Serum levels of nitric oxide and protein oxidation in goats seropositive for Toxoplasma gondii and Neospora caninum

The aim of this study was to assess and analyze the levels of nitric oxide (NO) and advanced oxidation protein products (AOPP) in serum of goats naturally infected by Toxoplasma gondii, Neospora caninum, or concomitantly infected by these two parasites. Thus, it was measured NOx and AOPP levels in twenty (n = 20) sera samples of goats seronegative for T. gondii and N. caninum [negative control group (A)]; while the positive groups were composed by sera of infected animals, twelve (n = 12) seropositive for N. caninum [group B]; eighteen (n = 18) positive for T. gondii [group C]; and thirteen (n = 13) seropositive for N. caninum and T. gondii [group D]. As results, it was observed that animals seropositive for N. caninum and T. gondii (Groups B to D) showed higher serum levels of NOx (P < 0.001; F = 9.5), when compared with seronegative animals. Additionally, it was observed a positive correlation between NOx levels and antibodies titrations for N. caninum (P < 0.01; r = 0.68) and T. gondii (P < 0.05; r = 0.56). AOPP levels were increase in groups C and D (P > 0.05). Interestingly, group B did not show increase in AOPP, what led us to hypothesize that the major protein damage is linked to T. gondii infection. Therefore, our results showed an increased in NOx levels, which was probably related to the immune response, since it is an important inflammatory mediator; and AOPP were increased in groups where there was seropositivity for T. gondii, but not for the group composed only by animals seropositive for N. caninum, allowing us to suggest higher protein damage in toxoplasmosis.