We studied the effect of collagen fragments (PGP and AcPGP) on serum content of epinephrine, corticosterone, and IL-1β in rats subjected to water-immersion stress. The degree of local inflammation accompanying ulceration was assessed by IL-1β production by ln. gastricus caudalis cells. In 1 h, the sharp increase in hormone concentrations in the blood of stressed animals reflected the high stress intensity. Intranasal administration of PGP reduced the area of stress-induced ulcers by 63%, prevented the increase in the levels of stress hormones and the main proinflammatory cytokine in rat blood. The concentrations of IL-1β in cell culture from regional lymph node of experimental animals returned to normal in 24 and 48 h after the stress. Acetylation of PGP prevents with gastroprotection, but does not abrogate other properties of the peptide. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.