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- Title
CELL BIOLOGY SYMPOSIUM: Practical application of the basic aspects of GLU T4 membrane trafficking and insulin signaling on issues related to animal agriculture.
- Authors
Smith, S. B.
- Abstract
Because of the relatively short lifespans of beef cattle, membrane trafficking in relation to inflammation is not considered important unless it overtly affects productivity. However, glucose uptake and utilization is important for adipose tissue development in beef cattle, and increasing glucose utilization in intramuscular adipose tissue can increase carcass quality. Research from the 1980s demonstrated a lack of insulin sensitivity in isolated bovine adipocytes and adipose tissue explants incubated in vitro. Insulin did not stimulate glucose or acetate incorporation into fatty acids, nor did it increase concentrations of glycolytic intermediates in bovine adipose tissue incubated with exogenous glucose. Specific binding of [I125] iodoinsulin and insulin degradation in bovine isolated adipocytes was low to non-detectable. These early studies indicated that insulin-dependent receptor-mediated signaling was less important in bovine adipose tissue than in adipose tissues of humans, swine, or laboratory species. More recent research demonstrated that glucose transporter protein 4 (GLUT4) expression in muscle and adipose tissue declines markedly after birth in calves, indicating the development of insulin resistance as cattle transition from suckling to functional ruminants. Insulin resistance is important in dairy cattle, causing ketosis and fatty liver. Consistent with this, subcutaneous adipose tissue GLUT4 expression decreases 50% following parturition in dairy cattle, although expression of genes associated with insulin responsiveness (IRS1, INSIG2, and ZFP423) is up-regulated by 21 d postpartum. Understanding the underlying mechanisms of insulin resistance in beef and dairy cattle would increase animal health and thereby improve productivity.
- Subjects
GLUCOSE transporter regulation; CYTOLOGICAL techniques; INSULIN regulation; BEEF carcasses; ADIPOSE tissue physiology
- Publication
Journal of Animal Science, 2017, Vol 95, Issue 5, p2185
- ISSN
0021-8812
- Publication type
Article
- DOI
10.2527/jas.2016.0984