nitroarginine and Chagas-Disease

Chagas' disease, caused by the protozoan parasite, Trypanosoma cruzi, is associated with gastrointestinal abnormalities. Since nitric oxide (NO) has been shown to be a factor influencing intestinal function we evaluated the distributions and activities of the NO synthase (NOS) isoforms, in the gut of mice infected with T. cruzi. Ca2+-dependent (NOS1/NOS3) activity was decreased, whereas Ca2+-independent (NOS2) activity was increased in infected mice. NOS2-immunoreactivity was demonstrated in cells within the muscle layers and epithelium in infected mice and NOS1 immunoreactivity was seen in nerve structures. These data indicate that alterations in the NO-system may be important in the pathogenesis of the gastrointestinal manifestations in Chagas' disease.

Topics: Animals; Arginine; Calcium; Chagas Disease; Citrulline; Colon; Digestive System; Enzyme Inhibitors; Epithelial Cells; Esophagus; Female; Ileum; Intestinal Mucosa; Isoenzymes; Male; Mice; Mice, Inbred C3H; Muscle, Smooth; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Nitroarginine; Stomach; Trypanosoma cruzi

Our aim was to investigate the possible involvement of nitric oxide (NO) in peripheral denervation during the acute phase of murine experimental Trypanosoma cruzi infection. Wistar male rats were infected with the Y strain of T. cruzi. One group of animals was also treated with the NO synthase inhibitor N-nitro-l-arginine. A group of uninfected animals was the control. At the 18th day of infection the animals were sacrificed. Quantification of neurons in the colon and heart and tissue parasitism in the heart was performed. Serum concentration of nitrate was measured and a histochemical technique for assessing NADPH-diaphorase activity in the colon was also performed. The infected animals presented a statistically significant decrease in the number of peripheral neurons in the colon and heart and a 2-fold increase in serum NO(3) concentration compared with controls. The animals treated with N-nitro-l-arginine showed almost an absence of NO(3) concentration in the serum and did not show loss of neurons compared with controls. These treated animals displayed a 15-fold increase in tissue parasitism compared with nontreated infected animals. The NADPH-diaphorase activity was much more intense in the muscle layers of the colon of the infected animals than in those of the controls. Taken together, these data suggest that NO is involved in the peripheral denervation observed in the acute phase of experimental T. cruzi infection.

Topics: Acute Disease; Animals; Autonomic Nervous System; Chagas Disease; Colon; Enzyme Inhibitors; Heart Atria; Male; Muscle, Smooth; Myenteric Plexus; Myocardium; NADPH Dehydrogenase; Neurons; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Rats; Rats, Wistar

Nitric oxide (NO) production by peritoneal macrophages was evaluated in Calomys callosus and Swiss mice during the course of infection with two strains of Trypanosoma cruzi. In C. callosus, no NO production was detected throughout the period of observation in animals infected with either parasite strain, except for a very low amount measured on day 40 in animals infected with strain M226 and on the 28th day in animals infected with strain F after in vitro stimulation with interferon gamma (IFN-gamma). Macrophages of Swiss mice produced large amounts of NO, the highest values being observed on the 40th day in mice infected with the F strain. Induced nitrogen oxide synthase (iNOS) was not detected in macrophages of infected C. callosus but was detected in mice. The i.p. inoculation of thioglycolate, bacille Calmette-Guérin (BCG) and periodate, nonspecific macrophage activators, did not induce NO production in C. callosus, but high levels were observed in Swiss mice after secondary in vitro IFN-gamma plus lipopolysaccharide (LPS) stimulation. However, H2O2 release was induced in macrophages stimulated with phorbol myristate acetate (PMA) in both experimental models. Serum NOx(NO2 + NO3) levels were low in C. callosus infected with strain M226, which was originally isolated from this animal species. Strain-F-infected animals had higher serum NOx levels in the initial period of infection, which dropped to noninfected control values on the 40th day. In Swiss mice, both strains induced the production of higher levels of NOx throughout the period of observation, with the increase being more pronounced in mice infected with the F strain. Daily treatment of F-strain-infected C. callosus with the arginine analogue L-nitro-arginine drastically reduced NOx levels, with no influence on parasitemia or mortality being observed. The results obtained suggest that C. callosus shows a distinct behavior with regard to resistance to T. cruzi infection.

Topics: Animals; Arvicolinae; Cells, Cultured; Chagas Disease; Hydrogen Peroxide; Immunity, Innate; Macrophages, Peritoneal; Mice; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitrites; Nitroarginine; Parasitemia; Trypanosoma cruzi

This study was carried out to determine the role of reactive nitrogen intermediates in Trypanosoma cruzi infection. In vitro, splenocytes obtained during the acute phase of infection produced elevated amounts of nitric oxide (NO) that were correlated with the resistance or susceptibility of the animals. In vivo, the levels of NO2- plus NO3- in plasma during the later phase of infection were higher in C57BL/6 mice than in BALBL/c mice. The treatment of infected C57BL/6 mice with inhibitors of NO synthase increased parasitemia and mortality. Finally, we found that the NO donor drug S-nitroso-acetyl-penicillamine is able to kill trypomastigotes in vitro in the absence of any other cells, suggesting a direct NO-mediated killing of T. cruzi.

Topics: Amino Acid Oxidoreductases; Animals; Arginine; Chagas Disease; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitrites; Nitroarginine; omega-N-Methylarginine; Spleen; Trypanosoma cruzi