Enteral nutrition affects nitric oxide production in peripheral blood and liver after a postoperative lipopolysaccharide-induced endotoxemia in rats.
OBJECTIVE
Sepsis is a common complication in the early postoperative period, leading to the augmentation of oxidative and nitrosative stresses. The present study investigated the role of enteral nutrition on nitric oxide (NO) production after a lipopolysaccharide (LPS)-induced endotoxemia as an index of nitrosative stress.


METHODS
Fifty rats were subjected to midline laparotomy and feeding gastrostomy. Ten rats served as controls after recovering from operative stress. The remaining rats received, through gastrostomy, enteral nutrition or placebo feeding for 24 h, after which they were injected intraperitoneally with LPS or equal volume of saline. Two hours later blood and liver tissue were collected. NO production was quantified in serum samples and homogenates of liver tissue by a modification of Griess's reaction. NO synthase (NOS) mRNA expression was examined in homogenate of liver tissue by reverse transcription-polymerase chain reaction.


RESULTS
The operation significantly increased basal NO production in rat serum. LPS induced a further significant increase of NO levels. Enteral feeding of rats significantly decreased NO levels in both groups. In contrast, enteral nutrition was found to increase significantly NO levels in liver homogenates from rats treated with LPS. A constitutive endothelial NOS mRNA expression was found in liver tissue, whereas LPS administration induced inducible NOS mRNA expression in liver tissue regardless of enteral feeding.


CONCLUSIONS
These findings indicate that early enteral feeding leads to a reduction in circulating NO levels induced by operation and endotoxemia, but increases hepatic NO levels in endotoxemia probably by the effect of LPS-induced inducible NOS on the increased L-arginine uptake.
Kolios
George
G
Department of Gastroenterology, University of Crete, Heraklion, Greece. gkolios@med.uoc.gr
Kotzampassi
Katerina
K
Manousou
Pinelopi
P
Paramythiotis
Daniel
D
Papanastasiou
Helen
H
Drygiannakis
Ioannis
I
Notas
George
G
Tsagarakis
Nikos
N
Eleftheriadis
Efthimios
E
Kouroumalis
Elias
E
D000818:Animals; D019446:Endotoxemia; D004750:Enteral Nutrition; D005774:Gastrostomy; D008070:Lipopolysaccharides / Q000633:toxicity; D008099:Liver / Q000378:metabolism*; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D009573:Nitrites / Q000097:blood*; D018384:Oxidative Stress; D011184:Postoperative Period; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction
D008070:Lipopolysaccharides; D009573:Nitrites; D012333:RNA, Messenger; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III