g/ml) and small LDLs (d=1.04-1.06 g/ml) compared to the amounts in control rabbits. Furthermore, we found that with equally high hypercholesterolemia, transgenic rabbits developed 1.8-fold more extensive aortic atherosclerosis than control rabbits. To examine the hypothesis that altered lipoprotein profiles may be responsible for the enhanced atherosclerosis in transgenic rabbits, we studied the atherogenic properties of apoB-containing lipoproteins in vitro. These studies revealed that small-sized LDLs of transgenic rabbits were more susceptible to copper-induced oxidation and had higher affinity to biglycan than large remnant lipoproteins. We conclude, therefore, that LPL exerts a dual function in terms of its atherogenicity, namely antiatherogenicity, through enhancing receptor-mediated remnant lipoprotein catabolism and proatherogenicity via the generation of a large amount of small-sized LDLs. At an equal atherogenic-cholesterol level, small and dense LDLs are more atherogenic than large remnant lipoproteins.     

Increase in hepatic lipase activity after testosterone substitution in men with hypogonadism of pituitary origin

Ten men with hypogonadism of pituitary origin were studied before and during testosterone substitution therapy with regard to effects on the activities of hepatic lipase (HL) and lipoprotein lipase (LPL) in postheparin plasma, and on plasma lipoprotein concentrations. The mean (+/- SEM) testosterone level increased from 1.8 +/- 0.5 to 16.3 +/- 2.4 nmol/l. The mean activity of HL rose from 327.1 +/- 35.2 to 432.8 +/- 57.2 mU/ml (p less than 0.02), while the activity of LPL did not change significantly, 71.0 +/- 9.1 mU/ml before and 62.2 +/- 3.8 mU/ml after treatment. No significant alterations in lipoprotein concentrations were recorded. These results indicate that a normal testosterone level is of importance for maintaining the activity of HL in men, thereby contributing to the sex difference previously recorded for HL activity.     

Lipoprotein lipase of human postheparin plasma and adipose tissue in relation to physical training

Adipose tissue lipoprotein lipase and postheparin plasma triglyceride lipase activities were measured in 28 men differing in their physical training activity. They were divided into 4 subclasses based on their training intensity. The two most active classes (17 subjects) having regular heavy exercise at least 4 times a week were considered as the actively training group, and the other two (11 subjects) classes not training regularly as the control group. In postheparin plasma, the lipoprotein lipase activities were not different between the two groups, whereas training subjects had significantly (P<0.02) lower hepatic lipase activities. Adipose tissue lipoprotein lipase activity was in the training group at about 70% higher level on an average than in the controls (P<0.10). A significant positive correlation (r=0.38, P<0.05) was obtained between the adipose tissue lipoprotein lipase activity and the level of physical activity. Our data suggest that even moderate inter-group differences in the physical training activity are reflected as measurable alterations in the adipose tissue lipoprotein lipase activity in man.     

Adipose tissue lipoprotein lipase activity in rats with obesity-inducing hypothalamic knife cuts

Three experiments examined the effects of obesity-inducing parasagittal hypothalamic knife cuts on adipose tissue lipoprotein lipase (LPL) activity in female rats. Knife cuts induced a 4-fold increase in adipose tissue LPL activity. Knife-cut rats with controlled insulin levels were hyperphagic but showed no increase in adipose tissue LPL activity or body weight gain. Prevention of the hyperphagia by food restriction also blocked the changes in LPL activity and weight gain. Finally, exogenous insulin treatment increased adipose tissue LPL activity in the absence of hyperphagia in neurologically-intact rats. We conclude that increased adipose tissue LPL activity may play a permissive role in the development of hypothalamic obesity, with the increase in enzyme activity being secondary to knife-cut-induced hyperinsulinemia.