Figure 2. Immunohistochemical localization of nitrotyrosine and poly (ADP-ribose) polymerase formation. No staining for nitrotyrosine (A) and poly (ADP-ribose) polymerase (D) was observed in sham gingivomucosal tissue, while positive staining was observed after ligature (B,E). In gingivomucosal tissue of aminoguanidine-treated rats (100 mg/kg i.p., daily for 8 days), no positive staining was observed both for nitrotyrosine (C) and poly (ADP-ribose) polymerase (F). Original magnification: x125. Fig. is representative of at least 3 experiments performed on different experimental days.