Physiological response to acute endotoxemia in swine: effect of genotype on energy metabolites and leptin

Certain high lean gain swine genotypes have greater sensitivity to pathogen and nonpathogen stressors evident by reduced productivity and increased mo rtality during disease stress or in suboptimal production environments. Sal ine (control) and an immunologic challenge (LPS; 25 mu g lipopolysaccharide /kg BW) were administered to three genetic populations teach pig used as it s own control): high lean (H), moderate lean terminal cross (MT), and moder ate lean maternal cross (MM). LPS induced anorexia, and significantly incre ased body temperature and circulating TNF-cu, cortisol, and NEFA in all gen otypes (P < 0.0004). LPS reduced circulating glucose, insulin, and IGF-1 in all genotypes (P < 0.05). The LPS-induced hypoglycemia was significantly g reater in MM versus MT and H pigs (P < 0.03). The hypoinsulinemia was signi ficantly greater in MM versus H pigs (P < 0.02). MM pigs recovered from hyp oinsulinemia slower than MT pigs (P ( 0.03). Control insulin was higher in H versus MT pigs (P < 0.08), but relative to basal, the insulin response to LPS was similar. Plasma haptoglobin response to LPS was lower for MM versu s MT and H pigs (P < 0.02), and tended to be lower in MT versus H pigs (P < 0.09). LPS treatment caused similar decreases in plasma IGF-1 concentratio ns among genotypes. Ten hours after LPS treatment, leptin mRNA abundance in adipose tissue was significantly reduced (relative to control) in MM and H pigs (P < 0.02) but not in MT pigs (P > 0.05). Physiological differences i n leptin, a potent regulator of food intake and energy metabolism, may be i mportant factors in the genetic variation in sensitivity to environmental s tress. (C) 2000 Elsevier Science inc. All rights reserved.