אסיף מאגר המחקר החקלאי

Periparturient dairy cows do not exhibit hepatic insulin resistance, yet adipose-specific insulin resistance occurs in cows prone to high weight loss

Year:

2013

Source of publication :

Authors :

Volume :

96

Co-Authors:

Zachut, M., Department of Ruminant Science, Institute of Animal Sciences, Volcani Center, PO Box 6, Bet-Dagan, 50250, Israel, Department of Animal Science, The Robert H. Smith Faculty of Agriculture, Food and Environmental Quality Sciences, the Hebrew University of Jerusalem, Rehovot, 76100, Israel
Honig, H., Department of Ruminant Science, Institute of Animal Sciences, Volcani Center, PO Box 6, Bet-Dagan, 50250, Israel
Striem, S., Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, 76100, Israel
Zick, Y., Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, 76100, Israel
Boura-Halfon, S., Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, 76100, Israel
Moallem, U., Department of Ruminant Science, Institute of Animal Sciences, Volcani Center, PO Box 6, Bet-Dagan, 50250, Israel

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Abstract:

The periparturient period in dairy cows is associated with alterations in insulin action in peripheral tissues; however, the molecular mechanism underlying this process is not completely understood. The objective was to examine the response to a glucose tolerance test (GTT) and to analyze insulin signaling in liver and adipose tissues in pre- and postpartum dairy cows. Liver and adipose tissue biopsies were taken before and after GTT, at 17. d prepartum and again at 3 to 5. d postpartum from 8 high-yielding Israeli Holstein dairy cows. Glucose clearance rate after GTT was similar pre- and postpartum. Basal insulin concentrations and the insulin response to GTT were approximately 4-fold higher prepartum than postpartum. In accordance, phosphorylation of the hepatic insulin receptor after GTT was higher prepartum than postpartum. Across periods, a positive correlation was observed between the basal and peak plasma insulin and phosphorylated insulin receptor after GTT in the liver. Hepatic phosphorylation of protein kinase B after GTT was elevated pre- and postpartum. Conversely, in adipose tissue, phosphorylation of protein kinase B after GTT pre- and postpartum was increased only in 4 out of 8 cows that lost less body weight postpartum. Our results demonstrate that hepatic insulin signaling is regulated by plasma insulin concentrations as part of the homeorhetic adjustments toward calving, and do not support a model of hepatic insulin resistance in periparturient cows. Nevertheless, we suggest that specific insulin resistance in adipose tissue occurs pre- and postpartum only in cows prone to high weight loss. The different responses among these cows imply that genetic background may affect insulin responsiveness in adipose tissue pre- and postpartum. © 2013 American Dairy Science Association.

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