Figure 5.

Representative examples of iNOS (left) and nitrotyrosine (right) immunohistochemistry of rat jejunum. The jejunum tissue of rats which received subcutaneous MTX presented intense immunostaining for iNOS, both in epithelial cells recovering the villi as well as in the lamina propria cells (G) and in the neutrophils (I; arrow) and other inflammatory cells surrounding and inside the necrotic crypts (I), when compared to the weak immunostaining in the jejunum villous and crypt region of a normal control rat (C and E). Negative control represents a sample of the jejunum where the antibody for iNOS was replaced by 5% PBS/BSA and no immunostaining was detected (A). The jejunum tissue of rats which received subcutaneous MTX presented intense immunostaining for nitrotyrosine in the lamina propria cells (F; yellow arrow), when compared to the weak immunostaining in the jejunum lamina propria and crypt region of a normal control rat (D). The treatment with aminoguanidine (H) or L-NAME (J) considerably reduced the immunostaining for nitrotyrosine. Negative control represents a sample of the jejunum where the antibody nitrotyrosine was replaced by 5% PBS/BSA and no immunostaining was detected (B). Magnification 400x. Scale bar lengths 10 μm. The yellow arrow indicate nitrotyrosine immunostained cells.