Expression of inducible nitric oxide synthase and cyclooxygenase-2 mRNA in brain damage induced by lipopolysaccharide and intermittent hypoxia-ischemia in neonatal rats

AIM: The purpose of the present study was to examine the effect of lipopolysaccharide (LPS) and intermittent hypoxia-ischemia (HI) on brain damage in neonatal rats. METHODS: Seven-day-old Wistar rats were injected with saline or LPS (1 mg/kg), and then underwent left common carotid artery ligation followed by a repetitive 8% hypoxia (2.0-4.5 min) at 10-min intervals 10 times. The rats were divided into three groups: LPS with HI (LPS/HI, n = 46), saline with HI (HI alone, n = 42) and LPS alone (n = 16). Seven days later, brains were assessed for neuronal damage and inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) mRNA expression. RESULTS: Neuronal damage in the ligated side was significantly higher in LPS/HI than the other two groups (P < 0.01). The expression of iNOS and COX-2 mRNA was observed in the affected brain in LPS/HI, which corresponded well to histologic neuronal loss. CONCLUSIONS: LPS enhanced intermittent HI brain damage in immature animals. The expression of iNOS and COX-2 mRNA is considered to be associated with perinatal brain injury processes.