2125
Severe gastric ulcers accompanied with increased ulcerogenic factors , including gastric acid back - diffusion , histamine release , LPO generation and luminal hemoglobin content were also observed in these rats .
 ulcers, histamine, luminal
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 ulcers, histamine, luminal