Effects of Insulin and Metformin on Indomethacin-Induced Gastric Injury in Streptozotocin-Induced Diabetic and Non-Diabetic Rats

Abstract

Diabetes is one of the major health issues globally. Diabetic gastropathy is a well-documented phenomenon. Current treatments for diabetes and its complications have proven to be unsatisfactory. Currently, standard insulin therapy alone is still not the best treatment for type 1 diabetes (T1D). Metformin, besides use in type 2 diabetes (T2D), might be considered for a treatment of T1D. This study analyzed the effects of insulin and metformin on the gastric injury caused by indomethacin in the streptozotocin (STZ)-induced diabetic (T1D) and control non-diabetic rats. STZ (60 mg/kg, i.p.) was administered once 2 weeks before indomethacin (IM, 35 mg/kg, s.c.) in rats. Control non-diabetic rats were injected with STZ vehicle. The development of diabetes was assessed by blood glucose levels, changes in the rats' body weight, and water consumption. Insulin (2 IU/kg, i.p.) and metformin (100 mg/kg, orally) were administered daily, separately to different groups of rats, starting from the 8th day after the administration of STZ, for 7 days. After the last administration of the drugs, the rats were fasted for 22 hours before IM administration. Four hours after IM administration, the rats were decapitated, the stomachs were removed to estimate the erosion area; the adrenal glands and thymus were removed to estimate their weight, and trunk blood was collected to test the corticosterone and glucose levels. During the first week after STZ administration characteristic signs of diabetes developed: increased blood glucose, increased water consumption, and slower body weight gain. A week after daily insulin administration (on the 14th day), the glucose level in diabetic rats was lower compared to the corresponding level on the 7th day (before insulin administration). At the same time, the glucose levels before (day 7) and after administration (day 14) of metformin did not differ significantly. The development of STZ-induced diabetes led to a pronounced worsening of the ulcerogenic effect of IM: the average area of erosions caused by IM was increased significantly compared to that in control non-diabetic rats. Administration of both insulin and metformin for 7 days prevented the ulcer-promoting effect of STZ. In addition, insulin, but not metformin, also had a gastroprotective effect in non-diabetic rats: it reduced the average area of IM-induced erosions. The development of STZ-induced diabetes was accompanied by the manifestation of signs of chronic stress: an increase in plasma corticosterone level, an increase in the relative weight of the adrenal glands, and a decrease in the relative weight of the thymus. Daily administration of insulin for 7 days, but not metformin, resulted in a decrease in corticosterone levels on day 14 in diabetic rats. In conclusion, both insulin and metformin effectively prevented the pronounced ulcer-promoting effect of STZ-induced diabetes on the gastric injury caused by indomethacin in rats. However, only insulin, but not metformin, also exerted gastroprotective effect against IM-induced injury in non-diabetic rats under our experimental conditions. Grant for the creation and development of the world-class scientific center "Pavlov Center “Integrative Physiology - to medicine, high-tech healthcare and technologies of stress resistance” and with financial support from the Ministry of Education and Science of the Russian Federation (No 075-15-2022-303 от 21.04.2022.). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.