Estradiol increases the secretion of hepatic lipase by rat hepatocyte cultures

Emmison, Neil; Zammit, Victor A.; Agius, Loranne

doi:10.1016/0005-2760(91)90035-g

Cited by 2 publications

(4 citation statements)

References 54 publications

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“…Radiochemicals were from Amersham International (Amersham, Bucks., U.K.). Sources of other materials were as described previously [19,42].…”

Section: Materials and Methods Materialsmentioning

confidence: 99%

“…For the determination of the secreted triacylglycerol, chloroform/methanol extracts were extensively washed with synthetic upper phase that contained no glycerol, and the lipid-containing lower phase was lyophilized and sonicated with extraction buffer [42] prior to determination of triacylglycerol by an enzymic method [48]. Palmitate, lactate dehydrogenase, acetoacetate, D-3-hydroxybutyrate and cellular triacylglycerol were determined enzymically as previously described [19,46]. Cellular protein was determined by an automated Lowry method [49].…”

Section: Determination Of Metabolic Parametersmentioning

confidence: 99%

“…After cell attachment, hepatocyte monolayers (in 12-well plates) were incubated for 10 h with 0.5 ml of MEM containing 10 nM-dexamethasone, 10 units of heparin (unless stated otherwise) and other additions as indicated. Determination of hepatic lipase activity was as described elsewhere [19].…”

Section: Secretion Of Hepatic Lipasementioning

confidence: 99%

“…Measurement of triacylglycerol secretion by hepatocyte cultures is based on the assumption that extracellular degradation is negligible [1]. However, hepatocyte cultures secrete hepatic lipase [15][16][17][18][19], which catalyses the hydrolysis of a variety of glycerolipids, including triacylglycerol [20][21][22][23][24][25]. Hepatic lipase deficiency [26,27] is associated with elevated circulating concentrations of VLDL.…”

Section: Introductionmentioning

confidence: 99%

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Triacylglycerol accumulation and secretion in hepatocyte cultures. Effects of insulin, albumin and Triton WR 1339

Emmison

Zammit

Agius

1992

Biochemical Journal

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We have investigated the possibility that the apparent inhibition of very-low-density lipoprotein (VLDL)-triacylglycerol secretion by the addition of insulin to rat hepatocyte cultures may result from insulin-mediated enhancement of hepatic lipase secretion and, consequently, of extracellular triacylglycerol hydrolysis. We have, therefore, studied the effects of the inhibitor of lipase activity, Triton WR 1339, on the secretion of triacylglycerol by cultured rat hepatocytes. Incubation of hepatocyte cultures with increasing concentrations of Triton WR 1339 increased the accumulation of acylglycerol in the medium, suggesting that, in normal incubations, a substantial rate of degradation of secreted triacylglycerol does occur and that it results in an under-estimation of the rate of triacylglycerol secretion. However, Triton did not counteract the inhibitory effects of insulin, suggesting that the observed increased activity of hepatic lipase induced by the hormone cannot account for the inhibition of acylglycerol accumulation in the medium that occurred in the presence of insulin. BSA increased the accumulation of triacylglycerol in culture media by about 2-fold and also decreased the activity of hepatic lipase by 80%. A causative relationship between these two effects was supported by the further observation that Triton abolished the effects of BSA on triacylglycerol accumulation in the medium. The implications of these data for the validity of the use of Triton for the study of hepatic rates of triacylglycerol production in vivo and of secretion by hepatocytes in vitro are discussed.

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“…Radiochemicals were from Amersham International (Amersham, Bucks., U.K.). Sources of other materials were as described previously [19,42].…”

Section: Materials and Methods Materialsmentioning

confidence: 99%

Section: Determination Of Metabolic Parametersmentioning

confidence: 99%

Section: Secretion Of Hepatic Lipasementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Triacylglycerol accumulation and secretion in hepatocyte cultures. Effects of insulin, albumin and Triton WR 1339

Emmison

Zammit

Agius

1992

Biochemical Journal

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Independent responsiveness of frog liver low-density lipoprotein receptor and HMGCoA reductase to estrogen treatment

Croce

Bruscalupi

Trentalance³

1997

Pfl�gers Archiv European Journal of Physiology

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Cholesterol metabolism in the female frog exhibits circannual modifications which parallel plasma estrogen fluctuations. Estrogens enhance production and lipidation of the yolk precursor vitellogenin by inducing the transcription of its gene and by stimulating the activity of 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase. The time dependence of the effects that these hormones have on HMGCoA reductase and the low-density lipoprotein (LDL) receptor in the liver of Rana esculenta complex has been investigated. Following estrogen treatment, the levels of LDL receptor mRNA and protein gradually increased, with a maximum concentration observed at 3 days. The HMGCoA reductase protein level increased progressively, while the mRNA level was not significantly modified. Thus the LDL receptor and HMGCoA reductase in frog behave independently after estrogen stimulation, as already reported to occur in the rat. This suggests a uncoordinated regulation that might be even partially related with the changes in cellular cholesterol content.

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Estradiol increases the secretion of hepatic lipase by rat hepatocyte cultures

Cited by 2 publications

References 54 publications

Triacylglycerol accumulation and secretion in hepatocyte cultures. Effects of insulin, albumin and Triton WR 1339

Triacylglycerol accumulation and secretion in hepatocyte cultures. Effects of insulin, albumin and Triton WR 1339

Independent responsiveness of frog liver low-density lipoprotein receptor and HMGCoA reductase to estrogen treatment

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