Effect of aminoguanidine and L-NAME on cell death and proliferation in the jejunum segments. An increased number of TUNEL positive cells is observed in jejunum of rats submitted to MTX-induced intestinal mucositis when compared to the jejunum of a normal control rat. The treatment with aminoguanidine or L-NAME significantly reduced the number of TUNEL positive cells in the lamina propria (A). The treatment with MTX result in a significant decrease in the number of Ki67 positive cells compared to control animals. Aminoguanidine administration, but not L-NAME, result in a significant increase in the number of Ki67 positive cells compared to the MTX group (B). Bars represent the mean value ± standard error of the mean (SEM) of the tunel positive cells (A) and Ki67 positive cells (B). The TUNEL and Ki67 positive cells were counted (10 fields per slide; x1000) in order to perform a statistical comparison. *p < 0.05 represents statistical differences compared to control group. **p < 0.05 represents statistical differences compared to MTX group (-). Data were analyzed by using analysis of variance (ANOVA) and Bonferroni tests.