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Enteral Relaxin Supplementation Improves Necrotizing Enterocolitis Associated Intestinal Hypoperfusion

Saturday, October 20, 2012: 9:58 AM
Versailles Ballroom (Hilton Riverside)
Alexandra Maki, MD1, Paul J. Matheson, Ph.D.1, Jessica A. Shepherd, BS1, R. Neal Garrison, M.D.1 and Cynthia D. Downard, M.D., M.M.Sc.2, (1)Surgery, University of Louisville, Louisville, KY, (2)Pediatric Surgery, University of Louisville, Louisville, KY

Enteral Relaxin Supplementation Improves Necrotizing Enterocolitis Associated Intestinal Hypoperfusion

Purpose:   Necrotizing enterocolitis (NEC) affects premature infants, and is associated with intestinal hypoperfusion.  Relaxin is a naturally occurring vasodilatory hormone found in maternal milk, but is not present in milk-based formulas.  We have previously found decreased levels of relaxin associated with the development of NEC.  We hypothesized that relaxin supplementation would improve the intestinal hypoperfusion seen in NEC.

Methods:   Sprague-Dawley rat pups were separated into four groups postnatally.  CONTROL animals were vaginally delivered and dam fed.  NEC was induced in the remaining three groups by premature delivery (cesarean), intermittent hypoxia, hypothermia, exposure to LPS and formula feeds.  Relaxin supplementation was given with every formula feed in the ALL experimental group, while relaxin was given with only the final feed in the ONE TIME group. NEC-ALONE animals had NEC induced but did not get relaxin supplementation.  All groups underwent laser Doppler flow study of the terminal ileum to determine real-time blood flow in the intestinal microvasculature at 24 hours of age. Results were compared by ANOVA and Tukey-Kramer HSD, significance set at p<0.05 a priori.

Results: Relaxin supplementation significantly increased ileal blood flow in the ALL (54.4 PU 0.9) and ONE TIME (54.3 PU 1.1) groups as compared to NEC–ALONE (38.5 PU 1.0) and CONTROL groups (37.3 PU 1.4), (p<0.05).

Conclusion:   Based on this data, relaxin supplementation in an NEC animal model increases ileal blood flow by more than forty percent when compared to NEC animals without relaxin and normal dam-fed pups.  This is true of both groups fed relaxin with every feed and those only supplemented with relaxin once.  As relaxin is a naturally produced hormone, it could be provided as an oral supplement in patients at risk for necrotizing enterocolitis.