Intestine and brain TLR-4 modulation following N-Acetyl-Cysteine treatment in NEC rodent model

Abstract

Objective: Necrotizing enterocolitis (NEC) brain injury is mediated through Toll-like receptor 4 (TLR4) on the intestinal epithelium and on brain microglia. We sought to determine whether postnatal and/or prenatal NAC can modify NEC associated intestinal and brain TLR4 expression and brain glutathione levels in a rat model of NEC.Study Design: Newborn Sprague-Dawley rats were randomized into 3 groups: Control (n=33); NEC (n=32) subjected to hypoxia and formula feeding; NEC-NAC (n=34) received NAC (300mg/kg IP) in addition to NEC conditions. Two additional groups included pups of dams who were treated once daily with NAC (300mg/kg IV) for the last 3 days of pregnancy: NAC-NEC (n=33) or NAC-NEC-NAC (n=36) with additional postnatal NAC. Pups were sacrificed on the fifth day, ileum and brains harvested for TLR-4 and glutathione protein levels. Results: NEC offspring had significantly increased brain and ileum TLR-4 protein levels compared to control (brain 2.5+0.6 vs 0.88+0.12 U; ileum 0.24+0.04 vs 0.09+0.01 U, p<0.05). NAC administered only to dams (NAC-NEC) significantly decreased NEC offspring brain (1.53+0.41 vs 2.5+0.6 U; p<0.05) and ileum (0.12+0.03 vs 0.24+0.04 U; p<0.05) TLR-4 protein levels compared to NEC. The same pattern was demonstrated when NAC was administered only or also postnatally. The decrease in offspring brain glutathione levels observed under NEC condition was reversed with all NAC treatment groups.Conclusion: NAC could reverse the increase in ileum and brain TLR-4 levels and the decrease in brain glutathione levels associated with NEC in a rat model, and thus may protect from NEC associated brain injury.