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

Background: Animals treated with tumor necrosis factor a (TNF-alpha) develo ped severe metabolic abnormalities despite receiving sufficient protein and energy by total parenteral nutrition (TPN). Objective: We sought to investigate the nutritional and metabolic effects o f bacterial lipopolysaccharide (LPS) in rats. Design: Rats were randomly allocated to 5 groups: oral nutrition (ON contro l; n = 7), TPN control (n = 7), ON+LPS (n = 6), TPN+LPS (n = 9), and pair f ed (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 ca rcass weights were significantly lower in the TPN+LPS and ON+LPS groups tha n in their respective control groups. Diaphragm and extensor digitorum long us weights were significantly lower in the ON+LPS and PF rats, but not in t he TPN+LPS rats, compared with their respective controls. Biochemical abnor malities and plasma corticosterone concentrations were,greater in the TPN+L PS group than in the other groups. Conclusions: These data suggest that provision of sufficient protein and en ergy by TPN does nor 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 abnor malities induced by LPS. More rapid clearance of TNF-alpha and low corticos terone concentrations in weight-losing animals may help reduce the severity of the metabolic effects of LPS.