Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: July 28, 2000
Publication Date: N/A
Technical Abstract: Depressed appetite is a well-recognized consequence of infectious disease. The primary objective of this study was to evaluate the effects of LPS injection on expression of the hypothalamic appetite-regulating genes: orexin, neuropeptide-Y (NPY), agouti-related protein, pro-opiomelanocortin, melanin-concentrating hormone, leptin receptor, and type 2 orexin receptor. .Interleukin-1beta (IL-1beta) mRNA levels were also determined to confirm a hypothalamic response to LPS. A secondary objective was to examine effects of indomethacin pretreatment, since we have previously reported that indomethacin treatment prevents sickness responses to LPS injection in piglets (J. Anim. Sci. 77(Suppl 1): 35, 1999). Ten mg IND/kg or vehicle (0.1 M Na2C03) was administered i.p. 1 h prior to i.p. injection of 150 ug LPS (0111:B4, Sigma Chem. Co.) or sterile saline. Forty-one piglets were utilized (LPS, n=11; IND, n=9; IND + LPS, n=11; Control, n=10). One h following IND the animals were quickly moved to a pen contained in an 18 deg C environmental chamber and injected with LPS or saline (time 0). Animals were sacrificed for tissue collection 3 h after LPS challenge. Total RNA was extracted from hypothalamic tissues and subjected to slot blot analyses for specific mRNAs. Values were expressed relative to 28S rRNA. LPS injection significantly increased IL-1beta mRNA (107+/4.1 vs 92.9+/4.7, P=.03), but concurrently depressed orexin mRNA levels (90+/4.5 vs 111+/7.1, P=.019). Levels of NPY mRNA tended to be lowered following LPS exposure (P=.07). Indomethacin pretreatment did not influence LPS-induced changes in hypothalamic IL-1beta and orexin mRNA levels. The reduction of orexin mRNA levels subsequent to LPS injection is consistent with an expected decrease in appetite during infectious disease.