Biomaterial Database

Chronic exogenous hyperinsulinaemia does not modify the acute inhibitory effect of insulin on the secretion of very-low-density lipoprotein triacylglycerol and apolipoprotein B in primary cultures of rat hepatocytes. 1996

C S Bourgeois, and D Wiggins, and G F Gibbons

Oxford Lipid Metabolism Group, Metabolic Research Laboratory, University of Oxford, U.K.

Male Wistar rats were fitted with subcutaneous osmotic mini-pumps that delivered insulin at a constant rate of 0.20 i.u./h for 7 days. This treatment raised the plasma insulin concentration from 31 +/- 4 to 201 +/- 64 micro-i.u./ml. Hepatocytes prepared from the hyperinsulinaemic animals secreted very-low-density lipoprotein (VLDL) triacylglycerol (TAG) at a higher rate (172 +/- 21 microgram per 24 h per mg cell protein) than did those from sham-operated controls (109 +/- 12 microgram per 24 h per mg) (P<0.05). However, chronic exogenous hyperinsulinaemia had no stimulatory effect on the secretion of VLDL apolipoprotein B (apoB) in derived hepatocytes compared with those from the sham-operated controls (2.32 +/- 0.38 compared with 3.09 +/- 0.40 microgram per 24 h per mg). Hepatocytes from the hyperinsulinaemic rats thus secreted larger VLDL particles as evidenced by the increased TAG:apoB ratio (78.4 +/- 13.1 compared with 38.4 +/- 7.6; P<0.05). In hepatocytes from the hyperinsulinaemic rats a larger proportion of the newly synthesized TAG was secreted as VLDL. Hepatocytes from the hyperinsulinaemic and the sham-operated control animals were equally sensitive to the inhibitory effect of insulin added in vitro on the secretion of VLDL TAG. Insulin added in vitro to the culture medium of hepatocytes from hyperinsulinaemic animals significantly decreased the TAG:apoB ratio of the secreted VLDL. This change did not occur in hepatocytes from sham-operated rats. These results suggest that, in vivo, chronic hyperinsulinaemia is not in itself sufficient to desensitize the liver to the acute inhibitory effect of insulin on the secretion of VLDL.

UI	MeSH Term	Description	Entries
D007328	Insulin	A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1).	Iletin,Insulin A Chain,Insulin B Chain,Insulin, Regular,Novolin,Sodium Insulin,Soluble Insulin,Chain, Insulin B,Insulin, Sodium,Insulin, Soluble,Regular Insulin
D008079	Lipoproteins, VLDL	A class of lipoproteins of very light (0.93-1.006 g/ml) large size (30-80 nm) particles with a core composed mainly of TRIGLYCERIDES and a surface monolayer of PHOSPHOLIPIDS and CHOLESTEROL into which are imbedded the apolipoproteins B, E, and C. VLDL facilitates the transport of endogenously made triglycerides to extrahepatic tissues. As triglycerides and Apo C are removed, VLDL is converted to INTERMEDIATE-DENSITY LIPOPROTEINS, then to LOW-DENSITY LIPOPROTEINS from which cholesterol is delivered to the extrahepatic tissues.	Pre-beta-Lipoprotein,Prebeta-Lipoprotein,Prebeta-Lipoproteins,Very Low Density Lipoprotein,Very-Low-Density Lipoprotein,Very-Low-Density Lipoproteins,Lipoprotein VLDL II,Lipoproteins, VLDL I,Lipoproteins, VLDL III,Lipoproteins, VLDL1,Lipoproteins, VLDL2,Lipoproteins, VLDL3,Pre-beta-Lipoproteins,Lipoprotein, Very-Low-Density,Lipoproteins, Very-Low-Density,Pre beta Lipoprotein,Pre beta Lipoproteins,Prebeta Lipoprotein,Prebeta Lipoproteins,VLDL Lipoproteins,VLDL1 Lipoproteins,VLDL2 Lipoproteins,VLDL3 Lipoproteins,Very Low Density Lipoproteins
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D008297	Male		Males
D009829	Oleic Acids	A group of fatty acids that contain 18 carbon atoms and a double bond at the omega 9 carbon.	Octadecenoic Acids,Acids, Octadecenoic,Acids, Oleic
D009929	Organ Size	The measurement of an organ in volume, mass, or heaviness.	Organ Volume,Organ Weight,Size, Organ,Weight, Organ
D001786	Blood Glucose	Glucose in blood.	Blood Sugar,Glucose, Blood,Sugar, Blood
D001835	Body Weight	The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.	Body Weights,Weight, Body,Weights, Body
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia