The route of lipid administration affects parenteral nutrition-induced hepatic steatosis in a mouse model

Background: The etiology of parenteral nutrition (PN)-associated hepatic injury remains unresolved. Recent studies have suggested that the intravenous (IV) lipid emulsion administered with PN may contribute to PN-associated hepatic injury. We therefore examined whether the route of lipid administration would affect the development of PN-associated liver injury in a previously established animal model of PN-induced hepatic steatosis. Methods: Mice were fed ad libitum PN solution as their only nutritional source for 19 days with lipid supplementation by either the enteral or the IV route. Control mice received chow alone, and a final group received enteral PN solution without lipid supplementation. Results: All mice gained equivalent weight during the study. Mice receiving PN alone or PN with IV lipid developed severe histologic liver damage that was not seen in control mice or in mice receiving PN with enteral lipid. Liver fat content as measured by magnetic resonance spectroscopy was significantly lower in the control and enteral lipid groups when compared with mice receiving PN alone or with IV lipid. Mice receiving enteral lipid had significantly lower levels of serum aspartate aminotransferase and alanine aminotransferase compared with animals receiving PN alone. Conclusions: These data provide preliminary evidence that lipid administered through the enteral route protects against PN-associated hepatic injury in an animal model.