Regulation of adipose tissue metabolism during pregnancy and lactation in the ewe: the role of insulin.
This study was conducted to examine the effect of insulin on lipid metabolism of adipocytes during pregnancy and lactation in ewes. During the first 3 mo of pregnancy, metabolism of adipocytes from omental adipose tissue was characterized by a high rate of de novo lipogenesis (90 to 125 nmol of acetate incorporated into lipids.2 h-1.10(6) cells-1) and a 38% reduction in response to beta-lipolytic stimulus (isoproterenol 10(-6) M). Simultaneously, there was a rise in the number of high-affinity insulin receptors (Kd = .2 nM), and insulin binding characteristics showed a decrease in the negative cooperativity phenomenon. Moreover, lipogenesis stimulated by insulin (1 mU/ml) increased in comparison with observations in nonpregnant ewes. The last third of pregnancy and early lactation were characterized by a marked fall in lipogenesis and a simultaneous increase in isoproterenol-stimulated lipolysis. During lactation, the number of total insulin receptors was decreased by 62% and insulin stimulation of lipogenesis became inefficient. Results suggest that insulin plays a direct role in adipose tissue metabolism during pregnancy.
Guesnet
P M
PM
Lab. de Nutrition et Sécurité Alimentaire, Institut National de la Recherche Agronomique, Jouy-en-Josas, France.
Massoud
M J
MJ
Demarne
Y
Y
D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D005260:Female; D007328:Insulin / Q000502:physiology*; D007774:Lactation / Q000378:metabolism*; D050356:Lipid Metabolism; D008055:Lipids / Q000096:biosynthesis; D008066:Lipolysis; D009852:Omentum; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011972:Receptor, Insulin / Q000032:analysis; D012756:Sheep / Q000378:metabolism*; D012867:Skin
D007328:Insulin; D008055:Lipids; D011972:Receptor, Insulin