Detrimental effect of nitric oxide on Trypanosoma cruzi and Leishmania major like cells.

The production of nitric oxide (NO) by activated macrophages has been reported to be a non-specific immune-effect mechanism against several parasites. In this work we investigate whether the NO has a detrimental effect on the intracellular parasites of the genus Leishmania and as well as Trypanosoma cruzi. This was assessed by co-cultivating infective Leishmania promastigotes and T. cruzi trypomastigotes and non-infective T. cruzi epimastigotes forms of the parasites in the presence of the NO releasing molecule, S-nitroso-N-acetyl-DL-penicillamine (SNAP). We demonstrate that the NO has the ability to inhibits the growth of all parasites in a concentration dependent manner. In addition, by analysing purified protein and cell homogenates of L. major (promastigotes) and T. cruzi (epimastigotes and trypomastigotes) we demonstrated that the NO may regulate the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity of both parasites.