Effects of hormones on apolipoprotein secretion in cultured rat hepatocytes

Lin, Reneé C.

doi:10.1016/0026-0495(88)90009-1

Cited by 21 publications

(13 citation statements)

References 34 publications

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“…Our results show that insulin inhibits the mRNA expression of apoA-I in primary rat hepatocytes. This is in contrast to observations made in previous reports [22,23]. One study, however, shows that insulin at physiological concentrations and an incubation time of 12 hours inhibits the secretion of apoA-I from rat hepatocytes [24].…”

Section: Discussioncontrasting

confidence: 81%

“…ApoA-I regulation by insulin may be affected by dose and time since Masumoto et al [24] and our results show that 10 nM insulin had an inhibitory effect after 12 and 24 hours, respectively. It appears that increased incubation time (44 or 96 hours) with both physiological and supraphysiological doses [22,23] switches the effect to be positive suggesting that insulin may have both fast and long term effects on target genes.…”

Section: Discussionmentioning

confidence: 99%

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et al. 2007

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Background: Scavenger receptor type B class I (SR-BI), ABC transporter A1 (ABCA1) -and G1 (ABCG1) all play important roles in the reverse cholesterol transport. Reverse cholesterol transport is a mechanism whereby the body can eliminate excess cholesterol. Here, the regulation of SR-BI, ABCA1, and ABCG1 by dexamethasone (a synthetic glucocorticoid) and insulin were studied in order to gain more insight into the role of these two hormones in the cholesterol metabolism.

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Section: Discussioncontrasting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

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et al. 2007

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“…Fibronectins affect a variety of biological processes such as phagocytosis, hemostasis, cell differentiation, growth and regeneration (46, 64, 65). In carbon tetrachloride-induced cirrhosis, fibronectin deposits in the space of Disse were observed before the accumulation of other components of the extracellular matrix, and therefore a pacemaker function of this protein was postulated in fibrogenesis (66 A few researchers (73,74) have reported that dexamethasone caused no significant or only minimal changes in apolipoprotein E secretion of cultured murine macrophages and rat hepatocytes. In contrast, our experiments indicate a dexamethasone-induced reduction of apolipoprotein E synthesis at the protein and RNA levels in rat fat-storing cells.…”

Section: Discussionmentioning

confidence: 98%

Dexamethasone modulates α2-macroglobulin and apolipoprotein E gene expression in cultured rat liver fat-storing (Ito) cells

Ramadori¹,

Knittel²,

Schwögler³

et al. 1991

Hepatology

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Fat-storing (Ito) cells are perisinusoidal liver cells thought to play a central role in vitamin A metabolism and fibrongenesis. Glucocorticoids have been shown to be beneficial in the treatment of certain types of liver diseases by delaying the development of cirrhosis. To study the regulatory effects of dexamethasone on Ito cell gene expression, Ito cells were isolated from normal rat liver and primary cultures were established. The effect of dexamethasone on the synthesis of alpha 2-macroglobulin, apolipoprotein E, fibronectin and actin was examined. Protein synthesis was studied both at the protein level and at the RNA level by means of biosynthetic labeling, immunoprecipitation followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by Northern blot analysis of total RNA. After exposure to dexamethasone for 20 hr, alpha 2-macroglobulin protein synthesis was increased threefold, whereas apolipoprotein E expression was decreased 80%. Biosynthesis of fibronectin remained unaffected by hormone treatment. The dexamethasone effect became detectable 5 hr after beginning the exposure. Deinduction kinetic experiments showed that the glucocorticoid effect was detectable more than 12 hr after the replacement of the dexamethasone-containing culture medium by medium without the hormone. Corresponding to the data obtained at the protein level, dexamethasone increased the steady-state levels of alpha 2-macroglobulin-specific messenger RNA and reduced apolipoprotein E-specific transcripts, whereas fibronectin and actin messenger mRNA remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…[12,15] Hepatic apoAi mRNA increased in cultured rat hepatocytes exposed to glucocorticoids. [16] Transient down-regulation of LDL receptors in rats followed methylprednisolone admini stration, accounting for elevated LDL and TC. [17] Overall, animal models illustrate marked effects on HDL and some adverse effects on LDL, as well as differences between the drugs.…”

Section: Animal Studies Of Lipid Changes In Steroid Usementioning

confidence: 99%

The influence of glucocorticoids on lipid and lipoprotein metabolism and atherosclerosis

Ross

Marais

2014

S Afr Med J

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Lipoproteins transport lipids in the circulation in four major pathways: (i) a postprandial (exogenous) pathway for chylomicrons; (ii) an endogenous pathway involving very-low-density lipoprotein (VLDL) for triglyceride (TG) transport from the liver; (iii) a lowdensity lipoprotein (LDL) pathway from a proportion of VLDL as a source of cholesterol for cells; and (iv) a reverse cholesterol transport pathway by high-density lipoprotein (HDL).[1] These pathways and the reported effects of glucocorticoids are shown in Fig. 1. Exogenous TG pathwayChylomicrons, comprising 85 -90% TG and containing apolipoprotein B (apo B)-48 (apoB48), apolipoprotein Ai (apoAi) and apolipoprotein Aiv (apoAiv), are produced in enterocytes, traverse the thoracic duct and ultimately reach the systemic circulation. Lipoprotein lipase anchored on cells by heparan sulphate proteoglycans hydrolyses TG at the vascular endothelium, yielding non-esterified fatty acids (NEFAs) and remnants, proportionately richer in cholesterol esters. Chylomicron remnants are rapidly cleared by liver remnant receptors, [2] as a result of apolipoprotein E (apoE) acquired in the circulation. Dietary fat restriction will have a significant impact on severe hypertriglyceridaemia.

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Effects of hormones on apolipoprotein secretion in cultured rat hepatocytes

Cited by 21 publications

References 34 publications

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Dexamethasone modulates α2-macroglobulin and apolipoprotein E gene expression in cultured rat liver fat-storing (Ito) cells

The influence of glucocorticoids on lipid and lipoprotein metabolism and atherosclerosis

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