THE EFFECT OF MATERNAL MALNUTRITION ON THE PROGENY IN THE RAT. STUDIES IN VITRO OF ADIPOSE TISSUE LIPOGENESIS AND LIPOPROTEIN LIPASE ACTIVITY FOLLOWING FRUCTOSE FEEDING

1973 ◽  
Vol 51 (6) ◽  
pp. 811-824 ◽  
Author(s):  
Katrine I McLeod ◽  
PJ Nestel ◽  
RB Goldrick
1978 ◽  
Vol 176 (3) ◽  
pp. 865-872 ◽  
Author(s):  
P Ashby ◽  
D P Bennett ◽  
I M Spencer ◽  
D S Robinson

Changes in adipose-tissue lipoprotein lipase activity that are independent of protein synthesis were investigated in an incubation system in vitro. Under appropriate conditions at 25 degrees C a progressive increase in the enzyme activity occurs that is energy-dependent. Part of the enzyme is rapidly inactivated when the tissue is incubated with adrenaline or adrenaline plus theophylline. The mechanism of this inactivation appears to be distinct from, and to follow, the activation of the enzyme. A hypothesis is presented to account for the results in terms of an activation of the enzyme during obligatory post-translational processing and a catecholamine-regulated inactivation of the enzyme as an alternative to secretion from the adipocyte.


1961 ◽  
Vol 200 (4) ◽  
pp. 841-846 ◽  
Author(s):  
Ruth Landolt ◽  
E. B. Astwood

A crude pituitary extract, potent in inducing visible lipemia in male rabbits, caused a) an eightfold increase in free fatty acids of the serum 1–2 hours after injection, followed by a 2.5-fold increase of fatty acid output in vitro from adipose tissue, removed 4 hours after injection; b) a reduction in lipoprotein lipase activity of adipose tissue at the same time; c) an increase in liver fat which was already prominent at 4 hours and which preceded the ninefold increase of total lipids in the serum at 24 hours. The lipemia was prevented by large doses of heparin. A direct effect of the extract on adipose tissue in vitro was observed; this was partially inhibited by insulin and glucose. Pig growth hormone given in corresponding doses produced the same effect, but to a smaller degree. It was concluded that the hyperlipemia is due to a separate factor, and that the lipemia is a consequence of excessive lipolysis in association with diminished lipoprotein lipase activity.


1983 ◽  
Vol 210 (3) ◽  
pp. 639-643 ◽  
Author(s):  
M A Lasunción ◽  
E Herrera

Lipoprotein lipase activity was higher in fat-pad pieces than in isolated adipocytes from the same fed rats, whereas hydrolysis of triacylglycerols from triacylglycerol-rich lipoproteins was similar in the two preparations when incubated either in basal conditions or in the presence of heparin. In both preparations there was a similar release of lipoprotein lipase activity into the medium during basal incubation, enhanced by the presence of heparin. In fat-pad pieces, but not in isolated adipocytes, incubation with heparin produced a decrease in the lipoprotein lipase activity measured in the tissue preparation. In fat-pad pieces from 24 h-starved rats, lipoprotein lipase activity was the same as in isolated adipocytes from the same animals and incubation with heparin did not affect the appearance of lipoprotein lipase in the medium or the utilization of triacylglycerols from triacylglycerol-rich lipoproteins. These results support the following conclusions. (1) The effectiveness of lipoprotein lipase in adipose tissue preparations in vitro depends more on its availability to the substrate than on its total activity. (2) Heparin acts on adipose tissue preparations from fed animals both by enhancing the release of pre-existing extracellular enzyme (which is absent in isolated adipocytes) and by enhancing the transfer outside the cells of the intracellular (and mainly undetectable) enzyme that is activated in the secretion process. (3) In adipose tissue from starved animals there is not only a decrease in the active extracellular form of lipoprotein lipase activity but also a reduction in the intracellular (and mainly undetectable) pool of the enzyme.


1980 ◽  
Vol 188 (1) ◽  
pp. 185-192 ◽  
Author(s):  
P Ashby ◽  
D S Robinson

The lipoprotein lipase activity of epididymal fat-bodies from starved rats was measured during incubations at 37 degrees C in vitro. Protein synthesis independent activation of the enzyme, previously observed during incubations at 25 decrease C, also occurs at 37 degrees C. Protein-synthesis-dependent increases in the activity of the enzyme occur in the presence of insulin and are markedly potentiated by glucocorticoids. The effects on the activity of the enzyme of insulin alone, or in the presence of glucocorticoids, are correlated with its effects on total protein synthesis in the tissue. Adrenaline antagonizes the increase in activity of the enzyme brought about by insulin and abolishes the potentiation of insulin action by glucocorticoids. These changes may be due, at least in part, to its stimulation of inactivation of the enzyme in the tissue. It is suggested that changes in adipose-tissue lipoprotein lipase activity that occur with changes in nutritional status in vivo result from the combined effects of changes in plasma insulin and glucocorticoid concentrations.


1993 ◽  
Vol 16 (1) ◽  
pp. 6-10 ◽  
Author(s):  
Hiroshi UEKI ◽  
Yusuke OHKURA ◽  
Toshio MOTOYASHIKI ◽  
Nobuaki TOMINAGA ◽  
Tetsuo MORITA

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