|Haydon, Keith - PRINCE AGRI PRODS, INC|
Submitted to: American Society of Animal Science Southern Section Meeting
Publication Type: Abstract Only
Publication Acceptance Date: November 13, 2007
Publication Date: July 15, 2008
Citation: Hulbert, L.E., Carroll, J.A., Haydon, K. 2008. Endotoxin induced uncoupling of the somatotrophic axis in nursery pigs [abstract]. Journal of Animal Science. 86(Suppl. 2):7. (Abstract #26) Technical Abstract: Lipopolysaccharide (LPS) is an endotoxin known to stimulate the innate immune response and stress axis in pigs. However, little is known about the effects of LPS on pig somatotrophic responses. The objective of this study was to determine the effects of an endotoxin challenge on weaned pig serum concentrations of growth factors. Crossbred pigs (n = 32, 6.7 ± 0.2 Kg) were selected at weaning (20.5 ± 0.3 d of age), transported to a climate controlled facility, penned individually and provided with ad libitum feed and water. After a 12 d acclimatization period, pigs were non-surgically fitted with jugular catheters. On d 13, pigs were infused i.v. with LPS (25 ug/Kg BW). Blood samples were collected every 30 min from -2 to 4 h following LPS challenge. Serum was analyzed for growth hormone (GH), insulin-like growth factor (IGF) -1 and IGF-2. Concentrations of GH decreased (P < 0.001) 0.5 to 2 h post-LPS challenge when compared to baseline concentrations (0.5 to 2 h: 5.22 ± 0.41, -2 to -1h: 9.81 ± 0.86 ng/mL). Serum GH concentrations sharply increased (P < 0.001) at 2.5 h (20.95 ± 3.19 ng/mL), then returned to similar concentrations as the 0.5 to 2 h post-LPS period (P = 0.281), but remained below baseline (P< 0.001). Serum IGF-1 concentrations decreased gradually from the first sample (-2 h) then increased (P < 0.01) rapidly at 0.5 h post LPS (0.5 h: 84.9 ± 4.88, -0.5h: 72.44 ± 5.11 ng/mL). Concentrations of IGF-1 remained below (P<0.01) baseline from times 1.5 to 3 h post-LPS (50.89 ± 2.84 ng/mL), then began to return to baseline concentrations 4 h post-LPS (68.66 ± 5.36 ng/mL). Endotoxin challenge did not affect IGF-2 concentrations although time fluctuations were observed throughout the time periods. The uncoupling of the GH/IGF-1 axis implies that IGF-1 is important for stimulation of an innate immune response in pigs. While GH is important for immunity, subsequent increase in GH may be associated with the liberation of energy to fend off invading pathogens.