Photoprotection But Not N-Acetylcysteine Improves Intestinal Blood Flow and Oxidation Status in Parenterally Fed Piglets.

OBJECTIVES The purpose of the current study was to determine if protecting parenteral nutrition solutions from ambient light and supplementing with N-acetylcysteine (NAC) improves mesenteric blood flow, gut morphology, and oxidative status of parenterally fed neonates. METHODS Neonatal Yucatan miniature piglets (n = 23, 7-11 d old) were surgically fitted with central venous catheters and an ultrasonic blood flow probe around the superior mesenteric artery. Piglets were fed continuously for 7 d either light-protected (LP) or light-exposed (LE) complete parenteral nutrition that was enriched with either NAC or alanine (ALA). RESULTS There were no differences in body weight or overall gut morphology among groups after 7 d. Plasma concentrations of NAC were greater and total homocysteine lower in NAC- vs ALA-supplemented pigs on day 7 (N-acetylcysteine: 94 vs. 7 μM; P < 0.001; homocysteine: 14 vs. 21 μM; P < 0.005); plasma total glutathione was not affected. Hepatic lipid peroxidation was reduced by 25% in piglets that received LP parenteral nutrition (P < 0.05). The mesenteric artery blood flow decreased in all pigs between days 2 and 6 (P < 0.001) due to parenteral feeding. Photoprotection alone (LP-ALA) attenuated the decrease in mesenteric blood flow to 66% of baseline on day 6 compared to LE-ALA (37%; P < 0.05) and LP-NAC pigs (43%; P = 0.062); LE-NAC piglets had intermediate reductions in blood flow (55%). CONCLUSIONS Photoprotection of parenteral nutrition solutions is a simple, effective method to attenuate decline in blood flow to the gut and hepatic lipid peroxidation which are both commonly associated with parenteral feeding.