Quantitative measurement of nitric oxide and hydrogen peroxide in Helicobacter pylori-infected Mongolian gerbils in vivo

Objective. Peroxynitrite formation, as reflected by nitrotyrosine expression, is low in Helicobacter pylori-infected Mongolian gerbils despite pronounced expression of radical-forming enzymes. The aim of the present study was to investigate in vivo whether H. pylori inhibits either one or both of the nitro- and oxyradical formation pathways. Material and methods. Male Mongolian gerbils were infected with two different H. pylori strains, TN2GF4 and SS1. Six months after inoculation, direct measurement of NO and H2O2 was performed in vivo using electrochemical microsensors positioned in close proximity to the gastric mucosa. Results. In the TN2GF4-infected animals the level of NO was significantly lower than that in controls. No significant difference in NO levels was detected between the SS1-infected group and the controls. H2O2 was significantly increased in the SS1 animals compared with that in controls after 6 months. The H2O2 level in the TN2GF4 group did not differ from that in controls. Conclusions. The results indicate that H. pylori infection is associated with strain-dependent functional inhibition of both the NO and oxyradical formation pathways in the gastric mucosa.