Ovarian modulation of lipoprotein lipase activity in white adipose tissue of ground squirrels

Golden-mantled ground squirrels were ovariectomized (OVX) or Sham-OVX during the weight gain phase of the circannual body weight cycle. Other squirrels, OVX or Sham-OVX during the weight loss phase, were subcutaneously implanted with estradiol-filled or empty Silastic capsules. The mass of several fat pads as well as adipose tissue lipoprotein lipase (LPL) activity were determined at autopsy. Ovariectomy at either phase of the annual cycle was without effect on body weight. However, LPL activity of the parametrial fat pad was increased in OVX as compared to Sham-OVX squirrels. Fourteen days of estradiol treatment during the weight loss phase decreased the mass and LPL activity of the retroperitoneal fat depot but did not affect these parameters in perirenal adipose tissue. Although estradiol exerts different or opposite effects on body mass and food intake of rats and ground squirrels, ovariectomy and estrogen treatment affect LPL activity in a similar fashion in both species.     

Activation of adipose tissue lipoprotein lipase by lipoprotein fractions from normals and patients with type V hyperlipoproteinemia

Summary The effects of the main lipoprotein density classes on the human adipose tissue lipoprotein lipase activity were studied. A dose-dependent stimulation of lipoprotein lipase activity was obtained for HDL and, to a lesser extent, for VLDL on a constant weight basis. LDL exerted virtually no effect. At higher concentrations, HDL as well as VLDL inhibited the stimulated lipolytic activity. In type V hyperlipoproteinemia, the stimulating effect of VLDL and of HDL was significantly lower, whereas the inhibiting action of HDL was markedly increased.     

Food intake and adipose tissue lipoprotein lipase activity after hypothalamic estradiol benzoate implants in rats

Unilateral implants of estradiol benzoate in the ventromedial hypothalamus (VMH) reduced food intake in ovariectomized rats. The implants did not produce cornification of the vaginal epithelium. Furthermore, the reduction in food intake was observed in the absence of changes in adipose tissue lipoprotein lipase activity or cytoplasmic progestin receptor levels. These results suggest that, while estradiol may normally act at both central and peripheral sites to affect food intake and body weight, estrogenic stimulation of just the VMH may be sufficient to reduce food intake in ovariectomized rats.     

茶多酚对实验性动脉粥样硬化兔脂蛋白脂酶、肝脂酶活性的影响及意义

目的:观察动脉粥样硬化(AS)发生发展过程中脂蛋白脂酶(LPL)、肝脂酶(HL)活性的变化及茶多酚(TP)的作用。方法:高脂食物AS模型兔口服茶多酚200μg·g^-1·d^-1,测定血浆中LPL、HL活性,同时用组织化学法检测动脉壁层组织中LPL活性、肝组织中HL活性。结果:AS组动脉粥样硬化病变血管壁与正常对照组血管壁组织中LPL活性差异无显著(P＞0.05);AS组肝组织中HL活性明显低于正常对照组(P＜0.05)。TP组肝组织中HL活性明显高于AS组(P＜0.05)、血浆中TC和LDL-c水平低于AS组(P＜0.05)、动脉粥样硬化斑块面积低于AS组(P＜0.05)。各组间血浆LPL、HL活性水平差异无显著(P＞0.05)。结论:茶多酚能增加实验性AS兔肝组织中HL脂酶活性,这一作用与降低血浆胆固醇水平和抗动脉粥样硬化密切相关。     

Regional adipose tissue and lipid and lipoprotein levels in HIV-infected women

BACKGROUND: HIV infection and antiretroviral therapy are associated with dyslipidemia, but the association between regional body fat and lipid levels is not well described. METHODS: Multivariable linear regression analyzed the association between magnetic resonance imaging-measured regional adipose tissue and fasting lipids in 284 HIV-infected and 129 control women. RESULTS: Among African Americans, HIV-infected women had higher triglyceride (116 vs. 83 mg/dL; P < 0.001), similar high-density lipoprotein (HDL; 52 vs. 50 mg/dL; P = 0.60), and lower low-density lipoprotein (LDL; 99 vs. 118 mg/dL; P = 0.008) levels than controls. Among whites, HIV-infected women had higher triglyceride (141 vs. 78 mg/dL; P < 0.001), lower HDL (46 vs. 57 mg/dL; P < 0.001), and slightly lower LDL (100 vs. 107 mg/dL; P = 0.059) levels than controls. After adjustment for demographic and lifestyle factors, the highest tertile of visceral adipose tissue (VAT) was associated with higher triglyceride (+85%, 95% confidence interval [CI]: 55 to 121) and lower HDL (-9%, 95% CI: -18 to 0) levels in HIV-infected women; the highest tertile of leg subcutaneous adipose tissue (SAT) was associated with lower triglyceride levels in HIV-infected women (-28%, 95% CI: -41 to -11) and controls (-39%, 95% CI: -5 to -18). After further adjustment for adipose tissue, HIV infection remained associated with higher triglyceride (+40%, 95% CI: 21 to 63) and lower LDL (-17%, 95% CI: -26 to -8) levels, whereas HIV infection remained associated with lower HDL levels (-21%, 95% CI: -29 to -12) in whites but not in African Americans (+8%, 95% CI: -2 to 19). CONCLUSIONS: HIV-infected white women are more likely to have proatherogenic lipid profiles than HIV-infected African American women. Less leg SAT and more VAT are important factors associated with adverse lipid levels. HIV-infected women may be at particular risk for dyslipidemia because of the risk for HIV-associated lipoatrophy.     

Responses of adipose and muscle lipoprotein lipase to chronic infection and subsequent acute lipopolysaccharide challenge

Infection of male Swiss Webster mice with Toxoplasma gondii or Neospora caninum leads to long-term alterations in energy balance. Following an initial 20 to 30% weight loss in all T. gondii-infected mice, half of the animals regain most of the lost weight (gainers), whereas the others maintain their low body weight (nongainers). Infection with N. caninum does not elicit weight loss. Lipoprotein lipase (LPL), the enzyme responsible for plasma triglyceride (TG) clearance and partitioning among tissues, is under tissue-specific modulation associated with energy balance. It is also a major determinant of infection-induced hypertriglyceridemia. This study aimed to assess the long-term modulation of adipose and muscle LPL activity in mice infected with T. gondii or N. caninum, to evaluate the effects of subsequent acute lipopolysaccharide (LPS) administration, and to relate LPL modulation in these conditions with infection-related changes in body weight gain. Twenty-eight days after infection, LPL activity in muscle of both gainer and nongainer T. gondii-infected mice was reduced by 40 to 50% compared with the levels in controls and N. caninum-infected mice, whereas LPL activity in adipose depots remained unchanged in all infected groups compared to the level in controls. LPS (from Escherichia coli, 100 ng/kg) injection induced a global reduction in adipose LPL in all groups, as assessed 90 min later. In both T. gondii-infected subgroups, muscle LPL was not further reduced by LPS treatment, whereas it was decreased by 40 to 50% in muscles of control and N. caninum-infected mice. Pre-LPS TG levels in plasma were similar in all groups. LPS greatly increased TG levels in plasma in both control and N. caninum-infected animals, whereas it did not alter those of T. gondii-infected gainer or nongainer animals. These results show that (i) independently of the extent of postinfection weight gain, long-term infection with T. gondii chronically reduces muscle LPL, which becomes unresponsive to acute endotoxemia; (ii) modulation of tissue LPL activity during chronic T. gondii infection favors TG partitioning towards adipose tissue; and (iii) skeletal muscle LPL is a key determinant of the acute response of triglyceridemia to LPS.     

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.