Relationship between oxidative stress and pathological findings in abomasum of infected lambs by Haemonchus contortus

The aim of this study was to evaluate the nitric oxide (NO) levels, and oxidative and antioxidant markers of lambs experimentally and naturally infected by Haemonchus contortus, and its relation to lesions in the abomasum. For experimental study, a total of 14 healthy lambs were divided into two groups with seven animals each. Group A represented the uninfected animals (control), and Group B was formed by infected animals with 15,000 larvae of H. contortus. Blood was collected on days 15, 45, and 75 post-infection (PI) to obtain serum for biochemical analysis: lactate dehydrogenase (LDH), nitrite/nitrate (NOx), advanced oxidation protein products (AOPP), and ferric reducing ability of plasma (FRAP). Parasitological stool examination (eggs per gram of feces--EPG) was performed on days 15, 45, and 75 PI to verify the evolution of the infection. On day 15 PI EPG was negative, but on days 45 and 75 PI the EPG was positive for animals from Group B. In the three periods evaluated it was observed an increase of LDH levels in serum of lambs infected with gastrointestinal nematodes, but on the other hand NOx levels were reduced on the same periods in infected animals. The AOPP and FRAP levels did not differ between groups on days 15 and 45 PI, but increased significantly on day 75 PI in infected lambs. The same variables were studied in 10 lambs naturally infected with helminths, where more than 97% corresponded to H. contortus (hematocrit and EPG values were 18.8 ± 2.5% and 7120 ± 2940, respectively). Similar to the experimental study, the levels of NOx reduced, and the levels of LDH, FRAP, and AOPP increased in serum of this animal associated inflammatory infiltrate in the mucosa of the abomasum. Therefore, during the infection by H. contortus it was observed alterations in oxidative markers, indicators of cell lesion confirmed by histological examination of the abomasum, and consequently there were changes in antioxidant levels, with the purpose of cell protection. We also conclude that helminth infection interferes with the nitric oxide metabolism.