Release of nitric oxide during experimental trichinellosis in mice.

Nitric oxide (NO) is one of the secretory products of macrophages. Abundant evidence indicates that NO contributes to the host defence functions of these cells. The aim of this study was to test the hypothesis that the induced form of NO synthase (iNOS) may participate in the defence of the host against Trichinella. To investigate whether NO was produced during trichinellosis, we examined NO serum levels as an indicator of NO production by iNOS in mice infected with T. spiralis. A statistically significant increase in the NO serum levels relative to the control group (uninfected animals) was observed during weeks 2-8 post-infection. This increase suggest that iNOS is induced during experimental trichinellosis in mice. In the next stage of our study, we compared the NO synthesis by peritoneal macrophages isolated from infected mice with those from uninfected control. A statistically significant increase in the NO release from macrophages obtained from infected mice was noticed on days 7, 21, 29, 43 and 63 post-infection. These results suggest that infection with T. spiralis induces NO production by macrophages.