In vivo oxidative stress in a mice model of delayed intestinal bacterial colonization lacking surfactant protein A

Excessive formation of reactive oxygen species may be associated with the onset and progression of necrotizing enterocolitis (NEC) a disease characterized by delayed intestinal bacterial colonization. Surfactant associated protein‐A (SP‐A) is found in lung and intestinal tissue and its role in prevention of respiratory distress syndrome in lung is due to its antioxidant activity. Knockout SP‐A (−/−) mice have delayed intestinal bacterial colonization resembling the pathophysiology of NEC. We investigated in vivo biomarkers of oxidative stress in the intestine of SP‐A: wild type (+/+) and (−/−) mice at postnatal ages of 7 and 14 days (PD7 and PD14). Homogenates from whole intestines were used to extract DNA, RNA, proteins; to determine the concentrations of: malondialdehyde (MDA), 8‐hydroxy deoxy guanosine (8‐OHdG), uric acid (UA); and the activity or expressions of: SP‐A, superoxide dismutase (SOD), glutathione (GTH), nicotinamide adenine dinucleotide phosphate‐oxidase (NADPH), and inducible nitric‐oxide synthase (iNOS). Paraffin embedded intestines from PD7 and PD14 mice were used for inmunohystochementry detection of iNOS. Inmunoblot analysis of intestinal proteins extracts for SP‐A were positive only at PD7. However, age and/or genotype related changes were significantly different (p<0.05): for MDA, 8‐OHdG, UA; SP‐A, NADPH, SOD, GTH and iNOS. Inmmunohystochemical analysis using proximal colon or cecum of SP‐A (+/+) and SP‐A (−/−) mice, revealed different activity for iNOS at PD7 or PD14 mice for both genotypes. The March of Dimes supported this research, grant #6‐FY07‐57.