Two signals are required for nitric oxide production by <i>T. cruzi</i>-infected astrocytes.

<p>(A) Primary astrocyte cell cultures were pretreated or not with IFNγ (10 ng/mL) in the absence or presence of L-NAME, infected using MOI 10:1 and analyzed 24 hours post-infection (p.i.). (B) The graph shows NO production by astrocytes treated or not (NT) with IFNγ and infected or not (NI) with <i>T. cruzi</i>. (C) Representative pictures of IFNγ- pretreated astrocytes infected in the absence or presence of L-NAME. (D) The graph shows the number of intracellular forms of the parasite per 100 cells in the different experimental conditions. Data are presented as mean ± SEM of triplicates. *, <i>p</i> < 0.05, **, <i>p</i> < 0.01 and ***, <i>p</i> < 0.001 comparing IFNγ pretreated astrocytes with NT cells; ^##, <i>p</i> < 0.01 comparing IFNγ pretreated astrocytes in absence or presence of L-NAME.