A shortage of Vitamine-C worsens gastric mucosal dna damages in ammonia administrated guinea pigs

Abstract

Background and Aims : Helicobacter pylori (HP) infection is well known to cause gastric mucosal DNA damages in assoc iation with oxidative stress caused by various free radical s. Previous studies have proposed the importance of anti-oxidant vitamines such as vitamine-C (Vit-C) to protect HP infected gastric mucosa, but there have been few experimental evidence . In the present study , we investigated the efficacy of Vit-C for the protec tion of gas tric mucosal DNA damages induced by ammonia in the guinea pigs. The guinea pig does not have the ability to produce Vit-C by nature similar to the human. Materials and Methods : The model of gastri c mucosal damages induced by ammonia administration and shortage of Vit-C was prepared by administrating water containing 0.1% ammoni a admin istration ad-lib and/or by feeding with autocl aved meal s in which Vit-C was contained only about half of regul ar meals for 2 weeks. Total 20 guinea pigs were divided into 4 group s i.e.; (A) control, (B) autoclaved meals + tap water, (C) 0.1% ammonia + regular meals, (D) 0.1% ammo nia + autoclaved meals. The gastric muc osal DNA damage was histologically evaluated by the following methods; in situ nick translation (ISNT) for the detection of single strand DNA break s, immuno-histochemistry of 8-hydroxydeoxyguanine (8-0HdG), TUNEL for the detect apoptosis, and BrdU incorporation to assess the cell proliferation . The respective labeling index (Ll) was determined as the mean number of the positive cells per 1000 cells in five randomly chosen micro scopic fields at a magnification of x400. Results : There was no significant differences between the group A and B in the LIs of ISNT , 8-0HdG, TUNEL and BrdU incorporation, but the they were significantly higher in the group C compared with the former two groups. The cells positive for ISNT , 8-0HdG and TUNEL increased at the upper part of gastric mucosa in the group C. The guinea pigs in the group D showed the highe st LI value s of every parameters, suggesting that a shortage of Vit-C and ammonia worked synergistically for the deterioration of gastric mucosa becau se the differences in the parameters between groups C and D were statistically significant. Conclusions : The present data demonstrated that a shortage of Vit-C worsens gastric muco sal dam age induced by ammonia administration to guinea pigs. Therefore, antioxidant vitamines might play important role s in the protection of gastric mucosa from HP infection.