Abstract:OBJECTIVE: To investigate the effects of bifidobacteria on malondialdehyde (MDA) content and intercellular adhesion molecule-1 (ICAM-1) expression in serum and ileum tissues of young rats with endotoxin-induced intestinal damage, and possible protective mechanisms of bifidobacteria on intestines. METHODS: Eigteen-day-old Wistar rats were randomly administered with normal saline (NS), lipopolysaccharide (LPS, 5 mg/kg) or LPS + bifidobacteria. Bifidobacteria (0.5 mL, twice a day) was intragastrically administrated 7 days prior to LPS injection until the end of the experiment. MDA contents in serum and ileum were detected by the TBA method. Expression of ICAM-1 protein and mRNA were evaluated by immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR) after 2, 6, 24 and 72 hrs of LPS injection. RESULTS: The serum and ileum MDA contents in the untreated LPS group increased significantly and reached a peak at 6 hrs of LPS injection when compared with the NS control group (ileum: 99.88±12.62 nmol/mg prot vs 84.25±12.96 nmol/mg prot, P<0.05; serum: 1.67±0.30 nmol/mL vs 1.13±0.20 nmol/mL, P<0.05). The MDA contents in ileum (92.75±9.28 nmol/mg prot) and serum (1.17±0.23 nmol/mL) in the bifidobacteria-treated group at 6 hrs of LPS injection were significantly lower than in the LPS group (P <0.05）.The expression of ICAM-1 protein in the untreated LPS group remarkably increased at 6, 12, 24 and 72 hrs of LPS injection when compared with the NS control group (P<0.01). The bifidobacteria-treated group displayed lower ICAM-1 protein levels than the untreated LPS group at 72 hrs of LPS injection (P<0.01). The ICAM-1 mRNA expression in the untreated LPS group significantly increased at 2hrs of LPS injection when compared with the NS control group (P<0.01). The ICAM-1 mRNA expression in the bifidobacteria-treated group began to decrease at 2 hrs of LPS injection and was reduced again at 24 hrs after experiencing increase at 6 and 12 hrs of LPS injection when compared with the untreated LPS group (P<0.01). CONCLUSIONS: The serum and ileum MDA contents and the expression of ICAM-1 protein and mRNA increased in young rats with endotoxin-induced intestinal damage. Bifidobacteria supplementation can decrease MDA contents and inhibit ICAM-1 expressions, thus providing protections for intestines.［Chin J Contemp Pediatr, 2007, 9 (4):375-378］
