Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8501785 | Journal of Dairy Science | 2018 | 15 Pages |
Abstract
Glucose uptake in tissues is mediated by insulin receptor (INSR) and glucose transporter 4 (GLUT4). The aim of this study was to examine the effect of body condition during the dry period on adipose tissue mRNA and protein expression of INSR and GLUT4, and on the dynamics of glucose and insulin following the i.v. glucose tolerance test in Holstein cows 21 d before (d â21) and after (d 21) calving. Cows were grouped as body condition score (BCS) â¤3.0 (thin, T; n = 14), BCS = 3.25 to 3.5 (optimal, O; n = 14), and BCS â¥3.75 (overconditioned, OC; n = 14). Blood was analyzed for glucose, insulin, fatty acids, and β-hydroxybutyrate concentrations. Adipose tissue was analyzed for INSR and GLUT4 mRNA and protein concentrations. During the glucose tolerance test 0.15 g/kg of body weight glucose was infused; blood was collected at â5, 5, 10, 20, 30, 40, 50, and 60 min, and analyzed for glucose and insulin. On d â21 the area under the curve (AUC) of glucose was smallest in group T (1,512 ± 33.9 mg/dL à min) and largest in group OC (1,783 ± 33.9 mg/dL à min), and different between all groups. Basal insulin on d â21 was lowest in group T (13.9 ± 2.32 µU/mL), which was different from group OC (24.9 ± 2.32 µU/mL. On d â21 the smallest AUC 5-60 of insulin in group T (5,308 ± 1,214 µU/mL à min) differed from the largest AUC in group OC (10,867 ± 1,215 µU/mL à min). Time to reach basal concentration of insulin in group OC (113 ± 14.1 min) was longer compared with group T (45 ± 14.1). The INSR mRNA abundance on d 21 was higher compared with d â21 in groups T (d â21: 3.3 ± 0.44; d 21: 5.9 ± 0.44) and O (d â21: 3.7 ± 0.45; d 21: 4.7 ± 0.45). The extent of INSR protein expression on d â21 was highest in group T (7.3 ± 0.74 ng/mL), differing from group O (4.6 ± 0.73 ng/mL), which had the lowest expression. The amount of GLUT4 protein on d â21 was lowest in group OC (1.2 ± 0.14 ng/mL), different from group O (1.8 ± 0.14 ng/mL), which had the highest amount, and from group T (1.5 ± 0.14 ng/mL). From d â21 to 21, a decrease occurred in the GLUT4 protein levels in both groups T (d â21: 1.5 ± 0.14 ng/mL; d 21: 0.8 ± 0.14 ng/mL) and O (d â21: 1.8 ± 0.14 ng/mL; d 21: 0.8 ± 0.14 ng/mL). These results demonstrate that in obese cows adipose tissue insulin resistance develops prepartum and is related to reduced GLUT4 protein synthesis. Regarding glucose metabolism, body condition did not affect adipose tissue insulin resistance postpartum.
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Authors
H. Jaakson, P. Karis, K. Ling, A. Ilves-Luht, J. Samarütel, M. Henno, I. Jõudu, A. Waldmann, E. Reimann, P. Pärn, R.M. Bruckmaier, J.J. Gross, T. Kaart, M. Kass, M. Ots,