sildenafil-citrate and Enterocolitis--Necrotizing

Necrotizing enterocolitis (NEC) has a 45% mortality in neonatal intensive care units. This paper aimed to evaluate the isolated and combined effects of sildenafil and L-arginine in the prevention of necrotizing enterocolitis. Neonatal rats were fed formula milk and submitted to hypoxia under a 100% N2 atmosphere for 70 s. Then, animals were subjected to hypothermia (4 °C for 10 min), twice a day for 3 days. Forty neonatal rats were divided into five groups: negative control-not submitted to the protocol (n = 5), sildenafil group-NEC protocol (n = 9), L-arginine group-NEC protocol (n = 9), L-arginine and sildenafil group-NEC protocol (n = 9) and positive control-NEC protocol and intraperitoneal saline solution (n = 8). Jejunum and terminal ileus were removed for histopathologic and immunohistochemical Ki-67 analysis. Kruskal-Wallis test was used to analyze mortality, survival, body weight, intestinal injury score and Ki-67 proliferation index. All animals submitted to the protocol developed enterocolitis. Mortality rate was higher in group that received only L-arginine (p = 0.0293). The Ki-67 analysis showed a higher proliferative index in groups that received interventional drugs (p = 0.017). In conclusion, sildenafil and L-arginine were not effective to reduce intestinal injury.

Topics: Animals; Animals, Newborn; Arginine; Disease Models, Animal; Enterocolitis, Necrotizing; Humans; Infant, Newborn; Infant, Newborn, Diseases; Ki-67 Antigen; Rats; Sildenafil Citrate

Necrotizing enterocolitis (NEC) is a devastating disease that impacts the intestine of premature infants. Sildenafil has shown benefit in colitis and ischemia/reperfusion models but has not been adequately studied in NEC. Sildenafil's best studied mechanism involves augmenting nitric oxide induced vasodilation. We hypothesized that sildenafil would improve outcomes during experimental NEC in an eNOS dependent manner.. NEC was induced in five-day old mouse pups with gavage formula feeds plus intermittent hypoxia and hypothermia. Using wild type (WT) mice, the route of sildenafil administration was studied in the following groups: (1) breastfed controls, (2) NEC + oral (PO) sildenafil, (3) NEC + PO vehicle, (4) NEC + intraperitoneal (IP) sildenafil, (5) NEC + IP vehicle. The eNOS KO groups studied included: (1) breastfed controls, (2) NEC + PO sildenafil, (3) NEC + PO vehicle. Data were tested for normality and compared using t-tests or Mann-Whitney with a p-value <0.05 considered significant.. In WT mice, oral and IP sildenafil resulted in improved clinical outcomes compared to their respective vehicle group. Only orally administered sildenafil significantly improved perfusion to the intestine and protected it from macroscopic and histologic injury. When repeated in eNOS KO mice, oral sildenafil improved clinical scores and attenuated intestinal injury scores, despite no effect on intestinal perfusion.. Sildenafil, when administered orally, improves clinical outcomes and protects the intestine in a murine model of experimental necrotizing enterocolitis. While sildenafil requires eNOS to impact mesenteric perfusion, it does not appear to be dependent on eNOS to attenuate intestinal injury.

Topics: Animals; Animals, Newborn; Disease Models, Animal; Enterocolitis, Necrotizing; Intestinal Mucosa; Intestines; Mice; Nitric Oxide; Nitric Oxide Synthase Type III; Sildenafil Citrate

Necrotizing enterocolitis (NEC) is a devastating disease of premature infants characterized by severe intestinal necrosis and for which breast milk represents the most effective protective strategy. Previous studies have revealed a critical role for the lipopolysaccharide receptor toll-like receptor 4 (TLR4) in NEC development through its induction of mucosal injury, yet the reasons for which intestinal ischemia in NEC occurs in the first place remain unknown. We hypothesize that TLR4 signaling within the endothelium plays an essential role in NEC development by regulating perfusion to the small intestine via the vasodilatory molecule endothelial nitric oxide synthase (eNOS). Using a unique mouse system in which we selectively deleted TLR4 from the endothelium, we now show that endothelial TLR4 activation is required for NEC development and that endothelial TLR4 activation impairs intestinal perfusion without effects on other organs and reduces eNOS expression via activation of myeloid differentiation primary response gene 88. NEC severity was significantly increased in eNOS(-/-) mice and decreased upon administration of the phosphodiesterase inhibitor sildenafil, which augments eNOS function. Strikingly, compared with formula, human and mouse breast milk were enriched in sodium nitrate--a precursor for enteral generation of nitrite and nitric oxide--and repletion of formula with sodium nitrate/nitrite restored intestinal perfusion, reversed the deleterious effects of endothelial TLR4 signaling, and reduced NEC severity. These data identify that endothelial TLR4 critically regulates intestinal perfusion leading to NEC and reveal that the protective properties of breast milk involve enhanced intestinal microcirculatory integrity via augmentation of nitrate-nitrite-NO signaling.

Topics: Analysis of Variance; Animals; Animals, Newborn; Enterocolitis, Necrotizing; Infant Formula; Intestinal Mucosa; Mice; Mice, Knockout; Microcirculation; Microscopy, Confocal; Milk, Human; Nitrates; Nitric Oxide; Nitric Oxide Synthase Type III; Nitrites; Piperazines; Purines; Signal Transduction; Sildenafil Citrate; Sulfones; Toll-Like Receptor 4