Nutritional and metabolic effects of the endotoxin bacterial lipopolysaccharide in orally and parenterally fed rats

Abstract

Background: Animals treated with tumor necrosis factor α (TNF-α) developed severe metabolic abnormalities despite receiving sufficient protein and energy by total parenteral nutrition (TPN). Objective: We sought to investigate the nutritional and metabolic effects of bacterial lipopolysaccharide (LPS) in rats. Design: Rats were randomly allocated to 5 groups: oral nutrition (ON control; n = 7), TPN control (n = 7), ON+LPS (n = 6), TPN+LPS (n = 9), and pair fed (PF) in relation to ON+LPS (n = 6). Results: Body weight decreased significantly as diet consumption decreased in the ON+LPS and PF groups compared with the ON control group. Relative carcass weights were significantly lower in the TPN+LPS and ON+LPS groups than in their respective control groups. Diaphragm and extensor digitorum longus weights were significantly lower in the ON+LPS and PF rats, but not in the TPN+LPS rats, compared with their respective controls. Biochemical abnormalities and plasma corticosterone concentrations were greater in the TPN+LPS group than in the other groups. Conclusions: These data suggest that provision of sufficient protein and energy by TPN does not prevent general carcass wasting induced by LPS but may protect individual muscles. However, compared with an oral ad libitum diet, TPN providing sufficient protein and energy worsens the biochemical abnormalities induced by LPS. More rapid clearance of TNF-α and low corticosterone concentrations in weight-losing animals may help reduce the severity of the metabolic effects of LPS.