Formula feeding and systemic hypoxia synergistically induce intestinal hypoxia in experimental necrotizing enterocolitis.
OBJECTIVE
Feeding and systemic hypoxia are major stresses inducing necrotizing enterocolitis (NEC). This study aims to investigate the role of systemic hypoxia in NEC and its effect before and after feeding.


METHODS
Neonatal mice were studied in three groups. Control (N = 9): breast feeding; NEC A (N = 8), gavage feeding + lipopolysaccharide (LPS) + preprandial hypoxia; and NEC B (N = 9), feeding + LPS + postprandial hypoxia. Pimonidazole, a hypoxia marker, was injected intraperitoneally before ileum was harvested for histology and quantitative RT-PCR studies. Statistical analysis was done using the ANOVA and Chi-square test.


RESULTS
NEC incidence was 62.5% in NEC A and 88.9% in NEC B. The mortality in NEC B (55.6%) but not A (25%) is significantly higher than control (0%, p < 0.05). Pimonidazole staining elevated in both NEC A and B with higher pimonidazole grade in NEC B (p < 0.01). Both NEC groups had increased the expression of hypoxia-related genes: HIF-1α, GLUT-1, and PHD-3 with GLUT-1 expressed more in NEC B compared with NEC A (p < 0.01). The inflammation marker, IL6, was similarly raised in both NEC A and B.


CONCLUSIONS
Feeding and postprandial hypoxia synergistically induce intestinal hypoxia in NEC. As feeding increases intestinal oxygen demand, maintaining a balance between intestinal oxygen supply and demand is important to prevent NEC.
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, Toronto, ON, M5G 1X8, Canada.|Department of Pediatric Surgery, KK Women's and Children's Hospital, Singapore, Singapore.
Y
Y
Chen
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, Toronto, ON, M5G 1X8, Canada.
Y
Y
Koike
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, Toronto, ON, M5G 1X8, Canada.
H
H
Miyake
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, Toronto, ON, M5G 1X8, Canada.
B
B
Li
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, Toronto, ON, M5G 1X8, Canada.
C
C
Lee
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, Toronto, ON, M5G 1X8, Canada.
A
A
Hock
Division of General and Thoracic Surgery, Programme of Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Canada.
A
A
Zani
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, Toronto, ON, M5G 1X8, Canada. agostino.pierro@sickkids.ca.
A
A
Pierro
D000818:Animals; D000831:Animals, Newborn; D000833:Animals, Suckling; D004195:Disease Models, Animal; D004750:Enteral Nutrition; D020345:Enterocolitis, Necrotizing / Q000473:pathology*; D000860:Hypoxia / Q000473:pathology*; D007082:Ileum / Q000473:pathology; D007422:Intestines / Q000473:pathology*; D008070:Lipopolysaccharides / Q000008:administration & dosage; D051379:Mice; D008810:Mice, Inbred C57BL; D041941:Milk Substitutes / Q000008:administration & dosage*; D016133:Polymerase Chain Reaction
D008070:Lipopolysaccharides
Feeding; Hypoxia; Ischemia; Necrotizing enterocolitis