The prolonged action of dexamethasone, which exerts a proulcerogenic effect on the stomach, is accompanied by alterations in the glycemic curve and an increase in the neutrophil-to-lymphocyte ratio

Previously, we demonstrated that dexamethasone (Dex) may exert either gastroprotective or proulcerogenic effects, depending on the duration of its action prior to the ulcerogenic stimulus, indomethacin (IM) or stressor. When Dex was administered 1 hour before IM, a gastroprotective effect was observed, but extending the interval to 24 hours transforms its gastroprotective effect into a proulcerogenic one. Suppression of corticosterone production and disturbances in glucose homeostasis may contribute to the development of Dex’s proulcerogenic action (Filaretova et al., 2009, 2020). In the present study, to further clarify the mechanisms underlying the transformation of Dex’s gastroprotective action into proulcerogenic consequences, we examined hematological parameters and glycemic curves after administering Dex 1 hour and 24 hours before IM or before the glucose tolerance test (GTT). Dex (1 mg/kg, i.p.) or its vehicle (control) was administered once, either 1 hour or 24 hours before IM (35 mg/kg, s.c.) in the first experiment, or before the GTT in the second experiment, in rats fasted for 24 hours. Four hours after IM administration, the rats were decapitated, their stomachs were removed to assess the erosion area, and blood samples were collected for complete blood count using automated hematology analyzer (BC-30 Vet) and for corticosterone measurement. In the second experiment, the GTT was performed 1 hour and 24 hours after administration of Dex or its vehicle. Blood glucose levels were measured from the tail vein using a glucometer before glucose loading (baseline level, 0 min; 2 g/kg, i.p.) and 30, 60, 120, and 180 min afterward. The results obtained confirmed the gastroprotective and the pronounced proulcerogenic effect of Dex administered 1 hour and 24 hours before IM, respectively, as well as its inhibition of corticosterone production. The proulcerogenic effect of Dex administered 24 hours beforehand (but not the gastroprotective effect observed when it was given 1 hour prior) was accompanied by pronounced alterations in the glycemic curve compared with the control: an elevation in baseline glucose levels, a reduction in the peak value (maximum glucose level at 30 minutes), a delayed return to baseline, and a marked increase in the neutrophil-to-lymphocyte ratio (NLR) in the blood. In conclusion, the long-lasting action of Dex, which exerts a proulcerogenic effect on the stomach, may lead to alterations in the glycemic curve during the GTT and an increase in the NLR, an indicator of pathological processes. Supported by State Program 47 SP “Scientific and Technological Development of the Russian Federation” (2019-2030), 0134-2019-0001. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.