Osmolality of enteral formula and severity of experimental necrotizing enterocolitis.
OBJECTIVE
Administration of hyperosmolar formula is regarded as a risk factor for the development of necrotizing enterocolitis (NEC). However, there are limited number of reports about the relationship between formula osmolality and NEC. The aim of this study is to evaluate the effects of formula concentration in an experimental model of NEC.


METHODS
We studied experimental NEC in C57BL/6 mice. NEC was induced by giving hypoxia, gavage administration of lipopolysaccharide and gavage formula feeding from postnatal day 5-9. We used two types of formula: (1) hyperosmolar formula (HF): 15 g Similac + 75 ml Esbilac (849 mOsm/kg); (2) diluted formula (DF): dilute hyperosmolar formula with an equal amount of water (325 mOsm/kg). Controls were fed by the mother. On postnatal day 9, the ileum was harvested and evaluated for severity of mucosal injury (hematoxylin/eosin staining) and inflammation (PCR for IL6 and TNFα mRNA expression).


RESULTS
The incidence of NEC was same in both HF and DF (80%). The intestinal inflammatory response was similar between HF and DF (IL6: p = 0.26, TNFα: p = 0.69).


CONCLUSIONS
This study indicates the osmolality of enteral formula does not affect incidence of experimental NEC. This experimental study provides new insights into the relationship between formula feeding and NEC.
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, 1526-555 University Avenue, Toronto, ON, M5G 1X8, Canada.|Department of Pediatric Surgery, Shizuoka Children's Hospital, 860 Urushiyama, Aoi-ku, Shizuoka, 4208660, Japan.
Hiromu
H
Miyake
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, 1526-555 University Avenue, Toronto, ON, M5G 1X8, Canada.
Yong
Y
Chen
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, 1526-555 University Avenue, Toronto, ON, M5G 1X8, Canada.
Yuhki
Y
Koike
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, 1526-555 University Avenue, Toronto, ON, M5G 1X8, Canada.
Alison
A
Hock
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, 1526-555 University Avenue, Toronto, ON, M5G 1X8, Canada.
Bo
B
Li
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, 1526-555 University Avenue, Toronto, ON, M5G 1X8, Canada.
Carol
C
Lee
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, 1526-555 University Avenue, Toronto, ON, M5G 1X8, Canada.
Augusto
A
Zani
Division of General and Thoracic Surgery, Programme of Physiology and Experimental Medicine, The Hospital for Sick Children, University of Toronto, 1526-555 University Avenue, Toronto, ON, M5G 1X8, Canada. agostino.pierro@sickkids.ca.
Agostino
A
Pierro
D000818:Animals; D000831:Animals, Newborn; D004195:Disease Models, Animal; D004750:Enteral Nutrition / Q000009:adverse effects; D020345:Enterocolitis, Necrotizing / Q000139:chemically induced*; D007082:Ileum / Q000187:drug effects; D041943:Infant Formula / Q000009:adverse effects* / Q000737:chemistry; D007249:Inflammation / Q000209:etiology; D007413:Intestinal Mucosa / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D009994:Osmolar Concentration; D012720:Severity of Illness Index
Formula; Inflammation; Mucosal injury; Necrotizing enterocolitis (NEC); Osmolality; Osmolarity