Background: The maternal-fetal infection/inflammation is believed to be the mechanism in the pathogenesis of periventricular leukomalacia (PVL). The activation of microglias (MGs) may contribute to preoligodendroglial damage. The present study was undertaken to explore the effect of N-[3-(aminomethyl) benzyl] acetamidine (1400W), a selective inhibitor of inducible nitric oxide synthase (iNOS), on the blockage of lipopolysaccharide (LPS)-induced microglial toxicity to preoligodendrocytes (preOLs).
Methods: The co-cultural MGs and preOLs obtained from two-day-old Sprague-Dawley (SD) neonatal rats were divided into three groups: co-culture control group, coculture LPS group, and co-culture LPS plus 1400W group. The concentration of nitric oxide (NO) was measured by nitric acid-deoxidize-colorimetry, the level of peroxynitrite (ONOO(-)) determined by immunocytochemistry, the synthetic level of inducible nitric oxide synthase (iNOS) detected by western blotting, and the apoptotic rate of preOLs assessed by flow cytometry after the co-cultural cells were induced by LPS (100 ng/ml) for 48 hours.
Results: Compared with those in the co-culture control group, the levels of NO (82.27+/-3.41 micromol/L vs. 167.86+/-9.87 micromol/L, P<0.01), ONOO(-) (6.14+/-1.27 vs. 34.38+/-7.75, P<0.01), and iNOS (0.18+/-0.027 vs. 0.79+/-0.068, P<0.01) induced by LPS increased remarkably in the co-culture LPS group, with a higher apoptotic rate of preOLs (6.73+/-1.39% vs. 24.77+/-2.05%, P<0.01). The levels of NO (69.55+/-5.07 micromol/L, P<0.01), ONOO(-) (10.33+/-3.47, P<0.01) and iNOS (0.35+/-0.042, P<0.01) were decreased significantly using 1400W at a dose of 10 micromol/L in the co-culture LPS plus 1400W group, and the apoptotic rate of preOLs (11.80+/-2.06% vs. 24.77+/-2.05%, P<0.01) also decreased compared with the co-culture LPS group.
Conclusion: 1400W can block effectively the LPS-induced microglial toxicity to preOLs by inhibiting iNOS specifically, resulting in a significant reduction of toxicity parameters investigated and a marked increase of the survival preOLs.