CXCR2 and necrotizing enterocolitis: Considering that 3–7 day-old neonatal rats may simulate the highest risk period of preterm brain injury (23–26 weeks of gestation) [4, 21], and the preference for white matter injury may decline rapidly after birth [22], we selected 3 day-old SD neonatal rats to construct HIBI and NEC + HIBI rat models and to observe behavioral and pathological changes and CXCL1 and CXCR2 expression changes in intestinal and brain tissues.