Leptin expression is reduced with acute endotoxemia in the pig: Correlation with glucose, insulin, and insulin-like growth factor-1 (IGF-1)

Leptin has been implicated in the regulation of anorexia associated with ca chexia in rodents and humans. Regulation of leptin expression is under comp lex endocrine and metabolic control, To determine if leptin expression is r egulated by acute inflammation and to define the endocrine and metabolic fa ctor(s) that regulates leptin expression during acute inflammation, castrat e male pigs (ad libitum fed, used as their own controls) were treated with saline (control period) and endotoxin (lipopolysaccharide [LPS] period). Fr equent blood samples were collected to identify dynamic changes in hormones and metabolites that are known to regulate leptin expression. LPS caused f ever and elevated plasma cortisol (p < 0.0004), tumor necrosis factor-alpha (TNF-alpha) (p < 0.0001), and plasma nonesterified fatty acids (NEFA) (p < 0.001) compared with control. Circulating insulin (p < 0.01), glucose (p < 0.003), and insulin-like growth factor-1 (IGF-1) (p < 0.0001), as well as adipose leptin mRNA abundance (p < 0.01), mere profoundly reduced following LPS treatment compared with control. Our data indicate that during acute e ndotoxemia (1-10 h after injection), leptin gene expression is decreased co mpared with ad libitum fed animals and is more closely related to energy ho meostasis than cytokine profiles in plasma.