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PubMed2006

Maternal lipid metabolism and placental lipid transfer.

During early pregnancy, long-chain polyunsaturated fatty acids (LC-PUFA) may accumulate in maternal fat depots and become available for placental transfer during late pregnancy, when the fetal growth rate is maximal and fetal requirements for LC-PUFAs are greatly enhanced. During this late part of gestation, enhanced lipolytic activity in adipose tissue contributes to the development of maternal hyperlipidaemia; there is an increase in plasma triacylglycerol concentrations, with smaller rises in phospholipid and cholesterol concentrations. Besides the increase in plasma very-low-density lipoprotein, there is a proportional enrichment of triacylglycerols in both low-density lipoproteins and high-density lipoproteins. These lipoproteins transport LC-PUFA in the maternal circulation. The presence of lipoprotein receptors in the placenta allows their placental uptake, where they are hydrolysed by lipoprotein lipase, phospholipase A(2) and intracellular lipase. The fatty acids that are released can be metabolized and diffuse into the fetal plasma. Although present in smaller proportions, maternal plasma non-esterified fatty acids are also a source of LC-PUFA for the fetus, their placental transfer being facilitated by the presence of a membrane fatty acid-binding protein. There is very little placental transfer of glycerol, whereas the transfer of ketone bodies may become quantitatively important under conditions of maternal hyperketonaemia, such as during fasting, a high-fat diet or diabetes. The demands for cholesterol in the fetus are high, but whereas maternal cholesterol substantially contributes to fetal cholesterol during early pregnancy, fetal cholesterol biosynthesis rather than cholesterol transfer from maternal lipoproteins seems to be the main mechanism for satisfying fetal requirements during late pregnancy.

Adipose Tissue↗
PubMedDate not supplied

[Effect of pregnancy on carbohydrate and lipid metabolism of the mother--I. Kinetics of various parameters of carbohydrate and lipid metabolism and of various hormones as a function of the length of pregnancy].

Numerous factors influence fetal weight increase and growth. To permit a discussion of biochemical influences on fetal growth, maternal substrates and hormones which influence lipid and carbohydrate metabolism were measured and their relationships were analyzed. In 173 patients the following substrates were measured between the 8th and 40th week of pregnancy: glucose in whole blood and urine, glycerin, triglycerides, total cholesterol, free cholesterol and the hormones HGH, HPRL, HPL, IRI and estriol (E3). A group of nonpregnant and a group of recently delivered women served as controls. The glucose concentration in the whole blood of the mother diminished during pregnancy from 88.3 mg/100 ml to 77.4 mg/100 ml (2 alpha less than 0.05, r = 0.47, n = 77). It was still below the value for the non-pregnant controls post partum (63.6 mg/100 ml as compared to 92.3 mg/100 ml). Glucosuria increased during pregnancy, reaching a maximum in the second trimester. The glycerin concentration was unchanged during pregnancy. As with the post-partial group (0.53 mg/100 ml) the values were lower than those for the non-pregnant control group (1.14 mg/100 ml). The triglyceride concentration increased during pregnancy from 90.3 mg/100 ml to 179.7 mg/100 ml (2 alpha less than 0.00004, r = 0.6, n = 29). In the second and third trimesters (162.9 mg/100 ml, 179.7 mg/100 ml) and post partum (162.3 mg/100 ml) the values were higher than that for the non-pregnant controls (101.5 mg/100 ml). (ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2001

Re-examination of the mechanisms regulating nuclear inositol lipid metabolism.

Although inositol lipids constitute only a very minor proportion of total cellular lipids, they have received immense attention by scientists since it was discovered that they play key roles in a wide range of important cellular processes. In the late 1980s, it was suggested that these lipids are also present within the cell nucleus. Albeit the early reports about the intranuclear localization of phosphoinositides were met by skepticism and disbelief, compelling evidence has subsequently been accumulated convincingly showing that a phosphoinositide cycle is present at the nuclear level and may be activated in response to stimuli that do not activate the inositol lipid metabolism localized at the plasma membrane. Very recently, intriguing new data have highlighted that some of the mechanisms regulating nuclear inositol lipid metabolism differ in a substantial way from those operating at the cell periphery. Here, we provide an overview of recent findings regarding the regulation of both nuclear phosphatidylinositol 3-kinase and phosphoinositide-specific phospholipase C-beta1.

Animals↗
PubMed1984

Regulation of lipid metabolism by a lipid-carrying protein.

