Central and peripheral concentrations of tumor necrosis factor-α in Chinese Meishan pigs stimulated with lipopolysaccharide1,2

The objective of this study was to investigate the presence of tumor necrosis factor-alpha (TNF-alpha) in the central nervous system and the effects of lipopolysaccharide on central and peripheral concentrations of TNF-alpha, behavioral conditions (standing or lying), elimination scores (defecation or urination), rectal temperature, and food intake (as-fed basis) in Chinese Meishan pigs. Intravenous injections of lipopolysaccharide resulted in increased (P < 0.05) plasma concentrations of TNF-alpha and cortisol. Although urination was not affected by the administration of lipopolysaccharide, defecation was stimulated (P < 0.05). Lipopolysaccharide increased (P < 0.05) rectal temperature and standing rate, and inhibited (P < 0.05) food intake in pigs. To determine whether TNF-alpha is present in the porcine central nervous system as well as in peripheral blood, TNF-alpha and its specific transcripts in brain tissues (hypothalamus, amygdala, or hippocampus) and the pituitary were determined. The abundance of TNF-alpha messenger RNA and immunoreactive TNF-alpha were observed in all tissues, and the concentrations of TNF-alpha were increased (P < 0.05) by the intramuscular injection of lipopolysaccharide. These results suggest that TNF-alpha is present in the central nervous system, and plays some roles in its biological regulation in Chinese Meishan pigs.