J. A. Shepherd2, P. J. Matheson1,2, L. A. Galganski4, J. W. Smith2, R. N. Garrison1,2, C. D. Downard2 1Robley Rex Veterans Affairs Medical Center,Surgery,Louisville, KY, USA 2University Of Louisville,Hiram C. Polk Jr. M.D. Department Of Surgery,Louisville, KY, USA 4University Of California – Davis,Department Of Surgery,Sacramento, CA, USA
Introduction:
The pathophysiology of NEC impairs ileal blood flow via dysregulation of mediators of vascular tone, but deranged intestinal angiogenesis might also contribute to impaired blood flow. Vascular endothelial growth factor A (VEGFA) may have an important role in neonatal intestinal vascular development and control. We hypothesized that the gene and protein dysregulation that occurs during experimental NEC results in altered VEGFA protein expression.
Methods:
Sprague-Dawley rats were randomized to groups by litter. CONTROLS were delivered vaginally and dam-fed. NEC groups were delivered by C-section 12 hrs prematurely, formula fed, exposed to intermittent cold and hypoxia, and given a single oral dose of lipopolysaccharide. Ileum samples were obtained at 0, 12, 24, 48, 72 and 96 hours of life and Western blots were performed with antibodies against VEGFA and β -actin for normalization by individual animal. Serum levels were analyzed for the 12, 24, 48, 72 and 96-hour time points by Luminex MagPix multianalyte cytokine array. Statistical analysis was performed using 2-way ANOVA and a priori P<0.05.
Results:
Ileal VEGFA protein expression peaked at 12 hours in the CONTROLS. This peak was significantly decreased in the NEC compared to CONTROLS (6.62±0.66 vs. 2.01±0.36 in NEC, *P<0.05). The NEC groups had a peak in VEGFA expression at 96 hours of life, which was increased compared to CONTROLS (1.60±.14 vs. 0.61±0.05, *P<0.05). Serum levels for VEGFA expression peaked at 24 hours in CONTROLS. The NEC group expression was significantly decreased at this time point. The NEC group did experience a peak in serum VEGFA expression at 96 hours of life when compared with the CONTROL group.
Conclusion:
This early peak in VEGFA expression suggests an important role for VEGFA in developmental angiogenesis in the CONTROLS that appears to be diminished in this experimental model of NEC. Further investigation of serum levels for VEGFA displayed the same concentration pattern, only delayed by 12 hours for each time point. These findings corroborate our prior studies that showed decreased expression of plate-derived growth factor (PDGF) and PDGF receptors. The deranged microvascular control of intestinal perfusion that occurs in NEC involves both altered mediators of vascular tone and mediators of vascular growth.
