Effect of aminoguanidine and L-NAME on MTX-induced villus atrophy in the duodenum (A), jejunum (B), and ileum (C). Bars represent the mean value ± standard error of the mean (SEM) of the villus height in each segment. *p < 0.05 represents statistical differences compared to control group. **p < 0.05 represents statistical differences compared to MTX group treated with saline (-). The number of animals in each group was at least six. Data were analyzed by using analysis of variance (ANOVA) and Bonferroni tests.