NOS2 and necrotizing enterocolitis: In addition, compared with the NEC group, the protein expression levels of TNF-α, iNOS, NF-κB, BAX, and TLR4 were significantly decreased, and the protein expression level of Bcl-2 and NOD2 was significantly increased in NEC + Astaxanthin group (P < 0.05 or P < 0.01).