The overall conclusion to be made from the information presented here is that for many reasons SCP is a highly unusual protein. Some of these reasons are, first, SCP serves as cofactor for a number of different membrane-bound enzymes catalyzing specific steps in lipid metabolism. Second, SCP is involved in intracellular transport or movement of both cholesterol and fatty acids. Third, SCP is remarkably abundant and ubiquitous; its structure is conserved throughout nature. Fourth, SCP is exported to the blood stream from its site of synthesis by some, perhaps unique, mechanism and then rapidly taken up by specific tissues, e.g., the adrenal. Fifth, SCP is free in the cytosol and can also move to the inner mitochondrial membrane, where it is tightly bound. Sixth, SCP undergoes a dramatic diurnal variation in amount, reflecting changes in synthetic rate. Its half-life is less than an hour. Seventh, the diurnal variation in amount is triggered by feeding and influenced by several hormones. The diurnal variation is lost but a high level of SCP is maintained in the face of debilitating conditions, i.e., starvation, diabetes. Eighth, malignant cells exhibit defects in the uptake, synthesis, or turnover of SCP. Ninth, the synthesis of SCP is regulated by the efficiency of translation of its ever abundant mRNA. Tenth, there is much more to be learned about the functions and regulation of SCP.

Adrenal Glands↗
PubMed1997

Changes in blood coagulation, platelet aggregation, and lipid metabolism in rats given lipids containing docosahexaenoic acid.

In order to identify an adequate intake level of docosahexaenoic acid (DHA), changes in various parameters related to health benefits were studied in rats fed on diets containing 10% test lipids at different n-3(DHA)/n-6 ratios for two weeks. An evaluation of the critical level of the dietary n-3/n-6 ratio which had a significant effect on the parameters of several tissues indicated that the response to the dietary ratios differed according to the parameter, the variation in ratio ranging approximately from 0.20 to 1.77 with either a positive or negative effect on the health benefit. These results suggest that a suitable intake level of DHA would be within this range. In view of safety, however, the critical level for the dietary n-3/n-6 ratio may be around 0.56, as shown by a detailed analysis on the lower limit level of the harmful parameters. We thus propose that the dietary intake of DHA should not be more than 0.56 in terms of the n-3/n-6 ratio.

Animals↗
PubMed1998

Changes in platelet aggregation and lipid metabolism in rats given dietary lipids containing different n-3 polyunsaturated fatty acids.

We compared the effects of different n-3 polyunsaturated fatty acids (PUFA) on platelet aggregation and lipid metabolism in rats. alpha-Linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were used as n-3 PUFA sources. The rats were fed diets containing 10% lipids (polyunsaturated/saturated fatty acid (P/S) ratio = 1.0; n-3/n-6 = 0.02 for the control group, 0.2 for the test groups) for two weeks. The platelet counts, platelet aggregation, and production of thromboxane A2 (TXA2), plasma total cholesterol (TC) and triacylglycerols (TG) were not different between the ALA group and the control group, but showed a decreasing tendency for the EPA group and significant decreases for the DHA group. The production of prostacyclin in the aorta was significantly decreased in all of the n-3 PUFA groups when compared with that in the control group. Liver TC and TG concentrations were significantly decreased in the DHA group when compared with those in the control group. Based on the above, it is assumed that the physiological action exerted by n-3 PUFA differs by type and that DHA is a more effective n-3 PUFA, both for suppressing platelet aggregation and for modulating lipid metabolism in the plasma and liver of rats.

Animals↗
PubMed1992

[Lipid metabolism in patients with insulin dependent diabetes. IV. Effect of sex, age, excess body weight, duration of diabetes, insulin dosage and family history on lipid metabolism in patients with insulin dependent diabetes].

The levels of the following blood serum lipid constituents: total cholesterol, triglycerides, phospholipids, HDL-cholesterol, apolipoproteins AI, AII and B, and lipoprotein fractions have been determined in patients with insulin-dependent diabetes in relation to sex, age, duration of diabetes, coexistence of obesity, insulin dosage and history of genetic predispositions. The age of the patients was between 1.3 and 22 years and the duration of the disease ranged between 3 months and 15 years. The analysis of the results revealed that sex, age, daily insulin dose and the known genetic predispositions have no influence on the values of the parameters of lipid metabolism. However, an increase in the levels of cholesterol, HDL-cholesterol, triglycerides and apolipoproteins AI and B was observed along with the progressing duration of the disease. An increase in the levels of cholesterol, apolipoprotein B and beta-lipoprotein, and a decrease in the level of alpha-lipoprotein have been found in diabetic children with coexisting obesity. The above analysis indicates that besides metabolic control of diabetes its duration and accompanying obesity may negatively influence the course of the disease contributing to the precocious development of atherosclerosis.

Adolescent↗