I found one protocol for establishing acetic acid induced chronic ulcer model in rat. The attached papers are good resources for further reading which I believe will help you developing the protocol.
Okabe S, Amagase K / An overview of acetic acid ulcer models. The history and state of the art of peptic ulcer re-search // Biol. Pharm. Bull. 2005;28(8):1321-1341
I dare to recommend my own review article on this matter here
https://www.researchgate.net/publication/258821777_Ulcer_disease_the_state_of_art as well. I would be highly obliged if you post your opinion about it.
Ulceration in the rats was induced with a single dose of indomethacin (30 mg/kg BW., oral gavage) dissolved in DW. The rats were deprived of food but had free access to tap water 24 h before ulcer induction
the ulcer in rat is induced by various methods , these are
ethanol induced ulcer, acetic acid induced ulcer , stress induced ulcer, pylorus ligation induced ulcer, indomethacin induced ulcer, aspirin induced ulcer, naproxen induced ulcer. The models are vary according to the severity like acute, chronic or subacute. You can use acetic acid induced ulcer model, with that you can give long treatment to rat by giving the indomethacin daily for 20 days it will produce chronic unhealed ulcer. also you can infect that ulcer with H-pylori to mimic the ulcer condition which usually occur in human being after H-pylori infection.
I have read the article and would like both to say thanks again for the colleague uploaded it and to ask a couple of more questions to advanced researchers of the experimental peptic ulcer disease:
1) The author did not explain why the ulcer developing after the cysteamine hydrochloride treatment displayed itself as a quite local defect with sharp borders, not as multiple or irregular ulceration. What is your opinion?
2) Judging by available literature, the cysteamine does not produce gastroduodenal ulcerations in humans, does it not?
Here is one of his latest reprints on this which should also cite all of his former work.
Also, as I mentioned, if you are interested in the restraint-induced ulcer model, please see my stress publications in Res. Gate.
New mechanistic explanation for the localization of ulcers in the rat duodenum: role of iron and selective uptake of cysteamine. Khomenko T, Kolodney J, Pinto JT, McLaren GD, Deng X, Chen L, Tolstanova G, Paunovic B, Krasnikov BF, Hoa N, Cooper AJ, Szabo S.