Proceedings of the International scientific and practical conference ― Education and Scientific Progress‖ (February 13-15, 2026) / Publisher website: www.naukainfo.com. - Manchester, United Kingdom, 2026. - 206 p.

79 activity, was detected after 0.5, 1, 2, and 3 hours during stress exposure. At the same time, during ulcer healing, the expression of this gene and catalase activity approached control values 24 hours after stress exposure. Thus, we have shown that under the conditions of stress-induced lesions of the gastrointestinal tract of rats, against the background of changes in catalase activity, Gast expression increased, while after the cessation of the stressor, its decrease was observed, which may indicate the involvement of the latter in accelerating the healing of lesions. Keywords: stress; gastric ulcer; RT-qPCR, Gast gene expression. The appearance of ulcers in the gastric mucosa is likely the result of the combined influence of many genetic, cellular, biological, environmental, pharmacological, psychosomatic and neuropsychiatric factors, which, in turn, cause changes in gene expression, initiate increased production of reactive oxygen species and pro-inflammatory cytokines, reducing cellular antioxidant levels; disrupt microvascular blood circulation and bicarbonate secretion, etc. [1]. Despite the numerous data in the literature, today, understanding the clear molecular biological aspects of ulcer formation and healing is relevant and requires further research. It is known that the formation of ulcerative lesions of the gastric mucosa is associated with the development of inflammation, a shift in the balance in the pro- and antioxidant system. The oxidative stress that occurs in this case is accompanied by a disruption of the molecular mechanisms of regulatory processes in the cell and leads to a change in the expression of individual genes [2]. Gastrin (encoded by Gast gene) is an important growth factor for the fundic enterochromaffin-like cells of the gastrointestinal tract, as it regulates the expression of the genes chromogranin A (required for the processing of histamine propeptide), vesicular monoamine transporter 2, and histidine decarboxylase due to binding to the gastrin receptor in these cells [3]. Therefore, the aim of the work was to quantitatively analyze the expression level of Gast gene in the gastric mucosa cells of rats under stress. The study followed international recommendations for animal experiments according to the European Convention. Sexually mature male rats were divided into 2