Gastrointestinal, hepatic, and metabolic effects of enteral and parenteral nutrition in rats infused with tumor necrosis factor.

BACKGROUND

We previously showed that continuous infusion of tumor necrosis factor-alpha (TNF-alpha) in orally fed rats caused weight and muscle wasting mainly because of anorexia. However, when we tried to prevent weight loss by giving total parenteral nutrition (TPN), TNF-infused rats developed hyperglycemia, azotemia, and hepatic abnormalities. The present study was designed to determine whether the enteral (ENT) feeding resulted in fewer complications than parenteral (TPN) feeding in TNF-infused rats (100 micrograms/kg/d).

METHODS

Forty-two rats were randomly allocated to four groups as follows: controls: TPN and ENT, and TNF-infused: TPN + TNF and ENT + TNF. All groups received the same liquid defined formula diet either enterally or parenterally (isocaloric and isonitrogenous). Twenty-six rats were used for studies of body composition and metabolism and 16 for vascular permeability.

RESULTS

TPN + TNF and ENT + TNF rats showed significantly increased liver weights and significantly reduced carcass weights compared with controls. A significant reduction in the muscle weights and total protein, as well as hyperglycemia, azotemia, and abnormal liver enzymes was also seen in ENT + TNF rats compared with ENT rats. The gastric and small intestinal mucosa was inflamed in the ENT + TNF but not in the ENT, TPN + TNF, and TPN rats. The plasma TNF levels determined by bioassay were significantly increased in the TPN + TNF and ENT + TNF rats compared with controls. There was increased vascular permeability in the stomach and small and large intestine in the ENT + TNF rats compared with ENT rats. No significant changes in vascular permeability were seen in TPN and TPN + TNF rats.

CONCLUSIONS

ENT, but not TPN, resulted in prominent changes in the body composition and marked metabolic effects in the TNF-infused rats.