Leptin expression in porcine adipose tissue is not increased by endotoxin but is reduced by growth hormone

The physiologic response to infection includes reductions in tissue concentrations of anabolic growth factors as a means of reducing growth and conserving nutrients for immunologic processes. This repartitioning of nutrients is accompanied by anorexia, which has been linked to increased leptin expression. Furthermore, leptin and growth hormone (GH) concentrations are inversely related, with leptin being required for normal GH release. The objective of this study was to determine if pretreatment with GH would influence endotoxin-induced changes in leptin expression or attenuate endotoxin-induced reductions in serum insulin-like growth factor-1 (IGF-1) and IGF-1 expression in liver and longissimus muscle. In experiment 1, 40 pigs were assigned to four treatments (n = 10 per treatment) arranged as a 2x2 factorial with GH (s.c. injection, 2 mg 1 h before challenge and 2 mg 2 h after challenge) and endotoxin (single i.m. injection, 25 microg/kg body weight) as main effect variables. Pretreatment with GH resulted in a marked increase (p