Effects of heat stress on carbohydrate and lipid metabolism in growing pigs

• Published in: Physiological reports Vol. 3; no. 2; pp. e12315 - n/a
• Main Authors: Victoria Sanz Fernandez, M., Johnson, Jay S., Abuajamieh, Mohannad, Stoakes, Sara K., Seibert, Jacob T., Cox, Lindsay, Kahl, Stanislaw, Elsasser, Theodore H., Ross, Jason W., Clay Isom, S., Rhoads, Robert P., Baumgard, Lance H.
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.02.2015; BlackWell Publishing Ltd
• Subjects: Adipose tissue; Animal sciences; Body weight; Carbohydrate metabolism; Costs; Diabetes; Epinephrine; Epinephrine challenge; Fatty acids; Glucose tolerance; glucose tolerance test; Heat; Heat stress; Hogs; Hormones; Humidity; Insulin; Intravenous administration; Iodide peroxidase; Laboratories; Lipid metabolism; Liver; Metabolism; Original Research; Oxidative phosphorylation; Phosphorylation; Physiology; Skeletal muscle; Thyroid gland; thyroid hormones; heat stress; metabolism; glucose tolerance test; Epinephrine challenge; thyroid hormones
• ISSN: 2051-817X; 2051-817X
• DOI: 10.14814/phy2.12315

Heat stress (HS) jeopardizes human and animal health and reduces animal agriculture productivity; however, its pathophysiology is not well understood. Study objectives were to evaluate the direct effects of HS on carbohydrate and lipid metabolism. Female pigs (57 ± 5 kg body weight) were subjected to two experimental periods. During period 1, all pigs remained in thermoneutral conditions (TN; 20°C) and were ad libitum fed. During period 2, pigs were exposed to: (1) constant HS conditions (32°C) and fed ad libitum (n = 7), or (2) TN conditions and pair‐fed (PFTN; n = 10) to minimize the confounding effects of dissimilar feed intake. All pigs received an intravenous glucose tolerance test (GTT) and an epinephrine challenge (EC) in period 1, and during the early and late phases of period 2. After 8 days of environmental exposure, all pigs were killed and tissue samples were collected. Despite a similar reduction in feed intake (39%), HS pigs tended to have decreased circulating nonesterified fatty acids (NEFA; 20%) and a blunted NEFA response (71%) to the EC compared to PFTN pigs. During early exposure, HS increased basal circulating C‐peptide (55%) and decreased the insulinogenic index (45%) in response to the GTT. Heat‐stressed pigs had a reduced T3 to T4 ratio (56%) and hepatic 5′‐deiodinase activity (58%). After 8 days, HS decreased or tended to decrease the expression of genes involved in oxidative phosphorylation in liver and skeletal muscle, and ATGL in adipose tissue. In summary, HS markedly alters both lipid and carbohydrate metabolism independently of nutrient intake. e12315 Heat stress markedly alters postabsorptive energetic metabolism. This is primarily characterized by hyperinsulinemia and metabolic fuel inflexibility.